international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 54-57 ijeca-issn: 2543-3717. december 2019 page 54 effect of heat flow via glazing on the productivity of a solar still abderrahmane khechekhouche 1* , zied driss 2 , benjamin durakovic 3 1 applied mathematical and sciences unit (ams), lab of labthop, university of el-oued, algeria 2 laboratory of electromechanical systems (lasem), enis, university of sfax, tunisia 3international university of sarajevo, 71210 ilidža, bosnia and herzegovina email*: abder03@hotmail.com abstract – in many parts of the world, particularly in the greater maghreb, desalination of water by solar energy is practiced with incredible abundance. drinking water shortage has become a major problem. improving the efficiency of solar distillers in several laboratories around the world is still one of the major concerns of research topics. in this work we want to show that the heat flow through the glazing can also be considered as an index on the productivity of pure water from a conventional solar still. keywords: solar energy; solar distiller; distilled water; drinking water. received: 26/11/2019 – accepted: 25/12/2019 i. introduction the technique of water desalination in several countries is very developed, but each technique used in this field has its advantages and disadvantages [1-3]. solar distillation is one of the simplest and most profitable purification techniques compared to other distillation methods because it uses a green and renewable energy source, it is solar energy. solar radiation and the main parameter in this technique and any variation of the solar intensity directly influencing the productivity of pure water in other words, the variation of the seasons has a remarkable influence on this type of distillation and this has been proven by an experimental study is made in the south-east of algeria [4, 5]. the performance of this procedure is relatively low, but several research studies around the world have aimed at improving the production of solar stills using several techniques. studies have focused on heating the water to be distilled, have used storage materials [6, 7], others have used a collector and a solar concentrator. even solar pv has been used to increase water temperature in order to speed up evaporation [8, 9]. nanofluid technology has touched the field of solar distillation and this through experimental studies done at the levels of several research laboratories [10]. the glazing of the distiller (condenser) plays a big role in solar distillation [11]. the temperature between the glazing and the water to be distilled is a good indicator of the production of pure water. each time the temperature difference increases this will be followed by an increase in production. this indicator is the temperature gradient [12]. in this work we show that the heat transfer through the glazing in a solar still can be considered as a new indicator on the production of pure water. ii. method and discussion ii.1. description of the solar distiller figure 1 shows a solar still, this device which can be easily designed by equipment available in the markets. it is designed essentially from a wood box, a glass cover and a pcv tube. figure.1. single slope solar distiller mailto:abder03@hotmail.com abder image placée abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2019 page 55 ii.2. thermocouples locations temperature measurements are made by means of five thermocouples positioned as shown in figure 2. • temperature of the inside face of the glazing. • temperature of the outside face of the glazing. • ambient temperature. figure.2. locations of the used thermocouples ii.3. characterization of glass glasses constitute an extremely varied set of products whose properties are innumerable. these depend mainly on the composition, especially thermal. the thermal conductivity of the glass: 1 w/(m k) glass thickness: 0.004 m glass surface: 1/4 m² specific heat cp: 0.8 j/g/k ii.4. meteorological conditions of the experiments an experiment was carried out at the university of el-oued (south-eastern algeria). the experiment was made on may 5, 2018 during a clear and calm windless day. table 1 shows the experimental weather conditions. table 1 meteorological conditions (summer may 5, 2018) sunrise sunset ambient temperature atmospheric pressure 05:41 am 07:19 pm 26-35°c 1013 mb iii. result and discussion there are many meteorological factors such as solar radiation; the ambient temperature influences the operation of the distiller. the transfer of heat through the glass cover is a remarkable indicator on the productivity of the solar still. the results obtained are illustrated in the following figures. iii.1. solar radiation evolution figure 4 shows the solar radiation evolution in w/m 2 during the day time (in hours). the radiation increases gradually until reaching a maximum value between 11:00h and 14:00h. solar radiation is the key parameter in solar distillation. figure.4. evolution of solar radiation iii.2. ambient temperature figure 5 shows the evolution of the ambient temperature as a function of time. the ambient temperature is growing until reaching a maximum value of 31 ° c and this at 15:00h. the ambient temperature is also a factor influencing the productivity of pure water from a solar still. figure.5. evolution of ambient temperature iii.3. variation in the temperature difference at the edge of the glass cover figure 6 shows the variation in the temperature difference at the edge of the glass cover of the solar still. this difference in temperature increases over time as well as productivity. this difference is maximum at 14:00h and the productivity is also maximum with 108.2 ml as shown in figure 7. abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2019 page 56 figure.6. evolution of the temperature difference at the edge of the glass cover iii.4. productivity of pure water figure 7 shows the evolution of the pure water production as a function of time. the productivity is maximum at 14:00h and notes that the temperature difference between the two faces of the glazing is also maximum at 14:00h so we can say that there is a relationship between the outgoing flow via the glazing and the productivity of the solar still. figure.7. productivity of distilled water iv. conclusion in general, the temperature gradient is a good indicator to follow the productivity of pure water from a solar still, but we can say that the flow leaving via the glazing of a still may also be a productivity indicator. so we can say:  the transfer of heat through the glass cover of a solar still gives a very remarkable indication of the productivity of the distilled water.  this difference is maximum at 14:00 with (∆t=31° c) and the productivity is also maximum with 108.2 ml reference [1] hasan f. khazaal, haider th. salim alrikabi, faisal theyab abed, salah ibrahim kadhm. water desalination and purification using desalination units powered by solar panels. vol 7, n° 3, 2019. periodicals of engineering and natural sciences. [2] n. ghaffour, j. bundschuh, h. mahmoudi, m.f.a. goosen. renewable energy-driven desalination technologies: a comprehensive review on challenges and potential applications of integrated systems, desalination, 356, 94-114 (2015). [3] k. choon ng, k. thu, s. jin oh, l. ang, m. wakil shahzad, a. bin ismail, recent developments in thermally-driven seawater desalination: energy efficiency improvement by hybridization of the med and ad cycles, desalination, 356; 255-270 (2015). [4] a. khechekhouche, a. boukhari, z. driss, n. benhissen, seasonal effect on solar distillation in the el-oued region of south-east algeria, international of energetica, 2, 1, 42-45 (2017). [5] abderrahmane khechekhouche, boubaker benhaoua, abd elnaby kabeel. traditional solar distiller improvement by a single external refractor under the climatic conditions of the el oued region, algeria. desalination and water treatment. (in press) 2019. [6] abderrahmane khechekhouche, boubaker benhaoua, abd elnaby kabeel, mohammed el hadi attia, wael m. el-maghlany. improvement of solar distiller productivity by a black metallic plate of zinc as a thermal storage material. journal of testing and evaluation, vol 49, no 2, (in press), 2019. [7] a.e. kabeel, mohamed abdelgaied, amr essa, "enhancing the performance of single basin solar still using high thermal conductivity sensible storage materials". journal of cleaner production, vol 183, 2018, pp. 20-25. [8] a.m. manokar, m. vimala, r. sathyamurthy, a. e. kabeel, d. prince winston, ali j. chamkha. “enhancement of potable water production from an inclined photovoltaic panel absorber solar still by integrating with flat-plate collector”. environ dev sustain (2019) [9] gurukarthik babu balachandran, prince winston, david aravind, bhaskar panayilvedu vijayakumar, abd elnaby kabeel, muthu manokar athikesavan, ravishankar sathyamurthy, "enhancement of pv/tintegrated single slope solar desalination still productivity using water film cooling and hybrid composite insulation", environ sci pollut res (2019). [10] hitesh panchal, ravishankar sathyamurthy, a. e. kabeel, s. a. el-agouz, dsilva rufus, t. abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2019 page 57 arunkumar, a. muthu manokar, d. prince winston, atul sharma, nishant thakar, kishor kumar sadasivuni, “annual performance analysis of adding different nanofluids in stepped solar still”, journal of thermal analysis and calorimetry, vol. 138, no 5, 2019, pp. 3175–3182. [11] abderrahmane khechekhouche, benhaoua boubaker, mruthu manokar, ravishankar sathyamurthy, abd elnaby kabeel. “exploitation of an insulated air chamber as a glazed cover of a conventional solar still”. heat transfer asian research. vol 48, issue 5, 2019, pp 1563-1574. [12] a. khechekhouche, b. ben haoua, z. driss, solar distillation between a simple and doubleglazing, revue de mécanique. vol 2, no 2. 2017 i. introduction ii. method and discussion iii. result and discussion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 32-36 ijeca-issn: 2543-3717. december 2020 page 32 induction machines diagnosis by the time's harmonics abderrrahim allal *1 , abderrahmane khechekhouche 1 , zied driss 2 1 technology faculty, university of el-oued, algeria 2 laboratory of electromechanical systems (lasem), enis, university of sfax, tunisia email * : allalabderrahim@yahoo.fr abstract – the induction motor is currently becoming the key element of most industrial equipment. despite these advantages, a certain number of constraints of very different natures can affect the lifetime of this machine, causing considerable economic losses. this work is the study experimental of defects for an asynchronous machine (with and without defect). after having described the main defects that can occur on these. in this study, we propose a method called induction machines diagnosis by the time's harmonics. this technique is based to study the influence of a defect of short-circuiting on the studied induction motor, we will find the rank of the harmonic of the most influenced by the number of the rank default. this study will find the diagnostic index of induction motor with stator default using the time harmonics. the results obtained show that the 3rd order time-harmonic is very sensitive compared to the other harmonics. keywords: induction motor, spectral analysis, stator fault, diagnosis, short circuit, time harmonics. received: 25/10/2020 – accepted: 01/12/2020 i. introduction induction motors are electric motors very much abandoned in the markets and they are widely used in all industrial applications; because of their simplicity, reliability, robustness and above all because of the possibility of adjusting the speed of rotation by the availability of power converters [1]. it is well known that the detection and diagnosis of failures in its engines make it possible to move from preventive maintenance to predictive maintenance of electrical machines during scheduled downtimes while avoiding unscheduled shutdowns [2]. for problem detection and fault diagnosis, it is very necessary to know whether a fault affects the system via online measurements and this has been done by a group of researchers [3]. according to specialists in the field of diagnostics, it is not only necessary to detect the defect, but it is also necessary to locate it and find its origin [4, 5]. many methods of induction motor fault detection are published and offered by research in journals conducted by diagnostic laboratories. they proposed an in-line induction motor diagnostic system based on motor current signature analysis (mcsa) with various advanced signal processing algorithms. over the past decades; there is much work in progress to find the best diagnostic technique [6, 7]. another study proposes a more advanced signal processing method based on the parkhilbert "park-hilbert" transformation (pvsmp-h). this research group used "fleet vector square modulus" (pvsm) and line current to obtain "motor square current signature analysis" (mscsa) [8-11]. another advanced technique called the "hilbert park vector product approach" (hpvpa) which is inspired. they used "park's vector product approach (pvpa) for the diagnosis of induction motors" which is based on an improved combination of the hilbert transform and park's [12-17]. in this study, we propose a method called induction machines diagnosis by the time harmonics. this technique is based to study the influence of a defect of short-circuiting on the studied induction motor, we will find the rank of the harmonic of the most influenced by the number of the rank fault. but in the real case, it is abderrahim allal et al ijeca-issn: 2543-3717. december 2020 page 33 very difficult to find a perfectly balanced power source, if not impossible, a well-centred winding as well as an ideally symmetrical geometry. an imbalance in the voltages will cause the creation of negative sequence (reverse field) currents in the stator windings which give rise to other harmonic frequencies in the stator windings. this gives us, finally, harmonics not only multiple of 3 but odd such as fs, 3fs, 5fs, 9fs,…. we obtain time harmonics whether for healthy or faulty operation. ii. method and experience ii.1. materials used two identical induction motors used, in the electrical engineering laboratory of el oued university, is threephase, 3 kw, 50 hz, 2 poles, squirrel-cage with 28 bars at the rotor and 360 turns in series per phase : 1) – healthy motor runs at full load (100%) 2) – motor with stator faults runs at full load (100%) with two cases short circuits between 5% of turns figure 1 shows two induction motors well prepared for the experimental tests the first is a healthy motor to give healthy spectral analysis the second is a motor with short circuit sockets to create artificial stator faults. figure 1. three-phase induction motors (3kw ) figure 2 shows the current sensor of a phase, with a calibre of 10 amps to take the image of the current to be processed in the pasco 750 interface. figure 2. current sensor figure 3 shows the pasco 750 interface processes the image of the current extracted from the current sensor to visualize the spectrum through the software installed in the computer. figure 3. interface pasco 750 (1. model no. ci-7599. 2.transformer for power supply. 3usb) ii.2. description of the signal extraction tool figure 4 shows the experiment setup which gives the data acquisition of the motor current signal. the various faults which affect the im will give rise to an influence on the signals coming from this im by the modulation of their amplitudes at the characteristic frequencies of these faults. it is necessary to take care with a very satisfactory resolution to make appear the various additional lines the sidebands to be able to easily analyze and diagnose our me. as an example, we are going to do tests with our experimental bench which has an im with stator fault at full load. for this, we will choose an acquisition time of ta ≈ 10 seconds, which implies that the total number of samples (ne = 20000): the number of samples by second of our results is therefore equal  ne = ne / ta = 2000 samples/second. abderrahim allal et al ijeca-issn: 2543-3717. december 2020 page 34 figure 4. experiment setup iii. results and discussion iii.1. case of a healthy machine figure 5 shows the experimental spectrum of the stator current with its harmonics (healthy state). it is shown also how the evolution of time harmonics, their amplitudes and their specific frequencies which are multiples of 3 compared to the supply frequency with the healthy motor operating at no-load. figure 5. experimental spectrum of the stator current with its harmonics (healthy state) figure 6 shows the evolution of the motor current in the time domain (2.7 amperes) which is non-sinusoidal due to the imbalance of the motor and the non-symmetry of the materials of its manufacture. figure 6. stator current healthy case. iii.2. case of a machine with stator short-circuit figure 7 shows the experimental fft of the stator current with its time harmonics (with stator short-circuits 5% of turns). we notice the increase of time harmonics in the case of stator fault with 5 percent of turns in phase a. figure 7. experimental fft of the stator current with its time harmonics (with stator short-circuits 5% of turns) figure 8 shows the evolution of the motor current in the time domain (3 amperes) which further distorted the sinusoidal shape of the currents due to the stator fault. abderrahim allal et al ijeca-issn: 2543-3717. december 2020 page 35 figure 8. stator current faulty case. figure 9 shows the experimental spectrum of stator current with its harmonics. the experimental spectral analysis of the stator current shows that the 3rd order time-harmonic is very sensitive compared to the other harmonics. the time harmonics are given, generally, by the following formula: (1) where n: is the time-harmonic order. is a power frequency (50 hz). 1,3,5…. figure 9. experimental spectrum of stator current with its harmonics iv. conclusion this experimental study was carried out in the electric freezing laboratory of the university of el-oued. this study is focused on the stator faults of the electric induction motor, such as what we have done (short circuit between the turns). the results obtained show that there is a remarkable increase in the amplitudes of the time harmonics but there is also a difference between these amplitudes as a function of their sensitivity. the experimental spectral analysis of the stator current shows that the time harmonics of order 3 are more sensitive than the other time harmonics of order 2 and order 1 influenced. for this, we can consider that the time harmonics of order 3 are the diagnostic index of asynchronous stator motors. references [1] m. blodt, p. granjon, b. raison, g. rostaing, “models for bearing damage detection in induction motors using stator current monitoring”, ieee trans. ind. electron, vol. 55, (no. 4), 2008, p 18131822. [2] m. boucherma, m. y. kaikaa, a. khezzar, park model of squirrel cage induction machine including space harmonics effect, journal of electrical engineering, vol 57 (no.4), 2006, p 193-199. [3] e. lughofer, e. p. klement, “model-based fault detection in multi-sensor measurement systems, technical report full/tr/0303”, johannes kepler university linz, austria. [4] s. ben salem, k. bacha, a. chaari, “support vector machine-based decision for induction motor fault diagnosis using air-gap torque frequency response”, international journal of computer applications, vol 38, no.5, 2012, pp. 27-33. [5] s. ben salem, k. bacha, a. chaari, “support vector machine-based decision for mechanical fault condition monitoring in induction motor using an advanced hilbertpark transform”, isa trans., vol 51, no.5, 2012, pp. 566– 572. [6] t. sribovornmongkol, “evaluation of motor online diagnosis by fem simulations”, thesis, royal institute of technology stockholm, sweden, 2006. [7] k. bacha, s. ben salem, a. chaari, “an improved combination of hilbert and park transforms for fault detection and identification in three-phase induction motors”, electrical power and energy systems, vol 43 no.1, 2012, pp.1006–1016. [8] mohamed sahraoui, adel ghoggal, salim guedidi, salah eddine zouzou, “detection of inter-turn short-circuit in induction motors using park–hilbert method”, international journal of system assurance engineering and management, vol 5, no.3, 2014, pp. 337-351. [9] m. sahraoui, “etude comparative des méthodes de diagnostic des machines asynchronies (comparative study of the methods of diagnosis in the asynchronous machines)”, thesis for the degree of doctor of science, biskra university, algeria, 2010. [10] v. f. pires, m. kadivonga, j. f. martins, a.j. pires, “motor square current signature analysis for induction motor rotor diagnosis”, measurement, vol 46, no.2, abderrahim allal et al ijeca-issn: 2543-3717. december 2020 page 36 2013, pp. 942–948. [11] a. allal, b. chetate, “high sensitivity detection of the stator short-circuit faults in induction motor using hilbert park's vector product”, j. fundam. appl. sci., vol 11, no 2, 2019, pp. 994-1022. [12] m. sahraoui, s. e. zouzou, a. ghoggal, s. guedidi, “a new method to detect inter-turn shortcircuit in induction motors, 19th ed., international conference on electrical machine (icem,2010 -rome, italy), ieee, 2010, pp. 1-6. [13] s. e. zouzou, m. sahraoui, a. ghoggal, s. guedidi, “detection of inter-turn short-circuit and broken rotor bars in induction motors using the partial relative indexes: application on the mcsa”, 19nd ed., international conference on electrical machine (icem,2010), rome, italy, ieee, 2010, pp. 1-6. [14] a. allal, b. chetate, d. benattous, “the instantaneous power approach for rotor cage fault diagnosis in induction motor”, 6 th symposium on hydrocarbons and chemistry ishc6, 2012, zeralda, algeria. [15] i. chouidira, k. djalal eddine, h. benguesmia, “detection and diagnosis faults in machine asynchronous based on single processing”, international journal of energetica (ijeca), vol 4, no. 1. 2019, pp. 11–16. [16] a. allal, b. chetate, “ a new and best approach for early detection of rotor and stator faults in induction motors coupled to variable loads”, frontiers in energy, vol 10, no.2, 2016, pp. 176-191. [17] a. allal, “nouvelles méthodes et techniques de diagnostic des machines asynchronous à rotor en cage d'écureuil (new methods and diagnostic techniques asynchronous machines of squirrel cage rotor”, thesis for the degree of doctor of science, boumerdes university, algeria, 2017. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 18-22 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 18 experimental study of temperature effects on the photovoltaic solar panels performances in algerian desert lamine medekhel 1 , kamel srairi 1 , chouaib labiod 2* 1 laboratory of energy systems modeling(lmse), university of biskra, algeria 2 technology faculty, university of el oued, algeria * corresponding author e-mail: labiod.chouaib@gmail.com abstract – photovoltaic panels are operated in the algerian desert areas under high temperatures, especially, in the summer, when the temperature may be reached 70°c on the panel's surface. the high temperature has a significant negative impact on the photovoltaic panels performance. in this paper, an experimental study to track the effects of temperature on the photovoltaic panels performances in different situations has been realized. the obtained results approve the importance of the temperature effects on the electrical power of the photovoltaic panel. the temperature increases lead to decreases in the performance of the panel, where an output power that does not exceed 52% of the nominal power at a high temperature. keywords: photovoltaic (pv) systems, maximal power (pmax), short-circuit current (isc), opencircuit voltage (voc). received: 22/04/2022 – revised 05/06/2022 – accepted: 17/06/2022 i. introduction in light of the rapid rise in population growth rates, the increasing demand for electricity around the world, the alarming increase in carbon emissions leading to global warming, the instability of the global oil and gas market, the constant prices fluctuation and the risks of political unrest and natural disasters such as the corona pandemic. many countries have been forced to reconsider their use of traditional energy sources and the tendency to invest in renewable energy and its equipment [1-3]; this will reduce carbon emissions and ensure energy security, especially, since renewable energies are formed in several forms, like the sun, the water, the wind, ...etc. the solar energy source is among the most powerful sources of renewable energy and it has, recently, witnessed a decrease in its production costs in a way that qualifies them to compete with oil and gas, as photovoltaic energy has become very popular among renewable energy sources [4]. this is since the main fossil fuel resources are being depleted continuously compared to solar energy generation which is a clean source and does not contribute to the carbon footprint on the environment [5]. in addition to having one of the most significant sun fields in the world, with more than 3500 hours of brightness annually, algeria's climate is very conducive to the growth of solar energy [6,7]. an excessive rise in temperature affects the photovoltaic panels (pv) performance, as the increase in temperature [8,9]. with the increase in temperature, the current increases slightly and the voltage decreases more [10], therefore, productivity and efficiency decrease [11,12]. several recent studies have proved the high negative impact of high temperatures on solar cell performances [13]. in this paper, our proposed experimental research work is carried out to test the performances of a monol. medekhel et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 18-22 page 19 crystalline solar panel under different temperatures for different seasons in the algerian desert of the oued souf region. the object of this work aims at temperature negative effects on the efficiency of the photovoltaic panel, especially in summer when the temperature exceeds 50 degrees in the shade and 70 °c in the sun at full summer. ii. material and method the band gap of solar cells is reduced when temperature rises, which has an impact on electrical solar cell parameters such as maximum power (pmax), shortcircuit current (isc), and open-circuit voltage (voc) [14– 17]. the maximum power, short-circuit current, and opencircuit voltage is the three key electrical characteristics that directly affect how much energy a solar panel can produce. the general objective of this study is to track the influence of temperature on the energy production of a photovoltaic panel at different times of the year at el oued souf algerian south region. the study was carried out on different days of the year taking into account the same irradiance in all the experiments equal to: e = 900 w/m 2 and focused mainly on the effect of temperature on the photovoltaic panel performances. in this study, the electrical characteristics of the used photovoltaic panel are summarized as shown in table 1. table 1. electrical characteristics of the photovoltaic panel figure 1 and figure 2 show our experiment therefore, an appropriate controllable variable load was connected to the pv array. environmental conditions were monitored using the following sensors: sunlight sensor to measure global solar radiation; temperature sensor for measuring the surface temperature of the pv panel. each time we switch the load, we use metering devices to capture the current and voltage and log the data to the laptop. between july and november, this is done. figure 1. measurement system setting up figure 2. photographic view for experimental outdoor electrical characteristics pv panel type: sunmodul sw 80 mono rha/d maximum power (pmax) 80w open-circuit voltage (voc) 22.5v rated voltage (vmpp) 18.5v short-circuit current (isc) 4.66a rated current (impp) 4.53a l. medekhel et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 18-22 page 20 iii. results and analysis iii.1. open-circuit voltage as a function of the temperature the greatest voltage that may be obtained from a solar panel is called the open-circuit voltage (voc), and it happens when the current value is zero. figure.3 shows the open-circuit voltage (voc) of the photovoltaic panel with the temperature change. it is clear that we certify the increase in temperature adversely affected the open-circuit voltage (voc). the highest value was recorded at a temperature equal to 25°c (22.45v) on the date 21 november 2021. in july, the lowest value of voc was recorded at 19.05 v. this is due to the significant rise in temperature, which reached the vale of 69°c. as the temperature increases, the open-circuit voltage values decrease. figure 3. temperature dependence on open-circuit voltage (voc) iii.2. maximal power as a function of the temperature the output power of the pv panel strongly depends on solar irradiance falling upon its surface and the temperature change. figure 4 shows the change in the output power by changing the temperature. at a temperature equal to 25°c, the output power is at its maximum and equal to 68.98 w. these are on 21 november 2021. in july and at a temperature equal to 69°c the output power reaches a very low value compared to the other situation. the temperature change has an important significant effect on the output power produced by the photovoltaic panels. as the temperature increases, the output power decreases remarkably as shown in figure 5. the output power does not exceed 52% of the nominal one recorded at t = 69°c. this result was recorded in july. figure 4. temperature dependence of maximum power (pmax) figure 5. v-i characteristic of a pv panel iii.3. short-circuit current as a function of the temperature the short-circuit current (isc) is the current passing throng a photovoltaic panel when voltage is equal to zero. figure 7 represents the current sugar circuit as a function of the temperature variation from 20 °c up to 70°c. it shows the change in the short-circuit current when the temperature changes. the highest value was recorded at t = 25°c, the short-circuit current (isc) decreases very significantly when the temperature rises. the value of the short-current was close to the value of the current record on the data plate at t = 25°c. these results certify and confirm that the temperature increase greatly affects the short-circuit current. l. medekhel et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 18-22 page 21 figure 6. temperature dependence of short-circuit current (isc) iv. conclusion experimental research work was carried out to test the performances of a mono-crystalline solar panel under different temperatures for different seasons in the algerian desert of the oued souf region.  the efficiency of solar cells is significantly impacted by temperature.  the main effect of increasing temperature for monocrystalline photovoltaic panels is the reduction in the open-circuit voltage values. as a result, the output power declines, which lowers the efficiency of the panels.  when studying the power budget, the temperature must be strongly taken into account because the output power of mono-crystalline panels may be reduced by 48% in areas characterized by high temperatures.  according to testing findings, solar panels operate best in the algerian desert when the temperature varies between 25°c and 34°c. if there is a choice between two sites, it would be preferable to choose one with a low temperature if the irradiance is the same to get higher solar panel performance. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] m. ghodbane, d. benmenine, a. khechekhouche, b. boumeddane, “brief on solar concentrators: differences and applications, ” instrumentation mesure métrologie, vol. 19, no. 5, pp. 371-37, 2020. https://doi.org/10.18280/i2m.190507 [2] a. laaraba, a. khechekhouche. “numerical simulation of natural convection in the air gap of a vertical flat plat thermal solar collector with partitions attached to its glazing. ” indonesian journal of science & technology. vol 3, no2, pp 1423, 2018. https://doi.org/10.17509/ijost.v3i2.12753 [3] a. hadjadj, b. benhaoua, a. atia, a. khechekhouche, n. lebbihiat, a. rouag, “air velocity effect on geothermal helicoidally water-air heat exchanger under el oued climate –algeria, ” thermal science and engining. vol. 20, pp. 100548, 2020. https://doi.org/10.1016/j.tsep.2020.100548 [4] m. jahangiri, s. pahlavan, a. alidadi shamsabadi, a. khechekhouche, “feasibility study of solar water heaters in algeria, a review, ” journal of solar energy research, pp. 135-146, 2018. [5] n.h. zaini, m. z. ab. kadir, m. izadi, n.i. ahmad, m.a.m radzi and n. azis, “ the effect of temperature on a mono-crystalline solar pv panel,” proceedings of the ieee,978-1-4799-8598-2/15/ 2015. [6] t.b. johansson, h. kelly, a.k.n reddy, and r.h. williams, "renewable energy: sources for fuels and electricity," island press, pp. 1-10 1993. [7] nouar anouna, and kada bouchouicha “estimating daily global solar radiation by day of year in algeria,” eur. phys. j. plus 2017. [8] m. irwanyusoff, muhammad irwanto, safwati ibrahim, and leow wai zhe "investigation of the effect temperature on photovoltaic (pv) panel output performance," issn: 2088-5334, vol.6, no. 5, 2016. [9] p. li, x. gao, z. li, x. zhou, “effect of the temperature difference between land and lake on photovoltaic power generation, ”renewable energy, vol 185, pp. 86-95, 2022. https://doi.org/10.1016/j.renene.2021.12.011 [10] q. luo, p. li, l. cai, “experimental investigation on the heat dissipation performance of flared-fin heat sinks for concentration photovoltaic modules,” applied thermal engineering, vol. 157, pp. 113666, 2019. https://doi.org/10.1016/j.applthermaleng.2019.04.076 [11] j. k. kaldellis, m. kapsali, “simulating the dust effect on the energy performance of photovoltaic generators based on experimental measurements,” energy, vol. 36, no. 8, pp. 5154–5161, 2011. https://doi.org/10.1016/j.energy.2011.06.018 [12] p. singh, s.n singh, m. lal, m. husain, “temperature dependence of i-v characteristics and performance parameters of silicon solar cell,” solar energy materials and solar cells 92.12, pp. 1611-1616, 2008. https://doi.org/10.1016/j.solmat.2008.07.010 [13] d.m. tobnaghi, r. madatov, d. naderi, “the effect of temperature on electrical parameters of solar cells,” international journal of advanced research in electrical, https://doi.org/10.1016/j.tsep.2020.100548 https://doi.org/10.1016/j.renene.2021.12.011 https://doi.org/10.1016/j.applthermaleng.2019.04.076 https://doi.org/10.1016/j.energy.2011.06.018 https://doi.org/10.1016/j.solmat.2008.07.010 l. medekhel et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 18-22 page 22 electronics and instrument engineering, vol. 2, pp. 64046407, 2013. [14] d. goossens, h. goverde, f. catthoor, “effect of wind on temperature patterns, electrical characteristics, and performance of building-integrated and building-applied inclined photovoltaic modules,” solar energy, vol.170, pp. 64-75, 2018. https://doi.org/10.1016/j.solener.2018.05.043 [15] m. j. adinoyi, s. a. said, “effect of dust accumulation on the power outputs of solar photovoltaic modules,” renew. energy, vol. 60, pp. 633–636, 2013. https://doi.org/10.1016/j.renene.2013.06.014 [16] p. singh, n.m. ravindra, “temperature dependence of solar cell performance-an analysis,” solar energy materials and solar cells 101, pp. 36-45, 2012. https://doi.org/10.1016/j.solmat.2012.02.019 [17] m. piralaee, a. asgari, “investigation of the performance parameters of p3ht: pcbm solar cell: the role of temperature, ” optik, vol.251, pp. 168453, 2022. https://doi.org/10.1016/j.ijleo.2021.168453 https://doi.org/10.1016/j.solener.2018.05.043 https://doi.org/10.1016/j.renene.2013.06.014 https://doi.org/10.1016/j.solmat.2012.02.019 https://doi.org/10.1016/j.ijleo.2021.168453 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 36-41 ijeca-issn: 2543-3717. december 2019 page 36 a trnsys dynamic simulation model for a parabolic trough solar thermal power plant ahmed remlaoui1,*, mohammed benyoucef 2 , djamel assi 2 , driss nehari 1 1 smart structure laboratory, university center of ain-témouchent, algeria 2 department of mechanical engineering, university center of ain-témouchent, 46000 ain-témouchent, algeria donremlaoui@gmail.com abstract – this paper presents a validated trnsys model for a thermodynamic plant with parabolic trough solar thermal power (pt). the system consist of trough solar collector (ptc) as well as auxiliary components.. the simulation of the system has been done during the day (01/01) under the meteorological conditions of ain témouchent city (algeria). the model compared the energy performance of the systems: case (1) rankine cycle facility with solar field and case (2) rankine cycle facility without solar field. the results showed that the present model has a good agreement with the experimental data of the literature. in case (1), ptc fluid outlet temperature reach the maximum value 330 ° c, work of the steam turbine increase from the 9hr to reach its maximum value 856 kj/kg at 13 hr. in case (2), the maximum value of the power remains constant from the beginning of the simulation to 1hr00. since the flow of fuel (gas natural) consumed does not change throughout the operating period. keywords: trnsys, solar thermal power plant, rankine cycle, parabolic trough power. received: 29/09/2019 – accepted: 10/11/2019 i. introduction electricity generation using a hybrid system combining several renewable energy sources is of great interest to developing countries, such as the maghreb countries. it is well known that generate energy from a solar thermal system with the following technologies are currently used: 1. parabolic trough (ptc) collector; 2. fresnel linear reflector (lfr); 3. sterling dish and solar energy tower [1]. among these technologies, the parabolic collector is more popular and is used in many places around the world. as a result, large concentrated solar power (csp) facilities are ptc technology. several works was realized on trnsys (transient systems simulation) of solar thermal power station. jones et al. [2] created a 30 mwe segs vi parabolic collector base plant model in trnsys to evaluate solar field and power cycle behavior. kolb [3] evaluates the performance of the 1 mwe sugurao solar power plants with and without thermal storage using the trnsys software. the objective of this work is to present the simulation of the hybrid solar field and power cycle model. the stec library of the trnsys software is used for an algerian site (ain témouchent) and meteorological data is provided by the meteonorm software [4]. our goal in this study is the design of a rankine cycle facility with and without solar field by trnsys software. ii. presentation of the parabolic trough solar thermal power plant used in the first part, we used the rankine cycle with the solar field (figure 1). the components of the steam cycle are steam generators (economizer, evaporator, and overheater), three stage steam turbine, condenser, pump, degasser, subcooler, preheater and solar field (parabolic trough). the objective of the collector field is to produce electricity from the thermal installation. the system consists of a parabolic trough collector type field connected to the rankine cycle through a series of heat exchangers. the heat transfer fluid (therminol vp-1) is heated by circulating in the absorbers of the parabolic concentrators (solar field) and returns to the rankine type power cycle, the role of the coolant is to transport the heat from the hot source ( solar rays concentrate in the parabolic trough). the average temperature of the heat transfer fluid changes according to the weather variations from one hour to another during one year (8760 hours). this fluid is pumped with a constant flow to the steam generator, which consists of an economizer, evaporator and superheater. the heat exchangers are of the counter flow type. heat transfer fluid (htf) with rankine cycle water flow is in opposite directions. the heat transfer fluid enters the superheater at high temperature before passing to the steam generator where the water of the power cycle undergoes a phase change from the liquid state to the vapor state. then, the heat transfer fluid passes through abder image placée a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 37 the economizer where yields to the water which is in the liquid state (called feeding) its energy. finally, the fluid is recirculated through the solar field. water before returning to the economizer to complete the cycle the supply water in the liquid state exiting the condenser passes through degasser and then has preheater. this plant also contains a 3-stage turbine namely high pressure, medium pressure and low pressure and two steam withdrawals that communicate with the preheaters. this withdrawn steam is used to heat the feed water before it enters the economizer to increase cycle efficiency. the outgoing steam at the low-pressure turbine is condensed in a condenser. figure 1. schematic diagram of the rankine cycle with solar field iii. system simulation using trnsys trnsys (transient systems simulation) is a complete and extensible simulation environment for the transient simulation of systems, including multi-zone buildings. it is used by engineers and researchers around the world to validate new energy concepts, from simple domestic hot water systems to the design and simulation of buildings and their equipment, including control strategies, occupant behavior, alternative energy systems (wind, solar, photovoltaic, hydrogen systems) [5]. the solar thermal electric component (stec) libraries were developed by peter schwarzbozl (dlr, germany) and scott jones (snl, new mexico) in 2002. they are used to simulate thermal systems (solar and conventional) in order to produce electricity. these libraries are not issued as standard with the trnsys software [6]. figure 2 shows the model under rankine cycle trnsys with solar field and figure 3 shows the power cycle installation without solar field. once all the components of the system have been identified, the main components of this model are described and shown in table 1. figure 2. presentation of the model under trnsys of rankine cycle with solar field a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 38 figure 3. presentation of the model under trnsys of rankine cycle without solar field table 1. the components and input design parameters in trnsys simulation programs component type input parameter value parabolic trough collector (ptc) type396 cwloss coef. d loss coef. clean reflectivity broken mirror fraction length of sca (m) aperature width of sca(m) focal length of sca(m) rowspacing(m) total field area (m2) 0 -0.096 0.94 0.0 14.37 1.52 0.45 4.54 200000 superheater and economizer type 315 counter flow mode overall heat transfer coefficient of exchanger (kj/hr k) reference press loss cold side (bar) reference cold side flow (kg/s) 2 1037068.37(sup) 3055710.24(eco) 1 12.14 evaporator type 316 overall heat transfer factor reference pressure loss (bar) reference flow rate (kg/s) 8164463.48 1 12.14 weather data reading and processing x2x online plotter s-split forcing function dearator type109-tmy2 type 391 type65c type 389 type 14h type 384 ain témouchent converting water vapor temperatures to enthalpies graphical plotter in line with the output file. simulate a vapor separator to allow extraction. constant gas flow in time runs. preheater mixer for feed water or steam is mixed with condensate undercooled to produce saturated water at the outlet turbine type 318 stage design inlet pressure (bar) design outlet pressure (bar) design flow rate(kg/s) design inner efficiency 1 2 3 100 -23.89 -2.875 23.89-2.875-0.08 12.14-9.919-8.82 0.84 0.85 0.86 condenser type 383 dt cool water out+condensing temp (delta c) temp increase in cool. water(delta c) 4 15 condenser pump and feed pump type 300 type maximum flow rate fluid specific heat maximum power cp fp 8.525 8.525 4.17814 4.19 1000 1000 preheater type 317 cold fluid spef. heat capacity (kj/kg k) overall heat transfer factor (kj/hr k) cold sid ref flow rate (kg/s) 4.24 186840 12.14 subcooler type 320 specific heat of hot side fluid (kj/kg k) specific heat of cold side fluid(kj/kg k) 3.355 4.240 a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 39 iv. results and discussion iv.1. meteorological data in order to run a simulation for one year and to predict the performance of the ssh system, a typical meteorological year of ain témouchent (tmy) is used at gmt1 time zone, latitude 35.306 0n and longitude 1.147 0e were used. figure 4a shows the solar radiation, (b) wind speed and dry bulb temperature. the peak total horizontal radiation is approximately 360 w.m -2 and occurs in the period from june to jul. this period is characterized by high ambient temperature with the peak 37 °c and maximum wind speed is 15 m/s. figure 5 shows the variation of the ambient temperature and annual average humidity. for the variation of the average annual moisture content, we observe that it is less important during the summer season it is balance between 0.48 and 0.63, so is important during the winter season it is balance between 0.63 and 0.82. figure 4a. solar radiation figure 4b. variations of ambient temperature and wind speed over one year . figure 5. variations in temperature and annual average humidity iv.2. thermal performance evaluation with solar field iv.2.1. ptc fluid inlet and outlet temperature the curve illustrated in figure 6 shows that at the beginning of the heating, at t = 0 the outlet temperature of the coolant is equal to the temperature of the injected fluid, after the sun rises this temperature increases with solar radiation concentrated to the concentrator opening, it reaches 200 °c between 09hr and 10hr while the inlet temperature reaches 177 °c. it continues its increase to reach the maximum value 330 °c to 13hr. during the afternoon, it will decrease until it reaches zero. a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 40 figure 6. variation of ptc fluid inlet and outlet temperature during the day of january 1 iv.2.2. steam generator temperatures of the fluid on the hot and cold sides the curve shown in figure 7 shows that steam generator fluid temperatures on the hot and cold sides increase to a maximum around 13hr at the steam generator inlet. this period corresponds to maximum sunlight. with regard to the (cold side), it is noted that the outlet temperature (cold side) in each exchanger will increase and reach the maximum output value 327 ° c to 13:00h. after 13:00h, the exit temperatures on each side and each exchanger will go down when the irradiation of the sun decreases until 18:00h or it will be zero. figure 7. variation of steam generator temperatures of the fluid on the hot and cold sides during the day of january 1 iv.2.3. transferred power the curve illustrated in figure 8 shows the evolution of the transferred power of each exchanger: economizer, evaporator, super heater and condenser. both types of transferred power (qin and oout) go into an increase from 8am in the morning to reach a maximum value at 13:00h such that qinmax = 3.9 * 107 kj/hr and qout,max = 3.4 * 107 kj/hr, then decrease in the next period to reach the zero value at 18:00h. it is observed that the transferred power used by the system (qin) is greater than the heat lost (qout), this difference is the main advantage for the increase of the efficiency of the installation. figure 8. variation of transferred power during the day of january 1 iv.2.4. work of the steam turbine figure 9 shows the evolution of the three stages of the steam turbine and the total work: it is observed that the work begins to increase from the 9:00h to reach its maximum value 856 kj / kg at 13:00h. then it starts to decrease after this maximum value so that it is zero at 18:00h. note also that the intermediate floor work is larger than the floors of the ends. figure 9. variation of work of the steam turbine during the day of january 1 iv.3. thermal performance evaluation without solar field iv.3.1. power of the steam turbine in this cycle, the thermal performance is almost constant throughout the week, due to the stability of the turbine power used, if for this reason we will take just one day in this cycle to evaluate the thermal behavior of the installation as we have a week of evaluation. in the second part, we will study a plant of the power cycle by the use of natural gas, and the results of this simulation will be presented by the figures below. the curve shown in figure 10 shows the evolution of the power of each stage obtained by the steam turbine; we note that the maximum value of the power remains constant from the beginning of the simulation to 01:00h. since the flow of fuel (gas natural) consumed does not change throughout the operating period. a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 41 figure 10. variation of power of the steam turbine during the day of january 1 iv.3.2. transferred power and work of the steam turbine the two curves of figure 11and 12 remain invariable for the work and the transferred power in both cases have the same max. figure 11. variation of transferred power during the day of january 1 figure 12. variation of work of the steam turbine during the day of january 1 v. conclusion this article aims at the study of an installation of the rankine cycle powered energetically by the solar field; through a modeling, which was carried out by trnsys software, knowing that the weather conditions of ain témouchent was used for the purpose of, evaluate the thermal behavior of the installation during one week. two cases were studied: case (1) rankine cycle facility with solar field and case (2) rankine cycle facility without solar field. results obtained showed: in case (1), ptc fluid outlet temperature reach the maximum value 330 ° c, work of the steam turbine increase from the 9hr to reach its maximum value 856 kj/kg at 13:00h. in case (2), the maximum value of the power remains constant from the beginning of the simulation to 1hr00. since the flow of fuel (gas natural) consumed does not change throughout the operating period. the results showed that the minimum efficiency of the facility is 13% in the winter period. for a power equal to 4mw, the natural gas consumption can be gained of 312.4 kg/hr in the sunny period. acknowledgements the authors gratefully acknowledge support from smart structure laboratory of university center belhadj bouchaïb, ain témouchent (algeria). references [1] s. sukhatme, j. nayak, “solar energy, principles of thermal collection and storage”, 3rd ed., tata mcgraw hill, ed. new york, 2009 [2] s. jones, r. pitz-paal, p. schwarzboezl, v.blair, r. cable. “trnsys modelling of the segs vi parabolic troug solar electric generating system, in proc”. asme international solar energy conference solar forum, washington dc, paper 01.3, 2004, pp. 109. [3] g. kolb, v. hassani. “performance analysis of thermocline energy storage proposed for the 1 mw saguaro solar trough plant, in proc”. asme international solar energy conference, denver. 15, 2006, pp. 8-13. [4] p schwarzboezl. “a trnsys model library for solar thermal electric components (stec)”. reference manual. release 3.0, november 2006. [5] solar energy laboratory, 2000, “trnsys, a transient simulation program,” university of wisconsin, madison, http://sel.me.wisc.edu/trnsys/. [6] r.pitz-paal, s.a jones. “a trnsys model library for solar thermal electric components (stec),” a reference manual, release 1.0, iea-solar power and chemical energy systems, task iii: solar technologies and applications. 1998 http://sel.me.wisc.edu/trnsys/ i. introduction ii. presentation of the parabolic trough solar thermal power plant used iii. system simulation using trnsys iv. results and discussion iv.2. thermal performance evaluation with solar field iv.2.1. ptc fluid inlet and outlet temperature iv.2.2. steam generator temperatures of the fluid on the hot and cold sides iv.2.3. transferred power iv.2.4. work of the steam turbine iv.3. thermal performance evaluation without solar field iv.3.1. power of the steam turbine iv.3.2. transferred power and work of the steam turbine v. conclusion acknowledgements references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 27-30 .http://dx.doi.org/10.47238/ijeca.v5i1.119. june 2020 page 27 enhancing of ch3nh3sni3 based solar cell efficiency by etl engineering. abdelkader hima 1* , abderrahmane khechekhouche 2,3 , imad kemerchou 3,4 1 department of electrical engineering, fac. technology, university of el oued, el oued, 39000, algeria 2 faculty of technology, el-oued university, algeria 3 laboratory ofanalysis and control of energy systems and networks, university thelidji amar of laghouat, algeria 4 materials science and engineering program, state university of new york at binghamton, binghamton, new york 13902, usa e-mail*: abdelkader-hima@univ-eloued.dz abstract – solar cells based on organic-inorganic perovskites (pvk) are the subject of several researches in laboratories around the world. one of the most promising hybrid perovskite is the methylammonium lead tri-iodide mapbi3 that is suitable for sun light harvesting. but the mapbi3 is a toxic material, so in this paper is proposed another nature friendly candidate which is the methylammonium tin tri-iodide masni3. the proposed material is inserted into an n-i-p heterojunction solar cell which structure is electron transport layer (etl)/pvk/hole transport layer (htl). the used htl is the pedot: pss in combination with one of two etls which are the pcbm and the igzo. simulation efforts using 1d scaps was carried. it is found that igzo etl based solar cell yields a higher power conversion efficiency (pce) compared with pcbm etl based solar cell in the same thickness. keywords: perovskite, solar cell, scaps software, pce, pcbm, igzo. received: 03/04/2020 – accepted: 12/06/2020 nomenclature abbreviations voc open circuit voltage ff fill factor jsc short circuit density of current pce power conversion efficiency eg band gap energy pvk perovskite  electron affinity etl electron transport material nc conduction band effective density of states htl hole transport material nv valence band effective density of states masni3 methylammonium tin tri-iodide r relative permittivity mapbi3 methylammonium lead tri-iodide µn electron mobility pcbm phenyl-c61-butyric-acid-methylester µh hole mobility pedot:pss poly(3,4-ethylenedioxythiophene) polystyrene sulfonate na shallow uniform acceptor density igzo indium galium zinc oxide nd shallow uniform donor density nt defect density of states α absorption coefficient h plank constant v frequency of light a and b material dependent constants mailto:abdelkader-hima@univ-eloued.dz abdelkader hima. et al ijeca-issn: 2543-3717. june 2020 page 28 i. introduction recently, power conversion efficiency of perovskite solar cells stepped exponentially from 2.2 % in 2006 [1] up to 25.2 % in 2019 [2]. this evolution attracted researcher’s attention to simulate new designs, fabricate perovskite solar cells using deferent methods and study of processing effects on device performances [3-5]. a numerical simulation has been done by researchers they find that the power conversion efficiency is 21.8% under optimized conditions and a pce of up to 15% were obtained by initially optimizing the preparation of the layer absorbent ch3nh3pbi3 [6]. a study shows that the energy conversion yields of perovskite-based solar cells have improved significantly to over 20 %, which now makes them equivalent to the performance of siliconbased photovoltaics [7, 8]. a group of researchers found that the energy of auerbach decreases with the rise in the temperature of the treatment giving the lower value of 0.66 ev at 100 ° c, which also corresponds to the best band range of 1 to 49 ev [9]. a numerical study has been made which focuses on the thickness and density of the states (donors and acceptors) and on the efficiency of solar cells. the results found improved the power conversion efficiency (pce) from 11.73% to 19.58% [9]. the optimization and the thickness of the layers were also done [10, 11]. most of perovskite solar cells use lead based materials which are not environment-friendly. in this paper, simulation efforts are conducted to study a free lead alternative of perovskite solar cells. software used for numerical calculation is scaps 1d [12, 13]. the objective of our work is to show that the lead-free ch3nh3sni3 perovskite-based solar cell exhibited better electrical performance when using igzo material in the etl. ii. device structure and methodology figure 1 presents the n-i-p perovskite heterojunction solar cell device that contains three layers: an electron transport layer, a perovskite layer and a hole transport layer. figure 1. n-i-p solar cell structure the table 1 summarizes electrical and optical parameters of each layer carefully selected from literature. the solar cell is exposed to a standard am1.5 solar spectrum under an incident power density of 100 mw/cm 2 . in all simulations, the pre-factor values of a and b (see equation 1.) are taken to be equal to 10 5 and 0 respectively for all used materials for calculation simplicity. α=(a+b/hv).(hv-eg) 1/2 (1) where α, h, v, eg are the absorption coefficient, plank constant, frequency of light and the band gap respectively, and a and b are model dependent parameters [12]. table .1. electrical and optical parameters masni3 [3] pedot:pss [3] igzo [4] pcbm [4] thickness variable variable variable variable eg (ev) 1.9 1.6 3.05 2  (ev) 3.98 3.4 4.16 3.9 r 10 3 10 3.9 nc (cm-3) 1016 1022 5*1018 2.5*1021 nv (cm-3) 1015 1022 5*1018 2.5*1021 µn (cm2/vs) 16.2 4.5*10-4 15 0.02 µh (cm2/vs) 10.1 9.9*10-5 0.1 0.02 na (cm -3) 109 1022 nd (cm -3) 109 1018 2.73*1017 nt (cm-3) 1014 2.5*1015 1015 1015 figure 2 presents energy band alignment of different used materials. abdelkader hima. et al ijeca-issn: 2543-3717. june 2020 page 29 figure .2. energy band alignment iii. result and discussions the first simulated structure is pcbm/masni3/pedot:pss/ag with initial layer thickness of 30 nm, 400 nm and 30 nm respectively, and then we change the pvk layer thickness to find out the one corresponding to the maximum of power conversion efficiency (pce). in the second simulated structure, we change the etl material from pcbm to igzo, and do the same optimization effort to find out the best pvk layer thickness that yields the maximum of pce. figure 3 and figure 4 show the different electrical parameters of both structures in function of pvk layer thickness, where we can notice that the second structure electrical parameters are better than the first structure. we can notice that concerning voc and ff, the two structures are approximately identical. however, in pce and jsc curves, we can notice that in low thickness values the two structures are approximately identical but in high values there is a more difference. figure .3. open circuit voltage in function of perovskite layer thickness figure .4. short circuit density of current in function of perovskite layer thickness figure 5 and figure 6 show the maximum values of the power conversion efficiency which are 12.58 % and 13.12 % for the first structure and the second structure respectively. this pce optimized value corresponds with the pvk layer thickness of 1 µm. figure .5. power conversion efficiency in function of perovskite layer thickness figure .6. fill factor in function of perovskite layer thickness abdelkader hima. et al ijeca-issn: 2543-3717. june 2020 page 30 table 2 gives the electrical parameters for both optimized structures (with pvk layer thickness of 1 µm). table .2. optimized electrical parameters for both structures paramater voc (v) jsc (ma/cm 2 ) ff (%) pce (%) 1 st structure 0.75 27 62.25 12.58 2 nd structure 0.75 28.08 62.33 13.12 figure 7 is presents the iv characteristic of both optimized structures where it is clear that igzo based structure is better than the pcbm structure. figure .7. iv characteristics of the 1st and 2nd structures iv. conclusion in this paper it is found that lead free perovskite ch3nh3sni3 based solar cell exhibited better electrical performances when using igzo material as etl. the pce of igzo based structure is better than the pcbm one especially in high perovskite layer thickness. it is found that igzo based solar cell maximum pce corresponds with 13.12 % which is better than the pcbm based solar cell maximum pce of 12.58% with a thickness of 30 nm for both etl and htl, and 1 µm for ch3nh3sni3. acknowledgements this work is supported by the research project university-formation (prfu) of algerian ministry of high education and scientific research (no.a16n01un390120180002) entitled “studies on synthesis, extraction and use of products and materials for environment and energy" references [1] a. kojima, k. teshima, t. miyasaka, and y. shirai, "novel photoelectrochemical cell with mesoscopic electrodes sensitized by lead-halide compounds (2) 210th ecs meeting, cancun, mexico", october abstract, vol. 397, 2006, pp. 397397 [2] nrel efficiency shart. available: https://www.nrel.gov/pv/assets/pdfs/best-research-cellefficiencies. 2020 [3] a. hima, n. lakhdar, b. boubaker, s. achour, k. imad, and r. fatiha, "an optimized perovskite solar cell designs for high conversion efficiency", superlattices and microstructures, vol. 129, 2019, pp. 240-246 [4] n. lakhdar and a. hima, "electron transport material effect on performance of perovskite solar cells based on ch3nh3gei3", optical materials, vol. 99, 2020, pp. 109517 [5] a. hima and n. lakhdar, "enhancement of efficiency and stability of ch3nh3gei3 solar cells with cusbs2", optical materials, vol. 99, 2020, pp. 109607 [6] x. wei, x. wang, h. jiang, y. huang, a. han, q. gao, jiantao bian, zhengxin liu, "numerical simulation and experimental validation of inverted planar perovskite solar cells based on nio x hole transport layer", superlattices and microstructures, vol. 112, 2017, pp. 383-393 [7] s. f. hoefler, g. trimmel, and t. rath, "progress on leadfree metal halide perovskites for photovoltaic applications: a review", monatsh chem, vol. 148, no 5, 2017, pp. 795826 [8] m. konstantakou and t. stergiopoulos, "a critical review on tin halide perovskite solar cells", journal of materials chemistry a, vol. 5, no 23, 2017, pp. 11518-11549 [9] i. kemerchou, f. rogti, b. benhaoua, n. lakhdar, a. hima, o. benhaoua, a. khechekhouche, "processing temperature effect on optical and morphological parameters of organic perovskite ch3nh3pbi3 prepared using spray pyrolysis method", journal of nanoand electronic physics; vol. 11, no 3, 2019, pp. 03011 (4) [10] a. hima, a. k. le khouimes, a. rezzoug, m. b. yahkem, a. khechekhouche, and i. kemerchou, "simulation and optimization of ch3nh3pbi3 based inverted planar heterojunction solar cell using scaps software", international journal of energetica, vol. 4, no 1, pp. 56-59 [11] a. hima, a. khechekhouche, i. kemerchou, n. lakhdar, b. benhaoua, f. rogti, i. telli, a. saadoun, "gpvdm simulation of layer thickness effect on power conversion efficiency of ch3nh3pbi3 based planar heterojunction solar cell", international journal of energetica, vol. 3, no 1, 2019, pp. 56-59 [12] m. burgelman, k. decock, a. niemegeers, j. verschraegen, and s. degrave, "scaps manual," ed: february, 2016. [13] m. burgelman, k. decock, s. khelifi, and a. abass, "advanced electrical simulation of thin film solar cells", thin solid films, vol. 535, 2013, pp. 296-301 i. introduction ii. device structure and methodology iii. result and discussions iv. conclusion acknowledgements references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 08-13 ijeca-issn: 2543-3717. december 2019 page 8 comparative study between pi and fuzzy pi controllers for dfig integrated in variable speed wind turbine h. mesai ahmed 1 , a. bentaallah 1 , y. djeriri 1 , a. mahmoudi 2,3 1 iceps intelligent control and electrical power systems laboratory, university of sidi bel abbes, algeria 2lmse laboratoire modélisation des systeme energitique , university of biskra , algeria 3cise electromechatronic systems research centre, university of beira interior, covilhã, portugal hamzamesai2@hotmail.com abstract – this paper presents the contribution of the application of fuzzy logic for the independent control of the active and reactive power stator of a doubly fed induction generator (dfig), used in a variable speed wind energy conversion system. so in this work, we are particularly interested in the application of indirect vector control by stator flux orientation to the dfig, based on fuzzy controllers. these latter surpass the limits of conventional controllers and possess essential characteristics for the improvement of the robustness of the vector control with against parameters variations of the system. the obtained simulation results have shown that it is possible to control the stator powers, even in the presence of parametric variations. keywords: wind energy doubly fed induction generator vector control fuzzy logic received: 12/11/2019 – accepted: 15/12/2019 i. introduction the new wind turbines technology work at variable spee ds.this type of operation allows energy efficiency to be in creased, mechanical loads to be reduced and the perform ance of the electrical energy generated to be improved. compared to the wind turbines at fixed speed, such wind turbines often use the doubly fed generator of induction (dfig) [1, 2]. the indirect vector control based on conventional regulators pi type (proportionalintegral) is traditionally used to control the active and reactive power of dfig [3, 4]. this technique decouples the rotor current active and reactive components are obtained indirectly by controlling the input currents. artificial intelligence techniques are currently known for their great potential to solve problems related to industrial processes. these techniques include genetic algorithms, neural networks and fuzzy logic that are increasingly applied in the control of the induction machine and the adaptation of its vector control [5]. in our study, we looked at fuzzy logic to synthesize robust regulators against dfig parametric variations to replace the four conventional ip controllers used in vector control. simulation results are presented to show the effectiveness of these regulators in solving the robustness problem so that they compare their performance with conventional regulators. ii. simplified model of dfig the dfig is represented by park model (d-q) whose equations are established in a reference related to the rotating field as follows [6]:  the terminal voltages         sdssqsqssq sqssdsdssd dt d irv dt d irv   (1)  the rotor voltages         rdrsrqrqrrq rqrsrdrdrrd dt d irv dt d irv   )( )( (2) abder image placée h. mesai ahmed et al ijeca-issn: 2543-3717. december 2019 page 9 (1) (2) the active and reactive statoric powers are expressed by:             sqsdsdsqs sqsqsdsds ivivq ivivp 2 3 2 3 (3) (3)  the electromagnetic torque )( 2 3 rqsdrdsq s m em ii l l pc  (4) (4) with: p is the number of pole pairs of the dfig. in view of dfig's vector control; it makes more sense to choose the d-q coordinator related to the statoric rotating field, which is related to the frequency of 50hz (frequency of the electrical grid). therefore, park's coordinator will be synchronized with the statoric flux (figure 1) figure 1. stator flux orientation often in the case of a dfig medium and high power, the stator resistance rs is neglected during the synthesis of the model according the assumption of orientation of the stator flux [7, 8]. by adopting the hypothesisof negligible stator resistance rs and the stator flux is constant and oriented according to the d-axis, we deduce:      ssd sq   0 (5)      ssssq sd vv v  0 (6)      rqmsqs rdmsdss ilil ilil 0 (7) from equation (7), we can write:           rq s m sq rd s m s s sd i l l i i l l l i (8)        rqrrq s s m rdrrd il l l il   (9) with :  rsm lll /1 2 (dispersion coefficient of blondel). by substituting the expression (9) of the rotor flux in equation (2) we obtain         s sm rdrsrqrrqrrq rqrsrdrrdrrd l vl gilgi dt d lirv ilgi dt d lirv   (10 in steady state, the terms involving derivatives of the diphasic rotor currents disappear, we can write:        s sm rdrsrqrrq rqrsrdrrd l vl gilgirv ilgirv   (11) the adaptation equations powers (3) with the axis system chosen and the simplifying assumptions made in this case (vsd=0) gives:         sdss sqss ivq ivp 2 3 2 3 (12) by replacing the stator currents by their values the equation (8) in equation (12) we obtain the following expressions for the active and reactive power:                    rd s m s s s ss rq s m ss i l l v l vq i l l vp 2 3 2 3 (13) h. mesai ahmed et al ijeca-issn: 2543-3717. december 2019 page 10 by pulling s s s v   the equation (6), the expression of reactive power becomes:          ss s rd s m ss l v i l l vq 2 3 2 3 2 (14) given the chosen coordinator, approximations made and if we consider the magnetizing inductance lm as constant (constant air gap), the resulting system proportionately links the active power to the rotor q-axis current and the reactive power to the rotor d-axis at a constant  sss lv 2/3 2 imposed by the grid. replacing (6) in (4), the dfig torque will be expressed: rq ss sm rqs s m em i l vl pi l l pc 2 3 2 3  (15) iii. indirect vector control of dfig this method involves taking into account the terms of coupling (cd and cq) and compensating them by using a system with two loops to control rotor power and currents, based on conventional ip-type regulators (proportional-integral). the block diagram of the system is thus reproduced in the opposite direction, resulting in a model corresponds to that of the machine but in the other direction which contains all the elements of the block diagram of the dfig. in this method, decoupling is done at the outputs of the current regulators rotor with a feedback, which allows the adjustment of the powers (figure 2). in our work, the design of these regulators is achieved by the method of compensation of the dominant poles. figure 2. block diagram of the indirect control with power loops with:       rdrsq rqrsd ilgc ilgc            s sm q ss s d l vgl f l v f 2 3 2 iv. fuzzy logic control the advantage of fuzzy control over conventional controls is that it does not require knowledge of mathematical models of the system. on the other hand, it needs a set of rules based mainly on the knowledge of a qualified operator manipulating the system [9]. the design of the fuzzy controller (flc) through four main distinct steps is shown in figure 3. the two most significant variables to analyze the behavior of the system to know the error and its variation are chosen as the two inputs of the controller by fuzzy logic (rfl). figure 3. basic structure of a fuzzy logic control [11,12] the output is the increment of the control signal applied to the system to be controlled qrdi (see figure 4). figure 4. the dfim control system block diagram the rfl inputs are calculated at time k as follows [12, 13]. )()()( kpkpke srefp  (16) )1()()(  kekekde ppp (17) thee ref rqi control signal is obtained after the integration of the rfl output )()1()( kdikiki refrq ref rq ref rq  (18) h. mesai ahmed et al ijeca-issn: 2543-3717. december 2019 page 11 the same reasoning and procedure applies to the reactive power loop where the control signal is the direct rotoric current ref rdi . the fuzzy regulator shown in figure 4 is composed of [11]:  the triangular and trapezoidal membership functions, this choice is due to the simplicity of implementation  a standardized universe of discourse; the universe of discourse is divided into three (fine adjustment) for the input and output variables  mamdani's involvement in inference.  the centre of gravity method for defuzzification. a. fuzzification for the membership functions, triangular and trapezoidal shapes were chosen for each variable as shown in figure 5[9]: figure 5. membership functions for input variables ep, dep and outlet dirq of the fuzzy controller of active power. b. inference as mentioned before, each of the two linguistic inputs of the fuzzy controller has three fuzzy sets, resulting in a set of nine rules. these can be represented by the following inference matrix [7] dep dirp p z n z n n n ep p z n z p p z p table 1. inference matrix of the fuzzy power regulator. c. defuzzification for defuzzification, we use the method of the center of gravity presented previously, we obtain    )( )( rqiri rqirqiri rq i dii di   (19) dfig's indirect power control strategy through fuzzy logic was validated by numerical simulation using matlab/simulink software: figure 6. simulation results of the dfig vector control based on fuzzy controllers (rfl), at variable wind speed the simulation results presented in figure 6 show that the fuzzy controller offers better dynamic and static performance of power reference tracking, with a very fast response time, no overshoot and an almost zero static error. 0 0.5 1 1.5 2 2.5 3 3.5 4 -16 -14 -12 -10 -8 -6 -4 -2 0 x 10 5 temps (s) p u is s a n c e a c t iv e p s ( w ) ps* ps p u is s a n c e r é a c ti v e o s ( v a r ) 3000 0 0.5 1 1.5 2 2.5 3 3.5 4 -2 -1.5 -1 -0.5 0 0.5 1 x 10 5 temps (s) p u is s a n c e r é a c ti v e o s ( v a r ) qs* qs 0 0.5 1 1.5 2 2.5 3 3.5 4 -3000 -2500 -2000 -1500 -1000 -500 0 500 temps (s) c o u r a n ts s ta to r iq u e s i s d i s q ( a ) isq isd 0 0.5 1 1.5 2 2.5 3 3.5 4 -500 0 500 1000 1500 2000 2500 3000 temps (a) c o u r a n t s r o t o r i q u e s i r d i r q ( a ) ird irq temps (s) 1 0 0 -1 1 n z p µ(ep), µ(dep ), µ(dirq ) ep, dep, dirq h. mesai ahmed et al ijeca-issn: 2543-3717. december 2019 page 12 3.2. robustness test the purpose of this test is to test the robustness of the technique of two controllers (pi -rlf) against variations in dfig parameters. we will perform a decrease in the mutual inductance (30% of lm), which corresponds to a saturation effect of the machine's magnetic circuit. from the results obtained in figure 7, it can be seen that the fuzzy controller retains its robustness in the face of the variation in mutual inductance, while the pi controller loses its robustness completely. figure 7. robustness test of controllers against dfig parametric variations we can summarize the dynamic and static performance obtained by the two regulators in normal operation (without parametric change) by the following table: table 2. performance comparison of the two regulators controller performances pi rlf response time (ms) 6 1.95 exceedance (%) 6 6 static error (%) 0.6 1.42 (w) 9000 21000 robustness to variation parameters bad acceptable conception simple difficult v. conclusion in this paper, the robust vector control of dfig based on fuzzy logic technique has been presented, whose notion of the offline decision table is implemented in the vector control of dfig. this choice of command was justified by the ability of fuzzy logic to deal with imprecision, uncertainty and vagueness. from the simulation results obtained, it can be said that the fuzzy controller provides significant robustness to the vector control of the dfig, with respect to the parametric variations of the latter, in particular the mutual inductance. by comparison, fuzzy controllers offer significant improvements over conventional controllers in terms of speed of transient regimes and insensitivity to parametric variations in the system. references [1] t. ghennam, “supervision d’une ferme éolienne pour son intégration dans la gestion d’un réseau électrique, apports des convertisseurs multi niveaux au réglage des éoliennes à base de machine asynchrone à double alimentation”, thèse de doctorat de l’ecole militaire polytechnique d’alger, algérie, septembre 2011. [2] l. peng, “reconfiguration du dispositif de commande d’une éolienne en cas de creux de tension”, thèse de doctorat, ecole centrale de lille, france, juin 2010. [3] b. hopfensperger, d.j. atkinson, r. lakin. 'stator-flux-oriented control of a doubly-fed induction machine with and without position encoder ', ieee proceedings – electric power applications, vol. 147, n°4, 2000, pp. 241 250. [4] m. yamamoto, o. motoyoshi. “active and reactive power control for doubly-fed wound rotor induction generator”, ieee transactions on power electronics, vol. 6, n°4, 1991, pp. 624 629. [5] h. mesai ahmed, y. djeriri, a.bentallah, “robust power controlof dfig using artificial neural networks for a wind energy conversion system based energy storage unit”. 2nd international symposium mechatronics, renewable energy ismre’2018 el-oued, algeria. 2018. [6] yaichi, i., semmah, a., wira, p. and djeriri, y. “supertwisting sliding mode control of a doubly-fed induction generator based on the svm strategy”. periodica polytechnica electrical engineering and computer science, vol. 63, n°3, 2019, pp.178-190. [7] y. djeriri, a. meroufel. “commande vectorielle par les réseaux de neurones artificiels d’une mada intégrée à un système eolien”; 6th international conference on electrical engineering, 2010, pp. 33-37. algeria. [8] s. muller, m. deicke and r.w. de doncker. “doubly fed induction generator systems for wind turbines”', ieee industry applications magazine, 2002, pp. 26 – 33. [9] e.h. mamdani and s. assilian. “an experiment in linguistic synthesis with a fuzzy logic controller”, international journal of machine studies, 1975, vol. 7, pp. 1 13. [10] m.j. hany. “design and implementation of neuron fuzzy vector control for wind-driven d o u b l y -fed 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -1 -0.5 0 0.5 1 1.5 2 x 10 6 temps (s) p u is s a n c e r é a c ti v e q s ( v a r) qs* qs-rc (0.7*lm) qs-rlf (0.7*lm) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -1 -0.5 0 0.5 1 1.5 2 x 10 6 temps (s) p u is sa n c e r é a c ti v e q s ( v a r) qs* qs-rc (0.7*lm) qs-rlf (0.7*lm) h. mesai ahmed et al ijeca-issn: 2543-3717. december 2019 page 13 induction generator”, ieee transactions on sustainable energy conversion, vol. 2, n°4, 2011. [11] a. chaiba, r. abdessemed, m.l. bendaas a. dendouga. “performances of torque tracking control for doubly fed asynchronous motor using pi and fuzzy logic controllers"', journal of electrical engineering, vol. 5, n°2, 2 0 0 5 , pp. 25 30. [12] z. boudjema, a. meroufel y.djeriri. “nonlinear control of a doubly fed induction generator for wind energy conversion”, carpathian journal of electronic and computer engineering, vol. 6, n°1, 2 0 1 3 pp. 28 35. [13] k. mouilah, m. abid, a. naceri m. allam. “fuzzy control of a doubly fed induction generator for wind turbines”, journal of electrical engineering, jee, vol. 14, n°4, 2014, pp. 352 357. i. introduction ii. simplified model of dfig iii. indirect vector control of dfig iv. fuzzy logic control v. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 47-51 ijeca-issn: 2543-3717. december 2020 page 47 performance of a wastewater treatment plant in south-eastern algeria abderrahmane khechekhouche 1 , fattoum bouchemal 1 , zineb kaddour 2 , khechana salim 1.3 , abdelmonem miloudi 1 1 department of hydraulic and civil engineering., technology faculty, university of el-oued, algeria 2 vtres laboratory, university of el-oued, algeria 3 levres laboratory, university of el-oued, algeria email * : abder03@hotmail.com abstract – the experimental study was carried out on an urban wastewater purification station located in the region of el oued -kouninein south-eastern algeria. during 6 months, samples were taken every month to study the physico-chemical parameters of this station. monthly monitoring of ss, cod, bod5 was made from september 2017 to february 2018 and the results obtained show that the average elimination rates were 77.76, 74.10 and 80% respectively for bod5, dco and ss. the average of the ratio cod/bod5 during the 6 months of follow-up is equal to 2.9. keywords: ss, cod, bod5, purification station, pollution, physico-chemical parameters. received: 14/09/2020 – accepted: 07/11/2020 i. introduction wastewater discharges are increasing due to industrialization and the rise in the standard of living of the population, the self-purification capacities are considered to be exceeded, which prompts researchers to develop several techniques to purify these effluents. solar energy is free and environmental energy that can be used for water treatment such as solar distillation but unfortunately, this technique suffers from its low efficiency [1-4]. researchers in the field of water treatment preferred neat large-quantity wastewater. the installation of purification systems downstream of sewerage networks is one of the solutions, if not the only one capable of preserving water resources. in addition to the decontamination of effluents, these installations allow the mobilization of a large volume of water suitable for reuse in several areas. wastewater is all water from domestic, agricultural and industrial activities loaded with toxic substances that enters sewage pipes. they also include rainwater and its pollutant loads; they generate all kinds of pollution and nuisance in the receiving environment [5]. biodegradable organics, hazardous, toxic, pollutant, bacteria, and hundreds of chemical compounds that float and settle in wastewater. considering the reactions between water, oxygen, bacteria, temperatures and many other factors, grandiose environmental problems have arisen in many regions of the globe such as the depletion of the quality of water in rivers, the appearance of diseases. waterborne and biodiversity extinction [6-8]. municipal wastewater treatment plants (wwtps) are public interest processes focused not on economic gains, but on the environment. the operation of a wastewater treatment plant leads to environmental impacts such as direct greenhouse gas (ghg) emissions from biological processes [9, 10]. various physical, chemical and biological solutions and even by solar energy are under development [11, 12]. the objective of our work is to follow up for 6 months of a treatment plant in our region to find out whether the treated wastewater is by international standards and to determine the physicochemical and biological purifying power of the waters of the city of el-oued by the kouinine purification station. abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2020 page 48 ii. method and experience ii.1. theoretical geographic position with a diameter area of 54573 square kilometers, the region of el oued is located in south-eastern algeria. the geographical coordinates of el oued are as follows: latitude 33.3683 ° and longitude 6.8674 ° with a mean altitude of 60 m as shown in figure 1 [13]. figure 1. location of el oued area ii.2. the operating principle of purification station in general, the wastewater treatment plant is made up of six aerated lagoons divided into two treatment stages and three finishing lagoons (3rd stage), a pretreatment structure (screening, sand trap), 14 drying beds for sewage sludge and operating building, as well as the assembly of hydromechanical and electrical equipment. figure 2 shows the stage principles of a wastewater treatment plant. figure 2. operating principle of purification station iii. results and discussion iii.1. performance of a station in this paper, we will study the operation of the kouinine south-east algeria treatment plant, on the one hand, and on the other hand, to examine the purification power and to follow the elimination efficiency of various pollution parameters. (organic load, dissolved oxygen, conductivity, etc.) at the exit of the station. in order to properly control the quality of the purified water (wwtp outlet), we will group all the results of the physicochemical parameters analyzed in tables or the form of curves and histograms to better examine the efficiency of the purification process. within the framework of this study, the parameters retained are as follows: ss, cod, bod5. the period taken for the analysis is from september 2017 to february 2018. iii.1.1. suspended solids (ss) the suspended solids (ss) are, for the most part, biodegradable by nature. the values reported in figure 3 show a substantial reduction in suspended solids between raw and treated water. they are distinguished by an average concentration of 194.65 mg/l for raw influents and 31.03 mg/l for treated effluents and lower than the specific limit value for direct discharge to the algerian receiving setting (40 mg/l). the monthly evolution of the suspended solid content (ss) of the gross influent at kouinine station shows that the highest load was registered during the time (septfeb); this high content may be the product of the intake of water loaded with mineral matter, i.e. sand, silt, etc. since these withdrawals coincided with sandstorms. the content and the mineral and organic composition of the materials in suspension in the raw wastewater are very variable depending on the watercourse (sand, sludge, organic particles, plankton, etc.); they depend on the nature of the land crossed, the season, the rainfall, the works, the discharges, etc. figure 3. ss evolution abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2020 page 49 iii.1.2. chemical oxygen demand (cod) figure 4 shows that the monthly average cod concentrations of raw water of the order of 403.11 mg/l and for treated effluent, the observed cod values are much lower than that of raw water on average of 102.83 mg/l, these values showed a high reduction of aerated basins in relation to carbon pollution. besides, the comparison of the cod content at kouinine station complies with the algerian standard for direct discharges to the receiving environment (120 mg/l). in wastewater from the station, the cod is evolving in the same direction as the mineralization gradient (upstreamdownstream). however, the effect of certain mineral elements, in particular, chlorides on the determination of this parameter results in an overestimation of the cod, the measurement of which remains negligible at the level of discharge. in addition, cod develops in the opposite direction with dissolved oxygen, indicating the likely use of oxygen for the degradation of carbonaceous material. kouinine station guarantees a satisfactory removal of cod and achieves maximum productivity of 75.10 %. figure 4. cod evolution iii.1.3. biological oxygen demand (bod5) monthly variations in bod5 content, during our monitoring, between upstream and downstream of treatment, are shown in figure 5. the average value of the pollutant load collected at the station is 303.55 mg/l. the concentration of bod5 in raw water can be explained by the existence of wastewater from urban agglomerations. however, we note that the maximum biodegradable organic pollution is eliminated by the station, the treated effluents are exhausted, with an average content of 33,55 mg/l. this output value tells us about the correct reduction of aerated basins with regard to carbon pollution. on the other hand, this reported bod5 value at the outlet matches the basic limit value for direct discharge to the algerian receiving environment (35 mg/l). figure 5 shows also an increase in bod5 in the waters of the station, especially during the (des-feb) time. the station receives raw water, rich in biodegradable organic matter and nutrients from the urban agglomerations of el-oued, bayadah, rabbah and kouinine. this triggers a large increase in the organic load of surface water in a small area. the increase in bod5 contents during the winter period can be explained by the effect of the large quantity of oils arriving at the purification station which forms a thick layer on the surface at low temperature, this layer is an obstacle to oxygen penetration during aeration, knowing that it is not equipped with an oil separator. this rise is correlated with the highest growth of bacterial abundance, and the decline in dissolved oxygen levels follows the absorption of the latter by micro-organisms. figure 5. bod5 evolution it is well known that the cod / bod5 ratio makes it possible to deduce whether the wastewater discharged directly into the receiving environment has the characteristics of domestic wastewater (cod / bod5 ratio less than 3), and the results of this work constitute an indication of the importance of pollutants that are little or not biodegradable. the average of this ratio dco/dbo5 during the 6 months of follow-up is equal to 2.9. range if it is lowered or increased, namely 70, 80, 90, 100, 110, 120, and 130%. based on figure 5, the 130% selling price variant shows the fastest payback period or pbp while the 70% selling price shows the longest pbp. the payback period (pbp) is faster if the selling price increases, and longer if the selling price is lowered. the profit obtained with the same production time, which is 14 years, shows that the higher the selling price, the greater the profit, and if the selling price decreases, the profits will be smaller. abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2020 page 50 iii.2. ss, dco and bod efficiencies the analysis of the physicochemical parameters of the raw and purified wastewater from the kouinine treatment plant gives us an idea of the purification yields, with rates of 77.76, 74.10 and 80% respectively for bod5, cod and ss. these three yields show a fairly good elimination of organic pollution and they interpret the correct operation of the station. interpret the correct operation of the station. figures 6, 7 and 8 show and prove these results. note that the efficiency of the purification of the organic load varies from one station to another depending on factors such as time, season, type of waste (urban and/or industrial). figure 6. evolution of ss in treated water over time figure 7. evolution of dco in treated water over time figure 8. evolution of dbo5 in treated water over time iv. conclusion monitoring the physicochemical parameters of raw and purified wastewater from the kouinine treatment plant allowed us to deduce that:  the purification yields reach values of 77.76, 74.10 and 80% respectively for bod5, cod and ss;  the average of this ratio cod/bod5 during the 6 months of follow-up is equal to 2.9. references [1] abderrahmane khechekhouche, boubaker benhaoua, zied driss, mohammed el hadi attia, muthu manokar, “ polluted groundwater treatment in southeastern algeria by solar distillation”, algerian journal of environmental and sciences. vol 6, no 1, 2020. [2] abderrahmane khechekhouche, boubaker benhaoua, muthu manokar, ravishankar sathyamurthy, abd elnaby kabeel, zied driss, “ sand dunes effect on the productivity of a single slope solar distiller”, heat and mass transfer journal. 2019. [3] abderrahmane khechekhouche, benhaoua boubaker, mruthu manokar, ravishankar sathyamurthy, abd elnaby kabeel, “exploitation of an insulated air chamber as a glazed cover of a conventional solar still”, heat transfer asian research. vol 48, no 5, pp. 1563-1574. [4] abderrahmane khechekhouche, zied driss, benjamin durakovic, “effect of heat flow via glazing on the productivity of a solar still”, international journal of energetica, vol. 4, no 2, 2019, pp. 54-57. [5] metahri mohammed saïd, “elimination simultanée de la pollution azotée et phosphatée des eaux usées traitées, par des procédés mixtes. cas de la step est de la ville de tizi-ouzou”, mémoire de doctorat, option: génie des procédés. université mouloud mammeri de tizi-ouzou. 2012 [6] j.vymazal, "removal of heavy metals in a horizontal sub-surface flow constructed wetland," journal of environmental science and health, vol. 40,,2005, pp. 37–41. [7] f. morari, n. d. ferro, e. cocco, "municipal wastewater treatment with phragmites australis l . and typha latifolia l . for irrigation reuse . boron and abderrahmane khechekhouche et al ijeca-issn: 2543-3717. december 2020 page 51 heavy metals”, water air soil pollut, vol. 56, 2015, pp. 226–240. [8] x. fan, b. cui, z. zhang, and h. zhang, “research for wetland network used to improve river water quality”, procedia environmental sciences, vol. 13, no. 2012, pp. 2353–2361. [9] m. meneses, h. concepcion, d. vrecko, r. vilanova, “life cycle assessment as an environmental evaluation tool for control strategies in wastewater treatment plants”, j. clean. prod. 2015, vol 107, pp. 653–661. [10] m. meneses, h. concepcion, r. vilanova, “joint environmental and economical analysis of wastewater treatment plants control strategies: a benchmark scenario analysis”, sustainability 2016, vol 8, no 360. [11] g. bonanno, “comparative performance of trace element bioaccumulation and biomonitoring in the plant species typha domingensis, phragmites australis and arundo donax”, ecotoxicology and environmental safety, vol. 97, pp. 124–130, 2013. [12] e. kalipci, “antimycobacterial activity of populus alba leaf extracts" , journal of medicinal plants research, vol. 29, no. 5, 2011, pp. 6571–6577. [13] miloudi, abdel monem, remini, boualame, “water potentiality of sustainable management challenges in the oued souf region, south-east algeria”, international journal of energetica, vol.1, no. 1, 2016, pp. 36-39. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 01-07 ijeca-issn: 2543-3717. december 2019 page 1 comparative study between fuzzy and sliding mode control based on a bdfig laid ouada, b. sebti electrical engineering department,university of batna 2, batna, algeria e-mail:ouada.laid@gmail.com abstract – brushless doubly fed induction (bdfig) is one of the best solutions of the previous research efforts about wind-power converter, which is represented by the absence of a brush gear and less maintenance cost, especially in the harsh regions. this task presents a comparative evaluation between a sliding mode and fuzzy control. it demonstrates also the robustness of these two regulators against supply voltage and load disturbances. furthermore, we have shown the undesirable phenomenon of oscillations having a finite frequency and amplitude, which is known as ‘chattering’ resulted from a sliding mode control which is based on lyapunov approach theorem. the control of the system and bdfig are both integrated in variable speed wind energy conversion. the performances of these control systems have been tested and analyzed in matlab simulink. keywords: brushless doubly-fed induction generator, neuro-fuzzy sliding mode control received: 12/11/2019 – accepted: 15/12/2019 nomenclature wind turbine q sc q sc d sp q sp vvvv ,,, stator and rotor d-q reference frame voltages emc rotor winding resistances q sc q sc d sp q sp iiii ,,, stator and rotor d-q reference frame currents spp total cyclic stators inductances d r q r q sc q sc d sp q sp  ,,,,, stator and rotor d-q reference frame flux spq number of pole pairs for power control scsp rr , stator winding resistances abbreviations rl total cyclic rotor inductance dfig doubly feed induction mcmp ll , magnetizing inductances bffig brushless doubly fed induction generator npc www ,, stators synchronous angular frequency dfig doubly fed induvtion generator rr number of pole pairs for power control bdfig doubly fed induvtion generator scsp ll , electromagnetic torque ann artificiel neural network cp active of stator powers smc sliding mode control pp reactive of stator powers nf smc neuro fuzzy sliding mode control mailto:ouada.laid@gmail.com abder image placée laid ouada et al ijeca-issn: 2543-3717. december 2019 page 2 i. introduction during the last years, there was a considerable exploitation of wind power energy which was expected to supply 5% of electrical global power during 2016, it suggests an approximation of 25%by the end of 2020 [1]. undoubtedly, the doubly fed induction (dfig) has become the most useful model in wind power application. but because of the presence of slip ring and brushes which requires more control and maintenance; therefore, it limits its application in harsh environment [2,3]. in this way, the emerging of bffig has made up for many drawbacks of usual electric machines, as being brushless and without slip ring. brushless doubly fed induction generator (bdfig) includes a stator which incorporates two sets of three phase windingwith different number of poles. the first is connected directly to the electrical grid, named the power winding (pw). the second is laid through a bidirectional converter to the grid, called control winding (cw)[3,4]. the rotor of bdfig consists of specially designed nested loops which may be connected or separated from each other aspresented in the following figure 1. the fuzzy logic control has been considered as one of the most successful expert systems which has been widely applied in control applications. [5]. as it doesn’t require a detailed mathematical model, it just uses the knowledge of the total operation of the system to build its based rule. the sliding mode control strategy is determined by the sum of two control laws: switching and equivalent it achieves robust control by adding a discontinuous control law [6,7].signal across the sliding surface, satisfying the sliding condition. nevertheless, this type of control has an usual disadvantage, known by the ''chattering'' phenomenon due to the discontinuous control action [8]. figure. 1. configuration of a bdfig ii. modeling of the brushless doubly fed induction generator the general relationships between these amounts as well as the electrical speed of the rotor for the 50 hz system is (1) the expressions for states' and rotor flux connections are given by the following equation: (2) electromagnetic torque of the wind turbine is given as: (3) iii. field oriented control of bdfig the surface orientation power machine has been selected so as to obtain a good decoupled control. [4] and . the obtained control strategy for the bdfm resembles to the well-known stator field orientation control used in the(bdfim). by neglecting resistances of the stator phases the stator voltage will be expressed by: (4) the stator active and reactive power can be written according to the stator currents as: (5) the stator active and reactive power and voltages are given by: (6)         ncppc pnpr p pp p    )( 502 laid ouada et al ijeca-issn: 2543-3717. december 2019 page 3 where: the block-diagram representing the internal model of the system is presented in figure 2. the input blocks relating represent the simplified stator converter model. knowing equations (5) and (6), it is then possible to synthesize the regulators. figure.2. block diagram of the power system iii.1 fuzzy control fuzzy controllers are non-conventional linear controllers. they can give satisfactory results if they are built correctly using the schema of the system operator. their design is composed of: (1) determining the inputs, (2) establishing rules and (3) the method of calculation to convert the rules in a net output signal, known adefuzzification. first of all, the input index in this case is the error and the variance ratio. the error index is estimated and based on the net value the signal; it can be expressed in terms of degree of composition of fuzzy sets. the shape of fuzzy sets can be determined by the expert knowledge of the system. the following step is to build the fuzzy rules, again based on the expert knowledge of control problems, to accommodate all possible combinations of memberships [6]. figure.3. structure of fuzzy logic controller figure.4. membership functions for inputs and output table 1. rule table of the fuzzy controller e/δe bn sn az sp bp bn bn bn bn bn az sn bn sn sn az sp az sn sn az sp sp sp sn az sp sp bp bp az sp bp bp bp input membership function output membership function + + + + + + + + + + b d f ig laid ouada et al ijeca-issn: 2543-3717. december 2019 page 4 figure.5. block diagram of bdfig fuzzy control scheme iii.2. sliding mode control in order to improve and enhance the response of our system; we add another loop sliding mode. this type of control appeared for the first time in the soviet union during the sixties, it proved a great success in the recent years because it is easily used in industries. this control is known by its robustness in the system. this control aims to force the system to reach a vicinity of the sliding surface and stay at this level [9]. so, we wanted to compare between these mode commands and another one to benefit from their advantage. iii.3. witching surface switching function, the design of control system will be demonstrated for a following nonlinear system [8]: (8) where: is the state vector, is the control vector, . it's possible to define a set s of the state trajectories x such as: (9) the following two conditions have to be satisfied: the control law satisfies the precedent conditions is presented in the following form: (10) where is the control vector, is the equivalent control vector, is the switching part of the control (the correction factor), k is the controller gain. can be obtained by considering the condition for the sliding regimen, . the equivalent control keeps the state variable on sliding surfaces, once they reach it: figure.6. sliding mode control block (11) the sliding surface proposed by j.j. slotine is used in this work: (12) : is a positive coefficient, : is the error. : is the desired state. n: is the system order. iii.4. direct power control (dpc) with smc of a bdfig in this section, the sliding surfaces are designed based on the active and the reactive power references given in the eq. (5). the objective of this design is to independently control the active and reactive generated powers converts. a-choice of the sliding surfaces control the expressions of the stator voltages according to the stator currents: ( 13) the surface of the control current is defined by: (14) b-conditions of convergence of this control to guarantee the convergence of selected variables towards the references, the two slip surfaces need to be null as following (15) + + + + + + + + + + + + + b d f ig d laid ouada et al ijeca-issn: 2543-3717. december 2019 page 5 the condition of a sliding mode control base on lyapunov attractively and the surface current time invariance for n = 1, the surface of the current control can be set from the equation as follow _ _ ( ) ( ) q q ref q sc sc sc d d ref d sc sc sc s i i i s i i i          (16) cthe control voltage and sign function law satisfy is presented in the following form (17) with: are the control vectors relation. are the equivalent control vectors relation. are the switching control. : are positive constant. finely the equivalent control voltage control is given by: (18) the bdfig global sliding-mode control are presented in figure 7 figure.7. block diagram of bdfig sliding mode control scheme iv. simulation results table 2 shows the electrical parameters of bdfig table 2. the electrical parameters of bdfig rated voltage pole pairs number resistance(ω) selfinductance(mh) mutual inductance(mh) nominal power synchronous speed 78.3 rad/s v. system results and discussions the results obtained are a comparison between two controls fuzzy and sliding mode control, respectively organized according to the following figures. the active power curve in figure 8 illustrates that the fuzzy control which ensures high optimization of the extracted power and greatly reduces the fluctuation around optimal value, it can be also clearly seen that fuzzy controller demonstrates more performance than sliding mode control. 0 1 2 3 4 5 -2000 0 2000 s ta to r a c ti v e p o w e r (w ) 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 -3000 -2000 -1000 0 time(s) p-ref p-smc p-ref p-flc figure.8. active a power response of stator (pw) in the figure 9, the reactive power is set to (0var), it had been observed that the two controllers have similar results, but the problem of chattering is evident in sliding mode controller curve and proves that fuzzy control is more robust and provides better performance. it can be laid ouada et al ijeca-issn: 2543-3717. december 2019 page 6 observed that the stator voltage and current are in opposite phases figure 10, which shows that the machine is operating in a generation mode (cosφ = – 1). after seeing the good tracking of the proposed set-points illustrated in figure 9, the robustness of the structure of control against the incertitude of parameters should be checked. 0 1 2 3 4 5 -1000 0 1000 r e a c t iv e p o w e r ( v a r ) 1.48 1.49 1.5 1.51 1.52 1.53 1.54 -1000 -500 0 500 time(s) q-ref q-smc q-ref q-flc figure.9. reactive a power response of stator (pw) 0 1 2 3 4 5 -20 0 20 s t a t o r p o w e r c u r r e n t a n d v o lt a g e 1.1 1.15 1.2 1.25 1.3 1.35 1.4 -20 0 20 time(s) ispa 0.04*vsp figure.10. stator (pw) voltage and current figure 11 illustrates the change of the variable speed in step form as follows when the speed is changed between 78 at the super-synchronized speed 86 rad /s to be reduced to76 rad / s. we observed in the figure 6 the active power is varied between – 1200 w, – 1800 wand in – 1800 w it remains respectively stable at 1.5 s and 3s while the reactive power is fixed at 0 var, from where the good tracking of the proposed control can be noted more clearly in the figure 8 in comparison to the figure 9. 0 1 2 3 4 5 1 1.2 1.4 1.6 1.8 2 2.2 2.4 time(s) r s c (o h m ) rsc rsc 2*rsc figure.11. parameter variation vi. conclusion in this paper, we described two controls of the wind energy system equipped with brushless doubly fed induction generator. at first, we proposed a mathematical model of the machine and generator in the form of the diagram. then, we presented two strategies based on fuzzy and sliding mode control. the machine obtained a good performance with the fuzzy logic control even in the appearance of variations on target, and has high-power output efficiency. finally, the fuzzy control has approved its robustness against speed variations in comparison with the sliding mode control that gives undesirable results. references [1].ren21. (jan. 2017). renewables 2016: global status report (gsr). [online].available:http://www.ren21.net [2].c. liu d. xu and x. zhang "dynamic performance of brushless doubly-fed induction generator during symmetrical gridfault" power electronics and ecce asia (icpe & ecce) 2011 ieee 8th international. [3].yang, jian, “sensorless control of brushless doubly fed induction machine using a control winding current mras observer”, ieee transactions on industrial electronics, vol. 66, n°1, 2019, pp. 728-738. [4]. cheng, ming, rensong luo, and xinchi wei. "design and analysis of current control methods for brushless doubly fed induction machines." ieee transactions on industrial electronics, vol. 66, n°1, 2019, pp. 717-727. [5].dong, hao, “research on double-fed induction generator low voltage ride through based on double braking resistors using fuzzy control”. energies vol. 11, n°5 2018, pp. 1155. [6]. zou, yu, “a new decoupled rotlin motor with fuzzy sliding mode control”. ieee transactions on magnetics (2018). http://www.ren21.net/ laid ouada et al ijeca-issn: 2543-3717. december 2019 page 7 [7]. r cheikh, a menacer, s. drid, “robust control based on the lyapunov theory of a grid-connected doubly fed induction generator”. frontiers in energy, 2013, vol. 7, n°2, pp. 191–196. [8 y].bekakra, d. ben attous, “ dfig sliding mode control fed by back toback pwm converter with dc-link voltage control for variable speed wind turbine”. frontiers in energy, 2014, vol. 8, n°3, pp.345–354 [9]. j. lo, y. kuo, “decoupled fuzzy sliding mode contro”l, ieee trans. fuzzy syst., vol. 6, n°. 3, 1998pp. 426-435. i. introduction ijeca-issn: 2543-3717. june 2021 page 18 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 18-24 influence of the geographical parameters on the performance of hybrid solar gas turbine omar behar 1,2 , basim belgasim 3 , 4 daniel sbarbaro 1,2 , luis moran 1,2 1 solar energy research center (serc-chile), santiago de chile, chile 2 department of electrical engineering, university of concepcion, concepcion, chile 3 center for solar energy research and studies, tripoli, libyia 4 mechanical engineering department, university of benghazi, benghazi, libyia email* : beharomar@gmail.com abs tract – this study aims to investigate the influence of the geographical and climate parameters on the performance of the hybrid solar gas turbine with a pressurized air receiver. a number of sites located in south america (chile, bolivia, and peru) and north africa (algeria and libya) are considered. the geometric design parameters of the solar receiver and the tower are calculated using an in-house code. the layout and the optical performance of the heliostat field are carried out using solarpilot software. the si mulation of the complete hybrid solar gas turbine is carried out using trnsys software. a 50 m we hybrid solar gas turbine is chosen in this study. results show that a hybrid solar gas turbine installed in north africa performs better than that installed in south america. this is mainly due to the optical performance of the heliostat field, which are better in north africa are than in south america. the highest annual optical efficiency of a solar field is observed at bechar (algeria) 56.8% while the lowest annual efficiency is observed at antofagasta (chile) 48.1%.the solar-to-electric efficiency at atacama desert is lower than in the sahara desert. indeed, in atacama region the solar -to-electric efficiency varies from 17% at antofagasta to about 18% in arequipa while it is above 19% at sabha and bechar. keywords: solar energy, hybrid solar gas turbine, solar thermal power plants, concentrating solar power, solarpilot, trnsys. received: 30/04/2021 – accepted: 15/06/2021 i. introduction concentrating solar power has attracted a lot of interest due to its potential for integration with the conventional power conversion cycles including rankine cycles and brayton cycles [1]. the integration of the central rece iver system with the brayton cycles and combined cycles offers several advantages including high solar to electric conversion efficiency and scalability [2]. the concept that integrates the central receiver system with the brayton cycle is known as hybrid sola r gas turbine (hsgt ). in a typical hsgt, concentrated solar heat is used to preheat the compressed air prior to combustion. three research pro jects name ly solgat e [3–5], solhyco [6], and solugas [7, 8] have demonstrated the hsgt technology. in sma ll scale systems, the hsgt technology has been studied intensively by many researchers. researchers have investigated the performance of mic ro hsgt systems under different operation conditions [9]. http://www.ijeca.info/ http://www.ijeca.info/ mailto:beharomar@gmail.com omar behar et al ijeca-issn: 2543-3717. 𝑦 √𝜃r𝑒𝑐 .𝜋2.𝐻𝖶𝑅r𝑒 𝑐 page 19 the performance of the gt based on a parabolic concentrator has been analysed for solar only and hybrid 𝑃𝑛𝑜𝑚_𝑟𝑒𝑐 = 𝑆𝑀.𝑃𝑛𝑜𝑚_𝑝𝑏 𝑦𝑛𝑜𝑚_𝑝𝑏 (1) operation [10]. technica l, economic and environ mental evaluation including therma l design were presented by an in-depth study [11]. thermo-economic modelling and simu lation were also provided [12]. the effect of in let temperature on the performance of sma ll scale hsgt systems were presented [13]. a thermodynamic and cfd modelling were presented for a small scale hsgt power where sm is the solar mult iple, p re fers to power, and η refe rs to the efficiency. subscripts “nom” and “pb” refer to nominal and power block respectively. the inc ident receiver power on the receiver fro m the heliostat field is a function of the receiver nominal efficiency: generation unit [14]. a sma ll scale solar tower integrated with gas turbine system has been presented [15]. behar investigated an innovative design for the the preheating 𝑃𝑛𝑜𝑚_𝑟𝑒𝑐_ i𝑛𝑐 = 𝑃𝑛𝑜𝑚_ r𝑒𝑐 𝑛𝑜𝑚_r𝑒𝑐 (2) system of the hsgt p lants [16]. also, a therma l analysis of hsgt system integrated with parabolic d ish collector was presented by a group of researchers [17]. a study investigated the domestic applications of the small scale subscripts “rec” and “inc” refer to the receiver and incident power respectively. the average allowable flux is calculated as: hsgt systems based on axial turbine system [18]. investigation predicted the simulation procedure of the 𝐹𝑎𝑣g = 𝐹𝑝𝑒𝑎𝑘 𝐹𝑅 (3) performance of the hsgt systems [19]. regarding to large scale hsgt systems, there is a c lear shortage in the studies and research based on the previous literature. recently study suggested a design methodology for the where favg is the average heat flux, fpeak is the peak heat flux, and fr is the peak-to-average heat flux ratio. the receiver area is calculated as: 𝑃𝑛𝑜𝑚_ i𝑛𝑐 solar field of the large scale hsgt systems [20]. the study included modelling and simulation validated by 𝐴𝑟𝑒𝑐 = 𝐹𝑎𝑣𝑔 (4) real data from a case study. the radius of the receiver is given as: this paper aims to investigate the influence of the geographical and climate parameters on the performance of commercial hsgts integrated with heliostat solar 𝑅𝑟𝑒𝑐 = 𝐴r𝑒𝑐 𝜋 (5) filed and central pressurized air receiver. a nu mber of sites located in south america and north africa a re selected. a simp lified methodology is adopted to design the solar filed of each site and the optical performance is predicted using solapilot simu lation tool. the whole system is modelled using the well-known energy simulation tool trnsys 18 using the input data from where: θrec is the opening angle of the cavity. hwrrec is the height to width ratio of the receiver. the height of the receiver is: 𝐻𝑟𝑒𝑐 = 2. 𝑅𝑟𝑒𝑐. 𝐻w𝑅𝑟𝑒𝑐 (6) the width of the aperture of the receiver is the design process and optical analysis for each of the proposed locations of the study. w𝑎𝑝 = 2. 𝑅𝑟𝑒𝑐 . cos (𝜋−𝜃r𝑒𝑐) . awr (7) 2 ii. methods and tools ii. 1 . a practical technique to design the solar receiver and the tower the central receiver system includes the heliostat fie ld, the solar receiver, and the tower. a pract ical technique is used to design the solar receiver and the tower. a cavity-type receiver is considered in this study. the nominal powe r of the receiver can be ca lculated using the following expression: where: awr is the aperture width to total width ratio. the aperture height is 𝐻𝑎𝑝 = 2. 𝐻𝑟𝑒𝑐. 𝐴𝐻𝑅 (8) where: ahr is the aperture he ight to total height ratio. the tower height is estimated using the following expression: 𝐻𝑡𝑜w𝑒𝑟 = 0.6806. 𝑃𝑛𝑜𝑚_𝑟𝑒𝑐 + 106.60 (9) pnom_rec is in mw is the above equation. omar behar et al ijeca-issn: 2543-3717. page 20 ii. 2 . the tool used to design the heliostat field solarpilot is used to design the heliostat field. solarpilot software is dedicated to design and estimate the performance of the central rece iver systems. it was developed as an extension to delsol3 with several improve ments in the he liostat field layout, characterizat ion, para metric simu lation, plotting, and optimization of the centra l receiver system. it uses the analytical flu x image he rmite series approximat ion and applies the analytical model to individual he liostat images. in addit ion, it uses a monte-carlo ray-t racing technique for the optical modeling of the solar receiver. ii. 3 . the tool used to design the simulate the complete system trnsys is used to simu late the performance of the hsgt. t rnsys is a simu lation tool of time -dependent energy systems. it has a solar library, wh ich includes some solar concentrating collectors such as the parabolic trough concentrator and central rece iver system. the lib rary na med sola r therma l electricity co mponents (st ec) is useful to model and simulate the hsgt. it includes rankin and bryton cycles in addit ion to the central rece iver system. the hsgt mode l is illustrated in figure 1. it consists from three weather data file, heliostat solar field, centra l pressurized air receiver and briton cycle components. figure 1. t rnsys model of hsgt syst em. iii. results and discussions the locations proposed to be considered in this study are de monstrated in tab le 1 including the country, latitude, longitude and time zone. t able 1. select ed locat ions for t he st udy c ou ntry ti me z on e c h i le ant ofagasta ( 23°39'3.34"s 70°23'51.01"w) ele 16m gmt -4 pe ru arequipa-characa ( 16°30'26.19"s 71°31'15.30"w) ele 2782m gmt -5 bol ivi a oruro-juan-mendoza ( 17°57'48.24"s 67° 4'23.77"w) ele 3709m gmt -4 al ge ria bechar ( 31°37'25.72"n 2°12'58.48"w) ele 791m gmt +1 li bya sebha ( 27° 2'11.55"n 14°25'44.49"e) ele 426m gmt +2 iii. 1 . results of heliostat field and receiver design to calculate the geo metric design para meters of the tower and the receiver, the nominal e ffic iency of the gt is taken as 37%. the no mina l efficiency of the receiver is 80% . the rece iver is supposed to be built with incoloy 800h. the allowab le peak flu x is 1000 kw/m 2 . a pea k to average flu x ratio of 1.78 is considered. the opening angle of the rece iver is 180°. the aspect ratio of the receiver (height to diameter ratio) is 1.27. the ratio of the height of the aperture to the height of the receiver is 0.9. the rat io of the width of the aperture to the total width of the rece iver is 0.9. the solar mu ltip le sm=1. table 2 illustrates the design para meters of the central rece iver system for a hybrid solar gas turbine of 50 mwe. the nominal power o f the receiver is 135.14 mwth, its absorptive surface is 300.68 m 2 . the aperture of the rece iver is a rectangle of 11.20 m in height and 8.8 m in width. the height of the tower is 198.57 m. the reflective surface of the heliostat field is 248776.02 m 2 . t able 2. design parameters of a heliostat field system for 50mwe solar gas t urbine. parameter u n i t val u e nominal power of the receiver mw 135,14 p ower int ercept on t he receiver mw 168,92 receiver absorbt ive surface m 2 300,68 receiver height m 12,44 radius of t he receiver m 4,90 widt h of the aperture m 8,80 height of t he aperture m 11,20 apert ure area m2 98.71 height of t he tower m 198,57 reflect ive surface of t he solar field m2 248776,02 omar behar et al ijeca-issn: 2543-3717. page 21 the layout and the optical perfo rmance of the heliostat fie ld are carried out using sola rpilot software. this software requires main ly the data of the location, the dimensions of a single heliostat, the geometric dimensions of the receiver and the tower, and the optical proprieties of the heliostat and the receiver. figure 2 shows the layout and the annual optical efficiency of the heliostat field installed at the selected sites. the layout method is radia l stagger and the sun location at the design point is the summer solstice. figure 2a. layout and average annual optical efficiency of the solar field inst alled at bechar, algeria. figure 2b. layout and average annual optical efficiency of the solar field inst alled at oruro, bolivia. figure 2c. layout and average annual optical efficiency of the solar field inst alled at antofagasta, chile. figure 2d. layout and average annual optical efficiency of t he solar field inst alled at sebha, libya. figure 2e. layout and average annual optical efficiency of the solar field inst alled at arequipa, p eru. table 3 illustrates the nominal and annual optical efficiencies of the heliostat field at each site. there is a slight diffe rence between the nominal effic iencies of the heliostat fie ld at the selected locations. it varies fro m 59.5% at sebha (libya) to 62.1 at arequipa (peru). however, there is a significant difference between the annual optical effic iencies. the annual optical e ffic iency of a heliostat field installed in no rth africa is so much higher than the annual optical efficiency of a heliostat fie ld installed in south a merica. the highest annual optical effic iency of a solar fie ld is observed at bechar (algeria) 56.8% fo llo wed by sebha (libya) 56.2 %. the lowest annual effic iency is observed at antofagasta (chile) 48.1%. t able 3. t he nominal and annual optical efficiency of the heliostat field at different locat ions. locat ion count ry nominal opt ical efficiency (%) annual opt ical efficiency (%) bechar algeria 60.9 56.8 oruro bolivia 61.5 49.9 ant ofagasta chile 59.1 48.1 sebha libya 59.5 56.2 arequipa p eru 62.1 50.3 omar behar et al ijeca-issn: 2543-3717. page 22 figure 3 shows the heat flu x distribution at the receiver aperture, on march 21 st at noon, for the five selected sites. the direct norma l irrad iance is 1 kw/ m 2 . the average heat flux at the receiver’s aperture varies fro m 1147.6 to 1421.9 kw/m 2 . this corresponds to an average heat flu x on the receiver’s absorptive surface of 376.26-463.28 kw/m 2 . figure 3a. heat flux dist ribution at t he aperture of t he solar receiver for t he case of bechar (algeria) figure 3b. heat flux dist ribut ion at the aperture of the solar receiver for t he case of oruro (bolivia) figure 3c. heat flux dist ribution at t he aperture of t he solar receiver for t he case of antofagasta (chile) figure 3d. heat flux dist ribut ion at the aperture of the solar receiver for t he case of sebha (lybia) figure 3e. heat flux dist ribution at t he aperture of t he solar receiver for t he case of arequipa (p eru) iii. 2 . results of the complete hsgt system the siemens sgt-800 gas turbine system of capacity 50 mwe is used as a case study in this work. the brayton cycle design and operation parameters of this type of gas turbine is shown in table 4. t able 4. gas t urbine t echnical dat a. parameter val u e out put power iso 50.5 mwe elect rical efficiency 38.3% heat rat e 9,407 kj/kwh compressor pressure ratio 21.1:1 exhaust gas flow 134.2 kg/s t urbine inlet temperature 1237.6 °c exhaust t emperature 553 °c the hsgt system is simulated based on the results of the solar fie ld and centra l rece iver obtained in the previous section. these results are integrated with the design and operation parameters of sgt -800 gas turbine in the t rnsys model. the gas turbine cycle e ffic iency of the all locations is presented in figure 4. it can be noticed that the gas turbine effic iency at atacama desert (che li, pe rue and bo liv ia) is higher than sahara region (algeria and libya) in which it is 40% and 39% respectively. this result is due to the fact that the annual omar behar et al ijeca-issn: 2543-3717. page 23 average ambient temperature at atacama locations is lower than at sahara desert as can be seen in table 5. figure 4. gas t urbine efficiency for the all locations t able 5. average annual ambient t emperat ure. locat ion average t emperature oruro-bolivia 5.8 °c ant ofagasta-chile 16.8 °c arequipa-p eru 14.7 °c bechar-algeria 22.4 °c sebha-libya 23 °c figure 5 de monstrates the solar-to-electric efficiency of the hsgt system fo r the all locations. it can be noticed that the solar-to-electric effic iency at atacama desert is lowe r than in the sahara desert. in more details, in atacama region the solar-to-electric e fficiency varies fro m 17% at antofagasta to about 18% in arequipa. on the other hand, the efficiency of sabha and bechar is above 19.5%. the reason behind this is e xpla ined in the previous section in which the optical effic iency of the heliostat field in sahara desert is higher than in the atacama region. figure 5. solar-t o-elect ric efficiency of hsgt iv . conclusion this paper investigated the influence of the location on the performance of the hybrid solar gas turbine. an inhouse code and two co mmerc ia l software were used to provide a co mprehensive study. results showed that the location has a strong influence on the layout and the annual optical efficiency of the heliostat field. the annual optical efficiency of a heliostat field in north africa is higher than that in south america. the highest annual optical effic iency of a solar fie ld is observed at bechar (56.8% ) while lowest is observed at antofagasta (48.1%). however, because of the lo w a mbient temperature at atacama, the gas turbine effic iency at in chlie, perue and boliv ia is higher than sahara (algeria and libya). overa ll, the solar-to-e lectric e ffic iency at atacama is lower than in the sahara desert. in ataca ma the solar-to-electric e ffic iency varies fro m 17% to 18% while in sahara it is above 19%. acknowledgements this work was supported by la agencia nacional de investigación y desarrollo (anid), project nu mber anid/fondap/ 15110019 “ solar ene rgy research center” serc-chile. references [ 1] b. belgasim, y. aldali, m . j. r. abdunnabi, g. hashem, and k. hossin, “the p otential of concentrating solar p ower (csp) for electricity gen eration in liby a,” renewable and sustainable energy reviews, vol. 90. 2018, p p . 1–15. [ 2] o. behar, a. khellaf, and k. m ohammedi, “a review of studies on central receiver solar thermal p ower p lants,” renew. sustain. energy rev., vo l. 23, 2013, p p . 12–39. [ 3] p. heller et al., “test and evaluation of a solar p owered gas turbine sy stem,” sol. energy, vol. 80, no. 10, 2006, p p . 1225–1230. [ 4] p. schwarzbözl et al., “solar gas turbine sy stems: design, cost and p ersp ectives,” sol. energy, vol. 80, no. 10, 2006, p p . 1231–1240. [ 5] “solgate solar hy brid gas turbine electric p ower sy stem. technical rep or,” 2005. [ 6] “solar-hy brid power and cogeneration plants (solhyco),” 2011. [ 7] m . quero, r. korzy nietz, m . ebert, a. a. jiménez, a. del río, and j. a. brioso, “solugas op eration exp erien ce of the first solar hy brid gas turbine sy stem at m w scale,” in energy procedia, vo l. 49, 2014, pp. 1820–1830. omar behar et al ijeca-issn: 2543-3717. page 24 [ 8] r. korzy nietz et al., “solu gas comp rehensive analy sis of the solar hy brid bray ton p lant,” sol. energy, vol. 135, 2016, p p . 578–589. [ 9] b. ssebabi, f. dinter, j. van der sp uy , and m . schatz, “predicting the p erformance of a micro gas turbine under solar-hy brid op eration,” energy, vol. 177, 2019, p p . 121–135. [ 10 ] s. semp rini, d. sán chez, and a. de pascale, “performance an aly sis of a micro gas turbine and solar dish integrated sy stem under different solar-only and hy brid op erating conditions,” so l. energy, vol. 132, 2016, p p . 279–293. [ 11 ] m . babaelahi and h. jafari, “analy tical design and optimization of a new hy brid solar-driv en micro gas turbine/stirling en gin e, based on exer goenviro economic concep t,” sustain. energy technol. assessments, vol. 42, 2020, p p . 100845. [ 12 ] m . c. cameretti, r. de robbio, e. pirone, and r. tuccillo, “thermo-economic analy sis of a hy brid solar micro gas turbine p ower p lant,” in energy procedia, vol. 126, 2017, p p . 667–674. [ 13 ] m . amelio, m . s. pèrez, v. ferraro, f. rovense, and s. bova, “dy namic simulation of the temp erature inlet turbine control sy stem for an unf ired micro gas turbine in a concentrating solar tower.,” in energy procedia, vol. 148, 2018, p p . 712–719. [ 14 ] m . c. cameretti, g. lan gella, s. sab ino, and r. tuccillo, “m odeling of a hy brid solar micro gas turbine p ower p lant,” in energy proced ia, vol. 82, 2015, p p . 833–840. [ 15 ] a. giostri, m . binotti, c. sterp os, and g. lozza, “small scale solar tower coup led with micro gas turbine,” renew. energy, vol. 147, 2020, p p . 570–583. [ 16 ] o. behar, “a novel hy brid solar p reheating gas turbine,” energy convers. manag., vo l. 158, 2018, p p. 120–132. [ 17 ] a. giostri, “preliminary analy sis of solarized micro gas turbine ap p lication to csp p arabolic d ish p lants,” in energy procedia, vol. 142, 2017, p p . 768–773. [ 18 ] a. m . daabo, k. e. hammo, o. a. m ohammed, a. a. hassan, and t. lattimore, “performance inv estigation and design op timization of micro scale comp ressed air axial turbine for do mestic solar p owered bray ton cy cle,” sustain. energy technol. assessments, vo l. 37, 2020, p p . 100583, feb. [ 19 ] g. barigozzi, g. bonetti, g. franchini, a. perdichizzi, and s. ravelli, “thermal p erformance p rediction of a solar hy brid gas turbine,” sol. energy, vol. 86, no. 7, 2012, p p . 2116–2127. [ 20 ] b. belgasim, o. b ehar, m . abdunnabi, and f. m ohamed, “m odeling and simulation of a lar ge-scale hy brid solar gas turbine with p ressurized air receiver,” in 11th international ren ewable energy congress, irec 2020, 2020. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 60-64 ijeca-issn: 2543-3717. december 2021 page 60 organometallic perovskite solar cell mohammed lakhdar ayachi 1* , atman benhaoua 1 , ali tliba 2 , belgacem souyei 3 1department of physics, faculty of exact science, university of el oued, algeria 2lab. vtrs, faculty of exact science, university of el oued, algeria 3department of chemistry, faculty of exact science, university of el oued, algeria email*: ayachi-mohammedlakhdar@univ-eloued.dz abstract –halide organometallic perovskite has an important role in the efficiency increase of the solar cell. thus in this work, we formed the basic nucleus of the organic perovskite, and we studied its morphological properties. the x-ray diffraction result shows that this compound is consistent, homogeneous, and has preferential orientation growth be at (100) plane, which means that the experimental conditions which we worked on were optimal. after adding both tin iodide and methylamine chloride in organic solvents (dmf and dmso). deposited this mixture by spray pyrolysis method at specific temperature 120c°, on the glass substrate, a thin black layer formed; the result of x-ray diffraction on this latter layer showed that it is a spectrum of perovskite compound, which has preferential orientation growth be at (110) plane. via optical proprieties, it found that has low gap energy of 1.78 ev, and transmittance of 1,6% furthermore it has a high absorption coefficient of 8.104 cm-1, in the visible domain. but it has a relatively high value of auerbach energy 0.6 ev due to the crystal defects. so this compound could be an active layer in the solar cell. keywords: auerbach energy, optical and morphological properties, x-ray diffraction, crystal defects. received: 05/10/2021 – accepted: 20/12/2021 i. introduction hybrid organic perovskite has the same structure as mineral perovskite (abx3) [1]. but a is organic cations such as methylammonium, formamidinium, or rare-earth elements as cs. b is ions of heavy metal as (pb+4, sn+4) [2,3]. as for the x can be (cl-br-i-f) [4]. hybrid organic perovskite has a wide range of applications in electrical engineering such as gas sensors and light-emitting diode (leds) [5], but the most important applications are in solar cells [6]. the solar energy conversion efficiency of perovskite solar cells is over high 25%. the preparation methods of these compounds in the laboratories have a major impact on the energy conversion efficiency of these cells [7]. the major obstacle facing relying on these compounds to convert solar energy is instability [8], this due to several factors including humidity [9] and asymmetry between fundamental compounds. halide perovskite has several kinds, among them we find (ch3nh3pbi3) which has black color and many applications but contains lead which is hazardous on human and deteriorate rapidly [10, 11]. and there is another kind has formula (ch3nh3pbcl3) also contains lead with white color but doesn't have greater applications because of the big gap of energy 3.1 ev [12], this latter type has good propriety that it doesn't deteriorate quickly because the basic nucleus is methylammonium chloride (ch3nh3cl). another type of compound less hazardous on humans and has high efficiency conversion of solar energy, is (ch3nh3sni3) has black color with small gap energy of 1.3 ev but it deteriorates very quickly [13]. there are great researches efforts about the instability of active compounds, without forgetting the simulation studies by several software specialized in the field [14, 15]. https://www.ijeca.info/ mailto:ayachi-mohammedlakhdar@univ-eloued.dz mohammed lakhdar ayachi et al ijeca-issn: 2543-3717. december 2021 page 61 the novelty of our work is combining between two properties structure stability and high efficiency conversion of energy, by preparing (ch3nh3sni2cl) and depositing on glass layer by using spray pyrolysis technique where we prepared methylammonium chloride (ch3nh3cl) in our lab and we studied the morphological structure and add tin iodide sni2 to methylammonium chloride and we study some optical and structural parameters of a new compound. ii. method and experience in the first step, ch3nh3cl was synthesized by mixing 30 ml of methylamine solution (40% in methanol) and 32.3 ml of hydrochloric acid solution (57% by weight in water) in a flask at 0°c in an ice medium for 2 hours with constant stirring. then put the solution overnight at 60°c, take the solution, and put in the rotavaporator we got white precipitate. finally, we wash with diethyl ether two or three times and then let this white precipitate at 70°c until dry. in the second step, we take 0.5g of ch3nh3cl and 1.2 g of sni2 were mixed in 15ml dmso because methylammonium chloride does not easily solute in dmf, then put the mixture at 60°c overnight with constant stirring. afterward, the small beaker was sealed and kept dark at room temperature to avoid reaction with sunlight. after this work we deposit the second compound over the glass layer by using the spray pyrolysis technique at 120°c, we note a brownish-red precipitate on the substrate, afterward heat treating for this second compound at 180°c, until the brownish-red color turns to black. finally, we get organic perovskite thin film as shown in figure 1 [16, 17]. figure 1. organic perovskite thin film iii. result and discussion iii.1 structural proprieties figure 2 shows the x-ray diffraction spectra of methylaminechloride ch3nh3cl use proto axrd device estimated wavelength kα of cu (0.15405nm) scans angular interval between 10 80 degree. the peaks which are appeared in ch3nh3cl at 2θ: 17.75 °, 27.4°, 29.7°, 35.15°, 42.05° , 56.3° , 58.29° , compatible to crystal levels of (100), (111), (310), (210), (224), (320), (321). based on previous studies prove the formation of first compound (ch3nh3cl) has tetragonal form. so, the obtained curve demonstrates that the compound has polycrystalline structure in form tetragonal the sharp peak correspond with plan (100) indicates to best crystallization means that preferential orientation be at (100) plan compared with other plans. figure 2. x-ray diffraction spectrum of ch3nh3cl powder the peaks which are appeared in the second compound as shown in figure 3 (ch3nh3sni2cl) at 2θ: 14.01, 21.964, 31.4, 34.61, 41.3, compatible with crystal levels (110), (014), (112), (200), (224 ). based on previous studies prove the formation of the second compound (ch3nh3sni2cl) has a tetragonal form. thus, the obtained curve demonstrates that the compound has a polycrystalline structure in tetragonal form, the sharp peak corresponding with a plan (110) indicates to best crystallization means that compared with other plans. the assigned (110) and (220) peaks confirm the perovskite phase. diffraction peaks have a good corresponding with the previous articles. both perovskite and methylamine chloride powder have tetragonal forms. for selecting inter-reticular distance dhkl and grid constants a and c, we used the following relations [18, 19]. mohammed lakhdar ayachi et al ijeca-issn: 2543-3717. december 2021 page 62 table 1 summarizes some parameters among them dhkl, 2θ, grid parameters, and miller indexes. 2 2 2 2 2 2 2 sin( ) 1 1 ( ) hkl hkl d n l h k d a c      (1) figure 3. x-ray diffraction spectrum of ch3nh3sni2cl thin films table 1. ch3nh3sni2cl and ch3nh3cl parameters:, dhkl, grid parameters, miller indexes compound (hkl) 2θ dhkl(a) a(å)= b(å) c(å) ch3nh3cl 100 17,75 4,995 9,9901 12,8972 111 27,4 3,2538 6,5076 8,4013 310 29,7 3,00688 6,0137 7,7637 210 35,15 2,5521 5,1042 6,5895 224 42,05 2,1479 4,2958 5,5459 321 58,29 1,5822 3,1645 4,0854 ch3nh3sni2cl 110 14,01 6,31899 12,6379 16,3155 014 21,964 4,0453 8,0906 10,4449 112 31,4 2,8478 5,6995 7,73531 200 34,61 2,5907 5,1814 6,6891 224 41,3 2,1851 4,3703 5,6421 iii.2. optical proprieties figure 4 shows the variation of the transmittance versus of the wavelength of ch3nh3sni2cl film. it is shown that the transmittance spectrum of 300-900 nm, splitted to two intervals : the first interval between 600 and 900 nm, the transmittance of deposited film is in the order of 1,6%, low permeability value is caused by the black color of compound, thickness of layer and some crystal defects. second interval between 300 and 600 nm, the transmittance of deposited film is in the order of 0.05% is very low permeability value is caused by electronic transition between valence band to conduction band so we used tauc’s relation in determining direct gap energy[20, 21] : 2 ( ) ( ) g h a h e    (2) where: a is proportional constant, eg gap energy, α is absorption coefficient, h is planck constant and ν is wave frequency. figure 4. transmittance versus wavelength figure 5 shows the variation of tauc quantity of organometallic perovskite, where noticed slow variation at weak energy, after them, we noticed sharp increasing in this quantity, so the intercept between tangent line and energy axis giving a value of gap energy. auerbach energy eu is a very important optical quantity in thin films, so we used the following relation for its determination [22]. 0 ( ) ( ) u h ln ln e     (3) figure 5. curve shows the variation of (αhν)2 versus photon energy through the spectrum drawing of the variation of ln(α) versus hυ as shown in figure 6, we can find the auerbach energy using the inverted value of the slop mohammed lakhdar ayachi et al ijeca-issn: 2543-3717. december 2021 page 63 tangent line with the curve. auerbach energy value is relatively great due to crystal defects. figure 6. curve shows the variation of ln(α) versus photon energy figure 7 shows the variation of the absorption coefficient. where found high value in visible and near infrared ranges within 10-5 cm-1 due to black color of films, but in near ultraviolet range noticed increasing in absorption coefficient due to principle transitions between valance band to the conduction band. figure 7. curve presented a variation of absorption coefficient (α) versus wavelength iv. conclusion through this work, methylamine chloride powder is obtained, which is considered the basic nucleus of organic perovskite where it has the best crystallization and preferential orientation be at (100) level as shown via xrd spectrum. meanwhile used this compound for producing perovskite thin film by the spray pyrolysis with moving nozzle deposition device at determining temperature (120c°). xrd spectrum shows the best crystallization and preferential orientation at the (100) level. this film has a low bandgap (1,78 ev) and black color, furthermore has high auerbuch energy (0.6 ev), and very high absorption coefficient in the visible range that's mean can be an active layer in solar cells. references [1] [a. k. abass, “synthesis of cdtio3 thin films and study the impact of annealing temperature on their optical, morphological and structural properties,” eurasian j. anal. chem., vol. 13, no. 5, 2018. [2] y. takahashi, h. hasegawa, y. takahashi, and t. inabe, “hall mobility in tin iodide perovskite ch3nh3sni 3: evidence for a doped semiconductor,” j. solid state chem., vol. 205, 2013, pp. 39–43. [3] x. li, l. li, z. ma, j. huang, and f. ren, “low-cost synthesis, fluorescent properties, growth mechanism and structure of ch3nh3pbi3 with millimeter grains,” optik (stuttg)., vol. 142, 2017, pp. 293–300. [4] s. a. moyez and s. roy, “thermal engineering of lead-free nanostructured ch3nh3sncl3 perovskite material for thin-film solar cell,” j. nanoparticle res., vol. 20, no. 1, 2018, [5] chengxi zhang, lyudmila turyanska, haicheng cao, lixia zhao, michael w. fay, robert temperton, james o'shea, neil r. thomas, kaiyou wang, weiling luan, amalia patanè, “hybrid light emitting diodes based on stable, high brightness allinorganic cspbi3 perovskite nanocrystals and ingan,” nanoscale, vol. 11, no. 28, 2019, pp. 13450– 13457. [6] d. li, j. shi, y. xu, y. luo, h. wu, and q. meng, “inorganic-organic halide perovskites for new photovoltaic technology,” natl. sci. rev., vol. 5, no. 4, 2018, pp. 559–576. [7] ganesh alwarappan and md raiyan alam and walid m. i. hassan and mohamed f. shibl and sherin alfalah and sunil patil and reza nekovei and amit verma, “role of organic cation in modern lead-based perovskites,” sol. energy, vol. 189, 2019, pp. 86–93. [8] c. l. chen et al., “improved open-circuit voltage and ambient stability of cspbi2br perovskite solar cells by incorporating ch3nh3cl,” rare met., vol. 39, no. 2, 2020, pp. 131–138. [9] x. dong et al., “improvement of the humidity stability of organic–inorganic perovskite solar cells using ultrathin al 2 o 3 layers prepared by atomic layer deposition,” j. mater. chem. a, vol. 3, no. 10, 2015, pp. 5360–5367. [10] j. bisquert and e. j. juarez-perez, “the causes of degradation of perovskite solar cells.” acs publications, 2019. [11] su-yong bae, su young lee, ji-wan kim, ha nee umh, jaeseong jeong, seongjun bae, jongheop yi, younghun kim & jinhee choi, “hazard potential of mohammed lakhdar ayachi et al ijeca-issn: 2543-3717. december 2021 page 64 perovskite solar cell technology for potential implementation of ‘safe-by-design’ approach,” sci. rep., vol. 9, no. 1, 2019, pp. 1–9. [12] f. xu, t. zhang, g. li, and y. zhao, “synergetic effect of chloride doping and ch3nh3pbcl3 on ch3nh3pbi3− xclx perovskite‐based solar cells,” chemsuschem, vol. 10, no. 11 , 2017, pp. 2365– 2369. [13] h. yao, f. zhou, z. li, z. ci, l. ding, and z. jin, “strategies for improving the stability of tin-based perovskite (asnx3) solar cells,” adv. sci., vol. 7, no. 2020, pp.10. [14] hima abdelkader, ahmed khalil le khouimes, abdallah rezzoug, mouslem ben yahkem, abderrahmane khechekhouche, imad kemerchou. simulation and optimization of ch3nh3pbi3 based inverted planar heterojunction solar cell using scaps software, international journal of energetica, vol 4, n°1, 2019. pp. 56-59. [15] abdelkader hima, abderrahmane khechekhouche, imad kemerchou, “enhancing of ch3nh3sni3 based solar cell efficiency by etl engineering”, international journal of energetica, vol 5, no 1, 2020. [16] k. deng, z. liu, y. xin, and l. li, “pbi2/ch3nh3cl mixed precursor–induced micrometer-scale grain perovskite film and room-temperature film encapsulation toward high efficiency and stability of planar perovskite solar cells,” adv. mater. interfaces, vol. 5, no. 15, 2018, pp. 1–8. [17] i. kemerchou, f. rogti, b. benhaoua, n. lakhdar, a. hima, o. benhaoua, a. khechekhouche, “processing temperature effect on optical and morphological parameters of organic perovskite ch3nh3pbi3 prepared using spray pyrolysis method,” j. nano-and electron. phys., no. 11, 3, 2019, pp. 3011. [18] i. kemerchou, a. khechekhouche, a. timoumi, f. rogti, a. hima, a. sadoun, a. tliba, m. s. aida, “study of the chemical structure of ch3nh3pbi3 peroveskite films deposited on different substrates,” j. mater. sci. mater. electron., vol. 32, no. 3, 2021, pp. 3303–3312. [19] m. mahmoudi, a. benhaoua, b. benhaoua, l. segueni, r. gheriani, and a. rahal, “study of structural, optical and electricl properties of fluorinecobalt co-doped tin dioxide sno2,” dig. j. nanomater. biostructures, vol. 14, no. 4, 2019, pp. 1079–1086. [20] a. s. hassanien and a. a. akl, “optical characteristics of iron oxide thin films prepared by spray pyrolysis technique at different substrate temperatures,” appl. phys. a, vol. 124, no. 11, 2018, pp. 1–16. [21] i. m. el radaf, t. a. hameed, g. m. el komy, and t. m. dahy, “synthesis, structural, linear and nonlinear optical properties of chromium doped sno2 thin films,” ceram. int., vol. 45, no. 3, 2019, pp. 3072– 3080. [22] f. n. c. anyaegbunam and c. augustine, “study of optical band gap and associated urbach energy tail of chemically deposited metal oxides binary thin films,” dig. j. nanomater. biostructures, vol. 13, 2018, pp. 847–856. i. introduction ii. method and experience iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 01-05 ijeca-issn: 2543-3717. june 2017 page 1 study of the aerodynamic structure around a naca6409 aairfoil rotor saoussane gouiaa, ameni mehdi, zied driss, bilel ben amira, mohamed salah abid laboratory of electro-mechanic systems (lasem), national school of engineers of sfax (enis), university of sfax (us), b.p. 1173, road soukra km 3.5, 3038 sfax, tunisia guiua@gmail.com abstractthe multi-copters are one of the important aircrafts in the world because they are used in both military and civil application. the problem of these aircrafts is the low efficiency of its propellers. that’s why, it is necessary to study the aerodynamic structure around every rotor. in this paper, a computer simulation has been done to study the aerodynamic structure around a naca 6409 airfoil rotor. the numerical model is based on the resolution of the navier stockes equations with a standard k-ε model. then, the finite volume discretization of these equations leads to solve it. the local characteristics of the aerodynamic structure are extracted using the software solidworks flow simulation and the validation is done with comparison with anterior result of alexandrov [1]. keywords: naca 6409 airfoil rotor, aerodynamic structure, computer simulation, cfd. received: 12/02/2017 accepted: 11/04/2017 i. introduction the study of the aerodynamic structure around a propeller has an important value not only in academic research but also in some industries. in fact, these types of propellers are used especially in multi-copters which are a specific category of uavs. these machines are used in military and civil applications. that’s why, we can deduce their importance. so, it is interesting to solve every problem related to the propellers which are called also rotors. in fact, due to the low efficiency of the rotors, the academic researchers discovered new technologies to decrease the consumption of energy. in this context, they investigated numerical models and experiments to improve their performances. in fact, the calculated the value of the thrust force and determined the local characteristics of the aerodynamic structure. for example, alexandrov [1] determined the thrust force of one rotor using cfd and experiments. he used the same method also to choose the best configuration of propellers that saves the maximum of energy. also, le pape et al. [2] investigated a procedure that leads to the optimization of the helicopter rotor aerodynamic performance. in fact, the optimizer has been coupled to a 3d navier-stockes cfd solver and applied to helicopter rotor optimization in hover. heyong et al. [3] simulated the unsteady flows around forward flight helicopter with coaxial rotors based on unstructured dynamic overset grids. the performances of the two coaxial rotors both become worse because of the aerodynamic interaction between them, and the interaction between the two rotors. when the spacing between the two coaxial rotors increases, the thrust of the top rotor increases and the total thrust coefficient is reduced. zhao et al. [4] studied the cfd analysis of a ducted-fan uav based on magnus effect. in this vehicle, the actuator system consists of four rotary cylinders which are symmetrically installed at bottom of inside duct. the force used for attitude stabilization is generated by the interaction between the surface of cylinder and the downwash, which is known as magnus effect. in this paper, the aerodynamic characteristics of propeller-wing interaction for the ducted fan uav were simulated numerically based on the computational fluid dynamics (cfd) by means of sliding mesh technology. brocklehurst et al. [5] evaluated the performance of a new tip design of helicopter rotor blade. they investigated new rotor designs which are still a subject of intensive flight test verification. indeed, they used the cfd as a prediction for the viscous, compressible flow-field in the tip region and thus a prediction of the performance of the blade. from the previous studies, it appears that it is important to mailto:guiua@gmail.com s. gouiaa et al. ijeca-issn: 2543-3717. june 2017 page 2 investigate new designs. in this paper, we are interested on the study of the naca 6409 airfoil rotor. , configurations or profiles of propellers to increase their performance. ii. geometrical arrangement figure 1 presents the geometrical model. it is composed of a 10x5 propeller having a naca 6409 airfoil and mounted in a brushless motor. the value d=10 inch presents the diameter of the propeller and 5 presents the value of the pitch in inch also. the used model is similar to the one used by alexandrov [1]. (a) naca 6409 airfoil (10x5 propeller) (b) studied geometry (propeller mounted in a brushless motor) figure 1. geometrical model iii. numerical model to study the local characteristics of the aerodynamic structure around a naca 6409 airfoil rotor, we have used the software “solidworks flow simulation”. “solidworks flow simulation” is a class of computational fluid dynamics (cfd) analysis software that is fully embedded in the mechanical design environment, for all engineering applications. the “solidworks flow simulation” incorporates a number of technologies like cad data management, mesh generation, cfd solvers, engineering modeling technologies and result processing [6]. flow simulation is capable to detect both laminar and turbulent flows. laminar flow is determined when the reynolds number, which is a dimensionless number that gives a measure of the ratio of inertial forces to viscous forces, is low. over a critical value of reynolds number, the flow becomes turbulent. the numerical model is based on the resolution of navier-stokes equations with a standard k-ε model [7]. “solidworks flow simulation” calculation was performed in a rectangular parallelepiped-shaped computational domain. the boundary conditions are orthogonal to the axes of the global coordinate system. a computational mesh vises the computational domain with a set of plane orthogonal to the coordinate system’s axes to form rectangular parallelepipeds called cells. the resulting computational mesh consists of cells of different types. these cells can be divided into triangles. after using solidworks to create the model, we use “flow simulation” to simulate the fluid environment of the object and the effects that can affect the model according to the following design cycle shown in figure 2 [8-9]. to simulate the model, it was important to choose the adequate boundary conditions. in the present application, the pressure is equal to 101325 pa and the air molecular mass is equal to 0.02896 kg/mol. the adequate numerical model is the one that gives a curve of the force of thrust in function of the rotational speed near to the experimental curve of the experimental results of alexandrov [1]. figure 2. solidworks’ procedure s. gouiaa et al. ijeca-issn: 2543-3717. june 2017 page 3 iv. numerical results in this section, we have selected three planes which cut the rotary volume according to the three axes x=0 mm, y=0 mm and z=0 mm in order to visualize the following parameters: the static pressure, the average velocity, the turbulent kinetic energy, the dissipation rate of the turbulent kinetic energy and the turbulent viscosity. iv.1. static pressure figure 3 shows the distribution of the static pressure according to the chosen planes defined by x=0 mm, y=0 mm and z=0 mm. according to these results, it has been noted a variation of the distribution of the static pressure surrounding the propeller. also, it has been observed that the static pressure in the top of the propeller is lower than in the bottom. far from the propeller, there is no variation of the static pressure. (a) plane x = 0 mm (b) plane y = 0 mm (c) plane z = 0 mm figure 3. distribution of the static pressure iv.2. average velocity figure 4 presents the distribution of the average velocity in the planes defined by x=0 mm, y=0 mm and z=0 mm. according to these results, it has been noted that the important values of the average velocity are located in the bottom of the propeller. far from the propeller, the velocity becomes lower. (a) plane x=0 mm (b) plane y=0 mm (c) plane z=0 mm figure 4. distribution of the average velocity iv.3. turbulent kinetic energy figure 5 illustrates the distribution of the turbulent kinetic energy in different selected planes. when seeing the results, it has been noted that the wake zone characteristic of the important values of the turbulent kinetic energy is located at the extremities of the propeller as well as the extremities of the rotating volume. due to the fact that the motor is fixed, there is a low variation of the turbulent kinetic energy at its neighbourhoods. (a) plane x=0 mm s. gouiaa et al. ijeca-issn: 2543-3717. june 2017 page 4 (b) plane y=0 mm (c) plane z=0 mm figure 5. distribution of the turbulent kinetic energy iv.4. dissipation rate of the turbulent kinetic energy figure 6 shows the distribution of the dissipation rate of the turbulent kinetic energy considered in the different planes defined by x=0 mm, y=0 mm and z=0 mm. as we see, the wake characteristic of the maximum values of the dissipation rate of the turbulent kinetic energy is concentrated at the extremities of the propeller as well as the extremities of the rotary volume. near the motor, the values of the dissipation rate of the turbulent kinetic energy are low. this result is shown also at the exterior of the rotary volume. indeed, it is clear that the zones where the turbulent kinetic energy is important, the dissipation rate of the turbulent kinetic energy is also high. (a) plane x=0 mm (b) plane y=0 mm (c) plane z=0 mm figure 6. distribution of the dissipation rate of the turbulent kinetic energy vi.5. turbulent viscosity figure 4.16 presents the distribution of the turbulent viscosity in the three different planes defined by x=0 mm, y=0 mm and z=0 mm. according to these results, it has been noted that the turbulent viscosity is important at the bottom of the propeller especially at its extremities. indeed, it is clear that the turbulent viscosity presents a moderate or a low value, more precisely near the motor and in the outer of the rotating volume. (a) plane x=0 mm (b) plane y=0 mm (c) plane z=0 mm figure 7. distribution of the turbulent viscosity s. gouiaa et al. ijeca-issn: 2543-3717. june 2017 page 5 v. conclusion computer simulations have been developed to study the aerodynamic structure around a naca 6409 airfoil rotor. it has been noted that the size of the propeller as well as the type of the airfoil has a direct influence on the local characteristics of the aerodynamic structure. particularly, it has been noted that the depression zones are located especially on the top of the propeller. also, the wake zones are located at the extremities of the propeller and the rotating volume. in further works, it will be interesting to determine the local characteristics around other airfoils as well as the curve of thrust in function of the rotational speed to discover the difference between them and deduce the airfoil that consumes less energy. reference [1] d. alexandrov, light weight multicopter structural design for energy saving, tallin university of technology, 2013. [2] a. le pape, p. beaumier, numerical optimization of helicopter rotor aerodynamic performance in hover, aerospace science and technology 9 (2005), pp. 191-201. [3] x. heyong, y. zhengyin, numerical simulation of unsteady flow around forward flight helicopter with coaxial rotors, chinese journal of aeronautics 24 (2011), pp. 1-7. [4] j. zhao, q. hou, h .jin , y.zhu, g.li, cfd analysis of ducted-fan uav based on magnus effect, international conference on mechatronics and automation, august 5-8, chengdu china, proceedings of 2012 ieee. [5] a. brocklehurst, g. n.barakos, a review of helicopter rotor blade tip shapes, progress in aerospace sciences 56, (2013), pp. 35-74. [6] z. driss, o. mlayah, s. driss, d. driss, m. maaloul, m.s. abid, study of the bucket design effect on the turbulent flow around unconventional savonius wind rotors, energy, vol. 89, 2015. pp. 708-729. [7] s. driss, z. driss, i. kallel kammoun, computational study and experimental validation of the heat ventilation in a living room with a solar patio system, energy & buildings, vol. 119, 2016, pp. 28-40. [8] a. bouabidi, z. driss, n. cherif, m.s. abid, computational investigation of the external excitation frequency effect on liquid sloshing phenomenon, wseas transactions on fluid mechanics, vol 11, 2016, pp. 1-9. [9] z. driss, o. mlayah, s. driss, m. maaloul, m.s. abid, study of the incidence angle effect on the aerodynamic structure characteristics of an incurved savonius wind rotor placed in a wind tunnel, energy, vol. 113, 2016, pp. 894-908. i. introduction ii. geometrical arrangement iii. numerical model iv. numerical results iv.1. static pressure iv.2. average velocity iv.3. turbulent kinetic energy iv.4. dissipation rate of the turbulent kinetic energy vi.5. turbulent viscosity v. conclusion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 07-13 . http://dx.doi.org/10.47238/ijeca.v5i1.114. june 2020 page 7 effect of the fluidic injection on the flow of a converging-diverging conical nozzle benderradji razik 1,2* , gouidmi hamza 2,3 , beghidja abdelhadi 2 1faculty of science, mohamed boudiaf university, m'sila, algeria 2laboratory of renewable energies and sustainable development, universiyu of constantine 1, algeria 3department of mechanical engineering, el-bachir el-ibrahimi university of bordj bou arreridj, algeria e-mail*: razik.benderradji@univ-msila.dz abstract – the flow in an over-expanded nozzle is subjected to shock waves leading to the unsteady separation of the boundary layer. free detachment may be followed by a restricted detachment. during the expansion regime in propellant nozzles, several physical phenomena are encountered: supersonic jet, jet separation, adverse pressure gradient, shock wave, turbulent boundary layer, highly compressible mixture layer, return flow, large scale turbulence. these very complex phenomena can considerably affect the performance of the nozzle.the numerical investigation was performed by the cfd-fastran search code, using the k-w sst model as the turbulence model. the calculation is performed by solving the navier-stokes equations of twodimensional compressible turbulent flow. it is based on the study of the fluidic vectorization phenomenon of the thrust of a double-injection convergent-divergent supersonic conical nozzle. the study is based on the effect of the ratio of npr pressures with spr = 1 on the overall structure of shock waves. the calculation is highlighting the behavior of a flow that has not neglected. in particular, the appearance of the separation zone formed by the fluid jet and the deflection of the main jet cause separation shocks. keywords: shock wave, fluidic vectorization, boundary layer, returns flow, navier-stokes equations. received: 15/05/2020 – accepted: 21/06/2020 i. introduction the ancient technique for orienting the jet of a supersonic airplane is the mechanical technique; it is based on all the parts placed at the divergent ax symmetric nozzle. this technique is powerful but expensive. several problems have marked this mechanical device, especially during take-off or rapid orientation of military flights. so piloting the flight is difficult. it is a question of using the fluid as a solution for orienting the main jet of the supersonic nozzle of the plane. this technique is noted by fluidic vectorization. it is based on the location of a secondary injector at the divergence of the nozzle. in this case, one eliminates all the problems related to the movable fins. however, the fluidic vectorization has some disadvantages mentioned below:  delicate installation of injection slots especially in ax symmetric nozzles;  the shock vectorization method penalizes the thrust coefficient via the total pressure losses through the system of oblique shocks caused by the injection. the majority of the work, which dealt with the problem of secondary injection of a fluid passing through a main jet [1, 2], who studied the phenomenon of interaction of the gaseous jets in slits crossing supersonic external flows, they showed that the supersonic flow crossing a fluid jet is similar to that when facing a step of a height h. among the researches that have been conducted on this vectorization technique, mention is made in particular of the experimental and numerical work [3-5], numerical and analytical study [6-9]. the stationary steady-state phenomenon of fluidic vectorization in a two-dimensional symmetric supersonic conical convergent-divergent nozzle was studied. r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 8 this study's target is focused on the pressure ratio and overall shock wave structure. we want to emphasize that the action of a flow is not ignored and that the presence of the separation zone created by the fluid jet and the main jet deflection creates shocks in the separation. ii. optimization of numerical simulation the study was conducted on a test case [1]. basing in this study on the effect of the pressure ratio npr = pio / pa, defined by the ratio of the pressure generating the combustion chamber to that of the atmosphere at spr = pinj / pio = 1, which expressed by the ratio of the injection pressure to the pressure generating the combustion chamber. figure 2 shows the schematic of split injection pattern distribution and 2d transverse wall pressure. the simulated nozzle is a two-dimensional axisymmetric supersonic conical nozzle, figure 2, with a section ratio as / ac = 1.8, and a divergence half-angle of 11.02 °. the length of the diverging part is l = 0.0577m. the first injector is placed in a fixed position of x / xt = 1.8 and of width b1 = 0.002032m, while the second injector of b2 = 0.001016m of width is placed at x / xt = 1.4 of the nozzle neck. figure 1. schematic of split injection pattern distribution and 2d transverse wall pressure [2] figure 2. real photo of nasa nozzle [1] ii.1. cfd –fastran the numerical approach of the cfd-fastran code is based on the resolution of the navier-stockes equations by the finite volume method. the flow field is subdivided into small control volumes. conservation equations are applied to each volume taking into account the flows of variables across each face of the control volume. each variable is calculated at the center of each cell and assumed to be constant throughout the control volume. the calculation of the convective flux is based on two off-centered diagrams (upwind). the roe-fds scheme (flow difference splitting) and the van leer-fvs scheme (vector splitting flow). spatial precision of order greater than two can be obtained by using a suitable flux limiter. these flux limiters are used to prevent numerical oscillations, in particular for the seat flows of strong interaction zones shocks / discontinuity surfaces. for temporal integration, three schemas are integrated in the code: the explicit runge-kutta schema, the semi-implicit schema (implicit point) and the fully implicit schema. ii.2. mesh and boundary conditions figure 3 shows the profile of the nozzle used in the 2d calculations. the block structured quadrilateral mesh is used. the refinement of the mesh is also taken into account in the vicinity of the walls and that in the wake zones. to better simulate the boundary layers. the domain of calculation comprises 381900 cells. numerical calculations are performed for turbulent and stationary flow. a subsonic input condition is imposed at the inlet of the nozzle where the generating conditions and the direction of the velocity are imposed. the walls of the nozzle and the upstream outer domains are adherent and adiabatic. the upper and lower boundaries are provided with conditions of non-reflections. finally, a subsonic exit condition is imposed on the downstream boundary of the domain. this last condition requires a significant longitudinal extension to allow the jet to become subsonic by diffusion of the momentum by the viscosity. the sonic conditions of the gas are applied to the inlet of the injectors are ensured by the laws of isentropic flow related by the ratio of total pressures spr (according to experience). r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 9 figure 3. mesh of the domain of computation ii.3 influence of turbulence models in numerical calculations, the choice of the turbulence model significantly affects the results. several models were tested: the algebraic model of baldwin_lomax, the model with an equation of spalart_allmaras and the models with two equations of transport (k-ε and k-ω). figure 4 hows the influence of turbulence models on the distribution of wall pressure along the divergent nozzle are injector. the numerical calculations are carried out at npr = 6. we notice that all the models used, for example the case of the model kε. the model of spalart allmaras, balwin lomax and kω reproduces the area of separation appropriately compared to the experiment. given these results, the k-ω sst model will be used in the following. 0,04 0,06 0,08 0,10 0,0 0,2 0,4 0,6 0,8 1,0 p /p 0 x/l exp k-w k-e s-a b-l figure 4. influence of the turbulence model on the distribution of pressure at npr = 6 iii. validation of results figure 5 represents the partial evolution of pressures and figure 6 shows the stereoscopy of shock waves. numerical calculations are compared with the experimental work [1] as shown in figures 5 and 6. our results are obtained for npr = 4.6 and spr = 0.7. we compared the evolution of parietal pressure between the experiment and our numerical computation by observing that: for the position of the point of separation on both high and low walls. numeric the point is located at x / xt = 1.289 and at x / xt = 1.962, whereas for the experiment predicts this position at x / xt = 1.24 and at x / xt = 1.89. also note for the jumps of the pressures, are in agreement between them. a pressure peak can nevertheless be observed on the numerical simulation curve near the inputs of the two injectors, reflecting the presence of the detached shock (bow shock). secondly, we have also compared the experimental stereoscopy with that obtained numerically presented in the form of pressure contours for npr = 4.6 and spr = 0.7, figure 6. two detachment shock waves are observed, one upstream of the injector 2 caused by the enlargement of the nozzle, and another shock wave on the opposite wall near the lip of the nozzle due to the phenomenon of free separation. we can say that the experimental and numerical results are close. so, our numerical results later are validated experimentally. figure 5. evolutions of the parietal pressure figure 6. numerical and experimental stereoscopy, shock waves [1] r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 10 iv. results and discussion we study the effect of the npr expansion rate on the fluidic vectorization phenomenon in a conical nozzle, with secondary double injection for a stationary compressible turbulent flow. this study deals with the phenomenon of shock interaction as well as the phenomenon of delaminating of the boundary layer in the divergent part of the nozzle. it is carried out for an expansion ratio npr = pio / pa ranging from 2 to 8 for an spr = 1, with a position of the injector 2 equal to 1.4 of the throat of the nozzle. figure 7 shows that the flow regime at the inlet of the two injectors in the divergent nozzle is sonic, corresponds to a mach number equal to unity (m = 1). this value makes it possible to say that this input is assimilated to a sonic neck of a nozzle. this observation is confirmed by the literature [3-5]. figure 7. fields of the mach number iv.1 effect of npr pressure rate on the overall structure of shock waves the effect of the npr pressure rate on the main jet of the flow is shown in figure 8 by the iso-contour of the mach number. for each pressure ratio, the separation obtained is free. it illustrates the stationary aerodynamic field corresponding to the spr = 1 injection ratio. it may also be noted that, regardless of the pressure ratio, the reflection of the detachment shock by the secondary jet with that detached by the isentropic expansion effect on the divergent surface downstream of the neck is regular. this type of reflection has remained to appear for values of the relaxation rate npr are becomes minimal up to the value of the npr = 2.5, where the reflection of mach is becoming to appear. it can be seen also that the flow at the exit of the nozzle is supersonic followed by a regime of an over-relaxed nozzle. this configuration translated the nature of a flow through a convergent-divergent nozzle. in addition, the size of the recirculation zone that appeared due to the fluidic obstacle is becoming wider with the decrease of the pressure ratio npr, see figure 9. this remark is explained at a significant rate of expansion npr, the main jet is pushed the secondary jet towards the exit of the nozzle, and it decreases its height h. this decrease affects the values of the injected jet heights (fluidic obstacles), h1, h2 and h3, on which the lengths and heights of the separation zones l1, l2, l3, h1, h2 and h3 depend. these displacements of the shock and the interaction zone are translated by the displacements of the separation points of the boundary layers on the high and low walls. in the opposite direction, when the npr is weak, the secondary jet is penetrated deeper into the middle of the main jet which has led to a higher jet height. this figure also highlights the recirculation zone associated with detachment and in particular the aspiration of the ambient fluid. there is also a small vortex at the corner of the exit lip of the nozzle in accordance with other numerical results [3-5]. the phenomenon of delaminating, and the interaction between the shock wave / compression shock induced by the boundary layer are presented as follows: the first configuration of mach is captured at npr = 3.0057 and the second was marked at npr = 2.5078, these appearances due to the increase of the angles of the shock waves detached 1 and the detached shock wave due to the second injector, which became strong with the decrease in the rate of npr pressures. the total absence of the detached shock wave due to the injector 2 and the mach reflection labeled with npr = 2.0208 and 2.5078, respectively. beyond npr = 3.0057, only observed configuration is the regular reflection, as a remark. the zone of interaction between the detached shock wave and the turbulent boundary layer of the lower wall is increasingly increasing with the decrease of the npr. the phenomenon of restricted delaminating is observed for all npr values. jet heights are important when the rate of npr pressures is decreased. the heights of the separation zones are important when the npr pressure levels decrease. r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 11 v. figure 8. fields of iso-contours from the mach number to spr = 1 for different nprs. figure 9. overall structure of the shock waves and the recirculation zones near the injectors of the upper wall of the nozzle at spr = 1, for different nprs r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 12 iv.2 variation of the deflection angle of the jet figure 10 shows the deflection angle of the main jet flow versus the npr expansion ratio for our test case compared with the experiment [1] at spr = 0.7. there is an approach between our value of the deflection angle and that of the experiment. the flow deflection angle as a function of the pressure ratio at spr = 1, gives the same evolutionary trend as that shown in the figure, it is between 8° and 13.05°. at npr = 3, the value of the deflection angle is large, there is a significant deviation of the flow in the direction of the injected jet. when, as the expansion ratio npr increases, the deflection angle is gradually decreased. 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10 12 14 16 d e fl e c ti o n a n g le npr test case experimental calculation present calculation  05,13max npr = 3 test case to npr = 4.6 and spr = 0.7 figure 10. evolution of the deflection angle of the main jet as a function of the pressure rate npr at spr = 1, for present calculation the width of the jet 2 b1 = 0.001016m and for the calculation of ka waithe et al [1] b1 = 0.002032m iv.3 effects of npr pressure ratio figures 11 and 12 show the evolution of the parietal pressures as a function of the pressure ratio npr to spr = 1. it is noted that the separation point and the plateau pressures are well graduated, one on the other following the decrease of the npr, in particular the value of npr = 2.0208, giving a position of the separation point further upstream by compared to others. this shift reflects the recirculation zone which is larger compared to other nprs cases. this finding is explained by the transition from regular reflection (rr) with small values of npr to the mach reflection (mr) that was detected at npr = 2.0208. this transition leads to making the low detachment shock waves weak. 0,5 1,0 1,5 2,0 0,0 0,2 0,4 0,6 0,8 1,0 p /p 0 x/xt npr= 2,0280 npr=2,5078 npr=3,0057 npr=3,5113 npr=4,611 npr=5,005 npr=6 npr=8,109 figure 11. evolutions of the wall pressure of the upper wall for different nprs and at spr = 1 0,5 1,0 1,5 2,0 0,0 0,2 0,4 0,6 0,8 1,0 p /p 0 x/xt npr=2,0208 npr=2,5078 npr=3,0057 npr=3,5113 npr=4,611 npr=5,005 npr=6 npr=8,109 figure 12. evolutions of the wall pressure of the lower wall for different nprs and at spr = 1. vi. conclusion in this study, numerical turbulent twodimensional flow calculations for the investigation of the fluidic vectorization phenomenon of the thrust of a convergent-divergent cone nozzle were presented. these calculations are based on the resolution of stationary navier-stokes equations, the cfd-fastran search code, and the k-w sst model as the turbulence model. this code is based on higher order's roe's fds shockabsorption scheme that is robust to capturing shock. the results obtained are well described this vectorization phenomenon. they conform to those found experimentally and numerically. the transition from regular reflection (rr) with small values of npr to the mach reflection (mr) that has been detected induces the existence of a hysteresis phenomenon associated with the shock wave / boundary layer interaction. this type of interaction, it is present in many fields of the aeronautics r. benderradji et al ijeca-issn: 2543-3717. june 2020 page 13 such as: the internal aerodynamic (air intakes, scramjet), external (presence of shock of extrados in transonic, flows in nozzle on-detente). the presence of this interaction in these mechanical systems is a real practical problem because it is at the origin of strong in-stationary constraints, which can lead to the fatigue of structures and their destruction. it can also lead to instabilities in the operation of the engines (pumping of compressors, instability of combustion in scramjet ...). references [1] k. a. waithe and k. a. deere, “experimental and computational investigation of multiple injection ports in a convergent-divergent nozzle for fluidic thrust vectoring”, 21st applied aerodynamics conference, june, orlando, florida 2003. [2] f.w. spaid, e.e. zukoski, “study of the interaction of gaseous jets from transverse slotswith supersonic external flows”, aiaa j.vol 6, no 2, 1968, pp. 205–212. [3] vladeta zmijanovic, “vectorisation fluidique de la poussée d'une tuyère axisymétrique supersonique par injection secondaire”, thèse de doctorat, de l’université d’orléans, 2013. [4] v. zmijanovic l. leger, v. lago, “experimental and numerical study of thrust vectoring effects by transverse gas injection into a propulsive axisymmetric c-d nozzle”, aiaa 2012-3874, 48th aiaa/asme/sae/asee joint propulsion conference & exhibit 30 july 01 august 2012, atlanta, georgia. [5] v. zmijanovic, v. lago, l. leger, e. depussay, m. sellam, a. chpoun, “thrustvectoring effects of a transverse gas injection into a supersonic cross flow of an axisymmetric convergent-divergent nozzle”, progress in propulsion physics, vol. 4, 2013, pp. 227-256. [6] n. maarouf, m. sellam, m. grignon, and a. chpoun, “thrust vectoring through fluidinjection in an axisymmetrical supersonic nozzle: theoretical and computational study”, journal of shock wave, 2009; pp. 11421146. [7] a. ashraf, c. g. rodriguez, a. j. neely, and j. young, “combination of fluidic thrust modulation and vectoring in a 2d nozzle”, aiaa 2012-3780, 48thaiaa/asme/sae/asee joint propulsion conference & exhibit, 2012, atlanta, georgia. [8] xin h. zou, qiang wang, hagemann, “the comparative analysis of two typical fluidic thrust vectoring exhaust nozzles on aerodynamic characteristics”, world academy of science, engineering and technology vol. 5, 2011, pp. 04-20. [9] ahmed remlaoui, mohammed benyoucef, djamel assi and driss nehari, “a trnsys dynamic simulation model for a parabolic trough solar thermal power plant”, international journal of energetica (ijeca),vol 4. no 2. 2019. i. introduction ii. optimization of numerical simulation ii.2. mesh and boundary conditions iii. validation of results iv. results and discussion v. vi. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 36-40 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 36 real time data acquisition of solar panel youssef rehouma 1* , mohamed abd el basset mahboub 2 , aicha degla 3 , djafer ghorma 2 , ahmed abd alouareth nadjemi 2 1 lage laboratory, university of ouargla, 30000 ouargla, algeria. 2 institute of technology, applied engineering, university of ouargla, 30000 ouargla, algeria 3 centre de développement des energies renouvelables –cder.62 route de l’observatoire, algeria. * corresponding author e-mail: rehouma.youssef@univ-ouargla.dz abstract – we created a real-time acquisition system to track the voltage, current and temperature changes of the solar panel as we installed it in a charging regulator with a battery. the system consists of an arduino uno board, the controllership, which is programmed by the arduino ide application, based on the c language, and sensors to capture the variables, we put the sd card to save the data and the lcd to see it currently and can be monitoring the data by connecting the arduino uno board to the computer and processing it with the excel application. keywords: panel solar, lcd, sd card, arduino uno, exel. received: 26/05/2022 – revised 10/06/2022 – accepted: 20/06/2022 i. introduction renewable energy sources include sunshine, wind, geothermal heat, rain, waves, living plants, and animal and plant materials. since these resources can be replenished naturally, this sort of energy is regarded as renewable[1, 2]. their primary benefit is that they can lessen the damaging effects of conventional sources like coal, gas, and oil on the environment [3]. real-time data refers to data that is presented as it is acquired [4]. the idea of real-time data handling is now popular in new technologies such as tracking changes progress and knowing the problems as they occur, and by collecting quantitative data, we were able to improve the quality of processing[5]. in the world of machinery, this allows a technician to intervene quickly when there is a problem, allowing their machinery to function at peak performance [6]. automated data entry was once carried out by hand. data acquisition systems employ automation, which minimizes human error and misplacement [7]. additionally, storing information gathered digitally is cheaper, takes up less space than physical paper, and can be retrieved almost instantaneously [8]. the data is also entered faster. these things don’t happen when humans are manually doing the job [9]. this paper purposes real-time monitoring changes of current, voltage and temperature of the solar panel and the battery by using the arduino board, which stores the data obtained in the sd card and piloted it instantaneously in an excel spreadsheet. ii. material and method ii.1. elements of data acquisition system in this section, we will present how to connect the hardware components to the arduino uno and the solar panel charging regulator, in addition to the programming code and how to work on it. we will also present how to extract and display the information obtained in real-time using the excel program. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahukewi-w9dzym_4ahwqlp0hhyl_clmqfnoecbsqaq&url=http%3a%2f%2fwww.univ-oeb.dz%2fit%2far%2f&usg=aovvaw3hc048s3irmnsfio2rjsgg https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahukewi-w9dzym_4ahwqlp0hhyl_clmqfnoecbsqaq&url=http%3a%2f%2fwww.univ-oeb.dz%2fit%2far%2f&usg=aovvaw3hc048s3irmnsfio2rjsgg mailto:rehouma.youssef@univ-ouargla.dz y. rehouma et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 36-40 page 37 figure 1. real-time data acquisition of solar panel system figure 2. schematic view of the hardware components connected to the panel controller ii.2. solar panel a solar panel is defined as a device that converts solar radiation into electrical energy through a photovoltaic effect [10]. these cells are arranged in a grid-like pattern on the surface of solar panels. figure 3. solar pv ii.3. arduino board arduino is an electric board with open-source hardware and software, which can be programmed by a software called arduino ide (integrated development environment) based on c++ a programming language, which is used to write and upload the computer code to the physical board[11]. ii.4. sensors a) current sensor acs712: hall effect, when current passing creates a magnetic field which is converting it to a voltage signal[12]. b) voltage sensor b25: the division of voltage, contains two resistance 30kω and 7.5kω. which divides voltage input 5 times 1/5[12]. c) thermocouple max6675: the seebeck effect describes the voltage or electromotive force induced by the temperature difference along the wire[13]. ii.5. solar charge controller a) voltage regulator dc/dc pwm: convert a direct current source from one voltage level input to another voltage level output. b) battery: the battery must be available in the installation of the solar energy system in order to regulate the load alimentation and ensure its continuity in the presence and absence of the sun or the supply of the solar panel. we used the propower battery 12v100ah model. c) load (lamp): a lamp load/load lamp is simply a standard light bulb connected in series with the equipment being evaluated. it can be used to control the load's power. ii.6. view and extract data from the system data can be extracted and displayed in three different ways, which we will present as follows: a) lcd display: lcd displays are taking the data from the arduino board in real-time, and display it in that order: the panel voltage and current in the first line and the temperature and battery current to know if it was charging or discharging in the second line. y. rehouma et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 36-40 page 38 figure 4. lcd display b) excel program: we can also get the data in realtime by connecting the arduino to the computer via a usb cable and defining it in the excel 2021 program as shown below: figure 5. data in excel c) sd card: the data is stored in the micro sd card in that order: panel voltage, panel current, battery voltage, battery current, temperature, into a file in the form “.txt”, must be placed comma between the parameter or escape to be able excel application differentiate between them, set a dividing line” ###” whenever restart the arduino board. figure 6. text data file. we explained how to install the hardware components of the system and program the arduino board, in addition to how to extract and display the data obtained. ii.7. experimental data we did this experiment in the institute of applied sciences and techniques -ouargla on wednesday 01/06/2022. figure 7. test bench through this cheap cost project, we designed a system to monitor the data of the solar system (solar panel + battery), we took into account the characteristics of the solar panel and the characteristics of the uno arduino board. we have provided the arduino uno board with the following: a max6675 temperature sensor, two b25 voltage sensors, two acs712 current sensors, a microsd card adapter, and an lcd screen. iii. results and discussion we will present the results of tests performed by a realtime solar panel data monitoring system, as previously described. the various results obtained and their scientific interpretation is presented in the following. we note that the temperature and radiation are the same as the curve at the beginning of the day was 26° at 7:00 am, corresponding to 232w/m², the temperature reached a maximum value of 14:48 57°, and the light intensity also reached 963w/m² at 13:00 s shown in figures 8a and 8b. weather fluctuations affect the results of the stability of temperature radiation at 13:00 and it affects the power of the solar panel. y. rehouma et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 36-40 page 39 figure 8. results for (a) radiation profile, and (b) temperature profile in the voltage curve figure 9a, we notice that the battery is increasing from 12v to 13.8v because the battery is charging, while the soler charge controller sets the battery the appropriate voltage for charging. for figures 9b and 9c, we notice that the pv current increases from 0.37a at 7:00 to 1.6a at 12:00, with increasing the load lamp, then it becomes almost stable. we turned on the 48w lamp from 13:40 to 14:55. we notice that the current of the battery has become negative -2.74a because it is discharging, and there is also an increase in the pv current to 1.18a. we notice that the pv power is the same curve as the current. it was 5w at 07:00 then becomes stable at 30w from 12:00 to 19:00. figure 9. results for panel and battery (a)voltage curve, (b) current curve and (c) puissance curve iv. conclusion through this installation, we aim to measure (the temperature of the solar panel, the voltage of the solar panel, the battery voltage, the current strength of the solar panel, and the strength of the battery current) and present it on the lcd screen and the excel program. in order to monitor the performance of the solar panel, the results we get are excellent, the system works well and it is scalable. in the modern world, collecting data has become necessary to improve the efficiency and reliability of machinery and processes, the data acquisition devices, used in laboratories and companies to evaluate and monitor parameters. the information gathered by data acquisition devices can then be used to make sure that machinery operates safely, specific processes are performed efficiently, and there are reliable outcomes. where is possible to take measurements and display the information in real-time. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper. y. rehouma et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 36-40 page 40  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] s. motahhir, a. chalh, a. el ghzizal, a.j.j.o.c.p. derouich, “development of a low-cost pv system using an improved inc algorithm and a pv panel proteus model, ”, journal of cleaner production, vol.204, pp. 355-365, 2018. doi: 10.48084/etasr.1675 [2] t. singh, r.j.i.j.o.c.s. thakur, engineering, “design and development of pv solar panel data logger, ”, international journal of computer sciences and engineering , vol. 7 ,2019. https://doi.org/10.26438/ijcse/v7i4.364369 [3] c. chen, y. hu, m. karuppiah, p.m.j.s.e.t. kumar, assessments, “artificial intelligence on economic evaluation of energy efficiency and renewable energy technologies, ” , sustainable energy technologies and assessments, vol. 47, pp. 101358,2021. https://doi.org/10.1016/j.seta.2021.101358 [4] s. lee, s.j. nam, j.-k.j.j.o.m.s. lee, technology, “realtime data acquisition system and hmi for mes, ” journal of mechanical science and technology, vol. 26, no.8, pp. 2381-2388, 2012. https://doi.org/10.1007/s12206-0120615-0 [5] h. hamdani, a.b. pulungan, d.e. myori, f. elmubdi, t.j.j.o.a.e. hasannuddin, t. science, “real time monitoring system on solar panel orientation control using visual basic, ” journal of applied engineering and technological science , vol. 2,no.2 ,pp112-124,2021. https://doi.org/10.37385/jaets.v2i2.249 [6] n.s. reddy, c. gowthami, e. mounika, s. harshad, r.p.j.i.j.o.r.a.i.m.t. kumar, “real-time data acquisition to excel and monitoring characteristics of solar panel using arduino, ” international journal of recent advances in multidisciplinary topics, vol.3,no.5, pp.15-20,2022. [7] d. girardeau-montaut, m. roux, r. marc, g.j.i.a.o.p. thibault, “change detection on points cloud data acquired with a ground laser scanner, ” remote sensing, s.i. sciences, vol.36, no.3, w19.2005. [8] v. gupta, m. sharma, r. pachauri, k.d.j.e.s. babu, “performance analysis of solar pv system using customize wireless data acquisition system and novel cleaning technique, ” energy sources, vol.44, no.2, pp.2748-2769, 2022. https://doi.org/10.1080/15567036.2022.2061091 [9] v. voicu, d. petreus, r. etz, “ data acquisition system for solar panels, ” , 2019 42nd international spring seminar on electronics technology (isse), ieee, pp. 1-6, 2019. [10] m.f. rabbe, m.s. bepari, “ residential electricity consumption and load pattern analysis, doctorat theses 2021. http://dspace.daffodilvarsity.edu.bd:8080/handle/12345678 9/8122 [11] m. papoutsidakis, a. chatzopoulos, c. drosos, k.j.i.j.c.a. kalovrektis, “an arduino family controller and its interactions via an intelligent interface, ” international journal of computer applications, vol.179, no.30, pp.5-8,2018. doi: 10.5120/ijca2018916684 [12] a. el hammoumi, s. motahhir, a. chalh, a. el ghzizal, a.j.r.w. derouich, water, solar, “low-cost virtual instrumentation of pv panel characteristics using excel and arduino in comparison with traditional instrumentation, ” renewables: wind, water, and solar, vol.5, no.1, pp. 116, 2018. https://doi.org/10.1186/s40807-018-0049-0 [13] s.p. nalavade, a.d. patange, c.l. prabhune, s.s. mulik, m.s. shewale, “development of 12 channel temperature acquisition system for heat exchanger using max6675 and arduino interface, ”innovative design, analysis and development practices in aerospace and automotive engineering (i-dad 2018), springer, pp. 119-125, 2019. https://www.sciencedirect.com/journal/journal-of-cleaner-production https://www.sciencedirect.com/journal/journal-of-cleaner-production http://dx.doi.org/10.48084/etasr.1675 https://doi.org/10.26438/ijcse/v7i4.364369 https://www.sciencedirect.com/journal/sustainable-energy-technologies-and-assessments https://www.sciencedirect.com/journal/sustainable-energy-technologies-and-assessments https://doi.org/10.1016/j.seta.2021.101358 https://doi.org/10.37385/jaets.v2i2.249 http://dspace.daffodilvarsity.edu.bd:8080/handle/123456789/8122 http://dspace.daffodilvarsity.edu.bd:8080/handle/123456789/8122 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 21-29 ijeca-issn: 2543-3717. december 2019 page 21 modeling solar desalination with reverse osmosis (ro) powered by concentrating solar power (csp) plan ahmed remlaoui 1,* , hammou soumia 2 , bent abdelkader nafissa 2 , driss nehari 1 1 smart structure laboratory, university center of ain-témouchent, 46000 ain-témouchent, algeria 2 department of mechanical engineering, university center of ain-témouchent, 46000 ain-témouchent, algeria donremlaoui@gmail.com abstract – this article deals with the desalination of seawater and brackish water, which can deal with the problem of water scarcity that threatens certain countries in the world; it is now possible to meet the demand for drinking water. currently, among the various desalination processes, the reverse osmosis technique is the most used. electrical energy consumption is the most attractive factor in the cost of operating seawater by reverse osmosis in desalination plants. desalination of water by solar energy can be considered as a very important drinking water alternative. for determining the electrical energy consumption of a single reverse osmosis module, we used the system advisor model (sam) to determine the technical characteristics and costs of a parabolic cylindrical installation and reverse osmosis system analysis (rosa) to obtain the electrical power of a single reverse osmosis module. the electrical power of a single module is 4101 kw; this is consistent with the manufacturer's data that this power must be between 3900 kw and 4300 kw. thus, the energy consumption of the system is 4.92 kwh/m3.thermal power produced by the solar cylindroparabolic field during the month of may has the maximum that is 208mwth, and the minimum value during the month of april, which equals 6 mwth. electrical power produced by the plant varied between 47mwe, and 23.8mwe. the maximum energy was generated during the month of july (1900 mwh) with the maximum energy stored (118 mwh). keywords: system advisor model (sam), reverse osmosis system analysis (rosa), rankine cycle, parabolic trough power. received: 03/10/2019 – accepted: 10/11/2019 i. introduction the use of seawater desalination to provide fresh drinking water is a well-established and flourishing industry. the two main technologies used are thermal desalination and reverse osmosis (ro) membrane filtration. the desalination of brackish water or seawater by conventional treatment units requires a large electrical energy and / or heat. among the processes, distillation and reverse osmosis are technologies whose performance has been proven to desalinate salt water [1]. concentrating solar power (csp) technology is considered as one of the alternative solutions of power generation from solar energy. in this technology, sunrays are focused onto a solar receiver with the help of mirrors. the energy captured by the receiver is converted to heat or electricity through a series of process [2]. martin et al. used a mathematical programming technique to optimize the operation of a csp plant employing regenerative rankine cycle for a site in spain. [3]. a simulation model for predicting the electrical output of a 50 mwe ptc power plant was developed by garcia et al. [4]. the model results were compared with the experimental data of a power plant operating in spain. during our modeling and simulation work, we used software, sam [5] (system advisor model) for the energy study of a parabolic concentrator and rosa [6] (reverse osmosis system analysis) to obtain the electrical power of a single reverse osmosis module. the objective of this work is the technical and economic study of a parabolic plant used to produce electricity consumed by a reverse osmosis module. the results obtained make it possible to highlight the effect of the electrical energy consumption on the cost of desalination by reverse osmosis. ii. presentation of the solar desalination plant used the heat generated by a csp plant can be utilized to produce the required electric power needed to drive the mailto:donremlaoui@gmail.com abder image placée a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 22 ro pumps [7].it has been reported that csp/ro coupling is more efficient and requires less energy than csp/med coupling [8]. fig. 1 shows a schematic diagram of a csp/ro coupling [9]. the parabolic-cylindrical mirror-type solar power plant consists of parallel rows of long, semi-cylindrical, north-south-oriented mirrors that circle around it to follow the sun's course. the sun's rays are concentrated on a longitudinal receiver tube arranged all along the installation. inside this tube circulates a coolant that will be used to capture and transport heat; the fluid temperature can reach up to 400 ° c. the coolant heat is transmitted to the water that vaporizes, the steam produced operates a turbine, and this turbine drives the generator that produces electricity. this plant has a molten salt tank that can store heat for several hours, and thus produce electricity in the night. the transfer fluid was chosen according to its physicochemical properties. in this study, therminol vp1 was used because of its thermal stability up to temperatures of 400°c. therminol vp-1 is a hydrocarbon based synthetic fluid consisting of a mixture of 75 % diphenyl oxide (c12h10oh) and 25% diphenyl (c12h10). on the other hand, since the molten salts based on sodium and potassium nitrates have a good exchange coefficient and a good thermal inertia, which allows them to store heat, they are used in the present study. figure 1. schematic diagram of the rankine cycle with solar field powering ro desalination system [8] iii. system simulation iii.1. reverse osmosis (ro) the approach used to obtain the electrical power required to run ten (10) reverse osmosis modules is done using the rosa software. the rosa 9.1 software is the latest version, used in the analysis to determine membrane performance and energy requirements for desalination [6]. rosa can be used to finalize and optimize the design of an installation, provide details for the selection of a feed pump and provide information for post-processing requirements [6]. the rosa program has four input pages, a report page and a cost analysis page. the six tabs are: 1. project information. 2. feed water data. 3.scaling information. 4. system configuration. 5. report. 6. cost analysis. table 1 shows the main parameters of feed water table 1. supply water settings number of modules = 10 seawater salinity 36132 mg/l temperature 18.8 ph 8.5 figure 2 shows the configuration of the system, in the case of a single module or there are 246 pressure tubes, each tube equipped with 7 membranes (1722 membranes in total). the type of membrane is sw 30 hr-380. the permeate flow rate is 20,000 m 3 /d and the conversion rate is 47 %. a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 23 figure 2. the configuration of the reverse osmosis system on rosa iii.2. rankine cycle with solar field after having completed the first step concerning the reverse osmosis module and the definition of the power necessary to operate the reverse osmosis desalination unit, we will proceed to the next step, which concerns the dimensioning of the csp plant in order to provide a power supply for the reverse osmosis unit. we used another technical-economic software to determine the technical characteristics and costs of the csp system, as well as the performance analysis of the parabolic cylindrical csp plant. in this part, we will make a simulation of a csp plant, whose heat transfer fluid is thermal oil (therminol vp1), this plant is tested for the ain témouchent site, the nominal power of this plant is 40.7 mwe. the system advisor model (sam) code was used to simulate the annual behavior of the csp plant at the time scale. sam predicts the dynamic behavior of the parabolic trough. the system advisor model (sam) software is a software that performs cost and performance analysis of solar installations. this software was developed by the national renewable energy laboratory (nrel), sandia's national laboratories in partnership with the united states department of energy (doe), and the solar energy technology and program (setp). it has been designed to facilitate decision-making for those involved in the renewable energy industry [5]. the empirical model of a csp modeling plant is identical to the physical model, only it uses a set of curve fitting equations derived from the regression analysis of the measured data from segs (solar energy generating systems) projects in the southwestern united states, is shown in figure 3. figure 3. the csp plant in sam program a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 24 the parameters concentrating the different components of the installation are: 1-solar field 2-collectors (scas) 3-receivers (hces) 4-power block 5-thermal storage iv. results and discussion iv.1. meteorological data figure 4a shows the solar radiation, the most extreme estimations of solar radiation was 1000 w.m -2 . figure 4.b shows the change in ambient temperature and figure 4c shows the wind speed during the year for the selected site. note that the maximum and minimum temperature recorded is equal to 37 ° c and 1 ° c respectively and we note that the maximum wind speed is 15 m /s. figure 4a. shows the solar radiation figure 4b. variation of ambient temperature figure 4b. variation of wind speed a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 25 iv.2. reverse osmosis after introducing, the previous data into the rosa code. the simulation results shown in table 2, we note that the electrical power of a single module is 4101 kw; this is consistent with the manufacturer's data that this power must be between 3900 kw and 4300 kw. thus, the energy consumption of the system is 4.92 kwh/m3. table2: ro system details parameter value feed flow rate [m3/j] 42553.19 pressure brine [bar] 66.61 brine flow rate [m3/j] 22553.02 pressure permeate [bar] 65.20 permeate flow rate [m3/j] 20000.17 salinity [mg/l] 277.51 the power [kw] specific energy [kwh/m3] 4101.57 4.92 iv.3. system performance of csp plan iv.3.1. thermal power produced by the solar cylindro-parabolic field figure 5 shows the total heat output produced during the year. we note that the thermal power during the month of may has the maximum that is 208mwth, and the minimum value of the thermal power recorded during the month of april, which equals 6 mwth. figure 5. total thermal power produced during the year (mwt) iv.3.2. electrical power produced by the plant figure 6 shows the hourly variation in the net power generated during the year. note that the power is varied between 47mwe, and 23.8mwe. it is observable that the power produced is proportional to the incident direct radiation on the solar reflectors. figure 6. system power generated during the year (kwe) a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 26 iv.3.3. power of csp plant as can be seen in the graphs above that: the maximum thermal power absorbed was estimated at 12 mwt as well as the maximum electrical output power (net) was estimated at 4.5 mwe, and the maximum electrical power of production (gross) was estimated at 4.8 mwe and incident of maximum thermal power on the ground was estimated at 30 mwt .its maximum thermal loss of the reservoir was estimated at 0 mwt and tes maximum thermal energy in storage was estimated at 4 mwt. iv.3.4. energy generated and thermal energy in storage the energy generated by each month and the thermal energy for storage illustrated in figure 7. it can be seen that the maximum energy was generated during the month of july (1900 mwh) with the maximum energy stored (118 mwh). iv.3.5. field htf temperature hot and cold header the heat transfer fluid (htf) flows from the cold reservoir to the hot reservoir, the minimum temperature of the cold header inlet has reached a value of 160 °c, and the maximum temperature obtained at the header outlet hot is 400 0c. the variation of the temperature of the hot and cold header input is shown in the figure 8. figure 7. monthly energy generated and thermal energy in storage (mwh) figure 8. field htf temperature hot and cold header a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 27 figure 9. absorbed thermal power (mwt) and field power (mwt), gross and net electric power (mwe), tes thermal losses from the tank (mwt) and in storage (mwt) iv.3.6. tes htf, hot and cold tanks volume for power generation after sunset, the htf fluid should be stored in the storage tank for a storage capacity of 8:00 h. the total htf maximum thermal energy storage (tes) is 1300 m 3 , the maximum hot tank htf volume is 1000 m 3 and the maximum cold tank htf volume is 1200 m 3 as shown in figure 9 and figure 10. figure 10. tes htf total volume, hot and cold tanks volume a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 28 iv.4. technical characteristics and system costs the simulation is carried out using the sam software, the technical characteristics of the csp system are shown in table 3 and the system costs are shown in table 4. table 3: technical characteristics of csp system table 4. csp system costs. the costs values site improvements ($) 981000 solar field ($) 5 886 000 htf system ($) 2354400 storage ($) 6 125950 total direct cost ($) 22 120782 total indirect cost ($) 3 672293 total cost of installation ($) 25 793022 total cost of the facility per capacity ($ / kw) 6 833 v. conclusion this article focuses on the techno-economic modeling of a cylindro-parabolic power plant to generate the electrical energy required for desalination by reverse osmosis. the results show that:  the electrical power of a single module is 4101 kw; this is consistent with the manufacturer's data that this power must be between 3900 kw and 4300 kw. thus, the energy consumption of the system is 4.92 kwh/m 3 .  thermal power produced by the solar cylindroparabolic field during the month of may has the maximum that is 208 mwth and the minimum value during the month of april, which equals 6 mwth.  electrical power produced by the plant varied between 47mwe, and 23.8mwe  the maximum energy was generated during the month of july (1900 mwh) with the maximum energy stored (118 mwh).  the minimum temperature of the cold header inlet has reached a value of 160 0 c, and the maximum temperature obtained at the header outlet hot is 400 0 c.  total cost of the facility per capacity is 6.833 $/kw acknowledgements the authors gratefully acknowledge support from smart structure laboratory of university center belhadj bouchaïb, ain témouchent (algeria). references [1] c. galus, “les techniques de dessalement de l'eau de mer prennent de l’essor, extrait du monde, 2000. [2] deepak bishoyi, k. sudhakar, “modeling and performance simulation of 100 mw lfr based solar thermal power plant in udaipur india”, resource-efficient technologies, 2017, doi: 10.1016/j.reffit.2017.02.002 [3] l. martin, m. mariano, “optimal year-round operation of a concentrated solar energy plant in the south of europe”. appl. therm. eng. 2013, vol. 59, pp. 627–633. [4] l.i garcia, j.l alvarez, d. blanco, “performance model for parabolic trough solar thermal power plants with thermal storage: comparison to operating plant data”. sol. energy, 2011, vol. 85, pp. 2443–2460. [5] nate blair, “system advisor model, sam2014.1.14: general description”, national renewable energy laboratory, 2014. [6] ahmed remlaoui, driss nehari, abderrahmane elmeriah reverse osmosis system analysis, rosa9.1-9/21/2013: general description, dow water & process solutions. 2013. the variables values collector reflective opening area [m2] 817.5 opening width, total structure [m] 5.75 length of collector assembly [m] 150 number of modules per assembly [-] 12 average length of the surface at the focal length [m] 2.11 distance between assemblies [m] 1 receiver inside diameter of absorber tube [m] 0.076 outer diameter of absorber tube [m] 0.08 the solar field line spacing [m] 15 irradiation [w/m²] 950 thermal field production [mw] 23.5613 solar field area (acres) 25 total area (acres) 35 https://www.dow.com/en-us/water-and-process-solutions a. remlaoui et al ijeca-issn: 2543-3717. december 2019 page 29 [7] t mezher, h fath, z abbas, a khaled. “techno-economic assessment and environmental impacts of desalination technologies”. desalination, 2011, vol. 266, no1, pp. 263–73. [8] a. al-karaghouli, ll. kazmerski. “energy consumption and water production cost of conventional and renewableenergy-powered desalination processes”. renew sustain energy rev, 2013, vol. 24, pp. 343–56. [9] shiva gorjian, barat ghobadian. “solar desalination: a sustainable solution to water crisis in iran”. renewable and sustainable energy reviews, vol. 48, 2015, pp. 571– 584. i. introduction ii. presentation of the solar desalination plant used iii. system simulation iv. results and discussion iv.2. reverse osmosis iv.3. system performance of csp plan iv.3.1. thermal power produced by the solar cylindro-parabolic field iv.3.2. electrical power produced by the plant iv.3.2. iv.3.3. power of csp plant iv.3.4. energy generated and thermal energy in storage iv.3.5. field htf temperature hot and cold header iv.3.6. tes htf, hot and cold tanks volume iv.4. technical characteristics and system costs v. conclusion acknowledgements references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 39-42 experimental study of the effect of meteorological parameters on the performance of the solar chimney power plant abdelghani azizi 1 , djamel benmenine 2 , hadda nouar 3 , abdelmadjid kaddour 4 1 department of renewable energies, university of kasdi merbah ouargla, ouargla, algeria 2 laboratory for the development of new and renewable energies in arid zones, university of kasdi merbah ouargla, algeria 3 electro technology and renewable energies department, university of hassiba ben bouali, chlef, algeria 4 unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria email*: abdelghani.azizi1@gmail.com abstrac t – the solar chimney power plant (scpp) is an economical technology for the production of solar electricity. the increase in the production efficiency of this type of installation is depended of the several theoretical and experimental studies. this paper stu died the effect of some k ey parameters such as (ambient temperature, solar radiation), on the performance of the solar chimney power plant. using the dimensions of our scpp prototype and also compared by the manzanares prototype with ouargla weather condit ions. where the maximu m solar radiation and ambient temperatures are 957 w/m 2 and 30 ° c at 15h00. respectively. the measured average air speed is 1.04 m/s, and the electric power value of the prototype is 2.04w. the results show that the solar radiation and the ambient temperature have a direct effect in the scpp efficiency, and also confirm that the technology of solar chimneys is the best solution to install in the hot and arid areas lik e ouargla city. keywords: solar chimney, meteorological parameters, electricity production, solar energy. received: 26/04/2021 – accepted: 16/06/2021 i. introduction in algeria, the global radiation received in d ifferent sites without altitudes or with a ltitudes of mediterranean or saharan c limates, is one of the highest in the world. in addition, the southern regions benefit fro m e xceptional qualities to harness solar energy in the most varied forms [1]. sola r energy is harnessed by a device called a solar fireplace. a solar chimney is the new technology for produce the electrica l energy using the solar energy where the main components are consists of: 1the solar greenhouse or collector ground; 2the chimney or tower; 3the turbine with electrical generator; the technology of the solar chimney power p lant was proposed in the first time by the engineer jorg schla ich and ge rman in 1976. in 1979, where they developed the first prototype that is reached the powe r output of 50 kw in manzanares city situated in the south of madrid, spain. consisted of collector of 120 m radius and high from ground of 2 m, and with chimney height of 195 m its radius of 5 m, the solar chimney power was operated from 1982 until 1989. the tests that are carried out in the power plant shown that the installation is reliably and therefore the concept is technically viable. the energy cost analysis and evaluation were studied in the work of haaf et al. the analysis showed that the power generation cost of the plant was (0.098 usd / kwh based on the 1983 average exchange rate). since then, no chimney solar power plant has been built but many theoretical and numerical studies have been carried out by many researchers. [2-4-5]. in the work of ba lijepa lli et a l an investigation has carried out in a s mall p rototype solar chimney powe r plant, where the ma ximu m a ir velocity was achieved at chimney is 1.9 m/s. and the effic iency of the scpp estimated is 0.0019% [6]. kiwan et al performed a modification in the scpp in aim to improve the ijeca-issn: 2543-3717. june 2021 page 39 http://www.ijeca.info/ http://www.ijeca.info/ mailto:abdelghani.azizi1@gmail.com abdelghani azizi et al ijeca-issn: 2543-3717. page 40 performance of the scpp viab ility. where they added two modifications the first is the photovoltaic (pv) and the second is installation of water pool for cooling the pv panels, the goal fro m these two modifications is to increase the power output of the installation, where the results found that the proposed system produces 45.35% more e lectricity annually than a standalone pv system installed in the same location [7]. setareh carried out a comprehensive study of the effects of geometric parameters on the performance of solar ch imney power plant (scpp), the proposition reveal that the ratio of pressure drop to total pressure potential of turbine must be chosen between 0.7–0.85 in the aim to achieve the optimu m performance of scpp. a lso the results shown that the increasing in air speed in side the chimney has a positive effect on the power output as well the performance of the scpp [8]. in this paper, we would like to show our study that is carried out at ouargla un iversity on the solar ch imney power plant (scpp) and analysis the effective of metro logical para meters on the pe rformance of sola r chimney powe r plant such as (a mbient te mperature solar radiation, air velocity inside collector and chimney). ii. material and methods ii. 1 . work ing principle solar chimney power plant (scpp) is a simp le solar therma l power p lant capable of converting solar energy into electricity. a solar towe r is a renewable energy plant built in such a way that air fro m a greenhouse heated by the sun is channeled into a ch imney, in order to drive turbines to produce electricity. as shown in figure 1. figure 1. working principle of t he solar chimney power plant scp p ii. 2 . prototype description in order to carrier out evaluate the measurement of the temperature field and air ve locity in side the solar chimney, a prototype of scpp was built university of ouargla as shown in figure 2 composed from collector wood ground of (5 m x 5 m) and (pvc) pipe with 0.16 m dia meter 6 m high used as chimney, where the pvc pipe was isolated using glass wool. the materia l used in the collector is a transparent glass and the height of collector from the ground is 0.2 m. figure 2. (a): t he solar chimney prototype. (b) t he sccp prototype wit h glass collect or used in our experiment al st udy the dimensional para meters of the scpp prototype are presented in the table 1. t able 1. t he dimensional parameters of t he solar chimney prototype descrip tion value area of collector 5 x 5 m 2 high of chimney 6 m high of collector from the ground 0.2 m diameter of the chimney 0.16 m tilt angle of the collector ≈ 6° iii. discussion of the measured results iii. 1 . variations of solar radiation and ambient temperature figure 2 presented the fluctuation of the solar radiation (g) and amb ient temperature (ta) measured with the time. these two parameters were registered in the day of 15 ma rche 2020. during the recorded of the results it was shown that the ambient temperature changes between 17 °c at 08h 00. to 30 ° c at 15h00. and the average value of the a mbient te mperature was 26.18 °c. also the solar radiation increases wit the time afte r and the ma ximu m value recorded is 957 w/ m 2 at 13h00. and decreases until sunset; where the average value was 728.9 w/ m 2 . it was observed following the results recorded that the potential of the village of ouargla it is the suitable to install the solar powe r p lants as the solar chimney power plant. abdelghani azizi et al ijeca-issn: 2543-3717. page 41 figure 2. t ypical measured solar irradiance and ambient t emperature vs t ime (15/03/2020) iii. 2 . variations of ambient temperature and air speed figure 3 shows the variations in measured a mbient temperature (ta) and air speed as a function of time. these two para meters we re registered during the day of 15 march 2020 in ouarg la. where observed that when the ambient temperature increases the air speed increases until reach ing the ma ximu m value of 1.6 m/s with amb ient te mperature value of 30 °c at 13h 00 , and begins to decrease to 0.8 m/s for an a mb ient te mperature value of 27 °c at 18h00. so we can a lso say that the air speed and the ambient te mperature have a p roportional relationship. figure 3. variat ion of air velocity at t he chimney entrance vs. solar irradiance (15/03/2020) iii. 3 . variation of the power calculated by the mathematical model figure 4 illustrates the expected energy variance using the scpp dimensional mathemat ical mode l as a function of solar radiation, using meteorologica l para meters for a typical day on 03/15/ 2020 in ouarg la. it is observed can that the power output generated by the prototype reached more than (1) watts in the presence of more than 860 w/m² o f solar rad iation between 10h00 and 13h00. it is important to note that the electrica l energy that can be produced at ouargla will be (1.13). the fo rm of the power output curve confirms the precisions of the mathematical model. figure 4. variat ion of t he power calculated by t he mathematical model using t he dimensions of the scp p vs. solar radiation (15/03/2020) iv . conclusion this paper presents the results as well as their discussions for an e xperimental study of the sma ll-scale scpp and also the results of the theoretical study by using the mathemat ical mode l for the calculat ion of the power. we can summarize the results found in our study as follows: the meteorological values recorded for the typical day of 03/ 15/ 2020 where the ma ximu m solar radiation and amb ient te mperatures are 957w/ m 2 and 30°c at 13h00 respectively, the measured average air speed is 1.04 m/s, and the electric powe r va lue calcu lated by the mathe matica l model for the prototype is 2.04 w, we found that the effic iency of the chimney has a proportional relat ionship with solar rad iation as we ll as the height of the chimney. and the value of the ma ximu m air speed reached 1.4 m/s with solar radiation of 957 w/m² at 13h00, for the typical day of 03/03/2017. abdelghani azizi et al ijeca-issn: 2543-3717. page 42 the air ve locity inside chimney increasing re ma rkab ly with the increasing of the solar radiance and the ambient temperature, it is clearly observed that the efficiency of the chimney has a proportional relat ionship with solar radiation as well as the ambient temperature. references [1] sellami, m . h., guemari, s., touahir, r. and loudiy i, k.: solar distillation using a blackened mixture of portland cement and alluvial sand as a heat storage medium. desalination vol 394, 2016, p p . 155-161. [2] w. haaf, k. friedrich, g. m ay r, j. schlaich, solar chimney s part i: princip le and construction of the p ilot p lant in m anzanares, int. j. sol. energy , vo l 2, 1983, p p. 3–20. [3] azizi, a., tahri, t., sellami, m .h. segn i, l., b elakrou m, r., loudiy ie, k.: exp erimental and cfd investigation of small-scale solar ch imney for p ower gen eration. case study : southeast of algeria. desalin ation and water treatment. vol 160, 2019, p p .1–8. [4] w. haaf, solar ch imney s, part ii: preliminary test results from the m anzanares p ilot p lant, int. j. sol. ener gy , vo l 2, 1984, p p . 141–161. [5] t. m ing, w. liu, g. xu, k. yang, thermody namic analy sis of solar chimney p ower p lant sy stem, j. huazhong univ. sci. technol., vol 33, 2005, p p . 1–4. [6] r. balijep alli, v.p. chandramohan and k. kirankumar, a comp lete design data and p erformance p arameter evaluation of a p ilot scale solar up draft tower, heat trans eng., vol 41.6-7, 2020, p p . 562-575. [7] s. kiwan, m . al-nimr and i. salim, a hy brid solar chimney /p hotovoltaic thermal sy stem for direct electric p ower p roduction and water distillation, sust ener gy techno. asses. vol 38, 2020, p p . 100680. [8] m .setareh, comp rehensive mathematical study on solar chimney p ower p lant, renewable ener gy , vol 175, 2021, p p . 470-485, international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 37-41 ijeca-issn: 2543-3717. december 2020 page 37 the electrical properties of au/gan and pedot: pss/gan diodes a. sadoun 1 , i. kemerchou 2,3 , s. mansouri 1 , m. chellali 1 1 applied microelectronics laboratory, university of sidi bel abbes, algeria 2 laboratory of analyses and control of energy systems and networks, university of amar telidji, algeria. 3 materials science and engineering program, state university of new york at binghamton, usa. e-mail * : 3ali39@gmail.com abstract – in the present paper, using a numerical simulator, the simulation of au/n-gan and pedot: pss/gan structures were performed in a temperature at room temperature. the electrical parameters: barrier height, ideality factor, shunt resistance series, and resistance have been calculated using different methods: conventional i-v, norde, chattopadhyay, and mikhelashvili. statistical analysis showed that the au/gan structure has a barrier height of (0.6 ev) which is higher compared with the pedot: pss/gan structure (0.72 ev) and ideality factor (1.88 and 2.26) respectively. the values of resistance shunt were increased from 77150.056 ω to 11207586 ω. it is observed that the leakage current increased from 6.64e-5 to 4.98926e-5a at −0.85 v. keywords: schottky diode; au/n-gan; pedot: pss/gan; (i-v), norde, cheung and chattopadhyay methods; leakage current; resistance shunt. received: 10/12/2020 – accepted: 15/12/2020 i. introduction in the development of electronic components such as schottky diode, mos, transistor and metal-isolatesemiconductor, gan's are commonly used (mis). et cetera. [1-3]. gallium nitride is a very promising material for semiconductor materials with high strength, highfrequency and wide-bandgap and high electron velocity saturation. the gallium nitride binary compound is a semiconductor direct bandgap with a lattice parameter = 4.52 å and eg = 3.22 ev and 300 k belonging to the iiiv family [4]. this binary compound (leds), photodetectors (msm), laser diodes, solar cell application, and field-effect microwave transistors[5-9] is the promising material in light-emitting diodes. gan's high-frequency characteristics make it suitable for highfrequency and high-power applications. [10, 11]. many theoretical and experimental studies on the production of devices for schottky diodes have been carried out (metal-gan). projects have investigated the electronic parameters and frequency dependent properties of au / nio / gan schottky diodes in the range 1 khz-1 mhz at different frequencies. a group of researchers have studied the effect of the hafnium dioxide layer on the electrical properties of the diode (pd / gan) in a wide temperature range (270 390k), they have also treated the effect of temperature (400-600 k) on the electrical properties of the au / ta2o5 / n-gan structure. another group have studied the electric transport and transport properties of the rare earth oxide intercalary diode au / y2o3 / n-gan [13,14]. the same group of researchers studied the effect of annealing temperature on the electrical properties of au / ta2o5 / n-gan of the metallic insulating semiconductor structure (mis) [12]. in this paper, we present a theoretical analysis of the effects of pedot: pss is given using forward i-v bias measurements on the electrical properties of the schottky diode (m / n-gan) at a temperature (300 k). we studied the evolution of ideality factor (n), barrier height (φb0), shunt resistance, and series resistance (rs) using (i-v), norde, chattopadhyay and mikhelashvili methods. ali sadoun et al ijeca-issn: 2543-3717. december 2020 page 38 ii. method the band gap (eg=3.40ev), electron affinity (ᵡ =4.10 , relative permittivity ε=9.50 , effective density of states in the conduction band (nc =2.3.10e17 cm -3 ) and effective density of states in the valence band (nv =4.7.10e17 cm -3 ) parameters used in the simulation for au/n-gan and pedot: pss/gan sbds, , the simulator is based on a mathematical model [13, 14].  bandgap model [15].  mobility model [16].  shockley–read–hall model [16].  auger recombination [17].  impact ionization [18].  thermionic emission [19].  universal schottky tunneling [20].  image force lowering [21]. iii. result and discussions 3.1 current-voltage (i-v) method the electrical characterization of schottky diode devices was carried out at the temperature 300 k. figure 1 shows the results of semi-log forward and reverse bias (currentvoltage) characteristics of the au/n-gan and pedot: pss/gan. the current-voltage characteristics of an ideal sbd are given by thermionic emission theory[24, 25] [7,8]. equation (1) can be written as an equation for the forward voltage applied (v > 3kt/q) (1). [24-26]: (1) we could find the value of (i0) by the plot ln (i) versus (v) at v = 0 volts. then, by replacing the calculated (i0) value in the equation (2), we could find the schottky barrier height. you can extract the value of the ideality factor (n) from the linear curve area (ln(i) -v) . (2) where a is the rectifier contact area, is the schottky barrier height [24]. is the richardson constant ( =26.4 a/cm 2 k 2 for n-gan). the values of barrier height and ideality factor, these values can be determined using the equation (3): ( ) (ln ) sq d v irn kt d i   (3) and the barrier height bn is given by: * 2 0 lnbn q aa t kt i         (4) figure 1. the semi-logarithmic reverse and forward bias currentvoltage characteristics for au/n-gan and pedot: pss/gan sbd in the temperature (300k) 3.2. method of norde the norde approximation method is defined by equation (5)[27]. this estimate is based on adjusted forward plots (i-v) that can be used to measure the height barrier: (5) where is an integer (dimensionless) greater than n and i (v) present the current which is acquired from the (i–v) curve. in this approximation, height barrier values can be determined using the equation (6) [27, 28]: (6) where value is obtained from the ln (i)-v curve, is the minimum point of f (v) as a function of v. from figure 2, we can determine values barrier heights, at the temperature of 300 k. was obtained and collected in table 1. ali sadoun et al ijeca-issn: 2543-3717. december 2020 page 39 figure 1. f (v) as a function of v of au/n-gan and pedot: pss/gan structures 3.3. model of chattopadhyay the chattopadhyay model is defined by equation (6) this approximation can be used to determine heights barrier and the ideality factor this values, can be calculated from the equation (7) : φb =ψs (jc, vc)+c2vc+vn-kt/q (7) the inverse of the ideality factor (c2) can be calculated by equation (8): c2= = jc,vc (8) where vn is the potential difference between the fermi level and the bottom of the conduction band , which can be calculated from equation (9): vn = (9) where, (nc and nd) present the effective conduction band density of states and the carrier concentration, respectively. the value of surface potential ψs can be determined from equation (10): ψs= ln ( ) –vn (10) with the aid of equations (9) and (10), the values of ideality factor (n) and barrier height were obtained and collected in table 1. figure 2. surface potential-forward voltage curves of the au/n-gan and pedot: pss/gan structures at t = 300k 3.4. mikhelashvili method mikhelashvili’s method for determination of the barrier height, ideality factor, and the series resistance. this method is based on the equation (11): (11) the barrier height and the ideality factor are obtained from equations (12) and (13) (12) (13) where ( ) are the coordinates of the maximum point in θ (v) versus v plot. at temperatures (300 k). the series resistance (rs) is obtained from equation (14): we can determine values barrier heights and series resistance, at the temperature of 300 k and presented in table 1 (14) ali sadoun et al ijeca-issn: 2543-3717. december 2020 page 40 figure 3. mikhelashvili’s plots for (a) the au/n-gan and pedot: pss/gan structures att = 300k we computed values of ideality factor, barrier height and series resistance and reported it in table 1. the obtained results using the i-v approach in temperatures 300 k shows an increase of barrier height (from 0.6 to 0.72 ev), an increase of ideality factor (n) (from 1.88to 2.26) and an increase of series resistance (rs) (from 318 to 608.5 ω). we observed that an increase in (t=300k) is accompanied by a decrease in the ideality factor and an increase in the barrier height for all methods [20]. the shunt resistance and series resistance are the other two important parameters for the sbd. table 1. the obtained values of saturation current, barrier height, ideality factor, and series resistance for au/n-gan and pedot: pss/gan structures figure 5 represents resistance rsh as a function of voltage v and it is noted that the rsh values are found to be 77150.056ω and 11207586ω au/n-gan and pedot: pss/gan structures, respectively. figure 5. voltage reliant device resistance iv. conclusion we reported in this paper the electrical characterization of au/ gan and pedot: pss/gan structures. we demonstrated that the i-v curves of these diodes. a low barrier height and the leakage current were obtained. the barrier height, ideality factor, and series resistance are also estimated by (i-v), norde’s, chattopadhyay’s, and mikhelashvili’s methods. results show that the schottky emission is the dominant conduction mechanism. the statistical analysis is employed to extract the barrier heights were 0.6 ev and 0.72 ev from i–v measurements respectively. it is observed that the leakage current increased from 6.64e-5 to 4.98926e-5a at −0.85 v. references [1] s. asubay, ö. güllü, a. türüt, "determination of the laterally homogeneous barrier height of metal/ pinp schottky barrier diodes", vacuum, vol. 83, no. 3, 2009, pp. 1470-1474. [2] j. schleeh, g. alestig, j. halonen, a. malmros, b. nilsson, p. nilsson, j.p. starski, n. wadefalk, h. zirath, j. grahn, "cooled integrated circuit amplifies with lowest noise so far", ieee electron device letters, vol. 33, no. 5, 2012, pp. 664-666. [3] f. acar, a. buyukbas-ulusan, a. tataroglu, “properties of al/coumarin doped pr2se3–tl2se/p-si devices", journal of materials science: materials in electronics, vol. 29, no. 15, 2018, pp. 1-8. [4] s. adachi, “group-iv, iii-v and ii-vi semiconductors”, john wiley & sons, 2009, isbn: 978-0-470-74369-0. [5] k. hattori, y. torii, “platform of peer-reviewed scholarly literature”, solid-state electronics, vol. 34, no. 5, 1991, pp. 429-534. ali sadoun et al ijeca-issn: 2543-3717. december 2020 page 41 [6] a. singh, k. reinhardt, w. anderson, “temperature dependence of the electrical characteristics of yb/p-inp tunnel metal-insulator-semiconductor junctions”, journal of applied physics, vol. 68, 1990, pp. 3475-3483. [7] t. enoki, h. yokoyama, y. umeda, t. otsuji, “ultrahighspeed integrated circuits using inp-based hemts ”, journal of applied physics, vol. 37, no. 3b, 1998, pp. 1359-1364. [8] k. pande, “characteristics of mos solar cells built on /ntype/ in p substrates”, ieee transactions on electron devices, vol. ed-27, 1980, pp. 631-634. [9] k. zeghdar, l. dehimi, a. saadoune, n. sengouga, “iinhomogeneous barrier height effect on the currentvoltage characteristics of an au/n-inp schottky diode ”, journal of semiconductors, vol. 36, no. 12, 2015, article id. 124002 [10] n. balaram, v.r. reddy, p.s. reddy, v. janardhanam, c.j. choi, “microstructural, chemical states and electrical properties of au/cuo/n-inp heterojunction with a cupric oxide interlayer”, vacuum, vol. 152, 2018, pp. 15-24. [11] m. benchehima, h. abid, a. sadoun, a.c. chaouche, "optoelectronic properties of aluminium bismuth antimony ternary alloys for optical telecommunication applications: first-principles calculation ", computational materials science, vol. 155, 2018, pp. 224-234 [12] m. cao, p.v. voorde, m. cox, w. greene, boron diffusion and penetration in ultrathin oxide with poly-si gate, ieee electron device letters, vol 19, 1998, pp. 291293. [13] s. atlas, silvaco international software, santa clara, ca, usa, 2005. [14] a. sadoun, s. mansouri, m. chellali, a. hima, and z. benamara, "the effect of introduction of hfo2 on the electrical characterization of the pt/hfo 2/n-gan," in 2018 international conference on communications and electrical engineering (iccee) ", 2018, pp. 1-4. . [15] a.u.s. manual, silvaco int., santa clara, ca, 2008. [16] j. dziewior, w. schmid, “auger coefficients for highly doped and highly excited silicon”, applied physics letters, vol 31, 1977, pp. 346-348. [17] f. zappa, p. lovati, a. lacaita, “temperature dependence of electron and hole ionization coefficients in inp”, proceedings of 8th international conference on indium phosphide and related materials, ieee, 1996, pp. 628631. [18] c. crowell, s. sze, “current transport in metalsemiconductor barriers”, solid-state electronics, vol 9, 1966, pp. 1035-1048. [19] m. ieong, p.m. solomon, s. laux, h.-s. wong, d. chidambarrao, “comparison of raised and schottky source/drain mosfets using a novel tunneling contact model”, international electron devices meeting 1998. technical digest (cat. no. 98ch36217), ieee, 1998, pp. 733-736. [20] s.m. sze, k.k. ng, book: physics of semiconductor devices, print isbn:9780471143239, john wiley & sons, 2006. [21] a. sadoun, s. mansouri, m. chellali, n. lakhdar, a. hima, and z. benamara, "investigation, analysis and comparison of current-voltage characteristics for au/ni/gan schottky structure using ivt simulation", materials science-poland, vol. 37, 2019, pp. 496-502. [22] a. sadoun, i. kemerchou, “extraction of the electrical parameters of the au/insb/inp schottky diode in the temperature range (300 k425 k) ”, international journal of energetica (ijeca), vol. 5, no. 1, 2020, pp. 31-36. [23] r. padma, b. p. lakshmi, m. s. p. reddy, and v. r. reddy, "electrical and structural properties of ir/ru schottky rectifiers on n-type ingan at different annealing temperatures", vol. 56, 2013, pp. 64-76. [24] v. r. reddy, v. manjunath, v. janardhanam, y.-h. kil, and c.-j. choi, "electrical properties and current transport mechanisms of the au/n-gan schottky structure with solution-processed high-k batio3 interlayer", vol. 43, 2014, pp. 3499-3507. [25] h. norde, “a modified forward i‐ v plot for schottky diodes with high series resistance”, journal of applied physics, vol 50, 1979, pp. 5052. [26] a. kocyigit, i. orak, z. çaldıran, a. turut, “currentvoltage characteristics of au/zno/n-si device in a wide range temperature”, j mater sci: mater electron, vol 28, 2017, pp. 17177–17184. [27] p. chattopadhyay, “a new technique for the determination of barrier height of schottky barrier diodes”, solid-state electronics, vol 38,1995, pp. 739-741. [28] ş. karataş, n. yildirim, a. türüt, “electrical properties and interface state energy distributions of cr/n-si schottky barrier diode”, superlattices and microstructures, vol 64, 2013, pp. 483-494. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 22-26 . http://dx.doi.org/10.47238/ijeca.v5i1.116. june 2020 page 22 numerical study of a new earth-air heat exchanger configuration designed for sahara climates abdessamia hadjadj 1* , abbes attia 2 , abderrahmane khechekhouche 3,4 , nabiha naili 5 , bachir bendjenidi 2 1university of el oued, vtrs laboratory, 39000 el oued, algeria 2university of ouargla, department of mechanical engineering, 30000 ouargla, algeria 3faculty of technology, university of el oued, algeria 4laboratory of electromechanical systems (lasem), enis, university of sfax, tunisia 5energy research and technology center (crten), thermal process laboratory (lpt), tunisia e-mail*: hadjadj-abdessamia@univ-eloued.dz abstract – thermal performance for cooling and heating in the building can be achieved by the novel shape of the earth–air heat exchanger (eahe). in a heavily populated area such as city, due to the limited ground space. eahe systems are rarely used, for most residential andcommercial utilization.this paper presents a numerical investigation of the thermal performance of a spiral-shaped configuration spiral earth to air heat exchanger seahe intended for the summer cooling inhot and arid regions of algeria. a parametric analysis of the seahe has been performed toinvestigate the effect of diameter, depth, pipe length and of airflow rate on the outlet air in theexchanger. results show that the specific heat exchange is used to cool in an arid zone (south-east of algeria). when the ambient temperature varies between 40°c and 45 °c, the coolingtemperature varies between 25°c and 29 °c. temperature difference inlet and outlet airexchanger 18°c, these values are quite acceptable with for cooling the building. keywords: cfd modeling, spiral, heat exchanger, geothermal energy, thermal performance received: 03/05/2020 – accepted: 19/06/2020 i. introduction energy consumption in arid areas is very high due to the high temperature in the summer and the low temperature in the winter. the local cooling needs a considerable consumption of electric energy, which costs very expensive. the warm-up also consumes energy (city gas or other fossil fuels). the utilization of geothermal energy to reduce heating and cooling needs in a building or greenhouse has received increasing attention during the last several years [1-4]. geothermal energy is considered among renewable energy resources which allow easy access to low thermal supply energy without environmental harm. it was considered as a promising space-cooling and heating solution [5-10]. a ground heat exchanger (ghe) is a long underground metal or plastic pipe which draws air through. as air passes through the pipe, during the cooling and heating process, it gives up or receives some of its heat from/to the surrounding soil, and enters the room as cooled or heated air [11-13].recently, many numerical and experimental studies have investigated the heat transfer mechanisms of the various types of hghe several research works have dealt with the exploitation of soil thermal potential for heating and cooling building [14-19]. a ghe system's energy performance is mainly influenced by air temperature, air velocity, geometric dimension, pipe materials, burial lengths of the pipe, soil temperature, and soil type [20]. study on calculation models of earth-air heat exchanger systems. have been performed to investigate the effect of pitch, depth, pipe length and of the flow velocity on the outlet air temperature and the eahe mean efficiency [21,22]. a study developed a cfd model to determine the effect of air velocity and buried pipe material on the performance of eahe system [23]. another project presented a technical and economic studies of an eahe coupled to the system for heating or abdessamia hadjadj et al ijeca-issn: 2543-3717. june 2020 page 23 cooling of a building [24]. an analytical model was compared with the experimental results and the use of a spiral heat exchanger form. the numerical results were obtained with the fluent program. there is a good agreement between the analytical results and the experimental results. the numerical results show that there is a significant difference in temperature between the ambient temperature obtained at the outlet of the exchanger. heat in all cases studied, which offers the possibility of planting this system in desert areas in algeria [25]. the objective of the present paper is to influence extern temperature on earth air heat exchangers in summer. this work aims to demonstrate that a simple pipe placed underground and connected to a building can significantly regulate indoor thermal comfort and thus help in energy savings in hot arid climate conditions. the modeling on heat exchanger study was conducted in the summer, in which the highest cooling demand and the climatic conditions were those of the region of ouargla in the algerian. ii. computational modeling the theoretical model used to research the eahe contains two main parts: the first is correlated to the bare soil for the measurement of initial conditions, and the second is devoted to the ground heat exchanger. for both sections the resolution of the equations together is based on an iterative mathematical method. a spiral earth air heat exchanger (seahe) consists primarily of a pipe buried in the ground made of pvc. the geometric parameters of the used pipe used in the thermal analysis are: length, inside diameter and thickness which is normally 4 mm. seahe is such that the hot outdoor air is drawn into the underground buried pipe with the help of an adequate blower the airs is cooling by transporting heat to the low-temperature soil in figure 1 then inject the cooled air into the house. table 1 represented the thermal and physical properties of air, soil, and pipe used in this simulation, while the parameters of the earth air heat exchanger are presented in table 2. figure.1. diagram representing an seahe table .1. physical and thermal properties material density (kg m-3) thermal capacity (j kg-1 k-1) thermal conductivity (w m-1k-1) air 1.225 1006 0.0262 soil 1758 1000 0,58 pvc 1380 900 0,16 the maximum and minimum monthly temperatures used in site understudy simulation are presented in figure 2. figure .2. monthly maximum and minimum temperatures of the site in ouargla ii.1. soil modeling the soil temperature mathematical model is based upon the principle of heat conduction applied to a semi-infinite homogenous solid. ref gives heat conductions in soil [26, 27]. s t t t z z             (1) where t is the soil temperature (°c). where the soil thermal diffusivity is given by: cp      moy s 0 2π zπ 8760t(z,t)=t +a ×(exp-(z) ×cos ×(t-t )× 8760 πα8760 2       (2) table .2. parameters of the earth air heat exchanger used in the simulation. parameter reference value pipe depth 2.5 m pipe length 54 m air flow rate 50, 80, 100 m 3 /h pipe diameter 110, 200, 250 mm abdessamia hadjadj et al ijeca-issn: 2543-3717. june 2020 page 24 ii.2. earth-air heat exchanger modeling computational fluid dynamics (cfd) methods are quite known for their ability to analyze the fluid flow in depth heat transfer, mass transfer and many other problems. numerical simulations have been conducted using cfd research software. the physical geometry system was utilized to develop a model for numerical analysis in figure 3. the material properties of seahe pipe and surrounding soil were used in the model developed on ansys's workbench platform i.e. ansys's design modeler [19]. material properties of seahe pipe and surrounding soil worked in the simulations are measured values or as specified by the manufacturer. developed physical model of seahe system was meshed using 2d. the numerical studies were based on the following hypotheses: a) thermo-physical properties of soil are homogeneous; b) uniform temperature is assumed along the perimeter of the face of pipe; c) thermal contact among soil and buried pipe is ideal; d) the temperature of the inlet air exchanger is the temperature of the outside air; e) the fluid is assumed viscous "and newtonian; f) the flow in steady state. the definitive differential equations are the mass equation, the equation of momentum, the equation of energy and the standard k -ε model used to close the systems. the standard model kε model is a semiempirical turbulence model based on the kinetic energy turbulence (k) and its dissipation rate (ε). figure.3. physical geometry of straight seahe iii. result and discussions figure 4 different depths (1-5 m). as the depth of the subsoil increases, fluctuations in the sine wave of the soil temperature decrease until the temperature reaches a relatively constant value at 5 m depth, allowing us to use the soil as a heat source (cold/hot). figure .4. soil temperature as a function of depth figure 5 represents to evaluate the influence of the air volume flow rate on the outlet air temperature, but in this case the length, diameter and depth are kept constant (for tin=320.15 k, d=200 mm, z = 2.5 m, and l=54m). the seahe efficiency decreased with the increase of the airflow rate. the outlet temperature of the heat exchanger was obtained to be 310.8 k,309 k and 306.2 k for the average airflow rate value of 50, 80 and 100 m 3 /h. figure.5. temperature profiles at the outlet of the tube for different airflow rate at varied airflow rate, figure 6 shows the evaluated air temperature at the exchanger. in figure 6, there are three different airflow rates of 50, 80 and 100 m 3 /h respectively have been considered to study the effect of air flow rate on the seahe thermal performance. it was observed that the increased airflow velocity causes a decrease in air abdessamia hadjadj et al ijeca-issn: 2543-3717. june 2020 page 25 temperature drops, because of the decreasing residence duration of the flowing air inside the seahe. therefore, the thermal performance deteriorates proportionally with air flow rate increases. figure. 6. outlet air temperature versus exchanger length and air flow rate to highlight the effect of the exchanger diameter, the air temperature the exchanger variations according to the exchanger length for three diameters were represented in figure.7. as seen in figure. 7. it was also observed the increase of the exchanger diameter causes a decrease in the air temperature because of the decreasing residence time of the flowing air inside the seahe. figure .7. outlet air temperature according to the pipe diameter and the exchanger length iv. conclusion the main interest of our study related to the reality that the seahe system is able to decrease a building indoor temperature in arid climate. to achieve efficient seahe, the recommendations can be summarized as follows:  at a depth of 2,5 m, the air temperature decreases from the maximum ambient temperature of 45 °c reaches the soil temperature at about 25 °c.  a maximum gap temperature difference of about 18.7 °c between the inlet temperature and outlet temperature at the exchanger.  the inlet airflow rate effect on the outlet air temperature. increasing the airflow rate from 50 to 100 m 3 /h leads to an increase in the outlet air temperature of the exchanger.  the diameter seahe effect on the outlet air temperature. increasing the airflow rate from 110 to 250 mm leads to an increase in the outlet air temperature of the seahe by two times. references [1] a.k. chaturvedi, v. bartaria, "performance of earth tube heat exchanger cooling of air—a review", int j mech eng robotics res, vol 4, no 1, 2015, pp. 378-382. [2] m.h. benzaama, s. menhoudj, c. maalouf, a. mokhtari, m. lachi, "experimental and numerical analysis of the energy performance of a water/soil exchanger coupled to a cooling floor for north africa", geothermics, vol 80, no 1, 2019, pp. 8-19. [3] r. singh, r. sawhney, i. lazarus, v. kishore, "recent advancements in earth air tunnel heat exchanger (eathe) system for indoor thermal comfort application: a review", renewable sustainable energy reviews, vol 82, 2018, pp. 2162-2185. [4] a. atia, a. hadjadj, b. benhaoua, n. lebbihiat, a. brima, "a review of studies on geothermal energy system applied on sub-saharan climate regions", water and energy international, vol 60, no 5, 2017, pp. 63-68. [5] i. johnston, g. narsilio, s. colls, "emerging geothermal energy technologies", ksce journal of civil engineering, vol 154, no 4, 2011, pp. 643-653. [6] c.k. lee, "effects of multiple ground layers on thermal response test analysis and ground-source heat pump simulation", applied energy, vol 88, no 12, 2011, pp. 4405-4410. [7] p. bayer, d. saner, s. bolay, l. rybach, p. blum, "greenhouse gas emission savings of ground source heat pump systems in europe: a review", renewable sustainable energy reviews, vol 16, no 2, 2012, pp. 1256-1267. [8] c. zhang, z. guo, y. liu, x. cong, d. peng, "a review on thermal response test of ground-coupled heat pump systems, renewable sustainable energy reviews, vol 40, 2014, pp. 851-867. [9] m. kaushal, "geothermal cooling/heating using ground heat exchanger for various experimental and analytical studies: comprehensive review", energy buildings, vol 139, 2017, pp. 634-652. abdessamia hadjadj et al ijeca-issn: 2543-3717. june 2020 page 26 [10] v. bansal, r. misra, g.d. agrawal, j. mathur, "performance analysis of earth–pipe–air heat exchanger for summer cooling", energy buildings, vol 42, no 5, 2010, pp. 645-648. [11] d. belatrache, s. bentouba, m. bourouis, "numerical analysis of earth air heat exchangers at operating conditions in arid climates", international journal of hydrogen energy, vol 42, no 13, 2017, pp. 8898-8904. [12] m. benhammou, b. draoui, m. hamouda, "improvement of the summer cooling induced by an earth-to-air heat exchanger integrated in a residential building under hot and arid climate", applied energy, vol 208, 2017, pp. 428-445. [13] a. pintoro, t.u.h.s.g. manik, t.b. sitorus, e.a. sihombing, "the experimental study and numerical of pipe finned as a earth-air heat exchangers", iop conference series: materials science and engineering, vol 505, no, 2019, pp. 012059. [14] m. khabbaz, b. benhamou, k. limam, p. hollmuller, h. hamdi, a. bennouna, "experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate", energy buildings, vol 125, 2016, pp. 109-121. [15] s. jakhar, r. misra, m. soni, n. gakkhar, "parametric simulation and experimental analysis of earth air heat exchanger with solar air heating duct", engineering science technology, an international journal, vol 19, no 2, 2016, pp. 1059-1066. [16] ł. amanowicz, j. wojtkowiak, validation of cfd model for simulation of multi-pipe earth-to-air heat exchangers (eahes) flow performance", thermal science and engineering progress, vol 5, 2018, pp. 44-49. [17] a. mathur, a. srivastava, g. agrawal, s. mathur, j. mathur, "cfd analysis of eathe system under transient conditions for intermittent operation", energy buildings, vol 87, 2015, pp. 37-44. [18] a. mathur, s. mathur, g. agrawal, j. mathur, "comparative study of straight and spiral earth air tunnel heat exchanger system operated in cooling and heating modes", renewable energy, vol 108, 2017, pp. 474-487. [19] a. hadjadj, b. benhaoua, a. atia, a. khechekhouche, n. lebbihiat, a. rouag, "air velocity effect on geothermal helicoidally water-air heat exchanger under el oued climate -algeria", thermal science and engineering progress, 2020, pp. 100548. [20] t.s. bisoniya, a. kumar, p. baredar, "study on calculation models of earth-air heat exchanger systems", journal of energy, 2014. [21] n. benrachi, m. ouzzane, a. smaili, l. lamarche, m. badache, w. maref, "numerical parametric study of a new earth-air heat exchanger configuration designed for hot and arid climates", international journal of green energy, vol 17, no 2, 2020, pp. 115-126. [22] a.a. serageldin, a.k. abdelrahman, s.j.e.c. ookawara, "earth-air heat exchanger thermal performance in egyptian conditions: experimental results, mathematical model, and computational fluid dynamics simulation", energy conversion management, vol 122, no, 2016, pp. 25-38. [23] v. bansal, r. misra, g.d. agrawal, j. mathur, "performance analysis of earth–pipe–air heat exchanger for winter heating", energy buildings, vol 41, no 11, 2009, pp. 1151-1154. [24] m. bojic, n. trifunovic, g. papadakis, s. kyritsis, "numerical simulation, technical and economic evaluation of air-to-earth heat exchanger coupled to a building", energy, vol 22, no 12, 1997, pp. 1151-1158. [25] m.h. benzaama, s. menhoudj, k.j. kontoleon, a.m. mokhtari, m.c. lekhal, "investigation of the thermal behavior of a combined geothermal system for cooling with regards to algeria’s climate", sustainable cities and society, vol 43, 2018, pp. 121-133. [26] h.b.j. derbel, o. kanoun, "investigation of the ground thermal potential in tunisia focused towards heating and cooling applications", applied thermal engineering, vol 30, no 10, 2010, pp. 1091-1100. [27] f. al-ajmi, d. loveday, v.i. hanby, "the cooling potential of earth–air heat exchangers for domestic buildings in a desert climate", building environment, vol 41, no 3, 2006, pp. 235-244. i. introduction ii. computational modeling iii. result and discussions references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 14-20 ijeca-issn: 2543-3717. december 2019 page 14 control of 3x7 matrix converter with pwm three intervals modulation mohamed mounir rezaoui 1* , noureddine bessous 2 , imad merzouk 1 1laadi, faculty of science and technology, university of djelfa 17000 dz, algeria 2faculty of science and technology, university of el oued 39000 dz, algeria mm_rezaoui@yahoo.fr abstract – direct power conversion from fixed ac voltage into variable ac voltage is gaining a significant attention, especially in case of multi-phases machines/generators; for such reason a new algorithm to control 3x7 matrix converter (mc) is developed in this paper, wherein the main aim is to control multi-phases induction motor/generator connected to the electrical grid with a novel converter (except matrix converter), for that the pwm three intervals modulation strategy is modified from the control of 3x3 mc to 3x7 mc; which is directly connected to the network through a three phase input in order to overcome the supplying problems, on the other side seven phases have been used as an output to benefit the advantages of the multi-phases machines. this paper intends in the first place to explain the 3x3 mc, then to manipulate the control equation for the purpose of making it suitable for controlling the 3x7 mc effectively, thus a good performance can be clearly seen according to the quality of the output voltage/current under typical r-l load, the shift between phases and the thd evaluation. the obtained simulation results which demonstrate the efficiency of the new control algorithm are presented and discussed. keywords: 3x3 matrix converter, 3x7 matrix converter, pwm three intervals, r-l load, thd. received: 07/10/2019 – accepted: 15/11/2019 nomenclature ur, us, ut ua, ub, … r, l wi, wo m, r sij ii, io fi/ fo mij t ud, u + , u [mr(t)] [mo(t)] ucmk input voltages of matrix converter matrix converter output voltages load parameters input/ output pulsation modulation index, modulation rate switch input / output currents input / output frequency relative conduction time during the kth sequence time intermediate virtual potential, virtual positive potential and virtual negative potential rectifier matrix function inverter matrix function modulation function abder image placée m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 15 i. introduction: in industrial applications the current absorbed by the machine is very high, this will demand a special calibration for the switches current/voltage, high cost and protection (means: winding in the motor and switches in the converter) [1-3]. one of many solutions to resolve this problem is to enlarge the number of output phases which will increase the number of the switches in the converter (more output phases means more switches which leads to a less current through the switches by keeping the same power) [3-5]. in order to achieve this target, the authors of this paper are interested in the multi-phases machines and converters. moreover, these machines can reduce the amplitude and increase the frequency of torque ripple [610]. however, the matrix converter has several advantages compared to the conventional converter [7-8]. it is obvious that this it is an ac-ac converter without dc link connected to the input. on the other side the passive elements of the energy storage, which form the intermediate circuit (generally capacitors) between the ac-dc conversion stage and the inverter are eliminated. it is therefore possible to reduce considerably the volume and the cost of the conversion stage [9-18]. the symmetry structure of the matrix converter allows ensuring the energy recovery directly to the supply system [9] [19-20]. in previous work, researchers are working hard on the 3x3 matrix converter (used 9 switches), three-phase has been used in the input, and similarly for the output; in this paper the 3x7 matrix converter (used 21 switches) is taken for example with r-l load, supplied by a three-phase network to avoid the problem of the specific supply of the multiphases machine[13 -14], therefore the model of a. schuster [10], is successfully modified, which will allow to write equations to facilitate the control of (3x7) matrix converter. current advances in power electronics and the development of computing processors can consider a finer control of these machines by using pwm techniques [1525]. the main objective of the study of this converter is to use a modern converter and benefit from the advantages of the multi-phases machines by modifying the same equations, so a new control algorithm is developed to ensure this conversion function. in this paper, the proposed control strategy is studied and analyzed with simulation results of the waveform quality of the output voltage/ current and their thd are also discussed. ii. modeling of the matrix converter the matrix converter is a static frequency and voltage converter, it allows outwardly obtaining a multi-phases voltage: amplitude and frequency, from a power supply network multi-phase voltages [11-13]. this converter topology is characterized by a matrix of twenty-one switches (3x7 matrix); network three phases in the input are connected to seven phases to feed a load through a bidirectional power switches. one switch of the matrix converter can be modelled by two diodes and two transistors [6, 10].    figure 1. schematic diagram 3x7 matrix converter since the converter is ideally coupled, the principle of causality leads to precise rules concerning the different states of the switches [1, 3]:  sources located on both sides of the group are necessarily different in their nature.  operating continuity requires energy to be retained, among the possible configurations of the operative part that are physically possible are: a non-zero voltage source can be short-circuited, a voltage source to zero can be set open circuit. finally, the number of the permissible configurations is reduced to 3 7 . table 1. matrix converter configurations of one output phase the configuration the value of output voltage «phase a» related to the input voltages e1 ua=ur e2 ua=us e3 ua=ut the cellular commutations present a symmetrical function and consequently a symmetrical control. the converter study intends to reduce the number of cellular commutations [10-13]; in this case three possible configurations appear, each of them is characterized by a quantity like it shown in table 1. iii. control strategy of matrix converter the principe of its control is based on the analogy of the indirect converter with an intermediate fictitious circuit (rectifier / inverter) [6, 10]. so to talk about the m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 16 complexity of the matrix converter control, the rectifier and the inverter parts are studied separately. figure 2. model of the 3x7 matrix converter with middle fictitious circuit the fact that at any given time, it must be at least one positive phase of the supply voltages and at least another negative one relative to neutral power, one can choose fictitious potentials u + and u like: d u u u   (1) figure 3. curve of the input voltages and virtual potentials in order to easily implement the rectifier, the matrix of the rectifier is defined to allow the connection between the input voltages and the intermediate part as follows [6, 10]:     cos 3 0 1 cos               (2) the table of the function of modulation τ is elaborated by a. schuster [10]: ( )r r s t m t v u r s t v u r s t v                                (3)       sin sin 2 3 sin 4 3 r m i s m i t m i v v t v v t v v t              (4) considering the symmetry founded in the recovery period, six intervals will appear as shown in figure 3. the functions ucmk of modulations will be introduced to be able to take continuous values between 0 and 1 to define the matrix modulation [m0]. this allows to create a link between the middle potential and the output voltages of the matrix converter, as follows: 1 1 2 2 3 3 4 4 5 5 6 6 7 7 ( ) 1 1 1 1 1 1 1 a cm cm b cm cm c cm cm d cm cm e cm cm f cm cm g cm cm mo t v u u v u u v u u v u u v u u v u u v u u u u                                                    (5) the equation (6) is obtained from the combination of the two equations (3) and (5): 1 1 2 2 3 3 4 4 5 5 6 6 7 7 1 1 1 1 1 1 1 g a cm cm b cm cm c cm cm r d cm cm s e cm cm t f cm cm g cm cm f v u u v u u v u u v r s t v u u v r s t v u u v v u u v u u                                                                 (6) it finally comes to characterize the matrix g f   which allows to define the complete algorithm for the frequency conversion such as: g g g ra sa taa g g g rb sb tbb g g g rc sc tcc r g g g rd sd tdd s gg g e sere te t g g g f rf sf tf g gg g rg tgsg f f fv f f fv f f fv v f f fv v v ff f v v f f f v f ff                                             (7) the output reference voltage phases are defined as follows: 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 -400 -300 -200 -100 0 100 200 300 400 500 600 time(s) in p u t v o lta g e s a n d v ir tu a l p o te n tia ls ( v ) v in3 v in1 v in2 u + u u d m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 17               sin sin 2 / 7 sin 4 / 7 sin 6 / 7 sin 8 / 7 sin 10 / 7 sin 12 / 7 a m o b m o c m o d m o e m o f m o g m o v v t v v t v v t v v t v v t v v t v v t                                   (8) with: 2o of  determining the functions of waves (standard reference functions) consists to modulate the fictitious middle voltage given above:   1 cos sin 2( 1) 7 2 cmk ou r t k             (9) k = 1, 2, …, 7. the pwm is a well-established technique for the multi-pulse converters. for that, the control of matrix converter in each output phase must be switched at each input phase during a specified range of the pulse period; therefore, the pulse period must be divided into three intervals (number of input phases). for such reason, a technique similar to the one used in the conventional pwm modulators has been adopted [9]; the saw tooth reference signal will be compared to a control signal, a binary signal by phase will be generated according to the comparison, for the purpose of indicating the state of the power switch. the carrier equation is defined as follows: 0 p p t u t t t    (10) the output binary signals xi of pwm modulator is defined as follow [10]: 1 0 if xi p i u x not      (11) by taking into account the previous equations, the reference signals τx are defined as: x1k x2k (1 ) (1 ) cmk cmk cmk cmk r u r u s u s u               (12) iv. simulations and results to have an overview about the behaviours of the presented algorithm, which has been tested by a simulation with r l load ( 20r   , 10l mh ), the input voltages of the matrix converter is considered as a typical three-phase system which is characterized by a magnitude of 220 v and 50 hz as a frequency, the switching frequency is chosen to be 2500hz with a modulation index r=0.8. the output voltages and currents obtained by the application of the modified pwm three intervals algorithm are presented in figure 4 and figure 5 respectively, the output voltages follow perfectly the reference, whereas in figure.5 the output currents are shown, it is clearly noticed that the resulting output current drawing a nearly sinusoidal waveform. the shift between voltage and the current (5x i) are showed in figure.6 and figure.7. whereas in figure. 8 the input currents of 3x7 matrix converter are presented. figure 9 output voltage compared to the output current on the other side the harmonic spectrum of the output voltage, output current and the input current are represented in figure 9, figure 10 and figure 11 respectively. in table .2, a summary of same results including thd and the fundamental values of the output voltage and input/output currents. it is obvious that the using of this algorithm ensures the maximum magnitude with a less thd compared with 3x3 matrix converter [6]; or 3x5 matrix converter [13]; on the other hand, the obtained output current is better and acceptable thd results from point of view of the sine waveform quality. the output current resulting from the adaptation of the proposed algorithm presents more important ripple which is characterized by thd = 15.87%. table 2. values of the fundamentals and their thd values thd fundamental output voltage 59.74 % 290.00 v output current 15.87 % 14.32 a input current 52.61 % 31.39 a m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 18 figure 4. output voltages of 3x7 matrix converter figure 5. output currents of 3x7 matrix converter figure 6. input voltage compared to the input current figure 7. output voltage compared to the output current figure 8. output currents of 3x7 matrix converter m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 19 figure 9. the harmonic spectra of output voltage figure 10. the harmonic spectra of output current figure 11. the harmonic spectra of input current v. conclusion in the present work, a modified pwm three intervals algorithm is applied to control a 3x7 matrix converter. simulation experiments of the proposed approach are achieved and the results which clarifying its behaviour are presented and discussed; after the examination of this method, it was found that the output voltages and input/output currents have an acceptable waveform, and thus allows obtaining better results. on the other side, the output voltages of 3x7 matrix converter are following perfectly their reference, which has been given a value of 290 v with a thd of 59.74 %. the shift between phases is equal to 0/ 7 51.43rad or , which represents the shift phase between the output voltages and the output currents. finally, the proposed algorithm gives better results and ensuring more flexibility and suitability when used for the control of the 3x7 matrix converter. references [1] k. bedoud, a. rhif, t. bahi, h. merabet. “study of a double fed induction generator using matrix converter: case of wind energy conversion system”. international journal of hydrogen energy, vol. 43, no 25, 2018, pp. 11432-11441. [2] m. ali, a. iqbal, m. rizwan khan, m. ayyub, m.a. anees. “generalized theory and analysis of scalar modulation techniques for a mxn matrix converter”. ieee transactions on power electronics, vol. 32, no 6, 2017, pp. 4864-4877. [3] m. ali, a. iqbal, m. rizwan khan. “4: ac-ac converters”. science direct. 4th edition power electronics handbook, 2018, pp. 417-456. [4] n.h. saad, a.a. el-sattar, m.e. marei. “improved bacterial foraging optimization for grid connected wind energy conversion system based pmsg with matrix converter”. ain shams engineering journal, vol. 9 , no 4, 2018, pp. 92183-2193. [5] p. gambôa, j.f. silva, s.f. pinto, e. margato. “input–output linearization and pi controllers for ac–ac matrix converter based dynamic voltage restorers with flywheel energy storage: a comparison”. electric power systems research, vol. 169, 2019, pp. 214-228. [6] m.m. rezaoui, l. nezli, m.o. mahmoudi. “high performances of five–phase induction machine feeding by a [3×5] matrix converter”. journal of electrical engineering (jee), vol. 65, no 2, 2014, pp. 83–89. [7] t.d. nguyen, h.h. lee. “carrier-based pwm technique for three-to-five phase indirect matrix converters”. iecon’11 37th annual conference on ieee transactions on industrial electronics society, 2011, pp. 3662–3667. [8] a. djahbar, b. mazafu, m. latroch. “control strategy of three-phase matrix converter fed induction motor drive system”. ieee international workshop on intelligent signal processing, 2005, pp. 104-109. [9] j. rodriguez, m. rivera, j.w. kolar, p.w. wheeler. “a review of control and modulation methods for matrix converters”. ieee transactions on industrial electronics, 59(1), 2012, pp. 58-70. [10] a. schuster. “a drive system with a digitally controlled matrix converter feeding an ac induction machine”. ieee conference on power electronics and variable speed drives, nottingham, uk, 1996, pp. 23-25. [11] o. abdel-rahim, h. abu-rub, a. iqbal, a. kouzou. “five-to-three phase direct matrix converter with model predictive control”, power engineering, energy and electrical drives (powereng) ”, 2013 fourth international conference on, istanbul, turkey, 13-17 may 2013. [12] s. moin ahmed, h. abu-rub, , z. salam, a. iqbal, “dual matrix converters based seven-phase open-end winding drive”. ieee, 23rd international m mohamed mounir rezaoui et al ijeca-issn: 2543-3717. december 2019 page 20 symposium on industrial electronics (isie), istanbul, turkey, 1-4 june 2014. [13] m.m. rezaoui, l. nezli, m.o. mahmoudi, a. kouzou, h. abu rub. “a modified pwm three intervals control for a matrix converter in real time”. archives of control sciences (acs), vol. 24 , no 1, 2014, 85-98. [14] o. abdel-rahima, h. abu-ruba, a. kouzou. “nineto-three phase direct matrix converter with model predictive control for wind generation system”. energy procedia, (vol. 42), 2013, pp. 173–182. [15] t.d. nguyen, l. hong-hee. “development of a three-to-five-phase indirect matrix converter with carrier-based pwm based on space-vector modulation analysis”. ieee transactions on industrial electronics”, vol. 63, no 1, 2016, pp. 13 24. [16] c. klumpner, f. blaabjerg, i. boldea, p. nielsen. “new modulation method for matrix converters. ieee transactions on industry applications”, vol. 42, no 3, 2006, pp. 797–806. https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=41 https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.c.%20klumpner.qt.&newsearch=true https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.f.%20blaabjerg.qt.&newsearch=true the table of the function of modulation τ is elaborated by a. schuster [10]: considering the symmetry founded in the recovery period, six intervals will appear as shown in figure 3. the functions ucmk of modulations will be introduced to be able to take continuous values between 0 and 1 to define the atrix modulation [m0]. this allows to create a link between the middle potential and the output voltages of the matrix converter, as follows: the equation (6) is obtained from the combination of the two equations (3) and (5): international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 42-46 ijeca-issn: 2543-3717. december 2020 page 42 numerical simulation of the flow rate effect on the evolution of a negatively buoyant water jet oumaima eleuch 1 , noureddine latrache 2 , sobhi frikha 1 , abderrahmane khechekhouche 3,1 , zied driss *1 1 laboratory of electro-mechanic systems (lasem), national school of engineers of sfax (enis), university of sfax, tunisia 2 university of brest, fre cnrs 3744 irdl, 29238 brest, france 3 technology faculty, university of el-oued, algeria email * : zied.driss@enis.tn abstract – a numerical simulation study was done on a penetrating pure water jet injected into another surrounding salt water miscible with negative buoyancy conditions. for the incompressible filtered navier-stokes equations and the sum of the fluid model volume, we used a transient computational fluid dynamics (cfd) solver (vof model). a finite volume discretization method using open source code given in open foam 2.3.0. was used to solve these equations. the flow has a significant impact in the laminar system on the evolution of the jet in terms of subsequent permanent phase as well as transient regime. keywords: pure water jet, saltwater, transient penetration, stationary profile. received: 21/11/2020 – accepted: 25/12/2020 i. introduction the mixing of fluids at a difference in temperature, concentration or density has been the subject of several scientific studies in the world. when a fluid is pumped into another fluid of different density, fountains or negatively buoyant plumes arise where the buoyancy force opposes the momentum flux. prior to collapsing back around itself, the injected fluid penetrates a distance into the environment. in a number of configurations, including round fountains, planar fountains, fountains affecting a solid surface and fountains penetrating an interface, there have been various studies examining fountain behavior. depending on the ratio of buoyancy and momentum flux, and also as laminar or turbulent, fountain flow can be defined as weak or forced. using numerical simulation over the parametric range 0.25<fr<10, 50<re<150, pr=7, 300 and 700 [1], the findings show that the behavior of plane laminar fountains with parabolic velocity inlet profile. the flow behavior is most strongly influenced by the number of froude and, to a lesser extent, by the number of reynolds, especially for poor fountains at low numbers of reynolds. in order to examine their results, a group of researchers examined the upward discharge of a floating plume in a two-layer stratified ambient medium and used the phenomenon of the stratification which is based on the difference in the density parameter in the flow [2]. the turbulent fountains were the subject of most early studies [3-5]. in comparison, only a few studies have been devoted to the case of laminar jets. in these cases, the weak laminar plane fountains exhibit both a uniform and parabolic profile of the discharge velocity at the source. in addition, the original, temporary and final characteristics of the fountain heights and the times for the front of the fountain to hit these heights were calculated and scaled [6]. the effect of flow rate on the penetration of a laminar pure water jet within miscible saltwater is investigated numerically in this paper. the increase in the flow rate allows the penetration depth to increase and the steadystate phase to be steadily reached. ii. numerical method the 3d numerical method was adopted to simulate the flow of the buoyant pure water jet in miscible saltwater. oumaima eleuch et al. ijeca-issn: 2543-3717. december 2020 page 43 the laminar flow is governed by the equations of navierstokes and the volume of the fluid model with the boussinesq approximation, which were solved by the finite volume method treated by open foam [7]. the further dependence test of the mesh is performed to a grid system of 77x150x77. figure 1 presents the computational domain and boundary conditions. the inlet boundary of the jet is defined as velocity-inlet. a value of p = 101325 pa is known for the outlet pressure, which means that the fluid will exit the model to an environment of static atmospheric pressure at the opening of the tank, where the nozzle is. figure 1. boundary conditions iii. results and discussion iii.1. volume fraction the jet evolution penetrates in the salt water through the nozzle with a diameter d = 1.37 mm and for different values of the flow rate equal to q = 0.047 cm 3 .s -1 , q = 0.065 cm 3 .s -1 , q = 0.086 cm 3 .s -1 and q = 0.132 cm 3 .s -1 . the results obtained are shown in the figures for different instances equal to t = 0.08 s in figure 2, t = 0.25 s in figure 3, t = 0.5 s in figure 4, t = 1 s in figure 5 and t = 1.5 s in figure 6. based on these results, it has been observed an increase in the depth and the width of the jet in each instance when the flow rate increases. this fact is due to the increase of the initial velocity of the flow with a constant section of the nozzle that allows the increase of the reynolds number corresponding to a laminar regime. in these conditions, it has been observed that there is more mixing layer in the boundary between the jet of lighter water and the denser water when the flow rate rises. indeed, the head of the jet contains more pure water (α=1) for the small values of the flow rate q. at t=0.08 s (a) q=0.047 cm 3 .s -1 (b) q=0.065 cm 3 .s -1 (c) q=0.086 cm 3 .s -1 (d) q=0.132 cm 3 .s -1 figure 2. distribution of the volume fraction of the jet in the plane z=0 mm at t=0.08 s (a) q=0.047 cm 3 .s -1 (b) q=0.065 cm 3 .s -1 oumaima eleuch et al. ijeca-issn: 2543-3717. december 2020 page 44 (c) q=0.086 cm 3 .s -1 (d) q=0.132 cm 3 .s -1 figure 3. distribution of the volume fraction of the jet in the plane z=0 mm at t=0.25 s (a) q=0.047 cm 3 .s -1 (b) q=0.065 cm 3 .s -1 (c) q=0.086 cm 3 .s -1 (d) q=0.132 cm 3 .s -1 figure 4. distribution of the volume fraction of the jet in the plane z=0 mm at t=0.5 s (a) q=0.047 cm 3 .s -1 (b) q=0.065 cm 3 .s -1 (c) q=0.086 cm 3 .s -1 (d) q=0.132 cm 3 .s -1 figure 5. distribution of the volume fraction of the jet in the plane z=0 mm at t=1 s iii.2. transient penetration the beginning of penetration of the liquid jet is made by the initial velocity. this velocity decreases up to zero because of the inverse buoyancy force and the viscous drag in the whole tank despite that the jet continues to penetrate in the outer liquid by gravity effect. in this transient regime, we have performed for a few values of the flow rate q the temporal evolution of the depth as shown in figure 6. according to these data, it has been reported that the depth of the penetration increases with the flow rate q. furthermore, the jet takes more time in the transient penetration for the high flow rate. however, when the flow rate decreases, the maximum depth and the steady-state system are easily reached by the jet. in table 1, the maximal penetration depth of the jet and the transient time needed to achieve this maximal depth are summarized for four flow rates in the same conditions. oumaima eleuch et al. ijeca-issn: 2543-3717. december 2020 page 45 figure 6. penetration of the jet head table 1. variation of the maximal penetration depth for four different flow rates flow rate q (cm 3 .s -1 ) time t (s) maximal penetration depth h (m) 0.047 0.75 0.0064 0.065 1 0.0096 0.086 1.5 0.014 0.132 2 0.02595 iii.3. stationary profile of the jet the variance of the penetration depth h of the jet is presented in figure 7 as a function of it’s a dimensionless width at four different injection flow rates. these results confirm that the profile of the jet in depth and width at the same time just after the steady-state is reached under the same condition. for each value of q, the curve has a horizontal asymptote in h=hs. indeed, it has been observed that once the jet penetrates the tank, the depth increases with the width in the transient phase with the presence of miscibility between the outer and the inner liquids. when the jet reaches the steady-state regime and the depth rest constant with h=hs in few seconds before rising back, the head of the jet continues to expel radially. to compare between the considered flow rates, it has been observed that for the big value of flow rate q=0.132 cm 3 .s -1 , the jet is wider and spreads easily despite it needs more time to reaches the steady-state regime. thus, the decreasing of the flow rate allows decreasing of the width of the jet with low penetration depth and fast steady-state phase. figure 7. profile of the jet for different flow rates iv. conclusion in this paper, negatively buoyant jet flow, induced by vertical injection of pure water downward into saltwater, has been affected by the flow rate of the jet. the numerical results show that the penetration depth of the jet inside the denser water increases with the increase of the flow rate. whereas, the jet reaches slowly the maximal depth and the stationary regime. nomenclature d fr h p pr q re t v α : diameter (mm) : froude number : penetration depth (m) : pressure (pa) : prandtl number : flow rate (cm 3 .s -1 ) : reynolds number : time (s) : velocity (m/s) : jet contains, α=1 for pure water references [1] n. srinarayana, s.w. armfield, l. wenxian, “behavior of laminar plane fountains with a parabolic inlet velocity profile in a homogeneous fluid”, international journal of thermal sciences, vol 67, 2013, pp. 87-95. [2] g. noutsopoulos, k. nanou, “the round jet in a two-layer stratified ambient”, proc. intl symp. on buoyant flows: athens-greece 1–5, 1986, pp. 165–183. [3] t. mizushina, f. ogino, h. takeuchi, h. ikawa, “an experimental study of vertical turbulent jet with negative buoyancy”, warme and stoffubertragung (thermo and oumaima eleuch et al. ijeca-issn: 2543-3717. december 2020 page 46 fluid dynamics), vol 16, 1982, pp. 15–21. [4] i. h. campbell, j. s. turner, “fountains in magma chambers”, journal of petrology, vol 30, 1989, pp. 885923. [5] w. d. bains, j. s. turner, i. h. campbell, “turbulent fountains in an open chamber”, j. fluid mech 212, 1990, pp. 557-592. [6] w. lin, s. w. armfield, “direct simulation of weak laminar plane fountains in a homogeneous fluid”, international journal of heat and mass transfer, vol 43, 2000, pp. 3013-3026. [7] z. driss, o. mlayah, s. driss, m. maaloul, m. s. abid, “study of the incidence angle effect on the aerodynamic structure characteristics of an incurved savonius wind rotor placed in a wind tunnel”, energy, vol 113, 2016, pp. 894-908. ijeca-issn: 2543-3717. june 2021 page 7 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 07-12 solar thermo-chemical process assisting a pressure oxidation process for co-production of electricity and metal omar behar 1,2* , daniel sbarbaro 1,2 , luis moran 1,2 1 solar energy research center (serc-chile), santiago de chile, chile. 2 department of electrical engineering, university of concepcion, concepcion, chile email*: beharomar@gmail.com abs tract –the mining industry is look ing at the use of solar energy to address issues related to highly variable energy prices, falling ore grades, and increasing concern about the industry’s carbon footprint. the pressure oxidation of ore sulfides is an economic alternative to the smelting process because it has the potential to reduce energy consump tion and treat low-grade ores. in the pressure oxidation of ore sulfides, the purity and utilization of oxygen are k ey factors. indeed, oxygen production and consumption constitute the major operating cost of the pressure oxidation process. solar thermo-chemical looping processes have been identified as one of the most efficient pathways for the production and storage of oxygen. this study investigates the integration of a solar thermo-chemical looping process with a pressure oxidation process to treat ore sulfide and produce electricity. the analysis shows that the temperature of the cold storage tank has a strong influence on the performance of the complete system. the increase in the cold tank temperature results in a sharp decrease in the size of the receiver. this reduce the investment costs for both the solar receiver and the heliostat field. for the considered case, the useful heat of the solar receiver is 3.7 mwth when the cold tank temperature is set at 100°c. if the cold tank temperature is set at 400°c, the required useful solar heat is about 3.1 mwth and the nominal output of the gas turbine is 0.56 mwe. the analysis showed that about 80% of the useful solar heat can be used to generate oxygen when the temperature of the cold tank is as high as that of the reduction reaction. keywords: solar thermo-chemical, pressure oxidation, energy storage, oxygen production, oxidation / reduction, solar mining process. received: 24/04/2021 – accepted: 03/06/2021 nomenclature subscript d diameter c compressor h enthalpy ele electric mass flow rate ge electric generator p pressure in inlet q heat mec mechanic t time out outlet t temperature t turbine w work rec receiver x conversion red reduction η efficiency st storage http://www.ijeca.info/ http://www.ijeca.info/ mailto:beharomar@gmail.com omar behar et al. ijeca-issn: 2543-3717. june 2021 page 8 i. introduction conventional mining processes depend on hydrocarbon resources for producing metals [1]. these processes are highly energy and carbon intensive [2]. the issues of fossil fuel depletion and climate change have pushed scientists to develop innovative solar mining processes [3-6]. concentrated solar technology offers the option of converting solar energy into heat, electricity and chemical forms. processes that make use of solar heat to drive high temperature endothermic chemical reactions are known as solar thermochemical processes. solar thermochemical processes has huge potential in industries like metal [7]. previous published studies showed that metals can be produced from their metal oxides, using solar thermos -chemical process, mainly by three methods: direct dissociation, carbothermal reduction process, and methanoth ermal reduction process [7]. the implementation of one of the three cited processes require changes in the existing mining processes. however, suitable use of solar energy in the existing mining processes should has relatively low investment costs to be accepted by the mining industry. we propose the integration of a solar thermos -chemical process into an existing solar mining process, known as, pressure oxidation process (pox). the existing pox require just minor changes to be coupled with the solar process. in the pox an autoclave reactor working at high temperature and pressure is used to oxidize ore sulfides [8, 9]. high-pressure oxygen is introduced into the autoclave in such a way as to maximize the dissolution of the gas into the solution phase. once dissolved in the solution, oxygen reacts exothermically with ore sulfides to produce oxide minerals. the purity and the utilization of oxygen are key factors in the pox since oxygen production and consumption constitute the major operating cost of the process [10]. this study investigates the integration of a solar thermo-chemical looping process (scl) with a pox to treat ore sulfides and produce electricity. ii. description of the complete system typical industrial pox is illustrated in figure 1. oxygen is feed to the autoclave reactor to reacts exothermically with ore sulfides and produce oxide minerals. the first commercial pox was implemented to treat refractory gold while the second one was implemented to treat copper concentrate [9]. in the present study, solar energy is used to generate storable electricity and oxygen thanks to the two storage tanks. the particles are stored in the hot tank. they are then sent to the air reactor where cu2o is oxidized to produce heat (4 cuo(s) + o2(g)=>2 cu2o(s)). cuo/cu2o redox pair is selected because it has a high oxygen transport capacity and is relatively cheap and the driving force of the redox reactions is the change in the pressure of oxygen in the gas phase [3]. to promote the reduction reaction in the solar receiver, steam is used to control the partial pressure of oxygen. the vitiated compressed air in the air reactor is expended in the gas turbine cycle to produce electricity. the o2/steam mixture is sent to the pox tank where it is used to oxidize ore sulfides. figure 1. t ypical pressure oxidation process [10] the proposed scl-pox to treat ore sulfides and produce electricity is depicted in figure 2. it consists mainly of a solar particles loop, a modified gas turbine cycle, and a pox tank. the solar particles loop mainly consists of a solar reductor, a hot storage tank, a cold storage tank, and an air reactor. a mixture of particles composed of cuo as the active ingredient and mgal2o4 as the inert support is used as the working fluid of the scl process. initially, the cuo/mgal2o4 particles are sent to the solar reductor where cuo is reduced to cu 2o (4cuo(s) => 2cu2o(s) + o2(g)). next, the particles are stored in the hot tank. they are then sent to the air reactor where cu 2o is oxidized to produce heat (4 cuo(s) + o2(g)=>2 cu2o(s)). cuo/cu2o redox pair is selected because it has a high oxygen transport capacity and is relatively cheap and the driving force of the redox reactions is the change in the pressure of oxygen in the gas phase [12]. omar behar et al. ijeca-issn: 2543-3717. june 2021 page 9 gt 4 in the reactor, cu2o(s) is oxidized to produce heat, which is used to power the gas turbine combine cycle. 2𝐶𝑢2𝑂(𝑠) + 𝑂2(𝑔) → 4𝐶𝑢𝑂(𝑠) (5) the work of the gas turbine unit is given by the following expression: w = w t−wc 𝑦𝑚𝑒𝑐𝑦𝑒𝑙𝑒 (6) figure 2. schemat ic presentation of coupling a solar chemical looping process wit h a pressure oxidat ion process t o t reat ore sulfides and produce elect ricit y. to promote the reduction reaction in the solar receiver, steam is used to control the partial pressure of oxygen. the vitiated compressed air in the air reactor is expended in the gas turbine cycle to produce electricity. the o2/steam mixture is sent to the pox tank where it is used to oxidize ore sulfides. iii. modeling of the system in the solar receiver, cuo-particles are reduced to cu2o using concentrated solar heat through the following endothermic reaction: 4𝐶𝑢𝑂(𝑠) → 2𝐶𝑢 𝑂(𝑠) + 𝑂 (𝑔) (1) wt and wc are respectively the work of the turbine and the compressor. ηmec_ge and ηele_ge are respectively the mechanical and electrical efficiencies of the generator. the turbine work is: wt = (mc − mo2_ use d)(ht,in − ht,out) (7) mc is the air mass flow rate of the compressor, mo2_used is the mass flow rate of the oxygen used in the reactor. h is the enthalpy. subscrit “in” and “out” refer to the inlet and the outlet of the turbine section. in the pox, ore sulfides are fed to the pox tank where it is mixed with oxygen, chloride and acid. the ore sulfide is composed of pyrite. it is assumed that the pyrite is completely liberated. the pressure oxidation process in the pox tank could be represented by the following reactions [13]: 𝑂2(𝑔) → 𝑂2(𝑎𝑞) (8) 2𝐹𝑒𝑆2(𝑠) + 7𝑂2(𝑎𝑞) + 2𝐻2𝑂(𝑙) → 2𝐹𝑒+2(𝑎𝑞) + 2 2 4𝐻𝑆𝑂−(𝑎𝑞) (9) the total solar heat absorbed (qparticles) by the particles in the solar receiver can be expressed as: 𝑄𝑝𝑎𝑟𝑡i𝑐𝑙𝑒𝑠 = 𝑄𝑠𝑒𝑛𝑠i𝑏𝑙𝑒 + 𝑄che mica l (2) where: qchemical is the enthalpy of reaction of equation (1) and qsensible is the heat required to raise the temperature of the inlet elements to the reduction temperature. the heat absorbed by the steam (qst, red) in the solar receiver can be expressed as: 𝑄𝑠𝑡,𝑟𝑒𝑑 = 𝑚𝑠𝑡(ℎ𝑠𝑡,𝑟𝑒𝑑,𝑜𝑢𝑡 − ℎ𝑠𝑡,𝑟𝑒𝑑,i𝑛) (3) where: is the mass flow, h is the enthalpy. subscripts st and rec refer to steam and solar receiver respectively. the total heat required for the reduction process (qtotal, red) is the sum of the heat absorbed by the particles and the heat absorbed by the steam. 𝑄𝑡𝑜𝑡𝑎𝑙,𝑟𝑒𝑑 = 𝑄𝑝𝑎𝑟𝑡i𝑐𝑙𝑒𝑠 + 𝑄𝑠𝑡,𝑟𝑒𝑑 (4) the intrinsic kinetics of reactions (9) can be described using the shrinking core model for surface reaction control. the respective conversion as functions of oxygen pressure, particle size, and time are given by the following expression [13]. 𝑥 = 1 − ⌊1 − 75. 106 𝑃02 . 𝑡. exp(− 13283)⌋ 3 (10) 𝑑0 𝑇 where: po2 is the oxygen pressure and it is expressed in atmospheres. do in the diameter of the particles of ore sulfide and it is expressed in centimeters. t is the time in minutes. t is the temperature in c°. . iv . results and discussion table 1 illustrated the technical data of the pox. the total pressure of the pox tank is the sum of the partial pressure of vapor and the partial pressure of oxygen. the saturation pressure of vapor at 190°c is 12.55 bars. omar behar et al. ijeca-issn: 2543-3717. june 2021 page 10 therefore, the nominal partial pressure of oxygen is 5.45 bars. t able 1. t echnical dat a of the p ox. data un i t val ue average diamet er of the particles cm 8e-3 nominal working pressure of the p ox at m 18 nominal working t emperature of the pox °c 190 mean t ime of t he particles in t he pox tank minut es 30 figure 3 illustrates the effect of the oxygen pressure on the conversion of pyrite. the conversion increases with the increase in oxygen pressure. the higher the oxygen pressure the higher is the amount of oxygen that is required to operate the pox tank. the conversion of pyrite varies from 0.28 to 0.99 for oxygen pressure in the range of 1 to 9 atm. the nominal conversion is 0.859 (oxygen pressure equals to 5.45 bars). figure 3. variat ion of t he conversion of pyrite as a function of oxygen pressure. the design of the solar particles loop should meet the requirements of the pox tank. in this study, the first objective of coupling the scl with the pox is to treat ore sulfides so electricity is a by-product. therefore, it is important to maximize oxygen production. figure 4 shows the variation of the heat fraction used to generate oxygen as a function of the cold tank temperature. the higher the temperature of the cold tank the higher is the fraction of the heat used to produce oxygen. eighty percent of the useful heat of the solar receiver can be used to generate oxygen while the remaining amount can be converted in electricity. figure 4. variat ion of t he useful heat fraction wit h t he cold tank t emperat ure assuming that the scl-pox is designed to treat 10,000 kg per day of pyrite and it works at steady state. the nominal operating parameters of the scl are illustrated in table 2. the molar flow rate of pyrite in the pox tank is 58 moles per minute and the required molar flowrate of oxygen is 202.6 moles per minute. t able 2. nominal operat ing paramet ers of t he scl. data unit value temp erature of the solar receiver °c 1000 reduction conversion 0.5 oxy gen concentration in the solar receiver 0.09 m ass fraction of cuo/m gal2o4 % 60/40 reduction temp erature °c 1000 reaction temp erature °c 1000 figure 5 illustrates the variation of the receiver useful heat and the gas turbine output as a function of the cold tank temperature. the isentropic efficiency of the compressor and the turbine is 0.89 and 0.91 respectively. the ambient air temperature is 25°c. as can be seen, the increase in the cold tank temperature results in a sharp decrease in the receiver useful heat. this reduce the investment costs since the size of the receiver and the heliostat field strongly depend on the useful heat of the receiver. for the considered case, the useful heat of the solar receiver is 3.7 mwth when the cold tank temperature is set at 100°c. omar behar et al. ijeca-issn: 2543-3717. june 2021 page 11 figure 3. variat ion of useful heat of the receiver and t he power product ion as a funct ion of t he cold t ank t emperat ure the corresponding electricity production is about 0.9 mwe. if the cold tank temperature is set at 400°c, the required useful solar heat is about 3.1 mwth and the nominal output of the gas turbine is 0.56 mwe. overall, the higher the cold tank temperature the smaller is the size of the solar receiver and the gas turbine. when the target is the production of oxide minerals, then high temperature is favorable for the cold tank. this offers several advantages including high oxygen production (high production of the oxide minerals in the pox) and low capex because the solar particles loop, the gas turbine and the heliostat field are small. conclusion the present paper investigates the integration of a solar thermos -chemical process with pressure oxidation process (scl-pox) to treat ore sulfides and produce electricity. a case study to treat 10,000 kg per day of pyrite is considered and the effect of the temperature of the cold storage tank on the design of the complete system is investigated. the analysis showed that the useful heat of the solar receiver is 3.7 mwth when the cold tank temperature is set at 100°c. however, if the cold tank temperature is set at 400°c, the required useful solar heat is about 3.1 mwth. this means that the temperature of the cold tank has a strong influence on the performance of the scl-pox. the proposed scl-pox is modular and can be adjusted to meet given objectives. it can be adjusted to produce electricity and oxide minerals by adjusting the temperature of the cold tank. when the primary objective is to treat ore sulfides, the temperature of the cold storage tank should be as high as that of the reduction reaction. the proposed system has the potential to store energy and oxygen in a sustainable manner, which offers a great opportunity to overcome the issue of current commercial technologies including low operating temperature of molten salt solar tower technology and the inconvenient of current commercial smelters. acknowledgements this work was supported by la agencia nacional de investigación y desarrollo (anid), project number anid/fondap/ 15110019 “solar energy research center” serc-chile. references [1] m .e. schlesinger, k.c. sole, w.g. davenp ort. “extractive metallurgy of cop p er”, elsevier, 2011. [2] t. norgate, n. haque. “ energy and greenhouse gas imp acts of mining and mineral p rocessing op erations”, j. clean. prod. vol. 18, 2011, p p . 266 – 274. [3] s. m oreno-leiva, g. díaz-ferrán, j. haas, t. telsnig, f.a. díaz-alvarado, r. palma-behnke, w. kracht, r. román, d. chudinzow, l. eltrop . “towards solar p ower sup p ly for cop p er p roduction in chile: assessment of global warming p otential using a life-cy cle ap p roach”. j. clean. prod. vol. 164, 2017, p p . 242 – 249. [4] c. m urray , w. platzer, j. petersen. “potential for solar thermal energy in the heap bioleaching of chalcop y rite in chilean cop p er mining”. m iner. eng. vol. 100, 2017, p p . 75 – 82. [5] g. pamp arana,w. kracht, j. haas, j.m . ortiz, w. nowak, r. palma-behnke. “study ing the integration of solar energy into the op eration of a semi-autogenous grinding mill. part i: framework, model develop ment and effect of solar irradiance forecasting”, m iner. eng. vol. 137, 2019, p p . 68 – 77. [6] g. pamp arana,w. kracht, j. haas, j.m . ortiz, w. nowak, r. palma-behnke. “study ing the integration of solar energy into the op eration of a semi-autogenous grinding mill. part ii: effect of ore hardness variability , geometallurgical modeling and demand side management”, m iner. eng. vol. 137, 2019, p p . 53 – 67. [7] d. yadav, r. banerjee. “a review of solar thermochemical p rocesses”. renewable and sustainable energy reviews , vol. 54, 2016, p p . 497 – 532. [8] c. green, j. robertson, j.o. m arsden. “pressure leaching of cop p er concentrates at m orenci, arizona – 10 y ears of exp erience”, m inerals & m etallurgical processing, vol. 35, no. 3, 2018, p p . 109 116. [9] v.g. pap angelakis. “m athematical modelling of an exothermic p ressure leaching p rocess”. phd thesis. m cgill university , quebec, canada, 1990 [10] m . nicolle, m . lamp i, k. valkama, j. karonen. “leaching of cop p er sulp hides”. cop p er cobalt africa, omar behar et al. ijeca-issn: 2543-3717. june 2021 page 12 incorp orating the 8th southern african base m etals conference livingstone, zambia, 6–8 july 2015. [11] d.h. rubisov, v.g. pap angelakis. “m odel-based analy sis of p ressure oxidation autoclave behaviour during p rocess up sets”, hy drometallurgy vol. 39, 1995, p p . 377 389. [12] p. haseli, m . jafarian, g. j. nathan. “high temp erature solar thermochemical p rocess for p roduction of stored energy and oxy gen based on cuo/cu2o redox reactions”, solar energy vol. 153, 2017, 1 – 10. [13] v.g. pap angelakis and g.p. “demop oulos. reactor m odels for a series of continuous stirred tank reactors with a gas-liquid-solid leaching sy stem: part ii1. m odel ap p lication”, m etallurgical transactions, vol. 23b, 1992, p p . 865. ijeca-issn: 2543-3717. june 2021 page 13 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 13-17 dynamic modelling of an earth-to-air heat exchanger for air cooling on the building in hot temperate climate of beni mellal morocco ismail arroub 1 , ahmed bahlaoui 1 , soufiane belhouideg 1 , abdelmadjid kaddour 2 1 team of applied physics and new technologies (epant), polydisciplinary faculty, beni mellal, morocco 2 unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria ismail.arroub@gmail.com abs tract – in this article, we examined the passive cooling techniques built into a building in hot temperate climate. our work aims to reduce the energy de mand for cooling and progre ss the thermal comfort of building by decreasing overheating hours. the dynamic simulations of the energy performance in a building with an earth -air heat exchanger (eahx) are performed in the summer period using trnsys software. the building is situated i n beni mellal city (morocco) where the climate is a hot temperate one. the results of the si mulations show a significant potential for air cooling. indeed, for the hottest day of july (retained for this study), when the outside temperature is 44.8 °c and the cooled temperature (inside) is 29 °c, the difference of 15.8 °c is obtained. also, an evaluation of the relative humidity is provided. finally, we recommend that the moroccan thermal code encourage the use of passive cooling techniques; precisely in temperate climate. keywords: energy efficiency, building, earth-air heat exchanger, passive cooling, trnsys received: 24/04/2021 – accepted: 15/06/2021 i. introduction buildings energy consumption in morocco arranged second, after transport, with 25% of total energy uptake in this country, including 7% for the services sector and 18% for residential [1]. the energy consumption of moroccan buildings is predictable to an incre ment rapidly in the ne xt years fo r t wo reasons; the first is significant increase of household equipment rate in hva c fac ilit ies, hot water and lighting due to the lower prices of these facilit ies and the amelioration of living standards. and the other is substantial development of the buildings sector. over the last decade, there has been an uprising interest in imple ment ing cooling and heating systems for buildings focused on renewable energy sources. because of its high thermal ine rtia, the ground attenuates the temperature variations that occur at the earth surface. furthermore, it causes a difference between the temperature in the soil and that at the surface [2]. methods for exploring geothermal energy are ground source heat pump, geotherma l e lectricity, earth -air heat e xchanger (ea hx) etc. a mong of them, an eahx has the advantages of a simp le system, low operation cost and easy implementation [3]. to supply comfortable circu mstances in the bu ildings of suffic ient ground space, a passive technology of cooling or heating, known as an eahx can be utilized efficiently and effect ively. it is a lso nominated earth tube heat exchanger, ground source heat pump, ground tube heat exchanger or canadian well. the idea o f utilizing ground therma l inert ia for a ir conditioning is not a new method, but a modified concept that goes back to the last decades. the a ir used is oftentimes outside air for ventilation, but also rentable for totally or partially http://www.ijeca.info/ http://www.ijeca.info/ mailto:ismail.arroub@gmail.com ismail arroub et al ijeca-issn: 2543-3717. page 14 managing the construction thermal loads. the climatic conditions affect strongly the system performances. thus, at adequate depth, the ground temperature is lower / (higher) than that of the external air during the summer / (winter). the constant temperature in the ground can be used for cooling and heating applications [4]. in case of the outside air is sucked through the eahx system, in wh ich the pipes inhumed in the soil; the air can be heated during the winter and cooled heated during the summer. consequently, the eahx can minimize the energy destined for cooling or heating or furthermore it enhances the therma l co mfort in the buildings [5-7]. several researchers have studied the impact of pipe dia meter and length and found that, these parameters affect the performance of eahx system [8]. in the 50 40 30 20 10 0 may june july august september eahx system, the difference in air te mperature between outlet and inlet sections of the pipe is imp roved by increasing the length of the pipe [9]. but weakened with the increase in the dia meter of the pipe [10-12]. in a recent works, the authors install two ea hx systems (u shaped pipe) to evaluate the dry and wet eahx system performance. they observed that the knee point position is greater in dry eahx co mpared to the wet eahx system [13,14]. the objective o f the current a rtic le is to study a dynamic therma l simulat ion in a building with integrated the eahx for a hot-dry c limate c ity of ben i me lla l moroccoalong the period between the months of may and september of 2020. ii. methodology ii.1. weather data and location the meteorologica l data used in this study were taken fro m a typica l year weather file fo r the city o f beni mellal, (32.36°n, -6.4°e). several pertinent weather data are presented in figure 1 and figure 2 for the atmospheric temperature and relat ive humidity respectively, for five months from may to septe mber o f 2020. the amb ient temperature o f theses five months varies between 8.1 °c and 44.8 °c which are the lowest and highest temperatures observed during this period at may and july respectively. the large a mplitude of the temperature perturbations is the characteristic of a hot temperate climate. figure 1. ambient temp erature (°c) for the p eriod from 1 st m ay to 30 th sep tember 2020 more the air is warm, more it contains the vapor. conversely, when the a ir cools the vapor condenses and forms liquid water droplets: the saturation threshold increases with temperature. fro m the figure the relative humid ity varies between 30% and 65% for the five months. when the temperature increases, during the hot month, the re lative hu midity decreases and vice versa, at the cold month. an increase in the relative hu mid ity accompanies this decrease in temperature as is observed in figures 1 and 2. in the month of july the temperature reaches up to 45 °c and the climate are hot in this city most often. consequently, fresh air is necessary for the inhabitants of the region to live healthy life with their good mental and physical health. 70 60 50 40 30 20 may june july august september figure 2. relative humidity (%) for the p eriod from 1 st m ay to 30 th sep tember 2020 t e m p e ra tu re ( °c ) r e la ti v e h u m id it y ( % ) ismail arroub et al ijeca-issn: 2543-3717. page 15 ii.2. reference building the building is a concrete hypothetical one which represents a typical villa building in country of morocco. the studied building is located in beni me llal and is north-fac ing built on a floor area of 109 m 2 , with a ceiling height of 2.8 m. it consists of a ground floor composed of seven pieces distributed over the whole area building as shown in figure 3. figure 3. building 2d p lan ii.3. dynamic simulation models in this artic le, dynamic thermal simu lation was carried out through trnsys which designates transient system simu lation software to simulate the building. the systems are simulated using components called “types” that are interconnected through time-dependent inputs and outputs. the building was simulated using type 56 (trnbuild) and connected to the soil using an earth -air heat exchanger (eahx) type 556 [15]. a time step of 1h was used to reduce computation time. the building was sp lit into 7 therma l zones as it is presented in figure 3. each roo m was specified as a therma l zone in order to find detailed informat ion on each one of them. the study is made for roo m 1 and the simu lation starts on 1 st may and ends on 30 th september for the year of 2020. for the computational study, the effect of the inclination pipe and its vertica l parts is not considered into account since the horizontal part of the pipe is long enough. thus, the eahx is formed by only 1 p ipe of pvc (polyviny l ch loride) with 35 m length. the pipe is assumed horizontal, and inhumed at the mean depth of 2.5 m. the thermo-physical characteristics of the pvc p ipe, soil and air at average a mbient temperature (20 °c) are reported in table 1. table 1. phy sical p rop erties thermal conductivity (w/m.k) specific heat (kj/kg.k) density (kg/m 3 ) soil 1.4 1.3 1400 air 0.025 1.01 1.16 pvc 0.17 1.3 1400 iii. discussion of the results in this part, the essential results obtained by means of the dynamic therma l simu lations carried out in this study are plotted and discussed in detail. the results concern the variations of the relative humid ity and temperature with and without the eahx in continuous operation over the period of the year 2020 (1 st may 30 th september of 2020), as mentioned above. it should be noted that the results are presented for the room 1. figures 4 and 5 illustrate the te mperature evolution and relat ive humidity in the roo m 1 respectively, with and without integration of the ea hx. the air temperature in the build ing passed 35 °c in the hottest day localized on july, but with the integration of the eahx, this temperature is varied between 20°c and 29 °c; which corresponds to the range of the therma l comfo rt te mperature. on the other hand, the corresponding relative hu mid ity is a round 40% , although the outside temperature reaches more than 44 °c. the re lative humidity shows a decrease profile when the system (eahx) has a preheating effect (see figure 5). we note that the ea hx could be used also for the air preheating; for e xa mp le, the beginning of the month may (see figure 4), but this aspect is not treated since we are only interested in the building cooling. 40 35 30 25 20 15 10 may june july august september figure 4. ambient temp erature (°c) in the room 1 for the p eriod from 1 st m ay to 30 th sep tember 2020 wit hout eahx wit h eahx t e m p e ra tu re ( °c ) ismail arroub et al ijeca-issn: 2543-3717. wit hout eahx wit h eahx page 16 70 50%. this range of variation in relative humidity does not present any risk of condensation. 60 40 50 35 40 30 20 may june july august 30 25 september figure 5. relative humidity (%) in the room 1 for the p eriod from 1 st m ay to 30 th sep tember 20220 as a comple ment, figure 6 and figure 7 present the time evolution o f the evaluated te mperature and relat ive humid ity respectively, in the studied roo m, during a typical days of summe r (the three hottest days of the year) corresponding to july 19 th , 20 th and 21 th of 2020. it is noted that the ma ximu m / min imu m te mperature, in the studied room, is obtained for the 19 th july and equal to 35.8 °c / 25.2 °c. th is affects the therma l comfo rt zone caused by the lack of refresh. the air temperatures obtained at the outlet of eahx is varying in the range of 23 °c 29 °c; which gives a fa irly significant difference o f 6.8 °c between the te mperature inside the studied room and that of the cooled a ir (see figure 4). note that the amb ient air te mperature in the outside which occurs at 19 th july is 44.8 °c, while the temperature of the air cooled by the eahx is 29 °c; which gives a fa irly significant difference of 15.8 °c (see figure 1 and figure 6). the percentage of this reduction is about 35%. consequently, the above results show that the earth air heat exchanger is a system mo re adapted to air re freshing in the buildings inside beni me lla l city, since it provides a quasi-constant air temperature of appro ximately 26 °c, with re lative humid ity that is almost 40% when the te mperature in outside exceeds 40 °c. the re lative hu midity of the a ir varies with the room temperature. when the temperature increases, during the day, the relative hu midity decreases and vice versa, at the night. the gro wth of the air re lative hu midity accompanies this decrease in te mperature as is observed in figures 6 and 7. thus, the relative humid ity of the amb ient air varies between 25% and 55% while the humidity of the air refreshed oscillates between 27% and 20 19th july 20th july 21th july figure 6. temp erature (°c) inside the room 1 for three hottest day s of the y ear 70 60 50 40 30 20 19th july 20th july 21th july figure 7. relative humidity (%) in the room 1 for three hottest day s of the y ear iv . conclusion in this study, we focused on reduction the demand for cooling energy in a typical building by blocked overheating through the installation of the eahx. the reference building was divided into 7 therma l zones and simulated in trnsys 18. the dynamic simulation of the eahx shows that this system serve air te mperature decrease up to 15.8 °c for the hottest day established in july. the obtained results reveal that the eahx is a therma l system mo re adapted to air re freshing in the build ing, as it provides a quasi constant air temperature of approximately 26 °c, with wit hout eahx wit h eahx wit hout eahx wit h eahx r e la ti v e h u m id it y ( % ) t e m p e ra tu re ( °c ) r e la ti v e h u m id it y ( % ) ismail arroub et al ijeca-issn: 2543-3717. page 17 relative humidity that is about 40% when the outside temperature e xceeds 40 °c. globa lly, these results indicated that the eahx is an efficacious system for a ir refreshment inside the building in hot t e mperate c limate as in beni mella l region, because it provoke an adequate air te mperature for hu man comfort in the hot season (may-september). furthermore, in such climate the eahx can also be used for air heating. references [1] am ee, m oroccan agency for en er gy efficiency "thermal regulation of construction in m orocco", 2013. [2] s. f. ahmed, g. liu, m . m ofijur, a. k. azad, m . a. hazrat and y. m . chu, "phy sical and hy brid modellin g techniques for earth-air heat exchan gers in reducin g buildin g ener gy consump tion: performance, ap p lications, p rogress, and challen ges" so lar ener gy , vol 216, 2021, p p . 274-294. [3] j. w. lund, d. h. freeston and t. l. boy d, "direct app lication of geothermal en er gy ", geothermics, vol 34, 2005, p p . 691-727. [4] d. yang, h. wei, r. sh i, and j. wan g, "a demand oriented ap p roach for integratin g earth-to-air heat exchan gers into buildin gs for achievin g y ear-round indoor thermal co mfort" ener gy conversion and m anagement, vol 182, 2019, p p . 95-107. [5] j. kaur, p. sin gh and h. kaur, "a review on the analy tical analy sis and modellin g of earth air tunnel heat exchan ger system", elk asia pacific journals-sp ecial issue, isbn: 978-81-930411-4-7. [6] a. chel, "perfor mance evalu ation and lif e cy cle cost analy sis of earth to air heat exchan ger integrated with adobe buildin g for new delhi comp osite climate", energy and buildings, vol 41, 2009, p p . 56-66. [7] d. belatrache, s. b entouba and m . bourouis, "numerical analy sis of earth air heat exchan gers at op eratin g conditions in arid climates", international journal of hy drogen energy , vol 42, no 13, 2017, p p . 8898-8904. [8] a. amadeh, m . habibi and a. hakkaki-fard, "numerical simulation of a groundcoup led heat p ump system with vertical p late heat exchan gers: a comp rehensive p arametric study ", geothermics, vol 88, 2020, p . 101913. [9] y. zhao, r. li, c. ji, c. huan, b. zhang and l. liu. "parametric study and design of an earth-air h eat exchan ger usin g model exp eriment for memor ial heating and coolin g", app lied thermal en gineerin g, vol 148, 2019, p p . 838-845. [10] k. k. agrawal, m . bhardwaj, r. m isra, g. d. agrawal and v. bansal, "op timization of op erating p arameters of earth air tunnel heat exchan ger for sp ace cooling: taguchi method ap p roach", geothermal en er gy , vol 6, no 10, 2018, p p . 1-17. [11] b. sin gh, r. kumar and a. k. asati, "influence of p arameters on p erformance of earth air heat exch an ger in hot-dry climate", journal of m echanical science and technology , vol 32, no 11, 2018, p p . 5457-5463. [12] k. k. agrawal, r. m isra, g. das a grawal, m . bhardwaj and d. k. jamuwa, "effect of diff erent design asp ects of p ip e for earth air tunnel heat exchan ger sy stem: a state of art", international journal of green energy , vol 16, no 8, 2019, p p . 598-614. [13] k. k. agrawal, r. m isra, t. yadav, g. d. agrawal and d. k. jamuwa, "exp erimental study to investigate the effect of water imp regnation on thermal p erforman ce of earth air tunnel heat exchan ger for summer coo lin g in hot and arid climate", renewable energy , vol 120, 2018, p p . 255-265. [14] k. k. agrawal, t. yadav, r. m isra and g. das agrawal, "effect of soil moisture contents on thermal p erforman ce of earth-air-p ip e heat exchan ger for winter heatin g in ar id climate: in situ measurement", geothermics, vol 77, 2019, p p . 12-23. [15] tess libr ary mathematical refer ence. in: tesslibs 17: comp onent libraries for the trnsys simu lation environment, vo l. 4. m adison, wisconsin: thermal energy sy stem sp ecialists, llc; 2013. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 01-06 ijeca-issn: 2543-3717. june 2021 page 1 simulation of night cooling through natural cross ventilation using ansys (fluent) yamina harnane 1,2* , sihem bouzid 1,4 , sonia berkane 3 , abdelhafid brima 2,3 abdelmadjid kaddour 5 1 university of oum el bouaghi, algeria 2 laboratory of mechanical engineering (lgm), university of biskra, algeria 3 university of batna 2, algeria 4 laboratory of advanced design ad modeling of mechanical and thermo-fluid’s system (lcmasmtf), university of oum el bouaghi , algeria 5 unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria email* : harnaney@gmail.com abstract – in this study, we carried out a numerical simulation using cfd code “fluent 14.0” to quantify night ventilation due to convective and radiative phenomena with well-defined boundary conditions. the configuration is an open square cavity. top & bottom walls are adiabatic, however, vertical walls represent the left/interior wall and right/external wall provided with a top and a bottom opening, at tcold & thot temperatures, respectively. the computational domain is twodimensional with open boundary conditions of the local bernoulli type. the fluid is incompressible with boussinesq's approximation and flow regime is stationary turbulent with k-ε rng model on a 200 * 240 mesh refined near the walls, (δt = 10 °c). the obtained results allowed flow dynamics & thermal characterization as well as cooling integral quantities calculation. introduction of surface emissivity influences heat transfer via active walls and increases (decreases) the lower (upper) passive wall temperature, while no effect was noted on the dynamics. keywords: thermal comfort, simulation, ventilation, open cavity, natural convection received: 24/04/2021 – accepted: 29/05/2021 i. introduction a comfortable and energy efficient building is well airtight, well thermally insulated and hygienically well ventilated. humans spend between 80% and 90% of their time in a closed indoor space and breathe indoor air that is often more polluted than outdoor air. ventilation allows renewing of the impure air with fresh and healthy air [1], it also allows to cool the buildings internal mass and participate in the body thermal comfort via extracting heat from it by convection and evaporation of sweat. we can find in the literature many more or less recent works in which several experimental models and numerical simulations have been carried-out to evaluate the ventilated cavities performance and their advantages in cooling [2]. in these cavities, air movements are often caused through combined action of pressure gradients induced by wind and/or by thermal draft. generally, the natural ventilation rate is high when there is a large temperature gradient between indoors and outdoors and/or when air is blowing strongly [3-4]. however, one condition remains to be met, the openings must be made so that progression of circulating air is not impeded [5]. many numerical studies were carried-out to ensure comfortable indoor conditions while removing effectively heat and contaminant. for example, studies who carried-out researches either on the outlet influence on ventilation performance, air flow field and air mean age distributions, or on the size and location of the thermal contaminant source and its influence on cooling mailto:harnaney@gmail.com y. harnane et al ijeca-issn: 2543-3717. june 2021 page 2 efficiency [7, 8]. therefore, where the building has several openings placed on opposite facades, the ventilation which takes place is of cross type. on the other hand, night cross ventilation can be used to release the heat stored during the day in the building envelope. this cross-ventilation mechanism is a good means used in buildings passive cooling to maintain thermal comfort conditions. in hot climates, buildings passive cooling is a proven solution, which is organized around four principles: minimizing internal and external heat input, bringing inertia to the building and ensuring good ventilation to promote convective exchanges. to this purpose, we present this study to describe thermoconvective transfers (evaluation of mass flow rates and heat transfers) used in open cavities (rooms with cross ventilation) in hot climates to improve our knowledge on natural ventilation. dynamics and thermics flow control in ventilated cavities are difficult because of the intervention of different dynamic and physical parameters. in this optic, we present modeling via a cfd code of natural ventilation in this kind of configuration. ii. geometric configuration and boundary conditions the geometry is a ventilated square cavity of . top and bottom walls (ceiling and floor) are adiabatic while vertical walls (active) represent the left wall (interior wall) at tcold temperature, provided with a 0.3 m top opening (outlet) and right wall (external wall) at thot temperature, provided with a 0.6 m bottom opening, respectively. the door and the window are closed, only transoms (openings) located at door’s top and window’s bottom are open, figure 1. our study is simplified to a two-dimensional domain and calculation is limited to the internal cavity. radiation in this part is negligible, while open boundary conditions are free and of local-bernoulli type. the air velocity at openings inlet is unknown, inlet & outlet conditions for this kind of model are of "pressure-inlet" ⁄ and "pressure-outlet” type, respectively. inlet turbulence intensity is equal to 5% [1] and with a hydraulic diameter . outside air temperature is and vertical walls temperatures are fixed and constant. tcold = to and thot = to + δt when radiation is considered, both opposite isothermal walls (active walls, ε = 0.15) and other passive walls (adiabatic: floor and ceiling) have an emissivity of [0.1; 0.6; 0.9]. the air inside the cavity is a semi-transparent medium with an absorption coefficient of . the fluid is incompressible with the boussinesq approximation and the regime is turbulent and stationary. figure 1. ventilated cavity geometry with boundary conditions iii. mathematical formulation and governing equations continuity equation: (1) momentum equation: ( ) (2) where ( ( )) energy equation: ( ) ( ) (3) equation of state: (4) the boussinesq hypothesis assumes that fluid density in terms of volume forces varies linearly with temperature, which leads to the following relationship: [ ] (5) k-ε rng model, developed by yakhot v. and orszag s.a [2], is based on a theory known as "renormalization". the constants relating to this model are as follows: ; ; ; ; ; for thermal radiation modeling, we have chosen the discrete ordinates model do [3-4]. radiative transfer equation (etr): ⃗ ⃗ ⃗ ⃗ y. harnane et al ijeca-issn: 2543-3717. june 2021 page 3 ∫ ⃗ ⃗ ( ⃗ ⃗⃗⃗) (6) iii.1. mean age of air (maa) the thermal comfort indices which used in this study can be calculated as following: the mean age of air can be calculated from the following transport equation: ( ( ) ) (7) where s is the source term depending on the air density. the maa is not directly available from fluent so, it is programmed and calculated as user-defined scalars. [9-13]. iii.2. effective draft temperature (edt) effective draft temperature (edt) is one of the first thermal indexes. it combines temperature and air velocity. edt values between -1.7 and 1.1 (-1.7 < edt < 1.1) characterize thermal comfort while edt values outside this range, represent thermal discomfort zone [14-16]. values less than -1.7 represent cool sensation while values above 1.1 represent warm sensation. according to [15], edt is defined as: (8) iv. resolution procedure for this study, we used the k-ε rng model with enhanced-wall function on a mesh (48000 cells) refined near the walls. equations resolution is carried-out via “simple” algorithm by adopting, from one hand, the “2 nd order” scheme for pressure and diffusive terms, and on the other hand, the 2 nd order “upwind” scheme for convective terms. rayleigh number is important (δt=10 °c). the main physical quantities, studied within buildings night cooling framework by natural ventilation, i.e. ventilation flow rate, the heat exchanges and the cooling power, are determined by the following formulas: [5]. cross ventilation flow [m 3 /h] ∫ ⃗⃗ ⃗⃗ (9) average nusselt numbers at the walls air renewal rate [vol/h] (10) outlet fluid average temperature avg [-] ∫ ⃗⃗⃗ ⃗⃗ ∫ ⃗⃗⃗ ⃗⃗ (11) cooling capacity [w] (12) v. results and interpretation two main cells will appear extending horizontally along the floor below the jet and along the ceiling. the third cell is located between the jet and the second cell; figure 2-a. the resulting velocity field, figure 2-b indicates the flow path and the air jet pace from inlet to outlet. the vectors positive direction shows the recirculation areas. on the ceiling, we can clearly see the appearance of dynamic boundary layers and the maximum values of the velocity are located in the jet. (a ) (b) figure 2. (a) current function; (b) velocity field y. harnane et al ijeca-issn: 2543-3717. june 2021 page 4 v.1. mean age of air maa values reflect the supply air flow characteristics and can, therefore, be adopted to evaluate supply air distributions. as seen in figure 3, there is a large region with high maa values, up to 90 s in the upper right part zone of the cavity, indicating that the supply air had a little effect on the air movement in this region. maa value in the region near the floor is significantly lower, between 30 and 50 s. in the jet, maa value is much lower, suggesting that it took less time to deliver the supply air to this region than to other ones. maa lower values don’t allow the air to exchange the heat with the walls. this means that the air is extracted from the cavity with low temperature. hence, the ventilation effectiveness is high. figure 3. maa distribution inside the ventilated cavity v.2. edt index and thermal field the thermal field indicates that a jet of cold air goes from the bottom opening to the top outlet, it divides the flow into two main streams. the first one is a cold stream that crawls along the floor to the opposite wall, it rises to the exit. the second is a jet heated by the right wall and rises along it to reach the exit but remaining stuck to the ceiling. the heart of the cavity is well cooled; figure 4-a. in order to predict thermal comfort zones, the edt index was calculated. from formula (8), we see that the effects of only two parameters of air, namely temperature and velocity, which were used to form this index. the edt shows high sensitivity of temperature and air velocity over the thermal comfort zone. the edt index greater than +1.1 indicates a hot discomfort zone and when edt is less than -1.7, we speak of a cold discomfort zone. in figure 4-b, we notice a zone of cold discomfort created from the entrance which extends along the jet to the exit. the comfort zone does not exceed 0.5 m elevation. also, due to the input jet effect, a hot discomfort zone is created at the right upper part of the cavity. as a result, the thermal comfort zone covers the lower area under the jet. the effect of the inlet jet on the thermal discomfort zone near the entrance is very pronounced and extends from the entrance to the exit of the cavity. this case illustrates that the whole body is inside the comfort zone on the left area of the cavity. (a ) (b ) figure 4. (a) thermal field; (b) edt distribution inside the ventilated cavity table 1 shows the results obtained for the integral quantities (calculated by excel). we find that the air renewal rate is very high which is very interesting for night cooling. y. harnane et al ijeca-issn: 2543-3717. june 2021 page 5 table 1. integral quantities rah θm qv q 1.43*10 10 0.215 329.65 235.37 rah η <nu> f <nu> c 1.43*10 10 52.74 -2.67 114 surface convection-radiation coupling occurs only via adaptability condition at passive walls. temperature distribution along the cavity top wall (adiabatic wall) shows an almost homogeneous average temperature (≈t = 300.92k) with a slight decrease. in figure 4, we note that temperature decreases along with passive walls εp emissivity increasing. consequently, wall radiation would reduce the top wall temperature allowing heat exchanges with the other walls. for the cavity lower wall, the phenomenon is reversed. this phenomenon has already been described in scientific study [17]. (a ) (b) figure 4. evolution of passive walls temperature as a function of emissivity, (a) top wall, (b) bottom wall. total nusselt number is given via the formula: increasing εp emissivity increases all the convective exchanges at the active walls, as shown in figure 5. surface radiation contribution at the active walls is important, it is about 84%, compared to the hot right wall which is about 24%, “table 2”. this can be explained through the air jet effect impacting the cold wall. table 2. total nusselt numbers at the walls (emissivity increasing effect) <nu> cold <nu> hot <nurad> hot ε=0 2.677 113.99 0 ε=0.1 15.124 151.416 37.43 ε=0.6 17.662 151.136 37.15 ε=0.9 18.263 151.09 37.1 <nurad> cold (nurad/nug) cold (nurad/nug) hot ε=0 0 -------- ε=0.1 12.48 82% 23% ε=0.6 14.98 84.84% 24.6% ε=0.9 15.58 85.34% 24.5% (a ) (b) figure 5: evolution of active walls nusselt number as a function of emissivity, (a) cold wall, (b) hot wall. y. harnane et al ijeca-issn: 2543-3717. june 2021 page 6 vi. conclusion turbulent flow in the ventilated cavity was well simulated through cfd calculation code "fluent". our goal is to study flow’s dynamics and thermics for night cooling of a room similar to a ventilated cavity. we evaluated energy performances and integral quantities (η, θm, qv, q) for this kind of configuration in presence of radiation and without radiation. the main conclusions are as follows: the configuration with openings set on opposite walls promotes night cooling with a high air exchange rate and the surface radiation intervening through the walls has an effect only on walls temperatures and nusselts. its effect on the flow’s thermics and dynamics is negligible. nomenclature dh hydraulic diameter, m h height, m l width, m l wall thickness, m p pressure, pa t temperature, k tx local air temperature, °c tm mean temperature, °c vx local air velocity, m.s -1 θ dimensionless temperature ⁄ indices conv convective g global m mean in inlet out outlet rad radiative x local references [1] fluent user’s guide, fluent inc., release 14.0, november 2011 [2] v. yakhot, s. a. orszag, “renormalization group analysis of turbulence i, basic theory, journal of scientific computing, vol. 1, no 1, 1986, pp. 3-51. [3] a. ibrahim, d. saury, d. lemonnier, “coupling of turbulent natural convection with radiation in an air-filled differentially-heated cavity at ra = 1.5*10 9 ”, computers & fluids, vol. 88, 2013, pp.115–125. [4] w. fiveland, “discrete-ordinates solutions of the radiative transport equation for rectangular enclosures”, journal of heat transfer, vol. 106, 1984, pp. 699–706. [5] b. brangeon,, “contribution à l’étude numérique de la ventilation naturelle dans des cavités ouvertes par la simulation des grandes échelles. application au rafraîchissement passif des bâtiments“. thèse de doctorat université de la réunion, 2012. [6] m. ning, s. mengyin, p. dongmei, d. shiming, computational fluid dynamics (cfd) modeling of air flow field, mean age of air and co2 distributions inside a bedroom with different heights of conditioned air supply outlet. applied energy, vol. 164, 2016 pp. 906-916. [7] z. younsi, l. koufi, h. naji, numerical study of the effects of ventilated cavities outlet location on thermal comfort and air quality. international journal of numerical methods for heat & fluid flow, vol. 29. no 11, 2019 pp. 4462-4483. [8] n. gupta, a. k. nayak, s. malik, conjugate heat and species transport in an air-filled ventilated enclosure with a thermo-contaminated block. ijhmt, vol. 117. 2018, pp. 388-411 [9] f. r. menter, two-equation eddy-viscosity turbulence models for engineering applications. aiaa j, vol. 32. no 8, 1994 pp. 1598–1605. [10] c. hu. t. kurabuch, m. ohba. numerical study of crossventilation using two equation rans turbulent models. int j ventilation, vol.4. no 2, 2005, pp.123–132. [11] a. stamou, i. katsiris. verification of a cfd model for indoor airflow and heat transfer. build environment. vol. 41, 2006, pp. 1171–1181. [12] g. d. raithby, e. h. chui. a finite-volume method for predicting a radiant heat transfer in enclosures with participating media. j heat transfer. vol. 112. no 2, 1990, pp. 415-423. [13] v. chanteloup, p. s. mirade. "computational fluid dynamics (cfd) modelling of local mean age of air distribution in forced-ventilation food plants". j food engineering. vol. 90, no 1,2009, pp. 90-103. [14] j. rydberg j and p. norback, “air distribution and draft”, ashrae transactions, 1949, pp. 55-225. [15] a. koestel and g. l. tuve. “performance and evaluation of room air distribution systems”, ashrae transactions, 1955, pp. 61-533 [16] a. f. alfahaid, effects of ventilation on human thermal comfort in rooms, ph. d thesis, old dominion university, norfolk, virginia 2000. [17] h. wang, s. xin, p le quéré, “etude numérique du couplage de la convection naturelle avec le rayonnement de surfaces en cavité carrée remplie d’air “. c.r. académie des sciences. vol. 334, 2006, pp 48-57. brief on solar concentrators: differences and applications international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 01-06 ijeca-issn: 2543-3717. december 2020 page 1 a small parabolic trough collector as a solar water heater: an experimental study in ouargla region, algeria djamel benmenine 1 , mokhtar ghodbane 2* , mohammed elbar soudani 1 , haffar abdelouahed 1 , amghar massiv 1 , nabil elsharif 3 1 laboratory for the development of new and renewable energies in arid zones (lenreza), university of ouargla, algeria 2 mechanical engineering department, faculty of technology, university of blida 1, algeria 3 mechanical engineering department, university of benghazi, libya * email: ghodbannemokhtar39@yahoo.com abstract – this study aims to conduct an experimental thermal examination of a parabolic trough collector in ouargla region at algeria, which will be used as a solar water heater. the solar collector was manufactured and then experimentally tested, as its theoretical optical performance was estimated at 75.06%, while the values of its true thermal performance are 10.61, 10.68 and 8.85 % for 13 may, 14 may and 15 may. although its thermal performance is somewhat low, the studied ptc is effective in heating the water, whereas, using a volumetric flow of 0.011 l/s, about 317 liters of water can be heated daily at 42°c, knowing that the daily average consumption of hot water in a typical house is 250 liters because the ouargla region is strategically located that receives huge amounts of solar irradiance. keywords: thermal solar energy, ptc solar collector, solar water heater, solar energy. received: 10/10/2020 – accepted: 20/11/2020 i. introduction currently, the world is experiencing an important shift in energy production from fossil fuels to the exploitation of renewable energies, and precisely the solar energy that is expanding its use through the use of various solar collectors (photoelectric [1] and thermal collectors “flat [2], linear [3-6] and point collectors [7, 8]”), whereas, the efficiency of these solar collectors can be improved by dispersing nanoparticles in the working fluid [9-11], this will allow to improve its thermophysical properties [12-14]. moreover, solar collectors have several important uses, including electricity production [15], water desalination [16-18], drying [19], cooking [20], air conditioning [21-24], heating [25-27], and industrial processes [7, 28]. therefore, the use of solar collectors of all kinds can be an ideal solution to provide the energy needs of regions with abundant solar energy [29, 30].one of the most important uses of solar energy now is the heating of water, as solar heaters are a way to exploit the thermal energy generated from the sun's rays in heating water for home, industrial and commercial purposes, and these systems achieve a higher economic feasibility than solar photovoltaic energy, where the household electricity bill can be saved especially if the solar heater is connected to a hot water tank. since the solar heater heats the water and stores it during the day for use throughout the day (24 hours), unlike the traditional (electric or gas) heater, which can heat at any time of day and night, the size of the solar heater tank is much larger than the traditional water heater tank [31 32]. through this paper, an experimental thermal examination of a solar water heater by adopting a parabolic trough collector (ptc) will be carried out in ouargla region, algeria, in order to provide hot water that can be used in many household uses, where in this study, the effect of the mass flow of water inside the receiver tube on the solar heater performance will be discussed. mailto:ghodbannemokhtar39@yahoo.com m. ghodbane et al. ijeca-issn: 2543-3717. december 2020 page 2 ii. materials and methods the region of ouargla (algeria) with latitude 31 ° 58 'n, longitude 5 ° 20' e, altitude 150 m is known for its agricultural and industrial activity. the need for domestic hot water is generally provided by conventional energy. in our study, we propose a solar, environmental and economical method to obtain hot water for domestic use. ii.1. ptc collector design water ptc was manufactured by the research group on energy conversion of the lenreza laboratory at ouargla university (algeria). figure 1. the experimental prototype the engineering and optical properties of the experimental device are shown in tables 1 and 2, respectively. table 1 . ptc engineering properties dimension value absorber tube diameter (inner) 0.0142 m absorber tube diameter (outer) 0.016 m focal length 0.2 m glass diameter (inside) 0.0175 m glass diameter (outer) 0.02 m mirror length 2 m mirror opening width 1.6 m reflector opening area 2.88 m² the ptc was placed on two identical steel supports 1.25 m long oriented north-south so that the ptc can follow the movement of the sun from east to west. table 2 . ptc optical properties parameter value absorptivity of absorber tube 0.94 emissivity of absorber tube 0.14 emissivity of glass tube 0.935 reflectivity of mirror 0.935 transmittivity of glass tube 0.92 ii.2. measuring instruments for the determination of the instantaneous thermal behavior of the ptc, there are parameters must be measured. the various parameters measured and the measuring instruments used are: temperatures: three calibrated k-type thermocouples were installed for temperature measurement on different parts of the ptc system, where the thermocouple locations are shown in figure 2. solar irradiance: as shown in figure 2, a solarimeter with an accuracy of (±5%) was used to measure solar irradiation during the experiments. figure 2. k-type thermocouples and solarimeter iii. results and discussion iii.1. experimental set up as shown in figure 3, the solar water heater is composed of a cold-water source, pump, small ptc solar collector and heated water tank, where the system is equipped with the following measuring devices: a solarimeter and three k-type thermocouples. regarding thermocouples, they are placed as follow:  tin: at the entrance to the ptc absorber tube to measure the cold-water temperature coming from the cold source;  tout: at the outlet of the ptc absorber tube to measure the hot water temperature coming out of the ptc collector;  tabs: to measure the absorber tube temperature. figure 3. the experimental installation m. ghodbane et al. ijeca-issn: 2543-3717. december 2020 page 3 several experiments were carried out in the open air behind the physics laboratories at ouargla university for three days from 06/05/2019 until 09/05/2019. the ptc solar heater has been tested on the basis of three scenarios, and they are: first scenario the main axis of the ptc was directed from north to south in order to follow the solar movement from east to west with a manual tracking system, where the temperature of the water is measured when entering and leaving the ptc solar collector, as the water volumetric flow inside the receiver tube is constant ̇ and the effect of weather data for may 13, 2019 on the thermal behavior of the system. second scenario in this scenario, which was completed on may 14, 2019, the ptc was set to the south at an angle of 30 degrees to the horizon, then the solar irradiance and temperatures were measured as was done in the first scenario, as the volumetric flow did not change ̇ ̇ . third scenario the third scenario was completed on may 15, 2019. the settings for this scenario are the same as those for the second scenario, but the volumetric flow value is less, i.e., the ptc was set to the south at an angle of 30 degrees to the horizon, then the solar irradiance and temperatures were measured as was done in the first scenario, as the volumetric flow did not change ̇ . iii.2. results analysis the daily variation in solar irradiance measured using the solarimeter on the ptc plane during the test days is given in figure 5, where it can be deduced from the change of the curves of figure 4 that the average solar irradiance for days 13 may, 14 may and 15 may is as follows 680, 540 and 494 w/m², respectively. regarding the change of water inlet temperature “tin, (°c)”, it is shown in figure 5, as the field of its change is between 28.2°c<tin<29.5°c. regarding the change of water outlet temperature “tout, (°c)”, it is shown in figure 6, where the average water outlet temperature for days 13 may, 14 may and 15 may is as follows 43.38, 40.03 and 41.56 °c respectively. . figure 4. measured solar irradiance values figure 5. measured water inlet temperature values figure 6. measured water outlet temperature values 10 11 12 13 14 15 16 17 250 300 350 400 450 500 550 600 650 700 s o la r ir ra d ia n c e ( w /m ²) time (hour) may 13, 2019 may 14, 2019 may 15, 2019 10 11 12 13 14 15 16 17 28.00 28.25 28.50 28.75 29.00 29.25 29.50 29.75 in le t te m p e ra tu re ( °c ) time (hour) may 13, 2019 may 14, 2019 may 15, 2019 10 11 12 13 14 15 16 17 32 34 36 38 40 42 44 46 48 50 52 o u tl e t te m p e ra tu re ( °c ) time (hour) may 13, 2019 may 14, 2019 may 15, 2019 m. ghodbane et al. ijeca-issn: 2543-3717. december 2020 page 4 concerning the change in ptc thermal efficiencies, it is illustrated in figure 7, as its average values for days 13 may, 14 may and 15 may is as follows 10.61, 10.68 and 8.85 % respectively. figure 7. thermal performance evaluation of the ptc solar heater despite good values for solar irradiance recorded on experimental days, it is noticeable that the ptc thermal performance is somewhat low due to the lack of good selection of the ptc focal length (f=0.2m), knowing that the theoretical optical performance of the studied ptc according to its optical properties is 75.06%. according to the geometrical dimensions of the ptc used, the focal distance should be equal to 0.7411m. therefore, the focal distance of the studied ptc must be adjusted by changing it from 0.2m to 0.7411m, after which the solar water heater will significantly improve in all energetic aspects. iv. conclusion this study made it possible to determine the water ptc performances, where the operating principle, as well as the parameters influencing the ptc performance have been identified and defined. through experimental work conducted on the device, it was concluded:  the theorical optical performance of the studied ptc is 75.06 %;  the amount of instantaneous solar irradiance has a direct effect on the thermal performance of the system, when the amount of radiation increases, the thermal performance values of the system increase directly with it (direct relationship);  the inlet-outlet temperature gradient (∆tout-in) becomes more and more important throughout the studied day until reaching 14.373, 11.29 and 12.86 °c for 13 may, 14 may and 15 may, respectively;  the mean values of real thermal performance of the studied ptc are 10.61, 10.68 and 8.85 % for 13 may, 14 may and 15 may, respectively. these values of ptc thermal performance are rather low due to the failure of the absorber tube at the appropriate focal distance (f), which is estimated at 0.7411 according to the dimensions of the studied ptc;  with a volumetric flow of ̇ , about 317 liters of water can be heated daily at 42°c, knowing that the daily average consumption of hot water in a typical house is 250 liters;  with a volumetric flow of ̇ , about 317 liters of water can be heated daily at 42°c, knowing that the daily average consumption of hot water in a typical house is 250 liters. moreover, it should be noted that the clear sky tests lasted only three days, which remains insufficient for establishing the characteristics of the ptc studied. indeed, it would be interesting to conduct performance tests including changes in focal distance, climatic disturbances (ambient temperature, wind speed, climate change of the season) and changes in operating conditions such as withdrawal of water from tanks, etc. references [1] a. peinado-gonzalo, a. pliego-marugán, f. p. garcíamárquez, "survey of maintenance management for photovoltaic power systems", renewable and sustainable energy reviews, vol. 134, 2020, pp. 110347. [2] e. vengadesan, r. senthil, "a review on recent developments in thermal performance enhancement methods of flat plate solar air collector", renewable and sustainable energy reviews, vol. 134, 2020, pp. 110315. [3] e. bellos, "progress in the design and the applications of linear fresnel reflectors – a critical review", thermal science and engineering progress, vol. 10, 2019, pp. 112-137. [4] m. ghodbane, e. bellos, z. said, b. boumeddane, a. k. hussein, l. kolsi, "evaluating energy efficiency and economic effect of heat transfer in copper tube for small solar linear fresnel reflector", journal of thermal analysis and calorimetry, 2020. [5] mokhtar ghodbane, evangelos bellos, zafar said, boussad boumeddane, abderrahmane khechekhouche, mohsen sheikholeslami, ziad m. ali., "energy, financial and environmental investigation of a direct steam production power plant driven by linear fresnel 10 11 12 13 14 15 16 17 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 t h e rm a l e ff ic ie n c y ( % ) time (hour) may 13, 2019 may 14, 2019 may 15, 2019 m. ghodbane et al. ijeca-issn: 2543-3717. december 2020 page 5 solar reflectors", journal of solar energy engineering, vol. 143, no2, 2020, pp. 021008. [6] m. ghodbane, b. boumeddane, z. said, e. bellos, "a numerical simulation of a linear fresnel solar reflector directed to produce steam for the power plant", journal of cleaner production, vol. 231, 2019, pp. 494-508. [7] e. bellos, c. tzivanidis, "solar concentrating systems and applications in greece – a critical review", journal of cleaner production, vol. 272, 2020, 122855. [8] m. ghodbane, d. benmenine, a. khechekhouche, b. boumeddane, "brief on solar concentrators: differences and applications", instrumentation mesure metrologie, vol. 19, no 5, 2020, pp. 371-378. [9] e. bellos, c. tzivanidis, "multi-criteria evaluation of a nanofluid-based linear fresnel solar collector", solar energy, vol. 163, 2018, pp. 200-214. [10] m. ghodbane, z. said, a. a. hachicha, b. boumeddane, "performance assessment of linear fresnel solar reflector using mwcnts/dw nanofluids", renewable energy, vol. 151, 2020, pp. 4356. [11] z. said, m. ghodbane, l. s. sundar, a. k. tiwari, m. sheikholeslami, b. boumeddane, "heat transfer, entropy generation, economic and environmental analyses of linear fresnel reflector using novel rgoco3o4 hybrid nanofluids", renewable energy, vol. 165(part 1), 2021, pp. 420-437. [12] e. bellos, z. said, c. tzivanidisa, "the use of nanofluids in solar concentrating technologies: a comprehensive review", journal of cleaner production, vol. 196, 2018, pp. 84-99. [13] e. bellos, c. tzivanidis, a. papadopoulos, "enhancing the performance of a linear fresnel reflector using nanofluids and internal finned absorber", journal of thermal analysis and calorimetry, vol. 135, no 1, 2019, pp. 237-255. [14] a. k. hussein, m. ghodbane, z. said, r. s. ward, "the effect of the baffle length on the natural convection in an enclosure filled with different nanofluids", journal of thermal analysis and calorimetry, 2020. [15] o. behar, "solar thermal power plants – a review of configurations and performance comparison", renewable and sustainable energy reviews, vol. 92, 2018, pp. 608-627. [16] a. khechekhouche, b. benhaoua, a. m. manokar, r. sathyamurthy, a. e. kabeel, z. driss, "sand dunes effect on the productivity of a single slope solar distiller," heat and mass transfer, vol. 56, 2020, pp. 1117-1126. [17] a. khechekhouche, a. e. kabeel, b. benhaoua, m. e. h. attia, e. m. s. el-said, "traditional solar distiller improvement by a single external refractor under the climatic conditions of the el oued region, algeria", desalination and water treatment, vol. 177, 2020, pp. 23-28. [18] a. khechekhouche, z. driss, b. durakovic, "effect of heat flow via glazing on the productivity of a solar still", international journal of energetica, vol. 4, no 2, 2019, pp. 54-57. [19] patchimaporn udomkun, sebastian romuli, steffen schock, busarakorn mahayothee, murat sartas, tesfamicheal wossen, emmanuel njukwe, bernard vanlauwe, joachim müller., "review of solar dryers for agricultural products in asia and africa: an innovation landscape approach", journal of environmental management, vol. 268, 2020, 110730. [20] mohamad aramesh, mehdi ghalebani, alibakhsh kasaeian, hosein zamani, giulio lorenzini, omid mahian, somchai wongwises, "a review of recent advances in solar cooking technology", renewable energy, vol. 140, 2019, pp. 419-435. [21] e. bellos, i. c. theodosiou, l. vellios, c. tzivanidis, "investigation of a novel solar-driven refrigeration system with ejector", thermal science and engineering progress, vol. 8, 2018, pp. 284-295. [22] e. bellos, c. tzivanidis, "optimum design of a solar ejector refrigeration system for various operating scenarios", energy conversion and management, vol. 154, 2017, pp. 11-24. [23] e. bellos, c. tzivanidis, "parametric analysis and optimization of a cooling system with ejectorabsorption chiller powered by solar parabolic trough collectors", energy conversion and management, vol. 168, 2018, pp. 329-342. [24] m. ghodbane, b. boumeddane, a. khechekhouche, d. benmenine, "study of a solar air conditioning system with ejector", international journal of energetica, vol. 5, no 1, 2020, pp. 14-21. [25] m. ghodbane, b. boumeddane, n. said, "a linear fresnel reflector as a solar system for heating water: theoretical and experimental study", case studies in thermal engineering, vol. 8(c), 2016, pp. 176-186. [26] m. ghodbane, b. boumeddane, n. said, "design and experimental study of a solar system for heating water utilizing a linear fresnel reflector", journal of fundamental and applied sciences, vol. 8 no 3, 2016, pp. 804-825. [27] z. said, m. ghodbane, a. a. hachicha, b. boumeddane, "optical performance assessment of a small experimental prototype of linear fresnel reflector", case studies in thermal engineering, vol. 16, 2019, 100541. [28] a. kasaeian, e. bellos, a. shamaeizadeh, c. tzivanidis, "solar-driven polygeneration systems: recent progress and outlook", applied energy, vol. 264, 2020, 114764. [29] m. ghodbane, b. boumeddane, "estimating solar radiation according to semi empirical approach of perrin de brichambaut: application on several areas with different climate in algeria", international journal of energetica, vol. 1, no 1, 2016, pp. 20-29. [30] m. ghodbane, b. boumeddane, and a. k. hussein, "performance analysis of a solar-driven ejector air conditioning system under el-oued climatic conditions, m. ghodbane et al. ijeca-issn: 2543-3717. december 2020 page 6 algeria", journal of thermal engineering, vol. 7(1), 2021, pp. 172-189. [31] m. ghodbane, "étude et optimisation des performances d'une machine de climatisation a éjecteur reliée à un concentrateur solaire " phd in energy and thermal systems, saad dahleb university of blida 1, algeria: www.univ-blida.dz, thesis available to the library of the faculty and the central library of the university, 2017. [32] m. ghodbane, b. boumeddane, "a parabolic trough solar collector as a solar system for heating water: a study based on numerical simulation", international journal of energetica, vol. 2, no 2, 2017, pp. 29-37. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 01-06 bioclimatic approach of passive cooling techniques for the design of buildings in southern algeria belkhir hebbal 1* , yacine marif 1 , abdelmadjid kaddour 2 , mohamed mustapha belhadj 1 , abdelghani azizi3 1 laboratory of new and renewable energies in arid zones (lenreza), university of ouargla, algeria 2unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria 3 department of renewable energies, university of ouargla, algeria e-mail*: hebbalbelkhir@gmail.com abstract – the bioclimatic approach looks into the opportunities for building conception under the local climatic conditions. the first bioclimatic chart has been developed by olgyay which combines temperature with relative humidity to characterize the comfort zone. it is founded on outside climate conditions to identify attenuation measures such as solar radiation, wind speed, or shading to reach comfortable inside conditions. givoni created also a bioclimatic chart founded on inside conditions using the physical and thermal properties of air. bioclimatic approach strategies contribute to decreasing the building energy loads and increasing thermal comfort for its residents over the year. the principal aim of this research is to evaluate a bioclimatic approach to passive cooling for building design in algeria's south using givoni's bioclimatic chart and olgyay's bioclimatic chart. climate data of various locations (ouargla, ghardaia, and el oued) within this area were collected and analyzed. furthermore, an overview of appropriated conception strategies for the hot season for each zone is developed. the results show that the maximum average temperature from june to august at around 43.1°c. after applying passive cooling strategies, the temperature indoor can be decreased from about 26.1 to 31.4°c, which can be described as being in the comfort zone for the three studied locations. finally, these findings can contribute to understanding the thermal behavior of residential buildings and offer guidelines to develop a convenient concept of what the building composition should look like in arid and hot climates. keywords: thermal comfort, passive cooling, bioclimatic approach, bioclimatic chart, hot climates. received: 24/04/2021 – accepted: 03/06/2021 i. introduction in recent years, electricity consumption in algeria has accelerated with an unexpected increase especially in the commercial, and industrial and residential sectors [1]. it is very important to notice that one of the principal factors for this increase in energy consumption is the use of conventional cooling systems power consumption. providing thermal comfort in architectural and building design is the subject of many types of researches that clarifies its significance especially in hot climates. since ancient times, people have been tried to adapt to their environment by creating new solutions to create suitable climate conditions indoor their dwellings [2]. in hot climates, excessive temperatures are the principal issue that should be taken into consideration in the selection of building passive thermal conception strategies. in these climates, natural ventilation is a significant process to maintain indoor temperature when the outdoor temperature cannot maintain thermal comfort. the standard bioclimatic tools, which utilized in the building design analysis, are olgyay's bioclimatic chart [3], and givoni's psychometric chart [4]. these graphs are founded on dry bulb temperature and relative humidity for a given location according to the ashrae http://www.ijeca.info/ http://www.ijeca.info/ mailto:hebbalbelkhir@gmail.com belkhir hebbal et al ijeca-issn: 2543-3717. december 2021 page 03 comfort zone. numerous studies have been recorded in the world about the providing of thermal comfort in buildings by using bioclimatic charts of the passive cooling design. in oman bioclimatic charts have developed for eight locations founded on typical meteorological year (tmy) data [5]. this chart indicates that the high thermal mass parameter can be efficient in four months (march, april, october, and november). the climatic conditions of the indonesian areas were examined by using the olgyay's bioclimatic chart and the givoni's bioclimatic chart [6]. these charts indicated that this climate needed air movement and shading to reduce solar gain entering the building. in the composite zone of india, bioclimatic charts have developed for 21 locations [7]. results have shown a significant difference in passive conception potential even within the composite area. in algeria, scientific research which attempts to improve the thermal performance of buildings remains rare and fragmented because thermal quality problems are not taken into account in the design of buildings to achieve thermal comfort. in the hot climate of algeria, the thermal behavior of bioclimatic buildings has assessed by applying wind towers [8]. performance observing and in-site measurement of the system offered data that introduced in model validation. the results have been encouraging and still over the minimum demand of comfort zone in a hot season for a climate such as that of ouargla. this study confirmed the advantage of the application of this passive cooling strategy in hot and arid climates. in the hot climate of adrar south algeria, a simulation of a hybrid passive cooling system composing of an earth-to-air heat exchanger (eahe) which assisted by a wind tower has been realized [9]. the results have shown that the system can significantly favor natural ventilation and provide a suitable level of inside temperature lower than 32°c.. other authors [10] have validated this model using both theoretical and experimental data. generally, looking through this study, clear comprehension of passive cooling in the bioclimatic charts is developed to improve both thermal performance and indoor comfort in hot climates in southern algeria. in south algeria, air conditioning is the most used compared to other electrical appliance. in the hottest three months (june, july, and august), energy consumption exceeds that of the rest 9 months of the year together. a good energy-saving opportunity at low or no additional cost could be offered by using passive cooling techniques. the added value of this study is founded on providing a bioclimatic approach to evaluate the building conception potential in south algeria. the recommendations for the bioclimatic design of passive cooling are validated by using the recent fifteen years of climate data (2004-2018) for ouargla, ghardaia, and el oued cities created and made available by the us noaa's integrated surface database. ii. methodology this study tries to develop guidelines of a passive cooling standard for buildings in south algeria that provides thermal comfort. the olgyay bioclimatic chart and givoni bioclimatic were used to examine and evaluate the climatic conditions of the selected areas. generally, the construction passive thermal conception strategies are founded on the local climatic conditions and could be made using bioclimatic charts. ii.1. case study and data collection recent climatic data supported by (atm) files for the three cities studied were used in this study. these climatic data were created and made available by the integrated surface database of us noaa [11]. figure 1 indicates the locations of the three selected provinces, and table 1 presents their geographic location. figure 1. algerian map showing the studied locations table 1. geographic coordinates of the three provinces locations latitude longitude elevation (m) ouargla 31°55’n 05°24’e 141 ghardaia 32°23’n 03°49’e 450 el oued 33°30’n 06°47’e 69 belkhir hebbal et al ijeca-issn: 2543-3717. december 2021 page 03 ii.2. olgyay bioclimatic chart this chart was one of the first chart that combined the relative humidity in abscissa with dry bulb temperatures in ordinate [6, 11]. in this chart, the comfort zone is situated at the center of the graph. oglyay’s chart has a constant comfort zone in the interval from 20 to 30°c. olgyay bioclimatic chart envelops a wide range of temperature, humidity, wind speed, and solar radiation levels. [12]. ii.3. givoni bioclimatic chart this chart is the most popular among the bioclimatic cards. it is based on the linear relationship between the temperature amplitude and vapor pressure of the external air. givoni’s chart identifies the convenient cooling concept founded on the outside climatic condition [13, 14]. several specific zones are found on givoni’s chart such as comfort zone (cz), natural ventilation (nv), high mass (hm), high mass with night ventilation (hmv), and evaporative cooling (ec) [5]. ii.4. adaptive thermal comfort the ashrae adaptive comfort model (by ashrae standard 55-2020) is the most well‐known model that paved the way for significant energy saving allowing a wider range of temperatures in naturally ventilated buildings [15]. the relationship between indoor comfort temperature, tcomf, and outside temperature, tout is given by the equation eq. (1): iii. results and discussions figure 2 shows the monthly minimum and maximum, temperatures in ouragla, ghardaia, and el oued. the thermal amplitude is very important throughout the year; it reaches to 38°c, with the monthly mean minimum and maximum being around 5°c and around 43°c respectively in three locations. relative humidity has been shown in figure 3. it ranges between 14% and 86% in three locations. these values are used in section 4 in order to determine the proper passive cooling strategy to be used as shown on olgyay bioclimatic chart and givoni bioclimatic chart. tcomf  0.31tout 17.8 (1) according to ashrae standard 55-2020, there are two major acceptability limits in this approach: 80% acceptability limits = operative temperature: 22.1 to 29.1 °c 90% acceptability limits = operative temperature: 23.1 to 28.1 °c the ranges of temperature for 80% and 90% of thermal acceptability are set as ±3.5 ºc and ±2.5 ºc respectively. figure 2. minimum and maximum temperatures for the three selected locations belkhir hebbal et al ijeca-issn: 2543-3717. december 2021 page 05 figure 3. minimum and maximum relative humidity for the three provinces the adaptive comfort temperature ranges between the minimum and the maximum for each month are calculated for the three zones studied using of course the adaptive ashrae model and equation (1). the climate data applied in this study are the means of 15 years (2004–2018) for each area. figure 4 indicates that all areas have an upper and lower limit for each month. figure 4. adaptive indoor comfort temperatures for all three provinces iii.1. olgyay bioclimatic chart for the three selected locations figure 5 highlights olgyay bioclimatic charts for ouargla, ghardaia, and el oued. during most of the year, the value of the minimum and the value of the maximum temperature are outside the comfort zone. this indicates the hard climatic conditions such as the high temperature level that due to their geographical position, which passes through the big sahara of algeria. belkhir hebbal et al ijeca-issn: 2543-3717. december 2021 page 05 figure 5. olgyay bioclimatic chart of (a) ouargla, (b) ghardaia, and (c) el oued iii.2. givoni bioclimatic chart for the three selected locations from givoni bioclimatic charts (see figure 6), the collection of the average monthly points suggest an arid and hot climate type. they show december, january, and february were projected on the comfort zone where solar radiation is sufficient for keeping the thermal comfort. on the other hand, from june to august are the hottest months in the year are lying outside the comfort zone. in this case, cooling is necessary for maintaining thermal comfort. similar results are observed for the three select locations ouragla, ghardaia, and el oued. figure 6. givoni bioclimatic chart of (a) ouargla, (b) ghardaia, and (c) el oued iv. conclusion in this paper, two types of bioclimatic charts have been developed: olgyay bioclimatic chart and givoni bioclimatic chart using the ashrae-55 adaptive model. the following findings are extracted based on the results obtained from the bioclimatic analysis. in general and according to the olgyay’s bioclimatic charts, the climate in ouargla, ghardaia, and el oued is particularly arid and warm throughout the year except for december and january. moreover, making a shading device is also recommended to reduce solar radiation entering the buildings. the givoni bioclimatic charts indicate almost the same findings as the olgyay charts. a requirement for natural ventilation is also suggested because of the intense heat, and making a shading device is required due belkhir hebbal et al ijeca-issn: 2543-3717. december 2021 page 06 to the high solar radiation intensity especially in the summer season where the day length becomes longer. the findings show that the maximum average temperature from june to august at around 43.1°c. after applying passive cooling strategies, the temperature inside can be decreased from about 26.1 to 31.4°c, representing the comfort zone for the three studied locations. finally, it will be better to take into consideration the comfort zones in the architectural conception of buildings and designing of cooling and heating installation systems in arid and hot climates of algeria in order to minimize additional charges of energy supply. references [1] energy and mine ministry, aprue national agency for promotion and rationalization of the use of energy, edition 2009. [2] b. hebbal, y. marif, m.m. belhadj, “bioclimatic architecture in the ancient villages of southern algeria”, icree2019, springer proceedings in energy. springer nature singapore pte ltd. 2020. [3] v. olgyay, “design with climate, bioclimatic approach, and architectural regionalism”, new jersey: princeton university press, 1963. [4] b. givoni, “comfort, climate analysis and building design guidelines”, energy and buildings vol. 18, 1992, pp. 11-23. [5] n. al-azri, yh. zurigat, n. al-rawahi, “selection and assessment of passive cooling techniques for residential buildings in oman using a bioclimatic approach”, journal of engineering research [tjer], vol. 10, 2013, pp. 52-68. [6] s. santy, h. matsumoto, k. tsuzuki, l. susanti, “bioclimatic analysis in pre-design stage of passive house in indonesia”, buildings vol. 7, 2017, pp. 24. [7] n.k. khambadkone, r. jain, “a bioclimatic approach to develop spatial zoning maps for comfort, passive heating and cooling strategies within a composite zone of india”, building and environment, vol. 128, 2018, pp. 190– 215. [8] bouchahm, f. bourbia, a. belhamri, “performance analysis and improvement of the use of wind tower in hot dry climate”, renewable energy, vol. 36, 2011, pp. 898-906. [9] m. benhammou, b. draoui, m. zerrouki, y. marif, “performance analysis of an earth-to-air heat exchanger assisted by a wind tower for passive cooling of buildings in arid and hot climate”, energy conversion and management, vol. 91, 2015, pp. 1–11. [10] m. benhammou, b. draoui, m. hamouda, “improvement of the summer cooling induced by an earth-to-air heat exchanger integrated in a residential building under hot and arid climate”, applied energy, vol. 208, 2017, pp. 428–445. [11] repository of free climate data for building performance simulation, 2020. http://climate.onebuilding.org [12] h.a. mahmoud, “an analysis of bioclimatic zones and implications for design of outdoor built environments in egypt”, building and environment vol. 46, 2011, pp. 605-620. [13] s. bodach, “developing bioclimatic zones and passive solar design strategies for nepal”, the 30th plea conference sustainable habitat for developing societies, 2014. [14] n.k. khambadkone, r. jain. r, “a bioclimatic analysis tool for investigation of the potential of passive cooling and heating strategies in a composite indian climate”, building and environment, vol. 123, 2017, pp. 469493 [15] gh.r. roshan, m. farrokhzad, s. attia, “defining thermal comfort boundaries for heating and cooling demand estimation in iran's urban settlements”, building and environment, vol. 121, 2017, pp. 168-189. [16] f. tartarini, s. schiavon, t. cheung, t. hoyt, “cbe thermal comfort tool: online tool for thermal comfort calculations and visualizations”, software x, vol. 12, 2020, pp. 100563. http://climate.onebuilding.org/ i. introduction ii. methodology iii. results and discussions iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 35-43 ijeca-issn: 2543-3717. december 2021 page 35 4e (energy-exergy-economic-environmental) performances assessment of different configurations of power cycles islem meriche1, adem chemoul1, taqiy eddine boukelia1,2* 1mechanical engineering department, jijel university, jijel, algeria 2 mechanical and advanced materials laboratory, polytechnic school of constantine, constantine, algeria email *: taqy25000@hotmail.com abstract – steam power plants are alimented by different sources of energy including fossil fuels or renewable ones such as solar thermal, biomass or geothermal. thus, thermodynamic, economic and environmental analyses of different steam power cycles are highly required for identification and choice of the most effective and viable layout to be adopted in the installation. consequently, the main aim of the present paper is to compare five different configurations of power cycles in terms of energy and exergy efficiencies, fuel and cooling water consumptions, co2 emissions rate, as well as investment and operating costs, and net present value (npv). the obtained results present relevant differences; the energy and exergy efficiencies of the fifth configuration similar to the one of achouat power station are the highest with 41.9% and 39.5% respectively. on the other hand, this configuration shows better environmental performances represented by co2 emission (46.12 kg/s), and water consumption for cooling (7.42 m3/s). economically, there is a clear convergence in the npv values for configurations with reheating and regeneration processes. moreover, the fourth configuration is the best in terms of net present value (npv) of 103.1(m€). keywords: 4e, configuration, power cycle, performance, steam power plant. received: 06/08/2021 – accepted: 30/10/2021 i. introduction the world is witnessing major changes in the energy sector that control the joints of human daily life, and there is no doubt that energy based on fossil fuels such as coal, oil, and gas is the most important source of energy for human development. however, this type of energy is currently facing two main challenges; global climate change and harmful environmental effects. to meet these challenges, any energy conversion system must comply with the environmental laws and respect the emissions limits. in algeria, the global demand for electricity has increased, especially during summer season and hot days, when consumption is at its peak. this increase is a direct result of a change in habits consumption and an increase in livelihoods, as well as the impetus given to economic and industrial sectors to meet algeria's electricity needs. in 2017, the power generation based on steam power plants was about 10074 gwh, which represents a share of 12% of the total installed capacity [1]. steam power plants have attended remarkable developments in order to improve their energy and exergy performances, and to reduce their economic risks and co2 emissions. steam power plants are alimented by different sources of energy, either fossil or renewable ones. this last type can be solar thermal, biomass or geothermal. thus, thermodynamic, economic and environmental analyses of different steam power cycles are highly required for identification and choice of the most effective and viable configuration to be adopted in the installation. in this direction, a large number of studies have been presented to examine this concern. a group of researchers analyzed the thermodynamic performances of a steam power plant with reheating-regenerative technology [2]. the simulations were performed with a cyclepad v2.0 software package. they examined the effects of regeneration on the performance indicators of the steam plant by increasing the number of feed water heater from 1 to 10. the simulation results show that the thermal efficiency of the plant has increased by 8.3%. https://www.ijeca.info/ i. meriche et al ijeca-issn: 2543-3717. december 2021 page 36 furthermore, another group of researchers analyzed the exergy and exergo-environmental performances of a 660 mw coal-fired supercritical steam power plant located in western india [3]. the study is based on the speco (specific exergy costing) approach, which is followed in this case by exergo-economic analysis. the obtained results prove the possibility of attending a value of 35.54 % for the exergy efficiency; the cooling water and exhaust gases represent the environmental impact rate of 507.173 mpts s-1and 676.29 mpts s-1 respectively. on the other study [4], the same research team, used matlab programming software and performed an economic and exergo-economic analysis of the 660 mw coal-fired supercritical units. the economic analysis is carried out using the net present value method. the results of the economic analysis established that the payback period of the plant is estimated at 4.5 years for 9% of the interest rate. in another numerical study performed a complete thermodynamic analysis of an 82 mw steam power plant. they developed an ees code to assess the energy loss, energy efficiency, exergy efficiency and exergy destruction for each part of the installation, by considering the range of actual values of the operating parameters. it has been observed that the energy and exergy efficiencies of this plant are 35.95% and 33.15% respectively [5]. moreover, the maximum energy loss occurs in the boiler, (approximately 36.39%). using the thermodynamic properties of steam, an investigation to show via a code developed under ees environment, the energy and exergy efficiencies of an existing commercial thermal power plant, and values of 38% and 53% respectively have been recorded. in addition, the monetary expenditure, the costs of exergy losses and the exergo-economic factors of the power plant units were calculated, and a maximum cost of exergy losses in the boiler of 758.32 $/h has been obtained [6]. on the other hand, a study concluded conducted technical and economic evaluations of the use or non-use of lowand high-pressure feed water heaters in different situations [7]. in a research lab, they used the pinch analysis method to integrate energy into the steam cycle of a 250 mw steam power plant located in rajasthan, india [8]. the recovery of the steam cycle is carried out according to six schemes. by using this approach, the generated power is increased by 0.55%, and the demand for demineralised water is reduced by 57.6%. furthermore, the exergy analysis shows that the boiler has maximum exergy destruction with a share of 89% of the whole steam power plant. an investigation used trnsys programming software to design a numerical model of a thermal power plant based on parabolic trough solar technology. the energy performance of the system was compared for two cases, the rankine cycle with and without a solar field [9]. a fairly recent study performed a techno-economic analysis of deploying an aerocondenser in a concentrating solar power (csp) plant with two configurations; the first is based on thermic oil as the working fluid, and the second is utilizing molten salt[10]. however, according to our knowledge, a 4e comparative study (energy-exergy-economicenvironmental) between different layouts of steam rankine power cycle is not found in the literature. consequently, the main aim of the present work is to compare five different configurations of this type of power cycles in terms of energy and exergy efficiencies, consumed fuel, co2 emissions, cooling water consumption, as well as investment and operating costs, net present value (npv) and depreciated payback period (dpp). ii. data and methodology ii.1. studied configurations 4e (energyexergy-economic-environmental) is a comparative study of five different configurations of a power cycle was carried out in order to choose the best configuration to adapt in csp, geothermal and biomass thermal power plants. these layouts are listed below: • basic rankine cycle (1); • regenerative rankine cycle (2); • rankine cycle with reheating (3); • rankine cycle with reheating and regeneration on both turbines (lpt and hpt) (4); • similar rankine cycle of a real steam power plant (achouatjijel, algeria) (5). the five studied configurations have the same net capacity of 210 mw to have a common ground for comparison. however, due to the addition of different processes in each configuration, differences in thermodynamic performances, economic and environmental parameters arise. therefore, the five configurations are compared in terms of energy and exergy efficiencies, consumed fuel, co2 emissions, cooling water consumption, as well as investment & operating costs, net present value (npv) and depreciated payback period (dpp). the table 1 summarises the assumptions and the nominal values of the design for the main parameters within the five studied configurations [11]. i. meriche et al ijeca-issn: 2543-3717. december 2021 page 37 table 1. nominal values for the main parameters in the studied configurations [10,11] parameters value units ambient conditions: temperature/ pressure 25/ 1.01325 °c/ bar hpt input conditions: temperature/ pressure 540/ 127.5 °c/ bar lpt input conditions: temperature/ pressure 540/ 23.48 °c/ bar isentropic efficiency of turbines 88 % mechanical efficiency of turbines 97.5 % isentropic efficiency of pumps 87 % generator efficiency 98 % fuel lower calorific value 28938 kj/kg condensing pressure 0.0527 bar outlet temperature of the reheater 540 °c power generated by the plant 210 mw number of service hours per year 7000 hr/yr ii.2. mathematical modeling the cycle-tempo 5.1 software has been used to simulate the thermodynamic performances (energetic and exergetic). on the other hand, using matlab software [12,13], mathematical codes have been developed to simulate the economic and environmental performances of these investigated configurations. ii.2.1. thermodynamics modelling the energy analysis of every sub-system of the installation is based on the conservation of mass and energy (the first law of thermodynamics): outin   mm  (1) (1) hmwhmq outoutinin    (2) on the other hand, the general formula to present the exergy analysis can be formulated as: outoutinin exmxeexmxe wq    (3) (3) the exergy of a substance can be partitioned into four segments. the two most significant are physical exergy and chemical exergy [14]. in this study, the other two parts; kinetic exergy and potential exergy are negligible. chmph xexexe   (4)    000 ssthhmxe ph   (5) (4)          00 ln i i n i ichm y y trmxe  (6) table 2 presents the main equations for each component of the studied configurations. table 2. main equations used to perform the thermodynamic analysis for each component of the configurations component equation boiler exergy produced tm water tm steamboilerprd xexexe  , exergy source chm fuelboilersrc xexe  , condenser exergy produced inpoutpconprd xexexe ,,,   exergy source outsinsconsrc xexexe ,,,   turbines power )( outinsteamtub hhmw    exergy produced tubtubprd wxe  , exergy source tm out tm intubsrc xexexe  , pump power )( inoutwaterpum hhmw    exergy produced pumpumprd wxe  , exergy source inoutpumsrc xexexe  , feed water heater exergy produced inpoutpfwhprd xexexe ,,,   exergy source outsinsfwhsrc xexexe ,,,   deaerator exergy produced inpoutpdesprd xeexmxe ,, )(   exergy source )(,, soutinsdessrc mexxexe    exergy efficiency src prd xe xe ex    electric power gentubele ww   net power pumelenet www   ii.2.2. economic modelling in the present study, the economic analysis of the five configurations was carried out on the basis of the initial investment (є), the operating cost (є/year), the annual income obtained (є/year), the net present value (npv) (є) and depreciated payback period (dpp) (years) [15]. the initial investment can be expressed in terms of the cost of every individual component as follows: )( inddtot cci  (7) the total direct plant costs: eqpd cc )1(  (8) where: µ, is the factor of direct installation, µ= 0.3. σ, is the factor of auxiliary services, σ= 0.15. δ, is the factor of instrumentation and controls, δ=0.1. ε, is the preparation site factor, ε=0.1. the total indirect plant costs: eqpind cc )(  (9) where: i. meriche et al ijeca-issn: 2543-3717. december 2021 page 38 ∂, is the engineering factor, ∂ = 0.12. ℓ, is the start-up factor, ℓ= 0.1. the initial cost of equipment: i b ieqp wac ])([  (10) the specific coefficients a and b are given in table 3. table 3. constants to determine the cost of each component of the plant presented [15]. components a b boiler 1340000 0.694 turbines 633000 0.398 condenser 398000 0.333 condensate extraction pumps 9000 0.4425 feed pump 35000 0.6107 pump 28 000 0.5575 feed water heater 51 000 0.5129 deaerator 17 100 0.5575 generator 138300 0.3139 the total annual operating cost (coopr), is obtained on an annual basis, including the cost of operating labor (colab), the cost of purchasing fuel (cof), the cost of servicing and maintenance (com), insurance and general costs (coinscgen). minscgenmlabfuelopr cccccc   (11) the annual cost of purchasing fuel (cof) : hrcgvfuel pc  (12) where cgp, is the price of fuel (natural gas) on the algerian market is set by the value 2 €/mwh [16]. the annual cost of operating labor is given by the following formula: cnlab labavrc ,emp (13) the annual cost of insurance and general costs: totinscgen ic 0.025 (14) the insurance costs are considered as 2.5 % of the total fixed cost [15]. the annual cost of maintenance is given by the following formula: totm ic 0.05  (15) the annual cost of maintenance considered as 5 % of the total fixed cost [15]. the annual revenues (rann) from the generated power: pann cehrwr  (16) where: ξ as 90 %, takes into account the energy needs of auxiliary equipment [15], cep is the current price of electricity on the algerian market is set by the value 33 є/mw [16], while hr represent number of service hours per year. finally, net present value is formulated as:     tot n j j joprann i r cor npv      1 (17) where: r and n are the discount rate (9%) and the life of the plant (35 years) respectively [15], [17]. ii.2.3. environmental modeling this study also examines the environmental impacts including the co2 emissions, and the cooling water consumptions. the general expression for the combustion of methane is written based on stochiometric combustion:   ohnconoch 222224 23.6767.32  (18) the cooling water consumption was also investigated by calculating the mass flow rate (ṁc) as: )t(tcp lm m c,c,c vh c outin     (19) iii. results and discussion iii.1. validation in order to confirm the credibility of the developed model, its performances are evaluated by comparing the obtained results using the energy model with those of real data given by the manufacturer of achouat-jijel plant. table 4 represents the statistical comparison between the two based on the relative error at some points. the error of the mass flow rate of the steam goes from a minimum value of 0.09% at the inlet of the boiler to a maximum value of 13.92% at the outlet of the condenser. on the other hand, the pressure error varies from a minimum value of 0% at the majority of the main points, to a maximum value of 3.01% at the outlet of hpt. in addition, the maximum temperature error is 2.94% at the outlet of the deaerator. table 4. statistical comparison between the manufacturer's data and the results of the model. point parameter manufacturer data model results error (%) boiler inlet t (°c) 244 242.9 0.45 p (bar) 178.5 178.5 0 ṁ (kg/s) 171.5 171.66 0.09 hpt outlet t (°c) 329 321.29 2.39 p (bar) 26.7 27.53 3.01 ṁ (kg/s) 160.27 165.92 3.4 condenser outlet t (°c) 33.5 33.81 0.91 p (bar) 0.0527 0.0527 0 ṁ (kg/s) 125.25 145.52 13.92 deaerator outlet t (°c) 169.2 164.37 2.94 p (bar) 6.9 6.9 0 ṁ (kg/s) 171.5 171.66 0.09 i. meriche et al ijeca-issn: 2543-3717. december 2021 page 39 iii.2. 4e comparative study between the five configurations according to the figures 1-5, it can be noticed that the quality of the steam at the outlet of the lpt is much better in the cycles which include the heating system than in the other cycles (basic cycle, regenerative cycle). the quality varies from a minimum value of 85.51% for the simple cycle, to a maximum value of 94.84% for the fourth configuration; this positive variation is due to the reheating system that works to improve the quality of steam at the lpt. on the other hand, it can be noticed that the steam mass flow in the system decreases when using the reheating system, which goes from a value of 173.5 kg/s in the simple cycle to 144.27 kg/s in the reheating cycle, while the value in the presence of regeneration processes is 154.55 kg/s. furthermore, due to the addition of different processes in each configuration, differences in performance (energy and exergy), and economic and environmental parameters arise. these differences are shown in table 5. furthermore, figure 6 shows the evolution of npv with the lifetime of the installation with the five layouts. table 5. 4e comparative analysis of the five configurations. configurations 1 2 3 4 5 energy efficiency (%) 35.74 37.41 38.31 40.02 41.09 exergy efficiency (%) 33.7 35.26 36.11 37.73 39.5 fuel consumption (kg/s) 19.7 18.9 18.32 17.61 16.81 co2 emissions (kg/s) 54.04 51.85 50.26 48.31 46.12 cooling water usage (m3/s) 9.64 8.99 8.56 8.01 7.42 investment cost (m€) 119.87 119.87 121.76 123.24 132.12 operating cost (m€/yr) 23.26 22.7 22.46 22.23 21.69 npv (m€) 96 102 102.2 103.1 100 dpp (years) 8.7 8.3 8.4 8.5 9 figure 1. stream at each point of the basic configuration. figure 2. stream at each point of the configuration with reheating. figure 3. stream at each point of the regenerative configuration. i. meriche et al ijeca-issn: 2543-3717. december 2021 page 40 figure 4. stream at each point of the configuration with reheating and regeneration on both turbines (lpt and hpt). figure 5. stream at each point of the fifth configuration. figure 6. evolution of npv with lifetime of the installation with the five layouts. i. meriche et al ijeca-issn: 2543-3717. december 2021 page 41 from table 5, it seems that the fifth configuration (similar to achouat plant) has the highest energy and exergy performances, with values of 41.9% and 39.5% respectively, therefore energy and exergy gains of 6.16% and 5.8% respectively are attained compared to the simple cycle (configuration 1). this explains the essential role of regeneration and reheating systems in the process of improving the performances of steam power plants. on the environmental point of view, and according to table 5, the fifth configuration is always the best, with a fuel consumption of 16.81 kg/s, which refers to a decrease of 2.89 kg/s compared to the first configuration, and 0.8 kg/s compared to the fourth configuration. in addition, the fifth configuration has the lowest rate of co2 emissions with a value of 46.12 kg/s, which represents a decrease of 7.93 kg compared to the first configuration, and 2.19 kg compared to the fourth one. on the other hand, the fifth configuration always remains the best configuration in term of water consumption for the cooling process, with the lowest value of 7.42 m3/s, with a saving of 2.22 m3/s compared to the simple cycle (first configuration). this difference is due to the decreasing in the mass flow rate of the steam at the outlet of the low-pressure turbine (lpt). in the economic dimension, there is an increase in the investment cost, when different thermal equipment are added to the plant, with a minimum value of almost 119.9 million euros (m€) for the simple cycle (configuration 1), and a maximum value of 132.12 million euros for the fifth configuration, thus, a difference of 12.25 m€ between the two layouts. on the other hand, the annual operating cost improves as the thermal equipment increases with a minimum value of 21.69 m€/year for the fifth configuration and a maximum value of 23.26 m€/year for the first configuration, and this is mainly due to the amount of fuel consumed. from figure 6, it can be observed a clear convergence in the npv in configurations with reheating and regeneration. the net present value is 1.07 times greater for the fourth configuration than the first one; with a maximum value in the fourth configuration recorded 103.1 million euros and the minimum value in the first configuration 96 million euros. in addition, it is noted the shortest depreciated payback period (dpp) for the second configuration is 8.3 years; this is mainly due to the low investment cost. the longest depreciated payback period (dpp), it goes back to the fifth configuration, 9 years. after this period, the plant begins to make a profit. iv. conclusion in this study, 4e (energy exergyeconomic environmental) comparative study of five different configurations of a power cycle was performed. thus, a validation was carried out to verify the reliability of the developed model compared to real data of achouat power plant. the results indicate relevant differences; the energy and exergy efficiencies of the achouat power station are the highest with values of 41.9% and 39.5% respectively, while the worst configuration was that of the basic cycle with the values of 35.74% and 33.7% respectively. on the other hand, achouat's configuration shows better environmental performance represented by the co2 emission rate and the cooling water usage. the net present value is 1.07 times greater for the fourth configuration than the first configuration. in addition, it is noted from the predictions that the shortest depreciated payback period (dpp) for the second configuration is 8.3 years. as for the longest depreciated payback period (dpp), it goes back to the fifth configuration, 9 years. after this period, the plant begins to make a profit. i. meriche et al ijeca-issn: 2543-3717. december 2021 page 42 nomenclature c cost (€) ṁout outlet mass flow rate (kg/s) cavr,lab average labour cost (€) ṁp mass flow rate of a primary fluid (kg/s) cd direct cost (€) ṁs mass flow rate of a secondary fluid (kg/s) ceqp total cost of equipments (€) ṁsteam mass flow rate of steam (kg/s) ceqp i initial cost of equipment (€) ṁwater mass flow rate of water (kg/s) cind indirect cost (€) n number (-) copr operating cost (€) npv net present value (€) cpc heat capacity of cooling water (kj/k) nemp number of employees (-) cep electric price (€) q heat quantity (mw) cgp gas price (€) r ideal gas constant (kj/mol.k) cof fuel cost (€) rann annual revenues (€) coinscgen insurance and general costs (€) r discount rate (%) colab labor cost (€) s entropy (kj/k) com maintenance cost (€) s0 specific entropy (kj/kg. k) ėx exergy (mw) t temperature (°c) ėxchm chemical exergy (mw) t0 ambient temperature (°c) ėxin inlet exergy (mw) tc,in inlet temperature of cooling water (°c) ėxph physical exergy (mw) tc,out outlet temperature of cooling water (°c) ėxprd product exergy (mw) v volume flow rate (m 3/h) ėxq heat exergy (mw) ẇ power (mw) ėxsrc source exergy (mw) ẇele electrical power (mw) ėxtm thermo-mechanical exergy (mw) ẇnet net power (mw) ėxw work exergy (mw) ẇpum pump power (mw) ex specific exergy (kj/kg) ẇtub turbine power (mw) exin specific inlet exergy (kj/kg) y molar fraction (-) exout specific outlet exergy (kj/kg) abbreviation h enthalpy (kj/kg) con condenser h0 specific enthalpy (kj/kgk) csp concentrating solar power hin inlet enthalpy (kj/kg) des deaerator hout outlet enthalpy (kj/kg) ddp depreciated payback period hr number of service hours per year (hour/years) fwh feed water heater itot total investment cost (€) hpt haut pressure turbine lv latent heat (kj/kg) gen generator ṁ mass flow rate (kg/s) lpt low pressure turbine ṁc mass flow rate of cooling water (kg/s) pum pump ṁh mass flow rate of heat fluid (kg/s) tot total ṁin inlet mass flow rate (kg/s) tub turbine references [1] ministry of energy (algeria), https://www.energy.gov.dz/ [2] s.o. oyedepo et al, "thermodynamics analysis and performance optimization of a reheat –regenerative steam turbine power plant with feed water heater", fuel, vol. 280, 2020. 118577. [3] k.c. nikam, r. kumar, r. jilte, "exergy and exergoenvironmental analysis of a 660 mw supercritical coalfired power plant", j therm anal calorim, 2020. [4] k.c. nikam, r. kumar, r. jilte, "economic and exergoeconomic investigation of 660 mw coal-fired power plant", j therm anal calorim, 2020. [5] v. kumar, b. pandya, v. matawala, "thermodynamic studies and parametric effects on exergetic performance of a steam power plant", international journal of ambient energy, vol. 40, issue 1, 2017, pp. 145. [6] a. bolatturk, a. coskun, c. geredelioglu, "thermodynamic and exergoeconomic analysis of cayırhan thermal power plant", energy conversion and management, vol. 101, 2015, pp. 371–378. [7] s.n. naserabad, a. mehrpanahi, g. ahmadi, "multiobjective optimization of feed-water heater arrangement options in a steam power plant repowering", journal of cleaner production, vol. 220, 2019, pp. 253–270. [8] s.s. chauhan, s. khanam, "enhancement of efficiency for steam cycle of thermal power plants using process integration", energy, vol. 173, 2019, pp. 364–373. [9] a. remlaoui, m. benyoucef, d. assi, d. nehari, "a trnsys dynamic simulation model for a parabolic trough solar thermal power plant", int. j. energetica, vol. 4, issue 2, 2019, pp. 36-41. [10] t.e. boukelia, m.s. mecibah, a. laouafi, a. mekroud, a. bouraoui, "potential assessment of using dry cooling i. meriche et al ijeca-issn: 2543-3717. december 2021 page 43 mode in two different solar thermal power plants", int. j. energetica, vol. 2, issue 2, 2017, pp. 18-24. [11] data catalog. available at achouat power station. [12] asymptote. cycl-tempo, http://www.asimptote.nl [13] mathworks. matlab, https://www.mathworks.com [14] i. dincer, " comprehensive energy systems", elsevier, 1st edition 2018, isbn 978-0-12-809597-3. [15] a.c. caputo, m. palumbo, p.m. pelagagge, f scacchia, "economics of biomass energy utilization in combustion and gasification plants: effect of logic variables", biomass and bio energy, vol. 28, 2005, pp. 35–51. [16] global petrol prices, https://fr.globalpetrolprices.com/ [17] r. kumar, a.k. sharma, p.c. tewari, "cost analysis of a coal-fired power plant using the npv method", j ind eng int, vol. 11, 2015, pp. 495–504. i. introduction ii. data and methodology ii.2.1. thermodynamics modelling ii.2.2. economic modelling ii.2.3. environmental modeling iii. results and discussion iv. conclusion nomenclature references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 50-54 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 50 power losses reduction by optimal allocation of renewable distributed generation in distribution networks abdelkader boukaroura 1* , mohammed amroune 2 1 department of electrical engineering, university of kasdi merbah, ouargla, 30000, algeria 2 department of electrical engineering, university of ferhat abbas setif 1, setif, 19000, algeria *corresponding author e-mail: boukaroura.abdelkader@univ-ouargla.dz abstract – the electrical energy demand is increasing dramatically in many countries around the world due to population growth. as a result of this significant increase in demand, electricity distribution companies are seeking to promote distributed generation (dg). with the growing integration of decentralized renewable power generation into the distribution network, it becomes an active circuit where power flows and voltages are influenced not only by loads but also by sources. in distribution networks (dn), the optimal allocation of renewable distributed generation (dg) units can significantly improve system performance by reducing power losses and enhancing the voltage profile and stability of the radial distribution network. the main objective of this paper is to apply the marine predator algorithm (mpa) to optimize the siting and sizing of dg units in the dn. the objective function considered is the minimization of active power losses. the proposed algorithm is tested on the ieee 33-bus and 69-bus dn. the simulation results demonstrate that the mpa algorithm outperforms other optimization algorithms in terms of perform. keywords: distribution network, renewable distributed generation, marine predator algorithm, power losses. received: 16/04/2023 – revised: 09/06/2023– accepted: 26/06/2023 i. introduction the term "distributed generation" (dg) is commonly used to refer to electrical energy sources that are directly connected to the distribution network. dg can be categorized into three groups: renewable energy sources (such as wind, solar, hydro, geothermal, and biomass), non-renewable energy sources (including small gas turbines, combustion turbines, and microturbines), and storage systems (such as batteries, flywheels, supercapacitors, compressed air energy storage, and pumped storage) [1, 2]. the integration of these energy sources into the distribution network brings numerous benefits, particularly with the incorporation of renewable energy sources. these benefits encompass power loss reduction, network reinforcement, improved reliability and security, reduction in greenhouse gas emissions, minimization of system costs, and more [3]. however, the improper allocation of dgs can have a significant impact on power flow, power losses, voltage profile, and system stability [4, 5]. the integration of distributed generation (dg) into distribution networks offers several advantages, including the reduction of power losses, improvement of voltage profile along feeders, and increased maximum power transmission capacity in cables and transformers [6]. however, the installation of dg in distribution systems requires careful consideration of their optimal locations and sizes. choosing a suboptimal location with an optimal size or vice versa can lead to increased system losses and costs, as well as deterioration in voltage profile, protection, and stability. therefore, simultaneous optimization of both location and sizing of dgs in distribution systems can prove highly beneficial for the overall performance of the distribution power system [7]. meta-heuristic optimization techniques have been extensively investigated for the allocation and sizing of https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ a. boukaroura et al/ international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 50-54 page 51 different types of dgs in distribution networks. these techniques employ iterative procedures to search for optimal or sub-optimal solutions to the optimization problem. several meta-heuristic methods have been employed in this context, including genetic algorithm (ga), simulated annealing (sa), tabu search (ts), particle swarm optimization (pso), ant colony optimization (aco), non-dominated sorting ga-ii (nsga-ii), plant growth simulation algorithm (pgsa), artificial bee colony algorithm (abc), bacterial foraging algorithm (bfa), cat swarm optimization (cso), grey wolf optimization (gwo), krill herd algorithm (kha), and invasive weed optimization (iwo) [8-10]. among these approaches, the marine predator algorithm (mpa) is specifically utilized for addressing the optimal placement and sizing problem of dgs in radial distribution networks [11]. the primary focus of this study is to achieve the minimization of real power losses in distribution networks. to evaluate the effectiveness of the marine predator algorithm (mpa) method, extensive assessments are conducted using the well-known ieee 33-bus and ieee 69-bus test systems. through these evaluations, the aim is to establish the validity and performance of the mpa approach in addressing real power losses. ii. methodology ii.1. minimization of total active power loss the main objective of dg siting and sizing in the distribution network is to minimize network active power losses while satisfying some operating constraints. the objective function for the minimization of active power loss is described as:         1 1 min min cos sin loss n n ij i j i j i j i j i j i j i ji j f p r p p q q q p pq v v                        (1) where pi, pj and qi, qj are the total active and reactive power at buses i and j; rij is the resistance of the branch ij; vi, vj and δi and δj are the voltage magnitudes and the voltage angles at buses i and j, respectively. ploss can be represented in percentage (%) while doing comparison as:   _ _ _ % 100    loss base loss dg loss loss base p p p p (2) where ploss_base denoted the total power losses in the base case, while ploss_dg represents the total power losses in the presence of dg units. ii.2. constraints some constraints in the distribution network must be addressed while determining the best placement and sizing of dgs. they are explained as follows.  equality constraint in the optimal allocation of dgs, active and reactive power balance equations are defined as equality constraints. these constraints are expressed by:  , , 1 cos busn g i l i i ij j i j ij j p p v y v         (3)  , , 1 sin busn g i l i i ij j i j ij j q q v y v         (4) where pg,i and qg,i are, respectively, the active and reactive power outputs of the ith generator; pl,i and ql,i are, respectively, the active reactive powers of ith load bus; θij are the angle of ith element in the admittance matrix of the system related to buses i and j.  inequality constraints the inequality constraints subjected to dg setting and sizing problem include [11]: bus voltage: min max 1, 2,..., i bus v v v i n   (5) branch current: _ max 1, 2,..., i i br i i i n  (6) size of dg: min max dg dgi dg p p p  (7) position of dg: 2 bus bus dg n  (8) where vmin and vmax are taken as 0.95 and 1.05 (p.u.), respectively; nbus is the total number of buses; dgbus is the bus number of the dg installation; vi is the bus voltage; ii is the current of the branch i; pdg is the total power of dg and nbr is the total number of branches. ii.3. marine predator algorithm (mpa) mpa is a new swarm intelligence-based algorithm, proposed by a search [12]. this algorithm is mainly inspired by the hunting mechanism of marine predators, which is displayed in two strategies, namely, lévy and brownian motion. these two strategies depend on the shortage or abundance of prey in the defined areas. the mpa optimization procedure is divided into three essential stages considering different velocity ratios:  high-velocity ratio, or when the target is moving quicker than the predator;  unit velocity ratio, or when both predator and target move at about the same speed; and a. boukaroura et al/ international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 50-54 page 52  low-velocity ratio, or when a target is moving slower than the predator. these three stages mimic the step size of a predator’s movements when catching prey. based on these three steps and marine memory ability, the fitness of each solution for the current iteration is compared to its counterpart in the previous iteration, and the best solution is chosen. this process ameliorates the solution quality throughout the number of iterations. ii.4. implementation of mpa in dg siting and sizing this procedure can also be summarized in the following steps.  step 1: read branch data and bus data for the network.  step 2: read dg data.  step 3: set the parameters of algorithm mpa and the limits of decision variables (siting and sizing of dg).  step 4: generate the initial population for the decision variables (dg siting’s and sizes).  step 5: run backwards and forward to sweep power flow, incorporating dg.  step 6: compute the active power loss (ploss).  step 7: compute the objective functions represented by eq. (1).  step 8: update the fitness of the objective function.  step 9: repeat steps 5–8 until the maximum number of iterations.  step 10: print the optimal solution (optimal siting and sizing of dg). the other control parameters are set up according to the recommendation of the author in their original paper, as shown in table 1. [12] table 1. settings of the mpa parameters algorithm parameter settings value mpa population size maximum number of iterations p high-velocity ratio unit-velocity ratio low-velocity ratio fads 50 200 0.5 ≥ 10 1 0.1 0.2 iii. simulation results and discussion in this section, the performance of the aforementioned algorithm is evaluated using the ieee 33-bus and ieee 69-bus radial distribution networks. figure 1 illustrates the diagram of the ieee 33-bus system, which comprises main feeders and three laterals. the system operates at a voltage level of 12.66 kv and has a total load of 3720 kw and 2300 kvar. the system data can be referred to in [13]. figure 2 displays the diagram of the ieee 69-bus system, consisting of 69 buses, 7 feeders, and 68 branches. this system operates at 12.66 kv and has a total load of 3800 kw and 2690 kvar. the relevant system data is provided in [14]. figure 1. ieee 33-bus distribution test system. figure 2. ieee 69-bus distribution test system. the optimal location and sizing of dgs in the rdn is determined with the objectif of reducing active power losses. the convergence characteristic of the mpa technique is depicted in figure 3 and figure 4 mpa technique converged to the optimal solution in a small number of iterations. figure 4 and figure 6 show how the voltage profile was improved in the ieee 33-bus system and ieee69bus system. the optimal allocation results of three dgs are shown in table 2 and table 3. the obtained results reveal that the mpa algorithm outperforms other existing methods such as oppositionbased tuned-chaotic differential evolution technique (otcde) [15], manta ray foraging optimization (mrfo) algorithm [16], chaotic maps integrated stochastic fractal search (cmsfs) [17] and hybrid cbga-vsa [18]. a. boukaroura et al/ international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 50-54 page 53 figure 3. convergence curve of mpa for the 33-bus network figure 4. bus voltage profile of ieee 33-bus system figure 5. convergence curve of mpa for the 69-bus network figure 6. bus voltage profile of ieee 69-bus system table 2. results for installing dgs in the 33-bus system algorithm pl without dg (kw) with 3 dgs bus no. dg size (kw) pl (kw) pl reduction (%) mpa 201.89 14 24 30 759.0859 1071.1 1099.9 69.3833 65.6335 otcde [15] 210.98 13 24 30 801.8 1091.31 1053.6 72.785 65.5000 mrfo [16] 210.98 13 24 30 788.276 1017.1 1035.3 72.876 65.4583 cmsfs [17] 210.98 13 24 30 802 1091 1054 72.785 65.5000 cbgavsa [18] 210.98 13 24 30 801.8 1091.3 1053.6 72.785 65.5000 table 2. results for installing dgs in the 69-bus system algorithm pl without dg (kw) with 3 dgs bus no. dg size (kw) pl (kw) pl reduction (%) mpa 224.55 11 18 61 472.3495 387.9321 1738.3 68.661 69.423 otcde [15] 224.95 12 22 61 379.26 328.39 1746.46 69.761 68.99 mrfo [16] 224.95 11 18 61 524.23 369.12 1713.4 69.426 69.14 cmsfs [17] 225.00 11 18 61 527 1719 380 69.428 69.14 cbgavsa [18] 225.00 11 18 61 526.8 380.1 1710.9 69.408 69.15 iv. conclusion the placement and sizing of renewable distributed power generation (dgs) in a distribution network play a vital role in enhancing network performance. this study focuses on the optimal allocation of dg units in a distribution network using the marine predator algorithm (mpa). the objective is to minimize power losses in the radial distribution network by selecting the optimal locations and sizes for the dgs. the effectiveness of the proposed method is demonstrated through its application to the ieee 33-bus and ieee 69-bus systems. comparative analysis with other existing methods, including otcde, mrfo, cmsfs, and cbga-vsa, showcases the superior performance of the mpa algorithm in achieving the desired objectives. a. boukaroura et al/ international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 50-54 page 54 declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal. the authors confirmed that the paper was free of plagiarism. references [1] g. pepermans, j. driesen, d. haeseldonckx, r. belmans, w. d‘haeseleer. “distributed generation: definition, benefits and issues.” energy policy. 2005, pp. 787–798. [2] r. h. a. zubo, g. mokryani, h. s. rajamani, j. aghaei, t. niknam, p. pillai. “operation and planning of distribution networks with integration of renewable distributed generators considering uncertainties: a review.” renewable and sustainable energy reviews. 2016, pp. 1177–1198. [3] a. ehsan, q. yang. “optimal integration and planning of renewable distributed generation in the power distribution networks: a review of analytical techniques.” applied energy. 2018, pp. 44–59. [4] p. s. georgilakis, n. d. hatziargyriou. “a review of power distribution planning in the modern power systems era: models, methods and future research.” electric power systems research. 2015, pp. 89–100. [5] m. a. abdelkader, et al. “an analytical formula for multiple dgs allocations to reduce distribution system losses.” alexandria eng. j. 2019, pp. 1265−1280. [6] r. sirjani, a. mohamed and h. shareef. “heuristic optimization techniques to determine optimal capacitor placement and sizing in radial distribution networks: a comprehensive review,” przegląd elektrotechniczny. 2012. vol. 7, no. 12, pp. 1-7. [7] o. amanifar and m. e. hamedani golshan. “optimal distributed generation placement and sizing for loss and thd reduction and voltage profile improvement in distribution systems using particle swarm optimization and sensitivity analysis,” international journal on technical and physical problems of engineering. 2011. vol. 3, no. 2, pp. 47-53. [8] rajkumar, d. k. khatod. “optimal planning of distributed generation systems in distribution system: a review,” renewable and sustainable energy reviews. 2012, pp. 5146 -5165. [9] p. prakash, d. k. khatod. “optimal sizing and siting techniques for distributed generation in distribution systems: a review,” renewable and sustainable energy reviews. 2016, pp. 111-130. [10] w. l. theo, j. s. lim, w. s. ho, h. hashim, c. t. lee. “review of distributed generation (dg) system planning and optimization techniques: comparison of numerical and mathematical modeling methods,” renewable and sustainable energy reviews. 2017, pp. 531-573. [11] p. nguyen, n. vo. “a novel stochastic fractal search algorithm for optimal allocation of distributed generators in radial distribution systems.” applied soft computing journal. 2018, pp. 773−796. [12] a. faramarzi, m. heidarinejad, s. mirjalili, a. h. gandomi. “marine predators algorithm: a natureinspired metaheuristic.” expert systems with applications. 2020, pp. 113377. [13] m. e. baran and f. f. wu, “network reconfiguration in distribution systems for loss reduction and load balancing”, ieee transactions on power delivery. 1989, vol. 4, no. 2, pp. 1401–1407. [14] a. khodabakhshian , m. h. ardishgar, “simultaneous placement and sizing of dgs and shun capacitors in distribution systems by using imde algorithm”, international journal of electric power and energy systems. 2016, pp. 599–607. [15] s. kumar, k. kamal, n. chakraborty. “a novel opposition-based tuned-chaotic differential evolution technique for techno-economic analysis by optimal placement of distributed generation,” engineering optimization. 2020, vol. 52, no. 2, pp. 303–324. [16] g. hemeida, a. ibrahim, a. mohamed, s. alkhalaf, m. bahaa el-dine. “optimal allocation of distributed generators dg based manta ray foraging optimization algorithm (mrfo).” ain shams engineering journal. 2021, pp. 609−619. [17] t. duong, p. nguyen, n. vo, m. le. “a newly effective method to maximize power loss reduction in distribution networks with highly penetrated distributed generations,” ain shams engineering journal. 2021, vol. 12, no. 2, pp. 1787−1808. [18] o. montoya, w. gil-gonzález, c. orozco-henao. “vortex search and chu-beasley genetic algorithms for optimal location and sizing of distributed generators in distribution networks: a novel hybrid approach,” engineering science and technology, an international journal. 2020, pp. 1351–1363. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 12-17 ijeca-issn: 2543-3717. december 2020 page 12 economic evaluation of the production of titanium dioxide (tio2) nanoparticles using the simple aqueous peroxo route method aldera margianti sukawaputri, indri ayuni nur fauziah, indri puji lestari, ni putu yunika arindita, riska nur pratiwi, siti nur hofifah, asep bayu dani nandiyanto * departemen kimia, fakultas pendidikan matematika dan ilmu pengetahuan alam, universitas pendidikan indonesia, jl. dr. setiabudi no. 229, bandung 40514, jawa barat, indonesia email * : nandiyanto@upi.edu abstract – this study aims to analyze the economic evaluation on the production of tio2 nanoparticles using the simple aqueous peroxo route method. economic evaluation is carried out using several economic parameters, such as payback period (pbp), break even point (bep), and cumulative net present value (cnpv). the economic evaluation method is carried out by calculating several factors to see the potential of tio2 nanoparticle production, such as an increase in tax prices, sales prices, and the effect of raw material prices. based on tax evaluation, the greatest income achievement when taxed is 10%. based on the sales evaluation, the minimum sales price so that the company does not lose is at the 90% point. based on variations in raw material prices, an increase in raw material prices by up to 50% will not cause a loss. pbp analysis shows the investment in a short period of time, namely in the fourth year and until the 20th year the company's profits continue to increase. in conclusion, the results of the economic evaluation show good prospects. the impact of this research is the evaluation of large-scale economic data on tio2 nanoparticles, production prospects with estimated factors that may occur under ideal conditions. keywords: economic evaluation, tio2, energy and mass balance, aqueous peroxo route method, pbp analysis. received: 28/10/2020 – accepted: 20/11/2020 i. introduction tio2 nanoparticles are an example of a nanometerscale material which is currently the focus of research because tio2 is a good material for photocatalysis and the development of various biomaterials [1]. tio2 was chosen because it is relatively cheap, easy to reach, and non-toxic, its affinity for light, and its ability to degrade organic compounds and transfer energy [2]. tio2 is also an efficient catalyst, can remove various environmental pollutants, and has been shown to be able to clean wastewater and surface water [3], [4], [5]. in addition, tio2 nanoparticles are widely used in cosmetics as solar cells, paints, and foodstuffs because of their various properties, such as colloid stability, high reflection index, photo catalytic properties [6], and their size according to wavelength and ultraviolet absorbance. the biocompatibility properties of titania can also be used in bone tissue engineering for the regeneration and healing of damaged bones [7]. various studies have demonstrated the synthesis method to produce tio2 nanoparticles. the synthesis method developed includes chemical methods, such as the simple aqueous peroxo route [8], the hydrolysis and peptisation method [9], the solvothermal method [10], the sol-gel method. [11], and hydrothermal methods [12]. in addition, biosynthetic methods using plants and microorganisms have also been developed, such as using moringa oleifera leaf extract [13], trigonella foenum-graecum leaf extract [14], jatropha curcas l. leaf extract [15], cinnamon powder mailto:nandiyanto@upi.edu aldera margianti sukawaputri et al ijeca-issn: 2543-3717. december 2020 page 13 extract [16], bixa orellana seed extract [17], microorganism staphylococcus aureus [7], lactobacillus sp. and saccharomyces [18]. the most effective method used in economic evaluation is the simple aqueous peroxo route method because the method is simple, low cost, environmentally friendly, and the results are pure (no impurities). the synthesis of tio2 nanoparticles using the simple aqueous peroxo route method has been proven by their research [8]. an economic evaluation analysis for the synthesis of tio2 nanoparticles has not been carried out on an industrial scale, so to provide that data, we will present economic evaluation data in this report. the results of these studies encourage further research on the synthesis of tio2 nanoparticles. the purpose of this study was to analyze the economic evaluation data for the production of tio2 nanoparticles using the simple aqueous peroxo route method. an economic evaluation of the chemical industry is a form of a quantitative assessment of what is expected and desired by the community to carry out the process of investing in a project. this evaluation analysis uses several parameters, such as calculating the payback period (pbp) to predict the length of time it will take for an investment to be able to return the total initial outlay; cumulative net present value (cnpv) is calculated to predict project condition as a function of year of production or cnpv can be obtained as the sum of cumulative financial flows each year; calculate the break-even point (bep) which states the minimum capacity at which the project does not benefit. this bep is an important factor to avoid project losses [19]. in this study, we performed a variation of several factors to see its effect on the economic evaluation, such as increases in tax prices, decreases and increases in product prices, and the effect of raw material prices. all calculations are carried out under ideal conditions for 20 years of production. the evaluation results obtained affect the cnpv/tic curve (%) against life time (years) when the variation is carried out. the impact of this research is to find out the economic evaluation of tio2 nanoparticle production on a large scale, production prospects by predicting the worst possible factors for ideal conditions. ii. method ii.1. theoretical synthesis of tio2 nanoparticles tio2 nanoparticles can be synthesized by simple aqueous peroxo route method. synthesis using tioso4.5h2o was dissolved in water at room temperature and then 30% h2o2 was added to the solution. the resulting yellow solution shows the formation of a peroxo complex from the titanium solution. this peroxo-titanium solution produces a yellow titanium oxy-hydroxide gel after keeping at room temperature for several hours. then the gel is separated by centrifugation at a rotation speed of 10,000 rpm, washed with double distilled water, and dried overnight in the oven. the dried titanium-peroxo complex was annealed at a temperature of 200 to 550 o c for 1 hour. all processes of forming tio2 nanoparticles are shown by the flowchart in figure 1. figure 1. flowchart diagram of tio2 synthesis nanoparticles ii.2. energy and mass balance figure 2 shows the synthesis process of tio2 using tioso4.5h2o and 30% h2o2. to produce 190 kg of tio2 nanoparticles, 400 kg of tioso4.5h2o and 85 kg 30% h2o2 are required for the reaction. the formation of tio2 is in accordance with the chemical reaction equation below: aldera margianti sukawaputri et al ijeca-issn: 2543-3717. december 2020 page 14 (1) (2) (3) figure 2. process flow diagram of the synthesis of tio2 nanoparticles ii.3. economic evaluation economic evaluation that could compare the costs and consequences of alternatives and ensure an efficient choice that could maximize benefit while using minimal cost [20], equipment specifications including prices can be obtained from online shopping sites. then, all data is calculated based on literature with simple mathematical calculations to obtain various economic evaluation parameters such as gpm, pbp, bep and cnpv from various variable costs [21]. to get the results of the calculation of this study using several formulas such as: 1) gpm is calculated by selling substitutes and the cost of raw materials 2) pbp is the length of time required to return investment costs. the easiest way to get pbp is obtained from the cnpv curve. the pbp value is determined when the cnpv value first reaches zero. 3) cnpv is the value obtained from the net present value (npv) at a certain time. npv is calculated by adding a discount factor to the cash flow multiplication calculation. 4) bep is a value that describes the minimum value of production to gain profit or loss. calculated by dividing fixed costs and profits. after that, the project feasibility study was tested under ideal conditions, the effect of raw materials, and various variable costs. some of the assumptions in this study include:  all chemical compositions in the reaction, such as titanium oxisulfate pentahydrate, hydrogen peroxide, and water are used for the production of tio2 nanoparticles.  titanium oxisulfate pentahydrate has been dissolved in water and the sodium hydroxide is reacted. both are assumed to have finished reacting to give titanium oxide of 95% purity.  the conversion rate for forming titanium oxide is 100%.  loses every 5% of the transfer process.  the total investment cost (tic) is calculated based on the lang factor.  land purchased. thus, land costs are added at the beginning of the factory construction year and recovered at the end of the project.  one cycle of the tio2 nanoparticle manufacturing process takes 12 hours.  shipping costs are borne by the buyer.  tio2 nanoparticles are sold for idr 120,000.00/ pack of 500 grams (8.4 usd).  the one year project lasts 300 days.  to simplify utility, utility units can be described and converted into electrical units, such as kwh. the unit of electricity is converted into cost by multiplying the cost of electricity. assuming the utility cost is idr 1,380/kwh.  total salary per worker is assumed to have a fixed value of idr 2,850,000.00/ month.  the discount rate is 15% per year.  income tax of 10% annually.  the duration of project operation is 20 years. iii. result and discussion iii.1. cnpv in ideal conditions figure 3 shows the relationship between the x and yaxis where the x-axis is the year of production and the yaxis is cnpv/tic. in the first and second years, there was a decrease in the graph, because at the beginning of production there were costs incurred for project needs such as purchasing tools, materials, and other production support facilities. the payback period (pbp) occurs in the fourth year and has increased. the payback period (pbp) is a period of time used to assess the capital in a business or to see how long it takes for a new business to return investment [22]. the profit earned every year increases until the 20th year. this shows that the aldera margianti sukawaputri et al ijeca-issn: 2543-3717. december 2020 page 15 production of tio2 nanoparticles can be said to be a profitable project. figure 3. cnpv in ideal conditions iii.2. variations in tax increases figure 4 shows the effect of a tax increase on cnpv/tic. the x-axis is the year of production while the y-axis is the cnpv/tic value which is affected by changes in the tax prices. variations of tax prices are starting from 10%, 15%, 20%, 25%, 30%, 35%, and 40%. the pbp (payback period) value for each variation of tax increases is different. the greater the value of tax, the year of return is longer. with a production time of 20 years, the company with a 10% tax obligation has the largest profit. this shows that the greater the tax value that must be paid. the company received more/less profit [23]. figure 4. variation of the tax increase to the value of cnpv/tic iii.3. variations in selling prices figure 5 shows the cnpv chart with variations of selling prices. the x-axis is the life time (year) and the yaxis is cnpv/tic. the variations in the selling price are the range if they are increased or decreased, namely 130%, 120%, 110%, 100%, 90%, 80%, and 70%. the results of the payback period (pbp) are shown in figure 5. the initial conditions (from 0 to 2 years of the project) of cnpv at variations of selling price are the same because the project is still under construction. the effect of selling price on cnpv can be obtained after 2 years. profits continue to increase after reaching the pbp point until the 20th year. the profits obtained each year increases with the increase in selling price from ideal conditions. however, the profits obtained each year decreases with the decrease in selling price and losses when the selling price is decreased by 20 and 30% from ideal conditions. thus, the minimum selling price for obtaining bep (the point at which both the profit and loss in the project) is 90%. changes in selling prices less than 90% lead to project failure [24]. figure 5. variation in selling prices against cnpv/tic value iii.4. variations of increase in raw material prices instability in raw material prices can affect a project. an analysis is needed to prevent failure if the price of raw materials increases. the analysis was carried out on variations in the increase in raw material prices by 10%. the variations are 0% (no increase), 10%, 20%, 30%, 40%, and 50%. this variation is carried out with the assumption that the production capacity in each variation is the same as the production capacity in ideal conditions, but with different raw material prices. this evaluation is carried out to analyze the effect of changes in raw material prices on the profitability of tio2 nanoparticles production. if there is an increase in raw material prices, the cnpv/tic chart changes as shown in figure 6. from this graph, it can be concluded that the greater the price of the raw materials aldera margianti sukawaputri et al ijeca-issn: 2543-3717. december 2020 page 16 used, the slower the rate of increase in cnpv/tic. this means that by increasing the price of raw materials, the rate of income and profit decreases. this occurs because raw materials are closely related to overall production costs. with the same number of sales, an increase in production costs will reduce profits. with the remaining production and sales capacity, an increase in production costs will reduce profits. the increase in raw material prices has a negative impact on this project [25]. the results of the pbp analysis show that capital will return to variations in the increase in raw material prices by 10%, 20%, 30%, 40%, and 50% respectively in years 5, 5, 6, 7 and 9. profits will continue to increase after pbp reaches its 20th year. the cnpv/tic variations in the 20th year were 2.59%, 2.17%, 1.75%, 1.32%, 0.90%, and 0.48%. so, even if there is a condition, the price of materials will still increase by up to 50%, the project can run. figure 6. variations in raw material prices for cnpv/tic iv. conclusion we conducted an economic evaluation of the synthesis of tio2 nanoparticles by the simple aqueous peroxo route method. the results of the economic evaluation show good prospects. based on the tax increase evaluation, the company gets the biggest profit when the tax liability is 10%. from the sales evaluation, the minimum sales price so that the company does not lose is at the 90% point. based on variations in raw material prices, an increase in raw material prices of up to 50% will not cause losses. pbp analysis shows that investment returns in a short time, namely in the fourth year and until the 20th year the company's profits continue to increase. the ups and downs of company profits are influenced by several factors including tax increases, increases in raw material prices and sales prices. the results of our research are expected to provide an economic evaluation for the development of tio2 nanoparticle synthesis using a simple aqueous peroxo route method, a production prospect by estimating the worst possible factors under ideal conditions. acknowledgements we would like to thank the universitas pendidikan indonesia for supporting the preparing of this paper. references [1] s. santangelo, g. messina, g. faggio, a. donato, l. d. luca, n. donato, a. bonavita, g. neri, "microramananalysis of titanium oxide/carbon nanotubes based nanocomposites for hydrogen sensing applications", journal of solid state chemistry, vol. 183, issue 10, 2010, pp. 2451-2455. [2] a. b. d. nandiyanto, d. sofiani, n. permatasari, t. n. sucahya, a. s. wiryani, a. purnamasari, a. rusli, e. c. prima, "photodecomposition profile of organic material during the partial solar eclipse of 9 march 2016 and its correlation with organic material concentration and photocatalyst amount", indonesian journal of science and technology, vol. 1, no. 2, 2016, pp. 132-155. [3] y. sun, b. mayers, y. xia, "transformation of silver nanospheres into nanobelts and triangular nanoplates through a thermal process", nano letters, vol. 3, no. 5, 2003, pp. 675–679. [4] a. v. kirthi, a. a. rahuman, g. rajakumar, s. marimuthu, t. santhoshkumar, c. jayaseelan, g. elango, a. a. zahir, c. kamaraj, a. bagavan, "biosynthesis of titanium dioxide nanoparticles using bacterium bacillus subtilis", materials letters, vol. 65, issue 17–18, 2011, pp. 2745–2747. [5] c. gélis, s. girard, a. mavon, m. delverdier, n. paillous, p. vicendo, "assessment of the skin photoprotective capacities of an organo-mineral broad-spectrum sunblock on two ex vivo skin models", photodermatol photoimmunol photomed, vol. 19, issue 5, 2003, pp. 242253. [6] j. l. znaidi, r. seraphimova, j. bocquet, c. colbeaujustin, c. pommier, "a semicontinuous process for the synthesis ff nanosize tio2 powders and their use as photocatalysts", materials research bulletin, vol. 36, 2001, pp. 811-825. [7] k. s. landage, g. k. arbade, p. khanna, c. .j. bhongale, "biological approach to synthesize tio2 nanoparticles using staphylococcus aureus for antibacterial and antibiofilm applications", journal of microbiology & experimentation, vol. 8, issue 1, 2020, pp. 36-43. [8] s. karuppuchamy, j. m. jeong, "synthesis of nanoparticles of tio2 by simple aqueous route", journal of oleo science, vol. 55, no. 5, 2006, pp. 263–266. [9] s. mahshid, m. askari, m. s. ghamsari, "synthesis of tio2 nanoparticles by hydrolysis and peptization of titanium isopropoxide solution", journal of materials processing technology, vol. 189, issue 1–3, 2007, pp. aldera margianti sukawaputri et al ijeca-issn: 2543-3717. december 2020 page 17 296–300. [10] c. s. kim, b. k. moon, j. h. park, b. c. choi, h. j. seo, "solvothermal synthesis of nanocrystalline tio2 in toluene with surfactant", journal of crystal growth, vol. 257, issue 3–4, 2003, pp. 309–315. [11] r. s. devi, d. r. venckatesh, d. r. sivaraj, "synthesis of titanium dioxide nanoparticles by sol-gel technique", international journal of innovative research in science, engineering and technology, vol. 3, issue 8, 2014, pp. 15206–15211. [12] h. xiong, l. wu, y. liu, t. gao, k. li, y. long, r. zhang, l. zhang, z. a. qiao, q. huo, x. ge, s., song, h. zhang, "controllable synthesis of mesoporous tio2 polymorphs with tunable crystal structure for enhanced photocatalytic h2 production", advance energy material, vol. 9, issue 31, 2019, pp. 1-9. [13] v. patidar, p. jain, "green synthesis of tio2 nanoparticle using moringa oleifera leaf extract vivek", international research journal of engineering and technology (irjet), vol. 4, issue 3, 2017, pp. 470-473. [14] s. subhapriya, p. gomathipriya, "green synthesis of titanium dioxide (tio2) nanoparticles by trigonella foenum-graecum extract and its antimicrobial properties", microbial pathogenesis, vol. 116, 2018, pp. 215–220. [15] s. p. goutam, g. saxena, v. singh, a. k. yadav, r. n. bharagava, k. b. thapa, "green synthesis of tio2 nanoparticles using leaf extract of jatropha curcas l. for photocatalytic degradation of tannery wastewater", chemical engineering journal, vol. 336, 2018, pp. 386396. [16] g. nabi, w. raza, m. b. tahir, "green synthesis of tio2 nanoparticle using cinnamon powder extract and the study of optical properties", journal of inorganic and organometallic polymers and materials, vol. 30, issue 4, 2020, pp. 1425–1429. [17] i. c. maurya, s. singh, s. senapati, p. srivastava, l. bahadur, "green synthesis of tio2 nanoparticles using bixa orellana seed extract and its application for solar cells", solar energy, vol. 194, 2019, pp. 952–958. [18] a. k. jha, k. prasad, a. r. kulkarni, "synthesis of tio2 nanoparticles using microorganisms", colloids and surfaces b: biointerfaces, vol. 71, issue 2, 2009, pp. 226– 229. [19] f. nandatamadini, s. karina, a. b. d. nandiyanto, r. ragaditha, "feasibility study based on economic perspective of cobalt nanoparticle synthesis with chemical reduction method", international journal of energetica, vol. 7, no. 1, 2019, pp. 17-22. [20] a. a. shafie, g. n. chua, y. v. yong, "steps in conducting an economic evaluation. in economic evaluation of pharmacy services", elsevier inc, 2017, pp. 135-157. [21] a. b. d. nandiyanto, "cost analysis and economic evaluation for the fabrication of activated carbon and silica particles from rice straw waste", journal of engineering science and technology, vol. 13, issue 6, 2018, pp. 1523-1539. [22] i. yacob, "studi kelayakan bisnis", jakarta: rineka cipta, 2002. [23] d. priatna, a. b. d. nandiyanto, "engineering and economic evaluation of production of mgo nanoparticles using a physicochemical method", international journal of advanced smart convergence, vol. 8, issue 4, 2019, pp. 26-33. [24] d. b. d. a. putri, a. b. d. nandiyanto, "evaluasi ekonomi dari produksi nanopartikel magnesium oksida melalui metode sol-gel combustion", satuan tulisan riset dan inovasi teknologi, vol. 4, no. 2, 2019, pp. 160168. [25] p. s. dewi, a. b. d. nandiyanto, "economic perspective in the production of copper nanowire using amino acids as capping agent," international journal of energetica, vol. 4, issue 2, 2019, pp. 30-35. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 07-11 ijeca-issn: 2543-3717. december 2020 page 7 economic and technical evaluation of lifepo4 production using hydrothermal method alya chairunnisa, sarah ayu wulandari, shafa salsabila, silmi ridwan putri, wulan maryam, asep bayu dani nandiyanto * departemen pendidikan kimia, universitas pendidikan, indonesia email * : nandiyanto@upi.edu abstract – the aim of this study is to evaluate the economic and engineering layout carried out on a factory scale lifepo4 production using the hydrothermal synthesis method. the method used is economic evaluation by calculating gross profit margin (gpm), payback period (pbp), breakeven point (bep), internal rate return (irr), cumulative net present value (cnpv), return on investment (roi). , and the profitability index (pi). lifepo4 was synthesized using precursors feso4.h2o, ascorbic acid and h3po4 and then reacted with lioh2.2h2o by maintaining the li: fe: p molar ratio of 3: 1: 1. the results of gpm and cnpv calculations from the manufacture of industrial scale lifepo4 show that the payback period (pbp) has increased in the fourth year. lifepo4 applications on an industrial scale can be used for lithium ion batteries. keywords: evaluate the economic, hydrothermal synthesis method, lithium, batteries. received: 28/10/2020 – accepted: 01/12/2020 i. introduction lithium ion batteries are very widely used, especially for rechargeable batteries [1,2]. lifepo4 is very likely to be used as a cathode in lithium ion batteries [3,[4] because it is cheap, has a good specific capacity (170 mah/g), the battery life cycle is good [1,2], safe, the structure is stable [2], a li/li+ charge-discharge curve at a voltage of ~3.45v [2], and the properties of the phosphate are excellent [3]. however, the disadvantage of lifepo4 as a lithium ion battery cathode is its low electrical conductivity [1-4] which limits the extraction of lithium ions and can reduce the charge/discharge capacity [2,4]. the cause of this electrical conductivity is the large band gap of pure lifepo4. there are several lifepo4 synthesis methods reported by researchers, including hydrothermal method [5-13], solid state reaction [14-18], freeze drying [14-16,19], and co-precipitation [19-25]. the most appropriate method used in economic evaluation is hydrothermal because the reaction process is simple and the raw materials are easy to obtain. therefore, the aim of this study is to evaluate the technical feasibility and economics of manufacturing lifepo4 nanoparticles on an industrial scale. in this study, we vary several factors to see their effect on the economic evaluation under study, such as increases in tax prices, decreases and increases in product prices, and the effect of raw material prices. ii. experiment ii.1. theoretical synthesis of lifepo4 nanoparticles all chemicals used are "ar grade" and purchased at sinopharm chemical reagent. the synthesis method used is the hydrothermal method by reacting precursors made of feso4.7h2o, h3po4 (85 wt.%), and ascorbic acid. the three materials were dissolved in 50 ml of deionized water using magnetic stirring so that all the materials reacted completely. lioh that has been dissolved in deionized water is also needed and slowly added to the previous solution to maintain the li:fe:p molar ratio of 3:1:1. the resulting mixture was transferred to a stainless steel autoclave and then tightly closed to prevent oxidation of the precursors. the mailto:nandiyanto@upi.edu alya chairunnisa et al ijeca-issn: 2543-3717. december 2020 page 8 autoclave was stored in a silicone oil bath and heated to 100-180 ° c for 0-180 minutes with magnetic stirring. furthermore, the autoclave is cooled to room temperature in an oil bath. the precipitate formed was separated from the supernatant by steam filtration and then washed several times with deionized water to produce pure lifepo4 nanoparticles. the supernatant is measured to measure its ph. the process of forming lifepo4 nanoparticles according to the flowchart in figure 1. figure 1. flow diagram of the synthesis of lifepo4 nanoparticles ii.2. energy and mass balance the synthesis process of lifepo4 is shown in figure 2. the materials needed for the synthesis of lifepo4 are 1.724 kg h3po4, 0.2g ascorbic acid, 4.1703 g feso4.7h2o, and 49.85 ml h2o. lioh solution is also needed as a precursor. the solution was prepared by dissolving 1.8882 g lioh.h2o in 29.91 ml h2o. the synthesis process is carried out in a stainless steel autoclave stored in a silicone oil pen. the autoclave was heated to 100-180 ° c for 0-180 minutes with magnetic stirring. then the autoclave is cooled to room temperature in an oil bath. the precipitate formed is separated from the supernatant by filtering. the precipitate is washed several times with deionized water to remove impurities. the work steps are made in the flow diagram in figure 2. the formation of lifepo4 follows the chemical reaction equation as follows: (1) lioh.h2o(s) + h2o(l) → li+(aq) + oh-(aq) + 2h2o(l) (2) li+(aq) + oh-(aq) + 3h2o(l) + h3po4(s) + c6h8o6(s) + feso4.7h2o(s) → lifepo4(s) + c6h8o6(s) + h2so4(aq) + 11h2o(l) from a technical point of view, the amount of lifepo4 nanoparticle production allows it to be increased because the capacity and quantity of tools and materials used can be enlarged. to produce about 16.2 kg of lifepo4 nanoparticles in one day, it takes 1 reaction cycle using about 188.82 kg of lioh.h2o, 172.4 kg h3po4, 20 kg of ascorbic acid, 417.03 kg feso4,6h2o, and 7000 l h2o. with a total raw material cost of rp1.976.90.650.000,00 and a one-year profit of $ 536,679,789.24 in ideal conditions with a project life of 20 years. figure 2. flowchart of the lifepo4 nanoparticle synthesis process ii.3. economic evaluation this method is done by analyzing some raw data. then the data is calculated to obtain various evaluation meters. in short, to obtain economic evaluation parameters, several calculations can be used such as: 1. break event point (bep) is a value that describes the minimum production value to gain profit or loss. it has been calculated by dividing the fixed costs and profits [26]. 2. cnpv (cumulative net present value) to predict and evaluate project conditions as a function of time (in years) [27]. 3. interval rate of return (irr) is the rate of return on annual income so that the initial capital is reduced to zero during the project [28]. alya chairunnisa et al ijeca-issn: 2543-3717. december 2020 page 9 4. profit investment (pi) is a ratio between the cumulative net present value and the total investment cost. pi corresponds to the type of return on investment or profit for each sale [26]. after doing the calculations, there are several assumptions in this study, including: calculation of 1 usd is equivalent to idr 15,000.00. all item prices are based on online market prices. the chemical composition in the reaction to form the lifepo4 nanoparticle product is increased by 1000 times. the purity of lifepo4 nanoparticles is assumed to be 90%, while 10% is lost due to mechanical treatment. the cycle for making lifepo4 nanoparticles per day is 12 hours. total salary per worker is assumed to be idr 3,750,000 / month. 10% income tax. value discount of 15%. the project operation duration is 15 years. the project lasts 300 days/year iii. results and discussion iii.1. cnpv in ideal condition figure 3 shows the relationship between the value of profit investment (pi) and the year of production. the curve shows constant income in the first and second years, and in the third year the return to the initial capital or called payback [26]. the increase in profit is then obtained every year until the 14th year. figure 3. cnpv under ideal conditions per year iii.2. tax increase variations figure 4 shows the effect of a tax increase on cnpv/tic. the x-axis is the year of production while the y-axis is the cnpv/tic value which is influenced by changes in tax prices. the tax rates vary from 10, 20, 30, 40, and 50%. the pbp value for each variation of tax increases is different. the greater the tax value, the longer the pbp is. the graph shows that the greater the tax value, the less profit will be received. figure 4. variations in tax increases against cnpv/tic iii.3. selling price variations figure 5 shows the effect of the selling price on the cnpv/tic value where the x-axis is the year of production and the y-axis is cnpv/tic with the effect of the selling price. the variation of the selling price is the range if it is lowered or increased, namely 70, 80, 90, 100, 110, 120, and 130%. based on figure 5, the 130% selling price variant shows the fastest payback period or pbp while the 70% selling price shows the longest pbp. the payback period (pbp) is faster if the selling price increases, and longer if the selling price is lowered. the profit obtained with the same production time, which is 14 years, shows that the higher the selling price, the greater the profit, and if the selling price decreases, the profits will be smaller. alya chairunnisa et al ijeca-issn: 2543-3717. december 2020 page 10 figure 5. variations in selling price increases against cnpv/tic iii.4. variations in raw material prices figure 6 shows the variation in the price of cnpv/tic raw materials against the year of production. the x-axis shows the year of production while the y-axis is the cnpv/tic value which is influenced by the increase in raw material prices. based on figure 6, if there is an increase in raw material prices, the cnpv/tic chart changes. if the increase is at 0%, the payback period (pbp) and profits decrease. this shows that the smaller the material, the smaller the profit and payback period (pbp) [29]. figure 6. variations in raw material prices against cnpv/tic iv. conclusion in the study, you have conducted regarding the economic evaluation and production layout of lifepo4 using the hydrothermal method. the results obtained in the economic evaluation are good. based on the payback period (pbp) occurs in the fourth year of production and will increase until 2034. based on the tax price, the greater the tax price, the less profit is earned. the cnpv/tic and pbp value analysis is mostly influenced by several factors such as price variations, sales tax and selling price. the results of our research regarding the economic evaluation and production layout of lifepo4 using the hydrothermal method are expected to provide an industrial scale depiction of economic and layout evaluation, especially in the production of lifepo4 which is used as a lithium ion battery. acknowledgements thanks to the course of industrial chemistry and universitas pendidikan indonesia who have supported the preparation of this paper. references [1] x. tu, y. zhou, y. song, “freeze-drying synthesis of three-dimensional porous lifepo4 modified with welldispersed nitrogen-doped carbon nanotubes for highperformance lithium-ion batteries”, applied. surfice science, vol. 400, 2017, pp. 329–338. [2] y. cui, x. zhao, r. guo, “improved electrochemical performance of la0.7sr0.3mno3 and carbon co-coated lifepo4 synthesized by freeze-drying process”, electrochimia acta, vol. 55, no. 3, 2010, pp. 922–926. [3] v. palomares, a. goñi, i. gil de muro, i. de meatza, m. bengoechea, i. cantero and t. rojo, “influence of carbon content on lifepo4/c samples synthesized by freezedrying process”, journal of electrochemical society, vol. 156, no. 10, 2009, pp. a817. [4] verónica palomares, aintzane goñi, izaskun gil de muro, iratxe de meatza, miguel bengoechea, oscar miguel, teófilo rojo, “new freeze-drying method for lifepo4 synthesis”, journal of power sources, vol. 171, no. 2, 2007, pp. 879–885. [5] satish bolloju, rupesh rohan, shao-tzu wu, ho-xin yen, gopeshwar d. dwivedi, yuya a. lin, jyh-tsung lee, “a green and facile approach for hydrothermal synthesis of lifepo4 using iron metal directly”, electrochimia acta, vol. 220, 2016, pp. 164–168. [6] andrea paolella, giovanni bertoni, pierre hovington, zimin feng, roxana flacau, mirko prato, massimo colombo, sergio marras, liberato manna, stuart turner, gustaaf van tendeloo, abdelbast guerfi, george p. demopoulos, karim zaghib “cation exchange mediated elimination of the fe-antisites in the hydrothermal synthesis of lifepo4”, nano energy, vol. 16, 2015, pp. 256–267. [7] f. ruiz-jorge, a. benítez, s. fernández-garcía, j. sánchez-oneto, and j. r. portela, “effect of fast heating and cooling in the hydrothermal synthesis on lifepo4 alya chairunnisa et al ijeca-issn: 2543-3717. december 2020 page 11 microparticles”, industrial & engineering chemistry research, vol. 59, no. 19, 2020, pp. 9318–9327. [8] y. cui, x. zhao, r. guo, “enhanced electrochemical properties of lifepo4 cathode material by cuo and carbon co-coating”, journal of alloys and compounds, vol. 490, no. 1–2, 2010, pp. 236–240. [9] b. pei, q. wang, w. zhang, z. yang, m. chen, “enhanced performance of lifepo4 through hydrothermal synthesis coupled with carbon coating and cupric ion doping”, electrochimia acta, vol. 56, no. 16, 2011, pp. 5667–5672. [10] g. meligrana, c. gerbaldi, a. tuel, s. bodoardo, n. penazzi, “hydrothermal synthesis of high surface lifepo4 powders as cathode for li-ion cells”, journal of power sources, vol. 160, no. 1, 2006, pp. 516–522. [11] b. pei, h. yao, w. zhang, z. yang, “hydrothermal synthesis of morphology-controlled lifepo4 cathode material for lithium-ion batteries”, journal of power sources, vol. 220, 2012, pp. 317–323. [12] daiwon choi, donghai wang, vish v. viswanathan, intae bae, wei wang, zimin nie, ji-guang zhang, gordon l. graff, jun liu, zhenguo yang, tien duong,, “li-ion batteries from lifepo4 cathode and anatase/graphene composite anode for stationary energy storage”, electrochemistry communications, vol. 12, no. 3, 2010, pp. 378–381. [13] x. qin, x. wang, h. xiang, j. xie, j. li, y. zhou, “mechanism for hydrothermal synthesis of lifepo4 platelets as cathode material for lithium-ion batteries”, journal of physical chemistry c, vol. 114, no. 39, 2010, pp. 16806–16812. [14] m. higuchi, k. katayama, y. azuma, m. yukawa, m. suhara, “synthesis of lifepo4 cathode material by microwave processing”, journal of power sources, vol. 119–121, 2003, pp. 258–261. [15] d. h. kim and j. kim, “synthesis of lifepo4 nanoparticles in polyol medium and their electrochemical properties”, electrochemical and solid-state letters, vol. 9, no. 9, 2006, pp. 439–442. [16] j. lim, v. mathew, k. kim, j. moon, j. kim, “one-pot synthesis of multi-morphous lifepo4 nanoparticles in polyol medium”, journal of the electrochemical society, vol. 158, no. 6, 2011, pp. a736. [17] jinsub lim, donghan kim, vinod mathew, docheon ahn, jungwon kang, sung-won kang, jaekook kim, “platetype lifepo4 nanocrystals by low temperature polyolassisted solvothermal reaction and its electrochemical properties”, journal of alloys and compounds, vol. 509, no. 31, 2011, pp. 8130–8135. [18] gim jihyeon, kang jungwon, song jinju, park hyosun, baek sora, kim jaekook., “synthesis of lifepo4 using fe 3+ precursors in polyol medium”, journal of the electrochemical society, vol. 159, no. 4, 2012, pp. a459– a463. [19] d. h. kim, j. kim, “synthesis of lifepo4 nanoparticles and their electrochemical properties”, journal of physics and chemistry of solids, vol. 68, no. 5–6, 2007, pp. 734– 737. [20] j. s. lim, d. h. kim, v. mathew, d. c. ahn, j. k. kim, “synthesis of lifepo4 nanoparticles by solvothermal process using various polyol media and their electrochemical properties”, journal of nanoscience and nanotechnology, vol. 11, no. 2, 2011, pp. 1451–1454. [21] s. a. hong, s. j. kim, j. kim, k. y. chung, b. w. cho, j. w. kang, “small capacity decay of lithium iron phosphate (lifepo4) synthesized continuously in supercritical water: comparison with solid-state method”, journal of supercritical fluids, vol. 55, no. 3, 2011, pp. 1027–1037. [22] j. lee and a. s. teja, “characteristics of lithium iron phosphate (lifepo4) particles synthesized in subcritical and supercritical water”, journal of supercritical fluids, vol. 35, no. 1, 2005, pp. 83–90. [23] a. aimable, d. aymes, f. bernard, f. le cras, “characteristics of lifepo4 obtained through a one step continuous hydrothermal synthesis process working in supercritical water”, solid state ionics, vol. 180, no. 11– 13, 2009, pp. 861–866. [24] d. rangappa, m. ichihara, t. kudo, i. honma, “surface modified lifepo4/c nanocrystals synthesis by organic molecules assisted supercritical water process”, journal of power sources, vol. 194, no. 2, 2009, pp. 1036–1042. [25] j. lee, a. s. teja, “synthesis of lifepo4 micro and nanoparticles in supercritical water”, materials letters, vol. 60, no. 17–18, 2006, pp. 2105–2109. [26] d. priatna, a. b. d. nandiyanto, “engineering and economic evaluation of production of mgo nanoparticles using a physicochemical method”, international journal of advanced smart convergence, vol. 8, no. 4, 2019, pp. 26-33. [27] p. s. dewi , a. b. d. nandiyanto, “economic perspective in the production of copper naniwire usig amino acids as capping agent”, international journal of energetica, vol 2, no. 2, 2019, pp. 30-35. [28] b. prabowo, t. khairunnisa, a. b. d. nandiyanto, “economic perspective in the production of magnetite (fe3o4) nanoparticles by co-precipitation method”, world chemical engineering journal, vol 2, no. 2, 2018, pp. 1-4. [29] g. miftahurrahman, h. setiarahayu, a. b. d. nandiyanto, “an economic evaluation on scaling-up production of nano gold from laboratory to industrial scale”, indonesian journal of computing, engineering and design (ijoced), vol 1, no. 1. 2019, pp. 29-36. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 37-42 ijeca-issn: 2543-3717. june 2020 page 37 experimental investigation of the effects of preheating on still productivity ridha cherraye 1,2* , bachir bouchekima 1,3 1laboratory of new and renewable energy in arid zones (lenreza), university kasdi merbah ouargla, 30000, algeria 2 department of process engineering, kasdi merbah university, ouargla 30000, algeria 3 department of renewable energy, kasdi merbah university, ouargla 30000, algeria e-mail*: cherrayeridha@yahoo.fr abstract – single basin solar still (sbss) has low productivity in this experimental research, some techniques have been employed to solve this problem, these techniques consist of using a flat plate collector. the main aim of this research was to make efficient use of the flat plate collector (fpc) to increase solar still productivity, and it works as a hybrid device. the model solar water heater for the flat plat collector (fpc) was coupled with a solar still, and the tests were repeated in 3 to 5 winter days, and the results were measured in the same way for each day. the results revealed that the productivity of the still increased 87 % when coupled with one, and decreased 20 % and 50 % when coupled with two and three flat plate collectors in southern algeria, respectively. keywords: solar energy, solar desalination, solar still, flat plate collector, productivity. received: 03/05/2020 – accepted: 19/06/2020 i. introduction solar energy is one of the renewable energies; it is used in several fields, especially in solar distillation. algeria has great energy potential in solar energy and it is favorable for solar distillation and heating of water. a study shows that any variation in solar radiation has an influence on the conventional solar still [1,2]. several researches have been made in the south-eastern region of algeria with the aim of treating polluted groundwater to transform it into pure portable water; researchers have conceived a small pilot distillation station in this area. their studies aim at improving the efficiency of a small solar distillation station under real insulation for underground geothermal desalination of water in the arid regions, and also to generate drinking water in arid regions. the small station had more than 15 l/m 2 of daily capacity [3-5]. in the same direction, a simpler study shows step by step the conventional solar still construction which can produce between 4 to 6 l/m 2 per day [6]. the transformation of affected groundwater into pure water is the subject of several research projects around the world [7-9]. the main objective of any researcher in the field of solar distillation is to improve the performance of a solar still using several simple, complex, economical, environmental techniques. among the techniques used, it is to take the glass cover (the condenser) as a factor of improvement; either by varying the angle of the cover (10, 15, 20, 30, 35 and 45 °) relative to the horizontal to determine the best angles which give the best performance of the still [10], either study the heat flow which passes from the interior of the still to the exterior via the cover [11], or to investigate the temperature gradient between the water and the cover [12] or to see the effect of double glazing on the performance of the solar still [13]. the use of a commercial refractor has improved the performance of solar stills and this has been proven experimentally [14, 15]. in solar distillers, the energy storage technique was used to increase productivity so that copper, stainless steel, mica, aluminum, sand and a black metallic plate of zinc were dipped into the water basin and increased the productivity of pure water between 19 and 45 % [16, 21]. the preheating by an external solar device such as solar collectors is a relatively complex process used in active mailto:cherrayeridha@yahoo.fr abder image placée ridha cherraye et al ijeca-issn: 2543-3717. june 2020 page 38 solar distillation [22, 26]. the aim of the present paper is to conduct an experimental study under the climatic conditions of south-east algeria for the solar still in active mode. to improve productivity, various operational techniques have proposed. ii. experimental investigations ii.1. solar still coupled with flat-plate collector . figure 1 shows the schematic diagram of a flat plate collector coupled to a single slope solar still. in figure 1 and 2 we see four identical stills that were made from different local materials in order to reduce cost and make construction easier. solar stills coupled with 3 different number of fpcs, namely single collector, two collectors and three collectors, collector inclination of 30° is fixed for all experiments there were four phases in the experiment: witness still, still with one fpc, still with two fpcs connected in series and still with 3 fpcs connected in series. for all of the four experiments, the following parameters are measured on 12 h basis: the parameters, outer glass temperature, inner glass temperature, vapour temperature, water temperature, ambient temperature, incident radiation on glass cover and collector/collectors, inlet and outlet temperatures of collector/collectors and distillate output for the active solar still, where mew is yield, l is latent heat, ag and ac are areas of glass cover and collector and i(t) and ic(t) are incident radiations on still and collector. figure .1. line diagram of an active solar still coupled with flat-plate collector iii. result and discussions iii.1. solar intensity, ambient temperature and wind speed we report in this study the comparative performance of a single basin active solar still with 30 condensing cover inclination with one fpc and two different numbers of fpcs connected in series and a single slope. the tilt angle and three different collector inclinations were fixed at 30° for the solar still (experimental result shows 30° was optimal inclination angle in winter at ouargla’s city). figure 3 shows the ambient temperature, wind speed and the varying intensity of solar for january the 18th and this day as is shown in the figure has the maximum irradiance (910 w.m-2) at 13:00 h, maximum wind speed (7.5 m.s-1) at 10:00h and maximum ambient temperature (20 °c) at 13:00h. figure 3 also shows that the minimum irradiance (245 w.m-2) at 09:00 h and 17:00 h, and minimum wind speed (2 m.s-1) at 09:00 h, 17:00h and 18:00h, and minimum ambient temperature (11 °c) at 09:00 h. these results show beyond reasonable doubt that ouargla has an attractive solar energy. ridha cherraye et al ijeca-issn: 2543-3717. june 2020 page 39 figure .3. solar intensity, ambient temperature and wind speed vs local time (18/01/2015) iii.2. hourly variation of productivity figure 4 shows that high productivity is achieved for the still coupled with 1fpcs in comparison to others to the 12h period. the distillation efficiency and the daily productivity are for the still coupled with three different fpc arrangements are shown in figure 6. the still with 1 fpc and 2 fpcs in series obtain respectively a maximum yield of 6.669 kg and 2.87 kg. the still with 3 fpc however has a productivity of 1.75 kg and 0.606 kg for witness solar still. ir becomes obvious that the still with single fpc gives more yield than fpcs connected in series. the cause of this is that the still with one fpc has an increased area for solar radiation; maintain low temperature of condensing cover for more time (less than 60°c). figure .4. hourly variation of productivity iii.2. average daily production for different configurations compared to the one with witness, the still with 1 fpc has a greater daily productivity by 1000%. in comparison to the one with a witness, the still with 3 fpcs in series has 300% less efficiency. the yield and still efficiency will increase with the increase in t which is a tendency that we can observe for the still with one fpc as well as for the still with 2 fpcs in series. however, the efficiency has decreased compared to other two cases, as the increase in area off sets the advantage of increase in yield for the still with 3 fpcs in series. nevertheless, the productivity is found to decrease for the still with 3 fpcs in series due to the increase in collector area and the distillation efficiency is optimum for the witness still compared to other arrangements as shown in figure 5. figure .5. the average daily production for different configurations iii.3. hourly variation of temperatures figure 6 shows the hourly water and condensing cover inside temperatures for still coupled with different numbers of fpcs in series. because of more added area with 3 fcps for solar radiation, maximum temperatures are obtained for the still with 3 fpcs connected in series when compared with witness, 2 fpcs and 1 fpc. there is significant increase for the still with 2 fpcs to 3 fpcs when there is water and condensing cover inside temperature because the local solar irradiation was very high during experimentation. abdelkader hima. et al ijeca-issn: 2543-3717. june 2020 page 40 figure .6. hourly variation of temperatures iv. conclusion  1 and 2 fpcs connected in series obtain more productivity compared to that with one fpc. consequently, to enhance the distillate yield the one fpc is found to be more suitable. the partial pressure difference between water temperature and condensing cover temperature is found to be high, which directly influences the yield.  the still with 2 fpc and 3 fpcs connected in series have distillation efficiencies of 6% and 3% respectively. the still with single fpc obtains a distillate efficiency of 17% and consequently the witness solar stills with produces the optimum (20%).  the still with single fpc obtains a maximum yield of 6.669 kg whereas the yield is 2.87 kg for the still with 2 fpcs in series and 1.75 kg for 3 fpcs respectively.  for the still with 2 and 3 fpcs in series has an average daily yield is 380% and 73% less respectively when compared to still with single fpc. for the still with 2 and 3 fpcs in series respectively,  when compared to that with single fpc the distillate efficiencies are 183% less and 466% less  to witness an increase in productivity it is not necessary to increase the number of collectors and to obtain the highest productivity there are several factors that must be studied. the study will be useful for designing efficient active solar distillation systems for the winter climatic conditions with 31.95°n, 5.4°e. acknowledgment for providing the experimental facilities, we are very thankful to dr. tekha mohammed member in the lenreza's lab teacher in the department of materials science, kasdi merbah ouargla university. algeria. ridha cherraye et al ijeca-issn: 2543-3717. june 2020 page 41 references [1] mehdi jahangiri, somayeh pahlavan, akbar alidadi shamsabadi, abderrahmane khechekhouche, "feasibility tstudy of solar water heaters in algeria", a review, journal of solar energy research, 2018. page 135-146. [2] a. khechekhouche, a. boukhari, z. driss, n.e. benhissen , "seasonal effect on solar distillation in the el-oued region of south-east algeria", international journal of energetica, vol 2, no 1, 2017. pp 42-45. [3] b. bouchekima, "solar desalination plant for small size use in remote arid areas of south algeria for the production of drinking water", desalination, 156 (2003) 353–354. [4] b. bouchekima, "a small solar desalination plant for the production of drinking water in remote arid areas of southern algeria", desalination, 159 (2003) 197–204. [5] b. bouchekima, "a solar desalination plant for domestic water needs in arid areas of south algeria", desalination, 153 (2003) 65–69. [6] abderrahmane khechekhouche, nabil elsharif, imad kermerchou, ali sadoun, "construction and performance evaluation of a conventional solar distiller", heritage and sustainable development, vol 1, no 2, 2019, pp. 74-77. [7] kishor kumar sadasivuni, hitesh panchal, chintan prajapati, f a essa, s shanmugan, naimish pandya, m suresh, mohammad israr, swapnil dharaskar, khechekhouche abderrahmane, "productivity enhancement of solar still with thermoelectric modules from groundwater to produce potable water: a review", groundwater for sustainable development, 2020. [8] abderrahmane khechekhouche, boubaker benhaoua, zied driss, mohammed el hadi attia, muthu manokar. "polluted groundwater treatment in southeastern algeria by solar distillation". algerian journal of environmental and sciences. vol 6, no 1, 2020. [9] kishor kumar sadasivuni, hitesh panchal, anuradha awasthi, mohammad israr, f.a. essa, s. shanmugan, m. suresh, v. priya, abderrahmane khechekhouche, “ground water treatment using solar radiationvaporization & condensation-techniques by solar desalination system”, international journal of ambient energy, 2020. doi: 10.1080/01430750.2020.1772872 [10] ridha cherraye, bachir bouchekima, djamel bechki, hamza bouguettaia, abderrahmane khechekhouche, "the effect of tilt angle on solar still productivity at different seasons in arid conditions-south algeria. international journal of ambient energy, (in press). 2020. [11] abderrahmane khechekhouche, zied driss, benjamin durakovic, "effect of heat flow via glazing on the productivity of a solar still", international journal of energetica, vol. 4, no 2, 2019, pp. 54-57. [12] a. khechekhouche, b. ben haoua, z. driss, "solar distillation between a simple and double-glazing", revue de mécanique. vol 2, n° 2. 2017. [13] abderrahmane khechekhouche, benhaoua boubaker, mruthu manokar, ravishankar sathyamurthy, abd elnaby kabeel. exploitation of an insulated air chamber as a glazed cover of a conventional solar still. heat transfer asian research. vol 48, issue 5, pp 1563-1574. doi:10.1002/htj.21446 [14] z.m. omara, a.e. kabeel, a.s. abdullah and f.a. essa, "experimental investigation of corrugated absorber solar still with wick and reflectors", desalination, vol 381, 2016, pp. 111–6. [15] abderrahmane khechekhouche, a.e. kabeel, b. benhaoua, mohammed el hadi attia, emad m.s. el-said, "traditional solar distiller improvement by a single external refractor under the climatic conditions of the el oued region, algeria", desalination and water treatment. vol 117, pp 23-28, 2020. [16] hitesh n. panchal, nikunj patel, "ansys cfd and experimental comparison of various parameters of a solar still", international journal of ambient energy, vol 39, 2018, pp. 551-557. [17] n. smakdji, a. kaabi, b. lips, "optimization and modeling of a solar still with heat storage", desalination and water treatment, vol 52, 2014, pp. 1761-1769. [18] a.e. kabeel, s.a. el-agouz, t. arunkumar and ravishankar sathyamurthy, " enhancing the performance of single slope solar still using jute cloth knitted with sand heat energy storage". twentieth international water technology conference, iwtc20. 2017. [19] abderrahmane khechekhouche, boubaker benhaoua, muthu manokar, ravishankar sathyamurthy, abd elnaby kabeel, zied driss, " sand dunes effect on the productivity of a single slope solar distiller", heat and mass transfer journal. spinger nature, vol 56, n° 4, pp 1117-1126, 2020. doi: 10.1007/s00231-019-02786-9 [20] sellami mohamed hassen,t. belkis, mohammed elamine ali ouar, s. d. meddour, hamza bouguettaia, khalid loudiyi, "improvement of solar still performance by covering absorber with blackened layers of sponge", groundwater for sustainable development, vol 5, 2017, pp. 111-117. [21] a. khechekhouche, b. benhaoua, a. e. kabeel, m. h. attia, w. m. el-maghlany, "improvement of solar distiller productivity by a black metallic plate of zinc as a thermal storage material", journal of testing and evaluation, vol 49, 2019. [22] ravishankar sathyamurthy, s.a.el agouz, p.k. nagarajanad, j. subramani, t.arunkumar, d.mageshbabu, b.madhu, r.bharathwaaj, n.prakash, "a review of integrating solar collectors to solar still", renewable and sustainable energy reviews, vol 77, 2017, pp. 10691097. [23] m. al-harahsheh, , m. abu-arabi, h. mousa and z. alzghoul, "solar desalination using solar still enhanced by https://doi.org/10.1080/01430750.2020.1772872 ridha cherraye et al ijeca-issn: 2543-3717. june 2020 page 42 external solar collector and pcm", applied thermal engineering, vol 128, 2018, pp.1030-1040. [24] abderrahmane khechekhouche, zied driss, boubaker benhaoua, mohammed el hadi attia, "cfd simulation of the solar distiller improvement (preheating), international conference on mechanics and energy (icme'17)", 2017, sousse, tunisia. [25] abderrahmane khechekhouche, imad kemerchou, ali sadoun, abderlkader hima, mokhtar ghoubdane, abderrahim allal, zied driss, "experimental investigation of a small solar water heater", international conference on mechanics and energy "icme'2019", 2019, tunisia. [26] v. r. raju, r. l. narayana, "effect of flat plate collectors in series on performance of active solar still for indian coastal climatic condition", journal of king saud university-engineering sciences, vol 30, no1, 2018, pp.78-85. i. introduction iii. result and discussions acknowledgment references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 25-31 ijeca-issn: 2543-3717. december 2020 page 25 engineering and economic evaluation of production of sno2 nanoparticles by microwave-assisted green synthesis annida salsabila, dea yuli nurfatonah, kitin sela selvian, putri kusuma wardhani, restia giantasya, yustinus sutantio lazuardi, and asep bayu dani nandiyanto * departemen pendidikan kimia, fakultas pendidikan matematika dan ilmu pengetahuan alam, universitas pendidikan indonesia jl. dr. setiabudi no. 229, bandung, 40154, jawa barat, indonesia email * : nandiyanto@upi.edu abstract – the synthesis of nanoparticles from noble metals such as tin (iv) oxide (sno2) is a research in progress with a very wide application in various fields, such as environmental improvement, gas sensors, catalysis, and lithium-ion batteries. the purpose of this study was to evaluate the economic feasibility of producing tin (iv) oxide (sno2) nanoparticles using the microwave-assisted green synthesis method on an industrial scale for 10 years by evaluating from an engineering and economic perspective. various economic parameters are used to analyze economic viability, including gross profit margin (gpm), payback period (pbp), cumulative net present value (cnpv), as well as economic variations in sales, taxes, raw materials, labor wages, and utilities to ascertain project viability. technical analysis to produce 8.54 kg of sno2 nanoparticles per day shows a total production cost of 1,982,243,613.12 idr and a total investment cost of 1,732,590,765.12 idr. the resulting gross profit margin is 39,231,578,268 idr/year, the profit is relatively economical, so this project can be run for 10 years under ideal conditions. this research is expected to be a reference for technical and economic analysis of industrial scale production of sno2 nanoparticles. keywords: sno2 nanoparticles, microwave-assisted green synthesis, economic evaluation, feasibility study. received: 01/010/2020 – accepted: 12/12/2020 i. introduction tin (iv) oxide nanoparticles (sno2 nps) are a group of metal oxides that have semiconductor properties. sno2 nps can be used as transparent electrodes for solar cells, liquid crystal displays, catalysts for methanol conversion, antistatic coatings, gas sensors, anodes for lithium-ion batteries, transistors, catalyst supports, nano and ultrafiltration membranes, and anti-corrosion coatings [1]. sno2 nps can be synthesized by various methods, including the sol-gel method [1,2], hydrothermal [3-5], coprecipitation [6-9], microwave-assisted [10-12], mechanochemical [13,14], green synthesis [15]. among these methods, the microwave-assisted green synthesis method is considered to have the highest efficiency, because the method is simple and more economical than other methods, produces minimum waste and is easy to handle, and does not use harmful oxidizing and reducing agents. the synthesized particles size of 27 nm, pure, and have spherical morphology. to evaluate the increase in production from small to large scale (industry), this study adopted the sno2 nps synthesis method with the microwave-assisted green synthesis method and changing the quantity of materials on a lab scale to an industrial scale [16]. there are also advantages of using a microwave, namely, the reaction takes place quickly [17] and the controlled high temperature in the microwave can increase the nucleation process during the synthesis of nanoparticles [18]. many raw materials for tin oxide also have been reported, such as tin chloride (e.g., sncl2 and sncl4) and tin fluoride [19]. annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 26 an economic evaluation of the chemical industry is a form of a quantitative assessment of what is expected and desired by the community to carry out the process of investing in a project. this evaluation analysis uses several parameters such as the number of sno2 nps produced per day, total equipment costs, total production cost, total investment cost, calculating gross profit margin (gpm) as the first analysis to determine the level of profitability of a project; calculating payback period (pbp) to predict the length of time it takes for an investment to be able to return the initial total expenditure; cumulative net present value (cnpv) to predict the condition of the project as a function of the production year or it can be obtained as the number of cumulative financial flows each year [20] also as well as several economic variations on sales, taxes, raw materials, salary labor, and utilities will be discussed and analyzed to support the economics analysis. the purpose of this study was to determine the feasibility of the project for making sno2 nanoparticles using the microwave-assisted green synthesis method by conducting technical and economic evaluations. this is because there are no articles that discuss the technical and economic evaluation of the synthesis of sno2 nps. ii. research method ii.1. theoretical synthesis of sno2 nanoparticles figure 1 shows the stages of the sno2 nps synthesis scheme using microwave-assisted green synthesis and andrographis paniculata leaf extract as a chelating agent. the method of synthesis of sno2 nps was adopted from research conducted by [16]. the synthesis of sno2 nps was initiated by dissolving 14.10 kg of sncl2.2h2o with 68 l of water. andrographis paniculata leaf extract was prepared by heating 2.50 kg of leaves with 50 l of water at 80c for 2 hours. the result of heating the leaf extract is filtered to separate the extract from the residue. the leaf extract is then mixed with sncl2 solution and stirred for 2 hours until a clear solution is formed which indicates the formation of sno nps. the formed sno nps were separated and washed with deionized water by centrifugation method. the final product was microwave-dried at 180c for 3 hours. calcination was carried out at 673 k for 6 hours to obtain sno2 nps. figure 1. synthesis scheme of sno2 nps ii.2. technical perspective the engineering perspective is based on the synthesis process of sno2 nps as shown in figure 1. the flow diagram of the process for making sno2 nps is shown in figure 2. several assumptions are made to synthesize sno2 nps on a large scale (industry) and are based on stoichiometric calculations and mass balance.  the synthesis process is carried out using the microwave-assisted green synthesis method.  all materials used in the synthesis reaction of sno2 nps such as double distilled water, sncl2.2h2o, andrographis paniculata leaves have high purity and are enlarged 500 times as calculated based on the literature from [16].  the formation of sno2 is assumed to be a complete reaction.  the residence time of the substance in the filter is 1.5 hours.  the stirring temperature for leaf extraction is 90c while for mixing it is 25c with a residence time of 2 hours.  the centrifugation process is carried out for 1.5 hours.  the microwave temperature used is 180c with a residence time of 3 hours. annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 27  the furnace temperature used is 674 k with a residence time of 6 hours.  assuming a loss of 5% in any mechanical process. figure 1. flowchart of the synthesis process for the production of sno2 nps ii.3. economic evaluation in this economic evaluation, the data of price in the analysis were obtained from an online shop called www.tokopedia.com, www.alibaba.com, and www.sigmaaldrich.com. the data processing in this economic evaluation analysis is processed mathematically using the microsoft excel application. the economic evaluation process in a factory is carried out based on the following parameters:  total investment cost (tic) total investment cost (tic) is capital or initial cost that must be provided at the beginning of production. tic is usually calculated based on the total factory cost (total purchasement cost (tpc)) [21]. simply put, tic is the cost to build a factory and initial costs (equipment and service costs related to equipment for equipment agencies in the factory) [22].  gross profit margin (gpm) gross profit margin (gpm) is the first analysis to determine the level of profitability of a project. this analysis is estimated by subtracting the cost of products sold (revenue) from the cost of raw materials [23]. gpm is also used to measure the efficiency of companies using materials and labor to produce and sell products so that they can make a profit [21].  payback period (pbp) payback period (pbp) or fund back is a calculation done to predict the length of time it will take for an investment to return the total initial outlay. pbp is calculated when cnpv is at zero for the first time [23].  net present value (npv) net present value (npv) is the value obtained from a project which represents expenses and income. the npv calculation must consider the opportunity cost of social capital (as a discount rate) [21]. on the other hand, npv can also be used to estimate the expected financial flows in the future [24].  cumulative net present value (cnpv) cumulative net present value (cnpv) is the calculation of the total npv value from the beginning of factory construction to the end of factory operations. cnpv can be obtained as the amount of cumulative financial flows each year [21]. in addition, cnpv also calculates land and final depreciation, as well as the value of the savings (final depreciation value) [24]. in determining the economic analysis, there are several assumptions that may occur during the project, including: • calculations on economic evaluation analyse using the idr currency. • based on prices sold commercially, the price of andrographis paniculata leaves is 53,000.00 idr/ kg and the sncl2.2h2o price is 142,148.40 idr/ kg. as for deionized water, it is obtained from water treatment that is processed in a factory using a water purifier and assumes that the factory is close to a water source. • equipment prices are determined based on commercially available prices with a total equipment purchase cost of 499,305,696.00 idr. • electricity costs are assumed to be 1,444.70 idr/ kwh. • one cycle of the synthesis process of sno2 takes four hours. • the project runs 25 days / month or in one year is 300 days. • the total labor during processing is 50 people with a per worker of 3,100,000.00 idr/month. • income tax 10%. • sales discount rate of 15%. • the project duration is 10 years. iii. result and discussion iii.1. theoretical synthesis of sno2 nanoparticles the synthesis of sno2 nps based on the assumptions of an engineering perspective, allows them to be produced on a large scale with the help of commercially available equipment. the reaction mechanism that occurs is as follows [25]. annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 28 furthermore, by calculating the processing cycle/year, the suggested scheme is prospective to produces 8.54 kg of sno2 nps per day. meanwhile, the raw materials used were as follows: 2.50 kg of andrographis paniculata leaves and 14.10 kg of sncl2.2h2o. the total cost incurred by the production process/year is 641,037,732.00 idr. total sales/year were obtained for 39,872,616,000.00 idr, gross profit margin/year for 32,768,518,317 idr. iii.2. ideal condition figure 3 shows a graph of the relationship between cnpv/tic and time. the x axis is the year and the y axis is cpnv/tic. the graph shows a decrease in income, namely in 1st to 2nd year, caused by initial capital expenditures for the purchase of equipment needed during the nanoparticle production process as well as for land purchase costs. in that year the factory had not yet produced nanoparticles. in the 3rd year, there is an increase in income, this condition is called the payback period (pbp). this increase in revenue because the factory has produced nanoparticles and is sold, it can cover the initial capital used for equipment purchases and land purchase costs. the profit earned continues to increase until the 10th year. thus, the production of nanoparticles is a very profitable project because this project takes only 2 years for initial capital. figure 3. graph of ideal condition of cnpv/tic as long as ten years iii.3. variation of sales figure 4 shows a cnpv chart with various sales variations over 10th years. the analysis was carried out by increasing and decreasing sales by 10 and 20%. the ideal sale is 100%, when sales are decreased by 10 and 20%, the sales are 90 and 80%, respectively. when sales are increased by 10 and 20%, sales are 110 and 120%. from figure 4, sales with various variations have the same value at the beginning of the project development (from 1st to 2nd year). after the project was created (in 3rd year) there was a sales effect on cnpv. the greater the sales value, the higher the profit for the project being undertaken. but if there are conditions that cause product sales to decline, then the project profits are reduced from the ideal state. profits continue to increase after reaching the pbp point until the 10th year. when sales are reduced by 20% from ideal conditions, the gap in profits generated for each year will be less. conversely, the distance between the profits generated from each year increases with an increase in sales from ideal conditions. the cnpv/tic values in the 10th year for each variation of 80, 90, 100, 110 and 120% were 42.575; 49,602; 56,630; 63,658 and 70,685%. from the variation of sales, the project can still run and make a profit. figure 4. graph of cnpv/tic as long as ten years with variation of sales iii.4. variation of tax tax is another levy imposed on projects by the state and is an external factor that can affect the success of a project. figure 5. in 1st and 2nd year shows the initial conditions of the project. the initial condition of the project in the graph has decreased because in the first and second years there was no income tax expense and in that year there was a factory construction, so the graph was the same as the ideal graphic conditions. the variation of taxes in the 3rd to 10th year is increasing, this is very influential on this project. the cnpv/tic values obtained in the 10th year with tax variations of 80, 90, 100, 110, and 120% were 56,630; 47.0623; 31,116; 28,0260; 24.9359%. the higher the tax that must be issued, the return on the initial investment will be longer than ideal conditions. the higher the tax issued, the annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 29 smaller or less profitable the profitability of nanoparticle production is. from the graph of cnpv/tic, the higher the tax that must be issued each year, the lower the profitability will be. figure 5. graph of cnpv/tic as long as ten years with variation of tax iii.5. variation of raw material the success factor of a project can be influenced by the condition of the raw materials. graph of cnpv against time with variations in the raw material is shown in figure 6. the analysis was carried out by decreasing and increasing the ideal raw material (represented by 100%) by 10 and 20%. when the raw material is reduced by 10 and 20%, the raw material becomes 90 and 80%, respectively. when the raw material is increased by 10 and 20% the raw material becomes 100 and 120%, respectively. in the 1st to 2nd year indicate the initial conditions of the project. the initial conditions of the project on the cpnv chart under the variation of raw materials have the same cnpv/tic (%) value and have decreased due to project development. variations in raw materials will affect the project in 3rd to 10th year, this is indicated by the value of cnpv/tic (%) which will increase starting in 3rd year for each variation. the cnpv/tic (%) values obtained did not show any significant difference except for the 120% variation which had very different values and had curves under ideal conditions. from figure 6, it can be concluded that the higher the conditions for the variation of raw materials, the lower the cnpv/tic value will be and it will lead to the formation of curves under ideal conditions. in the 10th year with variations of 80, 90, 100, 110, and 120% the cnpv/tic values were 56.856; 56.743; 56.630; 56.517; 56.517%. from the variety of raw materials, the project can still run and get profit. furthermore, the profit will continue to increase after reaching the pbp point until the 10th year. figure 6. graph of cnpv/tic as long as ten years with variation of raw material iii.6. variation of sales labor the labor factor can also affect the success of a project. graph of cnpv against time with labor variation is shown in figure 7. the analysis was carried out by reducing and increasing the salary of labor in ideal conditions (represented by 100%) by 10 and 20%. when the salary is reduced by 10 and 20%, it will be 90 and 80% respectively. when the salary is increased by 10 and 20%, it becomes 100 and 120% respectively. in the 1st to 2nd year indicate the initial conditions of the project. the initial project conditions on the cpnv chart under the labor variation have the same cnpv/tic (%) value and have decreased due to project development. the labor variation will have an effect on the project in 3rd to 10th year, this is indicated by the value of cnpv / tic (%) which will increase starting in 3rd year for each variation. in the 10th year with variations of 80, 90, 100, 110, and 120% the cnpv / tic values were 57.286; 56.958; 56.630; 56.302; 55.974%. from the variation of labor, the project can take place and generate a profit. furthermore, the profit will continue to increase after reaching the pbp point until the 10th year. figure 7. graph of cnpv/tic as long as ten years with variation of salary labor annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 30 iii.7. variation of utility the success of a project can also be affected by the utility. the graph of cnpv against time with utility variations is shown in figure 8. the analysis was carried out by decreasing and increasing the utility in an ideal state (represented by 100%) by 10 and 20%. when the utility is reduced by 10 and 20%, the utility becomes 90 and 80% respectively. when it is increased by 10 and 20% the utility becomes 100 and 120% respectively. in the 1st to 2nd year indicate the initial conditions of the project. the initial project conditions on the cpnv chart under the variation of utility have the same cnpv/tic (%) value and have decreased due to project development. the variation in utility will affect the project in 3rd to 10th year, this is indicated by the value of cnpv/tic (%) which will increase starting in the third year for each variation. the cnpv/tic (%) values obtained did not have a significant change. in the 10th year with variations of 80, 90, 100, 110, and 120% the cnpv/tic values were 56.692 respectively; 56.661; 56.630; 56.599; 56.568%. from the variation of utility, the project can take place and generate a profit. furthermore, the profit will continue to increase after reaching the pbp point until the 10th year. figure 8. graph of cnpv/tic as long as ten years with variation of utility iv. conclusion based on the above analysis, the sno2 nps production project using the microwave-assisted green synthesis method is a prospective production project from an engineering and economic perspective. this analysis is obtained from an economic evaluation using several parameters which state that the sno2 nps manufacturing project is very profitable and the payback period is short for the initial investment. income taxes, raw material costs, labor costs, and sales greatly affect project profitability. from this economic evaluation analysis, it can be concluded that this project is feasible to run. acknowledgements we would like to thank the universitas pendidikan indonesia for supporting the writing of this paper. references [1] j. zhang, l. gao, “synthesis and characterization of nanocrystalline tin oxide by sol–gel method”. journal of chemistry letter, vol. 177, 2004, pp. 1425-1430. [2] a. madzlan, s.a. saad, r.w.b. wan, “size-controlled synthesis of sno2 nanoparticles by sol–gel method”. journal of material letters, vol. 91, 2002, pp. 31-34. [3] a. anarki, a.r. mahjoub, a.a. khodadadi, “preparation of sno2 nanoparticles and nanorods by using a hydrothermal method at low temperature”. the journal of physical chemistry c. 2007, pp. 111. [4] h. chiu, c. yeh, “hydrothermal synthesis of sno2 nanoparticles and their gas-sensing of alcohol”. phys. chem c, vol. 111, 2007, pp. 7256-7259. [5] f. du, z. guo, g. li, “hydrothermal synthesis of sno2 hollow microspheres”. materials letters, vol. 59, 2005, pp. 2663-2565. [6] h. yang, x. song, x. zhang, w. ao, g. qiu, “synthesis of vanadium-doped sno2 nanoparticles by chemical co-precipitation method”. materials letters, vol. 57, 2002, pp. 3124–3127. [7] s.l. yuan, z.m. tian, j.h. he, p. li, s.q. zhang, c.h. wang, y.q. wang, s.y. yin, l. liu, “structure and magnetic properties in mn doped sno2 nanoparticles synthesized by chemical co-precipitation method”. journal of alloys and compounds, vol. 466, 2008, pp. 26–30. [8] c.a. ibarguen, a. mosquera, r. parra, m. s. castro, j. e.r. pae, “synthesis of sno2 nanoparticles through the controlled precipitation route”. materials chemistry and physics, vol. 101, 2007, pp. 433–440. [9] l.m. nejati, a.e.b. karimabad, m.s. niasari, h. safardoust, “synthesis and characterization of sno2 nanostructures prepared by a facile”. jns, 2006, pp. 547-53. [10] t. krishnakumar, r. jayaprakash, m. parthibavarman, a.r. phani, v.n. singh, b.r. mehta, “microwaveassisted synthesis and investigation of sno2 nanoparticles. materials letters, vol. 63, 2009, pp. 896. [11] c. thenmozhi, v. manivannan, e. kumar, s.v.r. murugan, “synthesis and characterization of sno2 nanoparticles by microwave-assisted solution method”. international journal of current research, vol. 7, 20015, pp. 23162-23166. [12] m. parthibavarman, v. hariharan, c. sekar, “highsensitivity humidity sensor based on sno2 nanoparticles synthesized by microwave irradiation method”. materials science and engineering, vol. 31, 2011, pp. 840–844. [13] l.m. cukrov, t. tsuzuki, p.g. mccormick, “sno2 nanoparticles prepared by mechanochemical annida salsabila et al ijeca-issn: 2543-3717. december 2020 page 31 processing”. scripta mater, vol. 44, 2001, pp. 1787– 1790. [14] u. kersen, m.r. sundberg. “the reactive surface sites and the h2s sensing potential for the sno2 produced by a mechanochemical milling”. journal of the electrochemical society, vol. 150, 2003, pp. h129h134. [15] g. elango, s.m. kumaran, s.s. kumar, s. muthuraja, s.m. roopan, “green synthesis of sno2 nanoparticles and its photocatalytic activity of phenolsulfonphthalein dye”. spectrochimica acta part a: molecular and biomolecular spectroscopy, vol. 145, 2015, pp. 176– 180. [16] k. karthik, v. revathi, t. tatarchuk, “microwaveassisted green synthesis of sno2 nanoparticles and their optical and photocatalytic properties”. molecular crystals and liquid crystals, vol. 671, 2018, pp. 17– 23. [17] m.a. surati, s. jauhari, k.r. desai, “a brief review: microwave assisted organic reaction”. scholars research library archives of applied science research, vol. 4, 2012, pp. 645-661. [18] g.a. kahrilas, l.m. wally, s.j. fredrick, m. hiskey, a.l. prieto, j.e. owens, “microwave-assisted green synthesis of silver nanoparticles using orange peel extract”. acs sustainable chemistry engineering, vol. 2, 2014, pp. 367–376. [19] a. b. d. nandiyanto, t. a. aziz, & r. fariansyah. engineering and economic analysis of the synthesis of fluoride tin oxide film production. international journal of energetica, vol. 2, issue 2, 2017, pp. 15-17. [20] f. nantamandini, s. karina, a. b. d. nandiyanto, & r. ragaditha. feasibility study based on economic perspective of cobalt nanoparticle synthesis with chemical reduction method. international journal of energetica, vol. 4, issue i, 2019, pp. 17-22. [21] a.b.d. nandiyanto, r. ragadhita, “evaluasi ekonomi perancangan pabrik kimia”, bandung, rumah publikasi indonesia, 2019. [22] s. frioui, r. oumeddour, “investment and production costs of desalination plant by semi-empirical method”. desalination, vol. 223, 2008, pp. 457-463. [23] d.e. garret, “chemical engineering economics”, new york, spinger science and bussines media, 2012. [24] d. brennan, k. golonka, “new factors for capital cost estimation in evolving process designs”. chemical engineering research and design, vol. 80, 2002, pp. 576-586. [25] c. ma, g. hong, s. lee, “facile synthesis of tin dioxide nanoparticles for photocatalytic degradation of congo red dye in aqueous solution”. catalysts, vol. 10, 2020, pp. 792. ijeca-issn: 2543-3717. june 2021 page 34 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 34-38 parametric study of the effective parameters on the performance of solar chimney power plant hadda nouar 1* , abdelghani azizi 2 , younes chiba 3 , toufik tahri 1 1 electro technology and renewable energies department, university of hassiba ben bouali, chlef, algeria 2 department of renewable energies, ouargla, university of kasdi merbah ouargla, algeria 3 department of mechanical engineering, university of yahia fares, medea, algeria email *: h.nouar@univ-chlef.dz abs tract –the solar chimney power plant (scpp) is an effective option for electrical energy production from solar energy. in this paper, a numerical model to predict the scpp performance is developed. the effects o f collector angle and solar radiation are investigated on the parameters of air as the velocity and temperature. the study shows that when the collector angle is 20°, the velocity maximum is 1.8 m/s at the chimney base and the maximum temperature is 332.1k . in addition, increased solar radiation produces an increase in temperature (from 400 w/m² to 900 w/m²) and air velocity (from 22.25 m/s to 2.75 m/s) in the solar energy tower keywords: velocity, solar chimney power plant, energy tower, solar energy, electrical energy. received: 25/04/2021 – accepted: 25/06/2021 i. introduction solar ch imney power p lant is a renewable energy center with the potential to generate important quantities of electrica l energy [1], wh ich are a therma l system that creates electrical energy using both the effect of buoyancy of hot air and effect of chimney [2]. a solar chimney power plant is made up of three ma in ele ments: the solar collector, the solar tower and the turbine. the collector angle is one of principa l parameters in the enhancement of electricity production [3]. the solar ch imney power p lant is used in hot areas with high intensity of solar radiat ion. its operating principle is based on the fact that hot air, be ing lighter than cold air, rises. the hot air is produced by the greenhouse effect in the collector wh ich can spread horizontally for several tens of meters on the surface of the ground. the tower (chimney) converts the heat flow captured by the collector into kinetic energy (convection current) and potential energy (pressure drop in the turbine), thus the diffe rence in a ir density caused by the temperature rise in the collector acts as a driving fo rce. the movement of air a llows turbines at the base of the chimney to generate electricity through generators coupled to them [4-5]. 3d nume rical model was developed to analyze the flow para meters such as temperature, veloc ity of solar updraft tour (sut ) and pressure also the influence of geometrica l para meters such as chimney height and the roof collector. it was observed that when the collector roof angle increased, air ve locity a lso increased whereas the air te mperature decreased slightly [6]. in another work, 3d nu me rica l model developed to analyze the influence of solar flu x, the divergence angle of the chimney and turbine effic iency on the performance of sut p lant [7]. the influences of roughness shape of collector were investigated on the performance of scpp. in their study, curved, the roughness shape of triangular and square grooves were studied and compared with the smooth case. in the authors erected a scpp inside the university campus, with 1m collector radius, 0.2 m chimney dia meter while the height was varied fro m 2 m to 4 m. the results revealed that the chimney height of 4 m and the collector inlet height of 0.04 m produced the optimal configuration [8]. based on the buoyancy phenomenon, the power production from the gas of the power plant's chimney using the combination of the power p lant's hot output with ambient air was investigated and modeled at http://www.ijeca.info/ http://www.ijeca.info/ mailto:h.nouar@univ-chlef.dz hadda nouar et al ijeca-issn: 2543-3717. page 35 temperatures and different discharge rates of the power plant's hot output on a pilot scale [9]. the authors proposed in a new chimney design of hyperbolic shape [10]. the design of chimney is enhanced by exa mining the effect of the divergence radius of the chimney on the performance of scpp using a 2d cfd mode l. in another work [11], a novel collector design with double-pass counter flow mode was proposed to enhance further the scpp effic iency and reduce the large p lant area. the authors compared three collector models including double-pass collector with para lle l flow, double-pass collector with counter flo w and conventional collector by using cfd model. small-scale prototype of scpp was designed and built at the un iversity of ouargla , a lgeria [12]. in the study of a small-scale prototype of scpp was designed and built at the university of ouargla, algeria. it was found that the velocities of air at the chimney base are in a good accord with those estimated fro m the cfd method. the ma ximu m a ir veloc ity in the chimney achieved was 1.6 m/s and the predicted generated power reached 104 kw. a novel concept consists of a horizontal solar chimney power plant with an adapted collector entrance, named sloped collector entrance scescpp. the results indicate that the new collector entrance design affects significantly the system performance [13]. in this paper, a nu merical model was presented to simu late the solar chimney for the iranian plant and the scpp performance is studied. the effect of collector angle and heat flu x on the a ir te mperature and velocity o f air was investigated. ii. methodology in the solar ch imney, the incident solar radiation will heat the air flowing inside the collector of the solar chimney by convection, causing the air te mperature to rise by the phenomenon of the greenhouse effect under the transparent roof wh ich acts main ly on the flow of heat absorbed not to leave the structure of the collector. and due to the temperature differences between the temperature at the base of the solar chimney and the temperature of the atmosphere, air is continuously drawn in through the periphery of the open collector in the chimney due to the buoyancy effect. a turbine is placed at the base of the chimney through which the hot air passes to convert part of the useful energy of the c ircu lating a ir into electricity [14]. 2d nume rica l solution of solar chimney power plant (scpp) as shown in figure 1, is developed according to the dimension of iranian prototype (table 1) [15]. scpp is simulated by com sol mu ltiphysics, simulations are used by solving rans equations to predict the output of scpp output. table 1. geometric p arameters of the scpp p arameter value[m] collector op ening height 0.15 diameter of chimney 0.25 diameter of collector 10 chimney height 12 figure 1. diagram schemat ic of solar chimney power plant ii. 1 mesh creation do main grid is important phase in the cfd ana lysis. in this simulation, a triangular mesh in figure 2 is created using the meshing tool comsol, it consist of 11477 ele ments with more concentrating ele ment density on the inlet, outlet and junction regions. figure 2. t he meshing of t he scp p syst em hadda nouar et al ijeca-issn: 2543-3717.  k page 36 ii. 2 governing equation based on rayleigh’s number the air flow type is determined and it is evaluated as: t able 2. boundary conditions gth 3  r  col a  (1) where hcol , ∆t, g, α and μ are collector height and diffe rence of te mperature in the system, gravity, thermal diffusivity and kinematic viscosity respectively. pr and gr indicate prandt number and grashof number, respectively. rayle igh number is more than 10 9 , so air flow in the system is considered as turbulent. the problem is governed by the conservation of mo mentu m, energy and mass equations is given as follows: continuity equation: iii. results and discussion iii. 1 impact of solar radiation on temperature and air velocity figure 3 d isplays impact of angle of collector roof on the air velocity. it is found that the variation of collector angle fro m15°-30° has an considerable e ffect on the velocity of air, when the velocity air augment (from 1.5   .()  0 t momentum equation: (2) m/s to 1.8 m/s) with the increasing of collector angle (fro m 15° to 20°), after this angle the a ir velocity decreases (1.8 m/s to 1.5 m/s) by increasing collector  u  (u.)  .[pi  (   )(  (u) t )  2 (   )(.u)i  2 ki] f angle (from 20° to 30°). t t energy equation: 3 t 3 (3) c t  c u.t  .(kt )  q  q w (4) p t p vh p where f, u, p and  are volume forces , radial velocity, pressure and density respectively. the dissipation rate and kinetic turbulence energy are obtained as: k equation:  k  (u.)k  .[(   t )k]  p     (5) t k s equation:           t       2 (6) t (u. ) .[( 3 2 ) ] c  1 p k  c  2 k figure 3. variat ion of air velocity for different collector angle 3 k wh ere   c  4 l t is the energy dissipation and figure 4 illustrates effect of angle collector roof on t   k 2 c   is the turbulent viscosity. temperature of air. it is found that the air temperature augment significantly (from 324.7k to 332.1k) with  k  1, c  0.09 , c1  1.44 c 2  1.92 and   1.3 . p k indicate to the generation of kinetic turbulent energy due by mean gradients of velocity, is calculated by: p   [u : (u  (u) t )  2 (.u) 2 ]  2 k.u (7) higher collector angle (fro m 15° to 20°) and declines significantly a fter a certa in point (fro m 20° to 30°). fro m these results, it can be concluded that the appropriate collector angle is 20°. k t 3 3 ii.3 boundary condition the main boundary conditions for the studied scpp are indicated in table 2. 1.8 1.75 1.7 1.65 1.6 1.55 1.5 15° 20° collector angle(°) °25 °30 a ir v e lo c it y (m / s )  k surface t ype value inlet collector p ressure inlet pci = 101325 pa, t = tam = 300𝐾 out let of chimney p ressure out let p =101325 pa surface of collect or semi-t ransparent wall solar irradiat ion; h=10.45 w/𝑚2 chimney wall adiabat ic q=0 w/𝑚2 hadda nouar et al ijeca-issn: 2543-3717. page 37 figure 4. variat ion of t emperature of air for different collector angle figure 5 illustrate the distribution of velocity of air and temperature for appropriate collector angle is 20°, on the left figure we show that the min imu m values of the temperature a re located at the entrance of the collector then it increases progressively to ma ximu m value in the collector center. on the right figure we show that the velocity magnitude is very wea k at the entrance of the co llector then increases gradually to outlet of the collector; it then reaches its maximu m value in the chimney base. figure 5. velocit y and t emperature contours at collector angle is 20° iii. 2 effect of solar radiation on temperature air and velocity the roof angle is 20° and the same temperature conditions and varies solar radiation such as 400w/ m² to 900 w/m². figure 6 and 7 show the effect of solar radiation on temperature o f a ir and veloc ity. as the solar radiation augment at 900 w/m² both the temp erature and the velocity rise reaches a maximu m value of 325 k and 2.7 m/s resp ectively . from these results, it is clear that the solar radiat ion has significant effect on both air velocity and temperature. figure 6. effect of solar radiation on air velocity figure 7. effect of solar radiation on temperature iv . conclusion nu merical modeling on the performance of scpp using two-dimensional (2d) energy and navie r-stokes equation was presented. the airflow is turbulent and simu lated with k-epsilon model, using comsol multiphysics . according to simulat ions, we can conclude the following:  the angle of the co llector roof has a considerable effect on both the velocity distribution and temperature in the scpp when collector angle is 20°, while the ma ximu m veloc ity is 1.81 m/s and the maximu m temperature is 332.1 k.  the increasing of the solar radiation increases the air temperature (fro m 315 k to 224.5 k) and velocity in the solar chimney (from 2.25 m/s to 2.75 m/s ). 332 330 328 326 324 322 15° °20 °25 °30 collector angle(°) 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 400 500 600 700 800 900 solar radiation(w/m²) 325 324 323 322 321 320 319 318 317 316 500 600 700 solar radiation (w / m²) 800 900 te m pe ra tu re (k ) a ir t e m p e r a t u r e (k ) v e lo c it y (m / s ) hadda nouar et al ijeca-issn: 2543-3717. page 38 references [1] h. hoseini, and r. m ehdip our," evaluation of solar chimney p ower p lants with multip le-angle collectors", journal of comp utational & app lied research in m echanical en gin eerin g (jcarm e), vol. 8, no 1, 2018, p p . 85-96. [2] f.n. elwekeel, a.m . abdala, and .m . rahman, " effects of novel co llector roof on solar chimney p ower p lant p erformance", journal of solar en er gy engineerin g, vo l. 141, no 3, october 2019, p p . 1-27. [3] s. deh ghan i, and a.h. m ohammadi, "op timum dimension of geo metric p arameters of solar chimney p ower p lants – a multi-objective op timization app roach", solar energy vol. 105, july 2014, p p . 603-612. [4] h.y. jeffrey and c.s.n. azwadi. "a brief review on solar up draft p ower p lant", journal of advanced r eview on scientific research, vol.18, no 1, 2016, p p . 1-25. [5] a. m azdak , s. m ekhilef, k. salim newaz, b. horan, and m . sey edmahmoudian, n. akram, a. stojcevski, " solar chimney p ower p lant and its correlation with ambient wind effect", journal of thermal analy sis and calorimetry , vol. 141, no 2, 2020, p p . 649-668. [6] p . das, and v.p . chandramohan,” effect of chimney height and collect or roof angle on flow paramet ers of solar updraft tower (sut) plant ,” journal of thermal analysis and calorimetry, vol. 136, no 1, 2019, pp. 133-145. [7] p . das, and v.p . chandramohan,”3d numerical st udy on est imat ing flow and performance paramet ers of solar updraft tower (sut ) plant : impact of divergent angle of chimney, ambient t emperat ure, solar flux and t urbine efficiency”, journal of cleaner p roduction, vol. 256, 2020, pp. 120353. [8] e.a.a. elkady, m.a. halawa, m. mohamed, and m.a. younes, “an invest igat ion on a solar chimney model,” journal of al azhar university engineering sector, vol. 14, no 51, 2019, pp. 485-494. [9] s.m. shahdost , f.r. ast araei, a. ebrahimi‐moghadam, and m.h. ahmadi, “ experiment al and numerical invest igat ions of a novel chimney syst em for power generat ion using t he combinat ion of fossil fuel power plant exhaust gases and ambient air,” energy science & engineering, vol. 7, no 3, 2019, pp. 764-776. [10] h. nasraoui, z. driss, a. ayedi, and h. kchaou, “ numerical and experiment al st udy of the aerothermal charact erist ics in solar chimney power plant wit h hyperbolic chimney shape”. arabian journal for science and engineering, vol. 44, no 9, 2019, pp. 7491-7504. [11] h. nasraoui, z. driss, and h. kchaou, ”novel collector design for enhancing the performance of solar chimney power plant ,” renewable energy, vol. 145, 2020, pp. 1658-1671. [12] a. azizi, t. t ahri, m.h. sellami, l. segni, r. belakroum, and k. loudiyi, ”experiment al and cfd invest igat ion of small-scale solar chimney for power generat ion. case st udy: southeast of algeria,” desalinat ion and wat er treatment , vol. 160, 2019, pp. 1-8. [13] h. kebabsa, m.s. lounici, m. lebbi, and a. daimallah, “thermo-hydrodynamic behavior of an innovat ive solar chimney,” renewable energy, vol. 145, 2020, pp. 2074-2020. [14] e. cuce, a. saxena, p.m. cuce, h. sen, s. guo, and k. sudhakar, "p erformance assessment of solar chimney power plant s wit h t he impacts of divergent and convergent chimney geomet ry", int ernat ional journal of low-carbon technologies, 2021, pp. 1-11. [15] s. amirkhani, s. nasirivatan, a.b. kasaeian, and a. hajinezhad, "ann and anfis models to predict the performance of solar chimney power plant s", renewable energy, vol. 83, 2015, pp. 597-607. https://link.springer.com/journal/10973 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 44-51 ijeca-issn: 2543-3717. december 2021 page 44 modeling and power control of 5th and 3rd order model for dfig applied of wind conversion system m. atallah 1* , a. mezouar 1 , kh. belgacem 1 , y. saidi 1 , m. a. benmahdjoub 1, 2 1 laboratory of electro-technical engineering, faculty of technology tahar moulay university of saïda (20000), algeria 2 laboratory of electrical energy-eelab, faculty of engineering and architecture, ghent university, sint-pieters-nieuwstraat 41, 9000, ghent, belgium email *: meddah.atallah@univ.saida.dz abstract – in this study, a comparison between the fifth-order model and the third-order model of the doubly fed induction generator (dfig) is presented. this paper aims to study and analyze transient stability for the fifth-order and third-order models. the fifth-order model of the dfig is based on five differentials equations. neglecting the stator transients from the fifth-order model of the dfig, we get the third-order. on startup and control of the power system that the third-order model produces better results than the fifth-order model in the transient regime. the performance of the two models on the startup and control of the power system is proved with the simulations (matlab/simulink® software). keywords: dfig, transient stability, wind energy, vector control. received: 27/09/2021 – accepted: 30/11/2021 i. introduction recently, renewable energy sources (res) are a natural alternative to conventional power generation. among all ress, wind power is the most promising and the fastest-growing. in this context, the electrical machines are generally divided into two groups: synchronous generators and induction generators. in induction generators, the dfigs are used more than squirrel cage induction generators. the advantage of the dfig is that the power transited by both converters, rotor side and grid side, is  30% of the total power supplied by the dfig stator [1, 2]. on the other hand, the switching losses are lower, the manufacturing cost of the transformer is lower and the size of the passive filters is reduced, which implies a reduction in costs and additional losses. in addition, the possibility of control the active and reactive power of the dfig stator, the reduction of stresses on the mechanical structure during the variation of wind speed, and the increase in the operating range, especially for low wind speeds where the maximum power can be easily converted [3]. generally, the fifth-order model representation of the dfig is more to use. the fifth-order model consists of five differential equations, representing the state variables of the stator, rotor, and generator speed. although the fifth-order model is considered the most accurate, it has some problems [4]. among these problems, the fifth-order model undoubtedly complicates the simulation model and represents a very long simulation time when dealing with a large wind farm. in addition, the fifth-order model of the dfig is not suitable for transient stability studies because the interface with the voltage and current phases of the power system is not easily implemented [5]. the alternative to the fifth-order model in the study and analysis of the transient stability, including the wind farm, is the reduced-order models, which lower the computational requirements. among all the reducedorder models, the third-order model is most used in wind energy applications [6, 7]. to obtain the third-order model, it is necessary to neglect the derivatives of stator flux linkages, which appear in the fifth-order model in park's equations. the theoretical explanation of neglecting electrical transients is proposed in [8, 9]. in [10], proposed a theoretical study and comparison between https://www.ijeca.info/ m. atallah et al ijeca-issn: 2543-3717. december 2021 page 45 three reduced-order models of induction machines. in [11], the authors presented a comparison between a fifthorder model and a third-order model of the dfig in wind turbine applications. for the integration of the third-order model in the power system, we must neglect grid transients so that we have a coherent set of equations. an overview of various dynamic models of induction machines is presented in [12]. a simplified dfig model for the representation of positive sequence and negative sequence components in wind energy conversion systems is proposed in [4]. in this context, several control schemes for dfig have been proposed and developed in recent years. among these schemes, vector control (with stator flux or voltage orientation) is the most widely used to control the active and reactive power of the stator dfig. the decoupled control of the instantaneous active and reactive power of the stator has been achieved by controlling the rotor currents either using linear or nonlinear controllers. the linear control such as the classical proportionalintegrator (pi) controller proposed in [12, 13]. on the other hand, there are non-linear controllers such as sliding mode control, backstepping, and fuzzy logic [1, 14, 15]. this paper deals with the detailed modeling of fifth and third-order models of the dfig based on transient reactance. in addition, the comparison between fifthorder and third-order models of the dfig is presented. this comparison was made between the two models in an open and closed loop. the main contribution of this paper is the study and analysis of transient stability, as well as to clarify the impact of both two models of the dfig on the power system. the paper is organized as follows: section 2 gives a description of a dfig in a wind power system. in section 3, a detailed model of fifth-order and third-order for dfig based on transient reactance is presented. in section 4, the control of the dfig based on vector control with stator flux orientation is presented. the simulations results of the dfig models mentioned in this work in the open and close loop are presented and discussed in section 5. finally, section 6 outlines the main conclusions of the paper. ii. description of dfig in wind power system in figure 1, the control scheme of a wind energy conversion system based on a dfig is depicted. measurement signal speed control power control reference signal pitch control dcv t g   dfig gsc rsc abcsi , ss qp abcri , figure 1. control scheme of a wind energy conversion system based on a dfig. the dfig consists of two three-phase windings, in stator and rotor. generally, the stator of the dfig is connected directly to the electrical network through three-phase lines while the rotor is connected to the electrical network through two bidirectional ac-dc and dc-ac converters. the converters on the generator side and on the grid side are modeled as a voltage. the main purpose of these converters is to change the frequency between the electrical network and the generator rotor, allowing the operation of wind turbine at variable speed. the grid side converter (gsc) controls the dc bus voltage and the rotor side converter (rsc) controls the active and reactive stator power. iii. modeling of dfig in wind power system typically, the electrical system part of a wind power system consists of a generator, a set of power electronics converters, and a control system. generally, the induction machine is modeled using the well-known "t-form" equivalent circuit with self and mutual inductances [16]. the dfig is generally represented by fifth-order differential equations of the flux linkages and shaft speed. according to a standard per-unit notation, can be represented this model in the ( qd  ) rotating reference frame by the stator and rotor voltages equations which can be written as follows [4, 13]:          sdsqssq sq base sqsdssd sd base irv dt d irv dt d       1 1 (1) m. atallah et al ijeca-issn: 2543-3717. december 2021 page 46          rdrqrrq rq base rqrdrrd rd base sirv dt d sirv dt d       1 1 (2) where sqsd v,v and rqrd v,v are the stator and rotor voltages, respectively, sqsd i,i and rqrd i,i are the stator and rotor courants, respectively, sqsd , and rqrd , are the stator and rotor flux, rs r,r are the stator and rotor resistances, respectively, s is the synchronous speed, base is the synchronous speed base, s is the slip. the electromagnetic relations can be expressed as follows:                       rqmsqs rdmsds sq sd s ixix ixix   (3)                       sqmrqr sdmrqr rq rd r ixix ixix   (4) with the stator and rotor reactance defined as follows: mss xxx   , mrr xxx   , where  rs x,x is the stator and rotor leakage reactance, respectively. the fifth differential equation describing mechanical motion is: emmec g s tt dt dh    2 (5) where h is the inertia constant in seconds m ect is the mechanical torque and emt is the electromagnetic torque. iii.1.1. fifth-order model of the dfig in this section, model fifth-order based on transient reactance and internal voltage components are presented. according to equation (4), the rotor currents, as follows:           r sqmrq rq r sdmrd rd x ix i x ix i   (6) substituting equation (6) into equation (3), we get the stator flux as follows:       dsqsq qsdsd eix eix   (7) with r m ssrd r m qrq r m d x x xx x x e x x e 2  ,,  after substituting equations (6) and (7) into equations (1) and (2), the fifth-order model of the dfig behind a transient reactance is obtained:                                              sqrqdsds qssq ss s sq sdrdqsqs dssd ss s sd vk ve t ix esi t xx r dt di vk ve t ix esi t xx r dt di 1 1 1 1 ... ...   (8)                     rddssdssq q rqqssqssd d k vesixxe tdt ed k vesixxe tdt ed   1 1 (9) with constants defined as follows: s sx     , r m s x x k  , rs r r x t   , where t  is the transient open circuit time constant, sx  is the transient reactance, de  and qe  are the internal voltage components of induction generator. the electromagnetic torque is calculated based on internal voltage as follows: sqqsddem ieiet  (10) iii.1.2. third-order model of the dfig by neglecting the stator transients in the fifth-order model of a dfig, a third order model is obtained. the third order model frequently used in transient stability studies. the following equations describe the third-order model of the dfig in the ( qd  ) rotating reference frame [7].       sdsqssq sqsdssd irv irv   (11) m. atallah et al ijeca-issn: 2543-3717. december 2021 page 47          dt d sirv dt d sirv rq base rdrqrrq rd base rqrdrrd       1 1 (12) substituting equations (6) and (7) in equations (11) and (12), respectively, it is obtained a third-order model of the dfig behind transient reactance, given by the following electrical equations:       qsdssqssq dsqssdssd eixirv eixirv (13)                     rddssdssq q rqqssqssd d k vesixxe tdt ed k vesixxe tdt ed   1 1 (14) iv. control of dfig in wind power system iv.1. decoupling of the active and reactive powers the following steps must be taken to connect the dfig to the grid. the first step is to synchronize the stator voltage with the grid voltage, the second step is to connect the stator to the grid and the last step is to regulate the active/reactive power between the dfig and the grid. in order to facilitate the control of the stator active and reactive powers injected into the electrical network, it is necessary to realize an independent control by the orientation of the stator flux. the objective of this choice is that the rotor currents are directly related to the stator active and reactive powers. an adapted control of these currents allows controlling the power exchanged between the dfig stator and the network. if the stator flux is linked to the d-axis of the frame we have [12, 13]: 0 sqssd  (15) neglecting the stator voltage drop and assuming that the network system is perfectly stable, with a single voltage that conducts a constant flux to the stator, we can easily deduce the voltages as follows:       ssdssq sd vv v  0 (16) where sv is the value of the grid voltage. from the orientation of the stator flux, the fluxes equations of dfig stator are simplified as below:       rqmsqs rdmsdss ixix ixix 0  (17) using equation (17), the stator currents equation becomes the following:         rq s m sq rd s m s s sd i x x i i x x x i  1 (18) substituting equation (18) in equation (4), we obtain the following expression:                           rq s m rrq s s m rd s m rrd i x x x x x i x x x 2 2   (19) by substituting equation (19) in equation (2), we obtain the following expression:                                                       dt di x xx x x si x xx sirv dt d x x dt di x xx i x xx sirv rq s mr s s m srd s mr srqrrq s s m rd s mr rq s mr srdrrd 2 2 22 ..... ..    (20) by simplifying equation (20), we obtain:                      qarqr rq s m rqr darqr rd s m rdr eir dt di x x xv eir dt di x x xv , , 2 2 (21) with dae , and dae , are the crosses coupling terms between the d axis and q axis:                      s s m srd s m rsqa rq s m rsda x x si x x xse i x x xse   2 2 , , (22) m. atallah et al ijeca-issn: 2543-3717. december 2021 page 48 using equation (21), the rotor current equation becomes the following:              )( )( )( )( , , qarq r rq dard r rd ev rs i ev rs i   1 1 (23) with s m r x x x 2  the active and reactive power of the dfig can be expressed by:       sdss sqss ivq ivp (24) by substituting the stator currents by their expressions given in (18), the stator active and reactive power can then be expressed only as a function of these rotor currents as:         rd s ms s s s s rq s m ss i x xv x v q i x x vp  (25) by replacing the rotor currents with their values from equation (23) in equation (25), we obtain the following equations for the active and reactive powers:                             pr ev x xv x v q pr ev x xv p r dard s ms ss s s r qarq s ms s   , , 2 (26) iv.2. indirect control power of difg in the section, control without a power regulation loop is presented. these forces are controlled indirectly by tuning the direct and quadratic components of the rotor current with a proportional integration (pi) corrector. simple and fast to implement pi corrector while offering acceptable performance. the indirect control without the power control loop of the dfig connected directly to the network is shown in figure 2. sq dfig p w m dq abc pll + flux estimation + power measurement encoder pi  rdi s r c * ,1rd v rdi + * rdi dae , + + * rdv pi  rqi * ,1rq v sm s vx x + * rqi qae , + + * rqv rqi * rav * rbv * rcv sm s vx x + *sq ss s x v  2 * sp dq abc rqi rdi rai rbi rci  d t d d t d  abcsv , abcsi , s s r s̂ sp rq s m rs i x x xs          2                    s sm rd s m rs x x i x x xs   ˆ2 dae , qae , r figure 2. indirect control without power control loop of the dfig directly connected to the grid. m. atallah et al ijeca-issn: 2543-3717. december 2021 page 49 v. simulation results and discussions in this section, the comparison results between the fifth-order model and third-order model of the dfig in the open-loop and close-loop are presented. this comparison is performed by simulations using matlab/ simulink® software. the dfig used for simulation was a 2 mw, 690 v and dfig parameters are given in appendix b. during the simulation period, the dfig operates at nominal conditions. the total time of the simulation is fixed at 10s and runge-kutta integration is used with a 0.0001s time step. figure 3 shows the simulation results for the two dfig models, fifth-order and third-order in an open loop. figure 3a shows the generator speed applied to two models. this speed starts at 0.8 during the first five seconds of the simulation. then it goes up to 0.95 p.u. 5 to 10 seconds. figures 3b, 3c, 3d show respectively the electrom-agnetic torque and the currents of the stator on the qd  axes. figure 4 shows the simulation results for the fifthorder model and third-order model of the dfig in the closed-loop. figures 4a, 4b, 4c, 4d, 4e, 4f, show respectively the generator speed, the electromagnetic torque, the currents of the stator on the axes, the active and reactive power of the stator. according to the simulation results of figure 4, we notice that the active and reactive stator power ( ss qp , ) generated by the dfig follow their references power ( ** , ss qp ) and there is a small error. moreover, we notice that the currents ( rqsq ii , ) are promotional to the active power generated by the dfig and that the currents ( rdsd ii , ) are promotional to the reactive power. electromagnetic torque has the same shape as active power because torque and active power are directly related to the quadrature rotor current. through the simulation results obtained in the openloop and in closed-loop, the third-order model compared to the fifth-order model does not allow any disturbance in the magnitudes of the stator (direct and quadrature currents) and the electromagnetic torque during the dfig start-up. moreover, it can be concluded that the complete neglect of stator flux transients gives a stable response in the transient regime during the simulation process. not neglecting stator flow transients, as noted above, can have critical effects on the integration of a large wind farm into the power grid. although the dynamic behavior is similar for the two models in the permanent regime and when the generator speed changes, the third-order model is suitable for the study of transient stability. g e n e ra to r sp e e d w g ( p u ) 0 2 4 6 8 10 0 0.4 0.8 1.2 wg = 0.8p .u wg = 0.95p .u generator sp eed change (t=5s) e le c tr o m a g n e ti c t o rq u e ( p u ) 0 2 4 6 8 10 -2 -1 0 1 0 0.2 0.4 -2 -0.5 1 zoom the transient regime tem, 5th order model tem, 3rd order model a) time (s) b) time (s) d -a x is s ta to r c o u ra n t is d ( p u ) 0 2 4 6 8 10 0 5 10 15 0 0.2 0.4 0 6 12 zoom the transient regimeisd, 5rd order model isd, 3rd order model q -a x is s ta to r c o u ra n t is q ( p u ) 0 2 4 6 8 10 -6 0 6 12 0 0.2 0.4 -6 0 6 isq, 5th order model isq, 3rd order model zoom the transient regime c) time (s) d) time (s) figure 3. comparison results between 5th and 3rd order model of the dfig in the open-loop. m. atallah et al ijeca-issn: 2543-3717. december 2021 page 50 g e n e ra to r sp e e d w g ( p u ) 0 2 4 6 8 10 0 0.4 0.8 1.2 wg = 0.8p .u wg = 0.95p .u generator sp eed change (t=5s) e le c tr o m a g n e ti c t o rq u e ( p u ) 0 2 4 6 8 10 -3 0 3 6 9 0 0.5 1 0 9tem, 3rd order model tem, 5th order model zoom the transient regime a) time (s) b) time (s) d -a x is s ta to r c o u ra n t is d ( p u ) 0 2 4 6 8 10 -4 0 4 8 12 0 0.5 1 -4 2 8 zoom the transient regime isd, 3rd order model isd, 5th order model q -a x is s ta to r c o u ra n t is q ( p u ) 0 2 4 6 8 10 -4 0 4 8 0 0.5 1 -4 2 8 zoom the transient regimeisq, 3rd order model isq, 5th order model c) time (s) d) time (s) a c ti v e p o w e r, p s (p u ) 0 2 4 6 8 10 -4 -2 0 2 4 0 0.5 1 -4 0 4 zoom the transient regimeps, 3rd order model ps, 5th order model r e a c ti v e p o w e r, q s (p u ) 0 2 4 6 8 10 -6 0 6 12 0 0.5 1 -5 0 5 zoom the transient regime qs, 3rd order model qs, 5th order model e) time (s) f) time (s) figure 4. comparison results between 5th and 3rd order model of the dfig in close-loop. m. atallah et al ijeca-issn: 2543-3717. december 2021 page 51 iv. conclusion this paper presents the detailed model of the dfig in the fifth-order and third-order based on the transient interaction. a comparison between the two open and closed loop models was also presented. through the simulation results, it was found that the fifth-order model, although it gives an accurate representation of the dynamic performance of dfig, but has an impact on the start-up of a dfig and the insta-bility of the transient system. on the other hand, the third-order model adequately reproduces the transient current and torque responses of the dfig at startup and stability of the transient system. the results achieved allow the conclusion that the third-order model is suitable for the study and analysis of the transient stability of large-scale electrical systems. in addition, the third-order model for modeling and the study of the transient behavior of a wind farm integrated into the power grid than the fifth-order representation can be preferred. appendix a base values for the per-unit system converting. the base voltage basev =690 v, the base power bases =2mw, the basic electrical speed basebase f 2 , the base frequency basef =50hz. appendix b the parameters of our system are in table 1[11]. references [1] k. d. kerrouche, a. mezouar, l. boumediene, a. van den bossche, speed sensor-less and robust power control of grid-connected wind turbine driven doubly fed induction generators based on flux orientation, the mediterranean journal of measurement and control, vol. 12, 2016, pp. 606-618. [2] h. benbouhenni, comparison study between svpwm and fsvpwm strategy in fuzzy second order sliding mode control of a dfig-based wind turbine, carpathian journal of electronic & computer engineering, vol. 12, 2019. [3] y. saidi, a. mezouar, y. miloud, m. benmahdjoub, m. yahiaoui, modeling and comparative study of speed sensor and sensor-less based on tsr-mppt method for pmsg-wt applications, international journal of energetica (ijeca), vol. 3, 2018, pp. 6-12. [4] i. al-iedani z. gajic, order reduction of a wind turbine energy system via the methods of system balancing and singular perturbations, international journal of electrical power & energy systems, vol. 117, 2020, p. 105642. [5] p. ledesma and j. usaola, doubly fed induction generator model for transient stability, ieee transactions on energy conversion, vol. 20, 2005 , pp. 388-397. [6] h. li, c. yang, b. zhao, h. wang, and z. chen, aggregated models and transient performances of a mixed wind farm with different wind turbine generator systems, electric power systems research, vol. 92, 2012 , pp.1-10. [7] l. shi, z. xu, j. hao, and y. ni, modelling analysis of transient stability simulation with high penetration of grid‐connected wind farms of dfig type, wind energy: an international journal for progress and applications in wind power conversion technology, vol. 10, 2007, pp. 303-320. [8] p. c. krause, f. nozari, t. skvarenina, and d. olive, the theory of neglecting stator transients, ieee transactions on power apparatus and systems, , 1979, pp. 141-148. [9] p. c. krause, o. wasynczuk, s. d. sudhoff, s. pekarek, analysis of electric machinery and drive systems vol. 2: wiley online library, 2002. [10] o. wasynezuk, y.-m. diao, p. krause, theory and comparison of reduced order models of induction machines, ieee transactions on power apparatus and systems, 1985, pp. 598-606. [11] j. b. ekanayake, l. holdsworth, n. jenkins, com-parison of 5th order and 3rd order machine models for doubly fed induction generator (dfig) wind turbines, electric power systems research, vol. 67, 2003, pp. 207-215. [12] s. chatterjee, a. naithani, v. mukherjee, smallsignal stability analysis of dfig based wind power system using teaching learning based optimization, international journal of electrical power & energy systems, vol. 78, 2016, pp. 672-689. [13] b. mehta, p. bhatt, v. pandya, small signal stability enhancement of dfig based wind power system using optimized controllers parameters, international journal of electrical power & energy systems, vol. 70, 2015, pp. 70-82. [14] y. dbaghi, s. farhat, m. mediouni, h. essakhi, a. elmoudden, indirect power control of dfig based on wind turbine operating in mppt using backstepping approach, international journal of electrical & computer engineering (2088-8708), vol. 11, 2021. [15] v. galdi, a. piccolo, p. siano, designing an adaptive fuzzy controller for maximum wind energy extraction, ieee transactions on energy conversion, vol. 23, 2008, pp. 559-569. [16] j. j. justo, f. mwasilu, j.-w. jung, doubly-fed induction generator based wind turbines: a compre-hensive review of fault rideturbines: a comprehensive review of fault ridethrough strategies, renewable and sustainable energy reviews, vol. 45, 2015, pp. 447-467. i. introduction ii. description of dfig in wind power system iii. modeling of dfig in wind power system iv. control of dfig in wind power system iv. conclusion this paper presents the detailed model of the dfig in the fifth-order and third-order based on the transient interaction. a comparison between the two open and closed loop models was also presented. through the simulation results, it was found that th... the results achieved allow the conclusion that the third-order model is suitable for the study and analysis of the transient stability of large-scale electrical systems. in addition, the third-order model for modeling and the study of the transient be... appendix a appendix b international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 2. 2020 page 18-24 ijeca-issn: 2543-3717. december 2020 page 18 economic evaluation of zinc oxide nanoparticle production through green synthesis method using cassia fistula plant extract fatmarin zahra, fidya ahdiati utami, gabriela chelvina santiuly girsang, sri zahra mina setyani mulya, vina dian fentiana, yashinta kirana putri, asep bayu dani nandiyanto * departemen pendidikan kimia, universitas pendidikan indonesia, indonesia email * : nandiyanto@upi.edu abstract – the purpose of this study was to determine the feasibility of a zinc oxide (zno) manufacturing project through a green synthesis method using plant extracts cassia fistula and then evaluate it from an engineering and economic perspective. several economic evaluation parameters are analyzed to inform the potential production of zno nanoparticles, such as the length of time required for an investment to return the total initial expenditure (pbp), the condition of a production project in the form of a production function in years (cnpv), project benefits and so on. the results showed that the production of zno nanoparticles was very prospective. technical analysis to produce 250 kg of zno nanoparticles per day shows the total cost of the equipment purchased to be 21,450.00 usd. pbp analysis shows that investment will be profitable after more than three years. this project can compete with pbp capital market standards because of the short investment returns. to ensure the feasibility of a project, the project is estimated from ideal conditions to the worst case in production, including labor, sales, raw materials, utilities, and external conditions. keywords: zinc oxide, green synthesis, economic evaluation. received: 08/11/2020 – accepted: 15/12/2020 i. introduction zinc oxide (zno) is an inorganic compound in the form of a white powder that is insoluble in water. this compound can be found in nature as the mineral zincite. zno crystallizes in three forms: hexagonal wurtzite, cubic zinc blende, and cubic salt rock. the wurtzite structure is the most common structure. zno can be used in various applications due to its ability to absorb ultraviolet radiation and can be a photocatalyst or photodetector because it has a wide band gap (3.37 ev) and high bond excitation energy (60 mv) [1]. zno exhibits interesting optical, acoustic and electrical properties and has a number of potential applications in electronics, optoelectronics and sensors. zno has great potential as a transparent electrode in photovoltaic technology, electroluminescence devices, and materials for ultraviolet emitting devices [2]. zinc oxide (zno) has various uses in various applications such as photoelectric devices, efficient absorbers, chemical and biological sensors, photocatalytic degradation [3], solar cells, sun cream raw materials which are effective in absorbing uv rays, uv lasers, light-emitting devices-diodes (led) to photovoltaic electrodes. recent research has shown zno has antimicrobial properties that can be used as a food packaging material. many methods have been developed to synthesize zno nanoparticles, including direct precipitation method [4], homogeneous deposition method [5], sol-gel technique [6], hydrothermal processing method [7-8], microwave sintering method [9]. then there are also several solid and gas based methods, such as solid-state reactions, spray pyrolysis [10,11], gas phase condensation and thermal evaporation [12-14]. the synthesis of nanoparticles can also be carried out by physical or chemical means. chemical methods such as sol-gel, precipitation and microemulsion have successfully synthesized zno nanoparticles with variations in particle shape and size. the most appropriate method for an economic evaluation analysis fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 19 is the green synthesis method using extract cassia fistula [15]. to confirm that zno nanoparticles were successfully produced, then the samples were characterized by using sem and powder x-ray diffraction [16]. the choice of this method is because the green synthesis is an environmentally friendly and simple method, it does not require raw materials that are carcinogenic and expensive. the purpose of this study was to determine the feasibility of a project for making zno nanoparticles through the green synthesis method using plant extracts cassia fistula and then evaluating from an engineering and economic perspective. we made this paper because there is no article discusses in detail the economic evaluation of zno nanoparticle synthesis. changing the lab scale to industrial scale on the quantity of raw materials and equipment was carried out for this study. we perform several economic variations on taxes, sales, raw materials, labor and utilities. ii. method ii.1. synthesis of zno nanoparticles currently, green synthesis method is being developed as an alternative to make nanoparticles that are environmentally friendly and still produce nanoparticles with good characteristics. the method for obtaining zno is by burning the solution with a homogeneous mixing of combustible fuels. the mixing of zinc nitrate hexahydrate with cassia fistula extract will produce zno nanoparticles. during the breakdown of the solution, there is an exothermic reaction between the oxidizing and reducing substance. generally, metal nitrate derived from zinc nitrate hexahydrate acts as an oxidizing agent and fuel from cassia fistula leaf extract acts as a reducing agent. research has stated that the method of making cassia fistula leaf extract begins with reflux extraction [14]. however, before reflux, 0.2 grams of cassia fistula leaves were mixed with 10 ml of distilled water. the reflux process was carried out for 5 hours with constant stirring. the extract is filtered and centrifuged to remove insoluble material. the extract was then concentrated in an evaporator and stored at 4 0 c. all processes of synthesis zno nanoparticles are shown in figure 1. figure 1. synthesis of zno nanoparticles using extract cassia fistula ii.2. economic evaluation this research used a method based on the analysis of the price of materials, equipment, and equipment specifications that are commercially available on the online shopping web. all data is calculated based on simple mathematical calculations using microsoft excel. economic parameter evaluation was carried out to confirm the economic evaluation of this project. several economic evaluation parameters are used based on literature [16], economic evaluation parameters are presented in the following: 1. gross profit margin (gpm) is the first analysis to determine the level of profitability of a project by reducing the cost of selling the product with the cost of raw materials. 2. payback period (pbp) or fund back is a calculation done to predict the length of time it will take for an investment to return the total initial outlay. pbp is calculated when cnpv is at zero for the first time. 3. breakeven point (bep) is the minimum amount of product that must be sold at a certain price to cover the total cost of production. bep can be calculated by calculating the fixed cost value divided by (total sales price less total variable cost). fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 20 4. cumulative net present value (cnpv) is a value that predicts the condition of a production project in the form of a production function in years. the cpnv value is obtained from the net present value (npv) at a certain time. npv is a value that states the expenses and income of a business. in short, cnpv is obtained by adding the npv value from the first project to the end of the plant operation. 5. profitability index (pi) is an index to identify the relationship between project costs and impacts. pi can be calculated by dividing the cnpv with the total investment cost (tic). if the pi is less than one, then the project can be classified as an unprofitable project and if the pi is more than one, the project can be classified as a good project. some of the process-based assumptions are shown in figure 2. these assumptions represent the stoichiometric calculations after scaling up the project which resulted in about 250 kg of zno nanoparticles. the assumptions are: (1) all chemical compositions in the reaction, such as zinc nitrate hexahydrate, leaf extract cassia fistula and distilled water are used for the production of mgo nanoparticles. these materials are increased up to 2000 times. the ingredients are of high purity. the ingredients are counted from the literature. (2) leaf extract cassia fistula and zinc nitrate hexahydrate reacted in a ratio of 1: 4. (3) the conversion rate for the zinc oxide formation process is 100%. several assumptions are used to confirm the economic analysis. these assumptions are needed to analyze and predict some of the possibilities that occur during the project. the assumptions are: 1. all analyzes are in usd. 1 usd = 15,000 rupiah. 2. based on commercially available prices, the prices for zinc nitrate hexahydrate and leaf cassia fistula are 166.67 usd / kg and 333.3 usd / kg. all materials were estimated based on stoichiometry. 3. the total investment cost (tic) is calculated based on the lang factor [16,17]. 4. tic is prepared in at least two steps. the first step is 40% in the first year and the second step is the rest (during project development). 5. land purchased. thus, land costs are added at the beginning of the factory construction year and recovered at the end of the project. 6. depreciation is estimated using direct calculations [16]. 7. one cycle of the process for making zno nanoparticles takes 10 hours. 8. postage costs are borne by the buyer. 9. mgo nanoparticles are priced at 5 usd / pack. 10. one year's project is 300 days (and the rest are days spent on cleaning and organizing the process). 11. to simplify utility, utility units can be described and converted as units of electricity, such as kwh [18]. then, the electricity unit is converted into cost. the unit of electricity (kwh) is multiplied by the cost of electricity. 12. total wages / labor are assumed to be fixed at 150 usd / day for 30 workers. 13. the discount rate is 15% per annum. 14. income tax is 10% annually. 15. the project operation length is 20 years. economic evaluation is conducted for a project feasibility test. this economic evaluation is carried out by varying the value of taxes, sales, raw materials, labor and utility under several conditions. tax variations are made at 10, 25, 50, 75 and 100%. variations in sales, raw materials, labor and utilities were carried out at 80, 90, 100, 110 and 120%. iii. results and discussion iii.1. engineering perspective figure 2 shows the process of making zno nanoparticles using the eco-friendly green combustion route based on literature. all the symbols in figure 2 are informed in table 1. from an engineering point of view, the total cost for purchasing raw materials for one year is 150,000 usd. sales in one year were 375,000 usd. the profit earned was 100,344.39 usd. the price for the analysis of equipment costs is 21,450 usd. the tic must be less than 90,948.00 usd. this project requires a small investment fund. the project life span is 20 years, resulting in zno nanoparticles with cnpv / tic reaching 2.167%, in the 9th year, and pbp has been reached in the 3rd year. figure 2. process flow diagram of zno fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 21 table 1. process flow diagram of zno no symbol information 1. g-1 grinding-1 2. t-1 tank-1 3. t-2 tank-2 4. t-3 tank-3 5. e-1 extractor-1 6. s-1 separator-1 7. c-1 centrifuge-1 8. r-1 reactor-1 9. f-1 furnace-1 iii.2. economic evaluation 2.1. ideal conditions figure 3 shows a graph of the relationship between the cnpv/ tic value on the y-axis and the lifetime (year) on the x-axis. in the curve, it can be found a negative cnvp / tic value (%), which is a value below 0 in the first year to the third year, which indicates a decrease in income in that year due to costs for initial capital for zno nanoparticle production. the lowest cnvp / tic value occurred in the second year which was -0.845204551. however, after that, the curve rises again for the first 9 years with a value reaching 1,89536589. there is no profit from the 1 st year to the 3 rd year. this is because of the initial capital costs such as the tools needed during the process of producing zno nanoparticles. in the 3 rd year, the graph shows an increase in income, which is the payback period (pbp). in the 3 rd year, there is an increase until the 9 th year and the income gain is able to cover the initial capital or the capital reversal. in table 2, the cnvp / tic value is negative from the first to the third year. then the cnvp/tic value began to come back positive in the 4 th year with a value of 0.33206856 which continued to increase until the 9 th year with a value of 2.167604403. thus, the production zno nanoparticles can be considered a profitable project because zno nanoparticle production requires a short time to recover investment costs. this is in line with previous studies where the cnpv / tic value decreased below 0 in the first 2 years to restore the initial total expenditure for the project. but after that, there will be an increase in the cnpv / tic value to a positive value in economic parameters. figure 3. cnpv/tic graph for lifetime year under ideal conditions table 2. annual cnpv values in ideal conditions. cnpv/tic year 1. 0 -0.409351928 1 -0.845204551 2 -0.215500329 3 0.33206856 4 0.80821542 5 1.222256168 6 1.582291601 7 1.89536589 8 2.167604403 9 2.2. the effect of external conditions economic evaluation on external factors can actually affect the success of a project. one of the factors is the tax given on projects by the country to finance various public expenditures. figure 4 shows a graph of cnpv for 10 years with various tax variations, where the y-axis is cnpv / tic and the x-axis is a lifetime (year). figure 4 shows that the conditions at the beginning of the year to two years show the same results because cnpv is under tax variations and the existence of project development. in addition, in that year there was no income and there was a reduction in accordance with the ideal condition chart. an increased tax after two years can affect the cnpv value and when tax costs are added to the project it results in lower project profits. this is related to pbp because the higher the tax issued, the pbp for the initial investment capital will be longer than ideal conditions. funds that will return when taxes have to be paid according to the pbp analysis of 10% will be achieved in year 3; 25% year 3.5; 50% 4th year; 75% year 6, and 100% pbp not achieved. the project profit will continue to increase when it reaches the payback period (pbp) point until the 10th year. cnpv / tic values in the 10th fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 22 year for 10, 25, 50, 75, and 100% were 2.17, 1.69, 0.89, 0.09 and -0.71%. therefore, the maximum tax earned for obtaining the bep or the point where the profit or loss on the project is 75%. if the tax change you get is more than 75%, it can make the project fail. figure 4. graphs of cnpv for tax variations 2.3. change in sales figure 5 shows a cnpv chart with various sales variations. the y-axis is cnpv / tic and the x-axis is the lifetime (year). the analysis was carried out by increasing and decreasing sales by 10% and 20%. the ideal sales are 100% when sales are decreased by 10% and 20%, the sales are 90% and 80% of the ideal 100%, respectively. when sales are increased by 10% and 20%, the sales will be 110% and 120%. pbp is obtained from sales variations. the results of the pbp are shown in figure 5. the initial conditions (from 0 to 2 years of project) of cnpv under various sales variations are the same. this is due to project development. the effect of sales on cnpv can be obtained after the project is created (from 2 years). the greater the sales value, the more profits will increase from the project being undertaken. however, if there are conditions that cause product sales to decline, the project profit will decrease from the ideal state. based on the pbp analysis, funds returned when sales variations of 120.110, 100.90, and 80% were achieved in year 3 and pbp was not achieved. profits continue to increase after reaching the payback period (pbp) point until the 9th year. pbp results for sales variations of 90, 100, 110, and 120% were achieved in year 4.5 respectively; 3.5, 3 and 2,9. pbp at 80% sales variation is still not achieved in the 9th year. however, the gap in profits generated for each year decreases as sales decrease and losses when sales are reduced by 20% from ideal conditions. conversely, the profit distance generated for each year increases with increasing sales from ideal conditions. the cnpv / tic value in the 9th year for each variation of 120, 110, 100, 90, and 80% is 4.50, 3.33, 2.16, 1.00 and -0.16% so, the minimum sales to earn bep (the point at which both the profit and loss on the project) is 90%. changes in sales of less than 90% result in project failures. as with zno nanoparticles sales are profitable if sales are increased by more than 100% because the graph shows a positive cnpv / tic value, this means the project is feasible to run. figure 5. cnpv curve of sales variation 2.4. change in variable cost (raw material, labor, utility) factors such as raw material conditions, utility, and labor can influence the success of a project. figure 6 shows a cnpv chart with variations in raw material price. the ideal raw material price was 100%. analysis of variations in raw materials was carried out by lowering and increasing the price of raw materials by 10 and 20% from ideal conditions. the variations of the raw materials used in this analysis were 80, 90, 100, 110, and 120%. the cpnv/tic value was constant in the initial project condition (0-2 years) because the project was still under construction. variations in raw material price began to affect the cpnv/tic value after 2 years of the project. the decreases in raw material expense resulted in increases in profits. however, if there is a situation that causes the price of raw materials to increase, the profits decreased. the value of cpnv/tic in the 9th year for the variation of raw materials 80, 90, 100, 110, and 120% were 3.10; 2.63; 2.16; 1.70; and 1.23%. pbp results from variations in raw material prices of 80, 90, 100, 110, and 120% were achieved respectively in the year 3.00; 3.20; 3.40; 3.65; and 4.00. the closest payback period (3 fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 23 years) with the largest profit (cpnv/tic = 3.10%) can be obtained from the variation of 80% raw material price. figure 6. cpnv/tic with raw material price variations as shown in figure 7, the cnpv/tic graph is analyzed with various utility price. the analysis was carried out by decreasing and increasing utility prices by 10 and 20% from ideal conditions. the ideal utility price was 100%. the utility price variations used in this analysis were 80, 90, 100, 110, and 120%. the cpnv/tic value from year 0 to 2 after the project was created is constant. this was due to the project development stage. the effect of the utility price on the cpnv/tic value can be obtained 2 years after the project is created. there was no significant effect of utility price variation on the cpnv/tic graph. the project can still run and make a profit. the cpnv/tic values in the 9th year for the utility variations of 80, 90, 100, 110, and 120% were 2.19; 2.18; 2.16; 2.15; and 2.13%. the pbp results from the utility variations of 80, 90, 100, 110, and 120% will be achieved in 3,4 since the project was created. the closest payback period (3.4 years) with the largest profit (cpnv/tic = 2.19%) can be obtained from the 80% utility variation. figure 7. cpnv/tic with utility price variations the cnpv/tic graph was analyzed with various labor wages as shown in figure 8. the analysis was carried out by decreasing and increasing the wages of workers by 10 and 20% from ideal conditions. the worker's ideal salary was 100%. the variations in the wages of workers used in this analysis were 80, 90, 100, 110, and 120%. in the initial project conditions (0-2 years), the cnpv/tic value was constant. this was obtained at the project development stage. the labor wage variations were affecting the cpnv/tic chart after the second year since the project was created. the higher the worker's salary, the lower the project's profit. on the other hand, the biggest project profit was derived from the lower wages of the workforce. the cpnv/tic values in the 9th year for the workers wage variations of 80, 90, 100, 110, and 120% were 2.63; 2.40; 2.17; 1.93; and 1.69%, respectively. the pbp results from the worker salary variations of 80, 90, 100, 110, and 120% were achieved in 3,2; 3,3; 3,4; 3.5; and 3.67, respectively. the closest payback period (3.2 years) with the largest profit (cpnv/tic = 2.63%) can be obtained from the worker's salary variation of 80%. figure 8. cpnv/tic with worker’s salary variation fatmarin zahra et al ijeca-issn: 2543-3717. december 2020 page 24 iv. conclusion based on the above analysis, the zno nanoparticle production project with green synthesis method using extract cassia fistula is prospective from an engineering point of view and it is promising in economic evaluation. pbp analysis shows that investment is profitable after more than 3 years. this project can compete with pbp capital market standards because of the short investment returns. some of the things that affect this benefit include using the green synthesis method, because this method is very simple, does not use hazardous materials and is cheap. from the analysis of this economic evaluation, we can conclude that this project is feasible to run. references [1] z. r dai, z. w pan, z. l wang, “novel nanostructures of functional oxides synthesized by thermal evaporation”, advanced functional materials, vol. 13, issue 1, 2003, pp. 9-24 [2] m abdullah, khairurrijal, “review: karakterisasi nanomaterial”, jurnal nanosains & nanoteknologi, 2009. [3] w. yujum, z. chunling, and b. siwei, “preparation of zno nanoparticles using the direct precipitation method in a membrane dispersion micro-structured reactor”, powder technology, 2010, pp.130-136. [4] c chen, p liu, c lu, “synthesis and characterization of nano-sized zno powders by direct precipitation method”, chemical engineering journal, vol. 144, issue 3, 2008, pp.509-513. [5] y liu, zhou, jian-er, a. larbot, “preparation and characterization of nano-zinc oxide”, journal of materials processing technology, vol. 189, 2007, pp.379-383. [6] k. hayat, m.a. gondal, m.m. khaled, “nano zno synthesis by modified sol gel method and its application in heterogeneous photocatalytic removal of phenol from water”, applied catalysis a: general, vol. 393, 2011, pp.122-129. [7] m h mamat, m z sahdan, s amizam, “properties of nanostructured zinc oxide by hydro-thermal aqueous chemical growth method”, aip conference proceedings, 2009, pp.586–590. [8] a. aimable, m. t. buscaglia, v buscaglia, p. bowen, “polymer-assisted precipitation of zno nanoparticles with narrow particle size distribution”, journal of the european ceramic society, vol. 30, 2010, pp.591–598. [9] s.e savary, marinel, h colder, “microwave sintering of nano-sized zno synthesized by a liquid route”, powder technology, vol. 208, 2011, pp.521-525. [10] x, zhao, b. zheng, c li, and h. gu, “acetate-derived zno ultrafine particles synthesized by spray pyrolysis”, powder technology, vol. 100, 1998, pp.20–23. [11] t tani, l, mädler, s. e pratsinis, “homogeneous zno nanoparticles by flame spray pyrolysis”, journal of nanoparticle research, vol. 4, issue 4, 2002, pp.337–343. [12] j.y. li., x.l. chen, h. li, m. he, “fabrication of zinc oxide nanorods”, vol. 233, issue 1, 2001, pp.5-7 [13] h kleinwechter., c. janzen., j. knipping, h. wiggers, “formation and properties of zno nano-particles from gas phase synthesis processes”, vol. 37, 2002, pp.4349-4360. [14] d. suresh, p. c. nethravathi., udayabhanu, h. rajanaika, h. nagabhushana, s. c sharma, “green synthesis of multifunctional zinc oxide (zno) nanoparticles using cassia fistula plant extract and their photodegradative, antioxidant and antibacterial activities”, materials science in semiconductor processing, vol. 31, 2015, pp.446–454. [15] e. r. p. priyanda, a. sukmafitri, a. mudzakir, a.b.d. nandiyanto. w. c. nugraha, w. ramadhani, “zinc oxide nanoparticles for enhancing students view of the nature of science and technology”, indonesian journal of science & technology, vol. 5, issue 1, 2020. [16] f. nandatamadini, s. karina, a.b.d nandiyanto, r. ragadhita, “feasibility study based on economic perspective of cobalt nanoparticle synthesis with chemical reduction method” international journal of energetica. vol. 4, issue 1, 2019, pp.17-22. [17] bank indonesia, “foreign exchange rates”. [online]. available: https://www.bi.go.id/en/moneter/informasikurs/referensi-jisdor/, 2020. https://www.bi.go.id/en/moneter/informasi-kurs/referensi-jisdor/ https://www.bi.go.id/en/moneter/informasi-kurs/referensi-jisdor/ international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 13-20 ijeca-issn: 2543-3717. december 2021 page 13 performance study and analysis between vector control and direct power control for dfig based wind energy system gufran nurettin * , ata sevinç department of electrical and electronic engineering, kırıkkale university, kırıkkale, turkey email* : ahghby@gmail.com abstract – this paper concentrates on analyzing the performance of the two most important techniques of independent active and reactive power control of the doubly-fed induction generator used in a variable speed wind power conversion system. in the first technique, the independent control of the active and reactive power is based on the vector control technique by the orientation of the stator voltage space vector using pi controllers; the decoupling components are deduced along with the d, q axes; and the pi controllers' parameters are calculated from the mathematical model of the doubly-fed induction generator. hysteresis controllers are utilized to designing a direct power control technique. the performances of the studied control methods are tested and compared via simulation results. keywords: voltage oriented control, direct power control, dfig received: 13/07/2021 – accepted: 05/12/2021 i. introduction the main reason for the popularity of doubly-fed induction generators (dfigs) in wind power implementations is the requirement for relatively small power converters. (usually, 30% from the rated power of the machine) [1-2]. the scherbius scheme was introduced by the 20thcentury german engineer arthur scherbius that provides bidirectional power flow in the rotor circuit. cycloconverter-based power converter topologies joined between the stator and the rotor was informed [3-4]. however, these converters produce high harmonics in the rotor current returned to the stator. these disadvantages can be overcome by employing two separated converters, a rotor side converter (rsc) and a grid side converter (gsc), which are attached back-to-back in the rotor side [5]. to achieve control of the dfig system, the rsc and gsc can be commanded independently. in practical applications, the rsc can operate in complete separation from the gsc provided that a steady dc bus voltage is supplied by the gsc. also, in most schemes, the rsc operates commands are completely independent of the gsc by a separate control unit for each converter. one of the conventional control methods in the literature is the vector control that was utilized in the dfig system [6]. the vector control method employing pi controllers provides a less harmonic distortion and reduces the power ripple [7]. but it might be hard to set the pi gains correctly and its performance depends significantly on machine parameters. the vector control technique according to orientation frame can be classified as the stator flux-oriented control (foc) [8] or grid voltage-oriented control (voc) [9]. foc techniques depend on the accuracy of the stator resistance values, integration problems also exist and extra low-pass filters are applied to precisely determine the stator flux [10]. the influence of the value of stator resistance in the flux calculation can be neglected using the voc technique by adding a 90-phase variation to the voltage angle which can be obtained using a phaselocked loop (pll). this can produce an added coupling impact in active and reactive power (arp) control, which can be recompensed by applying extra controllers https://www.ijeca.info/ gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 14 in the external loop [11-12]. another control technique in the literature is direct torque control (dtc). the rsc provides the necessary magnetizing current in the rotor windings to produce the needed arp at the stator terminals. furthermore, since the electromagnetic torque is concerning to the active power, it is reported that the electromagnetic torque and stator flux reference values are replaced by arp reference values [13-14]. the direct power control (dpc) technique directly controls the arp of the stator by applying the suitable voltage vector to the rotor. the errors between the reference arps and the estimated arps are handled by hysteresis controllers [15-18]. the dpc is distinguished by its simple structure, fast dynamic response and robustness to parameter changes, and not need to use rotor current control loops, but its disadvantages are the highly variable switching frequency. in this study, first, the dynamic model of the dfig is proffered. then the vector control and direct power control techniques are studied. at last, the detailed simulation results are presented and discussed using matlab/simulink for both techniques. ii. the dynamic model of dfig the dynamic model of the dfig in the synchronous reference frame dq can be described by the following equations: sd sd s sd s sq sq sq s sq s sd d v r i dt d v r i dt                  (1)     rd rd r rd s r rq rq rq r rq s r rd d v r i dt d v r i dt                      (2) the stator and rotor fluxes are related to the current by: sd s sd m rd sq s sq m rq l i l i l i l i          (3) rd r rd m sd rq r rq m sq l i l i l i l i          (4) whereas the electromagnetic torque, produced by the machine, can be defined by the next equation:  em 3 2 m rd sq rq sd r s pl t l l        (5) where p is the pole pair number of the motor; sr and rr are the stator and rotor phase resistances, respectively; sl , rl and ml are the stator, rotor and mutual inductances, respectively; and  is the total leakage factor. furthermore, the arps of the stator and rotor can be determined according to the next equations:     s s 3 2 3 2 sd sd sq sq sq sd sd sq p v i v i q v i v i         (6)     r r 3 2 3 2 rd rd rq rq rq rd rd rq p v i v i q v i v i         (7) iii. voltage oriented control technique the principle of the voc consists of aligning the qaxis with the stator voltage space vector sv , which means that s sqv v and 0sdv  . from equation (1), since the stator is connected directly to the grid at constant ac voltage the stator flux is constant, thus, the term s d dt  is zero. furthermore, considering that the voltage drop in the stator resistance is slight; consequently, the angle between the stator flux and the voltage vector almost is 90 ,  as demonstrated in figure 1. figure 1. the phasor diagram of dq reference frame aligned with the stator voltage space vector thus, the equations (1,3,5 and 6) become as follows: 0 . sd sq s s v v        (8) 0 sd s sd m rd s sq m rq l i l i l i l i         (9) gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 15  em 3 2 m rq sd r s pl t l l      (10)     s s 3 2 3 2 sq sq sq sd p v i q v i       (11) from the aforementioned equations, it can be noted that the current rdi is proportional to the stator reactive power sq and that the current rqi is proportional to the active stator power sp . accordingly, from the dfig model by substituting equations (4) and (9) into equation (2), the rotor voltages can obtain as a function of stator flux and the rotor currents. rd rd r rd r r r rq di v r i l l i dt      (12) rq m rq r rq r r r rd r s s di l v r i l l i dt l         (13) consequently, by adopting similar pi controllers for both loops, and using the decoupling components between the dq axes. the equivalent closed-loop systems for currents can be represented as a second-order system by two poles and zero. appropriate gains of the pi controllers are chosen as shown in figure 2. figure 2. inner closed-loop of rotor current control by pi controllers figure 3. overall block diagram of vector control technique next, it is possible to inference the external closed-loop of power control with pi controllers by substituting the direct and quadrature rotor currents from equation (9) in equation (11). gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 16 s 3 2 m s s rq p rq s l p i c i l     (14) s 3 2 m s s s s rd q rd s m m l q i c i l l l                     (15) it can be observed that the abridged closed-loop systems provide a first-order system that can be set by determining the proper gains of the pi controller. consequently, the overall diagram of vector control for the dfig is demonstrated in figure 3. iv. direct power control technique in this study, the direct control technique for arp is carried out based on the stator flux directing. the switching table is defined based on the arp errors and the instantaneous location of the stator flux. the stator flux orientation method is adopted instead of the rotor flux orientation based on that the electrical components of the stator have less noise and harmonics compared to the electrical components of the rotor due to the discontinuous voltage applied to the rotor from the voltage converter rsc. however, from equation (6), it is not possible to know how the injection of different rotor voltage vectors can affect the creation of desired sp and sq . the stator voltage is fixed by the grid, whereas the stator current depends on the chosen rotor voltage vectors. consequently, by substitution of dfig model equations in equations (6) can be obtained follows the equations:     s _ _ s _ _ 3 sin 2 3 cos 2 xy m s s xy r xy r s s m s xy r s xy s r l p l l l q l l                           (16) where   is the phase shift between the stator and the rotor flux space vectors. from equation (16) can notice the stator arps can be controlled by modifying the angle between the stator and rotor flux vectors and their amplitudes. fig. 4 illustrates the terms  _ sinr xy  ,  _ cosr xy  , stator and rotor flux space vector’s locations. figure 4. phasor diagram of xy rotating reference frame with stator and rotor fluxes the stator flux space vector position in the rotor reference frame is split into six sectors as shown in figure 5. figure 5. distribution of the six sectors in xy rotating reference frame iv.1. voltage vector selection and hysteresis controllers in the dpc technique, the required rotor voltage vector directly is select from sp and sq errors, using hysteresis controllers. it determines the needed voltage vector to correct the errors in the controlled variables. the sq controller is based on a two-level hysteresis controller with qh hysteresis band, while the sp controller employs a three-level hysteresis comparator with ph hysteresis band. the schematic representation of these two controllers is shown in fig. 6. once the psu and qsu signals are defined employing the hysteresis controllers, together with the information about the stator flux vector position (i.e., the sector number), it can choose the rotor voltage vector from the switching table as illustrated in table 1. figure 6. active and reactive powers hysteresis controllers gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 17 table 1. switching table for dpc technique qs u 1 -1 ps u 1 0 -1 1 0 -1 sector 1 v5 v7 v3 v6 v0 v2 sector 2 v6 v0 v4 v1 v7 v3 sector 3 v1 v7 v5 v2 v0 v4 sector 4 v2 v0 v6 v3 v7 v5 sector 5 v3 v7 v1 v4 v0 v6 sector 6 v4 v0 v2 v5 v7 v1 iv.2. estimation of stator flux in xy rotating reference frame the stator flux components are estimated from measured stator voltage and currents’ α and β components according to the following equations:     0 0 t s s s s t s s s s v r i dt v r i dt                   (17) the transformation matrix with the rotor angular position is employed to make the stator flux components rotate in xy rotating reference frame         cos sin sin cos sx s sy s                          (18) thus, the stator flux space vector angle which determines the sector number is calculated according to fig. 5 by the following relationship _ arctan 2 s xy sy sx             (19) the control scheme of the dpc technique implemented in this study is demonstrated in figure7. figure 7. block scheme of the dpc technique v. results and discussion the validity of the studied schemes was verified by the simulations using matlab/simulink. the simulation was carried out under various operating conditions to show the studied techniques' performance. (a) (a) (b) (c) (d) gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 18 figure 8. voc technique responses for case 1 figure 9. dpc technique responses for case 1 the runge-kutta method was used to solve differential equations. sampling time is 𝑇𝑠= 20𝜇𝑠 and the rsc converter switching frequency was set as 5𝐾𝐻𝑧. the nominal parameters of the dfig are presented in table 2. both controls technique voc and dpc are simulated and compared in the next cases: case 1: the rotor speed is increased from subsynchronous to super-synchronous speed with ramp reference change of the active power. case 2: the rotor speed is set at sub-synchronous with the step reference change of the active power. in both cases, the reactive power is adjusted to zero to get a unity power factor at the grid side. table 2. parameters of doubly fed induction generator pn=1 kw p=2 pairs un=380 v rs=7.2 𝛀 ls=0.28 h rr=1.35𝛀 lm=0.118 h lr=0.075 h j=0.006 kg.m 2 fn=50 hz tl=6.7 n.m f=0.0046 nm.s v.1. the performance at sub-synchronous and supersynchronous speed operation with ramp reference change of active power. as shown in figure 8 and 9, the rotor speed is subsynchronous (w= 250 rad/s) then at t= 4 s it accelerating to become super-synchronous (w= 350 rad/s), also, the reference active power demand is increased from 100 to 800 watts at t= 5 s. from figure 8 (f and d) and figure 9 (f and d), it can be noticed the supremacy of the dpc technique in terms of response speed and reducing distortion occurring in the active and reactive power. furthermore, in both techniques, balanced stator currents are obtained by maintaining a constant frequency equal to the grid frequency as illustrated in figures 8 (b) and 9 (b). (c) (a) (b) (d) (f) (f) gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 19 v.2. performance at sub-synchronous speed operation with the step reference change of active power. in this test, a step variable reference active power is demanded at a sub-synchronous rotation speed. figures 10 and 11 show the response of the arp to both studied techniques. as noticed, the effectiveness and speed response of the dpc technique compared with the voc technique. it can be seen the overshoot in the active power response with voc technique and reactive power response variations according to active power variations. in the last comparison test, the total harmonic distortion (thd) of the stator current in each technique is evaluated by employing the fast fourier transform (fft) as seen in figure 12. it can be seen that the thd for the dpc technique (thd = 1.01%) is low when compared with the voc technique, and it’s due to the difference and difficulty in choosing the optimal parameter values for pi controllers in the voc technique. figure 10. voc technique responses for case 2 figure 11. dpc technique responses for case 2 figure 12. stator current fft analysis, (a) voc, (b) dpc after presenting the detailed simulation results indicating the superiority of the dpc technique, table 3 reviews the key differences between the voc technique and the dpc technique. table 3. performance evaluation between dpc and voc techniques indicators dpc voc dynamic response high low dependency on machine parameters very low high power ripples medium high switching frequency variable constant robustness medium low controllers tow hysteresis controllers four pi controllers control method directly controlled indirectly controlled by rotor currents park and clark transformations no need needed (a) (b) gufran nurettin et al ijeca-issn: 2543-3717. december 2021 page 20 vi. conclusion in this paper, the dpc and voc techniques of dfig in energy conversion systems were studied and simulated by matlab/simulink. first, the theory of vector control by the stator voltage space vector orientation and how to calculate the parameters of pi controllers for the internal and external loops based on the mathematical model of dfig was explained. second, the stator flux orientation method is adopted instead of rotor flux orientation for the dpc technique using hysteresis controllers because the electrical components of the stator have less noise and harmonics compared to the electrical components of the rotor due to the discontinuous voltage applied to the rotor from the voltage converter rsc. simulation results showed that the dpc technique presents a fast and good dynamic response and less harmonic distortion compared with the voc technique. moreover, the implementation of the dpc technique is simple and does not have the inherent complexity of the voc technique. additionally, extended studies of dfig's control technologies can be achieved using advanced controllers such as the sliding mode controller and the fuzzy logic controller. references [1] r. pena, j. c. clare, and g. m. asher, "doubly fed induction generator using back-to-back pwm converters and its application to variable-speed wind-energy generation," iee proceedings electric power applications, vol.143, issue 3, 1996, pp. 231–241. [2] r. pena, j. c. clare, and g. m. asher, "a doubly fed induction generator using back-to-back pwm converters supplying an isolated load from a variable speed wind turbine, " electric power applications, iee proceedings-, vol. 143, issue 5, 1996, pp. 380–387. [3] h. akagi and h. sato, "control and performance of a doubly-fed induction machine intended for a flywheel energy storage system," power electronics, ieee transactions on, vol. 17, issue 1, 2002, pp. 109–116. [4] p. g. holmes and n. a. elsonbaty, "cycloconverterexcited divided winding doubly-fed machine as a windpower convertor," electric power applications, iee proceedings b, vol. 131, issue 2, 1984, pp. 61–69. [5] a. tapia, g. tapia, j. x. ostolaza, and j. r. saenz, "modeling and control of a wind turbine driven doubly fed induction generator," energy conversion, ieee transactions on, vol. 18, issue 2, 2003, pp. 194–204. [6] t. noguchi, h. tomiki, s. kondo, and i. takahashi, "direct power control of pwm converter without powersource voltage sensors," ieee trans. ind. appl., vol. 34, issue 3, 1998, pp. 473–479. [7] h. nian, y. song, p. zhou, s. s. member, and y. he, "improved direct power control of a wind turbine driven doubly fed induction generator during transient grid voltage unbalance," ieee transactions on energy conversion, vol. 26, issue 3, 2011, pp. 976–986. [8] b. nait-kaci, m. l. doumbia, k. agbossou and a. yousif, "active and reactive power control of a doubly fed induction generator for wind applications," ieee eurocon 2009, st.-petersburg, 2009, pp. 2034-2039. [9] muller s, deicke m, de doncker rw, "doubly fed induction generator systems for wind turbines," ieee industry applications magazine, vol.8, issue 3, 2002, pp. 26-33. [10] pena r, clare jc, asher gm, " a doubly-fed induction generator using two back-to-back pwm converters and its application to variable speed wind energy system," iee, vol.143, 1996, pp. 231-241. [11] t. samina, s. ramalyer and a. b. beevi, "dynamic behavior of wind driven doubly fed induction generator with rotor side control for wind power application," 2017 international conference on energy, communication, data analytics and soft computing (icecds), chennai, 2017, pp. 2470-2475. [12] a. r. kumhar, "vector control strategy to control active and reactive power of doubly fed induction generator based wind energy conversion system," 2018 2nd international conference on trends in electronics and informatics (icoei), tirunelveli, 2018, pp. 1-9. [13] s. seman, j. niiranen, & a. arkkio, "ride-through analysis of doubly fed induction wind-power generator under unsymmetrical network disturbance." power systems, 21, ieee transactions, issue 4, 2006, pp. 17821789. [14] bakouri, anass, et al. "a complete control startegy of dfig connected to the grid for wind energy conversion systems." 2015 3rd international renewable and sustainable energy conference (irsec). ieee, 2015. [15] e. tremblay, s. atayde, and a. chandra, "comparative study of control strategies for the doubly fed induction generator in wind energy conversion systems: a dsp based implementation approach," sustainable energy, ieee transactions on, vol. 2, issue 3, 2011, pp. 288–299. [16] r. datta and v. t. ranganathan, "direct power control of gridconnected wound rotor induction machine without rotor position sensors," power electronics, ieee transactions on, vol. 16, issue 3, 2001, pp. 390–399. [17] s. massoum, a. meroufel, a. massoum, p. wira,"a direct power control of the doubly-fed induction generator based on the svm strategy," elektrotehniški vestnik, vol. 84, issue 5, 2017, pp. 235–240. [18] a. ben amar, s. belkacem, t. mahni," direct torque control of a doubly fed induction generator," international journal of energetica, vol. 2, issue 1, 2017, pp. 11–14. i. introduction vi. conclusion references ijeca-issn: 2543-3717. december 2021 page 01 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 07-12 simulation of different modes of heat transfer on a parabolic trough solar collector loubna benhabib 1* , yacine marif 2 , zakia hadjou belaid 3 , abdelmadjid kaddour 4 , boumediène benyoucef 1 , michel aillerie 5 1 urmer laboratory, abou bekr belkaid university, tlemcen, algeria 2 lenreza, kasdi merbah university , ouargla, algeria 3 macromolecules laboratory, abou bekr belkaid university, tlemcen, algeria 4unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria 5 université de lorraine, centralesupélec, lmops, f-57000 metz, france email*: loubnabenhabibhadjou@gmail.com abstractthe development of solar concentrator technology has just reached a very significant level. using reflectors to concentrate the sun's rays on the absorber dramatically reduces the size of the absorber, reducing heat loss and increasing its efficiency at high temperatures. another advantage of this system is that the reflectors are significantly less expensive, per unit area, than the flat collectors. to determine the performances of a cylindrical-parabolic concentrator, mathematical modeling of the heat balance on the absorber, the coolant, and the glass envelope was established using matlab. the system of equations obtained is solved by the finite difference method. the results for a typical day are the variation in the temperature of the heat transfer fluid, the absorber tube, and the glass envelope. thus, we examine the effect of the wind speed, flow rate on the temperature distribution of the coolant at the outlet. however, for a mass flow rate of the fluid of 0.1 kg / s, the outlet temperature of the fluid is 85 ° c with a thermal efficiency of 73%. excluding the energy absorbed by the absorber tube is 75% of the solar intensity received on the reflector. keywords: parabolic trough collector, solar thermal energy, simulation, heat transfer, solar concentrator. received: 26/04/2021 – accepted:26/06/2021 i. introduction renewable energies have experienced the first phase of development during the oil shocks of 1973 and 1978. then a period of decline after the counter-shock of 1986, before regaining a new lease of life in 1998 following the signing of the kyoto protocol, which predicts, in particular, a 5.2% drop in greenhouse gas emissions from wealthy countries over the period 2002-2012 compared to 1990 [1]. solar energy can be used to generate power using concentrated solar systems. it is based on spherical, parabolic or fresnel lens-based mirror concentrators [2], which have the principle of focusing the incident solar radiation in a point or a line. the conversion efficiency is high, and temperature can easily surpass 500 °c. these technologies offer a natural alternative to the consumption of fossil resources with a low environmental impact and a high potential for cost reduction, as well as the possibility of hybridization of these facilities, by utilizing direct solar radiation, which is considered the primary resource and is very significant on a planetary scale [3]. when it comes to the specific challenges of electricity generation, transmission, and distribution, alternative sources, as opposed to conventional ones, can be a feasible answer. in areas where electrical energy delivery is unreliable, including alternative energy generation sources, such as solar, can be a viable choice [4]. http://www.ijeca.info/ http://www.ijeca.info/ mailto:loubnabenhabibhadjou@gmail.com loubna benhabib et al ijeca-issn: 2543-3717. december 2021 0 several studies have been conducted to anticipate, analyse, and estimate the performance of parabolic trough collectors under a variety of weather conditions and configurations. a comprehensive review is presented, that examines various models and simulation approaches of ptcs. this study constitutes a complementary application contribution to parabolic trough concentrators [5]. according to the literature a detailed heat transfer solar receiver model has been performed [6]. the proposed models are based on the detailed analysis of one-dimensional or two-dimensional heat transfer processes assumed by trough collectors. other researchers [7] performed precise two-dimensional digital heat transfer of ptc using synthetic oil therminol vp1 as heat transfer fluid (htf). they came up with two software options based on the properties of the solar ptc they were using. the first was written in matlab and was used to calculate the annual solar energy collected on the absorber pipe using several tracking modes that were available in the area. because (ees) automatically detects all unknowns and groups of equations for the most efficient solutions, the second program code is written using a simultaneous equation solving software (ees) to evaluate the performance of the heat collector element (hce) [8]. figure 1. different heat transfer modes ii.1. incident radiation our study will focus on the equations of direct incident solar irradiance, as it is the resource of concentrating systems [9]. modeling is done on a horizontal plane using two models. the data considered for the simulation in the mediterranean countries provide from the site of tlemcen city having the following coordinates latitude 34.53 °, altitude 806m, longitude 1.33 ° [10] in the current approach, a simulation program will be developed under matlab to deal with the different modes of heat transfer in the concentrator absorber by determining the evolution of the system's temperature. different parameters are studied to explain their importance in the temperature variation. the results taken are for a sunny day of june 21 in the region of tlemcen, north-western algeria, and water as the heat transfer fluid. ii. material and methods the absorber was the essential element in the direct solar radiation is calculated according to the capderou model, and the expression gives it: [11] 𝐼𝑑 = 𝐼0. s0. 𝑠i𝑛ℎ𝑠. exp(−𝑇𝐿. 𝑚𝑎. 𝛿𝑅) (1) where ε0 represents the earth-sun distance correction, it is expressed as follows [12]: s = 1 + 0.034 * cos( 360 * (𝑁 − 2)) (2) 365 with hs is the sun elevation angle, n is the number of days, and 𝐼0 is the constant solar (1367w/m²) the atmospheric mass 𝑚𝑎 , as well as the rayleigh thickness δr, is given by [11, 12]: 𝑚𝑎 = [sin(ℎ𝑠 ) + 9.4 * 10−4(sin(ℎ𝑠) + 0.0678)−1.253]−(13) 𝛿−1 =6.6296 + (1.7513×𝑚𝑎 ) − (0.1202×𝑚2 ) + 𝑅 𝑎 composition of the cylindrical-parabolic concentrator, (0.0065×𝑚3 ) − (0.00013×𝑚4 ) (4) 𝑎 𝑎 whose role is to absorb the incident solar radiation for its conversion into heat before transmitted to the heat transfer fluid. we report in figure1 the diagram of the process explaining the heat flow exchanged between components. however, the heat exchange coefficients are considered as known while considering the following assumptions: • the transfer by conduction between the absorber and the glass is considered negligible. • the flow of the incompressible fluid is in a one dimensional direction. or the linke factor 𝑇𝐿is given by the expression [13]: 𝑇𝐿 = 𝑇0 + 𝑇1 + 𝑇2 (5) where: 𝑇0 = (2.4 − 0.9 * 𝑠i𝑛𝜑) + 0.1 * (2 + 𝑠i𝑛𝜑) − (0.2 * 𝑧) − (1.22 + 0.14 * 𝐴ℎ𝑒) * (1 − 𝑠i𝑛(ℎ𝑠)) (6) 𝑇1 = 0.89𝑧 (7) 𝑇2 = [0.9 + (0.4 * 𝐴ℎ𝑒)] * 0.63𝑧 (8) with z is altitude, φ is latitude and 𝐴ℎ𝑒 winter-summer alternation. however, the expression of the energy absorbed by the absorber is given by the expression: [14] loubna benhabib et al ijeca-issn: 2543-3717. december 2021 𝑎𝑚 a .ρ .cp . = 𝑞 + 𝑞 − 𝑞 (12) ab ab ab 𝑎𝑏𝑠 i𝑛𝑡 𝑢 𝑞𝑎𝑏𝑠 = 𝐴0. 𝐼𝑑. 𝛼0. 𝜌0. 𝛾. 𝐾 /𝐴0 = 𝐿 * w (9) the transmission-absorption coefficient 𝛼0is given according to the following expression [15]: ii.3. the heat transfer coefficients  heat transfer between glass envelope and atmosphere 𝘢0 = 𝖺ab.𝜏g 1−(1−𝖺ab).(1−𝜏g) (10) convection and radiation are two transfer techniques for as for the modified angle of incidence is given by [16]: k=1 − 3.84. 10−5. (𝜃) − 143. 10−6. (𝜃)² (11) ii.2. heat balance the incident solar energy absorbed is not entirely transmitted to the heat transfer fluid. some are dissipated in the form of thermal losses between the absorber and the glass envelope. figure 2 shows several heat transfer analyses between collector components and between the collector receiver and its surrounding environment. transferring heat from the glass enclosure to the atmosphere; convection requires wind. the coefficient of radiation is given by [17]: ℎ𝑟(𝑒𝑥𝑡) = sg. 𝜎. ((𝑇𝑠𝑘𝑦 + 273.15)² + (𝑇g + 273.15)²) * (𝑇𝑠𝑘𝑦 + 𝑇g + 546.3) (16) with the expression of the sky temperature [18]: 𝑇𝑠𝑘𝑦 = 0.0552𝑇1.5 (17) then the coefficient of convection is given by [19]: 1⁄6 2 𝖥 𝖥 1 1 ℎ𝑐(𝑒𝑥𝑡) = i 0.6 + 3.87 * i 𝑅𝑎𝑎 16 i i * 𝑎 i i 0.559 9⁄16 ⁄9i i 𝐷𝑔𝑒 [ [ (1+( 𝑃r𝑎 ) ) ] ] (18) • heat transfer between the absorber and the glass envelope convection and radiation are the two ways of heat transmission. the annulus pressure affects the convection mechanism. temperature variations between the outer absorber surface and the inner glass surface cause radiation. with the expression of the sky temperature [20]: ℎ𝑟(i𝑛) = si𝑛𝑡. 𝜎. ((𝑇𝑎𝑏 + 273.15)² + (𝑇g + 273.15)²) * (𝑇𝑎𝑏 + 𝑇g + 546.3) (19) figure 2. heat balance of the absorber with si𝑛𝑡 = 1 (20) ( 1 1−𝗌𝑔 𝐷𝑎𝑏𝑒 𝗌𝑎𝑏 + 𝗌𝑔 )*( 𝐷𝑔i ) then the coefficient of convection is given by :  for the glass envelope: ℎ = 2 𝑒ƒƒ (21) 𝑑𝑇 g g g 𝑑𝑡 𝑎𝑏𝑠.g i𝑛𝑡 𝑒𝑥𝑡  for the absorber pipe : 𝑐(i𝑛) with: 𝐷𝑎𝑏𝑒 .𝑙𝑛( 𝐷𝑔i ) 𝐷𝑎𝑏𝑒 𝑃𝑟𝑎 1⁄4 1⁄ a .ρ .cp . 𝑑𝑇 = 𝑞 − 𝑞 − 𝑞 (13) 𝑑𝑡 𝜆𝑒ƒƒ = 0.386 * 𝜆𝑎 * ( ) 𝑃𝑟𝑎+0. 61 * (𝑅𝑎𝑐) 4 (22) 𝐷𝑔i 4 𝑅𝑎 = (𝑙𝑛( 𝐷𝑎𝑏𝑒 )) * 𝑅𝑎  for the fluid: 𝑐 3 −3/5 −3/5 5 𝑒ƒƒ (23) a .ρ .cp .𝑑𝑇 + 𝑚 ....... 𝑑𝑇 = 𝑞 (14) 𝐿𝑒ƒƒ*(𝐷𝑎𝑏𝑒 +𝐷𝑔i ) whose: f f f 𝑑𝑡 𝑑𝑥 𝑢 𝐿𝑒ƒƒ = 𝐷𝑔i−𝐷𝑎𝑏𝑒 2 (24) 𝑞𝑎𝑏𝑠.g = 𝐴0. 𝐼𝑑. 𝛼g. 𝜌0. 𝛾. 𝐾 (15) the boundary condition: 𝑇g,0 = 𝑇𝑎𝑚; 𝑇𝑎𝑏,0 = 𝑇𝑎,𝑒; 𝑇ƒ,0 = 𝑇𝑒 (tam is the ambient temperature). 𝑅𝑎𝑒ƒƒ = 𝐺𝑟𝑎 * 𝑃𝑟𝑎 (25) • heat transfer between the fluid and the absorber the flow type affects convective heat transfer from the inside surface of the absorber pipe to the fluid. we consider the case of turbulent flow [21] and is given by: loubna benhabib et al ijeca-issn: 2543-3717. december 2021 ℎ𝑢 = ƒ*𝑁𝑢ƒ 𝐷𝑎𝑏i 5 𝐷𝑎𝑏i 2⁄3 (26) moreover, the solar power absorbed by the absorber tube reached 680w / m², figure 4, which explains the existence of heat losses between the glass envelope and the absorber tube. these losses cause a decrease in the with: 𝑁𝑢ƒ = ( 8 ).(𝑅𝑒ƒ−1000).(1+( 𝐿 ) 2 ).𝑃𝑟ƒ . ( 𝑃𝑟ƒ ) 𝑃𝑟𝑎𝑏 0.11 rate of energy absorbed, which is of the order of 75%. 1+12.7.√ ƒ .(𝑃𝑟 ⁄3−1) 8 ƒ knowing that: 5 = (1.84. log(𝑅𝑒 ) − 1.64) −2 for 𝐷 < 𝐿 and; (27) 1000 800 ƒ 𝑎𝑏i 5 = (1.8. log(𝑅𝑒 ) − 1.5) −2 for 𝐷 > 𝐿, ƒ 𝑎𝑏i 600 the physical proprieties of fluid (water) are considering variants. iii. solution procedure, results and discussions 400 200 0 matlab did the programming of these equations. we used the finite difference method to solve these equations. the process consists of giving a value of the variable and recalculating this variable with the equation, and finally, we compare the two deals. depending on the desired precision, if the difference between the two calculated and proposed values is less than the fixed accuracy, this value is taken. otherwise, the second value is taken, and the calculations are repeated until the difference between these two values becomes inferior to precision. the characteristics of the solar ptc are mentioned in table.1 table 1. characteristics of the simulated ptc 700 600 500 400 300 200 100 0 4 6 8 10 12 14 16 18 20 22 tlo (h) figure 3. variation of the solar intensity 4 6 8 10 12 14 16 18 20 22 tlo (h) figure 4. variation of the absorbed energy moreover, figure 5 shows the variation in the outlet temperatures of the fluid, absorber and glass envelope. it is noted that the fluid outlet temperature is 55 ° c for a mass flow rate of 0.2kg / s. on the other hand, according to figure 6, it is deduced that the outlet temperature of the fluid varies as a function of the mass flow rate or the temperature increases by decreasing the latter. following the use of the capderou model for the calculation of the solar intensity and based on a solar tracking system for our solar system, we notice that the solar intensity at the level of the tlemcen region and for a day sunny, reaches 900w / m²as shown in figure 3. 21 juin p a b s ( w h /m ²) s o la r i n te n s it y ( w /m ²) absorber length (l) 7.8m collector width (w) 5m focal length (f) 1.84m the absorber external diameter (dabe) 0.07m the absorber internal diameter of (dabi) 0.066m the glass external diameter (dge) 0.115m the glass internal diameter (dgi) 0.109m thermal conductivity of the absorber (λab) 54w/mk thermal conductivity of the glass (λv) 1.2w/mk absorption of the absorber (αab) 0.906 glass transmissivity (τg) 0.95 transmissivity-absorbance factor (α0) emissivity of glass (𝗌𝑔) reflection of reflector (𝜌0) interception factor (𝛾) 0.864 0.86 0.93 0.92 loubna benhabib et al ijeca-issn: 2543-3717. december 2021 tv tab tf tf (°c) 90 in what follows figure 7, shows the variation of the thermal efficiency as a function of the temperature of the 80 collector which is equal to 73%. this efficiency helps to 70 control the reliability of our system since it is the ratio 60 between the useful flux and the power absorbed through the absorber tube. we note that the thermal efficiency is 50 close to the experimental, whose value is 73.68% in the 40 air in the annular space and validated by snl. this 30 difference only has to let us think of the existence of thermal losses. 20 10 8 10 12 14 16 18 20 22 tlo (h) figure 5. variation of the outlet temperature 90 80 70 60 50 40 30 20 10 8 10 12 14 16 18 20 22 tlo(h) figure 6. variation of the outlet fluid temperature for different mass flow rate iv. conclusion our study relates to the study of the various existing heat transfers for a ptc sensor. for this, a mathematical simulation in matlab language is carried out to solve the nonlinear equations. our results are based on the study of outlet temperatures and influencing parameters. among those proposed the mass flow rate of the fluid shows an important parameter introducing into the variation of the outlet temperature or we have seen that the water outlet temperature reaches a value of 85 ° c for a flow rate of 0.1 kg / s. however, the energy absorbed is 75% relative to the solar intensity received on the reflector. concerning the thermal efficiency which explains the rate of the useful flux linked to the heat transfer fluid, it is 73% for our system under the conditions of the tlemcen region for a sunny day. in contrast, the wind speed turned out to be negligible. in addition, the sun tracking system is essential and necessary for the operation of the ptc as it only uses direct solar radiation. 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 -0,1 25 30 35 40 45 50 55 60 outlet references [1] j. d. balcomb, r. w. jones, c. e. kosiewicz, g. s. lazarus, r. d. mc farland, w. o wray, « passivesolar design handbook », volume 3, american solar energy society, 1982. [2] s. mihoub, effect of design parameters on the performance of dsg linear fresnel solar power plant, int. j. energy clean environ, vol 22, no 2, 2021, pp. 65 81. [3] k. ogilvie, ‘l’abc des technologies de l’energie renouvelable’, pollution probe, canada, september 2003 [4] s. quezada-garcia, h. sanchez-mora, a.m. polor.i labarrios,. cazares-ramirez, modeling and simulation to determine the thermal efficiency of a parabolic solar trough collector system, case studies in thermal figure 7. variation of collector thermal efficiency compared to the outlet temperature of the fluid engineering, vol 16, 2019, pp.100523. df=0,1kg/s df=0,2kg/s df=0,5kg/s r th t fl u id ( ° c ) o u tl e t o u tl e t t e m p e r a tu r e s ( ° ) loubna benhabib et al ijeca-issn: 2543-3717. december 2021 [5] i.h. yilmaz, a., mwesigye, modeling, simulation and performance analysis of parabolic trough solar collectors: a comprehensive review, applied energy, vol 225, 2018, pp. 135-174. [6] r. forristall, heat transfer analysis and modeling of a parabolic trough solar receiver implemented in engineering equation solver. national renewable energy laboratory (nrel), golden, 2003. [7] charlain-joel ngangoum keou, donatien njomo, vincent sambou « two-dimension numerical simulation of parabolic trough solar collector: far north region of cameroon," march 31, 2017. [8] loubna benhabib zakia hadjou, belaidabdellah benyoucef theoretical study and modeling of a parabolic trough solar concentrator, algerian journal of materiels chemistry, vol 4, , 2021, pp. 7-14. [9] a. ferrière et g. flamant. ‘captation, transformation et conversion de l’energie solaire par les technologies à concentration’. imp-cnrs, centre du four solaire, france, 2004. [10] http://www.infoclimat.fr / 10/20/2021. [11] m. capderou, theoretical and experimental models, solar atlas of algeria (in french), tome 2. vol 1. algeria: university publications office; 1987. [12] f. kasten, the linke turbidity factor based on improved values of the integral rayleigh optical thickness, solar energy. vol 56, n°3, 1996, pp. 239-244. [13] m. capderou, ‘atlas solaire de l’algérie. modèles théoriques et expérimentaux’, vol. 1, t1, office des publications universitaires, epau, algérie, 375 p., 1987. [14] j.a. duffie and w.a. beckman, 'solar engineering of thermal processes', john wiley & sons, new york, 1991. [15] s. quoilin, concentrator solar power plants (in french), faculty of applied sciences". university of liége; 2007. [16] a. kalogirou soteris, solar thermal collectors and applications, prog energy combust sci, vol 30, 2004, pp. 231–95. [17] j.a. duffie , w.a. beckman, solar engineering of thermal processes. 2nd edition, madison, new york; john wiley & sons, hoboken, 2013. [18] o. garcia-valladares, n. velazquez, numerical simulation of parabolic trough collector: improvement using counter flow concentric circular heat exchangers. int j heat mass transf, vol 52, no (3–4), 2009, pp. 597–609. [19] belkacem agagna, arezki smaili, an improved model for predicting the performance of parabolic trough solar collectors. august 2018. [20] a. ratzel, c. hickox, d. gartling, techniques for reducing thermal conduction and natural convection heat losses in annular receiver geometries. journal of heat transfer, vol 101, 1979, pp. 108-113. [21] v. gnielinski, on heat transfer in tubes. int j heat mass transf, vol 63, 2013, pp. 134–40. . http://www.infoclimat.fr/ i. introduction ii. material and methods  for the glass envelope:  for the absorber pipe :  for the fluid: iii. solution procedure, results and discussions iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 30-35 ijeca-issn: 2543-3717. december 2019 page 30 economic perspective in the production of copper nanowire using amino acids as capping agent puspa sari dewi, asep bayu dani nandiyanto * departemen pendidikan kimia, fakultas pendidikan matematikadan ilmu pengetahuan alam, universitas pendidikan indonesia, indonesia email*: nandiyanto@upi.edu abstract –the purpose of this study is to evaluate the economic feasibility of making copper nanowire using amino acids as a capping agent. the evaluation was conducted from two perspectives, namely engineering analysis and economic evaluation using parameters such as gross profit margin, payback period, breakeven points, and net present value. an economic evaluation was also carried out comparing the use of amino acids glycine, lysine, proline, and alanine to find out which amino acids were more profitable in the production of copper nanowire. furthermore, the evaluation is done by estimating the ideal situation and several other state assumptions such as changes in raw material prices, labor costs, and also income tax. from the results of this study, glycine is known as the most profitable amino acid to be used in this process. in addition, by using glycine as an ideal condition, based on the results of the evaluation of all parameters, this project is classified as prospective to do. although further studies must be carried out to develop this project, this study can be the basis for developing new methods of making copper nanowire on a large scale. keywords: copper nanowire, economic evaluation, amino acid as capping agent received: 27/11/2019 – accepted: 25/12/2019 i. introduction copper nanomaterial is a material that is well known as a material that has many uses in various fields, including in the areas of catalysis [1], biomedicine [2], electronics, and sensors [3]. copper nanowire is specifically used in electronics as a transparent conductor of the future replacing ag nanowire [4]. copper nanowire is a very promising substitute for ag nanowire due to the difference in conductivity between copper and ag which is the best conductivity material, only 6%, with greater availability in nature[5]. due to its diverse uses, a wide variety of cu nanowire preparation techniques have been developed. the synthesis of cu nanowire is usually based on the principle of reducing copper ions to copper with the help of surfactants or capping agents. some cu nanowire preparation methods that have been carried out are wet chemical reduction methods [6], chemical vapor deposition [7], template-assisted syntheses [8], and electronic deposition [9]. surfactant or capping agent is an important aspect in the synthesis of nanomaterials to stabilize the cu that is formed to form the desired nanomaterial with the appropriate dimensions. in general, there are two types of capping agents for the formation of cu nanowire, namely are from the group of amines and carboxylic acids. agents with amine function include ethylenediamine, hexadeclyamine, and oleylamine. while agents with carboxylic acid groups are oleic acid, lactic acid, and glycolic acid [5]. in the literature [5], a new cu nanomaterial preparation method is developed using amino acids as a capping agent because it has an amine group and a carboxylic acid group. the results of the literature state that the use of amino acids glycine, alanine, lysine, and proline can produce cu nanowire that is good and homogeneous. the use of amino acids as a capping agent is interesting because it uses materials that are environmentally friendly, versatile, and low cost. but until now, there has been no literature that does economic valuation of the method to see its potential to be carried out on an industrial scale. therefore, this study was conducted to analyze the method in the literature [5]and evaluate the economy from an economic perspective in the production of copper nanowire using amino acids as capping agents to see its feasibility if scaled-up to the method. abder image placée puspa sari dewi et al ijeca-issn: 2543-3717. december 2019 page 31 evaluation is carried out by looking at the project from an engineering and economic perspective. in this study also carried out a comparison of economic evaluations of the use of glycine, lysine, alanine, and proline to determine the amino acids that are most suitable for use on an industrial scale, which are then used as ideal conditions. several other evaluations were conducted, namely economic evaluation in ideal conditions, evaluation with variations in raw material prices, variations in labor costs, and variations in income tax to see the effect of various aspects of the project's cumulative net present value. ii. method ii.1. theoretical synthesis of cu nanowires copper nanowire can be synthesized by reducing copper ions in an alkaline solution, with the help of amino acids as capping agent. copper nanowire synthesis in this paper was adopted from the paper [5]. synthesis begins by adding 15m naoh solution to the copper nitrate solution in water, then adding the selected amino acid as a capping agent, and 35% hydrazine. the mixture is then stirred slowly at a heating temperature of 80° c. this process will produce a color change from blue to white then to brick red. cu nanowire will begin to appear and float to the top layer of solution. after that, the suspension is filtered and the filtrate is washed with water, and then dried with a vacuum dryer. the reaction is carried out following the scheme in figure 1 below. chemical reactions that occur in the process of cu nanowire synthesis are as follows: 2cu(no3)2 + 4naoh + n2h4 2cu + n2 + 4nano3 + 4h2o figure 1. reaction flow chart ii.2. engineering perspective evaluation an evaluation from an engineering perspective was conducted to examine the feasibility of cu nanowire production with this method in terms of engineering. this evaluation is carried out based on the process flow diagram scheme in figure 2. the first process is carried out by dissolving sodium hydroxide and copper nitrate in water in different mixers. the water used is river water that has been treated so that it becomes distilled water. then by using a pump, the two solutions then entered into the reactor with a heater, then also added the selected amino acid and hydrazine. heating the reactor for this reaction is done by the heat exchanger method . after being reacted , the mixture is then filtered to separate the suspension and the solution . the suspension is then dried, ground, separated, and then copper nanowire is obtained . evaluation from the engineering side is based on paper [5] with the following assumptions , including all chemical compounds used in the production of cu nanowire are scaled up to 150 ,000 times the amount stated in the literature [5]. detailed are:  the reaction conversion rate is assumed to be 100%  there was a mass loss of the chemical compound transferred by 5% of the initial mass in each transfer process  cu nanowire obtained is as much as 80% of the stoichiometric calculation because it is assumed that loss occurs in each process of removal of nanowire cu after synthesis  the water used in the production process is purified, deionized water obtained from the water treatment plant provided at the plant figure 2. process flow diagram of copper nanowire production ii.3. economic evaluation the economic feasibility study conducted is to examine the feasibility of cu nanowire production by analyzing the prices of production components such as raw materials, equipment, utilities, and labor and its relation to the feasibility of large-scale production. the prices analyzed were obtained from various online shopping sites such as alibaba and tokopedia. the data was then calculated mathematically to produce a variety of economic evaluation parameters as follows: 1) gpm (gross profit margin) to predict economic evaluation roughly, 2) pbp (payback period) to estimate the time needed until profits are obtained, 3) bep (break-even point) to get the minimum production capacity abder image placée puspa sari dewi et al ijeca-issn: 2543-3717. december 2019 page 32 4) cnpv (cumulative net present value) to predict and evaluate project conditions as a function of time (in years). the evaluation from the economic side is carried out with the assumptions below:  the price of all equipment is adopted from several online buying and selling sites such as alibaba, tokedia, and bukalapak  raw material prices have been adopted from several online selling sites on alibaba from xi'an manufacturer huilin bio-tech. the price of each chemical compound used in this evaluation is as follows: cu(no3)2 rp61,110 per kg, naoh rp7,070 per kg, hydrazine 35% rp42,635 per kg, glycine rp71,058 per kg, alanine rp141,432 per kg, lysine rp183,861 per kg, proline rp141,432 per kg.  the period of production evaluated is 10 years  in one day of production, cu nanowire produced 1.72 kg  utility cost is rp. 1,467 / kwh. the amount paid in a year is rp. 49,291,200  labor wages in ideal conditions for 10 people are rp. 720,000,000 per year  all prices obtained in usd are converted to idr with a conversion value of 1 usd = idr 14,150  income tax under ideal conditions is 10%  discount rate is assumed to be 15% iii. result and discussion iii.1. engineering perspective this synthesis is carried out with the principle of reducing cu (no3)2 in basic conditions to cu. the formation of nanowire is carried out with amino acids that function as capping agents. in this paper, we evaluate the use of four different amino acids that can form cu nanowire, namely glycine, lysine, alanine, and proline. the reducing agent in this reaction is hydrazine 35% with 15m naoh to make alkaline condition. all of the reducers are reacted in a reactor with a heater to form a brick red solution with a copper suspension. the suspension is then filtered using a vacuum filter and then dried using an oven dryer. the dried copper is then through a grinding process to form the final product, copper nanowire. iii.2. economic evaluation of feasibility use of various amino acids as capping agent in preparation of cu nanowire the graph in figure 3 shows the cnpv / tic of lifetime with four different kinds of amino acids as capping agents, namely glycine, alanine, lysine, and proline. this variation is done with the assumption that the production capacity of each variation is the same, but with different raw material prices according to the price of each amino acid, so it can be seen that the most profitable amino acids to be used as a capping agent in cu nanowire production . on all four curves, there is a decrease in profits from 0 to about 2 years. this decrease occurred at an early stage of production due to initial costs such as costs for equipment, construction costs, and starting-up fees. in all circumstances, an increase in profit begins in the second year as the production process begins. after 2.5 years, there was a return on investment cost or a payback period. by comparing the four curves that represent economic evaluations of the use of four different amino acids, it can be seen that the use of a glycine capping agent is more beneficial than other amino acids. meanwhile, the profitability of using alanine and proline did not differ significantly, and the use of lysine was less beneficial than the other three amino acids. the use of different amino acids will cause changes in variable costs due to differences in the price of raw materials used and differences in the amount. raw material prices greatly affect the variable costs that will affect the profitability of this project [10]. the difference in quantity of amino acids due to the amount used is in the same number of moles, but due to different molecular masses, the quantity of amino acids in kilograms is also different. in molecular mass, glycine is the lightest amino acid compared to the other three amino acids, so the price of raw material using glycine is relatively lower than other amino acids. figure 3. cnpv / tic graph for lifetime with various amino acids as a capping agent for making cu nanowire iii.3. evaluation of ideal conditions the graph in figure 4 shows the curve of the npv / tic c relationship to lifetime under ideal conditions using glycine as a capping agent. from the picture cnpv / tic changes from year to year for ten years of production. decrease in profits occurred from 0 to about 2 years. this decrease occurred in the early stages of production because of the initial cost of the project. increased profits began do occur in the second year as the production process began. after 2.5 years, there was a return on investment cost or a payback period. the analysis was also carried out by calculating several economic evaluation parameters contained in puspa sari dewi et al ijeca-issn: 2543-3717. december 2019 page 33 table 1. all economic evaluation parameters showed positive and promising results. gpm, bep, and cnpv final year show that this project is very promising in terms of revenue. pbp for the capital market standard of usd 250,000 in indonesia usually takes 1-2 years so, with this project investment of 300,000 usd, this project is still considered competitive. irr for a 10-year project period is 191%, so that the annual irr is estimated to reach 19.1%. this irr value is classified as high and also will not create conflict with bank indonesia interest which reaches 5-6%[11]. based on this analysis, the cu nanowire synthesis project with glycine as a capping agent was declared profitable to be carried out on an industrial scale. figure 4. cnpv/tic graph to lifetime for ideal condition table 1. economic evaluation parameters in ideal conditions economic evaluation parameter value gpm/year rp40,662,601,314 pbp 2.5 year bep 10429.31 units final year cnpv rp101,295,984,748 irr 191% iii.4. economic evaluation with variations in raw material prices the graph in figure 5 shows the cnpv / tic relationship curve to lifetime with a comparison of several different raw material values. five variations in the value of raw material were carried out, namely curves under ideal conditions, raw material values varied by -100%, -50%, + 50%, + 100% of the value of raw material in ideal conditions. this variation is done with the assumption that the production capacity in each variation is the same as the production capacity under ideal conditions, but with different raw material prices. this evaluation was conducted to analyze the effect of changes in raw material prices on the profits of cu nanowire production. cnpv / tic value changes from year to year. there was a decrease from 0-2 in all variations, according to the curves under ideal conditions. this decrease occurred because of the initial capital condition carried out before the production process began. in all variations, the profile began to be generated in the second year. by comparing the five different raw material price conditions in figure 5, it can be realized that this project is still profitable to do if the production is carried out with raw material prices of -100%, -50%, + 50%, + 100% of the value of raw material in ideal conditions. however, the difference is seen in the rate of increase in cnpv / tic annually. from the graph, it can be concluded that the greater the price of raw material used, the rate of increase of cnpv / tic is slower. this means that with the price of raw materials increasing, the rate of profit income decreases. this happens because raw material is closely related to overall production costs. with the same number of sales, an increase in production costs will reduce profits. with the production capacity and sales that remain, an increase in production costs will reduce profits. the increase in raw material prices has a negative impact on this project [12]. however, this evaluation is also known that the project is still profitable to do even if the price of raw materials is greater 100% of the price of raw material on condition the ideal. figure 5. cnpv/tic graph with variations in raw materials iii.5. economic evaluation with labor cost variations the graph in figure 6 shows the cnpv / tic relationship curve to lifetime with a comparison of several different labor cost values. five variations in the value of labor cost were carried out , namely the curve under ideal conditions, the value of raw material varied by + 50%, + 100% , + 150%, + 200% of the value of labor cost under ideal conditions. this variation is done with the assumption that the number of workers in each variation is equal to the number of workers in ideal conditions, namely 10 people, but with different salary prices , so that it can be seen the effect of changes in labor cost prices on cu nanowire production profits. cnpv / tic value changes from year to year. there was a decrease from 0-2 in all variations, according to the curves under ideal conditions. this puspa sari dewi et al ijeca-issn: 2543-3717. december 2019 page 34 decrease occurred because the initial cost of setting up the project carried out before the production process begins. in all variations, ranging generated profit in the year to 2. from the chart on figure 6, it is known that the rate of increase of cnpv / tic will decrease along with the increase in labor costs incurred. this happens because labor cost is one aspect of production costs related to profits derived from the project. however, despite the decline in the rate, it can be concluded that the change in the price of labor cost does not have a significant effect on the rate of increase cnpv / tic. figure 6. cnpv/tic graph with variations in labor cost iii.6. economic evaluation with variations in income tax the graph in figure 7 shows the cnpv / tic relationship curve to lifetime with a comparison of several different income tax values. this variation is done to see the impact of external conditions, namely taxes, which can affect this project. five variations in the value of income tax were made, namely 25%, 50%, and 75% with income tax under ideal conditions of 10%. this variation is done with the assumption that the production capacity is the same, but with a different amount of income tax. cnpv / tic value changes from year to year. there was a decrease from 0-2 in all variations, according to the curves under ideal conditions. this decrease occurred because the initial cost of setting up the project carried out before the production process begins. in all variations, profits start to be generated in the second year. from the chart in figure 7, it is known that the rate of increase of cnpv / tic will decrease along with the increase in income tax. income tax has a significant effect on the cnpv / tic rate so that there is a difference in payback period that is different in each scenario. in ideal conditions and 25% income tax conditions, the payback period occurs before the 2.5th year. in the 50% income tax condition, the payback period occurs after the 2.5 year and in the 75% income tax condition, the payback period occurs in the 3rd year. from the graph it is known that ideal conditions are the most profitable conditions. it also appears that the increase in tax will reduce revenue and also have an impact on pbp which is getting longer to be achieved. this occurs because the incoming cash flow will be reduced due to truncated by the income tax incurred thereby reducing incoming profit [11]. figure 7. cnpv/tic graph with variations in income tax iv. conclusion based on the analysis that has been done, the copper nanowire production project using amino acids as a capping agent, in terms of engineering and economics, is a prospective project. the results of comparative analyzes with various amino acids show that the use of glycine is more profitable compared to the use of alanine, proline, and lysine. by using glycine as a capping agent in economic analysis under ideal conditions, analysis of some economic parameter values shows a positive value. so this project can be said to be prospective and very profitable. references [1] y. liao, g. yu, y. zhang, t. guo, f. chang, and c. j. zhong, “composition-tunable ptcu alloy nanowires and electrocatalytic synergy for methanol oxidation reaction”, ournal of physical chemistry c, vol. 120, no. 19. 2016. [2] b. maria, “single-crystalline copper nanowires produced track membranes”, advanced materials no. 1, pp. 1999–2002, 2001. [3] h. xiang, t. guo, m. xu, h. lu, s. liu, and g. yu, “ultrathin copper nanowire synthesis with tunable morphology using organic amines for transparent conductors”, acs appl. nano mater., vol. 1, no. 8, pp. 3754–3759, 2018. [4] v. b. nam and d. lee, “copper nanowires and their applications for flexible, transparent conducting films: a review”, nanomaterials, vol. 6, no. 3, 2016. [5] j. c. yu, f. g. zhao, w. shao, c. w. ge, and w. s. li, “shape-controllable and versatile synthesis of copper nanocrystals with amino acids as capping agents”, nanoscale, vol. 7, no. 19, pp. 8811–8818, 2015. [6] j. tanori and m. p. pileni, “control of the shape puspa sari dewi et al ijeca-issn: 2543-3717. december 2019 page 35 of copper metallic particles by using a colloidal system as template”, langmuir, vol. 13, no. 4, pp. 639–645, 1997. [7] y. zhao, z. zhang, y. zhang, y. li, z. he, and z. yan, “large-scale synthesis of cu nanowires with gradient scales by using ‘hard’ strategies and size effects on electrical properties”, cryst eng comm, vol. 15, no. 2, pp. 332–342, 2013. [8] c. f. monson, a. t. woolley, “dna-templated construction of copper nanowires,” nano lett., vol l. 3, no 3, pp. 359–363, 2003. [9] h. wu, “electrospun metal nanofiber webs as high-performance transparent electrode”, nano lett, vol. 10, no. 10, pp. 4242–4248, 2010. [10] b. prabowo, t. khairunnisa, a.b.d. nandiyanto, “economic perspective in the production of magnetite ( fe 3 o 4 ) nanoparticles by coprecipitation method ”, world chemical engineering journal , vol . 2, no . 2, pp . 1–4, 2018. [11] a. b. d. nandiyanto, “cost analysis and economic evaluation for the fabrication of activated carbon and silica particles from rice straw waste”, journal of engineering science and technology , vol. 13, no. 6, pp. 1523–1539, 2018. [12] f. nandatamadini, s. karina, a.b.d. nandiyanto, nandiyanto, “feasibility study based on economic perspective of cobalt nanoparticle synthesis with chemical reduction method”, cakra kimia vol. 7, pp. 62-68, 2019. i. introduction ii. method iii. result and discussion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 31-36 . http://dx.doi.org/10.47238/ijeca.v5i1.120. june 2020 page 31 extraction of the electrical parameters of the au/insb/inp schottky diode in the temperature range (300 k425 k) ali sadoun 1 , imad kemerchou 2,3 1 applied microelectronics laboratory, djillali liables university of sidi bel abbes, algeria 2laboratory of analysis and control of energy systems and networks, university thelidji amar of laghouat, algeria 3materials science and engineering program, state university of new york at binghamton, binghamton, new york 13902, usa e-mail: 3ali39@gmail.com abstract – in this work, we have presented a theoretical study of au/insb/inp schottky diode based on current-voltage (i-v) measurement in the temperature range ( 300 k425 k). electrical parameters of au/insb/inp such as barrier height (φb), ideality factor and series resistance have been calculated by employing the conventional (i-v), norde, cheung and chattopadhyay methods. measurements show that the schottky barrier height (sbh), ideality factor and series resistance, rs for au/insb/inp schottky diode in the temperature range (300 k–425 k) are 0.602-0.69ev, 1.683-1.234 and 84.54-18.95 (ω), respectively. these parameters were extracted using atlassilvaco-tcad logical. keywords: cheung and chattopadhyay methods, schottky barrier, schottky diode, sbh, silvaco. received: 09/04/2020 – accepted: 20/06/2020 i.1. introduction semiconductors of the (iii-v) family have important applications in the field of electronics and optoelectronics. recently, (iii-v) semiconductors have received a great deal of attention for the fabrication of microwave devices as well as integrated circuits used in modern high-speed optical communication systems [1-4]. among the most widely used iii-v compounds are gan, gaas, gap, and inp, because of their band gap to their wide band gaps, stability at high temperatures, electron mobility, hardness, low iconicity and high terminal conductivity [4-8]. inp binary compound belongs to a family of iii-v semiconductors which is widely used in the manufacture of electronic components such as schottky diode (ms), metal-isolate-semiconductor (mis) structure, mos, transistor,….etc [9-12]. inp binary compound is a direct band gap semiconductor with eg = 1.423 ev and lattice parameter a= 5.869 at 300 k [6]. this binary is a promising material for detectors in the long-wavelength spectral region, light emitters, solar cell application, and microwave field-effect transistors [2, 1316]. on the other hand, the inp binary compound has received a great deal of attention for the fabrication of schottky diodes (metalinp). a study have investigated the forward bias current-voltage ( i v) characteristics of au/n-inp schottky barrier diodes (sbds) in the temperature range of 160-400 k but by using atlas device simulator of the software silvaco-tcad, have simulated the (i–v) and (c–v) characteristics of the au/n-inp schottky as a function of the temperature range 200–400 k [17,18]. more recently work have analyzed the microstructural, chemical and elemental composition properties of cuo/n-inp junction using x-ray diffraction (xrd), x-ray photoelectron spectroscopy (xps) and energy-dispersive x-ray spectroscopy (edax) techniques [19]. another experience have prepared graphite/inp schottky diode and analyzed their electrical characterization, using (i–v–t) and (c–v) methods [20,21]. this work aims to present the current-voltage (i– v) measurement for au/insb/inp schottky diodes in the temperature range (300 k425 k). the surface of the inp is restructured by an insb’s thin film of several monolayers. electrical characteristics of au/insb/inp schottky diodes, such as ideality factor (n), barrier height, and series resistance (rs) were investigated using (i-v), norde, cheung and chattopadhyay methods. mailto:3ali39@gmail.com ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 32 material and method ii. 1. current-voltage (i-v) method the effect of the diode resistor can be modeled by a series combination of a diode and a resistor (rs) through which the current flows. in addition, in the case, the ideal diode the value of the ideality factor equals 1 while for the no ideal diode the value is superior to 1 (n >1 ). in the case of the schottky diode, assuming that the current is due to a thermionic emission (te), the relation between the applied forward bias and the current can be given by [22-25]. ……...…(1) (1) here, ,n, k, and t present the reverse saturation current, the ideality factor, the boltzmann constant, the absolute temperature in kelvin, respectively. for the applied forward voltage (v > 3kt/q), the equation (1) can be written as [22-25]: …………………………………...(2) we could find the value of ( i0) by the plot ln (i) versus (v) at v = 0 volts. then, by replacing the calculated (i0) value in the equation (2), we could find the schottky barrier height (φb). the ideality factor value can be extracted from the linear region of (ln (i) -v) curve (the straight line of the curve). ………………...……….(3) (3) where a is the rectifier contact area, (φb) is the schottky barrier height, the value of (φb) can be deducted directly from i–v curves if the effective richardson constant is known [22]. is the richardson constant ( =9.4 a/cm 2 k 2 for n-inp [26]). the voltage (v) across the diode can then be expressed in terms of the total voltage drop v across the series combination of the diode and resistor. the value of n for an ideal diode is e is equal to one. high values of n can be attributed to the presence of the interfacial thin layer and a wide distribution of low-schottky barrier height patches (or barrier inhomogeneities) [27]. it can also be described and expression of the voltage (v) across the diode can then out of the total voltage drop (v) across the series combination of the diode and resistor, out of which the current flows, it can be composed or formed the effect of the diode resistance can be modeled with a series combination of a diode and a resistor rs [27]. ii. 2. cheung method the schottky barrier height (φb), the ideality factor , and the series resistance (rs) can be calculated from a second method called cheung and cheung [28]. in this method, the series resistance (rs) and the ideality factor are determined by the following functions [28]: ………………..…...(4) also, schottky barrier height can be defined by cheung’s relation [28]: …....(5) ii. 3. norde method alternatively, another method called norde approximation [29] can be used to calculate the two parameters that are the series resistance and the barrier height of au/insb/inp structure. the norde approximation is defined as [29]: ……….……….. ………..…(6) here, is an integer (dimensionless) greater than n (n=1.84), and i (v) present the current which is acquired from the (i–v) curve. in this approximation, φb and rs values can be determinate by using the following relations [29, 30]: ……………..………………..(7) rs = ………………………………………..(8) where value is obtained from the ln i-v curve, is the minimum point of the plot, (v) is the corresponding voltage and is present the current corresponding to (v0) in the i–v characteristic.[31] ii. 4. chattopadhyay model in addition, chattopadhyay model can be also used to determine the ideality factor and barrier height values of the schottky diode. in the present model, the barrier height φb can be written as [32]: …….……..(9) ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 33 where, present the critical surface potential, is the critical voltage, is the potential difference between the fermi level and bottom of the conduction band, and (c2) present the parameter inverse of the diode ideality factor[31]. the critical surface potential value ( ) can be determined by the following relation [32, 33]: ……………………………...(10) (10) and parameter can be calculated from the following relation: )11(....................................................... (11) here, and are the effective conduction band density of states and the carrier concentration, respectively. using relation (9), we have calculated for different temperatures (300k, 325k, 375k, and 425k). theirs obtained values are 0.04ev, 0.044 ev, 0.0512 ev, and 0.581ev, respectively. in order to determinate the inverse of the ideality factor ( ), we have used the following relation [32]: …………………………………….......(12) iii. result and discussions iii.1. results of current-voltage (i-v method) figure 1 shows our simulated current-voltage (i-v) characteristics of au/insb/inp schottky diode, using atlas-silvaco-tcad soft word, at some selected temperature (300,325,375and 425 k). from figure 1, (i– v) characteristics plot show that the au/insb/inp structure has a schottky diode behavior. in addition, we remarked that all curves have similar behaviors with a qualitative difference. in addition, we observed that there is a deviation of the current and voltage characteristics of the linear. this deviation can be due to the series resistance (rs). our obtained results of saturation current (i0), barrier height (φb) and ideality factor are shown in table 1. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 simul. 300 k 325 k 375 k 425 k l n (i )( a ) v(v) figure .1. the (i–v) characteristics of au/insb/inp schottky diode in the temperature range (300–425 k). iii.2. results of cheung method figure 2 shows the obtained of and h(i) as a function of ( i ) for au/insb/inp structure, at different temperatures(300, 325, 375, and 425k). 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 simul. i(a) d v /d ln (i ) (v ) (a) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 simul. t=425k t=375k t=325k t=300k t=425k t=375k t=325k t=300k i(a) h (i ) (v ) (b) figure.2. the obtained of and h (i) as a function of (i) for au/insb/inp schottky diode, at different temperatures the curve is fitted to a straight line and using (4). both parameters ideality factor and series resistance (rs) have been extracted from the intercept and the slope of the line. we defined the function h (i) by replacing the value of and the characteristics (iv) in equation (5). the plot of h (i) as a function of (i) at different temperatures is shown in figure 2 b. according to the cheung method, the two parameters the height of the schottky barrier (φb), and the series resistance (rs) can be determined [31, 34]. where (φb) ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 34 value is given by (y-axis) intercept of h (i) and (rs) value is given by the slope. the obtained results of (n, rs and(φb) are shown in table 1. iii.3. results of norde method (2) figure 3 shows the variation of norde’s function as a function of v obtained from forward bias currentvoltage characteristics of the au/insb/inp structure. our obtained results of barrier height (φb) , series resistance (rs), and (v0) are shown in table 1. from figure 3 (a), our determinate values of and are 0.529 v and 0.24 v, respectively, at t=300k. 0.0 0.2 0.4 0.6 0.8 1.0 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 v0=0.24v f(v0)=0.529v t=300k simul. f (v ) v(v) 0.0 0.2 0.4 0.6 0.8 1.0 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 simul. t=325 t=375 t=425 f (v ) v(v) figure.3. f (v) as a function of v obtained from forward bias currentvoltage characteristics of the au/insb/inp schottky diode (a) at t=300k and (b) for t=(325, 375 and 425k) iii.4. results of chattopadhyay model figure 4 shows the surface potential-forward voltage curves of au/insb/inp structure for different temperatures (300k, 325k, 375k, and 425k). from behavior shown in fig.4, we remarked that the ψs decreases with the increases of v and ψs value increases with the temperature (t). as showed in fig. 4a, the critical values of (vc) and ψs were extracted from the curve of ψs and the slope indicated in (red dashed line). the obtained results of the critical values (vc) and , and barrier height (φb) using, chattopadhyay model, are shown in table 1. 0.0 0.2 0.4 0.6 0.8 1.0 0.28 0.30 0.32 0.34 0.36 0.38 0.40 0.42 0.44 0.46 0.48 0.50 0.52 simul. (vc,ys)=(0.256,0.362) v(v) t=300k (a) 0.0 0.2 0.4 0.6 0.8 1.0 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 (b) y s( v ) simul. y s( v ) v(v) t=325k t=375k t=425k figure. 4. surface potential-forward voltage curves of the au/insb/inp schottky diode according to what we found, we observed that the increases in temperature are accompanied by the decreases in the ideality factor and increases in the barrier height for all methods. these phenomena are due to the no pure thermionic emission current (te) in the device [35, 36]. because the charge carriers have no enough energy to cross the high barrier height into those low temperatures, but current transport is provided by lower parts of barrier height [37]. and also, we have remarked that the (rs) value decreases with increasing temperatures. this decreases can be due to the increase of the free carrier concentration at low temperatures [38] . also, the obtained results of (rs), using the four different methods, are slightly different. this different in the values of rs, is due to the different regions of (i-v) characteristics where we have determinate this quantity. in the case of the (i-v) method, we have employed the non-linear region while for cheung and norde methods we have used the linear region [19, 27]. the differences in the barrier height values, obtained from these methods, maybe due to the extraction of data from different regions of the forward-bias (i-v) plot [19, 33,39], where the cheung’s functions are only accomplished for the non-linear region of forward bias (i–v ) curve and the norde’s function are executed for the whole forward bias region of the current-voltage curve of the diode [40]. our obtained value of barrier height and ideality factor, for both methods ( ψs –v) and (i-v) [33]. the obtained results of(φb0), (n) and (rs) parameters for au/insb/inp schottky diode via (i-v) method, norde method, cheung method, and chattopadhyay model are summarized in table 1. ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 35 table .1. the obtained values of saturation current, barrier height, ideality factor, series resistance, surface potential (ψs), and critical voltage for au/insb/inp schottky diode in the temperature range (300 k–420 k) temperature 300 k 325 k 375 k 425 k from (iv) characteristics saturation current 10-5(a) 2.6 0.112 0.365 1.01 barrier height, (φb) (ev) 0.602 0.611 0.674 0.690 ideality factor, n 1.683 1.624 1.362 1.234 series resistance, rs (ω) 84.54 60.86 37.12 18.95 from cheung’ s method ( d v/dln i) versus i series resistance, rs (ω) 68.25 45.18 38.31 19.32 ideality factor, n 2.011 1.927 1.674 1.312 from cheung’ s method h( i) versus i series resistance, rs(ω) 62.01 45.18 27.72 16.55 barrier height (φb) (ev) 0.492 0.510 0.566 0.594 from norde’s method barrier height (φb)(ev) 0.626 0.623 0.681 0.692 series resistance, rs (ω) 646.1 633.8 315.2 206.1 f (v0) (v) 0.526 0.548 0.592 0.605 v0 (v) 0.240 0.210 0.230 0.220 from chattopadhyay ’s method barrier height, (φb)(ev) 0.526 0.541 0.605 0.644 ideality factor, n 1.660 1.542 1.422 1.247 surface potential ψs (v) 0.362 0.391 0.424 0.463 the critical voltage (v) 0.256 0.211 0.237 0.226 iv. conclusion in this paper, au/insb/inp schottky diodes were prepared and their electrical were studied by employing (i–v) measurements in the temperature range of (300k – 425 k). the main parameters such as ideality factor (n), barrier height (φb), and series resistance (rs) values were determined using four different methods (conventional (i-v), norde, cheung, and chattopadhyay methods). the obtained values of these parameters are in excellent agreement with each other. for all methods, it is observed that the increase in temperature increases the zero-bias barrier heights and decreases the ideality factor and series resistance. the nature and origin of the decrease in the ideality factor and the increase of the height barrier with the temperature for au/insb/inp schottky diode have been explained based on the thermionic emission with gaussian distribution of barrier heights. references [1] s.-j. yoon and t.-y. seong, "interfacial reactions to form high-barrier-height ito-based schottky contacts on p-type gan using a ti interlayer", vol. 741, 2018, pp. 999-1005. [2] [k. zeghdar, l. dehimi, a. saadoune, and n. sengouga, "inhomogeneous barrier height effect on the current–voltage characteristics of an au/n-inp schottky diode", 2015, vol. 36, p. 124002. [3] r. van meirhaeghe, w. laflere, and f. cardon, "influence of defect passivation by hydrogen on the schottky barrier height of gaas and inp contacts", vol. 76, 1994, pp. 403-406. [4] a. karabulut, a. türüt, and ş. karataş, "the electrical and dielectric properties of the au/ti/hfo 2/n-gaas structures," 2017. [5] m. benchehima, h. abid, and k. benchikh, "firstprinciples calculations of the structural and optoelectronic properties of bsb1− x asx ternary alloys in zinc blende structure", vol. 198, 2017, pp. 214-228. [6] s. adachi, "properties of semiconductor alloys: group-iv, iii-v and ii-vi semiconductors", vol. 28: john wiley & sons, 2009. [7] a. venter, d. murape, j. botha, and f. d. auret, "transport characteristics of pd schottky barrier diodes on epitaxial n-gasb as determined from temperature dependent current–voltage measurements", vol. 574, 2015, pp. 32-37. ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 36 [8] w.-c. huang, t.-c. lin, c.-t. horng, and y.-h. li, "the electrical characteristics of ni/n-gasb schottky diode", vol. 16, 2013, pp. 418-423. [9] s. asubay, ö. güllü, and a. türüt, "determination of the laterally homogeneous barrier height of metal/pinp schottky barrier diodes", vol. 83, 2009, pp. 14701474. [10] j. schleeh, g. alestig, j. halonen, a. malmros, b. nilsson, p. nilsson, j. p. starski, n. wadefalk, h. zirath, and j. grahn, "ultralow-power cryogenic inp hemt with minimum noise temperature of 1 k at 6 ghz", vol. 33, 2012, pp. 664-666. [11] a. konczykowska, j.-y. dupuy, f. jorge, m. riet, v. nodjiadjim, and h. mardoyan, "extreme speed power-dac: leveraging inp dhbt for ultimate capacity single-carrier optical transmissions", vol. 36, 2018, pp. 401-407. [12] f. acar, a. buyukbas-ulusan, and a. tataroglu, "analysis of interface states in au/zno/p-inp (mos) structure", pp. 1-8, 2018. [13] k. hattori and y. torii, "a new method to fabricate au/n-type inp schottky contacts with an interfacial layer", vol. 34, 1991, pp. 527-531. [14] a. singh, k. reinhardt, and w. anderson, "temperature dependence of the electrical characteristics of yb/p‐inp tunnel metal‐insulator‐semiconductor junctions", vol. 68, 1990, pp. 3475-3483. [15] t. enoki, h. yokoyama, y. umeda, and t. otsuji, "ultrahigh-speed integrated circuits using inp-based hemts", vol. 37, 1998, p. 1359. [16] k. pande, "characteristics of mos solar cells built on (n-type) inp substrates," vol. 27, 1980, pp. 631-634. [17] d. korucu and t. mammadov, "temperaturedependent current-conduction mechanisms in au/ninp schottky barrier diodes (sbds) ", vol. 14, 2012, p. 41. [18] a. fritah, a. saadoune, l. dehimi, and b. abay, "investigation on the non-ideal behaviour of au/ninp schottky diodes by the simulation of i–v–t and c–v–t characteristics", vol. 96, 2016, pp. 20092026. [19] n. balaram, v. r. reddy, p. s. reddy, v. janardhanam, and c.-j. choi, " chemical states and electrical properties of au/cuo/n-inp heterojunction with a cupric oxide interlayer", vol. 152, 2018, pp. 15-24. [20] s. tiagulskyi, r. yatskiv, and j. grym, "electrical characterization of graphite/inp schottky diodes by i–v–t and c–v methods", , 2018,pp. 1-5. [21] d. s. atlas, "atlas user’s manual," silvaco international software, santa clara, ca, usa, 2005. [22] r. padma, b. p. lakshmi, m. s. p. reddy, and v. r. reddy, "electrical and structural properties of ir/ru schottky rectifiers on n-type ingan at different annealing temperatures", vol. 56, 2013, pp. 64-76. [23] v. r. reddy, v. manjunath, v. janardhanam, y.-h. kil, and c.-j. choi, "electrical properties and current transport mechanisms of the au/n-gan schottky structure with solution-processed high-k batio3 interlayer", vol. 43, 2014, pp. 3499-3507. [24] s. gholami and m. khakbaz, "measurement of iv characteristics of a ptsi/p-si schottky barrier diode at low temperatures", vol. 5, 2011. [25] a. sadoun, s. mansouri, m. chellali, n. lakhdar, a. hima, and z. benamara, "investigation, analysis and comparison of current-voltage characteristics for au/ni/gan schottky structure using ivt simulation", vol. 37, 2019, pp. 496-502. [26] m. soylu and b. abay, "barrier characteristics of gold schottky contacts on moderately doped n-inp based on temperature dependent i–v and c–v measurements", vol. 86, 2009, pp. 88-95. [27] t. çakıcı, m. sağlam, and b. güzeldir, "the comparison of electrical characteristics of au/ninp/in and au/in2s3/n-inp/in junctions at room temperature", vol. 193, 2015, pp. 61-69. [28] s. cheung and n. cheung, "extraction of schottky diode parameters from forward current‐voltage characteristics," vol. 49, 1986, pp. 85-87. [29] h. norde, "a modified forward i‐v plot for schottky diodes with high series resistance", vol. 50, 1979, pp. 5052-5053. [30] a. kocyigit, i. orak, z. çaldıran, and a. turut, "current–voltage characteristics of au/zno/n-si device in a wide range temperature," vol. 28, 2017, pp. 17177-17184. [31] s. ali, m. sedik, c. mohammed, l. nacereddine, h. abdelkader, and b. zineb, "hafnium dioxide effect on the electrical properties of m/n-gan structure", vol. 38, 2020, pp. 165-173. [32] p. chattopadhyay, "a new technique for the determination of barrier height of schottky barrier diodes", vol. 38, 1995, pp. 739-741. [33] ş. karataş, n. yildirim, and a. türüt, "electrical properties and interface state energy distributions of cr/n-si schottky barrier diode", vol. 64, 2013, pp. 483-494. [34] a. sadoun, s. mansouri, m. chellali, a. hima, and z. benamara, "the effect of introduction of hfo2 on the electrical characterization of the pt/hfo 2/n-gan," in 2018 international conference on communications and electrical engineering (iccee) ", 2018, pp. 1-4. [35] v. janardhanam, a. a. kumar, v. r. reddy, and p. n. reddy, "study of current–voltage–temperature (i– v–t) and capacitance–voltage–temperature (c–v–t) characteristics of molybdenum schottky contacts on n-inp (1 0 0) ", vol. 485, 2009, pp. 467-472. [36] j. sullivan, r. tung, m. pinto, and w. graham, "electron transport of inhomogeneous schottky barriers: a numerical study", vol. 70, 1991, pp. 74037424. ali sadoun et al ijeca-issn: 2543-3717. june 2020 page 37 [37] ş. aydoğan, m. sağlam, and a. türüt, "on the barrier inhomogeneities of polyaniline/p-si/al structure at low temperature," vol. 250, 2005, pp. 4349. [38] h. dogan and s. elagoz, "temperature-dependent electrical transport properties of (au/ni)/n-gan schottky barrier diodes," vol. 63, 2014, pp. 186-192. [39] ö. güllü, ş. aydoğan, and a. türüt, "fabrication and electrical characteristics of schottky diode based on organic material," vol. 85, 2008, pp. 1647-1651. [40] y. ocak, m. kulakci, t. kılıçoğlu, r. turan, and k. akkılıç, "current–voltage and capacitance–voltage characteristics of a sn/methylene blue/p-si schottky diode," vol. 159, 2009, pp. 1603-1607. iii. result and discussions iv. conclusion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 52-59 ijeca-issn: 2543-3717. december 2021 page 52 continuous nonlinear model predictive current control of pwm ac/dc rectifier imad merzouk 1 , noureddine bessous 2 , mohamed mounir rezaoui 1* , mohamed elbar 1 , khansa bdiria 1 1 laadi, faculty of science and technology, university of djelfa 17000 dz, algeria 2 faculty of science and technology, university of el oued 39000 dz, algeria email*: mm_rezaoui@yahoo.fr abstract –the present work applies a nonlinear model predictive current control (nlmpcc) approach to ac/dc pulse width modulation (pwm) rectifier. a cascade structure is used to regulate dc-link voltage and grid currents. the outer loop objective is to regulate the dc-link voltage to the desired value, providing the level of the required active power to be used with the reactive power to calculate the referencing current for the inner loop. in the inner loop, the proposed approach is considered. after that, the nonlinear model of the converter is developed, based on continuous minimization of predicted tracking errors, the voltage at the terminal of the converter is deduced. after that, a pwm block is used to generate gate signals. simulation results are performed to illustrate the efficiency of the proposed control law. keywords: ac/dc pwm rectifier, active and reactive power, nonlinear predictive control, taylor approximation, continuous minimization. received: 05/11/2021 – accepted: 22/12/2021 i. introduction in recent years, ac/dc pulse width modulation (pwm) converters have had more and more applications. these converters have been utilized in high voltage direct current (hvdc) transmission systems, microgrids (mg), renewable energy, and battery energy storage systems. they offer many advantages including low harmonic current distortion, bidirectional power flow, flexible control power flows, smooth and controllable dc-link voltage, high efficiency, and reliability [1-4]. to control the ac/dc pwm rectifier many strategies were proposed in the literature. voltage oriented control (voc) and direct power control (dpc) are initially used. the voc reposed on double cascading loops control, the outer control loop gives the required dc-link voltage and the inner control loop controls the currents. pi regulator is used to regulate dc-ink voltage and current [5, 6]. the dpc concept regulates the active and reactive power directly based on the orientation of selected vectors from a look-up table [7, 8]. each method has its benefits and drawback. however, both methods do not take into account the nonlinearity of the pwm ac/dc converter, therefore they lack disturbance rejection capability and have a slow transient behavior [9-11]. for better performance of pwm ac/dc rectifier, several nonlinear control design approaches have been applied in the last decade [12, 13]. some of these techniques are based on replacing the pi regulator in voc control with a nonlinear controller, such as sliding mode and fuzzy controllers [14-20]. having, as an advantage, robustness with respect to parameters variations, generalized predictive control (gpc) of a linear system is an advanced technique widely adopted to control power electronics converters recently [21-26]. significant effort has been devoted to extend gpc to nonlinear systems, where a nonlinear optimization problem must be solved online with computational complexity. to avert this, several nonlinear predictive laws have been developed in [27, 28]. in this case, the prediction of tracking error is obtained using, taylor expansion model of the system and the reference signal. the control law is then established by minimizing a continuous quadratic function of the tracking [29-33]. in this paper, a nonlinear predictive current control https://www.ijeca.info/ imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 53 scheme is proposed to control the ac/dc pwm converter to benefit from the high accuracy, system stability, rapidity, and constraint capability. after developing the nonlinear model of the converter, the future values of the dq-axis currents are determined using the taylor approximation. after that, the control law (in our case the voltages at the input of the converter) is established by minimizing a continuous quadratic function of the tracking error between referencing and measured current. finally, a pwm block is used to calculate the switching function to be applied in semiconductor devices. the referencing currents are deduced from the required active and reactive powers, in some applications the active power is deduced from an outer control loop that regulates the level of dc-link voltage. ii. system modeling depending on the structure of the pwm converter shown in figure 1 and using park transformation we find a mathematical model in dq rotating coordinate frame of ac side of pwm converter as follows: d d d q d q q q d q di l e ri li v dt di l e ri li v dt                (1) where:  ,d qe e : source voltage in the rotating frame.  , d q v v : converter terminals voltage in the rotating frame.  ,d qi i : line current in the rotating frame.  ,l r : input filter inductance and resistance. + + + la lb lc rb ra rc ea eb ec ia ib ic cdc + vdc idc icap va vb vc t1 t2 t3 t4 t5 t6 n l o a d grid converter input filter il figure 1. topology of ac/dc rectifier the dc-side voltage dynamics of the converter is presented by (2) dc dc l dv c i i dt   (2) neglecting the losses in the input filter and semiconductor devices, the ac side active power is equal to dc side one, so:   3 2 in d d q q out dc dcp e i e i p v i    (3) replacing (3) in (2) the dc-link voltage dynamics   3 2 dc l d d q q dc dv i c e i e i dt cv c    (4) from (1) and (4) the state space of the converter model is given by.   1 0 1 0 3 0 0 2 d q d d d q q d q q dc l d d q q dc r i i li e vld r i i i e vdt l l v i e i e i cv c                                             (5 iii. modeling predictive current control of pwm ac/dc converter consider a nonlinear system, described by:         x f x g x u y t h x      (6) where:    nx t r : state variables vector,    mu t r : control vector,    my t r : output vector,    : n nf x r r ,   : n nxm g x r r and   : n mh x r r are smooth nonlinear functions. assumption 1: the general nonlinear system (6) is sufficiently differentiable with respect to time to any order. this implies that the nonlinear system (6) can be approximated by its taylor-series expansion to any specified accuracy [26, 27]. assumption 2: all states variables are measurable. assumption 3: the system defined in (6) has a relative degree 4 i r  the pwm converter system of (5) can be expressed in the form of (6), where: imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 54     3 2 d q q d l d d q q dc r i i l r i if x l i e i e i cv c                       ,   1 0 1 0 0 0 l g x l             ,       1 2 d q ih x h x ih x             so: 1 2 d q ix x ix             , 1 2 d d q q e vu u e vu             ,       1 2 y t y t y t        the objective of predictive control is to elaborate a control law that coincides the output  y t with the reference trajectory  refy t at the next step (t+h),h>0 is the prediction horizon, [26]. therefore, the control goal is to minimize the following cost function [27]:       2 2 1 1 2 2ref rq j y t h y t h u t     (7) where mxm q r is a definite positive matrix and mxm r r is a positive semi-definite matrix. the vector of the relative degree of our system is the vector  1 2 t i r r r j r , which is the relative degree of the jth element of the output. it corresponds to the first derivative of jy revealing explicitly the control input ju in the expression [25]:      1 1 j j j m r r r j f j gi f j i i y l h l l h u      (8) after calculation, we find that 1 2 1r r  a simple way to predict the influence of  u t on  y t h is to expand it in the    1 2 1 1 t t r r r  order taylor series [31].             1 2 1 1 1 2 0 0 f f g g hl h x y t h y t hl h x l h xh l h xh                      (9) assumption 4: for the output  y t of the nonlinear system (6) to follow the reference trajectory  refy t , we assume that the last one is i r differentiable (is differentiable times). this condition ensures the controllability of the output along with the setpoint  refy t [26]. therefore we can apply the taylor expansion of order    1 2 1 1 t t r r r  to the reference signal:     1 2 ref ref ref ref hy y t h y t hy          (10) with:       1 2 ref ref ref y t y t y t        by replacing equations (9) and (10) in (7) the cost function is then written as:             2 11 12 1 1 1 1 2 1 2 0 0 1 2 reff reff g g q r hyhl h x e t hyhl h x j l h xh u l h xh u t                            (11) where:  e t is the tracking error given as,      refe t h y t h y t h     the optimal solution is then obtained by minimizing the criterion (11) for the nonlinear system (6) compared to the control vector  u t : imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 55                     1 1 1 1 2 1 1 1 2 1 1 1 2 11 22 0 0 0 0 0 0 t g g g g t g g reff reff l h xh h l h x u t l h xh q r h l h x l h xh h l h x hyhl h x q e t hhyhl h x                                                                    (12) with:     1 1 d q f f q d r h i i hl h x l hl h x r h i i l                           ,     1 1 1 2 1 0 1 0 g g l h x l l h x l                 iv. simulations and discussion to verify the mathematical model of the pwm rectifier and to test the efficiency of the control laws presented in this work, we will test the program numerically in the environment matlab / simulink. the overall control structure is illustrated in figure 2. the control is based on two cascading loops, the outer loop controls the level of dc-link voltage using pi regulator, and in the inner loop, the d-q axis currents are regulated using predictive control. the converter parameters are given in table 1. the design of the nonlinear model predictive current controller is based on the continuous model. the general control objective is to extract the switching state that allows tracking the reference current, using a cascade structure. rlgrid nlmpcc equa (12) abc αβ pi p* vdc rl q* + iabc referencing currents calculation eabc pwm idiqeqed vdc*abc αβ dq αβ id*iq* vα vβ s1~s6 vq vd figure 2. control diagram of the proposed nlpc table 1. power circuit parameters. items symbol value input filter inductance l 12 mh input filter resistance r 0.3 ω dc-bus capacitor c 500µf load resistance rl 200 ω iv.1. case 1: dc-link voltage and reactive power step when the simulation reaches a steady state, two steps are applied on the reference of dc-link voltage at t= 1.5 and the reference of reactive power at t=2s. the results are presented in figure 3. 0 0.5 1 1.5 2 2.5 3 0 100 200 300 400 500 time (s) d c -l in k v o lt a g e ( v ) 0.6 0.8 1 1.2 399.8 400 400.2 zoom v dc v dc * (a) 0 0.5 1 1.5 2 2.5 3 -1000 0 1000 2000 3000 4000 5000 6000 time (s) a c ti v e & r e a c ti v e p o w e r (w , v a r) reactive power active power (b) 0 0.5 1 1.5 2 2.5 3 -5 0 5 10 15 20 25 time (s) i d & i q i d i q (c) 0 0.5 1 1.5 2 2.5 3 -140 -120 -100 -80 -60 -40 -20 0 20 time (s) ia , ib & i c 1 1.01 1.02 1.03 1.04 1.05 -20 -10 0 10 20 1.48 1.5 1.52 1.54 -20 -10 0 10 20 (d) imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 56 1 1.01 1.02 1.03 1.04 1.05 1.06 -100 0 100 e a & 4 x ia 2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 -100 0 100 time (s) e a & 4 x ia ea 4xia (e) figure 3. simulation results of case i: (a) dc-link voltage, (b) active and reactive powers, (c) grid voltage and current, (dd) d and q-axis current, (e) three phases current. when the reference of dc-link voltage boosts from 400v to 500v, the dc-link voltage stabilizes to the new reference on approximately 0.05s as shown in figure 3-a. with this change the active power exchanged with the grid is increased too, in order to assure the required power requested at the output of the converter as observed in figure 3-b. however, the reactive power stays unchanged. we can conclude from figure 3-c that the proposed control techniques ensure a decoupled control between active and reactive power, where q-axis current controls the active power and d-axis current controls the reactive power. the transient response of the inner loop is too high. the measured current reaches the new reference immediately without overshoot. in figure 3-d, the three phases current is presented, the currents are sinusoidal with a thd of less than 3%. in addition, along with the rise of active power, the amplitude of currents rises too. in figure 3-e, both grid voltage and current are plotted in the same figure, before and after the referencing reactive power step is applied. when the reactive power is kept zero the voltage and current are in phase. but, when the reactive power increases to 1000 var to a phase shift between the voltage and current is created. so the converter can be used as a reactive power compensator of the grid without affecting the output dc-link voltage, or the grid current quality. iv.2. case 2: load steps in this sub-section, a load step is applied at t=1s (from 60ω to 40ω). the dc-link voltage increases slightly and then returns to its reference without affecting the stability of the system as shown in figure 4-a. from figures figure 4-b and figure 4-c the active power, q-axis current, and the amplitude of the line current increase smoothly to a new value without a change in reactive power. in figure 4-d, the three phases current is plotted; it is observed that the amplitude of the current droops to a new value, the current is always balanced and sinusoidal. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 50 100 150 200 250 300 350 400 450 time (s) d c -l in k v o lt a g e ( v ) v dc * v dc (a) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -500 0 500 1000 1500 2000 2500 3000 3500 4000 time (s) a c ti v e & r e a c ti v e p o w e r (w ,v a r) reactive power active power (b) 0 0.5 1 1.5 2 2.5 3 -2 0 2 4 6 8 10 12 14 16 time (s) i d & i q i d i q (c) 0.95 1 1.05 1.1 1.15 1.2 -15 -10 -5 0 5 10 15 time (s) ia , ib & i c (d) figure 4. simulation results of case 2: (a) dc-link voltage, (b) active and reactive power, (c) d and q-axis current, (d) three phases current. iv.3. case 3: grid voltage droops in with the integration of renewable energy in the grid, the grid voltage may drop from time to time, so we see to test the behaviour of the converter when the grid voltage drops by 30%. the results are shown in figure 5. from figure 5, the control law has a perfect transient under voltage droop. the system remains stable. an imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 57 increase in the amplitude of the current is to be considered in order to keep the system function in gat the same power level. so the average value of the active and reactive power remains unchanged, the system always works at the required dc-link voltage with a unity power factor. the inner control loop has a very fast dynamic while keeping the system stable. 0.95 1 1.05 1.1 -200 -150 -100 -50 0 50 100 150 200 time (s) e a , e b a n d e c (a) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 50 100 150 200 250 300 350 400 450 time (s) d c -l in k v o lt a g e ( v ) 0.9 0.95 1 1.05 1.1 1.15 1.2 399 399.5 400 400.5 401 v dc * v dc (b) 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1 1.12 -5 0 5 10 15 20 25 time (s) i d & i q i d i q (c) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -1000 0 1000 2000 3000 4000 5000 time (s) a c ti v e & r e a c ti v e p o w e r (w ,v a r) reactive power active power (d) 0.95 1 1.05 1.1 -30 -20 -10 0 10 20 30 time (s) i a , i b a n d i c (e) 0.98 1 1.02 1.04 1.06 1.08 1.1 -200 -150 -100 -50 0 50 100 150 200 t (s) e a , 4 x i a e a 4xi a (f) figure 5. simulation results of case 3: (a) grid voltage, (b) dc-link voltage (c) d and q-axis current, (d) active and reactive power, (e) grid current. iv.4. case 4: line inductance mismatch investigation to investigate the robustness of the proposed control method, a big change in input filter inductance is applied, the value of the inductance is stepped from 12 to 2 mh at t=1s and afterward, it is increased to 20 mh at t=1.5s. slight perturbation does not exceed 1v is provoked in the dc-link voltage. otherwise, the dc-link stays smooth and in its reference value as shown in figure 6-a. according to the wave forms of current in figure 6-b, the change of the input filter inductance has no real impact on the current quality, the thd is practically unchanged. so the proposed control showed very high robustness against the system parameter mismatch. 0.5 1 1.5 2 396 397 398 399 400 401 402 403 404 time (s) d c -l in k v o lt a g e ( v ) v dc * v dc (a) imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 58 0 0.5 1 1.5 2 2.5 -60 -50 -40 -30 -20 -10 0 10 time (s) ia , i b & i c 0.5 0.52 0.54 -10 0 10 1 1.02 1.04 -10 0 10 1.5 1.52 1.54 -10 0 10 l=12 mh l=20 mhl=2 mh (b) figure 6. simulation results of case 4: (a) dc-link voltage, (b) three phases current. v. conclusion in this paper a nonlinear model predictive current control has been proposed in order to improve the transient behavior of the pwm ac/dc rectifier. the nonlinear predictive control law was extracted using taylor expansion and by choosing the d and q-axis current as control variables. the reference of current was deduced from the required values of active and reactive powers, where the active power determines the level of dc-link voltage which is controlled by the pi regulator. the control scheme was tested under significant changes in operating points of the converter and external disturbances (source voltage and load variation). the results are encouraging where the system stayed stable and follow the recommended reference. in order to investigate the robustness of the proposed control law, a sever change in the input filter was applied. in this case, the system showed high quality results. references [1] mh. naushath, dr. athula, mg. aniruddha, tf. ioni, “investigation of fault ride-through capability of hybrid vsc-lcc multi-terminal hvdc transmission systems”, ieee transactions on power delivery, vol. 34, issue. 1, 2019, pp. 241-250. [2] g. praveen, p. venkata, p. priyanka, cj. francis, "vacmc-based hybrid ac/lvdc micro-grid”, iet renewable power generation, vol. 11, issue. 4, 2017, pp. 521-528. [3] im. moghaddam, hc. badrul, s. mohajeryami, “predictive operation and optimal sizing of battery energy storage with high wind energy penetration”, ieee transactions on industrial electronics, vol. 65, issue. 8, 2018, pp. 6686-6695. [4] r. katayoun, cc. chin, z. rui, “energy cooperation optimization in microgrids with renewable energy integration”, ieee transactions on smart grid, vol. 9, issue. 2, 2018, pp. 1482-1493. [5] v. blasko, m. kaura, “a new mathematical model and control of a three-phase ac-dc voltage source converter”, ieee transactions on power electronics, vol. 12, issue. 1, 1997, pp. 116-123. [6] m. m. rezaoui, n. bessous, i. merzouk, “control of 3x7 matrix converter with pwm three intervals modulation”, international journal of energetica (ijeca), vol. 4, issue 2, 2019, pp.14-20. [7] k. kulikowski, a. sikorski, “new dpc look-up table methods for three-level ac/dc converter”, ieee transactions on industrial electronics, vol. 63, issue. 12, 2016, pp.7930-7938. [8] m. imad, mlbm. lokman, “improved direct power control for 3-level ac/dc converter under unbalanced and/or distorted voltage source conditions”, turkish journal of electrical engineering & computer sciences, vol. 24, issue. 3, 2016, pp. 1847-1862. [9] g. fouad, a. abdelmajid, l. ibtissam, c f. zahra, “formal framework for nonlinear control of pwm ac/dc boost rectifiers—controller design and average performance analysis”, ieee transactions on control systems technology, vol. 18, issue. 2, 2010, pp. 323-335. [10] lee dc, lee gm, lee kd. , “dc-bus voltage control of three-phase ac/dc pwm converters using feedback linearization”, ieee transactions on industry applications, vol. 36, issue. 3, 2000, pp. 826-833. [11] pk. dashn nayak, “nonlinear control of voltage source converters in ac–dc power system”, isa transaction, vol. 53, issue. 4, 2014, pp. 1268-1285. [12] ts. lee, “input-output linearization and zero-dynamics control of three-phase ac/dc voltage-source converters”, ieee transactions on power electronics, vol. 18, issue. 1, 2003, pp. 11-22. [13] r. gerasimos, cps carlo, “an h-infinity feedback control approach for three-phase voltage source converters”, iecon 2014 40th annual conference of the ieee industrial electronics society, dallas, tx, usa 29 oct.-1 nov 2014. [14] s. fadia, v. hani, yk. hadi, m. nazih, k. al-haddad, “sliding mode fixed frequency current controller design for grid-connected npc inverter”, ieee journal of emerging and selected topics in power electronics, vol. 4, issue. 4, 2016, pp. 1397-1405. [15] sk. kim, “robust output voltage tracking algorithm for three-phase rectifier with variable sliding surface”, iet power electronics, vol. 11, issue. 6, 2018, pp.1119-1127. [16] j. liu, y. yin, w. luo, s. vazquez, lg. franquelo, l. wu , “sliding mode control of a three-phase ac/dc voltage source converter under unknown load conditions: industry applications”, ieee transactions on systems, man, and cybernetics systems, vol. 48, issue. 10, 2018, pp. 1771-1780. [17] s. dan, w. xiaohe, f. yang, “backstepping direct power control without phase-locked loop of ac/dc converter under both balanced and unbalanced grid conditions”, https://ieeexplore.ieee.org/author/37271651300 https://ieeexplore.ieee.org/document/8454345/ https://ieeexplore.ieee.org/document/8454345/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=61 https://ieeexplore.ieee.org/document/7918714/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=4159946 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=4159946 https://ieeexplore.ieee.org/author/37085646782 https://ieeexplore.ieee.org/document/8113554/ https://ieeexplore.ieee.org/document/8113554/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=41 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=41 https://ieeexplore.ieee.org/author/37086284875 https://ieeexplore.ieee.org/author/37085461186 https://ieeexplore.ieee.org/document/7544637/ https://ieeexplore.ieee.org/document/7544637/ https://ieeexplore.ieee.org/document/7544637/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=5165411 https://ieeexplore.ieee.org/author/37351971700 https://ieeexplore.ieee.org/author/37351974700 https://ieeexplore.ieee.org/author/37351974700 https://ieeexplore.ieee.org/document/554176/ https://ieeexplore.ieee.org/document/554176/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=63 https://www.sciencedirect.com/science/journal/00190578 https://ieeexplore.ieee.org/document/1187319/ https://ieeexplore.ieee.org/document/1187319/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=63 https://ieeexplore.ieee.org/author/37330851300 https://ieeexplore.ieee.org/author/37272395200 https://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7036020 https://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7036020 https://ieeexplore.ieee.org/author/37085496384 https://ieeexplore.ieee.org/author/37587057100 https://ieeexplore.ieee.org/author/37628199500 https://ieeexplore.ieee.org/author/37274676300 https://ieeexplore.ieee.org/document/7501904/ https://ieeexplore.ieee.org/document/7501904/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=6245517 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=6245517 https://ieeexplore.ieee.org/document/8358987/ https://ieeexplore.ieee.org/document/8358987/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=4475725 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=4475725 https://ieeexplore.ieee.org/author/37086056173 https://ieeexplore.ieee.org/author/37085766836 https://ieeexplore.ieee.org/author/37293845300 https://ieeexplore.ieee.org/author/37277650800 https://ieeexplore.ieee.org/author/37348622000 https://ieeexplore.ieee.org/author/37348622000 https://ieeexplore.ieee.org/document/8125592/ https://ieeexplore.ieee.org/document/8125592/ https://ieeexplore.ieee.org/document/8125592/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=6221021 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=6221021 https://ieeexplore.ieee.org/document/7499961/ https://ieeexplore.ieee.org/document/7499961/ https://ieeexplore.ieee.org/document/7499961/ imad merzouk et al ijeca-issn: 2543-3717. december 2021 page 59 iet power electronics, vol. 9, issue. 8, 2016, pp. 16141624. [18] c. cecati, a. dell’aquila, a. lecci, m. liserre, “implementation issues of a fuzzy-logic-based three phase active rectifier employing only voltage sensors”,. ieee transactions on industrial electronics, vol. 52, issue. 2, 2005, pp. 378-385. [19] a. hakan, o. fatih kececioglu, a. gani, c. yildiz, s. mustafa, “improved control configuration of pwm rectifiers based on neuro-fuzzy controller”, springer plus. 2016; 5:1142. [20] j. rodríguez, pc. estay, “predictive control of power converters and electrical drives”, (wiley, chichester, west sussex, uk; hoboken, n.j.; 2012). [21] ay. hector, ap. marcelo, j. rodriguez, “analysis of finite-control-set model predictive current control with model parameter mismatch in a three-phase inverter”, ieee transactions on industrial electronics, vol. 63, issue. 5, 2016, pp. 3100-3107. [22] xl. dan, wz. peng , “improved finite-control-set model predictive control for active front-end rectifiers with simplified computational approach and on-line parameter identification”, isa transaction. 2017; 69: pp. 51-64. [23] xy. xing, c. zhang, j. he, a. chen, z. zhang, “model predictive control for parallel threelevel t-type gridconnected inverters in renewable power generations”, iet renewable power generation, vol. 11, issue. 11, 2017, pp. 1353-1363. [24] p. falkowski, a. sikorski, “finite control set model predictive control for grid-connected ac-dc converters with lcl filter”. ieee transactions industrial electronics, vol. 65, issue. 4, 2018, pp. 2844-2852. [25] t. he, lu d. dah-chuan , l. li, j. zhang, l. zheng, j. zhu, “model-predictive sliding-mode control for threephase ac/dc converters”, ieee transactions on power electronics, vol. 33, issue. 10, 2018, pp. 8982-8993. [26] l. ping, “non linear predictive control of continuous nonlinear systems”, journal of guidance, control and dynamics, vol. 17, issue. 3, 1994, pp. 553-560. [27] sn. singh, m. steinberg, rd. digirolamo, “nonlinear predictive control of feedback linearizable systems and flight control system design”, journal of guidance, control and dynamics, vol. 18, issue. 5, 1995, pp. 10231028. [28] j. corriou, “process control: theory and applications”, springer 2017. book isbn: 978-1-84996-911-6. [29] k. bdirina, ms. boucherit, r. hedjar, d. djoudi, naimi h. non linear predictive control with input constraints of electrical wheelchair”, the mediterranean journal of measurement and control, vol. 10, issue. 2, 2014, pp. 215-223. [30] l. tao, w. tan, g. chen, d. kong, “a novel robust model predictive controller for aerospace three-phase pwm rectifiers”, energies. 2018; 11: 2490. [31] e. rachid, sm. muyeen, a. al-durra, s. leng, “experimental validation of a robust continuous nonlinear model predictive control based grid-interlinked photovoltaic inverter”, ieee transactions on industrial electronics, vol. 63, issue. 7, 2016, pp. 4495-4505. [32] a. berboucha, k. djermouni, k. ghedamsi, d. aouzellag, “fuzzy logic control of wind turbine storage system connected to the grid using multilevel inverter”, international journal of energetica (ijeca), vol 2. issue. 1, 2017, pp.15-23. [33] y. saidi, a. mezouar, y. miloud, m. a. benmahdjoub, m. yahiaoui, “fuzzy logic based robust dvc design of pwm rectifier connected to a pmsg wecs under wind/load disturbance conditions”, international journal of energetica (ijeca), vol. 4, issue 1, 2019, pp.37-43. https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=4475725 https://www.sciencedirect.com/science/article/abs/pii/s0019057817303798#! https://www.sciencedirect.com/science/article/abs/pii/s0019057817303798#! https://www.sciencedirect.com/science/journal/00190578 https://ieeexplore.ieee.org/author/37086048004 https://ieeexplore.ieee.org/author/37289043600 https://ieeexplore.ieee.org/author/37965435500 https://ieeexplore.ieee.org/author/37085674046 https://ieeexplore.ieee.org/author/37086048951 https://ieeexplore.ieee.org/author/37085335153 https://ieeexplore.ieee.org/document/8207647/ https://ieeexplore.ieee.org/document/8207647/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=63 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=63 i. introduction in recent years, ac/dc pulse width modulation (pwm) converters have had more and more applications. these converters have been utilized in high voltage direct current (hvdc) transmission systems, microgrids (mg), renewable energy, and battery energy s... therefore they lack disturbance rejection capability and have a slow transient behavior [9-11]. for better performance of pwm ac/dc rectifier, several nonlinear control design approaches have been applied in the last decade [12, 13]. some of these tec... in this paper, a nonlinear predictive current control scheme is proposed to control the ac/dc pwm converter to benefit from the high accuracy, system stability, rapidity, and constraint capability. after developing the nonlinear model of the converter... ii. system modeling depending on the structure of the pwm converter shown in figure 1 and using park transformation we find a mathematical model in dq rotating coordinate frame of ac side of pwm converter as follows: (1) where: iii. modeling predictive current control of pwm ac/dc converter iv. simulations and discussion to verify the mathematical model of the pwm rectifier and to test the efficiency of the control laws presented in this work, we will test the program numerically in the environment matlab / simulink. the overall control structure is illustrated in fig... table 1. power circuit parameters. when the simulation reaches a steady state, two steps are applied on the reference of dc-link voltage at t= 1.5 and the reference of reactive power at t=2s. the results are presented in figure 3. figure 3. simulation results of case i: (a) dc-link voltage, (b) active and reactive powers, (c) grid voltage and current, (dd) d and q-axis current, (e) three phases current. when the reference of dc-link voltage boosts from 400v to 500v, the dc-link voltage stabilizes to the new reference on approximately 0.05s as shown in figure 3-a. with this change the active power exchanged with the grid is increased too, in order to ... we can conclude from figure 3-c that the proposed control techniques ensure a decoupled control between active and reactive power, where q-axis current controls the active power and d-axis current controls the reactive power. the transient response of... in figure 3-d, the three phases current is presented, the currents are sinusoidal with a thd of less than 3%. in addition, along with the rise of active power, the amplitude of currents rises too. iv.2. case 2: load steps in this sub-section, a load step is applied at t=1s (from 60ω to 40ω). the dc-link voltage increases slightly and then returns to its reference without affecting the stability of the system as shown in figure 4-a. from figures figure 4-b and figure 4-... figure 4. simulation results of case 2: (a) dc-link voltage, (b) active and reactive power, (c) d and q-axis current, (d) three phases current. iv.3. case 3: grid voltage droops in with the integration of renewable energy in the grid, the grid voltage may drop from time to time, so we see to test the behaviour of the converter when the grid voltage drops by 30%. the results are shown in figure 5. figure 5. simulation results of case 3: (a) grid voltage, (b) dc-link voltage (c) d and q-axis current, (d) active and reactive power, (e) grid current. iv.4. case 4: line inductance mismatch investigation to investigate the robustness of the proposed control method, a big change in input filter inductance is applied, the value of the inductance is stepped from 12 to 2 mh at t=1s and afterward, it is increased to 20 mh at t=1.5s. slight perturbation doe... figure 6. simulation results of case 4: (a) dc-link voltage, (b) three phases current. v. conclusion references microsoft word article_mokhtar ghodbane (2).docx international journal of energetica (ijeca) https://www.ijeca.info/index.php/ijeca/index issn: 2543-3717 volume 1. issue 1. 2016 page 20-29 estimating solar radiation according to semi empirical approach of perrin de brichambaut: application on several areas with different climate in algeria mokhtar ghodbane , boussad boumeddane faculty of technology, university of saad dahlab, blida 1, cp 09000, algeria abstractthe solar energy reaching a given surface is directly dependent on the orientation thereof and the position of the sun. to get maximum energy from the sun, it is necessary a good solar receiver orientation towards the solar radiation where the solar radiation is perpendicular to the solar collector, so the knowledge of the sun's position over time is a very important thing. the intensity calculate of solar radiation received by an inclined surface is the primary objective of this paper. the study is based on the true solar time, the geographic and astronomical data on-site study. matlab was the simulation tool, where a program was developed to calculate the daily global solar radiation collected by any geographical site depending on the semi-empirical model of perrin de brichambaut. the some applications on different places in algeria, like el-oued, biskra, blida and oran in the day of march 21, june 21, september 21 and december 21, and the results obtained were confirmed by comparing them with the previously results published by the researchers is of great competence in this field. keywords: solar energy, global solar radiation, inclined surface, simulation nomenclature h angular height of the sun (°) j number of the day l longitude (°) rc-h diffuse radiation from the sky intercepted by a horizontal surface (w/m²) rd direct radiation (w/m²) rd-c() diffuse radiation from the sky (w/m²) rd-s() rf-inc diffuse radiation from the ground picked up by a horizontal surface (w/m²) inclination factor rg global radiation (w/m²) tvs true solar time (hour) greek letters  inclination angle of the inclined surface (°) α azimuth (°) αsol soil albedo δ declination (°) φ latitude (°) ω hour angle (°) mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 21 1. introduction the sun is a star; on the human plane this star is of paramount importance because without it life would not exist on earth. the characteristics of the sun are shown in the table below. table 1. main characteristics of the sun [1]. characteristic value unit mass diameter density surface flux energetic 1,9891×1030 1 392 684 1 408 6,0877×1012 3,826×1026 kg km kg/m3 km² w solar energy is the oldest source of energy; it is at the origin of all the sources of energy such as: the wood, the coal, the natural gas, the oil and energy of the wind [2, 3]. the performance calculation of the solar collectors requires the knowledge of the incident solar flux in term of the time, which in the function of the sun position in relation to the earth [4-11]. the earth rotates on itself following an axis of rotation with a constant inclination in relation to the ecliptic plane, with which the equator makes an angle of 23.45° [12]. it also runs in the plane of the ecliptic around the sun. fig.1. earth movement around the sun. the application of solar energy can be grouped into two main categories: high temperature applications (solar concentrators and solar collectors under vacuum), and low temperature applications (the generally flat plate collectors) [4]. in algeria the climate is divided into three categories [4]:  the tell: characterized by a temperate mediterranean climate, such as the site of blida and oran;  the high plains: characterized by a continental climate;  the sahara: characterized by an arid and dry climate such as the site of el-oued and biskra. the notion of aridity does not concern only the desert areas but it affects all regions with scarce or erratic rainfall. table (2) shows the received sunshine annually in algeria according to the climatic region. table 2. the received sunshine annually in algeria [4]. climate category the area ratio hours of sunshine per year (h/year) average energy received (kwh/m²/year) the tell the high plains the sahara 4 10 86 2650 3000 3500 1700 1900 2650 mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 22 in these pages, a computer program accomplished to calculate the incident solar radiation in the area on the surface of the earth. the matlab language was used as a device for programming. this incident solar radiation will be used as a data from other studies in the field of renewable energy, where the solar energy will be converted into heat energy or electricity. these transformations were according to the needs of use and the type of solar collector. the solar radiation was calculated in the following sites: el-oued, biskra, blida and oran. the reason for choosing these areas is the type of climate. 2. geographical and astronomical coordinates any point of the terrestrial sphere can be spotted by two coordinates, these coordinates called terrestrial coordinates as follows:  latitude (φ): it is the angle between the earth place and the equator plane; it is counted positively towards the north,  longitude (l) of a location corresponding to the angle between the meridian planes passing through the area with a meridian plane chosen as origin. table 3. terrestrial coordinates of the regions. place latitude (φ) longitude (l) altitude (z) el-oued 33° 22′ 06″ n 6° 52′ 03″ e practically at the sea [13]. biskra 34° 51′ 00″ n 5° 44′ 00″ e 87 m above the level of the sea [14]. blida 36° 29′ 00″ n 2° 50′ 00″ e 260 m 260 m above the level of the sea [15]. oran 35° 42′ 10″ n 0° 38′ 57″ w min. 0 m max. 429.3 m above sea level [13]. the angle between the terrestrial equator planes and the earth-sun direction is called the declination δ. this angle varies throughout the year symmetrically of -23°26 'to 23°26' [14]. so declination (δ) is the point’s latitude of the earth which are achieved by the midday sun (noon-solar), it is directly related to day (j) of the year as it turns out in the relationship (1) [16]. 284)] + (j [0,980°sin 23,45° = δ (1) 2.1. hourly coordinates the hour angle (ω) is the angle between the vertical plane of the place and the meridian plane passing through the center of the sun, it is given by: 12)-tsv( + 24 360ω  (2) 2.2. horizontal coordinates the position of a star in the space can be identified by its horizontal coordinate defined on the celestial sphere namely an angular height (h) and an azimuth (α). so the position of the sun in a place, in a date and at any time depends on two angles: azimuth (α) is the angle between the projection of the sun direction on the ground and the south. it is measured from the south to the west positively zero at solar noon. the relation of the azimuth is: cosh sinωcosδsinα  (3) height of the sun (h) is the angle that the sun direction with its projection on the ground, it varies from 0 ° to 90 ° in the southern hemisphere (nadir), vanishes at sunrise and sunset and is maximal in the south-solar. δsin sin + ω cos δ cos cos =h sin  (4) mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 23 3. solar radiation received by inclined surface solar energy is an inexhaustible source of energy and clean, which does not cause harmful emissions to our environment. it is propagated in the space on the form of photons. therefore, it is available everywhere and cease renewable. the solar field is a set of data describing the evolution of the solar radiation available during a given period. its evolution can be done using data of global solar irradiation. figure 2 illustrate the number of daily insolation hours on the last day of each month during the year, which the length of the daylight period for the last day of each month in the selected areas of study. fig.2. the number of daylight hours according of the last day of each month. so in all sites, the daily insolation hours is varied for each month between 09 hours and 14.5 hours depending on the season of each month, that's why during the winter months, the amount received is less because of the low height of the sun. roughly the number of hours of daily insolation in the four sites is important. there is several models give a solar radiation depending on atmospheric and astronomical parameters. generally, they expressed by semi empirical approaches; the most commonly known and used in practice is mainly include the perrin de brichambaut model and the liu jordan model. this work will be based on the approach of perrin de brichambaut. 3.1. the perrin de brichambaut model the global solar radiation (rg) arriving on a surface directed to the south with a slope (β) consists of direct radiation and diffuse radiation [2, 3, 17, 18]. fig.3. characteristics of a flat plate collector directed to the south. 1 2 3 4 5 6 7 8 9 10 11 12 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 the da ily ins ola tio n h ou rs [ho ur] month el-oued biskra blida oran mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 24 it can be estimated the global solar radiation at any time and in any location from the eq. (5).    βrβrrrr s-dc-dincfdg   (5) with (rd) is the direct radiation (w /m²) [3, 19], generally the semi-empirical formulas as eq. 6 is used to calculate it.      c)sin(hb 1expar d (6) a, b and c are empirical constants that depend on the state of the sky, in which these values are from table (4). table 4. the values of the constants a, b and c in terms of the nature of the sky. sky condition a b c clear sky normal conditions of clear sky clear sky polluted 1210 1230 1260 6 3.8 2.3 1 1.6 3 rf-inc is the inclination factor; it is given by the following relationship:                   δsinsinδcosω)coscos( sinδβsinδcosωβ)coscos(r inc-f   (7) dr-c (β) is the scattered radiation which is received by a tilt surface with inclination angle (β).     hccd r2 βcos1βr   (8) rc-h is the diffuse radiation [w.m-²], intercepted by a horizontal surface.  0,4hc hsin d251r  (9) d is an empirical observation that depends on the state of the sky, whose values are expressed according to the following table: table 5. the value of the constant d depending on the nature of sky. sky condition d clear sky normal conditions of clear sky clear sky polluted 3/4 1 4/3 dr-s (β) is diffuse radiation coming from the soil and is received by a horizontal surface [20]. mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 25      hcdsolsd rhsin r2 βcos1αβr   (10) αsol is a reflectivity or an albedo of the soil; it depends on the nature thereof. some average values are summarized in table (5). table 6. a few albedo values based on the nature of the soil [4, 21]. type of soil average reflectivity (albedo) snowy soil ground covered with dead leaves green grass forest in autumn or golden fields pebbles white stones dry grass clay soil forest in winter (without snow coniferous trees) waterhole (high sunshine hours> 30°) 0.70 0.30 0.26 0.26 0.20 0.20 0.17 0.07 0.07 4. resultats and dicussion to calculate the global solar radiation from sunrise to sunset, an algorithm was developed that can simulate solar radiation by the semi-empirical model perrin de brichambaut. the global radiation was calculated in clear sky conditions for the 21st day of the following month: march, june, september and december in the areas of el-oued, biskra, blida and oran. figure 4 presents the calculation chart. fig.4. simulation flow chart. the change in global solar radiation particularly depends on the geographical coordinates of the location considered and the day number of the year. the results are simulated from a sunrise to a sunset, the collected radiation varies proportionally to the time of day, and the variation recorded due to the position of the sun during the day. so, the primary objective of this program is to calculate the amount of solar radiation to estimate the quantity of energy received by the solar collectors (especially the flat solar collectors). just choose the day, month, type of sky the latitude of the location and angle of inclination. the results will give the global radiation values in graph form. after inputting data of the site, the evolution allures of the global solar radiation were traced, these radiations are received by an inclined surface (or plane) with an inclination angle equal to the latitude of the selected site. the results of the four typical days “march 21, june 21, september 21 and december 21 (correspond to the solstices and equinoxes)” are shown in the figures 5a-5d. the data:  the month and day;  type of sky ;  location ;  angle of inclination of the inclined surface (collector) ; the calculations:  angle declination of the sun;  incidence angle;  height of the sun;  azimuth of the sun;  time of sunrise and sunset. calculates the global solar radiation mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 26 a) 21 march b) 21 june c) 21 september d) 21 december fig.5. evolution of global solar radiation during the four-day of the estimating. from the curves of the figure (5), it can be said that solar radiation reaches its maximum value around noon and minimum values at sunrise and sunset. the radiation quantities received at the beginning of the day and in the last of the day are almost equivalent (the amount received at 11:00 is very similar to that received 13:00), which the vertical axis at the same point waypoint (x=12, y=0) is the symmetry axis of all the curves, this axis can be defined as follows: ivgsrtftf  )12()12( (11) where, ivgsr is the instantaneous value of the global solar radiation, and “t” is a factor for definition of the time, it is changed as follows: 2,,.........3,2,1 tt  (12) 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] biskra el-oued blida oran 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 100 200 300 400 500 600 700 800 900 1000 1100 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] biskra el-oued blida oran 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] biskra el-oued blida oran 7 8 9 10 11 12 13 14 15 16 17 050 100150 200250 300350 400450 500550 600650 700750 800850 900950 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] biskra el-oued blida oran mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 27 δt is the duration of the day; it can be defined as follows: sunrisettt  sunset (13) according preventatives curves, it notes that the program can calculate and determine the daily solar radiation collected by any site on the earth surface. the solar radiation estimation requires the knowledge to make clear many parameters, including the parameters of location (latitude, longitude and altitude) without forgetting the albedo of the place and settings that depending of the receiving surface that are:  the inclination angle (β) at a tilt angle equal to the latitude;  the orientation of solar collector directed to the south. to confirm the validity of this program, a comparison is made with results of the semi empirical model of liu jordan and experimental work on the website of the university of biskra for march 21, june 21, september 21 and december 21[22]. the figures 6a-6d illustrate the curves of comparison. a) 21 march b) 21 june c) 21 september d) 21 december fig.6. comparison of results in the biskra region. after comparing the results of the three tools, it notices that they give very similar solar radiation values especially at noon or the difference is almost negligible. the gap that exists between the two models studied compared with experimental values is very important. therefore, the semi empirical adjustment is conclusive and can beings considered as a solar illumination simulation model in the studied site, so in algeria could be rely on a perrin de brichambaut model in estimating the quantity of global solar radiation, where 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 100 200 300 400 500 600 700 800 900 1000 1100 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] perrin model liu jordan model experimental 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 100 200 300 400 500 600 700 800 900 1000 1100 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] perrin model liu jordan model experimental 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 100 200 300 400 500 600 700 800 900 1000 1100 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] perrin model liu jordan model experimental 6 7 8 9 10 11 12 13 14 15 16 17 18 0 100 200 300 400 500 600 700 800 900 glo ba l so lar ra dia tio n [ w/ m² ] time [hour] perrin model liu jordan model experimental mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 28 sustainable use of this potential will largely meet the demand of the heating, the air conditioning, …etc. in previous studies, we have using this program, where we got very good results [4, 5]. 5. conclusion for countries with high solar radiation such as algeria, the application of solar renewable energy systems can make the difference and solve many problems. this study of the estimating solar radiation modeling on an inclined surface with semi-empirical model of perrin de brichambau in four sites as follows: el-oued, biskra, blida and oran. on september 21, it notes that the highest value of solar radiation recorded in el oued and it reached 1120 [w/m²] at a true solar noon and that on the day of september 21; the city of el-oued has one of the saharan regions with a strong luminous field; it is characterized by a hot, dry climate and a very high rate of sunshine. this program can calculate and estimate the diffuse solar radiation, direct and comprehensive anywhere on the surface of the earth based on geographic parameters and day number of the year. this program will help researchers in the field of renewable energies in determining the amount of solar energy that can be converted into thermal energy or photovoltaic as needed. references [1] wikipedia, "soleil, site web (http://fr.wikipedia.org/wiki/soleil), dernière modification le 17 mars 2015." [2] s. a. kalogirou, solar energy engineering: processes and systems, 1st ed: academic press, 2009. [3] a. rabl, active solar collectors and their applications: newyorkoxford, oxforduniversitypress, 1985, 1985. [4] m. ghodbane, b. boumeddane, n. moummi, s. largot, and h. berkane, "study and numerical simulation of solar system for air heating," journal of fundamental and applied sciences, vol. 8, pp. 4160, 2016. [5] m. ghodbane, b. boumeddane and s. largot, "simulation numérique d’un concentrateur cylindroparabolique en el oued, algérie," international journal of scientific research & engineering technology (ijset), vol. 3, pp. 68-74, 2015. [6] m. ghodbane, b. boumeddane, and n. said, "design and experimental study of a solar system for heating water utilizing a linear fresnel reflector," journal of fundamental and applied sciences, vol. 8, pp. 804825, 2016. [7] m. ghodbane, b. boumeddane, and n. said, "a linear fresnel reflector as a solar system for heating water: theoretical and experimental study," case studies in thermal engineering, vol. 8, pp. 176-186, 2016. [8] m. ghodbane, b. boumeddane and s. largot "etude optique et thermique d’un concentrateur cylindroparabolique en site d’alger, algerie," presented at ixth international congress on renewable energy and the environment, djerba, tunisie, 18-20 march 2015. [9] m. ghodbane, b. boumeddane, s. largot, and h. berkane, "modélisation d'un cycle de réfrigération solaire à éjecteur couplée à un concentrateur cylindro-parabolique," presented at international conférence en clean cooling technologies in the me na regions (ict3_mena'2015), bou smail, w. tipaza, 5-6 october 2015. [10] m. ghodbane and b. boumeddane, "a numerical analysis of the energy behavior of a parabolic trough concentrator," journal of fundamental and applied sciences, vol. 8, pp. 671-691, 2016. [11] m. ghodbane and b. boumeddane, "numerical modeling of a parabolic trough solar collector at bouzaréah, algeria," international journal of chemical and petroleum sciences, vol. 4, pp. 11-25, 2015. [12] vikidia, "latitude, site web (https://fr.vikidia.org/wiki/latitude), dernière modification le 20 décembre 2013." [13] wikipedia, "el-oued,site web (http://fr.wikipedia.org/wiki/el_oued), dernière modification le 22 décembre 2014." [14] wikipedia, "biskra, site web (http://fr.wikipedia.org/wiki/biskra), dernière modification le 17 mars 2015." [15] wikipedia, "blida, site web (http://fr.wikipedia.org/wiki/blida), dernière modification le 16 mars 2015." [16] a. a. sfeir and g. guarracino, ingénierie des systèmes solaires applications à l'habitat, paris ed, 1981. [17] z. sen, "flat plate collectors," in solar energy fundamentals and modeling techniques: atmosphere, environment, climate change and renewable energy: springer, 2008, pp. 246-249. [18] d. y. goswami and f. kreith, "solar energy resources," in energy conversion, t. f. group, ed.: crc press, 2007, pp. 5-1//5-9. [19] j. a. duffie and w. a. b, solar engineering of thermal processes, 4th ed: wiley & sons, inc, 2013. [20] b. s. romdhane, "rayonnement solaire incident sur les différentes parois d'un bâtiment en tunisie en fonction de l’heure et du mois. site de web (http://solairebattunisie.voila.net/index.html)," 20/11/2006. [21] y. jannot, thermique solaire, octobre 2003. mokhtar ghodbane et al ijeca – issn: 2543-3717. december 2016 page 29 [22] a. moummi, n. h. amani, n. moummi, and z. mokhtari, "estimation du rayonnement solaire par deux approches semi empiriques dans le site de biskra," presented at 8th international meeting on energetical physics, centre universitaire de béchar–algérie, 11 et 12 novembre, 2006. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 01-06 . http://dx.doi.org/10.47238/ijeca.v5i1.122. june 2020 page 1 studying sediment transport dynamics by using the smart sphere zaid alhusban 1 , manousos valyrakis 2 1 phd graduate, school of engineering, university of glasgow, united kingdom 2manager of the water engineering lab, university of glasgow, united kingdom z.al-husban.1@research.gla.ac.uk abstract –a new method is introduced by using high precision accelerometer and gyroscope micro-electromechanical sensors (mems), which can record lagrangian observations of sediments and shed light into the dynamics of sediment transport processes at above threshold conditions. the sensor can be used under a range of well-controlled flow conditions and can record measurements at high frequency (200 hz), which can be used at the field. the smart sphere performance was evaluated by comparing its rotation and acceleration readings from the sensors to the video recordings of both top and underwater high-speed camera for a range of flow rates and sphere densities. furthermore, an initial attempt to compare the smart-sphere’s velocity is achieved, by transforming the particle’s velocity from the lagrangian frame of reference, obtained from the inertial sensor, to its velocity at the eularian frame, obtained from the top camera. keywords: lagrangian, high frequency, velocity, micro-electomechanical sensors. received: 10/05/2020 – accepted: 12/06/2020 i. introduction for several decades, many theoretical and experimental studies were devoted to increase the understanding of the mechanics responsible for transporting sediment as they are center of attention for many hydraulic researchers, geomorphologists and industrial projects. measurements of sediment motion have been primarily limited to indirect observations with acoustic and optical instruments. radio frequency identification tags implanted in natural rounded riverbed spheres were used to study sediment transport, but they have limited capacity to detail exact sphere movement. smart loggers have been developed inside suitable sensors to store data and determine the actual paths of individual grains [1]. the approach after analysis had many technical challenges in attaining and storing the data [2, 3] after calibrating the sensor tried to get accurate information about the entrainment conditions of a sensor, but even though the analysis result of the data does not permit the precise resolution of the smart sphere path. recent technological advancements in the area of sensing and instrumentation has received increasing attention and rendered it possible to record lagrangian observations of sediments and shed light into the dynamics of sediment transport processes, at an unprecedented resolution and accuracy by using high precision accelerometer and gyroscope sensors micro-electomechanical sensors (mems)[4]. the mems sensor can record inertial dynamics such as accelerations (m/s 2 ) (related to the near bed hydrodynamic forces acting on it), angular velocities (rad/s), magnetic field and hence forces and energy. this sensor will be capable of higher frequency (up to approximately 200 hz) and have enhanced data acquisition and storage so it can provide a novel tool for investigating sediment transport dynamics. the "smart sphere" is a contemporary sensing equipment under development which is miniaturized to scales that enable implementation of dynamic micro-sensors within natural sediment spheres (of diameter <80 mm), so it can mimic the behaviour of a naturally rounded sediment particlesand determine the full inertial dynamics of sediment transport in 3d space from the moving bodyframe of individual spheres, giving an insight on how individual grains experience transporting forces during their movement from the riverbed. the purpose of this research project is to demonstrate how such technologies can improve our understanding of sediment transport dynamics . the theory and previous research of sediment transport will be considered in order to develop a better understanding of the problem and design suitable experiments.sphere transport experiments under a range of well-controlled, fully turbulent and rough flow conditions are conducted in a flume at the water ijeca-issn: 2543-3717. june 2020 engineering lab, of the university of glasgow, the sediment transport above the threshold of motion (between the threshold of motion and below continuous transport) for the smart sphere. it is expected in all experiments that the effect of hydrodynamic forces on the smart sphere is comparable to their effects on real sediment particle transporting in riverbeds. used to collect the data will be described, along with the procedures used to obtain and analyse the r findings will be further discussed, and the ‘smart sphere’s’ capacity to study the dynamics of sphere motion, as well as its use as a novel tool for the practioners and hydraulic engineers will be assessed. sediment transport of coarse bed mate complex process getting a probabilistic nature because of the intermittent character of turbulent flow forcing , local arrangement properties and the randomness of sphere. for this reason a principle that is universally accepted and strongly describes this dynamical process does not yest exist. the criteria generally employed for engineering applications, such as shields shear stress, is averaged in time and space with high level of variability, so it fails to capture the dynamic character of hydrodynamic forcing leading to sediment transport. lately, novel sediment transport criteria using a dynamic defintion that highlights the importance of adequate energetic turbulent flow structurs have been suggested 6]. in contrast with former studies based on the mean averaged static force balance approaches. therefore, it is assumed that for the same mean flow velocity the sphere will be subject to different forces and responses. the application of these criteria in engineering practice remains relatively low even though these criteria can capture the fully dynamic nature of sphere movement in turbulent flows. the research attempts to cover the gap in calculating the sediment transport by examining an application of a novel approach and taking advan recent technological advances that offer high precision sensors and microelectronic mechanical systems (mems), which could be used to enable approaching flow induced bed material transport dynamics from a lagrangian perspective, to improve the unde mechanism of bed load transport and the processes involved in the near bed region of a turbulent open channel flow by measuring inertial dynamics at scales suitable for gravel-sized sediment, because the miniaturization of sensing equipment ha sensor capable of measuring inertial dynamics such as acceleration and angular velocity) feasible. advanced low-cost tool can be used in a lot of applications after calibrating and testing the sphere carefully in controlled flow conditions zaid alhusban et al. 20 university of glasgow, to study the sediment transport above the threshold of motion (between the threshold of motion and below continuous it is expected in all at the effect of hydrodynamic forces on the smart sphere is comparable to their effects on real sediment particle transporting in riverbeds. he equipment used to collect the data will be described, along with the procedures used to obtain and analyse the results. the findings will be further discussed, and the ‘smartsphere’s’ capacity to study the dynamics of sphere motion, as well as its use as a novel tool for the practioners and hydraulic engineers will be assessed. sediment transport of coarse bed material is very complex process getting a probabilistic nature because of the intermittent character of turbulent flow forcing , local arrangement properties and the randomness of sphere. for this reason a principle that is universally accepted describes this dynamical process does not the criteria generally employed for engineering applications, such as shields shear stress, is averaged in time and space with high level of variability, so it fails to capture the dynamic character of hydrodynamic forcing leading to sediment transport. lately, novel sediment transport criteria using a dynamic defintion that highlights the importance of adequate energetic turbulent flow structurs have been suggested [5, s based on the mean averaged static force balance approaches. therefore, it is assumed that for the same mean flow velocity the sphere will be subject to different forces and responses. the application of these criteria in engineering practice tively low even though these criteria can capture the fully dynamic nature of sphere movement in the research attempts to cover the gap in calculating the sediment transport by examining an application of a novel approach and taking advantage of recent technological advances that offer high precision sensors and microelectronic mechanical systems (mems), which could be used to enable approaching flow induced bed material transport dynamics from a lagrangian perspective, to improve the understanding of port and the processes in the near bed region of a turbulent open channel flow by measuring inertial dynamics at scales sized sediment, because the miniaturization of sensing equipment has made the sensor capable of measuring inertial dynamics such as acceleration and angular velocity) feasible. this cost tool can be used in a lot of applications after calibrating and testing the sphere carefully in controlled flow conditions and can be transformative for the water engineering industry. results of this study could lead to a better understanding of sphere motion dynamics at above the sediment transport thresholds during its movement from the riverbed. ii. experimental investigat the experiments for this study were conducted to evaluate the performance of the “smart arm field flume in the water engineering lab at the university of glasgow where conditions threshold were created in a high capacity research flume, and the responses of a custom sphere fitted with inertial measurement sensors, namely the ‘smart-sphere’, sitting in a local topography of known geometry were observed. the sphere’s movements were monitored using both the video in camera and the data from sensors fitted in the sphere . flow measurements were recorded using a 3d acoustic doppler velocimeter (nortek vectrino 1). the internal components of the instrumented particle ii.1 description of the figure 1. the internal components as a result, the sensor can resolve for the movement of the unit. regular intervals and stored on the externa module via a microcontroller, waterproof hollow sphere [7]. appropriately fit while keeping the acceloremeter and gyroscope on the centre of the sphere uniform distribution of the mass may bias its motion. the gyroscope has excellent ability of measuring angular motions, but it lacks an absolute orientation reference in contrast with the rest sensors as the axes of the sensor are not aligned to the axis o local eulerian frame and they are taken with the body frame, so the same vectors will be recorded differently in the frame of the sensor compared to their initial form in the eulerian frame should be corrected to avoid possible effects of signal 20 page 2 transformative for the water engineering industry. the results of this study could lead to a better understanding motion dynamics at above the sediment during its movement from the experimental investigation the experiments for this study were conducted to evaluate the performance of the “smartsphere” at the flume in the water engineering lab at the university of glasgow where conditions above threshold were created in a high capacity research and the responses of a custom-made instrumented sphere fitted with inertial measurement sensors, namely sitting in a local topography of known the sphere’s movements were monitored using both the video input from a high-speed camera and the data from sensors fitted in the sphere . flow measurements were recorded using a 3d acoustic doppler velocimeter (nortek vectrino 1). figure 1 shows internal components of the instrumented particle .1 description of the smart sphere internal components of the instrumented particle as a result, the sensor can resolve 9 degrees of freedom for the movement of the unit. the data are recorded at regular intervals and stored on the external memory , embedded in a 3d-printed the instrumented board is while keeping the acceloremeter and gyroscope on the centre of the sphere, to achieve a nearly the mass, which could otherwise the gyroscope has excellent ability of measuring angular motions, but it lacks an absolute orientation reference in contrast with the rest sensors as the axes of the sensor are not aligned to the axis of the local eulerian frame and they are taken with respect to so the same vectors will be recorded differently in the frame of the sensor compared to their initial form in the eulerian frame [8]. the measurements should be corrected to avoid possible effects of signal ijeca-issn: 2543-3717. june 2020 drifts. therefore, readingsfrom the magnetometer and the acceleroter, which measures magnetic direction, are used to form an absolute component of orientation that corrects any short-term drifts made by the gyroscope. embedded sensors have a sufficiently high sampling rate (200 hz) to measure angular velocities and accelerations changes undergone by the smart sphere in our experiments. time series of the sphere from the gyroscope and the accelerometer readings were stored in the sensor system’s memory. these data were post-processed offline using an appropriate scientific programming language (matlab) which gives the ability to measure for the first time the inertial d 3-dimensions local accelerations (m 2 angular velocities (rad/s) from angular acceleration, and relate these to the near bed hydrodynamic forces acting on it and under threshold flow conditions. shows the time and acceleration relationship for one of the trials. after that the total acceleration magnitude was calculated as follows: � = ��� � + �� � + �� � figure 2. time and acceleration relationship for one of the trials the accelerometers accumulate errors in measurements, and they exhibit drift, no uniformity, misalignment, bias, sensitivity (due to interference, temperature, etc then post-processing will be done to the raw data extracted from the sensors to correct any er acquired signal by using 3 steps moving average for the acceleration data, which is used as a filter to remove noise from data. the “smart-sphere” employed is a custom-made instrumented sphere with 6.5 cm diameter with a built-in sensor for acceleration and rotation measurements. figure 3 shows the smart sphere with its internal components. zaid alhusban et al. 20 readingsfrom the magnetometer and the acceleroter, which measures magnetic direction, are used to form an absolute component of orientation that term drifts made by the gyroscope.the embedded sensors have a sufficiently high sampling rate (200 hz) to measure angular velocities and accelerations changes undergone by the smart sphere in our sphere response, data he gyroscope and the accelerometer readings were stored in the sensor system’s memory. these data were processed offline using an appropriate scientific ) which gives the ability to measure for the first time the inertial dynamics such as 2 /s), 3-dimension angular velocities (rad/s) from angular acceleration, and relate these to the near bed hydrodynamic forces acting on it and under threshold flow conditions. figure 2 celeration relationship for one of after that the total acceleration magnitude was (1) time and acceleration relationship for one of the trials accelerometers accumulate errors in measurements, , misalignment, bias, interference, temperature, etc). processing will be done to the raw data extracted from the sensors to correct any errors in the 3 steps moving average for the which is used as a filter to remove sphere” employed is a made instrumented sphere with 6.5 cm diameter eleration and rotation shows the smart sphere with its figure 3.a) the smart sphere shell b) the smart sphere with its internal components: inner casing, outer casing, sensor, o for sensor and density control smart spheres are made of plastic material and deployed in natural environments, such as rivers, are affected by large forces and damaging environmental conditions. it is important to ensure that the electromechanical components of the sensor will not be stressed extremely and will remain dry during operation to avoid affecting sensor data results. the encasement in the smart sphere is required to measure large forces experienced by mobile river sediment grains. the sensors are housed within separate conjoined cases that fit the sensor, hold it in place and keep it operational. the smart sphere is manufactured where sensor should be in the middle of sphere to get reasonable results and placed with known initial orientation. even though th shape and material are not matching the physical natural sphere, the instrumented sphere surrogate measurements, which can relate to transport metric. so, it is good to study the process (mode of transport) and physics. moreover, the results will not be exact but expected to correlate to actual same transport rates. having the sensor at the centre of smart sphere, surrounded by equally distributed weights, a uniform distribution of mass was obtained with un sphere, so that the motion was not biased and offsets in the readings were minimized. powered by an independent power supply to ensure autonomy and sufficiently long periods of operation, appropriate for its future deployme unit was powered by a battery, which generally powers the circuit up to about 50-60 minutes continuously. casing as shown in figure 5 is design different quantities of weights, thus having an adjustable density of 500-2900 kg/m 3 . the casing designs were produced using appropriate software (solidworks and where built using a rigid opaque photopolymer material and additive manufacturing equipment. ii.2 description of the experimental setup to assess the smart-sphere performance a series of flume experiments at well-controlled and conditions (figure 3 and figure 4) of the research flumes of the water engineering lab at the university of glasgow [9]. the response of the smart sphere for a range of 5 different flow rates, 4 different smart sphere 2-bed surface rough nesses satisfactory results, as detailed in the following sections: the observations of this experiment were obtained from tests carried out using a flume with the following 20 page 3 a) the smart sphere shell b) the smart sphere with its internal components: inner casing, outer casing, sensor, o-ring, holder density control smart spheres are made of plastic material and deployed in natural environments, such as rivers, are affected by large forces and damaging environmental conditions. it is important to ensure that the electromechanical or will not be stressed extremely and will remain dry during operation to avoid affecting encasement in the smart sphere is required to measure large forces experienced by mobile river sediment grains. the sensors are housed within two separate conjoined cases that fit the sensor, hold it in place and keep it operational. the smart sphere is manufactured where sensor should be in the middle of sphere to get reasonable results and placed with known even though the size, specific density, shape and material are not matching the physical natural sphere is used because it takes which can relate to transport metric. so, it is good to study the process (mode of ) and physics. moreover, the results will not be exact but expected to correlate to actual same transport having the sensor at the centre of smart sphere, surrounded by equally distributed weights, a uniform distribution of mass was obtained with uniform smart sphere, so that the motion was not biased and offsets in the readings were minimized. the smart sphere was powered by an independent power supply to ensure autonomy and sufficiently long periods of operation, appropriate for its future deployment in the field. the unit was powered by a battery, which generally powers 60 minutes continuously. the is designed to accommodate different quantities of weights, thus having an adjustable . the casing designs were produced using appropriate software (solidworks tm) and where built using a rigid opaque photopolymer material and additive manufacturing equipment. .2 description of the experimental setup performance a series of flume controlled and above threshold flow (figure 3 and figure 4) have been made at one of the research flumes of the water engineering lab at . during these experiments, the response of the smart sphere for a range of 5 different different smart sphere sphere densities and rough nesses were assessed with satisfactory results, as detailed in the following sections: bservations of this experiment were obtained from tests carried out using a flume with the following ijeca-issn: 2543-3717. june 2020 channel specifications: 12 meters long, 0.4 meters deep and 0.9 meters wide. flume walls comprise of smooth transparent glass, which enable observing transport from the side. in order to preciously intended flow heights at reasonable flow velocities, an adjustable tailgate is located at the outlet to control the flow heights. on the sidebars at the top of the flume, a mobile carriage attached, which is used to carry the adv and measure the flow velocities at the desired locations. figure 4 shows general layout of the experiments used in the flume. figure 4. test section view from upstream, showing the ‘smart resting on the flume’s bed surface, the adv for flow measurements, top and sidecameras for visual validation of the samrt sphere’s response. tests were conducted using two sizes for the comprising the bed surface, over which only one ‘smart sphere’ was placed to be transported for each set of experiments. the nominal diameters for the bed surface sphere s during the tests are 1.5 cm for surface a, and 2.15 cm for surface b. both bed roughness’s will have a length of 150cm and width of 50 cm and comprise of beads in a well-packed arrangement so the bed will not move. the test section was located at the downstream end of the flume, at 5.25m from the inlet, and 1.75m from the tailgate. figure 5 shows the top and side view of bed roughness (a). zaid alhusban et al. 20 channel specifications: 12 meters long, 0.4 meters deep and 0.9 meters wide. flume walls comprise of smooth which enable observing sphere to preciously create intended flow heights at reasonable flow velocities, an adjustable tailgate is located at the outlet to control the flow heights. on the sidebars at the top of the flume, a which is used to carry the adv the desired locations. shows general layout of the experiments used in test section view from upstream, showing the ‘smart-sphere’ surface, the adv for flow measurements, top and sidecameras for visual validation of the samrt sphere’s tests were conducted using two sizes for the sphere s comprising the bed surface, over which only one ‘smartsphere’ was placed to be transported for each set of experiments. the nominal diameters for the bed surface s during the tests are 1.5 cm for surface a, and ghness’s will have a length of 150cm and width of 50 cm and comprise of packed arrangement so the bed will not move. the test section was located at the downstream end of the flume, at 5.25m from the inlet, and 1.75m shows the top and side view of figure 5. a) top view of the beds rough nesses roughness the sphere’smotion is captured with from a high-speed commercial study the behavior of sphere dynamical features of sediment motion. the video is used as a tracking method to capture the position and velocity of the sphere being transported downstream the flume. the camera operating at 30 frames per second (gopro hero4 session), which was placed in the flume near the test section and a little bit downstream from it in order to cover the full length of the bed and to avoid any visual interference with the flow near the test section. photolux bulbs 500 w were used to avoid strong light reflection on the bed and facilitate visual tracking of the sphere movements. the whole test section without any problem as shown in profiles were taken by installing an acoustic doppler velocimeter in one of the mobile carriages of the flume to get flow hydrodynamics and velocity profiles. nortek acoustic doppler velocimeter (adv) provides time series of instantaneous flow velocity data in three directions (stream wise, vertical, and concerned direction was along the probe (sender/ receiver) of adv was directed towards the flow direction. the stream significant amount while the other directions are extremely lower for that the stream wise considered. ii.3 experimental protocol the first stage of the experiments was to visually identify the combinations of parameters for sphere densities that should be set to get low sphere movement just slightly above threshold flows. channel flow rate was increased by setting the pump of the flume to the required flow rate, a few minutes (3-5) to ensure fully developed steady flow conditions have reached. ensured by checking that the flow depth is the same at different distances downstream along flume and 20 page 4 rough nesses b) side view of the bed roughness motion is captured with video recording speed commercial camera to monitor and sphere motion by capturing the dynamical features of sediment motion. the video is used as a tracking method to capture the position and being transported downstream the the camera operating at 30 frames per second which was placed in the flume near the test section and a little bit downstream from it in order to cover the full length of the bed and to avoid any visual interference with the flow near the test section. used to avoid strong light and facilitate visual tracking of the movements. the whole test section was viewable without any problem as shown in figure 5. flow velocity profiles were taken by installing an acoustic doppler velocimeter in one of the mobile carriages of the flume to get flow hydrodynamics and velocity profiles. the nortek acoustic doppler velocimeter (adv) provides time series of instantaneous flow velocity data in three , vertical, and transverse), but the concerned direction was along the stream flow so the probe (sender/ receiver) of adv was directed towards wise velocity has the most significant amount while the other directions are stream wise velocity is only .3 experimental protocol the first stage of the experiments was to visually identify the combinations of parameters for flow rates and smart densities that should be set to get low sphere just slightly above threshold flows. the flow rate was increased by setting the pump of the flume to the required flow rate, and it was waited for 5) to ensure fully developed steady flow conditions have reached. flow uniformity was by checking that the flow depth is the same at different distances downstream along flume and zaid alhusban et al. ijeca-issn: 2543-3717. june 2020 page 5 sufficiently high to avoid any significant water surface effects and interactions with the smart sphere. the smart sphere was marked with distinct and discernible symbols in a way to observe its orientation from 6 directions (top, bottom, and front, back, 2 sides) to enable monitoring its orientation and its movement downstream. the lead strips that were used to change sphere density were also numbered and pre-weighted to assure the sphere’s weight increased in consistent way. calibrations of the sensor such as the rotation and the vertical axis orientation were done offline, before conducting the experiments, to get reliable data. the sensor was turned on after initiating recording with video, to allow recording the time at which the sensor is turned on. after that the smart sphere was placed on the test area to monitor its transport. the camera and sensor recording were stopped after each sphere transport had ceased, at the end of the flume’s test section. the flow rates, smart sphere densities and bed rough nesses were assessed as they will be changed throughout the experiment. iterations for different densities and flow rates were 3 times for both surfaces to get the best results. consideration was taken to ensure that each experiment started at the same relative condition, this was done by checking the water tank levels before and after operation of pump at the fixed chosen flow rate and adding any water if needed. the adv (figure 2) is used in the test area to record the time series of the instantaneous flow velocityin three directions (stream wise, vertical, and transverse), but the concerned direction was along the stream low so the probe (sender/ receiver) of adv was directed towards the flow direction. the stream wise velocity has the most significant amount while the other directions are extremely lower for that the stream wise velocity is only considered. the probe is placed and oriented to look upstream. adv tracking system moves up and down, the velocity profiles comprise of 7 points along the vertical axis as the probe moves up and down. so, seven points along the depth of the flow were measured by the adv to get stream wise velocities and produce the velocity profiles. in order to ensure sufficient accuracy of the results, the measurement intervals along the vertical axis were denser near the hydraulically rough boundary. each point measurement record is at least 4 minutes long.the sampling rate of adv was 25 hz, which means the adv measured 25 samples per second, then calculated their mean. data acquisition and processing was done automatically by the adv along with matlab software for data processing. figure 6 shows the adv measurement points with the smart sphere resting in front of it. figure 6. side view of the smart sphere resting on the bed with the adv used for velocity profiles measurements iii. results and discussion this section presents methods used to analyse the collected data and the preliminary results from the experimental procedure. flow velocity profles were produced from the adv data to relate the flow hydrodynamics (cause) to the sphere response (outcome), whereas the video recording allowed a qualitative analysis of the wide range of sphere’s dynamical responses. these responses were further measured using the high frequency inertial measurements recorded by the “smart-sphere” (including angular velocities and linear accelerations), these measurements can be related to the near bed hydrodynamic forces acting on it and above threshold flow conditions. iii.1 hydrodynamic data flow velocity profiles were attained at a distance of one diameter upstream the sphere’s face. the profiles comprise of seven points calculated from the channel bed along at depths of 5 mm, 10 mm, 16 mm, 24 mm, 32mm, 42 mm, 50 mm. these points were chosen to be as close to the bed surface, so as the capture the hydrodynamic forcing on the sphere and allow estimating bed shear stresses. for each point, time series of the flow velocity were recorded for 4 minutes and the results were postprocessed to get the average velocity. as predicted, higher flow rates have higher velocities and near the hydraulically rough boundary , the averaged velocity profiles follow closely the logarithmic shape. iii.2 analysis of video recording to qualitatively evaluate the sphere’s responses to the hydrodynamic forces the video recordings were reviewed in slow motion. weak sphere movements were observed for lower flow rates, while for higher flow rates the sphere movements were faster and more energetic (corresponding to greater flow and sphere reynolds zaid alhusban et al. ijeca-issn: 2543-3717. june 2020 page 6 numbers). clearly from figure 7, the measured velocities over depth increase normally with higher depths for the flow rate, the water velocity increased from 18 m/s to 23 m/s when the water depth measured is increased from 15 to 40 mm for the same flow rate of 1.9 m/s. in addition, the measured velocities over depth increase with higher flow rate for the same water depth, the measured velcoity increased from 0.17 to 0.21 m/s when the flow rate increased from 1.47 to 2.12 m/s for water depth of 25 mm. the velocity profiles have closely a logarithmic shape near the hydraulically rough boundary . figure 7. plot of the time-averaged stream wise velocity profiles for different water depths and flow rates for surfaces (a) and (b) iii.3 quantitative input after the calibration of the smart sphere and removing the errors by using filtering and moving averages techniques. the performance of the smart sphere was assessed by comparing its rotation and acceleration readings from the sensors to the video recordings of both top and underwater high-speed camera for a range of flow rates and sphere densities. so the sphere velocity can be compared between lagrangian and eularian frame and by using the data from the inertial sensor and the video from the camera, the instantaneous sphere kinetic energy can be measured to understand the effect of different flow rates on the dynamics of sediment and bed energy interactions. iv. conclusion this study details the introductory results and observations from a series of designed experiments in a flume above threshold conditions. using results from sets of sediment transport experiments with varying flow rates and sphere density, the probability distribution functions (pdfs) of sphere transport features, such as instantaneous sphere velocities, can be generated. the objectives of this research are to employ a novel instrumented sphere , namely ‘smart-sphere’to provide a better understanding of the coarse sediment transport processes at above threshold conditions,test the smart sphere under a range of well controlled flow conditions and to calibrate its response to different near bed hydrodynamic forcing. reference [1] d. sear, m. lee, m. collins, p. carling, "the intelligent pebble: a new technology for tracking particle movements in fluvial and littoral environments. in proceedings of erosion and sediment transport measurement: technological and methodological advances workshop", oslo, norway, 2002, pp. 19–21. [2] m. spazzapan, c j. petrovciˇ, s. miko ˇ, " new tracer for monitoring dynamics of sediment ˇ transport in turbulent flows", actahydrotech. 2004, pp.135–148. [3] d.k. abeywardana, a.p. hu, n. kularatna, "ipt charged wireless sensor module for river sedimentation detection", ieee sensors applications symposium (sas 2012), france, 2012, pp. 1–5. [4] m. valyrakis, e. pavlovskis, "smart-pebble” design for environmental monitoring applications", 11th int. conf. hydroinformatics 2014, hamburg, germany, 2014, pp.4. [5] m. valyrakis, p. diplas, c.l. dancey, "entrainment of coarse particles in turbulent flows: an energy approach". journal of geophysical research, 2013. [6] p. diplas, c. l. dancey, a. o. celik, m. valyrakis, k. greer, t. akar, "the role of impulse on the initiation of particle movement under turbulent flow conditions". science, vol. 322, 2008, pp. 717-720. [7] r. wilson,k. m.brook, "miniaturized wireless sensor node for earthquake simulation and monitoring applications", 7thieee international symposium on industrial embedded systems (sies'12), 2012. [8] g. maniatis, t. hoey, j. sventek, "sensor enclosures: example application and implications for data coherence". journal of sensor and actuator networks, vol 2, 2013, pp. 761– 779. [9] m. valyrakis, a. alexakis. development of a “smartpebble” for tracking sediment transport. international conference on fluvial hydraulics river flow 2016, st. liouis, mo, 2016, pp. 8. 0 10 20 30 40 50 60 0 100 200 300 400 500w a te r d e p th a b o v e d e p th ( m m ) measured velocities (mm/s) adv readings for different water depths and flow rates for surface (a) 23 28.2 33.3 40.5 46.5 channel flow rate (l)/s 0 10 20 30 40 50 60 0 100 200 300 400 500 w a te r d e p th a b o v e b e d ( m m ) measured velocities (mm/s) adv readings for different water depths and flow rates for surface (b) 23 28.2 33.3 40.5 46.5 channel flow rate (l)/s i. introduction ii. experimental investigation iv. conclusion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 09-17 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 9 mechanical speed estimation of a dfig based on the unscented kalman filter (ukf) hicham ben sassi 1 , khadija lahrech 2 , fatima errahimi 3 , najia es-sbai 3 , mokhtar ghodbane 4 1 lseed, private university of fez, morocco 2 laboratory lipi, national school of applied sciences ensa, usmba, fes, morocco 3 laboratory of intelligent systems, georesources and renewable energies (lisgre). faculty of sciences and technology, sidi mohamed ben abdellah university. fez, box 2202, fez, morocco 4 mechanical engineering department, saad dahlab university of blida 1, algeria * corresponding author e-mail: ghodbanemokhtar39@yahoo.com abstract – this work proposes a new estimation technique for the doubly-fed induction generator (dfig) variables. researchers have designed numerous sensorless control strategies for the dfig used either for mechanical speed, electromagnetic torque, or rotor position estimation. in this paper, an analysis of an unscented kalman filter (ukf) will be presented as an observer for both rotor and stator currents, and mechanical speed, which are key information in dfig control. the performance of the proposed observer has been validated in a 9 mw wind turbine under matlab/simulink. based on the results obtained, ukf is safely able to replace mechanically coupled sensors which have many disadvantages such as high cost, maintenance, and cabling requirements. keywords: sensorless control, wind energy, dfig, observers, mechanical speed estimation. received: 31/05/2022 – revised: 20/06/2022 – accepted: 25/06/2022 i. introduction the exploitation of various types of renewable energy sources (solar energy, wind energy, geothermal energy, biomass energy, hydropower) is a particularly viable solution to get rid of dependence on fossil energy sources [1-4]. regarding wind energy, it has presented itself for the last few years as one of the most reliable and promising renewable energy sources, which can successfully replace fossil energy sources in electricity generation [5-7]. accordingly, a lot of research activity has been dedicated recently to the problems of control and optimization of renewable energy conversion systems. when it comes to wind energy harvesting, the doubly-fed induction generator (dfig) has been widely used in recent years because of its high performance, and its capability to operate under variable wind speeds [810]. furthermore, its rotor power converters are sized to transfer only 30% of the total generated power, which is very eye-catching from a cost-effective point of view [11-13]. however, from a control point of view, the dfig is still challenging. many control strategies have been proposed for the dfig in wind energy conversion system (wecs) such as stator voltage orientation (svo) and field oriented control (foc) [14, 15]. the sliding mode control was been presented to overcome the nonlinearity of the system and parameter uncertainties [16, 17]. backstepping control was also used. however, all of those control strategies require exact knowledge of several dfig parameters, and variables such as rotor position and speed, electromagnetic flux, and wind speed. those variables can be obtained by numerous methods such as observers and sensors. nevertheless, the use of sensors has some drawbacks such as the high cost of cables and sensors and the mechanical coupling problems, as well as the high failure rate, which is due to the use of sensors as tools for data acquisition. as an alternative, the sensorless control of the dfig using observers is gaining a lot of interest in the last few years [18]. in this regard, several observers have been proposed in h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 10 the literature for dfig parameters estimation, including mechanical speed, rotor position, electromagnetic flux, and wind speed [19-21]. the model reference adaptive system (mras) based observer and an mras based fuzzy logic technique were used for mechanical speed and rotor position estimation. but because the effectiveness of an mras is highly sensitive to the inductance value, recursive techniques like kalman filters are increasingly being utilized in its place. [22-24]. an extended kalman filter (ekf) was adopted as an observer for the mechanical speed. nevertheless, this method has some drawbacks including the complexity of the linearization process. as a result, this paper proposes as an alternative observer the unscented kalman filter (ukf) to ensure an accurate estimation of the dfig variables [25, 26]. in this paper, the focus will be on the mechanical speed and both stator and rotor currents because of their significance in the dfig control. to obtain the values of these parameters an accurate observer is inevitable ii. wecs modeling ii.1. dfig modeling in the literature, there is no specific and unique model of wecs based on the dfig as shown in figure 1 [27], since the model depends on the adopted control strategy. in general, a dfig based grid-connected wecs consists of a doubly-fed induction generator coupled to the wind turbine through a gear and a shaft. the stator winding of the dfig is directly connected to the utility grid, and the rotor winding is indirectly connected to the grid through a back-to-back voltage source converter and a transformer. filters and physical components are also utilized as extra components to control the dfig during grid faults. figure 1. wind turbine based on the dfig connected to the grid based on the electrical differential equations of both the rotor and the stator, which are converted to direct and quadratic reference with the help of park transformation, the d-q components of the rotor and the stator voltage equations are expressed in eq. (1). these currents are expressed as a function of the stator flux linkages (𝜑�𝑠�𝑑�, 𝜑�𝑠�𝑞�), stator resistance 𝑅�𝑠�, stator currents (𝑖�𝑠�𝑑�, 𝑖�𝑠�𝑞�), stator angular velocity 𝜔�𝑠�, rotor flux linkages (𝜑�𝑟�𝑑�, 𝜑�𝑟�𝑞�), rotor resistance 𝑅�𝑟�, rotor currents (𝑖�𝑟�𝑑�, 𝑖�𝑟�𝑞�), and the slip angular velocity 𝜔�𝑟�. { (1) (2) the equations for the rotor and stator flux linkages are provided in eq. (3), where m is the mutual inductance and lr and ls, respectively, stand in for the rotor and stator self-inductances. { (3) according to the electrical equations of the dfig, the stator and rotor active and reactive powers are given in eq. (4). { (4) one of the most crucial parameters for mechanical speed estimation is the electromagnetic torque which is expressed in eq. (5), as a function of the rotor’s current, stator flux, and both mutual inductance and stator selfinductances, as well as the number of pair of machine poles. (5) h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 11 ii.2. wind turbine model the turbine represents the organ responsible for transforming the kinetic energy of the wind into a mechanical power given in eq. (6). � (6) where is the air density, π 2 , s is the total area swept by the turbine blades and r is the radius of the blades. is the coefficient of power which is the fraction between the kinetic energy of the wind and mechanical power extracted by the turbine. concerning given in eq. (7), it is a function that depends on the pitch angle and the tip speed ratio (λ) gave by eq. (8). (7) (8) the basic dynamic equation of the mechanical system provides an explanation for the change of mechanical speed. (9) where tmec is the mechanical torque, jt is the moment of inertia, and 𝑓� is the viscous friction coefficient. ii.3. dfig state-space model one of the requirements in the design of the unscented kalman filter is a nonlinear state-space model of the dfig. therefore, based on the basic mechanical system dynamic equation "eq. (9), , as well as the differential electrical equations of the dfig previously presented in eqs. (1-5), a state-space model of the dfig is given in eqs. (10) and (11). (10) (11) where x is the stat variable, y is the output (measurement) vector, and u is the input vector. �� �� �� �� �� �� (12) �� �� �� � (13) �� �� �� �� (14) ⌊ ( ) ((( ) ) ) ( ) ( ) ( ) ( ) (( ) ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 2 ⌋ (15) where m2 l l . and ⌊ ⌋ (16) iii. unscented kalman filter iii.1. unscented transformation kalman filters are one of the most powerful algorithms for solving estimation problems. accordingly, an unscented kalman filter (ukf) has been adopted in this work. the unscented transformation (ut) of nonlinear systems serves as the foundation for the ukf. in order to deal with any nonlinearity in the system, this novel approach is based on computing the statistic mean h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 12 and covariance of a random variable that goes through the nonlinear transformation y=f(x). figure 2 depicts the technique's working principal. figure 2. unscented transformation (ut) the ut procedure:  compute a set of sigma points ̃ ̅̅ ̅ ̃ ̅ (√ ) � ̃ ̅ (√ ) � (17) is the scaling parameter. � � 2 (18) while (α) defines the range of sigma points surrounding the mean x value. in most cases, has a value between 0 and 1 ( [0,1]) [26]. the system's dimension is represented by n. the second scaling factor, k, is frequently set to k=3-n. and ̅ are the covariance matrix and x's mean, respectively. the weight assigned to each sigma point is as follows: � ⁄ � 2 � ⁄ (19) as a constraint, the weights must sum up to 1. ∑ 2 � � (20) where is an additional scaling parameter that takes into account knowledge about the distribution of x from the past. the best option in the case of a gaussian distribution is =2. the terms mean and covariance are denoted by the symbols (m) and (c).  use the nonlinear function to propagate each sigma point and produce a series of altered samples. 𝑓 � 𝑓 𝑟��𝑖 (21)  utilizing the weighted mean ̅ and covariance of the prior samples, compute the mean y and covariance matrix for y. ̅ ∑ 2 � 𝑓 𝑟�𝑖 (22) ∑ ̅ 2 ̅ � 𝑓 𝑟�𝑖 (23) iii.2. the unscented kalman filter in this section, an unscented kalman filter (ukf) is adopted for estimating dfig system variables, given that the adopted ukf is a derivative-free filtering algorithm. therefore, as shown in references [26-29], the ukf algorithm for background theory is presented as follows:  step 1. initialization { }; 𝑅 { } ;� { } (24) ̅ ̅ (25) ̅ � (26) where q(k) and r(k) are diagonal matrices that represent respectively the process noise covariance and the observation noise covariance.  step 2. compute sigma points from eq. (17), sigma points can be calculated. ̅ ̅ (√ )� ̅ (√ )� (27)  step 3. prediction phase the propagation of the sigma points through the system/state equation is given by: (28) the following is a formula for calculating propagated mean and covariance: ̅ ∑ 2 (29) h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 13 ∑ 2 ̅ ̅ (30) the new sigma points matrix using is given by: ̅ and 𝑥 . [ ̅ ̅ (√ 𝑥 )� ̅ (√ 𝑥 )] (31) the propagation of the new sigma point through the nonlinear function is given by: 𝑖 (32) a) calculate the mean of the output variable. ̅ ∑ 2 , for i=1,…,2n (33)  step 4. measurement update the covariance between the measurement vector and the cross-covariance is calculated as: ∑ 2 ̅ ̅ (34) ∑ 2 ̅ ̅ (35) kalman gain is given by: (36) the state estimate update and the covariance estimate update are presented as follows: ̂ ̂ ̅ (37) ̂ 𝑥 (38) iv. results and discussion simulation and tests were conducted to verify the robustness of the proposed observer for parameter estimation relying on a 9 mw model of wts based on dfig implemented in matlab/simulink. the wts parameters used for simulations are given in table 1. table 1. parameters used in the simulation name symbol value dfig rated power (base power) pnom 9mw stator voltage (base voltage) unom stator 400v rotor voltage (base voltage) unom rotor 1975v grid frequency f0 50hz number of pair poles p 3 stator resistance rs 0.023(pu) rotor resistance rr 0.016(pu) stator inductance ls 0.18(pu) rotor inductance lr 0.16(pu) mutual inductance m 2.9(pu) figures 3 to 6 exhibit the measured and estimated stator and rotor currents, respectively. the simulation results reveal that the proposed observer ukf works very well in estimating the stator and rotor currents. the simulation results shown in figure 3 show that the ukf performs the estimation of direct and quadratic stator currents. based on these results, it is clear that the tracking performance and convergence velocity of ukf are satisfactory regardless of the rapid differences in currents observed at the start of the simulation. moreover, the rated stator currents given in red are almost identical to the real currents given in red with a maximum error of 1%, which displays the accuracy of the ukf. the results of figures 4 and 5 also show the estimation for the direct and quadratic components of the rotor current. similar to the case of the stator, the rated rotating currents given in blue converge instantly towards the real currents given in red, further illustrating the efficiency of the ukf. figure 6 shows the dynamic response and tracking performance of the ukf for the dfig mechanical velocity estimation, where it is clear that the rated velocity given in red was able to follow the measured velocity with great accuracy of max 1.3%. this confirms and verifies the robustness of the proposed controller and its ability to replace the mechanically coupled sensor. as shown in figures (3-6), the estimated currents converge towards the measured currents instantly and with great accuracy. this reflects the convergence speed of the observer as well as its accuracy. furthermore, based on the results presented in figure 7, it is clear that the estimated velocity of the rotor follows with great accuracy the measured velocity, which h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 14 confirms and verifies the robustness of the proposed observer, and its capability to replace the mechanically coupled sensor. figure 3. estimated and real currents of dfig stator figure 4. estimated and real quadratic currents of dfig stator figure 5. estimated and real direct current of the dfig rotor figure 6. the estimated and real quadratic current of the dfig rotor. h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 15 figure 7. real and estimated speed of the rotor since the performance of the observer is measured based on the speed and accuracy of convergence, in this section the efficiency of the ukf has been compared with other strategies adopted in the literature for estimating the mechanical velocity of dfig. this includes the high-order sliding mode observer (hosmo), which has been studied in study [30]. although hosmo was able to get close to its true rotor speed, it suffers from a collapsing phenomenon that affects the accuracy of the results. moreover, the convergence velocity of hosmo is relatively slow 0.5 seconds compared to that of the ukf which was almost instantaneous. in another study, compared to the mras monitor examined in the study [22], the ukf is also superior in terms of convergence velocity, with the authors stating that mras converges after 18 seconds, while in this paper the ukf took less than 0.1 seconds. for rotor velocity estimation, a second-order generalized integrator is used; however, because the system needs two synchronization cycles, as stated by the authors [31], its convergence velocity is slower than that of the ukf. based on the above results, it can be asserted that ukf is safely able to replace the mechanically coupled sensor as it suffers from several disadvantages including high cost and maintenance, and cabling requirements [32]. furthermore, since the ukf was able to accurately estimate both the direct and quadratic components of the stator and rotor currents, it is possible to rely only on these rated currents rather than the measured currents to control the active and reactive forces of the stator and rotor using eq. (4), as this can help overcome the added noise of existing sensors during power calculation and control. v. conclusion since wind energy has emerged as one of the most dependable and promising renewable energy sources, there has been a lot of interest in trying to improve the efficiency of its conversion systems recently. in this regard, this paper investigated the performances of an unscented kalman filter which is proposed as an alternative for mechanical sensors in speed measurement, whereas, simulations and tests were carried out to verify the robustness of the proposed observer for parameter estimation based on the 9mw model of wts based on dfig applied in matlab/simulink. the obtained results have shown that the ukf was able to track the rotor’s speed with high accuracy and impressive convergence time, which confirms the robustness of the ukf and its suitability for such tasks. therefore, ukf is safely able to replace mechanically coupled sensors which have many disadvantages such as high cost, maintenance, and cabling requirements. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 16 references [1] z. said, m. ghodbane, b. boumeddane, a.k. tiwari, l.s. sundar, c. li, n. aslfattahi, e. bellos, “energy, exergy, economic and environmental (4e) analysis of a parabolic trough solar collector using mxene based silicone oil nanofluids,” solar energy materials and solar cells, vol. 239, 111633. 2022. https://doi.org/10.1016/j.solmat.2022.111633 [2] z. said, p. sharma, n. aslfattahi, m. ghodbane, “experimental analysis of novel ionic liquid-mxene hybrid nanofluid's energy storage properties: modelprediction using modern ensemble machine learning methods,” journal of energy storage, vol. 52, 104858. 2022. https://doi.org/104810.101016/j.est.102022.104858 [3] m. ghodbane, z. said, a.k. tiwari, l. syam sundar, c. li, b. boumeddane, “4e (energy, exergy, economic and environmental) investigation of lfr using mxene based silicone oil nanofluids,” sustainable energy technologies and assessments, vol. 49, 101715. 2022. https://doi.org/10.1016/j.seta.2021.101715 [4] m. ghodbane, boumeddane, k. lahrech, “solar thermal energy to drive ejector hvac systems: a numerical study under blida climatic conditions,” case studies in thermal engineering, vol. 28, 101558. 2021. https://doi.org/10.1016/j.csite.2021.101558 [5] e. douvi, d. douvi, d. pylarinos, d. margaris, “effect of rain on the aerodynamic performance of a horizontal axis wind turbine – a computational study,” international journal of energetica, vol. 6, pp. 25-33. 2021. https://dx.doi.org/10.47238/ijeca.v6i1.158 [6] y. saidi, a. mezouar, y. miloud, m. a. benmahdjoub, m. yahiaoui, “fuzzy logic based robust dvc design of pwm rectifier connected to a pmsg wecs under wind/load disturbance conditions,” international journal of energetica, vol. 4, pp. 37-43. 2019. https://dx.doi.org/10.47238/ijeca.v4i1.84 [7] h. cherif, a. khechekhouche, m. maamir, h. aboub, b. belgasim, “modelling and control of a small domestic wind turbine,” asean journal of science and engineering, vol. 3, pp. 115-122. 2023. https://doi.org/10.17509/ajse.v3i1.44725 [8] h. mesai ahmed, a. bentaallah, y. djeriri, a. mahmoudi, “comparative study between pi and fuzzy pi controllers for dfig integrated in variable speed wind turbine,” international journal of energetica, vol. 4, pp. 8-13. 2019. https://dx.doi.org/10.47238/ijeca.v4i2.102 [9] g. nurettin, a. sevinç, “performance study and analysis between vector control and direct power control for dfig based wind energy system,” international journal of energetica, vol. 6, pp. 13-20. 2021. https://dx.doi.org/10.47238/ijeca.v6i2.175 [10] m. atallah, a. mezouar, kh. belgacem, y. saidi, m. a. benmahdjoub, “modeling and power control of 5th and 3rd order model for dfig applied of wind conversion system,” international journal of energetica, vol. 6, pp. 44-51. 2021. https://dx.doi.org/10.47238/ijeca.v6i2.170 [11] ashwani kumar, sanjay k. jain, “a review on the operation of grid integrated doubly fed induction generator,” international journal of enhanced research in science technology & engineering, vol. 2, pp. 25-37. 2013 [12] a. petersson. analysis, “modeling and control of doublyfed induction generators for wind turbines,” phd thesis, chalmers university of technology. 2005 [13] g. salloum, “contribution à la commande robuste de lamachine asynchrone a double alimentation,” phd thesis, l’institut national polytechnique de toulouse. 2007 [14] c. batlle, a d`oria-cerezo, r. ortega, “a stator voltage oriented pi controller for the doubly-fed induction machine,” proceedings of the 2007 american control conference marriott marquis, new york city, usa, july 11-13, 2007 [15] b. bossoufi, h. a. aroussi, e. m. ziani, a. lagrioui, a. derouich, “low-speed sensorless control of dfig generators drive for wind turbines system,” wseas transactions on systems and control, vol. 4, pp. 514-525. 2014 [16] s. kouadria, y messlem, e. berkouk, “sliding mode control of active and reactive power of dfig for variablespeed wind energy conversion system,” proceedings of the 3 rd international renewable and sustainable energy conference (irsec), marrakech – ouarzazate, morocco, december 10-13, 2015 [17] s. ebrahimkhani, “robust fractional order sliding mode control of doubly-fed induction generator (dfig)-based wind turbines,” isa transactions, vol. 63, pp. 343-354. 2016 [18] m. el azzaoui, h. mahmoudi, c. ed-dahmani, “backstepping control of a doubly fed induction generator integrated to wind power system,” 2 nd international conference on electrical and information technologies, tangier, morocco, pp. 306-311. 2016 [19] m. abdelrahem, c. hackl and r. kennel, “application of extended kalman filter to parameter estimation of doublyfed induction generators in variable-speed wind turbine systems,” international conference on clean electrical power (iccep), pp. 226-233. 2015. https://doi.org/10.1109/iccep.2015.7177628 [20] b. singh and n. k. s. naidu, “direct power control of single vsc based dfig without rotor position sensor,” ieee international conference on power electronics, drives and energy systems (pedes), pp. 1-6. 2012. https://doi.org/10.1109/pedes.2012.6484384 [21] y. majdoub, a. abbou, m. akherraz, “variable speed control of dfig-wind turbine with wind estimation,” international renewable and sustainable energy conference (irsec), pp. 268-274. 2014. https://doi.org/10.1109/irsec.2014.7059879 [22] r. cardenas, r. pena, j. proboste, g. asher, j. clare, “mras observer for sensorless control of standalone doubly fed induction generators,” in ieee transactions on energy conversion, vol. 20, pp. 710-718. 2005. https://doi.org/10.1109/tec.2005.847965 [23] a. mehdi, a. reama, h. benalla, “mras observer for sensorless direct active and reactive power control of dfig based wecs with constant switching frequency,” eleventh international conference on ecological vehicles and renewable energies (ever), pp. 1-7. 2016. https://doi.org/10.1109/ever.2016.7476349 [24] k. belmokhtar, m.l. doumbia, k. agbossou, “novel fuzzy logic based sensorless maximum power point h. ben sassi et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 09-17 page 17 tracking strategy for wind turbine systems driven dfig (doubly-fed induction generator),” energy, vol. 76, pp. 679-693. 2014. https://doi.org/10.1016/j.energy.2014.08.066 [25] m. abdelrahem, c. hackl, r. kennel, “sensorless control of doubly-fed induction generators in variable-speed wind turbine systems,” international conference on clean electrical power (iccep), pp. 406-413. 2015. https://doi.org/10.1109/iccep.2015.7177656 [26] s. j. julier jeffrey k. uhlmann, “a new extension of the kalman filter to nonlinear systems,” the robotics research group, department of engineering science, the university of oxford, proceedings of the ieee, vol. 92. 2004 [27] s. kumar senapati, “modelling and simulation of a grid connected doubly fed induction generator for wind energy conversion system,” thesis for the degree of master department of electrical engineering national institute of technology rourkela, may 2014 [28] y. wu, d. hu, m. wu, x. hu, “unscented kalman filtering for additive noise case: augmented versus nonaugmented,” in ieee signal processing letters, vol. 12, pp. 357-360. 2005. https://doi.org/10.1109/lsp.2005.845592 [29] b. huang, q. wang, “overview of emerging bayesian approach to nonlinear system identification. in round tables on non-linear model identification,” international workshop on solving industrial control and optimization problems, cramado, brazil, april 6–7, 2006 [30] m. benbouzid, b. beltran, h. mangel, a. mamoune, “a high-order sliding mode observer for sensorless control of dfig-based wind turbines,” iecon proc. industrial electron. conf., pp. 4288–4292. 2012. https://doi.org/10.1109/iecon.2012.6389200 [31] a. t. nguyen, d. c. lee, “sensorless control of dfig wind turbine systems based on sogi and rotor position correction,” ieee trans. power electron., vol. 36, pp. 5486–5495. 2021. https://doi.org/10.1109/tpel.2020.3027888 [32] m. pucci, m. cirrincione, “neural mppt control of wind generators with induction machines without speed sensors,” ieee trans. ind. electron., vol. 58, pp. 37–47. 2011. https://doi.org/10.1109/tie.2010.2043043 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 2. 2019 page 42-53 ijeca-issn: 2543-3717. december 2019 page 42 voltage sensorless based virtual flux control of three level npc back-to-back converter dfigunder grid fault imad merzouk 1 , mohamed mounir rezaoui 1 , noureddine bessous 2* , abdsalem gafazi1 1laadi, faculty of science and technology, university of djelfa 17000 dz, algeria 2faculty of science and technology, university of el oued 39000 dz, algeria email*: nbessous@yahoo.fr abstract – in this paper, a harmonic elimination of grid and stator currents of doubly fed induction generator (dfig) in case of grid fault without line voltage sensors is proposed . this can be achieved by compensating power based on virtual flux voltage sensorless technique. direct power control with space vector modulation (dpc-svm) is used to control both grid-side (gsc)and rotor-side converters (rsc). to achieve the control objective, compensated active and reactive powers are calculated based on virtual flux technique with balanced and harmonic free current as a control target. a theoretical analysis of active and reactive powers under unbalanced voltage source is clearly demonstrated and the effect of grid fault on the performance of dfig is profoundly discussed. simulation results verified the effectiveness of the modified control strategy. keywords: dfig,dpc-svm, virtual flux, compensating power, grid fault received: 17/10/2019 – accepted: 25/11/2019 nomenclature 1.1 subscript �:mutual. �, �: two axis stationary reference frame. �, �:two-axis direct and quadrature synchronous reference frame. �, �:stator and rotor reference frame. +, −, 5: positive, negative sequence and harmonic component. 1.2 superscript �, �: angle and angular speed. �, �:time constant and leakage factor. �: source voltage. �: converter terminals voltage. �: line current. �, �: input filter inductance and resistance. �, �: apparent, active and reactive powers. �: machine flux. � : virtual flux. 1.3 abbreviation dfig: doubly fed induction generator. dpc : direct power control gsc: grid side converter. rsc: rotor side converter. pnsc:positive-negative-sequence calculator. pwm: pulse width modulation. sogi: second order general integrator. svm: space vector modulation. abder image placée imad merzouk et al ijeca-issn: 2543-3717. december 2019 page 43 2. introduction doubly fed induction generator (dfig) connected to three level npc back-to-back converter has been widely used in recent years due to its several advantages. some of its advantages are speed operation, controllable power factor, improved system efficiency, very low harmonic distortion, low electromagnetic interferenceand most importantly, reduced converter rating, which is typically 30% of the generation rating , therefore, decreased cost and power loss [1-4]. one drawback of dfig is its sensitivity to any grid distortion because the stator is directly connected to the grid. this fact may limit the use of dfig especially in wind energy generation due to imposed electricity code. hence the power injected in the grid must be performed [5-8]. the control of two level gsc under grid fault was firstly studied in the works of [9-12].based on power analysis under grid unbalance, the referencing currents were calculated and then used in classical voltage oriented control. after that [13] generalized the study to gsc and rsc for dfig. but the control became more complex when the grid is unbalanced and harmonically distorted.in addition, the tuning of pi gains constitutes a barrier to the use of this method. in [13-16 ] a modified dpc for gsc and rsc was proposed to achieve one of three selective control targets: obtaining sinusoidal and symmetrical grid current, removing reactive power ripplesor removing active power ripples under unbalanced supply. the results obtained were good,but the study is in case of unbalance grid only. [17] investigated the method of grid connected three level npc converter and generalized the study to unbalanced and harmonically polluted grid. thus, the introduction of voltage sensorless is a good alternative for robust and economic operation [18]. virtual flux technique is the most responding technique for voltage sensorless control of gsc. in general, filters are used to estimate virtual flux [1921]. but under unbalanced conditions, where the separating positive and negative sequences are needed, cascading filter must be used [22]. however, it creates more time delay and reduces the accuracy. double second order generalized integrator (dsogi) is a good alternative to remove the drawback of cascading filter, it could estimate the virtual flux and separate sequences of virtual flux and grid current [23]. this paper proposes a voltage sensorless control scheme for three level npc back-to-back converter dfig under unbalanced and harmonically polluted grid in order to get sinusoidal and symmetrical grid and stator currents. to achieve that, the referencing current is calculated by the instantaneous power theory. the virtual flux isestimated using dsogi method which is proposed by [23]. the effectiveness of the proposed method is verified by simulation in matlab environment. the electrical circuit of the studied system is ullistrated in figure1 3. modeling of dfig dfig voltage and flux equations, expressed in the rotating reference frame, are given by: ⎩ ⎪ ⎨ ⎪ ⎧��� = ����� + � �� ��� − ����� ��� = ����� + � �� ��� + ����� ��� = ����� + � �� ��� − ����� ��� = ����� + � �� ��� + ����� � (1) ⎩ ⎨ ⎧ ��� = ����� + ����� ��� = ����� + ����� ��� = �����+����� ��� = �����+����� � (2) stator active and reactive powers are given by: � �� = ������ + ������ �� =������ − ������ � (3) setting the stator flux vector aligned to d-axis and neglicting the per phase stator resistance [15]. � ��� = �� ��� = 0 � (4) � ��� = 0 ��� = �� = ���� � (5) substuting in (2). � �� = ����� + ����� 0 = ����� + ����� � (6) the relation between the stator and rotor currents is set from equation(6): � ��� = − �� �� ��� + �� �� ��� = − �� �� ��� � (7) imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure.1. simplified electrical circuit of a 3l-npc back-to-back dfig stator active and reactive powers in (3) can be written as: � �� = −����� = − ���� �� ��� �� = −����� = − ���� �� ��� + �� � ���� � (8) rotor voltages can be expressed by: � ��� = ����� − ��� ��� − �� � �� � ��� ��� = ����� + ��� ��� − �� � �� � ��� + � ���� �� � (9) figure.2 shows the detailed model of dfig. 1 ��� − �� 2 �� � � + �� − �� �� �� 1 ��� − �� 2 �� �� + �� − �� �� �� ��� ��� − �� 2 �� � ��� ��� − �� 2 �� � � �� �� �� �� 2 ���� − − ��� ��� ���� ���� figure.2. simplified model of dfig 4. classical control strategy 4.1. rsc control if we neglect the coupling terms in equation (9), and replace (8) in (9) we can control the stator active and reactive powers. the measured statoricactive and reactive powers are compared with the referencing one, and then pi regulators are used as controllers. the output of pi regulators addedtocompensating terms provide the required rotor voltage as illustrated in figure 3. ��� ��� ��. �� �� ��. �� ���� figure.3. direct active and reactive powerscontrol of dfig 4.2. gsc control for the gsc, the well known dpc-svm is chosen as control algorithm which details is summarized in figure 4. the outer control loop provide the required active power to obtain the desired dc-link voltage level.the measured active and reactive powers are compared with the referencing one, and then pi regulators are used as controllers instead look-up-table[24]. the two regulators provide the reference voltage applied to the input of the converter, after that the switching signals are generated by svm block [25, 26]. figure.4. dpc-svm control of gsc imad merzouk et al ijeca-issn: 2543-3717. december 2019 5. power analysis under grid fault 5.1. virtual flux estimation virtual flux (vf) concept is the most adopted method to estimate grid voltage for gsc. by integrating ac-voltage we get the virtual flux as follows: ���� = ∫ ����� (10) replacing ac-voltage by its equivalent value extracted from the ac-side converter model we get: ���� = ����� + ∫������ + ������� (11) ����is estimated from the switching state and dc-link voltage. under ideal conditions, the vf has only positive-sequence components, but during grid fault, negative and harmonic sequences also appear in the virtual flux. and thus,positive,negative and harmonic sequences have to be separated in order to control the converter.positive and negative sequence calculator (pnsc) is used to calculate the positive and negative sequences for each order harmonics. as shown in figure 5-a the pnsc needs the instantaneous values of the vf and its quadratic value. to get these values, double second order generalized integrator (dsogi) is one of the most feasible solutions proposed so far in the literature for its good results in terms of the accuracy and its capability for grid synchronization [23]. the transfer function for the sogi-qsg is given by: �(�) = �(�)� �(�) = �.��́ ����.�́.���� (12) �(�) = �(�)� �(�) = �.�′ � ����.�́.���′ � (13) the structure of (sogi) is given in fig.5-b. where the constant k is the sogi gain that determines the system dynamics (k is selected as k =√2 for optimum value time response and overshoot). the complete structure of virtual flux estimation with sequences separation is illustrated in figure 6. 5.2. powers equations with the virtual flux approach active and reactive powers can be calculated from: � � = � � �(������ − ������) � = − � � �(������ + ������) � (14) using symmetrical component theory [27]. �� = � � �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) (15) �� = − � � �(��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + �� ���� � ) (16) compared with active and reactive powers obtained under ideal voltages supply, many additional terms appear under grid fault. these terms result from the interaction between each sequence of the voltage (positive, negative and 5 th harmonic) with the sequences of the current separately. these additional terms are responsible of the poor performance of the dfig, especially the distorted stator currents. according to equations (15) and (16) active and reactive powers can be regrouped in four terms: � = ��� + ��� + ��� + ��� (17) where: ⎩ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎧��� = 3 2 �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) +��� � ��� � − ��� � ��� � ��� = 3 2 �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) ��� = 3 2 �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) ��� = 3 2 �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) � (18) p1 is the average active power delivered to the stator and it is a constant power. p2 represents the interaction between the positive and the negative sequences of the voltages and the currents. p3 represents the interaction between the positive and the 5 th harmonic sequences of the voltages and the currents. p4 represents the interaction between the negative and the 5 th harmonic sequences of the voltages and the currents. the same analysis was carried for the reactive power: imad merzouk et al ijeca-issn: 2543-3717. december 2019 + + 1 1 s s k sogi � � � �� + + + + + + 1/2 1/2 pnsc �αβ � sogi sogi �α ��α �β ��β ��� + ��� − figure.5. pnsc and sogi structure + + + + + + + + + + + + � � � � � � � � � � � � ���� ���� ���� ���� + + + + + + + + + + + + � � � � � � � � � � � ���� ���� ���� ���� � �sogi 1 �sogi2 �sogi3 �sogi 1 �sogi2 �sogi3 �sogi n �sogi n � resistance voltage compensation inductor flux compensation ����� � ���� � ����� 3 ���� 3 ���� 2 ����� 2 ����� 1 ���� 1 ���� 1+ ���� 1− ���� 2− ���� 2+ ���� 3+ ���� 3− ���� �− ���� �+ ���� � ���� � ���� � ���� �−1 ���� 3 ���� 3 ���� 2 ���� 2 ���� 2 ���� 1 ���� 1 ���� 1 ���� ���� 1+ ���� 1− ���� 2− ���� 2+ ���� 3+ ���� 3− ���� �− ���� �+ ���� �− ���� �+ ���� 3− ���� 3+ ���� 2+ ���� 2− ���� 1− ���� 1+ ���� 1 ����� 1 ����� 2 ���� 2 ���� 3 ����� 3 ����� � ���� � ���� 1 ���� 1 ���� 1 ���� 2 ���� 2 ���� 2 ���� 3 ���� 3 ���� � ���� � ���� � ���� �−1 ���� figure.6. complete structure of virtual flux estimation with sequence separation imad merzouk et al ijeca-issn: 2543-3717. december 2019 � = ��� + ��� + ��� + ��� (19) ⎩ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎧��� = − 3 2 �(��� � ��� � + ��� � ��� � + ��� � ��� � +��� � ��� � + ��� � ��� � + ��� � ��� � ) ��� = − 3 2 �(��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � ) ��� = − 3 2 �(��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � ) ��� = − 3 2 �(��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � ) � (20) 6. modified control strategy classical dpc shows good performance under ideal voltage supply. but, unbalanced and or harmonically polluted grid voltages will result in significant low-order harmonic components in the grid and stator currents, which are caused by the negative and harmonic components in the voltages. thus, in this paper,a modified strategy is proposed to improve the behavior of dfig under grid fault. for symmetrical and harmonic free components of stator/grid current we must make the negative component of current in equations (15) and (16) equal to zero so we get: ⎩ ⎪ ⎨ ⎪ ⎧ �� = � � �(��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � + ��� � ��� � − ��� � ��� � ) �� = − � � �(��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � + ��� � ��� � ) �(21) omparing equations (21) and (14) we get the compensation power as: ⎩ ⎪ ⎨ ⎪ ⎧ ������ = � � (��� � ��� � − ��� � ��� � +��� � ��� � − ��� � ��� � ) ������ = � � (��� � ��� � + ��� � ��� � +��� � ��� � + ��� � ��� � ) � (22) the same analysis carried out for gsc was used to control rsc, substituting grid current by stator current in all active and reactive power equations. 7. simulation results simulation studies of the gsc and rsc under unbalanced and grid fault conditions were carried out using matlab/simulink. the system parameters are given in the appendix. the complete structure of the proposed control is shown in figure7. 7.1 balanced case the grid is assumed balanced and perfectly sinusoidal with a change in the reference value of the active power of dfig at instant 0.8 s (from -1.5 to -2mw) and an increase of the reactive power at instant 1s (from 0 to 30kvar) of gsc. the result are shown in figs.8 to 12. + + + + + vdc 1 vdc 2 ��� �� � � � � � � �� �� ��� �� + + + + + + + �� �� �� �� �� �� �� �scal qscal �scomp qscomp �sref qsref �gref qgref �gcal qgcal �gcomp qgcomp ����� ����� � � ��� +,− ���� +,− � ���� +,− � figure.7. control scheme under grid fault imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure.8. dc-link voltage, vdc1and vdc2 figure.9. grid current, voltage and current figure.10. grid estimated and measured active and reactive powers figure.11. stator active and reactive powers figure.12. virtual flux components it is noted that dc voltage follows its reference and the balancing of continuous sources is always ensured as shown in fig.8. grid currents are sinusoidal and balanced with a unit power factor that shifts with the change in reactive power. the change of the stator power causes a proportional variation in the power of gsc but does not affect the value of the continuous bus as well as the reactive power on the gsc. the change of the reactive power on the grid causes a change in the power factor on the grid side, however, and all the other quantities remain practically unchanged. the measured and estimated active and reactive powers are coincide as seen in fig.10, so the dsogi can estimate the active and reactive powers with infinite precision. figure12 shows the (α and β) component of the virtual flux. it is clear that the sogi is able to estimate the virtual flow with a good dynamic and excellent robustness with respect to the changes made. 7.2 unbalanced case introducing a voltage drop of 20% in phase 3 at time 0.7s then an overvoltage of 20% in phase 1 at time 0.8s. the compensation powers are injected at the instant 0.9s for gsc and 1s for rsc and the results obtained are shown in the figures above. 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1900 1950 2000 2050 2100 2150 2200 v d c (v ) 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 850 900 950 1000 1050 1100 1150 t(s) v d c 1 ,2 0.75 0.8 0.85 0.9 0.95 1 1.05 -200 -150 -100 -50 0 50 100 150 200 ig a b c (a ) 0.95 0.96 0.97 0.98 0.99 1 1.01 1.02 1.03 1.04 1.05 -600 -400 -200 0 200 400 600 t(s) e g a ,3 x ig a 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 -1.5 -1.4 -1.3 -1.2 -1.1 -1 -0.9 -0.8 x 10 5 p g ,p g e 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 -1 0 1 2 3 4 5 6 x 10 4 t(s) q g ,q g e pge pg qge qg 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 -2.5 -2 -1.5 -1 x 10 6 p s (w ) 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 -5 0 5 x 10 5 t(s) q s (v a r) 0.75 0.8 0.85 0.9 0.95 1 1.05 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 t(s) p h ig a lp h a ,p h ig b e ta imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure.13. dc-link voltage, vdc1and vdc2 figure.14. grid current, voltage and current figure.15. grid estimated and measured active and reactive powers figure.16. positive, negative component of virtual flux and positive component of current in figures. 13~16, the behavior of the gsc has been demonstrated. after the introduction of the compensation powers, the system remained stable and the currents became balanced and sinusoidal with a unit power factor. the estimated and measured active and reactive powers are coincide with each other. in figure16, we see that the negative sequence of the virtual flux is zero before the instant 0.7s, then we detect a negative sequence with a transient time about 0.02s and its amplitude is amplified at instant 0.8s. figure.17. stator active and reactive powers 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1900 1950 2000 2050 2100 v d c (v ) 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 920 940 960 980 1000 1020 1040 1060 1080 t(s) v d c 1 ,2 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -150 -100 -50 0 50 100 150 ig a b c (a ) 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -800 -600 -400 -200 0 200 400 600 800 t(s) e a ,3 x ig a 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -11 -10.5 -10 -9.5 -9 -8.5 -8 -7.5 x 10 4 p g (w ) 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -2 -1.5 -1 -0.5 0 0.5 1 1.5 x 10 4 t(s) q g (v a r) 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -2 -1 0 1 2 p h ia lp h a + ,b e ta + (w b r) 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -0.2 -0.1 0 0.1 0.2 p h ia lp h a -, b e ta -( w b r) 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -100 -50 0 50 100 t(s) ia lp h a + ,i b e ta + (a ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -1.8 -1.7 -1.6 -1.5 -1.4 -1.3 -1.2 x 10 6 p s (w ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -3 -2 -1 0 1 2 3 x 10 5 t(s) q s (v a r) imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure.18. stator and rotor current the same conclusion can be made for the gsc whose results are shown in figures.17 and 18. it is observed that the control proposed is capable of improving the waveform of the stator currents by acting on the rotor variables. stator currents become sinusoidal and balanced and rotor current fluctuations are minimized with the presence of ripples in the stator power. 7.3 distorted case to verify the wide validity of the proposed method, a test of the cascade under harmonically polluted grid was performed. in our case, the disturbance is the superposition of 20% of the 5 th harmonic on the fundamental of the grid voltage. the system parameters and operating point are always kept the same as before. the presence of the 5 th harmonic in the grid creates pulsating terms in the dc voltage, their frequency is six times that of the grid frequency. the reflected pulses combined with the svm fundamentals generate the 7 th order harmonic in the grid currents. these harmonics can be eliminated by applying the proposed command as shown in figuress.19~22. the thd of the grid currents of the proposed control is only 1.19%, contrary to conventional methods which have a thd of 20.56%. figure.19. dc-link voltage, vdc1and vdc2 figure.20. grid current, voltage and current figure.21. grid estimated and measured active and reactive powers 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -3000 -2000 -1000 0 1000 2000 3000 is a b c (a ) 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 -3000 -2000 -1000 0 1000 2000 3000 t(s) ir a b c (a ) 0.8 0.85 0.9 0.95 1 1.05 1900 1950 2000 2050 2100 v d c (v ) 0.8 0.85 0.9 0.95 1 1.05 900 950 1000 1050 1100 t(s) v d c 1 ,2 0.85 0.9 0.95 1 -150 -100 -50 0 50 100 150 ig a b c (a ) 0.85 0.9 0.95 1 -800 -600 -400 -200 0 200 400 600 800 t(s) e a ;3 x ig a 0.85 0.9 0.95 1 1.05 -12 -11 -10 -9 -8 -7 -6 x 10 4 p g (w ) 0.85 0.9 0.95 1 1.05 -3 -2 -1 0 1 2 x 10 4 t(s) q g (v a r) imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure ig.22. positive, 5th harmonic component of virtual flux and positive component of current likewise, the grid fault has a harmful impact on the stator and rotor currents of the dfig as shown in figures.23 and 24. but after the injection of the compensation powers at the instant 1s, we observe a significant improvement in the waveform of the stator currents where the thd is decreased from 20.56 % to 3.94% driven by a minimization of the fluctuations in the rotor currents. figure.23. stator active and reactive powers figure.24. grid current, voltage and current 7.4 unbalanced and distorted case finally the system is tested under a very severe case where the imbalance and the harmonic are introduced together. as shown infigures.25,26 and 27, the control technique proposed with the virtual flux always proves its validity under all conditions. the sogi is capable of estimating and decomposing the virtual flux with precession and with good dynamics. the target objective is achieved and, in our case, we were able to have sinusoidal and balanced currents on the grid and stator. the stability of the system is always assured in the different passages from the ideal to the abnormal. figure.25. from the top to the bottom: dc-link voltage, grid current, grid active and reactive powers 0.75 0.8 0.85 0.9 0.95 1 -2 -1 0 1 2 p h ig a lp h a + ,b e ta + (w b r) 0.75 0.8 0.85 0.9 0.95 1 1.05 -200 -100 0 100 200 p h ig a lp h a 5 ,b e ta 5 (w b r) 0.75 0.8 0.85 0.9 0.95 1 1.05 -200 -100 0 100 200 t(s) ig a lp h a + ,b e ta + (a ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -2 -1.8 -1.6 -1.4 -1.2 -1 x 10 6 p s (w ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -5 0 5 x 10 5 t(s) q s (v a r) 0.85 0.9 0.95 1 1.05 -3000 -2000 -1000 0 1000 2000 3000 is a b c (a ) 0.85 0.9 0.95 1 1.05 -3000 -2000 -1000 0 1000 2000 3000 t(s) e a ,i s a 0.75 0.8 0.85 0.9 0.95 1 1.05 1800 1900 2000 2100 v d c (v ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -100 0 100 ig a b c (a ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -1.5 -1 -0.5 x 10 5 p g (w ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -5 0 5 x 10 4 t(s) q g (v a r) imad merzouk et al ijeca-issn: 2543-3717. december 2019 figure. 26. from the top to the bottom: positive,negative, 5th harmonic component of virtual flux and positive component of current figure.27. stator active and reactive powers, stator current, stator current and voltage 8. conclusion this paper has proposed sensorless compensated control scheme based on improved direct power control with space vector modulation (dpc-svm) for doubly fed induction generator supplied by distorted grid voltage. in order to obtain sinusoidal grid and stator currents under grid distortion, compensated powers are calculated and added to the original referenced power to achieve balanced and high quality grid/stator current. the positive, negative and harmonic sequences of the virtual flux and the current are extracted using sogi filter. the proposed method proves its capability of yielding sinusoidal grid and stator currentwith unity power factor under severe unbalanced voltage source. references 1. portillo, r. ; vazquez, s.; leon, j.i.; parts, m.m and franquelo, l.g." model based adaptive direct power control for three-level npc converters". ieee transactions on industrial informatics, vol. 9,no 2,pp. 1148–1157.2013.doi: 10.1109/tii.2012.2209667. 2. belkacembelkacem, abdelhakem-koridaklahouari, rahlimostefa." comparative study between spwm and svpwm control of a three level voltage inverter dedicated to a variable speed wind turbine ". journal of power technologies 97 (3) (2017) 190– 200. 3. alejandro, c.p; salvador. a; josep, b; patricio, c.; and jose, r "predictive control of a back-to-back npc converter-based wind power system". ieee transactions on industrial electronics, vol 63,no7, pp.4615-4627,2016. doi: 10.1109/tie.2016.2529564. 4. fangzhou cheng and all, '' rotor-current-based fault diagnosis for dfig wind turbine drivetrain gearboxes using frequency analysis and a deep classifier'' ieee transactions on industry applications, vol.54 , no 2, pp. 1062 1071, 2018. doi: 10.1109/tia.2017.2773426. 5. david santos-martin, joseluis rodriguez-amenedo and santiago amalte" direct power control applied to doubly fed induction generator under unbalanced grid voltage conditions" ieee transactions on power electronics, vol.23, no.5. pp 2328-2335, 2008. doi: 10.1109/tpel.2008.2001907. 6. m. itsaso martinez, gerardo tapia, anasusperregui and haritzacamblong" dfig power generation capability and feasibility regions under unbalanced grid voltage conditions" ieee transactions on energy conversion, vol.26, no. 4,pp.1051-1062, 2011. doi: 10.1109/tec.2011.2167976. 7. x. y. xiao, r. h. yang, x. y. chen and z. x. zheng, ''integrated dfig protection with a modified smesfcl under symmetrical and asymmetrical faults," in ieee transactions on applied superconductivity, vol. 28, no. 4, pp. 1-6, 2018. doi: 10.1109/tasc.2018.2802782. 8. dehongxu,fredeblaabjerg,wenjie chen ,nan zhu " analysis of dfig under distorted grid voltage" in . fredeblaabjerg, dehongxu ,wenjie chen, nan zhu "advanced control of doubly fed induction generator for wind power systems". 139 165edition: 2018 1 online isbn: 9781119172093 publisher: wiley-ieee press. doi: 10.1002/9781119172093.ch6 9. eloy-garcia, j.; arnaltes, s ;andredriguez-amenedo, j.l." direct power control of voltage source inverters with unbalanced grid voltages. iet power electron, vol. 1, no. 3,pp. 395– 407, 2007. doi: 10.1109/tasc.2018.2802782. 10. jiabing hu, andyikang he, "modeling and control of grid-connected voltage-sourced converters under generalized unbalanced operation conditions", ieee transactions on energy conversion, vol. 23, no. 3, pp. 903-913, 2008. doi: 10.1109/tec.2008.921468. 11. xiao, .p.; corzine, k.a.; and vena yagamoorthy, g.k" multiple reference frame-based control of three-phase pwm boost rectifiers under unbalanced and distorted input conditions" ieee transactions on power electronics, vol.23, no.4, pp.2006–2017, 2008.doi: 10.1109/tpel.2008.925205. 0.75 0.8 0.85 0.9 0.95 1 1.05 -2 0 2 p h ia lp h a + ,b e ta + 0.75 0.8 0.85 0.9 0.95 1 1.05 -0.2 0 0.2 p h ia lp h a -, b e ta 0.75 0.8 0.85 0.9 0.95 1 1.05 -0.5 0 0.5 p h ia lp h a 5 ,b e ta 5 0.75 0.8 0.85 0.9 0.95 1 1.05 -100 0 100 t(s) ia lp h a + ,i b e ta + 0.75 0.8 0.85 0.9 0.95 1 1.05 -2.5 -2 -1.5 -1 x 10 6 p s (w ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -1 0 1 x 10 6 q s (v a r) 0.75 0.8 0.85 0.9 0.95 1 1.05 -2000 0 2000 is a b c (a ) 0.75 0.8 0.85 0.9 0.95 1 1.05 -2000 0 2000 t(s) e a ;i s a https://doi.org/10.1109/tii.2012.2209667 https://doi.org/10.1109/tie.2016.2529564 https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22first%20name%22:%22fangzhou%22&searchwithin=%22last%20name%22:%22cheng%22&newsearch=true&sorttype=newest https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=28 https://doi.org/10.1109/tia.2017.2773426 https://doi.org/10.1109/tpel.2008.2001907 https://doi.org/10.1109/tec.2011.2167976 https://doi.org/10.1109/tasc.2018.2802782 https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22first%20name%22:%22dehong%22&searchwithin=%22last%20name%22:%22xu%22&newsearch=true&sorttype=newest https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22first%20name%22:%22frede%22&searchwithin=%22last%20name%22:%22blaabjerg%22&newsearch=true&sorttype=newest https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22first%20name%22:%22wenjie%22&searchwithin=%22last%20name%22:%22chen%22&newsearch=true&sorttype=newest https://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22first%20name%22:%22nan%22&searchwithin=%22last%20name%22:%22zhu%22&newsearch=true&sorttype=newest https://onlinelibrary.wiley.com/action/dosearch?contribauthorstored=blaabjerg%2c+frede https://onlinelibrary.wiley.com/action/dosearch?contribauthorstored=xu%2c+dehong https://onlinelibrary.wiley.com/action/dosearch?contribauthorstored=chen%2c+wenjie https://onlinelibrary.wiley.com/action/dosearch?contribauthorstored=zhu%2c+nan https://onlinelibrary.wiley.com/doi/book/10.1002/9781119172093 https://doi.org/10.1002/9781119172093.ch6 https://doi.org/10.1109/tasc.2018.2802782 https://doi.org/10.1109/tec.2008.921468 https://doi.org/10.1109/tpel.2008.925205 imad merzouk et al ijeca-issn: 2543-3717. december 2019 12. shang, l.; sun, d.; and hu, j. "sliding-mode-based direct power control of grid connected voltagesourced inverters under unbalanced network conditions" iet power electronics, vol. 4, no 5,pp. 570–579. 2011.doi: 10.1049/iet-pel.2010.0160. 13. jiabing hu, hailiangxu and yikang he " coordinated control of dfig’s rsc and gsc under generalized unbalanced and distorted voltage conditions" ieee transactions industrial electronics, vol. 60, no.7,pp. 2808-2019, 2013. doi: 10.1109/tie.2012.2217718. 14. shang l, hu j" sliding-mode-based direct power control of grid-connected windturbine-driven doubly fed induction generators under unbalanced grid voltage conditions" ieee transactions on energy conversion, vol. 27,no.2, pp. 362–373,2012 . doi: 10.1109/tec.2011.2180389. 15. hengnian and yipeng song "direct power control of doubly fed induction generator under distorted grid voltage" ieee transactions on power electronics, vol. 29, no. 2, pp. 894-905, 2014. doi: 10.1109/tpel.2013.2258943 16. j.s. solís-chaves and all " a direct power control for dfig under a three phase symmetrical voltage sag condition" control engineering practice, vol 65,pp 48–58, 2017. https://doi.org/10.1016/j.conengprac.2017.05.002 17. imad merzouk, mohamed lokmanebendaas "improved direct power control for 3-level ac/dc converter under unbalanced and/or distorted voltage source conditions" turkish journal of electrical engineering & computer sciences, vol. 24, no.3, pp. 1847-1862, 2016. 18. haitao yang, yongchang zhang, nong zhang, paul d walker and jihaogao, "a voltage sensorless finite control set-model predictive control for three-phase voltage source pwmrectifiers". chinese journal of electrical engineering, vol. l0 ,no.3 , pp. 52 59, 2016. doi: 10.23919/cjee.2016.7933126. 19. yong, s. c.; and lee, k.b."virtual-flux-based predictive direct power control of three-phase pwm rectifiers with fast dynamic response". ieee transactions on power electronics, vol. 31, no. 4,pp. 3348-3359,2016. doi: 10.1109/tpel.2015.2453129. 20. xiong xiao ; yongjun zhang ; xian song ; tanjuyildirim ; fei zhang "virtualfluxdirectpowercontrol for pwm rectifiers based on an adaptive sliding mode observer" ieee transactions on industry applications, vol. 54 , no. 5, pp. 5196 5205, 2018. doi: 10.1109/tia.2018.2832122. 21. zhenbin zhang, he xu, ming xue, zhe chen, tongjing sun, ralph kennel, and christoph m. hackl, "predictive control with novel virtual-flux estimation for back-to-back power converters". ieee transactions on industrial electronics, vol. 62, no. 5, pp. 2823-2834,2015. doi: 10.1109/tie.2014.2361802. 22. pedro rodríguez, alvaro luna, ignacio candela, ramon mujal, remus teodorescu, and fredeblaabjerg, "multiresonant frequency-locked loop for grid synchronization of power converters under distorted grid conditions". ieee transactions on industrial electronics, vol. 58, no. 1, pp.127-138, 2011. doi: 10.1109/tie.2010.2042420. 23. jon are suul; alvaro luna; pedro rodríguez; tore undeland, "virtual-flux-based voltage-sensor-less power control for unbalanced grid conditions". ieee transactions on power electronics, vol. 27, n, pp. 4071 4087, 2012.doi: 10.1109/tpel.2012.2190301. 24. yong, chang, z.; and chang, qu." table-based direct power control for three-phase ac/dc converters under unbalanced grid voltages". ieee transactions on power electronics, vol. 30, no12, pp. 7090-7099,2015.doi: 10.1109/tpel.2014.2387694. 25. kulikowski, k.; and sikorski, a." new dpc lookup tabl e methods for three-level ac/dc converter". ieee transactions on industrial electronics, vol.63,no12,pp. 7930-7938. 2016. doi: 10.1109/tie.2016.2538208. 26. dan, s. ; xiao, h.w. ; yang, f. backstepping "backstepping direct power control without phaselocked loop of ac/dc converter under both balanced and unbalanced grid conditions "iet power electronics, vol.9,no 8,pp. 1614–1624, 2016. doi: 10.1049/iet-pel.2015.0653. 27. yashan hu, ziqiang zhu, ieee, and milijanaodavic" instantaneous power control for suppressing the second-harmonic dc-bus voltage under generic unbalanced operating conditions" ieee transactions on power electronics, vol. 32, no. 5, 2017. doi: 10.1109/tpel.2016.2584385. appendix table 1. power circuit parameters items symbol value nominal power p 2mw stator resistance �� 12 �ω rotor resistance �� 21 �ω stator inductance �� 0.0137 h rotor inductance �� 0.01367 h mutual inductance �� 0.0135h number of pole pairs � 2 input filter inductance l 12�h input filter resistance � 0.3ω dc-bus capacitor ��� 500μ� dc voltage ��� 400� ac source voltage � 690� https://doi.org/10.1049/iet-pel.2010.0160 https://doi.org/10.1109/tie.2012.2217718 https://doi.org/10.1109/tec.2011.2180389 https://doi.org/10.1109/tpel.2013.2258943 https://doi.org/10.1016/j.conengprac.2017.05.002 http://ieeexplore.ieee.org/document/7933126/ http://ieeexplore.ieee.org/document/7933126/ http://ieeexplore.ieee.org/document/7933126/ http://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=7873788 http://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=7873788 https://doi.org/10.23919/cjee.2016.7933126 https://doi.org/10.1109/tpel.2015.2453129 https://ieeexplore.ieee.org/document/8353122/ https://ieeexplore.ieee.org/document/8353122/ https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=28 https://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=28 https://doi.org/10.1109/tia.2018.2832122 https://doi.org/10.1109/tie.2014.2361802 https://doi.org/10.1109/tie.2010.2042420 http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.jon%20are%20suul.qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.alvaro%20luna.qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.pedro%20rodr%c3%adguez.qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.tore%20undeland.qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=%22authors%22:.qt.tore%20undeland.qt.&newsearch=true http://ieeexplore.ieee.org/xpl/recentissue.jsp?punumber=63 http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=6200448 https://doi.org/10.1109/tpel.2012.2190301 https://doi.org/10.1109/tpel.2014.2387694 https://doi.org/10.1109/tie.2016.2538208 https://digital-library.theiet.org/content/journals/10.1049/iet-pel.2015.0653 https://digital-library.theiet.org/content/journals/10.1049/iet-pel.2015.0653 https://digital-library.theiet.org/content/journals/10.1049/iet-pel.2015.0653 https://doi.org/10.1049/iet-pel.2015.0653 https://doi.org/10.1109/tpel.2016.2584385 nomenclature 1.1 subscript 1.2 superscript 2. introduction 3. modeling of dfig 4. classical control strategy 4.1. rsc control 4.2. gsc control 5. power analysis under grid fault 5.1. virtual flux estimation 5.2. powers equations 6. modified control strategy 7. simulation results 7.1 balanced case 7.2 unbalanced case 7.3 distorted case 7.4 unbalanced and distorted case 8. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 01-08 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 1 pv energy generation assessment based si-crystalline and cis technologies under algerian climatic conditions aziz haffaf 1* , fatiha lakdja 1 1 electro-technical department, faculty of technology, electro-technical engineering laboratory, saida university, 20000. algeria * corresponding author e-mail: azzoz28@hotmail.fr abstract – as in the whole world, renewable energies in algeria, including photovoltaic energy, are attracting more and more attention in recent years . the integration of distributed generation (dg) into the power grid using renewable energy sources, such as pv, fc and wind, has important advantages such as low distribution losses, better continuity and power quality, and high system reliability. this paper is about a simulation study to analyze the energy assessment of a gridconnected photovoltaic system (gcpvs). the system with 1 mw capacity is simulated and analyzed based on solar resource, tilt and azimuth angles for each area and using si-crystalline and cis technologies under different weathers conditions in algeria (algiers, chlef, tlemcen, tamanrasset and el oued). the system configuration is simulated using the new version of pvgis to account for pv plant energy output assessment. the obtained simulation results were discussed as per monthly and yearly values based on pv cell technologies and optimized tilt and azimuth angle. keywords: solar energy, pv energy assessment, pv grid-connected, pv cells technologies, pvgis tool. received: 01/04/2022 – revised: 30/05/2022 accepted: 16/06/2022 i. introduction today, power systems based renewable energy (psre) are becoming increasingly popular due to the increasing demand for energy and concerns about greenhouse gas (ghg) emissions that will cause environmental problems, i.e. global warming and climate change [1]. the demand for electricity increases due to population growth and industrialization, renewable energy sources are being used more and more, while fossil fuel sources are decreasing [2]. algeria is promoting the renewable energy program to minimize greenhouse gas emissions and protect its fossil fuel resources, like many other nations around the world and due to the energetic setting characterized by the progressive depletion of fossil fuels and global warming. in order to achieve this, the ministry of energy and mines introduced an extensive renewable energy initiative in 2011 [3]. this program is mainly based on photovoltaic solar energy. the target to be reached by 2030 is that about 40% of the electricity generation for domestic consumption comes from renewable energy sources (res). over the past decades, solar pv has grown steadily at about 40% per year through its use in grid-connected pv power plant [4]. due to its vast accessibility, solar energy is one of the most promising renewable energy sources. the annual installed capacity of solar pv rose by at least 50% to at least 75 gw in 2016, bringing the total installed capacity to 303 gw globally [5]. because the technological advances have drastically reduced the cost of solar photovoltaic modules, by about 80% between the years 2008 and 2015 [6]. the conversion of solar energy into other useful energy can be achieved by many techniques [7]. one of them, the solar photovoltaic system, is used to produce electricity based on the photovoltaic effect. the solar pv system can be used in two ways, for isolated application and/or grid connected mode [8,9]. most recently installed solar systems nowadays are wired into the utility grid [10]. in 2020, the world's cumulative solar pv capacity was 773.2 giga-watts, with 138 giga-watts of new pv capacity aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 2 installed that year [11]. the statistical data show that pv systems are now developing in three main categories: small photovoltaic systems (1-5 kw) used in residential application and private homes. medium pv systems used in industrial, commercial, and office buildings (usually 10250 kw). centralized pv power plants or large-scale grid connected system ranging (100 kw up to 5 mw). the large-scale grid connected pv systems with the rated capacity ranging from 1 mwp to hundreds of megawatts or even more are generally connected to the utility grid on the medium (20 kv/35 kv) or high-voltage side (110 kv). the primary purposes of renewable energy resources integration are environmental advantages using free sources of energy. as well, in order to remove the necessity of high-voltage transmission lines, they can be used close to the consumption centers. also, because distribution lines cause significant losses, distributed generation (dg) come with some advantages like: better power quality, low distribution losses and high system reliability [2,10]. in this study, we provide the evaluation and the performance assessment of a mega scale grid connected pv system for some areas in algeria which is algiers, tamanrasset, chlef, tlemcen and el oued ii. renewable energy statue in algeria as mentioned in the introduction section, the algerian government is now seeking to reduce the economy's dependence on hydrocarbons, which account for 98% of the country's currency income [12]. table 1. solar potential in algeria areas coastal high plains sahara surface (%) 4 10 86 area (km 2 ) 95.270 238.174 2,048,279 mean daily sunshine duration (h) 7.26 8.22 9.59 average duration (h/y) 2650 3000 3500 average energy (kwh/m 2 /y) 1700 1900 2650 solar daily energy density (kwh/m 2 ) 4.66 5.21 7.26 potential daily energy (twh) 443.96 1240.89 14,780.63 due to algeria's year-round abundance of sunshine, particularly in the sahara (total potential daily energy of 16,555.48 twh). according to the world energy council (wec) [13] and other sources and as indicated in table 1, the climate in algeria is conducive to the growth of renewable energies, particularly solar energy [14–18]. to meet the aim of 40% of power generation by 2030, as indicated in figure 1, the overall percentage of renewable energies re, which are growing more and more important, is anticipated to increase annually [19]. from the year 2011 to 2030, the programmer of energy production is summarized in figure 2. assessing and prediction the possible energy production from pv power plant is an important criteria which has to be focused in this study. the purpose of this work is to provide a general overview of the feasibility and production of photovoltaic systems in some regions of algeria, which can help the government, researchers and energy investors to make decisions for the exploitation and utilization of photovoltaic systems for the electricity generation. figure 1. contribution of re for power generation figure 2. structure of the national power generation in mw [19] iii. proposed case study this study provides the evaluation and the performance assessment of a mega scale grid connected pv system for some areas in algeria which is algiers, tamanrasset, chlef, tlemcen and el oued. author in [20] used the monthly average clearness index parameter to define the different aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 3 climatic zones as shown in figure 3. four zones are for different climatic conditions in algeria which are bound in the following limits [21]. figure 3. algerian climatic regions classification [22] zone i : k 0.548tm  zone ii : 0.548 k 0.609tm  zone iii : 0.609 k 0.671tm  zone iv : k 0.671tm  where; ktm is the monthly average clearness index. the geographical data and the distribution of climatic zones for the five selected sites located in algeria are presented in the table 2. as can be seen in this table, the selected locations are distributed over various latitudes and have different climatic conditions. figure 4 shows the locations of five selected areas in algeria. table 2. geographical data and climatic zones for the selected sites [21,23] name of site lati (°) long (°) l. a. m (m) climatic zones algiers 36.3 3.15 e 25 i tlemcen 34.5 1.19 e 810 ii chlef 36.08 1.17 e 112 ii el oued 33.21 6.5 e 84 iii tamanrasset 22.4 5.31 e 1378 iv figure 4. sites locations in algeria maps iii.1. pv grid connected system figure 5 shows the schematic view of the components of a grid connected photovoltaic system, consisting of pv modules, a dc/ac converter, and the electrical grid [24]. the photovoltaic effect is a physical phenomenon specific to certain materials called semiconductors that generate electricity when exposed to the sunlight. these pv materials include several types of solar pv cells such as cadmium telluride (cdte) or copper-indium gallium-selenide (cigs)), thin films (amorphous silicon (a-si), and crystalline silicon (mono-crystalline and polycrystalline) [25]. figure 5. pv grid connected system scheme in this paper, a grid connected pv system based on sicrystalline and cis technologies is simulated and the results are discussed and analyzed. the available solar radiation and ambient temperature of the location have major impact on the output power of the pv array. where the pv array output has a directly proportional relationship with the solar irradiation and inverse proportional relationship with the ambient temperature. equation (1) shows the array's instantaneous output power [26,27].       st g t p t p t t tpv ctpeak inv wire g st                  (1) where; the standard testing conditions of solar radiation and ambient temperature are displayed as gst and tst, aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 4 respectively. ppeak is the rated power of pv array, tc and tst are the temperature of the pv cell and the temperature of the pv solar cell under standard test conditions (25 °c), respectively [28]. tc represents the temperature of the pv cell, which can be calculate from equation (2). standard( ) ( ) 800 c ambient t t t t g t  (2) rp , 1 t t e v i t dc d dc dc r t      (3) where; tr is the recording time interval, trp is the reporting period, and n is the number of operating days of plant in a month. the monthly dc energy generated by the pv system is given by equation (4). , , 1 n e e dc m dc d d    (4) the total daily ac energy generated by the pv system (eac) which is fed into the utility grid is given by equation (5). rp , 1 t t e v i t ac d ac ac r t      (5) the monthly ac energy generated by the pv system is given by equation (6). , , 1 n e e ac m ac d d    (6) the inverter efficiency is given by equation (7). ac dc inv p p   (7) where; pac and pdc are respectively the power output delivered by the inverters and power output delivered by the photovoltaic modules [29]. iii.2. simulation procedure computer based simulation were more advanced and useful tools for hybrid renewable power systems analysis and the operation performance assessment under varying climates and capacities [30,31]. based on the literature review, the authors conducted studies for the performance analysis of photovoltaic systems for different sites worldwide by using various available simulation tools as well as through experimental analysis. several commercial software tools are available to study both grid-connected and off-grid renewable energy systems, as well as hybrid energy systems. as: homer, system advisor model (sam), pvsyst, retscreen, solar pro, pvwatt, and pvgis, this last one is used in this paper [32]. photovoltaic geographic information system (pvgis), a simulation tool from the european commission, is adopted in this paper for the assessment study of the proposed 1 mw photovoltaic grid connected power plant. pvgis, is one of the main and most used tools for solar irradiation estimation, pv energy production and economic parameters analysis. this software allows the calculation of monthly and annual electricity production for grid connected photovoltaic systems and isolated sites in africa, europe and now in america and asia. figure 6 shows the screen shot of the pvgis software. figure 6. pvgis software interface the pvgis simulation methodology adopted for the performance analysis of the proposed system is shown as in figure 7. figure 7. simulation methodology of 1mw grid connected pv system aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 5 iv. results and discussions the simulation results and performance analysis of the studied 1 mw grid connected pv system were presented taking into account the monthly and annual solar radiation, pv cell technologies, pv system capacity and optimized tilt and azimuth angle as input data of the system. iv.1. optimal tilts angles and orientations one of the main difficulties of electricity production by means of a pv power plant is its randomness, which is dependent on many other variables. indeed, many technical parameters such as the geographical location, weather conditions, inclination and orientation of pv modules, for a given system can provide very different results. the tilt angle is optimized and chosen in such a way that maximum potentials of solar energy can be harvested as shown in table 3. table 3. optimal orientation and inclination angles locations optimal inclination angle (°) optimal azimuth angle (°) algiers 30 -7 tamanrasset 24 -10 tlemcen 32 -12 chlef 32 -4 el oued 32 -5 iv.2. monthly solar irradiation on a fixed plan the monthly solar irradiance data in [kwh/m 2 ] relative to the optimal tilt angles for the four zones that include considered areas are analyzed. figure 8 clearly represents the monthly variation in solar irradiance for the selected locations. in zone i (algiers): the highest solar irradiation is possible in the march month and the lowest irradiation is seen in june. an average annual solar irradiation is about 2358 kwh/m 2 figure 8(a). in zone ii (chlef and tlemcen): the highest solar irradiation is possible for the months of july and august and the lowest solar irradiation is observed for the months of november and december, as shown in figure 8(b). the amount of solar irradiation is higher in tlemcen that in chlef with an average annual solar irradiation, i.e. 2157 kwh/m 2 and 2203 kwh/m 2 for the sites of chlef and tlemcen, respectively. in zone iii (el oued) and zone iv (tamanrasset): the highest irradiation is possible during the months of march, july and august and the lowest irradiation is observed during the months of november and december. as shown in figure 8(c), the amount of solar irradiation in tamanrasset is higher than in the el oued area. the average annual solar irradiation is about 2370 kwh/m 2 . (a) (b) (c) figure 8. monthly solar irradiation for each zone at optimal tilt angle, zone i (a), zone ii (b), zone iv (c) iv.3. monthly energy production the electrical energy generation is an important measure for the feasibility and performance analysis of the solar pv system. the electricity generation of the 1 mw photovoltaic power plant using cis and crystalline silicon technologies on a monthly basis is shown in figure 9 and figure 10, respectively. aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 6 it should be noted that there are variations in the amount of generated electricity during the year, which may be due to the effect of local weather conditions. from january to april and from september to december, tamanrasset have the highest energy production followed respectively by el oued, tlemcen, chlef and algiers, and this is for the tow pv cell technologies. the amount of ac energy produced in tamanrasset during november is the lowest when using cis technology (143000 kwh) and 144000 kwh when using si-crystalline. from may to august, the sites of algiers and chlef have the largest amount of energy that is injected into the grid, which is higher than the other areas, this is due to high temperatures in those regions. figure 9. pv electrical energy production for studied areas using cis technology. figure 10. pv electrical energy production for studied areas using sicrystalline at the first zone location (algiers), maximum energy outputs are seen in the month of jun, july and august i.e. 157000, 165000 and 162000 kwh respectively. when using cis modules, an average monthly energy output of 138166 kwh, 133500 kwh, 122016 kwh, 150083 kwh and 146916 kwh respectively for tlemcen, chlef, algiers, tamanrasset and el oued. an average monthly energy output of 139750 kwh, 135083 kwh, 125358 kwh, 150500 kwh and 149000 kwh respectively for tlemcen, chlef, algiers, tamanrasset and el oued when si-crystalline is used. the energy generation in the summer period is observed to be about twice the production in the winter period. the low energy production in winter is due to low solar radiation and short solar duration values. the temperature plays a major role in photovoltaic conversion, high temperatures lead to a decrease in the performance of pv modules and energy production (see the case of tamanrasset). iv.1. annual pv energy output finally, as a comparison between si-crystalline and cis technology, figure 11 shows the energy production fed into the grid on an annual basis for the regions studied. as a summary and from this figure, among the tow pv technologies, si-crystalline technology seem to be performed well for (tamanrasset, el oued, tlemcen and algeria) followed by cis pv cell, while cis is better than si-crystalline for the site of chlef. figure 11. annual pv energy output for selected areas using sicrystalline and cis technology v. discussion the results obtained in this study indicate that gridconnected photovoltaic system is technically feasible for power generation and could play an important role in the future energy mix of the country. the solar pv system can be used in many different applications such as in hybrid systems [33, 34], wastewater treatment plants [35], solar air conditioning [36], solar water heating system [37], solar concentrator application [38], and rural electrification [39]. as a future perspective, the study can be carried out using the various pv module technologies with appropriate installation methods (sun tracking system) for pv system performance improvement. aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 7 vi. conclusion in response to worsening environmental problems and the diminishing long-term viability of fossil fuels, renewable energies, including solar photovoltaic, are receiving a great deal of international attention. the simulation study of 1 mw pv system is presented in this paper, focusing on the assessment of the energy productions and its variations for five regions in algeria. the annual ac energy is predicted using two different photovoltaic modules (standard crystalline silicon and cis technology) based on optimal orientation and tilt angle is carried out using the new version of pvgis tool. based on this study, the following conclusions were drawn:  based on the monthly energy output, an average energy output of 139750 kwh, 135083 kwh, 125358 kwh, 150500 kwh and 149000 kwh respectively for tlemcen, chlef, algiers, tamanrasset, and el oued when si-crystalline is used.  the difference in the monthly average production between the two photovoltaic modules is 1584 kwh, 3000 kwh, 417 kwh and 2084 kwh respectively for tlemcen, algiers, tamanrasset and el oued, noted that si-crystalline modules recorded the highest performance. except in the region of chlef, when cis pv module is better than si-crystalline, the difference is 1583 kwh in terms of average monthly output.  from this study, it can be concluded that the feasibility studies are necessary before proceeding with the practical installation, the tilt angle and azimuth should be accounted as they are among the influencing factors as well as the effect of temperature. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] c. m. hong, c. h. chen, “intelligent control of a gridconnected wind-photovoltaic hybrid power systems”, international journal of electrical power & energy systems, vol. 55, pp. 554-561, 2014. https://doi.org/10.1016/j.ijepes.2013.10.024 [2] s. a. nowdeh, a. r. ghahnavieh, h. shojaei, “reliable designing of stand-alone pv/fc hybrid system”, majlesi journal of electrical engineering, vol. 7(2), pp. 41-47, 2013. [3] ministry of energy and mines (mem), “program for renewable energy and energy efficiency”, march 2011. [4] m. chikh, s. berkane, a. mahrane, “performance analysis of a grid connected micro-amorphous silicon pv pilot plant after eight months monitoring”, ieee, 2015. [5] ren21, “renewable 2017 global status report. paris”, http://www.ren21.net/status-of-renewables/global-statusreport/, accessed on 2022/01/10. [6] iea, “next generation wind and solar power: from cost to value”, international energy agency (iea), paris, 2016. [7] k. a. soteris, “solar energy engineering: processes and systems”, amsterdam, netherlands, elsevier, 2014. [8] a. el fathi, l. nkhaili, a. bennouna, a. outzourhit, “performance parameters of a standalone pv plant,” energy conversion and management, vol. 86, pp. 490500, 2014. https://doi.org/10.1016/j.enconman.2014.05.045 [9] r. rahul, s. c. kaushik, l. ravita, “a review on modeling, design methodology and size optimization of photovoltaic based water pumping, standalone and grid connected system,” renewable and sustainable energy reviews, vol. 57, pp. 1506-19, 2016. https://doi.org/10.1016/j.rser.2015.12.228 [10] m. castro, a. delgado, f. j. argul, a. colmenar, f. yeves, j. peire, “grid-connected pv buildings analysis of future scenarios with an example of southern spain”, solar energy, vol. 79, pp. 86-95, 2005. [11] statistas. https://fr.statista.com/, accessed on 2022/02/20. [12] b. a. stambouli, z. khiat, s.flaz, y. kitamura, “a review on the renewable energy development in algeria: current perspective, energy scenario and sustainability issues”, renewable and sustainable energy reviews, vol. 16, pp. 4445-4460, 2012. [13] world energy council, http://www.worldenergy.orgs. 2011. [14] cder algeria, http://www.cder.dzs, accessed on 2022/01/10. [15] s. a. boudghene, “algerian renewable energy assessment: the challenge of sustainability”, energy policy, vol. 39, pp. 4507-19, 2011. [16] s. h. muller, “renewable energies in the mena region: potential for sustainable energy provision and export to europe”, institute of technical thermodynamics german aerospace centre (dlr,2010), 2010. [17] pvgis, http://www.rensmart.com/weather/pvgissolars, accessed on 2022/01/11. [18] german aerospace centre (dlr), https://www.dlr.des, 2005. [19] cder, “renewable energy and energy efficiency program. portail des énergies renouvelables”, cder, https://www.cder.dzs, 2011. [20] a. hadj arab, b. ait driss, r. amimeur, e. lorenzo, “photovoltaic systems sizing for algeria, ” solar energy vol. 54(2), pp. 99-104, 1995. https://doi.org/10.1016/j.ijepes.2013.10.024 http://www.ren21.net/status-of-renewables/global-status-report/ http://www.ren21.net/status-of-renewables/global-status-report/ https://doi.org/10.1016/j.enconman.2014.05.045 https://doi.org/10.1016/j.rser.2015.12.228 http://www.worldenergy.orgs/ http://www.cder.dzs/ http://www.rensmart.com/weather/pvgissolars http://www.dlr.des/ http://www.cder.dzs/ aziz haffaf et al / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 01-08 page 8 [21] s. kebaïli, h. benalla, “optimal sizing of a stand-alone photovoltaic systems under various weather conditions in algeria”, revue des energies renouvelables, vol. 18(2), pp. 179-191, 2015. [22] s. semaoui, a. hadj arab, s. bacha, b. azoui, “the new strategy of energy management for a photovoltaic system without extra intended for remote-housing,” solar energy vol. 94, pp. 71-85, 2013. https://doi.org/10.1016/j.solener.2013.04.029 [23] a. mellit, s. a. kalogirou, s. shaari, a. hadj arab, “methodology for predicting sequences of mean monthly clearness index and daily solar radiation data in remote areas: application for sizing a standalone pv system”, renewable energy, vol. 33(7), pp. 1570-1590, 2008. [24] s. yilmaz, h. r. ozcalik, “performance analysis of a 500kwp grid-connected solar photovoltaic power plant in kahramanmaras”, turkish journal of electrical engineering & computer sciences, vol. 23, pp. 1946-1957 2015. [25] international energy agency (iea), “technology roadmap solar photovoltaic energy, https://www.iea.org, iea 2014. [26] lazard's, “levelized cost of energy analysis”, https://www.lazard.com/), accessed on 2022/02/18. [27] h. a. kazem, m. t. chaichan, “effect of humidity on pv performance based on experimental study”, international journal of applied engineering research, vol. 10(23), pp. 43572-43577, 2015. [28] r. m. patel, “wind and solar energy”, crc press llc, 1999. [29] a. raghoebarsing, a. kalpoe, “performance and economic analysis of a 27 kw grid-connected photovoltaic system in suriname”, iet renewable power generation, vol. 11(12), pp. 1545-1554, 2017. doi: 10.1049/ietrpg.2017.0204 [30] d. connolly, h. lund, b. v. mathiesen, m. leahy, “a review of computer tools for analyzing the integration of renewable energy into various energy systems”, applied energy, vol. 87(4), pp. 1059-1082, 2010. https://doi.org/10.1016/j.apenergy.2009.09.026 [31] s. sinha, s. s. chandel, “review of software tools for hybrid renewable energy systems”, renewable and sustainable energy reviews, vol. 32, pp. 192-205, 2014. [32] a. haffaf, f. lakdja, d. ould abdeslam, r. meziane, “monitoring, measured and simulated performance analysis of a 2.4 kwp grid-connected pv system installed on the mulhouse campus, france”, energy for sustainable development, vol. 62, pp. 44-55, 2021. https://doi.org/10.1016/j.esd.2021.03.006 [33] s. ebrahimi, m. jahangiri, h. a. raiesi, a. r. ariae, “optimal planning of on-grid hybrid microgrid for remote island using homer software, kish in iran”, international journal of energetica, vol. 3(2), pp. 13-21, 2018. http://dx.doi.org/10.47238/ijeca.v3i2.77 [34] a. haffaf, f. lakdja, r. meziane, d. ould abdeslam, “study of economic and sustainable energy supply for water irrigation system (wis) ”, sustainable energy, grids and networks, 100412. doi:10.1016/j.segan.2020.100412. [35] a. khechekhouche, f. bouchemal, z. kaddour, k. salim, a. miloudi, “performance of a wastewater treatment plant in south-eastern algeria”, international journal of energetica, vol. 5(2), pp. 47-51, 2020. http://dx.doi.org/10.47238/ijeca.v5i2.139 [36] a. haffaf, f. lakdja, d. ould abdeslam, r. meziane, “solar energy for air conditioning of an office building in a case study: techno-economic feasibility assessment”, renewable energy focus, vol. 39, pp. 148-162, 2021. https://doi.org/10.1016/j.ref.2021.09.002 [37] m. ghodbane, d. benmenine, a. khechekhouche, b. boumeddane, “brief on solar concentrators: differences and applications”, instrumentation mesure métrologie, vol. 19(5), pp. 371-378, 2020. https://doi.org/10.18280/i2m.190507 [38] d. benmenine, m. ghodbane, m. e. soudani, h. abdelouahed, a. massiv, n. elsharif, “a small parabolic trough collector as a solar water heater: an experimental study in ouargla region, algeria”, international journal of energetica, vol. 5(2), pp. 01-06, 2020. http://dx.doi.org/10.47238/ijeca.v5i2.141 [39] a. haffaf, f. lakdja, d. ould abdeslam, “electrification d'une charge isolée d'agriculture par hybridation énergétique”, rеvuе des energies renouvelables, vol. 22(1), pp. 1-17, 2019. https://doi.org/10.1016/j.solener.2013.04.029 http://www.iea.org/ https://www.lazard.com/ https://doi.org/10.1016/j.apenergy.2009.09.026 https://doi.org/10.1016/j.esd.2021.03.006 https://dx.doi.org/10.47238/ijeca.v3i2.77 https://dx.doi.org/10.47238/ijeca.v5i2.139 https://doi.org/10.1016/j.ref.2021.09.002 https://dx.doi.org/10.47238/ijeca.v5i2.141 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 15-23 ijeca-issn: 2543-3717. june 2017 page 15 fuzzy logic control of wind turbine storage system connected to the grid using multilevel inverter ali berboucha, kamel djermouni, kaci ghedamsi, djamal aouzellag laboratoire de maitrise des énergies renouvelables, faculté de technologie, university of bejaia. algeria b.ali06@hotmail.fr abstract – this paper aimed to evaluate the use of wind turbine storage systems to provide electricity in the electrical grid through a five-level inverter. the proposed system is composed of four wind turbine generators based on permanent magnet synchronous generator (pmsg), four battery storage systems connected to each capacitor of the dc link and a five level diode clamped inverter connected to the grid by three phase transformer. the control algorithm proposed is based on fuzzy logic to tracks and extract the maximum wind power by controlling the rotational speed of wind turbine, which is most appropriate when there is a lack of information on the characteristic cp (λ, β) of the turbine. the system operator controls the power production of the four wind turbine generators by sending out reference power signals to each input side regulation unit, the input side regulation units regulate the voltage of each capacitor of the dc link, regulate the voltage and the state of charge of each battery storage system. the inverter is controlled by simplified space vector modulation which allows us to reduce the computational time and reduce the algorithm complexity compared to the conventional five levels space vector modulation, the grid side control level regulate the power and the current injected to the grid. keywords: wind turbine generator, battery storage, five level diode clamped inverter, simplified space vector modulation, supervision and management, fuzzy logic controller. received: 15/02/2017 accepted: 16/03/2017 i. introduction the use of wind energy conversion systems has been considerably expanded over the last few decades, the installed wind turbines can be classified according to two categories: wind turbines with fixed speed and with variable speed, recently variable speed wind turbine generators are largely used, the authors in [1-2] gave some advantages of this kind of wind turbines compared to the fixed speed. one of the problems associated with variable-speed wind systems today is the presence of the gearbox coupling the wind turbine to the generator [2], permanent magnet synchronous generators (pmsg) turns out to be more and more attractive due to the low rotational speed and gearbox can be removed [3], this is important not only due to less space need, but also for reducing the downtime failure and because the gearbox usually requires significant maintenance [4], other advantages of pmsg are cited in [5]. many controllers to track the maximum power available in the wind have been developed in literatures [1–8], the authors in [4, 8] gave some advantages and disadvantages for each technique, in the case where the turbine parameters and the conditions climatic are unknown, the application of mppt based fuzzy logic is most suitable. energy storage systems (esss) have some important applications in operations like grid stabilization, stable power quality and reliability management, load shifting, grid operational support, smooth power injection to the grid. several power smoothing methods have been introduced in literature [9-16], battery energy storage system (bess) is selected as an energy storage medium and incorporated into wind farms for dispatching the wind power, it is usually necessary to maintain the power and energy balance as well as to improve the power quality [17]. recently multilevel inverters appear to be a very good solution for renewable energy applications, various types of topologies are presented in the literature [18, 19]. the diode clamped inverter topology appears to be more attractive for the reason cited in [19]. different methods of modulation techniques exist to control the inverter they are developed in [18-21]. in this paper as shown in fig.1 fuzzy logic mppt associated to variable speed wind turbine battery storage system connected to the grid with a five level diode clamped inverter is presented, each turbine is connected to each capacitor of the dc link of the inverter via an ac/dc converter and for each of this capacitor of the dc link a battery bank is also connected, the inverter is controlled by a simplified space vector modulation and its output is connected to the network via a perfect transformer. the proposed structure has many advantages over classic systems, in the case where the two levels converter is used to connect ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 16 production source to the grid, limits for power rise are imposed. the five level diode clamped inverter does not have this problem because it has a dc bus segmented by four series connected capacitors, so it offers many connection possibilities. in addition, harmonic distortion filter elements and cost of installation are reduced; moreover the proposed structure offers the advantage balancing the voltages across each capacitor without using complex algorithm. figure 1. global wind turbine connection system ii. modeling of wind energy conversion system ii.1. modelling of wind turbine the aerodynamics of the wind turbine can be characterized by its cp(λ,β) curve, which is usually provided by the manufacturers. cp is the power coefficient; it corresponds to maximum mechanical power extraction from wind at its maximum value and is a function of the tip-speed ratio λ and the pitch angle β. for a given cp, the mechanical power pm and mechanical torque tem extracted from the wind by the wind turbine can be given by [1]: pm = 0.5 ρ s cp(λ, β) v 3 w (1) m m em p t   (2) power coefficient is a function of the blade pitch angle, and the linear relation between the wind speed and the speed of the blade tip. this coefficient indicates the efficiency that the wind turbine transforms the kinetic energy contained in wind into mechanical energy. according to the betz limit, for horizontal axis turbines with three blades, the maximum possible value is approximately 0.593. in fig. 2 is presented some power coefficient curves for different pitch angles. the best result is with the angle in zero degrees. figure 2. cp-λ curves for different pitch angles ii.2. modelling of pmsg the generator chosen for the conversion of wind energy is the pmsg; the dynamic model of pmsg in d–q frame can be represented by the following equations:                                          sd sq s sq sd sq sd s sq sd dt d i i r v v      10 01 (3) where vsd, vsq, are the d, q axis stator voltages; isd,, isq, are the d, q axis stator currents; rs is the stator resistance; sd , and sq are the d, q axis stator flux linkages. the equations for these values in the absence of damper circuits can be expressed in terms of the stator currents and the magnetic flux as following [4]:                                   00 0 f sq sd qs ds sq sd i i l l   (4) s = p r (5) lds and lqs, are the d, q axis stator inductances; f is the magnetic flux; s is the generator electrical angular speed; r the mechanical angular speed and p is the pair number of poles. electromagnetic torque is given as: )( 2 3 sdsqsqsdem iipt   (6) ii.3. battery bank model a lead acid (la) batteries is the first and the oldest type of rechargeable battery in existence, they are invented in 1859 and they operate using a liquid electrolyte [22]; they are used in some areas because of their uncomplicated and fabrication costs are low, they are cheap ($300–600/kwh), highly reliable, improved maturity level in the technology, highly efficient (70– 90%) [22], extended service life of around 5 years or ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 17 250– 1000 charge/discharge cycles and a quick response especially in automobile systems and applications where weight is not seen as a parameter for the conditions of use. in renewable energy system applications multiple deep-cycle lead–acid (dcla) batteries, which provide a stable current for a large time period, are connected to form a battery bank. indeed, banks of up to 1mw of lead–acid batteries are already being used to stabilize wind farm power generation. for instance, dcla are designed for backup and peak shifting in off-grid and grid-tied pv systems [23]. lead acid batteries are used to ensure several hours to several days of energy storage. the model representation of the lead-acid battery is shown in fig. 3. the capacity of the battery is determined by integrating the main reaction current imr. figure 3. general structure of battery model to take into account losses gassing increased during the recharging of the battery at high voltage and temperature, in our case it is represented by the loss-current igas, represents a significant improvement compared to battery models for the simulation of hybrid energy systems. the main reaction current of the battery bank can be expressed as: imr (t) = ibb (t) – igas (t) (7) where imr is the main battery reaction current (a), ibb is external battery current (a), and igas is battery gassing current (a). the actual battery capacity can be determined as: cb (t)= 1 0 )( b t mr cdtti  (8) where cb is the actual battery capacity (ah) and cb1 is initial battery capacity (ah). the state-of-charge can be calculated by referring the actual capacity to the rated capacity of the battery: soc (t) = 1 )( b b c tc 100(%) (9) for all calculations shown, different model parameters represent the characteristic voltage behavior of lead-acid batteries when charging or discharging. the internal battery voltage is calculated as [24]: 1) charging (ibb< 0) : eb(t)=e0,c+ac . x(t) + efc c c txd txc ))(( )(  2) discharging (ibb > 0) : eb(t)=e0,d+ad . x(t) + efd d d txd txc ))(( )(  where eb is the internal battery voltage (v), and x is normalized maximum charge/discharge capacity (ah), it is given as: charging (ibb < 0) x(t)= )( ))((.max .max tc tiq q b mr c discharging (ibb > 0) x(t)= ))(( ))(( .max .max .max tcq tiq q bd mr d  the maximum capacity qmax in dependence of the main reaction current of the battery is expressed by a third order polynomial equation, where the parameters have to be determined by empirical curve fitting from measured data [24]: charging (ibb < 0) : qmax (imr (t))=c1[imr (t)] 3 + c2[imr (t)] 2 +c3imr (t)+c4 discharging (ibb > 0) : qmax (imr (t))=d1[imr (t)] 3 + d2[imr (t)] 2 +d3imr (t)+d4 therefore, the battery terminal voltage vb can be calculated as: charging (ibb < 0) : vb (t)= eb (t)r0c imr (t) discharging (ibb > 0) : vb (t)= eb (t)r0d imr (t) the voltage of a string of batteries is given by multiplying the battery voltage with the number of 12 v batteries in series: vbb (t) = vb(t) . bs where vbb is the voltage of battery bank (v), and bs is number of 12 v batteries in series. ii.4. multilevel inverter model first’s studies on multilevel inverters have been made with three-level inverter that has been presented by nabae [18]. last few years, multilevel inverters have gained lot of attention in the field of medium voltage and high power application due to their many advantages cited in [19], recent applications of this kind of inverters have a variety including induction machine and motor drives, active filters, interface of renewable energy sources, flexible ac transmission systems and static compensators[18, 19]. diode clamped inverters, especially three-level structure, have a wide use in motor drive applications compared with other multilevel inverter topologies; but when the number of level exceeds three, there is a limitation on number of clamping diodes and complexity to control the inverter. in this paper five level diode clamped inverter topology is used, as we can see in fig. 4 circuit diagram of this topology is presented. ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 18 the inverter has three legs; each leg is composed of eight switches with anti parallel diodes, capacitors split the dc-bus voltage. voltage across each capacitor is udc/4, and voltage stress across each switching device is limited to udc/4 through the clamping diodes. using the complementary control between upper switches and lower ones, so to have:            84 73 62 51 1 1 1 1 kk kk kk kk ss ss ss ss (10) where k= (1,2,3) is the leg number. assuming ideal power switches, connection functions are defined as follows:            )1.(.. ..).1( ... ... 87652 43211 87652 43211 kkkk b k kkkk b k kkkk a k kkkk a k ssssg ssssg ssssg ssssg (11) figure 4. circuit diagram of five level diode clamped inverter voltage of leg k (k = 1,2,3) of five-level inverter relative to middle point o is given by the following equation:  4/)]()(2[ 2121 dcbkbkakakko uggggv  (12) output voltage of the inverter is given by:                                   o o o v v v v v v 3 2 1 3 2 1 211 121 112 3 1 (13) as indicated in table 1, each leg of inverter can have five possible switching states, 1,2,3,4 and 5. table 1. diode clamped inverter voltage levels and switching states switching symbol switch state voltage vka sk1 sk1 sk1 sk1 sk1 sk1 sk1 sk1 1 1 1 1 1 0 0 0 0 udc/2 2 0 1 1 1 1 0 0 0 udc/4 3 0 0 1 1 1 1 0 0 0 4 0 0 0 1 1 1 1 0 -udc/4 5 0 0 0 0 1 1 1 1 -udc/2 iii. control of wind energy conversion system iii.1. mppt with fuzzy logic control the goal of the (mppt) strategy is to pick up the maximum power from the wind; given by: pm = 0.5 ρ s cp opt (λopt, β) v 3 w (14) the mppt controls the speed of the rotor by controlling the torque generator according to the optimal tip speed ratio λopt by imposing on the electromagnetic motor torque to be equal to its optimal reference value, [1]: tem = tem-ref (15) usually the wind turbine characteristic is unknown, an operational research based on fuzzy logic is proposed, rules of behavior to keep in order converging to the optimal point, are relatively easy to establish. these rules are based on the variation of the wind power (δp) and the rotation speed of the turbine (δω). the structure of a fuzzy control system is made up of the following blocs: – fuzzification, – knowledge base (rules), – inference engine, – defuzzification. fig. 5 shows the structure of a fuzzy logic controller. figure 5. general diagram of a fuzzy controller to each wind speed, the system has to find the maximal torque, what corresponds in search of the optimal rotation speed. from the existence of linguistic rules, the ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 19 controller by fuzzy logic (flc) works in the same way as the classic regulator. the block diagram for the power optimization by fuzzy logic is shown in fig.5. the mppt device based on the measurement of electrical power variation (δp) and rotation speed (δω) proposes a change (δω * ) of the rotational speed reference of the wind turbine (ω * ). the block diagram of the fuzzy logic mppt is shown in fig.6. figure 6. structure of controller mppt fuzzy the rotational speed of the wind turbine is regulated so as to follow the reference speed (ω * ) obtained at the output of fuzzy mppt controller; the output of the speed regulator determines the reference of the electromagnetic torque of the machine. the control rules are established. these ones link the output with the inputs. each of both linguistic inputs of the fuzzy mppt controller possesses seven fuzzy sets, which gives a set of forty-nine rules. these ones can be represented by the inference matrix (table 2). table 2. rules generated for the fuzzy mppt δω/δp nb nm ns z ps pm pb nb pb pn pm z nm nb nb nm pb pm ps z ns nm nb ns pm ps ps z ns ns nm z nb nm ns z ps pm pb ps nm ns ns z ps ps pm pm nb nm ns z ps pm pb pb nb nb ns z pm pb pb each of both linguistic inputs of the fuzzy pi controller possesses five fuzzy sets, which gives a set of twenty five rules. these ones can be represented by the inference matrix (table 3). table 3. rules generated for the fuzzy pi iii.2. control of battery bank storage system this control has two aims: control of battery bank system such illustrated in fig. 7 and regulation of the dc link capacitor using a corrector who provides the reference current to introduce in the dc link capacitor. the battery is connected to the dc-link via buck-boost chopper. the schematic of the battery converter control is shown in fig. 7. the power output of the four wind turbines is controlled by supervision system controls by sending reference power for each of the four control unit on the input side such as: windi gref refi p p p  8 (16) figure 7. battery bank storage control the battery power reference is produced by the supervisory system. the corrector adjusts the current ibat in the aim to track the reference ibat ref, with an objective of charging or discharging the battery depending to the need. fig. 8 shows flow chart of operation of storage battery system. figure 8. operation of storage battery iii.3. svpwm technique for five-level inverter one of the most known control approach for multilevel inverters is known as svpwm, which directly applying the control of the variable provided by the control system and identifies each commutation vector as a point in the complex area of (α, β). studies have shown that the use of svpwm gives us better results than sinusoidal pwm schemes concerning harmonic elimination and fundamental voltage ratios. in addition to δ en / en nb ns z ps pb nb nb ns ns ze ze ns nb ns ns ze ps z ns ns z ps ps ps ns z ps ps pb pb z z ps ps pb ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 20 this, the maximum peak value of the output voltage is 15% higher than triangular carrier-based modulation techniques [18]. five-level npc inverter has 125 switching states as shown in fig. 9. each phase arm of inverter consists of eight switching element and has five different switching states that are 1, 2, 3, 4, 5 representing positive big, positive small, zero, negative small and negative big switching sequences. figure 9. five-level space vector diagram in this paper, a new technique is proposed in which the five-level hexagon is subdivided into six smaller threelevel hexagons, and each three-level hexagons is subdivided into six smaller two-level hexagons as it can be seen in fig.10. the idea is to find in which two level hexagon is located the reference vector to apply the svpwm for the two-level inverter, and that starting with determining in which three level hexagon the reference vector is located, then subtracts the reference voltage vector from the central vector that connects the center of the five levels hexagon to the center of the hexagon with three levels. new three-level reference vector is created. repeat the same thing between three level hexagon and two level hexagon to get new two-level reference vector, and finally apply two level svpwm. first simplification: knowing the location of a reference voltage vector, a three level hexagon is selected among the six small hexagons which constitute the five levels space vector diagram. each hexagon is identified by the angle θ such as:                        6 11 2 3 6 2 3 6 7 5 6 7 6 5 4 6 5 2 3 26 2 66 11 1                   if if if if if if (17) figure 10. simplification five-level space vector diagram after having selected a hexagon, the new reference vector v *’ s is calculated as follows (table 4) table 4. first correction of reference voltage vector hexagon vα * ’ vβ * ’ 1 vα * 1/2 vβ * 2 vα * 1/4 vβ * 4/3 3 vα * + 1/4 vβ * 4/3 4 vα * + 1/2 vβ * 5 vα * 1/4 vβ * + 4/3 6 vα * + 1/4 vβ * + 4/3 second simplification: having the selected three levels hexagon and the location of the new vector, one hexagon is selected among the six small hexagons constituting this three level diagram. computing of the new reference vs *’’ is made. table.5 gives the components α and β of the reference voltage vs *’’ . table 5. second correction of reference voltage vector hexagon vα * ” vβ * ” 1 vα * ’ 1/4 vβ * ’ 2 vα * ’ 1/8 vβ * ’ 8/3 3 vα * ’ + 1/8 vβ * ’ 8/3 4 vα * ’+ 1/4 vβ * ’ 5 vα * ’1/8 vβ * ’ + 8/3 6 vα * ’+ 1/8 vβ * ’ + 8/3 when the new reference voltage vs *’’ and the corresponding hexagon are fixed; the traditional two level space vector modulation technique can be used. fig.11 show the output voltage of the first phase of the inverter and the spectral analysis it shows that the use of svpwm eliminates harmonic. ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 21 figure 11. output voltage va and spectral analysis for a five-level inverter controlled by svpwm iii.4. control of the grid side our system must (pmsg/battery bank) inject sinusoidal currents (amplitude and frequency) same to those of the network with the aim to generate the pmsg/battery bank active power to the grid. the active and reactive powers are given using components of grid voltage current (vgd igd vgq and igq) by:       gdgqgqgdg gqgqgdgdg ivivq ivivp (18) by controlling igd and igq, references for active and reactive power can be obtained (pgref and qgref):              gqgd gqgrefgdgref gdref gqgd gdgrefgqgref gqref vv vqvp i vv vqvp i ²² ²² (19) fig.12 shows us the diagram of the grid side control. figure 12. diagram of the grid side control iv. simulation results of global wind turbine system in this section, global wind turbine system is simulated using matlabsimulink, variable wind profile is taken for each turbine as shown in fig.13. fig.14 shows the rotor speeds they have the same allure whereas wind speed which proves a good tracking of our mppt. figure 13. wind speed profile for each turbine figure 14. mechanical speed for each turbine the generator power output is the sum of the four wind generators powers like shown in fig.15, negative values to say that power is supplied. ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 22 figure 15. mechanical power results simulations show the contribution of storage in grid connected systems. the strategy adopted allows controlling the level of storage of each storage unit when the wind productions are different and compensate the fluctuations of the wind power as illustrated in figs. 1617. figure 16. battery banks state of charge figure 17. battery banks power with battery storage units, we can balance the dc bus as shown in fig. 18. figure 18. dc bus voltages reactive power is kept at zero (unity power factor) after charging the capacitor fig.20, also, the results show that the connection of multiple wind turbines using a single multilevel inverter can inject more power to grid as shown in figs. 19 and 20. figure 19. grid active power figure 20. grid reactive power the injected currents are sinusoidal with a constant frequency (50 hz) and have a good quality figs. 21 and 22, the results demonstrate the effectiveness of the inverter control by the simplified space vector modulation. figure 21. grid current and voltage figure 22. zoom of grid current and voltage v. conclusion this paper proposed the study and the fuzzy logic control of variable speed wind battery storage grid connected system, a wind energy conversion system based on pmsg was proposed, the wind turbine system has been modeled in addition, in order to maximize the ali berboucha et al. ijeca-issn: 2543-3717. june 2017 page 23 exploited power from the wind fuzzy logic mppt control is applied which is most appropriate when there is a lack of information on the characteristic cp(λ,β) of the turbine, it is a simple and good control method with satisfactory dynamic performance. the pmsg was controlled by vector control; it gave good dynamic performances according to the wind speed variation. the use of a five level dci with it’s simplified space vector modulation as a grid interface gives a good results in term of thd and power quality, also, the aim was in this work to inject to the grid a fixed power with a variable wind speed, furthermore, the applied control strategies can benefit a high efficiency, especially by using the pmsg. the validity of the studied wind turbine system has been verified by simulation results using matlab simulink. references [1] samira chekkal, narimen aouzellag lahaçani, djamal aouzellag, kaci ghedamsi. fuzzy logic control strategy of wind generator based on the dual-stator induction generator. electrical power and energy systems, 59, 2014, pp. 166–175. [2] chih-ming hong, chiung-hsing chen, chia-sheng tu. “maximum power point tracking-based control algorithm for pmsg wind generation system without mechanical sensors”. energy conversion and management, 69, 2013, pp. 58–67. [3] abdeldjalil dahbi, mabrouk hachemi, nasreddine naitsaid, mohamed-said nait-said. realization and control of a wind turbine connected to the grid by using pmsg. energy conversion and management, 84, 2014, pp. 346– 353. [4] ali m. eltamaly, hassan m. farh. “maximum power extraction from wind energy system based on fuzzy logic control” electric power systems research, 97, 2013, pp. 144– 150. [5] m. seixas, r. melício, v.m.f. mendes. “fifth harmonic and sag impact on pmsg wind turbines with a balancing new strategy for capacitor voltages”. energy conversion and management, 79, 2014, pp. 721–730. [6] gonzalez lg, figueres e, garcera g, carranza o. maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion systems. appl energy, 87, 2010, pp. 2304–2312. [7] tomonobu s, yasutaka o, yasuaki k, motoki t, atsushi y, endusa bm, et al. sensorless maximum power point tracking control for wind generation system with squirrel cage induction generator. renew energy, 34, 2009, pp. 994–999. [8] m.a. abdullaha, a.h.m. yatima, c.w. tana, r. saidurb. a review of maximum power point tracking algorithms for wind energy systems. renewable and sustainable energy reviews, 16, 2012, pp. 3220–3227. [9] mohammed yekini suberu, mohd wazir mustafa, nouruddeen bashir. energy storage systems for renewable energy power sector integration and mitigation of intermittency. renewable and sustainable energy reviews, 35, 2014, pp. 499–514. [10] evans a, strezov v, evans tj. assessment of utility energy storage options for increased renewable energy penetration. renew sustain energy rev, 16, 2012, pp. 4141–4147. [11] am howlader, n urasaki, a yona, t senjyu, ay saber. a review of output power smoothing methods for wind energy conversion systems. renew sustain energy rev, 26, 2013, pp. 135–146. [12] m. maamir, a. betka, h. aboub. modeling and simulation of energy management hybrid sources system composed of solar-pv and battery. international journal of energetica (ijeca), 1, 2016, pp. 12–19. [13] rahim ahma, nowicki ep. supercapacitor energy storage system for fault ride through of a dfig wind generation system. energy convers manage, 59, 2012, pp. 96–102. [14] h xuesong, s caixin, l ren, l yong. an active power smoothing strategy for direct-driven permanent magnet synchronous generator based wind turbine using flywheel energy storage. automat electr pow syst. 2010 [15] t. kinjo, t. senjyu, n. urasaki, h. fujita. terminalvoltage and output-power regulation of wind-turbine generator by series and parallel compensation using smes. iet proc-gener trans distrib, 153, 2006, pp. 276–282. [16] fd. gonzalez, a. sumper, og. bellmunt, rv. robles. a review of energy storage technologies for wind power applications”. renew sustain energy rev, 16, 2012, pp. 2154–2171. [17] m. khalid, a.v. savkin. minimization and control of battery energy storage for wind power smoothing: aggregated, distributed and semi-distributed storage. renewable energy, 64, 2014, pp. 105-112. [18] i. colak, , e. kabalci, , r. bayindir. review of multilevel voltage source inverter topologies and control schemes. energy conversion and management, 52, 2011, pp. 1114– 1128. [19] ravi, a., manoharan, p.s, & vijay anand, j. modeling and simulation of three phase multilevel inverter for gird connected photovoltaic systems. solar energy, 85, 2011, pp. 2811–2818. [20] al-othman, ak., & abdelhamid, th. elimination of harmonics in multilevel inverters with non-equal dc sources using pso. j energy convers manage, 50, 2009, pp. 756–765. [21] rahim, n., selvaraj, j., & krismadinata, c. five-level inverter with dual reference modulation technique for grid-connected pv system .renewable energy, 35 (2010), pp. 712–720. [22] andreas poullikkas. a comparative overview of largescale battery systems for electricity storage. renewable and sustainable energy reviews, 27, 2013, pp. 778–788. [23] bayar t. batteries for energy storage: new developments promise grid flexibility and stability. renewable energy world magazine 2011 [24] wichert benjamin. control of photovoltaic diesel hybrid energy systems. ph.d. thesis of the curtin university of technology, 2000. i. introduction ii. modeling of wind energy conversion system ii.4. multilevel inverter model iii. control of wind energy conversion system iii.1. mppt with fuzzy logic control iii.2. control of battery bank storage system iii.3. svpwm technique for five-level inverter iii.4. control of the grid side iv. simulation results of global wind turbine system v. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 25-33 effect of rain on the aerodynamic performance of a horizontal axis wind turbine – a computational study eleni douvi * , dimitra douvi, dimitrios pylarinos, dionissios margaris department of mechanical engineering and aeronautics, university of patras, greece email*: douvi.eleni@gmail.com abs tract –this paper analyzes numerically the impact of rainfall on the aerodynamic performance of a three-bladed horizontal axis wind turbine, with blades constructed by naca 4418 airfoil. the simulations were conducted by the help of the commercial computational fluid dynamics code, ansys fluent 19.2. firstly, the optimum geometry of the blade was designed with an application based on blade element momentum theory. the moving reference frame model was applicated to simulate the rotation of the blades and the k -ω shear-stress transport turbulence model was added as well. the simulation of rain was a ccomplished by the discrete phase model and the taylor analogy break up model was enabled to simulate droplets break up. three different rainfall conditions were studied, corresponding to liquid water contents of 10g/m³, 30g/m³ and 60g/m³. the influence of droplet diameter on the aerodynamic performance of the blade was also examined. the results showed that the aerodynamic performance of the wind turbine is degraded in rain conditions, and the degradation is greater for higher values of liquid water content and for larger diameter of water droplets. keywords: aerodynamic performance, discrete phase model, horizontal axis wind turbine, rainfall. received: 06/06/2021 – accepted: 26/06/2021 i. introduction energy demand and consumption in modern societies is increasing recently by 2.3%, approximately twice the average rate of increase since 2010 [1]. electricity is mainly generated by fossil fuels burning, which is responsible for greenhouse gasses emissions. renewable energy sources (res) are vital against climate change. by 2050, the greenhouse gas emissions in eu should be at least 80 lower than 1990 levels. in order to achieve this goal, renewable energy technologies for power generation, such as wind turbines, have to be implemented [2]. there are many types of wind turbines, but the horizontal axis wind turbines (hawts) have prevailed, as they demonstrate higher power coefficients. according to 2019 statistics from the world wind energy association (wwea), the installed capacity of wind turbines worldwide exceeded 650 gw [3]. wind turbines operate in open environment, thus they are exposed in hazard weather conditions, i.e. extreme winds, ice accumulation and rain, which not only cause damages to the machine [4], but they affect their aerodynamic performance as well [5]. recent developments in computing power have led to the efficiency improvement of wind energy industry, since simulations replaced the costly experiments. the majority of these studies deal with the selection of appropriate locations for wind turbine installation in complex terrain. the recent trends on numerical methods applied in wind energy industry were reviewed [6] and it was concluded that greater accuracy is accomplished when coupling different methods. a numerical model, called riam-compact, was developed in order to estimate the real airflow over complex terrain [7]. the numerical results were validated by comparing them with flow measurements from noma wind park, so it can be concluded that riam-compact can accurately predict the airflow over complex terrain. the wasp model and computational fluid dynamics methods were utilized in order to predict the airflow over a cliff on the north of island of madeira, where there is an interest of wind park installation, and finally select the most appropriate location for wind turbines [8]. a particle tracking model for wind turbine wake flow estimation was also proposed [9]. the advantages of the model are that it is more accurate for complex terrain than the former linear model and it can also generate optimum wind turbines layout. moreover, the proper computational procedure in order ijeca-issn: 2543-3717. june 2021 page 25 http://www.ijeca.info/ http://www.ijeca.info/ mailto:douvi.eleni@gmail.com eleni douvi et al ijeca-issn: 2543-3717. page 26 to simulate the flow over complex terrain, by the help of a three-dimensional reynolds -averaged navier–stokes solver with k–ω turbulence model was recommended [10]. the effect of blade geometry on the performance of wind turbines was investigated computationally as well. a user-friendly software for large scale wind turbines blade optimization was developed [11]. in particular, the shape of the blades is optimized, and the aerodynamic performance is analyzed. the results showed that after optimization, the thrust coefficient reduced by 7.5% and the overall efficiency enhanced by 1%. the aeroelastic behavior of wind turbine blade sections, taking into account the airfoil radial position and the rotational speed of the blade was simulated as well [12]. the aeroelastic stability of wind turbine blades is crucial, since is more likely for cracks to be created on them. furthermore, the optimum angle of attack for untwisted wind turbine blades, in order to maximize power output was examined computationally [13]. it was concluded that the optimum angles of attack are those angles that exhibit the highest lift coefficients. the optimum wind turbine blade geometry, i.e. chord length and twist angle, was also investigated [14]. two different airfoils were examined, naca 4410 and naca 2415, and it was concluded that the power output is maximized for angles of attack with highest lift coefficient, as well. blades are constructed from various airfoils and the wind turbine performance depends on the airfoil aerodynamic behavior. the presence of dust or rainfall results on aerodynamic degradation of the airfoils. the impact of the presence of sand particles over wind turbine airfoils, namely naca 0012 [15] and s809 airfoil [16] was analyzed numerically. they concluded that the aerodynamic performance of the airfoils is degraded due to sand particles presence, and the degradation is higher for higher concentrations of sand particles and higher angles of attack. the aerodynamic performance of naca 63415 airfoil under sand presence, at re=460×10 3 was also studied numerically and it was found out that the lift coefficient could be reduced up to 28% at sandy conditions [17]. the interest of the researchers, concerning the effects of rainfall on aerodynamic sector, was focused on the investigated on the aerodynamic performance of airplanes under these conditions [18, 19]. the rainfall over the naca 0012 airfoil at rain rate of 1000mm/h, which corresponds to liquid water content (lwc) of 30g/m 3 and at re=1×10 6 and re=3×10 6 was simulated [20]. a year later, the aerodynamic performance of the same airfoil at re=1×10 5 and at lwcs of 20.548g/m 3 , 37.745g/m 3 , 41.096g/m 3 and 75.491g/m 3 was studied numerically and experimentally [21, 22]. it was found out that the aerodynamic performance degrades in rainfall due to the formation of water film on the surface of the airfoil and the cratering effects from the impact of raindrops. the degradation is higher as the angle of attack or the lwc increases. the degradation due to rain leads to less power generation of the wind turb ines, as it was found experimentally [23]. specifically, it was found that the performance of the nasa mod -0 hawt was degraded by 20% for light rain and by 30% for heavy rain. the aerodynamic performance of a three-bladed hawt with blades constructed by na ca 4418 airfoil under rainfall is examined in this paper. the blade geometry is the optimum, derived by the blade element momentum (bem) theory [24] and its behavior was simulated by the help of the commercial computational fluid dynamics (cfd) code, ansys fluent 19.2 [25]. firstly, the operation of the blade under air flow was analyzed and then, different rainfall conditions were examined, in order to show the impact of rain droplets on the aerodynamic performance of the wind turbine. it was concluded that rain affects the aerodynamic performance of the wind turbine. in particular, the power coefficient of the wind turbine is decreased as the liquid water content and the droplet diameter increase. ii. computational analysis ii. 1 . horizontal axis wind turbine blade geometry prior to the computational simulation, the blade of the three-bladed horizontal axis wind turbine had to be designed. the optimum geometry of the blade was calculated by ttbem, an application based on the blade element momentum (bem) theory originally developed for tidal turbines, but it can be applicated for hawts as well [26]. the blade was constructed by naca 4418 airfoil which is characterized by high lift to drag ratio, in order to achieve high aerodynamic performance. the length of the blade is 40m and the selected tip speed ratio (tsr) is equal to 6, a typical value for three-bladed hawts. the data provided from ttbem were then inserted in qblade open source software [27], to create the three-dimensional geometry file of the blade as shown in figure 1. figure 1. t he blade geometry eleni douvi et al ijeca-issn: 2543-3717. page 27 ii. 2 . computational simulation the simulations for both one phase flow and two phase flow cases were conducted by the commercial cfd code ansys fluent 19.2. the next step in the process is to create the computational domain around one blade, a one third of a truncated cone, placed horizontally. periodic boundary conditions, with a periodicity of 120 degrees, are applied in order to include in the simulation procedure the remaining two blades of the rotor. the hub and the tower of the hawt are not taking into account, since their effect on the aerodynamic behavior of the rotor is insignificant. the front side of the truncated cone is placed 90m upstream the blade, has a diameter of 120m and is defined as velocity inlet. the lateral side is located 180 downstream the blade, its diameter is 240m and is defined as pressure outlet. the computational domain and the boundary conditions are presented in figure 2. a grid independence study was conducted, and it was found that the most appropriate mesh for the simulation consists of about one million (1.000.000) cells. the mesh is hybrid, and in particular, it is structured on the blade, a proper inflation was added over the blade, and unstructured in the remaining do main. close to the blade, were greater accuracy is necessary, the mesh is denser as shown in figure 3. figure 2. t he comput ational domain and the boundary conditions figure 3. t he computational mesh close t o the wind t urbine blade all the simulations were conducted for an air velocity equal to 15m/s, which is a usual air velocity for wind turbines operation. the rotation of the blades was simulated by the help of moving reference frame model (mrf) [28] and the most appropriate turbulence model for such simulations is the k-ω shear-stress transport (sst) [29], which can accurately predict the separation of the boundary layer under adverse pressure gradient. the ratio of average velocity fluctuations to average velocity is expressed by turbulent intensity, which is set by default equal to 5%. the turbulent viscosity ratio, in other words the proportion of turbulence viscosity to dynamic flow viscosity, is also set to its default value of 10%. in order to simulate rain, the discrete phase model was enabled. the water droplets are injected from a rectangular surface, at 15m upstream the blade, in order to reduce computational memory and computational time. the horizontal velocity of the water droplets is equal to the air flow velocity and the vertical velocity is calculated by the empirical equation of markowitz, taking into account the droplet diameter [30]. the taylor analogy breakup (tab) model is also enabled for the simulation of droplets breakup as they impact the blade [31]. five different conditions for two-phase flows over the hawt rotor were examined, for various lwcs and various droplet diameters, as they are presented in figure 4. the velocity and pressure values are updated simultaneously through the option "coupled" at pressure velocity coupling. the "least square sell based" model is selected for the discretization of the gradient coefficients and the "standard" model is selected for the pressure discretization. the "second order upwind" model is used for the discretization of momentum values, while the "first order upwind" is used for the discretization of turbulent kinetic energy and specific dissipation rate. the "pseudo transient" and "high order term relaxation" mechanisms are used to control the convergence of variables. figure 4. t he examined condit ions for t he two-phase flow eleni douvi et al ijeca-issn: 2543-3717. page 28 iii. computational results iii.1. one-phase flow of air prior to the study of the rainfall, the air flow around the wind turbine blade should be examined, in order to estimate the effect of rain by the comparison of the results of the two different conditions. the velocity of the air for the simulations was equal to15m/s and for the tip (a) speed ratio a typical value of 6 was selected. the present model cannot be validated directly, since corresponding experimental data do not exist. due to this lack of experimental data for a wind turbine rotor of similar size, the specific aerodynamic performance was compared with the performance of a commercial rotor of a similar size, to appraise the estimated results. the power coefficients of three commercial wind turbines (b) were compared with the power coefficient of the blade of the present study and the results are presented in table 1. specifically, the wind turbines studied are the general electric three-bladed wind turbines ge 1.85 – 87 [32] and ge 2.5 – 88 [33]. t able 1. p ower coefficient of commercial wind t urbines and comparison wit h t he numerical result s of the t hree-bladed wind t urbine wit h blade const ruct ed by naca 4418 airfoil w i n d tu rbi n e mode l s wept are a (m²) rated wi n d speed (m/s) rated power (mw ) powe r c oefficient c p de vi ation of powe r c oe fficient (%) ge 1.85 – 87 5346 13 1.85 0,257 10,95 ge 2.5 – 88 6082 14 2.50 0,244 6,36 it is apparent that the deviation of the calculated power coefficient is comparatively low, which means that the computational method is reliable. the factor that can affect the difference in performance from commercial models is the different geometry, as blades consisting of only one type of airfoil, as considered in present work, are rarely used in the market. in figure 5 the static pressure distribution on the pressure and the suction side of the blade, for air flow, is presented. the magnitude of static pressure receives its highest absolute value on the suction side of the blade, in about 30% of its length, close to the tip. moreover, static pressure values are also high in the pressure side of the blade, close to the leading edge of the airfoil, but these values are lower than the negative values on the suction side. the pressure difference between the two sides of the blades is responsible for lift generation, which is responsible for the rotation of the blade. figure 5. st at ic pressure dist ribut ion on (a) t he pressure and (b) the suct ion side of t he naca 4418 blade for air flow figure 6 shows the relative velocity vectors at various sections along the blade, from close to the hub up to close to the tip. the velocity values are lower at the stagnation point and they are even lower for the sections close to the hub. the velocity reaches its highest values on the upper side of the airfoil, and in particular at the region between the leading edge and the middle of the airfoil, for all sections. the region with the highest values of velocity follows the region where the flow is separated, because of the gradual reduction of the air velocity due to friction. the separated flow expands at greater regions as the airfoil sections are closer to the blade tip. in figure 7 the static pressure distribution around the airfoil at various sections along the blade are presented. it is obvious that the static pressure difference between the suction and pressure surface of the blade increases along the blade, as we are moving from the hub towards the blade tip. (a) eleni douvi et al ijeca-issn: 2543-3717. page 29 figure 6. relat ive velocity vectors around various blade sect ions at a dist ance (a) r/r=0.25, (b) r/r=0.50, (c) r/r=0.75 and (d) r/r=0.99 from t he rot or hub however, the maximum pressure difference along the blade occurs at r/r=0.75. moreover, the static pressure distribution shows that the lowest pressure values appear in the regions where the velocity takes its highest values. generally, it is observed that the pressure is reduced in the regions where the velocity is increased and vice versa, which is confirmed by bernoulli's equation. (c) (d) figure 7. st at ic pressure dist ribut ion around various blade sect ions at a dist ance (a) r/r=0.25, (b) r/r=0.50, (c) r/r=0.75 and (d) r/r=0.99 from t he rot or hub iii.2. two-phase flow of air and water droplets in order to show the effect of rainfall on the aerodynamic performance of the hawt rotor, three different liquid water contents (lwcs) were examined, (b) (a) (c) (b) (d) eleni douvi et al ijeca-issn: 2543-3717. page 30 and in particular 10g/m 3 , 30g/m 3 , and 60g/m 3 , which represent light, medium and heavy rainfall, respectively. (a) (b) figure 8. st at ic pressure dist ribut ion on (a) t he pressure and (b) the suct ion side of t he naca 4418 blade for lwc=10g/m 3 (a) (b) figure 9. st at ic pressure dist ribut ion on (a) t he pressure and (b) the suct ion side of t he naca 4418 blade for lwc=30g/m 3 from figure 8 to figure 10 the static pressure distribution on the suction and the pressure side of the blade under light, medium and heavy rainfall, is presented. the pressure distribution is the same as for the one-phase flow, i.e. the highest absolute value of the static pressure is located on the suction side of the blade. furthermore, the minimum values of the static pressure are increased as the lwc increases. more specifically, the minimum static pressure is increased compared to the corresponding one-phase flow by 4.7%, 5.5% and 8% for lwcs of 10g/m 3 , 30g/m 3 , and 60g/m 3 , respectively. (a) (b) figure 10. st at ic pressure dist ribution on (a) the pressure and (b) the suct ion side of t he naca 4418 blade for lwc=60g/m 3 in figure 11 and figure 12 the water film height on the pressure and the suction side of the blade, for the three different lwcs that were examined, is illustrated. (a) (b) (c) figure 11. wat er film height on the pressure side of t he blade for lwc of (a) 10g/m 3 , (b) 30g/m 3 and (c) 60g/m 3 it can be observed that the maximum water film thickness is located close to the hub, where the chord length of the blade is greater, whereas less quantity of water is concentrated close to the blade tip. this could be explained by the fact that centrifugal force tends to remove the water from the blade. moreover, from these eleni douvi et al ijeca-issn: 2543-3717. page 31 figures it is clear that the water film occupies more space on the blade for higher lwc values. (a) (b) (c) figure 12. wat er film height on the suct ion side of t he blade for lwc of (a) 10g/m 3 , (b) 30g/m 3 and (c) 60g/m 3 table 2 shows the calculated power coefficient and of the examined hawt and the degradation of power coefficient due to rain, for all the lwcs that were simulated, and for water droplet diameter equal to 1mm. moreover, the mass flow rate of the water that impacts the blade is provided in table 2. figure 13 shows the power coefficient of the wind turbine versus the lwc and there is a clear trend of almost linearly decreasing of power coefficient as the lwc increases. t able 2. calculat ed power coefficient and its degradat ion due t o rain condit ions, and wat er mass flow rat e on t he blade lw c (g/m 3 ) w ater mass fl ow rate on the bl ade (kg/s) powe r c oe fficient c p de gradati on of powe r coefficient (%) 0 0.0 0.223 -- 10 4.5 0.199 10.8 30 14.0 0.190 14.8 60 20.0 0.174 22.0 figure 13. p ower coefficient of the wind t urbine at different lwcs these results are in line with the theoretical estimation that rainfall has adverse effects on the performance of a wind turbine. as the density of the rainfall increases, the water film on the blade is thicker and the cratering effects from the raindrops impact are more intense, leading in higher aerodynamic drag. the impact of droplet diameter on the aerodynamic degradation of a hawt was examined as well. three different droplet diameters, of 0.5mm, 1mm and 3mm were simulated, for lwc=30g/m³ and air velocity equal to 15m/s. figure 14 and figure 15 present the water film height on the pressure and the suction side of the blade, for the three different droplet diameters that were examined, for constant lwc and equal to 30g/m³. from these figures it is apparent that there is an increase in water concentration on the blade surface with an increase in droplet diameter and the highest water film appears to develop in the area close to the hub, for all three cases. this phenomenon could be explained by the fact that droplets of larger diameter are most probably unaffected by local aerodynamic forces and they follow a more direct path due to their greater mass and inertia. in contrast, droplets with smaller diameters are more vulnerable to these forces and may never reach the body. (a) (b) eleni douvi et al ijeca-issn: 2543-3717. page 32 (c) figure 14. wat er film height on the pressure side of t he blade for lwc of 30g/m 3 and droplet diameter of (a) 0.5mm, (b) 1mm and (c) 2mm table 3 and figure 16 show the results of power coefficient for lwc=30g/m³ and different droplet diameters. it is obvious that the performance of the wind turbine is negatively affected by the diameter of the rain droplets. however, it is observed that this reduction is smaller than the corresponding one due to the increase of lwc in the flow. figure 15. wat er film height on the suct ion side of t he blade for lwc of 30g/m 3 and droplet diameter of (a) 0.5mm, (b) 1mm and (c) 2mm t able 3. calculat ed power coefficient and it s degradation for lwc of 30g/m³ and different droplet diamet ers figure 16. p ower coefficient of the wind t urbine for lwc=30g/m³ and different droplet diameters iv. conclusion the purpose of the current study was to determine the effects of rainfall on the aerodynamic performance of a hawt with blades constructed by naca 4418 airfoil. initially, the one-phase flow of air was studied and then the two-phase flow of air and water droplets, in order to compare the results and understand the impact of rain on the hawt performance. from the contours of static pressure it was found that the highest absolute value of static pressure appears on the suction side of the blade, close to the tip, for all the cases studied, both for air flow and rainfall conditions. moreover, the static pressure difference between the pressure and the suction surface of the blade increases along the blade, towards the blade tip. in rainfall conditions, the lowest negative values of static pressure were increased with the lwc of 10g/m 3 , 30g/m 3 , and 60g/m 3 , by 4.7%, 5.5% and 8%, respectively. it can be observed that the maximum water film thickness is located close to the hub, where the chord length of the blade is greater, whereas less quantity of water is concentrated clos e to the blade tip, because the centrifugal force tends to remove the water from the blade. moreover, it is clear that the water film occupies more space on the blade for higher values of lwc. furthermore, a significant degradation of the aerodynamic efficiency of the compared to the one-phase flow was observed, equal to 11.84%, 16.87% and 23.9% for rain densities of 10g/m 3 , 30g/m 3 , and 60g/m 3 respectively. finally, the increase in the diameter of the raindrops leads to more concentration of liquid mass on the blade and at the same time a degradation of its aerodynamic performance since. for diameters of 0.5mm, 1mm and 2mm in a two-phase flow with lwc=30g/m 3 , the reduction of the power coefficient was 15.33%, 16.87% and 17.99% respectively. dropl e t di ameter (mm) powe r c oe fficient cp de gradation of power c oe ffi ci e n t (%) 0 0.223 -- 0.5 0.196 12.3 1.0 0.190 14.8 2.0 0.187 16.0 (a) (b) (c) eleni douvi et al ijeca-issn: 2543-3717. page 33 references [1] international energy agency , "global energy & co2 status rep ort 2019", iea, paris, 2019. [2] europ ean council, "energy roadmap 2050", brussels, 2011. [3] world wind energy association (wwea), "wind energy international", [online]. available: http s://library .wwindea.org/global-statistics/. [accessed m arch 2021]. [4] y. du, s. zhou, x. jing and y. peng, "damage detection techniques for wind turbine blades: a review", m echanical sy stems and signal processing, vol. 141, 2020. [5] l. m ishnaevsky , k. branner, h. petersen, j. beauson, m . m cgugan and b. sørensen, "m aterials for wind turbine blades: an overview", m aterials, vol. 10, issue 11, 2017. [6] a. m iller, b. chang, r. issa and g. chen, "review of comp uter-aided numerical simulation in wind energy ", renewable and sustainable energy reviews, vol. 25, 2013, p p . 122-134. [7] t. uchida and y. ohy a, "m icro-siting technique for wind turbine generators by using large-eddy simulation", journal of wind engineering and industrial aerody namics, vol. 96, issue 10-11, 2008, p p . 2121-2138. [8] j. palma, f. castro, l. ribeiro and a. ro, "linear and nonlinear models in wind resource assessment and wind turbine micro-siting in comp lex terrain", journal of wind engineering and industrial aerody namics, vol. 96, issue 12, 2008, p p . 2308-2326. [9] m . song, k. chen, z. he and x. zhang, "wake flow model of wind turbine using p article simulation", renewable energy , vol. 41, 2012, p p . 185-190. [10] j. prosp athop oulos, e. politis and p. chaviarop oulos, "ap p lication of a 3d rans solver on the comp lex hill of bolund and assessment of the wind flow p redictions", journal of wind engineering and industrial aerody namics, vol. 107–108, 2012, p p . 149-159. [11] b. kim, w. kim, s. lee, s. bae and y. lee, "develop ement and verification of a p erformance based op timal design software for wind turbine blades", renewable energy , vol. 54, 2013, p p . 166-172. [12] c. baxevanou, p. chaviarop oulos, s. voutsinas and n. vlachos, "evaluation study of a navier–stokes cfd aeroelastic model of wind turbine airfoils in classical flutter", journal of wind engineering and industrial aerody namics, vol. 96, issue 8–9, 2008, p p . 1425-1443. c. thumthae and t. chitsomboon, "op timal angle of attack for untwisted blade wind turbine", renewable energy , vol. 34, issue 5, 2009, p p . 1279-1284. [13] s. rajakumar and d. ravindran, "iterative ap p roach for op timising coefficient of p ower, coefficient of lift and drag of wind turbine rotor", renewable energy , vol. 38, issue 1, 2012, p p . 83-93. [14] d. douvi and d. μ argaris, "numerical simulation of naca 0012 airfoil in air p hase flow and in high concentration air–sand p articles two-p hase flow", in 8th international conference from “scientific comp uting to comp utational engineering", athens (greece), july 4-7 2018. [15] d. douvi, d. μ argaris and a. davaris, "aerody namic performance of a nrel s809 airfoil in an air–sand particles two phase flow", in 7th international conference "scientific comp uting to comp utational engineering", athens (greece), july 6-9 2016. [16] i. zidane, k. saqr, g. swadener, x. m a and m . shehadeh, "comp utational fluid dy namics study of dusty air flow over naca 63415 airfoil for wind turbine ap p lications", jurnal teknologi, vol. 79, issue 7-3, 2017, p p . 1-6. [17] r. rhode, "some effects on rainfall on flight of airp lanes and on instrument indications", naca tn 803, 1941. [18] a. bilanin, "scaling laws for testing of high lift airfoils under heavy rainfall", in aiaa 23rd aerosp ace science m eeting, reno, nv, u.s.a, january 1985. [19] e. douvi and d. m argaris, "aerody namic performance investigation under the influence of heavy rain of a naca 0012 airfoil for wind turbine ap p lications", international review of m echanical engineering (i.re.m .e.), vol. 6, issue 6, 2012, p p . 1228-1235. [20] e. douvi, d. m argaris, s. lazarop oulos and s. svanas, "exp erimental and comp utational study of the effects of different liquid water content on the aerody namic performance of a naca 0012 airfoil at low rey nolds number", in 5th international conference "on exp eriments/ process/ sy stem m odeling/ simulation/ op timization", athens (greece), 2013. [21] e. douvi, d. m argaris, s. lazarop oulos and s. svanas, "low rey nolds number investigation of the flow over a naca 0012 airfoil at different rainfall rates", international review of m echanical engineering (i.re.m .e.), vol. 7, issue 4, 2013, p p . 625-632. [22] r. corrigan and r. dem iglio, "effect of precip itation on wind turbine performance", nasa-tm -86986, 1985. [23] h. glauert, "the theory of the autogy ro", the journal of the roy al aeronautical society , vol. 31, issue 198, 1927, p p . 483-508. [24] ansys®, academic research, release 19.2. [25] e. douvi and d. m argaris, "hy drody namic analy sis of a horizontal axis tidal turbine, based on the blade element m omentum theory ", in proceedings of the 7th international conference on "exp eriments/ process/ sy stem m odeling/ simulation/ op timization", athens (greece), july 5-8 2017. [26] d. m arten, j. wendler, g. pechlivanoglou, c. nay eri and c. paschereit, "qblade: an op en source tool for design and simulation of horizontal and vertical axis wind turbines", international journal of emerging technology and advanced engineering, vol. 3, 2013, p p . 264–269. [27] j. y. luo, r. i. issa and a. d. gosman, "prediction of imp eller induced flows in mixing vessels using multip le frames of reference", in 8th europ ean conference on mixing, cambridge, 1994. [28] f. m enter, "two-equation eddy -viscosity turbulence m odels for engineering ap p lications", aiaa journal, vol. 32, 1994, p p . 1598-1605. [29] a. m arkowitz, "raindrop size distribution exp ression”, journal of ap p lied m eteorology , vol. 15, 1976, p p . 1029 1031. [30] g. tay lor, "the shap e and acceleration of a drop in a high sp eed air stream", in the scientific pap ers of g. i. tay lor, ed., g. k. batchelo, 1963. [31] ge renewable energy , "cap acity factor leadership in class s winds, ge's 1.85 87", general electric, 2013. [32] http s://www.ge.com/renewableenergy /sites/default/files/rel ated_documents/wind-onshore-turbine-1.85-87 gea30627d-r1.p df [33] ge power & water renewable energy , "2.5m w wind turbine series", general electric, 2013. https://www.ge.com/renewableenergy/sites/default/files/related_documents/wind-onshore-turbine-1.85-87-gea30627d-r1.pdf https://www.ge.com/renewableenergy/sites/default/files/related_documents/wind-onshore-turbine-1.85-87-gea30627d-r1.pdf https://www.ge.com/renewableenergy/sites/default/files/related_documents/wind-onshore-turbine-1.85-87-gea30627d-r1.pdf international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 23-27 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 23 effect of plastic fins on a traditional solar still's efficiency a. khechekhouche 1* , a. m. de oliveira siqueira 2 , nabil elsharif 3 1 technology faculty, el oued university, algeria 2 chemical engineering graduate program, federal university of viçosa, brazil 3 mechanical engineering department, university of benghazi, libya * corresponding author e-mail: abder03@hotmail.com abstract –solar distillation is a relatively straightforward and environmental method. it is used in many countries and especially in isolated areas to treat polluted water. in this context, two similar solar stills of 50 x 50 cm were used in the same climatic conditions in order to test the influence of plastic fins on the performance of this device. the results show that there is a negative effect on the output of the distiller with a rate of 8.8 %. so this way is not recommended for researchers in this field. keywords: solar energy, solar distillation, water output, pure water. received: 02/04/2022 – revised 05/05/2022 – accepted: 27/05/2022 i. introduction solar energy is a plentiful, renewable, free, and environmentally friendly source of energy. algeria is a north african country with a fascinating energy potential, namely solar energy [1-3]. this energy can be used to treat dirty underground water [4-7]. several research labs throughout the world produce their prototypes [8-10]. according to the literature [11,12], the solar still is a straightforward device to construct. it is a process that is directly tied to the intensity of solar radiation, and any change in the latter causes a change in the still's productivity. an experimental investigation found that productivity is 1127 ml during the summer and 119 ml during the winter when solar radiation is low [13]. the purpose of all investigations, whether experimental, numerical, or simulation-based, is to increase the solar still's production. studies on cooling the glazing, or the condenser, have been focused on improving the efficiency of this device. according to the findings of a study on the cooling of a solar still's glass cover, daily production increased by 32.8 % [14]. another recent study discovered that combining a high thermal conductivity absorber with a glass cover cooling system increases efficiency from 105.9% to 107.7% [15-17]. others conducted an experimental investigation to see the effect of variation in glass cover thickness and the use of double glazing on the performance of conventional solar stills, while others concentrated their research on modifying the angle of cover to best maximize their device. the findings show that the angle of the glazing, as well as the thickness of the glazing, has a direct impact on the solar output. in the case of double glass, the data suggest that the solar still performance is significantly reduced [18-22]. the heating of brackish water is another component of the study. some study has used phase change materials (pcm) in the field of solar distillation to boost the productivity of the solar still. it raises the temperature of the water and speeds up the evaporation process. this substance is effective in the solar still, although its performance is dependent on the type of material and its concentration [23,24]. despite their high cost, nanofluids have been utilized in solar distillation for a few years. on the one hand, the data demonstrate that the rate of a. khechekhouche et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 23-27 page 24 improvement varies greatly depending on the composition of the nanofluid and its concentration in the solar still's water basin. other criteria, such as the quality of the water to be treated and its thickness, come into play as well [25,26]. the use of available tools such as cfd, matlab, or others to examine heat and mass transfer, temperature evolutions, and other aspects of solar stills is known as numerical modeling. they are efficient tools for constructing mathematical models that researchers can use to validate their findings [27-30]. the heating of brackish water is another focus of the study. some research has been done to improve the productivity of solar stills. the heating of brackish water is another focus of the study. some studies have used pebbles, granites, metal plates, charcoal, aluminum wastes, palm fibers, sand, or sponge pieces to boost the solar still's output. the results demonstrate that natural material improvement ranges from 15% to 273 %, with cubic sponge pieces having the highest upgrading value [31-37]. the objective of this work is to see the effect of plastic fins on the performance of a conventional solar still. ii. material and method two solar stills were tested in march at the university of el oued, south-eastern algeria. the first still ssr is taken as a reference still and the second ssm still is taken as a modify still. so plastic fins were placed in this second still in order to know the effect of the fins on the output of our device as shown in figure 1. temperature and water quantity measurements are taken every hour during the 8 hours of the experiment. figure 1. measurement system setting up iii. results and analysis iii.1. solar radiation and ambient temperature sun distillation depends heavily on solar radiation. the progression of this radiation over time is depicted in figure 2. additionally, it displays the changes in ambient temperature over time. note that the maximum radiation is 880 w/m 2 between 12:h00 and 13:h00 and the maximum ambient temperature is 31°c at 14:h00. figure 2. evolution of solar radiation and ambient temperature iii.2. internal glass temperature evolution figure 1 represents the evolution of the temperature of the glass cover (inner face) during the duration of the experiment. we notice that the temperatures increase until reaching their maximum values between 13:00h and 14:00h and we note that the temperatures of the inner face of the two stills are almost the same, which suggests that the temperature of the water will influence the output of the stills. figure 3. evolution of internal glass cover temperature a. khechekhouche et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 23-27 page 25 iii.3. water temperature evolution a live image of the experiment is shown in figure 4 along with the water temperature variation of the two solar stills. it should be noticed that the ssr's water temperature is higher than the ssm's water temperature. this illustrates that the plastic fins on the solar still's water basin have no beneficial impact on the water's ability to be heated. figure 4. water temperature evolution iii.4. accumulation output of pure water figure 6 represents the output of the 2 solar stills as a function of time. we notice from the beginning of the experiment, that the output of ssr is higher than the output of ssm and this is throughout the experiment. the change in pure water accumulation from the two solar stills is seen in figure 7. keep in mind that over the course of the experiment's eight hours, the ssm distiller gathered 432 ml of pure water, and the ssr distiller 470 ml. therefore, there is a 38 milliliter discrepancy. what demonstrates that plastic fins cannot be viewed as a technique for solar distillation enhancement figure 6. evolution of hourly output figure 7. accumulation output of pure water iv. conclusion an experiment was done to test the effect of plastic fins on the performance of a solar still. the results show that:  the temperature of the front side of the glass cover is the same.  the water temperature of ssr is higher than ssm.  the output of the modify solar still ssm is lower than the reference solar still ssr with an output of 8.8%. it can be said that plastic fins are not a means of improvement in solar distillation. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] s. pahlavan, m. jahangiri, a. alidadi shamsabadi, a. khechekhouche, "feasibility study of solar water heaters in algeria, a review, " journal of solar energy research, vol 3, pp.135-146. 2018. [2] m. ghodbane, b. boumeddane, "estimating solar radiation according to the semiempirical approach of perrin de brichambaut: application on several areas with the different climate in algeria," international journal of eenergetica, vol.1, pp. 20-29. 2016. http://dx.doi.org/10.47238/ijeca.v1i1.12 [3] d. benatiallah, a. benatiallah, k. bouchouicha, b. nasri, "estimation of clear sky global solar radiation in algeria, " aims energy, vol. 7, pp. 710-727. 2019. a. khechekhouche et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 23-27 page 26 [4] a. khechekhouche, b. benhaoua, meh. attia, z. driss, a. manokar, "polluted groundwater treatment in southeastern algeria by solar distillation," algerian journal of environmental science and technology, vol. 6, 2020. [5] k.k. sadasivuni, h. panchal, a. awasthi, m., f.a. essa, s. shanmugan, m. suresh, v. priya, a. khechekhouche, "ground water treatment using solar radiation-vaporization & condensation-techniques by solar desalination system, " international journal of ambient energy, 2020. https://doi.org/10.1080/01430750.2020.1772872 [6] h. panchal, k.k. sadasivuni, c. prajapati, m. khalid, f.a. essa, s. shanmugan, n. pandya, m. suresh, m. israr, s. dharaskar, a. khechekhouche, "productivity enhancement of solar still with thermoelectric modules from groundwater to produce potable water: a review, "groundwater for sustainable development, vol. 11, pp. 100429. 2020. https://doi.org/10.1016/j.gsd.2020.100429 [7] a. miloudi, a. khechekhouche, i. kermerchou, "pollution groundwater treatment by solar stills with palm fibers, " jp journal of heat and mass transfer, vol 27, pp. 1-12. 2022. [8] a. laaraba, a. khechekhouche, "numerical simulation of natural convection in the air gap of a vertical flat plat thermal solar collector with partitions attached to its glazing, " indonesian journal of science & technology, vol. 3, pp. 14-23, 2018. https://doi.org/10.17509/ijost.v3i2.12753 [9] m. ghodbane, d. benmenine, a. khechekhouche, b. boumeddane, "brief on solar concentrators: differences and applications, " instrumentation mesure métrologie, vol. 19, pp. 371-378, 2020. https://doi.org/10.18280/i2m.190507 [10] m. s. meftah, b. benhaoua, a. khechekhouche, "bottom collector isolation effect on the solar chimney performance," jp journal of heat and mass transfer, vol 26, pp. 27-40. 2022. [11] a. khechekhouche, n. elsharif, i. kermerchou, a. sadoun,"construction and performance evaluation of a conventional solar distiller," heritage and sustainable development, vol. 1, pp. 72-77. 2019. doi: 10.37868/hsd.v1i2.3 [12] m. elgendi, m.y.e. selim, a. aldhaheri, w. alshehhi, h. almarshoodi, a. alhefeiti, "design procedures for a passive pyramid solar still with an automatic feed water system, "alexandria engineering journal (2021). https://doi.org/10.1016/j.aej.2021.12.002 [13] a. khechekhouche, b. boukhari, z. driss, n.e. benhissen, "seasonal effect on solar distillation in the el-oued region of south-east algeria, " international journal of energetica, vol. 2, pp. 42-45. 2017. http://dx.doi.org/10.47238/ijeca.v2i1.27 [14] z.m. omara, a.s. abdullah, a.e. kabeel, f.a. essa, "the cooling techniques of the solar stills' glass covers – a review," renewable and sustainable energy reviews, vol.78, pp. 176-193, 2017. https://doi.org/10.1016/j.rser.2017.04.085 [15] a.e. kabeel, mohamed abdelgaied, "enhancement of pyramidshaped solar stills performance using a high thermal conductivity absorber plate and cooling the glass cover, " renewable energy, vol. 146, pp. 769-775. 2020. https://doi.org/10.1016/j.renene.2019.07.020 [16] m.e.h. attia, a.e. kabeel, m. abdelgaied, a. bellila, "optimization of the hemispherical solar distiller performance assisted by high thermal conductivity metal trays incorporated with reflective mirrors, " environmental science and pollution research. 2022. https://doi.org/10.1007/s11356-022-18708-y. [17] b. souyei, a. khechekhouche, s. meneceur, "effect of comparison of a metal plate and a refractory plate on a sollar still, " jp journal of heat and mass transfer, vol 27, pp. 37-56. 2022. doi: 10.17654/0973576322022 [18] r. cherraye, b. bouchekima, d. bechki, h. bouguettaia, a. khechekhouche," the effect of tilt angle on solar still productivity at different seasons in arid conditions-south algeria," international journal of ambient energy. 2020. https://doi.org/10.1080/01430750.2020.1723689 [19] a. khechekhouche, m. manokar, r. sathyamurthy, f. essa, m. sadeghzadeh, a. issakhovm," energy, exergy analysis, and optimizations of collector cover thickness of a solar still in el oued climate, algeria," international journal of photoenergy. article id 6668325, 2021. https://doi.org/10.1155/2021/6668325 [20] a. khechekhouche, b. benhaoua, a. m. manokar, a. e. kabeel, r. sathyamurthy," exploitation of an insulated air chamber as a glazed cover of a conventional solar still," heat transfer asian research, vol. 48, pp. 1563-1574. 2019. https://doi.org/10.1002/htj.21446 [21] a. khechekhouche, z. driss, b. durakovic," effect of heat flow via glazing on the productivity of a solar still, " international journal of energetica, vol. 4, pp. 54-57. 2019. http://dx.doi.org/10.47238/ijeca.v4i2.109 [22] a. khechekhouche, b. ben haoua, z. driss,"solar distillation between a simple and double-glazing," revue de mécanique, vol. 2, 2017. [23] p. negi, r. dobriyal, d.b. singh, g.k. badhotiya, "a review on passive and active solar still using phase change materials," materials today: proceedings, vol. 46, pp. 10433-10438. 2021. [24] j. kateshia, v.j. lakhera, " analysis of solar still integrated with phase change material and pin fins as absorbing material, " journal of energy storage, vol. 35, pp. 102292. 2021. [25] a.k. singh, d.b. singh, v.k. dwivedi, g.n. tiwari, a. gupta, "water purification using solar still with/without nano-fluid: a review," materials today: proceedings, vol. 21, pp. 1700-1706. 2020. https://doi.org/10.1016/j.matpr.2019.12.025 [26] t. arunkumar, h.w. lim, s.j. lee,"a review on efficiently integrated passive distillation systems for active solar steam evaporation," renewable and sustainable energy reviews, vol. 155, pp. 111894. 2022. https://doi.org/10.1016/j.rser.2021.111894 [27] g. mittal, an unsteady cfd modelling of a single slope solar still, materials today: proceedings, vol. 46, pp. 10991-10995. 2021. doi: 10.1016/j.matpr.2021.02.090 [28] d. dsilva winfred rufuss, s. arulvel, s. iniyan, l. suganthi, "numerical study of titanium oxide nanoparticle enhanced energy storage material in solar desalination, materials today: proceedings," vol. 43, pp. 805-808. 2021. [29] o. prakash, a. ahmad, a. kumar, s.m. mozammil hasnain, g. kumar, "comprehensive analysis of design software application in solar distillation units, "materials science for energy technologies. 2022. [30] h. al-madhhachi, g.f. smaisim, "experimental and numerical investigations with environmental impacts of affordable square pyramid solar still," solar energy, vol. 216, pp. 303-314. 2021. https://doi.org/10.1016/j.solener.2020.12.051 [31] a.e. kabeel, m. abdelgaied, a. eisa, "enhancing the performance of single basin solar still using high thermal conductivity sensible storage materials, " journal of cleaner production, vol. 183, pp. 20-25. 2018. https://doi.org/10.1016/j.jclepro.2018.02.144 [32] m.e.a. ouar, m.h. sellami, s.e. meddour, o.b. mokrani, "brackish water desalination using black granite as heat storage medium under arid climatic conditions, " desalination and water treatment, vol. 225, pp. 149–155. 2021. doi: 10.5004/dwt.2021.27204 [33] a. khechekhouche, b. benhaoua, m. manokar, r. sathyamurthy, a. kabeel, z. driss," sand dunes effect on the productivity of a single slope solar distiller," heat and mass transfer journal, vol. 56, pp. 1117-1126, 2020. https://doi.org/10.1007/s00231-01902786-9 https://doi.org/10.1007/s00231-019-02786-9 [34] a. sadoun, a. khechekhouche, i. kemerchou, m. ghodbane, b. souyei, "impact of natural charcoal blocks on the solar still https://doi.org/10.1016/j.gsd.2020.100429 https://doi.org/10.17509/ijost.v3i2.12753 https://doi.org/10.1016/j.aej.2021.12.002 https://doi.org/10.1016/j.rser.2017.04.085 https://doi.org/10.1016/j.renene.2019.07.020 https://doi.org/10.1007/s11356-022-18708-y https://doi.org/10.1155/2021/6668325 https://dx.doi.org/10.47238/ijeca.v4i2.109 https://doi.org/10.1016/j.rser.2021.111894 https://doi.org/10.1016/j.solener.2020.12.051 https://doi.org/10.1016/j.jclepro.2018.02.144 a. khechekhouche et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 23-27 page 27 output, " heritage and sustainable development, vol. 4, pp.61-66, 2022. doi: 10.37868/hsd.v4i1.80 [35] i. kermerchou, i. mahdjoubi, c. kined, a. khechekhouche, a. bellila, g. e. devora isiordia. palm fibers effect on the performance of a conventional solar still, asean journal for science and engineering in materials, vol. 1, pp. 29-36, 2022. [36] a. bellila, a. khechekhouche, i. kermerchou, a. sadoun, a. m. de oliveira siqueira, n. smakdji," aluminum wastes effect on solar distillation, " asean journal for science and engineering in materials, vol 1. 2022. [37] a. khechekhouche, b. benhaoua, a. kabeel, m. attia, w m. elmaghlany," improvement of solar distiller productivity by a black metallic plate of zinc as a thermal storage material," journal of testing and evaluation, vol. 49, 2019. doi: 10.1520/jte20190119 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 5. issue 1. 2020 page 14-21 . http://dx.doi.org/10.47238/ijeca.v5i1.115. june 2020 page 14 study of a solar air conditioning system with ejector mokhtar ghodbane 1 , boussad boumeddane 1 , abderrahmane khechekhouche 2,3 , djamel benmenine 4 1 mechanical engineering department, faculty of technology;university of blida 1, algeria 2 faculty of technology, university of el oued, algeria 3laboratory of electro-mechanic systems (lasem), enis of sfax, university of sfax, tunisia 4renewable energy department, kasdi merbah university of ouargla, algeria e-mail*: ghodbannemokhtar39@yahoo.com abstract –air conditioning is one of the indispensable conditions of well-being in human life, so the face of this research to provide this basic necessity in remote areas and in desert places far from power grids. to achieve this goal, solar air conditioning has been adopted, where the compressor was replaced by an ejector, a parabolic trough solar collector coupled with a thermal generator and a small pump; this means that the solar air conditioner does not need a huge amount of electrical energy to operate. this paper is studding the optical and thermal efficiency of the solar collector used as a solar thermal generator, refrigeration subsystem performance (copejc) and system thermal ratio of the studied air conditioner, where the cooling load is estimated at 18 kw. this work has allowed to acquire very important knowledge about r718 ejector solar air conditioners. bouzaréah was chosen as the region to conduct this numerical study on june 11 th , 2018. regarding performance of the studied air conditioning subsystem (copejc) is 0.6235. as for the ptc solar reflector subsystem, its mean optical performance is 75.74 % and its mean thermal performance is 65.01 %. regarding the overall performance of the studied air conditioner, its mean value is 0.407. keywords: solar energy; water (r718); ejector; system thermal ratio (str). received: 03/02/2020 – accepted: 10/04/2020 i. introduction the role of renewable energies in industry and in human life is considerable. solar energy is the most important source of energy and is available in significant quantities in most regions of the globe [1, 2]. use of solar thermal energy in sunny countries such as algeria is an effective way to overcome energy shortages, especially in rural areas where it is sometimes difficult and expensive to provide them with a conventional electricity grid [1, 3, 4]. in addition, algeria is a country where the solar energy potential received daily on a horizontal surface of 1 m² is around 5 kwh over most of the national territory, where this lighting must be used in an intelligent and sustainable way to be able to meet the qualitative and quantitative needs of energies such as the production of electricity, heating, air conditioning, etc. [1, 4]. therefore, it is important to exploit this natural and cleaner resource in the field of cold production especially in the solar-driven ejector air conditioning system because of its simplicity of design and implementation. due to the increasing cost of energy and the reduction of its sources, a solar-driven ejector air conditioning system using low or medium temperature heat rejection or a free solar energy have become in recent years an interesting subject of study [5-7]. among the machines that are currently used in the field of air conditioning, the a solar-driven ejector air conditioner on the one hand, because of the air conditioning and cooling required in buildings that exist in industrial fields (oil and gas processing centers, etc.) and the availability of thermal resources either of solar origin in developing countries, or from low-temperature thermal discharges in industrialized countries, and secondly, thermodynamicists encourage the study of refrigeration production systems directly using solar energy [8-13]. the means by which this operation is carried out is the use of ejector refrigeration machines, also called thermodynamic machines with three temperature sources in which the hot source can be powered by the solar energy or by heat discharges, the cold source is produced at the cold source, i.e. the mailto:ghodbannemokhtar39@yahoo.com mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 15 evaporator and the residual heat from the condenser transferred to the ambient medium constitutes the third source. the ejector solar air conditioner is a very effective solution in rural areas and in desert industrial complexes because it has simple assembly and it has an acceptable performance [14-16]. for these reasons, this air conditioning technology is more attractive than conventional air conditioners technology because it is less expensive. in this work, an ejector air conditioner coupled with a water parabolic trough collector was studied at bouzaréah region in june 11 th , 2018. the studied air conditioner does not contain a gas compressor which is the main consumer of electricity. in addition, the studied system uses clean, environmentally friendly refrigerant and does not cause any gaseous emissions that threaten the ozone layer. ii. ejector air conditioning subsystem the operating mode of the studied machine is presented in the form of equations using the thermodynamic laws such as mass and energy conservation and the impulse conservation to determine the system thermal characteristics. the refrigerant r718 plays a key role in improving the performance of the studied system. fig. 1 represents a longitudinal section of a typical ejector. figure 1. illustrative schematization of a typical ejector [17]. as shown in figures 2(a-b), the model of the ejector air conditioner subsystem is based on the refrigerant thermodynamic states in each operating point, as this subsystem has two closed loops [18, 19]:  the driving loop (7-1-2-3-4-5-6-7);  the refrigerating loops (7-8-9-5-6-7). a) air conditioning loop b) (p-h) enthalpy diagram figure 2. operating loops of an ejector air conditioner: a) air conditioning loop, b) (p-h) enthalpy diagram. ii.1. driving loop (dl) in the driving loop, the energy supplied to the generator is used to evaporate a portion of the refrigerant which represents the driving fluid (primary), which is at high pressure (from state 1 to state 4), then passes through the ejector where it is mixed with the other part of the refrigerant which represents the fluid entrained (secondary), coming from the evaporator and where also performs a pressure recovery (from state 4 to state 6). then, all of the refrigerant passes through the condenser where it is condensed to the liquid state (from state 6 to state 7). this liquid will be pumped (pressure increase) to the generator and thus completes the cycle (from state 7 to state 1). ii.2. cooling loop (cl) in the refrigeration cycle, part of the refrigerant in the liquid state which represents the entrained fluid (secondary) passes through an expansion valve to bring it to a state of low pressure (from state 7 to state 8). the refrigerant subsequently enters the evaporator where it produces by evaporating the desired cold « 18 kw » (from state 8 to state 9). the refrigerant is mixed with the other part (the driving fluid) in the ejector where it is compressed (from state 9 to state 6) and the mixture mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 16 passes through the condenser where it is condensed to the liquid state and complete thus the cycle (from state 6 to state 7). these two loops (dl and cl) illustrate the thermodynamic working principle of the ejector air conditioner. in order for the ejector conditioning subsystem to work well, the condenser critical condition (pc = critical pressure) must be achieved. the pressure at the ejector outlet « diffuser » (p6) is less than or equal to the condenser critical pressure (p6 ≤ pc). in this study, a constant pressure mixing ejector (cpm ejector) has been used, as the ejector neck outlet is in the suction chamber before the fixed chamber, the primary and secondary flows are mixed in the chamber aspiration at this pressure. the pressure of the mixing streams remains constant along the chamber from the ejector neck outlet to the inlet of the constant surface section. therefore, cpm ejector has better efficiency than the rest of the ejector. for optimal understanding of the ejector working principle, it is advisable to familiarize yourself with the gas-dynamic lessons and a good understanding of the working principle of convergent-divergent pipes [19-22]. according to figures 2(a-b), the energy balance at the mixing point inside the ejector is given by [19-21] : 9e3g5eg .hm.hm)hm(m  (1) as for the isentropic efficiency of the ejector nozzle, it is given by [19-21] : is4,3 43 n hh hh η    (2) regarding diffuser isentropic efficiency, it can be calculated as follow [19-21] : 56 5is6, d hh hh η    (3) concerning mass ratio (drive ratio), is given by [18-21]:     1hh hh ).η(η m m ω 5is6, is4,3 dn g e          (4) as for the isentropic ejector efficiency, it can be calculated by [19-21] : dn .ηηλ  (5) regarding subsystem compression ratio, it is defined as follow [18-21]: e c p p p r  (6) as for the ejector air conditioning subsystem performance, it is the ratio between the cooling capacity “qe, (w)” and the required heat input “qg, (w)” to the ejector [18-21, 23] : )( )( 13 89 hhm hhm q q cop g e g e ejc    (7) where “h (j/kg)” refers to the enthalpy, “mg, (kg/s)” is the r718 mass flow rate into the generator and “me, (kg/s)” is the r718 mass flow rate into the evaporator. the thermodynamic analysis of ejector air conditioning subsystem loops was carried out with the engineering equation solver (ees). iii. solar collector subsystem the family of linear solar concentrators includes two types, the first is the linear fresnel reflectors (lfrs) [24-27] and the second is the parabolic trough collectors (ptcs) [28-30]. the operating principle of a parabolic trough collectors (ptc) lies in its parabolic mirror in the form of a half cylinder, where this mirror can be rotated following the path of the sun to constantly redirect and focus the beam radiation “dni, (w/m²)” towards an receiver tube where the working fluid passes to gain heat. one of the most important objectives of this part of the study is to determine the change in heat loss coefficient “ul, (w/m².k)” that helps to determine the heat loss amount around the studied solar reflector. table 1 and table 2 show the geometric and optical parameters of the studied ptc. table 1 . ptc geometric parameters geometric characteristics value (mm) outside diameter of the absorber (do) 22 inner diameter of the absorber (di) 20 outer diameter of the window (dg,o) 26 inside diameter of the glass (dg,i) 23.5 mirror length (l) 12270 mirror width (l) 1200 the studied system is installed in the north algeria, exactly in the research center of bouzaréah in the geometrical coordinates are 36° 47’ 24 "north, 3° 01’ 04" east, its altitude is 230 m and its surface is 22 km². mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 17 table 2 . ptc optical parameters. parameters value overall average optical error 03 mrad mirror reflectivity (ρm) 0.85 glass tube transmissivity () 0.945 receiver tube absorptivity (α) 0.90 receiver tube emissivity (a) 0.12 glass tube emissivity (v) 0.935 heat exchange occurs between the working fluid (water), the receiver tube and the glass tube. a calculation program in engineering equation solver has been developed to make the necessary calculations according to the following hypotheses:  the heat transfer fluid is incompressible;  the ambient temperature around the studied ptc is uniform;  the effect of the receiver tube shadow on the mirror is negligible;  the solar flux at the receiver tube is evenly distributed;  the glass tube is considered opaque to infrared radiation;  the conduction exchanges in the receiver and glass tube are negligible;  the water mass flow into receiver tube is 0.015 kg/s;  the water inlet temperature “ti, (k)” is 298.15 k. the amount of useful energy “qgain, (w)” that the working fluid acquires from the absorption tube can be estimated as follows [31, 32]:   ambirlaoprgain ttaua dni ηfq  (8) with "aa, (m²)" is the ptc opening area, "ar, (m²)" is the receiver tube surface, "tamb, (k) "is the ambient air temperature and “fr” is the heat dissipation factor. as for the ptc optical performance, it can be expressed by [33-35]: )k(ρα= mopt   (9) with “k()” shows the correction coefficient of incidence angle modifier [35, 36]. regarding overall heat loss coefficient "ul, (w/m².k)", it is given as follows [19, 31, 32] :   1 arr,gacr,w r l h 1 ahh a u              (10) with "ag, (m²)" is the glass tube area, "hw, (w/m².k)" is the wind convection coefficient, "hr,ca, (w/m².k)" is the radiative exchange coefficient between the glass and the ambient air and "hr,ra, (w/m².k)" is the radiative exchange coefficient between the absorber and the glass. regarding working fluid temperature “to, (k)” at the absorber tube exit, it is given by [19, 32, 37]: p .io c tt m q gain  (11) as for the ptc thermal performance, it is given by:   a a dni amb t ab t exta, a l u opt ηη th    (12) the thermal behavior of the studied solar reflector was attributed using ees, which was used as a programming language. iv. results and discussion as shown in figure 3, the ejector solar air conditioning machine is a system that has three sources of heat (a hot source corresponding to the motive heat supplied to the system, a cold source corresponding to the cold production and an intermediate source that allows the connection between the hot and cold sources). figure 3. solar ejector air conditioner for balance analysis the ejector solar air conditioner is similar to the conventional compression air conditioning system except that a pump, a steam generator and an ejector replace the compressor. the beam radiation transformed by the ptc reflector to thermal energy is used to generate a high temperature and pressure steam in the generator (primary fluid) that expands in the primary nozzle of the ejector. at the outlet, the high speed primary fluid drives the secondary fluid from the evaporator. then, the primary and secondary streams mix at constant pressure in the mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 18 mixing chamber. a first pressure increase due to the formation of a shock wave takes place in the mixing chamber followed by a second due to compression in the diffuser. at the diffuser outlet, the mixture condenses in the condenser, as a part of the condensate passes into the evaporator through a throttle valve to produce the cooling effect while the rest of the refrigerant returns to the generator via a circulation pump. regarding system thermal performance, it can be introduced as the product of the ejector air conditioning subsystem performance (copejc) and the ptc thermal performance (ηth). as for the system thermal ratio, it is given by [18, 19, 23]: thejc copstr . (13) this work aims to determine the parameters that are affected on the performance of the studied system based on the operating conditions shown in table 3, where the studied solar reflector is without storage tank and without auxiliary boiler. the simulation is executed under the following assumptions:  r718 is considered a perfect fluid with constant thermophysical parameters and its flow is stationary;  the kinetic energy of primary and secondary flows is negligible ;  the internal walls of the ejector are adiabatic ;  the outlet of the ejector is connected to the condenser. table 3 . operating conditions of the ejector solar air conditioner. service operating conditions value (k) generator temperature (tb) 393.15 condenser temperature (tc) 308.15 evaporator temperature (te) 288.15 on june 11 th , 2018 in bouzaréah, sun rises at 05:28 and sets about 14 hours and 39 minutes later (at 20:06), where the solar noon is at 12:47. as for the average air temperature, it varies from 289.15 to 301.15 k, where the average hourly wind speed varies with a daily average of 3.61 m/s. figure 4 illustrates the changes in beam radiation on june 11 th , 2018 at bouzaréah, algeria. as shown in figure 4, the maximum value of beam radiation is 1020.13 w/m² at 12:02, where its minimum value is 53.30 w/m² just before sunset and the mean beam radiation is 853 w/m². as it is noticed, the beam radiation quantity for the studied day is very considered, and it can be used for many uses such as air conditioning and seawater desalination in the region. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 100 200 300 400 500 600 700 800 900 1000 1100 b e a m r a d ia ti o n ( w /m ²) time (hour) figure 4. beam radiation assessment. figure 5 shows the change in temperature of the working fluid “thtf, (k)”, the receiver tube “tab, (k)” and the surrounding glass tube “tg, (k)”. from figure 5, it observed that the mean working fluid temperature is 431.15 k, i.e., the water has changed its nature from the liquid state to the vapor's intense heat in order to drive the ejector air conditioning subsystem by pumping this acquired heat to the generator, where it is noticed that the water is in a steam state from 08:00 until 17:00, meaning that the studied conditioner will work for nine hours continuously with solar energy without any interruption. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 470 480 490 t e m p e ra tu re s ( k ) time (hour) absorber tube temperature fluid temperature glass tube temperature figure 5. change in temperatures. as for the mean values of receiver tube and glass tube temperatures, they are 439.12 k and 404.39 k, respectively. in addition, it is observed from figure 5 that the receiver tube and glass tube temperatures are high, however the values of the heat loss coefficient "ul, (w/m².k)" are acceptable as shown in figure 6, and this is due to the emptying of the space between them from the air. mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 19 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 h e a t lo s s c o e ff ic ie n t u l ( w /m ². k ) time (hour) figure 6. assessment of overall heat loss coefficient vs. time. regarding heat loss coefficient, it varies from 3.70 to 6 w/m².k ant its mean value is 5.50 w/m².k. unlike conventional compression air conditioning systems, solar ejector air conditioners do not have a mechanical compressor, but they have an ejection thermal system (a solar thermal generator, a pump and a steam ejector). by numerical simulation, the ejector dimensions that correspond to the operating conditions of the air-conditioning system shown in table 3 have been obtained. table 4 shows the dimensions of primary nozzle throat diameter (dt) and constant area section diameter (dm) which is characterized by the ejector under critical conditions (p4 ≤ pc, where pc = 5627 pa) with the previous operating conditions and with a load cold equal to 18 kw. table 4 . dimensions of (dt) and (dm) under critical conditions ejector critical condition (p4≤ pc= 5627 pa) primary nozzle throat diameter (dt) 0.004009 m constant area section diameter (dm) 0.04214 m table 5 illustrates the drive ratio (ω) and ejector performance values of the studied air conditioning subsystem. table 5 . the drive ratio (ω) and ejector performance (copejc) of the studied ejector subsystem. ejector critical condition (p4≤ pc= 5627 pa) ω 0.8376 copejc 0.6235 regarding ptc optical performance, ptc thermal efficiency and system thermal ratio, they are shown in figure 7. 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0.500 0.525 0.550 0.575 0.600 0.625 0.650 0.675 0.700 0.725 0.750 thermal efficiency optical efficiency str time (hour) p t c e ff ic ie n c ie s 0.3850 0.3875 0.3900 0.3925 0.3950 0.3975 0.4000 0.4025 0.4050 0.4075 0.4100 0.4125 0.4150 s y s te m t h e rm a l ra ti o ( s t r ) figure 7. assessment of the system performances. as for the ptc optical performance, its mean value is 75.74 %, while the mean value of ptc thermal efficiency is 65.01 %. concerning thermal system ratio, it varies from 0.39 to 0.411. the solar ejector air conditioner is a tri-thermal machine that allows using three temperature levels in order to produce cold from heat only. it is noticeable that the overall performance of the system (str) is low, however this system is effective and sufficient for adapting, as it provides a cooling load of 18 kw for a period of nine hours a day without consuming any electricity except a very small amount to operate the pump. generally, the system thermal ratio varies automatically according to the temperatures (te), (tc) and (tb) of the ejector air conditioning subsystem, and is affected by the change in ptc thermal efficiency. v. conclusion the ejector solar air conditioner uses the ejector as a static compressor, which the ejector uses the primary fluid vapor as driving energy. the ejector solar air conditioner has four main elements as follow generator, ejector, condenser and the evaporator. in addition, it consists of two loops; one is the driving loop and the other the cooling loop. this work has allowed acquiring very important knowledge about r718 ejector solar air conditioners. bouzaréah was chosen as the region to conduct this numerical study on june 11 th , 2018. regarding performance of the studied air conditioning subsystem (copejc) is 0.6235, as it is very sensitive to changes in condenser temperature (tc), so to improve the performance of the machine it is necessary to increase the temperature of hot and cold sources (tb and te). as for the ptc solar reflector subsystem, its mean optical performance is 75.74 % and its mean thermal performance is 65.01 %. regarding the system thermal ratio, its mean value is 0.407, knowing that the cooling load of the studied machine is 18 kw. mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 20 finally, this type of solar air conditioner can be an ideal solution for providing luxury and air conditioning in residential complexes, institutional buildings, and at the living bases of workers in the hydrocarbon sector in southern algeria. this technology is low cost and does not contain any negative effects on the environment, as it contributes to the development of sustainable technology. as prospective, the research team in the future will manufacture a prototype for this r718 ejector solar air, then conduct practical experiments on it in order to track its thermodynamic behavior and then improve its performance. references [1] m. ghodbane, b. boumeddane, and n. said, "a linear fresnel reflector as a solar system for heating water: theoretical and experimental study," case studies in thermal engineering, vol. 8, no. c, 2016; pp. 176-186, [2] m. ghodbane and b. boumeddane, "estimating solar radiation according to semi empirical approach of perrin de brichambaut: application on several areas with different climate in algeria," international journal of energetica, vol. 1, no. 1, 2016, pp. 20-29. [3] m. ghodbane, b. boumeddane, and n. said, "design and experimental study of a solar system for heating water utilizing a linear fresnel reflector," journal of fundamental and applied sciences, vol. 8, no. 3, 2016, pp. 804-825, [4] m. ghodbane, b. boumeddane, z. said, and e. bellos, "a numerical simulation of a linear fresnel solar reflector directed to produce steam for the power plant," journal of cleaner production, vol. 231, 2019, pp. 494-508. [5] e. bellos and c. tzivanidis, "optimum design of a solar ejector refrigeration system for various operating scenarios," energy conversion and management, vol. 154, 2017, pp. 11-24. [6] e. bellos and c. tzivanidis, "parametric analysis and optimization of a cooling system with ejectorabsorption chiller powered by solar parabolic trough collectors," energy conversion and management, vol. 168, 2018, pp. 329-342. [7] e. bellos, i. c. theodosiou, l. vellios, and c. tzivanidis, "investigation of a novel solar-driven refrigeration system with ejector," thermal science and engineering progress, vol. 8, 2018, pp. 284-295. [8] z. zhang, x. feng, d. tian, j. yang, and l. chang, "progress in ejector-expansion vapor compression refrigeration and heat pump systems," energy conversion and management, vol. 207, 2020, pp. 112529. [9] v. v. nguyen, s. varga, j. soares, v. dvorak, and a. c. oliveira, "applying a variable geometry ejector in a solar ejector refrigeration system," international journal of refrigeration, 2020. [10] y. han et al., "characterization of choking flow behaviors inside steam ejectors based on the ejector refrigeration system," international journal of refrigeration, 2020. [11] m. habibi, f. aligolzadeh, and a. hakkaki-fard, "a techno-economic analysis of geothermal ejector cooling system," energy, vol. 193, 2020, pp. 116760. [12] f. foroozesh, a. b. khoshnevis, and e. lakzian, "improvement of the wet steam ejector performance in a refrigeration cycle via changing the ejector geometry by a novel eec (entropy generation, entrainment ratio, and coefficient of performance) method," international journal of refrigeration, vol. 110, 2020, pp. 248-261. [13] h. s. cao and h. j. m. ter brake, "progress and challenges in utilization of ejectors for cryogenic cooling," applied thermal engineering, vol. 167, 2020, pp. 114783. [14] m. bencharif, h. nesreddine, s. c. perez, s. poncet, and s. zid, "the benefit of droplet injection on the performance of an ejector refrigeration cycle working with r245fa", international journal of refrigeration, 2020. [15] a. mwesigye, a. kiamari, and s. b. dworkin, "energetic optimization and exergetic performance investigation of an ejector system using hcfo1233zd(e) as a refrigerant", international journal of refrigeration, 2019. [16] g. chen, v. ierin, o. volovyk, and k. shestopalov, "thermodynamic analysis of ejector cooling cycles with heat-driven feed pumping devices", energy, vol. 186, 2019, pp. 115892. [17] s. varga, p. m. s. lebre, and a. c. oliveira, "cfd study of a variable area ratio ejector using r600a and r152a refrigerants. international journal of refrigeration vol. 36, 2013, pp. 157-165. [18] w. pridasawas and p. lundqvist, "a year-round dynamic simulation of a solar-driven ejector refrigeration system with iso-butane as a refrigerant," international journal of refrigeration, vol. 30, 2007, pp. 840-850, [19] m. ghodbane and b. boumeddane, "numerical simulation of a solar-driven ejector refrigeration cycle coupled to a parabolic trough concentrator " international journal of chemical and petroleum sciences, vol. 5, no. 1, 2016, pp. 1-12. [20] m. ghodbane, "étude et optimisation des performances d'une machine de climatisation a éjecteur reliée à un concentrateur solaire " doctorat en système énergétiques et thermiques, département de mécanique université saad dahleb de blida 1 2017. [21] m. ghodbane, b. boumeddane, s. largot, and h. berkane, "modélisation d'un cycle de réfrigération solaire à éjecteur couplée à un concentrateur cylindro-parabolique," in international conférence en clean cooling technologies in the me na regions (ict3_mena'2015) bou smail, w. tipaza, 5-6 2015. [22] m. ghodbane and b. boumeddane, "physical description of an isentropic flow in a laval nozzle", revue des energies renouvelables, vol. 19, no. 1, pp. 41-47, 2016. [23] w. pridasawas and p. lundqvist, "an exergy analysis of a solar-driven ejector refrigeration system," solar energy, vol. 76, pp. 369–379, 2004. [24] m. ghodbane, z. said, a. a. hachicha, and b. boumeddane, "performance assessment of linear fresnel solar reflector using mwcnts/dw nanofluids," renewable energy, , 2019. mokhtar ghodbane et al. ijeca-issn: 2543-3717. june 2020 page 21 [25] z. said, m. ghodbane, a. a. hachicha, and b. boumeddane, "optical performance assessment of a small experimental prototype of linear fresnel reflector", case studies in thermal engineering, , 2019. [26] m. ghodbane, e. bellos, z. said, b. boumeddane, a. k. hussein, and l. kolsi, "evaluating energy efficiency and economic effect of heat transfer in copper tube for small solar linear fresnel reflector", journal of thermal analysis and calorimetry, 2020. [27] e. bellos, c. tzivanidis, and a. papadopoulos, "enhancing the performance of a linear fresnel reflector using nanofluids and internal finned absorber," journal of thermal analysis and calorimetry, vol. 135, no. 1, 2019, pp. 237-255. [28] a. fernandez-garcıa, e. zarza, l. valenzuela, and m. perez, "parabolic-trough solar collectors and their applications," renewable and sustainable energy reviews, vol. 14, 2010, pp. 1695–1721. [29] e. bellos and c. tzivanidis, "alternative designs of parabolic trough solar collectors," progress in energy and combustion science, vol. 71, 2019, pp. 81-117. [30] m. ghodbane and b. boumeddane, "a parabolic trough solar collector as a solar system for heating water: a study based on numerical simulation," international journal of energetica, vol. 2, no. 2, 2017, pp. 29-37. [31] s. a. kalogirou, solar energy engineering : processes and systems, 1st ed. academic press, 2009. [32] m. ghodbane, b. boumeddane, and s. largot, "simulation numérique d’un concentrateur cylindro-parabolique en el oued, algérie," international journal of scientific research & engineering technology (ijset), vol. 3, no. 2, 2015, pp. 68-74. [33] k. f. yogi d.g, kreider j.f, " off-normal incidence effects," in principles of solar engineering, t. francis., ed. 2nd edition ed., 1999, p. 139. [34] m. ghodbane and b. boumeddane, "a numerical analysis of the energy behavior of a parabolic trough concentrator," journal of fundamental and applied sciences, vol. 8, no. 3, 2016, pp. 671-691. [35] m. ghodbane and b. boumeddane, "engineering design and optical investigation of a concentrating collector: case study of a parabolic trough concentrator " journal of fundamental and applied sciences vol. 10, no. 2, 2018, pp. 148-171. [36] e. bellos, "progress in the design and the applications of linear fresnel reflectors – a critical review," thermal science and engineering progress, 2019. [37] m. li and l. l. wang, "investigation of evacuated tube heated by solar trough concentrating system. " energy conversion and management, vol. 47, 2006, pp. 3591–3601. i. introduction ii. ejector air conditioning subsystem iii. solar collector subsystem iv. results and discussion v. conclusion references ijeca-issn: 2543-3717. june 2021 page 43 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 1. 2021 page 43-54 numerical study of a hybrid photovoltaic/thermal pvt solar collector using three different fluids a. ghellab *1,2 , t.e. boukelia *2,3 , s. djimli 1,2 , a. kaabi 4 1 laboratory of applied energies and materials, faculty of sciences and the technology, ouled aissa bp 98, university of jijel, algeria 2 mechanical engineering department, faculty of sciences and the technology, ouled aissa bp 98, university of jijel, algeria 3 laboratory of mechanical and advanced materials, polytechnic school of constantine, constantine, algeria 4 climatic engineering department, faculty of science and technologies, route ain el bey, university of constantine1, algeria .email *:ghellab_amel@yahoo.fr and taqy25000@hotmail.com abs tract – hybrid photovoltaic and thermal (pv/t) systems have been widely used for the combination of pv modules and solar thermal collectors to generate both electrical energy and heat at the same time. in the present work , a numerical model has been developed to simulate the performances o f a hybrid photovoltaic/thermal (pv/t) solar collector. furthermore, a comparative study has been performed between the hybrid pv/t work ing with three conventional working fluids; air, water, and specified nanofluid (al2o3+ water). the obtained results show that the use of the alumina nanofluid is the best choice to increase the heat removal, and to improve the performances of the collector with the values of 73.28%, 10.37% and 99.21% for the thermal, electrical and global efficiency respectively. on the other hand, the p vt collector working with air as the primary fluid is the worst in terms of electrical, thermal, and global performances with the lowest values of 9.506 %, 41.55%, and 65.315% respectively. keywords: hybrid solar collector, nanofluid, numerical study, performance, nanofluid. received: 30/03/2021 – accepted: 29/06/2021 i. introduction many academics fro m a ll over the world are attempting to meet the rising need for energy, by developing diffe rent types of solar collectors to provide a clean energy in sufficient quantities and at low costs. for many decades, the hybrid photovoltaic and therma l (pv/t ) systems have been widely used for the combination of pv and solar therma l e ffects to generate both electrical and thermal energies, as it is we ll-known that the cell effic iency is decreasing with high temperatures. theoretical and also e xperimental research on hybrid pv/ t systems using air and/or water as working fluids were documented. for e xa mple , previous research [1-2] found that the flat plate photovoltaic therma l (pv/t) solar co llector is a good option for low energy applications in homes, commerc ial buildings, and industrial. prakash [3] has presented a dynamic model o f a hybrid pv/t solar system using two fluids; air and water as working fluids. it was reported that the therma l efficiency varies fro m 50% to 67% for water heating, and fro m 17% to 51% for a ir heating. in the case of air heating, the lowe r therma l effic iency is attributable to the poor conductivity and specific heat of a ir co mpared to water. a study has developed an analytical mode to compare and contrast the performance of a pv/t collector with two layouts; single and double pass. they concluded that the double pass pv/t co llector outperformed the single pass pv/t collector [4]. however, another study has showed a pv/t a ir heater with four designs for single and double pass. he developed the therma l mode l of every system, then e xa mined the effect of air specific flow rate on the performance of each one [5]. nine distinct designs of a combination pv/t water/a ir solar collector were evaluated by a research group, they revealed that the best design is the sheet-and-tube collector with single cover http://www.ijeca.info/ http://www.ijeca.info/ mailto:ghellab_amel@yahoo.fr mailto:taqy25000@hotmail.com a. ghellab et al ijeca-issn: 2543-3717. page 44 [6]. an e xp lic it dynamic model has been performed a pv/t co llector with a single gla zed flat plate for water heating. the model captured the instantaneous energy outputs and allowed for a detailed investigation of transient behavior across multip le collector co mponents [7]. a theoretical mode l was developed to study the effect of the channel d imension, as well as the mass flo w rate on the perfo rmance of such system. the results we re validated with those issued by their e xperience [8]. the paper looked at hybrid pv/t systems that ext ract heat fro m pv modules using air or water. he a lso e xperimented with three d ifferent ways to place the water heat exchanger inside the air channel; the modified twin pv/t collectors were co mb ined with booster diffuse reflectors to improve the pv/t systems' e lectrica l and therma l output. by integrating low-cost e xtra system ele ments, the recommended comb ination of diffuse reflectors improved the effective operation on horizontal building roof installation [9]. sc ientific work has focused on an experimental study by adding the propylene glycol (pg) in water as a working fluid in a pv/t solar collector. their obtained results indicated that the using of pg-water at 25% pg concentration, reduced the effic iency of the flat plate solar collector by 15.68% , compared with pure water [10]. a hybrid pv/t collector with water as working fluid produced in a copolyme r materia l was also described and simu lated in another study. they pointed out that using the copolymer reduces the weight and cost of such systems, as well as ma king them easier to manufacture [11]. investigation has studied the performances of a pv/t air heater with a double pass layout, and vertical fins in the bottoming channel of the absorber surface. such enhancement improves the heat transfer area to air, and increases the efficiencies of this form of co llector, according to the researchers [12]. the literature showed the enormous efforts which have been made to enhance the heat ext raction fro m the cells in a solar pv/t co llector, in order to imp rove t he electrica l conversion efficiency by using cooling fluids which have higher thermo-physical proprieties. this condition can be realized by adding ultra-fine solid particles of millimeter or mic ro meter size to the working flu id. on this d irection, most of research works we re ma inly based on nanofluids, which are co mposed of particles dispersed in water with various concentrations ranging. based on previous research’s review papers [13 15], in solar therma l systems, nanofluids can be used to improve the therma l e ffic iency and performance o f the solar collector. they found that producing a nanofluid based solar collector e mits roughly 170 kg/year less co2 on average than a traditional solar collector, implying that nanofluid causes less environmental da mage. however, the revie ws [16-18] summa rized the recent correlations developed to analyze the free and fo rced heat transfer convection phenomena in flow with nanoflu ids. a group of scientists has proposed a new correlation for the convective heat transfer of a cu-water nanoflu id for both laminar and turbulent flow conditions. they determined that this correlation takes into consideration the major e le ments impacting nanofluid heat transfer and that the presence of nanoparticles improves heat transfer performance [19]. on the other hand, another group has performed a co mprehensive analysis in order to evaluate the effects of variations in volu me fraction and temperature of nanofluid on its density, specific heat, therma l conductivity and viscosity [20]. the effect of cooper nanoparticles in the presence of a magnetic fie ld on unsteady non-darcy flo w and heat transfer over a porous wedge due to solar rad iation has been studied theoretically [21]. another research has studied numerically the heat transfer and pressure drop of three diffe rent nanofluids which were : copper o xide (cuo), alu mina (al2o3), o xide titaniu m (tio2), and water as based fluid. the results illustrated that by increasing the volume of concentration of nanoparticles, the heat transfer coeffic ient increased. furthermore, for a constant volume of concentration, the effect of cuo nanoparticles to enhance the nusselt number was better than the two other nanoparticles; al2o3 and tio2 [22]. study have reported the results of an experiment analysis, and have studied the effect of al2o3-h2o nanofluid as an absorbing mediu m on the efficiency of flat plate solar collector. the results of the experiment showed that the use of a concentration of 0.2 % al2o3 nanofluid increased the efficiency of the solar collector in comparison with water as wo rking fluid by 28.3%, and by using surfactant the ma ximu m enhanced efficiency is about 15.63% [23]. scientific analysis has analyzed the effect of nanofluid on the performances of an absorber of a direct solar collector. they showed that the particle size has minimal influence on the optical propriet ies of nanofluid, and the e xtinction coefficient is linearly proportionate to volume fraction [24]. another scientific analysis has studied experimentally the forced convectio n flow o f alu minu m o xide nanoparticles dispersed in water through a circula r p ipe. the results showed that the presence of nanoparticles in the working flu id caused a re markable increase in the heat transfer comparing to the working fluid itself [25]. furthermo re, scientific tea m have investigated experimentally the e ffect of density, therma l conductivity and viscosity of water and ethylene glycol water mixture (60:40 by mass) based alumina nanofluids, on the pressure drop and pumping power for a. ghellab et al ijeca-issn: 2543-3717. ( page 45 a flat p late solar collector. it was observed that the viscosity of the al2o3-water nanofluids e xponentially decreased with increasing in working temperature, and they have indicated the non-linear relat ion between viscosity and concentration. they showed that the pressure drops and consumed power for fluid pu mp ing of nanofluid flows are a lmost similar to that of the base liquid with low concentration [26]. another tea m have performed a nu merical simu lation of the heat transfer enhancement and behaviors of water-γ al2o3, and ethylene glycolγ al2o3 nanoflu ids in two different confined flow situations. their findings revealed that the use of nanoparticles resulted in a significant increase in heat transmission. however, and according to our knowledge concluded fro m literature, no co mparative study has been presented to compare the performances of these systems using different working fluids, thus, the objective of the present study is to use nanoparticles within the working flu id for a hybrid pv/ t solar collector, and to ma ke a co mparison in terms of efficiencies between this solar collector with three diffe rent flu ids (air, water, and alu mina nanofluid (al2o3+water)) [27]. this study takes constantine (north-east of algeria) as a case study, and a nu merical model is developed by presenting energy balances for different nodes: glazing, pv ce ll, absorber, fluid and back plate, and considering the transient effects. ii. description of the studied pv/t collector figure 1 shows a cross -sectional view of the proposed photovoltaic/thermal (pv/ t) collector. the investigated system is made up of transparent glazing located at the top of the collector, wh ich transmitted the incident solar radiation to the solar cell, and the absorber at the bottom of pv/t collector. the stagnant air in the air gap is assumed circulate under free convection. a fraction of the incident radiation is converted into electricity by the solar cell, and into heat by the absorber, which transfer the heat to the fluid flowing into a rectangular duct formed by the top absorber, and the back metallic plate supposed painted black. the cooling flu id is flowing under forced circulat ion mode. the conduct bottom is insulated in order to minimize heat losses with the amb ient. the inclination angle of the studied hybrid v/t solar collector is taken equal to the latitude of constantine east town in algeria. figure 1. a cross sect ional view of t he st udied hybrid p v/t solar collect or iii. mathematical modelling to e xa mine the pv/t performances, a transient mathe matica l model under forced convection was constructed. in order to write the energy balance between the components, it would be convenient to use the analogy between electricity and heat transfer. fig.1 shows the diffe rent heat transfer coeffic ients along various elements of the collector. it is necessary to make some assumptions to model the system considered, as:  the sky can be co mpared to a b lack body with equivalent calculated temperature.  the temperature of the soil is taken equal to the ambient temperature.  the physical proprieties of materials are assumed to be constant.  the wind is supposed blowing parallel to the faces of the system.  the fluid entering the duct is at room temperature, and the ducts flu id te mperature is a combination of the input and exit temperatures. the following are the energy balance equations for different surfaces of the pv/t collector:  glazing: 𝑚g𝑐g 𝑑𝑇g⁄ 𝑑𝑡) = 𝑃g𝐴g + ℎ𝑣g(𝑇𝑎 − 𝑇g)𝐴g + ℎ𝑟g(𝑇𝑠 −𝑇g)𝐴g + (ℎ𝑣𝑐 + ℎ𝑟𝑐)(𝑇𝑐−𝑇g)𝐴g (1) where mg, cg and 𝐴g denote the mass, specific heat and area of glass respectively, wh ile 𝑃g represents the rate of the energy absorbed by the glass, ℎ𝑣gand ℎ𝑟g are the heat transfer coeffic ients based on convection and radiation between the glazing and ambiance/sky respectively. on the other hand, ℎ𝑣𝑐is the convection heat transfer coeffic ient for air cavity between the solar cell and glazing, ℎ𝑟𝑐 is the heat transfer coeffic ient based on radiation between solar ce ll and gla zing. 𝑇g,𝑇𝑎 𝑇𝑠 and 𝑇𝑐 represent respectively temperatures of: glass, ambient, sky and pv cell and t represents the time. the a. ghellab et al ijeca-issn: 2543-3717. 5830 1 page 46 quantity of the energy absorbed by the glass is calculated by the following expression [28]: 𝑃g = 𝑃𝑑i𝑟 . 𝛼g−𝑑i𝑟 + 𝑃𝑑if . 𝛼g−𝑑if (2) 𝑁𝑢 = 1 + 1.446 *1 − 1708⁄ 𝑎 𝖥 𝑐𝑜𝑠 𝜃+ 1 i [ 1 such as pdir and pdif rep resents respect ive ly the intensity of the direct and diffuse incident radiation. the a b s o rp t i o n c o effi ci e n t s o f g l a zi n g 𝛼𝑉1−𝑑i𝑟 et 𝛼𝑉1−𝑑if are calculated from [28]. the coefficient of radiat ion heat transfer fro m the glazing to the sky is given by [29]: 1708[𝑠i𝑛( 1.8)] 1.6 𝑅𝑎 𝑐𝑜𝑠 𝜃 i ] + [( 𝑅𝑎 𝑐𝑜𝑠 𝜃⁄ ) 0.333 − 1] (8) where 𝑅𝑎represents the rayleigh number and 𝜃 is the h = 𝜎sg(𝑇4 − 𝑇4) (3) collector inclination angle, which can be calculated by 𝑟g g 𝑠 ⁄ (𝑇g − 𝑇𝑎) the following expression: 𝜌2 𝑐𝑝𝑔𝛽(𝑇𝑐 − 𝑇g)𝑏3 where 𝜎 is the stephan-boltzmann constant, sg is the 𝑅𝑎 = 𝑐⁄ 𝑎i𝑟𝜇 (9) emissivity of thermal rad iation of the glass cover, 𝑇g characterize the sky te mperature which is evaluated by swinbank (1963) as follows [29]: 𝑇𝑠 = 0.0552(𝑇𝑎)1.5 (4) the coefficient of convective heat transfer between the glazing and ambiance is formulated by mc adams where ρ, cp, β and μ are respectively the density, specific heat, therma l e xpansion coeffic ient and the dynamic viscosity of air, and g is the gravitational constant.  solar cell: 𝑚 𝑐 ( 𝑑𝑇𝑐⁄ ) = 𝑃 . 𝐴 + (ℎ ℎ )(𝑇 − 𝑇 )𝐴 (1954) [29]: 𝑐 𝑐 𝑑𝑡 𝑐 𝑐 𝑣𝑐+ 𝑟𝑐 g 𝑐 g h𝑣g = 5.7 + 3.8. 𝑣 (5) where v represents the wind velocity. the coeffic ient of radiation heat transfer between solar cell and glazing can be calculated fro m the following equation: + ℎ𝑐𝑐(𝑇𝑝 − 𝑇𝑐)𝐴𝑐 − 𝑄𝑒𝑙𝑒 . 𝐴𝑐 (10) where mc, cc and 𝐴𝑐 represents respectively the mass, specific heat and area of the solar cell, 𝑃𝑐 represents the rate of the energy absorbed by the pv h = 𝜎(𝑇𝑐 + 𝑇g)(𝑇2 + 𝑇2) (6) cell, ℎ𝑐𝑐 is the heat transfer coefficient conduction 𝑟𝑐 𝑐 g ⁄ ( ⁄s𝑐 + 1⁄sg − 1) between the pv cell and the absorber plate and 𝑄𝑒𝑙𝑒is the electrical power produced by the pv module. 𝑇𝑐 note that the symbol s𝑐 represents the emissivity of the solar cell. the coefficient of convection heat transfer for air cavity between the solar cell and glazing, is given by : represents the pv cell te mpe rature and 𝑇𝑝 represents the absorbing plate te mperature. the rate of solar energy received by solar cell a fter transmission is calculated by the following expression [30]: h𝑣𝑐 = 𝑁𝑢. 𝑘𝑎i𝑟⁄𝐷 (7) 𝑃𝑐 = 𝑟g × 𝛼𝑐 × 𝛽𝑐 × 𝑃g (11) w h er e n u r ep r es en t s t h e nu s s el t n u m b e r, ka ir i s t h e air conductivity and dh represents the hydraulic dia mete r of the air flowing in the channel. the nusselt number can be calculated by the convection between inclined parallel flat plates [29]: where 𝛼𝑐 is the absorption coefficient of the cell and 𝛽𝑐 is the pac king factor which represent the ratio of cell a rea to aperture area. while the rate o f e lectrica l energy generated by the pv cell can be calculated by [30]: 𝑄𝑒𝑙𝑒 = 5𝑒𝑙𝑒 × 𝑃g × 𝛽𝑐 × 𝑟g (12) where 5𝑒𝑙𝑒 design the electrical efficiency generated by the cell, which is estimated by the relation (3 8 ) and 𝑟g is the transmission coefficient of the glass. the heat transfer coefficient conduction between the pv cell and the absorber is calculated by: 𝑅 ⁄ 𝑘 ℎ − a. ghellab et al ijeca-issn: 2543-3717. 1 ( page 47 h𝑐𝑐 = 𝑘𝑐⁄𝑒 + 𝑘𝑝 ⁄𝑒 (13) 𝑚𝑏𝑝𝑐𝑏𝑝 ( 𝑑𝑇𝑏𝑝⁄ 𝑑𝑡) k , k and 𝑒 , e are respectively the thermal = h𝑣𝑏𝑝(𝑇f − 𝑇𝑏𝑝)𝐴𝑏𝑝 + (ℎ𝑐i + ℎ𝑣𝑎)(𝑇𝑎 − 𝑇𝑏𝑝)𝐴𝑏𝑝 c p 𝑐 p + h (𝑇 − 𝑇 )𝐴 conductivity and the thickness of pv cell and absorbing 𝑟𝑝 𝑝 𝑏𝑝 𝑏𝑝 plate.  absorbing plate: 𝑚𝑝 𝑐𝑝 𝑑𝑇𝑝⁄ 𝑑𝑡) = ℎ𝑐𝑐(𝑇𝑐 − 𝑇𝑝)𝐴𝑐 + ℎ𝑣𝑝(𝑇f − 𝑇𝑝)𝐴𝑝 + 𝐴𝑏𝑝ℎ𝑟𝑎(𝑇𝑠𝑜i𝑙 − 𝑇𝑏𝑝) (18) where mbp, cbp and 𝐴𝑏𝑝 represents respectively the mass, specific heat and area of the back plate, ℎ𝑐i is the + ℎ𝑟𝑝(𝑇𝑏𝑝 − 𝑇𝑝)𝐴𝑝 + 𝐴𝑝𝑃𝑝 (14) where mp, cp and 𝐴𝑝 represents respectively the mass, specific heat and area of the absorber plate, 𝑃𝑝 represents the rate of the energy absorbed by the absorbing plate, ℎ𝑣𝑝 is the heat transfer coefficient heat transfer conduction coefficient in the insulation, ℎ𝑟𝑎 is the radiation heat transfer coefficient fro m the back plate and soil, ℎ𝑣𝑎 is the convective heat transfer coefficient for air cavity between the back plate and soil. 𝑇𝑠𝑜i𝑙 represents the temperature of the soil. the heat transfer coefficient by conduction in the insulation can be obtained by: convection between the absorber plate and the fluid, h𝑐i = 𝑘i⁄𝑒 + 𝑘𝑏𝑝⁄𝑒 (19) ℎ𝑟𝑝is the heat transfer coefficient by radiation between t h e ab s o r b er a n d b a c k p l at e. 𝑇f an d 𝑇𝑏𝑝 rep resent the temperatures of flu id and back p late respectively. 𝑃𝑝 is the rate of solar energy absorbed by the absorbing plate, which is calculated by: 𝑃𝑝 = 𝑟g × (1 − 𝛽𝑐) × 𝛼𝑐 × 𝑃g (15) i 𝑏𝑝 with k i, k bp and ei, ebp are respectively the insulating and back plate thermal conductivity and thickness. the radiation heat coefficient between back plate and soil is calculated by: h𝑟𝑎 = 𝜎s𝑏𝑝(𝑇𝑠𝑜i𝑙 + 𝑇𝑏𝑝)(𝑇2 + 𝑇2 ) (20) the heat transfer coefficient by radiation between the 𝑠𝑜i𝑙 𝑏𝑝 absorber and back plate can be given as [29]: h𝑟𝑝 = 𝜎(𝑇𝑝 + 𝑇𝑏𝑝)(𝑇2 + 𝑇2 ) the convective heat coefficient between back plate and soil 𝐻𝑣𝑎 can be taken the same as 𝐻𝑣g. 𝑝 𝑏𝑝 ⁄ ( ⁄s𝑏𝑝 + 1⁄s𝑝 − 1) (16) iii. 1 . expression of convective heat transfer coefficients where s𝑏𝑝 and s𝑝 are respectively the back plate and the absorber coefficients of emissivity. for convective e xchange between two meta llic plates and the fluid inside the duct, the heat transfer coeffic ient can be calculated by:  fluid flowing in the duct: 𝑚f 𝑐f ( 𝑑𝑇f⁄ 𝑑𝑡) = ℎ𝑣𝑝(𝑇𝑝 − 𝑇f )𝐴f h𝑣𝑝 = h𝑣i = 𝑁𝑢 𝑘f⁄ 𝐷 (21) + ℎ𝑣𝑏𝑝(𝑇𝑏𝑝 − 𝑇f ) 𝐴f − 𝑚 𝑐f (𝑇𝑜𝑢𝑡 − 𝑇i𝑛 )𝐴f (17) w h e r e mf , cf an d 𝐴f re p r es e n t s t h e m a s s , s p e ci fi c h e at and area of the fluid respectively, ℎ𝑣𝑏𝑝 is the heat transfer coefficient convection between the fluid and the back plate, 𝑇i𝑛 and 𝑇𝑜𝑢𝑡 represent respectively the inlet and the outlet temperatures of the fluid in the duct, 𝑚 is the mass flow rate of the primary cooling fluid. where kf is the flu id therma l conductivity, nu is the nusselt number for forced convection in the duct formed by the absorbed plate and the back plate. according to the literature analysis, this number can be e xpressed for different fluid examined in this work as:  for air: according to [29] and [31], the corre lation of tan and charters (1970) is reco mmended for pa rallel flat plate and nusselt number can be expressed by: 𝑁𝑢𝑎i𝑟 = 0.018 𝑅𝑒0.8 𝑃𝑟0.4 (22)  back plate: 𝑎i𝑟 𝑎i𝑟 𝑐 𝑝 ℎ a. ghellab et al ijeca-issn: 2543-3717. f page 48 where prair is the prandtl number of air, reair is the reynolds number of air defined as:  viscosity 𝜇w𝑎𝑡𝑒𝑟 = 2.1897 exp(−1 1) 𝑇f 4 − 3.055 exp(−8) 𝑇f 3 + 𝑅𝑒𝑎i𝑟 = 𝜌 𝑣 . 𝐷ℎ⁄𝜇 (23) 1.6028 exp (−5) 𝑇f 2 ) − 0.00375 24 𝑇f + 0.33158 (30)  density in which ρ and μ represent the density and the dynamic viscosity of air, v is the mean velocity of air in the duct.  for water: refe rring to [32], the nus selt number of pure water for turbulent flow in two para lle l plates, can be calculated by the following corre lation over the we ll known equation of dittus -boelter: 𝑁𝑢 w𝑎𝑡𝑒𝑟 = 0.023 𝑅𝑒0.8 𝑃𝑟0.33 (24) 𝜌w𝑎𝑡𝑒𝑟 = −1.5629 exp(−5) 𝑇f 3 + 0.01177 8 𝑇f 2 − 3.0726 𝑇f + 1227.8 (31)  thermal conductivity 𝑘w𝑎𝑡𝑒𝑟 = 1.5362 exp(−8) 𝑇f 3 − 2.261 exp(−5) 𝑇f 2 + 0.010879 𝑇f − 1.0294 (32)  specific heat 𝑐𝑝,w𝑎𝑡𝑒𝑟 = 1.1105 exp( −5) 𝑇f 3 − 0.0031 0 𝑇f 2 w 𝑎𝑡𝑒𝑟 w 𝑎𝑡𝑒𝑟 − 1.478 𝑇f where prwater is the prandtl number of water, rewater is the reynolds number of water.  for nanofluid: according to [27, 33], the following correlat ion has been created to determine the nusselt number in terms of reynolds and prandtl nu mbers [16], of turbulent flo w in tube using al2o3 – water mixture under a uniform heat flux boundary condition on its wall. 𝑁𝑢𝑛f = 0.085 𝑅𝑒 0.71 𝑃𝑟0.35 (25) + 4631.9 (33)  for nanofluid: fro m literature, the physical proprieties of nanofluids depend on parameters including the therma l propriet ies of the water as base fluid and the volume fraction of alu minu m o xides (al2 o3) nanoparticles dispersed in water. based on the report [27], the eqs (34) and (35) are general relationships used to compute specific heat and the density for a classical two-phase mixture. the 𝑛f 𝑛f specific heat of the al2o3-water nanofluid can be for 6.6 ≤ prnf ≤13.9, 10 4 ≤ renf ≤ 5.10 5 and 0< φ <10 % where prnf , renf represent the prandtl and the reynolds number of the nanofluid and φ represents the volu m e fracti o n of al2 o3 nan o p a rt i cl es . iii. 2 . expression of thermo-physical properties  for air: according to [29], the physical properties of air are assumed varying with temperature, as follows:  viscosity 𝜇𝑎i𝑟 = [1.983 + 0.00184(𝑇f − 27)]10−5 (26)  density 𝜌𝑎i𝑟 = 1.1774 − 0.00359(𝑇f − 27) (27)  thermal conductivity 𝑘𝑎i𝑟 = 0.02624 + 0.0000758(𝑇f − 27) (28)  specific heat 𝑐𝑝,𝑎i𝑟 = 1.0057 + 0.000066(𝑇f − 27) (29)  for water: the equations of the physical propriet ies of water are obtained from the equations provided in the study by jayakumar et al [34], as: calculated by [27]: 𝑐𝑝,𝑛f = (1 − 𝜑)𝑐𝑝,w 𝑎𝑡𝑒𝑟 + 𝜑𝑐𝑝,𝑛𝑝 (34) where cp,nf, cp,water and cp,np represent respectively the specific heat of nanofluid, base fluid and nanoparticle. the nanoflu id density is calcu lated by the following relation [27]: 𝜌𝑛f = (1 − 𝜑)𝜌w𝑎𝑡𝑒𝑟 + 𝜑𝜌𝑛𝑝 (35) where ρnf, ρwater and ρnp represent respectively the density of nanofluid, base fluid and nanoparticle. they e xist several semi-e mpirica l corre lations for calculating therma l conductivity and the dynamic viscosity. recent models have shown that numerica l simu lations for v iscosity and thermal conductivity require more robust models that account for temperature dependency and nanoparticle size. these correlations include te mperature and volu me fraction [26, 35] in the eq (36) which represents the modified statement of nguen: 𝜇𝑛𝑝 = 𝑒𝑥𝑝(3.00 3 − 0.0420 3𝑇f − 0.5445𝜑 + 0.0002553𝑇2 − 0.0534𝜑2 − 1.622𝜑−1 (36) a. ghellab et al ijeca-issn: 2543-3717. ⁄ 𝐴 𝑃 𝑑𝑡 page 49 regarding the nanoflu id therma l conductivity, and according to maiga[27], this para meter can be calcu lated using the eq (37), this model has been used in this study because of his simplicity: coeffic ients which related with the input physical parameters. this equation system is solved by the iterative guass -siedel method, which allowed evaluating the unknowns for each time and for each component. for 𝑘𝑛f⁄ w 𝑎𝑡𝑒𝑟 k , k = 4.97𝜑2 + 2072𝜑 (37) represents respectively the thermal numerical ca lculat ion, a computer progra m was prepared in matlab language. first, init ial guessed temperatures are used equal to ambient te mperature in order to calculate the heat transfer coefficient, which can be used nf water conductivity of nanofluid, base fluid. iii. 3 . expression of efficiencies the e xpression of the electrical effic iency generated by the cell is: 5𝑒𝑙𝑒 = 5𝑟𝑒f [1 − 𝛽𝑟 (𝑇𝑐 − 𝑇𝑟 )] (38) w h e r e 5𝑟𝑒f i s t h e r ef er en c e c el l effi cien cy at operat ing te mp eratu re tr o f 25 °c, and 𝛽𝑟 is the coeffic ient o f t e mp erature and th ese pa ra mete rs are given by manufacturer [30]. the instantaneous pv/t collector therma l e ffic iency of can be e xp ressed by the heat ratio quantity e xtracted by the fluid used to the amount of solar radiation incident on the glazing [28]: to estimate (tg, tc, tp, tf and tbp), then the values obtained are reinserted to calculate new temperatures of various elements. if all new values are larger than 0.01% fro m their guessed temperature, the process is repeated until the solution converges. v. results and discussion v. 1 . validation results  air as working fluid the values of the thermo-physical para meters for various surfaces of the system wh ich have been used to validate the model a re found fro m literature [5], [11], and [36]. the re levant parameters used for numerica l calculations are listed in table 1. the electrical efficiency is calculated by eq. (38), and the following η 𝑡ℎ = ∫ 𝑚 𝑐f (𝑇𝑜𝑢𝑡 − 𝑇i𝑛 )𝑑𝑡 ∫ g ( 39) values were e xperimentally validated according to [5]: βr=0.004 k -1 , ηref=12.5% . both the absorber plate and the back plate are in cooper and the values of emissivity and the overall effic iency of the p v/t solar collector is computed by adding the therma l effic iency equivalent of electrical efficiency and the thermal efficiency [30]: and thickness of the back plate are taken as: εbp=0.9 and ebp= 3mm [5]. 5 = (5𝑒𝑙𝑒⁄ ) + 5 (4 0) t able 1. main parameters used in simulat ion [5, 11 and 36]. 𝑜𝑣𝑒𝑟𝑎𝑙𝑙 𝑐f 𝑡ℎ wh e re 𝑐f is the con v e rs i o n fact o r of the therm a l power plant, its value can be taken as 0.4 [30]. iv. method of resolution based on the finite diffe rence formulat ion, the temperature d istribution can be determined by a system of linear a lgebraic equations, these systems can be written as a matrix equation as follows [31]: 𝐴 (5, 5) × 𝑇 (5) = 𝐵 (5) (41) where a (d imension: 5) represents a square mat rix, such its ele ments jo in the known therma l capacities of materia ls with the different heat e xchange coeffic ients between pv/t collector e le ments, t (5) is a vector containing system of the unknown’s te mperatures at the nodes and the vector b (5) which jo in the constants, thermal capacities of materials with the heat exchange first, the program was operated on a panel with a rea of 9 m 2 the input data collected of the pv/t air collector model ii fro m the co mparative study [5], in his study this model represented the highest thermal efficiency values. 𝑘 parameters gl azing pv ce l ls absorbi ng pl ate in su lation absorption coe fficient (-) αg=0.04 αc=0.9 αp=0.94 tran smission coe fficient (-) τg=0.9 emi ssivi ty (-) εg=0.86 εc=0.7 εp=0.95 th i ck ness (mm) eg= 3 ec= 0.22 ep= 3 ei=50 th e rmal con du ctivity (w.m -1 .k -1 ) kg= 1.8 kc= 130 kp= 386 ki= 0.045 de n sity(kg.m -3 ) ρg= 2700 ρc= 2330 ρp= 8954 s pe cifi c h e at capaci ty (j.kg 1.k-1) cg=750 cc=836 cp=0.383 a. ghellab et al ijeca-issn: 2543-3717. page 50 figure 2 illustrates the comparison of the thermal efficiency of the present numerica l code with the thermal efficiency available in the study [5], the figure represents the variation of performances as a function of the air mass flow rate wh ich spanning the range of 0.005-0.04 kg/s.m 2 . the results obtained are in good agreement with those reported by [5]. the results of the present study predict the therma l effic iency within a re lative error of ±2% which may co me fro m ma king hypotheses and uncertainties in the correlations used in the mathematical analysis. figure 2. comparison bet ween t he present work and t hose of hegazy v. 2 . evolution of solar radiation intensity and ambient temperature the follo wing performance evaluation have been carried out for meteorologica l data wh ich concern constantine town in east algeria (36°70’, 6°37’), for the typical summe r day 30 july 2015, and during which the prevailing ma xima l and min ima l te mperatures are respectively equal to 43°c and 22°c, according to [37]. the calculat ion of the d ifferent para meters is during the sunshine and the collector represents an area of 1m long by 1 m wide and the wind speed was taken equal to 0.5m/s. figure 3 represents the variation of solar radiation and ambient temperature of the typical day on hourly basis. it can be seen that the radiation varies fro m a min imu m value of 290.206 w/ m 2 at 8:00h and 17:00h to a maximu m value of 920.88 w/m 2 at 13:00h. figure 3. hourly variation of solar intensity and ambient temperature of t he t ypical day v. 3 . comparative results the proprieties of the conventional working fluid, a re evaluated as a function of temperature by using equations: eqs (26)-(29) for a ir and eqs (30) -(33) for water. however, the proprieties of the alu mina nanofluid are simulated by using eqs (34)-(37) at different temperatures using 2% as a volu me fract ion of al2o3 nanoparticles in the base fluid that is water. figure 4 shows the effect of mass flo w rate on the therma l e ffic iency of the pv/t system. it is observed that the therma l effic iency increases with the increase of the mass flow rate and the results illustrates that the therma l efficiency of nanofluid is the highest comparing with those of water and a ir, since the increase in the mass flo w rate, enhance the convection heat transfer fro m the absorbing plate to the flowing flu id and leads to reduce the thermal losses fro m the absorbing plate to ambiance. these results are agrees well with [5], [15] and [23]. figure 4. variat ion of t hermal efficiency wit h mass flow rat e for: air, wat er and alumina nanofluid a. ghellab et al ijeca-issn: 2543-3717. page 51 figure 5 shows the hourly variation of the outlet temperature of three different working flu ids, wh ich were : a ir, water and a lu mina nanofluid. the outlet temperature o f d ifferent flu ids increases with local time as radiation increases and present their ma ximu m at 13:00h, because the solar radiat ion is collected on the absorbing plate then transferred to the working fluid and it can be seen that the outlet temperature of the alumina nanofluid presents the highest temperature with a significant diffe rence co mpared with those of water and air. whereas, the ma ximu m outlet te mperature of nanofluid is 3.72°c higher than water and 11.77°c more than air. figure 5. comparison between the simulated outlet temperatures of different working fluids: air, wat er and alumina nanofluid figure 6 represents the variation with time of the rate of heat extracted by the fluid when the mass flow rate is taken equal to 0.04kg/s. the results of this figure indicate that the quantity of heat extracted by the nanofluid is higher than the other two fluids, because the presence of al2 o3 nanoparticles in the nanofluid enhances its therma l conductivity and density than water and air, which imp roves the heat transfer coefficient fro m the absorber plate to the flowing fluid. these results are in good agreement with that reported in literature. values of the heat extracted by working fluid is substituted in eq (3 9 ) to calculate the therma l effic iency which is function of the specific heat and mass flow rates of the three working fluids, because of the highest values of the outlet temperature of nanofluid, it ’s re ma rkab le in figure 7 that the therma l effic iency of the nanofluid beco mes higher compared to other two fluids. the ma ximu m values of therma l effic iency are found to be: 73.28%, 67.67% and 41.55%, of nanofluid, water and a ir, respectively. it’s re markable in figure 8 that the temperature of the cell when the nanofluid is flowing is relatively lower than those of other fluids, this has a direct impact on the electrical efficiency, so it is clear in figure 6. hourly variation of heat gain of t hree fluids: air, wat er and alumina nanofluid figure 7. hourly variation of thermal efficiency for t he t hree working fluids figure 8. hourly variation of pv cell t emperature for the t hree cooling fluids a. ghellab et al ijeca-issn: 2543-3717. page 52 figure 9 that this fluid represents the best electrical efficiency compa ring to those of water and air because the increase in te mperature of the ce ll causes the decrease in electrical effic iency. it is noted from results of figure 7 and figure 9 that the therma l efficiency rises when operating temperature increases but in the same time the electrica l efficiency decreases, this conflict impose to calculate the overall effic iency using eq (40) in order to determine which flu ids represents the best performances of the pv/t system, the sa me co mment was established by [5], [8] and [30], so the figure 10 e xh ibits the evolution of the overa ll efficiency of the panel for the three fluids and it can be seen from results that the overall effic iency of alu mina nanofluids is h igher by about 6.15 % and 33.9 % than water and a ir, respectively, because nanoparticles give the nanofluids the highest density and lower specific heat and according to [15] less heat is required to raise the temperature of the nanofluid and thus ma king the output temperature and e fficiency becomes higher. figure 9. elect rical efficiency variation wit h t he t hree st udied fluids figure 10. hourly variation t he overall efficiency of t he t hree working fluids vi. conclusion according to the theoretical results obtained from the numerical calcu lation of the performances of a hybrid photovoltaic/thermal (pv/t) solar collector, using three diffe rent cooling flu ids: alu mina nanoflu id, water and air, the following conclusions have been drawn:  the model was validated and the results obtained are in good agree ment with those reported by literature.  the increase in mass flow rate e xtending over the range: 0.005-0.04 kg/s, leads to raise the efficiencies by decreasing the heat losses from absorbing plates to the ambiance.  the outlet te mperature of the system using nanofluid is higher than the two other systems using water and air.  the results show that using nanofluid as cooling flu id, the electrica l e fficiency increases due to the decrease of the temperature of the pv cell.  the hybrid (pv/t) system using alumina nanofluid presents the highest therma l effic iency, compared to the system using water and air as working fluids, respectively (73.28%, 67.67% and 41.55%).  the overall effic iency of the system using nanofluid (99.21% ) is higher than water (93.06%) and air (65.31%), because the presence of nanop articles in water increases the thermal proprieties of this fluid. nomenclature 𝐴: t he area of t he component of the syst em, m 2 cp : t he specific heat of the component of the syst em, j/kg .k dh : hydraulic diamet er, m e: t he t hickness of t he component , m ℎ𝑣g is t he convective heat t ransfer coefficient bet ween the glazing and ambiance, w/m 2 .k ℎ𝑟g is t he radiat ion heat t ransfer coefficient from t he glazing t o t he sky, w/m 2 .k ℎ𝑣𝑐 is t he convection heat transfer coefficient for air cavity bet ween t he solar cell and glazing, w/m 2 .k ℎ𝑟𝑐 is t he radiat ion heat t ransfer coefficient bet ween solar cell and glazing, w/m 2 .k ℎ𝑐𝑐 is t he heat t ransfer coefficient conduction bet ween t he pv cell and t he absorber plate, w/m 2 .k ℎ𝑣𝑝 is t he heat t ransfer coefficient convection bet ween t he absorber plat e and t he fluid, w/m 2 .k ℎ𝑟𝑝is t he heat t ransfer coefficient by radiat ion bet ween t he absorber and back plat e, w/m 2 .k ℎ𝑣𝑏𝑝 is t he heat t ransfer coefficient convection between t he fluid and t he back plate, w/m 2 .k ℎ𝑐i is t he heat t ransfer conduct ion coefficient in t he insulation, w/m 2 .k ℎ𝑟𝑎 is t he radiat ion heat t ransfer coefficient from t he back plate and soil, w/m 2 .k ℎ𝑣𝑎 is t he convective heat t ransfer coefficient for air cavity bet ween t he back plate and soil, w/m 2 .k a. ghellab et al ijeca-issn: 2543-3717. page 53 𝑄𝑒𝑙𝑒is t he elect rical power produced by t he p v module, w/m 2 g:t he gravit ational constant, m 2 /s. k: t hermal conduct ivity w/m.k m : t he mass of t he component of t he system, kg 𝑚 is t he mass flow rate of the fluid, kg/s nu represents t he nusselt number p : t he energy absorbed by t he component of the system, w/m 2 pdir and pdif represents respectively t he intensit y of t he direct and diffuse incident radiation, w/m 2 𝑅𝑎represents the rayleigh number t : t emperature, k, °c t : t ime, hr v t he wind velocity, m/s index a: ambient air: air bp: back plate c: p v cell f : fluid g: glass i: insolat ing in: inlet nf: nanofluid out : out let p: absorbing plate. s: sky soil: soil wat er: wat er grec s ymbols 𝛼𝑉1−𝑑i𝑟 et 𝛼𝑉1−𝑑if : t he absorption coefficients of glazing 𝜎 is t he st ephan-boltzmann constant, σ = 5.67×10 −8 w⋅m −2 ⋅k −4 s is t he emissivity of thermal radiation of the component. 𝜃 : t he collector inclination angle, ° ρ : t he densit y, kg/ m 3 β : t hermal expansion coefficient, 1/k 𝛽𝑐 is t he p acking factor 𝛽𝑟 is t he t emperature coefficient μ : t he dynamic viscosity φ : volume fraction of al2 o3 nanoparticules 5𝑒𝑙𝑒 design t he elect rical efficiency generated by the cell, % 5𝑟𝑒f is t he reference cell efficiency, % 5𝑡ℎt he instantaneous t hermal efficiency of t he p v/t collector, % 5𝑜𝑣𝑒𝑟𝑎𝑙𝑙 t he overall efficiency of t he p v/t solar collector, % references [1] a. ibrahim, m .y. othman, m .h. ruslan, s. m at, k. sop ian. “recent advances in flat p late p hotovoltaic/thermal (pv/t) solar collectors”, renewable and sustainable en er gy reviews, vol. 15, 2011, p p . 352 365. [2] f. hussain, m .y. h. othman, k. sop ian, b. yatim, h. ruslan, h. othman. “design dev elop ment and p erformance evaluation of p hotovoltaic/ thermal (pv/t) air base solar collector”, renewab le and sustainable energy reviews, vol. 25, 2013, p p . 431-441. [3] j. prakash. “transient analy sis of a p hotovoltaic/ thermal solar collector for co-generation of electricity and hot air/water,” ener gy conversion and m anagement, 1994, vol. 35, p p . 967-972. [4] k. sop ian, k. s. yigit, h. t. liu, s.kakaç , t.n. veziro glu. “performan ce analy sis of p hotovoltaic thermal air heaters,” en er gy conversion and m anagement, 1996, vol. 37, p p . 1657-1670. [5] a. hegazy . “comp arative study of the p erformances of four p hotovoltaic/thermal solar air sy stem,” ener gy conversion and m anagement, 2000, vol. 41, p p . 861-881. [6] h.a.zondag, d.w de vries , w.g.j.van .helden, r.j.c. van zolingen, a.a. van steenhoven. “ the yield of different combined p v-themal collector designs,” solar energy 2003, vol. 74, pp. 253-269. [7] t. t. chow. “performance analy sis of p hotovoltaic thermal collector by exp licit dy namic model, ” so lar energy , 2003, vol. 75, p p . 143-152. [8] j. k. tonui, y.trip anagnostop oulos. “air-cooled pv/t solar co llectors with low cost p erformance imp rovements,” solar energy , 2007, vol. 81, p p . 498-511. [9] y. trip anagnostop oulos. “asp ects and imp rovements of hy brid p hotovoltaic/ thermal solar ener gy sy stems”, solar energy , 2007, vol. 81, p p . 1117-1131. [10] e. shojaeizadeh, f. vey si, t. yousefi, f. davodi. “an exp erimental investigation on the efficien cy of a flat-p late solar collector with binary working fluid: a case study of p ropy lene gly col (pg)-water,” exp erimental thermal and fluid science, 2014, vol. 53, p p . 218-226. [11] c. cristofari, g. notton, j. l. canaletti. “thermal behavior of a cop oly mer pv/th solar sy stem in low flow rate conditions”, solar ener gy , 2009, vol. 83, p p . 1123 1138. [12] r. kumar, m . a. rosen. “performance ev aluation of a double p ass pv/t solar air heater with and without fins,” app lied thermal en gineerin g, 2011, vo l. 31, p p . 1402 1410. [13] l. a. tagliafico, f. scarp a, m . d. rosa. “dy namic thermal models and cfd analy sis for flat p late thermal solar collectorsa review”, renewable and sustainable energy reviews, 2014, vol. 30, 526-537. [14] o. m ahian, a.kianifar , s.a.kalogirou, i. pop , s. wongwises. “a review of the ap p lications of nanofluids in solar ener gy ,” international journal of heat and m ass transfer, 2013, vol. 57, p p . 582-594. [15] m . faizal, r. saidur, s. m ekhilef, m .a.alim. “ener gy economic and env ironmental analy sis of metal o xides nanofluid for flat p late collector,” ener gy conversion and m anagement, 2013, vol. 76, p p . 162-168. [16] j. sarkar. “a critical r eview on convective heat transfer correlations of nanofluids,” renewab le and sustainable energy reviews, 2011, vol. 15, p p . 3271-3277. [17] l. godson, b. raja, d. m. lal, s. wongwises. “enhancement of heat transfer using nanofluidsan overview,” r enewable and sustainab le ener gy reviews, 2010, vol. 14, p p . 629-641. [18] xq. wang, a. s. m ujumdar. “a review on nanofluids p art1: theoretical and numerical investigations,” brazilian journal of chemical en gineerin g, 2008, vol. 25, p p . 613 630. a. ghellab et al ijeca-issn: 2543-3717. page 54 [19] y. xuan, q. li. “investigation on convective heat transfer and flow features of nanoflu ids,” journal of heat transfer, 2003, vol. 125, p p . 151-155. [20] r.s. vajjha, d.k. das. “a review and analy sis on influence of temp erature and concentration of nanofluids on thermop hy sical p rop erties, heat transfer and p ump ing p ower,” international journal of heat and m ass transfer, 2012, vol. 55, p p . 4063-4078. [21] r. kandasamy , i.m uhaimin, a.k.rosmila. “the p erformance ev aluation of unsteady mhd non-darcy nanofluid f low over a p orous wedge du e to renewable (solar) ener gy ,” renewable ener gy , 2014, vol. 64, p p . 1 9. [22] m . rostanami, s. f. hosseinizadeh, m . gorji, j. m. khodadadi. “numerical study of turbulent forced convection flow of nanof luids in a lon g horizontal duct considerin g var iable p rop erties,” international communications in heat and m ass transfer, 2010, vol. 37, p p . 1426-1431. [23] t. yousefi, f. vey si, e. sho jaeizadeh, s. zinadini. “an exp erimental investigation on the effect of al2o3 – h2o nanofluid on the efficiency of flat p late solar collectors,” renewable energy , 2012, vol. 39, p p . 293-298. [24] r. saidur, t. c. m eng, z. said, m . hasanuzzaman, a. kamy ar. “evaluation of the effect of nanofluid-based absorbers on direct solar collector,” international journal of heat and m ass transfer, 2012, vol. 55, p p . 5899-5907. [25] h. vishwanadula, e. c. nsofor. “studies on forced convection nanoflu id flow in cir cular conduits,” arpn journal of en gineer in g and ap p lied sciences, 2012, vo l. 7, p p . 371-376. [26] z. said, m .h.sajid, m .a.alim, r.saidur, n.a.rahim. “exp erimental investigation of the thermop hy sical p rop rieties of al2o3nanofluid and its effect on a f lat p late solar collector,” international communications in heat and m ass transfer, 2013, vol. 48, p p . 99-107. [27] s. e. b. m aiga, s. j. palm, c. t. nguy en, g. roy , n. galanis. “heat transfer enhancement by using nanoflu ids in forced convection flows,” international journal of heat and fluid flow, 2005, vol. 26, p p . 530-546. [28] j. a. duffie, w. a. beckman. “solar en gin eerin g of thermal processes,” john wiley & sons inc, new york, 1991. [29] k. s. ong. “thermal p erformance of solar air h eaters: m athematical model and solution p rocedure,” solar energy , 1995, vol. 55, p p . 93-109. [30] g. n. tiwari and swap nil dubey . “fundamentals of photovoltaic m odules and their app lications,” rsc energy series n° 2, 2010. [31] incrop era, dewitt, bergman, lavine. “fundamentals of heat and m ass transfer”, johns wiley & sons, 2006. [32] a. i. kudish, e. g. evseev, g. walter, t. leuk efeld. “simulation study of a solar collector with a selectively coated p oly meric double walled absorber p late,” ener gy conversion and m anagement, 2002, vol. 43, p p . 651-671. [33] s. e. b. m aiga, c. t. nguy en, n. galanis, g. roy . heat transfer behaviours of nanofluids in a uniformly heated tube,” sup er lattices and m icrostructures, 2004, vol. 35, p p . 543-557. [34] j.s. jay akumar, s.m . m ahajania, j.c. m andala, kannan n. iy er, p.k. vijay an. “cfd analy sis of single-p hase flows inside helically coiled tubes”, comp uters and chemical engineering, 2010, vol. 34, p p . 430–446. [35] e. abu-nada. “effects of variable viscosity and thermal conductivity of al2o3-water nanofluid on heat transfer enhancement in natural conve ction,” international journal of heat and fluid flow, 2009, vol. 30, p p . 679-690. [36] j.p. holman. “heat transfer,” m c graw-hill series in m echanical engineering, 2010. 10th edition. [37] http ://www.accuweather.com/fr/dz/constantine/ 10/01/22021 http://www.accuweather.com/fr/dz/constantine/ international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 41-45 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 41 effect of using sponge pieces in a solar still abdelkader bellila 1 , imad kemerchou 2* , ali sadoun 3 , zied driss 4 1 exact science faculty, university of el oued, algeria 2 applied science faculty, university of ouargla, algeria 3 applied microelectronics laboratory, university of sidi bel abbès, algeria 4 laboratory of electro-mechanic systems, national school of engineers of sfax, university of sfax, tunisia * corresponding author e-mail: kemerchou.imad@univ-ouargla.dz abstract – solar distillation is a very effective way to obtain pure water, especially in isolated areas where the water is infected or polluted to obtain drinking water. two conventional solar stills of the same size (0.5 x 0.5 m) were tested for 8 hours. one still is priced as an ssr reference still and the other still which contains pieces of sponge is ssm and that is the subject of our work. the results show that the use of sponge in winter improves the yield of 10 %. keywords: solar energy, solar distillation, affected water, groundwater. received: 12/05/2022 – revised 05/06/2022 – accepted: 22/06/2022 i. introduction currently in the world the back world on drinking water has become a problem, which is why governments are looking for simple and quick solutions to this problem. the treatment of polluted or salty groundwater by solar energy is a method widely used, especially in isolated areas. in its areas, note the installations of solar stills designed locally to have pure water [1-6]. scientists have taken up this problem and have focused their work on improving solar stills by many and different methods. since solar energy is the main factor to trigger loosening. studies have been done on the distribution of solar rays on the earth and takes as an example the studies that have targeted algeria [7-10]. the researchers' experiments have shown that the cooling of the glass cover leads to an improvement in the performance of the solar still, regardless of the method of cooling, whether by air or by water. [11-14]. they are also shown that the heating of the pond water results in an improvement in the output of the solar still . they are shown that the heating of the pond water also leads to an improvement of the output of the solar still. the conclusion of the studies is based on two main axes, the first axis is the cooling of the glass cover and the second axis is the heating of the pool water. but still there are studies that have been based on two axes at the same time. so studies have been focused on the glass cover either by cooling it, or varying the angle, or doubling the number of covers [1519]. most of the studies in the world concentrate on the heating of water and this by increasing the intensity of solar radiation by using interior or exterior refractors [2022], by the use of natural and industrial materials in the distiller in the purpose of increasing the pool water temperature [ 23-29]. phase change materials and nanofluids have been rapidly integrated into solar distillation given their physical properties which promote the evaporation of water from the pool. several experiments have been made and they have given encouraging results, although these materials are not always available in the markets of developing countries and more than that, they are expensive [30,31]. mailto:kemerchou.imad@univ-ouargla.dz a. bellila et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 41-45 page 42 this work consists of cutting pieces of sponge and placing them in the basin of a still in order to see the effect of this abundant material on the performance of a solar still. ii. material and method in the university of el oued which is located in the south east of algeria and in march 2022, an experiment was carried out to test two solar stills of the same size (05 x 05 m) in the same climatic conditions. the first ssr still is taken as a control or reference still and the second ssm still which contains pieces of sponge as shown in figure 1. figure 1. measurement system setting up iii. results and analysis iii.1. solar radiation and ambient temperature figure 2 represents the evolution of the solar radiation of the day on february 15, 2002 and that according to time. solar radiation is reported to be a major factor in solar distillation note that the radiation is still weak. its maximum value is 750 w/m 2 at 13:00h. we note that the ambient temperature is quite low, the maximum value being 17°c between 13:00h and 14:00h. figure 2. evolution of solar radiation and ambient temperature iii.2. internal glass temperature evolution figure 3 represents the variation of the temperature of the condenser, that is to say the glass cover (the inner face) and we notice that the two temperatures of the two stills are almost the same. this resemblance is due to the ambient temperature, because the glass cools quickly. the maximum value is noted at 13:00h and is the same for both distillers (35°c). figure 3. evolution of internal glass cover temperature iii.3. water temperature evolution figure 4 represents the variation in the temperature of the pool water of the two distillers as a function of time. we note that the temperature of the distiller modify ssm and higher than that of the ssr distiller and this throughout the experiment despite having the same maximum value 31°c at 14:00h. a. bellila et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 41-45 page 43 figure 4. water temperature evolution iii.4. pure water hourly output gradient temperature figure 5 represents the evolution of the temperature gradient between the water in the pool and the inner face of the glass. this factor is very important, whenever this value is large, its shows that the output is interesting. in figure 5, notice that the temperature gradient of ssm is higher than that of ssr still and this gives an idea about the output of the system. figure 6 clearly shows that the production of the modified ssm still is greater than that of the reference ssr still and this in each hour of measurement. the total amount recovered from the ssm distiller is 446ml while for ssr it is 422ml. figure 5. gradient temperature figure 6. evolution of hourly output iv. conclusion two solar stills of the same size were tested. one is taken as ssr reference and the other contains ssm sponge pieces. after 8 hours of experiment, the result shows that:  the temperature gradient of ssm still and greater than that of ssr.  the amount of water produced from ssm is 446 ml while for ssr is 422 ml.  the improvement rate is 10 %. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] a. khechekhouche, b. benhaoua, meh. attia, z. driss, a. manokar, "polluted groundwater treatment in southeastern algeria by solar distillation," algerian journal of environmental science and technology, vol. 6, 2020. [2] k.k. sadasivuni, h. panchal, a. awasthi, m., f.a. essa, s. shanmugan, m. suresh, v. priya, a. khechekhouche, "ground water treatment using solar radiationvaporization & condensation-techniques by solar desalination system, " international journal of ambient a. bellila et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 41-45 page 44 energy, 2020. https://doi.org/10.1080/01430750.2020.1772872 [3] h. panchal, k.k. sadasivuni, c. prajapati, m. khalid, f.a. essa, s. shanmugan, n. pandya, m. suresh, m. israr, s. dharaskar, a. khechekhouche, "productivity enhancement of solar still with thermoelectric modules from groundwater to produce potable water: a review, "groundwater for sustainable development, vol. 11, pp. 100429. 2020. https://doi.org/10.1016/j.gsd.2020.100429 [4] a. miloudi, a. khechekhouche, i. kermerchou, "pollution groundwater treatment by solar stills with palm fibers, " jp journal of heat and mass transfer, vol 27, pp. 1-12. 2022. [5] a. laaraba, a. khechekhouche, "numerical simulation of natural convection in the air gap of a vertical flat plat thermal solar collector with partitions attached to its glazing, " indonesian journal of science & technology, vol. 3, pp. 14-23, 2018. https://doi.org/10.17509/ijost.v3i2.12753 [6] a. khechekhouche, n. elsharif, i. kermerchou, a. sadoun,"construction and performance evaluation of a conventional solar distiller," heritage and sustainable development, vol. 1, pp. 72-77. 2019. doi: 10.37868/hsd.v1i2.3 [7] s. pahlavan, m. jahangiri, a. alidadi shamsabadi, a. khechekhouche, "feasibility study of solar water heaters in algeria, a review, " journal of solar energy research, vol 3, pp.135-146. 2018. [8] m. ghodbane, b. boumeddane, "estimating solar radiation according to the semiempirical approach of perrin de brichambaut: application on several areas with the different climate in algeria," international journal of eenergetica, vol.1, pp. 20-29. 2016. http://dx.doi.org/10.47238/ijeca.v1i1.12 [9] d. benatiallah, a. benatiallah, k. bouchouicha, b. nasri, "estimation of clear sky global solar radiation in algeria, " aims energy, vol. 7, pp. 710-727. 2019. [10] a. khechekhouche, b. boukhari, z. driss, n.e. benhissen, "seasonal effect on solar distillation in the eloued region of south-east algeria, " international journal of energetica, vol. 2, pp. 42-45. 2017. http://dx.doi.org/10.47238/ijeca.v2i1.27 [11] z.m. omara, a.s. abdullah, a.e. kabeel, f.a. essa, "the cooling techniques of the solar stills' glass covers – a review," renewable and sustainable energy reviews, vol.78, pp. 176-193, 2017. https://doi.org/10.1016/j.rser.2017.04.085 [12] a.e. kabeel, mohamed abdelgaied, "enhancement of pyramid-shaped solar stills performance using a high thermal conductivity absorber plate and cooling the glass cover, " renewable energy, vol. 146, pp. 769-775. 2020. https://doi.org/10.1016/j.renene.2019.07.020 [13] m.e.h. attia, a.e. kabeel, m. abdelgaied, a. bellila, "optimization of the hemispherical solar distiller performance assisted by high thermal conductivity metal trays incorporated with reflective mirrors, " environmental science and pollution research. 2022. https://doi.org/10.1007/s11356-022-18708-y. [14] b. souyei, a. khechekhouche, s. meneceur, "effect of comparison of a metal plate and a refractory plate on a sollar still, " jp journal of heat and mass transfer, vol 27, pp. 37-56. 2022. doi: 10.17654/0973576322022 [15] r. cherraye, b. bouchekima, d. bechki, h. bouguettaia, a. khechekhouche," the effect of tilt angle on solar still productivity at different seasons in arid conditions-south algeria," international journal of ambient energy. 2020. https://doi.org/10.1080/01430750.2020.1723689 [16] a. khechekhouche, m. manokar, r. sathyamurthy, f. essa, m. sadeghzadeh, a. issakhovm," energy, exergy analysis, and optimizations of collector cover thickness of a solar still in el oued climate, algeria," international journal of photoenergy. article id 6668325, 2021. https://doi.org/10.1155/2021/6668325 [17] a. khechekhouche, b. benhaoua, a. m. manokar, a. e. kabeel, r. sathyamurthy," exploitation of an insulated air chamber as a glazed cover of a conventional solar still," heat transfer asian research, vol. 48, pp. 1563-1574. 2019. https://doi.org/10.1002/htj.21446 [18] a. khechekhouche, z. driss, b. durakovic," effect of heat flow via glazing on the productivity of a solar still, " international journal of energetica, vol. 4, pp. 54-57. 2019. http://dx.doi.org/10.47238/ijeca.v4i2.109 [19] a. khechekhouche, b. ben haoua, z. driss,"solar distillation between a simple and double-glazing," revue de mécanique, vol. 2, 2017. [20] m.e.h. attia, a.e. kabeel, m. abdelgaied, a. bellila, "optimization of the hemispherical solar distiller performance assisted by high thermal conductivity metal trays incorporated with reflective mirrors, " environmental science and pollution research. 2022. https://doi.org/10.1007/s11356-022-18708-y. [21] b. souyei, a. khechekhouche, s. meneceur, "effect of comparison of a metal plate and a refractory plate on a sollar still, " jp journal of heat and mass transfer, vol 27, pp. 37-56. 2022. doi: 10.17654/0973576322022 [22] a. khechekhouche, a.e. kabeel, b. benhaoua, m.e. h. attia, emad m.s. el-said. "traditional solar distiller improvement by a single external refractor under the climatic conditions of the el oued region, algeria," desalination and water treatment. vol 117, pp. 23-28, 2020. https://doi.org/10.5004/dwt.2020.24832 [23] a.e. kabeel, m. abdelgaied, a. eisa, "enhancing the performance of single basin solar still using high thermal conductivity sensible storage materials, " journal of cleaner production, vol. 183, pp. 20-25. 2018. https://doi.org/10.1016/j.jclepro.2018.02.144 [24] m.e.a. ouar, m.h. sellami, s.e. meddour, o.b. mokrani, "brackish water desalination using black granite as heat storage medium under arid climatic conditions," desalination and water treatment, vol. 225, pp. 149–155. 2021. doi: 10.5004/dwt.2021.27204 [25] a. khechekhouche, b. benhaoua, m. manokar, r. sathyamurthy, a. kabeel, z. driss," sand dunes effect on the productivity of a single slope solar distiller," heat and mass transfer journal, vol. 56, pp. 1117-1126, 2020. https://doi.org/10.1016/j.gsd.2020.100429 https://doi.org/10.17509/ijost.v3i2.12753 https://doi.org/10.1016/j.rser.2017.04.085 https://doi.org/10.1016/j.renene.2019.07.020 https://doi.org/10.1007/s11356-022-18708-y https://doi.org/10.1155/2021/6668325 https://dx.doi.org/10.47238/ijeca.v4i2.109 https://doi.org/10.1007/s11356-022-18708-y https://doi.org/10.5004/dwt.2020.24832 https://doi.org/10.1016/j.jclepro.2018.02.144 a. bellila et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 41-45 page 45 https://doi.org/10.1007/s00231-019-02786-9 https://doi.org/10.1007/s00231-019-02786-9 [26] a. sadoun, a. khechekhouche, i. kemerchou, m. ghodbane, b. souyei, "impact of natural charcoal blocks on the solar still output, " heritage and sustainable development, vol. 4, pp.61-66, 2022. doi: 10.37868/hsd.v4i1.80 [27] i. kermerchou, i. mahdjoubi, c. kined, a. khechekhouche, a. bellila, g. e. devora isiordia. palm fibers effect on the performance of a conventional solar still, asean journal for science and engineering in materials, vol. 1, pp. 29-36, 2022. [28] a. bellila, a. khechekhouche, i. kermerchou, a. sadoun, a. m. de oliveira siqueira, n. smakdji," aluminum wastes effect on solar distillation, " asean journal for science and engineering in materials, vol 1. 2022. [29] a. khechekhouche, b. benhaoua, a. kabeel, m. attia, w m. el-maghlany," improvement of solar distiller productivity by a black metallic plate of zinc as a thermal storage material," journal of testing and evaluation, vol. 49, 2019. doi: 10.1520/jte20190119 [30] a.k. singh, d.b. singh, v.k. dwivedi, g.n. tiwari, a. gupta, "water purification using solar still with/without nano-fluid: a review," materials today: proceedings, vol. 21, pp. 1700-1706. 2020. https://doi.org/10.1016/j.matpr.2019.12.025 [31] t. arunkumar, h.w. lim, s.j. lee,"a review on efficiently integrated passive distillation systems for active solar steam evaporation," renewable and sustainable energy reviews, vol. 155, pp. 111894. 2022. https://doi.org/10.1016/j.rser.2021.111894 https://doi.org/10.1016/j.rser.2021.111894 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 6. issue 2. 2021 page 21-34 ijeca-issn: 2543-3717. december 2021 page 21 literature review: synthesis of cuo (copper oxide) nanoparticles for thermal energy storage clarysa satari, rahmi sabila sidqi, rian febriyana putra, silmi ridwan putri, asep bayu dani nandiyanto* departemen kimia, universitas pendidikan indonesia, jl. dr. setiabudi no 229, bandung 40154, jawa barat, indonesia email*: nandiyanto@upi.edu abstract – this paper aims to provide a discussion of the methods used in the synthesis of cuo nanoparticles. a review of the cuo nanoparticle synthesis method was carried out from 65 articles from 2000 to 2021. the cuo nanoparticle synthesis methods described in this paper are electrochemical, sonochemical, sol-gel, biogenic, green synthesis, and hydrothermal methods. each method used to synthesize cuo nanoparticles has advantages and disadvantages. based on their advantages, electrochemical, sonochemical, green synthesis, and biogenic methods are environmentally friendly methods. moreover, the hydrothermal and biogenic methods are simple methods with easy preparation. in its utilization, cuo nanoparticles can be used to divert heat energy. the addition of a volume of cuo nanoparticles into the nitrate salt can increase the thermal diffusivity and thermal conductivity used in solar power plants. among the methods described, the hydrothermal method is the most effective and efficient technique. this is because the method is simple (without using any surfactant template), easy to vary the temperature, reactant concentration, and time variables on the growth of nanostructures. this paper is expected to provide some considerations regarding the synthesis method of cuo nanoparticles that can be used on an industrial scale based on the advantages of each method. keywords: cuo nanoparticles; synthesis methods; literature review received: 11/07/2021 – accepted: 15/11/2021 i. introduction nanotechnology in indonesia has been developed since 2004. until now, indonesia has produced various nanotechnology-based products in various fields including agriculture, food, textile, automotive, household, oil, cosmetics, health, renewable energy, and other industries [1]. currently, many studies focused more on nanoparticle research. this is because nanoparticles have several advantages, namely cheap, high yield under mild reaction conditions, high surface area, being physically stable, and reducing reaction time [2]. one of the nanotechnology products in indonesia is cuo nanoparticles. cuo (copper oxide) nanoparticles are one of the transition metal oxide nanoparticles that have become highly desirable materials for many applications. metal oxides are generally characterized by a very wide bandgap [3] whereas cuo nanoparticles are p-type oxide semiconductors with a bandgap of 1.2 1.5 ev [4]. one of the uses of nanoparticles is in solar cells [3]. solar power or solar cells is one viable source of sustainable energy. however, like many renewable energy technologies, the self-conversion of solar energy suffers from shortages due to intermittent solar resources [5]. molten salt has potential as a heat transfer fluid (htf) and thermal storage in solar power plants. however, organic htf is very unstable at high temperatures. thus, the addition of cuo nanoparticles to it will increase the stability in the highly oxidative liquefaction of nitrate salts [6]. in addition, cuo nanoparticles have unique catalytic, optical, and electrical properties [7] the unique properties of these particles allow cuo nanoparticles to be applied in various fields [8], such as photocatalytic reactions [9-10], antibacterial activity [11-16], nonenzymatic glucose sensor [17], polymer solar cells[18], inertness sensor [19], oxide architectural pores [20] ammonia sensing [21], antifungal agents [22], and cuo nanoparticles are also used in dry cell batteries and animal feeding supplements to combat copper deficiency. the methods that can be used in the synthesis of cuo nanoparticles include electrochemical methods [12], sonochemistry [23], sol-gel [24], green synthesis [25], hydrothermal [26], and biogenic [27]. each method has its advantages and has different results so it is necessary to do a review. https://www.ijeca.info/ clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 22 therefore, the purpose of this paper is to provide a discussion of several methods of synthesizing cuo nanoparticles based on their advantages and disadvantages to obtain a more effective and efficient method of synthesizing cuo nanoparticles. this paper is expected to provide an overview of the manufacture of cuo nanoparticles and help provide some considerations to be applied on the industrial scale for the manufacture of cuo nanoparticles. several analysis methods were also added, including x-ray diffraction (xrd), scanning electron microscope (sem), transmission electron microscope (tem), fourier transform infra red (ft-ir), and so on. ii. study on methods in the synthesis of cuo (copper oxide) table 1 shows several methods of synthesizing cuo (copper oxide) nanoparticles along with their synthesis results, weaknesses, and strengths. methods that can be used to synthesize cuo nanoparticles are electrochemical, sonochemical, sol-gel, green synthesis, biogenic, and hydrothermal methods. table 1. methods in the synthesis of cuo nanoparticles ref material method result advantage disadvantages [12] copper sheet (anode), platinum sheet (cathode), tbab (electrolyte) electroche mical the absorption band of cuo nanoparticles is in the range of 550-600 nm. the copper particles show a height of about 570 nm. in the ir spectrum, the peak appears at 3298 cm-1. microstructure sem of the electrochemical reduction of copper oxide nanoparticles showing solid agglomeration. the shape is irregular with the non-uniform distribution. hrtem showed spherical cuo nanoparticles with a size of 5-10 nm and a monoclinic structure. environmentally friendly and efficient in providing new opportunities for the rapid screening of various metal nanoparticle syntheses as well as for the development of new drugs for materials scientists the reaction that occurs can cause a layer (double layer) attached to the outside of the electrode to increase the resistance that occurs and reduce the current. [23] cun2o6.3h2o and naoh sonochem istry cuo particles obtained by the reaction of fewer than 20 minutes have a particle size of 80 nm. meanwhile, the 30-minute reaction resulted in particle size of 45 nm. extended time will result in particle size which tends to increase. an increase in the calcination temperature leads to complete cuo crystallization, accompanying welldefined and uniform crystalline particles with a particle size of ~50-70 nm. environmentally friendly, easy to prepare at low temperatures, minimal by-products. uneven distribution of particles [24] glacial acetic acid andcucl2.2h2o sol-gel sem shows the heterogeneous distribution of the synthesized cuo nanoparticles. xrd pattern of cuo nanoparticles shows a single phase with a monoclinic structure the mole ratio controls the size of the cuo nanoparticles. the size of cuo nanoparticles is 16 nm. can be carried out at room temperature and accurately control chemical and physical characteristics. relatively long processing time. [25] ixora coccinea and cuso4.5h2o green synthesis mean size of cuo nanoparticles 300 nm (sem), 80-110 nm (tem) it was found that ultrasonication improves the distribution of nanoparticles in the liquid by preventing cluster formation. the green synthesis method is a biologically reliable process that has been established for the synthesis of cuo. nanoparticles. environmentally friendly, low cost, and non-toxic synthesis method, produces largescale nanoparticles. the raw materials are hard to find. [26] ethanol, naoh, and cu(ch3coo)2 hydrother mal the results showed that the cuo nanoparticle structure has a monoclinic structure with a single crystal phase. the structure and morphology of cuo nanocrystals can be controlled by changing the concentration of the reactants. the rate of heat degradation to methylene blue can reach 92.1%. simple (without using any surfactant template), it is easy to vary the variables of temperature, reactant concentration, and time on the growth of nanostructures. particle size and shape can be controlled. equipment costs are expensive, it is difficult to control the stoichiometry of the solution, hydrothermal slurries are corrosive, and the use of high-pressure vessels will be dangerous in the event of an accident. [27] young guava leaves, cu(ch3coo)2. h2o biogenic the particle size of cuo nanoparticles is 11.07 nm. cuo nanoparticles show excellent degradation efficiency for industrial dyes, namely nile blue (nb). as well as cuo catalysts were found to be reusable for photocatalytic dye degradation. simple, eco-friendly, and economical. difficult implementation on a large scale and the need in maintaining cell cultures, control size, shape, and crystallinity. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 23 iii. synthesis of cuo nanoparticles cuo nanoparticles can be synthesized by several methods. review is needed to compare which method is more effective and efficient. the review of the cuo nanoparticle synthesis method was carried out from 65 articles from 2000 to 2021. based on the synthesis method that has been reviewed, there are several kinds of nanoparticle synthesis methods, namely electrochemical, sonochemical, sol-gel, green synthesis, hydrothermal, biogenic. iv. result and discussion iv.1. electrochemical method the electrochemical method is one of the many available methods for synthesizing metal oxides in the nanodomain due to its simplicity, low-temperature operation, and commercial feasibility [28]. electrochemical is a method based on oxidationreduction (redox) reactions. electrochemical systems include electrochemical cells and electrochemical reactions [29]. the basic equipment of electrochemical is to use two electrodes and an electrolyte solution in the process. overall the electrochemical method uses two inexpensive electrodes. the bulk metal used as anode will be converted into a metal group which in this case is cu. tetrabutylammonium bromide (tbab) in the electrolyte is used as a stabilizer. the electrochemical method is a process in which bulk metal is oxidized at the anode and metal cations will migrate to the cathode resulting in reduction with the formation of metal or metal oxide in a zero oxidation state. agglomeration with the formation of unwanted metal powders is prevented by the presence of an ammonium stabilizer. the anode will dissolve slowly and lead to the formation of then passivation with active tbab [12]. the electrodes used in the synthesis of cuo nanoparticles are copper sheet (anode) and platinum sheet (cathode). the electrolyte used was 0.01 m tetrabutylammonium bromide (tbab) and acetonitrile in a ratio of 4:1. the current used is 6 ma/cm2. electrolysis is carried out in a nitrogen atmosphere. the resulting copper oxide nanoparticles will be dark brown [12]. the obtained nanoparticles must be characterized, this is to find out that the nanoparticles obtained are the desired cuo nanoparticles. the characterization of nanoparticles can be done using uv-visible [4, 12, 30], ft-ir spectrophotometer [7, 4, 31-32], xrd [4, 7, 10, 12], and sem [4, 10, 12]. uv-visible can be used to determine when the precursor turns into cuo nanoparticles. the maximum absorption bands reported are 550-600 nm [12] and 638-642 nm [4]. this absorption band is closely related to the surface plasmon resonance peak of cuo nanoparticles. the peaks of the ir spectrum that appeared were reported with different results from one researcher to another. the reported ir spectrum peak is 3424-3437 cm-1 which can be attributed to the hydroxyl group which is the hygroscopic nature of cuo nanoparticles [4]. the characteristics of cuo nanoparticles using an ft-ir spectrophotometer can be shown in figure 1. figure 1. (a) ir spectra pattern of cuo nanoparticles with tbab 0.01 m, (b) x-ray diffraction pattern of cuo nanoparticles using tbab [12]. the average particle size of the synthesized nanoparticles was characterized by xrd and tem. xrd results of cuo nanoparticles showed that the calculated average particle size was 5-10 nm [12]. figure 2 shows the hrtem results of cuo nanoparticles which are spherical and 5-10 nm in size [12]. other studies reported that the average particle size obtained was 5-30 nm [4, 31] and had a monoclinic structure [4, 12, 31]. these results were confirmed by xrd and tem. in addition, cuo nanoparticles measuring 4.0 nm have been reported to have been successfully synthesized [7]. the size and nanoparticles of copper oxide depend on several parameters used (electrode, electrolyte, temperature, electrolysis time, current, solution, and cell shape dimensions). figure 2. hrtem cuo nanoparticles are spherical and 5-10 nm in size [12]. the surface morphology of cuo nanoparticles was investigated using an sem. sem microstructure of electrochemical reduction derived from copper nanoparticles shows solid agglomeration [4,12]. sem microstructure of cuo nanoparticles is shown in figure 3. figure 3. sem of cuo nanoparticles covered with 0.01 m tbab [20]. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 24 the electrochemical method is an easy and less timeconsuming method with the highest nanoparticle purity [4]. in addition, the electrochemical process is environmentally friendly and provides new opportunities for the synthesis of metal nanoparticles. the electrochemical method is considered good for use as new drug development. although the electrochemical method has several advantages, this method also has several disadvantages, namely, the reaction that occurs can cause a layer (double layer) to be attached to the outside of the electrode so that it increases the resistance that occurs and reduces the current [12]. iv.2. sonochemical method sonochemistry is a method of synthesizing materials using sound energy to induce physical and chemical changes in a liquid medium. the chemical effect of ultrasound produces acoustic cavitation, which is the formation and growth of foam in the liquid. the frequency used in the sonochemical method is a frequency in the range of 20 khz 2 mhz [29]. the basic principle of the sonochemical method is the displacement of sound waves that form and collapse the bubbles resulting in a local increase in temperature and pressure, causing physical and chemical changes in the material [33]. the schematic of the equipment used in the sonochemical method is shown in figure 4. figure 4. schematic of sonochemical method equipment [29]. the materials used in the synthesis of cuo nanoparticles by sonochemical methods are copper nitrate trihydrate (cun2o6.3h2o) and sodium hydroxide (naoh) with polyvinyl as the initial precursor [23]. synthesis of cuo nanoparticles begins by dissolving naoh in deionized water. the resulting solution is then added to cun2o6.3h2o for 30 minutes slowly drop by drop. sonication was carried out with the vcx 750 model. several other researchers used different models in sonication such as the branson 102c [33] and the ultrasound-assisted chemical reduction model uc-20a [8]. sonication is carried out until the desired product is completely precipitated. the precipitated product was then calcined at different temperatures in the range of 400-700 oc for 2 hours. the thermal behavior of the product was investigated by thermogravimetry (tg) powder in the open air with the heating rate used was 10 oc/min [23]. characterization is done through several instruments. to characterize the structural and microstructural properties of cuo nanoparticles an x-ray diffractometer was used which in this synthesis used panalytical x'pert pro mpd with radiation used was cu-kα operating at 40 kv and 30 ma, respectively. the sem (scanning electron microscope) used is the jeol jsm-6510 model [23]. thermo-gravimetric and thermal-differential analysis of cuo nanoparticles were sonicated for 30 minutes. in this sonication, it is seen that there are 2 weight losses at a temperature of 180-250 oc and at a temperature of 500700 oc as shown in figure 5. the first decrease is due to evaporation of polyvinyl alcohol and deionization in the mixed solution while the second decrease is due to oxidation of copper metal in the air. resulted in the crystallization of cuo [23]. figure 5. tg and dta curves of the precipitated product sonicated for 30 minutes [33]. the diameter of cuo nanoparticles obtained by sonochemical methods is 50 nm [19]. these results have been confirmed by tem (transmission electron microscope) and sem (scanning electron microscope). with a similar method, cuo nanoparticles can also be produced which are 80 nm before calcination and 70 nm after being calcined at 500 oc for 2 hours [34]. the results of the calcination of the sample at a temperature of 400-500 oc and the xrd pattern of the sample showed that good cuo particle powder was only obtained by a sonochemical process [23]. the results of xrd (x-ray diffraction) cuo nanoparticles calcined and sonicated at different temperatures and times are shown in figures 6 and 7. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 25 figure 6. xrd pattern of calcined cuo nanoparticles at different temperatures [23]. figure 7. xrd pattern of sonicated at different times [23]. the size of the cuo nanoparticles obtained can be influenced by the sonication time carried out as well as the kalisani temperature. a longer sonication time will result in smaller particle size compared to a lower sonication time. cuo nanoparticles obtained by the reaction of fewer than 20 minutes produce particles of about 80 nm, whereas if the reaction is prolonged to 30 minutes the resulting particle size is 45 nm. this result is thought to be due to sufficient energy supplied to the system by ultrasound after a certain time and can induce nucleation disintegration. the results will be inversely proportional in the sense that the size will increase after extending the sonication time to 40 minutes. this is thought to be due to changes in the crystal structure caused by the abundant energy of ultrasound after the critical time has elapsed [23]. the effect of temperature also causes changes in the size of the resulting particles. as the calcination temperature increases, the particle size will increase or increase. this is because the formation of crystallization of cuo nanoparticles is complete and well defined and uniform with a particle size of 50-70 nm [23]. figure 8 shows the sem results regarding the morphology of cuo nanoparticles at various calcination temperatures, namely 400, 500, 600, and 700 oc. the morphology of nanoparticles can be affected by the ph of the surfactant. when the ph is set to 8 the morphology looks like leaves while after the ph is raised to 11 the morphology changes to like a lumpy flower [33]. figure.8. sem morphology of cuo nanoparticles by sonochemical method calcined at various temperatures, namely 400, 500, 600, and 700 oc [23]. the sonochemical method has several advantages, namely easy preparation at low temperatures [18], can produce products with fine particles with nanometer dimensions [35], more uniform particle size distribution with higher phase purity. higher [33], reproducible [8], and the product can be used to remove environmental pollutants extensively [2]. the drawback of the sonochemical method is the uneven distribution of particles [23]. iv.3. sol-gel method another method for the synthesis of cuo nanoparticles is the sol-gel method [24, 36-39]. synthesis of cuo nanoparticles the sol-gel method can use several reactants, including cucl2.6h2o [36], lantana camara extract and cucl2 2h2o [37], [cu(ch3coo)2.h2o] [38], cu(ch3coo)2 with high purity [39], and glacial acetic acid and cucl2.2h2o [54]. the sol-gel method is carried out in several stages as shown in figure 9. figure 9. the process of making cuo nanoparticles using the sol-gel method [39]. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 26 the nanoparticle synthesis process using the sol-gel method started with glacial acetic acid added to cucl2.2h2o then heated to 100 oc. naoh is added after mixing the reactants to make the ph equal to 7. the color of the stirred solution changes rapidly from green to black and a large amount of black precipitate forms immediately. the precipitate was centrifuged and washed with distilled water under vacuum and dried at room temperature [24]. naoh was added to solutions of different concentrations at 60 oc and stirred for 2 hours then dried at 50 oc [39]. cu(no3)2 is dissolved in distilled water until dissolved. then acetic acid was added to the solution and heated to 100 oc and stirred using a magnetic stirrer for 60 minutes, and acetic acid was then added with naoh. the sole was heated and stirred for 1 hour then allowed to stand for 1 day. centrifugation was carried out at 3000 rpm, and a bluishgreen precipitate was obtained. then the precipitate is annealed. annealing was carried out at 400 oc for 4 hours then at 1000 oc, using a lindberg furnace [40]. characterization was carried out using several instruments such as xrd, tem, and uv-vis [39], ftir in the range of 4000.00 to 400.00 cm-1, thermogravimetry with sdt q 600, and sem [40]. the structure and morphology of the synthesized cuo nanoparticles were investigated using xrd and sem. the surface morphology of cuo nanoparticles was examined by sem scanning with the nanostructures visible and showing the heterogeneous distribution of the synthesized cuo nanoparticles. the nanoparticle size in this method is 16 nm and the nanoparticle size becomes smaller with increasing base concentration [24]. the result of the characterization of sem is shown in figure 10. figure 10. surface morphology of cuo nanoparticles using sem at (a) 400 oc and (b) 1000 oc [40]. xrd results show a single phase and a monoclinic structure. the intensity and peak position closely match the library data. the results of the characterization of xrd are shown in figure 11 [39]. figure.11. xrd pattern of samples prepared at various phs [18]. the morphological and size distribution were examined by tem. figure 12 shows that the cuo nanoparticles are spherical with uniform distribution with an average diameter of 4.5 nm [39]. figure 12. tem results and particle size distribution of cuo nanoparticles [39]. figure 13. ft-ir spectrum of cuo nanoparticles shows three peaks of the vibration of cu-o observed at 420.7, 472, and 631.5 cm-1 [39]. figure 13. ft-ir spectrum of cuo nanoparticles at (a) 400 oc and (b) 1000 oc [40]. uv-vis result is shown in figure 14. as can be seen, an adsorption peak is observed at 350 nm. the calculated band gap values are 4.08 ev [39]. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 27 figure 14. uv-vis spectra and tauc plots of cuo [39]. the result of another study using 3 samples, namely a, b, and c, was found that the particle size of cuo nanoparticles increasing with the calcination temperature. this is caused by the agglomeration of particles at high temperatures. the particle sizes of cuo a, b & c nanoparticles were 23, 25, and 28 nm. the reflectance appears above 830 nm for the three samples and the corresponding band gaps are 4.16, 4.17, and 4.16 ev for samples a, b, and c, respectively. from the sem results, it appears that cuo nanoparticles become porous balls and the balls were aggregated with the calcination temperature [41]. the sol-gel method offers many advantages compared to other synthesis methods, such as particle size, has a high homogeneity of form, uses low raw materials, and can be produced on a large scale [42]. the sol-gel method can synthesize nanoparticle materials at room temperature, can produce most metals, and accurately control chemical and physical characteristics [24]. this method is the easiest method that requires low temperatures and is the most economical [40]. the solgel method is considered to have great potential for the manufacture of nanoparticles from copper and copper oxide [43]. this method is also free from toxic and hazardous materials [44]. the drawback of the sol-gel method is the relatively long time in the synthesis process [24]. iv.4. green synthesis method the synthesis of cuo nanoparticles can be carried out using the green synthesis method [25, 45-49] can be carried out using several reactants, namely a solution of copper (ii) sulfate and leaf extract of ixora coccinea [25], kalopanax pictus [45], punica granatum [46], abutilon indicum [47], cucl2.2h2o and gum karaya [48], syzygium alternifolium [49], and aloe vera leaf extract and cu(no3)2 [50]. an illustration of the synthesis of cuo nanoparticles is shown in figure 16. figure.16. illustration of the synthesis of cuo nanoparticles using the green synthesis method [47]. the preparation of plant extracts is done by collecting the leaves, cleaned, and cut into small pieces. the leaves are then washed with distilled water. the leaves are then stored in a measuring flask filled with water and kept in a heating mantle until boiling. heating was stopped when the solution turned brown. the leaf extract was then cooled and filtered [25]. the synthesis process was carried out using a solution of copper (ii) sulfate. a solution of copper(ii) sulfate is a solution that has been stored overnight at room temperature so that bioreduction is possible and the copper salt is converted to copper oxide. the solution was centrifuged at 10,000 rpm using a 50 ml falcon tube for 20 minutes and washed several times with distilled water. then the supernatant solution was discarded and the nanoparticles were transferred to another container. the obtained nanoparticles must be dried in an oven to remove the moisture content [25]. there is a direct correlation between ph value, salt concentration, polydispersity index, and cuo nanoparticle size with biological methods. the correlation depends on the concentration of cu2+ ions in the solution, the enzymes released by the strain, and the ph of the solution. the results show the size distribution of the nanoparticles dispersed in the liquid to ensure the average size of the cuo nanoparticles. the polydispersity index measures the second moment of the nanoparticle population size distribution [25]. nanoparticle characterization was carried out using several techniques including ft-ir, sem, tem [50], and uv-vis spectrophotometer [25], and xrd (pan). analytical equipment: xpert-pro). sem results revealed that cuo nanoparticles have a high tendency to agglomerate. from the analysis of the tem images, it was found that cuo nanoparticles were concentrated at certain positions indicating their tendency to aggregate. the result of characterization by tem result is shown in figure 17. figure.17. tem results of synthesized cuo nanoparticles [25]. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 28 characterization of cuo nanoparticles using a uvvis spectrophotometer, namely the uv spectrum of cuo nanoparticles showed an abnormal capacity of cuo nanoparticles to absorb uv light in the wavelength range from 200 to 300 nm. sem results revealed the aggregation ability of cuo nanoparticles whereas tem revealed the average cuo nanoparticle size had been reduced to 5 nm by sonication of nanoparticles in acetone base liquid. the result of characterization by uv-vis spectrophotometer is shown in figure 18. figure 18. uv-vis spectrum of cuo nanoparticles synthesized with various concentrations of leaf extract [25]. the ft-ir peak obtained at the time shows bond vibrations such as cu-o and o-h in the cuo material. so that the synthesis of cuo nanoparticles using the green synthesis method was successfully carried out [25]. the results of characterization by ft-ir are shown in figure 19. figure 19. ft-ir spectrum of synthesized cuo nanoparticles [25]. the green synthesis method is more advantageous compared to other biological methods because it eliminates the use of cell culture and produces nanoparticles on a large scale [25]. the green synthesis method is also an environmentally friendly method with well-defined sizes, shapes, and mono dispersions [51]. the green synthesis method needs considerable attention because the protocol is cheaper than the basic synthetic method [52]. in addition, the green synthesis method has the ability as an antimicrobial agent against fish bacterial pathogens [50]. one of the disadvantages of this method is that the raw materials for the synthesis are relatively difficult to find [25]. iv.5. hydrothermal method the hydrothermal method is a water-solvent heating process that involves heating the reactants in a closed container using water. in a closed container, the pressure increases and the water remains as a liquid. heating water above its normal boiling point of 373 k is called superheated water. conditions in which the pressure increases above atmospheric pressure are known as hydrothermal conditions. hydrothermal synthesis is usually carried out at temperatures below 300 oc [29]. sample preparation using the hydrothermal method was carried out without the use of surfactants [53]. the procedure in the synthesis of cuo nanoparticles by the hydrothermal method is to dissolve cu(ch3coo)2.h2o 4 g in 50 ml of water. next, 40 ml of an aqueous solution of sodium hydroxybiogenicide (1 m/l) was added dropwise into the cu(ch3coo)2.h2o solution. then, 90 ml of the solution was transferred and sealed in a teflon-coated stainless steel autoclave at 110 oc for 2 hours. finally, the autoclave is removed and naturally cooled to room temperature. after the reaction stopped, the black precipitate was washed with deionized water and ethanol and then dried at 90 oc [26]. cuo nanoparticles can also be synthesized using cuso4.5h2o and naoh. where from these materials cuo powder will be produced which is stored in a vacuum desiccator to reduce the remaining solvent in the cuo powder [54]. the technique for characterizing cuo nanoparticles namely the size and morphology of the cuo nanostructures was examined by sem (jeol jsm-5900, japan) connected to the attached eds and the phase identification of the sample was examined by xrd (type dmax iii-a, rigaku co., japan) using radiation. cu-kα incidence, tube voltage 40 kv, and current 30 ma. the scanning range is from 20 to 60o 2θ with a scan speed of 4◦/min. the particle size was then calculated from the xrd spectrum using the scherrer equation. the ft-ir spectra were recorded as kbr pellets using an abb bomen mb 100 spectrometer at wavenumbers between 400 and 4000 cm −1 . the characterization technique is the xrd obtained on the bruker d2 phaser xrd system. surface morphology by sem was studied using a scanning electron microscope (jeol jsm 840a) coupled with an energy dispersive x-ray analyzer (edx) [55]. tem and selected area diffraction patterns (saed) were recorded using a philips cm-200 instrument. finally, ft-ir analysis was applied to determine the surface functional groups, using ft-ir spectroscopy (bruker atr), wherein the spectra were recorded from 400 to 4000 cm −1 [56]. figure 20 shows the xrd pattern of samples made by the hydrothermal process at 110 oc for 2 hours with different concentrations of copper acetate. all diffraction peaks can be indexed as monoclinic cuo phases with lattice constants a = 4.68ao, b = 3.43ao, c = 5.13ao, and β =99.26o or 99.47 which, which is consistent with the values in standard card (jcpds 80-0076 or jcpds 05 0661), as previously reported. no other impurities were detected by xrd analysis, which indicates the phase clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 29 purity of the cuo nanostructures. and the main peaks located at 2θ = 35.5o and 38.7o are indexed as crystal planes (0 0 2) and (1 1 1), respectively. the expansion of all the peaks recorded in the spectrum indicates the presence of nanoscale crystallites. in addition, with increasing cu(ch3coo)2 concentration from 0.06 m/l to 0.7 m/l (from pattern 1a to pattern 1i), the diffraction peaks were highest and narrowest when the copper acetate concentration was 0.2 m/l. , which illustrates that the crystallization and size of cuo nanostructures increase maximally [26]. figure 20. xrd pattern of cuo nanostructures made by hydrothermal approach at different concentrations of copper acetate: (a) 0.02 m/l, (b) 0.08 m/l, (c) 0.1 m/l, (d) 0.2 m/l, (e ) 0.3 m/l, (f) 0.4 m/l, (g) 0.5 m/l, (h) 0.6 m/l, (i) 0.7 m/l [26]. the concentration of copper acetate used will affect the morphological size of the cuo nanoparticles, the greater the concentration of the reactant (copper acetate), the greater the size of the cuo particles. the general morphology of the synthesized cuo products prepared by the hydrothermal route at different reactant concentrations was analyzed by fesem and the results are shown in figure 21 [22]. with the increase in the concentration of cu(ch3coo)2, the morphology of the cuo nanostructure has a large change. the floral morphology like cuo nanostructures was obtained at 0.4 m/l, as shown in figure 21(a), which indicates that the flower-like cuo nanostructures are composed of irregular nanosheets about 70 nm wide and 1.7 m long. with increasing reactant concentration, the morphology of the flower-like cuo nanostructures disappeared, and scattered plume-like nanosheets were formed, as shown in figure 21(b). the nanoplate size is about 400 nm wide and 900 nm long. when the reactant concentration is equivalent to 0.6 m/l, the morphology changes to a spindle-like nanostructure. thus, the morphology of cuo nanocrystals can be controlled by changing the concentration of the reactants [26]. figure 21. fesem images of cuo nanostructures prepared under different concentrations of copper acetate at 110 c for 2 hours: (a) 0.06 m/l, (b) 0.4 m/l, (c) 0.6 m/l [26]. besides acting as a precipitate, naoh is also very important in changing the shape of cuo particles. when naoh is not used, the cuo particles produced are spherical, but when naoh with a concentration of 1m is used, the resulting cuo particles form in layers. figure 22 shows the morphology of the nanostructures grown with naoh or not under the same conditions. when the synthesis process was carried out without naoh, a hericium erinaceus-like morphology of cuo was obtained, as shown in figure 22(a). however, with increasing naoh concentration to 1 m/l, there was a change in the morphology and layered structure of the cuo nanostructure, which we can conclude from figure 22(b). that is, naoh plays an important role to determine the morphology of cuo nanostructures because oh is strongly associated with reactions that form nanocrystals [26]. figure 22. fesem images of cuo nanostructures prepared with 0.4 m/l copper acetate at 110 c for 2 hours: (a) without naoh, (b) 1.0 m/l naoh [26]. the effect of temperature will make the diffraction peaks higher and sharper, this will affect the size of the cuo particles. at a temperature of 110-140 oc cuo particle size is around 2000 nm, when the temperature is raised to 170 oc the cuo particles produced shrink to 500 nm. figure 23 shows fesem images of the synthesized cuo nanostructures made by the hydrothermal route at different temperatures. it can be seen that each of these lamellar structures. with increasing temperature, the morphology of cuo nanostructures changes slightly so that the nanosheet length becomes shorter, as shown in figure 23(a-c). from figure 23(d), we can see that when the hydrothermal temperature is up to 170 oc, cuo nanosheets are about 600 nm long and 200 nm wide [26]. clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 30 figure 23. fesem images of cuo nanostructures prepared at different reaction temperatures: (a) 110 oc, (b) 140 oc, low (c) and high magnification (d) images at 170 oc [26]. the final effect is the duration of the reaction, although this factor only slightly affects the results. by prolonging the reaction time, the resulting diffraction peaks will be higher and narrower, therefore the size of the cuo particles produced will be smaller. the morphology of the synthesized cuo products under different reaction times was observed using fesem analysis and is shown in figure 24. from lowmagnification fesem images of cuo nanosheets. compared with the morphology of cuo nanosheets at 2 hours, the cuo nanostructures at 12 hours became clearer and had a smaller size. the reaction time has little influence on the morphology and structure of the product. figure 24. fesem images of cuo nanostructures prepared under different reaction times (a) 2 h, (b) 12 h [26]. the hydrothermal method is an effective method to obtain the desired crystals, such as mild conditions, controlled morphology, low aggregation, and high crystallinity. in addition, the hydrothermal method is also relatively simple and easy to vary the variables of temperature, reactant concentration, and time on the growth of nanostructures [26]. in addition, the hydrothermal method can control the size and shape of the nanoparticles [29]. the disadvantages of this method are that it requires expensive equipment and it is difficult to control the stoichiometry of the solution [26]. another disadvantage of the hydrothermal method is that hydrothermal slurries are corrosive, and the use of highpressure vessels will be dangerous in the event of an accident [29]. iv.6. biogenic method the biogenic method of cuo nanoparticles was prepared at room temperature by coprecipitation technique with several cation modifications. briefly, in this experiment, 0.1 m solution of copper acetate cu(ch3coo)2.h2o (purity 98.0%) and 40 ml plant extracts (such as algae) were stirred constantly for 30 minutes. then, 0.2 m naoh aqueous solution was added dropwise to the reaction mixture and allowed to stand for 4 hours. next, the reaction solution was incubated overnight at room temperature for the deposition of the nanoparticles as a precipitate. the precipitate was separated by centrifugation at 5000 × g for 10 min, the precipitate was washed with deionized water, and dried at 80 °c for 12 h. cuo dry powder was calcined at 400 °c for 4 hours to obtain cuo nanoparticles [57]. after the nanoparticles are calcined, they are cooled to room temperature for further exploration through photocatalytic characterization and application [27]. according to the available literature, it was observed that the secondary moieties (alkaloids, flavonoids, polyphenols, and terpenoids) present in plant extracts tend to have a high enough potential to reduce the acetate group of metal salts through chelation [5]. especially, the –oh group plays an important role in the synthesis of metal nanoparticles [58]. during the calcination process, the breaking of the bond between the metal salt and the –oh group causes the formation of metal oxide nanoparticles with the removal of water molecules [59-60]. a possible mechanism for the synthesis of cuo nanoparticles is described in figure 25. figure 25. schematic for stepwise synthesis procedure of cuo nanoparticles [27]. the functionality of the biogenic cuo nanoparticles was analyzed by the ftt-ir. the morphology and size of the synthesized nanoparticles were measured using uv-vis, fe-sem, and jeol 2100 tem. the elemental clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 31 composition of cuo nanoparticles was evaluated using xrd spectroscopy [27]. the ultraviolet-visible spectrum of the biogenic cuo nanoparticles synthesized with plant extracts is shown in figure 26(a). the colloidal buffer of the final product showed a strong absorption band at 282 nm, which confirmed the formation of cuo nanoparticles. the absorption band at 282 nm is associated with the transition between the electron bands of the copper metal core present in the cuo nanoparticles [50]. the presence of protein-like molecules in the leaf extract is responsible for the reduction of cu metal salts to form cuo nanoparticles [46]. the bandgap of the synthesized cuo nanoparticles was determined by the tauc plot method [61], which involves plotting (αhν) 1/2 versus, as shown in figure 26(b). in the tauc plot, is the absorption coefficient and is the light energy. furthermore, h is the planck's constant of 6.626 × 10 −34 js [39]. xrd spectra of biogenic cuo nanoparticles showed a series of diffraction peaks at 32.63, 35.67, 38.78, 48.88, 58.34, 61.69, 68.16, and 75.32°. which is associated with (110), (111), (202), (020), (113), (311), and (004) cuo monoclinic planes, respectively. the presence of a diffraction peak (between 2θ = 35–39°) confirmed the formation of cuo [62]. the xrd data obtained from the synthesized cuo nanoparticles are very similar to the monoclinic crystalline spectrum of cuo nanoparticles (ejcpds 05 0661) which can be seen in figure 26(c) [27]. ft-ir (perkin elmer, usa) was used to identify the functional groups present in cuo nanoparticles biosynthesized by the kbr pellet procedure. the visibleultraviolet spectrum was measured from 200 to 600 nm in quartz using a uv-visible spectrophotometer (model uv-2600, shimadzu inc. 01197). the surface functional groups of biogenic cuo nanoparticles were investigated by ft-ir spectroscopy. as shown in figure 26(d), the spectrum of the synthesized cuo nanoparticles showed the main vibrational peaks at 530, 1088, 1628, 2842, and 3750 cm-1. the strong bands at 1088 and 530 cm −1 are caused by cuo vibrations [50]. the 2842 cm −1 band is due to the c=o alkanes of the proteins present on the surface of the nanoparticles, respectively. these bands are associated with protein residues present on the surface of the nanoparticles after the synthesis process. in this study, it was assumed that the protein present in the leaf extract was responsible for the reduction of the acetate group of metal salts to nanoparticles and acted as a stabilizing and capping agent for cuo nanoparticles [46]. ft-ir also suggested the presence of a hydroxyl group (band at 3750 cm −1 ) on the surface of the synthesized cuo nanoparticles, which is thought to act as a stabilizer during the synthesis of biogenic cuo nanoparticles [46, 63-64]. figure 26. spectral analysis of synthesized biogenic cuo nanoparticles: (a) uv vis, (b) tauc plot, (c) xrd, and (d) ft-ir [27]. the morphological characteristics of the synthesized cuo nanoparticles were evaluated by fesem. as shown in figures 27(a and b), the nanoparticles exhibited a spherical morphology as coarse agglomerates. the same sample was used for edx analysis. as shown in figure 27(c), the agglomerated cuo nanoparticles contained 91.72 and 8.28% by weight cu and o, respectively. the presence of other elements even from the leaf extract was negligible. most of the remaining leaf extract molecules were removed during the washing and calcination processes of the synthesized nanoparticles cuo. however, due to the presence of carbon molecules in the leaf extract, a small amount of carbon may be present on the surface of the synthesized cuo nanoparticles in the form of capping [27]. as shown in figure 28, the prepared cuo nanoparticles are spherical with a uniform size distribution of 2-6 nm [27]. figure 27. fe-sem of synthesized biogenic cuo nanoparticles with (a) 200 nm (inset: square showing element mapping) and (b) 100 nm scale bars. moreover, (c) for the edx spectrum of cuo nanoparticles [27]. the specific surface area of the synthesized cuo nanoparticles was found to be 52.6 m2/g with a total pore volume of 0.197 cm3/g and an average pore diameter of 14.98 nm as described in figure 28. s1 in supplementary information (si). note that all related information clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 32 referring to the figure is also provided in the si. the relative pressure (p/po) is 0.985. in addition, the aggregation kinetics of cuo nanoparticles has been investigated through a particle size analyzer using nacl as an electrolyte at different concentrations (20, 40, and 60 mm) [65]. a very small change in mean particle size was observed even at 60 mm nacl concentration similarly, control experiments (without nacl) showed negligible variation in particle size after 60 min which signifies stability of the synthesized nanoparticles. figure.28. tem micrograph of synthesized cuo nanoparticles: (a) 50 nm and (b) 20 nm scale rods [27]. there are advantages to this method, namely the procedure is simple, the equipment required is environmentally friendly, and does not require high costs. however, this method also has drawbacks, namely the difficulty of implementing on a large scale and the need to maintain cell cultures and it is difficult to control the size, shape, and crystallinity [27]. v. conclusion cuo nanoparticles are oxide semiconductors that have unique properties and have many applications in several fields and are useful in everyday life. one of its uses is that it can be used to divert heat energy. the addition of a volume of cuo nanoparticles into the nitrate salt can increase the thermal diffusivity and thermal conductivity used in solar power plants. cuo nanoparticles can be synthesized from several methods: (1) electrochemistry, (2) sonochemistry, (3) sol-gel, (4) green synthesis, (5) hydrothermal, and (6) biogenic methods. each method has its results and advantages. among the methods described, the hydrothermal method is the most effective and efficient method for industrial scale. this is because the method is simple (without using any surfactant template), it is easy to vary the variables of temperature, reactant concentration, and time on the growth of nanostructures. this paper is expected to provide some considerations regarding the synthesis method of cuo nanoparticles that can be used on an industrial scale based on the advantages of each method. acknowledgments we acknowledged bangdos universitas pendidikan indonesia. references [1] n. t. rochman, y. l. brama, “indonesia nanotechnology development: current status overview”, in emerging nanotechnology power: nanotechnology r&d and business trends in the asia pacific rim, 2019, pp. 141167. [2] s. saravanan and t. sivasankar, “effect of ultrasound power and calcination temperature on the sonochemical synthesis of copper oxide nanoparticles for textile dyes treatment”, environmental progress & sustainable energy, vol 35, issue 3, may 2016, pp. 669-679. [3] t. velusamy, a. liguori, m. macias-montero, d. b. padmanaban, d. carolan, m. gherardi, v. colombo, p. maguire, v. svrcek. d. mariotti, “ultra‐small cuo nanoparticles with tailored energy‐band diagram synthesized by a hybrid plasma‐liquid process”, plasma processes and polymers, vol 14, issue 7, february 2017, pp. 1-8. [4] n. dighore, s. jadhav, s. gaikwad, a. rajbhoj, “copper oxide nanoparticles synthesis by electrochemical method”, materials science, vol 22, issue 2, june 2016, pp. 170173. [5] b. naseer, g. srivastava, o. s. qadri, s. a. faridi, r. u. islam, k. younis, “importance and health hazards of nanoparticles used in the food industry”, nanotechnology reviews, vol 7, issue 6, december 2018, pp. 623-641. [6] jr. p. d. myers, t. e. alam, r. kamal, d. y. goswami, e. stefanakos, “nitrate salts doped with cuo nanoparticles for thermal energy storage with improved heat transfer”, applied energy, vol 165, march 2016, pp. 225-233. [7] k. borgohain, j. b. singh, m. r. rao, t. shripathi, s. mahamuni, “quantum size effects in cuo nanoparticles”, physical review b, vol 61, issue 16, april 2000, pp. 9496. [8] n. silva, s. ramires, i. diaz, a. garcia, n. hassan, “easy, quick, and reproducible sonochemical synthesis of cuo nanoparticles”, materials, vol 12, issue 5, january 2019, pp. 804. [9] s. moleh, m. r. rahimi, m. ghaedi, k. dashtian, s. hajati, “sonochemical-assisted synthesis of cuo/cu2o/cu nanoparticles as efficient photocatalyst for simultaneous degradation of pollutant dyes in rotating packed bed reactor: led illumination and central composite design optimization”, ultrasonics sonochemistry, vol 40, january 2018, pp. 601-610. [10] e. mousali, m. a. zanjachi, “electrochemical synthesis of copper (ii) oxide nanorods and their application in photocatalytic reactions”, journal of solid state electrochemical, vol 23, issue 3, march 2019, pp. 925935. [11] i. m. araújo, r. r. silva, g. pacheco, w. r. lustri, a. tercjak, j. gutierrez, j. r. s. júnior, f. h. c. azevedo, g. s. figuêredo, m. l. vega, s. j. l. ribeiro, h.s. barud, “hydrothermal synthesis of bacterial cellulose–copper oxide nanocomposites and evaluation of their antimicrobial activity”, carbohydrate polymers, vol 179, issue 3, january 2018, pp. 341-349. [12] s. jadhav, s. gaikwad m. nimse, a. rajbhoj, “copper oxide nanoparticles: synthesis, characterization and their antibacterial activity”, journal of cluster science, vol 22, issue 2, june 2011, pp. 121-129. [13] n. c. joshi, y. a. s. h. w. a. n. i. prakash, “leaves extract-based biogenic synthesis of cupric oxide nanoparticles, characterizations, and antimicrobial clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 33 activity”, asian j pharm clin res, vol 12, issue 8, 2019, pp. 288-291. [14] p. pandey, s. merwyn, g. s. agarwal, b. k. tripathi, s. c. pant, “electrochemical synthesis of multi-armed cuo nanoparticles and their remarkable bactericidal potential against waterborne bacteria”, journal of nanoparticle research, vol 14, issue 1, january 2012. pp. 1-13. [15] g. sharmila, r. s. pradeep, k. sandiya, s. santhiya, c. muthukumaran, j. jeyanthi, n. m. kumar, m. thirumarimurugan, “biogenic synthesis of cuo nanoparticles using bauhinia tomentosa leaves extract: characterization and its antibacterial application”, journal of molecular structure, vol 1165, august 2018, pp. 288292. [16] r. sivaraj, p. k. rahman, p. rajiv, h. a. salam, r. venckatesh, “biogenic copper oxide nanoparticles synthesis using tabernaemontana divaricate leaf extract and its antibacterial activity against urinary tract pathogen”, spectrochimica acta part a: molecular and biomolecular spectroscopy, vol 133, december 2014, pp. 178-181. [17] v. v. khedekar, b. m. bhanage, “simple electrochemical synthesis of cuprous oxide nanoparticles and their application as a non-enzymatic glucose sensor”, journal of the electrochemical society, vol 163, issue 6, march 2016, b248. [18] j. zhang, j. wang, y. fu, b. zhang, z. xie, “sonochemistry-synthesized cuo nanoparticles as an anode interfacial material for efficient and stable polymer solar cells”, rsc advances, vol 5, issue 36, 2015, pp. 28786-28793. [19] h. abbasian, d. ghanbari, g. nabiyouni, “sonochemicalassisted synthesis of copper oxide nanoparticles and its application as humidity sensor”, journal of nanostructures, vol 3, issue 4, december 2013, pp. 429-434. [20] z. zhong, v. ng, j. luo, s. p. teh, j. teo, a. gedanken, “manipulating the self-assembling process to obtain control over the morphologies of copper oxide in hydrothermal synthesis and creating pores in the oxide architecture”, langmuir, vol 23, issue 11, may 2007, pp. 5971-5977. [21] s. bhuvaneshwari, n. gopalakrishnan, “hydrothermally synthesized copper oxide (cuo) superstructures for ammonia sensing”, journal of colloid and interface science, vol 480, october 2016, pp. 76-84. [22] m. a. choudhary, r. manan, m. m. aslam, k. h. rashid, s. qayyum, z. ahmed, “biogenic synthesis of copper oxide and zinc oxide nanoparticles and their application as antifungal agents”, int. j. mater. sci. eng, vol 4, 2018, pp. 1-6. [23] n. wongpisutpaisan, p. charoonsuk, n. vittayakorn, w. pecharapa, “sonochemical synthesis and characterization of copper oxide nanoparticles”, energy procedia, vol 9, january 2011, pp. 404-409. [24] h. k. thanoon, k. a. hubeatir, a. a. al-amiery, “synthesis of copper oxide nanoparticles via sol-gel method”, international journal of research in engineering and innovation, vol 1, issue 4, 2017, pp. 43-45. [25] k. vishveshvar, m. a. krishnan, k. haribabu, s. vishnuprasad, “green synthesis of copper oxide nanoparticles using ixiro coccinea plant leaves and its characterization”, bionanoscience, vol 8, issue 2, june 2018, pp. 554-558. [26] t. jiang, y. wang, d. meng, x. wu, j. wang, j. chen, “controllable fabrication of cuo nanostructure by hydrothermal method and its properties”, applied surface science, vol 3, issue 11, august 2014, pp. 602-608. [27] j. singh, v. kumar, k. h. kim, m. rawat, m, “biogenic synthesis of copper oxide nanoparticles using plant extract and its prodigious potential for photocatalytic degradation of dyes”, environmental research, vol 177, october 2019, pp. 108569. [28] n. verma, n. kumar, “synthesis and biomedical applications of copper oxide nanoparticles: an expanding horizon”, acs biomaterials science & engineering, vol 5, issue 3, february 2019, pp. 1170-1188. [29] s. k. w. ningsih, “sintesis anorganik. padang”, unp press, 2016, 76-99 [30] h. yang, j. ouyang, a. tang, y. xiao, x. li, x. dong, y. yu, “electrochemical synthesis and photocatalytic property of cuprous oxide nanoparticles”, materials research bulletin, vol 41, issue 7, july 2006, pp. 13101318. [31] s. m. pourmortazavi, m. rahimi-nasrabadi, a. sobhaninasab, m. s. karimi, m. r. ganjali, s. mirsadeghi, “electrochemical synthesis of copper carbonates nanoparticles through experimental design and the subsequent thermal decomposition to copper oxide”, materials research express, vol 6, issue 4, january 2019, pp. 045065. [32] m. starowicz, m, “electrochemical synthesis of copper oxide particles with controlled oxidation state, shape and size”, materials research express, vol 6, issue 8, may 2019, 0850a3. [33] n. a. neto, p. m. oliveira, r. m. nascimento, c. a. paskocimas, m. r. d. bomio, f. v. motta, “influence of ph on the morphology and photocatalytic activity of cuo obtained by the sonochemical method using different surfactants”, ceramics international, vol 45, issue 1, january 2019, pp. 651-658. [34] r. ranjbar-karimi, a. bazmandegan-shamili, a. aslani, k. kaviani, k, “sonochemical synthesis, characterization and thermal and optical analysis of cuo nanoparticles”, physica b: condensed matter, vol 405, issue 15, august 2010, pp. 3096-3100. [35] s. anandan, g. j. lee, j. j. wu, “sonochemical synthesis of cuo nanostructures with different morphology”, ultrasonics sonochemistry, vol 19, issue 3, may 2012, pp. 682-686. [36] y. aparna, k. e. rao, p. s. subbarao, “synthesis and characterization of cuo nano particles by novel sol-gel method”, in proceedings of the 2nd international conference on environment science and biotechnology, vol 48, 2012, pp. 156-160. [37] b. arunkumar, s. j. jeyakumar, m. jothibas, m, “a solgel approach to the synthesis of cuo nanoparticles using lantana camara leaf extract and their photo catalytic activity”, optik, vol 183, april 2019, pp. 698-705. [38] j. jayaprakash, n. srinivasan, p. chandrasekaran, e. k. girija, “synthesis and characterization of cluster of grapes like pure and zinc-doped cuo nanoparticles by sol-gel method”, spectrochimica acta part a: molecular and biomolecular spectroscopy, vol 136, february 2015. pp. 1803-1806. [39] n. zayyoun, l. bahmad, l. laânab, b. jaber, “the effect of ph on the synthesis of stable cu 2 o/cuo nanoparticles by sol–gel method in a glycolic medium”, applied physics a, vol 122, issue 5, may 2016, pp. 488. [40] z. n. kayani, m. umer, s. riaz, s. naseem, “characterization of copper oxide nanoparticles fabricated clarysa satari et al ijeca-issn: 2543-3717. december 2021 page 34 by the sol–gel method”, journal of electronic materials, vol 44, issue 10, october 2015, pp. 3704-3709. [41] k. nithya, p. yuvasree, n. neelakandeswari, n. rajasekaran, k. uthayarani, m. chitra, s. s. kumar, “preparation and characterization of copper oxide nanoparticles”, int. j. chemtech res, vol 6, issue 3, may 2014, pp. 2220-2222. [42] h. siddiqui, m. r. parra, f. z. haque, “optimization of process parameters and its effect on structure and morphology of cuo nanoparticle synthesized via the sol− gel technique”, journal of sol-gel science and technology, vol 87, issue 1, july 2018, pp. 125-135. [43] o. akhavan, h. tohidi, a. z. moshfegh “synthesis and electrochromic study of sol–gel cuprous oxide nanoparticles accumulated on silica thin film”, thin solid films, vol 517, issue 24, october 2009, pp. 6700-6706. [44] m. altikatoglu, a. attar, f. erci, c.m. cristache, i. isildak, “green synthesis of copper oxide nanoparticles using ocimum basilicum extract and their antibacterial activity”, fresenius environ. bull, vol 25, january 2017, pp. 7832-7837. [45] s.a. akintelu, a.s. folorunso, f.a. folorunso, a.k. oyebamiji, “green synthesis of copper oxide nanoparticles for biomedical application and environmental remediation”, heliyon, vol 6, issue 7, july 2020, pp. e04508. [46] a. y. ghidan, t. m. al-antary, a.m. awwad, “green synthesis of copper oxide nanoparticles using punica granatum peels extract: effect on green peach aphid”, environmental nanotechnology, monitoring & management, vol 6, december 2016, pp. 95-98. [47] f. ijaz, s. shahid, s.a. khan, w. ahmad, s. zaman, “green synthesis of copper oxide nanoparticles using abutilon indicum leaf extract: antimicrobial, antioxidant and photocatalytic dye degradation activitie”, tropical journal of pharmaceutical research, vol 16, issue 4, may 2017, pp. 743-753. [48] v. v. t. padil and m. černík, “green synthesis of copper oxide nanoparticles using gum karaya as a biotemplate and their antibacterial application”, international journal of nanomedicine, vol 8, february 2013, pp. 889-898 [49] p. yugandhar, t. vasavi, p.u.m. devi, n. savithramma, “bioinspired green synthesis of copper oxide nanoparticles from syzygium alternifolium (wt.) walp: characterization and evaluation of its synergistic antimicrobial and anticancer activity”, applied nanoscience, vol 7, issue 7, october 2017, pp. 417-427. [50] p. v. kumar, u. shameem, p. kollu, r.l. kalyani, s.v.n. pammi, “green synthesis of copper oxide nanoparticles using aloe vera leaf extract and its antibacterial activity against fish bacterial pathogens”, bionanoscience, vol 5, issue 3, september 2015, pp. 135-139. [51] s. honary, h. barabadi, e. gharaei-fathabad, f. naghibi, “green synthesis of copper oxide nanoparticles using penicillium aurantiogriseum, penicillium citrinum and penicillium waksmanii”, dig j nanomater bios, vol 7, issue 3, july 2012, pp. 999-1005. [52] d. berra, s.e. laouini, b. benhaoua, m.r. ouahrani, d. berrani, a. rahal, “green synthesis of copper oxide nanoparticles by pheonix dactylifera l leaves extract”, digest journal of nanomaterials and biostructures, vol 13, issues 4, october 2018, pp. 1231-1238. [53] k.j arun,a.k. batra, a. krishna, k. bhat, m.d. aggarwal, p.j. francis, “surfactant free hydrothermal synthesis of copper oxide nanoparticles”, am. j. mater. sci, vol 5, 2015, pp. 36-38. [54] b. dutta, e. kar, n. bose, s. mukherjee, “significant enhancement of the electroactive β-phase of pvdf by incorporating hydrothermally synthesized copper oxide nanoparticles”, rsc advances, vol 5, issues 127, november 2015, pp. 105422-105434. [55] k.y. kumar, h.b. muralidhara, y.a. nayaka, h. hanumanthappa, m. s. veena, s. k. kumar, “hydrothermal synthesis of hierarchical copper oxide nanoparticles and its potential application as adsorbent for pb (ii) with high removal capacity”, separation science and technology, vol 49, issues 15, october 2015, pp. 2389-2399. [56] m.p. neupane,y.k. kim, i.s. park, k.a. kim, m.h. lee, t.s. bae , “temperature driven morphological changes of hydrothermally prepared copper oxide nanoparticles”, surface and interface analysis: an international journal devoted to the development and application of techniques for the analysis of surfaces, interfaces and thin films, vol 41, issues 3, january 2009, pp. 259-263. [57] d. vinu, k. govindaraju, r. vasantharaja, s.a. nisa, m. kannan, k.v. anand, “biogenic zinc oxide, copper oxide and selenium nanoparticles: preparation, characterization and their anti-bacterial activity against vibrio parahaemolyticus”, journal of nanostructure in chemistry, vol 11, issue 2, june 2021, pp. 271-286. [58] m. imran din and a. rani, “recent advances in the synthesis and stabilization of nickel and nickel oxide nanoparticles: a green adeptness”, international journal of analytical chemistry, june 2016. [59] s. kaur, j. singh, r. rawat, s. kumar, h. kaur, k.v. rao, m. rawat, “a smart lpg sensor based on chemo-bio synthesized mgo nanostructure”, journal of materials science: materials in electronics, vol 29, issues 14, july 2018, pp. 11679-11687. [60] a. singh, n.b. singh, i. hussain, h. singh, v. yadav, “synthesis and characterization of copper oxide nanoparticles and its impact on germination of vigna radiata (l.) r. wilczek”, tropical plant research, vol 4, issue 2, june 2017, pp. 246-253. [61] b.d. viezbicke, “investigation of l-cystine assisted cu 3 bis 3 synthesis for energetically and environmentally improved integration as thin-film solar cell p-type semiconductor absorber”, rutgers the state university of new jersey-new brunswick, january 2015. [62] a. nezamzadeh-ejhieh and s. hushmandrad, “solar photodecolorization of methylene blue by cuo/x zeolite as a heterogeneous catalyst”, applied catalysis a: general, vol 388, issues 1-2, november 2010, pp. 149159. [63] a. nezamzadeh-ejhieh and m. karimi-shamsabadi, “decolorization of a binary azo dyes mixture using cuo incorporated nanozeolite-x as a heterogeneous catalyst and solar irradiation”, chemical engineering journal, vol 228, july 2012, pp. 631-641. [64] s. senobari and a. nezamzadeh-ejhieh, “a pn junction nio-cds nanoparticles with enhanced photocatalytic activity: a response surface methodology study”, journal of molecular liquids, vol 257, may 2018, pp. 173-183. [65] v.s. sousa and m.r.teixeira, “aggregation kinetics and surface charge of cuo nanoparticles: the influence of ph, ionic strength and humic acids” , environmental chemistry, vol 10, issue 4, august 2013, pp. 313-322. i. introduction ii. study on methods in the synthesis of cuo (copper oxide) iii. synthesis of cuo nanoparticles iv. result and discussion v. conclusion acknowledgments references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 33-40 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 33 enhancing the potential of smart building for general hospital: a case study in malaysian hospital mohd faisal baharuddin 1,2* , chin haw lim 2 , ahmad fazlizan 2 1 engineering department, state health department pulau pinang, 10450 georgetown, pulau pinang, malaysia 2 solar energy research institute (seri), universiti kebangsaan malaysia, 43600 bangi, selangor, malaysia * corresponding author: email: chinhaw.lim@ukm.edu.my abstract –hospital pulau pinang is the general hospital in malaysia which targeting energy savings of 10% within five years from 2015 and other sustainability targets such as 3-star energy management gold standard and green building certification. the targets are beneficial for the hospital itself to establish the smart building program to improve its energy efficiency concurrent with the green policy of the ministry of health malaysia and sustainable development goals by the united nations. this paper reviews the background of hospital pulau pinang energy data , energy consumption trending, energy-saving trending, and energy conservation measures taken for the hospital from 2015 to december 2021.the yearly energy consumption baseline taken in 2016 was 27,496,731.00 kwh. it reduced significantly to 21,356,063 kwh in 2021 due to energy conservation measures. as a result, hospital pulau pinang has achieved energy-saving about 16% at approximately rm7.3 million reduction in operational expenditure. the main objective of this paper is to provide further potential energy savings by studying the energy reduction by implementing solar photovoltaics using the simulation method. the simulation method can predict that hospital pulau pinang can achieve another 5,130,000 kwh energy savings annually. this type of simulation has never been done before at a public hospital, and it will give further enhancing strategies to the smart building program itself. furthermore, the potential of smart building can be maximized to the next level by simulation, which helps the hospital energy committee make the potential decision on the energy-saving investment. keywords: digital twin; energy saving; simulation; solar energy; smart building. received: 20/10/2022 – revised 07/12/2022 – accepted: 20/12/2022 i. introduction to achieve established smart building for hospital pulau pinang, the energy management program (e.m.p.) and sustainability program (s.p.) are essential and concurrently with requirements in the concession agreement (c.a.). today the entire world has realized the importance of being sustainable, smart building and energy-efficient building, and the hospital must also change eventually. the early 1980s was the starting point of research on making buildings intelligent. through the ministry of health (m.o.h.), hospital pulau pinang is bound to the concession agreement. the contract signed from 2015 until 2025 aims to achieve 10% energy saving for all hospitals in malaysia and a few other key performance indicators that are subject to terms & conditions [1]. mailto:chinhaw.lim@ukm.edu.my mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 34 the world summit on sustainable development in johannesburg in 2002 identified health as one of the five big priorities for the future [2]. in summary, hospital buildings should be sustainable, healthy, and technologically aware, meeting the needs of the occupants and building, and should be flexible and adaptable to deal with change. this leads to achieving a building that has with combination of environmental, social and economic values. in line with the national vision to create more green buildings within government building, this concession agreement also included with the sustainability program including energy management program (e.m.p. the world summit on sustainable development in johannesburg in 2002 identified health as one of the five big priorities for the future. in summary, hospital buildings should be sustainable, healthy, and technologically aware, meeting the needs of the occupants and building, and should be flexible and adaptable to deal with change. this leads to achieving a building with the best environmental, social and economic values [3]. hospital is using a lot of energy to operate the hospital to meet its healthcare standard. energy consumption in hospital is relatively high, while energy savings and cost reduction are some of the biggest challenges considered by mist designers, engineers, and decisionmakers [3]. hospital has the highest building energy index (b.e.i.) compared to other building types due to its non-stop 24/7 operations, especially in the pandemic season of covid-19 [4]. the program from 2015 until 2021 has started with data collection and energy countermeasure. this paper gives a better understanding of how to maximise the solar photovoltaic potential tailored suit with the hospital pulau pinang building. it can be achieved through building energy simulation, using i.e.s. icd and ve where the software can generate a digital twin of the hospital. it can simulate the potential energy saving, carbon emission, p.v. electricity yield and p.v. radiation from the interactive dashboard. determining the potential and calculating the performance of renewables in an urban environment is essential for the design of future urban areas and the retrofit of existing structures. accurate modelling is essential to achieve this objective [5]. the objective of this work is to explore ways in which smart building technology can improve the functionality and efficiency of a general hospital. the goal is to identify the benefits of implementing smart building systems, such as increased energy efficiency, improved patient care, enhanced security, and improved staff productivity, in order to create a better and more effective healthcare environment. ii. methodology ii.1. case study background hospital pulau pinang is the biggest hospital in the northern region and second-largest hospital in malaysia which offer clinical services, training & research centre. it is located at latitude 5.42 n and longitude 100.31 e of peninsular malaysia. this multiple-building hospital is categorized as a state hospital that first started its operation in 1812 and is managed by the ministry of health (m.o.h.) malaysia. this hospital has a building gross floor area of 119,383.77 m 2 with a total airconditioning area about 37% at 44,799.17m 2 with total energy consumption at 27,496,731.00 kwh from 2016 baseline. most of the buildings are designed with natural and mechanical ventilation with windows. hospital pulau pinang is a specialist state hospital that acts as a medical referral centre for the northern region of peninsular malaysia with multiple disciplines of medical departments with 15 secondary specialist, 34 tertiary specialist, and 16 clinical support services. its facilities include 1,163 beds, 4749 staff and 24 hours operation. total electricity consumption for year 2020 is 22,412,620.00 at rm9,600,974.30. hospital pulau pinang is classified as a high energy consumption hospital. the energy consumption in malaysia increased rapidly every year, with an average of 2,533 gwh per year involving hospitals as major energy users [6]. three methods were involved: data collection from various documents such as monthly energy report, detailed energy audit (d.e.a), etc. secondly is the empirical evidence approach by on-site measurement using the energy monitoring system as per shown in figure 1. furthermore, to enhance the potential saving for the hospital, building energy simulation is used by implementing of the i.e.s. intelligent community lifecycle, which contains icd & ve software. figure 1. methodology of enhancing the potential smart building for hospital based on the review, the benefit of this paper has become relevant due to the impact of the energy performance mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 35 contracting and energy management on the sustainable and smart building solution. green building has become one the most widespread focus area in scholarly studies, governmental agencies, civil society, and building industries. many countries have set up their own green rating systems according to their appropriateness for the benefit of the populace and this progress is seen as a world’s target in greening the earth [3]. iii. results iii.1. building energy index (b.e.i.) in normal condition to determine the performance of the e.m.p. activities at each building or facility, the gross floor area (g.f.a.) is being used as a factor for the calculation of the building energy index (b.e.i.), and it is measured in the unit of kwh/m 2 /year. the b.e.i. can be used as an indicator to compare the building energy consumption against the floor area. by the end of every interval, the hospital’s management will know the hospital’s energy performance based on the b.e.i. as the indicator. from the figure 2. hospital pulau pinang has shown a significant decrease in b.e.i. this trend can prove the implementation of energy-saving measures. the hospital b.e.i. is usually higher than a typical office building. the new trend to design and build hospitals using sustainable technology, renewable resources and systems to reduce energy consumption and carbon emissions make it possible to achieve higher building performance. figure 2. building energy index for hospital pulau pinang from 2016 to 2021 (monthly energy report,2021) therefore, the hospital could respond in terms of reducing energy consumption, improving indoor air quality and creating a supportive healing environment. electricity consumption in commercial buildings requires serious attention as electricity is the predominant energy source used in these buildings. with increasing fuel price, consumers are now using electricity more wisely. [7]. iii.2. energy monitoring system for smart building intelligent buildings, historically and technologically, refer to the integration of four unique systems: building automation systems (b.a.s.), telecommunication systems, office automation systems and computer building management systems. the increasingly sophisticated b.a.s. has become the “heart and soul” of modern intelligent buildings. integrating energy supply and demand elements has become an important energy efficiency policy concept, often known as demand-side management (d.s.m). (in the sustainability program, the monitoring system is limited to the energy or kwh as per shown in figure 3. the energy monitoring system installation was first started in 2015 [8]. figure 3. type of monitoring system for energy at hospital. (monthly energy report,2021) an energy management system (e.m.s.) is a set of software tools used to monitor, control, and analyse a building’s energy consumption. any building should be considered an installation of ems for building with airconditioned space ≥ 4000 m 2 (malaysia standard on energy efficiency and use of renewable energy for non-residential buildings, 2014). this make hospital pulau pinang included as the air-conditioned space inside the building is 37.0%. the energy management system consists of several components: the main controller, intuitive controller, and set of energy measurement meters, as shown in the following figure. monitoring, analyze, and optimizing building’s energy consumption is of central importance for the renovation and energyefficient operation of buildings since it allows the identification and correction of inefficient energy usage. generally, e.m.s. has three main functions: control of equipment, monitoring of equipment, and integration of equipment sub-systems. the primary purpose of the control equipment is to save energy by (preferably realtime) optimisation system controls. the amount of digital power meter that has been installed for hospital pulau pinang is 178. the data from the digital power meter mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 36 (d.p.m.) will be transmitted to the intuitive controller. the intuitive controller will then transmit the data to the main controller for further e.a.c analysis for each d.p.m. scientist across the world is working on energy modelling and control to develop strategies that would reduce a building's energy consumption [9]. iii.3. energy conservation measure. (e.c.m.) hospital pulau pinang has benefited a lot from the program of sustainability program since a large amount of money has been invested wisely which helps energy saving such as air-conditioning and lighting retrofitting. figure 4. oil-free compressor for chiller system during retrofit program by energy performance contracting with zero initial capital cost more than rm2.8 million has been invested in the energy management program. figures 4 and 5 show a few examples of the activities that have been done to make sure energy saving is achieved. figure 5. chiller retrofit program through e.p.c. the energy service company (e.s.c.o.), are responsible for designing, supplying, installing, and maintaining the e.p.c. project for hospital pulau pinang. the e.p.c. contract period starts from 1st october 2019 until 31st march 2025. for the record, the physical installation period started 1st october 2019 to 31st march 2020. it was followed by a performance period from 1st april 2020 to 31st march 2025 with an expected guaranteed saving of 5,664,691 kwh/year or rm 2.3 million. this attractive and practical option can extensively contribute to energy savings and environmental benefits. it has been reported that such an intelligent building monitoring and control system can result in an approximately 20% savings in energy usage, a substantial step toward the realisation of smart building automation and management [10]. iii.4. digital twin technology traditionally, digital twins were used to improving the performance of a single asset such as a car, but more recently, digital twins have been applied to systems of assets or an entire organization [11]. a significant portion of the energy consumed in buildings is wasted mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 37 because of the lack of controls or the failure to use existing building automation systems (b.a.s.s) properly. much of the waste occurs because of our inability to manage and control buildings efficiently. over 90% of the buildings are either small-size (<5,000 sf) or medium-size (between 5,000 sf and 50,000 sf); these buildings currently do not use b.a.s.s to monitor and control their building systems from a central location [12]. over the past decades, detailed individual building energy models (b.e.m.) on the one side and regional and country-level building stock models on the other side have become established modes of analysis for building designers and energy policy makers, respectively [13]. hospital pulau pinang does have an energy monitoring system, but it is only limited to data presentation with no analysis or simulation can be generated from the system. it will be significant if the energy data can be analyzed, simulated, and presenting the data in the interactive platform. this attractive and practical option can extensively contribute to energy savings and environmental benefits. it has been reported that such an intelligent building monitoring and control system can result in an approximately 20% savings in energy usage, a substantial step toward the realisation of smart building automation and management [10]. nowadays, modelling and simulation are standard processes in system development, e.g. supporting design tasks or validating system properties. firstly, simulationbased solutions are realized during operation and service for optimized operations and failure prediction. in this sense, simulation merges the physical and virtual worlds in all life cycle phases [14]. for this case study, building modelling through digital twin technology uses software such as i.e.s. intelligent community lifecycle (i.c.l.) software can generate data and provide information to enhance energy performance analysis. the i.c.l. consists of intelligent community information model (icim), intelligent portfolio information model (ipim), intelligent community design (icd), intelligent control and analysis (iscan) and intelligent virtual network (ivn). scientist across the world is working on energy modeling and control to develop strategies that would reduce the building's energy consumption [9]. hospital pulau pinang building-related information can be collected and visualized as the digital twin of the hospital to the energy management committee with an interactive platform. now, building energy modelling and control is an interdisciplinary area of study, that involves concepts and studies of electrical and electronic engineering, mechanical engineering, civil engineering, and architecture [9]. miniaturization and price decline enable the integration of information, communication, and sensor technologies into virtually any product. products become able to sense their state and the state of their environment. paired with the ability to process and communicate, this data allows for the creation of digital twins. the digital twin is a comprehensive digital representation of an individual product that will play an integral role in a fully digitalized product life cycle [15]. iii.5. smart building energy simulation hospitals in malaysia have been exposed to the idea of industrial revolution 4.0 to operate the buildings with sustainable approaches. align with the government's intention to reduce greenhouse gas emissions, converting the existing hospitals into smart hospitals will contribute largely as the buildings that operate in hot and humid climates are currently using enormous amounts of energy consumptions to maintain the thermal comfort level reduce infection control rate. as the public hospitals have already implemented the energy management program across malaysia, they barely need a platform that enables monitoring and simulation. b.i.m. energy consumption analysis can compare different materials, examine the performance of various materials, and select the most suitable and most energy-efficient materials for building structure maintenance [14]. a new phase of energy monitoring is to leverage the digital twin technology, which will bring a new phase of the internet of things (iot) to the energy management program itself. the building energy simulation tools perform the heat balance calculation based on the physical properties of the building, such as the material, orientation, the mechanical systems operating in the building, and the dynamic inputs such as occupancy, lighting, weather, etc. building energy simulation tools have become a popular method to predict the behaviour of a building during the initial design stage. the building designers can optimise the building energy performance from predicted values early in the design stage [16]. figure 6. digital twin of hospital pulau pinang https://www.sciencedirect.com/topics/engineering/miniaturization https://www.sciencedirect.com/topics/engineering/product-life-cycle mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 38 energy efficient building digital twins (b.d.t.s) are researched using building information model (b.i.m.) to explore the key techniques of digital twins (dts) [16]. by using the i.e.s. intelligent community lifecycle software to create the three-dimensional digital twin of the hospital, the energy simulation can be produced and thus the building energy index (b.e.i.), cooling, energy consumption, lighting energy consumption in kwh/m 2 /year and annual carbon emission of the hospital in tco2 for hospital pulau pinang are generated in an interactive platform that can be accessed from web browser as per shown in figure 13. apart from active measures, much more energy-saving potential can still be explored through passive strategies. the simulation method is used to establish an energy baseline as the basis for predicting energy saving potential for passive strategies that cannot not be measured through an energy audit. combining of these methods is essential to optimise the potential of energy saving through active and passive strategies that have so far never been implemented in any public hospital in malaysia [17]. all information was generated by i.c.l. software and the digital twin for hospitals was modelled according to autocad & google maps. some information was taken with the help of a drone view. the results of energy simulation by software can be shown in table 1. table 1. . attributes summary of the hospital pulau pinang by simulation. hospital / indicator hospital pulau pinang average energy user intensity (e.u.i.) kwh/m 2 /yr 249.66 average cooling energy (kwh/m2/yr) 62.51 average lighting energy (kwh/m2/yr) 27.05 annual co2 emission (tco2) 28081 further enhancement of the energy conservation measure is taking place with the implementation and integration of the renewable energy system in the hospital buildings. by simulation of i.e.s. icd software, it can generate the best position of solar photovoltaic (p.v.) based on sun path, analyse the solar photovoltaic (p.v.) radiation, site solar photovoltaic (p.v.) electricity yield and furthermore simulate the potential total solar photovoltaic (p.v.) contribution. the capacity of the solar photovoltaic (p.v.) system will be sized according to the roof surface area of the hospital pulau pinang as can be shown in figure 7. figure 7. solar p.v. positions are generated by the icd solar assessment simulation. iv. discussion the energy report showed significant energy saving for the hospitals. the energy management system and utility bills show that the energy consumption from 2017 to 2021 is decreasing, and total energy saving can be summarized in the table below. approximately rm 7.3 million has been saved from 2017, and it can be concluded that the program was successful and has achieved its target as per table 2. table 2. total saving since 2017 until 2021. (monthly energy report, 2021) year total saving in ringgit (rm) equivalent 2017 rm1,475,023.25 2018 rm827,700.25 2019 rm285,189.10 2020 rm1,844,557.40 2021 rm2,876,843.50 overall rm 7,311,892.10 a smart hospital model can be utilized by energy management committee (e.m.c) for a particular hospital or even at the ministry level in putrajaya, and it can also be extended throughout the other hospital in malaysia. for the result of the simulation works, implementing the solar photovoltaic (p.v.) at the best possible location as recommended in the software. it can be further improve energy saving by contributing about 5,130,000 kwh more to the existing saving that the hospital has achieved. in terms of carbon emission reduction, if the hospital implements the solar p.v. as per simulation, approximately about 3,801 tco²e can be offset from the total carbon emission. all the results from the simulation can be analyzed and visualized to the hospital management levels in an interactive dashboard. mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 39 v. conclusion after all, achieving the energy-saving for at large hospital is not an easy task and it has been shown that large hospitals such as the hospital pulau pinang needed almost five years to achieve such energy savings. the right policy and top management trust in the energy committee to fulfil the program are critical factors. driven by the high standard in concession agreement requirement, a journey for the smart building is in the proper structure, and steady investment is needed to see this program continuously improve in the next phase, renewable energy, particularly solar energy. for more than a 5-year energy management program, this hospital needs few more investments in retrofitting the hvac. they can look for solar p.v. to improve energy saving in the future as recommended by the simulation to further enhance the potential for smart building. the ability to assess, monitor, analyses and manage these public hospitals energy consumption throughout malaysia is a sustainable approach to make the idea of smart hospital. implementation of digital twin technology by i.e.s. software can help the committee decide on the suitable investment for energy-saving measures and monitor the energy data from the fingertips. the enormous amount of energy-saving from large hospitals, which have never undergone any energy management program, will significantly succeed with the right and structured policy and management. hopefully, the figure and exposure from this review can inspire any type of building to achieve the same goals as hospital pulau pinang. acknowledgements thanks to all the person that involve in this review and case study that eventually will help the hospital in malaysia to maximize their potential to become a smart building. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] j. wong, h. li, s. wang, “intelligent building research: a review, automation in construction,” vol. 14, no. 1, 2005, pp. 143–159, https://doi.org/10.1016/j.autcon.2004.06.001 [2] ministry of health malaysia (m.o.h.). “concession agreement in respect of provision of hospital support services at contract hospital”. ministry of health malaysia, putrajaya, 2015. [3] shaza rina sahamir, rozana zakaria, “green assessment criteria for public hospital building development in malaysia”, procedia environmental sciences, vol. 20, 2014, pp. 106-115, https://doi.org/10.1016/j.proenv.2014.03.015 [4] s. moghimi, f. azizpour, s. mat, c. h. lim, e. salleh, k. sopian, “building energy index and end-use energy analysis in large-scale hospitals—case study in malaysia,” energy efficiency, vol. 7, 2014, pp. 243–256, https://doi.org/10.1007/s12053-013-9221-y [5] jonas allegrini, kristina orehounig “a review of modelling approaches and tools for the simulation of district-scale energy systems,” a review of modelling approaches and tools for the simulation of district-scale energy systems, vol. 52, 2015, pp. 1391-1404, https://doi.org/10.1016/j.rser.2015.07.123 [6] sung c.t.b., 2016, “electricity demand, economic growth, and sustainable energy resources in malaysia”. extraordinary mind discuss ideas, pp. 1-8 [7] ahmad sukri ahmad, m. y. hassan, h. abdullah, h. a. rahman, m. s. majid and m. bandi, “energy efficiency measurements in a malaysian public university,” ieee international conference on power and energy (pecon), kota kinabalu, 2012, pp. 582-587, doi: 10.1109/pecon.2012.6450281 [8] v.s.k.v. harish n, arun kumar, “a review on modeling and simulation of building energy systems,” renewable and sustainable energy reviews, vol. 56, 2016, pp. 12721292, https://doi.org/10.1016/j.rser.2015.12.040 [9] srinivas katipamula, ronald m underhill, james k. goddard, danny j taasevigen, m a piette, j. granderson, rich e. brown, steven m lanzisera, t kuruganti, “technical report: smalland medium-sized commercial building monitoring and controls needs: a scoping study,” pacific northwest national laboratory (u.s.), 2012, pp. 1-4, https://doi.org/10.2172/1063081 [10] christoph f. reinhart, carlos cerezo davila, “urban building energy modeling – a review of a nascent field,” building and environment, vol. 97, 2016, pp. 196-202, https://doi.org/10.1016/j.buildenv.2015.12.001 [11] d. james, k. marcus, b. vladimir, “specification of an information delivery tool to support optimal holistic environmental and energy management in buildings”, national conference of ibpsa-usa, 2008, pp. 61-68, [12] s. boschert, r. rosen, “digital twin—the simulation aspect. in: hehenberger p., bradley d. (eds) mechatronic futures. springer, cham, 2016, https://doi.org/10.1007/978-3-319-32156-1_5 https://www.sciencedirect.com/journal/automation-in-construction https://www.sciencedirect.com/journal/renewable-and-sustainable-energy-reviews https://www.sciencedirect.com/journal/renewable-and-sustainable-energy-reviews https://doi.org/10.1016/j.rser.2015.12.040 https://www.osti.gov/search/author:%22katipamula,%20srinivas%22 https://www.osti.gov/search/author:%22underhill,%20ronald%20m%22 https://www.osti.gov/search/author:%22goddard,%20james%20k%22 https://www.osti.gov/search/author:%22goddard,%20james%20k%22 https://www.osti.gov/search/author:%22taasevigen,%20danny%20j%22 https://www.osti.gov/search/author:%22piette,%20m%20a%22 https://www.osti.gov/search/author:%22granderson,%20j%22 https://www.osti.gov/search/author:%22brown,%20rich%20e%22 https://www.osti.gov/search/author:%22lanzisera,%20steven%20m%22 https://www.osti.gov/search/author:%22kuruganti,%20t%22 https://digital.library.unt.edu/search/?q4=%22pacific%20northwest%20national%20laboratory%20%28u.s.%29%22&t4=dc_publisher&src=ark&searchtype=advanced https://digital.library.unt.edu/search/?q4=%22pacific%20northwest%20national%20laboratory%20%28u.s.%29%22&t4=dc_publisher&src=ark&searchtype=advanced https://doi.org/10.2172/1063081 mohd faisal baharuddin et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 33-40 page 40 [13] sebastian haag, reiner anderl, “digital twin – proof of concept,” manufacturing letters, vol. 15, 2018, pp. 64-66, doi:10.1016/j.mfglet.2018.02.006 [14] weixi wang, han guo, xiaoming li, “deep learning for assessment of environmental satisfaction using bim big data in energy efficient building digital twins,” sustainable energy technologies and assessments, vol. 50, 2022, pp.101897, https://doi.org/10.1016/j.seta.2021.101897 [15] muhamad zahin mohd ashhar, lim chin haw, “recent research and development on the use of reflective technology in buildings – a review,” journal of building engineering, vol. 45, 2022, pp.103552, https://doi.org/10.1016/j.jobe.2021.103552 [16] muhamad zahin mohd ashhar, lim chin haw, “recent research and development on the use of reflective technology in buildings – a review,” journal of building engineering, vol. 45, 2022, pp. 103552, https://doi.org/10.1016/j.jobe.2021.103552 [17] n. abd rahman, c. lim , a. fazlizan , “optimising the energy saving potential of public hospital through a systematic approach for green building certification in malaysia,” journal of building engineering, vol. 43, 2021, pp. 103088, https://doi.org/10.1016/j.jobe.2021.103088 https://doi.org/10.1016/j.mfglet.2018.02.006 https://doi.org/10.1016/j.jobe.2021.103552 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 1. 2022 page 28-35 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 28 switched capacitor nine-level inverter with reduced components for grid connected pv systems using fuzzy logic controller h. aboub 1* , r. mechouma 1 , b. azoui 1 1 dept. of electrical engineering, laboratory leb, university of batna 2, batna, algeria * corresponding author e-mail: haniaaboub @gmail.com abstract – the novel use of a three-phase switched capacitor sc nine-level inverter in a pv system is described in this article. it has a low input voltage, fewer components, and is gridconnected. the primary benefit of the suggested inverter is high voltage gain, which is attained by switching capacitors in series and parallel to raise the output voltage with the proper switching management. it is simpler to design a fuzzy logic controller to increase the infusion of solar energy into the electrical network. the matlab/simulink environment's findings demonstrate that the suggested fuzzy logic controller performs well under a range of illumination levels. in comparison to the traditional pi controller, the total harmonic distortion (thd) obtained is less than the limit of 0.67 %. good spectrum analysis and strong performance with fewer components are made possible by the nine-level sc inverter. keywords: photovoltaic pv, fuzzy logic controller flc, switched capacitor inverter sci, multi carriers spwm , thd received: 28/04/2022 – revised 25/05/2022 – accepted: 03/06/2022 i. introduction because they provide effective ways to reduce pollution by using less fossil fuels, photovoltaic grid-connected systems have grown in importance across the globe [1 3]. multilevel inverters have been acknowledged as a significant alternative to the typical two-level voltage source inverter [4], particularly in high pv power applications. these inverters can produce higher output voltages, which should be sinusoidal with lower switching frequency and lower total harmonic distortion [5,6]. three categories—neutral point clamped npc, flying capacitor fc, and cascaded h-bridge inverter—are used to classify common multilevel inverters in the literature [7,8]. an excessive number of diodes and unbalanced operation of dc-link's voltage divider capacitors are the major problems of npc topology, [911]. similar to this, the maximum output voltage of a flying capacitor multilayer inverter is equal to half of the dc input voltage. the cascaded h-bridge multilevel converter topology, on the other hand, necessitates a separate dc source for each h-bridge [12], and a separate dc source for each phase compared to npc and fc inverters [13]. furthermore, all these multilevel inverters' topologies need more components and high input voltage pv sources in high voltage applications [14]. as a consequence, it is appropriate to improve the boost dc/dc converter with a higher conversion ratio or involve more numbers of pv cells in series [15]. therefore, designing a particular topology for mlis that has a less number of components and uses a lower dc voltage supply that is the switched-capacitor converter (scc). this structure can be used as a multilevel converter coupled with conventional inverters to produce multi-level ac waveforms, or it can be utilized as a steph. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 29 up converter. additionally, this inverter switches the capacitors in series and parallel by carefully choosing the switching control, resulting in output voltages that are higher than the input voltage. moreover, many modulation techniques can be applied to drive a multilevel switched-capacitor inverter such as space vector modulation, selected harmonic elimination (she), and sinusoidal pulse width modulation (spwm). for the last decade, many types of research are conducted on the new topology of switched-capacitor inverters. a novel topology of a seven-level switchedcapacitor inverter using the spwm technique was presented. also, a comparative study of seven-level switched-capacitor inverters using the same technique was applied for a very low input voltage. in addition, a single phase five-level switched capacitor inverter for autonomous pv system applications without batteries has been implemented in a study [12], where the main objective is the test of a single phase nine-level switchedcapacitor converter in low pv energy with a simple harmonic elimination technique. the authors also presented a switched-capacitor nine-level inverter with a modified hybrid modulation technique [16,17]. this paper aims to study a grid connected pv system based on a nine-level switched-capacitor inverter with spwm technique controlled by a fuzzy logic controller. the remainder of the paper is organized as follows: the structure of a switched capacitor multilevel inverter is illustrated in section ii. in section iii, an explicit model control of the different sub-systems is described. section iv shows a set of simulation results of the pv side. the results of the nine-level switched-capacitor inverter are discussed in this section. finally, section v concludes this work. ii. material and method ii.1. proposed switched capacitor nine level inverter description the proposed switched-capacitor multilevel inverter is seen in figure 1 in its current configuration. it is created by cascading a switched capacitor network and a two level (full bridge) inverter. this must first be converted to a high dc voltage before being converted to an alternating current. figure 1. topology of three phase switched-capacitor nine level inverter scmli this topology can be used to get any number of levels with the help of series-parallel conversion operations. it consists of some switched-capacitor sc cells, each sc cell has one capacitor and two switches. several output voltage levels can be obtained from one input voltage. therefore, assuming the number of capacitors is equal to n, the balanced voltage of each capacitor is to be provided by the equation that follows [14]: for k = 1, 2,.., n (1) therefore, the maximum value of the output voltage ( ) and the number of generated output voltage levels ( ) are calculated with respect to n, using the following equations respectively: ( ) (2) ( ) (3) as a result, the switched capacitor nine-level inverter is composed of one voltage source from solar panels (vpv), 3 diodes, 3 capacitors and 8 switches (power igbt) [16,19]. the capacitors are charged when they are linked in parallel with the sources of the input voltage. the capacitors discharge when they are connected in series. the output voltage of nine level sci can be four times higher than the input voltage. table 1 summarizes the switching states of various switches and capacitors for each mode in the proposed multilayer inverter. h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 30 table 1. switches and capacitors’ states the letters c and d in table 1 stand for the charging and discharging modes for capacitors, respectively, while the numbers 0 and 1 stand for the off and on switching states. the following modes provide the expression for the output dc bus voltage: mode 1: capacitor c1 is charged to vin when switch s6 is turned on. this voltage level is concurrently transferred to the output by switches s1 and s2. the expression of the output dc bus voltage is: (4) mode 2: through switch s7, the capacitor c2 is charged from vin and voltage across the capacitor c1 (capacitor c1 is gone discharged). the second level of the output dc bus voltage is generated through s1, s2 and s3: (5) mode 3: in this mode, the capacitor c3 is charged by vin+vc2 through switch s8 and the discharge of c2. three voltage levels are concurrently created at the output through s1 and s3, and they equal 3vin: (6) mode 4: in this mode, without adding another capacitor to the circuit, switch s1 and s8 allow to transfer of the 4vin voltage level into output by the stored voltage of c3 and the input voltage source as shown below [16]: (7) it is important to note that, at this moment, c1is again charged directly by the dc voltage source for the next voltage level and this consecutive operation continues so on [20]. iii. results and analysis iii.1. grid connected pv system design and modeling based on 9-level scmli topology a dc/dc boost converter is used to extract the maximum power point by a fuzzy logic controller, and a dc-ac nine-level switched-capacitor inverter scmli can inject pv power into the grid with an rlc filter. figure 2 shows the architecture of the proposed gridconnected pv system. it consists of a photovoltaic solar array of 5 kw for each phase, which is made up of five strings of 13 modules each. a fuzzy logic controller was utilized to regulate the current output pumped into the grid in order to control the switching patterns of the 9l sci. figure 2. architecture of grid connected pv system with three phase switched-capacitor nine level inverter scmli different components models are shown as follows: 1 under any condition, the photovoltaic module's (ipv) current is provided by [21]: [ [ ] ] (8) ui2-the boost converter is made up of two different variables (il, vc ).the model will be as follows: [ ] [ ] [ ]+[ [ ] (9) 3 in order to maximize the energy extracted from the pv array, a fuzzy logic control was used to generate the required cyclic ratio d of dc/dc boost converter corresponds to mpp for any change in temperature or irradiance. 4the control of dc-link voltage: in the present architecture, applying kirchhoff current law at the dc-link between the inverter and boost converter it yields capacitors states c1 c d c d c2 c d c c3 c d switches states s1 1 1 0 1 s2 1 1 1 0 s3 0 1 0 0 s4 0 0 1 0 s5 0 0 0 1 s6 1 0 0 0 s7 0 1 0 0 s8 0 0 1 0 h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 31 where: is the boost output current known as is the input of inverter current: is the dc-link capacitor. so: ̇ in the present work, a fuzzy logic controller is proposed to regulate the dc link voltage of the pv interface system. the output of flc gets the value of the reference network current. 5to controller the three phase sc inverter, a virtual biphase system can be used, the d-q rotating frame is represented in the fallowing equations [22,23]: { the expression of active and reactive power of grid can be represented by using the components of park voltages after the filter and the currents of the grid [22,23]: ( ) ( ) 6. fuzzy logic control strategy of nine-level switchedcapacitor inverter : semiconductor devices must be turned on and off in such a way that the desired fundamental is obtained with the least amount of harmonic distortion in order to synthesise a multilevel ac voltage output utilizing various levels of dc inputs. there are numerous methods for choosing switching methods for multilayer inverters. to produce n-level inverter output voltage, the scmli topology requires (n-1/2) carrier signals. it is based on a comparison between each carrier signal and a sinusoidal reference waveform. the active devices corresponding to that carrier are turned on if the reference wave is greater than a carrier signal. if not, the gadgets are turned off. in order to create the gating pulses for each switch in the 9l-sci control system, the control system produced four carrier signals and compared them to the reference voltage (vref). in order to provide sinusoidal output, the output of this nine-level inverter is sent to the load and grid through an lc filter. figure 3. block diagram for pwm with fuzzy logic controller the control circuit of the proposed inverter is shown in figure 3. it is based on the use of flc control in a closed loop the fuzzy logic controller design is mainly involved three steps: fuzzification, which allows the passage from the real domain to another fuzzy domain. the second block is devoted to the inference rules, while the last block is dedicated to the defuzzification part, to return to their al domain. this last operation uses the center of gravity, widely used, to determine the value of the control output. both direct and quadratic currents grid fuzzy logic controller are shown in figure 4. figure 4. dq-axis current fl control scheme { (10) at each instant, the controller fc produces the variation of δ , δ according to the difference between the two inputs and , respectively: { ( ) ( ) ( ) ( ) (11) where: -the current is generated also by a fuzzy logic controller according to the produced pv power. -the current the is estimated in term of reactive power reference using the following equation: h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 32 iii.2. simulation of the overall system this section displays the various simulation results that were obtained using the matlab/simulink environment. the intensity of sunlight is considered to be varied between 500 and 1000 w/m 2 as shown in figure 5, and variation in the load power is shown in figures 6 to figure 16 supporting the performance of the fuzzy logic controller on the ac side. figure 5. variation of irradiation levels figure 6. power of load power the results of simulations of the overall system is shown in following figures: figure 7. power of load power figure 8. input voltage of nine-level sci figure 9. comparison of direct current grid of flc and pic figure 10. quadratic grid current of flc figure11. grid current of phase a with flc h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 33 figure 12. three phase grid current figure 13. output voltage of 9 l switched capacitor inverter (a) (b) figure 14. nine-level sc inverter fft analysis of the voltage of the phase "a(a): with pi controller and (b): with fl controller figure 15. voltage and current grid of phase a (a) (b) figure 16. fft analysis of the grid current : (a): with pi controller and (b): with fl controller iii.3. discussions of the results during the first interval [0 à 0.3], the all generated pv power injected to the grid, at 0.3s occurs the first step change in the load power from 0 to 5kw, this change leads to a small undershoot in vdc over its reference with flc compared with pi controller as shown in figure 8. at 0.8s an increase in the load demand is greater than the energy produced by the photovoltaic generator. in this case, the surplus of the power load from the electrical network is covered as observed in figures 7 and 9. the phase change at this moment is visible as seen in figures 11 and 12 since the grid current reflects its direction. there is no energy sent to the network because it can be seen at the field between 1 and 1.5 that the energy generated equals the energy needed for the load. as a result, the electrical network's current in this entire field is practically zero. in addition, it can be noted in figures 9 and 10 that flc always gives a better result than the pi for any change, whether in irradiance of the sun or the power load. also figures 15 and 16 show that the current grid with pi controller has a sinusoidal waveform with 0.28 thd per cent for current, this result can be reduced by using the fl controller to 0.19%. furthermore, it can be noted in figures 13 and 14 that the voltage of output 9l-sci has a waveform stairway shape with a peak value of 400v= 4*vin. the fast fourier transform (fft) analysis gives an acceptable value of thd. h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 34 iv. conclusion nine level switched-capacitor inverter 9lsci was proposed to inject pv power into the grid.  this inverter can produce a high gain voltage which is increasing four times the output voltage by using low voltage input ( 100 v ) with a minimum number of components.  the efficiency of the fuzzy logic controller is very satisfying with a reduced number of harmonic of 0.67% in efficiency obtained while compared to the classic pi controllers, and it achieves high quality outputs, and low thd an improvement. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] m. rabiaa, a. hania, a. boubakeur, ―multicarrier wave dual reference very low frequency pwm control of a nine levels npc multistring three phase inverter topology for photovoltaic system connected to the medium electric grid, ‖ j. electr. eng, vol. 16, no. 2, pp. 293–8, 2020. doi: 10.1109/upec.2014.6934666 [2] h. aboub, r. mechouma, b. azoui, c. labiod, a. khechekhouche, ―a new multicarrier sinusoidal pulse width modulation (spwm) strategy based on rooted tree optimization (rto) algorithm for reducing total harmonic distortion (thd) of switched-capacitor ninelevel inverter in grid-connected pv systems,‖ indonesian journal of science & technology, vol 7, no 1, 2021. https://doi.org/10.17509/ijost.v7i1.41716 [3] a. nouaiti, a. saad, a. mesbahi, m. khafallah, ―implementation of a single phase switched-capacitor nine-level inverter for pv system applications with selective harmonic elimination,‖ int. j. comput. appl, vol. 168, no.7, pp. 9–15, 2017. 10.5120/ijca2017914416. [4] m.a. husain, a. tariq, s. hameed, m.s. bin arif, a. jain, ―comparative assessment of maximum power point tracking procedures for photovoltaic systems, ‖ green energy environ, vol. 2, no.1, pp. 5–17, 2017. 10.1016/j.gee.2016.11.001. [5] m. derakhshanfar, ―analysis of different topologies of multilevel inverters,‖ international journal of engineering research & technology (ijert), vol. 2, no. 9, pp. 304– 9, 2010. [6] k. oliveira, j. afonso, m. cavalcanti, k. oliveira, j. afonso, m. cavalcanti, m. inverter, f. function, s. tomic, ―multilevel inverter for grid-connected photovoltaic systems with active filtering function to cite this version : hal id : hal-01348766 multilevel inverter for grid-connected photovoltaic systems with active filtering function, ‖ international journal of engineering research & technology (ijert), vol. 6, no. 05, pp. 752-758, 2016. http://dx.doi.org/10.17577/ijertv6is050454. [7] p. pany, r.k. singh, r.k. tripathi, ―performance analysis of fuel cell and battery fed pmsm drive for electric vehicle application, ‖ icpces 2012 2012 2nd int. conf. power, control embed. syst, 2012. 10.1109/icpces.2012.6508118. [8] j. rocabert, j. crébier, j. peracaula, j. rocabert, j. crébier, j.p. ―diode-clamped, diode-clamped multilevel converters with integrable gate-driver power-supply circuits,‖ to cite this version : hal id : hal-00422539 diode-clamped multilevel converters with integrable, 2009. https://hal.archives-ouvertes.fr/hal-00422539 [9] sharifzadeh, mahdi, alexandra sikinioti-lock and nilay shah. ―machine-learning methods for integrated renewable power generation: a comparative study of artificial neural networks, support vector regression, and gaussian process regression‖ renewable and sustainable energy reviews, vol. 108, pp. 513–38, 2019. 10.1016/j.rser.2019.03.040. [10] s.r. teja, p.u. sankar, y. rajkumar, ―switched capacitor seven-level inverter,‖ international journal of pure and applied mathematics, vol.114, no.12, pp. 535–43, 2017. [11] y. hinago, h. koizumi, ―a switched-capacitor inverter using series/parallel conversion with inductive load,‖ ieee trans. ind. electron, vol. 59, no 2, pp. 878–87, 2012. 10.1109/tie.2011.2158768. [12] a. nouaiti, a. saad, a. mesbahi, m. khafallah, ―experimental implementation of a low-cost single phase five-level inverter for autonomous pv system applications without batteries,‖ eng. technol. appl. sci. res. vol. 8, no 1, pp. 2452–2458, 2012. doi: 10.48084/etasr.1675 [13] m. baldé, m.l. doumbia, a. chériti, c. benachaiba, ―comparative study of npc and cascaded converters topologies,‖ renew. energy power qual. j. vol. 1, no 9, pp. 185–190, 2011. 10.24084/repqj09.282. [14] p.s. bhagyalakshmi, b.m. varghese, j. joy, ―inverters using sinusoidal multicarrier pwm technique,‖ international journal of advanced research in electrical, electronics and instrumentation engineering, vol. 5, no 10, pp. 8145–8154, 2016. 10.15662/ijareeie.2016.0510053. [15] b. yang,, w. li, y. gu, w. cui, x. he, ― improved transformerless inverter with common-mode leakage current elimination for a photovoltaic grid-connected https://doi.org/10.17509/ijost.v7i1.41716 h. aboub et al. / international journal of energetica (ijeca) vol. 7, n°1, 2022, pp. 28-35 page 35 power system,‖ ieee trans. power electron, vol. 27, no 2, pp. 752–762, 2012. 10.1109/tpel.2011.2160359. [16] h.n. avanaki, r. barzegarkhoo, e. zamiri, ―a switchedcapacitor multilevel inverter for grid-connected pv systems with mppt ability and reduced components,‖ 9th annu. int. power electron. drive syst. technol. conf. pedstc, pp. 224–230, 2018. 10.1109/pedstc.2018.8343800. [17] e. zamiri, r. barzegarkhoo, b. karami, s.h. hosseini, ―a hybrid switched-capacitor multilevel inverter with self charge balancing and less number of switches,‖ 6th annu. int. power electron. drive syst. technol. conf. pedstc, pp. 573–578, 2015. 10.1109/pedstc.2015.7093338. [18] b. karami, r. barzegarkhoo, a. abrishamifar, m. samizadeh, ― a switched-capacitor multilevel inverter for high ac power systems with reduced ripple loss using spwm technique,‖ 6th annu. int. power electron. drive syst. technol. conf. pedstc, pp. 627–632, 2015. 10.1109/pedstc.2015.7093347. [19] n. sandeep, u.r. yaragatti, ―a switched-capacitor-based multilevel inverter topology with reduced components,‖ ieee trans. power electron, vol. 33, no. 7, 2018. 10.1109/tpel.2017.2779822. [20] m. saeedian, e. pouresmaeil, e. samadaei, e.m. godinho rodrigues, r. godina, m. marzband, ―an innovative dualboost nine-level inverter with low-voltage rating switches,‖ energies, vol. 12, no. 2, pp. 1–15, 2019. 10.3390/en12020207. [21] m. maamir, o. charrouf, a. betka, m. sellali, m. becherif, ―neural network power management for hybrid electric elevator application,‖ math. comput. simul, vol. 167, pp. 155–175, 2020 https://doi.org/10.1016/j.matcom.2019.09.008 [22] m. kermadi, z. salam, e.m. berkouk, ―an adaptive sliding mode control technique applied in grid-connected pv system with reduced chattering effect,‖ ieee conf. energy conversion, cencon, pp.180–185, 2017. doi: 10.1109/cencon.2017.8262480 [23] u. yilmaz, a. kircay, s. borekci, ―pv system fuzzy logic mppt method and pi control as a charge controller,‖ renew. sustain. energy rev. vol. 81, pp. 994–1001, 2018. https://doi.org/10.1016/j.rser.2017.08.048 https://doi.org/10.1016/j.matcom.2019.09.008 https://doi.org/10.1016/j.rser.2017.08.048 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 01-07 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 1 heat exchanger design for the production of synthesized gold nanoparticles thyta medina salsabila erlangga 1* , asep bayu dani nandiyanto 2 , risti ragadhita 3 , teguh kurniawan 4 1,2,3 departemen kimia, universitas pendidikan indonesia, indonesia 4 departemen teknik kimia, universitas ageng tirtayasa, indonesia * corresponding author e-mail: nandiyanto@upi.edu abstract – this study aims to develop and analyze the design of heat exchangers in the production of gold nanoparticles (aunps) by the biosynthesis method using sargassum horneri (sh) extract. the simple design of this heat exchanger (he) uses the shell and tube type, the onepass tube, and the fluids are water. these specifications pertain to the design of a heat exchanger (he). the tube length of 4.267 m, shell diameter of 254 mm, outer tube diameter of 22.225 mm, inner tube diameter of 21.184 mm, and wall thickness of 2.1082 mm describe the physical dimensions of the tubes in the heat exchanger. the pitch tube of 31.75 mm refers to the distance between the centers of adjacent tubes in the heat exchanger. based on manual calculations using microsoft excel, the results show that this design has laminar flow as indicated by the reynolds value. in addition, the he designs has an effectiveness value of 98.98% with an ntu value of 11.50. in this study, the he designs results have a high effectiveness value, so it can be considered effective for use in producing gold nanoparticles with sh extract. therefore, this he designs analysis can be used as a learning medium in the he designs process, the operating mechanism, and the performance analysis of the he. keywords: reynolds number, shell and tube, specific heat capacity, sargassum horneri. received: 03/10/2020 – revised: 20/11/2022 – accepted: 10/12/2020 i. introduction the heat exchanger (he) is a device that transfers thermal energy, especially heat, between two streams at different temperatures. it is widely used in industrial processes as an integral part of the process or for heat recovery. heat exchangers are essential components in processing, power production, power generation, transportation, refrigeration, electronics, chemical or food industries, and manufacturing [1-2]. one of the existing heat exchanger types is shell and tube. the shell and tube-type heat exchangers were used in many applications. as its name suggests, this type consists of a large cylindrical reservoir (shell) at high pressure and a bundle of tubes inside it. this exchanger utilizes two fluids, where one fluid is permitted to flow in the tube and the other fluid flows outside the tube (in the vessel). the fluid runs through the tubes and the hot stream flows on the tubes and inside the shell [2-3]. the existence of this heat exchanger can then be utilized in the production process of nanoparticle materials, including gold nanoparticles (aunps). gold nanoparticles have unique optical, electronic, and thermal properties that depend on their size and shape, making them useful in a variety of fields, such as biomedicine, electronics, and catalysis. due to their small size, gold nanoparticles exhibit different properties than bulk gold and can be used to create new materials with specific desired properties. their biocompatibility and stability make them particularly attractive for use in medical applications, such as imaging and drug delivery [4]. gold nanoparticles are getting more attention because of their excellent plasmonic properties, ease to synthesize, ability to functionalize with different thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 2 materials for the desired purpose, low toxicity, high biocompatibility, and easy access to their nano dimensions [5]. based on these advantages, gold nanoparticles are widely used as catalysts [6–8], biosensors [9-10], x-ray imaging [11], drug delivery [12], bioelectric devices [13], and so on. currently, many researchers have developed gold nanoparticle synthesis. there are various techniques for carrying out the synthesis of aunps by dividing them into chemical, physical, and biological techniques [14]. the use of biological techniques to synthesize gold nanoparticles using plant species is a green and ecofriendly alternative to traditional chemical methods. this approach has the advantage of being less hazardous, as it reduces or eliminates the use of toxic chemicals [15]. several studies have carried out the biosynthesis of gold nanoparticles using citrus limetta risso peels [16], tecoma capensis [17], ceiba pentandra leaves [18], punica granatum peels [19] gracilaria crassa leaves [15], sargassum horneri [7], dittrichia viscosa [20], annona muricata leaves [21], galaxaura elongata [21], musa acuminata colla flowers [22], persea americana fruit peel [23], etc. the extracellular biosynthesis of gold nanoparticles using plant extracts or whole plants offers several advantages over other methods of nanoparticle synthesis. the ability to control the size, shape, and dispersion of the nanoparticles is important for optimizing their properties and applications.the plants used can also be increased for the large-scale synthesis of nanoparticle materials [24]. therefore, this study aims to design a heat exchanger to produce gold nanoparticles. as a model for the heat exchanger design, in this study, we use the process of producing gold nanoparticles with biological techniques or biosynthesis using sargassum horneri (sh) extract which has been done before [7]. the type of heat exchanger designed in this article is the shell and tube type. the heat exchanger selection represents significant importance in the design of the heat recovery system. it is essential to design the type of heat exchanger with the maximum degree of compactness concerning process parameters such as temperature, process fluid composition, proximity to impurities, and potential operational problems [25]. the study of the specifications of a heat exchanger can provide valuable insights into the design and performance of heat exchangers on an industrial scale. it can serve as a reference for engineers and designers, who can use the information to optimize the design of heat exchangers, improve their efficiency, and address any potential performance issues. ii. methodology the method followed in the study is likely based on the protocol described by [7]. in the manufacture of gold nanoparticles only a few materials are needed, such as sargassum horneri extract, ethanol, hydrogen tetrachloroaurate (iii) trihydrate, haucl4.3h2o. ii.1. gold nanoparticle synthesis the gold nanoparticle biosynthesis process is shown in figure 1 and the process flow diagram is shown in figure 2. the production of gold nanoparticles begins by adding 1 ml of filtered sh extract (2 mg/ml) to a haucl4.3h2o (1 m) solution, then incubating for 15 minutes at 80°c in water. after 15 minutes, the colloid tube was cooled for 5 minutes. the change in the color of the suspension to dark purple indicated the success of sh-aunps biosynthesis. the specific details of the procedure can be found in the study referenced in [7]. figure 1. schematic diagram of the gold nanoparticles biosynthesis. figure 2. process flow diagram of sh-aunps manufacturing. thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 3 ii.2. mathematical model on heat exchanger design the fluid characteristics assumptions used in the heat exchanger are presented in table 1. some of these assumptions are used to design shell and tube-type heat exchangers. the hot fluid enters the heat exchanger at a temperature of 80°c and leaves at a temperature of 30°c, while the cold fluid enters at a temperature of 10°c and leaves at a temperature of 20°c. the incoming water flow rate for the hot fluid is 3.05 kilograms per second, and the incoming water flow rate for the cold fluid is 2.2 (kg/s). the process of collecting specification data for a thermal analysis typically involves manual calculations using mathematical equations (1-15) [26]. the heat exchange parameters are calculated according to table 2. basic parameters calculation for heat exchanger shows by equation 1-4. to measure the energy transferred (q), some variables need to be determined, as mentioned below. where, q is the energy transferred (wt), m is the mass flow rate of the fluid (kg/s), cp is the specific heat, and δ is the fluid temperature difference (°c). to calculate the logarithmic mean temperature differenced (lmtd) the result has to be determined by: where, is temperature of the hot fluid inlet (°c), is temperature of the hot fluid outlet (°c), is temperature of the cold fluid inlet (°c), and is temperature of the cold fluid outlet (°c). to measure the heat transfer field area (a), it has to be determined using below equation. where is the energy transferred (w) is the overall heat transfer coefficient, and is the logarithmic mean temperature difference (f). to determine the number of tube (nt) use the eq. 4. where, a is the heat transfer area (ft 2 ), l is the length of tuber, and a is the outer surface area (ft/ft 2 ). shell and tube parameters calculation for heat exchanger shows by equation 1-4. to calculate the surface are of heat transfer in tube (at), it can be determined by this equation below. where, is the flow area in the tube (m 2 ) and the number of passes. the result of will use to calculate mass flow rate of water in tube ( ). these two values were needed to calculate the reynolds number. the reynolds number can be determined by using eq. 7, where 𝜇 is the dynamic viscosity of the fluid in the tube. 𝜇 prandtl number (pr) in the tube can be determined by using eq. 8, where k is the thermal conductivity of the tube material. ( 𝜇 ) the value of reynolds number and prandtl number was used to determine the nusselt number (nu). actual overall heat transfer coefficient (uact) can be determined by using eq. 10. where, is inside heat transfer coefficient, is outside heat transfer coefficient, and δ is wall thickness. to measure the hot and cold fluid rate, it has to be determined using the eq. 12 as mentioned below. where, is hot fluid rate (w/k), is specific heat capacity (j/kg k), and is mass flow rate of hot fluid (kg/s). this calculation also applied to calculate the cold fluid rate. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 4 when, is cold fluid rate (w/k), is specific heat capacity (j/kg k), and is mass flow rate of cold fluid (kg/s). this result used as . number of heat transfer units, ntu can be determined by using eq. 13. heat exchanger effectiveness, ε can be determined by using eq. 14. is actual energy transferred, is temperature of the hot fluid inlet and is temperature of the cold fluid inlet. table 1. physical and thermal properties of the fluid. hot fluid water at 80°c cold fluid water at 10°c thermal conductivity, λ (w·m -1 ·k -1 ) 0.671 0.585 viscosity, v (mm 2 ·s -1 ) 0.000339 0.00131 heat specific, cp (j·kg -1 ·k -1 ) 4193 4195 density, ρ (g·l -1 ) 971.6 999.2 iii. results and discussion the study used sh extract as a reducing and capping agent for the synthesis of aunps (gold nanoparticles) [7]. the synthesis of nanoparticles using algae or microorganisms is a fast, harmless, cost-effective, and environmentally friendly method, and by controlling the synthesis time and temperature, it is possible to reduce the size of the nanoparticles and increase their dispersion. [21]. the design of the heat exchanger for sh-aunps, begins with selecting cold and hot fluids. in this study, water was used as cold and hot fluids. water is the most popular base fluid for heat transfer in various industries. this is because water has a high specific heat, widely available, and cheap [2]. therefore, the physical and thermal properties of the two fluids are needed in designing a heat exchanger, as shown in table 1. the calculation results, using equations 1-15, show that the heat exchanger operates on the production of shaunps, based on the data obtained and adjusted for the fluid in the hot and cold water, as shown in table 2. the he designs concept calculates the temperature difference between the hot fluid temperature inlet and the cold fluid temperature inlet by looking at its effect on the output temperature [26, 27] based on the calculation results, the q value in the shell and tube type he design is 639432.5 w with the reynolds number on the tube as 2183.98. reynolds number in this design shows a number less than 2300, so the type of flow that occurs in the shell is laminar flow [28]. besides that, the heat exchanger design specifications are shell and tube type, with one pass tube type, tube layout is triangular (30°), baffle type is singlesegmental, and other specifications are shown in table 2 based on calculation results using microsoft excel. in addition, with the number of ntu operating conditions of 31.79, the effectiveness of this heat exchanger design is high when the hot fluid inlet temperature is 80°c, and the outlet temperature is 30°c with the cold fluid inlet temperature is 10°c, and the outlet temperature is 20°c. the effectiveness of a heat exchanger (he) can be determined by dividing the actual heat transfer rate by the maximum possible heat transfer rate as shown in eq. 15, and the result of this heat exchanger effectiveness is 98.98%. therefore, the results of this analysis provide information that is expected to help optimize the modeling of shell and tube type heat exchangers in producing gold nanoparticles with sargassum horneri extract. (12) (14) (15) (13) thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 5 table 2. specification of shell and tube heat exchanger and operating condition for water fluid based on calculation result description type/value type of heat exchanger shell and tube tube type one pass water inlet temperature (°c) (hot fluid) 80 water outlet temperature (°c) (hot fluid) 30 water inlet temperature (°c) (cold fluid) 10 water outlet temperature (°c) (cold fluid) 20 tube outside diameter, od (mm) 22.225 tube inner diameter, id (mm) 21.184 pitch tube (mm) 31.75 length (m) 4.267 wall thickness (mm) 2.1082 total tube number, n 495 total heat transfer surface area in tube (m 2 ) 0.2978 mass flow rate of fluid in tube (kg/m 2 .s) 34.95 reynold number in tube 2183.98 prandtl number in tube 2.118 tube layout triangular shell inner diameter, ds (mm) 254 total heat transfer surface area in shell (m 2 ) 0.03136 mass flow rate of fluid in shell (kg/m 2 .s) 70.15 reynold number in shell 1059259.704 prandtl number in shell 9.394 nusselt number in shell 4370.234 baffle type single-segmental baffle spacing, b (mm) 56 initial heat transfer rate (w) 639432.5 logarithmic mean temperature difference (°c) 24.8534 area of heat transfer (m 2 ) 147.545 water mass flow rate in tube (kg/s) 3.05 water mass flow rate in shell (kg/s) 2.2 water heat rate in tube (w/k) 11000 water heat rate in shell (w/k) 7920 number of transfer unit 11.50 he effectiveness (%) 98.98 thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 6 iv. conclusion in conclusion, the design of he with shell and tube and one pass tube type has several specifications, these specifications are important parameters that affect the performance of the heat exchanger such as length is 4.267 m, inner tube diameter is 21.184 mm, tube outside diameter is 22.225 mm, wall thickness is 2.1082 mm, pitch tube is 31.75 mm, inner shell diameter is 254 mm, and the total tube number is 495. based on the calculations performed through microsoft excel, the appropriate heat exchanger design results are laminar flow type, with an effectiveness of 98.98% and an ntu of 11.50. although the he effectiveness value is high (98.98%) without calculating the fouling factor, the analysis result on this heat exchanger design can provide an initial reference in optimizing the he models with shell and tube type, and the base fluid is water for producing gold nanoparticles. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] j. zhang, x. zhu, m. e. mondejar, and f. haglind, “a review of heat transfer enhancement techniques in plate heat exchangers,” renew. sustain. energy rev., vol. 101, 2019, pp. 305–328, doi: 10.1016/j.rser.2018.11.017. [2] a. hajatzadeh pordanjani, s. aghakhani, m. afrand, b. mahmoudi, o. mahian, and s. wongwises, “an updated review on application of nanofluids in heat exchangers for saving energy,” energy convers. manag., vol. 198, no. april, 2019, pp. 111886, doi: 10.1016/j.enconman.2019.111886. [3] s. muthukrishnan, h. krishnaswamy, s. thanikodi, d. sundaresan, and v. venkatraman, “support vector machine for modelling and simulation of heat exchangers,” therm. sci., vol. 24, no. 1partb, 2020, pp. 499–503, doi: 10.2298/tsci190419398m. [4] k. cruse et al., “text-mined dataset of gold nanoparticle synthesis procedures, morphologies, and size entities,” sci. data, vol. 9, no. 1, 2022, pp. 1–12, doi: 10.1038/s41597-022-01321-6. [5] m. yari, n. javanmardi, “multifunctional gold nanoparticle : as novel agents for cancer treatment,” j. adv. appl. nanobio-technologies, vol. 3, no. 2, pp. 43–48, 2022. [6] m. abbas, h. h. susapto, and c. a. e. hauser, “synthesis and organization of gold-peptide nanoparticles for catalytic activities,” acs omega, vol. 7, no. 2, 2022, pp. 2082–2090, doi: 10.1021/acsomega.1c05546. [7] w. c. song, b. kim, s. y. park, g. park, and j. w. oh, “biosynthesis of silver and gold nanoparticles using sargassum horneri extract as catalyst for industrial dye degradation,” arab. j. chem., vol. 15, no. 9, 2022, pp. 104056, doi: 10.1016/j.arabjc.2022.104056. [8] t. d. tran, m. t. t. nguyen, h. v. le, d. n. nguyen, q. d. truong, and p. d. tran, “gold nanoparticles as an outstanding catalyst for the hydrogen evolution reaction,” chem. commun., vol. 54, no. 27, 2018, pp. 3363–3366, doi: 10.1039/c8cc00038g. [9] x. lu, x. dong, k. zhang, x. han, x. fang, and y. zhang, “a gold nanorods-based fluorescent biosensor for the detection of hepatitis b virus dna based on fluorescence resonance energy transfer,” analyst, vol. 138, no. 2, 2013, pp. 642–650, doi: 10.1039/c2an36099c. [10] d. lin, r. g. pillai, w. e. lee, and a. b. jemere, “an impedimetric biosensor for e. coli o157:h7 based on the use of self-assembled gold nanoparticles and protein g,” microchim. acta, vol. 186, no. 3, 2019, pp. 1–9, doi: 10.1007/s00604-019-3282-3. [11] m. a. mackey, m. r. k. ali, l. a. austin, r. d. near, and m. a. el-sayed, “the most effective gold nanorod size for plasmonic photothermal therapy: theory and in vitro experiments,” j. phys. chem. b, vol. 118, no. 5, 2014, pp. 1319–1326, doi: 10.1021/jp409298f. [12] j. cheng, y. j. gu, s. h. cheng, and w. t. wong, “surface functionalized gold nanoparticles for drug delivery,” j. biomed. nanotechnol., vol. 9, no. 8, 2013, pp. 1362–1369, doi: 10.1166/jbn.2013.1536. [13] j. im et al., “functionalized gold nanoparticles with a cohesion enhancer for robust flexible electrodes,” acs appl. nano mater., vol. 5, no. 5, 2022, pp. 6708– 6716, doi: 10.1021/acsanm.2c00742. [14] k. nejati, m. dadashpour, t. gharibi, h. mellatyar, and a. akbarzadeh, “biomedical applications of functionalized gold nanoparticles: a review,” j. clust. sci., vol. 33, no. 1, 2022, doi: 10.1007/s10876020-01955-9. [15] c. kamaraj et al., “green synthesis of gold nanoparticles using gracilaria crassa leaf extract and their ecotoxicological potential: issues to be considered,” environ. res., vol. 213, 2022, doi: 10.1016/j.envres.2022.113711. [16] m. sivakavinesan et al., “citrus limetta risso peel mediated green synthesis of gold nanoparticles and its antioxidant and catalytic activity,” j. king saud univ. thyta medina salsabila erlangga et al / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 01-07 page 7 sci., vol. 34, no. 7, 2022, pp. 102235, doi: 10.1016/j.jksus.2022.102235. [17] m. hosny, m. fawzy, y. a. el-badry, e. e. hussein, and a. s. eltaweil, “plant-assisted synthesis of gold nanoparticles for photocatalytic, anticancer, and antioxidant applications,” j. saudi chem. soc., vol. 26, no. 2, 2022, pp. 101419, doi: 10.1016/j.jscs.2022.101419. [18] a. aji, d. oktafiani, a. yuniarto, and a. k. amin, “biosynthesis of gold nanoparticles using kapok (ceiba pentandra) leaf aqueous extract and investigating their antioxidant activity,” j. mol. struct., vol. 1270, no. august, 2022, pp. 133906, doi: 10.1016/j.molstruc.2022.133906. [19] n. ahmad, s. sharma, and r. rai, “rapid green synthesis of silver and gold nanoparticles using peels of punica granatum,” adv. mater. lett., vol. 3, no. 5, 2012, pp. 376–380, doi: 10.5185/amlett.2012.6357. [20] s. ayyoub et al., “biosynthesis of gold nanoparticles using leaf extract of dittrichia viscosa and in vivo assessment of its anti-diabetic efficacy,” drug deliv. transl. res., vol. 12, no. 12, 2022, pp. 2993–2999, doi: 10.1007/s13346-022-01163-0. [21] a. folorunso et al., “biosynthesis, characterization and antimicrobial activity of gold nanoparticles from leaf extracts of annona muricata,” j. nanostructure chem., vol. 9, no. 2, 2019, pp. 111–117, doi: 10.1007/s40097019-0301-1. [22] s. valsalam, p. agastian, g. a. esmail, a. k. m. ghilan, n. a. al-dhabi, and m. v. arasu, “biosynthesis of silver and gold nanoparticles using musa acuminata colla flower and its pharmaceutical activity against bacteria and anticancer efficacy,” j. photochem. photobiol. b biol., vol. 201, 2019, pp. 111670, doi: 10.1016/j.jphotobiol.2019.111670. [23] a. e. adebayo et al., “biosynthesis of silver, gold and silver–gold alloy nanoparticles using persea americana fruit peel aqueous extract for their biomedical properties,” nanotechnol. environ. eng., vol. 4, no. 1, 2019, doi: 10.1007/s41204-019-0060-8. [24] v. kumar and s. k. yadav, “plant-mediated synthesis of silver and gold nanoparticles and their applications,” j. chem. technol. biotechnol., vol. 84, no. 2, 2009, pp. 151–157, doi: 10.1002/jctb.2023. [25] p. stehlík, “conventional versus specific types of heat exchangers in the case of polluted flue gas as the process fluid a review,” appl. therm. eng., vol. 31, no. 1, 2011, pp. 1–13, doi: 10.1016/j.applthermaleng.2010.06.013. [26] a. b. d. nandiyanto, s. r. putri, r. ragadhita, and t. kurniawan, “design of heat exchanger for the production of carbon particles,” j. eng. sci. technol., vol. 17, no. 4, 2022, pp. 2788–2798, [27] a. m. flynn, t. akashige, and l. theodore, kern’s process heat transfer second edition. beverly: scrivener publishing, 2019. [28] o. evju, “computational hemodynamics in cerebral aneurysms : robustness of rupture risk indicators under different model assumptions,” 2016. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 08-18 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 8 neural network for prediction solar radiation in relizane region (algeria) analysis study abdennasser dahmani 1,2* , yamina ammi 2 , salah hanini 2 1* department of mechanical engineering, faculty of science and technology, university of relizane, algeria 2 laboratory of biomaterials and transport phenomena (lbmpt), university of medea, algeria * corresponding author: email: dahmani.abdennasser@univ-relizane.dz abstract – global solar radiation prediction is the most necessary part of the project and performance of solar energy applications. the objective of the present work is to predict global solar radiation (gsr) received on the horizontal surface using an artificial neural network (ann). for the city (relizane) in the western region of algeria. the neural network-optimal model was trained and tested using 80 %, and 20 % of the whole data, respectively. the best results were obtained with the structure 10-25-1 (10 inputs, 25 hidden, and 1 output neurons) presented an excellent agreement between the calculated and the experimental data during the test stage with a correlation coefficient of r = 0.9879, root means squared error of rmse = 47.7192 (wh/m 2 ), mean absolute error mae = 27.7397 (wh/m 2 ), and mean squared error mse = 2.2771e+03(wh/m 2 ), considering a three-layer feed forward neural network with regularization bayesienne (trainbr) training algorithm, a hyperbolic tangent sigmoid and linear transfer function at the hidden and the output layer, respectively. the results demonstrate proper ann’s predictions with a root mean square error (rmse) of less than 0.50 (wh/m 2 ) and a coefficient of correlation (r) higher than 0.98, which can be considered very acceptable. this model can be used for designing solar energy systems in the hottest regions. keywords: prediction, global solar radiation, artificial neural networks. received: 17/08/2022 – revised: 20/10/2022 – accepted: 06/11/2022 i. introduction solar radiation statistics are needed by architects, engineers, and scientists in the structure of research on photovoltaic or thermal solar radiation. the time step of facts relies upon the use that is supposed. if week-toweek average values permit us to comprehend an initial sizing or design solar systems, everyday values, and better but, hourly values are required if we are to carry out a greater accurate and unique sizing. it is miles the same aspect if we want to represent the behaviour of the solar machine whilst a time-lag happens among production and intake and that a strength storage way or an electrical electricity buffer is in the device [1]. algeria has a massive benefit regarding sun strength capacity due to its geographic position. the sunshine period at the complete algerian country-wide territory exceeds 3.000 hours every year and might even attain 3.900 h on excessive plateaus and sahara [2, 3], the solar radiation is one of the most sustainable energies most vital, it could be transformed into heat or electric powered power, and is used for plenty sun programs, which includes sun construction, sun consumption, heat pumps, air conditioning, agriculture, and studies of atmospheric physics [4]. mailto:dahmani.abdennasser@univ-relizane.dz abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 9 unfortunately, for lots of regions in this country, solar radiation measurements aren't effortlessly to be had due to the problem to afford the measurement equipment (pyranometers/ solarimeters) and the strategies involved (value, preservation, calibration requirement). despite the existence of some of the meteorological stations at many locations in algeria, now and again the measurements are not available continuously because of recording deficiencies due to heavy power cuts specifically in summers, or the number of recording variables is constrained. therefore, it's far alternatively essential to difficult techniques to estimate as it should be the sun radiation based on greater readily available meteorological data, we use proven techniques to evaluate the solar radiation components, as the empirical modelling and intelligent techniques(artificial neural networks) [5]. nonlinear autoregressive recurrent neural networks with exogenous inputs (narx) to be able to expect the hourly worldwide sun irradiation at 24-h forecast in new zealand. an assessment among the narx strategies with the artificial neural network (ann) primarily based multi-layer perceptron (mlp) method, autoregressive shifting average (arma), and a reference persistence technique have proven appropriate results [6], successfully confirmed the ability of mlps to generate very short-term inclined irradiation estimations (5 min) in algiers (algeria). the input data used: global horizontal irradiation, extraterrestrial irradiation, zenith angle, and azimuth declination. the study showed that the exclusion of azimuth as well, develops the accuracy of the model [7], applied ann techniques to predict components of solar radiation in new delhi (india) [8], developed a variety of model anns for global solar radiation forecasting in tamilnadu (india). the ann models had better results than the other approaches in this study [9]. used the comparison between the artificial neural network (ann) bayesian neural network (bnn), and empirical model for estimating the daily global solar irradiation with input data, air temperature, sunshine duration, relative humidity, and extraterrestrial irradiation. it was been deducted that the bnn model performs better than ann approaches and empirical models [10]. utilized the radial basis function (rbf) in order to predict daily global solar radiation with the air temperature, sunshine duration, and relative humidity as input data collected in al-madinah city in saudi arabia. it was found that the rbf approach uses the sunshine duration and air temperature as input parameters [11], and has focused on the prediction of the monthly average daily gsr over italy via multi-location ann by using other independent meteorological parameters, including the geographical coordinates [12], developed a nonlinear model based on ann and simulated annealing (sa) to predict the daily solar radiation on the horizontal surface [13]. this paper endeavors to propose an optimisation methodology for reaching a better multi-layer perceptron (mlp) network; based on almost all aspects of ann modeling such as the division of the total databases (training, validation, testing), the activation function in the hidden layers, the training algorithms, pre-and postprocessing, number of neurons in the hidden layers. in this work, an ann approach model is used with aim of predicting the hourly values of global solar radiation based on ten climatological and meteorological parameters for 68 months in the region of relizane– algeria. ii. material and method ii.1. artificial neural network neural network technology possesses the advantages of self-learning, adaptability, fault acceptance, and distributed storage, allowing to implementation of a variety of nonlinear mappings in various fields neural network does not need a mathematical equation for the nonlinear connection between the inputs and outputs. it only learns some rules through its training, and the result closest to the expected output value can be obtained when the input value is given [14]. artificial neural network models have been successfully used in many fields. the algorithm is the core of the ann to achieve its functions. the processes to establish the ann methods. the basic configuration of an ann consists of many interconnected computing processors, named neurons or nodes, grouped into input, hidden, and output layers. each node in an ann takes values from its inputs, multiplies them by the corresponding weights, and sums up all the results plus a constant bias value. the summation then passes a transfer function and produces the output of the node [15]. figure 1 presents a three-layer feed-forward neural network (ffnn) for global solar radiation (gsr). abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 10 figure 1. three-layer feed-forward neural network for global solar radiation (gsr) ii.2. modeling procedure in this work, a procedure based on the design and optimisation of the architecture of the neural network is advanced as described in figure 2. figure 2. the procedure of the design and optimization of the architecture of ann ii.3. database collection and pretreatment the database was provided for relizane [16, 17], it is situated in the western region of algeria, with a latitude: of 35.73°, longitude: of +5500°, and altitude of 0 m above the mean sea level (figure 3). the 68 months of database (1 january 2016 to 31 august 2021) were applied for forecasting hourly global solar radiation using neural networks (nn) for the ten parameter configurations. figure 3. the location of relizane, algeria [18] figure 4. shows the global solar radiation (gsr " wh/m 2 ", 0.000 gsr 1041.5670) as a function temperature (t"k" 274.2100 t 317.2100) for the total database (49680 points). global solar radiation increases with increasing temperature at some points. there are null values of global solar radiation when the temperature is high, because, it is the night hours of the summer. figure 4. global solar radiation (gsr "wh/m 2 ") is a function of temperature (k) abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 11 the statistical analysis of the inputs and output data was done in terms of the minimum "min", the average "mean", the maximum "max", and the standard deviation "std" which are mentioned in table 1. table 1. statistical analysis of inputs and output ii.4. modeling with neural network the total databases (49680 points) were divided into three subsets according to the learning algorithm levenberg-marquard "lm" (training database, validation database, and testing database) and into two subsets according to the learning algorithm regularization bayesienne "trainbr"(training database and testing database) to test the predicting ability of the proposed models. the number of neurons in the hidden layer varied from 3 to 25 neurons. the tangent hyperbolic (tanh), and the log sigmoid (logsig), transfer functions were used in the hidden layer. the pure-linear (purelin) was used in the output layer. the neural network was trained using two training algorithms levenberg-marquard (lm) and regularization bayesienne (trainbr). the optimisation stage of neural network architecture for solar radiation estimation was performed using matlab 2020b software which goes through several steps such as algorithms, the distribution of the database, one of the hidden layers, the number of neurons in the hidden layer, the transfer functions for the hidden and the output layer respectively. iii. results and analysis table 2 shows the error values (root mean squared error "rmse" and coefficient of correlation "r") obtained for the global solar radiation under the influence of the division of the database for anns model with division 1 (39744 points for training (80%), 4968 for validation phase (10%), and 4968 for testing phase (10%)), division 2 (34776 points for training (70%), 7452 for validation phase (15%) and 7452 for testing phase (15%)), and division 3 (29808 points for training (60%),9936 for validation phase (20%), and 9936 for testing phase (20%)) for the learning algorithm levenberg-marquard "lm". table 2 demonstrates that division 2 with the learning algorithm levenberg-marquard "train-lm" has lower rmse than divisions 1 and 3 (rmse = 49.9423 and r = 0.9866 for the testing phase). therefore, it is clear that division 2 with the learning algorithm levenbergmarquard "lm" with tansig represents the best result for modeling the global solar radiation using the ann model. table 2. effect of dividing the database with the learning algorithm levenberg-marquard "train-lm" table 3 shows the error values (root mean squared error "rmse" and coefficient of correlation "r") obtained for the global solar radiation under the influence of the activation function (log sigmoid "logsig", hyperbolic tangent sigmoid "tansig") in the hidden layer. the ann model with learning algorithms regularization bayesienne (trainbr) and with hyperbolic tangent sigmoid "tansig" gives lower errors than the other models (rmse = 47.7192 and r = 0.9872 for the testing phase). we conclude the superiority of the ann model with learning algorithms regularization bayesienne (trainbr) and with hyperbolic tangent sigmoid "tansig" for modeling the global solar radiation. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 12 table 3. effect of activation function in the hidden layer and the learning algorithms hence, the structure of the anns for the modeling of global solar radiation is mentioned in figure 5. its more detailed architecture is illustrated in table 4. the weight matrices and bias vectors of the optimized ann models are applied, : the input-hidden layer connection weight matrix (25 rows x 10 columns); : the hidden-output layer connection weight matrix (25 rows x 1 column); : the hidden neurons bias column vector (25 rows); : the output neurons bias column vector (1 row). the optimized ann models shown are in figure 5. assimilation of the global solar radiation can be depicted by a mathematical model incorporating all inputs , it is given by the following equations: the instance outputs of the hidden layer: j=1, 2, …, 25 the output "global solar radiation" the combination of eqs. (1) and (2) lead to the following mathematical formula which describes global solar radiation by taking into account all inputs. figure 5. three-layer feed-forward neural network for modeling the global solar radiation table 4. structure of the optimized ann model the parameters and the plot of the linear regression are, straightforwardly obtained using the matlab function "postreg" (figures 6a, b, and c). the comparison between experimental and calculated values of global solar radiation obtained by the ann model optimal shows that there is excellent agreement between them with agreed vectors approaching the ideal [a(the slope), β(yintercept), (correlation coefficient)] = [0.9745, 5.7842, 0.9872] for the training phase, [a, β, r] = [0.9727, 5.3708, 0.9879] for the testing phase, and [a, β, r] = [0.9741, 5.7027,0.9873] for the total phase. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 13 figures 6. comparison between experimental and calculated values for the whole dataset, (a) training, (b) testing, and (c) all the errors of the ann model optimal for the training phase, testing phase, and total phase are: the correlation coefficient (r), the mean absolute error (mae), the model predictive error (mpe), the root mean squared error (rmse), the standard error of prediction (sep), residual predictive deviation (rpd), range error ratio (rer), the mean square error (mse), the mean relative squared error (mrse), the accuracy factor (af), and bias factor (bf) are given by following equations. the errors were calculated to confirm the prediction capacity of global solar radiation. equations of those parameters are given below [19]: where n is the total number of data points, is the experimental value, represents the calculated value from the neural network "nn" model, and is the mean value of experimental data. std is the standard deviation of experimental data, min is the minimum of experimental data, and max is the maximum of experimental data. the statistical parameters of the ann model optimal for the phases concerning the training, testing, and total are shown in table 5. the correlation coefficient (r) for the training phase is 0.9872, which indicates the ideal agreement. the testing phase correlation coefficient represents a comparison between the experimental data and predicted results in order to show the interpolating ability of the ann model optimal. for the testing phase, the correlation coefficient is 0.9879, which demonstrates the good agreement between the experimental global solar radiation and the predicted global solar radiation. on the other hand, we adopted the five-level interpretations of residual predictive deviation "rpd" and range error ratio "rer" provided by viscarra rossel: excellent predictions (rpd and rer > 2.5); good (rpd and rer of 2.0 to 2.5); approximate quantitative predictions (rpd and rer of 1.8 to 2.0); possibility to distinguish high and low values (rpd and rer of 1.4 to 1.8); and unsuccessful (rpd and rer< 1.40) [20]. the rpd and rer of the neural networks model optimal are higher than 2.5 (rpd = 6.3051 (wh/m 2 ) and rer= 21.5033 (wh/m 2 ) for ann) for the total phase. moreover, the values of r,mae,sep, abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 14 rer,rpd, mse, mrse, rea, af, bf (for the training phases, for the testing phase, and the total phase) in addition to the rmse imply that the ann model has more predictive power in this work. they allow the representation of the nonlinear relationship the global solar radiation. table 5. statistical evaluation of the models performance the statistical parameters of the anns model for the phases concerning the training, testing, and total are shown in table 2. the correlation coefficient (r) for the training phase is 0.9872, which indicates the ideal agreement. the testing phase correlation coefficient represents a comparison between the experimental data and predicted results in order to show the interpolating ability of the anns model. for the testing phase, the correlation coefficient is 0.9879, which demonstrates the good agreement between the experimental global solar radiation and the predicted global solar radiation. the contribution of the input variables (time(h), day, month, year, temperature (k), relative humidity (%), pressure (mbar), wind speed (m/s), wind direction (°), rainfall(kg/m 2 )) on the output was determined by a sensitivity analysis using the "weight" method and thus for the neural network optimal. this method was proposed initially by [21]. and repeated by [22].provides a quantification of the relative importance (ri) of the inputs on the output of the neural network [23]. it is based on the partitioning of connection weights to [19]  connection weights of input – hidden;  connection weights of hidden output. the process of the "weight" method is composed of four steps, which are depicted in figure 7. figure 7. flowchart of the "weight" method [19] the contribution results are shown in figure 8. the most important variables that may influence global solar radiation are day, rainfall (kg/m 2 ) time (h), year, relative humidity (%), pressure (mbar), and wind direction (°), the input relevant variables cited above have a significant contribution (ri > 2 %). this sensitivity analysis by the weight method successfully identified the true importance of almost all the variables used for the modeling of global solar radiation, and therefore, proves the correctness of the choice of variables that were used in this study. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 15 figure 8. relative importance (ri) histograms comparison with different models for the significance of the problem encountered during global solar radiation, models have been developed to study the performance of these processes. among these models, we meet the neural networks optimal. however, there is a major number of works cited in the literature relating to work on modeling global solar radiation during the years 1998-2021. table 6 lists the only notable examples of studies predicting global solar radiation by the neural network model published over the years. table 6. shows that our model is the only model that brings the prediction of global solar radiation in relizane, algeria. in our model, we used ten input variables (time (h), day, month, year, temperature (k), relative humidity (%), pressure (mbar), wind speed (m/s), wind direction (°), rainfall (kg/m 2 )). then other authors used the same or different input variables: [24] added the mean vapor and mean sunshine hours as our input variables; [25] used the inputs extra the latitude, longitude, and altitude; [26] were working with other inputs like the declination, the elevation of the sun, the azimuth, the angle incidence, and the air mass; and append the extraterrestrial solar irradiation and sunshine duration and other parameters [27-31]. in our current study, we used feed-forward neural networks (ffnn) with two training algorithms (regularization bayesienne (trainbr) and levenbergmarquard (lm)) and two activation functions (sigmoid logistic and tangent sigmoid)in the hidden layer for prediction hourly global solar radiation. each literature cited in table 6. used the same organization (artificial neural networks, algorithm learning, and activation function), just [4] used quasi-newton back propagation (bfgs) as a training algorithm, and [18]: utilized an elman neural network (enn) as artificial neural networks type. the comparison between our artificial neural network optimal model (ann-optimal) and the literature models for predicting solar radiation in terms of the root mean squared error (rmse), and the correlation coefficient (r), which were calculated using the data. our study presented the good performance of anndeveloped models. ann models show a higher correlation coefficient (r=0.9879 and rmse = 47.7192 (wh/m 2 ) for the testing phase of our ann optimal model), the correlation coefficients are generally considered to be excellent (0.90 ≤ r ≤ 1.00) for each ann model compared to the ann models reported in the literature table 6 confirms the strength and accuracy of ann models for the prediction of hourly global solar radiation. [27]. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 16 table 6. results of our model versus various similar models models input variables ann type algorithm learning activation function in hidden layer prediction error al-alawi and alhinai. [24] -month -mean relative humidity -mean temperature -mean pressure -mean vapour pressure -mean wind speed -mean sunshine hours -feedforward neural network (ffnn) -r = 0.93 à 0.95 benghanem and mellit [11] -air temperature -relative humidity -sunshine duration -day of the year -feedforward neural network (ffnn) levenberg-marquard(lm) -r =0. 9765 -rmse = 0.04425% rezrazi et al. [27] -air temperature -relative humidity -number of days -local time -feedforward neural network (ffnn) levenberg-marquard (lm) and regularization bayesienne (trainbr). -sigmoid logistique -r = 0.9929 -rmse = 14.06% siham et al. [4] -day -time -relative humidity -temperature -speed of wind -wind direction -atmospheric pressure -feedforward neural network (ffnn) -quasi-newton back propagation (bfgs) -tangent hyperbolic -r = 0.997 -rmse = 4.82 % kurniawan and shintaku. [25] -latitude -longitude -altitude -number of months -average, minimum, and maximum temperature -sunshine duration precipitation -wind speed -relative humidity -feedforward neural network (ffnn) levenberg-marquard(lm) -r= 0.999 amiri et al. [26] -the declination -the elevation of the sun -the azimuth -the angle incidence -the air mass -the temperature relative humidity feedforward neural network (ffnn) -sigmoid logistic and tangent hyprbolique -r=0.995 -rmse = 6.37% benatiallah et al. [18] average temperature-wind speed -relative humidity atmospheric pressure -extraterrestrial solar irradiation -sunshine duration. feedforward neural network (ffnn) and elman neural network (enn) levenberg-marquard(lm) -tangent sigmoid rmse=0.703(kwh/m 2 /da y) -r = 0.9332 present work -day -month -year -time -temperature -relative humidity -pressure -wind speed -wind direction -rainfall -feedforward neural network (ffnn) levenberg-marquard(lm) and regularization bayesienne (trainbr) -sigmoid logistic and tangent sigmoid -r=0.9869 and r=0.9879 -rmse= 49.2661(wh/m 2 ) and rmse=47.7192(wh/m 2 ) https://www.sciencedirect.com/science/article/abs/pii/s036054421000294x#! https://www.sciencedirect.com/science/article/abs/pii/s036054421000294x#! abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 17 iv. conclusion in this study, the artificial neural network optimal model (ann-optimal) was developed for modeling the 49680points of global solar radiation. the best results were obtained with the structure 10-25-1 (10 inputs, 25 hidden, and 1 output neurons) presented an excellent agreement between the calculated and the experimental data during the test stage with a correlation coefficient (r) of 0.9879, root means squared error(rmse)of 47.7192 (wh/m 2 ), mean absolute error (mae) of 27.7397 (wh/m 2 ), and mean squared error 2.2771e+03(wh/m 2 ), considering a three-layer feedforward neural network with regularization bayesienne (trainbr) training algorithm, a hyperbolic tangent sigmoid and linear transfer function at the hidden and the output layer, respectively. the sensitivity analysis by weight method identified that the most important variables that influence the global solar radiation are: day, rainfall (kg/m 2 ), time (h), year, relative humidity (%), pressure (mbar), and wind direction (°).these input relevant variables have a significant contribution (relative importance ri >2 %).our ann-optimal model can be used for designing global solar radiation systems in the hottest regions. acknowledgments the authors gratefully acknowledge the ministry of higher education of algeria (prfu projects n°a16n01un260120220004) and the group of laboratory of biomaterials and transport phenomena in the university of medea and the university of relizane for their help throughout this project. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] g. notton, c. paoli, s. vasileva, ml. nivet, jl. canaletti, c. cristofari, “estimation of hourly global solar irradiation on tilted planes from horizontal one using artificial neural networks,” energy, vol. 39, 2012, pp. 166-179.‏ https://doi.org/10.1016/j.energy.2012.01.038 [2] a b stambouli, z khiat, s flazi, y kitamura, “a review on the renewable energy development in algeria: current perspective, energy scenario and sustainability issues,” renewable and sustainable energy reviews, vol. 16, no. 7, 2012, pp. 4445-4460.‏ https://doi.org/10.1016/j.rser.2012.04.031 [3] algerian ministry of energy and mines. renewable energy and energy efficiency program. available from :< http://www.men-algeria.org>, [accessed on 2021] [4] cm siham, h salah, l maamar, k latifa, “artificial neural networks based prediction of hourly horizontal solar radiation data: case study,” international journal of applied decision sciences, vol. 10, 2017, pp. 156-174. http://doi.org/10.1504/ijads.2017.084312 [5] m laidi, s hanini, a rezrazi, mr yaiche, aa el hadj, f chellali, “supervised artificial neural networkbased method for conversion of solar radiation data: case study: algeria,” theoretical and applied climatology, vol. 128, 2017, pp. 439–451. https://doi.org/10.1007/s00704-015-1720-7 [6] a ahmad, tn anderson, tt lie, “hourly global solar irradiation forecasting for new zealand,” solar energy, vol. 122, 2015, pp. 1398-1408. https://doi.org/10.1016/j.solener.2015.10.055 [7] k dahmani, r dizene, g notton, c paoli, c voyant, ml nivet, “estimation of 5-min time-step data of tilted solar global irradiation using ann (artificial neural network) model,” , vol. 70, 2014, pp. 374-381.‏ https://doi:10.1016/ j.energy.2014.04.011 [8] nd kaushika, rk tomar, sc kaushik, “artificial neural network model based on interrelationship of direct, diffuse and global solar radiations,” solar energy, vol. 103, 2014, pp. 327-342. https://doi.org/10.1016/j.solener.2014.02.015 [9] r kumar, rk aggarwal, jd sharma, “comparison of regression and artificial neural network models for estimation of global solar radiations,” renewable and sustainable energy reviews, vol. 52, 2015, pp. 1294 https://doi.org/10.1016/j.rser.2015.08.021 ‏.1299 [10] r yacef, a mellit, s belaid, z şen, “new combined models for estimating daily global solar radiation from measured air temperature in semi-arid climates: application in ghardaïa, algeria,” energy conversion and management, vol. 79, 2014, pp. 606-615. https://doi.org/10.1016/j.enconman.2013.12.057 https://doi.org/10.1016/j.energy.2012.01.038 https://doi.org/10.1016/j.rser.2012.04.031 http://dx.doi.org/10.1504/ijads.2017.084312 https://link.springer.com/journal/704 https://doi.org/10.1007/s00704-015-1720-7 https://doi.org/10.1016/j.solener.2015.10.055 https://doi.org/10.1016/j.solener.2014.02.015 https://doi.org/10.1016/j.rser.2015.08.021 https://www.sciencedirect.com/science/journal/01968904 https://www.sciencedirect.com/science/journal/01968904 https://doi.org/10.1016/j.enconman.2013.12.057 abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 08-18 page 18 [11] m benghanem, a mellit, “radial basis function network-based prediction of global solar radiation data: application for sizing of a stand-alone photovoltaic system at al-madinah, saudi arabia,” energy, vol. 35, 2010, pp. 3751-3762. https://doi.org/10.1016/j.energy.2010.05.024 [12] ef alsina, m bortolini, m gamberi, a regattieri , “artificial neural network optimisation for monthly average daily global solar radiation prediction,” energy conversion and management, vol. 12, no. 15, 2016, pp. 320-329. https://doi.org/10.1016/j.enconman.2016.04.101 [13] sm mousavi, e s mostafavi, , p jiao, “next generation prediction model for daily solar radiation on horizontal surface using a hybrid neural network and simulated annealing method,” energy conversion and management, vol. 153, 2017, pp. 671-682. https://doi.org/10.1016/j.enconman.2017.09.040 [14] y chen, l shen, r li, x xu, h hong, h lin, j chen, “quantification of interfacial energies associated with membrane fouling in a membrane bioreactor by using bp and grnn artificial neural networks,” journal of colloid and interface science, vol. 565 2020, pp. 1-10.‏ https://doi.org/10.1016/j.jcis.2020.01.003 [15] x xue, “prediction of daily diffuse solar radiation using artificial neural networks,” international journal of hydrogen energy, vol. 42, no. 47, 2017, pp. 28214-2822. https://doi.org/10.1016/j.ijhydene.2017.09.150‏ [16] soda data. http://www.soda-pro.com/webservices#meteodata [accessed on 2021]. [17] infoclimat. http://www.infoclimat.fr [accessed on 2021]. [18] d benatiallah, k bouchouicha, a benatiallah, a harouz, b nasri, “artificial neural network based solar radiation estimation of algeria southwest cities,” in international conference in artificial intelligence in renewable energetic systems, 2020, pp. 573-583. https://doi.org/10.1007/978-3-030-63846-7_54 [19] y ammi, l khaouane, s hanini, “prediction of the rejection of organic compounds (neutral and ionic) by nanofiltration and reverse osmosis membranes using neural networks,” korean journal of chemical engineering, vol 32, no. 11, 2015, pp. 2300-2310. https://doi.org/10.1007/s11814-015-0086-y [20] y ammi, l khaouane, s hanini, “a comparison of" neural networks and multiple linear regressions" models to describe the rejection of micropollutants by membranes,” kemija u industriji, vol. 69, 2020, pp. 111 https://doi.org/10.15255/kui.2019.024‏ .127 [21] gd garson, “interpreting neural network connection weights,” artificial intelligence expert, vol. 6, 1991, pp. 47–51. https://dl.acm.org/doi/10.5555/129449.129452 [22] a goh, “back-propagation neural networks for modeling complex systems,” artificial intelligence in engineering, vol. 9, no. 3, 1995, pp. 143-151. https://doi.org/10.1016/0954-1810(94)00011-s [23] m gevrey, i dimopoulos, s lek, “review and comparison of methods to study the contribution of variables in artificial neural network models,” ecological modelling, vol. 160, no 3, 2003, pp. 249-264. https://doi.org/10.1016/s0304-3800(02)00257-0 [24] sm al-alawi, ha al-hinai, “an ann-based approach for predicting global radiation in locations with no direct measurement instrumentation,” renewable energy, vol. 14, 1998, pp. 199-204. https://doi.org/10.1016/s0960-1481(98)00068-8 [25] a kurniawan, e shintaku, “ a neural network-based rapid maximum power point tracking method for photovoltaic systems in partial shading conditions,” machine learning and computing, vol. 56, no. 3, 2020, pp. 157-167. http://doi.org/10.3103/s0003701x20030068 [26]. b amiri, r dizène, k dahmani, “ most relevant input parameters selection for 10-min global solar irradiation estimation on arbitrary inclined plane using neural networks,” international journal of sustainable energy, vol. 39, no.8, 2020, pp. 779-803.‏ https://doi.org/10.1080/14786451.2020.1758104 [27] a rezrazi, s hanini, m laidi, “ an optimisation methodology of artificial neural network models for predicting solar radiation: a case study,” theoretical and applied climatology, vol. 123, 2016, pp. 769-783. http://doi.org/ 10.1007/s00704-015-1398-x https://www.sciencedirect.com/science/article/abs/pii/s036054421000294x#! https://www.sciencedirect.com/science/article/abs/pii/s036054421000294x#! https://www.sciencedirect.com/science/journal/03605442 https://doi.org/10.1016/j.energy.2010.05.024 https://www.sciencedirect.com/science/journal/01968904 https://www.sciencedirect.com/science/journal/01968904 https://doi.org/10.1016/j.enconman.2016.04.101 https://doi.org/10.1016/j.enconman.2017.09.040 https://doi.org/10.1016/j.jcis.2020.01.003 https://doi.org/10.1016/j.ijhydene.2017.09.150 https://doi.org/10.1016/j.ijhydene.2017.09.150 http://www.infoclimat.fr/ https://doi.org/10.1007/978-3-030-63846-7_54 https://doi.org/10.1007/s11814-015-0086-y https://doi.org/10.15255/kui.2019.024 https://doi.org/10.15255/kui.2019.024 https://dl.acm.org/doi/10.5555/129449.129452 https://doi.org/10.1016/0954-1810(94)00011-s https://www.sciencedirect.com/science/journal/03043800 https://www.sciencedirect.com/science/journal/03043800 https://doi.org/10.1016/s0304-3800(02)00257-0 https://www.sciencedirect.com/science/journal/09601481 https://www.sciencedirect.com/science/journal/09601481 https://doi.org/10.1016/s0960-1481(98)00068-8 https://doi.org/10.3103/s0003701x20030068 https://doi.org/10.1080/14786451.2020.1758104 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 06-10 ijeca-issn: 2543-3717. june 2017 page 6 optimal dg location and sizing for minimum active power loss in radial distribution system using firefly algorithm s. remha, s. chettih, s. arif amar telidji university, lacosere laboratory, university of laghouat, algeria s.remha@lagh-univ.dz abstract – in this paper, a novel optimization algorithm is presented for the optimal location and sizing of distributed generation (dg) units on distribution systems. for this purpose, a recently based meta-heuristic called firefly algorithm (fa) has been employed to minimize the total active power losses. the results show considerably improved in voltage profiles of all the buses and enhance the voltage stability index. the investigations were tested on ieee 33 bus radial distribution system. simulation results demonstrate the effectiveness of firefly algorithm. comparison with another method is also given. keywords: generation, firefly algorithm, active power losses, radial distribution network received: 18/02/2017 – accepted: 25/05/2017 i. introduction distributed or dispersed generation (dg) is used in order to produce electrical power for a small-scale (1 kw to 50 mw) that is usually connected to or embedded in the distribution system [1]. the advantage of dg are numerous [2, 4] and the reasons for implementing dg units are an energy efficiency or rational use of energy, diversification of energy resources, reduction of on-peak operating cost, deferral of network upgrades, minimizing power losses, lower transmission and distribution costs, and possible increase of service quality to the end-customer. moreover, dgs are available in modular units, characterized by ease of finding sites for smaller generators, shorter construction times, lower capital costs and reduction of gaseous emissions. in literature different analytical and meta-heuristic optimization based algorithms have been proposed for optimum dg location and sizing. in [5], the authors in [6] have employed an analytical approach for the optimum dg unit location with fitness function of minimization of active power losses. further, the authors in [7] have developed a new analytical method for the voltage profile enhancement and compensation of active power losses. the authors in [8] have proposed a meta-heuristic technique called ant bee colony (abt) algorithm for reducing the active power losses in distribution power system. also, the authors in [9] and [10] have applied a cuckoo search algorithm (csa) for dg placement and sizing problem in order to reduce the active power loss and to enhance the network voltage profile. in [11], the authors have proposed particle swarm optimization (pso) algorithm for reducing the power losses in the distribution system. furthermore, the authors in [12] have proposed on the installation of the capacitor bank with objective function of minimization of total power losses and net saving maximization using a novel optimization algorithm. other prepositions in [13] based on multiobjective optimization problem for improving the transient stability using a hybrid evolutionary algorithm. the presents study describes the employment of a novel meta-heuristic called firefly algorithm (fa) for the optimal placement and sizing of dg unit in radial distribution networks. this problem is formulated as an optimization problem. the proposed algorithms have been tested on ieee 33 bus radial distribution systems. figure 1. electrical equivalent of two node system. this paper is organized as follows: firstly presents the problem formulation. section ii explains the proposed approach. the results and discussion are presented in section iii and finally the conclusion is given in section iv ri + jxi sending end receiving end s. remha et al. ijeca-issn: 2543-3717. june 2017 page 7 ii. problem formulation a. active power loss in this study, the optimal siting and sizing of dg units in 33 bus radial distribution networks is formulated as an optimization problem to reduce the total active power losses. this latest can be calculated by eq. 1. figure 1 shows the electrical equivalent of radial distribution system. from figure 1, the following equation can be written:   2 22 )( i ii i v qp ripl   (1) therefore, the objective function is calculated using the following equation:         bus busbus n i n i i ii i n i v qp riplplf 2 2 2 22 2 )( (2) where i-1 sending end node; i receiving end node; ri+jxi is the line impedance connected between i-1 and i; i current of branch j; vi-1 voltage of node i-1; vi voltage of node i; pi and qi active and reactive power load fed through node i.  total loss reduction (tlr) total loss reduction (tlr) is calculated using eq. (3) [14]: 100% 1 11 / //        bus dgwo bus dgwo bus dgw n i n i n i pl plpl tlr (3) where, plw/dg is the total line losses in the system with the employment of dg and plwo/dg is the total line losses in the system without dg iii. constraints the objective function is subjected to main constraints in the optimization process in the proposed methodologies are:  power constraint  voltage constraint.  active power losses constraint.  dg size constraint. b. power constraint the equality constraints are active/reactive power flow equations as:     busn j ijijijjidigi n j ijijjjidigi ni yvvqq iyvvpp bus bus ,..,1 sin cos 1 1                 (4) where pgi and qgi are the active (resp. reactive) power generated at the ith bus; pdi and qdi are the active (resp. reactive) load demand at the same bus; yij and θij are the admittance magnitude (resp. angle) of branch connecting bus i and j. c. voltage constraint the voltage magnitude must keep within the specified limits at each bus [15]: maxmin vvv i  (5) where vmin, vmax are the lower and upper limits of bus voltage, respectively. d. active power losses constraint the losses after installing dg in power grid should be less than or equal losses before installing dg [15]. dgwithoutpldgwithpl  (6) e. distributed generation size constraint to obtain a reasonable solution, the size of generator should not be so small or so high with respect to load value. the dg size is considered not less than zero and not more than the total active load demand as following [15]:   busn i didg ppdgofsize 1 )(0 (7) where dip is the active load demand at the same bus. iv. proposed algorithm firefly algorithm (fa) is invented by xin-she yang [15] for solving multimodal optimization problem. the development of fa is based on flashing behavior of fireflies. there are about two thousand firefly species where the flashes often unique for a particular species. the flashing light is produced by a process of bioluminescence where the exact functions of such signaling systems are still on debating. nevertheless, two fundamental functions of such flashes are to attract mating partners (communication) and to attract potential prey. for simplicity, the following three ideal rules are introduced in fa development [16]:  all fireflies are unisex so that one firefly will be attracted to other fireflies regardless of their sex,  attractiveness is proportional to their brightness, thus for any two flashing fireflies, the less brighter one will move towards the brighter one,  the brightness of a firefly is affected by the landscape of the objective function. for maximization problem, the brightness can simply be proportional to the value of the objective or fitness function. v. application of the firefly algorithm to the problem in this section, firefly algorithm (fa) is proposed to discover the best placement and sizing of distributed generation (dg) unit in a radial distribution system to s. remha et al. ijeca-issn: 2543-3717. june 2017 page 8 minimize the total active power loss in the system. by reducing power loss, the voltage profile at each bus is also expected to be improved the voltage profiles and increased values of voltage stability index. figure 2 presents the general flowchart of firefly algorithm for evaluating the objective function. figure 2. flowchart of dg location and sizing using firefly algorithm. vi. resultats and discussion in this study, the proposed algorithms are used to determine the optimal location and size of the dg unit and they have been carried out on ieee 33-bus radial distribution system. the fa properties in this simulation are set as follow: table i. firefly algorithm settings settings values number of iteration 50 number of population 20 variation of attractiveness 0.5 randomization 0.8 absorption coefficient 1  ieee 33-bus radial distribution system the test system is ieee 33-bus radial distribution system, with the total load is 3.715 mw and 2.3 mvar, its voltage level is 12.66 kv, this system contains 33 bus and 32 branches. its corresponding scheme is presented in figure 3 [17]. figure 3. ieee 33-bus radial distribution system f. results the dg unit localization, corresponding sizes and active power losses in the cases without and with dg unit using the proposed algorithm and pso algorithm find by [11] are respectively summarized in table ii. the voltage profile, minimum and maximum voltage, voltage stability index, minimum and maximum voltage stability index and the active power losses are presented in figures. (4-8) simultaneously. table ii. application of proposed algorithm on ieee 33 test system ieee 33-bus test system without dg with dg pso [11] proposed method optimum location 7 6 optimum dg size (mwa) 2.91 2.60 active power losses (kw) 211,00 115.1 111 loss reduction % 45.45 47.39 g. discussion the effect of dg placement is also measured by calculating the active power loss, the voltage profiles and s. remha et al. ijeca-issn: 2543-3717. june 2017 page 9 the voltage stability index. table iii shows the effect of dg placement on system performance. from these results, we can observe the advantage of dg units in improvement of system performances, as reduction of total system losses and the voltage index stability enhancement. in order to validate the performance of the proposed algorithm in this study, we have used ieee 33-bus test distribution system. when the proposed method is applied on test system, it was found that the proposed method gives much better voltage profile as compared to the base case. fig. 4 shows voltage profile of ieee 33-bus test distribution system (with and without dg placement). from fig. 5, it can be observed that the minimum voltage is raised from 0.90 pu in the case without dg unit to 0.94 pu in the case with dg unit using the proposed method. fig. 6 shows the voltage stability indices of test system. the weakness of voltage stability indices for all buses in the distribution system before integration dg unit is obvious. but after integration dg unit, the buses stability indexes are considerably enhanced. fig. 7 shows the minimum and maximum voltage stability index of the test system (with and without dg placement). the proposed method also results in total power loss reduction. table ii shows the effect of dg placement on loss reduction, using the proposed and another existing method. from table ii, it can be observed after installation of dg units, the active power losses have been significantly reduced. the proposed algorithm is found better in performance than pso algorithm. where the proposed algorithm gives 2% more power loss than pso algorithm. fig. 8 shows the active power loss at buses with and without dg for ieee 33 bus test system. figure 4. voltage profiles of 33 bus system. figure 5. minimum and maximum voltage of 33 bus system. figure 6. voltage stability index of 33 bus system figure 7. minimum and maximum voltage stability index of 33 bus system s. remha et al. ijeca-issn: 2543-3717. june 2017 page 10 figure 8. active power loss of 33 bus system. vii. conclusion in this paper, the problem of optimal dg unit placement and sizing in radial distributed network has been treated. for this reason, a recent meta-heuristic technic known as firefly algorithm is employed to minimize the total active power losses. its effectiveness and robustness is compared to the particle swarm optimization algorithm. simulations were performed on ieee 33 bus radial system. the obtained results clearly reveal the effectiveness of the proposed algorithm in total active power losses minimizing compared to pso algorithm. references [1] r. d. mohammedi et al, optimal dg placement and sizing in radial distribution systems using nsga-ii for power loss minimization and voltage stability enhancement, international review of electrical engineering, vol 8, nov/dec 2013. [2] p.a. daly, j. morrison, understanding the potential benefits of distributed generation on power delivery systems, rural electri power conference, 29 april – 1 may 2001, pp. a211 – a213. [3] p. chiradeja, r. ramakumar, an approach to quantify the technical benefits of distributed generation, ieee trans energy conversion, vol. 19, no. 4, 2004, pp. 764-773. [4] m. maamir, a. betka, h. aboub, modeling and simulation of energy management hybrid sources system composed of solar-pv and battery, international journal of energetica, vol. 1, no. 1, 2016, pp. 12-19. [5] caisheng w, nehrir mh, analytical approaches for optimal placement of distributed generation sources in power systems. ieee t power syst 2004;19(4):2068–76. [6] t. gözel et al, an analytical method for the sizing and siting of distributed generators in radial systems, electric power systems research, vol. 79, 2009, pp. 912-918. [7] a.lakshmi devi et al, a new analytical method for the sizing and siting of dg in radial system to minimize real power losses, international journal of computational engineering research, vol. 2 issue. 7, november 2012. [8] r. s. rao et al, optimization of distribution network configuration for loss reduction using artificial bee colony algorithm, world academy of science, engineering and technology 45 (2008), pp 708-714. [9] z. moravej et al, a novel approach based on cuckoo search for dg allocation in distribution network, international journal of electrical power & energy systems, vol. 44, 2013, pp. 672-679. [10] w. s. tan et al, allocation and sizing of dg using cuckoo search algorithm, in power and energy (pecon), 2012 ieee international conference on, 2012, pp. 133-138. [11] s. kansal et al, optimal placement of distributed generation in distribution networks, international journal of engineering, science and technology, vol. 3, no. 3, 2011, pp. 47-55 [12] t. v. kumar et al, implementation of novel optimization algorithm for optimal placement and sizing of capacitor banks in radial distribution systems for power loss minimization and net savings maximization, international journal of computer applications 108, december 2014. [13] m. nayeripour et al, multi-objective placement and sizing of dgs in distribution networks ensuring transient stability using hybrid evolutionary algorithm, renewable and sustainable energy reviews 25, 2013, pp759–767. [14] m.m. aman et al, a new approach for optimum dg placement and sizing based on voltage stability maximization and minimization of power losses, energy conversion and management 70, 2013, pp 202–210. [15] m. begovic et al, summary of system protection and voltage stability, power delivery, ieee transactions on, vol. 10, 1995, pp 631-638. [16] x.-s. yang, firefly algorithms for multimodal optimization, stochastic algorithms: foundation and applications saga 2009, vol.5792, 2009, pp. 169-178. [17] m. jamil et al, optimal allocation of spv based dg system for loss reduction and voltage improvement in radial distribution systems using approximate reasoning, in power electronics (iicpe), 2012 ieee 5th india international conference on, 2012, pp. 1-5. a. active power loss  total loss reduction (tlr) b. power constraint c. voltage constraint d. active power losses constraint e. distributed generation size constraint v. application of the firefly algorithm to the problem  ieee 33-bus radial distribution system f. results g. discussion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 46-49 ijeca-issn: 2543-3717. june 2017 page 46 piezometric variation of the water table in the the municipality of eloued, south-east algeria zine brahim 1 , zaiz issam 2 1 department of civil engineering and hydraulic, university of kasdi merbah, ouargla, algeria 2 department of civil engineering and hydraulic, university of kasdi merbah, ouargla, algeria hydro.br@gmail.com abstract – municipality of el-oued has been confronted with the phenomenon of the upwelling of water for several years and without almost any cease to become more extensive each year. this phenomenon took very alarming dimensions the last twenty years. the use of the deep layers water (the continental intercalary and the final complex) in an excessive way considerably increased the volume of the water input, as well as the absence of a natural discharge system for the rejections of wastewater, are the principal causes of this ecological imbalance. contributing to the deterioration of the palm trees, the inundation of (ghouts) causes mortal consequences at the level of environment, agriculture, the economy and the health of municipality of el-oued. the piezometric variation of the water table has shown that in the areas of upwelling groundwater; correspond to piezometric depressions which has favored the accumulation and especially of the waste water. keywords: piezometric variation, water table, el-oued, depressions. received: 01/06/2017 – accepted: 27/06/2017 i. introduction these some regions such as the municipality of el-oued are confronted with the phenomenon of the rise in surface area, groundwater for several years and which keeps growing every year. this phenomenon of the upwelling of groundwater has assumed very alarming dimensions in recent years. the use of deep water (the terminal complex and the continental intercalary) in an excessive manner has considerably increased the volume of inputs, as well as leakage from the drinking water supply networks and the absence of a natural outlet for the discharges of sewage, are the main causes of this ecological imbalance. contributing to the decline of palm trees, the flooding of craters and depressions (ghouts). in this study, we looked at the level of ground water in urban and agricultural areas. ii. the geographical situation of municipality of el-oued the study area is located in the commune of eloued, the most agglomerated commune, is the chief place of el-oued, one of the main oases of the algerian northern sahara in the eastern erg. it is located in the south-east of algeria, about 700 km south-east of algiers and 350 km west of gabes (tunisia), north-east of the northern sahara. the municipality covers a total area of 79 km2, is limited to the north by the commune of kouinine, to the south by the municipality of bayadha, in the east by the commune of trifaoui and to the west by the commune of oued alenda. this commune extends between the following coordinates (utm, clark 1880) (figure 1): x = 298000 m; y = 3690000 m x = 304000 m; y = 3698000 m figure 1. geographical location of the study area. zine brahim et al. ijeca-issn: 2543-3717. june 2017 page 47 the valley of the souf contains a number of oases in the grand erg oriental, and as in most oasis in the northern sahara, the only water resources available for irrigation are underground water tables. those of the souf region are contained in aquifer formations of different natures. at the regional and country levels, the authors (baba sy, 2005, brl-bneder, 1999, cornet 1961, castany 1982, cornet and gouscov 1952, guendouz a, et al., 2003, unesco, 1972a) [1,2]. generally distinguish three geological complexes that contain groundwater resources of thickness and hydrogeological characteristics variables. the water table throughout the souf rests on the argilo-gypsum floor of the upper pontian. the aeration zone separating the surface of this water from the surface of the soil does not exceed an average depth of more than 40 m of non-aquifer sand [3]. iii. digital terrain model of the study area the study area occupies a large part of the municipality of el oued in which the topographic surface has been interpolated from 9892 ground leveled points for the sanitation network in the urban areas and 129 points in the non-urban areas, ie 10021 points covering the area of a digital terrain model (figure 2). according to the digital terrain model, this region has an average altitude of 82 m above mean sea level and is marked by a significant decrease from southwest to north to reach 66 m altitude. the topographical features have been shown in the following table in elevation ranges (table1). table 1. distribution of elevation ranges altitude range (m) surface (km 2 ) area (%) 64 70 70 76 76 82 82 88 88 94 94 100 4.2 15 13 3.6 3 1.2 10.5 37.5 32.5 9 7.5 3 figure 2. digital terrain model of the study area. the study area is characterized by two important domes in the cities of mars 19 and mai 8 and a depression in the cities choot and nezla. iv. piezometry of the water table of the souf region iv.1. inventory of water points the monitoring network of the city of oued souf, set up in 2006 was originally composed of 62 points, spread over the city in a zone of 40 km 2 , the coordinates were recorded to the global positioning system and all the data collected were introduced into a database linked to a geographic information system (figure 3). in 2008, a companion for the measurement of groundwater piezometric levels was carried out by the national agency of hydraulic resources in mai. in 2009, a companion was made to measure the piezometric levels of the water table in the flooded areas in january and mai. zine brahim et al. ijeca-issn: 2543-3717. june 2017 page 48 figure 3. network monitoring of the souf region. iv.2. the piezometry of the free water table in 2008 the piezometric measurements carried out in mai 2008 by the national agency of hydraulic resources enabled us to establish a piezometric map (figure 4). it is noted that the groundwater is characterized the existence of three important areas. zone a1, that of the city of 19 mars, errimel west, errimel east, el-mujahideen west, el-mujahideen east, 300 housing units, 400 housing units, tawba, amir abdelkader, 17 october and ennour a piezometric dome with an altitude ranging from 74.7 m to 77.7 m. zone b1, represented by the cities 08 mai and 01 november at northeast, characterized by a piezometric dome with an altitude ranging from 67.2 m to 70.2 m. zone c1, at the center represented by the choot city, corresponding to a major depression of an altitude ranging from 64.2 m to 65.7 m, it is characterized by the rise of the surface water table (figure 4). we note in passing that: the piezometric dome corresponds to a feeding zone. a piezometric depression corresponds to drainage. the water table in the town of oued souf has the following flow directions: from northeast of zone a1 to zone c1 (cited choot). from the north of zone a1 to the north-west of the town near point g12. from the southwest of the town near the p17 piezometer to the northwest of the town near the g12 well. from the east of zone a1 towards the east the town near the well h80. from the south of zone b1 to zone c1 (quoted choot). a divergent flow is obtained from the piezometric dome of zone a1, from the sw to the ne and from the ne to the sw. there is a second flow diverging from the piezometric dome of zone b1 to ne therefore from east to west and from west to east. a convergence of the flows of all the senses towards zone c1 of the choot. figure 4. piezometric map of the water table of the of oued souf in 2008. iv.3. the piezometry of the free water table in 2009 in order to follow the evolution of the water table, we made piezometric measurements in mai 2009, which enabled us to establish a piezometric map (figure5). we have noticed that the water table has retained the same structure as before, with a significant rise in the piezometric level. we estimate this rise to 50000 m3 of water in one year. zine brahim et al. ijeca-issn: 2543-3717. june 2017 page 49 figure. 5 piezometric map of the water table of the of oued souf in 2009. iv.4. piezometry between 2009 and 2008 the map of the figure below (figure 5) shows the evolution of the piezometric level from one year to the next. figure. 6 piezometric beating map between 2009 and 2008. between may 2009 and may 2008, a groundwater level rise of 1.2 meters was observed at the feeding zones represented by the agglomerations and a drawdown of 0.6 meters in the evaporation zones of open water surfaces ( chott, flooded ghouts) and vegetation evapotranspiration (traditional ghout crops, irrigated crops by traditional or improved wells in the groundwater). v. conclusion the only available water resources are underground water tables. the aquifer of the valley of the souf is contained in formations of different nature. feeding of the surface aquifer is ensured by the infiltration of deep ct and ci drilling waters, by urban water, by irrigation water, and by rare and low exceptional precipitation. this water table goes up in the depressions, under the agglomerations and falls in the irrigated zones. the general direction of groundwater flow is from south west to the north east. the piezometric maps of the city of el oued show this situation well. faced with this critical situation, especially in the agglomeration areas, there are several solutions that have been proposed and that are currently being implemented to shape a new sufi landscape. the increase in pumped volumes and the development of saharan agriculture have repercussions at the level of these saharan aquifers (terminal complex) in the form of the drying up of the sources and the weakening or losing of artesianism as in our region. this increasing exploitation is likely to lead to changes in water quality in the vulnerable zones (salt and mineral concentrations) over the long term [4]. references [1] m. baba sy, besbes m., 2006. holocene recharge and present recharge of the saharan aquifers. a study by numerical modelling, colloque international gestion des grands aquifères 30 mai-1er juin 2006, dijon, france. p 16. [2] a.guendouz, a.s. moulla, w.m. edmunds, k. zouari, p.shand, a.mamou, 20 may 2003. hydrogéochemical and isotopic evolution of water in the complexe terminal aquifer in the algerian sahara, hydrogeology journal (2003). pp 485-495. [3] a.r. voisin, 2004. les souf monographie, edition elwalid, el oued-algérie. p 319. [4] a. miloudi, b. remini, water potentiality of sustainable management challenges in the oued souf region, south east algeria, international journal of energetica (ijeca), vol.1 issue.1, 2016, pp.36-39. i. introduction ii. the geographical situation of municipality of el-oued iii. digital terrain model of the study area iv. piezometry of the water table of the souf region iv.1. inventory of water points iv.2. the piezometry of the free water table in 2008 iv.3. the piezometry of the free water table in 2009 iv.4. piezometry between 2009 and 2008 v. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 42-45 ijeca-issn: 2543-3717. june 2017 page 42 seasonal effect on solar distillation in the el-oued region of south-east algeria a. khechekhouche 1,3 , a. boukhari 2 , z. driss 3 , n. benhissen 4 1renewable energy research center in arid zones, el-oued university, algeria 2mechanical engineering department, faculty of technology, el-oued university, algeria 3laboratory of electromechanical systems (lasem), enis, university of sfax, tunisia 4electrotechnical department, university of trois révères, québec, canada abder03@hotmail.com abstract – in the present purely experimental work, we tested a solar distiller with a simple slope in the region of el-oued located in the south-east of algeria, during the winter then the summer seasons at the same place. dimensions of the studied device are 1000 x 500 mm, while the depth of the water to be distilled is 1 cm, the glazing thickness is 4 mm, and the tilt angle with respect to the horizontal is 10 °.the aim of this work is to compare distillation between winter (january) and summer (may) to show that weather factors such as solar radiation, ambient temperature and humidity are influential on the distiller productivity. the amount of distilled water in winter was about 119 ml per day. however, that in summer was 1127 ml per day in total, so it is an increase of more than 9 times the production of distilled water. key words: solar distiller, solar radiation, humidity, distilled water, productivity received: 31/05/2017 – accepted: 27/06/2017 i. introduction desalination technology has become very developed due to the new techniques that often appear, but each technique has its advantages and disadvantages [1, 2]. the most economical way to purify or desalt water is by solar distillation. the efficiency of this technique is relatively low compared to the other distillation modes, but this drawback is compensated for by the fact that this process only requires the sun's radiation to function. several researchers have studied and improved flat solar distillers by adding a black absorber, a mirror, or preheating. others have doubled the glass of the distiller [3], whilst others have played the angle of the glazing [4]. the water desalination technology has its advantages and disadvantages [5]. elango et al. [6] studied the performance of a single slope solar distiller with and without nanofluids. the distillers were tested with three nanofluids (al2o3, zno, sno2) with different concentrations. using al2o3 nano-water fluid at 0.1% concentration gave 29.95% more distillate output due to its higher thermal conductivity. the preparation of nanofluids is a costly and dangerous technique. this work gives us a clear experimental response on the solar radiation and also the ambient temperature influences on solar distillation with a simple effect. ii. materials and method ii.1. description of the solar distiller the single slope solar distiller (see figure 1) is a well-known device, with simple design and construction because its components are available in all world’s markets. figure 1. single slope solar distiller ii.2. operating principle the increase in temperature due to the greenhouse effect causes the air to warm up above the saline water, which in turn evaporates. this evaporation capacity increases as the temperature rises until the air reaches its saturation with water vapour: the relative humidity is then 100%. the steam contained in the hot air condenses in contact with the cold glazing (figure 2). this contact led to the formation of water droplets, which flow towards the lower part of the sloped glazing. a collector (tube) groups these droplets and then led them to be a. khechekhouche et al. ijeca-issn: 2543-3717. june 2017 page 43 accumulated into a storage tank. figure 2. the prototype distiller ii.3. essential experimental system components the solar distiller is essentially composed of: • a box of wood having the dimensions (1000 x 500 mm), the lid slope is 10° with respect to the horizontal direction, in the way to have the maximum of sunshine. • an ordinary glass lid (1000 x 600 mm) with a thickness of 4 mm. • a pvc plastic tube of 1100 mm length and 25 mm in diameter. ii.4. thermocouples locations temperature measurements are made by means of five thermocouples positioned as perfected in figure 3: • temperature of the inside face of the glazing. • temperature of the outside face of the glazing. • temperature inside the distiller. • temperature of the water to be distilled. • ambient temperature. figure 3. locations of the used thermocouples ii.5. meteorological conditions of the experiments two experiments were carried out at the university of el-oued (south-east algeria). the first on january 13, 2017 and the second on may 5, 2017 during the summer. table 1 shows the meteorological conditions of the experiments. table 1 meteorological conditions in summer and winter may (summer 2017) january (winter 2017) sunrise sunset ambient temperature atmospheric pressure 05:41 am 07:19 pm 26-35°c 1013 mb 07:38 am 05:46 pm 11-17°c 1031 mb ii.6. conduct of the experiment the experiments are made according to the geographical coordinates of the city of el-oued located at 33.3676° n latitude and 6.8516° e longitude. the same distiller was exposed to the sun in the same place, same position, same water nature and the same water quantity to be distilled, but in two different seasons. the first experiment was carried out in january 2017 (in winter), while the second in may 2017 (in summer) in order to see the influence of meteorological effects on the phenomenon of solar distillation. temperature sampling was carried out every one hour during the period from 9:30 am to 4:10 pm for both experiments, so the same period of sunshine was maintained to eliminate any ambiguities in relation to this factor (i.e. sunshine duration). iii. results and discussion meteorological factors such as solar radiation, ambient temperature and humidity influence the distiller operating. the results obtained are illustrated in the following figures. figure 4 shows the solar radiation evolution in wh/m 2 during the day time (in hours) for both experiments, one in winter and the other in summer. the radiation increases gradually in both cases until reaching a maximum value between noon and 2:00 pm with the only difference that the solar radiation in winter has not exceeded the value of 600 wh/m 2 but in summer it has reached the value of 1000 wh/m 2 . solar radiation is the key parameter in solar distillation. 0 200 400 600 800 1000 1200 9h00 10h00 11h00 12h00 13h00 14h00 15h00 16h00 time (h) r a d ia ti o n ( w h /m 2 ) summar winter figure 4. evolution of solar radiation a. khechekhouche et al. ijeca-issn: 2543-3717. june 2017 page 44 figure 5 shows the relationship between the day time (hours) and the ambient temperature for the two experiments. the latter increases gradually until reaching a maximum constant value between 01:00 pm and 04:00 pm [7]. figure 5 also shows that the ambient temperature is greater in summer where it has exceeded 30 °c, than that in winter which has not reached the value of 18 °c. the ambient temperature is also a crucial factor influencing the phenomenon of solar distillation. figure 5. the evolution of the ambient temperature figures 6 and 7 illustrate the dependence between the day time (hours) and the interior temperature of the glazing for water distiller in the experiments. we can see that the temperature difference between the basin water and the inner glazing temperature is also another important factor for the distillation process. the mean temperature difference between the inner glazing and the basin water in the first experiment (carried out in winter) is of the order of 32 °c. however, it is of the order of 130 °c in the second experiment (carried out in summer). this large difference is favorable for the improvement of the productivity of distilled water due to the evaporation phenomenon of water. 0 5 10 15 20 25 30 35 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:10 time (h) a m b ie n t t e m p e ra tu re ( °c ) winter summar figure 6. time evolution of the inner glazing temperature 0 10 20 30 40 50 60 70 80 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:10 time (h) t e m p e ra tu re ( ° c ) winter summar figure 7. time evolution of the basin water temperature figure 7 shows that the temperature evolution of the basin water in summer is very high, and exceeds the value of 50 °c to reach a maximum temperature of 73 °c at 01:30 pm. all temperatures in winter are below the value of 40 °c. the temperature of the water to be distilled in the basin is an essential factor in the phenomenon of solar distillation. figure 8 shows the temporal evolution of the internal temperature of the distiller in the two seasons. this temperature is maximal between 12:30 am and 03: 30 pm. also, high difference between summer temperatures and those taken in winter is obvious. 0 10 20 30 40 50 60 70 80 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:10 time (h) t e m p e ra tu re ( ° c ) winter summar figure 8. temperature evolution inside the distiller during winter and summer figure 9 illustrates the relation between the day time and the outer glazing temperature, where the phenomenon of natural convection between the glazing and the atmosphere takes place. the temperature increases until reaching a maximum value between noon and 04:00 pm. a. khechekhouche et al. ijeca-issn: 2543-3717. june 2017 page 45 0 10 20 30 40 50 60 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:10 time (h) t e m p e ra tu re ( °c ) winter summar figure 9. evolution of the glazing temperature on its external face obviously, from figure 10 we can see the dependence of the productivity of the distilled water on daytime and season for both experiments. note that the first 4 sunshine hours in the winter did not trigger the distillation, but the first hour of sunshine in the summer triggered the distillation. consequently, the production of distilled water in summer is more profitable than in winter. the total amount of water produced by the winter experiment was 119 ml, and that in summer was 1127 ml over a period of 6 hours and 40 minutes. the distillate yield increased by 1008 ml / day in the summer. 0 50 100 150 200 250 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:10 time (h) m l winter summar figure.10. productivity of distilled water through experiments iv. conclusion according to the results obtained in the present work, solar distillation is more productive and more favorable in the summer period than in the winter period. this fact is due to the increase of the solar radiation. the maximum distilled water quantity for 6 hours and 40 minutes is recorded in may 2017 (in summer) for an amount of 1127 ml, whereas in january 2017 (in winter), the yielded quantity is about 119 ml. those results demonstrate manifestly the difference in distilled water productivity between the two seasons. therefore, any increase in solar radiation necessarily yields an increase in the distilled water productivity, without neglecting other key parameters such as ambient temperature. references [1] n. ghaffour, j. bundschuh, h. mahmoudi, m.f.a. goosen. renewable energy-driven desalination technologies: a comprehensive review on challenges and potential applications of integrated systems, desalination, vol 356, 15 january 2015, pp. 94-114. [2] k. choon ng, k. thu, s. jin oh, l. ang, m. wakil shahzad, a. bin ismail, recent developments in thermally-driven seawater desalination: energy efficiency improvement by hybridization of the med and ad cycles, desalination, vol 356, january 2015, pp. 255-270. [3] j. lindblom, solar thermal technologies for seawater, desalination: state of the art, renewable energy system lulea university of technology, lulea, 2010. [4] n. retiel, etude expérimentale d’un distillateur solaire plan amélior, revue des energies renouvelables vol. 11, no 4, 2008, pp. 635 – 642. [5] l. cherrared, amélioration du rendement d’un distillateur solaire à effet de serre, revue des energies renouvelables, valorisation, 1999, pp. 121-124. [6] t. elango, a. kannan and k. murugavel, performance study on single basin single slope solar still with different water nanofluids. desalination, volume 360, 2015, pp. 45– 51. [7] m. ghodbane et b. boumeddane, estimating solar radiation according to semi empirical approach of perrin de brichambaut: application on several areas with different climate in algeria, international journal of energetica, vol. 1, no 1, 2016, pp. 20-29. i. introduction ii. materials and method ii.5. meteorological conditions of the experiments ii.6. conduct of the experiment iii. results and discussion iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 64-70 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 64 anfis models for fault detection and isolation in the drive train of a wind turbine zakaria zemali * , lakhmissi cherroun, nadji hadroug, ahmed hafaifa applied automation and industrial diagnostics laboratory, faculty of science and technology, university of djelfa, 17000 dz, algeria *corresponding author: email: z.zemali@univ-djelfa.dz abstract – the paper aims to improve the fault detection and isolation process in wind turbine systems by developing intelligent systems that can effectively identify and isolate faults. specifically, the paper focuses on the drive train part of a horizontal axis wind turbine machine. the proposed fault diagnostic strategy is designed using an adaptive neural fuzzy inference system (anfis), which is a type of artificial neural network that combines the advantages of both fuzzy logic and neural networks. the anfis is used to generate residuals that occur after faults have been detected, and to determine the appropriate thresholds needed to correctly detect faults. the simulation results show that the proposed fault diagnostic strategy is effective in detecting faults in the drive train part of the wind turbine system. by using intelligent systems such as anfis, the fault detection process can be automated and streamlined, potentially reducing maintenance costs and improving the overall performance and efficiency of wind turbine systems. keywords: wind turbine, drive train, fault detection, anfis, residual, estimation. received: 12/11/2022 – revised 15/12/2022 – accepted: 25/12/2022 i. introduction recently, many types of wind turbine systems have been developed and installed to power production. however, the operation long time becomes more challenging for the wind turbines because they are exposed to environmental facts. to maintain their safety, much research has been proposed to maintain their availability [1, 2]. a new approach based on ultrasonic was used on two real blades to detect the elimination of it [3], among the most commonly used methods, are those based on data where they are used to generate residuals for diagnosis of various faults [4, 5], a model of a nominal power 4.8 mw wind turbine was developed and a set of actuator and sensor faults is proposed in paper [6]. a method based on intelligent technical has used fuzzy and neural networks to derive a nonlinear dynamic connection between the measured input-output parameters and the presumed fault signal [7]. kalman filter as an observer with artificial neural networks has been proposed for the diagnosis of the blade pitch system fault for wind turbines and floating wind turbines in papers [8, 9]. a deep convolutional network for feature learning and classification based on scada measurements is proposed for sensor fault detection [10]. hence, a new intelligent method of diagnosing faults via deep learning called ce-cnn (as a convolutional neural network) has been proposed for the diagnosis of bearing faults in the wind turbine [11]. it has a good advantage in generalization ability, not only a good precision of classification. the model can balance the depth and width of the network, and thus control the growth of parameters and calculations. a new algorithm for diagnosis, sensor, and actuator diagnosis is solved, by integrating analysis techniques into fast multi-linear principal components with fourier transform and zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 65 uncorrelated is presented in [12]. the use of the principal component analysis (pca) technique to classify the faults in the wind turbine is investigated in [13]. the svm method is combined with a model-based observer for the diagnosis of faults actuator and sensor in the wind turbine benchmark [14]. an effective fault diagnosis structure is proposed for the pitch system part of a wind turbine benchmark [15]. the elaborated structure is based on the physical redundancy of sensors and actuators to generate the appropriate residuals between all measurements. then a crisp logic technique is used to classify actuator and sensor faults [16]. a fault detection scheme for a wind turbine based on the takagi–sugeno interval observer, a set of interval observers is used to detect the sensor fault [17]. the objective of this paper is to propose a fault diagnosis system based on intelligent techniques as equivalent models using an adaptive neural network-based fuzzy inference system (anfis) as an output estimator to detect and isolate faults in a wind turbine system. anfis is used for generating residuals and as a decision system for the detection and classification of the occurred failures in the drive train part. ii. description of the wind turbine the function of the wind turbine is to generate electrical energy from the wind energy. the three blades of the turbine exploit the wind to produce kinetic energy in the two shafts. the wind turbine is composed mainly of four components as depicted in fig. 1: pitch system, drive train, converter with its generator, and control [6, 18]. each part is modeled as follows: the module temperatures, calibrated platinum sensors with ±0.5 °c measurement accuracy, and 0.1 °c resolution, placed on the backside center of each module are used. the data recorded by the system included environment temperature, module temperature, total insolation, operating current and voltage, wind speed, and total output power. the data captured starts in march 2012 and ends in may 2015. however, the point of focus in this research was the year 2014 since it provided the greatest amount of data as compared to the other years. figure 1. wind turbine structure  pitch system model: it is the process of adjusting the angle of the turbine blades to optimize power output. where a hydraulic motor is employed for each blade. the pitch system is defined by a secondorder closed-loop transfer function [18] between the measured pitch angle βm and its reference βref as shown in eq. 1. (1) ζ: is the dumping factor equal to 0.6, ωn is the natural frequency equal to 11.11 rad/s.  drive train model: it's like a locomotive for the turbine. it consists of two shafts (low-speed shaft and high-speed shaft) for increasing the speed of the rotor to the generator. the state space model is: (2) the output of the state space is: (3)  generator with converter: its role is to convert the mechanical energy generated from rotating the shaft into electrical energy. it is modeled by a transfer function of the first order: (4) where τrg: the reference torque of the generator is, α gc is a parameter model. the produced power is defined zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 66 as: (5) where the generator function efficiency ηg = 0.98.  controller: its role is to generate appropriate control actions to maintain the output of 4.8 mw during its period of operation by a suitable wind speed. the employed controller type is a proportional integrator (pi), which works in two intervals for various wind speeds. iii. brief on anfis model adaptive network based fuzzy inference system (anfis) is a hybrid system between the fuzzy inference system (fis) and artificial neural network (ann) [19, 21]. this system as depicted in fig. 2 has the advantages of the two approaches, the powerful knowledge representation of fis and the learning capacities of ann. so, the hybrid anfis system exploits these characteristics to generate an optimal fis using the available data on the studied process. as the name suggests adaptive network, the neural network adapts to the input and output values of the system, because the network contains a group of nodes, a node that operates on itself to generate an output signal to another node via the input signal, where the function of each node changes depending on the general behaviour of the network. each layer of this ann defines an operation of fis [19, 20, 21]. anfis is composed of five layers: the first layer for fuzzification, the second layer to calculate the degree of activation, the third layer for normalization, the fourth layer to calculate rule outputs based on the consequent parameters, and finally the fifth layer for computing the overall output of the fis. figure 2. anfis architecture proposed fault diagnosis strategy in this section, we will present and explain the proposed fault diagnostic strategy in this paper, based on an equivalent model of the anfis system for the drive train part of a wind turbine benchmark. the proposed structure is illustrated in figure 3, where the simulated wind turbine is based on the benchmark model of odgaard [18]. this fault detection and isolation strategy is tested on the drive train part in order to detect occurred system faults. as depicted in figure 3. the anfis model is trained and elaborated as an equivalent model of the wind turbine machine. this intelligent system is used to generate residuals as mentioned in the form of step (1). then, in the second step, a set of anfis models have been employed to decide and detect the occurred faults. in this calculation stage, the diagnosis structure must determine the existence of faults. the parameters of tested system faults in the simulated scenario are presented in table. 1. in this paper, we will simulate faults in the generator speed (ωg) and rotor speed (ωr) for the drive train as a modification in the efficiency from ηdt =0.97 to ηdt2=0.3. the proposed diagnosis structure is based on three steps: output estimation using an equivalent model based on neuro-fuzzy system, residual generation, and residual evaluation. table. 1 fault scenario figure 3. structure of the diagnosis approach based on anfis models 1) output estimation: an anfis system is used as an equivalent model to ensure the output of the system without fault, while the model is not affected by the zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 67 system damage and its output is always without fault. 2) residual generation: as shown in figure 3, in this step, the obtained residual by comparing the output of the system (yt ) and the equivalent model system (ῠt), each difference between them is a residual, the following equation at each time (6) 3) residual evaluation: after obtaining the residuals, another anfis is used with a fixed threshold to detect the fault. when the signal exceeds this threshold, it is considered a fault, else, it doesn't consider a fault. iv. results and discussions in this section, we will present the obtained simulation results of the proposed diagnosis structure (shown in figure 3) for the drive train system. the developed framework is tested on the wind turbine benchmark measurements [6, 18]. firstly, the simulation results will be displayed without faults and then it will be studied with faults to demonstrate the ability of the designed anfis models to detect faults. iv.1. dynamic without fault for (ωr) and (ωg) in the case of the system without fault, in figures 4 and 5 the speed of the rotor and the generator denoted (ωg) and (ωg), and the calculated residuals are presented respectively. figure 4 (a) shows the output of the rotor ῠt. the capture zoom at the interval time speed (yt) and the estimated output by the equivalent model [2000s2200s] show that both signals are very similar. whereas, figure 4 (b) presents the obtained residual as calculated using eq.6. this result shows a good estimation of the output signal at a rotor speed. a b figure 4. rotor speed without fault (ωr) and the residual the second output of the drive train as a speed generator denoted (ωg) and the estimated output of the equivalent model anfis are presented in figure 5(a). it's clearly shown the similarity of the two responses, which demonstrates the ability of the designed anfis model to perceive the output. this is depicted in the capture zoom, which shows that both signals are identical at the interval time [2000s-2200s]. figure 5(b) presents the residual between both outputs. zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 68 a b figure 5. (a) generator speed without fault (ωr), (b) generated residual iv.2. dynamic with fault for (ωr) and (ωg) the fault that occurred in the drive train was caused by the increased level of drive train vibrations that can be simulated by changing the parameter from ηdt = 0.97 to ηdt2=0.3 affected by both output generator speed (ωg) and the rotor speed (ωr). figure 6(a) shows both outputs of the rotor speed (ωr) as an output y(t), ῠ(t). the occurred fault in the rotor speed is presented and the output of the equivalent model denoted capture zoom presents the fault that happened at the interval time [2000s-2200s] at a period time of 200s. figure 6(b) presents the obtained residual. figure 6. (a) generator speed with the fault (ωr), (b) generated residual the same fault occurred in the generator speed (ωg) at the same time [2000s-2200s]. figure 7(a) illustrates the capture zoom of the fault that happened in the generator speed during 200s. whereas, figure 7(b) shows the residual and the lower defined threshold. zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 69 figure 7. (a) generator speed with the fault (ωr), and (b) the residual figures 8 (a, b) present detection of a fault in rotor speed and generator speed respectively at the same interval time [2000s-2200s] during a period of 200s. a b figure 8. (a) detection of faults in the rotor speed (ωr) and (b) generator speed (ωg) v. conclusion in this paper, a powerful and efficient fault diagnostic strategy is proposed for the drive train part of the horizontal axis with three blades wind turbine machine. the elaborated structure is based on the development of an equivalent model of the drive train using the anfis approach. this hybrid model can generate residuals resulting from the occurrence of faults in the studied system. a fixed threshold is determined by another intelligent system to detect the fault that occurred in the drive train sub-system, especially in generator and rotor speeds. the obtained simulation results demonstrate the ability of this diagnosis strategy to detect faults in the drive train correctly. in future work, all faults in the wind turbine will be tested and investigated using this type of approach as intelligent equivalent models. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. zakaria zemali et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 64-70 page 70 references [1] z. gao, x. liu, “an overview on fault diagnosis, prognosis and resilient control for wind turbine systems,” processes, vol. 9, 300. 2021, https://doi.org/10.3390/ pr9020300 [2] l. zepeng, l. zhang, “a review of failure modes, condition monitoring and fault diagnosis methods for large-scale wind turbine bearings,” measurement, vol. 149, 2020, pp. 107002 https://doi.org/10.1016/j.measurement.2019.107002 [3] f. p. marquez, c. quiterio gómez muñoz, “a new approach for fault detection, location and diagnosis by ultrasonic testing,” energies, vol. 13, no. 5, 2020, pp. 1192; https://doi.org/10.3390/en13051192 [4] [m. s. li, d. yd. yu, z. m. chen, k. s. xiahou, t. y. ji.q. h. wu, “a data-driven residual-based method for fault diagnosis and isolation in wind turbines,” ieee transactions on sustainable energy, vol.10, no 2, 2019. [5] shen yin guang wang hamid resa karim, “datadriven design of robust fault detection system for wind turbines,” mechatronics, vol. 24, no. 4, 2014, pp. 298-306 https://doi.org/10.1016/j.mechatronics.2013.11.009 [6] p. s. odgaard, and m. kinnaert, “fault-tolerant control of wind turbines: a benchmark model,” ieee transactions on control systems technology. vol. 21, no 4, 2013, pp. 1168–1182. [7] s. simani and p. castaldi, “intelligent fault diagnosis techniques applied to an offshore wind turbine system,” appl. sci., vol 9, no. 4, 2019, pp. 783, https://doi.org/10.3390/app9040783 [8] s. cho, m. choi, z. geo and t. moan, fault detection and diagnosis of a blade pitch system in a floating wind turbine based on kalman filters and artificial neural networks renewable energy https://doi.org/10.1016/j.renene.2020.12.116 [9] z. zemali, l. cherroun, a. hafaifa and n. hadroug, fault diagnosis structure based on kalman filter for the pitch system of a wind turbine process, 2 nd algerian symposium on renewable energy and materials asrem2022, march 16-17, 2022, medea algeria. [10] h. wang, h. wang, g. jiang, y. wang, s. ren, ''a multiscale spatio temporal convolutional deep belief network for sensor fault detection of wind turbine,'' sensors, vol. 20, no. 12, 2020, pp. 1–14. [11] y. chang, j. chen, c. qu, t. pan, “intelligent fault diagnosis of wind turbines via a deep learning network using parallel convolution layers with multi-scale kernels,” renewable energy, vol. 135, 2020, pp. 205-21. https://doi.org/10.1016/j.renene.2020.02.004 [12] y. fu, z. gao, y. liu, a. zhang, x. yin, actuator and sensor fault classification for wind turbine systems based on fast fourier transform and uncorrelated multi-linear principal component analysis techniques, processes, vol. 8, no. 9, 2020, pp. 1066 [13] y. fu, y. liu, z. gao, fault classification in wind turbines using principal component analysis technique, in: ieee 17th international conference on industrial informatics (indin),, ieee, 2019, pp. 1303e1308. [14] n. laouti, s. othman, m. alamir, n. s. othman. “combination of model-based observer and support vector machines for fault detection of wind turbines; “international journal of automation and computing, vol. 11, 2014, pp. 274-287. https://doi.org/10.1007/s11633-014-0790-9 [15] a. saci, l. cherroun, o. mansour and a. hafaifa, "effective fault diagnosis method for the pitch system of a wind turbine", first international conference on renewable energy advanced technologies and applications (icreata’21), october 2021, adrar-algeria. isbn: 978-99319819-0-9 [16] a. saci, l. cherroun, a. hafaifa and o. mansour, “effective fault diagnosis method for the pitch system, drive train and the generator with converter in a wind turbine system,” electrical engineering. vol. 104, no. 4, 2022, pp. 1967-1983, https://doi.org/10.1007/s00202-021-01446-8 [17] e. jesús pérez, f. lópez-estrada, v. puig, g. v. palomo, i. santos-ruiz, fault diagnosis in wind turbines based on anfis and takagi–sugeno interval observers, expert systems with applications, https://doi.org/10.1016/j.eswa.2022.117698 [18] p.f. odgaard, and kinnaert, m, “fault tolerant control of wind turbinesa benchmark model.” 7th ifac symposium on fault detection, supervision and safety of technical processes, 500, 155-160. [19] j. s. r. jang. anfis: adaptive network based fuzzy inference systems. ieee transactions on syst man cybern., vol. 23, no.5, 1993, pp. 665-685. [20] l. cherroun, n. hadroug, m. boumehraz, “hybrid approach based on anfis models for intelligent fault diagnosis in industrial actuator,” journal of electrical and control engineering, vol.3, no.4, 2013, pp. 17-22. [21] l. cherroun and m. boumehraz, "path following behavior for an autonomous mobile robot using neuro-fuzzy controller", international journal of systems assurance engineering and management, (ijsa), springer-verlag, vol. 5, no. 3, 2014, pp. 352360. https://www.sciencedirect.com/journal/measurement https://www.sciencedirect.com/journal/mechatronics https://www.sciencedirect.com/journal/renewable-energy international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 11-14 ijeca-issn: 2543-3717. june 2017 page 11 direct torque control of a doubly fed induction generator a. ben amar 1 , s. belkacem 1 , t. mahni 2 1 department of electrical engineering, university of batna, algera 2 lgeb laboratories, department of electrical engineering, university of biskra, algera b.asma39@gmail.com abstract – in this paper a direct torque control system is proposed and is applied to doubly fed induction generator (dfig) based wind power generation systems. in this control system the rotor flux and the electromagnetic torque are estimated based on the rotor voltage and currents measurements. the validity and effectiveness of this control is demonstrated by some simulation results. keywords: doubly fed induction generator (dfig), wind power generation systems, direct torque control (dtc), field oriented control (foc) surmised 26/04/2017 – accepted 25/05/2017 i. introduction doubly fed induction generators (dfigs) are used mainly for wind energy conversion in mw range. the stator is directly connected to grid while the rotor is fed through power electronic converter. the power electronic converter is rated at 25% to 30% of the generator rating for a variation in synchronous speed around ± 25%. the major advantages of the dfig based wind turbines are variable speed operation and stator power factor control from rotor side converter [1]. direct torque control (dtc) was proposed in1980s and then it was well developed in power electronics and drives application for its excellent steady state and transient performance [2-3]. compared to field oriented control (foc) technique, dtc system is very simple and robust because current regulators and complicate coordinate transformation are eliminated [3]. today direct torque control (dtc) is considered one of the most important techniques to achieve high dynamic performance in ac machines. the direct torque control (dtc) scheme has been increased due to several factors such as quick torque response and robustness against the machine parameter variations [4]. in this paper the conventional dtc algorithm using the hysteresis based voltage switching method is applied to dfig. ii. mathematical modeling of dfig the mathematical model of the dfig used in this paper is presented here using the d-q synchronous reference frame. the equations for the stator and rotor windings can be written as [5-6]: ⎩ ⎪⎪ ⎨ ⎪⎪ ⎧ ��� = ����� + ���� �� − �� ��� ��� = ����� + ���� �� + �� ��� ��� = �� ��� + ���� �� − �� ��� ��� = �� ��� + ���� �� + �� ��� � (1) where the rotor frequency ωr is given by: �� = �� − �ω vds, vqs, vdr, vqrare the d and q axis of the stator and rotor voltages; ids, iqs, idr, iqrare the d and qaxis of the stator and rotor currents;φds, φqs, φdr, φqr are the d and q axis of the stator and rotor fluxes; ωs is the angular velocity of the synchronously rotating reference frame; ωris the rotor angular velocity; and rs,rrare the stator and rotor resistances. the flux equations of the dfig are: ⎩ ⎨ ⎧ ��� = �� ��� + ���� ��� = �� ��� + ���� ��� = �� ��� + ���� ��� = �� ��� + ���� � (2) where: ls, lr and m are the stator, rotor and mutual inductances, respectively. the electromagnetic torque given by t� = − � � p � �� (i��φ�� − i��φ��) (3) p is dfig pairs of poles number. mailto:b.asma39@gmail.com a.ben amar et al. ijeca-issn: 2543-3717. june 2017 page 12 iii. direct torque control the direct torque control (dtc) method is basically a performance enhanced scalar control method. the main features of dtc are direct control of flux and torque by the selection of optimum inverter switching vector, indirect control of stator at standstill. the advantages of dtc are minimal torque response time, absence of coordinate current and voltages, approximately estimators implying the consequent parameters identification [7]. sinusoidal stator flux and stator currents and high dynamic performance even transformations which are required in most of vector controlled drive implementation and absence of separate voltage modulation block which is required in vector controlled drives. the disadvantages of dtc are inherent torque and stator flux ripple and requirement for flux and torque as shown in fig. 1, the position of the rotor flux is divided into six sectors. there are also 8 voltage vectors which correspond to possible inverter states. these vectors are shown in fig. 1. there are also six active vectors v1, v2,…, v6 and two zero vectors v0and v7. figure. 1 inverter output voltages a. estimation of rotor flux the magnitude of the rotor flux is estimated from its components along the α and βaxes[8]. � ��� (�) = ∫ (��� − �� ��� )�� � � ��� (�) = ∫ ���� − �� ��� ��� � � � (4) the amplitude of the rotor flux vector can be expressed by: �� = ���� � + ��� � (5) the angle α� of the rotor flux φr is determined by: �� = ����� ��� ��� (6) b. estimation of the electromagnetic torque the electromagnetic torque can be estimated starting from the estimated value of the flux (��� and ��� ) and the calculated values of the current (��� and ��� ) [8]: �� = �������� − ������� (7) the dtc control is based on the regulation of the rotor flux magnitude and the value of the torque of the machine. the switching table applied in this work is a standard table. this table makes it possible to define the vector which it is necessary to apply in each sector starting from the exits of hysteresis regulators (rotor flux and torque) and the position of the rotor flux vector. the e vectors v0 and v7 are alternatively selected so as to minimize the number of commutations in the arms of the rectifier/inverter [8]. table i switching table with zero voltage vectors cf ct z1 z2 z3 z4 z5 z6 1 1 v2 v3 v4 v5 v6 v1 0 v7 v0 v7 v0 v7 v0 -1 v6 v1 v2 v3 v4 v5 0 1 v3 v4 v5 v6 v1 v2 0 v0 v7 v0 v7 v0 v7 -1 v5 v6 v1 v2 v3 v4 iv. dtc system structure the bloc diagram of dtc applied to dfig is shown in figure. 2 using switching table proposed by takahashi. figure. 2 the diagram of the dfig direct torque control system. v5(001) v6(101) 1 2 3 4 5 6 v0(000) v7(111) v1(100) v2(110) v3(010) v4(011) β α ��� ��� ��� ��� + 3 5 2 4 1 ��� ��� ��� z ct cf n �� grid dfig ∅�_��� ∅� ��_��� ��_��� ��� ��� ∅�� ∅�� concordia transformation estimation of flux estimation of torque switchingt able 1 0 -1 1 0 6 + a.ben amar et al. ijeca-issn: 2543-3717. june 2017 page 13 v. simulation simulation of the proposed direct torque control strategy for dfig based wind generation system is carriedoutusing matlab/simulink. the parameters of dfig are given in appendix. figure.3 electromagnetic torque for 2 step change in reference torque. figure.4 rotor flux. figure.5 evolution of rotor flux estimated components figure.6 stator current of dfig. figure.7 rotor current of dfig. the torque and flux references used in the simulation results are (-5000 n.m in 0s, -500 n.min 1s, and again 5000 n.m in 1.5s) and 1.1wb respectively..the curves are electromagnetic torque, rotor flux, stator current, and rotor currents. figure 3 show that the electromagnetic torque of dfig is follows the reference value quickly. figure 4 is showing the rotor flux magnitude response of dtc control strategy. note that the rotor flux is maintained constant (1.1wb) while torque changes, it certify that the decoupled control of rotor flux and torque is achieved. figure 6 show the trajectory of the estimated rotor flux components, the dtc has good dynamic response. figure 6 and figure 7 shows the corresponding stator and rotor currents waveform which are almost sinusoidal with some harmonic in the beginning. vi. conclusion this paper presents a direct torque control strategy for dfig based wind energy conversion systems. simulation results show that the dtc strategy presents a fast and good dynamic torque in steady state behaviour. however this strategy because of the variable switching frequency presents the drawback to having a high frequency of switching which present a high harmonic distortion of currents, high ripples of electromagnetic torque, and warming-up of the silicon switchers. vii. appendix table ii parameters of doubly fed induction generator rated power pn 1.5 mw stator voltage vs 398/690 v stator frequency f 50 hz stator resistance rs 0.012 ω rotor resistance rr 0.021 ω stator leackage inductance ls 0.0137 h rotor leakage inductance lr 0.0136 h mutual inductance m 0.0135 h pairs of poles number p 2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -6000 -4000 -2000 0 2000 time (s) e l e c t r o m a g n e t i c t o r q u e ( n m ) teref te mes 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 0.6 0.7 0.8 0.9 1 1.1 time (s) r o t o r f lu x m a g n it u d e ( w b ) fluxref fluxmes -1.5 -1 -0.5 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 fluxalpha (wb) f lu x b e t a ( w b ) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -6000 -4000 -2000 0 2000 4000 6000 time (a) is ( a b c ) ( a ) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -6000 -4000 -2000 0 2000 4000 6000 t ime (s) i r ( a b c ) ( a ) 1.185 1.19 1.195 1.2 1.205 1.21 1.215 -1500 -1000 -500 0 500 1000 1500 t ime (a) is ( a b c ) (a ) a.ben amar et al. ijeca-issn: 2543-3717. june 2017 page 14 references [1] b. b. pimple, v. y. vekhande and b. g. fernandes, new direct torque control of dfig under balanced and unbalanced grid voltage", ieee trondheim power tech, 2010, pp. 2154-2158. [2] l. xu, senior member, ieee, and p. cartwright, "direct active and reactive power control of dfig for wind energy generation", ieee trans. industrial electronics, vol. 21, no. 3, sep. 2006, pp. 750-758. [3] y. djeriri, a. meroufel and a. massoum, "artificial neural network based direct torque control of doubly fed induction, journal of electrical engineering, jee, romania, issn 1582-4594, vol.14, no.2, june 2014, pp. 71-79. [4] s. belkacem, f. naceri1, r. abdessemed, "reduction of torque ripple in dtc for induction motor using input– output feedback linearization, serbian journal of electrical engineering, vol. 8, no. 2, may. 2011, pp. 11097. [5] l r. zaimeddine and t. undeland, "control of a gridconnected double-fedinduction generator wind turbine", ieee trondheim power tech, 2011, pp. 1-7. [6] a. meroufel, y. djeriri, a. massoum et a. hammoumi commande vectorielle par les réseaux de neurones artificiels de l’énergie d’une mada intégrée à un système éolien", revue des energies renouvelables, vol. 13 n°. 4, déc 2010, pp. 669 – 682. [7] y. sreenivasarao, a. jayalaxmi, direct torque control of doubly fed induction generator based wind turbine under voltage dips, international journal of advances in engineering and technology, ijaet, vol. 3, no. 2, may. 2012, pp. 711-720. [8] s. tamalouzt, t. rekioua, r. abdessemed, direct torque and reactive power control of grid connected doubly fed induction generator for variable wind speed turbine", 5thconference cee'14 proceeding, batna, 2014, pp.16-17. 𝑉 𝑑𝑠 = 𝑅 𝑠 𝐼 𝑑𝑠 + 𝑑 𝜑 𝑑𝑠 𝑑𝑡 − 𝜔 𝑠 𝜑 𝑞𝑠 𝑉 𝑞𝑠 = 𝑅 𝑠 𝐼 𝑞𝑠 + 𝑑 𝜑 𝑞𝑠 𝑑𝑡 + 𝜔 𝑠 𝜑 𝑑𝑠 𝑉 𝑑𝑟 = 𝑅 𝑟 𝐼 𝑑𝑟 + 𝑑 𝜑 𝑑𝑟 𝑑𝑡 − 𝜔 𝑟 𝜑 𝑞𝑟 𝑉 𝑞𝑟 = 𝑅 𝑟 𝐼 𝑞𝑟 + 𝑑 𝜑 𝑞𝑟 𝑑𝑡 + 𝜔 𝑟 𝜑 𝑑𝑟 (1) table i table ii references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 24-28 ijeca-issn: 2543-3717. june 2017 page 24 investigation of plc for logic selectivity communication in protection systems s. boughazala mohamed 1 , a. cheriet 1 and d. ben attous 2 1electrical engineering laboratory (lgeb), university of biskra. algeria 2faculty of technology, department of electrical engineering, university of el-oued. algeria bougsalah@yahoo.com abstract – this paper reports an investigation of power line communication technique plc for logic selectivity in protection systems. a simulation of power grid with two protection systems using plc as communication process is performed by simulink/matlab program. also, the attenuation characteristic of high frequency plc signal is studied regards to resistance, inductance and frequency variation. keywords: power line communication plc, logic selectivity, protection, coupler, attenuation. received: 25/04/2017 – accepted: 03/06/2017 nomenclature plc: power line communication. i. introduction selectivity between protection elements consists to isolate as quickly as possible only the defect parts and leaving under electrical power all healthy parts [1]. by the way, both service continuity of power supply and assistance function between different protection elements are ensured. when a fault occurs in a radial network, the fault current is located between the source and the fault point. protections upstream of the fault are solicited [1]. downstream protections of the defect are not solicited. subsequently, only the first protection upstream of the fault must act [2, 3]. each circuit breaker is associated with protection able of sending and receiving a logic data as is shown in fig. 1. in the fact, the logic selectivity has been developed with the aim of overcoming disadvantages of both current and timed selectivity [4]. it makes possible to obtain a perfect selectivity and reduce considerably the delay in tripping the circuit-breakers closest to the source [3, 4]. power line communications plc is a technology that makes possible the transmission of voice [5], video and data over standard power lines [6, 7]. this will include the wiring systems of homes and offices. plc system does not require civil engineering works or modification of the current power distribution lines which covering approximating all population [8]. this makes plc a highly competitive option in term of costs and services in comparison with the current broadband solutions available. figure 1. protection system using logic selectivity ijeca-issn: 2543-3717. june 2017 page 25 plc uses power distribution lines for the transmission of data. the electric current reaches users in the form of low frequency alternating current of 50hz [8]. plc uses high-frequency carriers for data transportation. the band used covers a range between 1mhz and 34mhz [8]. in general, the plc uses ofdm coding for data transmission [1]. this modulation is the safest against interferences taking place in power networks and provides the highest level of spectral performance and efficiency. the principle of plc is to superimpose the electrical signal of 50hz another signal at higher frequencies and low energy [6-9]. this second signal propagates on the electrical grid and can be received and decoded by plc receiver which is on the same grid [9, 10]. in this paper the plc technique is investigated to ensure communication between circuit-breakers. the high frequency signal is modulated by using am modulation. two circuit-breakers protection system is used to show the applicability of the plc as communication way in power system protection [1-3]. ii. topological design of the system a three phase line and two protection systems simulation is carried out with simulink/matlab program. the simulink model is shown in fig.2. each protection is associated to circuit-breaker and logic relay which receiving fault information from its current transformer ct and emitting tripping and logic wait signals. figure 2. simulink model of three phase network with two level protection system using logic selectivity controlled with plc signals. the transmitter and receiver couplers are presented in figure 3 and figure 4 respectively. figure 3. transmitter coupler of plc signals, ct=1.013µf, lt=10 -5h, f=50khz. figure 4. receiver coupler of plc signals, lr=10 -4 h, cr=1.0132x10 -6 µf, rr=15ω. iii. simulation results case 1grid without faults: the protection b is not affected; therefore the logic relay of protection b does not transmit a logic wait signal to the protection a. in this case, we have a normal network operation that the current flows from the source to the load. the simulation results of this case are shown is figure 5. case 2when a fault appears in point m (figure 2): when a fault appears in point m, a fault current through both protections a and b. therefore, protections a and b are informed of this fault. in this case, the relay of protection b sends two logic signals; a tripping signal to its circuit-breaker and a logic wait signal to protection a. the circuit-breaker b opens after its delay time tb before protection a begin active. knowing that protection a is locked by the wait logic signal. the simulation results of this case are shown is figure 6. (a). output voltage of circuit-breaker a, (b). current across circuit-breaker a, (c). output voltage of circuitbreaker b, (d). current across circuit-breaker b, (e). high frequency signal ut transmitted by means of the transmitter coupler using plc technique, (f). high frequency signal ur received by means of the receiver coupler using plc technique, (g). tripping signal of circuit-breaker a, (h). tripping signal of circuit-breaker m b re a ke r b t r a n s m it t e r h f z l2 r e c e iv e r z g z l1 z s v s b re a ke r a c o u p le u r c o u p le u r b re a ke r c o n tro l b re a ke r c o n tro l t im e r in 1 in 2 o u t1 in 1 o u t1 o u t2 g m 1 2 c1 2 c1 2 c1 2 c1 2 c1 2 c1 2 i + i + 1 s. boughazala mohamed et al. ijeca-issn: 2543-3717. june 2017 page 26 b, (k). logic wait signal transmitted from protection a to protection b via plc system. a b c d e f g k figure 5. simulation results of case 1. a b c d e f g h k figure 6. simulation results of case 2. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -300 -200 -100 0 100 200 300 t u1 na 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t i1a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -300 -200 -100 0 100 200 300 t u1 nb 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -5 -4 -3 -2 -1 0 1 2 3 4 5 t i1b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t ur 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u a l 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -300 -200 -100 0 100 200 300 t u1 na 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t i1a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -300 -200 -100 0 100 200 300 t u1 nb 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -20 0 20 40 60 80 100 t i1b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t ut 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t ur 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u a l s. boughazala mohamed et al. ijeca-issn: 2543-3717. june 2017 page 27 a b c d e f g h k figure 7. simulation results of case 3. case 3when a fault appears in point m and protection b is broken down: consider now that a fault appears in point m and protection b is broken down. as the previous case, the fault current through both protections a and b which are informed of this fault. hence, the relay of protection b sends two logic signals; a tripping signal to its circuitbreaker and a logic wait signal to protection a. because the protection b is broken down, its circuit-breaker does not open and for this reason the logic wait signal becomes longer. the circuit-breaker a opens after its delay time ta + tal (tal is the waiting time of protection a before its activation). the simulation results of this case are shown is fig. 7. iv. hf attenuation measurement the signal attenuation equation [6] is represented as the ratio of the received high frequency signal (ur) in protection a to the transmitted high frequency signal (ut) from protection b:        ut ur dbav log20)( (1) the attenuation characteristics of the signal versus cable resistance, cable inductance and frequency variation are presented in fig.8, fig.9 and fig.10, respectively. figure 8. hf signal attenuation versus line resistance variation. figure 9. hf signal attenuation versus line inductance variation. figure 10. hf signal attenuation versus frequency variation. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -250 -200 -150 -100 -50 0 50 100 150 200 250 t u1 na 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -100 -80 -60 -40 -20 0 20 40 60 80 100 t i1a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -300 -200 -100 0 100 200 300 t u 1n b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -100 -80 -60 -40 -20 0 20 40 60 80 100 t i1 b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t ut 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -10 -8 -6 -4 -2 0 2 4 6 8 10 t u r 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c a 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u c b 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -1 0 1 2 t u a l 0 1 2 3 4 5 6 -9 -8 -7 -6 -5 -4 -3 -2 av=f(r) 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 -140 -120 -100 -80 -60 -40 -20 0 av=f(l) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 x 10 6 -60 -50 -40 -30 -20 -10 0 av=f(f) s. boughazala mohamed et al. ijeca-issn: 2543-3717. june 2017 page 28 v. conclusion electrical networks deliver electrical energy required for different consumers. however, the continuity of supply of receivers is sought from the network design. the main functions of protection are brought into play in order to ensure continuity of service. the most used function is the protections of the max current against defects in short-circuit. this work is concerned with the use of the function. in the case of a protection system with has many levels, different protection are linked to each other with a logic selectivity with a polite cable and cpl. reference [1] f. sautriau, protection of electrical distribution networks the logic selectivity system, february 1983. [2] ali reza fereidouni, hamed nafisi, mehdi garmrudi, hamed hashemi dezaki, the effect of distributed generation in distribution network on coordination of protective devices, international review on modelling and simulations (i.re.mo.s.), vol. 4, n. 2011, pp. 17731780. [3] andré sastre, network protection (hta ) industrial and tertiary, ct 174 édition décembre 1994. [4] mohamad haffar, zeashan h khan, jean-marc thiriet, eric savary, an extension to iec 61850 for solving selectivity problem in electrical substations, author manuscript, published in "23rd iar workshop on advanced control and diagnosis, coventry : united kingdom (2008) [5] eklas hossain, sheroz khan, et ahad ali, modeling low voltage power line as a data communication channel, international conference on electrical engineering (icee 2008), wcset 2008: world congress on science, engineering and technology, paris, france, 2008, pp. 2123. [6] charles j. kim, and mohamed f. chouikha e. f. fuchs, attenuation characteristics of high rate homenetworking plc signals, ieee transactions on power delivery, vol. 17, 2002, pp. 945-950. [7] i. hakki cavdar, et engin karadeniz, measurements of impedance and attenuation at cenelec bands for power line communications systems, sensors 2008, vol 8, pp. 8027-8036, doi: 10.3390/s8128027. [8] t. tran-anh, p.aurio, t. tran-quoc ideal, distribution network modeling for power line communication applications, 0-7803-8844-5/05/$20.00c2005 ieee. [9] p. malathi et p.t.vanathi, power line communication using ofdm and oga, aiml journal, vol 7, issue (1), 2007. [10] yihe guo, zhiyuan xie, and yu wang, a model for 10kv overhead power line communication channe, huangshan , p. r.china, pp. 289-292. i. introduction iii. simulation results case 1grid without faults: case 2when a fault appears in point m (figure 2): case 3when a fault appears in point m and protection b is broken down: international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 12-18 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 12 analysis for inter turn stator fault with load variation in induction motor hakima cherif 1* , madiha maamir 1 , seif eddine chehaidia 2 1 lgeb laboratory, university of biskra, algeria 2 national polytechnic school of constantine, alegria *corresponding author e-mail:hakimacherif25@gmail.com abstract – this paper investigates the impact of load variation on the diagnosis of inter-turn stator faults in induction machines. the proposed detection technique relies on the analysis of stator current using the discrete wavelet transform (dwt) in both normal and faulty states of the machine. the energy of the approximation and detail signals obtained from dwt provides valuable information about the machine's health and the severity of the inter-turn stator faults. experimental tests were conducted using a dspace 1104 signal card-based interface to study the load effects in detecting and diagnosing stator inter-turn short circuit faults in induction motor. keywords: induction motor, fault detection, diagnosis, inter turns short circuit fault (itsc), discrete wavelet energy (dwe). received: 15/04/2023 – revised: 28/05/2023 – accepted: 15/06/2023 i. introduction induction motors play a crucial role in various industrial applications by converting electrical power into mechanical energy. these electromechanical devices are widely employed globally and are considered the workhorses of industrial operations. induction motors are known for their robustness, making them suitable for a wide range of applications, including hazardous environments and challenging operating conditions. induction motors can experience failures due to various environmental or internal factors. these faults often exhibit subtle symptoms but can lead to increased energy consumption, reduced efficiency, and diminished performance. even minor faults can result in losses and elevated temperatures, leading to insulation deterioration in the windings and potentially reducing bearing lifespan due to increased vibration levels. the history of fault diagnosis and protection for electrical machines dates back to the early stages of their development. initially, manufacturers and users relied on basic protections such as overcurrent, overvoltage, and earth-fault protection to ensure safe and reliable operation. however, as the tasks performed by these machines became more complex, there was a need for improvements in fault diagnosis techniques. nowadays, diagnosing faults when they occur has become crucial, as unscheduled downtime of machines can disrupt deadlines and result in significant financial losses [1]. hence, it is imperative to diagnose the health of induction motors to minimize maintenance costs. published surveys have indicated that induction motor failures encompass various types of faults. the most common failures include bearing-related faults, accounting for 40% of failures, followed by short circuits in stator windings at 38%. rotor faults constitute approximately 10% of failures, while other types of faults, such as end ring faults, make up the remaining 12% [2]. research indicates that stator winding faults are the second most common type of failures in induction machines, following bearing faults. however, detecting https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 13 bearing faults is comparatively easier through physical examination. in small motors, abnormal noise produced by the machine can be a telltale sign of bearing faults, while large motors are equipped with temperature sensors for online monitoring, where a rise in temperature indicates a fault. stator faults typically originate as minor inter-turn short circuits (itsc) within a coil. these short circuits arise due to hotspots forming in the winding. itsc can progress into more severe faults, such as phase-to-earth or phase-to-phase short circuits. the high current resulting from these short circuits further elevates the winding temperature, leading to insulation deterioration and eventual failure. detecting and diagnosing itsc faults at an early stage is crucial in preventing significant damage to the stator core. by identifying inter-turn short circuits before insulation failure occurs, the motor can be rewound, averting a complete machine failure. typically, the rewinding process is faster and more cost-effective than replacing the entire motor [3,4] . several offline and online techniques are available for the detection and diagnosis of stator winding faults. in this context, non-intrusive methods that rely solely on voltage and current measurements from motor terminals, without requiring additional sensors, are generally preferred [5]. one such non-invasive method is motor current signature analysis (mcsa), which has demonstrated its efficiency in identifying stator winding faults [6]. recently, various stator winding fault detection techniques have been extensively discussed in the literature, including analysis of axial flux [7], vibration monitoring, extended park's vector approach (epva) [5], detection of negative sequence current [8], negative sequence impedance [9], residual saturation harmonics [10], and multiple reference frame theory [11]. to extract fault-related information from stator current signals, signal processing tools such as fast fourier transform (fft), short-time fourier transform (stft), wavelet transform (wt) [4,16], and power spectral density (psd) estimation have been introduced [12-17]. this paper explores the utilization of energy derived from the analysis of stator current using discrete wavelet transform (dwt) to diagnose inter-turn short circuit faults in induction motors under varying load conditions. by harnessing the multi-resolution analysis capabilities of dwt, the proposed approach enhances fault diagnosis accuracy and reliability. the study validates the effectiveness through experimental investigations, offering valuable insights for real-world implementation. this research contributes to improved motor diagnostics, leading to enhanced reliability and operational efficiency. ii. materials and methods ii.1. experimental setup experimental data were obtained from a squirrel-cage induction motor with the following specifications: threephase, 50 hz frequency, y connection, 4 poles, 46 bars, and a power rating of 1.1 kw. the motor was directly supplied by the network with a voltage of 400v (un). it was specially rewound to allow for the external manipulation of the number of turns in each phase winding, enabling easy creation of inter-turn short circuit (itsc) faults. stator current data was recorded using current sensors connected to the interface of a dspace card 1104, and the data was stored on a pc (figure 1). the data acquisition process utilized a sampling frequency of 10 kilo samples per second for all experimental tests conducted. figure 1. workbench used in tests to modify the stator of the motor, an alteration was made by incorporating five additional connections that were linked to the stator coils of the three phases. this modification can be observed in the schematic winding diagram provided in figure 2. hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 14 the opposite ends of these external wires were connected to a motor terminal box, which facilitated the introduction of inter-turn short circuits (itsc) with varying numbers of turns across different phases, as depicted in figure 2. the duration of the fault was controlled through the utilization of a specialized circuit, comprising a relay contactor that was controlled by an 'mega2560' arduino card, as illustrated in figure 3. this setup allowed for the application of the fault for a specified duration, typically a few seconds, to protect the machine from potential damage figure 2. tappings connected to the stator coils of the stator phase w1w2 figure 3. circuit to control the time of the itsc fault by ‘arduino card’ table 1. frequency bands for the wavelet signal level frequency bands (hz) d1 2500-5000 d2 1250-2500 d3 625-1250 d4 312.5-625 d5 156.25-312.5 d6 78.125-156.25 d7 39.0625-78.125 d8 19.531-39.0625 d9 9.765-19.531 this study focuses on detecting inter-turn short circuit (itsc) faults under various load conditions. the detection process is accomplished by calculating the energy of the detail coefficients derived from the discrete wavelet transform (dwt) of the stator current. the analysis considers different scenarios, including healthy operation and itsc faults occurring under different load conditions. detailed explanations of the methodology and findings related to this detection approach will be provided in the upcoming sections. ii.2. algorithm for fault detection figure 5 illustrates the sequential steps required to implement the discrete wavelet energy (dwe) based methodology for diagnosing inter-turn short circuit (itsc) faults. hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 15 figure 5. flowchart for the dwe-based diagnosis methodology the proposed methodology utilizes the application of the discrete wavelet transform (dwt) to the stator current signal under healthy and inter-turn short circuit (itsc) fault conditions with varying loads. by employing this method, the sideband harmonics generated during the fault can be extracted, and the energy of the detail coefficient is calculated. this approach enables the diagnosis of the fault by comparing the values of the detail coefficient energy between the healthy and itsc fault states under different load conditions. the discrete wavelet energy (dwe) serves as a reliable indicator for detecting and diagnosing itsc faults, while also considering the effects of varying loads on the fault diagnosis process. iii. expremental result iii.1. validation to validate the proposed method, a series of tests were conducted using a specialized of 4-pole 1.1 kw industrial induction motor that was rewound for the purpose. this motor was equipped with an external connection box (refer to figure 2 and figure 3) which allowed for the external creation of an itsc fault. to vary the load, the motor was coupled with a powder brake. the experiments were carried out at a supply frequency of 50 hz. figure 6 and figure 7 depict the stator current of the aphase while the induction machine operates in both healthy and itsc fault conditions at various loads. the motor was initially started with no load after charging, and then the itsc fault was applied with a load for a duration of 2 seconds using the time control circuit (refer to figure 3). this allowed us to observe the impact of the fault under different load conditions. the short duration of the itsc fault enabled multiple uses of the machine in the tests. this section presents the current behavior of the a-phase in both healthy and itsc states (with 2% and 5% turns shorted) under different load levels (25%, 50%, 75%, and full load). it is worth noting that:  healthy stat as the load increases, there is an observed increase in the a-phase current in different states.  itsc fault stats the stator current of the a-phase shows a significant increase, particularly in the 5% itsc fault state, where the current value surpasses the nominal value of the motor, especially under a load of 75%. in the case of the 2% itsc fault, the current increase is comparatively lower since the number of turns shorted is negligible in comparison to the total turns of the winding. iii.2. analyses the results by dwe the evaluation of the forecasted causes of the defect cannot be directly assessed in the temporal space. however, by analyzing the stator current using discrete wavelet transform (dwt), the energy obtained from different harmonic components can provide valuable information about the effect of load on the fault. the impact of load variation on the "short circuit" defect becomes evident through the energy stored at certain levels. energy analyzing the results, it is observed that the energy stored in level d7, corresponding to the frequency band [78.125-39.0625hz], depends on the degree of the fault and the load. the energy increases with higher loads and an increased percentage of inter-turn short circuit. fig 8 illustrates the results of the energy variation, represented by the discrete wavelet detail coefficient in level 7 (ed7) of the stator current (a-phase), for the motor in healthy and itsc fault states (2% and 5%) with different load conditions. ed7 serves as a clear indicator of the effect of both load and itsc fault, particularly when the number of turns shorted is small (2%). therefore, studying the behavior of ed7 values allows for the diagnosis of the induction motor in itsc fault under different load conditions. hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 16 figure 6. stator current of the a-phase in different cases: healthy and itsc 2% under different load (no load, 25%, 50%, 75%, full load) figure 7. stator current of the a-phase in different cases: healthy and itsc 5% under different load (no load, 25%, 50%, 75%, full load). 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (a ) healthy no load itsc 2% 25% load healthy 25% load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (s ) healthy no load healthy 25% load itsc 5% 25% load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia ( a ) healthy no load healthy 50% load itsc 2% 50% load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (a ) healthy 50% load itsc 5% 50% loadhealthy no load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (s ) itsc 2% 75% load healthy 75% load healthy no load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (a ) itsc 5% 75% load healthy 50% load healthy no load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia (s ) healthy no load healthy 100% load itsc 2% 100% load 0 1 2 3 4 5 6 7 8 9 10 -5 0 5 t(s) ia ( a ) healthy no load itsc 5% 100% load healthy 100% load hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 17 fig.8.the energy variation in frequency bands for different cases (a): healthy with deferent load (no load , 25%,50% ,75% and full load) (b): itsc fault 2% with deferent load (no load , 25%,50% ,75% and full load) (c): itsc fault 5% with deferent load (no load , 25%,50% ,75% and full load) fig. 9 illustrates the relationship between the energy stored at level 7 (ed7) and the different loads applied on motor. it can be observed that the energy ed7 rises with an increase in load for the normal operating condition (healthy) of the machine. however, the energy increase is more pronounced in the faulty cases (itsc) of the motor figure 9. comparison of energy variation for three cases (health and faulty state: 2% and 5% itsc) at different load: no load, 25%, 50%, 75% and full load respectively. iv. conclusions an essential aspect to consider during the detection of faults is the behavior of primary faults in a motor operating under various loads. detecting faults becomes difficult due to large variations in load .the amplitude and frequency of the spectral components associated with the faults also change with loads. thus, evaluating the amplitudes of the fault components requires a load calculation. next, it can be seen that motor faults, specifically itsc faults are depend on the torque applied to the motor. this study investigates the impact of load on the detection and diagnosis of stator inter-turn short circuits fault. the diagnostic approach employed in this research focuses on analyzing the energy of the stator current using discrete wavelet transform (dwt). the proposed wavelet-based energy technique successfully captures valuable characteristics from the stator current, particularly in non-stationary conditions, within an induction motor. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. hakima cherif et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 12-17 page 18 references [1] j. cusido, et al., "wavelet and pdd as fault detection techniques," electric power systems research, vol. 80, no. 8, 2010, pp. 915-924. [2] y. amara and g. barakat, "modeling and diagnostic of stator faults in induction machines using permeance network method," in progress in electromagnetics research symposium, 2011. [3] a. jacob, v. jose, and d. sebastian, "stator fault detection in induction motor under unbalanced supply voltage," in emerging research areas: magnetics, machines and drives (aicera/icmmd), 2014 annual international conference on, 2014. ieee. [4] h. cherif, a. benakcha, i. laib, s. e. chehaidia, a. menacer, b. soudan, and a. g. olabi, "early detection and localization of stator inter-turn faults based on discrete wavelet energy ratio and neural networks in induction motor," energy, vol. 212, 2020, p. 118684. [5] s. grubic, et al., "a survey on testing and monitoring methods for stator insulation systems of low-voltage induction machines focusing on turn insulation problems," ieee transactions on industrial electronics, vol. 55, no. 12, 2008, pp. 4127-4136. [6] j.-h. jung, j.-j. lee, and b.-h. kwon, "online diagnosis of induction motors using mcsa," ieee transactions on industrial electronics, vol. 53, no. 6, 2006, pp. 1842-1852. [7] j. penman, et al., "detection and location of interturn short circuits in the stator windings of operating motors," ieee transactions on energy conversion, vol. 9, no. 4, 1994, pp. 652-658. [8] m. arkan, d. perović, and p. unsworth, "online stator fault diagnosis in induction motors," iee proceedings-electric power applications, vol. 148, no. 6, 2001, pp. 537-547. [9] s. cheng, p. zhang, and t. g. habetler, "an impedance identification approach to sensitive detection and location of stator turn-to-turn faults in a closed-loop multiple-motor drive," ieee transactions on industrial electronics, vol. 58, no. 5, 2011, pp. 1545-1554. [10] s. nandi, "detection of stator faults in induction machines using residual saturation harmonics," ieee transactions on industry applications, vol. 42, no. 5, 2006, pp. 1201-1208. [11] s. m. cruz and a. m. cardoso, "multiple reference frames theory: a new method for the diagnosis of stator faults in three-phase induction motors," ieee transactions on energy conversion, vol. 20, no. 3, 2005, pp. 611-619. [12] j. cusido, et al., "fault detection in induction machines using power spectral density in wavelet decomposition," ieee transactions on industrial electronics, vol. 55, no. 2, 2008, pp. 633-643. [13] a. mohanty and c. kar, "fault detection in a multistage gearbox by demodulation of motor current waveform," ieee transactions on industrial electronics, vol. 53, no. 4, 2006, pp. 1285-1297. [14] s.h. kia, h. henao, and g.-a. capolino, "diagnosis of broken-bar fault in induction machines using discrete wavelet transform without slip estimation," ieee transactions on industry applications, vol. 45, no. 4, 2009, pp. 1395-1404. [15] h. cherif, et al., "stator inter turns fault detection using discrete wavelet transform," in diagnostics for electrical machines, power electronics and drives (sdemped), 2015 ieee 10th international symposium on, 2015. ieee. [16] a. khechekhouche, h. cherif, a. benakcha, a. menacer, s. e. chehaidia, and h. panchal, "experimental diagnosis of inter-turns stator fault and unbalanced voltage supply in induction motor using mcsa and dwer," periodicals of engineering and natural sciences, vol. 8, no. 3, 2020, pp. 1202-1216. [17] a. allal, a.khechekhouche, diagnosis of induction motor faults using the motor current normalized residual harmonic analysis method. international journal of electrical power and energy systems. 2022, vol. 141, 108219. https://doi.org/10.1016/j.ijepes.2022.108219 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 19-25 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 19 structural analysis of wind blades with and without power control b. kouadria 1* , m. debbache 2 1 university of algiers 1, benyoucef benkhedda, algiers, algeria 2 centre de développement des energies renouvelables, bp. 62 route de l'observatoire bouzareah 16340, algeria * corresponding author: email: b.kouadria@yahoo.com abstract –the blade is the principal element in the wind rotor mechanism. the efficiency of the wind turbine depends on the optimal geometry of this element, as well as its structural configuration. this work presents a contribution to wind blade structural design. the blade structure was evaluated without the control power operating case and with the power control case. in this case, an 80kw horizontal axis wind turbine design was proposed. the process begins with design and aerodynamic analysis based on blade element momentum theory by using qblade software to determine the blade geometry. the blade structure was defined by the numad package, it is composed of two parts. the shell part is four layers of composite materials and the rib part has a sandwich panel shape. the evolution of structure was done by the co-blade package. the results show a decreasing in displacement decreased to 64% at the tip of the blades which leads to the stress at the leading and trailing edge being negligible. that proves the importance of a control power system in the protection of the blade structure and turbine generator in the operating case under high wind velocity and ensures the stability of the power output value. keywords: blade, wind rotor, aerodynamic, structure, composite material. received: 03/11/2022 – revised: 20/12/2022 – accepted: 25/12/2022 i. introduction electricity is an irreplaceable and indispensable source of human comfort in modern life. the global demand for this energy is increasing year by year, but due to the recent methods of energy conversion used to have a significant pollution problem. which presents a huge challenge and promotes scientific research to improve and optimize current conversion techniques to decrease the amount of pollution, or to find an alternative source of energy. as a new trend, renewable energy sources (solar, wind, geothermal, etc.) present a serious solution. these depend on the availability of these resources and how these renewable energies are converted into electricity. currently, wind energy has an attractive and growing interest in this field. in which the wind kinetic energy is converted to mechanical energy to finally converted to electrical energy. this conversion uses a wind rotor, which takes the form of a turbine and consists of blades. the structure of wind turbine blades is a crucial aspect of their design and performance. researchers aim to improve the efficiency and durability of blades by optimizing their shape, size, material properties, and aerodynamics. this research helps to make wind energy more cost-effective and reliable, which is important for its growth as a sustainable source of energy [1, 5]. the effectiveness of this solution depends on the development of wind turbine construction technology and its performance, including the design of the performance of wind blades. to define the optimal blade shape and structure, several works have been done. g.p. a study of reducing blade mass. it combined two phases. the first is the bend-twisting coupling method. it aims to reduce the loads in the operational state. in this case, the plies of composite material over the caps of the spar beam are rotated. the second phase is the flap-edge coupling method. it aims to reduce the vibration due to b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 stall induction at parked operation state by caps displacement in the opposite direction. the evaluation of material reducing amount has been done by the structural simulation to define the optimal blade mass with acceptable loads resistance. the results show an 8.3% of mass reduction with 5.8% of plies rotation and 3% of caps displacement in opposite direction [6]. tried to optimize the blade of a 50mw wind turbine to reduce the total cost. an aero-structural optimization method has been used based on monte carlo simulation. it focused on the spar caps of the blade root region. the method proposed the airfoil thickener and thinner of 10%. in addition, the cord took greater and smaller by 10% compared to the initial design. the results show an up to 25% weight loss and a 30% cost reduction. study proposed a new design for the wind blade [7].. this design consists of two parts based on the variation of aerodynamic and structural parameters from the root to the tip case and the opposite case. the blade body is a combination of three blades. this new design is proposed and applied for nrel 5mw to obtain optimal structural compliance. where the deflection is less than 5m and the strain is less than 0.5%. the structural simulation shows that the new design has a 7.2% low mass compared to the original blade. another hand, 3.31m of maximum deflection was registered and 0.39% of the stain [8]. one method focused on reducing blade mass by using topology optimization. this method is applied for determining the optimal internal structural compliance. based on their results, the finite element model was created to study the influence of distinguishing characteristic parameters on blade performance. the results of the application of a 1.5mw wind turbine show that the method defines a new blade structure with a 3% lower mass compared to the initial blade. (bemt) and computational fluid dynamics (cfd) simulations. the bemt is a simple and efficient method to analyze the aerodynamic performance of wind turbines, but it has limitations in predicting the performance under complex flow conditions [9]. cfd simulations can provide a more accurate prediction of the aerodynamic performance, but they are computationally expensive and time-consuming. in addition, the structural performance of wind turbines is determined by the design of the blade and its material properties. factors such as blade weight, stiffness, and natural frequency play an important role in determining the structural performance. therefore, an optimal design of wind turbine blades requires a trade-off between aerodynamic and structural performance. effective modeling and simulation tools can help to optimize the design of wind turbine blades, improve their performance, and reduce costs [10, 11]. this work presents a contribution to blade structural design. in which the blade structure efficiency was evaluated for two cases. the first is the wind turbine operates without a power system and the second is with a power control system. ii. material and method ii.1. aerodynamic analysis the performance of wind turbines depends on the blade's aerodynamic and structural performance. the aerodynamic performance is related to several parameters such as the geometry parameter like a chord, twist angle, speed ratio, and section profile. the environmental parameters as mean wind speed and topology of the site. the analyses of the aerodynamic performance of wind turbines are based on blade element momentum theory. where the thrust force and the torque created by the aerodynamic wind effect are presented by: figure 1. flow effect on blade section [5]. where cl and cd are the lift and drag coefficients respectively., r is the radial position, and b is the blade number. ρ is the air density. c is the chord length, φ is the flow angle (fig.1) and w is relative velocity, the chord, the flow angle, and the relative velocity are defined respectively by [10, 11]: b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 v1 is the wind speed, ω is rotor rotation speed, r is element position and a and a’ are the axial and radial induction factors defined respectively by [10, 11]: σ presents section solidity defined by [5, 6]: cn et ct is the coefficient of normal and tangential force respectively, they are determined as follows [10, 11]: the total efficiency is determined by [5, 6]: λr is the local speed ratio, it equals [5, 6]: ii.2. design and methodology of analysis to reach the goals, an 80kw wind turbine has been proposed to be installed in the adrar region, where the mean wind speed is 6.8m/s [7]. the rotor is combined by three 8.5m blades designed for the value of tip speed ratio equal to 6 with profile section type naca 4415. which have an attack angle of 4.75deg for high drag to lift at 1e6 of reynolds number [8]. the section is a profile distribution with the variation of the chord and the twist angle as shown in table 1. table 2 presents the blade structure contains a shell and two internal ribs. it shows also the internal rib has the shape of a sandwich panel.it is located inside the shell of the blade to ensure the junction between the upper and the lower shell skin, thus increasing the rigidity of the blade. the two ribs are attached at the 30% and 70% positions chord length in each section. the shell is proposed to be made of four composite layers, and the ribs are sandwich panel structure with three layers, each layer mechanical properties presented in table 3. table1. chord and twist distribution. table 2. positioning of the ribs. table 3. mechanical properties to evaluate the proposed design, an investigation method has been proposed, where the aerodynamic analysis is done by using qblade software. qblade is a software tool for the aerodynamic design and analysis of wind turbine blades. it is commonly used for simulation and optimization of wind turbine blades to help improve the efficiency and performance of wind turbines. the software calculates and predicts the loads, performance, and operating behavior of wind turbine blades under various conditions. it provides valuable information for the aerodynamic design of wind turbine blades, allowing engineers to make informed decisions regarding blade geometry, airfoil selection, and other important design parameters [12, 13]. ii.3. modeling procedure in this work, a procedure based on the design and optimisation of the architecture of the neural network is advanced as described in figure 2. b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 figure 2. material configuration. the blade structure shown in figure 3 is designed by the numad package. the structural analysis is done by using the co-blade package [14-17]. figure 3. blade structure (numad). iii. results and analysis the aerodynamic analysis using the qblade software resulted in the load distribution. figure 4 shows the variation of the tangential force, while figure 5 shows the variation of the normal force. the impact of this load system on the proposed blade structure was evaluated by studying the variations in stress distribution of forces and torques in both the control and non-control cases. figure 4.variation of the tangential force (ft). figure 5. variation of normal force (fn). in the general case, if a wind turbine operates without a control system, the increase in wind speed leads to an increase in power collected by the wind rotor and its torque. however, the generator has a limited torque capacity, so it cannot handle increases in torque beyond its nominal torque. this leads to high pressure on the blades, causing them to experience cyclic and variable loads. a wind speed of 15m/s is considered a critical case for blade structural evaluation. figure 6 shows the distribution of forces (in kn) in the controlled case as a function of the length z (in m). it displays also the distribution of the resultant moment (in kn-m) as a function of the length z (in m). the figure deals with the distribution of the force and the resultant of the moment in the two cases (controlled and uncontrolled). in the uncontrolled case, the blades rotate with a maximum centrifugal force of 21kn at the root level of the blades and decrease towards the blade tip. the normal force is 3kn and the tangential force is 1kn. there is a normal torque of -7 kn.m and a tangential torque of 16 kn.m. in the control case, the centrifugal force, vz, vy, and my are the same as the uncontrolled case but the normal torque is -4kn.m instead of -7kn.m. uncontrolled case b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 controlled case figure 6. distribution of forces and resultant moment figure 7 shows the displacements and rotation of the section as a function of the length z (m) in the two cases (controlled and uncontrolled). in the uncontrolled case, the variations of the loads put the blades under constraints causing displacements of the blade sections, with the maximum at the tips of the blades with a maximum value of 0.05m in both normal and tangential directions. the constraints also result in small rotations of the blade sections with a maximum value of 0.07 degrees at the end of the blades. in the controlled case, the decrease in normal torque leads to a decrease in normal displacement, with a maximum value of 0.018m at the end of the blade. the reduction in displacement directly affects the constraints. uncontrolled case controlled case figure 7. displacements and rotation of section figure 8 displays the distribution of shear stress (in the uncontrolled case and in controlled case) in a screw view along the length z (in m). in the uncontrolled case, the cyclical movements create normal and transverse stresses in the layers of material. the maximum shear stress is at the root level with a value of 0.65mp, and the minimum shear stress is at the leading and trailing edges with a value of 0.2mp. in the controlled case, the maximum shear stress at the blade roots remains the same as the uncontrolled case, but there is no stress at the leading and trailing edges. uncontrolled case. controlled case figure 8. shear stress distribution b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 figure 9 depicts the failure criteria with respect to the length z (in m). the results of evaluating the failure criteria suggest that the blade structure configuration is secure and meets the necessary safety standards. figure 9. failure criteria. iv. conclusion the focus of this work is to contribute to the development of a composite material wind turbine blade. a horizontal axis wind turbine model capable of producing 80kw was studied, with a blade length of 8.5m and a naca4415 profile. a structural performance study was conducted to validate the blade structure, considering material and thickness. the blade is estimated to be made of composite material with two different configurations: one for the blade shell with four composite plies of different angles (0°/90°/0°/90°), and the second for the internal rib with three composite plies of angular configuration (0°/90°/0°). the structural behavior of the wind turbine was studied under a wind speed of 15m/s for two cases: one without power control and the other with power control. the results of the structural evaluation show that in the case of no power control, the blades experience high fluctuation in loads, which affects the blade structure layers. however, when using the power control system, the loads decrease, leading to a decrease in displacement to 64% at the tip of the blade. this reduction in displacement results in a decrease in section deviation and negligible stress at the leading and trailing edges, ensuring a long working life for the blade and generator, and providing increased output power. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] w. wang, j. yang, j. dai, a.chen, eemd-based videogrammetry and vibration analysis method for rotating wind power blades, measurement, vol 207, 2023, pp. 112423, https://doi.org/10.1016/j.measurement.2022.112423. [2] s. jayswal, a. bhattu, structural and modal analysis of small wind turbine blade using three different materials, materials today: proceedings, vol. 72, part 3, 2023, pp. 1347-1352, https://doi.org/10.1016/j.matpr.2022.09.329 [3] m. khazaee, p. derian, a. mouraud, a comprehensive study on structural health monitoring (shm) of wind turbine blades by instrumenting tower using machine learning methods, renewable energy, vol. 199, 2022, pp.1568-1579, https://doi.org/10.1016/j.renene.2022.09.032 [4] h.a. porto, c.a. fortulan, a.j.v. porto, power performance of starting-improved and multi-bladed horizontal-axis small wind turbines, sustainable energy technologies and assessments, vol. 53, part a, 2022, pp. 102341, https://doi.org/10.1016/j.seta.2022.102341 [5] z. chuang, c. li, shewen liu, x. li, z. li, l. zhou, numerical analysis of blade icing influence on the dynamic response of an integrated offshore wind turbine, ocean engineering, vol. 257, 2022, pp. 111593, https://doi.org/10.1016/j.oceaneng.2022.111593 [6] g. p. serafeim, d. i. manolas, v. a. riziotis, p. k. chaviaropoulos, d. a. saravanos,” optimized blade mass reduction of a 10mwscale wind turbine via combined application of passive control techniques based on flapedge and bend-twist coupling effects”, journal of wind engineering and industrial aerodynamics, vol 225,2022, https://doi.org/10.1016/j.jweia.2022.105002. [7] s., yao, m. chetan, d. t. griffith, e. mendoza, a. s., m. s. selig, d. martin, s. kianbakht, k. johnson, e. loth, “aero-structural design and optimization of 50 mw wind turbine with over 250-m blades”, wind engineering, vol 46, 2022, pp. 273–295. https://doi.org/10.1177/0309524x211027355. [8] ranjeet a. & robert a. chin (2022) structural design and analysis of a redesigned wind turbine blade, international journal of ambient energy, 43:1, 1895-1901, doi: 10.1080/01430750.2020.1723688. [9] jie zhu, xin cai, dongfang ma, jialiang zhang, xiaohui ni, improved structural design of wind turbine blade based https://doi.org/10.1016/j.measurement.2022.112423 https://doi.org/10.1016/j.jweia.2022.105002 https://doi.org/10.1177/0309524x211027355 b. kouadria et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 19-25 page 20 on topology and size optimization, international journal of low-carbon technologies, vol.17, 2022, pp. 69–79, https://doi.org/10.1093/ijlct/ctab087. [10] debbache m, hazmoune m, derfouf s, ciupageanu d-a, lazaroiu g. wind blade twist correction for enhanced annual energy production of wind turbines. sustainability. 2021, vol. 13, n°.12, pp. :6931. https://doi.org/10.3390/su1312693. [11] t. burton, n. jenkins, d. sharpe, ea bossanyi, wind energy handbook, 2ed, 2012. [12] h. daaou nedjari, s. kheder haddouche, a. balehouane, o. guerri, optimal windy sites in algeria: potential and perspectives, energy, volume 147, 2018, pp. 1240-1255, https://doi.org/10.1016/j.energy.2017.12.046. [13] m. alaskari, a. oday, m. h. majeed, analysis of wind turbine using qblade software, materials science and engineering, vol 518, 2019, pp. 032020, doi 10.1088/1757-899x/518/3/032020 [14] http://airfoiltools.com/airfoil/details?airfoil=naca4415-il (view 2022). [15] https://www.q-blade.org/ (view 2022). [16] https://numad.readthedocs.io/en/latest/ (view 2022). [17] https://code.google.com/archive/p/co-blade/ (view 2022). https://doi.org/10.1093/ijlct/ctab087 https://doi.org/10.3390/su1312693 http://airfoiltools.com/airfoil/details?airfoil=naca4415-il http://airfoiltools.com/airfoil/details?airfoil=naca4415-il https://www.q-blade.org/ https://numad.readthedocs.io/en/latest/ https://code.google.com/archive/p/co-blade/ international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 19-23 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 19 effect of rubber thickness on the performance of conventional solar stills under el oued city climate (algeria) imad kermerchou 1* , abderrahmane khechekhouche 2 , nabil elsharif 3 1 applied science faculty, university of ouargla, algeria 2 faculty of technology, university of el oued, algeria 3 mechanical engineering department, university of benghazi, libya *corresponding author e-mail:hakimacherif25@gmail.com abstract – our study focuses on examining the performance of conventional solar stills in an arid region, specifically investigating the impact of rubber material and its thickness on the distillation process. four solar stills were tested, including a reference solar still (ssr) and three modified solar stills (mss1, mss2, and mss3) with rubber thicknesses of 1 cm, 2 cm, and 3 cm, respectively. the experimental findings clearly demonstrate a notable difference in distilled water productivity between varying rubber thicknesses. the outputs of mss1, mss2, and mss3 were measured at 1105 ml/day, 1010 ml/day, and 955 ml/day, respectively, all surpassing the output of ssr, which was recorded at 830 ml/day. these results indicate that the utilization of rubber with varying thicknesses positively impacts the productivity of the solar still, leading to higher distilled water yields compared to the reference configuration. keywords: solar energy, water productivity, salty water, solar radiation. received: 10/02/2023 – revised: 11/03/2023 – accepted: 03/04/2023 i. introduction water treatment is the process of purifying and conditioning water to make it safe, clean, and suitable for various purposes, including drinking, industrial use, and environmental protection. it involves a series of physical, chemical, and biological processes to remove contaminants, impurities, and harmful substances from water sources such as rivers, lakes, groundwater, and even wastewater. water treatment using chemical or biological methods involves the application of various processes to remove contaminants and ensure the provision of safe and clean water for consumption and other purposes. chemical methods often include the addition of coagulants, disinfectants, and chemicals that aid in the removal of suspended particles, organic matter, and harmful microorganisms. these chemicals can assist in flocculation, sedimentation, and disinfection processes. on the other hand, biological methods utilize natural processes involving microorganisms to degrade and remove pollutants from water. both chemical and biological methods play vital roles in treating water from various sources, ensuring its quality and safety for human use and environmental protection [1-2]. solar distillation is a simple and effective method of purifying water using the energy from the sun. it involves the process of evaporating water through solar heat and condensing the vapor to produce clean, drinkable water. solar distillation takes advantage of the sun's energy to separate impurities and contaminants from the water, making it a sustainable and environmentally friendly solution for obtaining safe drinking water, particularly in areas with limited access to clean water sources [3-5]. to enhance the efficiency of solar stills, researchers have explored various approaches. one strategy involves incorporating high https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ imad kermerchou et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 19-23 page 20 thermal conductivity materials into the water being treated, which helps to enhance heat transfer and improve distillation rates [6-15]. additionally, some studies have explored the use of biological materials [16-22]. furthermore, the utilization of natural materials, and other simple and complex techniques, has been investigated [23-31]. these innovative approaches contribute to the continuous development of solar still technology. the main objective of our research is to evaluate the potential of rubber as an enhancement material in solar distillation and investigate the influence of rubber thickness on the distillation process. by varying the thickness of the rubber used in solar stills, we aim to determine its impact on the overall performance and productivity of the distillation system. ii. materials and methods ii.1. experiment the experiment was conducted on a specific date, 05/06/2023, with consistent climatic conditions and geometric dimensions, except for the variation in rubber thickness (1cm, 2cm, and 3cm), its pieces are deposited an interior in the solar still as shown in figure 1. the experiment involved the use of 3 liters of salty water, and various measurements were taken including the solar radiation, ambient temperature, and temperature of the inner and outer glass cover, water temperature, and atmospheric conditions. the amount of distilled water produced was measured hourly from 8:00 in the morning until 18:00 in the evening. this comprehensive experimental analysis aims to assess the influence of rubber thickness on the performance of conventional solar stills in an arid region, providing valuable insights into the efficiency of different rubber thicknesses under controlled conditions. ii.2. experience setup in this study, the setup and instrumentation procedures for the solar distillation experiment are described. the process involves placing a water balance on a table to support the four solar distillers, ensuring their alignment and straightness. the tubes are positioned, and 3 liters of water are added to each distiller. the glass cover is thoroughly cleaned to remove impurities, and it is placed level with the distillers. thermal collectors are installed on the internal and external glass surfaces, and the distillers are tightly sealed to prevent thermal leaks. figure 1. experience setup iii. experimental result iii.1. evolution of ambient temperature and solar radiation figure 2 displays the variations in solar irradiance and ambient temperature during the testing of the distillers. the maximum solar irradiance of 1001 w/m 2 was recorded at 12:00h, gradually decreasing until sunset. similarly, the ambient temperature followed a similar pattern, with the highest temperature of 34 °c occurring at 01:00h, followed by a gradual decrease during the sunset hours. the average daily solar irradiance and ambient temperature throughout the testing period were calculated as 750.01 w/m 2 and 30.4 °c, respectively. these findings provide insights into the environmental conditions during the distiller testing, illustrating the temporal dynamics of solar irradiance and ambient temperature. figure 2. evolution of ambient temperature and solar radiation imad kermerchou et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 19-23 page 21 iii.2. evolution of inner surface temperature the experiment was conducted from 8:00h to 14:00h, under consistent climatic conditions. initially, at 8:00h, all the glass covers exhibited the same temperature of 28°c. as the experiment progressed, the temperatures gradually increased, reaching their maximum values at 13:00h, with the following recorded temperatures: ssm3 (45°c), mss2 (42.9°c), ssm1 (42.5°c), and ssr (41.9°c). subsequently, between 13:00h and 14:00h, the temperatures showed a decrease while maintaining the same order of temperatures for each solar still as shown in figure 3. this analysis aims to provide insights into the impact of rubber thickness on temperature fluctuations throughout the day in conventional solar stills, contributing to a better understanding of their thermal behavior. figure 3. glass inner surface temperature evolution iii.3. evolution of water temperature the temperatures in solar stills with different rubber thicknesses were investigated. the experiment commenced with an initial temperature of 27.5°c, in figure 4. subsequently, between 8:00h and 12:00h, the temperatures progressively increased. notably, from 12:00h to 14:00h all solar stills reached their respective maximum temperatures: mss3 (62.5°c), mss2 (59°c), ssm1 (57.5°c), and ssr (55°c). subsequently, between 14:00h and 18:00h, a gradual drop in temperature was observed across all solar stills, while maintaining the previous order of temperatures for each still. this detailed analysis sheds light on the temperature behavior of conventional solar stills with varying rubber thicknesses throughout the day, contributing to a comprehensive understanding of their thermal performance figure 4. water temperature evolution iii.4. evolution of accumulation output figure 5 provides valuable insights into the relationship between rubber thickness and water output in conventional solar stills. it is evident from the figure that the water output deviates significantly in the mms3 solar stills compared to the others. the final accumulated productions for each still are as follows: mss3 (1105 ml/day), mss2 (1010 ml/day), ssm1 (955 ml/day), and ssr (830 ml/day). the figure clearly demonstrates the influence of rubber thickness on the output of the solar stills, revealing a direct correlation between increasing rubber thickness and higher water output. these findings highlight the importance of considering rubber thickness as a factor in optimizing the performance of conventional solar stills, as it can significantly impact the overall water production. iii.5. evolution of hourly output the observations indicate that at 8:00h, no distilled water was produced. however, starting from 9:00h the amount of distilled water began to increase across all solar stills, with a value of approximately 15 ml as shown in figure 6. between 9:00h and 01:00h, the production of distilled water reached its maximum values: ssm3 (160 ml), mss2 (143 ml), mss1 (142 ml), and ssr (135 ml). subsequently, from 15:00h to 14:00h, the amount of distilled water decreased in each solar still, while maintaining the previous order of temperatures for each still. these observations provide insights into the temporal variations in distilled water production in conventional solar stills, highlighting the peak production period and subsequent decline during the latter part of the day. imad kermerchou et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 19-23 page 22 figure 5. water accumulation output evolution figure 6. water hourly output evolution iv. conclusion our study has investigated the effect of rubber thickness on water output in conventional solar stills. the experimental results clearly demonstrate the impact of rubber thickness on the distillation process. the accumulated water productions for different rubber thicknesses were as follows: ssm3 (1105 ml/day), mss2 (1010 ml/day), mss1 (955 ml/day), and ssr (830 ml/day). it is evident that as the rubber thickness increases, there is a corresponding increase in water output. this finding emphasizes the importance of considering rubber thickness as a critical parameter in solar still design and operation. by optimizing rubber thickness, it is possible to enhance the water productivity of conventional solar stills. therefore, our study highlights the significance of further research and development in this field to improve the efficiency of solar distillation systems for sustainable water production. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] abderrahmane khechekhouche, fatouma bouchmel, zineb kaddour, khechana salim, abdelmonem miloudi. "performance of a wastewater treatment plant in southeastern algeria." international journal of energetica, vol. 5, no. 2, 2020, pp. 47-51. https://dx.doi.org/10.47238/ijeca.v5i2.139. [2] asma khelassi-sefaoui, abderrahmane khechekhouche, manel zaoui-djelloul daouadji, hamza idrici. "physicochemical investigation of wastewater from the sebdoutlemcen textile complex, north-west algeria." indonesian journal of science & technology, 2021. https://doi.org/10.17509/ijost.v6i2.34545. [3] abderrahmane khechekhouche, boubaker benhaoua, zied driss, mohammed el hadi attia, muthu manokar. "polluted groundwater treatment in southeastern algeria by solar distillation." algerian journal of environmental and sciences, vol. 6, no. 1, 2020. https://aljest.org/index.php/aljest/article/view/288. [4] kishor kumar sadasivuni et al., "ground water treatment using solar radiation-vaporization & condensation-techniques by solar desalination system." international journal of ambient energy, 2020. doi: 10.1080/01430750.2020.1772872. [5] kishor kumar sadasivuni et al., "productivity enhancement of solar still with thermoelectric modules from groundwater to produce potable water: a review." groundwater for sustainable development, 2020. doi: 10.1016/j.gsd.2020.100429. [6] abderrahmane khechekhouche, boubaker benhaoua, abd elnaby kabeel, mohammed el hadi attia, wael m. el-maghlany. "improvement of solar distiller productivity by a black metallic plate of zinc as a thermal storage material." journal of testing and evaluation, vol. 49, no. 2, 2019.: https://doi.org/10.1520/jte20190119. https://aljest.org/index.php/aljest/article/view/288 https://doi.org/10.1520/jte20190119 imad kermerchou et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 19-23 page 23 [7] khechekhouche et al., "sand dunes effect on the productivity of a single slope solar distiller." heat and mass transfer journal, springer nature, vol. 56, no. 4, pp. 1117-1126, 2020. https://doi.org/10.1007/s00231019-02786-9. [8] khechekhouche et al., "traditional solar distiller improvement by a single external refractor under the climatic conditions of the el oued region, algeria." desalination and water treatment, vol. 117, pp. 23-28, 2020. https://doi.org/10.5004/dwt.2020.24832. [9] ridha cherraye, bachir bouchekima, djamel bechki, hamza bouguettaia, abderrahmane khechekhouche. "the effect of tilt angle on solar still productivity at different seasons in arid conditions-south algeria." international journal of ambient energy, 2020https://doi.org/10.1080/01430750.2020.1723689. [10] khechekhouche et al., "energy, exergy analysis, and optimizations of collector cover thickness of a solar still in el oued climate, algeria." international journal of photoenergy, vol. 2021, article id 6668325. https://doi.org/10.1155/2021/6668325. [11] djamel khamaia, ridha boudhiaf, abderrahmane khechekhouche, zied driss. "illizi city sand impact on the output of a conventional solar still." asean journal of science and engineering, vol. 2, no. 3, 2022, pp. 267-272. [12] bellila et al., "aluminum wastes effect on solar distillation." asean journal for science and engineering in materials, vol. 1, no. 2, 2022. [13] a. khechekhouche, a. m. de oliveira siqueira, nabil elsharif. "effect of plastic fins on a traditional solar still's efficiency." international journal of energetica, vol. 7, no. 1, 2022. [14] khechekhouche et al., "iron pieces effect on the output of single slope solar still." heritage and sustainable development, vol. 4, no. 2, 2022. [15] a. bellila, i. kemerchou, a. sadoun, z. driss. "effect of using sponge pieces in a solar still." international journal of energetica, vol. 7, no. 1, 2022, pp. 41-45. http://dx.doi.org/10.47238/ijeca.v7i1.197. [16] kermerchou et al., "palm fibers effect on the performance of a conventional solar still." asean journal for science and engineering in materials, vol. 1, no. 1, 2022. [17] a. sadoun, a. khechekhouche, i. kemerchou, m. ghodbane, b. souyei. "impact of natural charcoal blocks on the solar still output." heritage and sustainable development, vol. 4, no. 1, 2022, pp. 61–66. [18] brihmat et al., "energy performance improvement of a solar still system using date and olive kernels: experimental study." clean soil air water, december 2022. [19] khechekhouche et al., "energy, exergy investigation of absorber multilayered composites materials of a solar still in algeria." journal of testing and evaluation, vol. 51, no. 5, 2023, pp. 13. https://doi.org/10.1520/jte20220577. [20] temmer et al. "effect of different carbon types on a traditional solar still's output." desalination and water treatment, in press 2022-2023. [21] a. khechekhouche et al. "impact of solar energy and energy storage on a still's nocturnal output." journal of testing and evaluation, vol. 51, no. 6, 2023, p. 10. doi: 10.1520/jte20220701. [22] abdelmonem miloudi, abderrahmane khechekhouche, imad kermerchou. "polluted groundwater treatment by solar stills with palm fibers." jp journal of heat and mass transfer, vol. 27, 2022. [23] a. khechekhouche, a. boukhari, z. driss, n.e. benhissen. "seasonal effect on solar distillation in the el-oued region of south-east algeria." international journal of energetica, vol. 2, no. 1, 2017, pp. 42-45. http://dx.doi.org/10.47238/ijeca.v2i1.27. [24] a. khechekhouche, b. ben haoua, z. driss. "solar distillation between a simple and double-glazing." revue de mécanique, vol. 2, no. 2, 2017. doi: 10.5281/zenodo.1169839. [25] mehdi jahangiri, somayeh pahlavan, akbar alidadi shamsabadi, abderrahmane khechekhouche. "feasibility study of solar water heaters in algeria: a review." journal of solar energy research, 2018, pp. 135-146. https://jser.ut.ac.ir/article_67424.html. [26] abderrahmane khechekhouche, benhaoua boubaker, mruthu manokar, ravishankar sathyamurthy, abd elnaby kabeel. "exploitation of an insulated air chamber as a glazed cover of a conventional solar still." heat transfer asian research, vol. 48, issue 5, 2019, pp. 1563-1574. doi: 10.1002/htj.21446. [27] abderrahmane khechekhouche, nabil elsharif, imad kermerchou, ali sadoun. "construction and performance evaluation of a conventional solar distiller." heritage and sustainable development, vol. 1, no. 2, 2019, pp. 7477. doi: 10.37868/hsd.v1i2.3. [28] abderrahmane khechekhouche, zied driss, benjamin durakovic. "effect of heat flow via glazing on the productivity of a solar still." international journal of energetica, vol. 4, no. 2, 2019, pp. 54-57. [29] belgacem souyei, abderrahmane khechekhouche, souhaila meneceur. "effect of comparison of a metal plate and a refractory plate on a solar still." jp journal of heat and mass transfer, vol. 27, 2022. [30] d. djaballah, b. benhaoua, a. khechekhouche. "surface tension force effect on the solar still output." jp journal of heat and mass transfer, vol. 28, 2022. [31] bellila et al., "ethanol effect on the performance of a conventional solar still." asean journal of science and engineering, vol 4, 2022, pp. 25-32. doi: 10.17509/ajse.v4i1.56026 https://doi.org/10.1007/s00231-019-02786-9 https://doi.org/10.1007/s00231-019-02786-9 https://doi.org/10.5004/dwt.2020.24832 https://doi.org/10.1080/01430750.2020.1723689 https://doi.org/10.1155/2021/6668325 http://dx.doi.org/10.47238/ijeca.v7i1.197 https://doi.org/10.1520/jte20220577 http://dx.doi.org/10.47238/ijeca.v2i1.27 https://jser.ut.ac.ir/article_67424.html international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 01-05 ijeca-issn: 2543-3717. december 2017 page 1 numerical investigation of heat transfer enhancement inside a parabolic trough solar collector using dimpled absorber amina benabderrahmane, abdelylah benazza faculty of technology, djilali liabes university. sidi bel abbes. algeria amina.benabderrahmane@yahoo.fr abstract – three dimensional numerical investigation of heat transfer enhancement in a nonuniformly heated parabolic trough solar collector using dimpled absorber under turbulent flow was incorporated in the current paper. the governing equations were solved using the finite volume methods (cfd) with certain assumptions and appropriate boundary conditions. the monte carlo ray trace technique was applied to obtain the heat flux distribution around the absorber tube. the numerical results were validating with the empirical correlations existing in the literature and good agreement was obtained. the present results demonstrate that the inclusion of inserts provide a good performance in heat transfer, also the receiver temperature gradient are shown to reduce with the use of geometrical modification, the absorber geometry have a remarkable effect on the htf velocity distribution. keywords: numerical investigation, parabolic trough solar collector, heat transfer enhancement, turbulent flow, dimpled tube. received: 16/11/2017 – accepted: 15/12/2017 i. introduction heat transfer enhancement is an active and important field of engineering research. many studies are carried out to improve the heat transfer following both numerical and experimental methods. heat transfer achievement techniques are typically classified into three categories: active techniques (using external inputs, electrical power or rf signals, vibration, and synthetic jet….etc). passive techniques (using surface or geometrical modification to the flow by incorporating inserts as: twisted tape, wire coils, fins, baffles, or by additives like gas bubbles, solid particles, liquid droplets…etc.) and compound techniques in which two or more passive or/and active techniques are employed together. at present, different methods of convective heat transfer enhancement have been proposed and studied. yakut et al. [1] experimentally investigated the effect of conical ring turbulators on the turbulent heat transfer, pressure drop. they indicated that nusselt number increases with the smallest pitch arrangement. ayhan et al. [2] examined numerically and experimentally the heat transfer improvement in a tube with truncated hollow cone inserts; they reported that tube with inserts gives higher heat transfer enhancement. eiamsa-ard et al. [3] studied the effect of v-nozzle turbulators and conical nozzle on heat transfer and friction factor inside a uniformly heat flux tube, they found that heat transfer rate increases for using the both techniques. saha et al. [4] investigated pressure drop and heat transfer characteristics in a circular tube equipped by regularly spaced twisted tape elements; they declared that pinching of place rather is a better property from thermo-hydraulic performance. amina et al. [5] investigated numerically the effect of triangular and rectangular longitudinal fins on heat transfer enhancement inside ptc receiver; they concluded that ptc thermal performance increase with inserting fins. amina et al. [6] studied again the effect of baffles on heat transfer enhancement, they reported that high nusselt number and friction factor are obtained for tube fitted with baffles and the inserts have a remarkable effect on fluid flow characteristics. the aim of this numerical investigation is to estimate the convective heat transfer enhancement in the fully developed turbulent flow under a non-uniform heat flux using dimpled absorber; the results of these studies are presented in the form of nusselt number and darcy friction factor. ii. geometrical configuration model in this work; we have considered a simplified model of a parabolic trough receiver in which the effect of the central rod and other supports is considered negligible. a detailed schematic diagram of the receiver is presented in figure 1, where the materiel used for the glass cover and the absorber tube are borosilicate glass and steel respectively, the annular space between both tubes is considered as vacuum at very low pressure and ambient temperature. the principal objective of this paper is to improve heat transfer inside ptc receiver using simple geometrical mechanisms easily realizable in mailto:amina.benabderrahmane@yahoo.fr a. benabderrahmane et al. ijeca-issn: 2543-3717. decembre 2017 page 2 the industry, by means of modifying the absorber geometry by longitudinal dimples which acts as a passive vortex generators. the configuration proposed is shown in figure 2. and the physical parameters are given in table. 1. figure 1. schematic of cross-section of the receiver figure 2. schematic of dimpled absorber table 1. receiver’s physical parameters. focal length 1.71 m aperture width 5.77 m receiver length 200 cm absorber inner radius 3.2 cm absorber outer radius 3.5 cm glass cover inner radius 5.96 cm glass cover outer radius 6.25 cm material of the absorber steel material of the glass cover borosilicate transmittance of the glass envelope >95% glass cover emissivity 0.837 iii. boundary conditions in this study, the outer absorber’s wall receives a nonuniform heat flux obtained by using mcrt technique [7] and taking the dni of 1000 w/m 2 , the local concentration ratio distribution results are illustrated in figure 3. for the outer glass envelope, a thermal boundary condition that includes the convection and radiation heat transfer is used. sky temperature and sky emissivity can be calculated using the following correlations [8], [9]: 1 5 0 0552 . sky ambt . t (1) 2 273 15 273 15 0 711 0 56 0 73 100 100 dp dp sky t . t . . . .            (2) where the ambient temperature used in this simulation is 300k and tdp is dew point temperature (k). additionally, the convection heat transfer coefficient used for the boundary condition is defined by the experimental correlation [10]: 0 58 0 42 4 . . w w goh v d   (3) where: vw is the wind speed (2m/s in this study) and dgo is the glass cover outer diameter. figure 3. local concentration ratio on a cross-section of absorber outer surface. iv. validation of the numerical results the present numerical results for smooth absorber were validating using empirical correlations. for nusselt number, we used gnielinski [11] and notterrouse [12] correlations; and for friction factor results, the numerical data was compared with petukhov [13] and blasius [14] correlations.   0 5 2 3 1000 8 1 12 7 1 8 . f re pr nu f . pr              (4) 0 856 0 347 5 0 015 . . nu . re pr  (5)   2 0 79 1 64f . ln re .    (6) where re varies from 10 4 to 5x10 6 0 25 4 0 316 2 10 . f . re ; re     (7) 0 2 4 0 184 2 10 . f . re ; re     (8) as clearly seen in figure 4, the numerical model was been successfully validated with the empirical results, where the maximum deviation was less than 8%. a. benabderrahmane et al. ijeca-issn: 2543-3717. decembre 2017 page 3 figure 4. validation of numerical results. v. results and interpretations v.1. effect of absorber geometry on heat transfer the numerical results on heat and fluid flow characteristics in a non-uniformly heated ptc receiver with inserts are presented in the form of nusselt number and friction factor. the numerical data carried out under forced turbulent flow conditions are reported in fig. 5 and figure 6. figure 5 illustrates the enhancement of the average nusselt number with reynolds number due to the presence of inserts, the nu increases with increasing re for smooth absorber and enhanced absorber. as can be noticed, the solution of the dimpled absorber retrieves a higher nusselt number compared to the smooth tube model, where the nusselt number increases of about (1.4 to 2 times which means that the absorber geometry plays an important role in the heat transfer so, these results have indicated the beneficial effects due to the inserts in the tube side of ptc receiver. on the other hand, figure 6 represents the variation of darcy friction factor for tube with and without inserts. as expected in literatures the friction factor decreases with increasing reynolds number. it can be seen that the friction factor augments about 1.14 times, these higher values are the results of the swirling flow induced by the longitudinal dimples that act like an obstacle. figure 5. variation of nusselt number with reynolds number for absorber with and without heat transfer enhancement. figure 6. variation of friction factor with reynolds number for absorber with and without inserts. vi.2. temperature distribution analysis figure 7 presents the temperature distributions of the htf along the radial direction on the middle cross section of the absorber, the higher temperature on the bottom part dues to the non-uniform heat flux, however the heat flux distribution is symmetrical approximately, that’s why half of the circumferential angles are presented, the temperature increases where the inserts are placed but decreases in clear fluid region, the maximum temperature region close to the receiver tube rises up along the inner wall, increased heat transfer performance is expected to reduce the temperature gradients in the receiver’s absorber tube. on the other hand, the variations of temperature distributions of the absorber tube which play a crucial role in the heat collecting is studied. it can be seen from fig. 8 that the absorber equipped with inserts give a slight reductions in the absorber tube temperature gradients which leads to the higher heat transfer enhancement. figure 7. htf temperature distributions on the absorber’s middle cross-section for plain tube and dimpled tube a. benabderrahmane et al. ijeca-issn: 2543-3717. decembre 2017 page 4 figure 8. absorber temperature distribution for smooth tube and enhanced tube. vi.3. velocity field analysis figure 9 presents the htf velocity distribution at the cross-section in fully developed region for the tube with and without inserts at the same conditions. it is noticed that the htf velocity inside a tube is maximum at the center and tends to zero at the walls, which is clearly shown in figure 9 in the case of smooth absorber, while the inclusion of inserts change the velocity distributions where the velocity is almost uniform in a large area of the absorber and minimal at the walls. figure 9. htf velocity distributions on the middle cross-section. vi. conclusion three-dimensional numerical simulation on enhancing heat transfer in a non-uniformly heated parabolic trough solar collector under turbulent flow by using a passive technique is performed in this paper. the following conclusion can be drawn: the nusselt number for absorber fitted with inserts increases by around 104 to 120%. the skin friction coefficient of dimpled tube augments 1.14 to 1.45 times compared to the smooth tube. the absorber geometry has remarkable effects on htf temperature, on the inner wall absorber temperature distribution and on htf velocity. references [1] k. yakut, b. sahin, s. canbazoglu, performance and flowinduced vibration characteristics for conical-ring turbulators, applied energy 79 (2004) 65–76. [2] t. ayhan, y. azak, c. demirtas, b. ayhan, numerical and experimental investigation of enhancement of turbulent flow heat transfer in tubes by means of truncated hollow cone inserts, heat transfer enhancement of heat exchangers, kluwer academic publishers, 1999, pp. 347– 356. [3] s. eiamsa-ard, p. promvonge, experimental investigation of heat transfer and friction characteristics in a circular tube fitted with vnozzle turbulators, international communication heat and mass transfer 33 (2006) 591– 600. [4] s.k.saha, a.dutta and s.k.dhal, “friction and heat transfer characteristics of laminar swirl flow through a circular tube fitted with regularly spaced twisted-tape elements”, int. j. heat and mass transfer, 44, 2001,4211– 4223. [5] a. benabderrahmane, m. aminallah, s. laouedj, a. benazza, j.p.solano. heat transfer enhancement in a parabolic trough solar receiver using longitudinal fins and nanofluids. journal of thermal sciences. vol.25, no.5 (2016) 410-417. [6] a. benabderrahmane, a. benazza, m. aminallah, s. laouedj. heat transfer behaviors in parabolic trough solar collector tube with compound technique. international journal of scientific research engineering & technology (ijsret). volume 5, issue 11 (2016). [7] nrel. soltrace optical modeling software. soltrace 2012; 2012.7.9; 2012. [8] garcía-valladares o, velázquez n. numerical simulation of parabolic trough solar collector: improvement using counter flow concentric circular heat exchangers. int j heat mass transfer 2009; 52:597–609. [9] pandey dk, lee iii rb, paden j. effects of atmospheric emissivity on clear sky temperatures. atmos environ 1994; 29(16):2201e4. [10] mullick sc, nanda sk. an improved technique for computing the heat loss factor of a tubular absorber. sol energy 1989; 42:1–7. [11] v. gnielinski, “new equations for heat and mass-transfer in turbulent pipe and channel flow,” in int j chem eng, (1976), 16(2):359e68. [12] r.h. notter, m.w. rouse, a solution to the graetz problem-iii. fully developed region heat transfer rates, chemical engineering science, 27 (1972) 2073-2093. [13] b.s. petukhov. in: irvine tf, hartnett jp, editors. heat transfer and friction in turbulent pipe flow with variable a. benabderrahmane et al. ijeca-issn: 2543-3717. decembre 2017 page 5 physical properties. advance in heat transfer, (1970), pp. 503-64. [14] incropera f, dewitt d. fundamentals of heat and mass transfer. 3rd ed. (john wiley and sons, new york, 1990), pp. 490. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 01-05 ijeca-issn: 2543-3717. june 2018 page 1 modeling electric field and potential distribution of an model of insulator in two dimensions by the finite element method nassima m’ziou 1,2 , hani benguesmia 1,3* , hilal rahali 3 1 laboratoire de recherche (li3cub), biskra university, algeria 2 department of electrical engineering, faculty of engineer sciences, boumerdes university, algeria 3 department of electrical engineering, faculty of technology, m’sila university, b.p. 166, 28000 m’sila, algeria e-mail*: hanibenguesmia16@gmail.com abstract – the electrical effects can be written by two magnitudes the field and the electrostatic potential, for the determination of the distribution of the field and the electric potential along the leakage distance of the polluted insulator, the comsol multiphysics software based on the finite element method will be used. the objective of this paper is the modeling electric field and potential distribution in two dimensions by the finite element method on a model of insulator simulating the 1512l outdoor insulator used by the algerian company of electricity and gas (sonelgaz). this model is under different conductivity, applied voltage, position of clean layer and width of clean layer. the computer simulations are carried out by using the comsol multiphysics software. this paper describes how comsol multiphysics have been used for modeling of the insulator using electrostatic 2d simulations in the ac/dc module. numerical results showed a good agreement. keywords: model of insulator, pollution, high voltage, potential distribution, eectric field. received: 30/05/2018 – accepted: 25/06/2018 i. introduction the pollution flashover, observed on insulators used in high voltage transmission, is one of the most important problems for power transmission. it is a very complex problem due to several factors such as the modeling difficulties of complex shapes of the insulators, different pollution density at different regions, non-homogeneous pollution distribution on the insulator surface and unknown effect of humidity on the pollution. in the literature, some static and dynamic models were developed by making some assumptions and omissions to predict the flashover voltages of polluted insulators [1,2]. the problematic related to such a study, is in the difficulty to determine, experimentally, in a precise way, the distribution of the potential and moreover, that of the electric field along polluted insulators. indeed, these measurements, which can only be performed in the laboratory, require heavy and sophisticated equipment, usually expensive [3]. however, there is an alternative to experimental measurements, consisting of the use of digital tools to determine electrical potential and field distributions along polluted insulators. with the increasing development of increasingly powerful computing and numerical computation software, it is now possible to obtain fast and accurate results. it is very interesting to have a simulation environment that includes the possibility of adding different physical phenomena to the studied model. it is in this philosophy that comsol multiphysics has been developed. it is a finite element numerical computation software allowing to model a large variety of physical phenomena characterizing a real problem. among the numerical methods available and applicable to electromagnetic calculations, the finite element method. thus, its use, using commercial software comsol multiphysics, was used to carry out the various simulations [4]. it is very interesting to have a simulation environment that includes the possibility of adding different physical phenomena to the studied model. it is in this philosophy that comsol multiphysics has been developed. the determination of the distribution of the field and the electric potential on the insulating surfaces, in the presence of the pollution, has been the subject of numerous researches [5-7]. the main aim of our work is to see the distribution of the field and electric potential on a type 1512l cap and n. m’ziou et al ijeca-issn: 2543-3717. june 2018 page 2 pin insulator model of artificially polluted high voltage, under ac voltage, subjected to various parameters such as the conductivities. ii. description of the insulator model in our simulation, we chose model 1512l insulator plan. the dimensions of the model defined by moula et hilal [8,9], the model is a plane that is constituted by a glass plate of (500x500mm) on which are placed two electrodes, one of ground and the other of high voltage, and the two electrodes are placed on two aluminum conductive bands that are cut (500x 500mm) for the glass and (500x30mm) for the two electrodes. the distance between two electrodes is 292mm. figure 1. real model vs model plane of insulator. iii. identification of domains in the comsol software comsol multiphysics is an analysis software and finite element solver, which has various applications in physics and engineering especially coupled phenomena, or multi-physics. the different domains of the insulator studied in comsol multi-physics were defined by introducing for each of them the dielectric constant εr and the conductivity σ (µs/cm). the model is a plane that consists of three parts with different properties: the glass having a relative permittivity equal to εr=6, and the conductivity σ=10 -12 , the aluminum electrodes of relative permittivity of εr=10 6 and conductivity of σ=10 6 , attached to the polluted layers having a relative permittivity of 80 and of which we vary the conductivity. the air a rounding the insulator has a permittivity of εr=1 and σ=10 -14 . this software uses the finite element method; the simulation of the model of insulator can be summarized in the following four successive steps:  the first step is to define the two-dimensional geometry of the model in comsol.  the second step is the definition of the electrical properties of the materials present. this consists in defining the relative permittivities and the volumic conductivities for each part of the model. in addition, it is necessary to define the boundary conditions that result in the potential imposed on each electrode (dirichlet conditions).  the third step is devoted to solving the problem by applying the numerical method and by the construction of the system of equations ( 0 vgraddivvgraddiv  ), and this in introducing the factors of each part of the equation.  the final step is to display the results as the electrical potential and field with their modules, following each part of the plane model and their distributions. iv. simulations results several application-specific modules are available for comsol multiphysics. we chose the ac/dc module. this module simulates electrical components and devices that depend on electrostatic, magnetostatic and electromagnetic quasi-static and another application. for the case studied, we have taken as boundary conditions for the active electrode (hv) a constant potential equal to 30kv (high voltage) and ground electrode a l potential equal to 0v. the mesh density of the finite elements is important for critical areas (close to the surface of the insulator) where greater precision is required, because the electrical properties of the materials are very changeable. indeed, we considered 1376 elements, and after refining we find 5504 elements in the case of a polluted insulator model. the mesh is illustrated in the clean case, in the figure 2. the study of potential and electric field distributions is along a plane model of real 1512l insulator. to illustrate the impact of any parameter denoted x, we plot the potential and the field as a function of the isolator leakage distance for different l, with l <=> (l1, l2 and l3) shown in figure 3. real model model plane of insulator hv electrode 500mm 5 0 0 m m figure 3. mesh of the plane model n. m’ziou et al ijeca-issn: 2543-3717. june 2018 page 3 0 5 10 15 20 25 30 0 0.5 1 1.5 2 2.5 3 x 10 4 ligne de fuite en (cm) t e n s io n e n ( v ) propre 700 µs /cm 1200 µs /cm 2400 µs /cm 3000 µs /cm 8.9 9 9.1 2.97 2.98 2.99 x 10 4 14.5998 14.5998 14.5998 14.5998 1.5 1.5 1.5 1.5 x 10 4 20 20.1 20.2 0 100 200 300 figure 3. plan model with all specifications iv.1. distribution of electrical potential we are interested in determining the potential distribution along the insulator leakage distance as a function of the conductivities. for this, we have introduced in the software different conductivities values (700, 1200, 2400, 3000 μs/cm), with the applied voltage equal to 30kv and a clean layer (li) fixed, equal to 3cm. figures 4 to 5 illustrates respectively the variation of the potential along of the leakage distance and the potential distribution for the conductivities examined. there is a low influence on the potential distribution when you vary the values of the conductivities, the potential distribution along the leakage distance of a 1512l model, a rapid reduction in clean layer levels and a slowdown in the polluted layers. if the clean model the potential decreases in a linear way, on the other hand for the polluted case the clean layer (li) forms an obstacle when the potential stays stable then decreases quickly until the potential equal to 0v. leakage distance (cm) figure 4. electrical potential-leakage distance for different conductivities 3000µs/cm figure 5. distribution of electrical potential for various conductivities in two cases, echogram & equipotential lines e le c tr ic a l p o lt e n ti a l (v ) clean state 700µs/cm 2400µs/cm 1200µs/cm polluted layer l2 l3 clean layer (l) leakage distance 292mm hv (30kv) 0v glass l1 n. m’ziou et al ijeca-issn: 2543-3717. june 2018 page 4 0 5 10 15 20 25 30 0 500 1000 1500 2000 2500 3000 3500 ligne de fuite en (cm) c h a m p é le c t r iq u e e n ( k v / m ) propre 700 µs /cm 1200 µs /cm 2400 µs /cm 3000µs /cm iv.2. distribution of electrical field we are interested in the influence of the conductivity on the electric field distribution for different values of the conductivity (700, 1200, 2400, 3000 μs / cm) with applied voltage equal to 30 kv. figures 6 to 7 respectively illustrate the variation of the electric field along the leakage distance and the electric field distribution for the conductivities cited above. figure 6. electric field-leakage distance for different conductivities we noticed after the appearance of the results that the change of the conductivities has a slight effect on the intensity of the electric field; it is zero inside the two electrodes, because aluminum foil is a perfect conductor. in the proper case the electric field take the value 1000 kv/m is remains constant along the leakage distance to the ground electrode is canceled. in figure 7, you can see for example in the case own the model corners is in red, which explains the intensity of the electric heat is very high, the concentration of electric arcs on the corners of the model, may be due to shape of the model, can also be explained by the movements of concentrated electrons in these corners (leakage current). figure 7. distribution of electric field for various conductivities in two cases, echogram & equipotential lines clean state 700µs/cm 2400µs/cm leakage distance(cm) e le c tr ic f ie ld (k v /m ) 1200µs/cm 3000µs/cm n. m’ziou et al ijeca-issn: 2543-3717. june 2018 page 5 v. conclusion in this paper we present the results of different simulations performed on the model of a 1512l isolator. using the comsol multiphysics software, based on the finite element method, we have been able to analyze the potential and electric field distributions of the 1512l plane model, subjected to electro-geometric parameter, namely the conductivities. as main results, we can say that the conductivities of the polluting layer have practically no effect on the distributions of the potential and the electric field. on the other hand, the intensity of the electric field is more important at the level of the clean layer. the vector of the electric field in the plan model is parallel because the configuration of the geometry represents a distribution of the uniform electric field. (plan-plan). the variation of the conductivities has a slight influence on the intensity of the electric field. acknowledgements we thank the anonymous referees for their useful suggestion. references [1] h. benguesmia, n. m’ziou, a. boubakeur, simulation of the potential and electric field distribution on high voltage insulator using the finite element method, diagnostyka, vol 19 (2) , 2018, pp 41-52. [2] h. benguesmia, n. m’ziou, a.m. chouchou, l rachdi, experimental study of the various pollution and simulation of potential and electric field distribution using femm at a high voltage insulator under alternative current, international symposium on computational and experimental investigations of fluid and structure dynamics, (cefsd2015-94), hammamet, tunisia, march 16-18, 2015, pp 144. isbn: 978--9938--9564--2--9. [3] a. nekahi, s. g. mcmeekin, m., farzaneh, effect of pollution severity on electric field distribution along a polymeric insulator, in : properties and applications of dielectric materials (icpadm), 2015 ieee 11th international conference on the. ieee, 2015, pp 612-615. [4] comsol multiphysics, user’s manual, version 5. [5] t. zhao, m. g. comber, calculation of electric field and potential distribution along non-ceramic insulators considering the effects of conductors and transmission towers, ieee transactions on power delivery, vol 15 (1), 2000, pp 313-318. [6] l. a. dissado, j. c. fothergill, electrical degradation and breakdown in polymers, iet (no.9), 1992. [7] arshad, a. nekahi, s.g. mcmeekin, m. farzaneh, effect of pollution severity on electric field distribution along a polymeric insulator, 11th international conference on the properties and applications of dielectric materials (icpadm) 2015. ( in press) [8] b.moula, a. mekhaldi, m. teguar, evaluation of insulator's energy under uniform pollution condition, in: energy conference and exhibition (energycon), 2012 ieee international. ieee, 2012, pp 975-978. [9] h. rahali, comportement d’un modèle d’isolateur sous différentes configurations de pollution sous tension alternative 50 hz, magister's thesis, ecole nationale polytechnique, algiers, algeria, 2011. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 31-37 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 31 developed nonlinear model based on bootstrap aggregated neural networks for predicting global hourly scale horizontal irradiance abdennasser dahmani 1,2* , yamina ammi 2 , salah hanini 2 , zied driss 3 1 department of mechanical engineering, faculty of science and technology, gidd industrial engineering and sustainable development laboratory, university of relizane, bourmadia, 48000, relizane, algeria 2 laboratory of biomaterials and transport phenomena (lbmpt), university of medea, algeria 3 laboratory of electro-mechanic systems, national school of engineers of sfax, university of sfax, tunisia *corresponding author: email: dahmani.abdennasser@univ-relizane.dz abstract – this research study examines the use of two models of artificial intelligence based on a single neural network (snn) and bootstrap aggregated neural networks (bann) for the prediction value of hourly global horizontal irradiance (ghi) received over one year in tamanrasset city (southern algeria). the snn and bann were created using overall data points. to improve the accuracy and durability of neural network models generated with a limited amount of training data, stacked neural networks are developed. to create many subsets of training data, the training dataset is re-sampled using bootstrap re-sampling with replacement. a neural network model is created for each set of training datasets. a stacked neural network is created by combining multiple individual neural networks (inn). for the testing phase, higher correlation coefficients (r = 0.9580) were discovered when experimental global horizontal irradiance (ghi) was compared to predicted global horizontal irradiance (ghi). the performance of the models (inn, bann, and snn) demonstrates that models generated with bann are more accurate and robust than models built with individual neural networks (inn) and (snn). keywords: horizontal irradiance, single neural networks, bootstrap aggregated, prediction. received: 31/04/2023 – revised: 25/05/2023 – accepted: 05/06/2023 i. introduction renewable energy sources are universally acknowledged as being essential for any country's long-term energy growth. this strategic focus on energy resource diversification has been spurred by the threats of not having adequate and secure sources of energy at low rates, as well as the environmental harm caused by the usage of fossil fuels [1,2]. solar energy is important both economically and environmentally since it protects the environment and promotes a healthy society [3]. algeria is located in the sunbelt, an area rich in solar energy potential. the algerian ministry of energy and mining approved law in 2011, which lays the framework for the country's long-term renewable energy policy. algeria's geographical location gives it a huge edge in terms of solar energy potential. on the whole of algeria's national territory, the annual sunlight length surpasses 3,600 hours, and on high plateaus and in the sahara, it may even approach 3,900 hours [4]. unfortunately, due to the cost-effectiveness of the measurement equipment (solarimeters/ pyranometers) and systems involved, solar irradiation measurements are difficult to obtain in many locations in algeria (charge, cost, maintenance, calibration requirement). despite the presence of a number of weather stations in various sites around algeria, measurements are not always available due to recording problems caused by significant power outages, particularly during the summer, or because dataset is limited. as a result, it is far more significant to use complicated procedures to accurately predicted solar radiation (sr) using more readily available meteorological data [5]. recently, artificial intelligence techniques have received much method that offers an alternative approach to modeling as they can deal with difficult and poorly https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 32 defined problems in many scientific domains. in the meteorological field, several authors have investigated to apply of artificial neural network models for modeling the prediction of (sr) as can be seen from the following literature: rehman and mohandes. used neural network technology to predict the values of solar radiation falling on the city of abha in saudi arabia from 1998 to 2004 using three models based on temperature and relative humidity, the findings reveal that neural networks can accurately estimate gsr from temperature and relative humidity for sites where temperature and humidity data are available [6]. a research paper applied radial basis function technology for a good and optimal prediction of the hourly solar radiation values in the saudi arabian city of menorah using only two parameters as input, the temperature, and length of sunshine. however, the results were good [7]. the transfer model was constructed using artificial neural networks (ann) to predict the differences between tilted and horizontal irradiance at three different sites in taiwan over a one-year. the experimental findings reveal that the suggested anns with differential outputs may significantly increase estimation [8]. one study applied the datasets from the meteorological agency and the turkish state for predicting solar radiation parameters over a four-year period for seven cities in the anatolian-mediterranean region of turkey. the obtained results show that the method can be used by researchers or scientists to design efficient solar devices. the number of input parameters was also found to be the most effective parameter for estimating future solar radiation data [9]. the ability of a multilayer perceptron to provide very short (five-minute) exposure readiness estimates over a two-year period was investigated in bouzareah –algeria [10]. the inclined irradiation using data from thirteen places in algeria's various climate zones, eight parameters were used as input. the current best neural network model has a root mean square error low 6 wh/m 2 [11]. a research paper applied twenty-two empirical models, artificial neural network techniques, machine learning methods, and treebased ensemble methods tested to estimate daily global solar irradiance in five cities in morocco. the results show that the empirical results perform well and are more robust than other intelligent models [12]. another study focused on using neural networks in multi-location to predict the gsr over italy using non-meteorological data such as geographic locations [13]. another research paper tested twenty empirical models to predict (gsr) in six meteorological stations on the fiji islands [14]. the bootstrap aggregated neural networks method was suggested by a research group [15]. it is a method of improving the generalization ability of a model by training multiple neural networks and then combining them. this strategy is successful and easy to use, having to be applied in a variety of situations [16]. stacked neural networks have been shown to generalize better than individual neural networks [17,18]. several strategies proposed to exploit the strengths of artificial neural network models [19]. the aim of this research work was to improve a bootstrap aggregated-based neural networks (bann) model to predict the hourly global horizontal irradiance (ghi) received over one year in tamanrasset city (southern algeria) based climatological and meteorological parameters. to the best of our knowledge, there is no reported study of model prediction (ghi) using bootstrap-based anns in the literature. ii. material and methods ii.1. study area and data collection tamanrasset is the largest algerian province with an area of 336000 km 2 , about 15 % of the country's area located in the great south-east. which benefits from the abundant sunlight of more than 3600 hours per year with an average daily irradiation more than 6 kwh/m 2 /day [20]. in this research work, the meteorological database (db) were collected from eppley psp pyranometer for predicting hourly global horizontal irradiance (ghi) in tamanrasset region over one year situated in the west of algeria with latitude: +22.783°, longitude: + 5.517°, and altitude of 1377 m. it is characterized by higher radiation than other algerian ground places. the geographical coordinates of the study site are located on the map of algeria (see figure 1). figure 1. position of the study area: a) algeria country abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 33 figure 1. position of the study area: b) tamanrasset area. c) elevation of the city [21] ii.2. single neural network single neural networks (snn) have been developed as a model of how the human brain processes information, learning snns, and extracting developmental performance from past operational information. generally, there are two cases of neural network model learning, supervised learning and unsupervised learning. in the first case of supervised learning, a set of training input vectors is trained with a corresponding set of target vectors to tune the weights in (nn). in the second case, no object vectors are specified in unsupervised learning of one or more hidden layers, whose computation nodes are correspondingly named hidden neurons of hidden layers [22,23]. the structure of the neural network contains three layers called input, hidden, and output layers. the inputs signal received from external sources bias (b) are multiplied by weights (w). depending on the neural network activation function, if the results of multiplying y surpass the threshold, the signal will be released and sent to the output [5]. figure 2 shows the architecture of feed forward single neural network. figure 2. multi-layer perceptron, feed-forward single neural network ii.3. bootstrap aggregated neural networks (bann) a most significant method to enhance the strength of neural network models is to improve a set of neural models, many researcher have studied the multiple of a set of neural networks. the creation of the bootstrap aggregated neural networks model is done by sampling the training database using a function matlab 2020b software [24,25]. bootstrap aggregated neural networks (bann) is used in this research study to improve an accurate model for prediction hourly global horizontal irradiance (ghi) in tamanrasset city, figure 3 showed a bootstrap aggregated where neural network model are built to the relationship between inputs-outputs and are then aggregated individual neural networks (inn) are learned using various training datasets. figure 3. structure of bootstrap aggregated neural networks (bann) model ii.4. modeling the neural networks in this research study, a method based on the optimization and improvement of the structural design of neural networks is advanced. it is based, as defined in figure 4, on the plan of three neural network models: snn, inn, and bann (stacking of 10, 15, 20, 25, and 30 networks)). the neural network models (snn and inn) were ameliorated, every neural network (snn and "10, 15, 20, 25, and 30" individual nn models) have three layers: one input layer with eight neurons for nn in the input layer, the number of neurons in hidden was varied between 3 to 25 neurons. the tangent hyperbolic, the log sigmoid, the sin, and the exponential activation functions were applied in the hidden layer. the pure-linear activation function was applied in the output layer. bfgs quasinewton training algorithm was applied for trained for all neural network (snn and inni) models. the average of the inn outputs gives the (bann) model. the matlab 2020b and statistica software applied for the creation of each model. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 34 figure 4. flow diagram for development different models (snn, inn, and bann (stacking of 10, 15, 20, 25, and 30 networks) iii. results and discussion iii.1. effect of the division of database table 1 displays error (root mean squared error "rmse") values and coefficient of correlation "r" obtained for the global horizontal irradiance under the influence of the division of the database for the snn model with division 1 (2694 points for training (80%), 336 for validation phase (10%), and 336 for testing phase (10%)), division 2 (2356 points for training (70%), 505 for validation phase (15%) and 505 for testing phase (15%)), and division 3 (2020 points for training (60%),673 for validation phase (20%), and 673 for testing phase (20%)). it has been observed that the first division represents the greatest result. table 1. influence of the division of database phases percentage errors rmse (wh/m 2 ) r division 1 training phase 80% 87.1485 0.9361 validation phase 10% 93.1570 0.9241 testing phase 10% 81.7573 0.9446 division 2 training phase 70% 91.6322 0.9287 validation phase 15% 94.3601 0.9225 testing phase 15% 89.8774 0.9345 division 3 training phase 60% 92.9007 0.9277 validation phase 20% 92.4126 0.9267 testing phase 20% 84.8200 0.9381 iii.2. comparison between different bootstrap neural network models in order to compare five models of bann were implemented: stacking 10 networks, stacking 15 networks, stacking 20 networks, stacking 25 networks, and stacking 30 networks. we evaluated the model predictive error (mpe), root mean squared error (rmse), mean absolute error (mae) and standard error of prediction (sep): where n is the total number of data; is the experimental value, represents the calculated value from the neural network model and is the average value of experimental data. figure 5 shows the comparison between bann models in terms of mae, mpe, rmse, and sep. it can be seen that the bann with stacking 30 nets is more robust than the other bann stacking models, (mae = 49.9095 (wh/m 2 ), (mpe = 10.9726 (wh/m 2 ), (rmse = 71.4998 (wh/m 2 ), and (sep=13.5391 (wh/m 2 )) for testing phase. figure 5. several type of errors vs. different stacking neural network models for test datasets iii.3. performance neural network (inn and snn) models the configurations of the 30 optimized individual neural networks "nn" models used to build the bann (with stacking 30 nets) and the single neural network "snn" model. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 35 table 2 shows the model structure of each neural network "inn" and each neural network "snn". the networks inn and snn are clearly incoordinated and have different architectures. 15 individual neural networks use a logarithmic sigmoid (logistic) transfer function and 14 individual neural networks use a tangential hyperbolic (tanh) transfer function; it is the snn model that brings efficiency, reliability, and robustness the same function, and an exponential transfer function is used in the hidden layer of the neural network in inn29. in the hidden layer, the neural network does not use the sin function. we conclude that two transfer functions (sigmoid and tanh) outperform functions (exponential and sinusoidal), and these results are consistent with those of [26]. thirty individual neural networks inn have enough layer neurons (10 to 25 neurons) to achieve a good approximation. table 2. structures of the optimized nn and snn models iii.4. comparison between bann(stacking 30 nets) and snn (fig. 6a, b, c, and d) show comparisons of experimental and predicted global horizontal solar irradiance with a consistent vector close to the ideal [i.e. = 1 (slope), = 0 (intercept), r = 1 (determination coefficient).)] match the neural network profile of the snn ([α, β, r] = [0.8532, 83.3870, 0.9242] for the validation phase, [α, β, r] = [0.8964, 60, 8747, 0.9446] for the test phase, for bann (stack of 30 networks) ([α, β, r] = [1.0002, -8.8450, 0.9387] for validation stage, [α, β, r] = [1.0060, -9.0290, 0.9580] with in the validation and testing phases) in the validation phase of bann and snn models, the slope α is close to 1, and in the testing phase of the two neural network models, it is near to 1. the intercept β is far from 0 in the validation phase, and in the testing phase, for these neural networks (snn and bann (stacking of 30 networks)), the model snn and bann regression coefficients are generally considered to be excellent (0.90 ≤ r ≤ 1.00). (a) (b) (c) nni neurons number in hidden layer activation function in hidden layer nni neurons number in hidden layer activation function in hidden layer inn1 13 tanh inn16 14 logistic inn2 16 logistic inn17 25 logistic inn3 23 tanh inn18 16 tanh inn4 10 tanh inn19 21 tanh inn5 17 logistic inn20 21 logistic inn6 23 logistic inn21 21 logistic inn7 22 tanh inn22 23 logistic inn8 25 tanh inn23 25 logistic inn9 20 logistic inn24 24 logistic inn10 21 logistic inn25 22 logistic inn11 25 tanh inn26 25 tanh inn12 23 tanh inn27 20 tanh inn13 21 tanh inn28 20 tanh inn14 10 logistic inn29 22 expo inn15 18 logistic inn30 19 tanh abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 36 (d) figure. 6 comparison between experimental vs. calculated global horizontal irradiance(ghi): (a) snn "validation phase", (b) snn "testing phase", (c) bann(stacking of 30 networks) "validation phase", (d) bann(stacking of 30 networks) "testing phase". the two models were compared in terms mentions in section 3 to fit the developed bann (stacked 30 network) model as a reasonable alternative to the snn model (rpd). the equation for this parameter (rpd) is as follows: sd is the standard deviation of the experimental data. the comparison between bann (stacking of 30 networks) and snn models is shown in figure 7. in this comparison, the advantage of the bann (stacking of 30 networks) model is proved. it demonstrates the stability and reliability of neural network models (bann (stacking of 30 networks) and snn). the bann model (stacking of 30 networks) is more accurate than the snn model and can calculate hourly global horizontal radiation (ghi). when applied to an experimental database, this comparison confirms the robust predictions of the bootstrap aggregated neural network. figure. 7 comparison between snn vs. bann(stacking of 30 networks) models in terms of the mae, mpe, rmse, sep, and rpd for testing data iv. conclusion in this research study, two t neural network models (bann(stacking of 30 networks) and snn) have been developed to predict hourly global horizontal irradiance (ghi) in tamanrassetalgeria. the comparison between bann and snn models revealed the superiority of the bann model in predicting the hourly global horizontal irradiance (ghi) as it gave the best performances (the rmse for the test dataset were 71.4998 wh/m 2 for bann, 81.7573 wh/m 2 for snn and mpe for the test dataset were 10.9726 wh/m 2 for bann and 15.4304 wh/m 2 for snn). the bann model has higher precision and can describe the prediction of hourly global horizontal irradiance more accurately compared with the snn model. the bann model will be suitable for predicting global horizontal irradiance for other locations and can also be used to install solar-energy systems. in addition, this model can be applied by researchers in terms of site selection and techno-economic performance evaluation of solar energy applications particularly those relying on photovoltaic technologies. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism acknowledgments the authors gratefully acknowledge the help the university of relizane throughout this project, and the group of laboratory of biomaterials and transport phenomena in the university of medea. references [1] r. t. nand and a. raturi, "feasibility study of a grid connected photovoltaic system for the central region of fiji," appl. sol. energy, vol. 49, no. 2, 2013, pp. 110. [2] c. a. agostini, s. nasirov, and c. silva, "solar pv planning toward sustainable development in chile: challenges and recommendations," j. environ. dev., vol. 25, no. 1, 2016, pp. 25–46. abdennasser dahmani et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 31-37 page 37 [3] m. ouria and h. sevinc, "evaluation of the potential of solar energy utilization in famagusta, cyprus," sustain. cities soc., vol. 37, 2018, pp. 189–202. [4] a. b. stambouli, z. khiat, s. flazi, and y. kitamura, "a review on the renewable energy development in algeria: current perspective, energy scenario and sustainability issues," renewable and sustainable energy reviews, vol. 16, no. 7, 2012, pp. 4445–4460. doi: 10.1016/j.rser.2012.04.031. [5] a. dahmani, y. ammi, and s. hanini, "neural network for prediction solar radiation in relizane region (algeria)-analysis study." [6] s. rehman and m. mohandes, "artificial neural network estimation of global solar radiation using air temperature and relative humidity," energy policy, vol. 36, no. 2, 2008, pp. 571–576. [7] m. benghanem and a. mellit, "radial basis function network-based prediction of global solar radiation data: application for sizing of a stand-alone photovoltaic system at al-madinah, saudi arabia," energy, vol. 35, no. 9, 2010, pp. 3751–3762. doi: 10.1016/j.energy.2010.05.024. [8] h.-y. cheng, c.-c. yu, k.-c. hsu, c.-c. chan, m.-h. tseng, and c.-l. lin, "estimating solar irradiance on tilted surface with arbitrary orientations and tilt angles," energies, vol. 12, no. 8, 2019, pp. 1427. [9] a. koca, h. f. oztop, y. varol, and g. o. koca, "estimation of solar radiation using artificial neural networks with different input parameters for mediterranean region of anatolia in turkey," expert syst. appl., vol. 38, no. 7, 2011, pp. 8756–8762. [10] k. dahmani, r. dizene, g. notton, c. paoli, c. voyant, and m. l. nivet, "estimation of 5-min time-step data of tilted solar global irradiation using ann (artificial neural network) model," energy, vol. 70, 2014, pp. 374–381, doi: 10.1016/j.energy.2014.04.011. [11] m. laidi, s. hanini, a. rezrazi, m. r. yaiche, a. a. el hadj, and f. chellali, "supervised artificial neural network-based method for conversion of solar radiation data (case study: algeria)," theor. appl. climatol., vol. 128, no. 1–2, 2016, pp. 439–451, doi: 10.1007/s00704015-1720-7. [12] z. bounoua, l. o. chahidi, and a. mechaqrane, "estimation of daily global solar radiation using empirical and machine-learning methods: a case study of five moroccan locations," sustain. mater. technol., vol. 28, 2021, p. e00261. [13] e. f. alsina, m. bortolini, m. gamberi, and a. regattieri, "artificial neural network optimization for monthly average daily global solar radiation prediction," energy convers. manag., vol. 120, 2016, pp. 320–329. [14] o. m. oyewola, t. e. patchali, o. o. ajide, s. singh, and o. j. matthew, "global solar radiation predictions in fiji islands based on empirical models," alexandria eng. j., vol. 61, no. 11, nov. 2022, pp. 8555–8571, doi: 10.1016/j.aej.2022.01.065. [15] l. k. hansen and p. salamon, "neural network ensembles," ieee trans. pattern anal. mach. intell., vol. 12, no. 10, 1990, pp. 993–1001. [16] j. zhou, y. wu, g. yan, and z. ma, "solar radiation estimation using artificial neural networks," taiyangneng xuebao/acta energiae solaris sin., vol. 26, no. 4, 2005, pp. 509–512. [17] d. v sridhar, r. c. seagrave, and e. b. bartlett, "process modeling using stacked neural networks," aiche j., vol. 42, no. 9, 1996, pp. 2529–2539. [18] j. zhang, e. b. martin, a. j. morris, and c. kiparissides, "inferential estimation of polymer quality using stacked neural networks," comput. chem. eng., vol. 21, 1997, pp. s1025–s1030. [19] d. h. wolpert, "stacked generalization," neural networks, vol. 5, no. 2, 1992, pp. 241–259. [20] n. bailek et al., "a new empirical model for forecasting the diffuse solar radiation over sahara in the algerian big south," renew. energy, vol. 117, 2018, pp. 530– 537, doi: 10.1016/j.renene.2017.10.081. [21] l. achour, m. bouharkat, o. assas, and o. behar, "hybrid model for estimating monthly global solar radiation for the southern of algeria: (case study: tamanrasset, algeria)," energy, vol. 135, 2017, pp. 526–539, doi: 10.1016/j.energy.2017.06.155. [22] y. ammi, l. khaouane, and s. hanini, "stacked neural networks for predicting the membranes performance by treating the pharmaceutical active compounds," neural comput. appl., vol. 33, no. 19, 2021, pp. 12429–12444, doi: 10.1007/s00521-021-05876-0. [23] m. e. emiroglu, o. bilhan, and o. kisi, "neural networks for estimation of discharge capacity of triangular labyrinth side-weir located on a straight channel," expert syst. appl., vol. 38, no. 1, 2011, pp. 867–874. [24] r. j. tibshirani and b. efron, "an introduction to the bootstrap," monogr. stat. appl. probab., vol. 57, 1993, pp. 1–436. [25] f. n. osuolale and j. zhang, "exergetic optimisation of atmospheric and vacuum distillation system based on bootstrap aggregated neural network models," exergy a better environ. improv. sustain. 1 fundam., 2018, pp. 1033–1046. [26] y. ammi, l. khaouane, and s. hanini, "a model based on bootstrapped neural networks for modeling the removal of organic compounds by nanofiltration and reverse osmosis membranes," arab. j. sci. eng., vol. 43, no. 11, 2018, pp. 6271–6284, doi: 10.1007/s13369-018-3484-8. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 52-63 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 52 optimal controller design and dynamic performance enhancement of high step-up non-isolated dc-dc converter for electric vehicle charging applications rajanand patnaik narasipuram 1, 2* , narendra kumar muthukuri 1, 2 , subbarao mopidevi 2 1 eaton india innovation center, vehicle group, pune, india 2 laboratory of electric vehicles-ev lab, department of electrical & electronics engineering, vignan’s foundation for science technology and research, india * corresponding author e-mail: rajanand.ee@gmail.com abstract – ideally, traditional boost converters can achieve a high conversion ratio with a highduty cycle. but, in regular practice, due to low conversion efficiency, rr reverse-recovery, and emi (electromagnetic interference) problems, the high voltage gain cannot be performed, whereas cibc (coupled inductor-based converters) can achieve high voltage gain by re-adjusting the turn ratios. even though the leakage inductor of the ci (coupled inductor) makes some problems like voltage spikes on the main connectivity switch, high power dissipation, and voltage pressure can be minimized by voltage clamp. in this paper, a non-isolated dc-dc converter with high voltage gain is demonstrated with 3 diodes, 3 capacitors, 1-inductor, and a coupled inductor. the main inductor is connected to the input to decrease the current ripple. the voltage stress at main switch s is shared by diode d1 and capacitor c1 and the main switch is turned on under zero current, hence it turns to low switching losses. this paper proposes two controllers like proportionalintegral (pi) controller and fuzzy logic (flc) for dc-dc converter. furthermore, it demonstrates the operation, design, mathematical analysis, and performance of dc-dc converter using controllers for efficient operation of the system is performed using simulations in matlab 2012b. keywords: ev, electric vehicles, proportional integral, pi, on-board charger, fuzzy logic, fl, dc-dc received: 08/11/2022 – revised 28/11/2022 – accepted: 05/12/2022 i. introduction generally, environmental problems are caused by using non-renewable energy resources like fossil fuels, coal energies, etc. so by using pv, wind, and tidal energy the environmental problems are reduced. this energy's applied at the input side or distribution generation (dg) systems. due to the climatic effects the voltage gain will be reduced [1-3]. it's the major drawback of using renewable energy sources. moreover, it's an effective method, by using pv panels the number of pv cells is connected in series so that output voltage across the pv panel will be improved. a dark effect cannot be obtained [4-5]. the main advantages are a large transmission ratio, excessive voltage gain, and small size [6-8]. input current ripples are the main consideration by using photo voltaic and fuel cell applications. moreover, similar advantages are getting by using an ideal converter but during the practical conditions due to less transmission efficiency, reverse recovery, and emi problems high voltage gain will not achieve [9-10], [28]. however, many converters with different new techniques have been introduced for getting high voltage gain and high transmission efficiency [11], [24]. rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 53 switched capacitors [11-13] and voltage lift techniques [14-16] have been introduced for improving the voltage gain. high current ripples at the input side are the main disadvantage so it reduces the performance and efficiency of the converter. recently there are many nonisolated coupled inductors-based converter are presented with different voltage clamping circuits [19-25]. they have the merit of high voltage gain; recovery of the leakage inductor's energy and low switching voltage stress are the main features and have the main drawback of high input current ripple. this makes problems in tracking the maximum power point (mpp) of pv panels. the proposed converter figure 1 has excessive voltage gain by maintaining the required turn ratio. moreover, using a leakage inductor across the coupled inductor [17-19] produces voltage spikes across the main switch so it leads to more power discharge. by providing voltage clamping circuits the power stored in the leakage inductor will be recovered. so, it’s very important to provide voltage clamping circuits across the main switch s. figure. 1. schematic of non-isolated dc-dc converter the inductor is connected in series to the input side for minimizing the ripple currents at the input side. the voltage stress across switch s is shared by diode d1 and capacitor c1 and the main switch is turned on under zero current switching and conduction losses also decreased. ii. operating principle and analysis operating principle and analysis, consider to 1) all capacitors c and inductors l & lm are taken large beyond any ripple voltages and currents, 2) only leakage inductance ilk is considered. ii.1. ccm analysis of the non-isolated dc-dc converter it consists of 5 time intervals in a single switching period. figure. ii to figure. vii shows a flow of the current path in ccm mode. the ns current of the nonisolated coupled inductor is: (1) there is no simultaneous change in il & ils, the study state performance is given below. mode i [t0<t<t1]: s and d3 are in conduction. in this period ilk is increased & equal to ilm. this mode of operation ends when ilk equals ilm. the equation of ilk, (2) the operating period of this mode is very small, where the value of lk is less and vlk is high. l becomes magnetized due to v1, ending of this first mode, id3 becomes zero due to the secondary current of the inductor. using kcl, is can take as (3) figure 2. first mode of interval [to-t1] mode ii [t1<t<t2]: in this period the switch is still on. the ilk improved and became more than then ilm. the ilk equation is written as follows: , (4) d2 on due to ns current. thus, the d2 current improved from zero. due to ns current, the c3 is charged .c1 energy is discharged through the coupled inductor and c2. l is energized because of v1. this period ends when s is off using kvl the equations can be written as: (5) (6) (7) figure 3 shows the second mode of the interval [t1-t2]. where n is the turns ratio of coupled inductor = ns/np rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 54 figure 3. second mode of interval [t1-t2] mode iii [t2<t<t3]: switch s is off, il current flows through d1 and makes it conduction. d1 and d2 currents are written as: (8) (9) the ilk is de-energized continuously until its equals the ilm. at this time id2 becomes zero. ilk can be expressed as follows: (10) according to the above equation, less value of leakage inductor and high –ve voltage causes a high current slope. operating time is also small in this mode. due to the de-energizing of inductors l and v1 the c1 is charged. this mode is when d2 off. figure 4 shows the third mode of the interval [t2-t3] figure 4. third mode of the interval [t2-t3] mode iv [t3<t<t4]: the c1 is charged by v1 and storage energy in l. the leakage inductor voltage becomes charged in this mode. its voltage is written as follows: (11) where d4ts is the time interval of this period. c0 is energized due to ns current. d1 current will be written as: (12) this period ends when d1 current becomes zero. however, the slope of ilm is less than ilk, according to equation (1), the slop id3 is +ve. in this mode the vl, vlm, can be expressed as: (13) (14) (15) figure 5 shows the fourth mode of the interval [t3t4]. figure 5. fourth mode of the interval [t3-t4] mode v [t4<t<t5]: d3 is still conducting in this period. due to id3, the c0 is energized. the id3 is expressed as: (16) the diode d3 and the ilk slope calculate on the il, ilm slope. eliminating the il, ilm ripples take the slope of id3 and the ilk tends to zero. then vlk will become zero. as in this equation, zero currents are possible when s becomes conduction like the beginning mode. in zcs condition the switch is off. from kvl the voltage equation is written as: (17) (18) vlk2 & vlk4 calculated from the ilk slope in periods ii &iv. c2 and c3 are in series with ns and np, ilk and ilm avg. currents are zero, according to amp-sec balance law. considering the balancing law in c1, c2 &c3, and c0 it can be justified that the average value of the diode current is equal to the io. so, the following equation can be obtained from figure 2, (19) rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 55 (20) so, the ripples of the l & lm are also not considered in the vgain calculation. the istress of the s and d1 can be getting as given below: (21) by not considering the 3 rd mode using this equation, the 4 th time interval can be obtained as ⇒ (22) due to (4) and (19) equations the voltage vlk2 can be found as: (23) where, fswitch and rl, respectively. join volt-sec balance basis on the lk by neglecting modes 1&3, the following equation is obtained. (24) applying volt-sec balance basis on the inductors the output is: (25) (26) (27) m= (28) as the above expression depends on switching frequency, rl, and ilk value the voltage gain of this new converter is controlled. whatever, it does not contain significant change on the vgain. the change of q on the voltage gain is shown in fig iv and it's nearly low. for example, fs=30 khz, lk=5uh, rl=200 & d=0.5, the q factor value is about 0.96. the actual vgain is 96% of the conventional vgain. the vgain of the new converter is (29) figure 6 shows the fifth mode of the interval [t5-t6] and figure 7 presents the current waveforms for the new converter in ccm mode. figure 6. fifth mode of the interval [t5-t6] figure 7. current waveforms for new converter in ccm mode b. boundary condition mode (bcm) in this mode, at ending of the switching period currents of l and lm become equal. equations can be written as follows (30) rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 56 (31) (32) operating ccm mode in the new converter, coupled inductor lm should be in ccm. since ns and np of the coupled inductor are series to the c2 and c3 according to the amp-sec balance law, avg ilk & ilm is zero. at the end of this switching period, d3 current reaches zero in ccm. in bcm, d3 becomes zero at end of the switching period. so the value of il, ilk & ilm becomes zero. at the final end of this operation -the ilm value is nearly equal to il-0.5δil. if the lm is in ccm, its maximum value of current is to be semi of its ripple. it implies the lm is in ccm. (33) for operating the converter in ccm, the lmin must be calculated. it operates in ccm when the normal value of inductor current is better than the semi of its ripple, using eqn (31) lmin can be obtained as (34) figure 8 shows the current waveforms in bcm. figure 8. current waveforms in bcm iii. design of the switching components voltage and current stress are obtained by selecting the appropriate semiconductors of the new converter, according to the working principle the stress voltages of diodes and switches are formulated as. (35) (36) the d2(peak) current is obtained from equation (19). the value of speak and diode d1(peak) currents is as follows: (37) based on fig. iii and taking equation (37), the current value of d3(peak) can be written as given below: (38) by neglect, the esr of the co, the vo ripple of the new converter can be given as follow (39) according to [1], [18], [28], by taking into consideration a certain ripple value, co size is designed using (39). then, by taking the esr of the selected capacitor, the voltage ripple is less than the desired voltage ripple. the peak-peak voltage across the esr of the capacitor co can be taken as (40) iv. modelling of pi controller the enhanced pi controller is the commonly used control technique in electric vehicle applications. figure 9 demonstrates the block diagram of the enhanced pi control technique rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 57 figure 9. block diagram of proposed pi controller for converter the error signal e(s) is sent to the pi controller i.e kp and output control signal q(s) of the enhanced pi controller of the proposed system is: v. modelling of flc the development of flc is easier and provides effective flexibility for the sudden change in output loads. in addition, it provides effective and smarter dynamic responses and is very reliable in operation. the flc set rules are defined below: 1. gaussian method. 2. sigmoidal method. 3. trapezoidal method. 4. π method. 5. triangular method. 6. bell method etc. figure 9a shows the block diagram of the proposed fl controller for the converter. figure 9a. block diagram of proposed fl controller for converter 5.1 fuzzification the process of defining the fuzzification matches the input data with the predefined conditions with set rules to examine how well the condition of each rule matches that particular input instance. it gives a mathematical way to demonstrate each input and output variable in traditional language. figures 9b, 9c, and 9d show the fuzzy membership function of the error input variable with 7 linguistics. figure 9b. membership function for single input figure 9c. membership functions error for change in error figure 9d. membership function for control signal vi. simulation results the whole analysis is done in matlab/simulink, and analysis takes part in three cases which gives an open loop of dc-dc converter in case i, pv fed dc-dc converter with pi and fl controllers in cases 2 and 3 respectively. table 1 shows the specifications of the pv module and dc-dc converter. rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 58 table 1. circuit parameters specification parameters pv parameters voc 27v isc 3.8a parasitic resistor (ro) 1ω parasitic capacitor (co) 0.1mϝ dc-dc converter parameters vin 27v vout 290v capacitors c1, c2, c3, c4=47μϝ c0 =180μϝ inductors 320μh coupled-inductor lm=100μh n=2.1 switching frequency 30khz case (i): open-loop simulation of new non-isolated coupled inductor-based high step-up dc-dc converter designed for 225 watts of power and 27 input voltages achieving a high dc voltage of nearly 300 volts having less duty cycle 0.6. the conventional boost converter can achieve the same output voltage, but it requires 0.94 duty cycle for 300 volts. figure 10 shows the simulink model of coupled inductor-based dc to dc converter figure 10. simulink model of coupled inductor-based dc to dc converter the output voltage response of the new converter is shown in figure 10a. it’s clear that the output voltage is 300v at 60% duty cycle operates 36% less than conventional converter. figure 10a. output voltage and output current response of coupled inductor-based dc-dc converter figure 10b shows the inductor and diode current responses of coupled inductor converter. figure 10b. inductor and diode current responses of coupled inductor converter figure 10c shows the capacitor voltage responses of coupled inductor converter. rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 59 figure 10c. capacitor voltage responses of coupled inductor converter figure 10d shows the switch voltage responses (diodes & main switch) of coupled inductor converter. figure 10d. switch voltage responses (diodes & main switch) of coupled inductor converter figure 6f shows the comparison of the voltage gains and switch stresses of the main switch for coupled inductor-based converter and boost converter. from the graphs, it is identified that the gain values of the coupled inductor-based converter are more than the boost converter for the same duty cycles. also, the switch stresses are less for the coupled inductorbased converter compared to the boost converter. thus, the coupled inductor-based converter is superior in operation to the boost converter and in further sections, the dynamic performance of this converter is verified for the load changes using the pi controller and fuzzy logic controller. figure 10e. comparisons of voltage gains and switch stress of coupled inductor-based converter and boost converter rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 60 case (ii): closed-loop control simulation of picontrolled coupled inductor based dc to dc converter figure 11a gives the simulation diagram of the proposed converter at an input voltage is 27 v, load current varies from 0.35 to 0.72 a and figure 11b shows the voltage and current responses of dc-dc converter using a pi controller. figure 11a. simulink model of pi-controlled coupled inductor based dc to dc converter figure 11b. voltage and current responses of dc-dc converter using pi controller case (ii): closed-loop control simulation of fuzzy controlled coupled inductor-based dc to dc converter the input voltage is 27 v, the output voltage 290v, and the load current are from 0.35 a to 0.72a with the fl controller. figure 12a gives the simulink model of fuzzy controlled coupled inductor based dc to dc converter and figure 12b shows the output voltage and current responses of flc coupled inductor converter for a sudden load change at 0.2 sec from 112.5w to 225w figure 12a. simulink model of fuzzy controlled coupled inductor based dc to dc converter figure 12b. output voltage and current responses of flc coupled inductor converter for a sudden load change at 0.2 sec from 112.5w to 225w vii. comparison study comparison for both pi and fuzzy controlled coupled inductor based dc to dc converter. figure 13a presents the output voltage responses of pi & fuzzy controlled coupled inductor converter for a sudden load change at 0.2 sec from 112.5w to 225w rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 61 figure 13a. output voltage responses of pi & fuzzy controlled coupled inductor converter for a sudden load change at 0.2 sec from 112.5w to 225w figure 13b shows the simulink model of the coupled inductor with fuzzy logic controller maintaining the stiff output voltage of 300v even under the changes in the input voltage from 27v to 15v. figure 13b. simulink diagram of a coupled inductor with voltage variations using a fuzzy logic controller figure 13c shows the output voltage response of 300v for the converter with fuzzy controller under the changes in the input voltage from 27v to 15v at 0.2 sec. figure 13c. output voltage response for input voltage variations applied at 0.2 sec from 27v to 15v. figure 13d shows the comparison for both pi and fuzzy controller when sudden input voltage variations. figure 13d. comparison for both pi and fuzzy controller when sudden input voltage variations thus, the fuzzy logic controller works effectively for the range of voltage variations at the input side from 15v to 27v and delivers a stiff voltage of 300v. . (41) viii. conclusion a non-isolated dc-dc converter with high voltage gain is designed and simulated in matlab r2012b version. the same output voltage of 300v is achieved for a very smaller duty ratio of 0.65 when compared with the conventional boost converter. it comprises 3-diodes, 3capacitors, 1-inductor, and a coupled inductor are utilized. the pressures switch s is reduced by utilizing the clamping circuit formed with diode d1 and capacitor c1. the dynamic response of the converter is analyzed for the disturbances on the load side from 112.5w to 225w at 0.2 sec and the output voltage is maintained constant by using the pi and flc. the pi-controlled converter settles to the desired voltage with a dip of 1.2v at the disturbance point (0.2sec), whereas the fuzzy logiccontrolled converter gives a stiff voltage of 300v without any dip. also, the fuzzy logic controller is verified for the disturbances at the input side for a range of 15v to the 27v input voltage. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 62 references [1] h. ardi, a. ajami, f. kardan and s. nikpour, “analysis and implementation of a non-isolated bidirectional dc-dc converter with high voltage gain,” ieee trans. ind. electron., early access. doi: 10.1109/tie.2016.2552139 [2] h. ardi, r. reza ahrabi, s. najafi ravandanagh, “non-isolated bidirectional dc-dc converter analysis and implementation,” iet power electron., vol. 5, no. 12, 2014, pp.3033-3044. [3] s. m. chen, t. j. liang, l. s. yang, and j. f. chen, “a boost converter with capacitor multiplier and coupled inductor for ac module applications,” ieee trans. ind. electron., vol. 60, no. 4, 2013, pp.1503-1511. [4] j. h. lee, t. j. liang, and j. f. chen, “isolated coupled-inductor-integrated dc–dc converter with non-dissipative snubber for solar energy applications,” ieee trans. ind. electron., vol. 61, no. 7, 2014, pp. 3337–3348. [5] r. b. mohammad, h. ardi, r. alizadeh, a. farakhor, “non-isolated multi-input–single-output dc/dc converter for photovoltaic power generation systems,” iet power electron., vol. 7, no. 11, 2014, pp. 2806–2816. [6] y. zhao, w. li, y. deng, and x. he, “high step-up boost converter with passive lossless clamp circuit for non-isolated high step-up applications,” iet power electron., vol. 4, no. 8, 2011, pp. 851–859. [7] y. p. hsieh, j. f. chen, t. j. liang and l. s. yang, “a novel high stepup dc–dc converter for a microgrid system,” ieee trans. power electron., vol. 26, no. 4, 2011, pp.11271136. [8] r. j. wai, c. y. lin, c. y. lin, r. y. duan, and y. r. chang, “high efficiency power conversion system for kilowatt-level stand-alone generation unit with low input voltage,” ieee trans. ind. electron., vol. 55, no. 10, 2008, pp. 3702–3714. [9] m. subbarao, ch. sai babu, s. satyanarayana, “digital variable switching frequency controlled integrated power converter for class c and class d appliances”, int. j. power electronics, vol. 11, no. 3, 2020. doi: 10.1504/ijpelec.2020.10027750 [10] s. mopidevi, rp. narasipuram, sr. aemalla, and h. rajan, “e-mobility: impacts and analysis of future transportation electrification market in economic, renewable energy and infrastructure perspective”, int. j. powertrains, vol. 11, nos. 2/3, 2022, pp.264–284. https://doi.org/10.1504/ijpt.2022.124752 [11] l. s. yang, t. j. liang, and j. f. chen, “transformerless dc–dc converter with high voltage gain,” ieee trans. ind. electron., vol. 56, no. 8, 2009, pp. 3144– 3152. doi: 10.1109/tie.2009.2022512 [12] t. j. liang, j. h. lee, s. m. chen, j. f. chen, and l. s. yang, “novel isolated high-step-up dc–dc converter with voltage lift,” ieee trans. ind. electron., vol. 60, no. 4, 2013, pp. 1483–1491. [13] f. l. luo and h. ye, “hybrid split capacitors and split inductors applied in positive output super-lift luo-converters,” iet power electron., vol. 6, no. 9, 2013, pp. 1759–1768. [14] rajanand patnaik narasipuram, “modelling and simulation of automatic controlled solar input single switch high step-up dc-dc converter with less duty ratio”, int. j. industrial electronics and drives, vol. 3, no. 4, 2017. [15] rajanand patnaik narasipuram, subbarao mopidevi, a technological overview & design considerations for developing electric vehicle charging stations, journal of energy storage, volume 43, 2021, 103225. [16] rajanand patnaik narasipuram, “analysis, identification and design of robust control techniques for ultra-lift luo dc-dc converter powered by fuel cell”, int. j. computer aided engineering and technology, vol. 14, no. 1, 2021, pp.102–129. [17] rp. narasipuram, c. somu, rt. yadlapalli, ls. simhadri, “ efficiency analysis of maximum power point tracking techniques for photovoltaic systems under variable conditions”, int. j. innovative computing and applications, vol. 9, no. 4, 2018, pp.230–240. [18] s. chaitanya, n. r. patnaik and c. b. a. raju, "a novel transformerless asymmetrical fifteen level inverter topology for renewable energy applications," 2018 fourth international conference on advances in electrical, electronics, information, communication and bio-informatics (aeeicb), 2018. [19] n. rajanand patnaik, y. ravindranath tagore, "design and evaluation of puc (packed u cell) topology at different levels & loads in terms of thd," in european journal of advances in engineering and technology, vol. 3, no. 9, 2016, pp. 33-43. [20] n. rajanand patnaik, y. r. tagore and s. chaitanya, "advanced seven level transformer-less multilevel inverter topology for pv application," 2017 third international conference on advances in electrical, electronics, information, communication and bioinformatics (aeeicb), chennai, 2017, pp. 111-116. [21] rp. narasipuram, “optimal design and analysis of hybrid photovoltaic-fuel cell power generation system for an advanced converter technologies”, int. j. mathematical modelling and numerical optimisation, vol. 8, no. 3, 2018, pp.245–276. [22] m. subbarao, ch. sai babu, s. satyanarayana, “digital fuzzy current mode controlled integrated pfc converter with external ramp compensation”, journal of circuits, systems, and computers (jcsc), issn:1793-6454, vol. 27, no. 9, 2018, p.p.18501471-23. https://doi.org/10.1142/s0218126618501475 [23] m. subbarao, ch. sai babu, s. satyanarayana," design and analysis of variable switching frequency controlled integrated switched mode power converter https://doi.org/10.1504/ijpt.2022.124752 rajanand patniak. n et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 52-63 page 63 for class c & class d appliances", ain shams eng jol., vol. 9, 2018, pp 2849–2858. https://doi.org/10.1016/j.asej.2017.10.008 [24] n. k. muthukuri, s. mopidevi, “analysis of a modified switching pattern for packed u cell-15 inverter topology with advanced level shift carrier pulse width modulation techniques”, electrica, vol. 21, no. 2, 2021, pp. 272-282. doi: 10.5152/electrica.2021.20082 [25] n. k. muthukuri and s. mopidevi, "optimal controller design of puc-15 mli topology for smart grid applications with reduced power components," 2022 international conference on smart technologies and systems for next generation computing (icstsn), 2022, pp. 1-4. doi: 10.1109/icstsn53084.2022.9761358 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 26-32 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 26 effective modeling of photovoltaic modules using sailfish optimizer m. b. danoune 1* , a. djafour 1 , y. rehouma 1 , a. degla 2 , z. driss 3 1 faculté des sciences appliquées laboratoire lage univirsité d’ouargla, ouargla 30000, algeria 2 centre de développement des energies renouvelables–cder., 62 route de l’observatoire, algeria 3 laboratory of electro-mechanic systems, national school of engineers of sfax, university of sfax, tunisia * corresponding author e-mail: danoune.mohammed.bilal@gmail.com abstract – the current study proposes a novel meta-heuristic technique called sailfish optimizer (sfo) to design reliable photovoltaic (pv) modeling models. unlike others, the proposed technique employs two populations (prey and predator) instead of one to effectively reach the desired solution. this unique propriety can substantially augment the probability of locating the global optimum as well as accelerating the search process. moreover, to show the efficacy of the algorithm, the results are compared with some literature techniques such as salp-swarmoptimizer (ssa), whale optimization (woa), artificial-bee-colony (abc), and particle-swarm optimization (pso) methods. eventually, the proposed sfo algorithm demonstrated a remarkable amelioration in terms of accuracy with root-mean-square-error of 13e-3 a. keywords: parameters extraction, photovoltaic cells, double-diode model, meta-heuristic algorithms, sailfish optimizer. received: 12/05/2022 – revised 05/06/2022 – accepted: 22/06/2022 i. introduction in the last decades, fossil energy has been consumed tremendously due to human being activities. this consumption has led to problems of energy shortage as well as an increase in environmental concerns. experts at the paris conference (2015) have declared that the earth's temperature has reached a critical point [1], and to overcome this issue, the world governments have decided to develop clear and practical policies that respect the ecological balance and promote sustainable development [2]. today, solar pv energy is viewed as one of the strategic sources that are able to fulfill present and future energy needs and mitigate environmental risks simultaneously [3, 4]. pv generators convert directly solar irradiance into useful power. voltage is produced across the pv cell terminals when sunlight reaches the n-layer (negative) of the pv cell. however, pv cells generate unregulated voltage. in order to design a robust control system for pv generators with constant output voltage, good performance analysis using accurate modeling and simulation is required. in this context, various mathematical models have been developed in the literature to simulate the real pv cell's behavior including single-diode (sd) [5], double-diode (dd) [6], and threediode models [7]. among all, the dd model is the noteworthy one due to its great balance between accuracy and simplicity in predicting pv cell output characteristics. before modeling the pv cells using dd model, there are a number of unknown parameters that need to be determined first. researchers have used certain analytical correlations to address this problem for instance: k. et-torabi method [8], villalva algotithm [9], mailto:danoune.mohammed.bilal@gmail.com m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 27 celik approach and others [10]. however, the abovementioned methods are time-consuming, and they have been developed based on many simplifications, which reflect negatively on the quality of the results. for these reasons, researchers have developed another way to treat the system as an optimization problem. guided by this idea, meta-heuristics optimization algorithms are intensively employed to eliminate the drawbacks conducted by analytic approaches and extract the best parameters [11]. meta-heuristic algorithms are random search and population-based methods. they were inspired from biological or physical phenomena. they have demonstrated their effectiveness in many engineering applications including parameters identification. a survey in the literature revealed many techniques have been applied in pv cell parameters tasks. the most recent studies, which proposed the salp swarm theory to determine the parameters of the dual diode model. similarly, for another research group who presented the butterfly flame optimization algorithm to extract the parameters of multicrystalline solar cells with special emphasis on the three-diode model [12,13]. as an extreme case, one study tested the performance of the bacterial foraging algorithm in shedding parameters of sd-dd models using only the three points highlighted in the manufacturer's nameplate [14-16]. from the previous review, we can see that a variety of meta-heuristic methods with different levels of accuracy have been applied. however, this domain remains hot and still evolving over time. in other word, there still chances to be conducted to find new improvements. for these reasons, the present paper intends to apply a new met-heuristic optimization algorithm for determining the parameters of pv cells with high accuracy. to examine the precision, robustness, and efficacy of the suggested algorithm, the results are compared with some state-ofart methods namely ssa [17], woa [18, 19], abc [20], and pso [21, 22]. identifying the unknown parameters of photovoltaic (pv) models is extremely important to accurately assess the behavior of the device. many methods are used in this context, however, majority of them struggle to find the true parameters due to the nonlinear and complex nature of the mathematical model. this study presents a novel approach based on metaheuristics optimization methods to solve this still complex engineering problem. the core goal of the work is design a high quality pv modeling models that are able to produce estimations close the real ones. ii. pv cells modeling pv cells behavior is represented in double diode model by a photoelectric current source iph connected in parallel with a p–n junction diode. a second diode is added to portray the recombination loss in the depletion region [6]. moreover, tow resistances rs and rp are incorporated to represent the cell ohmic losses (rs) due to wiring contacts, and rp leakage current resistance in the p–n junction [23]: figure 1. double diode model the overall output current is given in eq. (1) with the meaning of each element in table 1: )1( rp irsv 1 vtn2 irsv expis21 vtn1 irsv expis1iphi                                  it is worth mentioning that eq. (1) includes seven unknown parameters i.e., iph, is1, is2, n1 , n2, rs and rp, which need to be determined. this step is described below. table.1. parameters of dd model [23] symbol name unit v cells output voltage v vt thermal voltage v i cells output current a iph photo-current a is1, is2 diode reverse saturation current a ns number of cells in series τ cell temperature k q electron charge (q=1.60217646e-19) c k boltzmann constant (k=1.3806503e-23) j/k n1,n2 diode ideality factor rs series resistance ω rp parallel resistance ω m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 28 iii. objective function the mathematical model is said to be accurate if the experimental and estimated i-v data match with each other, meaning that the difference between them is neglegable. based on the above, the root-mean-squareerror between the experimental and estimated i-v points given in eq. (1) is generaly considered as the objective function (of). in eq. (2), all the parameters are known except iph, is1 is2 ,n1, n2,rs,and rp, since iest is as a function of the stated parameters. these parameters are limites by bounderies as depicted in table 2. the ultimate goal now is to adjust the values of the parameters randomly based on the algorithm until good accordance is achieved. (2) n is the samples number. iexp and iest are the experimental and estimated current of the cell panel respectively. table.2. parameters variation range iv. sailfish optimizer algorithm (sfo) sfo is a population-based search method. it was proposed in 2019 by shadravan [24]. the method mimics the foraging behavior of a sailfish school. unlike other faunas, sailfish uses less effort and saves more energy while hunting its prey. figure 2. sailfish hunting mechnism the foraging behavior of the sailfish optimizer is conducted by the following steps: iv.1. elitism in random search algorithms, the best solution can be missed while adjusting the search agent position. here, the elitism step is employed to copy the fittest particle (best solution) into the future generation. in each iteration, the best sailfish position is taken as elite. as a consequence of a continuous attack the sardines shall be injured by slashing motion. the position of injured sardine in each iteration is saved and selected as the best target to collaborate in hunting with the sailfish. iv.2. attack-alternation strategy sailfish work to herd and injury the prey. this behavior allows sailfish to adjust their positions according to the location of the other hunters. it was observed that the search agents provide the exploration phase by searching a large section of the search space to discover the promising solutions that are not refined before. the sailfish attacks in all orientations and within a shrinkingcircle. this mechnism is simulated using eq. (3) [24]: (3) λ = 2 x rand(0.1) x pd -pd (4) where x i new_s and x i injued_s are the position of the elite sailfish and injured sardine respectively. rand (0, 1) is a random number in (0-1), is a random coefficient that mimics the sailfish divergence from each-other and convergence of it from the prey. pd signifies the prey density, a correlation is given in eq .(5) to calculate pd by combining both the number of sailfish nsf and sardines ns. practically, the sardines number nsf is larger than sailfish nsf, therefore, nsf is taken as a fraction or percentage pp of ns . nsf = pp . ns (6) in this paper pp=0.3, but make sure that nsf is always an integer. m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 29 iv.3. hunting and catching prey during hunting procedure, sailfish’s bills hits and injury a large number of sardines in the school. the power of sailfish’s will be decreased over the time. also, due to frequent attacks, the power of the prey will reduce as well. power of this reduction could give information to the prey about the sailfish location to escape from it. clearly, some sardines will be hit by sailfish’s bill and quickly be captured. whereas, other sardines will be forced to adjust their positions according to the current best sailfish x i elite_sf . the new position of the ith sardine x i old_s is given as: x i new_s = rand (0.1) (x i elite_sf – x i old_s + ap) (7) where x i old_s and x i new_s are the previous and updated sardines positions successively. ap is the sailfish’s attack power at each iteration. ap= a [1(2 it . 𝜀)] (8) 𝐴 and 𝜀 are coefficients (a=4, 𝜀 =0 .001 ) and it is the itération number. notice that ap is linearly decreasing number from a to 0 to simulate the reducing sailfish attack due to sardine’s maneuverability [24]. ap parameter can help in selecting the sardines α and that have to adjust their positions and finding the remaining sardines variable β: α = ns . ap (9) β = di . ap (10) where ns is the sardines number in each cycle and is the variables number at i th iteration. according to ap, if sailfish intensity is low (ap < 0.5) just α sardines will update their positions and 𝛽 is the variables number. else (ap ≥ 0.5) the position of all sardines will be updated. a pseudo-code is given to implement the method [24]. figure 3. flowchart of the sailfish optimizer go back to elite sailfish display , , , , , & from vector of elite sailfish stop compute the fitness of all sardines by eq (2) replace the sailfish with injured sardine, if there is a better solution in sardine population remove the hunted sardine from population adjust the best sailfish and best sardine set it=it+1 end while adjust the position of all sardines by eq(7) end if compute by eqs(9)-(10) select a set of sardines based on adjust the position of the selected sardinesby eq(7) if ap yes no adjust the position of sailfish byeq (3) compute ap by eq(8) end for start set a=4 and set it=0 while it max it for k=1:ns yes no m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 30 v. experiment and results analysis v.1. experimental steps to identify the cell parameters, a number of experiments were performed at the laboratory first. an industrial va200 solar analyzer was utilized to extract the experimental i-v curves automatically. the remaining equipment connected to the system is shown in figure 4. figure 4. experiments platform moreover, for a meaningful investigation, the results of the suggested algorithm were compared with some stateof-the-art methods namely ssa [17], woa [18, 19], abc [20], and pso [21, 22]. named algorithms were used in many research papers for extracting the pv cell parameters. the controlling coefficients of them are fixed as original papers recommend. additionally, for a fair comparison, agents number was set equal to 30 particles in each algorithm. the results were executed for 100 independent runs and the best parameters are taken as a desired solution. v.2. case study 1 (i-v characteristics) it is worthy to remember that there are 7 unknown parameters that have to be optimized. the extracted best parameters are displayed in table 3. they have been fedback to the model to estimate i-v curve at g = 735 w/m 2 and t = 48 °c. figure 5 represents the plotted i-v curves for all algorithms. 0 10 20 30 0 0.5 1 1.5 2 2.5 3 3.5 4 voltage[v] c u r r e n t [ a ] me as ure d sfa sa a woa a bc pso 31 32 33 3.3 3.4 3.5 figure 5. i-v curves at g=735w/m2 & t=48°c it can be observed that around the short circuit and open voltage points all the methods are showing good accordance. however, around the maximum power point (mmp) some differences are detected. a closer view shows that the suggested method attain the highest accuracy, meaning that the global optimum (go) is well explored by sfo. in contrast, the results of other approaches are less accordance and they failed to track the go. the results in table iii validate these observations. sfo placed in first position with rmse of 13.2 e-3 followed by woa which has ranked in second position with rmse of 19.9e-3 a, ssa has positioned third with rmse of 24.3e-3 a. abc & pso methods exhibit the lowest precision with rmse of 101.6e-3a and 103.9e-3a respectively. table 3. results of the simulation m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 31 v.3. case study 1 (i-v characteristics) figure 6 represents the objective function evolution over the course of iterations for all tested algorithms. it is apparent that the suggested method has shown rapid convergence compared to others. 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 iterations o b j e c t i v e f u n c t i o n sfo ssa woa pso abc figure 6. convergence speed the desired solution has been reached only in 43 th iteration. furthermore, ssa and woa have approximately the same inclination curve; however, ssa has hit the target on 78 th iteration as second place, and woa in 146 th iteration in third place. abc-pso methods showed some delay while settling down. but, unfortunately they have converged to the local minimium without escaping from it. based on iterations number, abc (iteration of 254 th ), and pso (iteration of 186 th ) algorithms were ranked in last positions. these results signify that the suggested algorithm has high potential in explored the search area in very short-time. the explanation for the rapidity of the method is that the sfa employs two populations (population of prey and predator) instead of one to search for the solution. the school of sardines also assists the predators in searching process. in other words, the randomly motion of sardines itself can separate the weakest particles in the school and then get easily captured by sailfish. this unique hunting strategy can dramatically accelerate the convergence speed of the method. however, this behavior is not observed in the other methods. vi. conclusion accurate pv cells parameters identification has a significant impact on predicting the power of the pv installation. thus, the demand for more accuracy is always required. in this study, a novel swarm intelligence optimization algorithm called sailfish optimizer is applied for the first time to model the outputs of pv cells. the idea was to determine the optimal unknown parameters by minimizing the error between the experimental characteristic curves with the estimated ones. the main difference between this applied algorithm and others is its efficacy in finding the optimal parameters with high accuracy and noticeable rapidity. a comparison was undertaken with several state-of-the-art meta-heuristic algorithms to show the effectiveness of the proposed algorithm. the main outcomes of the study can be pointed out as follows:  the performance of the sailfish optimizer is tested in this study to solve modeling problems of pv generators.  an accurate pv model for sw 175 polycrystalline pv panel has been established.  among many techniques, the sailfish optimizer produced the highest accuracy with rmse of 13.2 e-3.  the study revealed that the proposed method has a great potential to avoid local optimum and has converged rapidly to the desired solution with minimum iterations (i.e., 43 iterations). finally, from this work, it can be stated that the sailfish optimizer is a powerful technique. its results were motivating and even excited us to perform other studies to test the efficacy of this method in addressing other engineering problems for instance modeling fuel cell generators. declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] christopher j. rhodes, " the 2015 paris climate change conference: cop21," science progress. vol 99, 2016, pp. 97–104. [2] m.b.danoune, a.djafour, yuewang, a.gougui, " the whale optimization algorithm for efficient pem fuel cells modeling,” international journal of hydrogen energy. vol 46, n°59, 2021, pp. 37599-37611. https://www.sciencedirect.com/science/article/abs/pii/s036031992101017x#! https://www.sciencedirect.com/science/article/abs/pii/s036031992101017x#! https://www.sciencedirect.com/science/article/abs/pii/s036031992101017x#! https://www.sciencedirect.com/science/article/abs/pii/s036031992101017x#! https://scholar.google.fr/scholar?oi=bibs&cluster=6269934639007017158&btni=1&hl=fr https://scholar.google.fr/scholar?oi=bibs&cluster=6269934639007017158&btni=1&hl=fr https://scholar.google.fr/scholar?oi=bibs&cluster=6269934639007017158&btni=1&hl=fr m. b. danoune1et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 26-32 page 32 [3] n khelfaoui, a djafour, c ghenai, i laib, mb danoune, a gougui, "experimental investigation of solar hydrogen production pv/pem electrolyser performance in the algerian sahara regions,” international journal of hydrogen energy. vol 46, n°59, 2021, pp. 30524-30538. https://doi.org/10.1016/j.ijhydene.2020.11.193 [4] a gougui, a djafour, mb danoune, n khelfaoui, "field experience study and evaluation for hydrogen production through a photovoltaic system in ouargla region, algeria,” international journal of hydrogen energy. vol 45, n°4, 2020, pp. 2593-2606. doi: 10.1016/j.ijhydene.2019.11.188 [5] m. azzouzi, d. popescu, and m. bouchahdane, " modeling of electrical characteristics of photovoltaic cell considering single-diode model,” journal of clean energy technologies november . vol. 4, no. 6. 2016 [6] mohammed bilal danoune, ahmed djafour, abdelmoumen gougui, narimane khelfaoui, halima boutli, " characterization of photovoltaic panel using single diode and double diode models a comparative study with experimental validation,” the 5th international seminar on new and renewable energies; ghardaïa – algeria 24 – 25, 2018. [7] kashif ishaque, zainal salam, hamed taheri, " simple, fast and accurate two-diode model for photovoltaic modules,” solar energy materials & solar cells. vol 95, 2011, pp. 586–594. [8] k. et-torabi, i. nassar-eddine, a. obbadi, y. errami, r. rmaily, s. sahnoun, a. el fajri, m. agunaou, " parameters estimation of the single and double diode photovoltaic models using a gauss–seidel algorithm and analytical method: a comparative study,” energy conversion and management. vol 148, 2017, pp. 1041– 1054. [9] marcelo gradella villalva, jonas rafael gazoli, and ernesto ruppert filho, " comprehensive approach to modeling and simulation of photovoltaic arrays,” ieee transactions on power electronics may. vol. 24, n°. 5. 2009. [10] ali naci celik, nasır acikgoz, " modelling and experimental verification of the operating current of mono-crystalline photovoltaic modules using fourand five-parameter models,” applied energy. vol 84, 2007, pp. 1–15. [11] guojiang xiong, jing zhang, xufeng yuan, dongyuan shi, yu he, gang yao, " parameter extraction of solar photovoltaic models by means of a hybrid differential evolution with whale optimization, " solar energy . vol 176, 2018, pp. 742–761. [12] rabeh abbassi, abdelkader abbassi, ali asghar heidari, seyedali mirjalili, “an efficient salp swarm-inspired algorithm for parameters identification of photovoltaic cell models,” energy conversion and management. vol 179, 2019, pp. 362–372. [13] dalia allam, d.a. yousri, m.b. eteiba, " parameters extraction of the three diode model for the multicrystalline solar cell/module using moth-flame optimization algorithm,” energy conversion and management. vol 23, 2016, pp. 535–548. [14] mohamed a. awadallah, "variations of the bacterial foraging algorithm for the extraction of pv module parameters from nameplate data,” energy conversion and management. vol 113, 2016, pp. 312–320. [15] alireza askarzadeh, leandro dos santos coelho, " determination of photovoltaic modules parameters at different operating conditions using a novel bird mating optimizer approach,” energy conversion and management . vol 89, 2015, pp. 608–614. [16] qun niu, of solar and fuel cells,” energy conversion and letian zhang, kang li, " a biogeography-based optimization algorithm with mutation strategies for model parameter estimation management. vol 86, 2014, pp. 1173–1185. [17] mirjalili s, gandomi ah, mirjalili sz, saremi s, faris h, mirjalili sm, " salp swarmbalgorithm: a bio-inspired optimizer for engineering design problems, " adv eng softw. vol 114, 2017, pp. 163–91. [18] seyedali mirjalili, andrew lewis, "the whale optimization algorithm,” advances in engineering software. vol 95; 2016, pp. 51–67. [19] mb. danoune, a. djafour, a. gougui, “accurate pem fuel cell parameters identification using whale optimization algorithm,” advances in renewable hydrogen and other sustainable energy carriers, pp. 203210, 2020. https://doi.org/10.1007/978-981-15-6595-3_27 [20] dervis karaboga, bahriye basturk, " a powerful and efficient algorithm for numerical function optimization: artificial bee colony (abc) algorithm,” j glob optim. vol 39, 2007, pp. 459–471. [21] russell eberhart, james kennedy, " a new optimizer using particle swarm theory,” ieee, sixth international symposium on micro machine and human science. 07803-2676-8/9 [22] n khelfaoui, a djafour, k bouali, mb danoune, a gougui, h boutelli, " investigation of the temperature effect on the electrical parameters of a photovoltaic module at ouargla city,” international journal of emerging electric power systems . vol 20, n°4. 2019. https://doi.org/10.1515/ijeeps-2019-0025 [23] mohammed bilal danoune, ahmed djafour, abdelmoumen gougui, narimane khelfaoui, halima boutelli, " study and performance analysis of three conventional mppt algorithms used in photovoltaic applications, " ieee proceeding international conference on communications and electrical engineering (iccee) el oued (algeria) december. 2018, pp. 18-19. [24] s. shadravan, h.r. naji, v.k. bardsiri, “ the sailfish optimizer: a novel nature-inspired metaheuristic algorithm for solving constrained engineering optimization problems,” engineering applications of artificial intelligence. vol 80, 2019, pp.20–34. https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ufrvopgsrksc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ufrvopgsrksc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ufrvopgsrksc https://doi.org/10.1016/j.ijhydene.2020.11.193 https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:w7oemfmy1hyc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:w7oemfmy1hyc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:w7oemfmy1hyc http://dx.doi.org/10.1016/j.ijhydene.2019.11.188 https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ysmsglbcyi4c https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ysmsglbcyi4c https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:ysmsglbcyi4c https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:zylm7y9caggc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:zylm7y9caggc https://scholar.google.fr/citations?view_op=view_citation&hl=fr&user=_bbru1saaaaj&citation_for_view=_bbru1saaaaj:zylm7y9caggc https://doi.org/10.1515/ijeeps-2019-0025 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 7. issue 2. 2022 page 41-51 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 41 generating temperature cycle profiles of different solar photovoltaic module technologies from in-situ conditions for accurate prediction of thermomechanical degradation bebeto nii sampa sampah * , frank k. a. nyarko, benjamin atribawuni asaaga, jefferson aggor department of mechanical engineering, college of engineering, kwame nkrumah university of science and technology kumasi, ghana *corresponding author: email: bebetosampahns@gmail.com abstract – the iec61215 tc200 is a rigorous approval thermal cycling test process that assesses the reliability of solar photovoltaic modules and offers a 25-year lifetime guarantee. however, previous research has shown that installed solar photovoltaic modules experience different rates of degradation depending on the location and climate with most research focused on crystalline silicon. in this study, outdoor weathering data obtained from a rig set up in kumasi, ghana for the year 2014, is used to generate thermal cycles for 5 different technologies including monocrystalline, polycrystalline, and amorphous silicon, copper indium gallium selenide (cigs) and heterojunction-with-intrinsic-thin-layer (hit). from the results, the highest yearly average of the maximum and minimum temperatures, and ramp rates of 54.8 o c, 26.1 o c, and 6.05 o c/h respectively are recorded in cigs. polycrystalline recorded the least temperatures of 45.2 ° c and 23.9 ° c while hit recorded the least ramp rate of 4.45 ° c /h. a comparison between the 2014 and the iec61215 thermal cycles show extremely wide differences which could explain the higher degradation rates and shorter life of installed solar photovoltaic modules. the procedure adopted in this research can be repeated at different locations to obtain technology-specific thermal cycling profiles to evaluate the thermomechanical damage and predict the life of different solar photovoltaic modules. keywords: temperature cycling, ramp rates, temperature gradient, dwell time, iec 61215/61416, co-efficient of thermal expansion (cte), in-situ data generation. received: 12/09/2022 – revised 29/11/2022 – accepted: 05/12/2022 i. introduction the commercial viability of pv systems is strongly dependent on the field performance, cost, and life. it is imperative for engineers to study and minimize degradation and failure modes exposed to pv systems during their operational lifetime to improve commercial viability [1]. pv modules are expected to function at 90% power capacity for the first 10 years of operation and 80% power capacity after 25 years [2]. however, these estimations are not guaranteed due to the various external stresses pv modules are exposed to during field operation. these include temperature changes, moisture, humidity, mechanical stress, and irradiance [3]. one of the common failure modes in solar modules is thermo-mechanical fatigue. solder joints are the most susceptible layers to thermal damage and contribute to 40.7% of failures reported in field operations. this can result from exposure to high temperatures during the soldering process at manufacturing. also, the difference in the coefficient of thermal expansion induces expansion mailto:bebetosampahns@gmail.com bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 42 and contraction in the various layers of solar modules at different rates during day and night temperature changes. the growth of intermetallic compounds (imc) in the solder joints also contributes to thermomechanical damage [4]. to study reliability in pv modules, the choice of thermal cycling is an important factor. it is characterized by temperature fluctuations between peak day temperatures and low night temperatures, ramp rates, and dwell times [5]. many researchers have resorted to the use of the iec 61215/iec 61646 tc 200 thermal cycles to study thermochemical damage [4, 6, 7]. the iec 61215/ iec 61646 involves subjecting solar modules to temperatures ranging between -40 °c to +85 °c, with ramp rates of 100 °c /h and 10-minute dwells [8]. it is most commonly seen with researchers varying parameters of the tc 200 in the course of their research. this includes an increased number of cycles, higher temperature gradients, ramp rates, and dwell times [4, 6, 7]. however, these conditions do not properly define the thermal conditions that the solar modules are exposed to during field operation, which varies from place to place. on the other hand, the use of field data to study degradation in pv modules is essential to generating more accurate results since their actual lifetime are climate and location dependent [3]. cuddalorepatta et al. [9] reported the use of field conditions between the temperature ranges of 17 °c to 63 °c in their study on the durability of lead-free solder in crystalline silicon solar modules. one study used data obtained from two days of weather exposure in doha, qatar to represent a summer day and a winter day in the study of the reliability of pv modules [10]. there are different types of solar modules with a wide range of efficiencies, which depends on the types of semiconductor that were adopted during manufacture [11]. these include mono-crystalline silicon, polycrystalline silicon, microcrystalline silicon, copper indium selenide, cadmium telluride, amorphous silicon, gallium arsenide, and hit solar modules [2, 12]. the most commonly used solar module is monocrystalline silicon, which dominates the market by 85%. this supports the fact that the majority of research carried out on solar module reliability involved monocrystalline silicon [10, 13, 14]. some researchers adopted polycrystalline in their studies on thermomechanical reliability [4, 15]. a research used four different solar modules which include monocrystalline silicon, multicrystalline silicon, amorphous silicon, and cigs solar modules to study the performances in the field [16]. the study also used data obtained from three consecutive days in malaysia. from the literature, it can be seen that there is limited use of field data in studies on solar module reliability. moreover, most of this research is focused on crystalline silicon solar modules and an even lesser number on thin films. there is also limited research on the inclusion of different technologies in one test site. the purpose of this study is to generate an in-situ thermal cycle profile for five (5) different solar pv module technologies in kumasi, ghana. this involves the use of data obtained in the year 2014 for solar modules including monocrystalline silicon, polycrystalline silicon, cigs, amorphous silicon, and hit to develop temperature profile cycles and subsequently generate five different thermal cycles to represent the different technologies at the test site. ii. material and method this study makes use of secondary data that was obtained from an outdoor climate monitoring rig. figure 1(a) shows a number of solar photovoltaic modules that make up the rig. it involves monocrystalline silicon, polycrystalline silicon, cigs, amorphous silicon, and hit solar photovoltaic modules. figure 1(b) shows the data collection substation. the list of solar photovoltaic module specifications and capacities is shown in table 1. the rig was installed in 2012 through the african renewable energy access program financed by the world bank under the project title:" capacity upgrading for west african partners in renewable energy education". the rig can be found at the college of engineering knust, kumasi, ghana, west africa. its site location is latitude 64000 n and longitude 13700 w, 250m above sea level. they are mounted on a rooftop inclined at an angle of 5 degrees, facing southwards. the rigs are connected to the grid by a 4 kw sma sunny boy dc-ac inverter (sb 3800). using a bluetooth adhoc connection, five inverters are connected and configured to communicate with a sma sunny webbox, to log and transfer data from the various photovoltaic technologies to a server to be stored. using the university network, an online monitoring system is established for the sma sunny portal created on the server. to measure the module temperatures, calibrated platinum sensors with ±0.5 °c measurement accuracy, and 0.1 °c resolution, placed on the backside center of each module are used. the data recorded by the system included environment temperature, module temperature, total insolation, operating current and voltage, wind speed, and total output power. the data captured starts in march 2012 and ends in may 2015. however, the point of focus bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 43 in this research was the year 2014 since it provided the greatest amount of data as compared to the other years. figure 1. (a) outdoor climate monitoring rig involving five different solar photovoltaic technologies. (b) data collection substation [13]. table 1. solar photovoltaic module specifications and capacities. ii.1. generating daily temperature profile the 288 data points of module temperature recorded at intervals of 5 minutes were extracted for the various photovoltaic technologies according to their days. the module temperature columns for the various technologies were extracted and arranged by days of the month to match their respective times at which data was recorded in a new excel sheet according to the type of photovoltaic technology. subsequently, this was repeated for all months of the various years. the monthly temperature average was computed for all the months. with the help of a simple matlab program, the monthly averages were extracted and plotted against time to obtain the plots of the daily temperature profiles. ii.2. generating thermal cycles to obtain thermal cycles, six data points per cycle were to be selected: the first point being the first temperature to be recorded in a given day, the second point being the temperature at the end of the first cold dwell, the 3 rd point being the temperature at the end of the ramp up or the beginning of the dwell, the 4 th point being the temperature at the beginning of the ramp down or the end of the dwell, 5 th being the temperature at the end of the ramp down and the 6 th point being the temperature at the end of the second cold dwell. figure 2 demonstrates a labeled thermal cycle and the 6 points selected for simulation. in order to obtain these points, the ramp rate/rate of change from one point to another was computed for all months of the given years. the calculated ramp rates in conjunction with graphical linear fitting were used to identify these points which signify the turning points in the daily temperature cycles. the temperature and time at these points were noted and used to plot a graph with the help of a simple matlab program. the dwell times were also obtained as follows. the hot dwell time was given by: 𝑇ℎ𝑜𝑡 𝑑𝑤𝑒𝑙𝑙 = 𝑇4 − 𝑇3 (1) the first cold dwell was given by: (2) the second cold dwell was given by: (3) where t1, t2, t3, t4, t5, and t6 are the respective times obtained from the thermal cycle. bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 44 figure 2. sample of a daily thermal cycle[17]. iii. results and discussions the rig setup transmits data recorded at the 5-minute interval and stored on a server from march 2012 to may 2015. the study and data analysis is limited to the year 2014 and the technologies included are monocrystalline silicon, polycrystalline silicon, cigs, amorphous silicon, and hit solar modules. this section presents and discusses the results obtained from data analysis for the generation of temperature cycle profiles for the five technologies in the year 2014. iii.1. modeling procedure the 288 data points obtained from the test rig were used to plot the monthly average of the daily temperatures against time to generate the temperature cycles for the various technologies of the various years. table 2 summarizes the statistics of the data obtained from the daily temperature of the various technologies in the year 2014. cigs recorded the highest maximum temperature of 77.1 °c while polycrystalline silicon recorded the least minimum of 15.7 °c. the maximum mean temperature of 35.4 °c was recorded in cigs and the lowest mean temperature of 30.9 °c was recorded in polycrystalline. table 2. data summary for all solar module technologies in the year 2014. figure 3 shows the daily temperature profiles for the year 2014 for all technologies. figure 3(a). monthly averaged daily temperature profiles for january 2014 to april 2014. bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 45 figure 3(b). monthly averaged daily temperature profiles for may 2014 to october 2014. figure 3(c). monthly averaged daily temperature profiles for november 2014 to december 2014. high temperatures contribute significantly to reducing the life of a solar module. it results in high stress formed in the solar module due to different coefficients of thermal expansion of module materials which eventually leads to failure. this means that solar modules with higher temperatures are expected to have shorter life [18]. the variation in the difference in coefficient of thermal expansion among the various technologies, along with other material properties may be the reason for different temperature readings in the various technologies despite being installed in the same geographical location under the same solar radiation. the method of manufacturing could also be a contributing factor. iii.2. temperature gradient the change in temperature between the high temperatures in the day and low temperatures at night is referred to as the temperature gradient. it was obtained by identifying the highest and lowest temperatures observed in a given month and finding the difference between them. hence the temperature gradient is given by δt=tmax tmin (4) bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 46 table 3 shows a summary of the frequency of occurrence for temperature gradient expressed in percentage of occurrence for the various technologies for the year 2014. it can be observed that the monocrystalline silicon and the hit solar module had their temperature gradients within the range of 35 °c -to 49.99 °c and cigs solar module had temperature gradients within the range of 40 °c -to 59.99 °c. the polycrystalline recorded temperature gradients within the range of 25 °c -to 44.99 °c which was slightly similar in the amorphous silicon solar module which also recorded some temperature gradient occurrence in the range of 55 °c -to 59.99 °c. all the technologies with exception of cigs recorded the most temperature gradients in the limits of 40 °c -49.99 °c. cigs recorded the most temperature gradients in the limits of 50°c -to 54.99°c which shows it recorded the highest temperature gradients amongst the other solar modules. figure 4 shows a frequency distribution of the daily temperature gradients obtained in the year 2014 for all the technologies. table 3. summary of frequency of occurrence of temperature gradient distribution for the year 2014 for all technologies. figure 4. frequency distribution of the monthly average of daily temperature gradients for various technology module temperatures in the year 2014. table 4 shows the mean temperature gradients of all the various technologies in the year 2014. the highest temperature gradient was observed at 51.8 °c in cigs and the least at 38.4 °c was observed in polycrystalline silicon. table 4. mean temperature gradients of the various technologies in the year 2014. iii.3. 3.3 thermal cycles the thermal cycles were obtained using the average ramp rates in conjunction with linear curve fitting of the daily temperature profiles. the six points were obtained and their respective times and temperatures were used to plot the thermal cycles. for example, in january 2014 shown in figure 3(a), it was observed that the average ramp rate between point 1 and point 84 was a very small negative decimal approaching zero. this number authenticated the graphical nature of the first cold dwell, which is characterized by a horizontal line. beyond point 84, it was observed that ramp rates began to increase significantly till it reached point 146. the average ramp rate was a significant positive value which implied a very steep upward slope, equal to that of a ramp-up. between point 146 and point 172 was a dwell. after point 172, the ramp rate was seen to be a significant negative value which implied a steep downward slope, equal to that of a ramp down. after point 227 the average ramp rate was seen to be a small negative value hence the slope became less downward steep up to point 288, which was equal to that of the second cold dwell. hence these points were translated into time steps for the 6 data points required for the simulations; 0:00 gmt, 6:55 gmt, 12:05 gmt, 14:15 gmt, 18:50 gmt, and 23:55 gmt respectively. the temperatures recorded at these times were also noted. the temperature at point 3 was equated to point 4 to emulate the dwell. this procedure was repeated for all the months and years for the various technologies. the times and temperatures were extracted with help of a matlab program and used to plot a yearly module temperature cycle for the various photovoltaic technologies. figure 5 shows the thermal cycles of the various technologies for the year 2014. the maximum temperatures slightly increased from january to march, reduced till august, and then increased till december. the trends of the thermal cycles for the various technologies are a result of the weather changes associated with the climate seasons in ghana, namely the dry season and the rainy season. the dry season occurs from november to march, which explains the observation of high peak temperatures during these months, in the thermal cycles. the rainy season, on the other hand, occurs from april to september/november bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 47 which explains the low peak temperatures recorded during these months in the thermal cycles [21]. figure 5. thermal cycles for the year 2014 iii.4. ramp rate the ramp-up rate signifies the rate at which temperature rises at a significant amount from the 1 st cold dwell to the dwell. it can then be referred to as the heating rate. the ramp-down rate signifies the rate at which temperature reduces at a significant rate from the dwell to the 2 nd cold dwell hence can also be referred to as the cooling rate. table 5 shows a summary of the ramp rates in the year 2014 for all technologies. the highest mean heating rate of 5.95 ° c /h was found in cigs solar module with a maximum heating rate of 7.76 ° c /h and the least heating rate of 4.31 was observed in hit solar module with a maximum heating rate of 5.39 o c/h. the highest mean cooling rate of 6.09 ° c /h was observed in cigs with a maximum cooling rate was 7.67 ° c /h and the least mean cooling rate of 4.45 o c/h with a maximum cooling rate of 5.29 ° c /h was observed in amorphous silicon solar module. the results on the ramp rates are graphically presented in figure 6 which shows the distribution of the mean and maximum for the ramp-up and ramp-down rates in the year 2014 for the various technologies table 5. ramp rates for the various technologies in the year 2014. figure 6. distribution of the mean and maximum ramp rates in the year 2014 for the various technologies. it was observed that ramp rates for cigs solar modules were consistently the highest among all the other solar modules. this was then followed by monocrystalline. hit, polycrystalline silicon, and amorphous silicon modules were often in varying positions. the mean ramp rates obtained in this study were slightly lower than the ramp rates observed in a similar study [15]. observing the ramp-up and ramp-down rates shows that their respective values relate closely to each other which is similar to the iec thermal cycle with ramp-up and ramp-down rates both at 100c/h [8]. this means that the rate at which temperatures rise to the peak of the day is the same rate from after the peak to the night. the study showed that faster ramp rates led to more damage in the solder joint than slower ramp rates [22]. another study expected that the solar module with the highest ramp rates should have the shortest life [20]. iii.5. 3.5 temperature dwell times in theory, the temperature dwell time refers to the time in the temperature cycle profile when there is no increase in temperature hence zero ramp rates. in practical application, the hot dwell occurs at the time when there is a significant decrease in the ramp-up/heating rate. the 1 st and 2 nd dwell occur at the time when there are minimal ramp rates before ramp-up starts and after ramp-down ends respectively. the dwell times were obtained using equations (1) (2) and (3) mentioned in section 2. with respect to all the solar module technologies (monocrystalline, polycrystalline, amorphous silicon, cigs, and hit), it was observed that dwell times were the same each month. however, across the months of the year 2014, different hot and cold dwell times were recorded. figure 7 shows the mean monthly distribution for the hot dwell, 1 st , and 2 nd cold dwell times in the year 2014 for all the technologies. the mean hot dwell time was observed to be 190 minutes with a maximum of 265 bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 48 minutes in april and a minimum of 130 minutes in january. the mean 1 st and 2 nd cold dwell times were 398 and 320 minutes respectively. the maximum for the 1 st and 2 nd cold dwell times were 420 and 350 minutes respectively, with both recorded in february and the minimum for the 1 st and 2 nd cold dwell times were 375 and 300 minutes respectively, with both recorded in june. the trend of dwell times correlates with the trend of the thermal cycles and climate in ghana [21]. this implies that dwell times are longer during dry seasons and shorter in the rainy seasons. figure 7. monthly mean distribution of hot dwell, 1 st and 2 nd cold dwell times for the year 2014 for all technologies. the mean hot dwell and cold dwell times in this study were about 3 hours and 6 hours respectively which are closely related to dwell times obtained in a similar study [15]. longer dwell times contributed significantly to reducing the fatigue life of solder joints by causing more creep [22]. although dwell times for the various technologies are the same, dwells were seen to occur at different temperatures. table 6 shows the mean hot dwell temperatures (hdt) and mean cold dwell temperatures (cdt) in the year 2014 for the various technologies. the highest mean hot dwell temperature was observed in cigs with the highest of them being 54.78 ° c. the lowest hot dwell temperature of 45.15 ° c was seen in hit. the highest cold dwell temperature of 26.12 ° c was seen in cigs with the lowest cold dwell temperature of 23.88 °c seen in polycrystalline. table 6. summary of mean hot dwell temperatures (hdt) and mean cold dwell temperatures (cdt) for the various technologies in the year 2014. iii.6. comparison between iec 61215 and 2014 thermal cycle the thermal cycles of the various technologies were compared with iec 61215 thermal cycle and the percentage differences for the parameters evaluated above were obtained. table 7 shows a summary of the percentage difference of parameters between the thermal cycles of the various technologies in the year 2014 and the iec 61215 thermal cycle. the iec 61215 is characterized by high ramp rates, short dwell times, and a high-temperature gradient. it is performed over a short cycle time(10200s). on the other hand, the thermal cycles of the various technologies had low ramp rates, long dwell times, low-temperature gradients, and longer cycle times (86400s). iii.6.1. ramp rates the percentage difference in ramp-up and ramp-down rates between the monocrystalline silicon and iec 61215 was -95.1% and -95.0% respectively. the ramp-up and ramp-down rates of polycrystalline silicon compared to the iec 61215 were both -95.5%. the ramp-up and ramp-down rates of hit compared to the iec 61215 were -95.7% and -95.4% respectively. the ramp-up and ramp-down rates of cigs compared to the iec 61215 were -94.1% and 93.9% respectively. the ramp-up and ramp-down rates of amorphous compared to the iec 61215 were -95.4% and 95.6% respectively. the highest percentage difference was seen in hit while the lowest was seen in cigs. this shows that the ramp rates of the iec 61215 were extremely larger than that of the various technologies with the cigs having the highest ramp rates among the other technologies. iii.6.2 dwell times dwell times were the same across the various technologies. compared with the iec 61215, the hot dwell and cold dwell from all the technologies had a difference of 1796% and 3489.5% respectively. this shows that the dwell times of the various technologies were significantly higher compared to iec 61215. this is because the nature of the weathering conditions is such that daytime temperatures remain fairly constant for about 3 hours nearing the highest day temperatures and nighttime temperatures remain fairly constant for about 7 hours nearing the lowest night temperatures. iii.6.3 maximum, minimum, and temperature gradient the maximum, minimum, and temperature gradients of the mono-crystalline silicon thermal cycle compared to that of the iec 61215 had percentage differences of 43.6%, -161.6%, -81.4% respectively. the maximum, bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 49 minimum, and temperature gradients of the polycrystalline crystalline silicon thermal cycle compared to that of the iec 61215 had percentage differences of -46.8%, -159.7%, -82.9% respectively. the maximum, minimum, and temperature gradients of the hit thermal cycle compared to that of the iec 61215 had percentage differences of 46.9%, -160.9%, and 83.4% respectively. the maximum, minimum, and temperature gradients of the cigs thermal cycle compared to that of the iec 61215 had percentage differences of -35.6%, -165.3%, and -77.1% respectively. the maximum, minimum, and temperature gradients of the mono-crystalline silicon thermal cycle compared to that of the iec 61215 had percentage differences of 45.9%, -160.4%, and -82.6% respectively. the highest difference in maximum temperature was observed in polycrystalline while the lowest difference was seen in cigs as shown in table 7. with minimum temperature, the highest difference was seen in cigs with the lowest difference in polycrystalline. the greatest difference in temperature gradient was seen in hit with the least difference seen in cigs. this shows that the temperatures of the various technologies were significantly lower than that of the iec 61215. table 7. summary of the percentage difference between thermal cycles of the various technologies in the year 2014 and the iec 61215 thermal cycle. iv. conclusion and recommendation in this study, outdoor weathering data from a rig setup in kumasi was used to generate thermal cycles for 5 different technologies namely monocrystalline silicon, polycrystalline silicon, heterojunction with an intrinsic thin layer (hit), copper indium gallium selenide (cigs), and amorphous silicon solar modules in the year 2014. key parameters which included maximum, and minimum temperatures, ramp rates, and hot and cold dwell times were obtained. the thermal cycles in the year 2014 had the most amount of data and hence were the most suitable to be used for further studies on thermomechanical reliability. the maximum, minimum, and ramp rates for the various technologies in the year 2014 were 47.9 ° c, 24.6 ° c, 4.95 ° c /h for monocrystalline silicon, 45.2 ° c, 23.9 ° c, 4.55 ° c /h for polycrystalline silicon, 45.2 ° c, 24.4 ° c, 4.45 ° c /h for hit, 54.8 ° c, 26.1 ° c, 6.05 ° c /h for cigs and 46.0 ° c, 24.2 o c,4.55 ° c /h for amorphous silicon solar modules respectively. parameters in cigs were constantly the highest, followed by monocrystalline silicon and then polycrystalline silicon, amorphous silicon, and hit which were closely related. hot dwell and cold times were 189 minutes and 359 minutes respectively for all the technologies. a comparison between the thermal cycles of the various technologies and the iec 61215 thermal cycle showed massive differences. the percentage differences of the various technologies were in the ranges of -35.6% to -46.9% for maximum temperatures, -35.6% to -46.9% for minimum temperatures, -159.7% to -165.3% for minimum temperatures, -94% to -95.55% for ramp rates, and 1796% and 3489.5% for the hot and cold dwell times. in light of the findings obtained from this research, the author recommends that the thermal cycling for the various technologies under outdoor weathering in kumasi may be used to carry out reliability testing to assess thermomechanical fatigue in the solder joints of the solar modules. this is necessary to evaluate the damage exposed to the solder joints by thermal stress and provide knowledge on the expected life. thermal cycling is location-dependent hence similar research may be repeated to obtain thermal cycles in various test sites in ghana. acknowledgment the us national academy of sciences provided funding for the pressa project sub-grant no. 2000004829, which the authors gratefully acknowledge. the arizona state university photovoltaic reliability laboratory's dr. mani and sai tatapudi's technical assistance is greatly appreciated by the authors. the authors also acknowledge the norwegian program for capacity development in higher education and research for development in the fields of energy and petroleum (enpe) for the support provided. bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 50 declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism. references [1] m. aghaei et al., “review of degradation and failure phenomena in photovoltaic modules,” renewable and sustainable energy reviews, vol. 159, 2022, pp. 112160, doi: 10.1016/j.rser.2022.112160. [2] v. devabhaktuni et al., “solar energy : trends enabling technologies,” renewable and sustainable energy reviews, vol. 19, 2013, pp. 555–564, doi: 10.1016/j.rser.2012.11.024. [3] a. smets, k. jaeger, o. isabella, r. van swaaij, m. zeman, "fundamentals, technology and systems, solar energy,” vol. 1. uit cambridge ltd, 2016. [4] m. t. zarmai, n. n. ekere, c. f. oduoza, e. h. amalu, ” optimization of thermo-mechanical reliability of solder joints in crystalline silicon solar cell assembly,” microelectronics reliability, 2015, pp. 117-125. doi:10.1016/j.microrel.2015.12.031 10.1016/j.microrel.2015.12.031 [5] s. chaparala, j. m. pitarresi, and m. meilunas, “effect of dwell times and ramp rates on the thermal cycling reliability of pb-free waferlevel chip scale packages-experiments and modeling.,” conference: asme international mechanical engineering congress and exposition, 2006, doi : 10.1115/imece2006-13376 [6] e. h. amalu, d. j. hughes, f. nabhani, j. winter, “thermo-mechanical deformation degradation of crystalline silicon photovoltaic ( c-si pv ) module in operation,” eng. fail. anal., vol. 84, no. 2018, pp. 229–246, doi: 10.1016/j.engfailanal.2017.11.009. [7] d. ghaderi, m. pourmahdavi, " combination of thermal cycling and vibration loading effects on the fatigue life of solder joints in a power module," journal of materials: design and applications, vol. 233, 2018, doi: 10.1177/1464420718780525. [8] c. b. jones, b. hamzavy, w. b. hobbs, c. libby, o. lavrova, “iec 61215 qualification tests vs outdoor performance using module level in situ i-v curve tracing devices,” 7th world conference on photovoltaic energy conversion, 2018, doi: 10.1109/pvsc.2018.8548222 [9] g. cuddalorepatta, a. dasguptal, s. sealing, j. moyer, t. tolliver, j. loman, “durability of pb-free solder connection between copper interconnect wire and crystalltne silicon solar cells,” 2006, doi: 10.1109/itherm.2006.1645486 [10] s. p. aly, s. ahzi, n. barth, a. abdallah, “numerical analysis of the reliability of photovoltaic modules based on the fatigue life of the copper interconnects,” solar energy, vol. 212, no. april, 2020, pp. 152–168, doi: 10.1016/j.solener.2020.10.021. [11] s. m. shamim, m. b. science, s. islam, f. huq, “design , performance analysis and efficiency optimization of copper indium gallium selenide ( cigs ) solar cell,” european scientific journal, vol.11, no.6, 2015. [12] l. m. fraas, “the dream of thin film pv,” in lowcost solar electric power, ” springer international publishing, 2014, pp. 73–79. [13] f. k. a. nyarko, g. takyi, e. h. amalu, m. s. adaramola, “generating temperature cycle profile from in-situ climatic condition for accurate prediction of thermo-mechanical degradation of c-si photovoltaic module,” engineering science and technology, an international journal, 2018, doi: 10.1016/j.jestch.2018.12.007 [14] u. eitner, s. kajari-schr, k. marc, and h. altenbach, “thermal stress and strain of solar cells in photovoltaic modules,” part of the advanced structured materials book series, 2011, pp. 453–468. [15] n. park, j. jeong, c. han, “microelectronics reliability estimation of the degradation rate of multicrystalline silicon photovoltaic module under thermal cycling stress,” microelectron. reliab, microelectronics reliability, vol . 54 , 2014, pp. 1562– 1566, doi:10.1016/j.microrel.2014.03.021 [16] n. amin, c. wen, k. sopian, “a practical field study of various solar cells on their performance in malaysia,” renew. energy, vol. 34, no. 8, 2009, pp. 1939–1946, doi: 10.1016/j.renene.2008.12.005. [17] f. k. nyarko, afriyie, g. takyi, a. a. agyemang, c. s. k. kofi, “crystalline silicon ( c-si ) solar cell interconnect damage prediction function based on effect of temperature ramps and dwells on creep damage under field thermal cycling,” crystals and thin films , 2021, vol. 633 , https://doi.org/10.3390/cryst11060633 [18] o. m. al-habahbeh, b. a. al-hrout, e. a. al-hiary, s. a. al-fraihat, “durability prediction of thin-film pv modules durability prediction of thin-film pv modules,” int’l j. eng. simulation with indust. applications (ijes), vol. 15, 2014, pp.13-21. [19] w. herrmann, n. bogdanski, f. reil, k.-a. weiss, m. assmus, m. heck, “pv module degradation caused by thermomechanical stress : real,” reliability of photovoltaic cells, modules, components, and systems iii. doi:10.1117/12.859809 [20] s. c. chaparala et al., “effect of geometry and temperature cycle on the reliability of wlcsp solder joints,” ieee transactions on components and packaging technologies, 2005, pp. 441–448. [21] k. owusu, p. r. waylen, “the changing rainy season https://doi.org/10.1109/itherm.2006.1645486 bebeto nii sampa sampah et al. / international journal of energetica (ijeca) vol. 7, n°2, 2022, pp. 41-51 page 51 climatology of mid-ghana,” theoretical and applied climatology, vol 112, 2012, pp. 419–430, doi:10.1007/s00704-012-0736-5 [22] x. fan, g. raiser, v. s. vasudevan, “effects of dwell time and ramp rate on lead-free solder joints in fcbga packages,” proceedings electronic components and technology, 2005, doi: 10.1109/ectc.2005 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 25-28 ijeca-issn: 2543-3717. december 2017 page 25 structural, electronic and thermoelectric properties of the intermetallic materials based on mg2x (x= si, ge, sn): dft calculations. miloud ibrir 1 , moufdi hadjab 2 , said lakel 3 , nafissa meggag 1 1 laboratory of physics of materials and its applications,department of physics, m’sila university, algeria. 2 thin films development and applications unit (udcma) – setif, algeria 3 laboratory of metallic and semiconducting materials,department of physics , university of biskra, algeria. ibrirmiloud@yahoo.fr abstract – the scope of this work is the investigation of the physical properties of chalcopyrite materials using ab-initio methods in order to simulate a new structure of thin-films photovoltaic cells with high conversion efficiency. in the first framework, we obtained the results of calculations based on density functional theory (dft) using the full-potential linearized augmented plane wave method (fp-lapw) as involved in the wien2k computational package. for the exchange-correlation potential, the local density approximation (lda) was used to calculate the lattice parameters, bulk modulus and its first derivative as well as the densities of states of the intermetallic semiconductors materials based on mg2x (x=si, ge and sn). the semilocal becke-johnson (mbj) potential and its modified form proposed by tran and blaha (tb-mbj) were also used for studying the electronic and thermoelectric properties; (merit factor, seebeck coefficient, electronic conductivity). the achieved results were compared to computational works and other data acquired experimentally. keywords: fp-lapw, science research, publication received: 15/11/2017 – accepted: 25/12/2017 i. introduction at this work, we will study the structural properties (lattices parameters, bulk modulus and its first derivative), the electronic properties (total and partial density of states) and thermoelectric properties (seebeck coefficient, thermal and electrical conductivities and figure of merit) for mg2x(x=ge, si, sn) compounds. the investigation are accomplished by employing a full potential augmented plane wave (fplapw) method framed within density functional theory dft as implemented in wien2k code. to determine the exchange correlation potential, we have used lda approximation and tarn et blaha functional [1] denoted (tb-mbj), which is modified of becke-johnson in the method fp-lapw. ii. computational details in the present calculation, full potential augmented plane wave fp-lapw [2] method within tb-mbj approximation and lda approximation are used as incorporated in wien2k code [3]. half-relativistics calculations are performed (spin orbital effect is neglected). we have carried out convergence tests of total energy 𝐸𝑡 for mg2x (x=ge, si, sn) as function of 𝑅𝑚𝑡 and 𝐾max parameters and as function of k-points number over reduced brillioun zone. the calculations were performed in self-consistent way, using the two approximations mentioned below. the input parameters are listed in table1. table 1. input parameters of fp-lapw for mg2x (x=ge, si, sn) compounds rmt*kmax kpoints rmt (mg) rmt x (ge, sn, si) mg2ge 9 1000 1.9 2.5 mg2sn 9 1000 2 2.35 mg2si 9 1000 2.5 2.5 mailto:ibrirmiloud@yahoo.fr miloud ibrir et al. ijeca-issn: 2543-3717. december 2017 page 26 iii. properties of mg2x compounds iii.1. structural properties for mg2x (x= ge, si, sn) to determine the lattice equilibrium parameters and find how total energy varies as function of those parameters, we have to realize structural optimization on mg2x. we have performed, employing wien2k, a selfconsistent total energy calculations. the minimization of total energy was achieved by computing total energy for different lattice parameters around experimental value. figure 1. the total energy variation as function of volume for mg2x. the equilibrium volumes for all the investigated compounds were obtained by fitting the total energy as function of murnaghan’s equation state [4]: (1) where b0 and b’0 are respectively the equilibrium bulk modulus and its first derivative of pressure and v0 being the equilibrium unit cell volume. the lattice parameter corresponding the ground state is obtained from the minimum of etot (ev). the total energy was calculated as function of volume (figure 1) for mg2x in cubic structure. table 2. lattice parameter a (å), bulk modulus b (gpa) and its derivative bʹ and minimum energy emin, for mg2x (x = si, ge, sn). present calculations lda other calculations (gga)[5] other calculations experim ent mg2ge a (a°) 6,289 6,420 6,12 a 6, 286 e 6,31 f 6,38 k b0(gpa) 56,0866 49,7156 57,6 a – 55,9 e – 55,1 f 44,0 – 54,7 i 4,3089 4,1955 4,051 e emin(ry) -4990,529293 -4999,5929 _ _ mg2si a (a°) 6,261 6,369 6,09 a -6,26 e 6,29 f 6,35 k b0(gpa) 58,7828 54,1633 59,2 a -58,3 e 56,2 f 46,355,0 i 4,2243 3,5255 4,023 e _ emin(ry) -1376,202415 -1381,4461 _ _ mg2sn a (a°) 6,663 6,818 6,825 c 6,765 k b0(gpa) 45,6374 40,3594 _ _ 4,5973 4,1668 _ _ emin(ry) -13145,78347 -13159,657 _ _ [9] i . [7] e . [10] c . [6] a . [8] f .[11] k . iii.2. electronic properties the total and partial density of states for mg2x(x=ge, si, sn) obtained by using mbj method in cubic structure, are shown in figure 2. we can deduce that mg2x compounds have semiconducting character according to the density of states. the valence band is divided into two bands; the lower one is dominated by x-s orbital with no neglected contribution of mg-3s and mg-3p orbitals. the second is between (-9 and -7ev) for mg2si and mg2sn, between (10and -8ev) for mg2ge below ef, is dominated by ge4s, si-3s and sn-5s contribution. after gap of 2.5ev for mg2si and mg2sn and 3.5ev for mg2sn, it appears that the contribution of states mg3s and mg-3p predominate in this range of (-4.5and 0ev). in the conduction band, it emerges that the contribution of states mg-3s, 3p and x-3p are dominated. according to our decomposition of total and partial densities, we have shown that the valence electrons are mainly around the x (ge,si, sn). although, there is a weak covalence between mg and the x miloud ibrir et al. ijeca-issn: 2543-3717. december 2017 page 27 figure 2. total and partial density of states for mg2x(x=ge, si, sn). iii.3. thermoelectric properties the calculation of transport properties such as electrical conductivity, electronic thermal conductivity and seebeck coefficient are performed using boltztrap, which is tool for evaluating those properties, by solving boltzmann transport equation in the constant relaxation time approximation. the efficient thermoelectric materials (figure 3) of mg2x(x=ge, si, sn) compounds, have obvious attractive characteristics that makes them promising as thermoelectric energy converters in the range of medium temperature between (300-800). miloud ibrir et al. ijeca-issn: 2543-3717. december 2017 page 28 figure 3. variation of seebeck coefficient, electrical conductivity and electronic thermal condutivities with respect to chemical potential for mg2x(x=ge, si, sn). iv. conclusion the purpose of this research work is to investigate the structural, electronic and thermoelectric properties of intermetallic materials based on mg2x. we have utilized the all-electron fp-lapw method with lda for optimizing the lattice constants, the related bulk modulus and its first pressure derivative. the achieved results concerning the structural constants show an excellent agreement with the experimental data and other theoretical values. to calculate the densities of states (pdos/tdos) we used the new modified semi-local mbj approximation, we found that this approach brings the calculated energy gaps close to the experimental values and much better than the previous simulated results. based on this good agreement, the thermoelectric properties were predicted and discussed in details by using boltz-trap code. the results signify that our studied binary compounds are attractive materials for the optoelectronic devices area and thermoelectric applications. references [1] f. tran et p. blaha, phys.rev. lett. 102 (2009) 226401. [2] l. hedin et b. i. lundqvist, j. phys. c 4 (1971) 2064. [3] p. blaha, k. schwarz, g. k. h. madsen, d. k vasnicka et j. luitz,wien2k, an augmented planewave+local orbitals program for calculating crystal properties (karlheinz schwarz, techn. universitat wienna, austria), 2001. isbn 3-9501031-1-2. [4] f. d. murnaghan, proc. natl. acad. sci., 30 (1944) 5390. [5] m. guezlane, mémoire de magister, université elhadj lakhdar – batna 2011. [6] j.l. corkill and m.l. cohen, phys. rev. b 48, 1993, pp 17138. [7] o. benhelal, a. chahed, s. laksari, b. abbar, b. bouhafs et h. aourag, phys. stat. sol. (b) 242, 2005, pp 2022. [8] j.-i. tani, h. kido, lattice dynamics of mg2si and mg2ge compounds from first-principles calculations, comp. mater. sci., in press. [9] f. yu et jiu-xun sun solid state communications vol. 150, 2010, pp 620-624 [10] h. zhang, s. shang, intermetallics vol 17, 2009, pp. 878-885 [11] r. v. stuart et g. k. wehner, ‘energy distribution of sputtered cu atoms ‘, journal of applied physics, vol. 35, 1964, pp 1819. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 38-42 ijeca-issn: 2543-3717. december 2017 page 38 numerical study of the combustion of ch4-c3h8/ air: application to a combustion chamber with two coaxial jets mohamed el hadi attia 1 , zied driss 2 , abderrahmane khechekhouche 2,3 1* department of physics, faculty of science, university of el oued, 39000 el oued, algeria 2 laboratory of electro-mechanic systems (lasem), enis, university of sfax, tunisia 3 renewable energy development unit in arid zones (uderzr), el-oued university, algeria attiameh@gmail.com abstract – in this study, we studied numerically the non-premixed combustion provided by two coaxial methane-propane/air jets in a 3d cylindrical combustion chamber. to study this kind of phenomenon we used a special treatment of the mathematical model and we chose two models of computation pdf and les. in order to find the aero-thermo-chemical characteristics in the burner, namely: axial velocity, temperature and mass fraction of carbon monoxide co. using commercial calculation software cfd fluent the objective of this work is to research the fuel that reduces the emission of carbon monoxide co, which is considered a gas toxic to the environment, by comparing the two fuels ch4 and c3h8. the results give methane fuel reduces carbon monoxide as a pollutant chemical species in combustion products compared to propane fuel. keywords: non-premixed combustion; methane; propane; numerical simulation cfd received: 12/10/2017 – accepted: 15/11/2017 i. introduction combustion control is a vital capacity in the development of new industrial systems, such as propulsion systems. one of the challenges that industry must face today in order to accompany technological development is to reduce the impact of combustion on the environment. this impact is manifested in the discharge of chemical pollutants, of which the oxides of nitrogen (nox) and the gases participating in the greenhouse effect, such as carbon oxides, co and co2, are in the forefront. this challenge forces engine manufacturers to propose increasingly innovative solutions to achieve the set objectives [1]. several projects aim to minimize these emissions by introducing techniques such as lean burning, combustion of fuels of renewable origin and which does not contain carbon. combustion is a very complex phenomenon and its experimental investigation poses many difficulties. therefore, the experimental approach remains costly and limited to certain operating conditions. however, numerical calculation can be the most appropriate solution, given the progress made in the field of computing and modeling. there are several simulation models, either to simulate only the flow, or to simulate it by associating other joint phenomena [2]. in this work, a simulation study of the combustion of methane and propane in a combustion chamber. in addition, we used mathematical models, especially les for dynamic parameters and pdf for thermochemical parameters to reduce the number of equations, we used fluent-cfd. considering that the study of the behavior of non-premixed combustion fueled by ch4 and c3h8 fuels consists of three parameters: axial velocity, temperature and mass fraction of carbon monoxide co. the objective of this research is compared the fuels ch4 and c3h8 to find the fuel that reduces the emission of carbon monoxide co, which is considered the most toxic gas to the environment. the results give methane fuel reduces carbon monoxide as a pollutant chemical species in combustion products compared to propane fuel. ii. experimental configuration the configuration is a burner is given in figure 1. the cylindrical combustion chamber of radius r4=61.15 mm and length l=1 m provided by two coaxial jets ch4c3h8/air, the central jet presents by an internal radius equal to r1=31.57 mm and an external radius r2=31.75 mm, which injects the fuel with a speed v1=0.9278 m/s and the temperature t1=300 k. and the annular jet has an internal radius equal to r3≡r=46.85 mm, which injects air at a speed v2=20.63 m/s and preheated to a temperature t2=750 k. the combustion chamber is pressurized at p=3.8 bar and has a wall at constant temperature of partition t =500 k [3-8]. mailto:attiameh@gmail.com mohamed el hadi attia et al. ijeca-issn: 2543-3717. june 2017 page 39 figure. 1 schematic of the burner iii. governing equations in this paper, we study the behavior of non-premixed turbulent combustion in three dimensions using numerical simulation. we can write the control equations for the compressible flow in cartesian coordinates as follows [38]: continuity: 0)~(       i i u xt   (1) momentum: i ij j jiji i ji i i xx p uuuu x uu xt u                  )]~~([)~~( ~ (2) energy: ijj i ii i i i u xt p huhu x hu x h t                )] ~~([) ~~( ~ (3) species: ffifi i fi i f yuyu x yu x y t           )] ~~([) ~ ( ~ (4) where: i = 1, 2, 3 and j = 1, 2, 3,  , iu ~ , i , t are density, velocity vector, fuel reaction rate and time respectively. thermodynamic state: trp m ~  (5)  unresolved reynolds stresses )~~( jiji uuuu  , requiring a subgrid scale turbulence model.  unresolved species fluxes ) ~~( fifi yuyu  and enthalpy fluxes ) ~~( huhu ii  requiring a probability density function (pdf) approach.  filtered chemical reaction rate by f . the tensor of the unsolved constraints ij  as the tensor velocity of deformation ij s ~ for subgrid models by the intermediary of a turbulent viscosity ( t  ), and a subgrid kinetic energy ( ll k ). therefore, we focus on the assumption of boussinesq in which the small scales influence the large scales via the subgrid-scale stress [18]: ijllijtij ks  3 1~ 2  (6) where, the filtered strain rate tensor is defined by: ijll i j j i ij u x u x u s ~ 3 1 ~~ 2 1~                (7) the use of this wale-eddy viscosity model to express the eddy viscosity term in the momentum equation (2) is motivated by:  recovering the proper behavior of the eddy viscosity near the wall in the case of the wall-bounded flows;  preserving the interested properties such as the capacity to provide no eddy-viscosity in the case of vanishing turbulence (property required for the transition from laminar to turbulent states);  relying on the fact that no information about the direction and distance from the wall are needed (avoiding the use of any damping function);  being suitable for unstructured grids, where evaluating a distance to the wall is precarious. the residual stress tensor of the wale eddy viscosity model can be found as [38]: 4/52/5 2/3 2 )()~~( )( )( d ij d ijijij d ij d ij wt ssss ss c   (8) where ijkkjiij d ij gggs  222 ~ 3 1 )~~( 2 1  (9) and j i ij x u g    ~ ~ (10) cw: is the wale model constant (cw=0.49). the model constants used for all the computations in this paper have been set up for academic configurations such as turbulent combustion and homogenous isotropic turbulence [1-8]. and,  is the spatial filter width. the statistical distribution function of the mixture fraction performs much better than the commonly used subgrid scale models perform for the mixture fraction variance. therefore, the mixture fraction is considered as the scalar variable [1-8]: dzzpzyy z  1 0 )( ~ )(~ (11) with a simple global reaction rate, non-premixed combustion can be presented by a reactant mass fraction yf( x  ,t), which is described in (4) [1-8]. for non-premixed combustion, additional scalar variable of mixture fraction z ~ ( x  ,t) is needed. the transport equation of mixture fraction is such as: ) ~ () ~ ( ~ z x d x zu x z t ii i i            (12) the above two equations can be combined to be applied in whichever premixed, partially premixed, or mohamed el hadi attia et al. ijeca-issn: 2543-3717. june 2017 page 40 non-premixed flames [1-8]. in the case of simple global reaction rate, progress variable c~ ( x  ,t) is often used instead of f y ~ ( x  ,t) for convenience. in the thin premixed flame, progress variable changes from zero to unity. and with progress variable and mixture fraction, lean reactant mass fraction can be defined by: f y ~ ( x  ,t) = y [ c ~ ( x  ,t), z ~ ( x  ,t)] (13) but for the premixed combustion with coflow of air or pilot product, following equation can be applied to express the lean reactant mass fraction [1-8], f y ~ ( x  ,t )= y . z ~ ( x  , t). [1-c ( x  , t)] (14) y is the mass fraction of fuel in the main fuel/air mixture inflow. for the unburnt reactants z ~ =1 and c~ = 0; for the burnt product z ~ =0 and c~ =1. for homogenous combustion z ~ ( x  , t), the equation (14) is reduced to traditional progress variable equation for non-premixed combustion [1-8]: c ii c i i i c x d xx cu xt c                 )~.()~~( ~ (15) in this work, the pdf method is employed as a subgrid scale (sgs) closure in les of a turbulent nonpremixed combustion of methane-hydrogen/air. the joint probability density function of the sgs scalars is determined via the solution of its modeled transport equation. these les and pdf models are already validated in previous work [3-8]. iv. results and discussion "comparison of ch4 & c3h8" the les models and the pdf approach explained and detailed in previous work [3-8]. then the parameters: axial velocity, temperature and mass fraction of carbon monoxide are also used to control the flame behavior supplied by the ch4 or c3h8. moreover, the presentation and comparison of results are based on normalizing length and velocity by using, respectively, the injector radius (r≡r3) and the inlet bulk velocity of the air (u≡v2). a. axial velocity the results obtained for the axial velocity of methane and propane in the various stations x/r=0.38 and x/r=4.67 are shown in figure 2. the large velocity values are those in the flame zone. it can be observed that the radial profiles of the axial velocity of two fuels have the same tendency, when the difference between the two profiles is small is given by 7%. the high air velocity axial velocity values presented by the peaks in the x/r=0.38 and x/r=4.67 stations, where it is in the flame area. the zone where the velocities are negative presents the recirculation zone generated by sudden widening of the burner and the shear of the delayed flow of the fuel. the increase in speed is justified by the existence of the flame in this region. we can also see negative values in the velocity profiles which show the recirculation regions: in the center of the burner and close to the walls. it is observed that the velocity of the methane is greater than the propane velocity caused by the molar mass of methane below the mass of propane. 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 u / u r/r ch4 c3h8 a) x/r=0.89 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 u / u r/r ch4 c3h8 b) x/r=4.67 figure 2. comparison of the axial velocity between ch4 and c3h8 b. temperature figure 3 shows the difference in temperature distributions between ch4 and c3h8 in a combustion chamber. the radial temperature profiles have the same trend for both fuels with the difference of 5%. the stations x/r=1.57 and x/r=5.20 are situated in the region of the combustion chamber, ie close to the fuel and oxidizer zone, which justifies the decrease in the temperature downstream report. the temperature takes maximum values at the center of the combustion chamber because this zone is the same zone of chemical reactions and these reactions are considered as exothermic reactions. this is called the hot zone where chemical reactions and soot formation generate radiation accumulation, which means an increase in temperature in these areas. in the region of the flame, the temperature profiles show by the peaks in the stations defined by x/r=1.57 and x/r=5.20, and then decrease to equal the wall temperature equal to t=500 k. the values of the mohamed el hadi attia et al. ijeca-issn: 2543-3717. june 2017 page 41 temperature decreases as we move away from the flame area. the observed shift of c3h8 and ch4 temperatures obtained by calculations is owed to the molar masses difference between theses fuels, since the chemical composition is the key parameter in rising combustion temperatures. 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 800 1000 1200 1400 1600 1800 2000 2200 2400 t e m p e ra tu re ( k ) r/r ch4 c3h8 a) x/r=1.57 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 800 1000 1200 1400 1600 1800 2000 2200 2400 t e m p e ra tu re ( k ) r/r ch4 c3h8 b) x/r=5.20 figure 3. comparison of the temperature between ch4 and c3h8 c. mass fraction of carbon monoxide figure 4 shows a comparison between the mass fraction of co resulting from the combustion of methane and propane. the radial profiles of the mass fraction of carbon monoxide present by the stations defined by x/r=3.84 and x/r=7.41. the mass fraction of the chemical species may be provided to behave in the same manner as the temperature. the difference between the two profile curves of the mass fraction of co resulting from ch4 and c3h8 is about 3%. in stations x/r=3.84 and x/r=7.41: the mass fraction values in these stations are relatively high, which is reflected by high combustion efficiency at these stations. it is always found that the fractions are elevated at the center of the combustion chamber because it is the reaction zone where the production of chemical species. in general, the results clearly show that the carbon monoxide co value of propane is high than methane. 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 -0,02 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 y c o r/r ch4 c3h8 a) x/r=3.84 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 -0,02 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 y c o r/r ch4 c3h8 b) x/r=7.41 figure 4. comparison of the mass fraction of co between ch4 and c3h8 v. conclusion in this study, we summarize the validation of the coupled les/pdf models and the effect of the methane and propane input behavior supplied to the combustion chamber, using the fluent-cfd package to perform the calculations. the conclusions of this inquiry are as follows: • the relationship between temperature and carbon monoxide is proportional. • generally, a certain temperature discrepancy between the studied fuels was observed in different stations, which can be owed to the molar masse role played in combustion flame temperatures. • the higher temperature for propane fuel versus methane fuel, at different stations. • the methane velocity is faster than that of propane since the molar mass of methane is smaller than propane. • the ch4 fuel gives a good result reduces the co emission in the species produced by the combustion of c3h8. with these results, we conclude that methane fuel is better than propane, which is cleaner and less harmful to the environment compared to propane. mohamed el hadi attia et al. ijeca-issn: 2543-3717. june 2017 page 42 references [1] m.e.h. attia, “etude de l’effet de l’injection de h2 sur une flamme non prémélangée,” ph.d. thesis, university of tébessa, algeria 2017. [2] f. bouras, “étude de la combustion turbulente via des fonctions de densité de probabilité. . ph.d. thesis, university of hl batna, algeria 2011. [3] f. bouras, m.e.h.attia, f. khaldi and m. siameur. “control of the methane flame behavior by the hydrogen fuel addition: application to power plant combustion chamber,” international journal of hydrogen energy, vol. 42, pp. 8932 8939, 2017. [4] f. bouras, m.e.h. attia, f. khaldi and m. siameur. “control of the methane flame behavior by the hydrogen fuel addition: application to power plant combustion chamber,” proceedings of engineering & technology (pet). ipco-2016, vol. 13, pp.114-118, 2016. http://ipco.com/pet_journal/pet_currentissue.ht ml [5] f. bouras, a. soudani, and m. si ameur, “thermochemistry study of internal combustion engine,” energy procedia, vol.18, pp. 1086–1095, 2012. [6] f. bouras, a. soudani, and m. si ameur, “betapdf approach for large eddy simulation of nonpremixed turbulent combustion, international review of mechanics engineering,” vol. 4, pp. 1096–1099, 2010. [7] c. p. pierce, p. moin, “progress-variable approach for large-eddy simulation of non-premixed turbulent combustion,” journal of fluid mechanics, vol. 504, pp 73–97, 2004. [8] f. bouras, m.e.h. attia and f. khaldi, “entropy generation optimization in internal combustion engine,” environ. process, vol. 02, pp. 233–242, 2015. nomenclature r constant of ideal gas [j.kg -1 .k -1 ] r, r radius [m] t temperature [k] u axial velocity [m.s -1 ] x cartesian coordinate [m] y mass fraction of chemical species [%] greeks symbols α thermal diffusivity [m 2 .s -1 ] ρ density [kg.m -3 ] ɛ dissipation of energy [m 2 .s -3 ] ω arrhenius terms [s -1 ] λ thermal conductivity [kw.m -1 .k -1 ] μ chemical potential, viscosity [kg.m -1 .s -1 ] n number of chemical species indices i,j,k indices of cartesian coordinate http://ipcoco.com/pet_journal/pet_currentissue.html http://ipcoco.com/pet_journal/pet_currentissue.html international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 06-09 ijeca-issn: 2543-3717. june 2018 page 6 economic evaluation analysis of nano-silica ultrafiltration membrane production from sand kurnia 1 , asep bayu dani nandiyanto 1* , riska ismiati 1 , ainnaya annisa 1 , fiona finandia 1 , noor nazmi aulia nissa 1 , rita chintia dewi 1 1 departemen pendidikan kimia, universitas pendidikan indonesia, jl. dr. setiabudi no. 229, bandung 40154, jawa barat, indonisa nandiyanto@upi.edu abstract – the purpose of this research was to analyze the production method of a membrane of silica nanoparticles from an economic perspective. silica nanoparticles are synthesized using a coprecipitation method. briefly, the process consists of immersion, heating, precipitation, washing and drying, and packaging. the parameters used for economic analysis are gross profit margin (gpm), internal rate return (irr), payback period (pbp), cumulative net present value (cnpv), break-even point (bep), and profitability index (pi). the production of this ultrafiltration nanosilica membrane can be done by varying the amount of initial sand from 6 to 14 kg. the production of ultrafiltration nano-silica membranes can be produced in both domestic and microscale industries. to get a very good profit, economic analysis shows the minimum amount of sand used should be more than six kg. this study is very important because the production of ultrafiltration nano-silica membranes have a high potential in the field of economics and will encourage further investigation for the possibility of industrial production of these ultrafiltration nano silica membranes. keywords:economic evaluation, nanoparticles, ultrafiltration membranes, nano-silica. received: 19/05/2018 – accepted: 20/06/2018 i. introduction indonesia is rich in mineral materials that can be used as high-technology applications such as zno, sio2, mgo, al2o3, tio2, etc. in order to utilize the material to the fullest, it is required the support of new technologies namely nanotechnology. silica (sio2) has been utilized in many applications[1-5], and the most familiar usage of silica is for the main ingredient in the glass industry. in this study, the purpose of this research was to analyze the production method of a membrane of silica nanoparticles from an economic perspective. sand was used as a main material for ultrafiltration nano-silica membrane. silica membrane is used to select and reduce the content of fe, mn, and mg elements in water. currently, clean water treatment with membrane technology is a very promising processing process with excellent quality and is also suitable for drinking water treatment in developing countries because the membrane has many advantages [6]. ultrafiltration is a separation process with membranes based on pressure differences, in which the separate components in the liquid are a function of the size and structure of the dissolved components. ultrafiltration membranes are principally used to hold colloids and macromolecules but pass on salt and water particle [7]. in the literature, sand-based silica synthesis using coprecipitation methods can be made with the highest percentage of si content averaging 95.73% [8]. as for the results of the synthesized silica xrd test from pasirmerapi showed that the percentage of the third silica crystal phase of the samples was 56.27% (ph 7), 31.66% (ph 4), and 38.34% (ph 1), and the particle size of each sample is 89.55 ± 5.23 nm (ph 7), 63.55 ± 30.68 nm (ph 4), and 132.26 ± 19.26 nm (ph 1) [9]. the characterization of membrane physical properties showed that the greater the silica addition will create the better membrane filtration quality because the resulting silica grains are so tight to make smaller pores, as shown from the data obtained with the addition of silica of 5 grams to have 0.058 (cm3/min) of smaller flow rate and to get silica membrane density (sio2) of greater than 1.67 (g/cm3) with membrane porosity of 6.67% [10]. silica nanoparticles are synthesized using a coprecipitation method. this method is based on the precipitation of one or more substances together as it passes through its saturation point. coprecipitation is a promising method because the process uses a fairly low temperature so that the time is relatively short, which is about 12 hours. common precipitating agents used in kurnia et al. ijeca-issn: 2543-3717. june 2018 page 7 coprecipitation are hydroxides, carbonates, sulfates, and oxalates. in addition, the coprecipitation process uses easily accessible tools and materials; thus, the synthesis process can be carried out flexibly [9]. in this research, the economic feasibility analyses of the industry with parameters used are gross profit margin (gpm), internal rate return (irr), payback period (pbp), cumulative net present value (cnpv), break-even point (bep) and profitability index (pi) and so on, with production time of 20 years. the production of ultrafiltration nano-silica membrane is done by variation of the quantity of material in order to know the comparison of the results to be obtained. this study performed from 6 to 14 kg of sand. economic analysis showed the interesting results that to get a very good profit, the minimum sand used production should be more than six kg. this suggested that the production of ultrafiltration nano-silica membranes from sand can be produced in home industry and micro-scale production. this research is very important and useful because the production of ultrafiltration nano-silica membranes have a high potential in the economic field. ii. method the data used in this research analysis was adopted from textbooks and scientific articles. the average price of raw materials and some equipments (with specifications) for the production of nanoparticle membranes is taken from the online shopping web to determine the current price of the material. the data obtained was calculated using some economic evaluation parameters. the analysis used the assumptions that the exchange rate value of one usd is equivalent to 13,547 idr. to perform the calculation of economic evaluation parameters, including gpm, irr, cnpv, bep, and pi, we used lang data from reference [11]. iii. results and discussion figure 1.schematic illustration image of the production process of ultrafiltration membrane of silica nanoparticles from sand figure 1 illustrates the production of the filtration membrane contained silica nanoparticles. based on the figure, there are 16 processing steps in the production of the filtration membrane. the raw materials used in this production process are coastal sand, hcl solution, naoh solution, aquadest, poly vinyl alcohol (pva), ethylene glycol poly (peg). in this study, beach sand used from the coast. the first step is immersion (step 1). sand immersion is done using hcl solution. hcl solution is used because hcl is very polar. thus, it can dissolve polar minerals is also high, including silica. the event is in accordance that only solvent type can dissolve a molecule. it means the solvent and the solute molecule interact each other intermolecular by forming a certain bond, thermodynamically. indeed, the solute will be dissolved into the solvent [7]. immersion is done for 12 hours to maximize the dissolution process. the result of the process is washed with pure water (step 2) and dried (step 3). weighing 4 grams of sand (step 4) was done for further reaction using naoh solution (step 5), and the solution was then filtered (step 6). the equation of the reaction is as follows [13]: 𝑆𝑖𝑂2 𝑠 + 2𝑁𝑎𝑂𝐻 𝑎𝑞 → 𝑁𝑎2𝑆𝑖𝑂3 𝑎𝑞 + 𝐻2𝑂(𝑙) the filtering solution plus water (step 7) is then titrated bit by bit with hcl by controlling the ph to approximately 7-8. next, silica gel is discontinued titration for ph 7-8 conditions or continue the titration until the final ph 4-5 and 1-2 (step 8) [14]. 𝑁𝑎2𝑆𝑖𝑂3 𝑎𝑞 + 𝐻2𝑂 𝑙 → 𝐻2𝑆𝑖𝑂3 𝑎𝑞 + 2𝑁𝑎𝐶𝑙(𝑎𝑞) the titration gel was washed using 300-ml pure water (step 9) to remove nacl up to five times[15]. 𝐻2𝑆𝑖𝑂3 𝑎𝑞 + 𝐻2𝑂 𝑙 → 𝑆𝑖(𝑂𝐻)4 𝑎𝑞 silica gel is filtered (step 10) and then dried at a temperature of 80° c (step 11). after the water content is removed, it is crushed with mortar (step 12) to obtain silica powder [8]. the next step is mixing the silica powder that has been obtained with poly vinyl alcohol (pva) solution. poly vinyl alcohol (pva) solution serves as a silica powder adhesive agent to become a solid membrane. furthermore, ethylene glycol (peg) solution was added and stirring was made using a stirrer until the mixture became homogeneous (step 13). the homogeneous mixture is then molded in a water (step 14) and set at room temperature for 30 hours. this is done to eliminate the water content. after 30 hours, the semi-finished solid membrane (still slightly wet) is removed from the mold of the hose, and put it in the oven for 1 hour at 70°c (step 15). use of the 70°c temperature is expected only to remove the moisture present in the solid membrane after drying at room temperature. in addition, to strengthen the solid membranes that have been formed, the oven temperature at higher than 70°c was used. pva and peg in the membrane will melt before forming a strong bond between the silica compound in the silica solid membrane, resulting in the membrane becoming soft. after put it in the oven for 1 hours, the resulting solid membrane was then put in the furnace at 800°c for 5 kurnia et al. ijeca-issn: 2543-3717. june 2018 page 8 hours (step 16). it aims to remove the organic compounds derived from pva and peg and to strengthen the bonds between silica in the membrane. the silica membrane is obtained with pores that are regular and not fragile [16]. to calculate the mass balance of the production process, the following assumptions are used: 1. based on reference [12], to produce membrane filtration of silica nanoparticles. the required materials are beach sand, hcl solution, naoh solution, aquadest, poly vinyl alcohol (pva), poly ethylene glycol (peg). 2. the temperature used in this procedure is 70 and 800°c. 3. the sand used contains 95.33% silica [8]. based on the above assumptions (see table 1), the data shows that the quantity of sand and the quantity of the product affect gpm every year. the highest gpm value is obtained if the quantity of sand reaches 14 kg. the lowest gpm ratio in six kg sand quantity. meanwhile, to calculate other advantages, it takes other parameters that will be explained in the next discussion. quantities of sand (kg) quantities of product (pack) gpm (usd) 6 150 52,395 8 200 69,890 10 250 87,325 12 300 104,790 14 350 122,255 table 1. gross profit margin for various quantities of sands to evaluate the economic analysis we used the following assumptions: 1. the wage of labor is 15,501.58 usd per year. the wage is applied to five workers. 2. the duration of operation of this production is 20 years with total tic of 13,720.84 usd per year. 3. the discount rate for this project is 15% per year. 4. income tax is 10%. 5. the project does not develop with loans from banks. 6. sale of silica membrane is 7.38 usd/pack. figure 2. cnpv/tic curve in accordance to project time with various raw sand productions from the figure 2, it can be seen the relation between cnpv/tic with the duration of membrane filtration production of silica nanoparticles for 20 years. with the price of 7.3817 usd/pack, for once production, it produced 25 packs then the project will be profitable when the main raw material used is more than six kg. to achieve the payback period, production must be done at least five years. likewise, at 6 kg, production using 8, 10, 12, and 14 kg also gave profit. table 2. analysis of irr, bep, and last cnpv on the project type of project (kg) pi to invesment (%) irr (%) bep (pack) last cnpv/tic (%) 6 -0.46 170 -0.5410 -15.08 8 0.61 180 0.1892 2.93 10 1.69 200 0.0805 20.95 12 2.78 210 0.0511 38.97 14 3.86 210 0.0375 56.99 from the above analysis, it can be concluded that the higher the quantity of basic materials creates the higher cnpv to go. in the quantity of six kg of production, the value of pi to investment is negative. it identifies that with the amount of that production, the production is a loss. production was conducted in this study in accordance with the literature. this is because the production of ultrafiltration membranes can achieve remarkable advantages if it is developed on an industrial scale. however, if this research is done by a conventional method, the project will suffer losses. this is because the value of the sale cannot cover the value of expenditure, especially on the tools used for production. iv. conclusion the production of membrane with silica nanoparticles has been evaluated from an economic evaluation study. economic evaluation presents the profitability of this project. to increase the quantity of profit, the number of raw materials was to achieve the standard profits per year that it is required more than six kg of raw materials. we found that profits will be obtained when using the amount of eight kg of raw materials. further development of this research should be undertaken. thus, profits continue to persist or even increase. additional innovation is also required for this product after several years of production. kurnia et al. ijeca-issn: 2543-3717. june 2018 page 9 references [1] n. permatasari, t. n. sucahya, & a. b. d. nandiyanto, agricultural wastes as a source of silica material. indonesian journal of science and technology, vol 1 (1), 2016, pp 82-106. [2] a. b. d nandiyanto, t. rahman, m. a. fadhlulloh, a. g. abdullah, i. hamidah, & b. mulyanti, synthesis of silica particles from rice straw waste using a simple extraction method. iop conference series: materials science and engineering, 128(1), 2016, 012040. [3] a. b. d nandiyanto, r. zaen, r. oktiani, a. g. abdullah, & a. a. danuwijaya, monodispersed and sizecontrollable potassium silicate nanoparticles from rice straw waste produced using a flame-assisted spray pyrolysis. pertanika journal of science & technology, 26 (1), 2018, pp 391-408. [4] a. b. d nandiyanto, n. permatasari, t. n. sucahya, a. g. abdullah, & l. hasanah, synthesis of potassium silicate nanoparticles from rice straw ash using a flameassisted spray-pyrolysis method. in iop conference series: materials science and engineering, 180 (1), 2017, 012133. [5] a. b. d nandiyanto, n. permatasari, t. n. sucahya s. t. purwanti, h. s. h. munawaroh, a. g. abdullah, & l. hasanah, preparation of potassium-posphate-embedded amorphous silicate material from rice straw waste. iop conference series: materials science and engineering, 180(1), 2017, 012138. [6] a. mirwan, v. indriyani, & y. novianty, (). pembuatan membran ultrafiltrasi dari polimer selulosa asetat dengan metode inversi fasa. konversi, 6(1), 11-16. [7] piluharto. kajian sifat fisik film tipis nata de coco sebagai membran ultrafiltrasi. jurnalilmudasar, 4, 2017, 55 2003. [8] s. hadi, munasir, & triwikantoro. sintesis silika berbasis pasir alam bancar menggunakan metode kopresipitasi. jurnalfisikadanaplikasinya, 7 (2), 2011, pp 1-10. [9] n. qisti & n. s. indrasti, optimization of process condition of nanosilica production by hydrothermal method. iop conference series: materials science and engineering, 162 (1), 2016, 012036. [10] a. mufid, & e. hastuti, karakterisasi sifat fisis membran padat silika (sio2) untuk filtrasi air laut menjadi air tawar. jurnal neutrino, 6(1), 2013, pp 40-46. [11] a. b. d nandiyanto, and ristiragadhita. evaluasiekonomi perancanganpabrik kimia. bandung: upi press (2018.) [12] l. yogantari, & s. sulistiyani, purifikasi silika dari pasir vulkanik gunung merapi sebagai bahan baku sel fotovoltaik. jurnal kimia dasar 4(2), 2016, pp 22-127. [13] r. t. bakri, utari, & i.p. sari. kaolin sebagai sumber sio2 untuk pembuatan katalis ni/sio2: karakterisasi dan uji katalis pada hidrogenasi benzena menjadi siklohesana.makara saims, 12(1), 2008, pp 37-43. [14] b. gu, d. ko, s. ahn, d. c. hyun, h. k. lee, & j. kim, synthesis of high purity silica from low cost water glass via sol–gel process and soxhlet extraction. journal of solgel science and technology, 82(3), 2017, pp 675-681. [15] kurniati. ekstraksi silika white powder dari limbah padat pembangkit listrik tenaga panas bumi dieng, upn press, surabaya (2009). [16] k. pratiwi, & r. gunawan, (pembuatan membran silika dari fly ash batubara untuk penurunan intensitas warna dari limbah cair industri sarung samarinda. jurnalatomik, 3(1), 2018, pp 31-38. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 15-17 ijeca-issn: 2543-3717. december 2017 page 15 engineering and economic analysis of the synthesis of fluoride tin oxide film production asep bayu dani nandiyanto, tsabbit aidil aziz, ruslan fariansyah departemen kimia, universitas pendidikan, jl. dr. setiabudi no 229, bandung 40154, jawa barat, indonesia nandiyanto@upi.edu abstract – the purpose of this study was to analyze the fluoride tin oxide (sno2/f) production in home-scale industry in engineering point of view and economic evaluation perspective. this material is considered due to its wide range of energy-related applications. evaluation of the sno2/f production in engineering perspective is conducted from the selection of the most economical process, mass balance calculation, to the adaptation in the commercially available apparatuses. evaluation of the production from the economic point of view is done by calculating economic parameters: gross profit margin, internal rate return, payback period, cummulative net present value, profitability index, and breakeven point. in short of the production process, we used the pure tin (as the metal precursor) and ammonium fluoride (as the source of flouride for doping). the engineering point of view showed that the process is able to produce conductive glass that can be used as the active electrode substrate in the solar cell. economic evaluation showed that the process is profitable, confirmed by the positive values from all economic parameters. however, for some cases that are compared to the market and the local bank interest, the process is not attractive for investor. thus, to make them attractive, support from government or corporate social responsibility is required. keywords: energy, tin oxide production, conductive glass received: 01/12/2017 – accepted: 20/12/2017 i. introduction recently, energy has become a major problem in many aspects. one of the objects related to energy is how to manage the source of energies and materials for energy conversion or transfer. in the field of solar energy, solar rays are used to produce drinking water [1], or to produce electrical energy [2] and thin layers of different materials are used to produce conductive glass plates and semiconductor [3-4] tin oxide is one of the attractive energy-related materials because this material has a wide band gap with a low n-type resistivity (1023 v.cm) and high transparency (90%) in the visible region. interestingly, resistivity of this material can be reduced further to the range of 1024 v.cm by additional doping, which is suitable for application in thin film solar cells. tin oxide has also been known in the fabrication of gas sensors due to sensitivity of its surface conductance to gas adsorption [5, 6]. this makes tin oxied has been well-documented from preparation techniques to the control of properties [7, 8]. for example, fabrication techniques for preparing tin oxide has been well reported, including dip coating, evaporation, sputtering, chemical vapor deposition, and spray pyrolysis [9]. many raw materials for tin oxide has been also reported, such as tin chloride (e.g. sncl2 [10] and sncl4 [11] ) and tin fluoride. the tin material was also combined with several doping component [12], such as antimony (sb), chloride (cl) [13,14], bromide (br) [11-15], and fluoride (f) [11]. some reports showed that fluoride is the most effective dopants [11, 16-19]. although synthesis of tin oxide is well documented, the papers are discussed for the laboratory scale production only. no information about economic evaluation is found, while this information is important. this is because economic evaluation relates to the further studies for scaling up production. based on our previous studies on the mathematical analysis[20, 21], the purpose of this study was to analyze the engineering point of view and economic evaluation of the flourinet in oxide (sno2/f) production for home-scale industry. mailto:nandiyanto@upi.edu asep bayu dani nandiyanto et al. ijeca-issn: 2543-3717. december 2017 page 16 ii. method in this study, we analyzed the feasibility study on the fabrication of sno2/f in home-scale industry. the feasibility study was done in two ways: engineering evaluation and economic analysis. evaluation of the sno2/f production in engineering perspective is conducted from the selection of the most economical process, mass balance calculation, to the adaptation in the commercially available apparatuses. evaluation of the production from the economic point of view is done by calculating economic parameters: gross profit margin (gpm), internal rate return (irr), payback period (pbp), cumulative net present value (cnpv), profitability index (pi), and breakeven point (bep). iii. results and discussion iii.1 engineering evaluation figure 1. chart of sno2.f production figure 1 shows the process diagram for thehomescale production of sno2/f. the manufacturing process described with some steps. first step,tin metal was mixed and dissolved in hydrochloric acid and nitric acid at temperature of 80-100c.[22] the process was maintained until all acid component evaporates (forming sncl2 yellow precipitated).[23,24] then,the evaporated component was added by ethanol and ammonium fluoride solution for oxidation process for about 2 hours. the process was maintained in the same temperature condition.[25]the final product yields a solution of sno2.f in ethanol and then packed in 1-liter bottle for sale to markets.during the process, the following chemical reactions happen: for dissolution process: sn sn 2+ for formation chloride tin: sn 2+ + 2 cl  sncl2 for oxidation process: sncl2+ 2c2h5oh + nh4f + 8 o2sno2/f + 4co2 + ½ n2 + 8 h2o + cl2 based on the diagram process in figure 1, several assumptions are added: 1. the conversion rate in all reactions is 100%. 2. during the process, ethanol is oxidized and losses about 20% . 3. then, using analysis of commercially available apparatus in market for home-scaling industry, the product can be generated in one batch process is 933 ml of concentrated sno2/f. iii.2 economic evaluation to ensure the economic evaluation, the analysis of gpm firstly evaluated. the gpm value for the 1 year sno2/f home-scale production can reach more than 220 million rupiahs. or, using exchange rate for 1 usd = 10,000 rp, we can get the gpm value can reach more than usd 22,000. calculation with the initial raw material, the profit can reach about 200%. the percentage of profit was calculated from the comparison between the results of products sales with purchased raw materials needed for the production.based on the results of gpm calculation, the production of sno2/f is quite profitable. further analysis of the process is shown in figure 2.this figure shows the cnpv analysis of sno2/f production. the curve shows the relationship between the value of cnpv and total investment cost (tic) in the operating years (20 years of production). the result showed that the initial time can result negative cnpv. but, after pbp years (about 4 years), the project is profitable. the calculations for pi, irr, bep and last cnpv / tic are 10%, 68%, 1, 3.51%, respectively. based on the data, the pi may explain that this production project is not feasible to proceed from a pi value of only 10% or 0.1, where the minimum eligibility value of a project is greater than 1 [23]. irr value describes the amount of return that will be obtained from the total value of investment that has been issued as the main capital. thus, with an irr of 68%, the amount of returns that will be obtained in the future is quite large. based on calculations in the production of sno2.f, the value of bep obtained is 1 unit. this value mean the minimum quantity of products that can be produced is just 1 unit product per day. further, last cnpv / tic explained that in 20 years of production value of the rate of profit from the tic issued is 3.51%. compared to local bank interest at20 october 20, the value is relatively lower. local bank interest shows a value of 4.35% [24].thus, this project is relatively not interesting for investor. asep bayu dani nandiyanto et al. ijeca-issn: 2543-3717. december 2017 page 17 figure 2. correlation between cnpv graph in one year of production iv. conclusion the production of sno2/f in the home-scale industry has been evaluated from engineering and economic perspective. based on the project, the engineerig point of view shows the possibility for the production of sno2/f in home scale. economic evaluation showed that the project is profitable, confirmed by the positive values from all economic parameters. however, compared to the market and the local bank interest, the process is not attractive for investor. thus, to make them attractive, support from government or corporate social responsibility is required. references [1] a. khechekhouche, a. boukhari, z. driss, n. benhissen. seasonal effect on solar distillation in the el-oued region of south-east algeria. vol 2; issue 1, 2017, pp 42-45. [2] m. maamir, a. betka, h. aboub. modeling and simulation of energy management hybrid sources system composed of solarpv and battery. international journal of energetica, vol1; issue1, 2016; pp 12-19. [3] achour rahal, said benramache, boubaker benhaoua, preparation of n-type semiconductor sno2 thin films. journal of semiconductors.vol 2 issue 2. 2013 https://doi.org/10.1088/16744926/34/8/083002 [4] nandiyanto, a. b. d., sofiani, d., permatasari, n., sucahya, t. n., wiryani, a. s., purnamasari, a., rusli, a.,& prima, e. c. photodecomposition profile of organic material during the partial solar eclipse of 9 march 2016 and its correlation with organic material concentration and photocatalyst amount. indonesian journal of science and technology, 1(2), 2016, pp 132-155. [5] britt, j., &ferekides, c. thin‐film cds/cdte solar cell with 15.8% efficiency. applied physics letters, 62(22), 1993, pp 2851-2852. [6] das, s. k., & morris, g. c. preparation and properties of electrodeposited indium tin oxide/sno2/cdte and indium tin oxide/sno2/cds/cdte solar cells. journal of applied physics, 73(2), 1993, pp 782-786. [7] watson, j., ihokura, k., & coles, g. s. the tin dioxide gas sensor. measurement science and technology, 4(7), 1993, pp 711. [8] yoo, d. j., tamaki, j., park, s. j., miura, n., &yamazoe, n. h2s sensing characteristics of sno2 thin film prepared from sno2 sol by spin coating. journal of materials science letters, 14 (19), 1995, pp 1391-1393. [9] dawar, a. l., & joshi, j. c. semiconducting transparent thin films: their properties and applications. journal of materials science, 19(1), 1984, pp 1-23. [10] jordan, j. f., & albright, s. p. large-area cds/cdte photovoltaic cells. solar cells, 23(1-2), 1988, pp 107-113. [11] agashe, c., & major, s. s. effect of f, cl and br doping on electrical properties of sprayed sno 2 films. journal of materials science letters, 15(6), 1996, pp 497-499. [12] morris, g. c., &mcelnea, a. e. fluorine doped tin oxide films from spray pyrolysis of stannous fluoride solutions. applied surface science, 92, 1996, pp 167-170. [13] shanthi, e., dutta, v., banerjee, a., & chopra, k. l. (1980). electrical and optical properties of undoped and antimony‐doped tin oxide films. journal of applied physics, 51(12), pp 62436251. [14] unaogu, a. l., &okeke, c. e characterization of antimonydoped tin oxide films prepared by spray pyrolysis. solar energy materials, 20(1-2), 1990, pp 29-36. [15] abass, a. k. electrical and optical properties of chlorine doped sno2 coatings. solid state communications, 61(8), 1987, pp 507510. [16] mohammad, m. t., & abdul‐ghafor, w. a. properties of fluorine‐doped sno2 films prepared by the spray pyrolysis technique. physica status solidi (a), 106(2), 1988, pp 479-484. [17] cowache, p., lincot, d., &vedel, j. cathodic codeposition of cadmium telluride on conducting glass. journal of the electrochemical society, 136(6), 1989, pp 1646-1650. [18] afify, h. h., momtaz, r. s., badawy, w. a., & nasser, s. a. some physical properties of fluorine-doped sno 2 films prepared by spray pyrolysis. journal of materials science: materials in electronics, 2(1), 1991, pp 40-45. [19] grosse, p., schmitte, f. j., frank, g., &köstlin, h. preparation and growth of sno2 thin films and their optical and electrical properties. thin solid films, 90(3), 1982, pp 309-315. [20] andika, r., & valentina, v. techno-economic assessment of coal to sng power plant in kalimantan. indonesian journal of science and technology, 1(2), 2016, pp156-169. [21] nandiyanto, a. b. d. mathematical approximation based on thermal analysis curves for calculating kinetic parameters of thermal decomposition of material.journal of engineering science and technology, 12, 2017, pp 76-90 [22] surahman, h., krisnandi, y. k., &gunlazuardi, j. preparation and characterization of transparent conductive sno2-f thin film deposited by spray pyrolysis: relationship between loading level and some physical properties. procedia environmental sciences, 28, 2015, pp 242-251. [23] vera, d., carabias, j., jurado, f., & ruiz-reyes, n. a honey bee foraging approach for optimal location of a biomass power plant. applied energy, 87(7), 2010, pp 2119-2127. [24] agusman. bank indonesia mempertahankan suku bunga kebijakan: ekonomi global membaik, pemulihanekonomi domestik berlanjut. jakarta :departemenkomunikasi. no.19/79/dkom. 2017 [25] riveros, r., romero, e., & gordillo, g. synthesis and characterization of highly transparent and conductive sno2: f and in2o3: sn thin films deposited by spray pyrolysis. brazilian journal of physics, 36(3b), 2006, pp 1042-1045. http://iopscience.iop.org/journal/1674-4926 http://iopscience.iop.org/journal/1674-4926 http://iopscience.iop.org/journal/1674-4926 https://doi.org/10.1088/1674-4926/34/8/083002 https://doi.org/10.1088/1674-4926/34/8/083002 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 2. 2018 page 29-33 ijeca-issn: 2543-3717. december 2018 page 29 effect of the preheating inlet air on the g222 fuel combustion mohammed el hadi attia 1 , zied driss 2 and abderrahmane khechekhouche 3 1department of physics, faculty of science, university of el oued, 39000 el oued, algeria 2laboratory of electro-mechanic systems (lasem), enis, university of sfax, tunisia 3renewable energy development unit in arid zones (uderza), university of el-oued, algeria attiameh@gmail.com abstract – in this paper, a numerical simulation is developed to study the preheating effect of the air in a three-dimensional cylindrical combustion chamber using the fluent-cfd code. particularly, we are interested on the calculation of the characteristic parameters such as the axial velocity, the temperature and the mass fraction of carbon monoxide. this study consists of a special treatment of mathematical models. the considered approaches resolve the governing equations of system. the main objective of this work is to study the behavior of the parameters considered previously during the variation of the air inlet temperature. the obtained results show that the variation of the inlet temperature presents a direct effect on the considered parameters. keywords: premixed combustion; turbulence; fuel g222; preheating, computational fluid dynamics. received: 02/09/2018 – accepted: 25/11/2018 i. introduction turbulent combustion is found in industry most often in gas burners, turbojets and rocket engines. turbulence plays an essential role in mixing as quickly as possible the gases present. it is essentially due to the strong gradients of velocity that exist at the air entrance [1, 2]. this fact is encountered in the industrial sector. as an example, we can found it in the burners used to convert the stored energy in the molecular bonds of fuels into thermal energy and then into mechanical energy. thus, controlling combustion is a vital capacity in the development of new industrial systems, such as propulsion systems [3, 5]. one of the challenges that industry must face today in order to accompany technological development is to reduce the impact of combustion on the environment. this impact is manifested in the release of polluting chemical species, of which oxides of nitrogen (nox) and gases participating in the greenhouse effect, such as carbon oxides, co and co2. this challenge forces engine manufacturers to propose ever more innovative solutions to achieve the objectives set. several works aim to minimize these emissions by introducing techniques such as lean burning, combustion of fuels of renewable origin and which does not contain carbon. hydrogen h2 and methane ch4 are two important fuels from an energy point of view. ch4 has a significant practical application in the energy sector since it is the major constituent of natural gas. hydrogen is a clean, carbon-free fuel. its combustion produces only water and a reduced amount of nitrogen oxides. indeed hydrogen is not a primary energy but an energy vector [6]. the effect of preheating air in a combustion chamber provides significant energy savings and reduces fuel consumption, coupled with co reduction techniques, and has found applications in several sectors industrial sectors. the main objective of this work is to present a 3d thermo chemistry study in a cylindrical combustion chamber fed by g222. in these conditions, the mixture named g222 is based on 77% of methane and 23% of hydrogen. starting with injection of g222 and air at the same temperature equal to t=300 k, the temperature of the fuel is then fixed to the previous value and the temperature inlet of the air is varied at t=300 k, t=500 k, t=750 k and t=900 k. the simulation was carried out by the cfd code fluent. the obtained results show that the preheating of the air presents a direct impact on the parameters of the combustion. ii. mathematical formulation of the problem the equilibrium equations of the aero-thermochemistry used for the combustion study with a compressible flow [5-8] are defined by the continuity equation: 0)~(       i i u xt   (1) the momentum equations are written as follows: mailto:attiameh@gmail.com m.e.h. attia et al ijeca-issn: 2543-3717. december 2018 page 30 i ij j jiji i ji i i xx p uuuu x uu xt u                  )]~~([)~~( ~ (2) the energy equation is written as follows: ijj i ii i i i u xt p huhu x hu x h t                )] ~~([) ~~( ~ (3) the species equations are written as follows: ffifi i fi i f yuyu x yu x y t           )] ~~([) ~ ( ~ (4) where i = 1, 2, 3 and j = 1, 2, 3. the thermodynamic state is written as follow: trp m ~  (5) in these equations, the unresolved reynolds stresses )~~( jiji uuuu  require a subgrid scale turbulence model. the unresolved species fluxes ) ~~( fifi yuyu  and the enthalpy fluxes ) ~~( huhu ii  require a probability density function (pdf) approach. the filtered chemical reaction rate is characterized by f . the les models and the pdf approach are explained and detailed in our previous work [5-8]. iii. experimental configuration as presented in figure 1, the considered combustion chamber shows a cylindrical shape with a radius r4=61 mm and a length l=1 m fed by two coaxial jets. the central jet has an internal radius r1=31.57 mm and an external radius r2=31.75 mm, to inject the fuel g222 with a mass flow q1=7.2 g/s at a temperature t1=300 k. the annular jet presents an internal ray r3=46 mm, injecting a preheated air a mass flow rate q2=137 g/s at different temperatures equal to t=300 k, t=500 k, t=750 k and t=900 k. the combustion chamber is pressurized at 3.8 atm with a isothermal temperature equal to t=500 k [9-14]. moreover, the presentation and comparison of results are based on normalizing length and velocity by using, respectively, the injector radius r≡r3 and the inlet bulk velocity of the air u≡v2. figure 1. geometrical arrangement of the combustion chamber. iv. results and discussions the equations of the balance sheet are solved by the finite volume method. the mesh used is of the hybrid type so that prisms are chosen at the centers and parallelepipeds in the rest of the field of study of the combustion chamber. iv.1. axial velocity figure 2 illustrates the radial profiles of the average axial velocity obtained by numerical calculation. according to these results, it has been observed that the high velocity values are located in the area of the flame presented by the peak in both stations defined by x/r=0.14 and 0.38. indeed, these profiles show the same pattern when the production of the mixture layer presented by the peak is located approximately in the same position. the curves represent some change in the average velocity in the nonpremixed cylindrical combustion chamber when the radial distance changes from x/r=0.14 to x/r=0.38. indeed, it has been noted that the different profiles are superimposed identically with a slight decrease of the average velocity which is affected by the preheating of the air. in these conditions, the maximum value of the axial velocity is equal to v=23 m.s -1 for t=300 k. however, it is equal to v=20 m.s -1 for t=750 k. figure 3 shows a 2d view of the axial velocity distribution in the non-premixed cylindrical combustion chamber confined by two coaxial g222/air jets. in these cases, the iso-surfaces of the temperature are defined with the inlet conditions characterized by an air temperature equal to t=750 k and a g222 fuel temperature equal to t=300 k. we consider that high values of velocity are located in the flame zone, however, the velocity decrease when we go far to this region. 0,0 0,2 0,4 0,6 0,8 1,0 0 5 10 15 20 25 a x ia l v e lo c it y ( m /s ) r/r t=300 k t=500 k t=750 k t=900 k (a) x/r=0.14 0,0 0,2 0,4 0,6 0,8 1,0 0 5 10 15 20 25 a x ia l v e lo c it y ( m /s ) r/r t=300 k t=500 k t=750 k t=900 k (b) x/r=0.38 figure 2. radial profiles of the axial velocity. m.e.h. attia et al ijeca-issn: 2543-3717. december 2018 page 31 (a) x/r=0.14 (b) x/r=0.38 figure 3. distribution of the axial velocity. iv.2. temperature figure 4 illustrates the temperature profiles in the combustion chamber during a non-premixed combustion of the g222. according to these results, these profiles present the same appearance. in these conditions, the highest value of the temperature appears in the vicinity of the flame areas and it is equal to t=2300 k. however, it is very low near the burner wall, where the temperature is equal to t=500 k. the area of the flame is a zone of chemical reaction of the fuel with air, so this source of heat is generated by the chemical reactions caused by the rupture of carbon bonds and hydrogen, oxygen to produce h2o, co2, co and oh. the preheating zone defined by t=750 k is located at x/r=0.14. the peak value characterized by t=1950 k at the position r/r=0.45. however, at x/r=0.38 and r/r=0.45, the temperature is equal to t=2000 k. figure 5 shows a 2d view of the temperature distribution in the non-premixed cylindrical combustion chamber confined by two coaxial g222/air jets. these iso-surfaces of the temperature are defined with the inlet conditions characterized by an air temperature equal to t=750 k and a g222 fuel temperature equal to t=300 k. the results show that the high temperature is produced by the combustion. whereas, high values of temperature are located near the flame region. 0,0 0,2 0,4 0,6 0,8 1,0 400 600 800 1000 1200 1400 1600 1800 2000 2200 t e m p e ra tu re ( k ) r/r t=300 t=500 t=750 t=900 (a) x/r=0.14 0,0 0,2 0,4 0,6 0,8 1,0 400 600 800 1000 1200 1400 1600 1800 2000 2200 t e m p e ra tu re ( k ) r/r t=300 k t=500 k t=750 k t=900 k (b) x/r=0.38 figure 4. radial profiles of the temperature. (a) x/r=0.14 m.e.h. attia et al ijeca-issn: 2543-3717. december 2018 page 32 (b) x/r=0.38 figure 5. distribution of the temperature. iv.3. co fraction mass figure 6 presents the mass fraction of the carbon monoxide co produced during the combustion of the fuel g222. according to these results, it has been noted that the mass fraction of the co presents high values in the middle of the combustion chamber and decreases until reaching the zero value in the vicinity of the walls of the combustion chamber. indeed, it has been observed that the mass fraction of the co decreases when moving away from the inlet of the combustion chamber near the flame area. this fact can be explained by the secondary reaction of the co with o2 to become co2. these results present the same distribution founded for the temperature. this fact means that the region of the flame is rich in co, produced by the combustion. the comparison between these curves confirms that the choice of the air inlet temperature equal to t=750 k can improve the co reduction. in these conditions, the co mass fraction is equal to mco=0.07 at the position defined by x/r=0.14 and r/r=0.35. however, it is equal to mco=0.05 at the position defined by x/r=0.38 and r/r=0.55. figure 7 shows a 2d view of the distribution of the carbon monoxide co mass fraction in the non-premixed cylindrical combustion chamber confined by two g222/air coaxial jets. these iso-surfaces correspond to the inlet conditions characterized by an air temperature t=750 k and a g222 fuel temperature equal to t=300 k. according to these results, it has been observed that the maximum value of the co mass fraction appears near the axis. elsewhere, it presents a very weak value, particularly near the lateral surface. we observe that the co profiles have same tendency with the temperature. because the co is produced by the combustion of ch4 found in g222. 0,0 0,2 0,4 0,6 0,8 1,0 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 m a s s e f ra c ti o n o f c o r/r t=300 k t=500 k t=750 k t=900 k (a) x/r=0.14 0,0 0,2 0,4 0,6 0,8 1,0 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 m a s s e f ra c ti o n o f c o r/r t=300 k t=500 k t=750 k t=900 k (b) x/r=0.38 figure 6. radial profiles of the co mass fraction. (a) x/r=0.14 m.e.h. attia et al ijeca-issn: 2543-3717. december 2018 page 33 (b) x/r=0.38 figure 7. distribution of the co mass fraction. v. conclusions this paper presents a numerical simulation to model the preheating effect in a non-premixed combustion powered by the fuel g222. in this work, the phenomenon of the injected air preheating is considered with injection of the fuel g222 at a constant temperature equal to t=300 k and for different air inlet temperature equal to t=300 k, t=500 k, t=750 k and t=900 k. the obtained results allow us to the following remarks: • the ideal and suitable air temperature which gives a good and comfortable compromise to drive combustion studied and less loss of energy is equal to t=750 k. also, we confirm that the temperature of the fuel is equal to t=300 k. • the carbon monoxide co emissions are reduced in the case of the intake conditions characterized by the air temperature equal to t=750 k and the fuel temperature equal to t=300 k. references [1] f. bouras, a. soudani and m. si-ameur, simulation aux grands échelles de la combustion turbulente couplée à des fonctions densités de probabilité, proceeding of international conference on energetics and pollution, 2007, pp. 45-50. [2] f. tabet, b. sarhb and i. gokalp, hydrogen–hydrocarbon turbulent non-premixed flame structure, international journal of hydrogen energy, vol.34, 2009, pp. 5040–5047. [3] b. x. liu, p. sun, h. q. ning, j. meng, h. huang, “simulation of heat transfer by fluid structure interaction of diesel engine block coolant jacket”, journal of mechanical engineering research and developments, vol. 38, no. 2, 2015, pp. 36-42. [4] f. bouras, a.soudani, and m. si ameur, thermochemistry study of internal combustion engine, energy procedia, vol.18, 2012, pp. 1086–1095. [5] f. bouras, a. soudani, and m. si ameur, beta-pdf approach for large eddy simulation of non-premixed turbulent combustion, international review of mechanics engineering, vol. 4, 2010, pp. 1096–1099. [6] c. p. pierce, p. moin, progress-variable approach for large-eddy simulation of non-premixed turbulent combustion, journal of fluid mechanics, vol. 504, 2004, pp 73–97. [7] j. h. tang, y. y. zuo, s. y. bei, & k. y. wang, numerical calculation and analysis of automobile aerodynamic noise based on large eddy simulation, journal of mechanical engineering research and developments, vol. 39, no. 3, 2016, pp. 607-616. [8] f. bouras, m.e.h. attia and f. khaldi, entropy generation optimization in internal combustion engine, environ. process, vol. 02, 2015, pp. 233–242. [9] f. bouras, a. soudani, and m. si ameur, large eddy simulation for lean premixed combustion, canadian journal of chemical engineering, vol. 91, 2013, pp. 231– 237. [10] f. bouras, a. soudani, and m. si ameur, numerical study of the turbulent flow inside an oracles configuration, trans. asme, journal of appllied mechnics, vol. 79, 2012, pp. 510-514. [11] f. bouras, numerical study of turbulent structures for lean premixed prevaporized combustion, journal of applied mechanics and technical physics, vol. 55, 2014, pp. 614– 626. [12] f. bouras, m.e.h. attia, f. khaldi and m. si-ameur. control of the methane flame behavior by the hydrogen fuel addition: application to power plant combustion chamber, international journal of hydrogen energy, vol. 42, 2017, pp. 89328939. [13] m.e.h. attia, z. driss, a. khechekhouche. numerical study of the combustion of ch4-c3h8/air: application to a combustion chamber with two coaxial jets, international journal of energetica, vol. 2, no. 2, 2017, pp. 38-42. [14] m.e.h. attia, a. khechekhouche, z. driss. numerical simulation of methane-hydrogen combustion in the air: influence on combustion parameters, indian journal of science and technology, vol. 11, no. 2, 2018, pp. 1-8. i. introduction ii. mathematical formulation of the problem iii. experimental configuration iv. results and discussions v. conclusions references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 01-11 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 1 predictive study on the application of the soweto wind turbine results in the coastal region of south africa t. sithole 1* , v.r. veeredhi 2 , t.sithebe 2 1 department of electrical engineering, university of south africa, south africa 2 department of mechanical engineering, university of south africa, south africa *corresponding author e-mail: sitholetshepo7@gmail.com abstract – this study evaluates the performance of three wind turbine prototypes (prototypes 1, 2, and 3) in soweto, south africa, by analyzing their monthly energy generation under different time of day/month conditions. prototype 3 emerges as the most efficient, generating 39.5 w at a wind speed of 1.17 m/s and projecting a maximum of 40 kwh per month. building upon these results, a predictive study examines the feasibility of implementing the same technology in coastal regions, specifically gqeberha, where stronger winds prevail. utilizing empirical data from soweto, the study forecasts an improved energy output of up to 54.3 w at a wind speed of 5.16 m/s (18.6 km/h) and up to 100 kwh per month. the findings highlight the potential benefits of utilizing wind turbine technology in coastal areas, contributing valuable insights to renewable energy system development in similar geographical contexts. keywords: predictive study, coastal regions, soweto, port elizabeth result. received: 10/02/2023 – revised: 11/03/2023 – accepted: 03/04/2023 i. introduction in the past, south africa heavily relied on electricity generated from fossil fuels like oil and coal, which has limited the country's overall electricity supply. however, south africa possesses abundant solar resources, with an average of 2,500 hours of sunshine per year and radiation levels ranging from 4.5 to 6.6 kwh/m 2 . this places south africa among the top three countries in the world in terms of solar potential. additionally, the country has a significant wind power potential, estimated at 67,000 gw, which proves to be competitive alongside its solar potential [1]. wind energy is a viable source of power in regions with consistent and strong winds. south africa's climate offers favorable conditions for substantial wind energy production, particularly in the coastal regions of the eastern and western capes. in 2014, the first major wind farm in south africa began operating, marking a significant milestone in the country's wind energy sector. according to the south african wind energy association (sawea) report, there are currently 33 wind farms in the country, with 22 fully operational and 11 under construction [2]. amidst the increasing global demands for decarbonization and sustainability, south africa has embraced the proliferation of wind energy. this support stems from the recognition of the risks posed by climate change to various resources in the country, including water security, agriculture, and shorelines. the growing renewable power sector not only addresses these challenges but also reduces the country's reliance on coal, aligning with international policies and lowering the demands for coal-related ventures. the impact of wind energy spill-overs is particularly evident in the eastern cape province, which has secured 51% of south africa's wind farm allotments, benefiting the impoverished region. furthermore, major banks have become hesitant to provide financial support for coal-related projects, https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 2 indicating a shift in capital spending towards the development of high-tech wind turbines on wind farms [3-8]. moreover, the use of fossil fuels in the generation of electricity contributes significantly to greenhouse gas (ghg) emissions, which further contributes to climate change [9, 10]. according to [11], utilizing renewable energy as an alternative energy source will help reduce environmental problems, essentially ghg emissions and air pollution. in this article, presentation will be done on results of the 7 rotor-blade prototype (design-3) wind turbine that was optimally designed and eventually implemented and tested in residential area in soweto, johannesburg, south africa. a predictive study will be done using the design 3 results to predict the possible implementation of the same technology in the high gust area of south africa. ii. selection of appropriate hardware and implementation in this section, the selection and implementation of the required hardware will be discussed. the following hardware components were selected: ac-dc inverter, anemometer, storage batteries, rotor coupling hub, threephase ac permanent magnet generator, battery regulator/ charge controller, ac cabling and monitoring devices. . ii.1. windy boy vertiv inverter a windy boy inverter as in figure 1, has 93% to 95% efficiency [12], and the cost of this electronic device is approximately r800.00. it has the ability to protect itself from spikes, surges and over voltages. it can be used for both off-grid and grid tied applications. figure. 1. windy boy vertiv inverter [12] ii.2. ut363-b anemometer this instrument was acquired to measure wind and temperature for the applications at the test household in soweto. the ut363-bt mini anemometer is a mini wind speed and temperature tester. this lightweight device is equipped with the latest magnetic sensing technology, and directly displays the airflow speed on an lcd screen. bluetooth function can be added for data transfer and analysis by means of the ienv cell phone app; this can be downloaded from google play or apple store. the ut363-bt mini anemometer was taken for calibration at a south african national accreditation system (sanas) accredited laboratory and this calibration cost approximately r550.00. figure 2 shows a ut363-bt anemometer. figure. 2. ut363 wind anemometer ii.3. storage batteries storage of power is an important factor in wind turbine use. these battery store the generated energy of the turbine, and then the stored energy is sent through an electronic regulator to the inverter for output supply. figure 3, illustrates two 12v 100a/h vrla batteries coupled in series, which suited system implementation. each battery cost approximately r850,00. the batteries can be connected in series or parallel depending on the wind turbine charge controller specification. figure. 3. 2x 12v 100 ah vrla batteries coupled to the soweto swt t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 3 ii.4. rotor coupling hub used for the soweto project a rotor hub was purchased from a chinese supplier and this was used to couple the wind turbine blade to the generator shaft. the rotor hub is the component that usually holds the blades and connects them to the main shaft of the wind machine. it is a key component not only because it holds the blades in their proper position for maximum aerodynamic efficiency, it also rotates to drive the generator. hubs come in many different shapes and configurations, mostly dependent on the type of generator used and the design of the rotor blades as shown in figure 4. figure. 4. 7-blade wind turbine blade hub used for soweto project ii.5. three phase ac permanent generator in terms of the generators for wind-power application, there are different concepts in use today. the major distinction among them is made between fixed speed and variable speed wind turbine generators. in the early stage of wind power development, fixed-speed wind turbines and induction generators were often used. figure 5, shows permanent magnetic synchronous generators (pmsgs) used for the soweto project. figure. 5. soweto’s three-phase pmsg used. ii.6. battery regulator / charge controller the battery regulator/ charge controller essentially forms a protection against overcharging a bank of batteries. it also acts as monitoring system when the batteries are fully charged; the controller sends a full energy stored code from the charge controller to the load [13]. figure 6, shows the charge controller connected to the battery bank during testing in soweto. figure. 6. charge controller connected to the batteries during testing in soweto. ii.7. ac cabling routing for the soweto swt project the importance of neat cabling in wind turbines should be considered when constructing a system. figureure 7, shows a medium ac cable running from the wind turbine tower to the charge regulator during testing in soweto. the anticipated current delivery of the cable is a maximum of 50 amps. figure. 7. three-phase ac medium cabling routing during testing in soweto ii.8. 7designed rotor blades for prototype 3 in my recent 2022 article [14] showed the blade design and optimisation using bem theory. different blade design aspects were taken into consideration while adapting and developing further blade designs in the https://www.sciencedirect.com/topics/engineering/wind-machines https://www.sciencedirect.com/topics/engineering/aerodynamic-efficiency https://www.sciencedirect.com/topics/engineering/rotor-blade t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 4 soweto project. the finished blade designs for prototype 3 when implemented are shown in figure 8. the design procedure and final specifications were further detailed in [14]. figure 8. prototype 3 (design 3) 7rotor blades for soweto swt project ii.9. developed wind turbine tower for the soweto project wind turbine towers are usually made out of concrete, steel (tubular), or lattice (steel). their purpose is to create balance within the structure of the wind turbine whenever there is movement of wind. it is known that the greater the height of the wind tower, the better the wind turbine will perform. figure 9, shows a chosen wind turbine tower designed for this project. figure. 9. developed steel tower for the soweto swt. ii.10. power wattmeter and dp-3051 software package the power wattmeter was compatible with the dpa3051 software package and thus used together. a power wattmeter was used to record data and stored in the device memory. the dpa-3051 software package was used to extract data from the power wattmeter and therefore give outcomes of the wind turbine in the form of graphing. see figure 10: figure. 10. power wattmeter and dpa -3051 software used for the soweto project. iii. result and discussion iii.1. case study for the eastern cape province, south africa [15] stated their research problems to be as follows: an assessment of generating electricity from wind for six sites of the eastern cape province: gqeberha (pe), queenstown, fort beaufort, makhanda/grahamstown, graaff reinet and bisho. the research was done at the fort hare university in south africa from june 2014 to december 2014. iii.2. research methodology used for the eastern cape province study the following technique and procedures were used in order to accomplish the project [15]: the series of five-year wind speed average data (01/2009 to 12/2013) for 6-eastern cape weather station were acquired at south african weather services (saws). the analysing of data with matlab was done with the use of a weibull distribution. iii.3. results and conclusion obtained for the eastern cape province from case study: reviewed. figure 11, shows location of six sites in the eastern cape province that research was conducted on. table 1, shows weather station coordinates that were used for eastern cape case study. figure 12, shows the variation of wind speed per day for eastern cape sites from (2009-2013). figure 13, shows the annual weibull probability t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 5 frequency density for part of the eastern cape for period under consideration. as depicted in figure 13, it is the observation of variation of wind speed for six eastern cape sites from 2009 to 2013. the respective maxima fluctuate from site to site. most inland sites trends have lower wind speed conditions, except gqeberha (pe) and bisho, which are located very near the coast. moreover, the minimum probability of an event in gqeberha (pe) is 0.13 but the city also has the highest wind speed, while fort beaufort has the least spread among these sites/regions [15]. figure. 11. location of six sites in the eastern cape province [15] table1. weather station coordinates used for eastern cape case study [15] figure. 12. variation of wind speed per day for eastern cape sites (20092013) [15] figure. 13. the annual weibull probability frequency density for part of the eastern cape for period under consideration [15] therefore, in this study, it was determined to use characteristics of p.e (gqeberha) region in the eastern cape province with soweto’s in order to determine the feasibility of implementing the soweto technology in the coastal region of p.e. iii.4. predictive study results for soweto and eastern cape province regions it is of major importance that the assessment of wind potential is performed correctly. all characteristics must be considered as they will impact every aspect of the assessment, such as the evaluation of physical performance, investment viability and system design. figure 14 illustrates the unit-t anemometer tool that was used in soweto to measure the effectiveness of wind periods for the area. according to [16], this tool is mostly used by meteorologists to analyse weather. the device has the ability to measure wind speed in (m/s) and (km/h) and temperature in (°c) and (°f), with data logging capture. it also has the ability to give outputs in the form of waveforms for analysis. the device has bluetooth functionality to transfer data to the user after measuring wind speed. the portable device can be plugged into the wind turbine and allowing convenient extraction of data. figure 14. unit-t 363-b anemometer [16] t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 6 table 2, 3 and 4 shows data that was collected for soweto wind measurement effectiveness with the use of a unit-t bluetooth anemometer every 24-hour intervals. the highest wind power probability as in figure 15 was found to be 2.3 m/s (8.28 km/h) using soweto data recorded in table 2, 3 & 4 and results were compared to that of statistics of south african weather services. table 2. phase two of soweto wind measurement data figure 15. probability of wind and normalized wind power for soweto area table 3. phase three of soweto wind measurement data. t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 7 table 4. phase four of soweto wind measurement data the average wind speed per year for gqeberha (pe), as determined by weather spark [17], is 11.6 mph (approximately 5.16m/s). knowing that soweto has an average wind speed of 2.3 m/s, characteristic variables were found as shown in table 5. as per my recent article published by etasr peer review open journal (engineering, technology and applied science research), titled: implementation and evaluation of a low speed and self-regulating small wind turbine for urban areas in south africa, results showed that prototype 3 with maximum pitch angle of 12° produced the maximum output power of 39.5 w during testing and the maximum power output was achieved at average wind speed of 1.17 m/s (4.2 km/h) with energy production to generate a maximum 40 kwh per month. figure 16, thus shows the predicted power output for prototype 3 (design 3) when it is applied in the gqeberha (pe) region, assuming that it operates continuously. the analysis yields a maximum output power of 54.3 w at the average wind speed in gqeberha. figure 16. predicted (output power vs. blade maximum pitch angle as derived for prototype 3 in gqeberha (pe) region). table 5. predicted wind speed between soweto and gqeberha (pe). figure 17 shows kwh energy production per month over a year, when the soweto technology results were predicted for gqeberha (pe)’s wind speed. it can be seen that the predicted production of energy per month in figure 17 was positive when compared to energy production for the prototype 3 when it was implemented in soweto. t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 8 figure 17. projected (kwh production vs. months) for prototype 3 when predicted to be applied in the gqeberha (pe) region. scientific research showed that while the minimum probability of an event in gqeberha was 0.13, the city also has the highest wind speed [15]. then the predicted annual probability density frequency for gqeberha (pe) and soweto in figure 18 shows that soweto has the maximum event probability of 0.16 with least wind speed. figure. 18. the predicted annual probability density frequency for soweto and gqeberha (pe)  predictive investment analysis for the soweto wind turbine an investment analysis for the soweto project is crucial as this will determine the viability of the project in the long term. in this section, the lists of materials that will be used for this project will be given together with the estimated prices. next, the project viability in terms of investment versus profitability and pay-back period of the investment will be analysed. a. budget for the soweto project table 6 shows the total wattage that was consumed for this project, and table 7 shows a list of all material that were used for this project. the prices of the main hardware and electronic devices were taken from the internet sources. the total energy consumption is 2910 w/day. table 6. energy consumption of appliances in soweto however, to calculate the minimum power of a generator, it is necessary to add the loss of energy from the electrical system; this can be estimated as 10 % of the electrical system’s total consumption. [18] stated that electrical energy consumption can be calculated as follows: (1) = 2619 w b. the predicted study of pay-back period and profitability for this project the predicted energy yielded using the soweto wind turbine system in kwh will be compared to the energy yield of electricity suppliers in south africa such as eskom and city power. the conclusion will be given on the expediency of this project, based on economic considerations. it is already known that the start-up investment is r15,600.00 (table 7). table 7. list of materials for the soweto project. t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 9 the internal rate of return is given as irr; to calculate the (irr), total start-up investment (r15,600.00) should be included. as shown in table 7, the life span of a small wind turbine will be given as (n) and (r) as rate of interest. according [18], the formula to calculate (irr) then becomes: ………………… (2) “r” is the rate of average interest of the total start-up investment, as shown in table 7. therefore, the soweto technology life span is estimated to be 20 years and rate of interest to be 7% of the start-up investment. thus we get an equation (3) as follows: [18] ( ) (3) the capital cost (cc) for production of energy in (kwh) taking into account that (i) is regarded as the initial investment and will be included in the equation of (irr). (cf) is the capacity factor and (p) is the minimum power generated. moreover, we will assume that the wind functions for 10.5 hours per day. then (cc) will be calculated as follows in equation (4): [18]. (4) ( ) ( ) (5) ( )( ) (6) [19] stated that maintenance is performed to prevent failures, that is preventive maintenance or it is for correcting a failure event, which is corrective maintenance. the importance of operation and maintenance in wind turbine site is to ensure the wind turbine generator (wtg) availability. when the wtg works, there would be possibility of issues such as errors / warning signals which may affects the availability of the wtg.operation and maintenance (o&m) costs make up 25-30% of the total costs of a wind turbine. this is almost as much as the cost of the wind turbines and about as much as the costs of construction and installation. according to [20], o&m costs are related to a limited number of cost components, and include: (i) regular maintenance (batteries, etc.) (ii) repairs; (iii) spare parts replacement and (iv) administration. thus, for the soweto small wind turbine, if we assume that o&m is 20% of the initial investment, then equation (7) will be as follows: [18] ( ) (7) therefore, the cost of power production (r /kwh) is the total cost of maintenance and operation plus the cost of capital (cc) as shown in equation (8): [18] (8) as per equation 8, it is seen that the estimated average cost to generate 1 kwh was r0.4567 /kwh with the soweto turbine, considering all initial capital outlay costs. however, according to [21], the average cost of generating 1 kwh in south africa is about r1.85 /kwh + 15 % tax = r2.13 /kwh for an average household that consumes between 100 and 1000 kwh per month, with a tariff addition of r5.00 per kwh where 1000 kwh usage is exceeded per month. c. the predicted pay-back of the capital investment calculations the payback period is the time period (generally in years) in which a return is required from an investment or the amount of time it takes for the positive cash flow to exceed the initial investment, without concern for the time value of money [22, 23]. [18] further stated that to calculate the aeo = annual energy output (kilowatt-hours/year) use the following equation (9): aeo = emean × 365 (where emean is appliances energy consumption shown in table: 6): 2910 × 365 1062.15 kwh/yea (9) table 8 and 9 [24], was used to analyse the annual energy production of selected turbines at the different sites and estimate the payback period of the investment. the total predicted energy generated per year by means of the soweto technology would be 1062,15 kwh/year. looking at table 8, under: region northern and site location johannesburg, it is apparent that the aeo calculated would fall under the power category of johannesburg as shown in table 8. t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 10 table 8. annual energy production of selected turbines at different sites [24]. this project initial plan was to use 500w wind generator as a departure point, therefore, table 9, further shows that with the range of 300 w-1 kw modern designed wind turbine application, the predicted payback period would be 16 years if all regular maintenance (batteries, etc.), repair, supply of spare parts and administration are taken into consideration. table 9. estimated payback period of selected turbines at different sites [24] iv. discussion • the highest wind power probability derived from wind anemometer collected data in soweto was approximately 2.3 m/s, demonstrating that the anemometer was calibrated correctly as compared to average wind speed referenced in south african weather service (saws). • the results showed that a predictive case study which was done for regions in eastern cape, specifically for the gqeberha (pe) area, utilizing the empirically obtained data in soweto, projected an energy output of up to 54.3 w per wind speed of 5.16 m/s (18.6 km/h) at gqeberha and up to 100 kwh per month production energy. • a predictive investment analysis to determine profitability and viability of prototypes revealed that when all initial capital outlay costs and operational costs over a 20-year period were considered, the average cost of generating 1 kwh was r0.4567 /kwh. this derived cost compares extremely favorably with the amount charged by electricity companies in south africa such as eskom and city power, which is (in 2022) approximately r1.85 /kwh + 15% tax = r2.13 /kwh) for an average household that consumes between 100 to 1000 kwh per month. moreover, at above 1000 kwh usage, the tariff increases to r5.00 per kwh, which then raises the anticipated cost savings even further. it was also predicted that the payback period for the soweto project to be 16 years. • social and environmental impact of the soweto technology as well as challenges and barriers to its widespread adoption can be found in my 2022 article [25]. v. conclusion the following are the major conclusions drawn from the research: 1. the benefits of this research was to achieve possible application of low-cost small-scale wind turbine in south africa for low wind speed areas, thereby providing low-cost electricity to households and inhabitants in urban as well as in rural areas for a very large region in south africa. this was achieved by developing a test prototype for low wind speed condition in soweto, johannesburg, south africa, and moreover prediction case study using soweto test results were shared in number (2). 2. a predictive case study for the eastern cape, focused on the gqeberha (pe) area, was conducted using the empirically obtained data for the soweto and gqeberha (pe) areas, and it was concluded that it would be feasible to implement the soweto technology in port elizabeth due to the results emanating presumably from the conditions at lower altitude (higher density air), and much higher wind speed resources at or near the coastal region. 3. finally, the predictive case study between soweto and p.e that was carried out contributed to new knowledge created within the field of study as it hasn’t been done before and it is original. t. sithole et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 01-11 page 11 declaration  the authors declare that they have no known financial or non-financial competing interests in any material discussed in this paper.  the authors declare that this article has not been published before and is not in the process of being published in any other journal.  the authors confirmed that the paper was free of plagiarism reference [1] s. jain and p.k. jain. "the rise of renewable energy implementation in south africa." energy procedia, 143, 2017, pp. 721-726. [2] n.n. rad, a. bekker, and m. arashi. "enhancing wind direction prediction of south africa wind energy hotspots with bayesian mixture modeling." sci rep 12, 2022, 11442 https://doi.org/10.1038/s41598-022-14383-8 [3] g. josie. "the science behind decarbonization: the race to zero." stanford earth matters magazine, 2021. [4] e.c. merem. "appraising variations in climate change parameters along the lower west african region." journal of safety engineering, 7:1:1-19, climate change and shorelines, may. 2018. [5] e.c. merem. "techniques of remote sensing and gis as tools for visualizing impact of climate change-induced flood in the southern african region." american journal of climate change, vol 6, 2017, 306-327. [6] b. babalwa. "south africa: kangnas wind farm kicks off operations." esi africa, 2020. [7] m. jamie. "south africa will be a wind energy powerhouse." olifansfontein, south africa: my broadband news, 2020. [8] pr newswire. "second wind's technology gains ground in south africa's expanding wind energy market." 2011. https://www.prnewswire.com/newsreleases/second-winds-technology-gains-ground-in-southafricas [9] memon, m. h., baloch, a. h. memon, s. h. qazi, r. haider, and d. ishak. "assessment of wind power potential based on raleigh distribution model: an experimental investigation for coastal zone." engineering, technology & applied science research, vol. 9, no. 1, 2021, pp. 3721-3725. https://doi.org/10.48084/etasr.2381 [10] y. kassem, h. gokcekus, and h. s. a. lagili. "a techno-economic viability analysis of the two-axis tracking grid-connected photovoltaic power system for 25 selected coastal mediterranean." engineering, technology & applied science research, vol. 11, no. 4, aug. 2021, pp. 7508-7514. https://doi.org/10.48084/etasr.4251 [11] f. elmahmoudi, o. e. k. abra, a. raihani, o. serrar, and l. bahatti. "elaboration of a wind energy potential map in morocco using gis and analytic hierarchy process." engineering, technology & applied science research, vol. 10, no. 4, aug. 2020, pp. 6068-6075. https://doi.org/10.48084/etasr.3692 [12] sma. "wind power inverter." available from: http://ust.su/upload/iblock/bb1/sollight-smawindyboy5000-6000.pdf accessed: 15th january 2020. [13] myint, a. s., tun, h. m., and naing, z. m. "implementation of wind turbine controller design for smart campus." international journal of scientific and research publications, jun. 2014, vol. 4, no. 5, pp. 1-10. [14] t.s sithole, v.r veeredhi, and t. sithebe. "small wind turbine blade optimization using blade elementary method theory (bemt)." ijisrt, dec. 2022, vol. 7, no. 12, pp. 16-21. https://doi.org/10.5281/zenodo.7444983 [15] c. shonhiwa, g. makaka, and k. munjeri. "estimation of wind power potential of six sites in eastern cape province of south africa." physical science international journal, june 2015, pp. 209-218. [16] electromann sa. "wind power (technology and economics)." aug. 2021. available from: https://www.electromannsa.com/products/uni-t-ut363btbluetooth-mini-wind-speed-meter [17] weather spark. average weather in port elizabeth. 2020. https://tinyurl.com/y6kd795c [18] moreno, f.g. design of a small wind generator. 2008. https://tinyurl.com/yy45y38z [19] rajeesh, k.c. and sankar, s. improving battery life in the wind turbine generator using ultracapacitor. international journal of advanced technology in engineering and science, no 03, 2015, pp. 2348–7550. [20] castellà, a.t. operations and maintenance costs for offshore wind. 2020. available: https://upcommons.upc.edu/bitstream/handle/2117/32973 1/master-thesis-xavier-turc-castell-.pdf [21] business -tech. south africa’s petrol and electricity prices vs. the world. 2019 jun. available: https://tinyurl.com/y6gkx49p [22] ayompe, l. performance and policy evaluation of solar energy technologies for domestic application in ireland. 2011. https://tinyurl.com/3rbpt938 [23] mostafaeipour, a. economic evaluation of small wind turbine utilization in kerman, iran. energy conversion and management, 73, 2013, pp. 214-225. [24] olatayo, k.i. a development path for small wind energy systems in south africa. 2017 may.: http://repository.nwu.ac.za/bitstream/handle/10394/25628 /olatayo_ki_2017.pdf?sequence=1&isallowed=y [25] t.s sithole, v.r veeredhi, and t.sithebe. a review on small wind turbine aerodynamic performance for contribution of power supply for low wind speed areas. ijceee, may 2022, vol. 4, no. 5, pp. 1-6. https://wairco.org/ijceee/may2022.html https://doi.org/10.1038/s41598-022-14383-8 https://www.prnewswire.com/news-releases/second-winds-technology-gains-ground-in-south-africas https://www.prnewswire.com/news-releases/second-winds-technology-gains-ground-in-south-africas https://www.prnewswire.com/news-releases/second-winds-technology-gains-ground-in-south-africas https://doi.org/10.48084/etasr.2381 https://doi.org/10.48084/etasr.4251 https://doi.org/10.48084/etasr.3692 http://ust.su/upload/iblock/bb1/sollight-sma-windyboy5000-6000.pdf http://ust.su/upload/iblock/bb1/sollight-sma-windyboy5000-6000.pdf https://doi.org/10.5281/zenodo.7444983 https://www.electromannsa.com/products/uni-t-ut363bt-bluetooth-mini-wind-speed-meter https://www.electromannsa.com/products/uni-t-ut363bt-bluetooth-mini-wind-speed-meter https://tinyurl.com/y6kd795c https://tinyurl.com/yy45y38z https://upcommons.upc.edu/bitstream/handle/2117/329731/master-thesis-xavier-turc-castell-.pdf https://upcommons.upc.edu/bitstream/handle/2117/329731/master-thesis-xavier-turc-castell-.pdf https://tinyurl.com/y6gkx49p https://tinyurl.com/3rbpt938 http://repository.nwu.ac.za/bitstream/handle/10394/25628/olatayo_ki_2017.pdf?sequence=1&isallowed=y http://repository.nwu.ac.za/bitstream/handle/10394/25628/olatayo_ki_2017.pdf?sequence=1&isallowed=y https://wairco.org/ijceee/may2022.html international journal of energetica (ijeca) https://www.ijeca.info/index.php/ijeca/index issn: 2543-3717 volume 1. issue 1. 2016 page 36-39 ijeca – issn: 2543-3717. december 2016 page 36 water potentiality of sustainable management challenges in the oued souf region, south east algeria miloudi abdelmonem 1 , remini bouallem 2 1 department of hydraulics and civil engineering, university of el oued algeria 2 department of water science, saad dahlebe university of blida algeria e-mails: monem_mld@yahoo.fr abstract water is the most essential product of life and is a part of the essential constitution of living cells; it helps to carry out all the vital operations. water is a cosmic element, in the same way as the sun and the earth. with the population growth in the souf region, the needs of habitats and farmers increase for water. these needs have a negative consequence on the serene life of the people; the phenomenon of the upwelling of the free water table has taken a very alarming dimension during the last twentieth century. in our study, we focused our intention in the mechanism of the drawdown of the waters of the aquifer ct of state al oued (south east algeria) and the consequences of irrational overexploitation of this aquifer on the environment of the region. keywords: the water, souf region, ct, overexploitation. nomenclature ct: complex terminal drh: direction of hydraulic resources dtm: digital terrain model aep: drinking water supply 1. introduction if man maintains singular relations with water, it is because of the absolute necessity in which he finds himself appealed to it simply to stay alive. it is impossible in these circumstances, to take a step back. twenty-four hours without it and the finest intellectual machine stops, the brain does not hear its thirst. the traditional water supply system for the inhabitants and farmers, operate in a closed loop, with limited flows. the deep drilling has created additional crises, without planning any exits. the system is now disturbed. the problem of water surpluses does not only affect the city of oued, but it also affects several other towns in the algerian sahara, as example ouargla region and touggourt region; those are large cities, where the volumes of which have developed great perimeters of putting in values, which discharge considerable amount of drainage water. this fast development has led to enormous problems in recent years, mainly related to the upwelling and evacuation of water from groundwater, to the sewerage water. our work is based on the hydro geological part, to be able to realize the drawdown of the level of the deep water table of complex terminal of the region of the souf (algeria) or by a word overexploitation of ct. mailto:monem_mld@yahoo.fr miloudi abdelmonem et al ijeca – issn: 2543-3717. december 2016 37 2. the geographical situation of the oued souf region the study area is located in the wilaya of el oued, one of the main oases of the algerian northern sahara. the study area covers 18 municipalities (el oued, bayadha, robbah, kouinine, guemar, taghzout, hassani abdelkrim, debila, sidi aoun, magrane, hassi khelifa, reguiba, mihouensa, oued alenda, ogla, nakhla, ourmes et trifaoui), an area of approximately 11200 km2, limited by the following geographical coordinates: longitude: 06 ° 20 'and 07 ° 50' east and latitudes; 32 ° 50 'and 34 ° 30' north (figure 1). fig1. areas (sectors) in the state of el oued (a. miloudi 2015) the only water resources available are underground aquifers [1]. the underground water tables of the souf region are contained in aquifer formations of a different nature especially on the national and regional scale of the country. the authors (baba sy, 2005, brl-bneder, 1999, cornet 1961, castany 1982, cornet and gouscov 1952, guendouz a, et al., 2003, unesco, 1972a) [2-5]. generally distinguishes three geological complexes that contain groundwater resources: a vast sedimentary basin consisting of layers of varying thickness and hydrogeological characteristics are: 1-continental intercalary. 2 complex terminal. 3groundwater. 3. the ct piezometry of the souf region 3-1 terminal complex piezometric map of 2012: measurements of the piezometric level (pressure) in the saharan boreholes face many problems:  the first problem is the absence or very limited number of true piezometers specifically designed for measurements due to important depths (case of continental intercalary) which will be resulting in prohibitive costs of piezometers. the piezometric measurements are therefore generally made on boreholes in operation, which implies stopping pumping or closing the drilling, if it is artesian, for at least several hours. this operation runs up against the reluctance of the users who are thus deprived of water, for a certain time. for our study, the anrh carried out twelve 12 boreholes (piezometers for monitoring) distributed geographically on the souf region.  the second problem is related to the difficulty of measuring the gushing boreholes, the closure of which is not always possible and which are not always equipped with an outlet upstream of the valve to connect the manometer. in general, a measurement was made at the time of drilling. with the help of the database of 1.el oued 2.kouinine 3.bayadha 4.guemar 5.debila 6.hassi khalifa 7.reguiba 8.taghzout 9.trifaoui 10.hassani a-karim 11.oued el alenda 12.ourmes 13.mih ouensa 14.robbah 15.taleb el arbi 16.douar el maa 17.magrane 18.sidi aoun 19.nakhla 20.el ogla 21.ben ghecha 22.sidi amrane 23.m’rara 24.djamaa 25.tendla 26.sidi khellile 27.hamraia 28. el mghair 29.oum tiour 30.still miloudi abdelmonem et al ijeca – issn: 2543-3717. december 2016 38 niveau piézométrique de ct 2012 en (m) direction of hydraulic resources (drh) state of el oued, concerning the piezometric level for new boreholes drilled or drilled their pump (broken down) during the year 2012 using arcgis, a digital terrain model (dtm) of the souf region is added as a background and the borehole data is interpolated to extract the piezometric map of terminal complex ct (figure 02) fig2. ct piezometric map of the souf region in 2012 according to the previous map, overexploitation of the aquifer at the common robbah, bayadha, hassani a. karim and hassi khalifa is clear, due to the need for drinking water supply (aep). the hassi khalifa common dws network is connected to the barremian (continental intermediate) drilling to cover water requirements, and some ct drilling for irrigation. the water requirement for the common hassani a-karim is distributed between the aep, irrigation and need of the industrial zone. the piezometric level at level f14 (common kouinine) is high compared to other boreholes "f2, f12, f15, f16", because it is not in service a few years i.e. when we return to the nesson c in 1978 (figure 03) piezometric level map. we found that the communes el oued, kouinine, guemar and reguiba ... etc. or rather the northern part of the souf is characterized by deep artesian (complex terminal) artesian. fig3. ct piezometric map of the souf in 1967(nesson. c, 1978) miloudi abdelmonem et al ijeca – issn: 2543-3717. december 2016 39 terrain naturel zones de ct artésienne irrigated palm grove. 2. palmeraie "bour". 3. chott; sebkha. 4. wells used for irrigation. 5. wells for the supply of drinking water. 6. well not exploited. -7. locality without well. 8. isopieze of the terminal complex (lower eocenepontian). the greasy trais in blue marks the southern limit of the gushing waters of the complex terminal. for this reason, we have built a 3d model by arc scene; presents the zones that it had of ct artesian artery (figure. 4). fig4. ct artesian areas in 2012 according to the drilling inventory (drh, 2015) the flow extracted every day is approximately 3447.42 liters per second, this model clearly explains that the artesian water table was lost due to overexploitation of this source. 4. conclusion the increase in pumped volumes and the development of saharan agriculture have repercussions at the level of these saharan aquifers (ct) in the form of the drying up of the sources and the weakening or losing of artesianism as in our region. this increasing exploitation is likely to lead to changes in water quality in the vulnerable zones (salt and mineral concentrations) over the long term. our study is insufficient to give total coverage on the water resources below us feet, for this it is of plan of work in 2016 with the group anrh of touggourt concerned the hydrodynamics and hydrochemistry of complex terminal and continental intercalary of the region oued souf and oued righ. we also pence this work with the three tablecloths or rather the three subtablets that make up the complex terminal. reference [01] voisin a.r., 2004. les souf monographie, edition el-walid, el oued-algérie. 319 p. [02] baba sy m., besbes m., 2006. holocene recharge and present recharge of the saharan aquifers. a study by numerical modelling, colloque international gestion des grands aquifères 30 mai-1er juin 2006, dijon, france. 16p. [03] cornet a., 1961. initiation à l'hydrogéologie saharienne. cours ronéoté destiné aux officiers du cours préparatoire aux affaires sahariennes. s.e.s. birmandreis, alger, 108p. [04] castany g., 1982. bassin sédimentaire du sahara septentrional (algérie tunisie). aquifères du continental intercalaire et du complexe terminal. bull. brgm 2 iii, vol. 2. pp 127-167. [05] guendouz a., moulla a.s., edmunds w.m., zouari k., shand p., mamou a., 20 may 2003. hydrogéochemical and isotopic evolution of water in the complexe terminal aquifer in the algerian sahara, hydrogeology journal (2003). pp 485-495. [06] nesson c., 1978. l'évolution des ressources hydrauliques dans les oasis du bas sahara algérien. in: recherche sur l'algérie. ed. cnrs, paris. pp 7-100. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 2. 2018 page 34-37 ijeca-issn: 2543-3717. december 2018 page 34 numerical study of a turbulent burner by means of rans and detailed chemistry mohamed hafid 1 , nacer hebbir 1 , kamel bouarour 2 , senda trabelsi 3 1 lmssef, university of larbi ben m'hidi, oum el bouaghi, 04000, algeria 2faculty of science and technology, university of ghardaia, ghardaïa, algeria 3mechanical engineering department, university of sherbrooke, sherbrooke, quebec, j1k 2r1, canada mohamed.hafid@usherbrooke.ca abstract – the present paper shows a numerical study of the co-flow turbulent flame configuration using the reynolds averaged navier-stokes (rans) modelling with detailed chemistry. the presumed probability density function (pdf) model combined with the k-ɛ turbulence model is adopted. the gri mech-3.0 mechanism that involves 53 species and 325 reactions is used. the effect of the turbulent schmidt number sct and the c1ε constant in the turbulent dissipation transport equation is highlighted. despite the simplicity of rans approach compared to other complex models such as les and dns, the results show that this approach is still able to simulate the turbulent flame. keywords: turbulent flame, rans simulation, non-premixed, burner, presumed-pdf. received: 30/11/2018 – accepted: 27/12/2018 i. introduction energy demand is rising due to the increase in electricity requirements, heating and cooling etc. energy requirements can be met by different energy resources such as fossil fuels, renewable energy, nuclear energy, biomass etc. however, most of this energy comes from the combustion of fossil fuels. in recent years, the negative effects of combustion on the environment particularly greenhouse gas (ghg) emissions released to the atmosphere that contribute to global warming have received much attention. consequently, the study of combustion process is extremely important in order to reduce environmental impact and enhance the energy efficiency. most of the industrial flames are of a turbulent non-premixed type, called also diffusion flames. this kind of combustion is controlled by the flow, and consequently, it is very sensitive to the turbulence [1, 2]. in this paper, a presumed probability density function (pdf) approach is used in turbulent combustion modelling. this approach solves the evolution of the onepoint, one-time pdf for a set of variables that determines the local thermochemical of combustion process [3]. this approach is also fairly elaborate, and consequently, computationally expensive, especially when the number of chemical species is large such as the gri mech-3.0 mechanism. on the other hand, presumed-pdf approach gives a form of pdf to close the chemical source term, which is computationally less expensive even if complex chemical mechanisms are considered [4, 5]. in the present study, the combustion chemistry of chemical species is described by the gri mech-3.0 mechanism. this one consists of 325 reactions that involve 53 species. the mechanism precision was intensively assessed in previous studies [6, 7]. the purpose of this paper is to provide a numerical characterisation of the co-flow configuration turbulent combustion using the reynolds averaged navier-stokes (rans) modelling with detailed chemistry. ii. problem statement figure 1 presents the geometry of burner. the combustion burner is modelled by a cylinder with a diameter d = 800 mm and a length of 1200 mm (see figure 2). the central fuel jet (d1 = 8 mm) is a mixture of ch4, h2 and n2. this fuel jet is surrounded coaxially by air jet (d2 = 140 mm). figure 2 shows the simulated domain. figure 1. geometry of burner. mailto:mohamed.hafid@usherbrooke.ca m. hafid et al ijeca-issn: 2543-3717. december 2018 page 35 figure 2. geometry and boundary conditions the boundary conditions are summarized in table 1. table 1 boundary conditions number boundary conditions 1 velocity inlet intensity of turbulence i= 5% hydraulic diameter d 0.004h m    2 velocity inlet intensity of turbulence=1 % hydraulic diameter d 0.069 average velocity =0.3 m/s h m      3 pressure inlet intensity of turbulence i=0.1% hydraulic diameter d 0.39h m    4 slip wall 5 pressure outlet intensity de turbulence i=1 % hydraulic diameter d 0.4h m    6 axis (v = 0 m/s) in this paper, a 2d steady-state simulation of the physical domain was considered due to the axial symmetry of the system. figure 3 shows the computational mesh used to simulate this turbulent flame. it is a structured non-uniform grid with about 16044 cells, designed to give high resolution in the flame region and close to the inlets and save computational efforts elsewhere. the grid domain is 1200 mm in axial and 400 mm in radial direction from the jet exit. the grid-independency of the results was also verified. figure 3. grid of the computational domain m. hafid et al ijeca-issn: 2543-3717. december 2018 page 36 iii. results and discussion in this section, the numerical simulation results compared with the experimental measurements are presented and discussed [8]. the effect of the c1ε constant on the flame velocity is illustrated in figure 4. for both positions presented here, it is seen that the case with c1ε=1.64 gives better prediction of the experimental values than those with c1ε=1.44 the effect of the c1ε constant on the flame temperature is illustrated in figure 5. it is seen that the case with c1ε=1.64 gives better prediction of the experimental values than those with c1ε=1.44 and 1.60. this indicates the existence of a strong interplay between turbulence and combustion model formulations. figure 6 presents the effect of the turbulent schmidt number sct on the temperature prediction. reducing the schmidt number is the better. 0,0 0,4 0,8 1,2 1,6 2,0 0 10 20 30 40 50 exp c epsilon 1 = 1.64 c epsilon 1 = 1.44 x/d=5 u [ m /s ] r/d 0 2 4 6 8 10 0 4 8 12 16 20 exp c epsilon 1 = 1.64 c epsilon 1 = 1.44 x/d=40 u [ m /s ] r/d figure 4. velocity profiles at x/d1 = 5 and 40 0 3 6 9 12 15 0 400 800 1200 1600 2000 exp cepsilon 1= 1,44 cepsilon 1= 1,6 cepsilon 1= 1,64 t [ k ] r/d figure 5. temperature profiles at x/d1 = 40 0,0 0,5 1,0 1,5 2,0 2,5 0 300 600 900 1200 1500 1800 expérience sc=0,85, c epsilon 1 = 1,44 sc=0,49, c epsilon 1 = 1,44 sc=0,49, c epsilon 1 = 1,64 t [ k ] r/d figure 6. temperature profiles at x/d1 = 5 temperature contours are depicted in figure 7 to visualize the development of flame inside the domain. it is seen that a high temperature region is formed around the mixing region. figure 7. computed contours of mean temperature m. hafid et al ijeca-issn: 2543-3717. december 2018 page 37 the mixture fractions z, profiles and contours, are presented in figure 8 and 9 respectively. it is seen that the agreement between the numerical predictions and the experimental results is good. 0 20 40 60 80 100 120 0,0 0,2 0,4 0,6 0,8 1,0 simulation exp fr a c ti o n d e m é la n g e z x/d figure 8. mixture fraction profiles figure 9. mixture fraction contours iv. conclusion a numerical investigation of turbulent flame configuration using the reynolds averaged navierstokes (rans) modelling with detailed chemistry was presented. the presumed probability density function (pdf) model is combined with the k-ɛ turbulence model was used. the gri mech-3.0 mechanism that involves 53 species and 325 reactions was adopted. the effect of the turbulent schmidt number sct and the c1ε constant in the turbulent dissipation transport equation was highlighted. the results show that this approach is still able to simulate the turbulent flame. v. references [1] lassaad jebali, anis kacem, impact of fuel energy prices in tunisia. international journal of energetica, vol. 3, no 1, 2018, pp. 24-30. [2] madiha maamir, achour betka, hania aboub, modeling and simulation of energy management hybrid sources system composed of solar-pv and battery. international journal of energetica, vol. 1, no 1, 2016, pp. 12-19. [3] mohamed el hadi attia, zied driss, abderrahmane khechekhouche, numerical study of the combustion of ch4-c3h8/air: application to a combustion chamber with two coaxial jets. international journal of energetica, vol. 2, no 2, 2017, pp. 38-42. [4] norbert peters, turbulent combustion, institut fur techniche mechanik rheinisch-westfalische technische hochschule aachen, germany, 2000. [5] forman a williams, combustion theory, the fundamental theory of chemically reacting flow systems, second edition, the benjamin/cummings publishing company, inc. 1985. [6] a. mameri, f tabet, a hadef, mild combustion of hydrogenated biogas under several operating conditions in an opposed jet configuration. international journal of hydrogen energy, vol. 43, no 6, 2018, pp. 3566-3576. [7] a. mameri, f tabet, a. hadef, numerical investigation of biogas diffusion flames characteristics under several operation conditions in counter-flow configuration with an emphasis on thermal and chemical effects of co2 in the fuel mixture. heat and mass transfer, vol. 53, no 8, 2017, pp. 2701-2710. [8] v. bergmann, w. meir, d. wolff and w. stricker, application of spontaneous raman and rayleigh scattering and 2d lif for the characterization of a turbulent ch4/h2/n2 jet diffusion flame, appl. phys. b: laser and optics, vol. 66(4), pp. 489 – 502, springerverlag, 1998. i. introduction ii. problem statement iii. results and discussion iv. conclusion v. references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 31-36 ijeca-issn: 2543-3717. june 2018 page 31 the relationship between the compressive strength and ultrasonic pulse velocity concrete with fibers exposed to high temperatures belaribi hassiba 1 , mellas mekki 2 , rahmani farid 3 1 laboratoire de génie civil, département de génie civil et hydraulique, université mohammed khider biskra 07000 2 laboratoire de génie civil, département de génie civil et hydraulique, université mohammed khider biskra 07000 3 département de mécanique, université mohammed khider biskra 07000 farsou1@yahoo.fr abstract – the paper analyses the effects of high temperatures on the concrete residual strength using ultrasonic velocity (upv). an experimental investigation was conducted to study the relationship between upv residual data and compressive strength of concrete with different mixture proportions, cubic specimens with water-cement ratio of 0.35. they were heated in an electric furnace at temperatures ranging from 200°c to 600°c. in this experiment a comparison was made between the four groups which include two types of fibers steel 0,19%, 0,25% and 0,5%, polypropylene: 0,05%, 0,11% 0,16 % by volume. cube specimens were tested in order to determine ultrasonic velocity. the compressive strength was tested too. according to the results, relations were established between ultrasonic velocity in the specimens and the compressive strength at different temperature and the range of the velocity of the waves were also determined for this kind of concrete. result of the test showed that upv test can be successfully used in order to verify the consistency of structures damaged by fire. keywords: ultrasounds; non-destructive testing; concrete, fibers, temperature, steel, polypropylene. received: 01/12/2017 – accepted: 11/04/2018 i. introduction concrete is a building material that finds its field of use virtually in all areas of civil engineering. that is, it includes buildings, tunnels, oil platforms, nuclear power plants and other several structures that may be exposed to high temperatures or fire. the effect of high temperatures study on concrete structures started in 1920 however, in the mid-1990s, a new interest in evaluating the performance of the concrete when it was subjected to extreme temperatures was carried out in particular after fires in different tunnels [1]. when concrete exposed to high temperatures, the chemical composition and physical structure change considerably, resulting in a significant reduction of the mechanical properties, such as strength, modulus of elasticity and volume stability[2].one of the successful techniques for detection of chemical and physical changes and damage in concrete is the use of nondestructive testing methods , the ultrasonic method is one of the nondestructive testing techniques and is frequently adopted for evaluating the quality in situ concrete structures[3,4, 5,6]. for concrete with a density of approximately 2400 kg/m3 are given as excellent, good, doubtful, poor and very poor for 4500 m/s and above, 3500–4500, 3000–3500, 2000–3000 and 2000 m/s and below upv values, respectively according to the classification criterion for concrete based on ultrasonic pulse measurements by whitehurst [7]. several experimental studies had been carried out to investigate how the pulse velocity was affected by the damage of concrete caused by various high temperatures and have been made to develop the relation between the ultrasonic pulse velocity and the compressive strength at high temperature. the following equations are the most important ones established by various scientists given in table 1: b. hassiba et al. ijeca-issn: 2543-3717. june 2018 page 32 the article examines the residual compressive strength and ultrasonic pulse velocity of concrete that has been cured with water after exposure to elevated temperatures. the relationship between the residual strength ratio and the residual upv ratio was developed. cubic specimens were made of concrete with water-cement ratios of 0.35 after 56 days, the samples were heated in an electric furnace at temperatures ranging from 400 to 600 ° c. the speed of the ultrasonic pulse and the compressive strength of each test piece after curing of fire are measured immediately after 24 hours of cooling. the results obtained indicate that the application of upv has demonstrated to be a trustworthy analysis, being able to prove the effectiveness of its use on fire-damaged concrete structures. ii. experimental study the materials used for the different concretes are: -the cement used to make the concrete was the cpj cem ii/a 42,5. the cement density was 3kg/dm3 and the compressive strength measured at 28 days was > 40 mpa -aggregates: crushed gravel class 8/15 mm, density was 2.61 kg/dm3 a crushed gravel class 3/8 mm, density was2.63 kg/dm3 sand class 0/5 mm, density was 2.57 kg/dm3 water-reducing superplasticizer named sika viscocrete tempo 12. -steel fibers:the fibers used are sika fibre rl-45/50bn which are made from steel wire. they have a mechanical ink consisting of hooks to the end. they were cylindrical of 50 mm length with a diameter of 1.05 mm. the tensile strength was 1000mpa and temperature de fusion are 1380°c -polypropylene fibers: polypropylene high tenacity fibers are used for reinforcement of concretes with length 12 mm and density was 0.91 kg/dm3andtemperature de fusion are between 160 – 170 °c. tree groups of high strength concrete mixes were studied: the first group of concrete mixes without fibers (b), the second mixes with polypropylene fibers (bp), the third mixes with steel fibers (bm). all mixes have the same water/cement (w/c) ratio of 0.35 and the same paste volume. three volume fractions of polypropylene fibers in the concrete were tested: 0.05, 0.11% and 0.17% (equivalent to 0.5, 1 and 1.5kg/m 3 ). three volume fractions of steel fibers were used: 0.19%, 0.25 % and 0.5 (equivalent to 15 to 19.5 and 39 kg/m 3 ).of cubic specimens (10x10x10) cm were manufactured and preserved in water until 28 days after unmolding. after that they were dried in the open air (28 days) before the heat treatment. three cycles of heating cooling from room temperature (20°c) and up to bearing different temperatures: 200°c, 400°c and 600°c were applied to the specimens by means of an electric furnace. each cycle consists of three phases. the first is a temperature rise at a ramp rate of 10°c/min. then constant temperature level in the oven for one hour. the mechanical properties of the specimens were determined before and after the heat treatment by conventional testing according to the standard nf en 12390-3 [14] for the compressive strength. the mixture proportions of the different concretes are presented in table 2. table 2mix proportions table 1 the relationship between the compressive strength and the ultrasonic pulse velocity at high temperature established by various scientist. formula r2 the scientist year (ft/ f o) = -0.07 + 3.29 (vt/vo) 2.42 (vt/vo) 2 0.98 0.91 h.w.chung [8] 1985 ft/ f o) = -0.08 + 2.15 {vt/vo) 1.32 (v/vo) 2 fc = 17,244 e0,2997v 0,8354 suhaendi sl, horiguchi t [9] 2006 y= 37,43 x +3190 at 28 days y= 40,11 x +3093 at 90 days 0,901 0,918 prashant y.pawade [10] 2011 fc= 14,804 e0,0002upv mesure methode direct fc= 7,5391 e0,0003upv mesure methode semi direct fc= 6,5583 e0,0004upv mesure methode indirect 0,63 0,70 0,68 k. prasopchaichana [11] 2012 fc = 44,86 ln vt +25,15 for ordinary concrete fc = 22,09 ln vt +15,81 for high performance concrete 0,949 0,961 izabela hager and hélène carré [12] 2012 fc = 19,034v-54,026 0,987 olowofoyeku adeoye m., [13] 2013 mixture without fibers % steel fibers % polypropylene fibers % of fibers 0 0.19 0.25 0.5 0.055 0.11 0.16 w/c 0.35 0.35 0.35 0.35 0.35 0.35 0.35 water kg 158 158 158 158 158 158 158 cement kg/m3 450 450 450 450 450 450 450 aggregates sizes (mm) 8/15 mm kg/m3 182.91 181.91 180.91 180.91 180.66 180.26 179.16 3/8 mm kg/m3 1016.79 1001.79 1001.79 984.97 1016.29 1015.79 1015.29 0/5 mm kg/m3 585.44 585.44 581 580 585.44 585.44 585.44 superplasticizer (% in dry extract) 1.5 1.7 1.9 2 2 2.1 2.2 b. hassiba et al. ijeca-issn: 2543-3717. june 2018 page 33 iii. results and discussions the results obtained in this study were presented in figures1– 6. they are evaluated and discussed below. iii.1.1. the effect of the steel fibers on the compressive strength and upv influenced by temperature for percentages of fibers 0.19 %,0.25% et 0.5% respectively, it is seen that at 200 °c the compressive strength decreased 14 % ,15 % and 3 % compared to the room temperature strength. the reduction in compressive strength for samples heated to 400 °c was 25%, to 33 % compared to the room temperature strength. after heating to 600 °c the compressive strength decreased 38%, to 44 % compared to the room temperature strength. obviously, compressive strengths concrete deteriorates with the increasing in maximum heat temperature as shown in figure 1.similar behavior has already been observed in the literature [15, 16, 17, 18, 19]. the volume percentage has no efficacy after heating at 200° which is confirmed by [9]. (the fiber percentage is less than 0.5%). it is known that concrete quality can be classified by upv value: if the value is more than 4500 m/s, 3500– 4500 m/s, 3000–3500 m/s, 2000–3000 m/s and less than 2000 m/s, the concrete is classified as ‘‘excellent’’, ‘‘good’’, ‘‘doubtful’’, ‘‘poor’’ and ‘‘very poor’’, respectively[6]. by comparing the residual upv at different heating temperatures; it is seen upv measurements at 200 °c is 4696.67 m/s, 4680 m/s and 4633.33m/s for percentages of fibers 0,38%,0,19% et 0.19% respectively the concrete is classified as excellent quality of concrete and at 400 ° c the (upv) measurement are 3873.33 m/s for 0.5%, percentage of steel fibers the results obtained are considered good interms of quality ,the same remark for 0.25% were upv are 3753.33 m/s were are considered good et doubtful for 0.19% where the upv are 3260 m/s and from then temperature 600°the pulse velocity decrease there is a very significant reduction 2943.33 m / s, 2870 m / s and 2416.67 m/s are considered poor in-terms of quality..all specimens degraded from ‘‘excellent’’ to ‘‘good’’, to ‘‘doubtful’’, to ‘‘poor’’ respectively. the upv values decreased for all mixture types after exposure to elevated temperatures as presented in figure2in accordance with other authors [5, 8, 9, 19,20,21 22,]. fig. 1. relationship between compressive strength and temperature for different percentage of steel fibers. fig. 2 the relationship between upv (m/s) and temperature for different percentage of steel fibers iii.1.2. the effect of the polypropylene fibers on the compressive strength and upv influenced by temperature for percentages of fibers polypropylene 0.16%, 0.11% and 0.05 % respectively; it is seen that at 200 °c the compressive strength decreased 17.15 %, 17.90% and 15.70 % compared to the room temperature strength. the reduction in compressive strength for samples heated to 400 °c was 30.45% and 32.79% and 33.55 % compared to the room temperature strength. after heating to 600 °c the compressive strength decreased 43.16%, 46.47 % and 47.70% compared to the room temperature strength. obviously, compressive strength concrete deteriorate with the increasing in maximum heat temperature as shown in figure 3 , a similar behavior has already been observed by other scientists like xiao [23]and others[24, 25, 26]. it is seen that upv measurements at 200 c° is4681,55 m/s, 4653.33 m/s and 4620 m/s for percentages of fibers 0.17% , 0.11% and 0.05 % respectively the concrete is classified as excellent quality of concrete; and at 400°c the upv measurement are 3743.33 m/s for 0.17 %, percentage of polypropylene fibers where the results obtained are considered excellent in-terms of quality , for the 0.11% and 0.05% upv are 3393.33 m/s and 2993.33 m/s are considered good and from thence temperature 600° the pulse velocity decrease there is a very significant reduction 2666.67 m / s, 2593.33 m / s b. hassiba et al. ijeca-issn: 2543-3717. june 2018 page 34 and 2286.67 m/s are considered poor in-terms of quality. the upv values decreased for all mixture types after exposure to elevated temperatures as presented in figure 4accordance with works of [5, 8, 9, 19,20,21 22,]. fig. 3. the relationship between compressive strength and temperature for different percentage of polypropylene fibers. fig.4. the relationship between upv (m/s) et la temperature for different percentage of polypropylene fibers. iii.1.2. relationship between ultrasonic pulse velocity upv and compressive strength many scientists have studied how upv can be correlated with concrete strength. according to previous research by [34] and [33], the compressive strength and ultrasonic pulse velocity upv values are related by the following equation a (non-linear model is suggested) v (1) where fc is the compressive strength, vc is the pulse velocity (km/s), a and b are empirical constants [33] the following law relating compressive strength (f c in mpa) to upv (vc in m/s) for concrete with steel fibers: fc = 17,476e 0,0003 v et r² = 0,6739 fig.5. the relationship between compressive strength and upv for concrete with steel fibers the following law relating compressive strength (f c in mpa) to upv (vc in m/s) for concrete without fibers: fc = 8,5773e 0,0004v et r² = 0,8419 fig.6. the relationship between compressive strength and upv for concrete without fibers the following law relating compressive strength (f c in mpa) to upv (vc in m/s) for concrete without fibers: fc = 16,312e 0,0003v et r² = 0,8713 fig.5. the relationship between compressive strength and upv for concrete with polypropylene fibers b. hassiba et al. ijeca-issn: 2543-3717. june 2018 page 35 conclusion based on the experimental results were noticed: the compressive strength and the upv ultrasonic speed deteriorate with increasing temperature whatever the nature of the fibers. analysis of local materials shows that they meet the standards for the manufacture of quality concrete. the steel fibers improve the compressive strength of concretes for all heating-cooling cycles. it is concluded that the incorporation of this type of fiber is advantageous in concrete that has been exposed to elevated temperatures. the polypropylene fibers are generally no significant influence on the improvement of the resistance to the residual compression for the concrete after high temperature heating. the different grades of polypropylene and metal fibers do not change the kinetics of the compressive strength loss. the increase of percentage of the polypropylene fibers in the concrete polypropylene fibers and metal is an adverse effect on the compressive strength. the feature of concrete with the mixture of polypropylene fibers and metal is closer to the concrete with metal fibers. -an exponential relationship between upv and compressive strength for the different concrete mix has provided an adequate approximation for comparing them with r 2 values in the range of 67 87% the results indicate that the exponential relationship provides an adequate approximation for comparing the values upv and compressive strength. the constant b values in the range 0.0003 and 0.0004 the ultrasound test is found to be an effective tool to assess the degree of damage in concrete structures exposed to high temperatures. references [1] laboratoire central des ponts et chaussées, présentation des techniques de diagnostic de l’état d’un béton soumis a` un incendie. report me 62 (in french), 2005. [2] l. d. kirchhof, a. lorenzi, l. s filho, assessment of concrete residual strength at high temperatures using ultrasonic pulse velocity .20 no.7 2015the e-journal of nondestructive testing issn 1435-4934. [3] m. colombo, r. felicetti, new ndt techniques for the assessment of fire-damaged concrete structures. fire saf j 42, 2007, pp 461–472. [4] h.w chung, ks law, assessing fire damage of concrete by the ultrasonic pulse technique. cement, concrete and aggregates, 7, 1985, pp 84-88. [5] l. logothetis, c. economou, the influence of high temperatures on calibration of non-destructive testing of concrete), 14(79)1979, materiaux et constructions. [6] m. y. l. chew, the assessment of fire damaged concrete, building and environment, 28(1), 1993, pp 9710. [7] e.a. whitehurst, soniscope tests concrete structures, j. am. concr. inst. 47, 1951, pp 443 – 444. [8] h.w.chung (1985), ultrasonic testing of concrete after exposure to high temperatures, mndt international. vol 18. no 5. 1985 [9] s. l. suhaendi,t.horiguch, effect of short fibers on residual permeability and mechanical properties of hybrid fibre reinforced high strength concrete after heat exposition cemconcr res 36, 2006, pp 1672–1678. [10] p. y. pawade, performance of steel fiber on standard strength concrete in compression, international journal of civil and str structural engineering volume 2, no 2, 2011, issn 0976 – 4399. [11] k. prasopchaichana, evaluating the compressive strength of concrete exposed to elevated temperatures using ultrasonic pulse velocity and artificial neural networks, 6th european workshop on structural health monitoring poster 17 [12] i. hager, h. carré and k. krzemień,damage assessment of concrete subjected to high temperature by means of the ultrasonic pulse velocity – upv method studies and researches – v.32, graduate school in concrete structures – fratellipesenti, politecnico di milano, italy, 2013. [13] o. deoye m, domestication of pundit non-destructive test chart in measuring compressive strength of normal strength concrete subjected to elevated temperature ,australian journal of basic and applied sciences, 7(1): 16, 2013 , issn 1991-8178 [14] nf en 12390-3. essai pour béton durci – partie 3: résistance à la compression des éprouvettes, indice de classement: p 18-455, 2003. [15] y. f chang; y. h chen, m. s sheu, g.c yao, residual stress-strain relationship for concrete after exposure to high temperatures, cement and concretes resarch 36 (10), 2006, pp 1999-2005. [16] a. lau, m. anson, effect of high temperatures on high performance steel fiber reinforced concrete. cement concrete res; 2006, 36:1698–707. [17] p. pliya, a.l beaucour, a. noumowé, strength and porosity of concrete incorporating polypropylene and steel fibres subjected to high temperature. in: 20th international conference on structural mechanics in reactor technology, espoo, finland, 2009, pp 9–14. [18] c.s poon, z.h shui, l. lam, compressive behavior of fiber reinforced highperformance concrete subjected to elevated temperatures. cement concrete res, 34, 2004, pp 2215–22. [19] s.k. handoo, s. agarwal, s.k. agarwal, physicochemical, mineralogical, and morphological characteristics of concrete exposed to elevated temperatures , cement and concrete research 32, 2002, pp 1009 – 1018. [20] h. yang, y. lin, c. hsiao, j.y liu, evaluating residual compressive strength of concrete at elevated temperatures using ultrasonic pulse velocity, fire safety journal 44 , 2009, pp 121– 130. [21] y. lin, c. hsiao, h. yang, y.f lin, the effect of postfire-curing on strength–velocity relationship for nondestructive assessment of fire-damaged concrete strength, fire safety journal 46, 2011, pp 178–185. [22] savva, p. manita, k.k. sideris, influence of elevated temperatures on the mechanical properties of blended cement concretes prepared with limestone and siliceous aggregates, cement concr. compos. 27, 2005, pp 239– 248. b. hassiba et al. ijeca-issn: 2543-3717. june 2018 page 36 [23] j. xiao, h. falkner, on residual strength of highperformance concrete with and without polypropylene fibres at elevates temperatures. fire safety, 41 2006, pp 115–21. [24] m. zeiml, d. leithner, r. lackner, h. mang, how do polypropylene fibers improve the spalling behavior of insitu concrete? cement concrete res. 2006. [25] a. noumowé, mechanical properties and microstructure of high strength concrete containing polypropylene fibers exposed to temperatures up to 200°c. cement concrete res, 35, pp 2192–8. [26] a. behnood, m. ghandehari, comparison of compressive and splitting tensile strength of high-strength concrete with and without polypropylene fibers heated to high temperatures. fire safety j 2009. [27] g.f peng, w.w yang, j. zhao, y.f liu, s.h bian, l.h zhao, explosive spalling and residual mechanical properties of fiber-toughened high-performance concrete subjected to high temperatures. cement concrete res, 36, pp 723–7. [28] p. pliya, a.l beaucour, a. noumowé, a way to improve the behaviour of concrete at high temperature: addition of a cocktail of polypropylene and steel fibres. in: international fib congress and pci annual convention/exhibition, washington, 2010. [29] b. chen, j. liu, (2004), residual strength of hybrid-fiber reinforced high strength concrete after exposure to high temperature. cement concrete res,34:1065–9 [30] r. demirbog, i. turkmenk, m.b. karakoc, relationship between ultrasonic velocity and compressive strength for high-volume mineral-admixture concrete, cement and concrete research 34, 2004, pp 2329 – 2336. [31] tharmaratnam, b.s. tan, attenuation of ultrasonic pulse in cement mortar, cem. concr. res. 20, 1990, pp 335 – 345. [32] d. breysse, nondestructive evaluation of concrete strength: an historical review and a new perspective by combining ndt methods, construction and building materials 33, 2012, 139–163. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 11-16 ijeca-issn: 2543-3717. june 2019 page 11 detection and diagnosis faults in machine asynchronous based on single processing ibrahim chouidira 1* , djalal eddine khodja 2 , hani benguesmia 3 1,2electrical engineering laboratory (lge), university of mohamed boudiafm’sila, algeria 3department of electrical engineering, faculty of technology, university of mohamed boudiaf, m’sila, algeria e-mail*: ibrahimchouidira@yahoo.com. abstract – in this work, we proposed multi-winding model for the simulation of broken bars in squirrel cage asynchronous machine, this model allows to study the influence of the broken bar defects on the behavior general of machines in different operating conditions (healthy and faulty). the breaking of the most frequent bars of the rotor causes oscillations of the torque, speed, and the current, the increase of the resistance of the rotor creates the defects proportional with the number of breaks bar k .the diagnosis fault using technique of single processing based on spectrum analysis for detection broken bar. the results of the simulation obtained allowed us to show the importance of this technique for detection broken bar. keywords: machine asynchronous, spectrum analysis, fft, detection, diagnosis, broken bat. received: 28/02/2019 – accepted: 20/04/2019 i. introduction the fault diagnosis induction motors are component of many industrial processes applications, because of their robustness, cost, and performance and used in wide variety of application of a mean of converting energy, pumps, electric vehicle and asynchronous generator [1] [2]. major faults of electrical machines can broadly be classified as the following: stator faults, broken rotor bar, faults bearing are the most prevalent [3-4]. mcsa (motor current signature analysis) this work is the topic of several research works used to find out various faults such as: the impact of broken rotor bar to the stator current can be determined by analysing in the frequency [5-6]. the analysis of the stator current spectrum around the fundamental frequency current is used to diagnose the fault. and appear the amplitudes of the frequency components are increased because of the exists defect according relation (1±2s)fs [7]. in this work, we presented multi-winding model for simulate the machine behavior in case healthy and fault when broken bar, the faults diagnosis is based on technique of single processing very important for detection rotor fault in the asynchronous machine. ii. fault detection of induction motor ii.1. detection of broken bars broken rotor bars can be detected by monitoring the stator current spectral components. these spectral components as in (1) [8]: (1) where s is the per-unit motor slip and k =1,2,3,4…..etc. the amplitude of the left sideband is proportional to the number of broken bars. the spectral component associated with broken rotor bars is found at the frequency, (1 ± 2s)fs. these two frequencies (1 2s)fs and (1 + 2s)fs are the classical twice slip frequency sidebands due to the broken bar [9].figure. 1 picture show the bar broken used for the simulation study. figure 1.picture show the two bar broken adjacent abder image placée ibrahim chouidira et al ijeca-issn: 2543-3717. june 2019 page 12 ii.2. techniques of single processing for faults detection analysis by signal processing of quantities (current, voltage and power) can give a real picture of the imbalances that which happen in the machine, the advancement techniques of signal processing in field mechanical, the frequency in the signal become very important part of the detection of the rotor fault in the induction motor [10]. this analysis is based on classical techniques such as fourier analysis (fft). the fourier transform is as in (2): (2) fourier analysis is very useful for many applications where the signals are stationary. iii. multi-winding model of the asynchronous machine the model of the asynchronous takes into account the following hypotheses [11-12]:  negligible saturation and skin effect,  uniform air-gap,  sinusoidal mmf of stator windings in air-gap,  rotor bars are insulated from the rotor, thus no interbar current flows through the laminations,  relative permeability of machine armatures is assumed infinite. although the mmf of the stator windings supposed is to be sinusoidal, other distributions of rolling up could also be considered by simply employing the superposition theorem. it is justified by the fact that the different components of the space harmonics do not interact. in order to study the phenomena taking place in the rotor, the latter is often modeled by nr meshes as shown on figure 2. figure .2 rotor cage equivalent circuit. a. stator inductance the principal inductance of the magnetizing stator phase is: (3) therefore the total inductance of a phase is equal to the sum of the magnetizing and leakage inductances, thus: (4) the mutual inductance between the stator phases is computed as: (5) b. rotor inductance the form of the magnetic induction produced by a rotor mesh in the air-gap is supposed to be radial and is represented in figure 3. the principal inductance of a rotor mesh can be calculated from the magnetic induction distribution [11-12]: figure .3 form of magnetic induction of rotor mesh created by two bar the total inductance of the kth rotor mesh is equal to the sum of its principal inductance, inductance of leakage of the two bars and inductance of the leakage of the two portions of rings of the short circuit closing the mesh k as indicated in figure 4. figure .4 electric diagram equivalent of a rotor mesh. re le nr nr rbklbk , 1 rb (k-1)lb(k-1) , 2 ibk ib(k-1) iek irk ir(k-1) ir(k+1) re le nr nr (nr -1)μ0 nr e bk 0 (k+1)a 2 π θ ka a 2π nr -μ0 nr e ir ir irk ir ibrahim chouidira et al ijeca-issn: 2543-3717. june 2019 page 13 (6) (7) (8) the expression for the mutual inductance stator-rotor is can be calculated using the flux and is given by: (9) where: (10) and: (11) the application of transformation the park's extended of rotor system so as to transform the system in nr phases in a system (d,q). the mathematical model of squirrel cage induction motor can be written as: (12) c. defect model of the rotor in order to simulate the defect of rotor broken bars, a fault resistance rrf is added to the corresponding element of the rotor resistance matrix rr: the new matrix of rotor resistances, after transformations, becomes: where the four terms of this matrix are: . the mechanical equations must also consider: (13) with : the electromagnetic torque with the expression: (14) iv. results and discussion iv.1 the case of healthy machine for observe and simulate the multi-winding model of the asynchronous machine. at time 0.5 s apply in load torque of 3.5 (n.m). figure.5 and figure. 6 and figure. 7, we indicate the evolution respectively the speed of rotation, the electromagnetic torque, stator currents, we notice speed of rotation decreases at nominal and the electromagnetic stabilizes towards the value of the resistance torque, the current stator increases and reach value nominal. figure. 5 speed for the healthy machine. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 50 100 150 200 250 300 350 w ( ra d /s ) t(s) ibrahim chouidira et al ijeca-issn: 2543-3717. june 2019 page 14 figure. 6 electromagnetic torque for the healthy machine. figure. 7 stator current for the healthy machine. iv.2 the case of fault machine the time t=1 ,simulates the breaking of the first bar ,the time t = 2 s, breaking two bar adjacent, and the time t = 3 s, breaking three bar adjacent, we observation in the figure.8 of rotational speed decreases during bar break and creates oscillations break the figure.9 electromagnetic torque increase in the amplitude after the breaking of two bar, ,and the figure.10 are illustrated modulation of the envelope of the stator current increase in the amplitude withe the number of broken bar. figure. 8 speed for broken three bar adjacent. figure. 9 electromagnetic torque for broken three bar adjacent. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 50 100 150 200 250 300 350 w ( ra d /s ) t(s) laod break two bar break one bar break three bar 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -10 0 10 20 30 40 50 t(s) break three bar break two bar break one bar laod e le ct ro m ag n et ic t o rq u e ( n m ) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -5 0 5 10 15 20 25 30 35 t(s) e le ct ro m ag n et ic t o rq u e ( n m ) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -15 -10 -5 0 5 10 15 20 t(s) is a (a ) ibrahim chouidira et al ijeca-issn: 2543-3717. june 2019 page 15 figure. 10 stator current for broken three bar adjacent. figure. 11 shows spectrum analysis of the stator current through the hanning window in the healthy state, we observe no raise frequency. figure. 12, we notice the appearance of raise frequency for broken three bar adjacent. these raise have amplitude which increases according of the break number bars, two frequencies appear around the fundamental f=50 hz, one on the left and the other right according relation fcal= (1 ± 2sk). figure.11 stator current spectrum analysis for the healthy machine. figure.12 stator current spectrum analysis for broken three bar adjacent. the amplitudes and frequencies for tests broken three bar adjacent are recorded in table 1. table. 1 frequencies and magnitudes of the stator current : healthy and broken three bar adjacent the table 1 represents simulation frequencies and magnitude the current stator spectral for broken three bar adjacent. frequency and magnitude of broken bar (1-4s)fs (1-2s)fs (1+2s)fs (1+4sk)fs healthy / / / / b ro k en t h re e b a r ad ja ce n t m ag n it u d e (d b ) -35.70 -24.29 -29.86 -58.08 f (h z) 32.18 41.25 59.12 61.91 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -20 -15 -10 -5 0 5 10 15 20 is a (a ) t(s) 0 50 100 150 200 250 300 -200 -150 -100 -50 0 50 m ag n it u d e (d b ) frequency (hz) 0 50 100 150 200 250 300 -150 -100 -50 0 50 (1+2s)fs (1+4s)fs (1-2s)fs (1-4s)fs (1+6s)fs (1-6s)fs frequency (hz) m ag n it u d e (d b ) ibrahim chouidira et al ijeca-issn: 2543-3717. june 2019 page 16 iv. conclusion this study allows us highlighting on fault diagnosis technique are based on signal processing by spectral analysis of stator current analysis this method is very effective and widely used for detection the fault. further using multi windings model for simulation broken bars. when applying the faults we obtain reduces the average value of electromagnetic torque and speed and increases the amplitude of oscillations. the current stator effect of bar break increases rapidly with the number of broken bars. appendix list of parameter and symbols parameters value units pn 1.1 kw vs 220 v fs 50 hz p 1 rs 7.58 ω rr 6.3 ω rb 0.15 m ω re 0.15 m ω lb 0.1 μh le 0.1 μh lsf 0.0265 h nr 16 ns 160 j 0.0054 kg m 2 e 2 mm acknowledgements this work was supported electrical engineering laboratory (lge), at the university of mohamed boudiafm’sila, (algeria). we like to thanks dr. djalal eddine khodja, and dr. hani benguesmia, for their helps in the preparing of this paper. references [1] subhasis nandi, hamid a. toliyat,, xiaodong li, "condition monitoring and fault diagnosis of electrical motors—a review", ieee transactions on energy conversion, vol. 20, n°4, december 2005, pp. 719-729. [2] o. moussa, d. khodja, h. benguesmia, "comparative study between sliding mode control and the vectorial control of a brushless doubly fed induction generator ",international journal of energetica (ijeca), vol. 3, 2018, issue 2, pp. 22-28. [3] a. lebaroud, guy clerc, ''classification of induction machine faults by optimal timefrequency representations'', ieee transactions on industrial electronics, institute of electrical and electronics engineers, vol. 55, no. 12, december 2008, pp.4290 4298. [4] p.j. tavner, "review of condition monitoring of rotating electrical machines. electric power applications", iet electr. power appl., 2008, vol. 2, no. 4, pp. 215–247. doi: 10.1049/iet-epa:20070280. [5] pratesh jayaswal, a. k.wadhwani, k. b.mulchandani, "machine fault signature analysis", international journal of rotating machinery volume 2008, article id 583982, 10 pages doi:10.1155/2008/58398 [6] chaitali s. kalaskar, vitthal j. gond, "motor current signature analysis to detect the fault in induction motor",journal of engineering research and applications, issn : 2248-9622, vol. 4, issue 6 (version 1), june 2014, pp.58-61. [7] szabó loránd – dobai jenő barna – biró károly ágoston, "rotor faults detection in squirrel-cage induction motors by current signature analysis", ieeetttc, international conference on automation, quality and testing, robotics may 13 – 15, 2004.. [8] k.m. siddiqui, v.k. giri, "broken rotor bar fault detection in induction motors using transient current analysis", international journal of electronics & communication technology, vol. 2, issue. 4, october – december 2011, pp. 114–119. [9] neelam mehala, ratna dahiya, "motor current signature analysis and its applications in induction motor fault diagnosis", international journal of systems applications, engineering & development, vol. 2, issue.1, 2007, pp. 29–35. [10] dragan matić, željko kanović, vladimir bugarski, filip kulić, dejan reljić, đura oros, veran vasić, "detection of the broken bar fault. a case study for a 3.2 mw induction motor detekcija otkaza slomljene šipke. analiza asinhronog motora 3,2mw ", journal on processing and energy in agriculture, 17:3, 2013, pp. 134–137. [11] a. menacer, s. moreau, a. benakcha, m.s. nait said "effect of the position and the number of broken bras on asynchronous motor stator current spectrum", epe-power electronics and motion control, portoroz, slovenia, 2006, pp 973-978. [12] a. menacer, a. benakcha, m.s. nait said, s. drid, "stator current analysis of incipient fault into asynchronous motor rotor bars using fourier fast transform", journal of electrical engineering, vol. 55, n°5-6, 2004, pp 122-130. i. introduction iv. conclusion appendix acknowledgements international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 8. issue 1. 2023 page 24-30 this open access article is licensed under the cc by-nc license (https://creativecommons.org/licenses/by-nc/4.0/) page 24 optimal tilt angle for photovoltaic panels in the algerian region of eloued in the spring season: an experimental study soulef largot 1 , noureddine bessous 1 , mokhtar ghodbane 2* , boussad 2 , rania zhar 3 , khadija lahrech 3 1 electrical engineering department, university of el-oued, algeria 2 mechanical engineering department, faculty of technology, saad dahlab university of blida 1, blida 09000, algeria 3 sidi mohamed ben abdellah university. lipi laboratory ens national school of applied science ensa, fez, morocco * corresponding author e-mail: ghodbanemokhtar39@yahoo.com abstract – the tendency to exploit solar energy in the electricity production in algeria is a priority and a major goal of the algerian government, and for this reason it seeks to provide all the necessary capabilities to achieve this lofty goal. photovoltaic electricity is one of the effective technologies for the solar electricity production, but before installing any photovoltaic panel, it is important to determine its optimal tilt angle, and based on this, this study allowed to show the optimal tilt angle of the photovoltaic panels in the algerian region of el oued in the spring season, and accordingly, two days (march 21 st , 2023, and april 21 st , 2023) were chosen to conduct this experimental study. based on the obtained results, the optimal pv tilt angle for the month of march is 33° and 28° for the month of april. in addition, the greater the amount of solar radiation, the higher the efficiency and productivity of the pv panels, as the highest values for them (6.31 % and 62.17 w, respectively) were recorded on april 21st, 2023. the results of this study will contribute to the correct installation of photovoltaic panels in the algerian region of el-oued, especially if the photovoltaic panels are equipped with dual-axis solar tracking systems. keywords: solar electricity production, photovoltaic panels, optimal tilt angle, productivity; performance. received: 20/05/2023 – revised: 12/06/2023 – accepted: 20/06/2023 i. introduction c rr tly, th w rl 's i s rc f rgy is f ssil f ls (g s, il, c l), which is li it s rc i t r s bj ct t pl ti , -r w bl , its p ll ti g g s s t th vir t. th t is why th s rch f r lt r tiv , cl , s st i bl , r w bl s rc s is pri rity f r ll c tri s f th w rl [1], sp ci lly alg ri . th alg ri g v r t c r g s th sp y st blish t f i fr str ct r f r th xpl it ti f r w bl rgy s rc s, sp ci lly s l r rgy. i r r t chi v this l fty g l, which is th xpl it ti f s l r rgy i y t ch l gic l fi l s, y sci tific r s rch s p blish i i x sci tific j r ls sh w th t alg ri r c iv s ily h g t f s l r r i ti , s th i s l ti r ti i alg ri is b tw 2000 3900 h rs/y r th v r g v il bl rgy is b tw 1700 2650 kwh/ ², i. . 5 kwh/ ² p r y i st p rts f th ti l t rrit ry [2, 3]. i th lit r t r , y st i s h v b c ct pplic ti s th t ll w th r w bl rgy xpl it ti i alg ri , s t ch s l r istill ti i r r t pr vi p t bl w t r [4, 5]. it w s ls f th t s i t l. h v c ct s v r l xp ri ts th p ssibility f si g li r fr s l r fl ct rs s s l r w t r h t rs i th alg ri r gi f li [6, 7], th y h v r ch th p ssibility f i pr vi g th p rf r c f th s li r s l r https://www.ijeca.info/ https://creativecommons.org/licenses/by-nc/4.0/ soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 25 c c tr t rs by isp rsi g p rticl s i p r w t r [8, 9]. i iti , gh b t l. h v c ct xp ri t l, ric l, cfd li g f s l r w t r h t rs si g li r fr s l r fl ct rs [10, 11]. m r v r, s rch st i ric lly th p ssibility f si g p r b lic tr gh c ll ct rs i c t rs i stri l f ciliti s t h t i stri l ils (mx b s silic il fl i s) [12], k wi g th t t ch l gy is c rr tly xp ri ci g c ti s zi g v l p t, it is i t f r s i y i stri l fi l s [13, 14]. a th r s rch h v st i ric lly th p ssibility f si g li r fr s l r fl ct rs i c t rs i stri l f ciliti s t h t i stri l ils (mx b s silic il fl i s) [15]. als , r s rch gr p h s pr v th p ssibility f si g li r s l r c c tr t rs t riv ir c iti rs by r vi g th c pr ss r r pl ci g it with j ct r p p [16-18]. h r , p r b lic tr gh c ll ct rs r li r fr s l r fl ct rs c b s , s p r b lic tr gh c ll ct rs r r ptic l th r l ffici t [19-22], b t li r fr s l r fl ct rs r l ss xp siv [23]. m r v r, li r fr s l r fl ct rs c b s t pr c s l r th r l l ctricity [24, 25], s s l r l ctric st ti s c b st blish i alg ri th t p r t with th s li r s l r c c tr t rs th ir l v liz c st f rgy is v ry cc pt bl c p r t f ssil l ctricity [26]. s v r l st i s h v c ct ric l st y s l r w t r isi f cti si g s ll li r fr s l r fl ct rs [27]. r c t w rk h v cr t g r l lg rith i i g t fi th pti l l y t f ph t v lt ic p ls irr g l rly sh p s rf c s [28]. i iti , it h s b f th t f r á z-r bi r t l. h v st i s w-t th tr gh v-c vity f r l wc c tr ti ph t v lt ic syst s b s s ll li r fr s l r fl ct rs [29]. as t , th r is l t f r s rch i th lit r t r c r gi g tr t w r s th xpl it ti f s l r rgy i y fi l s i p rt t t ch l gic l pplic ti s i alg ri . th i bj ctiv f this st y is t t r i th pti l tilt gl f th ph t v lt ic p ls i alg ri r gi f el-o i th spri g, th r f r , pr ctic l xp ri ts w r c ct tw ph t v lt ic p ls (pv) th t h v th s t ch ic l ch r ct ristics. th xp ri t l st y w s c ct cc r i g t th p r t rs sh w i t bl 1. wh t r i i g th pti l pv tilt gl , ll gi rs t ch ici s will b bl t c rr ctly i st ll th pv syst s (st l pv syst s, gri -c ct pv syst s) i el-o r gi , this will bl th s pvs t giv th gr t st pr ctivity b r ff ctiv . ii. materials and methods th xp ri t l w rk w s c rri t tw ph t v lt ic p ls with si il r t ch ic l ch r ct ristics. th alg ri r gi f el-o (33.57°, 6.77, 50) w s s l ct f r th st y. th xp ri t l st ps w r s f ll ws: acq isiti f tw ph t v lt ic p ls (raggie typ , rg-m165w l) is with c p city f 165 w tts. th t ch ic l ch r ct ristics f th tw ph t v lt ic p ls r st y r sh w i fig r 1. figure 1. st i ph t v lt ic p ls th ir t ch ic l ch r ct ristics  m f ct r f t l h l rs f r ph t v lt ic p ls, s th s pv h l rs c v i b th ir cti s, v rtic l (t tr ck th s 's h ight, ch g th tilt pv gl ) h riz t l (t tr ck th s 's p th fr st t w st). th s f ct r st l s pp rts c h l th ph t v lt ic p ls i b th v rtic l h riz t l p siti s.  acq isiti f s ri g vic s f r cli tic c iti s (pyr t r pyr 1307 t s r th s l r gl b l r i ti , a t r m t r (am4206m) t s r th wi sp , a t r m t r (am-4206m) t s r th bi t ir t p r t r .  acq isiti f s ri g vic s f r l ctric l p r t rs (digit l m lti t r mx 20 (metrixtyp ) t s r th l ctric c rr t), digit l m lti t r ct44053 (crown-typ ) t s r th soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 26 l ctric l v lt g . t t , th l ctric l r sist c h s b fix t 5 ω si g v ri bl r sistiv l f th ecodime-typ .  c rryi g t th sir pr ctic l xp ri ts i tw ys (march 21 st , 2023, and april 21 st , 2023) f spri g. as ti pr vi sly, th i f th st y is t t r i th pti l pv tilt gl i th alg ri r gi f el-o , cc r i gly, ch ph t v lt ic p l h s b li k t th l ctric l s ri g vic s t f r l ctric l cycl , cc r i gly, st y f tw l ctric l circ its si lt sly r th s cli tic c iti s h s b st i . b t r iff r t xp ri t l c iti s s sh w i t bl 1.  as sh w i fig r 2 , th first circ it will b c ll th "r f r c l ctric l circ it (rc)", it will c t i th r f r c ph t v lt ic p l (pvr), igit l lti t r mx 20 (metrix-typ ), ecodime l ctric l r sist c fix t 5 ω, ll thr f which r c ct i s ri s, whil th igit l lti t r ct44053 (crown-typ ) t s r th l ctric l v lt g will b c pl i p r ll l with th v ri bl r sistiv l .  as sh w i fig r 2b, th s c circ it will b c ll th " l ctric l circ it r v ri bl c iti s (ecvc)", it will c t i th ph t v lt ic p l r v ri bl c iti s (pvcv), igit l lti t r mx 20 (metrix-typ ), ecodime l ctric l r sist c fix t 5 ω, ll thr f which r c ct i s ri s, whil th igit l lti t r ct44053 (crown-typ ) t s r th l ctric l v lt g will b c pl i p r ll l with th v ri bl r sistiv l . figure 2. st i l ctric l circ its t bl 1 c t i s th xp ri t l c iti s f r th tw ph t v lt ic p ls, b ri g i i th t th tw st i ph t v lt ic p ls h v b s bj ct t pr vi s pr ctic l xp ri ts r th s cli tic c iti s th s xp ri t l c iti s t v rify th ir t ch ic l pr ctic l si il rity. t t , th r s lts f pr vi s xp ri ts h v pr v gr t c v rg c i th pr ctivity f th tw p ls r th s xp ri t l c iti s, wh r s ll iff r c i p w r f (p = 0.41v × 0.069a = 0.02869 watt) w s r c r b tw th . this r s lt (p = 0.02869 watt) pr v th cc r cy f th r s lts bt i , wh r th pr ctivity f th tw ph t v lt ic p ls (pvr pvcv) is v ry cl s r th s p r ti g c iti s. table 1. exp ri t l c iti s f r th st y pvr pvcv d a y t il t a n g le ( °) t r a c k in g s y st e m e ff e c ti v e a p e r tu r e c o n d it io n t il t a n g le ( °) t r a c k in g s y st e m e ff e c ti v e a p e r tu r e c o n d it io n 0 3 /2 1 /2 0 2 3 33 s t ti ry ri t t t h s th c l 28 s t ti ry ri t t t h s th c l 0 4 /2 1 /2 0 2 3 33 s t ti ry ri t t t h s th c l 28 s t ti ry ri t t t h s th c l with r g r t th q ti s s t c lc l t th tp t f th ph t v lt ic p l its ffici cy, th y r s f ll ws: p = i × v (1) η = p apv × ig (2) soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 27 wh r , p is th pv tp t (w), i is th l ctric c rr t (a), v is th l ctric l v lt g (v), η is th pv ffici cy (%), apv is th ff ctiv pv p rt r ( ²), ig is th s r gl b l irr i c (w/ ²). iii. results and discussion this st y will ll w t r i i g th pti l pv tilt gl i th alg ri r gi f el o . as it is k w , th p rf r c pr ctivity f y ph t v lt ic p l is ir ctly r l t t ch gi g cli tic c iti s, i p rtic l r, th t f gl b l s l r r i ti th t r ch s its ff ctiv p rt r . fig r 3 sh ws th ch g i th cli tic c iti s th st i ys i t r s f th ch g f ti fr 06h00 t 17h00 (th ti wh th pr ctic l xp ri ts w r c ct ). fr fig r 3, th f ll wi g c b c cl :  th gl b l s l r r i ti f r y (april 21 st , 2023) is gr t r th th r c r gl b l s l r r i ti f r y (m rch 21 st , 2023), wh r th high st v l f 1001 w/ ² w s r c r t 11h00. thr gh this, it is c cl th t th p rf r c pr ctivity f th ph t v lt ic p l will b b tt r i th y (april 21 st , 2023), this is wh t is sh w i fig r 4. figure 3. m s r w th r t vs. ti  th bi t ir t p r t r f r y (april 21 st , 2023) is gr t r th th bi t ir t p r t r f r y (m rch 21 st , 2023), s th high st v l f 27.6 °c w s r c r t 16h00. t t , ph t v lt ic p ls r r pr ctiv wh bi t ir t p r t r s r r t r g i g t l w, b c s high ir t p r t r s r c th p rf r c pr ctivity f ph t v lt ic p ls t v lt g r p. th s, il s y y is th b st c iti f r pti l p rf r c pr ctivity f th ph t v lt ic p ls.  th wi sp f r y m rch 21 st , 2023) w s gr t r th th wi sp f r y (april 21st, 2023), wh r th high st v l f 7.6 /s w s r c r t 08h00. with th v c t f t ch l gy, ph t v lt ic p ls h v b c r s phistic t fl xibl , s th y c pr c l ctricity i iffic lt cli tic c iti s. th r f r , c st rs st h v p rst i g f th cli tic c iti s f th r i which th ph t v lt ic p ls r t b i st ll , i r r t b bl t k i f r cisi s r g r i g ph t v lt ic pr j cts. fig r 4 sh ws th ch g i th ffici cy pr ctivity f th tw ph t v lt ic p ls (pvr pvcv). fr th c rv s f fig r 4, it h s b bs rv th t: figure 4. o tp t ffici cy f th st i ph t v lt ic p ls  pr ctivity p rf r c y (april 21 st , 2023) is b tt r th p rf r c pr ctivity y (m rch 21 st , 2023), b c s y (april 21 st , 2023) w s f ll f gl b l s l r r i ti c p r t th th r y. it is k w th t ph t v lt ic p ls will pr c th xi t f l ctric l rgy wh th s 's r ys r p rp ic l r t its ff ctiv p rt r , this c ly h pp thr gh t th y si g s -tr cki g syst s. if s -tr cki g syst s r t s , th ph t v lt ic p ls st b ir ct t th si th t s r s th t th s l r r ys f ll s l g s p ssibl th ph t v lt ic p ls. i alg ri , th ph t v lt ic p ls st b ir ct t th s th b c s th s 's p th is i cli t th s th. soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 28  th pti l pv tilt gl i m rch is 33°, wh r th pvr p l g v th b st ffici cy th b st pr ctivity with v l s f 5.41% 46.7 w, r sp ctiv ly, t 12h00.  th pti l pv tilt gl i m rch i april is 28°, wh r th pvcv p l g v th b st ffici cy th b st pr ctivity with v l s f 6.31 % 62.17 w, r sp ctiv ly, t 11h00. alth gh th st y w s c ct i tw ys i th spri g s s , th st y r s lts pr v th t i th s s s th pti l pv tilt gl i th alg ri r gi f el-o ch g s fr th t th. this ch g is t th lliptic l p th f th rth's r t ti r th s ch g s its i cli ti gl s w ll cc r i g t th s s . th ph t v lt ic p ls th t r i st ll i th alg ri r gi f el-o h v pti l i cli ti gl v ry th, t k w its v l cc r t ly, th p th f th s st b tr ck ily fr s ris t s s t f r p ri f y r. iv. conclusions s l r rgy c b s t g r t l ctric rgy by i st lli g ph t v lt ic syst th t c t i s ph t v lt ic c lls th t c v rt s l r ph t v lt ic rgy ir ctly i t l ctricity. th i bj ctiv f this xp ri t l st y is t fi t th pti l pv tilt gl i th alg ri r gi f el-o i th spri g s s . th r s lts f th st y sh w th t i th s s s , iff r t pti l pv tilt gl s c b bt i fr th t th. this iff r c i th pti l pv tilt gl fr th t th r is t th c ssity th t th ff ctiv pv p rt r st b c pl t ly p rp ic l r t th s l r r i ti c i g t it, th t th p th f th s ch g s fr th t th r t th lliptic l p th f th rth's r t ti r th s . th st i p rt t c cl si f this st y is th t th pti l pv tilt gl f r th th f m rch is 33° 28° f r th th f april. i iti , th gr t r th t f s l r r i ti , th high r th ffici cy pr ctivity f th pv p ls, s th high st v l s f r th (6.31 % 62.17 w, r sp ctiv ly) w r r c r april 21 st , 2023. th r s lts f this st y will c trib t t th c rr ct i st ll ti f ph t v lt ic p ls i th alg ri r gi f el-o , sp ci lly if th ph t v lt ic p ls r q ipp with lxis s l r tr cki g syst s. declaration  th th rs cl r th t th y h v k w fi ci l r -fi ci l c p ti g i t r sts i y t ri l isc ss i this p p r.  th th rs cl r th t this rticl h s t b p blish b f r is t i th pr c ss f b i g p blish i y th r j r l.  th th rs c fir th t th p p r w s fr f pl gi ris . references [1] r. zhar, a. allouhi, m. ghodbane, a. jamil, k. lahrech, "parametric analysis and multi-objective optimization of a combined organic rankine cycle and vapor compression cycle," sustainable energy technologies and assessments, vol. 47, 2021, pp. 101401. https://doi.org/10.1016/j.seta.2021.101401. [2] m. ghodbane, b. boumeddane, "estimating solar radiation according to semi-empirical approach of perrin de brichambaut: application on several areas with different climate in algeria," international journal of energetica, vol. 1, 2016, pp. 20-29. https://doi.org/10.47238/ijeca.v1i1.12. [3] m. ghodbane, b. boumeddane, "a numerical analysis of the energy behavior of a parabolic trough concentrator," journal of fundamental and applied sciences, vol. 8, 2016, pp. 671-691. https://doi.org/10.4314/jfas.v8i3.12. [4] a. khechekhouche, b. benhaoua, m.e.h. attia, z. driss, a. manokar, m. ghodbane, "polluted groundwater treatment in southeastern algeria by solar distillation," algerian journal of environmental science and technology, vol. 6, 2020. available at: https://www.aljest.net/index.php/aljest/article/view/269/2 60. [5] a. khechekhouche, n. smakdji, m. el haj assad, a.e. kabeel, m. abdelgaied, m. ghodbane, a. allal, r. sathyamurthy, "impact of solar energy and energy storage on a still's nocturnal output," journal of testing and evaluation, vol. 51, 2023, pp. 20220701. https://doi.org/10.1520/jte20220701. [6] z. said, m. ghodbane, a.k. tiwari, h.m. ali, b. boumeddane, z.m. ali, "4e (energy, exergy, economic, and environment) examination of a small lfr solar water heater: an experimental and numerical study," case studies in thermal engineering, vol. 27, 2021, pp. 101277. https://doi.org/10.1016/j.csite.2021.101277. [7] z. said, m. ghodbane, a.a. hachicha, b. boumeddane, "optical performance assessment of a small experimental prototype of linear fresnel reflector," case studies in thermal engineering, vol. 16, 2019, pp. 100541. https://doi.org/10.1016/j.csite.2019.100541. [8] z. said, m. ghodbane, l.s. sundar, a.k. tiwari, m. sheikholeslami, b. boumeddane, "heat transfer, entropy generation, economic and environmental analyses of https://doi.org/10.1016/j.seta.2021.101401 https://doi.org/10.47238/ijeca.v1i1.12 https://doi.org/10.4314/jfas.v8i3.12 https://www.aljest.net/index.php/aljest/article/view/269/260 https://www.aljest.net/index.php/aljest/article/view/269/260 https://doi.org/10.1520/jte20220701 https://doi.org/10.1016/j.csite.2021.101277 https://doi.org/10.1016/j.csite.2019.100541 soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 29 linear fresnel reflector using novel rgo-co3o4 hybrid nanofluids," renewable energy, vol. 165, 2021, pp. 420437. https://doi.org/10.1016/j.renene.2020.101154. [9] m. ghodbane, z. said, a.a. hachicha, b. boumeddane, "performance assessment of linear fresnel solar reflector using mwcnts/dw nanofluids," renewable energy, vol. 151, 2020, pp. 43-56. https://doi.org/10.1016/j.renene.2019.101137. [10] m. ghodbane, e. bellos, z. said, b. boumeddane, a.k. hussein, l. kolsi, "evaluating energy efficiency and economic effect of heat transfer in copper tube for small solar linear fresnel reflector," journal of thermal analysis and calorimetry, vol. 143, 2021, pp. 4197-4215. https://doi.org/10.1007/s10973-020-09384-6. [11] m. ghodbane, b. boumeddane, n. said, "a linear fresnel reflector as a solar system for heating water: theoretical and experimental study," case studies in thermal engineering, vol. 8, 2016, pp. 176-186. https://doi.org/10.1016/j.csite.2016.06.006. [12] z. said, m. ghodbane, b. boumeddane, a.k. tiwari, l.s. sundar, c. li, n. aslfattahi, e. bellos, "energy, exergy, economic and environmental (4e) analysis of a parabolic trough solar collector using mxene-based silicone oil nanofluids," solar energy materials and solar cells, vol. 239, 2022, pp. 111633. https://doi.org/10.1016/j.solmat.2022.111633. [13] z. said, p. sharma, n. aslfattahi, m. ghodbane, "experimental analysis of novel ionic liquid-mxene hybrid nanofluid's energy storage properties: modelprediction using modern ensemble machine learning methods," journal of energy storage, vol. 52, 2022, pp. 104858. https://doi.org/10.1016/j.est.2022.104858. [14] a.k. hussein, m. ghodbane, z. said, r.s. ward, "the effect of the baffle length on the natural convection in an enclosure filled with different nanofluids," journal of thermal analysis and calorimetry, vol. 147, 2022, pp. 791-813. https://doi.org/10.1007/s10973-020-10300-1. [15] m. ghodbane, z. said, a.k. tiwari, l.s. sundar, c. li, b. boumeddane, "4e (energy, exergy, economic and environmental) investigation of lfr using mxene-based silicone oil nanofluids," sustainable energy technologies and assessments, vol. 49, 2022, pp. 101715. https://doi.org/10.1016/j.seta.2021.101715. [16] m. ghodbane, z. said, o. ketfi, b. boumeddane, a.t. hoang, m. sheikholeslami, m.e.h. assad, m. hossein ahmadi, v.n. nguyen, v.d. tran, t.h. truong, "thermal performance assessment of an ejector airconditioning system with parabolic trough collector using r718 as a refrigerant: a case study in algerian desert region," sustainable energy technologies and assessments, vol. 53, 2022, pp. 102513. https://doi.org/10.1016/j.seta.2022.102513. [17] m. ghodbane, b. boumeddane, k. lahrech, "solar thermal energy to drive ejector hvac systems: a numerical study under blida climatic conditions," case studies in thermal engineering, vol. 28, 2021, pp. 101558. https://doi.org/10.1016/j.csite.2021.101558. [18] m. ghodbane, b. boumeddane, a.k. hussein, "performance analysis of a solar-driven ejector air conditioning system under el-oued climatic conditions, algeria," journal of thermal engineering, vol. 7, 2021, pp. 172-189. https://dx.doi.org/10.18186/thermal.847334. [19] m. ghodbane, b. boumeddane, f. hussain, r. zhar, k. lahrech, j. bhatti, b. zhang, h. yassin, l.c. de silva, a. barbón, "evaluation of the design and optical errors for a parabolic trough collector field in an algerian desert region: gassi-touil as a study area," energy reports, vol. 8, 2022, pp. 15326-15337. https://doi.org/10.1016/j.egyr.2022.15024. [20] m. ghodbane, b. boumeddane, a.k. hussein, h.m. ali, d. li, "thermal numerical investigation of a small parabolic trough collector under desert climatic conditions," journal of thermal engineering, vol. 7, 2021, pp. 429-446. https://doi.org/10.18186/thermal.884657. [21] m. ghodbane, b. boumeddane, a.k. hussein, d. li, s. sivasankaran, "optical numerical investigation of a solar power plant of parabolic trough collectors," journal of thermal engineering, vol. 7, 2021, pp. 550-569. https://doi.org/10.18186/thermal.888167. [22] m. ghodbane, b. boumeddane, a. khechekhouche, s. largot, "study of the effect of the position and metal of the receiver tube on the performance of a parabolic trough solar collector," materials today: proceedings, vol. 51, 2022, pp. 2144-2151. https://doi.org/10.1016/j.matpr.2021.12.2497. [23] m. ghodbane, d. benmenine, a. khechekhouche, b. boumeddane, "brief on solar concentrators: differences and applications," instrumentation mesure metrologie, vol. 19, 2020, pp. 371-378. https://dx.doi.org/10.18280/i18282m.190507. [24] m. ghodbane, m. majdak, b. boumeddane, "the efficiency of linear fresnel reflectors in producing superheated steam for power plant drive," e3s web conf., vol. 323, 2021, article 00011. https://doi.org/10.1051/e3sconf/202132300011. [25] m. ghodbane, b. boumeddane, z. said, e. bellos, "a numerical simulation of a linear fresnel solar reflector directed to produce steam for the power plant," journal of cleaner production, vol. 231, 2019, pp. 494-508. https://doi.org/10.1016/j.jclepro.2019.05.1201. [26] m. ghodbane, e. bellos, z. said, b. boumeddane, a. khechekhouche, m. sheikholeslami, z.m. ali, "energy, financial and environmental investigation of a direct steam production power plant driven by linear fresnel solar reflectors," journal of solar energy engineering, vol. 143, apr 2021, article 021008. https://doi.org/10.1115/1.4048158. [27] a. barbón, d. vesperinas, l. bayon, d. garcíamollaghan, m. ghodbane, "numerical simulation of a solar water disinfection system based on a small-scale linear fresnel reflector," rsc advances, vol. 13, 2023, pp. 155-171. https://doi.org/10.1039/d1032ra05596a. https://doi.org/10.1016/j.renene.2020.101154 https://doi.org/10.1016/j.renene.2019.101137 https://doi.org/10.1007/s10973-020-09384-6 https://doi.org/10.1016/j.csite.2016.06.006 https://doi.org/10.1016/j.solmat.2022.111633 https://doi.org/10.1016/j.est.2022.104858 https://doi.org/10.1007/s10973-020-10300-1 https://doi.org/10.1016/j.seta.2021.101715 https://doi.org/10.1016/j.seta.2022.102513 https://doi.org/10.1016/j.csite.2021.101558 https://dx.doi.org/10.18186/thermal.847334 https://doi.org/10.1016/j.egyr.2022.15024 https://doi.org/10.18186/thermal.884657 https://doi.org/10.18186/thermal.888167 https://doi.org/10.1016/j.matpr.2021.12.2497 https://dx.doi.org/10.18280/i18282m.190507 https://doi.org/10.1051/e3sconf/202132300011 https://doi.org/10.1016/j.jclepro.2019.05.1201 https://doi.org/10.1115/1.4048158 https://doi.org/10.1039/d1032ra05596a soulef largot et al. / international journal of energetica (ijeca) vol. 8, n°1, 2023, pp. 24-30 page 30 [28] barbón, m. ghodbane, l. bayón, z. said, "a general algorithm for the optimization of photovoltaic modules layout on irregular rooftop shapes," journal of cleaner production, vol. 365, 2022, p. 132774. https://doi.org/10.1016/j.jclepro.2022.132774. [29] j.a. fernández-rubiera, a. barbón, l. bayón, m. ghodbane, "sawtooth v-trough cavity for low concentration photovoltaic systems based on small-scale linear fresnel reflectors: optimal design, verification and construction," electronics, vol. 12, 2023, p. 2770. https://doi.org/10.3390/electronics12132770. https://doi.org/10.1016/j.jclepro.2022.132774 https://doi.org/10.3390/electronics12132770 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 29-37 ijeca-issn: 2543-3717. december 2017 page 29 a parabolic trough solar collector as a solar system for heating water: a study based on numerical simulation mokhtar ghodbane 1 , boussad boumeddane 1 1 department of mechanical engineering, university of saâd dahlab, blida 1, algeria ghodbanemokhtar39@yahoo.com abstract – this paper is an optical and thermal study of a small model of a parabolic trough solar collector (ctp), which will be used to heat tap water, in the winter, at guemar location, (eloued, algeria). a mathematical model was presented based on the energy balance equation applied to the absorber tube; this model was solved by the finite difference method. a computer program based on matlab was developed to solve the problem. the results show that the thermal efficiency of the concentrator can attend a high value of more than 61%, while the fluid outlet temperature can reach 343 k. keywords: solar thermal, parabolic trough collector, outlet temperature, tap water, numerical analysis. received: 09/10/2017 – accepted: 25/12/2017 i. introduction the oldest and the greatest source of energy in the universe is the sun, where an average of 1367 (w/m²) reached the edge external of the terrestrial atmosphere according to the world radiometric center of davos (switzerland) [1]. the global solar radiation is the sum of both direct and diffuse components [2-16]. algeria has one of the highest solar radiation in africa. the sunshine duration on almost all of the national territory exceeds 2000 hours annually and can reach 3900 hours in the highlands and sahara [17]. this study deals with the exploitation of solar energy to produce hot water using parabolic trough concentrator (ptc) in guemar region, where the table (1) shows the meteorological data of this city. in previous studies, we have studied several models of this system in different regions in algeria, where the results were very encouraging [2-11]. table 1. the meteorological data of the city of guemar. month global radiation (kwh/m²) diffuse radiation (kwh/m²) beam radiation (kwh/m²) monthly average of ambient temperature (°c) monthly average of dew point (°c) monthly average of wind speed (m/s) 1 114 19 211 10,6 4 2,1 2 125 28 184 12,9 3,1 2,5 3 170 48 197 17,8 4,6 3,3 4 207 54 225 21,6 7,1 4 5 234 69 237 26,8 9,6 4,1 6 236 70 228 31,3 11,4 3,6 7 248 66 242 34,7 13,3 3,4 8 219 67 217 33,8 14,6 3,1 9 176 55 187 28,8 15 3 10 144 45 179 23,8 12,7 2,2 11 117 21 200 16,1 7,3 2 12 100 21 187 11,7 5,1 2,3 for the ptc solar concentrator, it gives us a temperature of fluid that can be used both in industrial and domestic applications, with a mediumto high range of [80-160 ° c] [2-6, 9, 11]. according to the size and position of the ptc collector, this system can obtain a steam temperature exceeding 1500 °c, according to mailto:ghodbanemokhtar39@yahoo.com m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 30 studies cited in the scientific literature [3-6, 9, 11, 18]. so, the ptc systems are the most currently used technology by the most powerful solar power plants in the world, we quote in this context that the solar plant at kramer junction in california represents a total installed capacity of 354 mw [19]. this kind of solar field is made up of parallel alignments of long half-cylindrical mirrors, oriented north-south axis that revolved around the latter to follow the path of the sun. the sun's rays are concentrated on a horizontal tube, where circulates a heat transfer fluid. as we said earlier, this study focuses on the conversion of solar energy to thermal energy by using a parabolic trough solar concentrator in a troubled day of the winter (low-temperature weather with some wind). tap water was used as the heat transfer fluid. our aim in this study is to characterize the optical and thermal efficiencies of our ptc model based on the geographic parameters and climatic conditions in guemar location, (el-oued, algeria). figure 1 shows the scheme of the approved water heating system using trnsys 16. figure 1. illustrative diagram of the water heater system. in order to solve to problem, this study will begin with an optical efficiency analysis using soltrace software. in the second step, a mathematical model has been established with matlab to calculate the thermal efficiency, the fluid outlet temperature, the receiver’s surface temperature, the glass temperature and the coefficient of thermal losses. ii. optical simulation the optical modeling was performed using the soltrace; the code is developed by the national renewable energy laboratory (usa) [20]. the optical system of the concentrator is composed of the reflecting surface and absorber tube. the reflecting surface was modeled as a single mirror of parabolic section. table (2) shows the geometric parameters of the ptc concentrator and the optical parameters are shown in table (3). table 2. geometrical parameters of the ptc collector. geometric characteristic value (mm) receiver tube number 1 absorber length (la) 12270 outer diameter of the absorber (da,ext) 22 inner diameter of the absorber (da,int) 20 outer diameter of the glass (dv,ext) 26 inner diameter of the glass (dv,int) 23,5 mirror length (l) 12270 mirror width (l) 1100 the absorbent tube dimensions mentioned in the previous table are the dimensions of a linear fresnel receiver that was previously manufactured by h. chabahi et al., (2011) [21], but the length of the absorbent tube here was different. m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 31 for the optical simulation, it was assumed that the reflection coefficient, the absorptivity, and transmissivity are uniform over the entire reflecting surface. it was considered that the solar tracking is very accurate and therefore the concentrator opening is constantly perpendicular to the rays from the solar disc. table 3. optical parameters of the collector. parameter value optical overall average error (σoptical) 03 mrad mirror reflection coefficient (ρm) 0,92 transmissivity of the glass 0,945 absorption coefficient of the absorber (α) 0,94 the emissivity of the absorber tube (εa) 0,12 there are several models for the simulation of global direct and diffuse solar irradiance, expressed by semiempirical approaches. for the ptc concentrators, the absorbed solar energy depends on the beam radiation (dni) [3-6, 9, 11]. figure 2 reflects the change in the solar radiation during the day of 05 december 2016 according to the semi-empirical model of perrin de brichambaut, where m. ghodbane et al., (2016), had created a numerical simulation based on programming using matlab for the calculation of solar radiation (direct, diffuse and global) [8]. for this model, the different components of the solar radiation vary according to the height of the sun, the angle of incidence, the weather condition and the state of visibility of the atmosphere. any application of solar energy in a given site requires a complete and detailed knowledge of the sunshine of the site. this is possible if the data are available over a sufficient period. however, in the majority of cases, there are no local measurements of solar radiation, and some approximate methods must be used to predict the characteristics of solar irradiation. the total quantity of radiation calculated for a particular location or area was entered as global radiation. the calculation radiation (direct, diffuse and global) was repeated for each entity location or for all locations of the topographic surface and generates sunshine maps for an entire geographical area. 8 9 10 11 12 13 14 15 16 17 0 100 200 300 400 500 600 time (hour] s o la r ra d ia ti o n [ w /m 2 ] global radiation direct radiation diffuser radiation figure 2. solar radiation evaluation in guemar area. virtually, it was in the regions for which we had the least solar radiation measurements that the projects of implantation of the solar energy systems for water pumping, desalination, or the decentralized electric power supply are the most important and the most demanding. direct radiation (dni) is solar radiation reaching the earth's surface directly from the sun. it depends on the thickness of the atmosphere that the solar radiation must cross, as well as the inclination of the rays relative to the ground. the pyrheliometer is the instrument for measuring the intensity of direct radiation. the pyrheliometer must be equipped with a device to direct it permanently towards the sun. through figure 2, it was noticeable that the maximum radiation value is the true solar noon, which can reach 585 (w/m²), despite the bad weather on this day, the amount of solar radiation was considered. figure 3 illustrates the captured solar energy by the collector, as presented in soltrace. we tried to show the importance and effectiveness of parabolic trough collector in the field of solar concentrate. figure 3. schema parabolic trough concentrator as it appears in soltrace. iii. thermal simulation this section treats the thermal analysis and numerical modeling of a ptc concentrator. this modeling was used to predict the change in the outlet temperature of the heat transfer fluid (water) versus the beam radiation. the thermal exchanges are between the heat transfer fluid, the absorber tube and the glass tube. the temperature modeling was based on the energy balances characterized by the differential equations of the three temperatures: tf (for the fluid), tv (for glass tube) and ta (for the absorber tube), these equations will vary depending on m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 32 two parameters, namely the time (t) and the length (x) of the absorber tube. in calculating the energy balances, we have assume that [9, 13]:  the heat transfer fluid is incompressible;  the parabolic shape is symmetrical;  the ambient temperature around the concentrator is uniform;  the shadow effect of the absorber tube on the mirror is negligible;  the solar flux at the absorber is uniformly distributed;  the glass is considered opaque to infrared radiation;  the exchanges by conduction in the absorber and the glass are negligible. iii.1. energy balance for the fluid the energy balance for the heat transfer fluid that circulates in the absorber tube was expressed by the following relationship [2, 5, 7, 10, 11]: x (x,t)t ..q.cρq t (x,t)t ..a.cρ f vffu f a,ff       int (1) the initial conditions and the boundary conditions of equation (1) are [2, 5, 10, 11]: (0)t=(t)t=t)(x,t (t)t=(t)t=t)(0,t ambinitialf,f ambentryf,f (2) qu is the heat flow transmitted to the fluid [w]; it was given by the following relationship [3, 10, 14]: )t(t.ahq faa,fu  int (3) iii.2. energy balance for the absorber tube the energy balance for the absorber was given by the following equation [2, 5, 7, 10, 11]: figure 4. thermal balance on a surface element of the parabolic cylindrical concentrator [3]. (x,t)(x,t)-qq(t)q t (x,t)t ..a.cρ uexitabsorbed a aaa     (4) the initial conditions for the equation (4) are [5, 10, 11]: )((t)=t(x,t)=tt amba,initiala 0 (5) iii.3. energy balance of the glass similarly, the energy balance for the glass was given by [2, 5, 7, 10, 11]: (x,t)(x,t)-qq t (x,t)t ..a.cρ ext v vv v int    (6) the initial condition of equation (6) is [5, 10, 11]: )((t)=t(x,t)=tt ambv,initialv 0 (7) to solve this problem, we chose the finite difference method. a calculation program matlab was established, after the discretization of non-linear equations that allowed us to obtain a set of numerical results. the thermal power emitted by the sun and received by the concentrator is therefore [5, 10, 11, 22]: .dni.ka=q camcmabsorbed .. (8) where kcam is angle of incidence correction factor modified,  is the intercept factor. we can express the optical efficiency ( optη ) of the concentrator [5, 10, 11, 15]: camopt k=η ..α.ρ m  (9) the thermal efficiency ( η ) was calculated as follows [2, m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 33 5, 10, 11, 15]: c ambaal opt adni )t.(t.au ηη    (10) iii.4. the coefficient of thermal losses the coefficient of thermal losses (ul) was expressed as [2, 5, 7, 10, 11]:                                                                                  vva,ext a,a aa ambaamba va,ext a, amba l ε f εd dt εε )t).(ttσ(t hd d f tt c u 1 450 104.0 1 1 int 1 22 1 int 25.0 1 (11) where the factor (f) takes into account the loss ratio resulting from the wind, it can be obtained by the following equation [5, 10, 11]:     27300325.0exp 3.161.1 9.04.0 int   a va a, t h εdf (12) c1 was given by the following empirical expression [5, 10, 11]:   251 6.06.0 int int 2 1 1 5.096.045.1 , a,exta, a, a dd d ε c            (13) the term (hv) is the wind convection coefficient, it can be obtained by the following equation (according mcadams (1954)) [5, 10, 11, 15, 23]: wv wh 8.37.5  (14) iv. results and discussion the ptc concentrators can offer an opportunity to sunny countries such as algeria for investment and construction of solar central. the right choice of the studied site is very important because each site is characterized by its direct illumination, the ambient temperature, the speed of the wind, the latitude, and the elevation compared to the level of the sea, which play a significant role on the profitability of the solar concentrator. these factors were quite apparent in the results obtained where the energy production vary when moving the solar collector in different sites. we selected guemar city to conduct this study, it is located at an altitude of 62 meters with a latitude and longitude of 33°29'24'' n north and 06°47'50'' east respectively. ptc concentrator had headed south. we chose tap water as the working fluid with a flow rate of 0.015 [kg/s]. the absorber was the seat of the thermal conversion (from concentrated solar radiation into high temperature heat sensitive). on wall of the absorber tube, the thermal energy acquired from the sun has propagated by direct contact of the particles without appreciable displacement of the latter. figures 5a and 5b reflect the average intensities contours of heat flux on the absorber surface based on the direct solar radiation (dni). a) dni= 1000 [w/m²] b) dni= 500 [w/m²] figure 5. flux intensity contour at the absorber tube [w/m²]. this assessment can approach the actual values of thermal flow influencing absorbers with a reflectivity of the mirrors equal to 92% and real illumination values. the main objective of the optical characterization have known the concentration of solar power on the surface absorber tube, and the evolution of the maximum value of thermal flow depending on the incidence angle of solar radiation. figures 6a and 6b illustrate the average heat flow distributions. we observe a good distribution of heat flux m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 34 at the surface level of the absorber. we can say that our concentrator has a good overall optical behavior. thus, we can conclude that the average distributions of heat flux provided the software ray tracing issues representative of real flux distributions by the parabolic trough concentrator. a) dni= 1000 [w/m²] b) dni= 500 [w/m²] figure 6. flux intensity distribution at the absorber tube [w/m²]. now we turn to the thermal analysis, the finite difference method was chosen to solve the non-linear equations of thermal balance. a calculation program using matlab was developed after the discretization of the linear equations, which allowed us to obtain a set of numerical results, thus we will be able to know the performance of the concentrator. figure 7 shows the evolution of optical performance versus time during the day of the study, while figure 8 shows the evolution of thermal performance versus time for the same day. 8 9 10 11 12 13 14 15 16 17 0.4 0.45 0.5 0.55 0.6 0.65 time [hour] o p ti c a l e ff ic ie n c y time [hour] figure 7. evolution of optical efficiency. 8 9 10 11 12 13 14 15 16 17 0.4 0.45 0.5 0.55 0.6 0.65 time [hour] t h e rm a l e ff ic ie n c y time [hour] figure 8. thermal efficiency evolution versus the time. it is noted that the thermal performance was equal to 60.61% at 12:00, after this time, the thermal efficiency decreases with the decreasing of solar radiation resources. the receiver must absorb as much concentrated solar flux as possible, and convert it into thermal energy; this heat is transferred to water. the difference in temperature between the two faces (internal and external) of the absorber tube generates the creation of a heat flow. figure 9 represents the variations of the absorber tube temperature, the fluid temperature and the glass temperature, where the wind speed (ww) during the day was equal to 4.5 [m/s] and the water temperature inside the absorbent tube was equal to 9°c. at the beginning of the day (at 08:00am), the temperature of the absorber tube was equal to the ambient temperature (ta = tamb = 292k), after one hour of heating this temperature increases according to the direct solar radiation concentrated to the absorber, it reaches 302 k. it continues to increase where its value becomes stationary. in this case, the absorber is in a state m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 35 of equilibrium, that is to say that all the surfaces of the absorber are at the same temperature, this state of equilibrium was very difficult to establish because of the influence of the wind. the maximum of the ambient temperature was reached between 12:00 and 14:00 hours, when the illumination is important. the absorber tube is heated by concentrated direct solar radiation; this radiant energy absorbed by the absorber was converted into heat energy, which is transferred by convection to the water inside the receiver, which increases its temperature. 8 9 10 11 12 13 14 15 16 17 280 290 300 310 320 330 340 350 360 time [hour] te m p e ra tu re [ k ] t f luide t a bsorber tube t g lass tube the temperature of the water at the absorber tube inlet = 9 ° c. -the wind speed during the day is 4.5 m / s figure 9. evolution of the temperatures (ta, tf and tv). the heat transfer between the absorber tube and the water comes from the macroscopic movement of the water. according to figure 9, it is certain that the absorber tube temperature (ta), the water temperature (tf) and the glass temperature (tv) were directly related to the experimental conditions of weather conditions. the results in figure 9 show the rapid heating of water by solar irradiation during the day. it is noted that the temperature of the absorber (ta) is close to (tf) which it has the maximum value at 14:55, we recorded an absorber temperature equal to 353 (k), and this is a sign of a good thermal insulation and low heat loss between the absorber tube and the surrounding air. the selective surfaces are taking advantage of different wavelengths of incident solar radiation, so the selectivity of the surface will result in a maximum absorption in the solar and infrared spectrum minimum. therefore, the absorber tube has a high absorptivity for visible solar radiation and low emissivity for the long‘s wavelength infrared radiation due to the selective coating of the absorber. this coating can retain the greater part of the incident solar energy on the surface of the absorber and lose very little amount of heat radiation in the wavelength when the absorbent surface becomes hot. the decrease of the absorber tube surface results in an increase in the concentration, therefore the performances are higher. for a test day with a constant volumetric flow, the temperature depends mainly on the qabsorbed (t), which is based on optical parameters, geometric of the concentrator and direct radiation received by the collector. 8 9 10 11 12 13 14 15 16 17 0 50 100 150 200 250 300 350 time [hour] th e p o w e r a b s o rb e d [ w ] figure 10. evolution of the power absorbed. the inside of the absorber absorbs infrared radiation, which undergoes a temperature increase (ta) (greenhouse effect). therefore, the temperature of the outer side is lower and close to the ambient medium subjected mainly to the wind speed, which creates convection to the outer side of the absorber, that is why the information about the meteorological data, including wind speed and ambient temperature are important parameters. the useful power absorbed by the receiver is used to heat the water inside the receiver and increases its temperature to a temperature of 353 k at 14:55. in nature, there are three modes of heat transfer, thermal transfer by conduction, by convection (natural and / or forced) and by radiation. from these three modes of transfer results three types of thermal losses: thermal losses by conduction, by convection and finally by radiation. for the ptc solar concentrator, the heat losses are important because the temperature of the absorber tube is high. moreover, these concentrators require regular maintenance to maintain the optical quality of the mirrors subjected to dust and corrosion of the environment. figure 11 shows the variation in the coefficient of thermal losses as a function of the difference in temperature between the absorber tube and the ambient temperature (ta-tamb). in general, the heat loss coefficients depend on the insulation quality of ptc collector. 0 10 20 30 40 50 60 70 3.250 3.375 3.500 3.625 3.750 3.875 4.000 4.125 4.250 4.375 4.500 4.625 4.750 4.875 5.000 th e rm o l lo s s e s c o ff e c ie n t [w /m ². k ] (t a -t amb ) [°c] equation y = intercept + b1*x^1 + b2*x^2 weight no weighting residual sum of squares 3.23177e-28 adj. r-square 1 value standard error intercept 3.4719 1.28987e-15 b1 0.0281 4.41468e-17 b2 -1e-4 3.02289e-19 figure 11. evaluation of thermal losses coefficient. m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 36 it can be seen from figure 11 that the coefficients of global heat losses (ul) increase slightly with increasing temperature. thus, the coefficient of overall losses varies proportionally with the difference in temperature between the receiver tube and the ambient temperature (ta-tamb), and this is due to the amount of heat absorbed by the absorber. ul increases with the increase of (tatamb), it varies from 3.4 to 5 w / m².k where 0° c < (tatamb) <70 ° c. therefore, we see that the coefficient of losses varies in a slightly slow way; this is due to the range of operating temperature that is not high, and also to the good thermal insulation of the receiver. generally, the climatic conditions vary from season to another (intensity of solar radiation and the ambient temperature) affect the productivity of hot water. through our study on linear concentrator [3-6, 10, 11], we can conclude that the results are very encouraging to exploit and build fields of linear concentrators in all regions of the country (north, south, east and west). v. conclusion this work is a numerical study of a parabolic trough concentrator (ptc) in a volatile day in the winter (low air temperature with some wind). tap water was used as heat transfer fluid. the study was based on the numerical analysis of the energy balance equations of the absorbent tube, the water and the glass envelope surrounding the absorbent tube. according to this numerical solution, we can control the absorber temperature, the fluid outlet temperature and the glass temperature. the thermal efficiency of device exceeds 61%, where the fluid temperature at outlet of the absorber tube is equal to 344 [k]. the results are very encouraging for the development of this type of solar concentrator in the country. references [1] p. bessemoulin and j. oliviéri, "le rayonnement solaire et sa composante ultraviolette," la météorologie, vol. 8, no. 31, 2000, pp. 42-59. [2] m. ghodbane, b. boumeddane, and n. said, "design and experimental study of a solar system for heating water utilizing a linear fresnel reflector," journal of fundamental and applied sciences, vol. 8, no. 3, pp. 804-825. http://dx.doi.org/10.4314/jfas.v8i3.8, 01/09/2016 2016. [3] m. ghodbane, b. boumeddane, and n. said, "a linear fresnel reflector as a solar system for heating water: theoretical and experimental study," case studies in thermal engineering, vol. 8, no. c, pp. 176-186. http://dx.doi.org/10.1016/j.csite.2016.06.006, 2016. [4] m. ghodbane, b. boumeddane, and s. largot, "simulation numérique d’un concentrateur cylindro-parabolique en el oued, algérie," international journal of scientific research & engineering technology (ijset), vol. 3, no. 2, 2015, pp. 68-74. [5] m. ghodbane, b. boumeddane, and s. largot, "etude optique et thermique d’un concentrateur cylindro-parabolique en site d’alger, algérie," in ixth international congress on renewable energy and the environment, djerba, tunisie, 18-20 march 2015. [6] m. ghodbane, b. boumeddane, s. largot, and h. berkane, "modélisation d'un cycle de réfrigération solaire à éjecteur couplée à un concentrateur cylindro-parabolique," in international conférence en clean cooling technologies in the me na regions (ict3_mena'2015) bou smail, w. tipaza, 5-6 october 2015. [7] m. ghodbane and b. boumeddane, "optical modeling and thermal behavior of a parabolic through solar collector in the algerian sahara " amse journals-amse iieta publication2017-series: modelling b, vol. 86, no. 2, 2017, pp. 406-426. [8] m. ghodbane and b. boumeddane, "estimating solar radiation according to semi empirical approach of perrin de brichambaut: application on several areas with different climate in algeria," international journal of energetica, vol. 1, no. 1, 2016, pp. 20-29. [9] m. ghodbane and b. boumeddane, "numerical simulation of a solar-driven ejector refrigeration cycle coupled to a parabolic trough concentrator," international journal of chemical and petroleum sciences, vol. 5, no. 1, 2016, pp. 1-12. [10] m. ghodbane and b. boumeddane, "a numerical analysis of the energy behavior of a parabolic trough concentrator," journal of fundamental and applied sciences, vol. 8, no. 3, 2016, pp. 671-691. [11] m. ghodbane and b. boumeddane, "numerical modeling of a parabolic trough solar collector at bouzaréah, algeria," international journal of chemical and petroleum sciences, vol. 4, no. 2, 2015, pp. 11-25. [12] z. sen, "flat plate collectors," in solar energy fundamentals and modeling techniques: atmosphere, environment, climate change and renewable energy: springer, 2008, pp. 246-249. [13] a. rabl, active solar collectors and their applications. new york oxford, oxford university press, 1985. [14] s. a. kalogirou, solar energy engineering: processes and systems, 1st ed. academic press, 2009. [15] d. y. goswami, f. kreith, and j. f. kreider, "offnormal incidence effects," in principles of solar engineering2nd ed.: taylor & francis, 1999, p. 139. m. ghodbane et al. ijeca-issn: 2543-3717. december 2017 page 37 [16] d. y. goswami and f. kreith, "solar energy resources," in energy conversion, t. f. group, ed.: crc press, 2007, chapter 5, pp. 1-9. [17] m. ghodbane, n. moummi, b. boumeddane, s. largot, and h. berkane, "study and numerical simulation of solar system for air heating," journal of fundamental and applied sciences, vol. 8, no. 1, pp. 41-60. http://dx.doi.org/10.4314/jfas.v8i1.3, 2016. [18] j. r. vaillant, utilisation et promesse de l’énergie solaire. 1978. [19] j. kramer. (2015). kramer junction (californie) : la plus grande centrale solaire thermique du monde. available: http://www.eco-conscient.com/art-53centrale-solaire-thermique-de-kramer-junctioncalifornie.html [20] t. wendelin, a. dobos, and a. lewandowski, "soltrace: a ray-tracing code for complex solar optical systems," technical report october 2013, available: http://www.osti.gov/bridge. [21] h. chabahi, b. boumeddane, and n. said, "dimensionnement et expérimentation d’un concentrateur linéaire a miroirs de fresnel," thesis of a state engineer in mechanical engineering, mechanical departement, saad dahlab university, blida 1, algeria, 2011. [22] s. bonnet, m. alphilippe, and p. stouffs, "conversion thermodynamique de l'énergie solaire dans des installations de faible ou de moyenne puissance: réflexion sur choix du meilleur degré de concentration," in revue d'énergie renouvelable: 11 ème journée internationales de thermique, 2003, pp. 73-80. [23] j. a. duffie and w. a. beckman, solar engineering of thermal processes, 4th ed. wiley, 2013. nomenclatures . v volume flow rate (m 3 /s)  intercept factor aa absorber area (m²) ac collector aperture area (m²). ca specific heat of the absorber (j/kg k). cf specific heat of the fluid (j/kg k). cp thermal capacity (j/kg k). da,ext external diameter of the absorber (m). da,int internal diameter of the absorber (m). dv,ext external diameter of the glass tube (m). dv,int internal diameter of the glass (the transparent envelope) (m). hv coefficient of transfer by convection of the wind (w/m².k). kcam angle of incidence correction factor modified qabsorbed heat absorbed in the absorber tube (w/m²). qexte heat quantity lost to the outside (convection + conduction) between the glass and ambient (w/m²). qint internal heat (convection + conduction) between the glass and ambient (w/m²). qu heat exchanged by convection between the absorber and the fluid (w/m²). se the effective area of a sensor reflector (m²). ww wind velocity (m/s). ta temperature of the absorber (k). tamb ambient temperature (k). tf fluid temperature (k). tv temperature of the glass (k). ul overall coefficient of heat loss (w/m².k). εa emissivity of the absorber tube εv emissivity of the casing transparent glass ρa density of the absorber (kg/m 3 ). ρf fluid density (kg/m 3 ). σ stefan-boltzmann constant (w/m 2 .k 4 ). ieee paper template in a4 international journal of energetica (ijeca) https://www.ijeca.info/index.php/ijeca/index issn: 2543-3717 volume 1. issue 1. 2016 page 12-19 ijeca – issn: 2543-3717. december 2016 modeling and simulation of energy management hybrid sources system composed of solar-pv and battery m. maamir 1 , a.betka 1 , h. aboub 2 1 lgeb laboratory, electrical engineering department, university of biskra, algeria, 2 leb, university of batna email: m.maamir39@ gmail.com abstract— this paper describes the modeling and control of a hybrid source consisting of pv generator (as main source) along with a battery (as an auxiliary source) and a dc-load are connected through power converters and a dc-link. the main objective of this paper is to design a power manager to control effectively the power of the different sources. to test the effectiveness of the different control techniques involved, simulation results are plotted and commented. keywords: hybrid system, energy storage, pv generator, power management, battery, fuzzy logic, batteries. 1. introduction currently, most of the energy demand in the world is met by fossil and nuclear power plants. a small part is drawn from renewable energy technologies such as wind, solar, fuel cell, biomass and geothermal energy [1]. renewable energy sources are considered as alternative energy sources to conventional fossil fuel energy sources due to the environmental pollution and global warming problems. the combination of all different kinds of available renewable energy associated with available energy storage units produces an hybrid energy system (hes) [2]. therefore, in order to supply electric power to fluctuating loads with a hybrid system composed of solar cell and electric energy-storage system is needed to compensate for the gap between the output from the renewable energy sources and the load, in addition to the collaborative load sharing among those energies. to control the power flow among the elements consisting hes a suitable energy management system (ems) must be designed. the ems is usually a central controller that drives all the elements. thus, the complexity in designing an ems increases with the level of hybridization of the hes (the number of elements present in the system). energy management of multi-power sources has already been studied recently, for example, control, robustness, stability, efficiency, and optimization of hybrid sources remain an essential area of research. several researchers have studied different topologies. g. boukettaya [3] studied a dynamic power management strategy of a grid connected hybrid generation system using wind, photovoltaic and flywheel energy storage system in residential applications. r. souad [4] studied the development and the realization of an intelligent power strip for energy consumption management in hybrid wind/photovoltaic systems. m. mohammedi [5], studied passivity based control and fuzzy logic estimation applied to dc hybrid power source using fuel cell and super capacitor. shiyas p.r [6] fuzzy controlled dual input dc/dc converter for solar-pv/wind hybrid energy system. m. y. ayad [7], studied sliding mode control applied to fuel cell, super capacitors and batteries for vehicle hybridizations. in this paper, a control strategy for the energy management of an hybrid renewable energy system is presented. the system is composed of a photovoltaic solar array and batteries which are connected in a common dc-link bus. the dc bus is connected in parallel with resistive charge. dc-dc power converters are introduced to quietly perform the different control strategies proposed. fig.1 is shown a synoptic scheme of the system. the paper focuses on the design of a power supervisor able to decide, at each moment and according to the load power demand, which source has to supply or absorb the energy and eventually define the ratio of using of different sources in the same time [8]. the rest of the paper is organized as follows: in section2; an explicit madiha. maamir et al ijeca – issn: 2543-3717. december 2016 13 modeling of the different sub-systems are given. in section3, both the power management algorithm and the proposed control techniques are properly detailed. in section 4, simulation results conducted with both various load demand. fig1: system architecture 2. system modeling 2.1 pv array model the equivalent circuit of the pv device can be represented as a current source in parallel with diode includes a parallel resistor (rsh) expressing a leakage current, and a series resistor (rs) describing an internal resistance [9] .the model is shown in fig2. fig 2: equivalent circuit of photovoltaic module. since rsh is very high, the mathematical model which relates the output current to the output voltage is given by the following expression [10]: i = icc − i0 [exp v +r p i v th − 1] (1) the adaption of eq. (1) for different levels of solar insolation and temperature can be handled by the following equations. ∆𝑇 = 𝑇 − tref (2) ∆i = α e e ref ∆t + ( e e ref − 1)iccref (3) ∆v = −β∆t − rs ∆i (4) 𝑉 = 𝑉𝑟𝑒𝑓 + ∆v (5) i = iref + ∆i (6) 2.2 battery model: in general a battery device can be viewed as a voltage source 𝐸𝑏𝑎𝑡 in series with an internal resistance 𝑟𝑏𝑎𝑡 as shown in fig 3. [8]. madiha. maamir et al ijeca – issn: 2543-3717. december 2016 14 fig 3: dynamic model of lead-acid battery the terminal voltage 𝑉𝑏𝑎𝑡 is given by: 𝑉𝑏𝑎𝑡 = 𝐸𝑏𝑎𝑡 − 𝑟𝑏𝑎𝑡 . 𝑖𝑏𝑎𝑡 (7) as the internal voltage 𝐸𝑏𝑎𝑡 is assumed to be a function only of the state of charge (soc) [11] [12], or the depth of discharge (𝐷𝑂𝐷𝑏𝑎𝑡 ). eq. (8) describes the used open voltage: 𝐸𝑏𝑎𝑡 = 𝑛(2.15 − 𝐷𝑂𝐷𝑏𝑎𝑡 . 2.15 − 2.00 (8) in addition, socbat and 𝐷𝑂𝐷𝑏𝑎𝑡 are respectively estimated by [11]: 𝑆𝑂𝐶𝑏𝑎𝑡 = 𝐶𝑎𝑐𝑡𝑢𝑒𝑙𝑙𝑒 𝐶𝑡𝑜𝑡𝑎𝑙𝑒 = 𝑆𝑂𝐶𝑏 𝑖𝑛𝑡 + 100 𝐶𝑁 𝑖(𝑡)𝑑𝑡 (9) 𝐷𝑂𝐷𝑏𝑎𝑡 = 1 − 𝑆𝑂𝐶𝑏𝑎𝑡 (10) 2.3 average state-space models of the static converters dc/dc boost converter model: the dc-dc boost is modeled using an average state-space approach, given in eq (11) [12] to check the effectiveness of the control techniques via continuous models: 𝑑𝑖𝐿 𝑑𝑡 𝑑𝑣𝑐 𝑑𝑡 = 0 − 1−𝛼𝑝𝑣 𝐿𝑝𝑣 1−𝛼𝑝𝑣 𝐶 − 1 𝑅𝐶 𝑖𝐿𝑝𝑣 𝑉𝑐 (11) in order to maximize the energy extracted from the pv array, a fuzzy logic based mppt strategy has been applied because it has the advantages of robustness, and minimal requirement for accurate mathematical model [13]. bidirectional dc/dc converter model the bidirectional dc/dc converter is a current reversible dc/dc converter. it can work as a boost converter when the current (of the bidirectional dc/dc converter inductance) flows from the super capacitor (battery) to the dc bus. it works as buck converter when the current flows on the opposite direction [14]. thus, to achieve energy transfer in two directions, the buck and boost converters were associated as shown in fig 4. madiha. maamir et al ijeca – issn: 2543-3717. december 2016 15 fig 4: structure of the bidirectional dc-dc converter the average model of the converter in both power direction flow can be written as: lbat d ibat dt = vbat − 1 − αbat vdc (12) 3. controller for hybrid systems in the present work, three operating modes are distinguished and smoothly permuted through the presented power management system. throughout the simulation the photovoltaic generator operates on mppt: mode1: the main source is the pv array and the battery, supply energy to the load. mode2: power load is below to the maximum power point (mppt), then the battery is charged. mode3: this mode starts when the power of the pv array demand equal to the power demand, where the photovoltaic array supplies only the load demand. to permit a global flow of the different source’s energy, the dc bus must be kept constant. a main voltage loop with a lyapounov controller generates the total current reference that should be taken from the dc-link bus. in the ems depicted in (fig 5), a low-pass filter is introduced, which extracts the low frequency content of the reference sent to the battery, and through the chosen constant time, the battery contributes mainly in steady state. the rules are summarized in eq. (13) for battery. fig 5: energy management system 𝐼𝑏𝑎𝑡𝑟𝑒𝑓 0, 𝑖𝑓 𝐼𝑑𝑐𝑟𝑒𝑓 < 0 𝑎𝑛𝑑𝑆𝑂𝐶𝑏𝑎𝑡 > 95%, 𝐼𝑑𝑐𝑟𝑒𝑓 > 0 𝑎𝑛𝑑𝑆𝑂𝐶𝑏𝑎𝑡 < 25% 𝐼𝑏𝑎𝑡 𝑟𝑒𝑓 , 𝑖𝑓 𝐼𝑑𝑐𝑟𝑒𝑓 <0 𝑎𝑛𝑑 𝑆𝑂𝐶𝑏𝑎𝑡 <95%, 𝐼𝑑𝑐𝑟𝑒𝑓 >0 𝑎𝑛𝑑 𝑆𝑂𝐶𝑏𝑎𝑡 >25 %, (13) battery current control loop the design of the bidirectional dc-dc converter of the battery or sc is based on the direct lyapunov theory. the controller adjusts the duty cycle by comparing the reference and the actual battery currents to operate the converter in boost and buck mode [15]. let the battery current error defined as : e = ibat − ibat ref (14) one can define a quadratic positive defined function related to the tracking error [16]: v = 1 2 e2 (15) the gradient function of the loss function v is derived as: v = e e (16) to ensure the error convergence to zero, let’s choose the desired gradient function of the form: v = −ke2 (17) by a proper adjustment of the constant k, the system dynamics are improved, and the battery current tracks its reference in a finite time. by equation (16) and (17), the closed loop error dynamic is derived as a stable first order equation: e = −ke (18) the duty cycle is computed as: 𝛼𝑏𝑎𝑡 = 1 − 𝑉𝑒 𝑉𝑑𝑐 (19) madiha. maamir et al ijeca – issn: 2543-3717. december 2016 16 pv current control loop the pv panels are equipped with the maximum power point tracking controller to track the mpp and extract maximum possible power from the panel [17]. in this study, fuzzy logic has been applied for tracking the mpp of pv systems because it has the advantages of robustness, design simplicity, and minimal requirement for accurate mathematical model [18]. the fuzzy controller consists of three blocks: the fuzzification of input variables which is performed in the first block, it allows the passage from the real domain to fuzzy domain. the second block is devoted to inference rules, while the last block is the defuzzification for returning to the real domain. this last operation uses the center of mass to determine the value of the output. fig 6 shows the basic structure of the used mppt fuzzy controller [18]. fig 6: block diagram of the fuzzy logic controller 4. simulation results the whole system has been implemented in the malab-simulink using the system parameters shown in table1. table 1: sources parameters fig 7 : load demand and battery power 0 5 10 15 20 25 -500 0 500 1000 1500 t(s) p o w e r s( w ) pch ppv pbat photovoltaic generator vop=68.8v iop=14.a icc=15.3a voc=86.v battery vbat=48v cn=200h n=24 cellule madiha. maamir et al ijeca – issn: 2543-3717. december 2016 17 fig 8 : load current fig 9 : battery current fig 10: state of charge fig 11: dc-link voltage fig 12: pvg boost and battery bidirectional converters controls 0 5 10 15 20 25 0 2 4 6 8 10 12 14 t(s) il o a d ( a ) 0 5 10 15 20 25 -8 -6 -4 -2 0 2 4 6 8 t(s) ib a t( a ) 0 5 10 15 20 25 0.65 0.7 0.75 0.8 0.85 0.9 t(s) so c b a t 0 5 10 15 20 25 0 20 40 60 80 100 t(s) v d c (v ) 0 0.005 0.01 0 50 100 vdcref vdc 0 5 10 15 20 25 0 0.2 0.4 0.6 0.8 t(s) d b a t , d p v dpv dbat madiha. maamir et al ijeca – issn: 2543-3717. december 2016 18 fig 13: refrences currents battery fig 7 shows the powers transfer of the system, the pv generator and the battery provide the power to the load (0 s 9 s).to 9s at 17s, the pv generator suplyies energy to the load and charge the battery, when the power load equals the power of the pv generator the battery current becomes zero (17s-25s). in fig 10, increase battery state of charge correspond to a charge, and the decrease to a discharge. the dc bus voltage tracks well the reference without overshoot and no state error (with a response time of 0.00065s) (fig 11). fig 12 presents the network boost controller, the the battery bidirectional converter controller. 𝛼𝑝𝑣 and 𝛼𝑏𝑎𝑡 are in the interval [0.5]. fig 13 shows the battery current ibat. it tracks well the reference, this current becomes positive to compensate for an increase in the load power demand that oppears between time (t= 0s and t=9s) resulting in discharge of the battery, negative when the battery is charged (for example between t=9s and t=17s) and takes zero values if the battery is completely charged or discharged. 5. conclusion energy management of multi-power sources has been proposed as a solution for a hybrid energy system that uses renewable energy from solar cells and a storage with batteries, when the pv array is used as a source of power supply to stand alone loads, it is necessary to use the mppt to get the maximum power point from the pv array and implemented with matlab/simulink for simulation. the energy management system (ems) is operated in suitable modes according to the conditions of pv panel and battery.the problem of the dc bus voltage control is solved by using a direct lyapunov theory. eferences [01] phatiphat thounthong, viboon chunkag, panarit sethakul, suwat sikkabutc, serge pierfederici, bernard davat , “ energy management of fuel cell/solar cell/supercapacitor hybrid power source”, journal of power sources 196, elsivier, 2011, pp. 313–324. [02] gupta, a., r. p. saini, and m. p. sharma, “hybrid energy system sizing incorporating battery storage: an analysis via simulation calculation",third international conference on power systems, 2009. [03] ghadaboukettaya, lot fi krichen, “a dynamic power management strategy of a grid connected hybrid generation system using wind, photovoltaic and flywheel energy storage system in residential applications”, journal homepage, contents lists available at science direct, 2014, pp 148 – 159. [04] rafa souad, khenfri fouad, diaf said,” development and realization of an intelligent power strip for energy consumption management in hybrid wind/photovoltaic systems”, the mediterranean green energy forum 2013, mgef-13, science direct. [05] m. mohammedi, m. becherif, m.y. ayad, o. kraa, a. aboubou and m. bahri,” passivity based control and fuzzy logic estimation applied to dc hybrid power source using fuel cell and supercapacitor”, proceedings of the 3rd international conference on systems and control, algiers, algeria, october 2931, 2013. [06] [shiyas p.r, kumaravel s. and dr. asho s, “fuzzy controlled dual input dc/dc converter for solarpv/wind hybrid energy system”, 2012 ieee students. [07] m. y. ayad, m. becherif, a. henni, m. wack and a. aboubou, “sliding mode control applied to fuel cell, supercapacitors and batteries for vehicle hybridizations”,ieee international energy conference, 2010. 0 5 10 15 20 25 -6 -4 -2 0 2 4 6 8 t(s) ib a t, i b a tr e f 12.005 12.01 -5.212 -5.21 -5.208 ibat ibatref madiha. maamir et al ijeca – issn: 2543-3717. december 2016 19 [08] h. alloui, m. becherif and k. marouani, “modelling and frequency separation energy management of fuel cell-battery hybrid sources system for hybrid electric vehicle”, 21st mediterranean conference on control & automation (med) platanias-chania, crete, greece, june 25-28, 2013. [09] ionel laurentiu albotea nu, sergiu ivanov and gheorghe manolea, “modelling and simulation of a stand-alone photovoltaic system”, 8th wseas international conference on power systems (ps 2008), santander, cantabria, spain, september 23-25, 2008. [010] angkee sripakagorna, nartnarong lim wuthigraijiratb, “experimental assessment of fuel cell/supercapacitor hybrid system for scooters” international journal of hydrogen energy 34, elsevier, pp. 6036–6044, 2009. [011] lagrioui, h.mahmoudi “nonlinear adaptive backstepping control of permanent magnet synchronous motor (pmsm)” jatit-vol 29. no. 2 – 2011. [012] premananda pany, r. k. singh, r.k.tripathi, “performance analysis of fuel cell and battery fed pmsm drive for electric vehicle application”, 2nd international conference on power, control and embedded systems, 2012. [013] h. afghoul and f. krim, “intelligent energy management in a photovoltaic installation using neuro-fuzzy technique”, 2nd ieee energycon conference & exhibition, 2012. [014] mustapha amine rahmani ,mazen alamir anddavidgualino,”control strategy for an off grid hybrid stirling engine/super capacitor power generation system “american control conference (acc) washington, dc, usa, june 17-19, 2013. [015] premananda pany, r. k. singh, r.k.tripathi, “performance analysis of fuel cell and battery fed pmsm drive for electric vehicle application”, 2nd international conference on power, control and embedded systems, 2012. [016] drid. s, a. makouf, nait-said m.s, and tadjine. m, “the doubly fed induction generator robust vector control based on lyapunov method”, transactions on systems, signals & devices vol. 4, no. 2, pp. 1-13, 1861-5252/ c 2009 tssd. [017] muhammad sheraz, mohammed a. abido, “an efficient mppt controller using differential evolution and neural network”, international conference on power and energy (pecon), 2-5 december 2012. [018] h. afghoul and f. krim, “intelligent energy management in a photovoltaic installation using neuro-fuzzy technique”, 2nd ieee energycon conference & exhibition, 2012 international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 56-59 ijeca-issn: 2543-3717. june 2019 page 56 simulation and optimization of ch3nh3pbi3 based inverted planar heterojunction solar cell using scaps software abdelkader hima 1* , ahmed khalil le khouimes 1 , abdallah rezzoug 1 , mouslem ben yahkem 1 , abderrahmane khechekhouche 2 , imad kemerchou 3 1 faculty of technology, univ. el-oued, el oued 39000, algeria 2 uderza unit, university of el oued, 39000 el oued, algeria 3 laboratory of analysis and control of energy systems and networks, university of laghouat, algeria email*: himaaek@yahoo.fr abstract – in order to improve the efficiency of a planar heterojunction organic-inorganic solar cell, this work is carried out using scaps software. the studied inverted p-i-n structure is pedot:pss/ ch3nh3pbi3/ pcbm where pedot:pss is the hole transporting layer (htl), ch3nh3pbi3 is the perovskite absorber layer (pvk) and pcbm is the electron transporting layer (etl). the simulated structure is sandwiched between sno2: fto and al which are the transparent and aluminum electrodes respectively. simulation efforts are focused on thickness and density of states (donor’s and acceptors) effect on solar cell efficiency. found results improved the power conversion efficiency (pce) from 11.73% up to 19.58 %. keywords: perovskite, ch3nh3pbi3, scaps, power conversion efficiency, layer thickness received: 15/05/2019 – accepted: 27/06/2019 i. introduction from 2009 up to 2016, perovskite based solar cell efficiency stepped from 3.8 % to 22.1% [1-3]. this exponential development of perovskite based solar cell efficiency encouraged researchers to use deferent processing methods to enhance it. due to experiment high costs, a simulation effort is a good way to calculate the better parameters prior to do experiments [4-6]. in this work we investigated effect of different layer thickness and density of states on power conversion efficiency of a p-i-n inverted planar heterojunction solar cell using the organic/inorganic perovskite material ch3nh3pbi3 as absorber layer. ii. device simulation parameters figure 1 shows deferent layer deposition of the simulated p-i-n inverted planar heterojunction ch3nh3pbi3 based solar sell. we can see in figure 1 the sno2: fto/ pedot: pss/ ch3nh3pbi3 / pcbm where the etm layer is the pcbm and the htm layer is the pedot:pss. in table 1 is presented initial simulation electrical parameters that were carefully selected from practical and theoretical references [7-17]. firstly, layer thickness is investigated to carry out the best thickness giving higher pce. secondly, density of states is investigated to find out better values that yeld high pce. figure 1. planar heterojunction architecture of the studied solar cell. abder image placée abdelkader hima et al ijeca-issn: 2543-3717. june 2019 page 57 iii. results and discussion in simulation process, the thickness of each layer was fixed in the initial values presented in table 1, then we changed the htl thickness from 0.05 µm to 0.08 µm after that the pvk thickness is changed from 0.3 µm to 0.9 µm and in the last step the etl thickness is modified from 0.3 to 0.6 µm. in each step we fix the thickness value that gives better pce and use it in the next step. table 1. simulation parameters figure 2 presents layer thickness effect on pce for every layer. it is found that the maximal value for pce is 10.85 % which corresponds on 0.05 µm, 0.3 µm and 0.3 µm layer thickness for htl, pvk and etl respectively. figure 2. effect of a) htl, b) pvk and c) etl layer thickness on pce the simulation results for initial and optimized results are presented in table 2. table 2. simulation results for initial and optimized values voc (v) jcs(ma/cm2) ff(%) pce(%) init val 1.4 18.4 44.81 11.73 opt val 1.5 17.7 75.9 19.57 in the figure 3 is illustrated the effect of na of the htl and pvk layer and nd of the etl layer on pce. it is clear from curves of figure 3 that best values that gives a pce of 19.57 % are na=5.10 16 cm -3 , na=5.10 16 cm -3 and nd = 5.10 16 cm -3 for htl, pvk and etl respectively. layer property pedot/pss ch3nh3pbi3 pcbm thickness (μm) 0.080 0.8 0.5 band gap (ev) 2.2 1.55 2.100 electron affinity (ev) 2.9 3.75 3.9 dielectric affinity 3.000 6.500 3.900 cb effective density of states (cm-3) 2.200e+15 2.200e+15 2.200e+19 vb effective density of states (cm-3) 1.800e+18 2.200e+17 2.200e+19 electron thermal velocity (cm/s) 1.00e+7 1.00e+7 1.00e+7 hole thermal velocity (cm/s) 1.00e+7 1.00e+7 1.00e+7 electron mobility (cm2 / v.s.) 0.01 2.0 0.001 hole mobility (cm2/ v.s.) 0.0002 2.0 0.002 donor density nd (cm-3) 1.000e+13 1.000e+13 1.000e+16 acceptor density na (cm-3) 1.000e+16 1.000e+16 1.000e+13 defect nt (cm-3) 1.000e+15 1.000e+15 1.000e+15 p c e ( % ) figure 2 a. htl layer thickness (µm) a) p c e ( % ) figure 2 b. pvk layer thickness (µm) b) p c e ( % ) figure 2 c. etl layer thickness (µm) c) abdelkader hima et al ijeca-issn: 2543-3717. june 2019 page 58 figure 3.a figure 3.b figure 3.c figure 3. effect of acceptor density of a) htl, b) pvk and donor density of c) etl on pce. iv. conclusion in this paper it is found that layer thickness and density of states of a p-i-n perovskite based solar cell have an important effect on pce. simulations done using scaps software have optimized the pce of the studied structure to 19.57 % with the layer thickness values of 0.05 µm, 0.3 µm and 0.3 µm for htl, pvk and etl respectively, and the values of na=5.10 16 cm -3 , na=5.10 16 cm -3 and nd = 5.10 16 cm -3 for htl, pvk and etl respectively. references [1] a. kojima, k. teshima, y. shirai, t. miyasaka, organometal halide perovskites as visible-light sensitizers for photovoltaic cells. journal of the american chemical society, 2009. 131(17) pp. 6050-6051. [2] t. oku, a. takeda, a. nagata, h. kidowaki, k. kumada, k. fujimoto, a. suzuki, t. akiyama, y. yamasaki, e. ōsawa, microstructures and photovoltaic properties of c60 based solar cells with copper oxides, cuins2, phthalocyanines, porphyrin, pvk, nanodiamond, germanium and exciton diffusion blocking layers. materials technology, 2013. 28(1-2) pp. 21-39. [3] nrel chart 2018. 2018. [4] a. hima, a. khechekhouche, i. kemerchou, n. lakhdar, b. benhaoua, f. rogti, i. telli a. saadoun, gpvdm simulation of layer thickness effect on power conversion efficiency of ch3nh3pbi3 based planar heterojunction solar cell, international journal of enerjetica, 2018. 3(1) pp. 37-41. [5] a. hima, n. lakhdar, a. saadoune, effect of electron transporting layer on power conversion efficiency of perovskite-based solar cell: comparative study, journal of nanoelectronic physics, 2019. 11(1) (2019) pp. 01026(3). [6] a. hima, n. lakhdar, b. benhaoua, a. saadoune, i. kemerchou, f. rogti, an optimized perovskite solar cell designs for high conversion efficiency, superlattices and microstructures, 2019. 139 pp. 240-246. [7] p. umari, e. mosconi, f. de angelis, relativistic gw calculations on ch 3 nh 3 pbi 3 and ch 3 nh 3 sni 3 perovskites for solar cell applications. scientific reports, 2014. 4 pp. 4467. [8] q. y. chen, y.h., p. r. huang, t. ma, c. cao, y. he, electronegativity explanation on the efficiency-enhancing mechanism of the hybrid inorganic-organic perovskite abx3 from firstprinciples study. chin. phys. b, 2016. 25(2) pp. 27104-027104. abdelkader hima et al ijeca-issn: 2543-3717. june 2019 page 59 [9] n. k. noel, s.d. stranks, a. abate, c. wehrenfennig, s. guarnera, a. a. haghighirad, a. sadhanala, g. e. eperon, s. k. pathak, m.b. johnston, a. petrozza, lead-free organic– inorganic tin halide perovskites for photovoltaic applications. energy & environmental science, 2014. 7(9) pp. 3061-3068. [10] f.hao, c. c. stoumpos, d. h. cao, r. p. chang, m. g. kanatzidis, lead-free solid-state organic– inorganic halide perovskite solar cells. nature photonics, 2014. 8(6) pp. 489. [11] t. minemoto, m. murata, theoretical analysis on effect of band offsets in perovskite solar cells. solar energy materials and solar cells, 2015. 133 pp. 8-14. [12] k.w.kemp, a.j. labelle, s.m. thon, a.h. ip, i.j. kramer, s. hoogland, e.h. sargent, interface recombination in depleted heterojunction photovoltaics based on colloidal quantum dots. advanced energy materials, 2013. 3(7) pp. 917-922. [13] t. minemoto, m. murata, device modeling of perovskite solar cells based on structural similarity with thin film inorganic semiconductor solar cells. journal of applied physics, 2014. 116(5) pp. 054505. [14] t. minemoto, m. murata, impact of work function of back contact of perovskite solar cells without hole transport material analyzed by device simulation. current applied physics, 2014. 14(11) pp. 1428-1433. [15] f. liu, j. zhu, j. wei, y. li, m. lv, s. yang, b. zhang, j. yao, s. dai, numerical simulation: toward the design of high-efficiency planar perovskite solar cells. applied physics letters, 2014. 104(25) pp. 253508. [16] h. j. du, w. c. wang, j. z. zhu, device simulation of lead-free ch3nh3sni3 perovskite solar cells with high efficiency. chin. phys. b, 2016. 25(10) pp. 108802-108802. [17] j.m. ball, s.d. stranks, m.t. hörantner, s. hüttner, w. zhang, e.j. crossland, i. ramirez, m. riede, m.b. johnston, r.h. friend, h.j. snaith, optical properties and limiting photocurrent of thin-film perovskite solar cells. energy & environmental science, 2015. 8(2) pp. 602-609. i. introduction ii. device simulation parameters iii. results and discussion iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue. 1. 2018 page 37-41 ijeca-issn: 2543-3717. june 2018 page 37 gpvdm simulation of layer thickness effect on power conversion efficiency of ch3nh3pbi3 based planar heterojunction solar cell a. hima 1 , a. khechekhouche 2 , i. kemerchou 3 , n. lakhdar 1 , b. benhaoua 2 , f. rogti 3 , i. telli 4 , a. saadoun 5 1 faculty of technology, univ. el-oued, el oued 39000, algeria 2 renewable energy research unite in arid zones, el-oued university, algeria 3 laboratory of analysis and control of energy systems and networks, faculty of technology university of laghouate, algeria 4 faculty of technology, university of biskra, algeria 5 faculty of technology, university of sidi belabbes, algeria himaaek@yahoo.fr abstract – perovskite-based solar cell technologies have been a very attractive area of research in recent years. organic-inorganic perovskite materials are in an increased evolution in power conversion efficiency. inorganic materials have been tested at the laboratory level but their power conversion efficiency is still limited. in this paper, we used the gpvdm software to study the effect of some parameters on power conversion efficiency in a planar heterojunction solar cell based on ch3nh3pbi3 as an absorbing layer. the modifications were made by considering layers of perovskite without defects. the results show that the efficiency of the power conversion can be improved by adjusting layer thickness; in our case power conversion efficiency was increased from 9.96 % to 12.9 %. keywords: perovskite, mapbi3, pce, gpvdm software, layer thickness received: 02/06/2018 – accepted: 25/06/2018 i. introduction the very peculiar structure of perovskites is at the origin of many researches in various fields of physics and their applications. it was discovered in 1940 that synthetic ceramics of perovskite structure such as barium titanate (batio3) had remarkable piezoelectric properties, that is to say that they were electrically polarized easily under the action of mechanical stresses. . perovskite-type single crystals have been more recently manufactured with even more interesting piezoelectric properties. the research in laboratories on hybrid organicinorganic perovskites has become very intensive. this new technology of perovskite solar cells has seen a rapid progression and each time new percentage of power conversion efficiency that appear. to see the surprising progression of this area reminds that in 2009 a study was made on a cell based on ch3nh3pbbr3 with a high photovoltage of 0.96 v and the value of the efficiency was 3.8% [1] . after two years in 2011, a perovskite cell of size 2-3 nm (ch3nh3pbi3) nanocrystal gave a solarelectric conversion efficiency of 6.54% [2]. during the year 2013, energy conversion efficiencies reached an astounding 16.2% [3]. in the same year, an optimization of the tio2 layer treatment conditions, yields a pce of 19.3% [4, 6]. almost five years of research, it became between 22.1 and 22.6 % [7] different parameters can increase pce in perovskite based solar cells; one of them is layer thickness of different layers. in the present paper we used gpvdm which is a powerful software simulation for photovoltaics, where we investigated effect of different layer thickness on power conversion efficiency of a planar heterojunction solar cell using ch3nh3pbi3 as absorber layer. ii. device simulation parameters general-purpose photovoltaic device model (gpvdm) is free general purpose software for solar cell simulation based on solving poisson equation (1) and the bipolar drift diffusion equations (2,3) and the carrier continuity equations (4,5) in 1d and time domain.  pnq dx d dx d r    .. 0 (1) x n qd x e nqj n c cn        (2) x p qd x e pqj p v hp        (3)            t n grq x j n n (4) a. hima et al. ijeca-issn: 2543-3717. june 2018 page 38            t p grq x j p p (5) more detail on above equation resolving and device modeling can be found in more detail in [8-11]. gpvdm software graphical interface is shown in figure 1. figure 1. gpvdm home window. in figure 2 is shown the planar heterojunction architecture of a ch3nh3pbi3 based solar sell. the layer configuration adopted in this simulation is glass/tco/etm/ch3nh3pbi3/htm/silver where etm layer is the tio2 and the htm layer is the spiroometad. in table 1 is shown initial parameters that were carefully picked from practical and theoretical references [12-21]. perovskite electrical and optical parameters are set from [16] and from gpvdm software database based on [22]. glass layer and silver layer thickness are taken 6×10 -8 m and 2×10 -7 m respectively. our simulation is based on study of effects of different layer thickness on power conversion efficiency. initial layer thickness given in table 1 yields the j-v characteristic curve shown in figure 3, in which power conversion efficiency pce is 9.96 %, fill factor is 75.86 %, open-circuit voltage voc is 0.47 v and shortcircuit density of current is -277 a/m 2 . figure 2. planar heterojunction architecture of the studied solar cell table 1. simulation parameters parameters fto tio2 ch3nh3pbi3 spiro-ometad layer thickness (m) 1e-7 (variable) 2.5e-8(variable) 1e-7(variable) 1e-7(variable) relative permittivity r 3 9 3 3 band gap energy (ev) 0 3.2 2.1 3.17 electron affinity (ev) 4.7 4.26 3.7 2.05 electron mobility (m 2 /v.s) 6.86e-07 20e-4 6.86e-07 2e-08 hole mobility (m 2 /v.s) 3.75e-02 10e-4 3.75e-02 2e-08 donor concentration (m -3 ) 5e26 1e22 5e26 0 acceptor concentration (m -3 ) 5e26 0 5e26 2e25 a. hima et al. ijeca-issn: 2543-3717. june 2018 page 39 figure 3. j-v characteristics for initial layer values iii. results and discussion optimization method used in our simulation is to fix all parameters and modify one by one until we have the parameters that gives maximal pce. in figure 4 is presented the curve of effect of perovskite layer thickness on pce. figure 4. effect of ch3nh3pbi3 layer thickness on pce from figure 4 we can note that a perovskite layer thickness of 2×10 -7 m gives the maximal value of pce which is 12.83 %, with a fill factor of 74.79 %, an opencircuit voltage of 0.47 v and a short-circuit density of current of -370 a/m 2 . we fix the ch3nh3pbi3 layer thickness on 2×10 -7 m and we change the fto layer thickness to obtain curve in figure 5. figure 5. effect of fto layer thickness on pce from figure 5 we obtained a maximal value of pce which is 12.90 % corresponding on fto layer thickness of 4×10 -8 m, with a fill factor of 74.79 %, an open-circuit voltage of 0.47 v and a short-circuit density of current of -372 a/m 2 . by setting fto layer thickness to 4×10 -8 m and changing the spiro-ometad layer thickness we obtained curve in figure 6. figure 6. effect of spiro-ometad layer thickness on pce in figure 6 we can note that the maximal pce is 12.90 % in the spiro-ometad layer thickness of 10 -7 m with a fill factor of 74.79 %, an open-circuit voltage of 0.47 v and a short-circuit density of current of -372 a/m 2 when spiro-ometad layer thickness is set to 10 -7 m and changing of tio2 layer thickness we obtained curve in figure 7. figure 7. effect of tio2 layer thickness on pce curve of figure 7 shows that maximal pce of 12.9 % is obtained in tio2 layer thickness of 2.5×10 -8 m, where fill factor is 74.79 %, open-circuit voltage is 0.47 v and short-circuit density of current is -372 a/m 2 . in figure 4 to figure 7 is presented different layer thickness effect on pce for a ch3nh3pbi3 based planar heterojunction solar cell where we saw that efficiency increased from 9.96 % in initial parameters to 12.9 % with optimized parameters. a. hima et al. ijeca-issn: 2543-3717. june 2018 page 40 figure 8. j-v characteristics for optimized layer values in figure 8 above we can see j-v characteristic of the studied solar cell with optimized parameters. iv. conclusion perovskite power conversion efficiency was analyzed using the gpvdm solar cell software simulation. results indicate that a good choice of layer thickness of different materials used in the solar cell increases considerably the pce ratio. from simulation results is found that an improvement of 2.94 % is made by setting layer thickness of fto to 4×10 -8 m, of tio2 to 2.5×10 -8 m, of perovskite to 2×10 -7 m and of spiro-ometad to 10 -7 m. further pce enhancements can be done by changing layer structure and materials. v. nomenclature 0 is the permittivity of free space r is the relative permittivity  is the voltage profile q is the elementary charge on an electron n is the free electron concentration p is the free hole concentration jn is the electron current flux density jp is the hole flux density µc is the electron mobility µh is the hole mobility ec is the free electron mobility edge ev is the free hole mobility edge dn is the electron diffusion coefficient dp is the hole diffusion coefficient rn is the net recombination rate for electrons rp is the net recombination rate for holes g is the free carrier generation rate references [1] akihiro kojima, kenjiro teshima, yasuo shirai§ and tsutomu miyasaka, organometal halide perovskites as visible-light sensitizers for photovoltaic cells, journal of the american chemical society, vol. 131, no. 17, 2009, pp. 6050-6051. [2] j.-h. im, c.-r. lee, j.-w. lee, s.-w. park, and n.-g. park, 6.5% efficient perovskite quantum-dot-sensitized solar cell, nanoscale, vol. 3, no. 10, 2011; pp. 4088 4093. [3] m. a. green, a. ho-baillie, and h. j. snaith, the emergence of perovskite solar cells, nature photonics, vol. 8, no. 7, 2014, pp. 506–514. [4] b. conings, l. baeten, t. jacobs, r. dera, j. dhaen, j. manca, and h.g. boyen, an easy-to-fabricate lowtemperature tio2 electron collection layer for high efficiency planar heterojunction perovskite solar cells, apl materials, vol. 2, no. 8, 2014, pp. 081505. [5] r. service, perovskite solar cells keep on surging. science (new york, ny), vol. 344, no. 6183, 2014, pp 458. [6] m. peplow, the perovskite revolution [news], spectrum, ieee, vol. 51, no. 7, 2014, pp. 16–17. [7] nrel chart 2018, 2018. [8] roderick c. i. mackenzie, thomas kirchartz, george f. a. dibb, and jenny nelson, modeling nongeminate recombination in p3ht:pcbm solar cells, j. phys. chem. c, vol. 115, no. 19, 2011, pp 9806–9813. [9] r. hanfland, m.a. fischer, w. brütting, u. würfel, r.c.i. mackenzie, the physical meaning of charge extraction by linearly increasing voltage transients from organic solar cells, appl. phys. lett., vol. 103, no. 6, 2013, pp 063904. [10] f. deschler, d. riedel, b. ecker, e. von hauff, e. da como, r.c.i. mackenzie, increasing organic solar cell efficiency with polymer interlayers, phys. chem. chem. phys., vol. 15, no. 3, 2012, pp 764-769. [11] r.c.i. mackenzie, c.g. shuttle, m.l. chabinyc, j. nelson, extracting microscopic device parameters from transient photocurrent measurements of p3ht:pcbm solar cells, adv. energy mater., vol. 2, no. 6, 2012, pp 662-669. [12] umari, pp., e. mosconi, and f. de angelis, relativistic gw calculations on ch3nh3pbi3 and ch3nh3sni3 perovskites for solar cell applications, scientific reports, vol. 4, 2014, pp. 4467. [13] qing-yuan chen, y.h., peng-ru huang, tai ma, chao cao, yao he, electronegativity explanation on the efficiency-enhancing mechanism of the hybrid inorganic-organic perovskite abx3 from first-principles study, chin. phys. b, vol. 25, no. 2, 2015, pp. 27104027104. [14] noel, n.k., et al., lead-free organic–inorganic tin halide perovskites for photovoltaic applications, energy & environmental science, vol. 7, no. 9, 2014, pp. 30613068. [15] hao, f., et al., lead-free solid-state organic–inorganic halide perovskite solar cells, nature photonics, vol. 8, no. 6, 2014, pp. 489. [16] minemoto, t. and m. murata, theoretical analysis on effect of band offsets in perovskite solar cells, solar energy materials and solar cells, vol. 133, 2015, pp. 814. [17] kemp, k.w., et al., interface recombination in depleted heterojunction photovoltaics based on colloidal quantum dots, advanced energy materials, vol. 3, no. 7, 2013, pp. 917-922. [18] minemoto, t. and m. murata, device modeling of perovskite solar cells based on structural similarity with thin film inorganic semiconductor solar cells, journal of applied physics, vol. 116, no. 5, 2014, pp. 054505. a. hima et al. ijeca-issn: 2543-3717. june 2018 page 41 [19] minemoto, t. and m. murata, impact of work function of back contact of perovskite solar cells without hole transport material analyzed by device simulation, current applied physics, vol. 14, no. 11, 2014, pp. 1428-1433. [20] liu, f., et al., numerical simulation: toward the design of high-efficiency planar perovskite solar cells, applied physics letters, vol. 104, no. 25, 2014, pp. 253508. [21] hui-jing du, w.-c.w., jian-zhuo zhu, device simulation of lead-free ch3nh3sni3 perovskite solar cells with high efficiency, chin. phys. b, vol. 25, no. 10, 2016, pp. 108802-108802. [22] ball, j.m., et al., optical properties and limiting photocurrent of thin-film perovskite solar cells, energy & environmental science, vol. 8, no. 2, 2014, pp. 602609. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 18-24 ijeca-issn: 2543-3717. december 2017 page 18 potential assessment of using dry cooling mode in two different solar thermal power plants t.e. boukelia 1 , m.s. mecibah 2 , a. laouafi 3 , a. mekroud 4 , a.bouraoui 1 1 laboratory of applied energetics and materials, mechanical department, jijel university, algeria 2 laboratory of mechanics, mechanical department, university of brothers mentouri, constantine 25000, algeria 3 department of electrical engineering, university of 20 august 1955-skikda, skikda, algeria 4 laboratory of renewable energies and durable development, mechanical department, university of brothers mentouri, constantine 25000, algeria taqy25000@hotmail.com abstract – most of concentrating solar power (csp) plants are usually installed in desert regions where water resource availability is a critical limitation due to the lack of water required for the exploitation of these systems in these regions. therefore, the aim of this study is to investigate the techno-economic competitiveness of deploying both modes of cooling (wet and dry) in two different parabolic trough solar thermal power plants integrated with thermal energy storage and fuel backup system; the first one is using thermic oil, while the other is working using molten salt. the obtained results show that the dry cooling mode can decrease the yields of the two power plants down to 8.7 % and 9.3 % for oil and salt configurations respectively. on the other hand, the levelized cost of electricity can increase by using this cooling option up to 9.3 % for oil plant, and 10.0 % for salt one. however, the main advantage of using dry cooling option is reducing water consumption which has been decreased by more than 94 % for both plants. the application of our methodology to other two sites worldwide, confirms the viability of the obtained results. the importance of this result is to show the effect of working fluids on the cooling system of solar power plants. keywords: cooling mode; dry; parabolic trough solar thermal power plant; wet. received: 01/12/2017 – accepted: 27/12/2017 i. introduction these with the rising price of fossil fuels, and the elevation of the levels of air pollution and gas emissions, solar energy has the potential to cater the world energy needs with clean and competitive power in the future. among technologies developed to convert pure solar radiation to useful energy such as heat or electricity, csp (concentrating solar power) is one of the most promising options for power generation. most of csp plants consist of solar field (sf), power block (pb), and optionally thermal energy storage (tes) system or fuel backup system (fbs) can be used for enhancing the system potential and stabilize the grid [1]. the existing csp plants convert thermal energy collected by the sf in the pb, based on conventional steam rankine cycle with regeneration. many studies in the literature compared different configurations of parabolic trough solar thermal power plants (ptstpps) with different working fluids such as steam/water, synthetic oil, and molten salt, to find the best technology with low investment cost and high thermal performances to be adopted in these systems. for example, reddy and kumar [2] performed an investigation to make a techno-economic assessment of a ptstpp with two different technologies; the first is based on synthetic oil as working fluid in the sf, while the other is a direct steam generation (dsg) plant. in the first step, and in addition to the operating conditions of these two plants, the design including solar field geometry have been optimized. secondly, the two optimized plants were chosen for the viability study in the indian climatic conditions. the obtained results show that dsg has a better levelized cost of electricity (lcoe) compared to oil plant. furthermore, boukelia et al [3] made a 4e (energy-exergy-economicenvironment) comparison between different plants based on synthetic oil and other based on molten salt. they found that molten salt plants have lower lcoe compared to the same configurations based on thermic oil. in another study [4], they found that it is possible to optimize salt plant to give a higher annual power generation and lower lcoe in comparison to oil optimized plant with almost 26 % and 15 % respectively. mailto:taqy25000@hotmail.com t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 19 furthermore, montes and his team [5] developed a thermofluidynamic model to evaluate energy and exergy sf performances with three primary working fluids: water/steam, thermic oil, and molten solar salt. according to their results, and from the point of view of the energy efficiency of the sf, oil shows better performance compared to the two others. on the other side, solar salt seems to be the best technology in terms of exergy performance. moreover, a comparative study based on both design and yield has been performed by giostri et al. [6]. they obtained better performances by using salt plant compared to oil one. on the other hand, the thermodynamics rules state that wet cooling of conventional steam rankine cycles is advantageous over dry cooling in terms of efficiencies since with wet cooling option the exit steam from the turbine will be cooled down faster and to a lower temperature than with the second option [7]. however, unlike conventional steam power plants, which are generally installed in the coastal regions, where water resource availability is not critical limitation, csp plants are usually installed in desert regions with semi-arid and arid climate, where there is a lack of water resources. therefore, it is so important to investigate the technoeconomic competitiveness of deploying dry cooling mode in such systems. some studies showed that the integration of dry cooling in solar thermal power plants could save more than 90 % of water consumption; however, the overall performance of such systems will be reduced due to the higher ambient temperatures [7]. liqreina and qoaider [7] analyzed the competitiveness of using dry cooling mode in a reference andasol 1 parabolic trough power plant. ma’an area (south of jordan) was taken as a case study. the results proved that by employing dry cooling mode in csp, the annual power generation has been decreased by more than 11 %, the water consumption has also decreased by more than 92 %, and this cooling option also increased the lcoe by almost 13 % in comparison to conventional wet cooling mode. colmenar-santos et al. [8] highlighted water consumption as one of decisive parameters for the erection of csp plants. they analyzed different technical alternative options for minimizing water usage, and their effects on these systems were also presented. furthermore, martín [9] optimized the operation of csp plant with dry cooling mode located in almería (south of spain) over a year. for this purpose, a multi period mixed integer non-linear mathematical formulation was used to optimize the operating working conditions in both thermal cycles and cooling system. another study performed by deng and boehm [10] reporting the potential performance of dry cooling in trough solar thermal power plants. the commercial gate-cycle was used to estimate the technical performances of both wet and dry cooling modes. in this study, las vegas (usa) has been considered for the simulation. other studies [11-13] investigated the same problem of using dry cooling mode in a solar thermal power plant. however, among studies published in the literature, no comparative study between the influence of using the two modes of cooling (wet and dry) in csp plants with different working fluids has been conducted. therefore, the objective of this paper is to investigate the technoeconomic competitiveness of deploying dry cooling mode in two solar thermal power plants considering both hourly and annual basis; the first is based on synthetic oil as primary heat transfer fluid (htf) in the sf and the other is using molten salt technology. the importance of such a study is to show the techno-economic impact of using the two cooling modes on solar power plants with two different main htfs. on the other hand, as there is still an open question about the possibility of using molten salt as primary heat transfer working fluid in the plant, this paper gives another decisive parameter that favors the using of molten salts in csp plants compared to synthetic oils. ii. data and methodology ii.1. plants configuration nowadays, most of the commercially operated ptstpps in the world have a capacity of 50 mwe. thereby, two configurations of large scale csp plants of 50 mw integrated with tes and fbs, have been selected in this study to perform the techno-economic analysis. the designs of the sf and pb of the investigated plants have been considered based on existing commercial plants. in order to study these two configurations, similar assumptions such as the size of the plant, components, etc. are imposed, in order to have a common ground for comparison. the difference between these two configurations is the heat transfer fluids (htf) which has been taken as thermic oil of type therminol vp-1 in the first configuration with a temperature range of 293-393 ˚c at the inlet and outlet of the sf, respectively, and molten solar salt (60% nano3+ 40% kno3) in the second one with a temperature range of (286-550 ℃). the sf consists of parabolic trough collector assemblies of solargenix sgx-1 type. each solar collector assembly is of 100 m length, 5 m of width aperture and consists of 12 modules. four solar collector assemblies are arranged in a row, along north–south horizontal axis and track the sun from east to west [14]. the two pbs (with oil and salt) of this work are assumed to operate using a steam regenerative rankine cycle of 50 mw. the considered plants are installed in bechar (latitude 31.38º n, longitude 2.15º w, altitude 806 m), algeria, which has been chosen due to its high direct solar irradiation (more than 2500 kw h/m 2 ). the two solar thermal plants have been incorporated with tes t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 20 and fbs, and two different cooling options (wet cooling mode with a condenser, and dry one based on air cooled system) were considered. the schematic layout of the two configurations is illustrated in fig. 1, while the common assumptions and nominal values of the main parameters considered in the two plants are listed in table 1. figure 1. schematic for the two studied configurations. table 1. the main inputs of the two proposed plants. configuration oil plant salt plant solar field  solar multiple 1.6  number of loops 184 167  aperture area (m 2 ) 346,141 314,160  collector orientation n-s n-s  collector design solargenix sgx-1  receiver design schott ptr 70  row spacing (m) 15 thermal energy storage indirect direct  full load hours (hr) 7.5  thermal capacity (kwht) 1,107.1 1003.65  storage volume (m 3 ) 16,683 4,953 fuel backup system  outlet set temperature (°c) 393 550 power block  outlet conditions  temperature (°c)/pressure (bar)  mass flow rate (kg/s) 296/15 567.1 286/1 303.42  inlet conditions  temperature (°c)/pressure (bar)  mass flow rate (kg/s) 393/20 567.1 550/3.7 303.42  net electrical output (mwe) 50 50 ii.2. mathematical modelling the techno-economic study based on energy and economic analysis is required to determine the viability of any energy system. in this paper, the free software system advisor model (sam) version 2014.1.14, was used to perform the simulation. the model used in this software was previously validated by price [15]. the detailed model used in this software is presented by wagner and gilman [16]. as the analytical model of the studied plants is quite significant and all the complexities involved in the power plants are considered in the software, the presented mathematical modelling in this work will be limited to the main equations of both energy and economic analyses, while the full detailed model can be found in the literature [16]. ii.2.1. energy analysis the total incident solar energy received by sf aperture area is given as: while the total useful energy delivered by the sf is presented as: therefore, the energy efficiency of the sf is given as: in this paper, the solar multiple (sm) is a key factor which defined as the ratio between thermal power obtained by the sf at design point and thermal power required by the pb at nominal conditions [17], and expressed as follow: t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 21 the sm was taken as 1.60 for both plants [17-18] to have common ground of comparison to perform technoeconomic analysis. on the other side, as solar thermal power plants suffer from low dispatch capacity compared to conventional thermal power plants based on fossil fuels, and in order to enhance the potential of the considered plants and to extend their working hours, this issue has been solved in this study by incorporating thermal energy storage and fuel backup system together at the same time to these plants. in this study, the full load hours of the storage defines the number of hours of energy supply for the operation of the pb. it is assumed to be 7.5 equivalent hours at the design point, and can be calculated as follows [16]: the main design parameters of the storage systems are presented in table 2. the plant therminol vp1 solar salt type of storage indirect direct full load hours of tes (hours) 7.5 7.5 tes thermal capacity (mwh) 1,107.09 1,003.65 tank high (m) 14 14 tank heater efficiency 0.98 0.98 table 2.the main parameters of the storage systems at the design point. furthermore, the fuel backup system is another component that supplies thermal energy to the working fluid at the inlet of the high pressure turbine whenever the thermodynamical state has not been obtained, while maintaining a total auxiliary contribution less than fossil fill fraction at the same time. this parameter can be defined as [19]: the energy efficiency of the pb is calculated as: where is the total thermal energy received by the pb, this total thermal energy received by the pb. the overall energy efficiency of the plant is given as: while the net capacity factor of the plants is given by: where: nd is the number of the days in a year. to perform this study, two different cooling mode in the power blocks were considered, wet cooling and dry one. the mathematical model of the heat rejection in these plants is presented in detail in the literature [16]. the main inputs for the cooling systems are summarized in table 3. table 3. the main inputs for the two cooling options [16]. type of cooling wet (evaporative) dry (air cooled) ambient temperature at deign (ºc) 20 20 the cooling water temperature rise across the condenser (ºc) 10 temperature difference at the hot side of the condenser (ºc) 3 circulating water pressure drop (bar) 0.37 cooling water pump mechanical/isentropic efficiency 0.75/0.80 fan mechanical/isentropic efficiency 0.75/0.80 0.94/0.80 the condenser air pressure ratio 1.0028 ii.2.2. economic analysis as the levelized cost of electricity (lcoe) is the major figure to analyze the viability of any solar thermal power plant [20], and this indicator can be significantly affected by assumptions and inputs such as operation and maintenance and investment costs, the economic inputs of this study were set according to previous studies and databases [16, 17, 21]. the economic assessment is performed using the software sam, where the lcoe is calculated as follows: where, iii. results and discussion the annual mean hourly water consumption mass flow rates (kg/s), net electric power outputs (mwh), power cycle efficiency, in addition to annual comparative analysis of using wet and dry cooling modes in the two presented configurations are presented in figures 2, 3, 4 and table 4, respectively. table 4. annual comparative analysis of using wet and dry cooling modes in the two optimized plants. oil plant salt plant wet dry wet dry mean energy efficiency of the plant ( (%) 18.64 17.01 18.26 16.56 capacity factor (%) 38.2 34.9 34.0 30.8 annual power generation (gwh) 165.74 151.26 147.35 133.63 lcoe (cent/kwh) 11.58 12.66 9.68 10.65 annual water consumption (m 3 ) 633,635 32,765 518,329 26,319 t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 22 figure 2. annual mean hourly water consumption in the two studied plants by using wet and dry cooling modes. it can be illustrated that the main advantage of using the dry cooling option is to reduce the amount of water consumption by almost 95 % in both plants. on the other hand, the salt plants with both modes of cooling still consume less water in comparison to those based on thermic oil with 18.19 % for wet mode and 19.67 % for the other one. the water usage in the plants with dry cooling is limited to steam cycle makeup water in addition to mirror cleaning which was taken into consideration as 63 washes per year and 0.7 l/m 2 for every wash [3], and excludes water usage for cooling. 0 2 4 6 8 10 12 14 16 18 20 22 0 10 20 30 40 50 q n e t (m w h ) time (hour) oil (wet) salt (wet) oil (dry) salt (dry) figure 3. annual mean hourly net electric power output of the two studied plants by using wet and dry cooling modes. 0 2 4 6 8 10 12 14 16 18 20 22 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40  p b time (hour) oil (wet) salt (wet) oil (dry) salt (dry) figure 4. annual mean hourly power cycle efficiency of the two studied plants by using wet and dry cooling modes. on the other side, the main disadvantage of using this option is the negative effect on the yields of the studied plants; the efficiencies of the two plants have decreased from 18.64 % (oil plant) and 18.26 % (salt plant) to 17.01 % and 16.56 %, respectively. this represents a difference of almost 8.75 % in oil plant, and 9.31 % in plant based on salt technology. this effect is due to the drooping in power cycle efficiencies affected by the decreasing of cooling performances and the increasing of the plants parasitic power consumptions in the power cycles. this decreasing causes a reduction in the annual power generation and capacity factor of about 8.6 % in oil plant and 9.4 % in salt plant. since the lcoe totally depends on the investment costs and on the annual power generation of the plant, this parameter increases up to 12.66 cent$/kwh and 10.65 cent$/kwh for oil and salt configuration, respectively. this means an increase of 9.3 % and 10.0 % for oil configuration and salt configuration, respectively. while the selection of a solar thermal power plant is contingent upon the identification of sites well suited to the system, the performances of these plants are highly affected by the climatic conditions of sites chosen for the simulation, as they have huge effects on both solar field and cooling system which are the main components of these systems. therefore, it is highly recommended to simulate the considered plants in other locations with different solar resources, different air temperature variations and different altitudes, to confirm the viability of our study for different sites and conditions. thereby, in this paper, two other sites (granada and dagget) alongside with bechar have been selected. t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 23 table 5. the viability analysis of the studied plants in other sites. granada (37.18 o n, 3.78 o w) dagget (34.86 o n, 116.78 o w) bechar (31.38 o n, 2.15 o w) elevation (m) 599 588 722 annual dni (kwh/m 2 ) 2033.3 2791.4 2568.9 dry bulb temperature (ºc) 14.9 19.8 21.8 oil plant type of cooling wet dry wet dry wet dry annual power generation (gwh) 127.82 118.68 172.83 158.79 165.74 151.26 lcoe (¢/kwh) 14.92 16.05 11.10 12.05 11.58 12.66 annual water consumption (m 3 ) 502,344 29,049 658,336 33,487 633,635 32,765 salt plant annual power generation (gwh) 107.66 99.21 148,12 135,69 147.35 133.63 lcoe (¢/kwh) 13.13 14.22 9.60 10.45 9.68 10.65 annual water consumption (m 3 ) 407,070 23,609 519,119 26,428 518,329 26,319 as it can be noted in table 5, the lowest values of both annual power generation and water consumption are for the salt plant using dry cooling mode installed in granada (south of spain), with values of 99.21 gwh and 23,609 m3, and can take the maximum values for oil plant with the wet cooling option of 172.83 gwh and 658,336 m3 for dagget (california, usa). this difference in these two factors is due to the difference in solar resource potentials represented by solar radiation intensity and working hours of the plant. moreover, plants with higher power generation need more water for cooling system. on the other hand, the salt plant cooled by wet option at dagget gives the lowest value of lcoe (9.60 ¢/kwh), while the one using oil as the primary htf, and coupled with dry cooling system at granada shows the highest value of lcoe (16.05 ¢/kwh). as we mentioned, and in order to confirm the viability of the obtained results for plants installed in bechar, it is required to apply the study for other sites. the obtained results show that the drop in the annual power generation between wet and dry cooling options is between 7.7 % and 9.6 % for oil plant, 8.5 % and 10.2 % for salt plant. the same note for annual water consumption as there is a decreasing in water usage in the studied plants between wet and dry of 94.2 % and 94.9 % for both plants (oil and salt). while the lcoe varies between the range of 7.5 9.32 ¢/kwh for oil plant 8.3-10.0 ¢/kwh. this clearly confirms the ability of applying our study to other locations worldwide. iv. conclusion this paper investigates the effect of deploying dry cooling mode in two different configurations of ptstpp integrated with tes and fbs; the first configuration uses thermic oil (therminol vp1) as primary heat transfer fluid in the plant, while the second one is using molten solar salt (60% nano3+ 40% kno3). by using the dry cooling option in the two studied configurations, there is a higher drop in the yields of oil plant (a decrease of 8.7 %) and salt plant (a decrease of 9.3 %), in addition to the rise of the lcoe up to 9.3 % and 10.0 % in oil and salt plants, respectively. the obtained results have a big importance to show the effect of working fluids on the cooling system of solar power plants. it is recommended to preform another study refers to the hybrid mode of cooling before drawing a final conclusion of the effects and techno-economic competiveness of using the three different modes of cooling. references [1] hl zhang, j baeyens, j degrève j, and g cacères. concentrated solar power plants: review and design methodology. renew sust energ rev, vol. 22, 2013, pp.466-81. [2] ks reddy, kr kumar. solar collector field design and viability analysis of stand-alone parabolic trough power plants for indian conditions, energ sustain dev, vol. 16(4), 2012, pp.456-70. [3] te boukelia, ms mecibah, bn kumar, ks reddy. investigation of solar parabolic trough power plants with and without integrated tes (thermal energy storage) and fbs (fuel backup system) using thermic oil and solar salt, energy, vol. 88, 2015, pp. 292-303. [4] te boukelia, o arslan, ms mecibah. potential assessment of a parabolic trough solar thermal power plant considering hourly analysis: ann-based approach, renew energy, vol. 105, 2017, pp 324333. [5] mj montes, a abánades, jm martinez-val. thermofluidynamic model and comparative analysis of parabolic trough collectors using oil, water/steam, or molten salt as heat transfer fluids, j sol energ eng, vol. 132(2), 2010, 021001. [6] a giostri, m binotti, m astolfi, p silva, e macchi, and g manzolini, g. comparison of different solar plants based on parabolic trough technology, sol energy, vol. 86(5), 2012 pp.1208-21. [7] a liqreina, and l qoaider. dry cooling of concentrating solar power (csp) plants, an economic competitive option for the desert regions of the mena region, sol. energy, vol. 103, 2014, pp.417424. [8] a colmenar-santos, d borge-diez, cp molina, and m castro-gil. water consumption in solar parabolic trough plants: review and analysis of the southern spain case, renew. sustaina. energy rev, vol. 34, 2014, pp.565-577. [9] m martín. optimal annual operation of the dry cooling system of a concentrated solar energy plant in the south of spain, energy, vol. 84, 2015, pp.774782. [10] h deng, and rf boehm. an estimation of the performance limits and improvement of dry cooling on trough solar thermal plants, appl. energy, vol. 88(1), 2011, pp.216-223. t.e. boukelia et al. ijeca-issn: 2543-3717. december 2017 page 24 [11] a poullikkas, i hadjipaschalis, g kourtis. a comparative overview of wet and dry cooling systems for rankine cycle based csp plants, trends in heat & mass transfer, vol. 13, 2013, pp.27-50. [12] l qoaider, and a liqreina. optimization of dry cooled parabolic trough (csp) plants for the desert regions of the middle east and north africa (mena), sol. energy, vol. 122, 2015, pp.976-985. [13] se trabelsi, r chargui, l qoaider, a liqreina, and a guizani. techno-economic performance of concentrating solar power plants under the climatic conditions of the southern region of tunisia, energy convers. manage, vol. 119, 2016, pp.203-214. [14] te boukelia, ms mecibah. estimation of direct solar irradiance intercepted by a solar concentrator in different modes of tracking (case study: algeria), int. j. amb energy, vol. 36 (6), 2015, pp.301-308. [15] h price. a parabolic trough solar power plant simulation model, international solar energy conference. hawaii, usa, 15-18 march 2003. [16] mj wagner, p gilman. technical manual for the sam physical trough model, nrel.gov/docs/fy11osti/51825.pdf. last accessed 07/06/2017. [17] mj montes, a abánades, jm martinez-val, m valdés. solar multiple optimization for a solar-only thermal power plant, using oil as heat transfer fluid in the parabolic trough collectors, sol energy, vol. 83(12), 2009, pp.2165-76 [18] mj montes, a abànades, jm martȋnez-val. performance of a direct steam generation solar thermal power plant for electricity production as a function of the solar multiple, sol energy, vol. 83(5), 2009, pp.679–89, [19] t larraȋn, r escobar, j vergara. performance model to assist solar thermal power plant siting in northern chile based on backup fuel consumption, renew energy, vol. 35(8), 2010, pp.1632–43. [20] j dersch, m geyer, u herrmann, sa jones, b kellyd, r kistner, w. ortmanns, r pitz-paal, h price. trough integration into power plants—a study on the performance and economy of integrated solar combined cycle systems, energy, vol. 29(5), 2004, pp.947-959. [21] nrel. system advisor model (sam) case study: andasol-1. sam.nrel.gov/sites/sam.nrel.gov/files/content/case_stu dies/sam_case_csp_physical_trough_andasol1_2013-1-15.pdf. last accessed 07.06.2017. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 18-23 ijeca-issn: 2543-3717. june 2018 page 18 control with sliding mode of a five-phase series-connected twoasynchronous motor drive omar zouaid 1 , lazhari nezli 2 1 polytechnic national school of algiers, algeria 2 laboratory of control and process (lcp), polytechnic national school of algiers, algeria o_zomardj125@yahoo.fr abstract – in this paper, we study sliding mode control of series-connected five-phase two asynchronous machines supplied with a three levels inverter. after presentation of multiphase machines, we worked out the mathematical model of five phase asynchronous machine supplied with voltage inverter. application of park transformation reduces considerably the mathematical model of machine. after, we applied vector control and sliding mode control to the five-phase induction machine. after that, we study a multi-machine system, which comport five-phase two asynchronous machines supplied with a single voltage inverter. in the last, we had the sliding mode control of series-connected five-phase two asynchronous machines. simulations are presented to show the effectiveness of the control strategy. we observe that an appropriate transposition of phase’s order permits an independent control of two machines. keywords: five-phase, asynchronous machine, multi-machine systems, phase’s transposition, sliding mode control received: 01/06/2018 – accepted: 28/06/2018 i. introduction ever since the inception of the first fivephase variable speed drive in 1969 [1], five-phase machines have been considered as a viable alternative to threephase machines. this especially holds true for highpower and safety-critical variable speed applications, where a five-phase drive can be realized using inverters with smaller rating per leg while enabling fail-safe operation in redundancy mode [2,3]. a vector control scheme for a five-phase machine is in its basic form, regardless of the machine type, identical to the corresponding vector control scheme for a threephase machine [4,5]. however, since vector control of an ac machine requires only two axis currents for decoupled flux and torque control, higher torque density can be achieved in a five-phase machine by utilizing the remaining two degrees of freedom. the injection of the third stator current harmonic enables utilization of the third spatial harmonic of the field for torque production, in addition to the fundamental harmonic of the field [2,3]. a rather different use of these additional degrees of freedom was proposed in [5]. on the basis of considerations related to the machine's rotating field, it was suggested to connect two five-phase machines in series and supply them from a single five-phase source. by introducing an appropriate phase transposition in this series connection, it was reasoned that the two machines could be controlled completely independently, using basic vector control schemes, although they are supplied from the common five-phase source. the major advantage of such a two-motor drive system is the reduction op the number of required inverter legs, when compared to an equivalent two-motor three-phase drive system (from six to five). this translates into increased reliability, due to a smaller number of components. on the basis of this novel d-q axis model of the seriesconnected two-motor drive system, an indirect rotor flux oriented control scheme is designed. a detailed simulation study is finally undertaken. the complete drive system, including the hysteresis current controllers and the voltage source inverter (vsi), is simulated for a number of transients. it is shown that completely decoupled flux and torque control results not only for each of the two machines, but for one machine with respect to the other as well. the correctness of the developed models and the vector control scheme are verified in this way ii. description of the drive the drive consists of two five-phase machines, which can be either induction or synchronous (permanent magnet or synchronous reluctance) and which can be freely mixed within the system. it is here assumed that the machines in question are both induction motors, mailto:o_zomardj125@yahoo.fr o. zouaid et al. ijeca-issn: 2543-3717. june 2018 page 19 without any loss of generality. five-phase stator windings of the two machines are connected in series, with an appropriate phase transposition, as illustrated in fig. 1. phase transposition in the series connection is a necessary prerequisite for independent vector control of the two control. inverter phase sequence is denoted in fig. 1 with capital letters a,b,c,d,e, while the phase sequence of the two machines, respecting the spatial distribution of the windings, is identified with lower case letters a,b,c,d,e. spatial displacement between any two consecutive phases in the machines equals 2 5  . according to the connection diagram of fig. 1, inverter phase-to-neutral voltages and the correlation between inverter output currents and machine phase currents are given with 1 2 1 2 1 2 1 2 1 2 a as as b bs cs c cs es d ds bs e es ds v v v v v v v v v v v v v v v           (1) 1 2 1 2 1 2 1 2 1 2 a as as b bs cs c cs es d ds bs e es ds i i i i i i i i i i i i i i i           (2) it is assumed for modeling purposes that all the standard assumptions of the general theory of electrical machines apply [9], including the one related to sinusoidal distribution of the resulting field in the machine. rotor windings are initially taken as five-phase as well, for the sake of generality. iii. drive modelling iii.1. phase-variable model two machines of fig. 1 are assumed to be of different parameters and ratings, for the sake of generality. the electrical subsystem's model of the drive in fig.1 is of the 15th order and it can be represented in matrix form (underlined quantities) with  d li v ri dt   (3) where machines. its purpose is to make flux/torqueproducing currents of one machine non flux/torqueproducing currents in the second machine, and vice versa [5]. the two-motor drive is supplied from a single fivephase vsi, which is current controlled. current control is exercised upon phase currents in the stationary reference frame, using either hysteresis or ramp-comparison current 0 0 inv v v            1 2 inv r r i i i i            (4) figure1. five-phase two-motor drive with series connection of phase windings and an appropriate phase transposition.   tinv a b c d e v v v v v v (5)   tinv a b c d e i i i i i i 1 2 1 2 s s r r r r r r r           (6) ' ' 1 2 1 2 1 1 ' 1 2 0 0 s s sr sr rs r rs r l l l l l l l l l            sub-matrices of the inductance matrix identified with the prime symbol are those whose form has been altered through the phase transposition operation. iii.2. decoupling transformation decoupling (clark's) transformation matrix is applied first. let the correlation between original phase variables andnew  ,  variables be given with abcde f c f   . o. zouaid et al. ijeca-issn: 2543-3717. june 2018 page 20 where c is the power-invariant transformation matrix [6] 1 cos cos 2 cos 3 cos 4 0 sin sin 2 sin 3 sin 4 2 1 cos 2 cos 4 cos 6 cos 8 5 0 sin 2 sin 4 sin 6 sin 8 0 1/ 2 1/ 2 1/ 2 1/ 2 1/ 2 c x y                                 (7) application of (8) in conjunction with inverter voltages yields axis components of the inverter voltages 0 inv a inv b inv cx inv dy inv e vv vv c vv vv vv                                  (8) which can be further expressed, using correlation (l), as functions of the voltage axis components of the two machines 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 20 0 inv as as s xs inv bs cs s ys inv cs es xs sx inv ds bs ys sy inv es ds v v v vv v v v vv c v v v vv v v v vv v vv                                                         (9) due to the absence of the neutral conductor inverter zero sequence voltage components must equal zero. the correlation between inverter voltage axis components and individual machine's voltage axis components implies series connection between appropriate   and x-y circuits of the two machines. a corresponding correlation between inverter output currents and   and x-y current components of the two machines is obtained by using (8) in conjunction with (2). 1 2 1 2 1 2 1 2 inv s xs inv s ys inv x xs s inv y ys s i i i i i i i i i i i i                (10) the zero sequence component is omitted due to the star connection of the system without neutral conductor. iii.3. model in the stationary common reference frame upon application of the decoupling transformation matrix (9) onto inverter and rotor voltage equations of (3). rotational transformation matrix, leading to the d-q system of equations, is applied in conjunction with rotor equations (angle  is the instantaneous rotor position, which is different for the two machines: cos sin sin cos 1 1 1 rd                    (11) since the stator-to-rotor coupling appears in   equations only and torque production' is entirely governed by   current (flux) components, rotational transformation is not applied to x-y rotor equations. as rotational transformation is applied to rotor windings only, indices ,  and d, q are interchangeable in inverter (stator) equations (8)-(10). the resulting system model is in the stationary common reference frame and is in general of the 15 th order. however, taking into account that rotor windings of the two machines are short-circuited, rotor x-y component equations and rotor zero sequence equation can be omitted from further consideration. zero sequence component equation for the inverter can be omitted as well. the electro-magnetic part of the drive system can then be represented with eight first-order differential equations. the four inverter equations are 1 1 1 1 1 2 2 1 1 1 1 1 2 2 2 1 1 2 2 2 2 ( ) ( ) ( ) inv inv inv inv invd dr d d s d ls m m s d ls inv inv q qr qinv inv inv q s q ls m m s q ls inv inv inv inv invx x dr x s x ls s x ls m m y di di di v r i l l l r i l dt dt dt di di di v r i l l l r i l dt dt dt di di di v r i l r i l l l dt dt dt v                   2 1 1 2 2 2 2 ( ) inv inv y y qrinv inv inv s y ls s y ls m m di di di r i l r i l l l dt dt dt       (12) or, in terms of individual machine d-q axis stator voltage components (according to (9)) 1 2 1 2 1 2 1 2 inv d ds xs inv q qs ys inv x xs ds inv y ys qs v v v v v v v v v v v v         (13) o. zouaid et al. ijeca-issn: 2543-3717. june 2018 page 21 rotor voltage equilibrium equations of the two machines are: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 0 ( ) ( ( ) ) 0 ( ) ( ( ) ) 0 ( ) ( ( ) inv invd dr r dr m lr m m q lr m qr inv q qr inv r qr m lr m m d lr m dr inv invx dr r dr m lr m m y lr m qr di di r i l l l l i l l i dt dt di di r i l l l l i l l i dt dt di di r i l l l l i l l i dt dt                         2 2 2 2 2 2 2 2 2 2 2 ) 0 ( ) ( ( ) ) inv y qr inv r qr m lr m m x lr m dr di di r i l l l l i l l i dt dt        (14) finally, torque equations of the two series connected machines are given in terms of inverter current axis components with 1 1 1 1 1 2 2 2 2 2 inv inv em m dr q d qr inv inv em m dr y x qr c p l i i i i c p l i i i i         (15) iv. design of sliding mode control the sliding mode control is one of simplest approaches of the robust control. very good performances (response time, precision) can be obtained in the presence of uncertainties on the parameters of the system and their variations on the one part, and uncertainties on the models of the system on the other part. these performances are obtained at the price of a very strong activity of order which can result in very strong oscillations called “chattering". the design of the controllers by sliding mode takes into account the problems of stability and good performances in a systematic way in its approach, which is devised into three principal stages [6]: -choice of surfaces, -establishment of the conditions of existence and convergence, -determination of the law of control. iv.1. choice of the surface of commutation j.j. slotine proposes a format general equation to determine sliding surface 1 ( ) n d s x e dt          (16) d e x x  : variation  : positif coefficient n: order of the system d x : desired value iv.2. condition of convergence the condition of convergence is defined by the equation of lyapunov. it makes surface attractive and invariant    . <0s x s x  (17) figure 2. modes of trajectory in the plan of phase. v. sliding mode control of a five-phase series-connected two-motor drive if one chooses n=1, surfaces are written: for the first machine:         1 1 1 1 1 1 1 1 1 1 1 1 r r ref r r r ref r s s s d d ref d s s s q q ref q s s s i i i s i i i                 (18) for the second machine:         2 2 2 2 2 2 2 2 2 2 2 2 r r ref r r r ref r s s s d d ref d s s s q q ref q s s s i i i s i i i                 (19) decoupling resulting from the orientation of the rotor flow of the two machines enables us to control flow and speed separately, by using the current s d i for the control of flow and the current s q i for the speed control. v.1. application of the control to the first machine along the axe “d”     1 1 1 1 1 1 1 1 1 1 0 1 s d n r r s r d eq r ref r m m i k sign s s t i l l                (20) o. zouaid et al. ijeca-issn: 2543-3717. june 2018 page 22 and  1 0 s d s i           1 1 1 1 1 1 1 2 1 1 1 1 1 2 1 1 1 1 1 s s d n id d s s s s rm d eq s ls d ref d s ls s q r r v k sign s i l v l l i r i l l i t l                (21) along axe “q”     1 1 1 11 1 11 1 1 1 1 1 0 s q n r r refs rr q eq m r r i k sign s j fs i l p l                   (22) and  1 0 s q s i        1 1 1 1 1 1 1 2 1 1 1 1 1 2 1 1 1 1 1 ( ) s s q n iq q s s s s rm q eq s ls q ref q s ls s d r r v k sign s i l v l l i r i l l i l                  (23) v.2.application of the control to the second machine along the axe “d”   2 2 2 2 22 2 2 2 1 s d n r s r r refd eq r m m i k sign s t i l l            (24) and        2 2 2 2 2 2 2 1 2 2 2 2 2 1 2 2 2 2 2 s s d n id d s s s s rm d eq s ls d ref d s ls s q r r v k sign s i l v l l i r i l l i t l                (25) along the axe “q”   2 2 2 22 2 2 2 2 2 2 2 s q n r r refs r q eq m r r i k sign s j f i l p l               (26) and        2 2 2 2 2 2 2 1 2 2 2 2 2 1 2 2 2 2 2 s s q n q s s s s rm q eq s ls q ref q s ls s d r r v k sign s i l v l l i r i l l i l                  (27) figure 3. sliding mode control of a five-phase series connected two-motor drive vi. simulation results the transposition of the phases allowed the independent control from two machines. we notice that the speed and rotorique flow of two machines after a short transitory regime towards the compulosry references .during the application of the load at the moment t=0.5s, the speed decreases, then returns to its reference. we notice the same thing when the load is iliminated.the undulations of the couple are always due to the not sinusoidal shape of the tension of exit of the inverter. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 500 1000 1500 t(s) v it e s s e d e r o ta ti o n d e l a p re m iè re m a c h in e ( t r/ m in ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 600 700 800 900 1000 t(s) v it e s s e d e r o ta ti o n d e l a d e u x iè m e m a c h in e ( t r/ m in ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -5 0 5 10 15 20 25 t(s) c o u p le é le c tr o m a g n é ti q u e d e l a p re m iè re m a c h in e ( n .m ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -5 0 5 10 15 20 t(s) c o u p le é le c tr o m a g n é ti q u e d e l a d e u x iè m e m a c h in e ( n .m ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.2 0.4 0.6 0.8 1 t(s) f lu x d ir e c t ro to ri q u e d e l a p re m iè re m a c h in e ( w b ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 t(s) f lu x d ir e c t ro to ri q u e d e l a d e u x iè m e m a c h in e ( w b ) figure 4. simulation results of the sliding mode control of a five-phase series connected two-motor drive o. zouaid et al. ijeca-issn: 2543-3717. june 2018 page 23 vii. conclusion the results of simulation showed the importance of the transposition of phases applied for the independent control from two machines. we noticed that the use of regulators “sliding mode” improved the ansewer of the machine, beter than during the use of regulators pi, we supposed that the parameters do not vary, what is not the case in practice, the parameters of machines vary either by heating or by saturation, and thes variations influence directly the variables of exit of the control. acknowledgements i would like to thank my advisor lazhari nezli for her constant support, suggestions and scientific guidance during all stages of my work. references [1] e.semail, e.levi, a.bouscayrol, x.kestelyn, (2002) “multi-machine modeling of two series connected five-phase synchronous machines: affect of harmonics on control”, ieee-ias'04, seattle (washington), vol.1, pp71-78. [2] h.a.toliyat, h.xu, l.j.petersen, (2002) “five-phase induction motor drives with dsp-based control system ”, ieee transactions on power electronics, vol.17, no. 4, pp524-533. [3] e.levi, m.jones, s.n.vukosavic, h.a.toliyat “a novel concept of a multiphase, multi-motor vector controlled drive system supplied from a single voltage source inverter”, ieee [lip-80]. [4] c.namuduri and p.c. sen, (1986) “a servo control system using a self controlled synchronous motor (scsm) with sliding mode controller”,ieee ias annuel meeting, pp56-65. [5] e.levi, m.jones, s.n.vukosavic, h.a.toliyat, a.iqbal, (2006) “modelling, control and experimental investigation of a five-phase series-connected twomotor drive with single inverter supply”, ieee trans, energy convers. [6] t.a.lipo, (2004) “a d-q model for six phase induction machines”,proc. icem'80, pp.860-867, athens, greece, 1980 trans,power electronics, vol. 19, pp320-335. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 28-36 ijeca-issn: 2543-3717. june 2019 page 28 study of photovoltaic systems with differences connecting configuration topologies for applications in renewable energy systems mouhoub birane 1* , abdelghani chahmi 2 1 university of amar telidji laghouat. algeria 2 electrical drives laboratory, university of sciences and technology, oran, algeria email*: m.birane@lagh-univ.dz abstract –this paper focuses in the optimization of the efficiency of photovoltaic power conversion systems; we present a new alternative for improving both the optimization of the efficiency of photovoltaic power conversion chain. in this way, we present to the valuation problem of photovoltaic by new coupling systems between photovoltaic generators and their loads and performance of photovoltaic (pv) systems and the efficiency of the energy conversion by using different configuration of power converters. different type’s improvements have been proposed of different architecture in order to choose the correct pv architecture for each pv installation on the efficiency improvement in all power conversion level stages between pv cells and loads. in this context, this work presents the study and adaptive simulation of photovoltaic systems with micro inverters configurations for applications of renewable energy. we performed comparative between a central and distribution connection of converter via an adaptation floor with maximum power point tracker (mppt) control. for this reason, it is important to know different types of architecture and different configuration of power converters in order to choose the correct pv architecture for each pv installation. simulation results are used to demonstrate the proposed topologies to provide improvement in efficiency over existing traditional pv systems. keywords: photovoltaic systems, maximum power point tracker mppt, topologies, micro inverters, performance, power, dc-dc converters received: 01/03/2019 – accepted: 28/04/2019 i. introduction the world's major energy sources are non-renew able and are faced with ever increasing demand, thus are not expected to last long. besides being non-renewable, these sources includes mainly of fossil fuels, contribute tremendously to the perennial problem of global warming, renewable sources of energy acquire growing importance due to its enormous consumption and exhaustion of fossil fuel. solar energy could be one of the significant sources as an alternative energy for the future. such ambient energy can come from various green energy sources such as solar, thermal, wind, and kinetic. energy .in regard to endless importance of solar energy, it is worth saying that photovoltaic energy is a best prospective solution for energy crisis [1]. in the literature, different topologies for distributed power conversion for pv system have been studied. the architecture of the power converter is important in a pv system. this structure determines the main characteristics of the photovoltaic installation, the competitive topologies must be ready to fulfill these requirements with minimal changes on the installation as the amount the pv modules need for the pv system and its type of connection. the effect of the partial shadowing or mismatch between pv modules in the energy production will also depend on the type of the architecture. nevertheless, the price and cost of the pv also depends on the choice of the architecture, the choice will involve a bigger or smaller energy production and efficiency as well as an importance difference in the cost. for this reason, it is important to know different types of architecture in order to choose the correct pv architecture for each pv installation [2]. the upgradeability of topologies can be evaluated by detecting evolvable patterns, which they do not interfere with the overall operation. furthermore, if modules need to be replaced during the plant’s lifespan, an upgradeable installation must easily integrate new components without degrading its initial performance [3]. the competitive topologies must be ready to fulfill these requirements with minimal changes on the installation. the main architectures of the nowadays pv system will be analyzed, following their evolution and looking for the future tendency. abder image placée mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 29 gpv in the central inverter topology means that pv-panels are connected in one common array both series and parallel that is connected to one large inverter (implemented by mppt system). moreover, the losses due to partial shading are reduced because each string operates at its maximum power point. additional strings can be easily added to the system to increase its power rating, thus, increasing the flexibility in the design of the pv system. this system increases the system efficiency, the result of pv array is connected to a single dc/dc converter .this topology has the economic benefits as the number of the inverters is small, but the partial shadowing of the one panel will effect on the whole array power output. the reduction of the generated power is caused by the characteristics of the pv-panels. the main advantages of the centralized inverter are the simplicity of the layout [4]. in the string inverter configuration, each string has its own inverter and all inverters operate in parallel to supply the load.. this system increases the system efficiency, but with additional cost due to the increase in the number of inverters [5]. the goal of the research presented in this paper is structured around three main parts. firstly, we present different topologies in details and discussing different proposed pv topologies such as adaptive pv central-inverter configuration, and the adaptive pv string-inverter configuration including some illustrations of different operational conditions and the controller logic. secondly, we describe and analyze this characteristic curve by using dc-dc converters. the switching power converter dc-dc are widely used in photovoltaic systems to transform dc power, and are also used in maximum power point tracker (mppt) an adaptive photovoltaic (pv) system is proposed adaptive configuration is analyzed form different possible topologies. finlay is organized as follows. analyses and simulation of the performance of the different configurations are presented tools are used to demonstrate that the proposed topologies provide improvement in efficiency over existing traditional pv systems. furthermore, a prototype has been designed and developed we present and discuss the obtained results via simulation using a co-simulation matlab and psim software. furthermore, results of both systems are analyzed and compared. in the conclusion, the key show your results presented a potential research idea for future work in this field is proposed. ii. connection topologies of pv systems many type of association can be envisaged, the series and parallel connection of converter involve a major power transfer capability, the utility interactive system, the simplest system in terms of its number of components, can be configured with added components to serve its intended purpose and improve efficiency. these configurations can be classified into; central converter topology, string converter topology. ii.1. centralized converter topology the simplest configuration is the central inverter system, shown in fig. (1), where pv modules are connected to form strings. in the central inverter topology, strings consisting of series connected pv panels are connected in parallel to obtain the desired power. the resulting pv array is connected to a single dc/dc converter. the main advantage of the central inverter topology is the low cost as compared to other topologies as well as the ease of maintenance of the inverter. the thus structured pv high power of the generator is connected dc side to a single converter. this central inverter has a high efficiency at reduced costs. however, this topology has low reliability as the failure of the inverter will stop the pv system from operating [6]. this is because each string has its own mpp according to the operational conditions and shadowing effect. fig. 1.central converter configuration ii.2. string converter topology in the string converter configuration, shown in figure (2), each string has its own converter and all inverters operate in parallel or series to supply the load. in string topology, each string is connected to a dc-dc converter. the outputs of the dc-dc converters are connected to the centralized grid-tied inverter, which may not be the desired voltage required to obtain mppt for all panels. consequently with this configuration not all the panels are utilized effectively. the problems of the partial shadowing of array each of the pv-modules gets equipped by parallel diode, that by passes the module in case if module is shadowed or damaged. some of the modules get produced with built in diodes for several cells of pv-panel. this system increases the system efficiency, but with additional cost due to the increase in the number of converter [5]. mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 30 fig. 2.string converter configuration iii. photovoltaic arrays in order to implement the cell into real application, a combination of cells forms different sizes where a module consists of connected pv cells in one frame, and an array is a complete pv unit consisting of connected modules with structural support [7]. these structures can be used to supply power to scalable applications known as photovoltaic plants, which may be stand-alone systems or grid-connected systems [8]. modules can be connected in different ways to form pv array. this is done for the sake of voltage/current requirement of the power conditioning units of the pv system. in order to do that, a series and parallel connections of pv modules are needed. fig. 3.the typical electric protections in a pv module. fig. 4.the association of pv module iv. shading of pv system shading and mismatch losses of pv system are considered very critical problems in the pv systems. significant reduction in generated power from solar pv arrays occurs when the shading falls across some pv modules, leading to extra losses [9]. pv modules are very sensitive to shading. when one full cell is hard shaded by structure that stops light from reaching the cell(s), the voltage of that module will drop to half of its non shaded value in order to protect itself as shown in fig. (5). fig.5. shading affects me a tiny drain of energy on the entire system v. maximum power point tracking (mppt) the main goal of a mppt control is to automatically find at each time the vopt and iopt of a pv array. best mppt control algorithms have to be fast, stable, robust, and efficient. mppt methods, commonly used in widespread applications, are currently reported in the literature [10]. mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 31 fig.6.simplest electrical scheme block of a typical power conversion chain the current and voltage measurements are important parts in the mppt controls, since they affect in the accuracy and the efficiency of the controls. vi. analysis of dc / dc converter in this paper we describe and analyze a new way to measure characteristic curve by using dc-dc converters. the switching power converter dc-dc are widely used in photovoltaic systems to transform dc power between a voltage and another, and are also used in maximum power point tracker (mppt) . the electrical schema of the boost converter is reminded in the fig. (7), the boost converter is one of the simplest dc-dc converters. in a dc transformer the relationship of transformation can be controlled electronically by changing the duty cycle of the converter in the range [0, 1]. the relationships used for the design are the conventional relationship between the output voltage, the input signal and the duty ratio [11]: inout vv   1 1 nowadays, there are two widespread and costeffective technologies suitable for the implementation of the proposed converter switches: mosfet and igbts because both technologies are available for the intended operation voltage, current and frequency [12]. losses of igbt conduction losses mainly depend on the duty cycle, load current and junction temperature, whereas, switching losses depends on the load current, dc link voltage, junction temperature and switching frequency [12]. if the switching frequency is higher, then the losses will be higher. the total average power of the igbt is the sum of the conduction loss, turn on and turn off losses as shown in eqn. (1). (2) when the igbt turns on, collector current increases rapidly and the voltage across the collector to emitter decreases. (3) time period ‘t’ is inversely proportional to frequency ‘f’ the total average power loss incurred in the igbt can be obtained by integrating all the values of power losses over a period of time. the total average power loss for the igbt can be split into three phases; 1) turning on the device, 2) conducting period, 3) turning off the device. the conduction losses are independent of the switching frequency but dependant on the duty cycle, the values for the energy loss eon and eoff are given in the dynex datasheet; therefore there is no need to calculate these values [12]. the switching energies are then simply multiplied by the switching frequency to give the power loss for on and off time as shown in eqn. (5). total losses: the average total power loss in diode is given by eqn. (7). reverse recovery time: when the device turns off it generates losses called recovery loss and the time required to recover is called the reverse recovery time. change of forward voltage and forward current can give the rd resistance value. mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 32 the average power losses in diode are when operated under pwm sine wave switching is given by eqn.(9). vii. simulation resultants and discussion the simulations were done using matlab simulink and toolbox, used for simulation of pvgenerator and psim software for simulation electrical circuits boost converter while modeling boost converter is provided by psim. fig.7. electric structure of the boost power converter the parameters have been used throughout the simulations, these are listed below: l = 3.5 mh. c1 = c2 = 5.6 mf. the switching frequency: fsw = 5 khz a. simulation of a central converter fig.8.the central converter. the figures show a simulation of the variables: the figures (9) show a variation of efficiency simulation of a power converter in relation with input power. fig.9.efficiency simulation of a power converter in relation with input power that the efficiency η increases rapidly with the power to reach a maximum yield of 80% -83 %. b. simulation of a string converter the converters are connected in series: η =80-83% η =85% gpv mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 33 the model of each converter is the same as the central converter, the two converters connected in series fig.10. simulation results of the string converter connected in series the figures show a simulation of the variables: pe (input power), ps (output power), η (efficiency), ve (input voltage), vs (output voltage), is (output currant), the fig. (11) show a variation of efficiency simulation of a power converter in relation with input power the model of each converter is the same as the central co inverter, the two converters connected in parallel. η =77% η =77% mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 34 fig.11. simulation results of the string converter connected in parallels damage on a single converter the efficiency is low because the effect of damage a single converter. mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 35 parallels the model of each converter is the same as the central converter, the two converters connected in parallel. fig.12. results the string converter connected in parallels fig.13.converter image with input power damage on a single converter if you destroy a converter the yield is low. v. conclusion in conclusion to paper, we are proposing different topologies system between central and distribution. the approach proposed in this paper a comparison study by simulation of these two approaches. the obtained results showed the efficacy of the proposed; in the centralized topology which divides the pv arrays into strings, a bigger division is taking place; and the pv group is directly divided in individual pv modules connected to a unique power a dc-dc converter. in string topology, each string is connected to a dc-dc converter. in the topologies, string benefits of the mppt control and the maximum power point tracking is carried out in more distributed way than the centralized architecture. thus, a failure in one of the string does not affect to the energy production of other strings and the pv power production is improved. nevertheless, the price and cost of the pv also depends on the choice of the architecture. for this reason, it is important to know different types of architecture in order to choose the correct pv architecture for each pv installation. the conclusion of the paper is presented a potential research idea for future work. this work was motivated by these issues and hopes to have contributed to their progression. the future work will be simulate the different architecture with series connection or parallel dc / dc and compare this result with experimental typical configurations. η =85% mouhoub birane et al ijeca-issn: 2543-3717. june 2019 page 36 references [1] m. boumboue, e. n. donatien "mathematical modeling and digital simulation of pv solar panel using matlab software " international journal of emerging technology and advanced engineering (issn 2250-2459, iso 9001:2008 certified journal, volume 3, issue 9, september 2013). [2] b.a alona, "new optimized electrical architectures of photovoltaic generators with high conversion efficiency" doctoral thesis, university of toulouse3 paul sabatier (ut3paulsabatier), france 2013. [3] d. picault, b. raison, s. bacha, "reducing mismatch losses in grid-connected residential bipv arrays using active power conversion components"eupvsec’10 conf. proceedings, pp.5141-5144.eupvsec’10 valencia, spain september 6-9, 2010. [4] m. amer. chabane, "adaptive photovoltaic configurations for decreasing the electrical mismatching losses"(2011). architectural engineering -dissertations and student research. paper 10. [5] b. burger, “extreme high efficiency pv-power converters”. european conference epe’09, 2009, pp. 113. [6] mh rashid. power electronics handbook. san diego, ca: academic press; 2007. [7] jp dunlop, “national joint apprenticeship and training committee for the electrical industry”. photovoltaic systems. orland park, ill.: american technical publishers, inc.; 2010. [8] gn tiwari, s. dubey, “fundamentals of photovoltaic modules and their applications”. cambridge: royal society of chemistry; 2010. [9] n dzung, b lehman, “an adaptive solar photovoltaic array using model-based reconfiguration algorithm. industrial electronics”, ieee transactions on. 2008; 55(7):2644-54. [10] p. assis sobreira, m. gradella villalva, p. gomes barbosa, h.a. carvalho, j.r. gazoli, e. ruppert, a.a. ferreira, "comparative analysis of current and maximum voltage‐controlled photovoltaic maximum power point tracking"; power electronics conference, cobep, brazil, 2011. [11] m birane, c larbes, a cheknane, “topologies modeling efficiency of dc / dc converter for ccm and dcm mode for applications of renewable energy systems”. international conférence on renewable energy icre 2012 15/16 avril 2012 université a. mira bejaia. [12] noman. rao, dinesh. chamund, "calculating power losses in an igbt module”, an6156-1 september 2014 ln31943. i. introduction v. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 2. 2017 page 06-14 ijeca-issn: 2543-3717. december 2017 page 6 modeling and parameter extraction of pv cell using singleand two-diode model b. benabdelkrim 1,2 , a. benatillah 2 1 department of material sciences, institute of science and technology, university of ahmed draia, adrar, algeria 2 laboratory of energy, environment and systems of information (leesi), university ahmed draia adrar, algeria benaekbouchra01@gmail.com abstract – photovoltaic modules operate under a large range of conditions. this combined with the fact that manufacturers provide electrical parameters at specific conditions (stc). the present study proposes a comparison between single and double diode models of solar pv system and ensures the best suited model under specific environmental condition for accurate performance prediction. an important feature of these models is that its parameters can be determined using data commonly provided by module manufacturers on their published datasheets. accurate determination of these parameters which arose from a diversification of models and methods dedicated to their estimations is still a challenge for researchers. in this paper the single and two diode models have been studied by mathematical methods based on simulated newton-raphson iteration method. newton-raphson iteration method is solved by matlab simulation. keywords: pv module; single-diode model; two diode model; performance i–v curves, parameter extraction received: 10/12/2017 – accepted: 25/12/2017 i. introduction the rapid growth of pv system utilizations is due to its availability everywhere which avoids transmission costs and losses, free, abundant and pollution free. silicon is the basic material required for the production of solar cells based crystalline or thin film technology. the photovoltaic (pv) modules are generally rated under standard test conditions (stc) with the solar radiation of 1000 w/m2, cell temperature of 25°c, and solar spectrum of 1.5 by the manufacturers. the parameters required for the input of the pv modules are relying on the meteorological conditions of the area. the climatic conditions are unpredictable due to the random nature of their occurrence. these uncertainties lead to either overor underestimation of energy yield from pv modules. an overestimation up to 40% was reported as compared to the rated power output of pv modules [1, 2]. the growing demand of photovoltaic technologies led to research in the various aspects of its components from cell technology to the modeling, size optimization, and system performance [3–5]. there are various pv cell modules studied by researchers in the literature. one of the simplest is single diode model. [6] in broad sense this model is derived by three parameters: short circuit current (isc), open circuit voltage (voc), and diode ideality factor (a). when the parameter series resistance (rs) is added in this model, the accuracy of model gets improved. one drawback of this model is that it is not capable of temperature (t) variation handling. parameter shunt resistance (rsh) significantly improves the model efficiency. [7] this model is having a drawback of reduced accuracy under low irradiance (g) level, especially at open circuit voltage (voc). additional diode design is added to the model for the recombination loss in the depletion region of the cell of solar module. [8] this is doublediode model. this model has more parameters to calculate. this model gives more accuracy because this model is more practical especially under low voltages. in this paper, a comparative analysis details the behavioral i-v characteristics of a single-diode using analytical four and five parameter model and twodiode model. the accuracy of the simulation results is verified by comparing it with published data provided by manufacturers of six pv modules of different types (mono-crystalline, poly-crystalline and thin-film). ii. mathematical models of pv module ii.1 single-diode model an electrical circuit with a single diode (single exponential) is considered as the equivalent mailto:benaekbouchra01@gmail.com b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 7 photovoltaic cell in the present article. two different models drawn from the equivalent electrical-circuit are studied: namely fourand five-parameter models. figure1. pv-cell equivalent-circuit models: single-diode model [9]. an output current equation of i-v characteristic using this model can be written as: . . . exp 1 0 v r i v r i s si i i pv v r t sh                         (1) where ipv photocurrent i0 cell saturation current rsh shunt resistance rs series resistance vt the thermal voltage (vt=a.ns.k.t/q) ns number of cells in series a ideal factor of the pv diode q electron charge (1.60281×10 -19 c) k boltzmann‟s constant=1.38066×10 -23 j/k t cell operating temperature ii.1.1 four-parameter model the four-parameter model studied in this work has been used elsewhere [10, 11]. assuming rsh as infinite and neglecting it in equation (1), the fourparameter model is obtained as follows: . . exp 1 0 v r i si i i pv v t               (2) the unknown parameters are denoted at stc as , , a 0 i i pvn n n and r sn ; where the “n” subscript refers to the reference operating conditions. the short circuit current can be found when v=0 i i scn pvn  (3) the following equations are used to calculate the other parameters at stc [10]. 2 3 .( ) . ocn v n n gi tn pvn n n v k t a ek v i t k t     (4) 0 exp 1 n ocn i pvn i v v tn          (5) .ln(1 ) v i mpn tn ocn mpn pvn mpn i v v i r sn     (6) where eg is the band gap of the material the parameters can be found at any other operating conditions by using following equations: ( ) pv pvn i n n g i i k t t g      (7) 3 . 1 1 exp 0 0 . q e t g i i n t a k t t n n                         (8) r r s sn  (9) . n n t a a t  (10) this model is implemented as follows: eqs. (3)–(6) are used to find values of the four parameters under reference conditions. these four parameters are corrected for environmental conditions using eqs. (7)–(10) and used in eq. (2), which relates cell current to cell voltage. from eq. (2) either cell current or voltage could be calculated provided that the other is known. alternatively, cell current and voltage could both be calculated at the maximum-power point. ii.1.2 five-parameter model as given in eq. (1), the five-parameter model is an implicit non-linear equation, which can be solved with a numerical iterative method such as newton raphson method [12]. however, this requires a close approximation of initial parameter values to attain convergence. alternatively, the parameters may be extracted by means of analytical methods. some of the analytical methods are studied elsewhere [12-15]. the five parameters ipv, io, rs, rsh, and m are calculated at a particular temperature and solarirradiance level from the limiting conditions of voc, isc, vmp, imp and using the following definitions of rso and rsho: 0 oc s v v dv r di    (11) 0 sc sh i i dv r di    (12) where rs0 and rsh0 are the reciprocals of the slopes at the open-circuit point and short-circuit point, respectively. the values of these resistances are not usually provided by module manufacturers. the other parameters are calculated as follows. the following equations are used to calculate the five parameters required. 0 . 1 i . exp 1s sc s pv sc sh t r i r i i r v                    (13) b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 8 0 .expoc oc sc sh t v v i i r v              (14) the value of the diode ideality factor (a) may be arbitrarily chosen. many authors discuss ways to estimate the correct value of this constant. usually, 1 ≤ a≤ 2 and the chosen value depend on other parameters of the i–v model. as it‟s given in [16], there are different opinions about the best way to choose (a). because (a) expresses the degree of ideality of the diode and it is totally empirical, any initial value of ( a) can be chosen in order to adjust the model. the rs and rsh resistances are calculated by iterative methods. the relation between rs and rsh, may be found by making the maximum power calculated by the i–v model, equal to the maximum experimental power from the datasheet (p max,m = pmax,e) at the (v m; im) point. in the iterative process, rs must be slowly incremented starting from rs = 0 and for every iteration, the value of rsh is calculated simultaneously: . . . exp 1 max, 0 max,e v r i v r i mp s mp mp s mp p v i i p m mp pv v r t sh                               (15) 0 0 exp oct s s t vv r r i v         (16) . . max, . exp 1 0 v r i mp s mp r sh v r i p mp s mp e i i pv v v t mp                 (17) the initial condition for the shunt resistance rsh can be found when considering the initial value of rs=0 [17, 18] sh,min mp oc mp sc mp mp v v v r i i i     (18) in the proposed iterative method, the series resistance must be slowly incremented starting from a null value. adjusting the i-v curve to match the cell reference condition requires finding the curve for several values of series and equivalent shunt resistances. the newton–raphson method was used in the proposed iterative method due to the ability to overcome undesired behaviors [19]. ii.2 two-diode model the two diode model (fig.2) equation of the i–v curve is expressed as [20]: . . . . exp 1 . exp 1 01 02 1 2 v r i v r i v r i s s si i i i pv v v r t t sh                                            (19) figure2. pv-cell equivalent-circuit models: two-diode model where the diode factors a1=1 and a2 can be derived from: 1 2 1 a a p   (20) where, p can be chosen greater than 2.2. the rest of parameters can be deduced from the following equations [20]: i i pv sc  (21)     01 02 1 2 . . . exp 1 . / p i oc v i k t sci i q v k t kt a a            (22) rs and rsh are calculated by iterative method, similar to the procedure proposed by [21], where the relation between rs and rsh is chosen to verify that the calculated maximum power is equal to the experimental one (p max,m =p max,e) at (vm, im) point. the rs value is found by a slow incrementation by the same manner as the above subsection. the expression of rsh can be written as: . . . max, . exp exp 2 01 . (p 1) . v r i mp s mp r sh v r i v r i p mp s mp mp s mp e i i q q pv k t k t v mp                           (23) iii. results and discussion the modeling methods described in this paper are validated by measured parameters of selected pv modules. the experimental (v,i) data are extracted from the manufacturer‟s datasheet. three different modules of different brands/ models are utilized for verification; these include the multiand mono crystalline as well as thin-film types. the specifications of these modules are summarized in table 1 b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 9 table1. specification of the pv modules modules isc (a) voc (v) imp (a) vmp (v) ki(isc) (ma/°c) kv(voc) (mv/°c) ns poly-cristallin kyocera kc200gt 8.21 32.9 7.61 26.3 3.18 -123 54 shell s70 4.5 21.2 4.12 17 2 -76 36 mono-cristallin shell sq150 4.8 43.4 4.4 34 1.4 -161 72 shell sp70 4.7 21.4 4.25 16.5 2 -76 36 thin-film shell st40 2.68 23.3 2.41 16.6 0.35 -100 36 pvl-136 5.1 46.2 4.1 33 5.1 -176 66 figures (3-5) shows the i-v curves for modules for different levels of irradiance and temperature. it can be seen that for varying irradiance, despite the modeling curves do not match experimental data in all points, the tow diode model strongly agrees to experimental data than the four-parameter and fiveparameter models for all types of modules, except for the thin-film (st40) module at low irradiance of about 200w/m² where the five-parameter modeled curve is closer to the experimental data than fourparameter and tow diode models. in the case of the varying temperature, g is kept constant at 1000 w/m 2 . it can be noted that all three methods show good general agreement with the experimental data. however, a close inspection reveals that the tow-diode model yields the most accurate results at all temperature. 0 5 10 15 20 25 0 1 2 3 4 5 6 voltage (v) c u rr e n t (a ) mono-cristallin sp70 i-v curve experimental data 4-p model 5-p model 2-diode model 600 w/m2 200 w/m2 1000w/m2 800 w/m2 400w/m2 0 5 10 15 20 25 0 1 2 3 4 5 6 mono-cristallin sp70 i-v curve voltage (v) c u rr e n t (a ) experimental data 4-p model 5-p model 2-diode model 60°c 40°c 20°c figure3. the i-v characteristics of sp70 module at varying irradiance and temperature. 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 8 9 10 voltage (v) c u rr e n t (a ) poly-cristallin kc200gt i-v curve experimental data 4-p model 5-p model 2-diode model 1000w/m2 800 w/m2 600 w/m2 400w/m2 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 8 9 10 voltage (v) c u rr e n t (a ) poly-cristallin kc200gt i-v curve 50°c 75°c 25°cexperimental data 4-p model 5-p model 2-diode model figure4. the i-v characteristics of kc200gt module at varying irradiance and temperature. b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 10 0 5 10 15 20 25 0 0.5 1 1.5 2 2.5 3 3.5 voltage (v) c u rr e n t (a ) thin-film st40 i-v curve experimental data 4-p model 5-p model 2-diode model 800 w/m2 1000w/m2 400w/m2 600w/m2 200w/m2 0 5 10 15 20 25 0 0.5 1 1.5 2 2.5 3 3.5 voltage (v) c u rr e n t (a ) thin-film st40 i-v curve experimental data 4-p model 5-p model 2-diode model 20°c 40°c 60°c figure5. the i-v characteristics of st40 module at varying irradiance and temperature. table 2-4 shows the parameters used for three models. four parameters are calculated namely, i0, ipv, ideality factor (a) and rs for the 4-p model. in the five parameter model, the additional calculated parameter is the shunt resistance; rsh. and the twodiode model has more variables, the actual number of parameters computed is four because i01=i02=i0 while a1=1 and p can be chosen arbitrarily, i.e. p  2.2. the two-diode model and the five parameter model exhibit similar results at stc. this is to be expected because both models use the similar max power matching algorithm to evaluate the model parameters at stc. however, at low irradiance, more accurate results are obtained from the two-diode model. table2.parameters extracted for the four parameter model poly-crystalline mono-crystalline thin-film module kc200gt s70 sp70 sq150-pc st40 pvl-136 ipv 8.2100 4.5000 4.7000 4.8000 2.6800 5.1000 a 1.0758 1.0177 1.0222 1.0594 1.3219 1.2573 rs 0.3541 0.4547 0.6310 1.0296 1.6156 2.3723 io 2.1954e-9 7.4460e-10 6.9528e-10 1.1570e-9 1.4202e-8 1.9783e-9 table3. parameters extracted for the five parameter model poly-crystalline mono-crystalline thin-film module kc200gt s70 sp70 sq150-pc st40 pvl-136 ipv 8.2146 4.5055 4.7150 4.8073 2.6961 5.2942 a 1.3000 1.3000 1.3000 1.3000 1.3000 1.3000 rs 0.2300 0.2200 0.4000 0.6700 1.5100 1.6800 rsh 601.3368 189.0262 133.1309 466.4639 266.5478 44.1667 io 9.8252e-8 9.9101e-8 8.7645e-8 6.9745e-8 1.0292e-8 4.0336e-9 table4. parameters extracted for the two-diode model poly-crystalline mono-crystalline thin-film module kc200gt s70 sp70 sq150-pc st40 pvl-136 ipv 8.2100 4.5000 4.7000 4.8000 2.6800 5.1000 a1 1 1 1 1 1 1 a2 1.2000 1.2000 1.2000 1.2000 1.2000 1.2000 rs 0.3300 0.3400 0.5100 0.9100 1.7100 1.9600 rsh 174.1551 119.5882 94.9643 275.2625 204.8492 54.2497 io1=io2 4.1280e-10 4.9996e-10 4.2065e-10 3.1059e-10 3.0748e-11 7.5012e-12 tables 5–8 show the relative errors for pmax, voc and isc at varying irradiance and temperature of sp70 and st40 modules. the relative error is defined as:    data data *100 calcul relative abs x x e x x        (24) the irradiance is maintained constant at stc. from the data it can be concluded, more accurate results are obtained from the two-diode model for the crystalline silicon technologies. b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 11 table5. relative errors of three models at different irradiances (t =25°c) for sp70 module. irradiance (w/m 2 ) parameters measured data 4-p model error % 5-p model error % 2d model error % 1000 pmax voc isc 70.07 21.33 4.682 70.5 21.39 4.7 0.61 0.28 0.38 70.11 21.35 4.7 0.057 0.094 0.38 70.22 21.34 4.675 0.21 0.047 0.15 800 pmax voc isc 56.13 21.03 3.752 57.61 21.18 3.76 2.64 0.71 0.21 55.95 21.07 3.76 0.32 0.19 0.21 56.38 21.13 3.74 0.45 0.48 0.32 600 pmax voc isc 41.89 20.5 2.815 43.96 20.91 2.82 4.94 2.00 0.18 41.46 20.72 2.82 1.026 1.073 0.18 41.99 20.84 2.805 0.24 1.66 0.36 400 pmax voc isc 27.53 19.92 1.882 29.62 20.53 1.88 7.59 3.06 0.11 26.76 20.19 1.88 2.79 4.92 0.11 27.12 20.43 1.87 1.49 2.56 0.64 200 pmax voc isc 13.17 19.12 0.9472 14.72 19.81 0.94 11.76 3.61 0.76 12.08 19.25 0.94 8.28 0.68 0.76 11.99 19.65 0.935 8.96 2.77 1.29 table6: relative errors of three models at different temperatures (e =1000 w/m 2 ) for sp70 module. temperature (°c) parameters measured data 4-p model error % 5-p model error % 2d model error % 20 pmax voc isc 71.54 21.71 4.743 72.23 21.77 4.69 0.96 0.28 1.12 71.76 21.70 4.69 0.31 0.046 1.12 71.82 21.70 4.665 0.39 0.046 1.64 40 pmax voc isc 64.77 20.18 4.736 65.29 20.26 4.73 0.80 0.39 0.13 65.15 20.25 4.73 0.59 0.35 0.13 65.38 20.24 4.705 0.94 0.29 0.65 60 pmax voc isc 57.94 18.71 4.743 58.34 18.69 4.77 0.69 0.11 0.57 58.54 18.68 4.77 1.036 0.16 0.57 58.86 18.67 4.745 1.59 0.21 0.042 table7. relative errors of three models at different irradiances (t =25°c) for st40 module. irradiance (w/m 2 ) parameters measured data 4-p model error % 5-p model error % 2d model error % 1000 pmax voc isc 40.21 23.29 2.677 40.03 23.30 2.68 0.45 0.04 0.11 39.99 23.27 2.68 0.55 0.086 0.11 40.04 23.26 2.658 |0.42 0.13 0.71 800 pmax voc isc 31.71 22.85 2.149 33.04 23.02 2.144 4.19 0.74 0.23 32.68 22.99 2.144 3.06 0.61 0.23 32.97 23.04 2.126 3.97 0.83 1.07 600 pmax voc isc 23.52 22.33 1.607 25.44 22.67 1.608 8.16 1.52 0.062 24.80 22.62 1.608 5.44 1.30 0.062 25.17 22.76 1.595 7.02 1.92 0.75 400 pmax voc isc 15.34 21.63 1.074 17.26 22.17 1.072 12.52 2.49 0.19 16.4 22.11 1.072 6.91 2.22 0.19 16.7 22.35 1.063 8.86 3.33 1.02 b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 12 200 pmax voc isc 6.967 20.28 0.537 8.611 21.33 0.536 23.59 5.18 0.19 7.615 21.17 0.536 9.30 4.39 0.19 7.655 21.61 0.5316 9.87 6.56 1.01 table8: relative errors of three models at different temperatures (e =1000 w/m 2 ) for st40 module. tempetaure (°c) parameters measured data 4-p model error % 5-p model error % 2d model error % 20 pmax voc isc 41.29 23.65 2.702 41.36 23.80 2.678 0.33 0.63 0.89 41.27 23.76 2.678 0.048 0.46 0.89 41.3 23.75 2.656 0.024 0.42 1.70 40 pmax voc isc 36.36 21.7 2.702 36.09 21.79 2.685 0.74 0.41 0.63 36.19 21.77 2.685 0.47 0.32 0.63 36.29 21.75 2.663 0.19 0.23 1.44 60 pmax voc isc 31.49 19.87 2.706 30.93 19.77 2.692 1.78 0.50 0.52 31.21 19.76 2.692 0.89 0.55 0.52 31.34 19.75 2.67 0.48 0.60 1.33 figure.6 and 8 shows the analysis for relative error of voc and the pmax for st40 module at different irradiance levels. as can be seen at stc irradiance, there is a very small difference in the voc values among the three models. however as the irradiance is reduced, there is a significant deviation of voc calculated using the 4-p, 5-p and two-diode models. similar results can be observed for the pmax. figure.7 shows the performance of the three models at different temperature for st40 module. there is no significant difference between three models for voc. however the four-parameter model exhibits poor performance for pmax calculations. figure.9 shows the performance of the three models at different temperature for sp70 module. we note that the two-diode model and the fiveparameter model are the least accurate at the three remarkable points at 60 °c compared to the fourparameter models. this is logical because the value of the ideality factor is assumed to be fixed in the fiveparameter model and the two-diode model and in the other hand the values of the recombination and diffusion saturation current are assumed to be equal in the two-diode model. 1 0 5 10 15 20 25 irradiance (w/m²) e r r o r r e la t iv e ( p m a x % ) st40(thin-film) 4-p model 5-p model 2d model 1000 800 600 400 200 1 0 1 2 3 4 5 6 7 irradiance (w/m²) e r r o r r e la t iv e ( v o c % ) st40(thin-film) 4-p model 5-p model 2d model 800 600 400 2001000 figure.6. relative error of pmax (a) and voc (b) at varying irradiance for st40 pv module b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 13 1 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 temperature (°c) e r r o r r e la t iv e ( p m a x % ) st40(thin-film) 604020 4-p model 5-p model 2d model 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 température (°c) e r r o r r e la t iv e ( v o c % ) st40(thin-film) 4-p model 5-p model 2d model 20 40 60 figure.7. relative error of pmax (a) and voc (b) at varying temperature for st40 pv module 1 0 2 4 6 8 10 12 irradiance (w/m²) r e la t iv e e r r o r ( p m a x % ) sp70 (mono-cristallin) 4-p model 5-p model 2d model 1000 800 600 400 200 1 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 irradiance (w/m²) r e la t iv e e r r o r ( v o c % ) sp70(mono-cristallin) 4-p model 5-p model 2d model 1000 800 600 400 200 figure.8. relative error of pmax (a) and voc (b) at varying irradiance for sp70 pv module 1 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 temperature (°c) r e la t iv e e r r o r ( p m a x % ) sp70 (mono-cristallin) 4-p model 5-p model 2d model 20 40 60 1 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 température (°c) r e la t iv e e r r o r ( v o c % ) sp70 (mono-cristallin) 4-p model 5-p model 2d model 20 40 60 figure.9. relative error of pmax (a) and voc (b) at varying temperature for sp70 pv module iv. conclusion the present paper has proposed the comparison between the four-parameter, five-parameter and towdiode models. these models used to predict the electrical response of illuminated six pv modules for various operating conditions. the accuracy of the three models is evaluated using practical data from manufacturers of different types of pv modules. its performances are compared with the experimental values given by the constructors. it has been found that, the tow-diode model is better when subjected to variations in irradiance and temperature. and gives better accuracy for reconstructing the electrical characteristics of mono-crystalline and poly-crystalline pv modules, but for thin-film pv module the five parameter model is closer to the experimental data at the low irradiance. references [1] w. durisch, d. tille, a. worz, and w. plapp, “characterisation ¨ of photovoltaic generators,” applied energy, vol. 65, no. 1–4, 2000, pp. 273–284. [2] a. q. jakhrani, a. k. othman, a. r. h. rigit, s. r. samo, and s. r. kamboh, “a novel analytical model b. benabdelkrim et al. ijeca-issn: 2543-3717. december 2017 page 14 for optimal sizing of standalone photovoltaic systems,” energy, vol. 46, no. 1,2012, pp. 675– 682. [3] a. n. celik, “a simplifed model based on clearness index for estimating yearly performance of hybrid pv energy systems,” progress in photovoltaics: research and applications, vol. 10, no. 8, 2002, pp. 545–554. [4] a. h. fanney and b. p. dougherty, “building integrated photovoltaic test facility,” journal of solar energy engineering, vol. 123, no. 3, 2001, pp. 194– 199. [5] m. a. green, “short communication: price/efciency correlations for 2004 photovoltaic modules,” progress in photovoltaics: research and applications, vol. 13, 2005, pp. 85–87. [6] glass m. c., „improved solar array power point model with spice realization of generalized‟, iecec, vol. 1,1996, pp. 286-291. [7] kajihara a and harakawa a. t., „model of photovoltaic cell circuits under partial shading‟, icit, 2005, pp. 866-870. [8] tan y. t., kirschen d. s., and jenkins n., „a model of pv generation suitable for stability analysis‟, ieee trans. energy converts, vol. 19, no. 4, 2004, pp. 748755. [9] a. chatterjee, a. keyhani, and d. kapoor, "identification of photovoltaic source models," energy conversion, ieee transactions on, vol. pp, 2011, pp1-7. [10] celik, a. n. and acikgoz, n. “modelling and experimental verification of the operating current of mono-crystalline photovoltaic modules using fourand five-parameter models”, applied energy, 84, 2007, pp 1–15. [11] arab, a. h., chenlo, f., benghanem, m.,. “lossofload probability of photovoltaic water pumping systems”, solar energy, 76, 2004, pp713–723. [12] phang jch, chan dsh, philips jr. accurate analytical method for the extraction of solar-cell model parameters. electron letters, 20, 1984, pp406–408. [13] blas ma, torres jl, prieto e, garcia a. selecting a suitable model for characterizing photovoltaic devices. renewable energy, 25, 2002, pp371–380. [14] kou q, klein a, beckman wa. a method for estimating the long-term performance of directcoupled pv pumping systems. solar energy, 64, 1998, pp 33–40. [15] chenlo f, fabero f, alonso mc. testing, norms, reliability and harmonization: a comparative study between indoor and outdoor measurement. agencia eurec, joule. jouii-ct92-0178, brussels: european commission, 1996. [16] marcelo g. villalva, jonas r. gazoli, and ernesto r. filho, "comprehensive approach to modeling and simulation of photovoltaic arrays ", ieee transactions on power electronics, 24, 2009, pp 1198 1208. [17] villalva, m.g., gazoli, j.r., filho, e.r. comprehensive approach to modeling and simulation of photovoltaic arrays. ieee trans. power electron. 24, 2009, pp1198–1208 [18] ishaque, k., salam, z., taheri, h., shamsudin, a. a critical evaluation of ea computational methods for photovoltaic cell parameter extraction based on two diode model. sol. energy, 85, 2011, pp 1768–1779. [19] walker, g.r.: evaluating mppt topologies using a matlab pv model. journal of electrical & electronics engineering, 21, 2001, pp 49-56. [20] ishaque, k., salam, z., taheri, h. simple, fast and accurate two diode model for photovoltaic modules. sol. energy mater. sol. cells, 95 (2), 2011a, pp 586– 594. [21] villalva, m.g., gazoli, j.r., filho, e.r. comprehensive approach to modeling and simulation of photovoltaic arrays. ieee trans. power electron. 24, 2009, pp 1198–1208. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 2. 2018 page 01-05 ijeca-issn: 2543-3717. december 2018 page 1 cfd simulation of natural convection and heat transfer in a flat solar thermal collector with fins on the glazing horizontal case laaraba adel 1department of physics, university of batna. (05000) batna, algeria laaraba_adel@yahoo.fr abstract – this study is based on a cfd simulation of a flat horizontal solar thermal collector containing fins on its inner face of the glazing. the walls of the solar collector with insulation are considered adiabatic and the rest of the walls are at constant different temperatures. the principal objective of this work is to study the effects of the number of fins that changed from 0 to 30, as well as their length varied from 0 to 0.8 on the air flow and heat transfer characteristics. it has been observed that the heat transfer rate is strongly affected by the number of fins and the length of the fins. the obtained result showed that the increase of the fins reduces the heat loss by convection by 54 %. keywords: partitions number, fin, cfd, solar collector, natural convection received: 19/09/2018 – accepted: 06/12/2018 i. introduction algeria is a country that has a large capacity solar energy. solar energy systems can work without problems in the sunny areas of southern algeria [1]. these solar devices are based on solar rays and they are influenced by the intensity of solar radiation. thus, the efficiency of solar devices changes with the seasons [2]. transparent glazing plays a big role in solar devices such as solar collectors, solar distillers and solar heating. double glazing for example increases the efficiency of the solar collector while it decreases the efficiency in the solar still [3, 4]. the use of the fins on the glazing has a great influence on the yield of the solar device [5]. the number of partitions on the glazing shows a reduction in heat loss [6]. the location of the fins on the inner face of the glazing and their length lp in a divided rectangular cavity, have been studied in the case of natural convection coupled with radiation [7]. still in the case of natural convection, the effect of the high location of the partition on the warm wall a heated square enclosure has been studied [8, 9]. a study was based on the effect of thickness and thermal conductivity fins [10]. this simulation work is based on studying the influence of the number and length of fins on the performance of a solar thermal collector in a horizontal position. ii. problem description the geometry studied is a two-dimensional rectangular cavity containing fins glued to the inner glazing of the solar collector. figure 1 shows a sketch of the problem under consideration, the dimensionless length of partitions lp. it is considered that the solar collector is placed horizontally perpendicular to the field of gravity and the temperature gradient. figure 1. schematic representation of the problem ii.1 boundary conditions the horizontal walls (glazing and absorber) are maintained at different temperatures, and the vertical walls are thermally insulated. that is, -horizontal wall (absorber): ht t -horizontal wall (glazing): c t t laaraba adel ijeca-issn: 2543-3717. december 2018 page 2 q n u t   vertical walls (insulation): 0 t x    no-slip conditions on all walls: u=v=0 the following assumptions are made to simplify the problem.  the flow is steady, laminar and two-dimensional.  the fluid is newtonian and incompressible.  work induced by the viscous forces and pressure is negligible.  the physical properties of the fluid (air) are considered constant except for its density which obeys the boussines approximation in terms of buoyancy. therefore: (1) the power density dissipated is negligible. iii. the mathematical formulation the governing equations considering the abovementioned assumptions are given below: continuity equation (2) xmomentum equation (3) y-momentum equation 2 2 02 2 1 ( ) ( ) v v p v v u v g t t x y y x y                     (4) energy equation (5) the average nusselt number which is employed to evaluate the effect of studied parameters on the heat transfer rate is calculated as: (6) the governing equations with relevant boundary conditions are solved by a commercial cfd code (ansys fluent). simpler algorithm is used to couple velocity and pressure. convective terms in the governing equations are discretized by second order upwind difference scheme. iii.1 verification of the numerical procedure based on the comparisons of average nusselt number obtained in the present study and taken from the literature, which is given in table 1, one finds that the obtained results are similar and in agreement with those presented by different authors with a percentage of acceptable error. that is, the comparison presents an excellent concordance, which confirms that the procedure can be used for the further numerical simulation in this work. table1 nusselt number comparison with the references values. ra present work ref. [11] ref. [12] 103 1.116 1.118 1.118 105 4.549 4.545 4.523 iv. results and discussions in this work the studied phenomenon is the natural convection in a partitioned rectangular cavity. the bottom wall (the absorber) is made of aluminum, and the outer wall (the glazing) is ordinary glass. the cavity (the gap of the thermal solar collector) contains the air. the objective is to study the influence of number and length of partitions on the heat transfer in the cavity. the simulations are performed for ra=2.51x10 4 and pr=0.71. the results obtained are presented in the form of isotherms, streamlines and average nusselt numbers. to ensure that the accuracy of the results are independent from the mesh, calculations are conducted for several different structured meshes. the monitored parameter, average nusselt number for different meshes is presented in table 2. table 2 average nusselt number for different meshes. mesh 20400 30600 40800 501000 nu 73.16 74.87 75.34 75.40 as seen in table 2, the variation in average nusselt is not significant between the meshes 40800 and 501000. thus, the former mesh is chosen to save computational time. the obtained results are presented below:   0 01 t t     2 2 2 2 1 ( ) u u p u u u v x y x x y                  0 u v x y       2 2 2 2 ( ) t t t t u v x y x y             laaraba adel ijeca-issn: 2543-3717. december 2018 page 3 iv.1 effect of partition length lp  the dynamic field the influence of partition length on the flow and heat transfer characteristics is discussed below. the partition length is varied from 0 to 0.8 while the number of partitions is kept constant at 5. fig. 2, demonstrates the streamlines for lp=0.0 to 0.8. as can be seen from the figure, for all the cases rolling cells are established in the enclosure. as the partition length increases, the fluid velocity decreases which consequently reduces flow circulation intensity. v (m/s) lp= 0 lp= 0.2 lp= 0.6 lp= 0.8 figure 2. streamlines for different partition length values (ra=2.51.104, n=5)  the thermal field figure 3, shows the isotherms for different values of lp and 5 partitions. it note that there is a variation in the distribution of the temperatures in the air gap, when the increases of the length of partitions, which means the influence of lp on the thermal transfer by natural convection in the air gap, therefore it is concluded that in the case horizontally the increase in the length of partitions cause a variation of thermal transfer by natural convection therefore a variation of thermal losses toward the outside. the movement of the fluid is forced to be close to the absorber. the isotherms are presented in the figures below: lp= 0 lp= 02 lp= 0.4 t(k) lp=0.6 lp= 0.8 figure 3. isotherms for different values of lp for ra= 2.51.104, n=5.  the average number nusselt figure 7 shows the variation in the number of average nusselt depending on the length of partitions lp, for a number of partitions equal to 5. we note a gradual decrease in the value of the the nusselt number when the length of partitions increases, which means a decrease of the thermal losses by natural convection to the outside ra=2.51.10 4 , n=5. figure 4. variation in the number of average nusselt for different values of lp. iv.2 effect of the number of partitions  the dynamic field the dynamic field in the form of streamlines and velocity vectors: figure 5, shows the streamlines for different numbers of partitions for a length of 0.4. we note that the movement of the air is close to the absorber below the partitions and form of waves when there is an increase in the number of partitions, which means an impediment of convective movements of the air in the air gap, this impediment cause a reduction of losses convective. it is observed that the reduction is at a maximum when n=30. laaraba adel ijeca-issn: 2543-3717. december 2018 page 4 v (m/s) n=0 n=20 n=10 n=30 figure.5. streamlines and velocity vectors for different values of the number of partitions n, for ra=2.51.10 4 , lp=0.4.  the thermal field the thermal field is presented in the form of the isotherms: figure 6, shows the isotherms for different numbers of partitions, in order to study the influence of the number of partitions. it has set their length to lp=0.4, and there has varied their number from 0 to 30. we note in this figure that the increase in the number of partitions cause a variation in the distribution of the temperatures in the air gap of the solar collector, therefore an influence on the performance of the solar collector. n=0 n= 10 n= 20 t(k) n= 30 figure.6. isotherms for different values of the number of partitions n for ra=2.51.10 4 , lp=0.4.  the average nusselt number variation in the values of the average nusselt number is represented in the figure below: 0 5 1 0 1 5 2 0 2 5 3 0 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 n u n n um o y figure.7. variation in the number of average nusselt for different numbers of partitions does for ra= 2.51.10 4 . figure7 represents the variation in the number of average nusselt with the number of partitions n. it note that the decrease in the values of this last when the number of partitions increases, it is concluded that the increase in n cause a minimization of convective losses. v. conclusion in this study it indicate that the addition of partitions to the glazing wall can enhance the efficiency of the flat plat thermal solar collector with reduce of thermal losses by natural convection with 54%. the effect of number and length of partitions is studied numerically. according to the previous results, it can be concluded that:  the presence of partitions causes a decrease in the value of average nusselt, therefore a minimization of thermal losses to the ambient.  the increase in the length of the partitions cause a diminution the flow exchanged by convection, a maximum decrease for lp=0.8.  the increase in the number of partitions causes a decrease in the value of average nusselt, and therefore a minimization of thermal losses toward the outside, by the impediment of convective movements of the air, a maximum decrease for n=30.  the increase in the number of partitions causes a lowering of the rollers to the bottom near the absorber, and dons an impediment of convective movements of the air. . nomenclature gr: grashof number l: length of the thermal collector (m). lp: dimensionless length of partitions n: number of partitions greek symbols α: thermal diffusivity(m 2 /s) λ : thermal conductivity(w/m. k) laaraba adel ijeca-issn: 2543-3717. december 2018 page 5 nu: nusselt number pr: prandtl number ra: rayleigh number re: reynolds number tp: temperature of absorber (k) x, y : cartesian coordinates (m) u, v : velocity components (m/s) ν: kinematic viscosity(m 2 /s) β: coefficient of volume dilatation(k -1 )  :density(kg/m3) 0  : reference density (kg/m 3 ) acknowledgment i would like to thank dr müslüm arıcı from kocaeli university -turkey, for his help and for his valuable remarks. references [1] s. pahlavana, m. jahangirib, a. shamsabadic, a. khechekhouche. feasibility study of solar water heaters in algeria, a review. journal of solar energy research. vol 3, no 2, 2018, pp 135-146. [2] a. khechekhouche, a. boukhari, z. driss, n. benhissen. seasonal effect on solar distillation in the el-oued region of south-east algeria. international journal of energetica. vol 2. no 1. 2017, pp 42-45. [3] h. vettrivel, palanivel mathiazhagan. comparison study of solar flat plate collector with single and double glazing systems. international journal of renewable energy research. vol 7, no 1, 2017, pp 267-274. [4] abderrahmane khechekhouche, boubaker benhaoua, zied driss. solar distillation between a simple and doubleglazing. recueil de mécanique. vol 2, no 2, 2017, pp 145-150. [5] adel laaraba, abderrahmane khechekhouche. numerical simulation of natural convection in the air gap of a vertical flat plat thermal solar collector with partitions attached to its glazing. indonesian journal of science & technology. vol 3, no 2, 2018, pp .14-23. [6] ahmed. m. s. amraqui, c. abid. combined natural convection and surface radiation in solar collector equipped with partitions. applied solar energy. vol 47, 2011, pp. 36-47. [7] bahlaoui and al. numerical study of mixed convection coupled with radiation in a vented partitioned enclosure. international scientific journal for alternative energy and ecology. vol 6, no 62, 2008. [8] paweena khansila et al. numerical study of natural convection in porous square enclosure non-uniformly heated from the partitions. international journal of pure and applied mathematics. vol. 96. no 2, 2014, pp. 2013228. [9] a. haghighi and k. vafai. optimal positioning of strips for heat transfer reduction within an enclosure. numerical heat transfer. vol. part a, 66, 2014, pp. 17-40. [10] mehdi khatamifara et al. conjugate natural convection heat transfer in a partitioned differentially-heated square cavity. international communications in heat and mass transfer, 2016, pp. 12. [11] s. amraqui. modeling of thermal transfers paired in a thermal solar collector cells with anti-losses. doctorate thesis, 2009. [12] g. de. vahl. davis. natural convection of air in a square cavity: a bench mark numerical solution. int. j. for numerical methods in fluids. vol. 3, 1983, pp. 249-264. i. introduction ii. problem description iv. results and discussions v. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 24-30 ijeca-issn: 2543-3717. june 2018 page 24 impact of fuel energy prices in tunisia lassaad jebali 1 , anis kacem 2 1 university of tunis, isg of tunis and lieri (fsegt), tunisa 2 the international academy of governance, tunisa lassaad.jebali@gmail.com abstract – the policy of subsidizing petroleum derivatives in tunisia distorts the real prices of goods and services. it does not take care on environment. there is no serious fiscal policies to reduce pollution generated by energy products. the calculation of the correlation matrix between different macroeconomic aggregates does not give a negative effect of oil prices on national gdp. however, this result is serious, because the impact on economic (performance) is hidden, affecting first the general level of prices, unemployment and inflation. instability of oil prices has no apparent impact. this fact and instability make many difficulties to manage prices and inflation after revolution. impact on gdp passes through economic vulnerability indicator (evi) and agricultural sector. keywords: upward oil price days, tunisian gdp, hidden impact, curve shifts, evi received: 28/03/2018 – accepted: 30/05/2018 i. introduction a large number of studies have investigated the direct and hidden impact of oil prices on economies. most studies have adopted var models to capture crud price impact on groups of countries. these researches have been able to calculate the effects of energy through elasticities. however, a (reduced) number of studies have calculated the hidden effects of fuel volatility with subsidy policies without consideration of negative externalities on environment this paper tries to capture the effects of crude oil price volatility on an economy that subsidizes petroleum derivatives and has not a clear environmental policy. we try to answer the following question: what are the (direct) and hidden impacts of oil volatility on the tunisian economy? tunisia produces, export crude oil and import petroleum derivatives (diesel, gasoline, kerosene). oil shocks and price increases in the world market. it has impacts on the macroeconomic aggregates of tunisia and on the tunisian social welfare. these impacts are indirect for the tunisian case. indeed, in this paper, we show that the number of days in which the price of crude increases has not a negative effect on the national gdp and the correlation is low and positive. however, the effect of fuel prices is significant on the other macroeconomic aggregates as inflation. the high volatility of fuel prices makes the tunisian economy more vulnerable through the agricultural sector. we explain this idea by introducing the variable evi that measures the vulnerability of the tunisian economy. this paper aims to detect the hidden and apparent effects of energy on the tunisian economy given the institutional change of 2011 and the political change. we organize this into five sections: with the first one, we develop the concept of oil shocks via the supply and demand curves shifts. second, we analyze economic growth and oil shocks. the third section develops the welfare hidden impact of oil prices. forth, we give attention to the macroeconomic transmission channels of oil price shocks. in the last section we analyses the case study of tunisia and we conclude. ii. oil shocks: the supply and demand curves shifts we can define an oil shock by a large modification in oil prices, in the international market, and the supply. these variations may occur slowly and gradually or abruptly and unexpectedly. petroleum, as a substantial source of energy, affects energy prices directly. when the price of the crude increases in the world market, energy prices rise and vice versa, even with subsides policies. moreover, when the price of oil increases, the demand for other sources of energy indirectly increase; in such a case, the price of other competitor sources which would be supplied as a new source of energy, will rise. consequently, an oil price shock is more generally an energy and agricultural sector price shock, and an energy and agricultural crisis are directly influenced by an oil crisis. mailto:lassaad.jebali@gmail.com l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 25 three oil shocks or energy shocks occurred in 1973 and in 1990 (iraq and nato war). as it is clear, the reason for these three main oil shocks was supply disruption. the oil price shocks of the 1970s can be explained by pure supply factors, but starting from the 1980s oil price increasingly began to come under another pressure from its demand side. it accelerated from about us$35/barrel in 1981 to beyond us$120/barrel in 2013. at the same time federal interest rates decreased from 16.7 percent per year to about 0.1 percent. taghizadeh and yoshino (2015) explain how this long-term price increase was, in most cases, caused by expansionary monetary policies that heightened oil prices through interest rate channels, and so the change rate. for the case of developing country, inflation has an energy dimension (imported inflation) according to banking interest rates. aggressive monetary policies stimulated oil demand and blew up the oil price. consequently there will be slower economic growth. this means that there are also many demand factors that affect consumption of oil. this idea can be more expressed using the aggregate supply and demand model, which explains economic fluctuations in the short run. we can show, via the aggregate and supply curve, that an oil shock do not cause only shift on the supply curve but on the demand curve simultaneously. consequently, production and the general level of price will change. we can explicit this idea as follows: if an oil price shock shifts the general level of prices by increasing production costs, it decreases the components of total demand such as real national consumption, real investment expenditure, real government expenditure, and the real transport cost of exports and imports. therefore, the real value of national expenditure decreases du to inflation. if the relative increase in the imported oil price exceeds the relative rise of exported goods, then a deficit will occur in the trade balance or the net exports of a country(x-m). consequently, the federal real gained income of energy consumers will fall. therefore, their demand for goods and services decreases. such a decrease in demand will cause the demand curve to fall. this occurs mostly in industrial countries, which happen to also be the major importers of oil. the final result can be: a reduction on the production or the gdp, with a price level that can be the same as initially (before the oil shock) or lower, if we suppose a passive, or no change, in the monetary and fiscal policies) iii. economic growth and oil shocks in addition to labor and capital, energy is also considered as factor of production. therefore, production would be a function of labor, capital and energy. (1) where, q measure the gdp, k measure the stock of capital, l the stock of labor, and the stock for energy is e. therefore, any change on the quantity of labor, capital or energy leads to the alteration of levels of production. furthermore, there are direct relationships between the use of such elements and the level of production. in other words, a rise (decrease) of each of the foregoing elements leads to an increase (decrease) in production. in the above function, a positive variation of: k, l and e leads to a positive modification of q. in addition, utilization of energy from different sources such as oil, gas, coal and electricity, is itself a reverse function of the price level of energy sources. in other words, an increase in energy prices lead to a fall in energy as input in the production function, which in turn results in a decrease in production. with, for oil price, for gas price, for coal price and for electric price. energy considered as a factor of production that has a down turn demand curve relatively to price of energy. consequently, partial derivative between e and each price is negative. an increase in oil price may lead to the substitution of oil by other sources of energy. therefore, as it is a production factor, it will have short-term effects on the increase of production costs and will lead to the reduction of real production of oil importer countries. in the long run too, it leads to a rise in costs; the rate of which will depend on the ability of other sources to replace oil. if ability to substitute exists, such price increases will have no important effect on costs. to show the primary and secondary effects of alteration of energy prices, we can deduct energy costs from gross product to determine net product as follows: the net product is y and e is the amount of energy used to monetary product q and represent price index of energy. iv. welfare hidden impact of oil prices the bulk of petroleum is consumed indirectly through household consumption of other goods and services that use petroleum products as inputs. therefore, the welfare effect of higher oil prices and lower subsidies on household real incomes is as two form: direct effect of higher prices for petroleum products consumed by households indirect effect arising from higher prices for other goods and services, using energy or petroleum as input in their production process. so, these higher prices will be passed indirectly to households. calculating the direct effect or hidden effect, and how it is distributed across income groups, essentially requires information on the level of direct consumption of various petroleum products (gasoline, diesel, and liquefied petroleum gas) or the budget share expenditure of households across the national income distribution. the main source of information is typically a household survey containing expenditures by each household on individual oil products. a “first-order” measures the direct real income effect of oil price and can be calculated l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 26 as follows: for each household we calculate the budget share of fuel expenditure items, i.e., fuel expenditures divided by total household consumption. multiplying budget shares by the percentage increase in price due to the increase in fuel prices gives a first-order estimate of the real income effect of the price rise, which assumes that fuel consumption stays fixed. we assume that there is a total pass-through of pricing. this means, that the increase of energy prices on the supply cost are directly transmitted to consumers and there is no subsidies from the government. this overestimates the real income effect since, in practice, households can reduce this impact by substituting away from fuel. the incidence of the real-income effect can be analyzed by examining how the magnitude of the effect varies across the income distribution. typically, household per capita consumption, possibly adjusted for family composition, is taken as the best proxy of household welfare. we can then analyze the hidden incidence of the real income effect by calculating the average percentage real income loss. if the percentage real income loss is higher (lower) for low-income households, then the incidence is said to be regressive (progressive). recent studies showed that the greatest budget share of the poorest households are devoted for fuel. therefore, the increase of price of this type of energy, has a great impact on poor households. put differently, the budget share gives a first-order approximation of the welfare impact of price change, or the amount of money required to maintain unchanged the utility level of the household. for a given product, the share of spending on that product in total expenditure corresponds to the price elasticity of real income or total spending assuming the volume of demand constant. put differently, the budget share gives a first-order approximation of the welfare impact of price change, or the amount of money required to maintain unchanged the utility level of the household. where y is the level of income or expenditure, is the share of spending on good i in total expenditure and, is the price of good i. for instance, if diesel account for 10 percent of total spending of a household, the direct effect of a 10 percent increase in diesel price would be a 1 percent decline in household real income or a corresponding increase in household real expenditure. since households can consume energy products or goods as gasoline, fuel, diesel, the overall direct effect is the sum of the direct effect associated with each fuel product. where m is the total number of goods directly depend to energy products (gasoline, fuel, diesel). identifying the magnitude of the hidden indirect effect requires an estimate of the effect of higher fuel costs on the prices of other goods and services consumed by households. these price effects can be estimated using an input-output table of the economy showing the energy intensity of each sector and a simple model of the effect of higher fuel costs on prices. as with the direct effect, the indirect real-income effect can be calculated by multiplying the budget shares of the various goods and services by the estimated percentage price increases in these sectors. the incidence of the indirect effect can be determined by estimating the effect separately for households across the national income distribution. we have n-m as the number of non-fuel products. with n is the number of goods produced using energy as inputs. the total real income effect is calculated as the sum of the direct and indirect real income effects, and the incidence can also be determined by calculating the average effect for households in different parts of the income distribution. in practice, reflecting the high proportion of fuel consumed in the production and distribution of goods and services, the indirect effect accounts for over half of the total effect. v. macroeconomic transmission channels of oil price shocks the several researchers have supported the view that the countries with stronger trade relationships have similar business cycles. for instance, we can state that the shocks that occur in one country can be transmitted to all sectors in that country spatially to agricultural sector. in addition, oil price shocks can be transmitted to another country if they have intensive trade linkages. according to the reference [15] the hidden effects of oil price were significant at the case of integrated countries. the results of the study suggested that, it is quite advantageous for the industrial countries to trade with the developing countries, due to the high growth capacity of developing countries. on the other hand, the developing economies gain from trading with the industrial countries because of the higher relative income levels in the industrial countries. to explain our idea, we present the study by tilak abeysinghe and kristin forbes (2005) that used a structural var model and 11 asian countries, also confirmed the fact that trade linkages is very significant aspect in case of transmitting the effects of shocks occurred in one country to its main trading partners. for developing countries in which agricultural sector has a great part of the national gdp (gross domestic product), oil price shocks are directly and indirectly transmitted to social welfare through agricultural goods. oil price changes are almost generally accepted as a significant factor that affects different economies of oilexporting and oil-importing countries. according to the study by weiqi tang, libo wu and zhong xiang zhang (2009) there are several channels through which oil prices l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 27 affect an economy and macroeconomic variables: interest rate, output and investment. according to the theory oil prices affect the macroeconomic variables through these six transmission channels: 1) supply-side shock effect; 2) inflation effect; 3) real balance effect; 4) the unexpected (uncertainty) effect. supply-side shock effect – from this perspective oil is described as direct input of production process. when local and national oil price increases it automatically affects the output through the rising production costs. consequently, a lower productivity decreases the total output and increases the unemployment. this transmission process scenario is typical for an oilimporting country. for an oil-exporting economy higher revenues as a result of the oil price shocks can contribute the increases in investment opportunities, which will boost the output and decrease the unemployment. inflation effect – oil price shocks also trigger the inflation in economy. the prices of agricultural goods will increase. as it was mentioned, oil price shocks increase the costs of production, which is considered as a price shock therefore. for developing countries, oil prices shocks make the economy more vulnerable due to the great part agricultural sector. this vulnerability calculated according to evi indicator 1 . real balance effect – through this transmission channel, an oil price shock impacts money demand. as an example, consumers tend to borrow and not to save, it increases the interest rates and decreases the demand for cash. the unexpected (uncertainty) effect – the investment demand of both consumers and producers is affected through the uncertainty channel of an oil price shock. the future investment plans can be postponed if people do not know if the oil prices will go up or down. after that, the uncertainty causes the investment demand to decrease. vi. hidden impact of oil price volatilities: the case of tunisia in this section, we resume a limited works done on the effects of oil price shocks on oil importing and oil dependent economies such tunisia. the most important and significant research related to the effects of oil price shocks on economic activity and macroeconomic variables was done through the example of the us by [12]. in his papers, they showed that there is a strong relationship between oil price changes and economic growth of 11 asian and oecd countries. in other words, an essential negative correlation between the oil price increases and the economic recessions in some countries was determined. another not less significant aspect of oil price increases is that oil supply interruptions is a good prediction tool for gdp decrease, hence, it can cause the economic slowdowns. however, after the later research by [7], it was stated that there was a negative correlation in the case of oil price decreases and national gdp for the united states of america case. another interesting [9] studied the correlation path between the oil price shocks and economic growth during the period of 1982-2008 in greece, which is a highly oil dependent country. accordiong this study, the oil consumption was 64% of the total energy consumption in greece in 2006. a statistic approach with time series equation were used to examine the relationship and possible asymmetries between oil prices and economic activity. the results stated that more than 3% month to month increases in oil prices and oil price volatility more than 2.4% during a year negatively affect the economic activity in greece. vii. statistical approach and database to start the statistical development of direct and indirect impact on economy let us see the tendencies of oil prices over time from the 90 th to 2015. next graphic (figure 1) shows this evolution: figure 1. annual modification of crude oil prices was done day by day from 1987 to 2017. thus, if we measure the daily growth rate of oil prices, and the number of positive and negative growth each year, we can represent figure 2’ as follow: figure 1. the number of positive and negative growth each year l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 28 with ncrud_plus is the number of days in which we have growth of oil prices, and ncrud_ is the number of days in which we have negative growth oil prices. the net result of the number of modification days is positive. the number of days in which we have growth of oil prices is more than the number of days with negative growth. figure 1’’ shows this result: figure 1. the number of days in which we have growth of oil prices is more than the number of days with negative growth according to tunisian indicators: annual gdp in national currency converted to u.s. dollars and annual real growth rate, we can represent figure 2 and figure 3 using ins database. figure 2. annual gdp in national currency converted to u.s. dollars and annual real growth rate figure 3. annual gdp in national currency converted to u.s. dollars and annual real growth rate using ins database. using descriptive analysis we cannot easily see that there is direct and significant dependence between the tendency of oil prices and growth rates of national gdp in tunisia. we add that tunisia is one of developing countries which subsidies energy products. therefore, oil or energy choc are not transmitted directly to domestic prices. however, the choc is transmitted via a more budget deficit. in addition, we can represent figure 4 in order to explain how tunisian gdp vary according to petroleum prices. in figure 4, we represent the tendency of tunisian national investment per gdp (nid_ngdp 2 ) and national saving over time. we can see that there is a gap from 2010 until now between nid_ngdp and (national domestic saving per gdp) ngsd_ngdp. figure 4. the tendency of tunisian national investment per gdp (nid_ngdp) and national saving over time l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 29 in order to detect the direct and indirect effects of oil prices on the social welfare, we adopt a descriptive statistical method and the estimation of time series equations. this method differs from the approaches of imf studies using a-theoretical approaches under var models. our approach differs radically from imf studies that aim to detect impacts through var modeling because in tunisia the price system does not reflect production costs due to the fuel subsidy policy. tunisia is the start point of the arab spring. there has been a restructuring of the institutional and political system from a presidential regime to another hybrid regime supported by the international financial institutions including the imf. the latter institution has encouraged all policies to reduce petroleum subsidies adopted by governments. consequently, the tunisian government has adopted a policy of automatic correction of fuel prices. the database used is world bank data and international energy statistics (ies) during the period 1980-2020. the values of 2017, 2018, 2019 and 2020 are estimates by the world bank. missing data are estimated by moving average. we introduce in this paper the variable evi, which measures economic vulnerability according to the ferdi database. the evi is the simple arithmetic average of 2 sub-indexes 3 : the exposure sub-index, which is a weighted average of 5 component indexes: population size (25%), remoteness from world markets (25%), exports concentration (12.5%), share of agriculture, forestry and fishery in gdp (12.5%) and the share of population living in low elevated coastal zone (25%). the shocks sub-index, which is a weighted average of 3 component indexes: the victims of natural disasters (25%), the instability in the agricultural production (25%), and the instability in exports of goods and services (50%). components are built on different kinds of primary data (number, percent, index), which are normalized through a min-max procedure, to get component indices ranging from 0 to 100, with high scores corresponding to a high level of vulnerability. the sum of components’ weights equals 1 so that the evi is also lying between 0 and 100. the variable x measures the share of agriculture in the national gdp according to the ferdi database. y measures the number of days in which an increase in crude oil prices from ies database. the variable ngdpd is the current gdp in dollars. pcpi is the general index of consumer prices. lur is a measure of unemployment rate according to the world bank. bca is the current balance account, according to the world bank database. by calculating the correlation coefficient between different variables, we provide the following matrix: table1: correlation matrix ngdpd y x pcpi evi bca lur ngdpd 1.000000 0.369781 -0.884368 0.958629 -0.801204 -0.703016 -0.391848 y 0.369781 1.000000 -0.541596 0.400977 -0.314260 -0.097818 -0.311239 x -0.884368 -0.541596 1.000000 -0.900987 0.698300 0.500775 0.417394 pcpi 0.958629 0.400977 -0.900987 1.000000 -0.826433 -0.729118 -0.302252 evi -0.801204 -0.314260 0.698300 -0.826433 1.000000 0.922689 -0.090466 bca -0.703016 -0.097818 0.500775 -0.729118 0.922689 1.000000 -0.248040 lur -0.391848 -0.311239 0.417394 -0.302252 -0.090466 -0.248040 1.000000 according to this matrix, there is a strong correlation between gdp and all variables. however, the upward movements of oil price days (y) positively modify the tunisian gdp measured in current us dollars. at the same time, we note that the variable y is negatively correlated with the economic vulnerability index (evi). y has no remarkable effect on the current balance of payments (bca). upward movements of oil price days (y) is creator of inflation and he is not creator of unemployment. it seems paradoxical that y generates growth by positive co-rotation between y and ngdpd, bit it is normal to find a negative correlation between energy price measurement (y) and the share of agriculture in national gdp (x). this result seems logical for a country like tunisia, which is a producer of crude oil and importer of petroleum derivatives. the upward movements in brent crude oil prices affect positively the national gdp through other hidden channels: it is an indirect impact of oil on the tunisian economy. from the remarks of the correlation matrix, the following regressions estimated by ols can be provided and givehidden measurement of the impact of oil prices to macroeconomic variables: table 2: impact of oil prices on vulnerability, national gdp and inflation equation 1 log(evi) equation 2 log(ngdpd) equation 3 log(pcpi) log(y(-1)) 0.089506 0.284842 ar(1) 1.103476 c 3.012979 11.81396 3.368298 log(evi(1)) -2.709354 ma(1) 0.841762 r 2 0.903996 0.500136 0.864299 f statistc 94.16206 22.01198 82.79918 l. jebali et al. ijeca-issn: 2543-3717. june 2018 page 30 nb. all parameters are elasticities. they are statistically significant at a risk of 1%. the three equations are globally significant according to the fisher criterion. the linear equations 1, 2 and 3 prove the results of the correlation matrix. a 1% increase in oil prices makes the tunisian economy more vulnerable. this vulnerability negatively affects current national gdp growth. a 1% increase in economic vulnerability translates into a 2.7% drop in economic growth. according to equation 1, a 1% increase in oil prices generates 0.285% inflation. viii. conclusion the volatility of fuel prices has serious impacts on the tunisian economies because they are not direct. the impact on social welfare and economic growth is indirect. it is apparent on consumer prices by making the tunisian economy more vulnerable. the effect of international fuel prices and volatility are more severe for tunisia and will only be apparent over the long term, through the negative impact to the balance of payments (current account) and the rise in prices by damaging the agricultural sector. the hidden negative impact of crude oil prices on national gdp is serious because in tunisia there is an energy subsidy policy that distorts the precise calculation of the production costs of goods and services. to remedy this problem, the imf (international monetary fund) proposes to the tunisian authority to review the subsidy policy and to adopt a pollution control policy and (the efficiency price system). references [1] d. coady, m. el-said, r. gillingham, k. kpodar, p. medas, and d. newhouse,the magnitude and distribution of fuel subsidies: evidence from bolivia, ghana, jordan, mali, and sri lanka, imf working paper, wp 06/247, 2006. [2] e. papapetrou, oil price asymmetric shocks and economic activity: the case of greece, university of athens, department of economics, athens, greece and bank of greece, economic research department, 2009. [3] f. fabrizio, a. goumilevski, and k. kpodar, a new tool for distributional incidence analysis: an application to fuel subsidy reform, imf working paper, 2015. [4] f. taghizadeh-hesary, n. naoyuki yoshino, macroeconomic effects of oil price fluctuations on emerging and developed economies in a model incorporating monetary variables. adbi working paper series, working paper n°546, 2015. [5] fh. taghizadeh, n. yoshino, g. abdoli, and a. farzinvash,”an estimation of the impact of oil shocks on crude oil exporting economies and their trade partners”, imf working paper, 2013. [6] hc . bjørnland, oil price shocks and stock market booms in an oil exporting country, working papers from norges bank n°16, 2008. [7] hg. huntington, oil shocks and real us income, energy modeling forum stanford university stanford, ca 943054026, 2007. [8] j. de haan, r. inklaar, r. jong-a-pin, will business cycles in the euro area converge? a critical survey of empirical research, journal of economic surveys vol. 22, no. 2, 2013, pp. 234–273. [9] m. balcilar, the impact of oil price on south african gdp growth: a bayesian markov switching-var analysis, university of pretoria department of economics working paper series, 2014. [10] m. closset, s. feindouno, and m. goujon, human assets index retrospective series: 2013 updat, working paper fondation pour les études et recherches sur le développement international. [11] r. jiménez-rodríguez, m. sánchez, oil price shocks and real gdp growth empirical evidence for some oecd countries, european central bank, working paper series, n°362, 2004. [12] t. abeysinghe k. forbes, trade linkages and outputmultiplier effects: a structural var approach with a focus on asia, review of international economics, 13(2), 356–375, 2005. [13] t. abeysinghe, estimation of direct and indirect impact of oil price on growth, economics letters 73, 2001, pp 147– 153. [14] t. clements, h. rainey, et al, an evaluation of the effectiveness of a direct payment for biodiversity conservation: the bird nest protection program in the northern plains of cambodia, biological conservation n°157, 2013, pp 50-59. [15] v. arora, a. vamvakidis, asia and pacific department and strategy, policy, and review department china’s economic growth: international spillovers, imf working paper n°165, 2010. [16] w. tang, l. wu, and zx, zhang, oil price shocks and their shortand long-term effects on the chinese economy, energy economics 2010. doi:10.1016/j.eneco.2010.01.002. international journal of energetica (ijeca) https://www.ijeca.info/index.php/ijeca/index issn: 2543-3717 volume 1. issue 1. 2016 page 30-35 ijeca – issn: 2543-3717. december 2016 30 the profile of the electric field on the earth discontinuity with a lightning conductor ali. khechekhouche department of electric engineering, university of el oued. algeria khechali@yahoo.fr abstract: in this paper, we present some results of investigations carried out in the electric field distribution of both horizontal and vertical lightning conductors in the case of discontinuous earth. the conductors may be situated as well as in the upper or the lower earth part. the electric field distribution was determined in the case of lightning conductor situated between the high voltage rod and the discontinuity (interface) and also in the case of high voltage rod situated between the lightning conductor and the discontinuity. in some situations the electric field distribution on the plan are smaller than defined by the electro-geometrical model. we attribute this result to the great field intensity at the discontinuity, which reduce the lightning conductor discharge capture effect. this is in concordance with the results concerning the electrical strength of such air gaps without lightning conductors. keywords: the electric field, discontinuous earth electrogeometrical model, vertical lightning conductor, horizontal lightning conductor. nomenclature h: height d : distance between its axis and the interface u0% : applied voltage 1. introduction the electrogeometrical model represents a widely used method for the determination of the electric field distribution of a lightning conductor. this method does not take in amount the ground nature. the earth electrogeological properties are in fact very important in the predetermination of the lightning impact points. to examine the influence of these properties, some investigations have been carried out to determine the capture zones of horizontal and vertical earthed rods in the case of the heterogeneous or homogeneous and bad conducting earths [1, 2]. it has been found that the capture zones of a lightning conductor could be, in general, greater than defined by the classical electrogeometrical model [1, 2]. to explain the variations of electric field distribution, it has been studied the electric strength of rod-plane air gaps under negative lightning impulse voltage. both heterogeneous and discontinuous earths were studied. it has been observed that the discharge phenomena are different as found in the case of air gaps with conducting homogeneous earth [3, 4]. this led us to do experiments to determent the electric field distribution on the discontinuous earth with a vertical and a horizontal lightning conductor [5, 6]. in this paper, we present a comparison between the different results obtained with and without lightning conductor on the discontinuous earth. the electric field distribution was determined experimentally, using a laboratory experimental model. mailto:khechali@yahoo.fr ali khechekhouche ijeca – issn: 2543-3717. december 2016 31 2. experimental set up the studied earth called "discontinuous earth" is made up of a square metallic sheet with 4 mm thickness and having two different levels of respective surface 1x1 m 2 (figure 1a or lb). the lightning discharge at its final jump is simulated by an iron rod, whose diameter equals 4.8 mm. this electrode is connected to a lightning pulse generator of 600 kv, 4 kj. the position of the rod is determined by its height (h) compared to the earth and the distance (d) between its axis and the interface. this distance is considered positive when the rod is located above the high and negative part in the other case. the distances h are the same one as in homogeneous system, but the distances d and d is selected so that the tests are carried out for d/h ratio and respectively identical d/h for various values of h. the applied voltage level to use is 0.3u0% of the rod-plane corresponding system, at each selected distance h. for a given height h, we as well apply the same applied voltage level for the rod located above the high part as above the low part of the discontinuous plane. thus it is the same level of applied voltage u0% which is taken into account for a given height h and the corresponding height h+e when the rod is located above the low part of the discontinuous plan. we are interesting to the u0% voltage of disruptive discharge in order to determine the voltage level of selected test equal to 0.3u0%. this applied voltage level allow to avoid the disruptive discharges on the level of the probe because of its sensitivity to the high currents [7, 8]. during tests, the u0% breakdown voltage is determined by the constant multiple steps method. to find this voltage we have used a gaussian arithmetic scale paper. in this work, we have studied all possible configurations according to the lightning conductor position upon the higher or the lower part of the discontinuous earth. we present in this paper results concerning both cases of horizontal and vertical lightning conductors [9, 10]. the electric field distributions obtained with the different configuration of discontinuous earth are compared to that defined by homogeneous system. the configuration of the experimental model used is constituted of a flat metallic earthed sheet (figure 2) fig.2a. system with homogeneous conducting earth for a horizontal lightning conductor e(kv/cm) h d probe ht hc d fig.2b. system with homogeneous conducting earth for a vertical lightning conductor e(kv/cm) h d probe ht hc d fig. 1b. configuration with discontinuous earth for a vertical lightning conductor h dp probe ht d e e(kv/cm) interface aluminium d hc fig.1a .configuration with discontinuous earth for a horizontal lightning conductor h dp probe ht d e e(kv/cm) interface aluminium d hc ali khechekhouche ijeca – issn: 2543-3717. december 2016 32 1. results and discussion 3.1 electric field distribution on the homogeneous conductor earth in order to obtain a reference for the comparison between the results of experimental with discontinuous system, we initially determine the distribution of the field in the case of the homogeneous system with vertical and horizontal lightning conductor, according to the height h of the stem under high voltage in the case of the selected voltage level 0.3u0%. with the applied voltage level 0.3u0%, we notice that, the intensity of the electric field tends towards a constant value, as the lightning conductor moves away from the rod under voltage starting from a relative position d/hc higher or equalizes to 2. when the lightning conductor approaches to the axis of the rod for d/hc lower than 2, the intensity of the field decrease considerably and takes a minimum value for d/hc = 0 (fig.3). [10, 11] 3.2 electric field distribution on the discontinuous conductor earth 3.2.1 lightning conductor situated on the upper part of discontinuous earth we have determined the electric field distribution for different values of the d/hc ratio, in to possible configuration. the first configuration corresponds to the vertical (figure 4a) or the horizontal (figure 4b) lightning conductor situated between the earth discontinuity and the axis of the discharge. for the applied voltage level 0.3u0% and for the positions of the probe far from the interface (d/h > 2), we notice that the intensity of the field measured on the high part of the discontinuous earth is practically equal to that corresponding to the case of the system with homogeneous earth of the same length. near the interface (d/h<2), the results obtained show a kind of discontinuity in the evolution of the electric field. this discontinuity is due to the role of the lightning conductor which would have the same effect as a point, transforming the system rod-plan into system rod-rod. this fact explains the abrupt decrease in the field below the lightning conductor and the increase in the rigidity of the interval rod-plane and the phenomena of discharge observed in preceding research tasks [03, 04]. indeed, even for relatively large d/h distances, electric discharges can occur between the rod and the lightning conductor and not between the rod and the plan according to the path the shortest correspondent with the height h. [11, 12] we notice that the air interval rod-lightning conductor constitutes preferable path for the lines of electric field. indeed, the system rodlightning conductor which behaves as a system point-point is less rigid than the system point-plan. this justifies, the reason why, we sometimes obtain disruptive discharges on the lightning conductor, for the low values of the d/hc ratio. fig.3a. electric field distribution with homogeneous conducting earth for a horizontal lightning conductor fig.3. electric field distribution with homogeneous conducting earth for a vertical lightning conductor 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=0 d/hc=2 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=0 d/hc=2 ali khechekhouche ijeca – issn: 2543-3717. december 2016 33 the second configuration consists of a lightning discharge evolving between the vertical (figure 5a) or the horizontal (figure 5b) lightning conductor and the earth discontinuity. the results show that when the lightning conductor is relatively near of the earth discontinuity (d/hc=1.5), the distribution of electric field is decrease than defined by the same model without rod lightning. but when the d/hc ratio becomes superior or equal to 3.5 the electric field intensity is confounded to the model without rod lightning, how has no effect on the attract of discharges by the interface 3.2.2 lightning conductor situated on the lower part of discontinuous earth in the theirs configuration, the lightning conductor is placed in the lower part of the earth and the high voltage lightning rod is situated between the earth discontinuity and the lightning conductor (figure 6a and 6b). with regard to the field on the low part of the discontinuous earth, the results show that the field intensity is lower than that of the high part. that is due to the increase in the distance rod-probe. in the vicinity of the interface, the field takes the lowest value on the plan. the results show that when the vertical (figure 6a) or the horizontal (figure 6b) lightning conductor is relatively near of the earth discontinuity (d/hc =1.5), the electric field distribution increase. but when the d/hc ratio becomes superior or equal to 2.5 the electric field intensity is confounded to the model without rod lightning. on the level of the interface, where the system rod-interface behaves as a system rod-rod which is less rigid than the system rod-plan, the relationship between the two systems takes the value maximum (e/e0=1.25) which corresponds to the value where there is a great probability of having disruptive discharges direct on the interface. [11, 13] fig.4a. electric field distribution with discontinuous conducting earth for a horizontal lightning conductor 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=1,5 d/hc=2 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=1,5 d/hc=2 fig.5a. electric field distribution with discontinuous conducting earth for a horizontal lightning conductor fig.5b. electric field distribution with discontinuous conducting earth for a vertical lightning conductor fig.4b. electric field distribution with discontinuous conducting earth for a vertical lightning conductor 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=0 d/hc=0,5 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=0 d/hc=0,5 ali khechekhouche ijeca – issn: 2543-3717. december 2016 34 the last studied configuration corresponds to the lightning conductor situated in the lower part of the discontinuous earth, between the lightning high voltage rod and the earth discontinuity (figure 7a and 7b). we observe that the electric field intensity of the vertical (figure 7a) or the horizontal (figure 7b) lightning conductor correspond in this case to that give by second configuration [12, 14] 3. conclusion the influence of the earth discontinuity on the electric field distribution with presence of a vertical or a horizontal lightning conductor depends essentially on the discharge axis position with regard to the lightning conductor and to earth discontinuity. this influence is more marked when the lightning conductor is situated very near of the earth discontinuity. it would be owed to the relatively intense electric field in this part of the earth. in the case of vertical or horizontal lightning conductor situated on the high part of the discontinuous earth between the discharge axis and the earth discontinuity, the electric field intensity is smaller that defined by the same model without lightning conductor. this wideness depends on the lightning conductor horizontal position. on the other hand, when the discharge evolves on the same part of the earth between the interface and the lightning conductor, the electric field intensity is smaller or equal that defined by the same model without lightning conductor. when the vertical, or horizontal, lightning conductor is placed on the low part of the earth, and the high voltage rod situated between it and the earth discontinuity, the electric field distribution depend on the position d/hc of the lightning conductor with regard to the earth discontinuity. more this relative size is small; more the electric 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=-1,5 d/hc=-2 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=-1,5 d/hc=-2 fig.6a. electric field distribution with discontinuous conducting earth for a horizontal lightning conductor fig.6b. electric field distribution with discontinuous conducting earth for a vertical lightning conductor 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=-0,5 d/hc=-1 0.5 1 1.5 -6 -4 -2 0 2 4 6 e /e ° d/h d/hc=-0,5 d/hc=-1 fig. 7a. electric field distribution with discontinuous conducting earth for a horizontal lightning conductor fig.7b. electric field distribution with discontinuous conducting earth for a vertical lightning conductor ali khechekhouche ijeca – issn: 2543-3717. december 2016 35 field intensity would be reduced. in the other cases, the intensity is confounded that defined by the same model without lightning conductor. when lightning conductor is placed on the lower part of the earth, and it situated between the high voltage rod and the earth discontinuity, the electric field intensity reduced on the interface. this is also available for a vertical or a horizontal lightning conductor. references [01] r. h. golde ; « lightning : t2 », academic press, 2ème édition, london,(1981). [02] g. le roy, c. gary, b. hutzler, j. lacot, c. dubaton : « les propriétés diélectriques de l’air et les très hautes tensions», ed eyrolles, paris, 1984, pp 92-251. [03] t. horvath : « computation of ligthning protection», research studies press ltd, england 1991. [04] beroual a, rakotonandrasana j, fofana i. predictive dynamic model of the negative lightning discharge based on similarity with long laboratory sparks. ieee transactions on dielectrics and electrical insulation. october 2010, vol. 17, 5, pp. 1551 – 1561. [05] a. boubakeur, s. a. a. boumaza, r. belaicha, r. boudissa : « influence of earth heterogeneity on negative lightning breakdown of rod-plane air-gaps », 24th iclp, birmingham, 1998, pp : 473-477. [06] a. boubakeur, j. ferras : « négative lightning breakdown of rod-plane air gaps with heterogeneous earth », 5ème ish, paper 14-26, braunschweig ,rfa, 1987. [07] a . rahmani, a. boubakeur, h. brouri; “ model of an horizontal lightning conductor protection in the case of earth discontinuity” international symposium on electromagnetic compatibility emc europe 2002, (sorrento) italy 2002, pp 267-270. [08] s. cristina, g. denelli, m. feliziani, numerical computation of corona space charge and v-i characteristic in dc electrostatic precipitators, ieee trans. ind. appl., 27, (1991), pp 147-153 [09] pei-bai zhou, numerical analysis of electromagnetic fields, springer-verlag, berlin, 1993. [10] a. kara, e. onal, o. kalenderli, k. mardikyan, “the effect of insulating barriers on ac breakdown voltage in inhomogeneous field”, ieee melecon 2006 mediterranean electrotechnical conference, benalmádena (málaga), spain, 16-19 may 2006. , pp. 1206-1208 [11] khechekhouche a, ben attous d. effect of earth discontinued to the electrical field distribution in rod plane air gaps under lightning impulse. j. fundam. appl. sci., 2016, 8(3), pp 1054-1065. [12] khechekhouche a. benattous d. mekhaldi a. boubakeur a. electric field measurement in rod discontinued plane air gaps using distributed capacity probe. j fundam app sci. 2014, 6(1), 1-10 [13] a .rahmani, a. khechekhouche, a. mekhaldi, a.boubakeur “ electrical strength of rod-discontinuous plane air gap under lightning impulse applied voltage using a distributed capacity probe ” ieeeceidp, october 14-17, 2012, montréal canada, pp 379-382. [14] k. yamazawa and h. yamashita, “calculation of the electric field distribution under the point-plane gap configurations using the fem”, 1997 ieee annual report conference on electrical insulation and dielectric phenomena, minneapolis, 19-22 october 1997. , pp. 648-651 i international journal of energetica (ijeca) https://www.ijeca.info/index.php/ijeca/index issn: 2543-3717 volume 1. issue 1. 2016 page 1-11 ijeca – issn: 2543-3717. december 2016 page 1 numerical investigation of heat and mass transfer processes while the desorption of hydrogen gas stored in mmni4.6fe0.4-h6 ali boukhari department of mechanical engineering, faculty of technology, university of el-oued 39000. algeria. e-mail: fibonali2379@gmail.com abstract— this work presents a numerical investigation of two-dimensional coupled heat and mass transfer processes in a unit disc of an annulus-disc reactor filled with the intermetallic (mischmetal) compound mmni4.6fe0.4, during the hydrogen gas desorption using the finite volume method. temperature and amount of desorbed hydrogen and their time-averaged quantities inside the metal hydride bed are presented for different heat transfer fluid temperatures, and different metal thermal conductivities. impacts of both effects on the metal hydride reactor performance in terms of discharging time are examined by means of a set of numerical simulations. thus, the dehydriding time minimization relates to the adjustment of the amount of heat addition to the packed bed reactor. a good agreement was found between the present computational results and the experimental data reported in the literature. keywords— numerical simulation, coupled heat and mass transfer, finite volume method, metal hydride, desorption. nomenclature ba, van’t hoff constants b forchheimer’s coefficient, m -1 dc desorption rate coefficient, s -1 pc specific heat, j/kg k pd particle diameter, m de desorption activation energy, j/mol h heat convection coefficient, w/m 2 k k permeability, m 2 m h2 mass reaction rate, kg/m 3 p pressure, pa  universal gas constant, j/mol k r radius of the annular disc unit, m r radius of cooling tube, m dxs , dys forchheimer terms in the x and y-directions t temperature, k t time, s v  velocity in the metal bed, m/s %.wt hydrogen storage capacity yx, x and y-coordinates greek symbols h heat of formation, j/kg  thermal conductivity, w/mk  porosity  dynamic viscosity, kg/m s  density, kg/m 3 slp slope factor hys hysteresis factor  desorbed fraction subscripts 0 initial e effective emp empty eq equilibrium f bath fluid g gas s solid mailto:fibonali2379@gmail.com ali boukhari ijeca – issn: 2543-3717. december 2016 page 2 1. introduction besides the fact that hydrogen is been sought as a clean alternative energy source, naturally abundant and having various production sustainable sources, hydrogen energy exploit encounter many industrial obstacles that are mainly categorized under transportation and/or storage related to the automotive industry. among the techniques of storing hydrogen gas is to absorb it chemically by some simple or intermetallic compounds to form a metal hydride, this technique is qualified as solid state hydrogen storage. therefore, many research studies have been carried out to improve this storage technique, and to enhance its reliability and safety in different applications. the technology of solid state hydrogen storage offer high volumetric density compared against many other techniques, but unfortunately has a low hydrogen absorption capacity [1]. nevertheless, in addition to their disadvantages of weight and cost, metal hydrides have another disadvantage which is their limited kinetics because they release/absorb huge amounts of heat whereas hydriding/dehydriding process, the latter is mostly restricted by the hydride’s thermal properties and related cooling or heating techniques respectively. in fact, his causes serious challenges to the thermal management of the hydriding/dehydriding process [2]. hence, the aforesaid thermal management of metal hydride reactors encounters the complex phenomenon of coupled heat and mass transfer in porous media where all the three modes of heat transfer take place. thus in order to describe this phenomenon in packed beds, a variety of mathematical models have been reported on the heat and mass transfer in literature through multiple investigations[3-8], clarifying at which the amount of heat is removed or furnished to the metal hydride managed system. these research investigations argued the obvious dependency of the hydrogen absorption and desorption rates on heat and mass transfer and on the reaction kinetics of the packed hydride beds [3-5]. starting from one-dimensional models and focusing on heat conduction [6], afterward considering both convection and conduction [7-9], followed by coupling the conduction and convection with thermal radiation effects [10]. effects of porous bed reactors geometries also have been studied notoriously; the two-dimensional models [8-9, 11-12] and the well-known three-dimensional study of aldas et al. [3]. it was concluded from several works that radiative effects on the sorption process are negligible in the case of the lani5based systems (low-temperature hydrides), and are important for the mg–based systems (high-temperature hydrides) [11], whereas the effect of convection is important and significantly influences the temperature repartition, however the overall hydride formation is found to be not affected by fluid flow [3]. various hydride packed bed studies proved that twodimensional models are plenty adequate to represent heat and mass transfer in cylindrical shaped reactor beds (named metalhydride tanks), and can be employed in an enhanced bed-reactors design to reduce absorption and desorption times. by numerically studying the solid state hydrogen storage in packed beds, dogan et al. [13] found that the temperature increases adversely affect the absorption rate. therefore the system must be efficiently cooled for a rapid charge. furthermore, they investigated the effect of two charging methods on filling time, and found that hydrogen gas must be supplied radially for a fast filling operation. in their work, macdonald and rowe [14] examined, by mean of the resistive analysis calculations, the impacts of external convection resistance on thermodynamic behavior inside the mh tank. they used a one-dimensional resistive analysis and a two-dimensional transient model to determine the impact of external fins addition on the ability of a metal hydride tank to deliver hydrogen at a specified flow rate. they found that external fins addition have a large impact on the hydrogen gas pressure within the tank when a periodic hydrogen demand is imposed for the particular metal hydride alloy (lani5) employed and the tank geometry studied. according to model results, they suggested that the metal hydride alloy at the tank core region can be removed to reduce weight and cost, without detrimental effects on the system performance. some widely-studied hydrogen storage alloy (like intermetallic compound) showed evidently that their hydrogen storage capacity ( .%wt ) is substantially lower than the current us department of energy (doe) target for on-board hydrogen storage applications [8, 15]. while, the introduction of the computational fluid dynamics (cfd) techniques in the researches field of thermal engineering, have developed the design of heat exchange devices, particularly when investigating heat and mass transfer in porous media e.g. in packed bed reactors used for energy storage [10] or fuel cell applications modeling [16]. in their work dated in 2006, marty et al. [4] aimed to numerically predict the coupled heat and mass transfer characteristics of an industrial cylindrical tank during hydrogen storage, using the commercial cfd code fluent. they emphasized the importance of achieving a three-dimensional modeling for the design of an industrial tank; their results were obtained on a magnesium hydride laboratory tank. also, phate et al. [5] deemed to explain hydride reactor coupled heat and mass transfer during absorption of hydrogen in cylindrical coordinates using the aforementioned cfd tool, and considering the effect of bulk diffusion to accurately model the mass transfer in solid phase. both latter work models ignored the effects of plateau slope and the pressure-concentration isotherms (pct) hysteresis related to the hydriding alloy used. the simulation results of mohan et al. [17] showed that the bed thickness is the major controlling parameter of the hydrogen absorption rate at all locations within the bed, although the heat exchanger (cooling tubes) dimensions are observed to have marginal influence on hydriding time of the lani5-based hydrogen storage device. afterward, krokos et al. [18] presented a systematically novel approach aiming to the design optimization of a multi-tubular metal hydride tank, containing up to nine tubular metal hydride reactors, and used in on-board hydrogen storage applications. they numerically investigated the arrangement of cooling tubes inside the metal hydride bed, founding that a uniform arrangement configuration of the embedded cooling tubes yielded to an optimal design parameter, consequently to their detailed three-dimensional mathematical model validated against that developed by kikkinides et al. [12]. thus by choosing a symmetric arrangement of the cooling tubes inside the reactor bed, freni et al. [19] concluded that a shorter refueling time would be obtained at higher heat transfer rate. they have performed their numerical computations using the comsol multiphysics simulation ali boukhari ijeca – issn: 2543-3717. december 2016 page 3 environment to demonstrate the fact that an increase in the hydride thermal conductivity can further improve dynamically the reactor performance, provided that the absorbent bed is sufficiently permeable to hydrogen. optimizing the performance and well designing the metal hydride (mh) reactors is of primordial importance for the efficient operation of related systems in many industrial applications beside the hydrogen storage, particularly heat pumps and thermal compressors, rendering the configuration design an extremely imperative part in the mh reactors applications field. based on the aforesaid, we present this current work to emphasize the numerical study results of an annulus-disc reactor (adr) unit containing a packed hydrogen-saturated metal hydride alloy. in which a mass transfer takes place between the packed metal hydride and the hydrogen gas ceded to the inner tube of the disc unit. concurrently, heat transfer occurs between the annulus-disc unit on one hand, and the heating fluid outside it and the tubes inside it, on the other hand. in mh applications, there are several types of reactors; the one studied in the present work enters under the shell and tube class type of heat exchangers studied by many researchers [8, 20]. a practical configuration of an adr would consist of many annular discs to store or provide hydrogen gas depending on whether hydrogen is being absorbed or desorbed. in this paper, we attempt to present a numerical study of such a device filled with the mischmetal mmni4.6fe0.4 as the hydriding/dehydriding alloy. throughout the computations of this numerical investigation we have used openfoam ® [25], an open source finite volume code capable of solving industrial type problems, while adopting the two-dimensional mathematical model of demircan et al. [11] to show and analyze the influence of the heat exchange device and the solid (mh) conductivity on dehydriding temperature fields of the mh bed reactor, and on the overall hydrogen gas desorption too. this paper is organized as follows. section 2 presents the mathematical model. section 3 discusses the numerical method and techniques of resolution, which have been used to achieve computations. section 4 presents the validation of the adopted model and numerical techniques, then the results discussion. finally, a conclusion is given. 2. mathematical model the mathematical model for the annulus-disc reactor (represented schematically in figure 1) considered in the present work is similar to that of demircan et al. [11], with mmni4.6fe0.4 as metal hydride alloy which is filled in the annular space between the inner central tube and the outer peripheral heating wall. the annulus disc is traversed by a number of active heating tubes in this case of the hydrogen desorption process. the thermo–physical properties of the alloy are as it is listed in table 1. because of angular symmetry we will restrict the computational domain to the sector area between two adjacent heating tubes. the computational domain accompanied with the mesh used in computations are shown in figure 2. table 1. thermo–physical properties of the metal hydride, hydrogen and other parameters used in the simulations [8, 14, 22 23]. parameters values absorption rate constant dc 475 s -1 specific heat of hydrogen gas pgc 14.9 kj/mol k specific heat of the solid psc 419 j/kg k activation energy for absorption de 25 kj/mol heat convection coefficient h 1652 w/m 2 k permeability of the metal k 10 -8 m 2 heat conductivity of the h2 gas g 0.24 w/mk heat conductivity in the metal s 1.6 w/mk molecular mass of hydrogen 2h m 2.016 kg/kmol porosity of the metal  0.5 h2-free metal hydride density emp 8500 kg/m 3 reaction heat of formation h 27.5 kj/kg plateau slope slp 0.35 outlet pressure of hydrogen 0p 8 bars outlet temperature of hydrogen 0t 298 k htf and tubes temperature ft 298 k annular disc unit radius r 0.2 m ali boukhari ijeca – issn: 2543-3717. december 2016 page 4 fig. 1. schematic section view of the studied adr unit disc equipped with 5 heating tubes the unit disc reactor considered is composed of a solid phase (metal-powder) and a gaseous phase (hydrogen), hence forming a porous medium. in order to establish the governing equations of the coupled heat and mass transfer with chemical reaction within the metal hydride reactors, we consider to up-scale these latter equations from pore level to macro level. fig. 2. one of the computational domains considered, meshed with the prescribed boundary conditions. the main simplifying assumptions considered in applying the mathematical model are the following: 1. the media are in local thermal equilibrium between gas and solid 2. radiative heat transfer is negligible. 3. the gas phase is ideal from the thermodynamic viewpoint. 4. mass transfer takes place through the porous filter (h2 collector), while the hydrogen outlet temperature and pressure are maintained constants. 5. porosity is uniform and its variation with desorption is negligible. 6. equilibrium gas pressure in the bed obeys van’t hoff law relations. 7. thermo-physical properties of both gas and solid phases are constant. 8. the radial temperature variation of the heating tubes is negligible; hence they are considered isothermal tubes. 2.1 volume-averaged mass balance equations for the hydrogen gas for describing the hydrogen flow and the desorption in a metal hydrogen reactor, unsteady flow is assumed. and the local hydrogen gas density g and the local metal hydride density s change as the metal hydride cede its hydrogen gas progressively; therefore an additional source term is included in the right-hand side of the continuity equation to denote the appearing amount of hydrogen in the bed with time mv y u xt gg g          )()(    (1) for the metal-hydride alloy to model the density of metal powder changes due to the desorption of hydrogen, a sink term is added to the right-hand side of the governing equation, to denote the amount of hydrogen that is out-flowing from the solid with time. hence, m t s       )1( (2) ali boukhari ijeca – issn: 2543-3717. december 2016 page 5 2.2 hydrogen gas density the gas density g is deduced from the perfect gas law t pm h g   2 (3) where 2h m and  denote the molecular mass of hydrogen and the universal gas constant respectively. 2.3 volume-averaged momentum equations for the gas due to the presence of the solid matrix, a pressure drop will occur in flows through porous media (metal hydride powder bed in this case). accordingly, to reveal this effect a supplementary sink term should be added to the momentum equations in x and y directions. the above mentioned pressure drop depends on the properties of the porous medium and is described by including the forchheimer modification term in x and y momentum equations which reduces to darcy’s law if the gas velocity and viscous boundary effect are low. thus, in the x-direction, dxgg s y u v x u u y u x u x p t u                   )()( 2 2 2 2  (4) in the y-direction, dygg s y v v x v u y v x v y p t v                   )()( 2 2 2 2  (5) where )( uvbu k s gdx     and )( vvbv k s gdy     are the source terms instead of the additional pressure drop in the bed due to viscous effects and the increasingly important role played by fluid inertia. in these equations v  is the magnitude of the hydrogen flow velocity. the following correlation for b have been yielded from experimental measures implying the drainage of the gas through the columns of packed spheres, some sand and some pulverized coal (bejan and kraus [21]): 3 150 75.1 k b  (6) where k and  are the permeability and the porosity of the packed bed. 2.4 volume-averaged energy equation the energy equation in the metal bed can be expressed in terms of a single temperature variation, in this way we can conclude that the gas and solid phases quickly reach thermal equilibrium for the mischmetal alloy used in the reactor [22]. since dehydriding process inside the bed is an endothermic reaction, an amount of heat is consumed; subsequently an additional source term is added in the energy equation. hence, ))(()()()()()( pspgpggpggeeep ccthm y t vc x t uc y t yx t xt t c                     (7) with the effective volumetric heat capacity : psspggep ccc  )1()(  (8) and the effective thermal conductivity is taken as : sge  )1(  (9) 2.5 reaction kinetics the amount of hydrogen that is desorbed from the hydrogen-saturated solid with time is directly related to the reaction rate of the dehydriding process of the metal, the latter is expressed as [11]: ))()(exp( emps eq eqd d p pp t e cm      (10) where dc is a material-dependent desorption rate constant, de is the activation energy, emp is the density of the empty metal hydride and eqp is the equilibrium pressure calculated using the van’t hoff relationship; ali boukhari ijeca – issn: 2543-3717. december 2016 page 6 hysslp eq t b a p p   )()ln( 0 0 (11) where slp is a factor which takes into account the slope of the plateau pressure in the pct of hydriding/dehydriding metal alloy, and hys accounts for hysteresis between the absorption and desorption processes, but since the present work focus only on desorption process we will not take the hysteresis parameter into consideration. 0p is the reference pressure (taken 1 atmosphere in all cases), a and b are van’t hoff constants having the values of 12.95 and 3731.42, respectively [23]. 2.6 initial and boundary conditions initially, the pressure, temperature and hydride density are assumed to be constant in the bed. in mathematical parlance, these conditions are written as: at .)0,,(,)0,,(,)0,,(;0 000 ss yxtyxtpyxpt   for ;0t at the hydrogen outlet (the inner central tube) : ,),,(,),,( 00 ttyxtptyxp  (12) the lateral heating wall (peripheral wall) (fig. 2) : )(),,( tthtyx n t fe      (13) where h is the heat transfer conductance between the metal hydride bed and the heating fluid having the temperature ft inside the peripheral jacket, taken from [8-9, 11], and n  is the outward normal unit vector of the considered boundary. the embedded heating tubes, which are supposed to be isothermal (fig. 2): ,),,( fttyxt  (14) the other boundary conditions are assumed to have the symmetry condition type. 0),,(    tyx n t  (15) 3. numerical method of solution the governing equations are solved with a fully implicit finite volume numerical method implemented in the cfd openfoam ® [25]. the solution procedure by means of the aforesaid method consists of transforming the governing differential equations into a general algebraic form, after integrating those numerically over a finite volume-meshed computational domain (versteeg and malalasekera [24]). a transport equation in the general form may be written as cd sv t    )()( )(    (16) where  denotes a generic transported variable quantity, d denotes the diffusion coefficient and cs the source term. this common form equation is solved using the pressure-velocity coupling algorithm named simplec [24] which give to our cfd calculations more rapidity, stability and consistency, knowing that the second order upwind scheme is used in the purpose of interpolating momentum convective fluxes [24-25]. calculations were carried out on a core™ i5 pc, leading to take about 8 hours per a typical case, while using highly optimized compilation for the binaries. statistically, the volume-weighted average of the problem physical quantities defined by the following relation:     i j ji i j jiji v v , ,, (17) provides a reliable measure of the mh reactor performance, where ji, is the generic variable quantity, corresponding to the control volume jiv , , in the sense of finite volume method [8]. 4. results and discussion 4.1 grid independency tests after adopting the mathematical model, and establishing the relevant solution procedure, a mesh independency tests were performed to examine the effect of the computational mesh on the dynamical behavior of the average reacted fraction. ali boukhari ijeca – issn: 2543-3717. december 2016 page 7 various quadrilateral mesh grids for the considered domain geometry were exploited in the independency test calculations, consisting in structured and non-structured types. it was observed a close accord between the several tested computational meshes, which concede to the present simulations a clear independency from the computational meshes. 4.2 validation of numerical results first of all, before showing and discussing the obtained results, we have carried out some simulations for the validation of the considered model in comparison with some experimental data present in the literature, mainly those from the work of jemni et al. [22], in which a cylindrical shaped lani5–h2 reactor was investigated. also we have assumed axial symmetry to apply the adopted two-dimensional approach to deal with the three-dimensional experimental reality. figure 3 shows the temperature time-evolution inside the metal bed in three different points within the reactor. the temperature of the heating fluid and the outlet pressure are ct f  20 and barsp 8 for the absorption case, respectively. at the beginning of the desorption process, the temperatures show a rushed decrease in the metal bed, because the hydrogen-metal reaction is endothermic then increase gradually with the reaction kinetics exponential growth. the simulation results were in excellent agreement with the experiments, conceding that the adopted model can be used for further investigations of the transient thermal–fluid behavior in mh reactors. fig. 3. temperature evolution at three points within the cylindrical mh tank experimented by jemni et al. [22] in the hydriding case with the heating fluid temperature at 20°c 4.3 hydrogen desorption from the mmni4.6fe0.4 alloy we focus our attention in this section impacts of heat transfer fluid temperature, and metal alloy thermal conductivity on hydrogen gas desorption inside the adr-type metal-hydride reactor. thus, the heat and mass transfer dynamical behavior inside the annulus-disc reactor is examinated by means of several numerical simulations of the packed bed containing the mischmetal mmni4.6fe0.4, considered as hydrogen-saturated (mmni4.6fe0.4h6). this ab5-type alloy, which present equilibrium pressures ranging from 10 to 20 bars at the ambient temperature, and can stock up to 1.6 wt% reversibly. desorption numerical simulations presented in this paper were carried at a constant discharging pressure of 35 bars, and at temperature of 25 °c. simulations are realized for the heating temperature range ; tf = 20°, 25°, 30° and 35°c, in the aim to inspect the heating temperature influence on the hydrogen desorption time. storage metal thermal conductivity effects on the adr reactor performance in discharging time terms, and related to the h2 reacted fraction, are examined by carrying a set of numerical simulations ranging in the interval; λs = 2.4,3,5 et 8 w/mk. 4.3.1 htf temperature effects initially, the system is discharged at an outlet pressure of 35 bars and outlet temperature of 25°c. the corresponding hydrogen concentration is 1.57 wt%. figure 4 gathers the time evolutions of the hydrogen desorption capacity (wt%), calculated inside the mh reactor at the monitoring point s3(0.092, 0.094). we can observe from these time history curves that hydrogen desorption capacity is always an increasing function monotonically, until reaching the limit capacity. hence, the htf temperature augmentation reduces visibly the discharging time of the h2 gas. consequently, the heating temperatures affect positively the examined mh reactor performance enhancements in desorption. ali boukhari ijeca – issn: 2543-3717. december 2016 page 8 fig. 4 temporal evolution of the storage capacity of the packed bed of mmni4.6fe0.4 at point s3(0.092, 0.094). from the figure 4, we observe also that the required time to attain the limit value of desorption capacity is considerably short (< 15 minutes). this can be explained by the fact that the monitoring point (s3) position is located near the heated walls. figure 4 showing the temporal evolution curves of the average desorbed fraction, affirms the conclusion that the heating temperature augmentation is a favorable parameter in the mh reactor desorption performance. fig. 5 htf temperature effect on h2 desorption at constant discharging pressure. the average desorbed fraction plots show that a complete desorption takes a delay of 4.5 hours in the case of the 20 °c heating temperature-reactor, nevertheless the same average fraction requires only about 3 hours to be desorbed completely, which represents 33% of the reaction time reduction. obviously, from the profile plots of hydrogen desorption capacity along the midline, at instants indicated on figure 6, we can mention the conclusion that a wave-like (in motion) behavior of the desorbed fraction take place within the mh reactor. figure 6 confirms again this conclusion, and announces that a complete dehydridation (desorption) is achieved after 3 hours for the case of heating temperature of 308 k. ali boukhari ijeca – issn: 2543-3717. december 2016 page 9 fig. 6 desorbed hydrogen amount profiles (in kg h2/kg of hydride), plotted along the midline of the packed bed, at selected times. 4.3.2 metal-hydride thermal conductivity effect the mh bed thermal conductivity is a key-parameter in enhancing reactor performance. figure 7 shows the temporal evolutions of the hydride bed average temperature obtained by numerical simulations for different thermal conductivities. as expected, a thermal conductivity increase could be directly interpreted in a discharging (desorption) time decrease within the mh reactor. practically, the results obtained for this packed bed reactor type incites us to investigate the mh reactors design containing highly conductive porous matrices, or to incorporate several heat exchangers devices inside the metal-hydride bed [16]. moreover, the average density of the metal hydride is affected by its thermal conductivity, as we can observe on figure 8 showing thermal conductivity effect on solid (metal-hydride) average density, where thermal conductivity increase involves a substantial h2 discharging time reduction, knowing that for the metal thermal conductivity of 8 w/mk, the solid cede the entirety hydrogen absorbed mass in a time period of 1.5 hour. reacted fraction values χ (desorbed amount) close to unity indicate high desorption rate, which conduct to conclude that hydrogen desorption process take place essentially in hot regions inside the reactor, or near walls undergoing thermal exchange (heating). the core region of the mh reactor having the weakest reaction rate, which yet has drawn to the suggestions to take-off this region without harmful effect on reactor performance [14]. fig. 7 temporal evolutions of desorption temperatures for different mh thermal conductivities. ali boukhari ijeca – issn: 2543-3717. december 2016 page 10 fig. 8 thermal conductivity effect on mh density during h2 desorption. 5. conclusion in this work, the hydrogen gas desorption in metal hydride bed is numerically investigated in an annulus-disc reactor unit. a two-dimensional mathematical model to describe the transient coupled heat and mass transfer in the hydride bed during the desorption process of hydrogen has been adopted and employed. the calculations were performed using the finite volume method bundled in the open cfd software called openfoam ® , whilst taking into account the pct’s plateau slope factor of the dehydriding alloy (its kinetics), and the additional pressure drop in the bed caused by fluid inertia (momentum), besides considering the forchheimer modification source terms in the momentum equations of the present mathematical model. the numerical results showed good accordance with the experimental data reported in the literature. references [01] l. k. heung, “using metal hydride to store hydrogen,” doe report, wsrc-ms-2003-00172, 2003. [02] a. isselhorst, “heat and mass transfer in coupled hydride reaction beds,” j. alloys compounds, vol. 231, pp. 871-79, 1995. [03] k. aldas, m. d. mat and y. kaplan, “a three-dimensional mathematical model for hydrogen absorption in a metal hydride bed,” int. j. hydrogen energy, vol. 27, pp. 1049-56, 2002. [04] p. marty, j. f. fourmigue, p. de rango, d. fruchart and j. charbonnier, “numerical simulation of heat and mass transfer during the absorption of hydrogen in a magnesium hydride,” energy conversion and management, vol. 47, pp. 3632-43, 2006. [05] a. k. phate, p. maiya and s. murthy, “simulation of transient heat and mass transfer during hydrogen sorption in cylindrical metal hydride beds,” int. j. hydrogen energy, vol. 32, pp. 1969-81, 2007. [06] r. gopal and s. murthy, “prediction of heat and mass transfer in annular cylindrical metal hydride beds,” int. j. hydrogen energy, vol. 17, pp. 795-805, 1992. [07] h. choi and a. f. mills, “heat and mass transfer in metal hydride beds for heat pump applications,” int. j. heat and mass transfer, vol. 33, pp. 1281-89, 1990. [08] a. boukhari and r. bessaïh, “numerical heat and mass transfer investigation of hydrogen absorption in an annulusdisc reactor”, int. j. hydrogen energy, vol. 40(39), pp. 13708-17, 2015. [09] d. chabane, f. harel, a. djerdir, m. ibrahim, d. candusso, o. elkedim and n. fenineche, “influence of the key parameters on the dynamic behavior of the hydrogen absorption by lani5”, int. j. hydrogen energy, (article in press), 2016. [010] i. a. el-osery, m. a. el-osairy, a. m. metwally, m. m. keshk and m. el-gammal, “dynamic simulation of the convective model for metal hydride hydrogen storage beds,” energy sources, vol. 15, pp. 523-30, 1993. [011] a. demircan, m. demiralp, y. kaplan, m. d. mat and t. n. veziroglu, “experimental and theoretical analysis of h 2 absorption in lani5-h2 reactors,” int. j. hydrogen energy, vol. 30, pp. 1437-46, 2005. [012] e. kikkinides, m. georiadis and a. stubos, “on the optimization of hydrogen storage in metal hydride beds,” int. j. hydrogen energy, vol. 31, pp. 737–51, 2006. [013] a. dogan, y. kaplan and t. n. veziroglu, “numerical investigation of heat and mass transfer in a metal hydride bed,” app. math. and computation, vol. 150, pp. 169-80, 2004. ali boukhari ijeca – issn: 2543-3717. december 2016 page 11 [014] b. macdonald and a. rowe, “impacts of external heat transfer enhancements on metal hydride storage tanks,” int. j. hydrogen energy, vol. 31, pp. 1721-31, 2006. [015] d. p. broom, hydrogen storage materials: the characterization of their storage properties, springer-verlag london, 2011. [016] m. visaria and i. mudawar, “experimental investigation and theoretical modeling of dehydriding process in highpressure metal hydride hydrogen storage systems,” int. j. hydrogen energy, vol. 37, pp. 5735-49, 2012. [017] g. mohan, p. maiya and s. murthy, “performance simulation of metal hydride hydrogen storage device with embedded filters and heat exchanger tubes,” int. j. hydrogen energy, vol. 32, pp. 4978-87, 2007. [018] c. a. krokos, d. nikolic, e. s. kikkinides, m. c. georgiadis and a. k. stubos, “modelling and optimization of multi tubular metal hydride beds for efficient hydrogen storage,” int. j. hydrogen energy, vol. 34, pp. 9128-40, 2009. [019] a. freni, f. cipiti and g. cacciola, “finite element-based simulation of a metal hydride-based hydrogen storage tank,” int. j. hydrogen energy, vol. 34, pp. 8574-82, 2009. [020] f. yang, x. meng, j. deng, y. wang and z. zhang, “identifying heat and mass transfer characteristics of metal hydride reactor during adsorptionparameter analysis and numerical study,” int. j. hydrogen energy, vol. 33, pp. 1014-22, 2008. [021] a. bejan and a. d. kraus, heat transfer handbook, john wiley & sons, inc, 2003. [022] a. jemni, s. ben nasrallah and j. lamloumi, “experimental and theoretical study of a metal–hydrogen reactor,” int. j. hydrogen energy, vol. 24, pp. 631-44, 1999. [023] g. sandrock and g. thomas, iea/doe/snl hydride databases, [online available] http://hydpark.ca.sandia.gov. [024] h. k. versteeg and w. malalasekera, an introduction to computational fluid dynamics: the finite volume method, 2 nd edition, pearson education ltd, 2007. [025] open∇ foam, the open source cfd toolbox user guide, version v1606+, opencfd ltd, 2016. http://hydpark.ca.sandia.gov/ international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 2. 2018 page 22-28 ijeca-issn: 2543-3717. december 2018 page 22 comparative study between sliding mode control and the vectorial control of a brushless doubly fed induction generator oussama moussa 1 , rachid abdessemed 1 , said benaggoune 1 , hani benguesmia2 1department of electrical engineering, faculty of technology, university of batna 2, algeria 2department of electrical engineering, faculty of technology, university of m’sila, algeria ouskador@gmail.com abstract – brushless doubly fed induction generators (bdfig) show commercial promise for wind-power generation due to their lower capital and operational costs and higher reliability as compared with doubly fed induction generators. this paper proposes a robust sliding mode control of grid-connected brushless doubly fed induction generator (bdfig). the developed algorithm is based on the decoupling control by using oriented grid flux vector control strategy. the decoupling of the active and the reactive stator powers insures an optimal performance of the bdfig at the sub-synchronous region. the stator of this machine incorporates two sets of three phase windings with different number of poles, power winding (pw) and control winding (cw). the proposed method is tested with the matlab/simulink software. simulation results illustrate the performances and the feasibility of the designed control. . keywords: brushless doubly fed induction generator (bdfig), vector control, sliding mode control (smc), active and reactive power. received: 15/11/2018 – accepted: 17/12/2018 i. introduction brushless doubly fed induction generators (bdfig) remise significant advantages for wind-power generation. the absence of a brush gear increases the reliability of the device and requires less maintenance cost [1]. this configuration is of great importance for offshore and difficult-to-reach installations. moreover, the bdfig manufacturing cost is very less compared to the doubly fed induction generator [2] [3]. this fact is due to the absence of slip-ring system and the simple structure of the rotor winding. recently, research efforts are directed towards eliminating the slip rings and brushes while maintaining the benefits of dfig.. in literature, several bdfig scalar control algorithms are proposed. for instance, it is shown that the open-loop control, the closed-loop frequency control and the phase angle control can stabilize the machine over a wide speed range. however, the vector control (vc) methods, also known as field-oriented control, give better dynamic performance [3] [4]. this last can be implemented with a conventional proportional plus integral (pi) controller [57]. in general these control proposals are intrinsically based on taylor’s linearization of the system dynamic model around a particular operational point. therefore, the tuning of the controller is only valid in a restricted operational area. on the other hand, these controllers are not robust against parameter variations, model uncertainties and external perturbations, and can present an asymptotic convergence. their main advantage lies in their relatively simple implementation with a rather low computational cost. figure 1. schematic diagram of bdfig wind power generation system mailto:ouskador@gmail.com o.moussa et al ijeca-issn: 2543-3717. december 2018 page 23 more accurate methods are developed based on different nonlinear control techniques. for instance, neural networks [8], feedback linearization [9], variable structure control [10], fuzzy logic control [11, 12], combinations of some previous techniques [13] , and other nonlinear approaches are possible design alternatives. despite the recognized advantage of using nonlinear controllers to cope with nonlinear systems, many of these techniques produce control laws with a rather high computational burden. these calculi commonly depend on the system states and on several model parameters having the secondary effect of reducing the control robustness. this paper a new variable structure controller using a dynamic model with a unified reference fame based on the power winding flux oriented controlled is proposed, the sliding mode control (smc) is conception for the power loop of the outer loop associated to power flux oriented vector control scheme. ii. theory of operation the brushless doubly fed machine (bdfig), also known as a self-cascaded machine. as shown in fig. 1, the stator of this machine incorporates two sets of three phase windings with different number of poles. the first one, called power winding (pw), is connected directly to the grid and handles most of the machine power. the other one, called control winding (cw), is connected via a bi-directional converter to the grid and handles a small percentage of machine power. the rotor of the bdfig carries special design cage (sarasola 2008; williamson et al. 1997). typically the two stator supplies are of different frequencies, one a fixed frequency supply connected to the grid via switch, and the other a variable frequency supply derived from a power electronic frequency converter (inverter), as illustrated in fig. 1. the bdfig can be operated in several modes, including the synchronous (doubly fed) mode, cascade mode, and induction mode (shao et al. 2009). the synchronous mode is the most desirable mode in which the shaft speed is independent of the torque exerted on the machine. this is achieved when the following two relations are satisfied (williamson et al. 1997). (1) (2) sc sp r c p r c p p p n p p         where wsp and wsc are the electrical angular velocities of the pw and cw voltages, and wr is the rotor angular speed. pp and pc are the number of pole pairs of pw and cw respectively, in our case pp=3 and pc=1 and nr is the number of rotor bars. the ± sign accounts for the case which the cw is excited in positive or negative phase sequence as illustrated in fig. 2. figure 2. different reference frame in bdfig if the conditions stated in eqs (1) and (2) are satisfied, then a cross coupling between the two stator fields will occurs via the rotor, and hence a nonzero average torque will be produced. this mode of operation the bdfig is called ‘‘synchronous mode’’. to avoid the direct mutual coupling between the two stator field windings their number of poles should be different (sarasola 2008) iii. mathematical model of bdfig the bdfig equations obtained in the (d, q) reference frame depicted in fig. 2, that rotates synchronously with the power winding stator flux by angular speed of wsp [15][16] can be expressed as (3) sp sp sp sp sp sc sc sc c sc sc r r r r r r sp sp sp p r sc sc sc c r r r r c sc p sp d v r i jsp dt d v r i j dt d v r i j dt l i m i l i m i l i m i m i                                * * 3 3 im . im . (4) 2 2 em p sp sp c sc sc t p i p i    where: vsp, vsc and vr are the pw, cw and rotor winding voltage vector respectively. rsp, rsc and rr the pw, cw and rotor resistances. lsp , lsc and lr are the self-inductances of the pw, cw and rotor winding respectively. mp is the mutual inductance between the pw and the rotor. mc is the mutual inductance between the cw and the rotor. o.moussa et al ijeca-issn: 2543-3717. december 2018 page 24 φsp , φsc and φr are the pw, cw and rotor flux space vector respectively. the powers winding active and reactive power are expressed as:   3 2 d d q q sp sp sp sp sp p v i v i  (5)   3 2 q d d d sp sp sp sp sp q v i v i  (6) current-flux equations: d sp p r sp sp m i i l    (7) r p sp c sc r r m i m i i l     (8) equation (9) is obtained by replacing eq. (8) in eq. (7): 2 2 2 pr sp sp r sp r p sp r p c p sc sp r p ml i l l m l l m m m i l l m         (9) the eq. (10) is obtained by substituting eq. (9) in eqs.(5) and (6):     5 4 3 5 4 3 (10) 3 2 3 2 q q q sp sp sp r sc d d d sp sp sp r sc p v i q v i                      with; 2 1 2 32 2 2 4 52 2 , , , c sp c sp c p sc sp r p sp r p sp r p p r sp r p sp r p m l m l m m l l l m l l m l l m m l l l m l l m                 from eqs. (3–10), the dynamic relation between the cw current and the voltage in the d-q axis (vsc and isc) is given as follows:         1 2 1 2 3 1 2 1 2 3 (11) q q q q d d d sc sc sc r sc sc r sc sp d d d d q q q sc sc sc r sc sc r sc sp d v r i i i dt d v r i i i dt                                               v. power decoupled control the target of the vector control is to achieve independent control of the active and reactive power of the pw. this can be fulfilled using the vector control technique described in the following section. the model of the bdfg is derived in the pw synchronously rotating d-q reference fame with the daxis aligned with the pw flux. accordingly d sp sp    . but there is no component in the q-axis 0 d sp sp q sp         (12) to simplify calculations, let us assume that the resistance of the stator winding rsp is ignored, the voltage equations of the stator windings (pw) can be simplified in steady state as following [17]: 0 d sp q sp sp v v v      (13) replacing eqs. (13) and (12) in eq. (10), the power expressions become:     4 3 5 4 3 (14) 3 2 3 2 q q q sp sp r sc q d d d sp sp sp r sc p v i q v i                    iv. sliding mode power controller design sliding mode controller (smc) is a powerful nonlinear controller which has been analyzed by many researchers especially in recent years [18, 19]. this method forces the system to slide along a predesigned sliding mode surface and alters the dynamic of system by using a discontinuous control signal [20]. this last allows the switch at any time between the different structures. thus, it combines the useful properties of each of these structures in order to obtain the desired system behavior. in fact, the lyapunov like stability condition guarantees that the distance between the system state and the surface decreases along all system trajectories and constrains the trajectories to move toward the sliding surface [21]. the advantages of the sliding mode controller can be summarized as follows [22]:  fast response with no overshoot.  no steady state error.  robustness, stability in a closed loop environment, insensitivity to parameter variations and load disturbances. o.moussa et al ijeca-issn: 2543-3717. december 2018 page 25 one considers the system described by the following state space equation:         (15)x a x b u  with,   nx r is the state vector   mu r is the control input vector;  a and  b are system parameter matrices. the first phase of the control design consists of choosing the number of the switching surfaces  s x . generally this number is equal the dimension of the control vector  u . in order to ensure to convergence of the state variable to its reference value ref x ,[23] proposes a general function of the switching surface:     1r d s x e x dt           (16) whereis a strictly positive constant. ensure controllability;   r e fe x x x  is the error variable. the second phase consists to find the control law which meets the suiciency conditions for the existence and reachability of a sliding mode such as [24]     0 (17)s x s x  intuitively, the existence of a sliding mode on the sliding surface implies stability of the system. one of the possible solutions is given by:   (18)equ t u u   ueq is the so-called equivalent control. it plays the feedback linearization role is the solution of   (19) ds s x s x dt x t                  (20)eq ds s s s x a x b u b u dt x t           during the sliding mode, the u is equal zero, then ueq is        1 (21) eq s s u b a b x x        with:   0 s b x    during the convergence mode, the 0u  substituting (21) in to (20), yields     (22) s s x b u x      substituting (22) in to (17), obtain:     0 (23) s s x b u x     so that the state trajectory is attracted toward the switching surface   0s x  . a commonly used from of is a constant relay control.   (24)xu k sign s x   sign s x : is a sign function, which is defined as:       1 0 (25) 1 0 if s x sign s x if s x         where kx determine the ability of overcoming the chattering. in order to reduce the chattering phenomenon caused by the discontinuous nature of the controller, a smooth function is used in some neighborhood of the sliding surface. vi. sliding mode control of bdgif in this section, the sliding surfaces are defined based on the active and the reactive power references given in the eq. (14). the main objective of this design is to independently control the active and reactive generated powers. a. choice of the sliding surfaces in this work, two sliding surfaces are used and taken as follows since a first order is defined as:  ( ) 26refsp sps p p ( ) (27) ref sp sp s q q where ref sp p and ref sp q are the expected active and reactive power reference. b. conditions of convergence to insure the convergence of selected variables towards the references, the two slip surfaces need to be null as following: (28) ( ) 0 ( ) 0 ( ) 0 ( ) 0 ref sp sp sp refsp sp sp d p p s p dt s q d q q dt                the realization of a sliding mode control relies on the lyaponov attractively . ( ( ) ( ) 0)s x s x  and the surface time invariance . ( ) 0s x  c. development of the control laws the algorithm of control is defined by the relation: o.moussa et al ijeca-issn: 2543-3717. december 2018 page 26 d d eq d attr sc sc sc q q eq q attr sc sc sc v v v v v v         d sc v , q sc v : is the control vector. d eq sc v  , q eq sc v  : is the equivalent control vector. d attr sc v  , q attr sc v  : is the switching part of the control. to control the power one takes r=1, the expression of the surface has as a form: ( ) ( ) (29) ( ) ( ) ref sp sp sp ref sp sp sp s p p p s q q q          the derivative of surface: . . ( ) ( ) 0 (30) . . ( ) ( ) 0 ref sp sp ref sp sp d s p p p dt d s q q q dt             one draws the expression. from . ref spp , . spp , . ref sp q , . sp q   4 3 (31) . . .3 2 ref q q q sp r scsp sp s p p v i                  5 4 3 . . . .3 (32) 2 ref d d d q sp r scspsp sp s q q v i                  substituting the current expression , )( d q sc sc i i into (31-32), obtains:     4 3 2 2 1 1 2 3 2 2 4 5 3 2 . ( ) ( . 3 (33) .2 ( ) ) . . ( ) ( . 3 2 2 q q eq q attr qsc sc s r scref q spsp sp q d d dc rr sc sp d d d eq d attr sc sc r sp ref q spsp sp ds sc v v r i s p p v i v v s q q v r i                                                                    1 1 2 2 2 (34) . ( ) ) d q qc rr sc i                              the equivalent control winding current vector q sc v can express by: 2 4 1 2 1 3 2 4 1 2 3 1 3 . . . ( ) (35) 1.5 . . . ( ) (36) 1.5 ref d d spd eq d q q r rsc s sc c r scq sp ref q q spq eq q d d d r rsc s sc c r sc spq sp v r i i v p v r i i v                                                         attr sc v is the sign function defined by: ( ( )) (37) ( ( )) (38) d attr sc d sp q attr sc q sp v k sign s q v k sign s p     where kd,kq determine the ability of overcoming the chattering. the smc control is conception for the power loop of the outer loop associated to power flux oriented vector control scheme, to further enhance the robustness of the system path as shown in figure 3 vii. simulation results to confirm the electiveness of the proposed smc algorithm for bdfig it is simulated in the environment of matlab/simulink to investigate the dynamic performance of the (bdfig.) the parameters of the bdfig are given in the appendix (table i) [13]. figure 4 are the simulation results for active and reactive power response in case of fixed speed operation when traditional pi controller (fig. 4(a)) and sliding mode control (fig. 4(b) ) is applied. in this case study, simulation results show clearly the improvement of active and reactive power demand obtained by applying sliding mode control in term of time response and good reference tracking accuracy than those obtained using traditional pi regulator. we notice here, in case of step change, that the sliding mode controller transient responses of both active and reactive powers present no overshoot whereas the steady state error is close to zero. figure 3. sliding mode control block diagram of bdfig. o.moussa et al ijeca-issn: 2543-3717. december 2018 page 27 p s p (w a t) q s p (v a r) p s p (w a t) q s p (v a r) figure 4. active and reactive power response of stator (pw) i s p (a ) figure 5. phase power winding current i s c (a ) figure 6. phase control winding current the frequency and amplitude of the control winding current both change during the period of the active and reactive power variation, the frequency of power winding current is constants accorder to power frequency of the grid with amplitude change when the reference of the active power is modified as shown in fig. 5and 6. viii. conclusion this paper presents a comparative study on the performance of two control strategies; vector and sliding mode controller applied on a bdfig wind turbines when operated in power regulation mode. this last, can control the stator (pw) active and reactive powers independently with desired performances of stability and robustness. therefore, the obtained results demonstrate the efficiency of the adopted control structure. it can be concluded that the proposed bdfig system control is an interesting solution in the wind energy conversion systems. appendix table. i electrical parameters of prototype bdfig for simulation power winding (pw) control winding (cw) rotor resistance (ω) rsp=1.732 rsc=1.079 rr=0.473 self inductance (mh) lsp=714.8 lsc=121.7 lr=132.6 mutual inductance (mh) mp=242.1 mc=59.8 pole pair numbers pp=3 pc=1 references [1] p. farrokh, m. jalalifar, robust speed sensorless control of doubly-fed induction machine based on input-output feed back linearization control using a sliding-mode observer, international proceedings of the ieee international conference on power electronics, drives and energy systems, 2006. pp. 1-5, [2] r. a. mcmahon, x. wang, e. abdi, p. j. tavner, p. c. roberts, and m. jagiela, the bdfm as a generator in wind turbines, in proc. 12thint. power electron. motion control conf, 2008. pp. 1859-1865, [3] s. shao, e abdi, f barati, r. mcmahon, flux-oriented vector control for brushless doubly fed induction generator, ieee transactions on industrial electronics, vol. 56, no.10, 2009. pp. 4220-4228, [4] r. mcmahon, x. wang, e abdi, m. jagiela, the bdfm as a generator in wind turbines, in: proceedings ofthe 12th international conference on power electronics and motion control, 2006. pp. 1859-1865, [5] k. protsenko, d. xu, modeling and control of brushless doubly-fed induction generators in wind energy applications, ieee transactions on power electronics, vol. 23, no. 3, pp. 1191-1197, 2008. [6] i. sarasola, robust control of doubly fed induction machine by the stator power generation applications at variable speed. dissertation for the doctoral degree, basque: university of mondragon, 2008. [7] s. williamson, s. ferreira, a. k. wallace, generalized theory of the brushless doubly-fed machine 2. model verification and performance, ieee proceedings—electric power application, vol. 44, no. 2, 1997. pp. 111-122, [8] j. poza, e. oyarbide, m. rodriguez, unified reference framed model of the brushless doubly fed machine, ieee proceedings-electric power application, vol. 153, no.5, 2006. pp. 726-734, [9] a. tamaarat, a. benakcha, performance of pi controller for control of active and reactive power in dfig operating in a grid-connected variable speed wind energy conversion system, frontiers in energy, vol. 8, no.3, 2014. pp. 371378, o.moussa et al ijeca-issn: 2543-3717. december 2018 page 28 [10] o. soares, h. goncalves, a. martins, a. carvalho, nonlinear control of the doubly fed induction generator in wind power systems. renewable energy, vol.35, no. 8, 2010. pp. 1662-1670, [11] a. dida, and d. b. attous, doubly-fed induction generator drive based wecs using fuzzy logic controller, frontiers in energy, vol. 9, no. 3, 2015. pp. 272-281, [12] b. boukhezzar, and h. siguerdidjane, nonlinear control with wind estimation of a dfig variable speed wind turbine for power capture optimization, energy conversion and management, vol. 50, no.4, 2009. pp. 885-892, [13] m. a. mahboub, and s. drid, sliding mode control of a brushless doublyfed induction generator, in proceedings of ieee (icsc) the 3rdintel conference on systems and control, 2013.pp. 308-313, [14] r. yazdapanpanah, g. r. markadeh, nonlinear torqueand stator flux controller for induction motor drive based onadaptive input–output feedback linearization and sliding mode control, energy conversion and management, vol. 49, no. 4, 2008. pp. 541-550, [15] r. mcmahon, x. wang, e abdi, p. tavner, m. jagiela, the bdfm as a generator in wind turbines, in proceedings of 12th international conference on power electron, 2006.pp.1859-1865, [16] k. protsenko, d. xu, modeling and control of brushless doubly fed induction generators in wind energy applications, ieee trans power electron, vol.23, no.3, 2008. pp. 1191-1197, [17] t. mesbahi, a. ouari, t. ghennam, e. berkouk, n. mesbahi, ahybrid wind energy conversion system/active filter for nonlinear conditions, int j syst assur eng manag, vol. 6, no. 4, 2011. [18] b. beltran, m. benbouzid, t. ahmed-ali, h. manfel, dfig based wind turbine robust control using high-order sliding modes and a high gain observer, international review on modelling and simulations, vol.4, no.3, 2011. pp. 1148-1155, [19] a. abdellah, a. abdelhafid, r. mostafa, combining sliding mode and linear quadratic regulator to control the inverted pendulum, international review of automatic control, vol. 6, no.1, 2013. pp. 69-76, [20] f. yong, c. bing, y. xinghuo, and y. yongmin, terminal sliding mode control of induction generator for wind energy conversion systems, 38th annual conference on ieee industrial electronics society, 2012. pp.4741-4746, [21] g. andrade, d. pangano, j. lvarez, m. berenguel, sliding mode control of distributed parameter processes: application to asolar power plant, j control autom electr syst, vol. 25, no. 3, 2014. pp.291-302, [22] f. benchabane, a. titouine, o. beennis, k yahia, d. taibi, fuzzy sliding mode control for permanent magnetsynchronous motor fed by ac/dc/ac converter, int j syst assur eng manag, vol. 6, no.2, 2013. pp.192-199, [23] o. zouaid, l. nezli, control with sliding mode of a fivephase series-connected two-asynchronous motor drive. international journal of energetica (ijeca), vol.3, issue 1. 2018. [24] v. utkin, variable stucture systems with sliding modes-a survey, ieee trans automat control, vol. 22, no.2, 1977. pp. 212-222, i. introduction appendix references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 17-22 ijeca-issn: 2543-3717. june 2019 page 17 feasibility study based on economic perspective of cobalt nanoparticle synthesis with chemical reduction method fira nandatamadini, suci karina, asep bayu dani nandiyanto * , risti ragadhita departemen kimia, universitas pendidikan indonesia, jl. dr. setiabudi no 229, bandung 40154, jawa barat, indonesia email*: nandiyanto@upi.edu abstract – cobalt nanoparticle powder is synthesized by a chemical reduction method. in short, it is synthesized through reduction of cobalt ions that are dissolved in aqueous solution by boronrelated solution with cationic surfactant. cobalt nanoparticles have many applications, especially in the field of engineering. the successful project for the production of cobalt nanoparticles will produce opportunities that make it possible to advance technology in developing countries. for this reason, a feasibility study for the synthesis of cobalt powder nanoparticles is needed. this project has estimated ideal conditions for worst cases that will occur in production by adding several parameters: raw materials and sales. evaluation of this feasibility study is using two parameters, which are economic analysis and evaluation techniques, including gross profit margin (gpm), cumulative net present value (cnpv), break-even point (bep), payback period (pbp) this parameter to show potential profitability for the project. the irr value of this project that it is not very promising, but all evaluations with various parameters have a positive impact. the project also uses the method of reducing metal salt an easy and the total cost of purchasing relatively inexpensive equipment will provide benefits in the project, and investors will attract this project. keywords: cobalt nanoparticles, reduction, mass balance, economic evaluation, feasibility study received: 05/01/2019 – accepted: 28/02/2019 i. introduction cobalt (co) is a chemical element in period 4, group 9, and block d element, with an atomic mass of 58.933195. the cobalt atom has a radius of 125 pm and the van der waals radius of 192 pm. in its elemental form, cobalt is gray and shiny. cobalt releases blue pigments and has been used in a long time for paint and glass colors. cobalt is a ferromagnetic metal, used in the production of very hard and magnetic super alloys [1]. metallic nanoparticles have been used for many applications in various fields such as catalysis, photonics, and electronics [2]. several preparation routes have been reported for the preparation of metallic nanoparticles, such as salt reduction [3], reverse micelles [4], ultrasonic irradiation [5], microwave dielectric heating reduction [6], radiolysis [7], electrochemical synthesis [8-9] and thermal synthesis [2, 10]. co nanoparticle powders were synthesized through chemical reduction methods by several researchers [11]. cobalt (ii) is reduced by a chemical reduction reaction, by adding sodium borohydride at a controlled rate, with a concentration of sodium hydroxide, which varies in reducing solution. the synthesized particles are about 20100 nm in size [12]. applications of co nanoparticles are in the field of separation technology, information storage systems [13], catalysis, and biomedicine requiring discrete nanoparticles [14], identical in shape and size, and uniform in composition and crystal structure [15]. however, the formation of nanoparticles that meet these requirements has proven difficult because of their high surface energy, intrinsic magnetic properties, and inherent limitations available [16]. so far, the liquid phase synthesis route is the most successful in preparation of monodispers co nanoparticle. examples of liquid phase processes are metal salt reduction, reverse micelles, and organometallic precursor thermal decomposition. among these methods, the method chosen in this study was the reduction of direct metal salt in solution because it was the simplest, fastest, cheapest, and desired in large-scale production [17]. in order to uttermostly use the material, nanotechnology is required to support new technology [17]. in a chemical industry, research and development is very important. this is including what kind of product, which route to produce, and which technology will be used. an industry is frequently asked about the directions regarding the issues in current or future time that are faced by the industry [18-20]. the economic evaluation analysis is used to analyze the feasibility study of cobalt abder image placée fira nandatamadini et al ijeca-issn: 2543-3717. june 2019 page 18 nanoparticle synthesis using chemical reduction method. the economic evaluation of the chemical industry is a form of quantitative assessment of what is expected and desired by the community to carry out the investment process in a project [21-22]. this evaluation analysis uses several parameters, like calculating gross profit margin (gpm) which is the first analysis to determine the level of profitability of a project from economic conditions; calculate the internal rate of return (irr) to ensure economic conditions; calculating break-even point (bep) states the drinking capacity where the project does not benefit. this bep is an important factor to avoid the project losses; calculate the payback period (pbp) to predict the length of time it takes for an investment to be able to return the initial total expenditure [21, 23]; the cumulative net present value (cnpv) is calculated to predict the condition of the project as a function of the production year or cnpv can be obtained as the number of cumulative financial flows each year; calculate the profitability index (pi) to obtain information about profits. data for chemicals, equipment specifications and labor are needed to support the economic evaluation analysis. then the data was calculated to analyze the industrial feasibility study of making cobalt nanoparticles powder, which was designed to fit the feasibility test or not to be established. for the industry, feasibility study is very important to support the optimization of the project’s economic growth at this time. cobalt nanoparticles are needed especially in the technological applications, for example, as medical sensors; biomedicine as a contrast agent for magnetic resonance imaging (mri); coatings, plastics, nanofibers, nanowires, textiles, high-performance magnetic recording materials; magnetic fluids-made of iron, cobalt, nickel and mixed nanoparticles; and as microwave absorbing material [24]. therefore, the success of this project will create job opportunities that have a direct impact on reducing poverty and advancing technology, specifically in developing countries. all calculations in economic evaluation research are carried out in ideal conditions. additional variables are put to calculations such as raw materials, product sales, and cnpv analysis based on changes in variable cost. ii. method the economic feasibility study method is used to analyze the price, components, and specification of apparatuses [19] which obtained from sigma-aldrich and other online shopping webs such as alibaba.com. data were obtained later with mathematical analysis to obtain economic evaluation parameters such as gpm, irr, pbp, cnpv, bep and pi sales to investment. economic evaluation parameters are calculated based on literature [12]. calculations use the following formula: (1) gpm is calculated by reducing the costs of raw material and sales results. (2) pbp is a calculation to predict the length of time which takes an investment to be able to return the initial total expenditure. in short, pbp is calculated based on when cnpv reaches zero for the first time. (3) irr was calculated from the following equations: where, co and ct are the total investment costs and the net cash inflow during the t period, respectively. t is time (as year) and r is the discount rate. (4) cnpv is a value obtained from net present value (npv) at a certain time. cnpv is obtained with adding of the npv value from the beginning of the project. npv is calculated by multiplying cash flows by a discount factor. (5) calculating bep by dividing fixed costs and profits. (6) estimating the pi by dividing the cnpv with the sales or total investment cost, based on profit on sales or the type of pi profit for investment, respectively. when evaluating the economic feasibility, various conditions were tested such as changes in raw materials, sales capacity and variable cost variations. iii. result and discussion iii.1. engineering perspective co nanoparticle production was carried out based on the literature [12]. the most successful route of liquid phase synthesis in the preparation of nanoparticles co is monodispers. an example of a method in the liquid phase is the reduction of metal salt. the method of reducing metal salts directly in solution is chosen because of the simplest, fastest, and cheapest method. the systematics of the process carried out in this economic feasibility study is shown in figure 1. figure 1. flowchart of co nanoparticle synthesis process fira nandatamadini et al ijeca-issn: 2543-3717. june 2019 page 19 the steps for the synthesis of co nanoparticles were as follows: a total of 23.76 g cobalt (ii) chloride hexahydrate with 97% purity were added to the reaction flask beaker and 9.12 g ctab with 99% purity was added. ctab is a cationic surfactant (surface active agent) and is added because its addition is expected to facilitate pore formation. then 1 l of distilled water was added, and the beaker reaction flask was closed using a 3-neck reaction flask. stir the mixture using a magnetic stirrer while being purged with high-purity nitrogen gas. a total of 37.84 g sodium borohydride (nabh4) solids with 98% purity were used as reducing agents were also dissolved in 1 l of distilled water in the beaker reaction flask, which was also fed with high-purity nitrogen gas. then, the reducing solution (nabh4) is added slowly to a solution containing a solute to prevent a sudden reaction due to ctab, which can cause boiling over. during this process, nitrogen gas is purged continuously. after the reaction is complete, the solution is filtered and washed with distilled water and ethanol to prevent oxidation. the prepared powder is then dried. the following is the co nanoparticle formation reaction mechanism using chemical reduction: 4co2 + + bh4 − + 8oh − → 4co + bo2 − + 6h2o as shown in figure 1, the yield of the production has been calculated by mass balance stoichiometry [25], based on 24 l of cobalt solution, with the following assumptions: (1) all compositions of chemicals used such as cobalt (ii) chloride hexahydrate, ctab, and sodium borohydride used for the synthesis of cobalt nanoparticles are based on the literature[12]. (2) the rate of conversion of nanoparticle co formation is 90% (3) losses caused by washing with ethanol are 10%. based on the assumption above, it takes 570.24 g of cobalt (ii) chloride hexahydrate, 218.88 g of ctab, 908.16 g of sodium borohydride, ethanol, and water to produce 543 g co nanoparticles in a day. co nanoparticle production is obtained every day which is 108 products (per 5 grams), so that in one year it will produce as many as 32400 nanoparticle co products (per 5 grams). iii.2. economic evaluation in ideal condition the cnpv curve with economic evaluation indicators that vary in ideal conditions is presented in figure 2. the analysis results show that the synthesis of co nanoparticles from cobalt (ii) chloride hexahydrate is quite profitable. technical analysis explains that the preparation can be improved using currently available technology, with equipment that is reasonably priced. the results of the economic evaluation also showed very promising results, because of the positive value of the economic parameter values. however, to return the initial total expenditure on the project, it takes around 2 years. figure 2. curve of the ideal condition of the cnpv under various indicators of economic evaluation the ideal cnpv curve as shown in figure 2 is obtained by the following assumptions: (1) materials used in the production nanoparticles co were estimated based on the stoichiometric calculation. (2) the process neglected other supporting fees (e.g. instrumentation, plant start-up, electrical-related component). (3) calculations using idr (indonesian currency). then, the value is converted to usd with a fixed value of 1 usd = 10000 idr (4) prices of commercial raw materials obtained from available online sites. the price of cobalt (ii) chloride hexahydrate is 1.5247 usd / gram, ctab 2.4526 usd / gram, and sodium borohydride 1.3297 usd / gram (5) the raw materials used for production are calculated according to stoichiometric calculations. (6) the electricity price is 24.9375 usd / day. (7) labor is paid at 8 usd / day (8) the duration of the project is 20 years. iii.3. economic evaluation in non-ideal condition figure 3 confirms the effect of raw material prices and sales on the gpm, where gpm is calculated by reducing sales revenue and production prices. the most influential indicator in the raw material of this project is sodium borohydride because it has the highest prices compared to other raw materials. sodium borohydride is an important factor in the method used for the synthesis of nanoparticles co as a reducing agent and more needed raw materials. fira nandatamadini et al ijeca-issn: 2543-3717. june 2019 page 20 figure 3. effect changing raw materials and sales on the gpm the curve analysis in figure 3 shows that the higher the price of raw materials, it will have a negative impact on the project because it produces a low gpm value, which means it produces fewer sales that will be loss to the project. otherwise, if the price of raw materials is lowered and the value of gpm is high, it will produce more sales that will benefit the project. on the sale of nanoparticles co it will be profitable if the sales price is increased by more than 100% because it shows a positive gpm value. cnpv analysis based on changes in variable cost is shown in figure 4. figure 4. cnpv curve below the various variable cost values the variable cost in analysis result plays an important role in profits, which the decrease in variable cost affects the high value of final cnpv. relating to increasing variable cost, the project will suffer losses. but, when using a lower variable cost value, the project will be more effective in producing more profits. when using production that is more than 100% variable cost, minimum pbp cannot be achieved. in fact, this can make the project unprofitable. the maximum value in varying sales must be less than 100% of the estimated value, in order to support the project. iii.4. result from engineering perspective in terms of engineering, it can be seen the possibility in the scaling up process. this is because the scaling up process can be applied using generally available and cheap equipment. the plan suggested in the future with a project that has 28800 cycles per year is to produce co nanoparticles of 171.072 kg from an amount of 163.1232 kg cobalt (ii) chloride hexahydrate per year. in ideal conditions, the project can reach 28800 cycles per year, which can produce 163.1232 kg of nanoparticle co per year. by calculating the length of the project for 20 years, the results show that the entire project can produce an amount of 3.262464 tons products in ideal conditions. iii.5. result from economic evaluation based on the analysis of the data produced, the project is feasible to run in ideal conditions. however, the project will be profitable under certain conditions if there are changes in certain situations so the project can no longer be run. the specific conditions based on the analysis of economic feasibility studies can be explained. the project will be profitable if the increase in raw material costs is less than 150% of the estimated raw material costs, and the impact of the gpm value of each raw material in the synthesis of co nanoparticles varies. the most influential raw material is sodium borohydrate. to keep the project runs and get profit, product sales must be as high as possible. however, the increase in sales must keep optimized because of its relation with other costs. when there are conditions to reduce sales, sales must remain higher than 100% of the estimated value. otherwise, the project will be unprofitable. this is because the minimum costs for production cannot be obtained if sales are too low. table 1. the estimate of gross profit margin on nanoparticle cobalt production in addition to the economic outlook, a project feasibility analysis also needs to be carried out. in this project, gpm in table 1 and bep in table 2 shows a positive value, which mean that this project is feasible to run. another economic analysis factors such as pbp, and cnpv provide highly profitable prospects from investors. pbp analysis shows that investment will be profitable after more than 2 years. it could be that this project can be competed with pbp capital market standards because the investment will return in a short period of time. regarding the parameters, the irr in table 2 value shows 15% for 20 years of project life. this value gives a nanoparticle price (usd / 5 gram) approx. gpm (usd/day) nanoparticle co 28 373 fira nandatamadini et al ijeca-issn: 2543-3717. june 2019 page 21 relatively low yield per year. this irr value indicates that this project is not promising. however, based on the final cnpv parameters, the value is quite high for projects with 20 years of life time. this result is also reinforced with the relatively high values for pi. of course, this typical long-term investment will provide a very interesting perspective for investors [26]. table 2. economic parameters for the production of nanoparticle cobalt product parameters nanoparticle cobalt profit-toinvestment (%) 588.55 pbp (years) 2 irr (%) 15 bep (cycle) 8.9 last cnvp (%) 102533.53 iv. conclusion this study shows the engineering perspective and economic evaluation in production of co nanoparticles. pbp analysis shows that investment will be profitable after more than 2 years. it could be that this project can compete with pbp capital market standards because the investment will return in a short period of time. it can be seen from the irr value of this project that it is not very promising, but there are other parameters that have a positive impact on attracting investors in this project. some of the things that affect these benefits include using a chemical reduction method, because this method is very easy and cheap. from this analysis of economic evaluation, we can conclude that this project is feasible to run. references [1] t. d. jickells, j. d. burton. “cobalt, copper, manganese and nickel in the sargasso sea”, marine chemistry, vol. 23, issue (1-2), 1998, pp. 131-144. [2] m. g guzmán, j. dille, s. godet, “synthesis of silver nanoparticles by chemical reduction method and their antibacterial activity”, int j chem biomol eng, vol. 2, issue (3), 2009, pp. 104-111. [3] z. s. pillai, p. v. kamat, “what factors control the size and shape of silver nanoparticles in the citrate ion reduction method?”, the journal of physical chemistry b, vol. 108, issue (3), 2004, pp. 945-951. [4] m. maillard, s. giorgio and m. p. pileni, “silver nanodisks”, advanced materials, vol. 14, issue (15), 2002, pp. 1084-1086. [5] r. a. salkar, p. jeevanandam, s. t. aruna, y. koltypin, a. gedanken,“the sonochemical preparation of amorphous silver nanoparticles”, journal of materials chemistry, vol. 9, issue (6), 1999, pp. 1333-1335. [6] k. patel, s. kapoor, d. p. dave, t. mukherjee, “synthesis of nanosized silver colloids by microwave dielectric heating”, journal of chemical sciences, vol. 117, issue (1), 2005, pp. 53-60. [7] b. soroushian, l. lampre, j. bellono, m. mostafavi, “radiolysis of silver ion solutions in ethylene glycol: solvated electron and radical scavenging yields”, radiation physics and chemistry, vol. 72, issue (2-3), 2005, pp. 111-118. [8] j. j. zhu, x. h. liao, x. n. zhao, h. y. chen, “preparation of silver nanorods by electrochemical methods”, materials letters, vol. 49, issue (2), 2001, pp. 91-95. [9] s. liu, w. huang, s. chen, s. avivi, a. gedanken, “synthesis of x-ray amorphous silver nanoparticles by the pulse sonoelectrochemical method”, journal of noncrystalline solids, vol. 283, issue (1-3), 2001, pp. 231-236. [10] n. permatasari, t. n. sucahya and a. b. d. nandiyanto, “agricultural wastes as a source of silica material”, indonesian journal of science and technology, vol. 1, issue (1), 2016, pp. 82-106. [11] j. lu, d. b. dreisinger, w. c. cooper, “cobalt precipitation by reduction with sodium borohydride”, hydrometallurgy, vol. 45, issue (3), 1997, pp. 305-322. [12] s. h. hong, y. m. jin, k. t. kim, c. w. ahn, d. s. park and m. y. song,“synthesis of nanocobalt powders for an anode material of lithium-ion batteries by chemical reduction and carbon coating”, journal of nanomaterials, 2014, vol.11. [13] m. maamir, a. betka, h. aboub, “modeling and simulation of energy management hybrid sources system composed of solar-pv and battery”, international journal of energetica, vol. 1, issue (1), 2016, pp. 12-19. [14] r. h. kodama, “magnetic nanoparticles”, journal of magnetism and magnetic materials, vol. 200, issue (1-3), 1999, pp. 359-372. [15] c. zhu, g. yang, h. li, d. du, y. lin, “electrochemical sensors and biosensors based on nanomaterials and nanostructures”, analytical chemistry, vol. 87, issue (1), 2014, pp. 230-249. [16] m. d. l. balela, “synthesis and characterization of cobalt nanoparticles prepared by liquid-phase reduction”, doctoral dissertation, universiti sains malaysia, 2008. [17] l. mulfinger, s. d. solomon, m. bahadoru, a. v. jeyarajasingam, s. a. rutkowsky and c. boritz, “synthesis and study of silver nanoparticles”, journal of chemical education, vol. 84, issue (2), 2007, pp. 322. [18] k. kurnia, a. b. d. nandiyanto, r. ismiati, a. annisa, f. finandia, n. n. a. nissa1, r. c. dewi,“economic evaluation analysis of nano-silica ultrafiltration membrane production from sand”, international journal of energetica, vol. 3, issue (1), 2018, pp. 06-09. [19] z. a. putra, “early phase process evaluation&58; industrial practices”, indonesian journal of science and technology, vol. 1, issue (2), 2016, pp. 238-248. [20] l. jebali, a. kacem, “impact of fuel energy prices in tunisia”, international journal of energetica, vol. 3, issue (1), 2018, pp. 24-30. [21] a. b. d. nandiyanto, t. a. aziz, r. fariansyah “engineering and economic analysis of the synthesis of fluoride tin oxide film production”, international journal of energetica, vol. 2, issue (2), 2017, pp. 15-17. [22] m. jahangiri, “optimal planning of on-grid hybrid microgrid for remote island using homer software, kish in iran”, international journal of energetica, vol. 3, issue (2), 2019, pp. 13-21. [23] r. andika, v. valentina, “techno-economic assessment of coal to sng power plant in kalimantan”, indonesian journal of science and technology, vol. 1, issue (2), 2016, pp. 156-169. fira nandatamadini et al ijeca-issn: 2543-3717. june 2019 page 22 [24] m. imadadulla, n. manjunath, l. s. koodlur, “solvent dependent dispersion behaviour of macrocycle stabilized cobalt nanoparticles and their applications”, new journal of chemistry, 2018. [25] a. boukhari, “numerical investigation of heat and mass transfer processes while the desorption of hydrogen gas stored in mmni4. 6fe0. 4-h6”, international journal of energetica, vol. 1, issue (1), 2016, pp. 1-11. [26] h. s. mojaveri, m. daftaribesheli, a. allahbakhsh, “the relationship between social performance and corporate financial performance”, indonesian journal of science and technology, vol. 1, issue (2), 2016, pp. 216-231. i. introduction ii. method iii. result and discussion iii.2. economic evaluation in ideal condition iii.3. economic evaluation in non-ideal condition iii.4. result from engineering perspective iii.5. result from economic evaluation iv. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. no. 2. 2018 page 06-12 ijeca-issn: 2543-3717. december 2018 page 6 modeling and comparative study of speed sensor and sensor-less based on tsr-mppt method for pmsg-wt applications y. saidi 1 , a. mezouar 1 , y. miloud 1 , m. a. benmahdjoub 1 , m. yahiaoui 2 1 laboratory of electro-technical engineering, faculty of technology tahar moulay university of saïda (20000), algeria 2 university of mascara, road of mamounia, mascara (29000), algeria saidi_youcef_20@yahoo.com abstract – this paper aims to present a study and comparison between two approaches for maximizing the power delivered by the wt-s (wind turbine system) which is called (mppt-control) based on tsr method (tip-speed ratio): first method is based on mpc (maximum power control) with wind speed measurement (tsr-mpcwsm) and the second one based on mpc with wind speed estimation (tsr-mpcwse). these methods are analytically compared to illustrate tsrmppt and power smoothing capability delivered by the aerodynamic turbine system. the dynamic performance, robustness and fast approximation of the optimal value are proved with the simulations (matlab/simulink® software). keywords: aerodynamic wind systems, mpcwsm, mppt, mpcwse, tip-speed ratio (tsr), proportional integral (pi), wind turbines systems (wt-s) received: 30/09/2018 – accepted: 13/11/2018 i. introduction wind turbines systems (wt-s) have been widely used both in autonomous systems for power supplying remote loads and in grid-connected applications. although wt-s have a lower installation cost compared to photovoltaic, the overall system cost can be further reduced using high-efficiency power converters, controlled to obtain the optimum power according to current atmospheric conditions [1]. aerodynamic wind systems based on variable-speed turbine have been used for many reasons. among the wecs currently available, variable-speed based on aerodynamic wind systems are steadily increasing their market share, since changes in wind speed are followed by shaft speed control, which allows the turbine to function at its at maximum capacity regardless of wind speeds [2, 3]. one of the most major problems in aerodynamic wind systems is capturing as much aerodynamic wind power as possible in the shortest possible time, which can be achieved through different mppt approaches [4]. in order to determine the optimal operating situation of the wt, it is essential to include a mppt algorithm in the system. much has been written about the subject of of mppt algorithms [5], especially for aerodynamic wind systems. many papers for mppt technique have been presented, with different control schemes of wt-s to extract a maximum of power from wind speed variable, such as reference [6], which provided an analytical and critical study of several papers published in this area including [7, 8]. wind turbines systems are controlled to operate only within a specified range of wind speeds value limited by by cut_in (vcut-in) and cut out (vcut-out) speeds. beyond these bounds, the turbine must be shut down to protect both the generator and turbine. figure. 1 shows the typical power curve of a wt (wind turbine) [9]. (1) (2) (3) wind speed (m/s) vcut-in (4) vrated vcut-out paer pretad figure 1. areas of operation and control wecs it can be seen from figure 1 that there are three different operational regions. the first region is the lowwind-speed region, where the turbine should be stopped and dis-connected from the grid to prevent it from being driven by the generator [10]. the second region is the moderate-speed region which is limited by the cut_in wind speed at which the turbine begins to y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 7 operate and the rated wind speed (vrated), at which the turbine produces its nominal power. the wt produces maximum power in this region, because it is controlled to extract the available wind power. in the high speed region (i.e., between vrated and vcut-in), the turbine power is limited so that the turbine and generator are not over-loaded and dynamic loads do not cause mechanical failure [10, 11]. it should be noted that to protect the turbine against structural overload it should be stopped above the tripping speed (cut-out speed). this article focuses on the moderate-speed region, where the mppt (maximum power point tracking) algorithm is required for optimal operation. although the speed of the wt can be fixed or variable, the maximization of the energy extracted can only be achievable with variable speed wt. since these turbines may change their rotational speed to follow instantaneous changes in wind speed, they are able to maintain a constant rotational speed to wind speed ratio [11]. it can be noted that there is a specific ratio called the optimum tsr (tsr_opt) for each wt for which the extracted power is maximized [6, 11, 12]. this paper presents the fundamentals of mppt algorithms available for aerodynamic wind conversion system. in addition, a comparison of simulation results is made on the two selected mppt approaches. finally, a critical discussion is made and a conclusion is drawn. ii. wind speed modeling wind speed generally has complex random variations, both deterministic effects (mean wind, tower shadow) and stochastic fluctuations over time due to turbulence. generally, the deterministic and stochastic components are superimposed to form the following wind profile model [13]:  ii n i i tavtv    sin)( 1 0 (1) where: 0v , ia , i and i are, respectively, the mean component, magnitude, pulsation and initial phase of each turbulence. in this work we are interested only in much localized wind, the wind on the area swept by the rotor for a few seconds. in addition, to take into account the nature of wind turbulent, stochastic models are also used. the turbulence spectrum endorsed the distribution of turbulent fluctuations energy, whose integral is determined by the intensity of the turbulence. the intensity of the turbulence is the following ratio: 0v i   with the variance  t dttv t 0 2 )( 1 a gaussian process can generate a turbulent wind distribution. therefore, the v. karman spectrum and one kaimal spectrum are the two models used, respecting the standards set by the iec (international electrotechnical commission) [14]: von karman spectrum:   652 ))(1(   t k kaimal spectrum:   35 1   t k where: k is a variable related to the change t , which determines the turbulence bandwidth. fast simulator of the nrel (american national renewable energy laboratory) considers these issues and is described in [15]. in fact, this concept will be used very much in the turbine modeling equations. these equations allow calculation of the average torque actually produced by the wt-s. the danish riso national laboratory developed the wind model based kaimal filter. this model is implemented in matlab/simulink®, as shown in figure. 2. figure 2. fast simulink implementation of aerodynamic wind speed model iii. wind turbine modeling according to aerodynamic characteristics of the wts, the amount of power captured by the wt-s delivered by the rotor is calculated by following formula [16]: 32),( 2 1 vrcp paer  (2) where  is the air density, r is the blade length and v is the wind velocity. the aerodynamic torque is is calculated by the ratio of the aerodynamic power aerp to the shaft speed t : t aer aer p t   (3) in wt-s, the turbine usually associated to the generator shaft through a gearbox whose gear ratio g is chosen to adjust the speed of the generator shaft to a desired speed range. ignoring the transmission losses, the shaft speed and torque of the wt, referred to the gearbox on the generator side, are given by: g t t aer g  , g g t   (4) y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 8 where g is the generator shaft speed, gt is the torque of the generator, respectively. depending on the modeling turbine characteristics, the power coefficient pc can be represented by the following expression [17]:             643 2 1 5 --, cecc c cc i c i p (5) where 1 035.0 08.0 11 3      ii the power coefficient pc depends on the pitch angle  and the ratio  between linear speed at the tip of the blades and the wind speed [18]: v rt  (6) the typical pc versus curve for difference values of pitch angle  is shown in figure.3. in a wt-s, there is an optimum value of tsr for which pc is maximum and that maximizes the power for a certain wind speed. p o w e r c o e ff ic ie n t c p tip speed ratio  0 5 10 15 -0.2 0 0.2 0.4 0.6 max ���� � = �° � = ��° � = ��° � = ��° � = �° figure 3. power coefficient variation against tsr and deferent pitch angle by using the eq. (4), the dynamic mechanical equation of the pmsg shaft is given as follows [17]:  gvemg g ftt jdt d   -1 (7) where emt is the electromagnetic torque, j is the total moment of inertia and vf is the coefficient of viscous friction. the typical characteristics giving the aerodynamic power of a wt-s, operating at variable speed, depending on the different values of wind speeds, are shown in figure. 4. the maximum of energy efficiency is indicated in this figure, by connecting all the points of maximum power (mpp) of each power curve optaerp , where the maximum power coefficient max_pc is retained. a e ro d y n a m ic p o w e r [p u ] generator shaft speed g [pu] 0 100 200 300 400 500 0 0.5 1 1.5 2 4m/s 6m/s 8m/s 10m/s 14m/s 12m/s pitch control mppt figure 4. aerodynamic powers various speed characteristics with tracking curve iv. maximum power tracking control based on tsr method many techniques of mppt algorithm have been studied in the literature [11, 13]. control of the torque (thus of the power) is designed to extract the maximum possible power available from the wind by adjusting the generator shaft speed. to achieve this objective, the turbine tsr must be maintained at its optimum value ( opt ) despite wind variations, where maximum wind energy is captured by the turbine [18]. iv.1. control with wind speed measurement tsrmpcwsm this first mode configuration consists in adjusting the torque appearing on the turbine shaft so as to fix its speed to a reference. in this context, it is considered that it is considered that the electromagnetic torque developed and its reference are equal at all times, assuming that the electric machine and its static converter are ideal. * em ttem  (8) from the eq. (7) it is clear that the generator speed is governed by the action of two couples, the torque coming out of the gearbox gt and the electromagnetic torque emt . this relation also shows that to have a reference torque, it’s necessary to have a reference generator speed. to apply this control configuration, the speed must be enslaved by a proportional-integral (pi) regulator. as a result, the rotational of the reference speed generator *g , which depends on the speed of the turbine, is obtained by eq. (4) as follows: ** tg g  (9) this method of the first mode is based on wind speed information. therefore, an anemometer is required for measuring the wind speed on the wind turbine, supposing that the optimal value of the tsr opt can be obtained y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 9 from figure.3, the optimal speed of the turbine can be determined from equation. (6), as follows: r vopt optt   , (10) we can easily deduce a diagram of this control configuration which presents the servo control of the speed for the maximization of the extracted aerodynamic power as show in fig. 5 for the first mode. iv.2. control with wind speed estimations tsrmpcwse the difficulty found in this first method is the wind speed measurements which use an additional anemometer. consequently, another method can be conceived for the mppt, without wind speed measurement and without controlling the generator shaft speed, as presented in the second mode. in this case, from the dynamic equation of the turbine shaft, we obtain the static equation describing the steady state of the turbine:  gvemg g ftt dt d   0 (11) so, ignoring the effect of the viscous friction couple ( 0gvf ), we obtain: emg tt  (12) at the output of the gearbox, with an estimation of the turbine torque, it is easy to determine the reference electromagnetic torque [19]: g t t aer em ˆ *  (13) the objective of the control is to improve the capture wind energy by following the optimal torque optaert ,ˆ expressed in eq.(3), using the above estimated wind speed: 3 , ˆ 2 1ˆ vsct p t optaer    (14) the generator shaft speed allows the estimation of the turbine speed t̂ from the following relation: g g t  ̂ (15) assuming that the pitch angle  remains constant, the wind speed can be estimated as follows: opt tr v    ˆ ˆ (16) by grouping the previous equations, we obtain a global relation of tsr-mpcwse method configuration: 2 5 3 * 2           g rc t gp em (17) this control block diagram of variable-speed fixedpitch wecs in generally aims at regulating the power (thus the torque) harvested from wind by modifying the generator shaft speed. the generation system operated well and achieved the mppt curve during variation of generator shaft speed. the electromagnetic will be an input for the control loop described in section iv. it should be noted that this work focuses on the mppt. accordingly, the mpcwse of our system is shown in fig. 5 (second select mode). this control block also proposes a select mode to choose the operating mode; the first select mode for the mppt is based on wind speed measurement with a simple anemometer and speed control with a classical pi controller. vfsj  1 g 1 g 1 t aert pc 3),( 2 1 svc p t    v turbine gsap g emt g 1 t̂ opt t ˆr   g 1 v̂ aert̂ emt̂ gt g v r t r vopt g * t * g pi 3 2 1 svc p t   1 2 + + multiplicateur figure 5. the schematic diagram of the mppt control with select mode: 1. with wind speed measurement (tsr-mpcwsm), 2. with wind speed estimations (tsr-mpcwse). v. simulation results and discussion some results of the simulation of the two mode of control were carried out on the matlab/simulink® platform. in this simulation, we are required to represent most the simulation figures that allow us to evaluate the performances provided by the control system. the parameters of the wecs are reported in the appendix. the proposed profile of the wind speed using fast model is given in fig. 6. the mpc (maximum power control) is then applied by the conditions given from fig. 2, the maximum values of power coefficient max_pc and the optimum speed ratio opt for the curve associated to the fixed pitch angle  0 . the pitch angle is maintained at its fixed value, without power limitation below the rated wind speed. y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 10 w in d s p e e d [ m /s ] time (s) 0 1 2 3 4 5 6 0 5 10 15 figure 6. wind speed profile using fast model g e n e ra to r s p e e d [ ra d /s ] g e n e ra to r to rq u e [ n m ] time [s] time [s] a e ro d y n a m ic p o w e r [w ] a e ro d y n a m ic t o rq u e [ n m ] time [s] time [s] p o w e r c o e ff ic ie n t (c p ) t ip s p e e d r a ti o ( � ) time [s] time [s] 0 2 4 6 0 100 200 300 400 tsr-mpcwse tsr-mpcwsm 0 2 4 6 0 200 400 600 800 1000 1200 tsr-mpcwsm tsr-mpcwse 0 2 4 6 0 0.5 1 1.5 2 2.5 3 x 10 5 tsr-mpcwsm tsr-mpcwse 0 2 4 6 0 1 2 3 4 x 10 4 tsr-mpcwsm tsr-mpcwse 0 2 4 6 0 0.1 0.2 0.3 0.4 0.5 0 0.5 1 1.5 2 0.45 0.46 0.47 0.48 ��_��� ��_��� ��_��� 0 2 4 6 0 2 4 6 8 10 �_��� �_��� �_��� figure 7. reponses of wecs: (a) generator speed, (b) aerodynamic torque, (c) aerodynamic power, (d) generator torque, (e) power coefficient, (f) tip speed ratio. y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 11 the following simulation results are performed to compare the two modes of control, namely, control with wind speed estimations (tsr-mpcwse) and control with wind speed measurement (tsr-mpcwsm) algorithm (see fig. 5). fig. 7(a) shows the mechanical speed of the pmsg shaft obtained by using two different models. fig. 7(b), fig. 7(c), fig. 7(d) shows the dynamic behavior of wecs such as aerodynamic power, aerodynamic and generator torque using tsrmpcwsm/mpcwse approach. it can be seen from fig. 7(e) that the mppt technique ensures the tracking of the optimum power points, by maintaining the power coefficient around its maximum value 479,0max_ pc . it is also shown from fig. 7(f) that the tip speed ratio is around its optimum value 8opt . based on the response of the techniques described above, comparisons are made between the two methods: • tsr-mpcwsm: this method is characterized by a good and rapid response. as the technique uses the actual wind speed for the purpose of measuring the optimum rotational speed, the ability to track this controller is very good. however, the exact measurement of wind speed is a daunting task, especially in the case of large-scale wind turbines. • tsr-mpcwse: this method is characterized by a rather slow response, as shown in fig. 7. the control strategy for this part is easy and simple to implement as there is no need to measure wind speed (anemometer). the two previous methods are compared in table i. it can be seen, that during of wecs operation, the control policy with tsr-mpcwse has a good performance against variations in wind profile and the difference between the measured value and its reference is significantly reduced compared to the tsr-mpcwsm. table 1. comparison of control methods t ec h n iq u es p o w er c o ef fi ci en t e rr o r v al u e t ip s p ee d r at io e rr o r v al u e co m p le x it y c o n v er g en ce sp ee d w in d s p ee d m ea su re m en t mpcwsm high high high fast yes mpcwse low low low slow no vi. conclusion in this paper, the modeling and control strategy of a wind energy conversion system (wecs) based on pm generator is presented. the randomly varying wind speeds and modeling uncertainties can affect the wecs’ efficiency and lead to drive train mechanical stresses. the overall system is simulated for two different approach, control with wind speed measurement tsrmpcwsm and control with wind speed estimations tsr-mpcwse. the results of the simulation showed the possibility of extracting the maximum power of energy for different wind speeds values. appendix in this part, simulations are investigated with a 1.5mw generator wind turbine [13]. the parameters of our system are presented below: parameters value turbine air density: 3/22.1 mkg wind turbine blade radius: mr 25.35 pitch angle: deg0 gearbox ratio: 30g cp parameters c1 c2 c3 c4 c5 c6 0.5176 116 0.4 5 21 0.0068 references [1] e. koutroulis, k. kalaitzakis, design of a maximum power tracking system for wind-energy-conversion applications, ieee transactions on industrial electronics, vol. 53, no. 2, 2006, pp. 486-494. [2] k. ghedamsi, d. aouzellag, e. berkouk, control of wind generator associated to a flywheel energy storage system, renewable energy, vol. 33, no. 9, 2008, pp.2145-2156. [3] a. nadhir, t. hiyama, maximum power point tracking based optimal control wind energy conversion system, advances in computing, control and telecommunication technologies (act), 2010 second international conference on, 2010. ieee, pp. 41-44. [4] s. ganjefar, a. a. ghassemi, m. m. ahmadi, improving efficiency of two-type maximum power point tracking methods of tip-speed ratio and optimum torque in wind turbine system using a quantum neural network, energy, vol. 67, no. 1, 2014, pp.444-453. [5] m. bechouat, proposed algorithm mppt for photovoltaic system, international journal of energetica, vol. 3, no. 1, 2018, pp.10-17. [6] s. m. r. kazmi, h. goto, h.-j. guo, o. ichinokura, review and critical analysis of the research papers published till date on maximum power point tracking in wind energy conversion system, energy conversion congress and exposition (ecce), 2010 ieee, pp. 40754082. [7] j. hui a. bakhshai, a new adaptive control algorithm for maximum power point tracking for wind energy conversion systems, power electronics specialists conference (pesc) ieee, 2008, pp. 4003-4007. [8] s. m. r. kazmi, h. goto, h.-j. guo, o. ichinokura, a novel algorithm for fast and efficient speed-sensorless maximum power point tracking in wind energy conversion systems, ieee transactions on industrial electronics ,vol. 58, no. 1, 2011, pp.29-36. [9] a. olimpo, j. nic, e. janaka, c. phill, h. mike, wind energy generation: modeling and control, john wiley & sons, ltd, 2009. y. saidi et al. ijeca-issn: 2543-3717. december 2018 page 12 [10] m. verdonschot, modeling and control of wind turbines using a continuously variable transmission, master's thesis. tu eindhoven, eindhoven, the netherlands, 2009. [11] k. d. e. kerrouche, a. mezouar, l. boumediene, k. belgacem, modeling and optimum power control based dfig wind energy conversion system, international review of electrical engineering (iree), vol. 91, no. 2, 2014, pp. 174–185. [12] m. a. abdullah, a. yatim, c. w. tan, r. saidur, a review of maximum power point tracking algorithms for wind energy systems, renewable and sustainable energy reviews, vol. 16, no. 5, 2012, pp.3220-3227. [13] k. d. e. kerrouche, a. mezouar, l. boumediene, a. v. d. bossche, modeling and lyapunov-designed based on adaptive gain sliding mode control for wind turbines, journal of power technologies, vol. 96, no. 2, 2016, pp.124-136. [14] i. munteanu, a. i. bratcu, n.-a. cutululis, e. ceanga, optimal control of wind energy systems: towards a global approach, springer science & business media. 2008. [15] a. manjock, design codes fast and adams for load calculations of onshore wind turbines, national renewable energy laboratory (nrel): golden, colorado, usa, 2005. [16] a. berboucha, k. djermouni, k. ghedamsi, d. aouzellag, fuzzy logic control of wind turbine storage system connected to the grid using multilevel inverter, international journal of energetica, vol. 2, no. 1, 2017, pp.15-23. [17] y. saidi, a. mezouar, y. miloud, modeling and control of a wind energy conversion system based on a pmsg, 1st algerian multi-conference on computer, electrical and electronic engineering (amceee'17), 2017. [18] f. amrane, a. chaiba, s. mekhilef, high performances of grid-connected dfig based on direct power control with fixed switching frequency via mppt strategy using mrac and neuro-fuzzy control, journal of power technologies, vol. 96, no. 1, 2016, pp.27-39. [19] l. peng, reconfiguration du dispositif de commande d’une éolienne en cas de creux de tension, central school of lille, france, phd thesis, 2010. i. introduction ii. wind speed modeling iii. wind turbine modeling iv. maximum power tracking control based on tsr method iv.1. control with wind speed measurement tsr-mpcwsm iv.2. control with wind speed estimations tsr-mpcwse v. simulation results and discussion vi. conclusion appendix references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 23-27 ijeca-issn: 2543-3717. june 2019 page 23 elastic, mechanical and thermodynamic properties of zinc blende iii-x (x= as, sb): ab-initio calculations miloud ibrir 1* , moufdi hadjab 2 , gazi yalcin battal 3 , fayçal bouzid 2 , abderrahim hadj larbi 2 , samah boudour 2 , hassene nezzari 2 1laboratory of materials physics and its applications, department of physics, university of m’sila, 28000, algeria 2thin films development and applications unit udcmasetif / research center in industrial technologies crti, algeria 3department of physics, sakarya university, esentepe campus, 54187 sakarya, turkey email*: ibrirmiloud@yahoo.fr abstract – in this work, density functional theory plane-wave full potential method, with local density approximation (lda) are used to investigate the structural, mechanical and thermodynamic properties of of zincblende iii-x ( x= as, sb) compends. comparison of the calculated equilibrium lattice constants and experimental data shows very good agreement. the elastic constants were determined from a linear fit of the calculated stress-strain function according to hooke’s law. from the elastic constants, the bulk modulus b, shear modulus g, young’s modulus e, poisson’s ratio σ, anisotropy factor a, the ratio b/g and the hardness parameter h for zincblende iii-x ( x= as, sb) compound are obtained. our calculated elastic constants indicate that the ground state structure of iii-x ( x= as, sb) is mechanically stable. the sound velocities and debye temperature are also predicted from elastic constants. keywords: mechanics, mechanics, energy, dft, lda received: 03/03/2019 – accepted: 15/05/2019 i. introduction the method developed by charpin (modified by ferenc karsai) and integrated in wien2k code [1] has been used to obtain elastic constants of considered binary compounds. the knowledge of elastic parameters of solids is very important because they provide important information about the stability and mechanical properties of solids such as sound velocities, load deflection, fracture toughness, thermoelastic stress and internal strain etc. ii. elastic and mechanical properties the elastic constants cklmn (where the letter k, l, m, n refer to cartesian components) are defined by the help of a taylor expansion of the total energy of the system, e(v,ϵ), in accordance with a small strain ϵ of the lattice (v is the volume of the system). the energy e(v,δ) fit curve versus strain, δ, for the three different types of strains, namely the volume conserved, tetragonal and rhombohedral shear strains, are plotted in figure 1 (a)(c), respectively, for the studied binary compounds. the total energy has been calculated for five to seven different distortions for each of the three different deformations of the lattice. there are 21 independent elastic constants cij, but symmetry of the cubic lattice reduces this number to only 3 independent constants (c11,c12, and c44) for cubic lattices. the calculated values of elastic constants are summarized in table 1. the calculated elastic constant values of studied binary compounds are in good agreement with the results of other calculations [2, 4] and the available experimental data [3, 5].the obtained values for the elastic tensor constants satisfy the mechanical stability restrictionsfor cubic unit cells c11 c12 > 0, c11 + 2c12 > 0 and c12 < b < c11 [6].resistance to shear distortions of a cubic crystal is best characterized by the two moduli the tetragonal shear constant c' = (c11-c12)/2 and c44. the elastic constant c44 is related to an orthorhombic deformation whereas c' is related to a tetragonal deformation. at any volume v, the bulk modulus b for a cubic crystal is related to elastic constants by b0 = (c11+2c12)/3 [7]. the c11 and c12 can be obtained from the calculated bulk modulus and c'. abder image placée miloud ibrir author et al ijeca-issn: 2543-3717. june 2019 page 24 the kleinmann parameter [8], ζ, is an important parameter describing the piezoelectric effect of solids [9]. it is given by the following relation: 11 12 11 12 8 7 2 c c c c     the obtained values of ζ for the materials are between 0.575 and 0.716 as shown table 1. the obtained results for studied binary compounds fairly coincide with previous first-principles calculations [2, 10].we have also found the anisotropy factor a = 2c44/(c11 − c12). for an isotropic crystal, a is equal to 1, while any value smaller or larger than 1 indicates anisotropy. from table 1, it is clearly seen that the calculated anisotropy factor for these compounds deviate from 1. the magnitude of the deviation from 1 is a measure of the degree of elastic anisotropy possessed by the crystal. the isotropic bulk modulus b0, which is related to c11 and c12, and shear modulus (g) are determined by the calculated elastic constants [11]. however, there is no distinct expression for the polycrystal-averaged shear modulus with respect to the cij, but one can evaluate approximate averages of the lower and upper bounds given by various theories [12]. voight [13] found upper bounds, while reuss [14] discovered lower bounds for all lattice. the kleinmann parameter [8], ζ, is an important parameter describing the piezoelectric effect of solids [9]. it is given by the following relation: 11 12 11 12 8 7 2 c c c c     the obtained values of ζ for the materials are between 0.575 and 0.716 as shown table 1. the obtained results for studied binary compounds fairly coincide with previous first-principles calculations [2,10].we have also found the anisotropy factor a = 2c44/(c11 − c12). for an isotropic crystal, a is equal to 1, while any value smaller or larger than 1 indicates anisotropy. from table 1, it is clearly seen that the calculated anisotropy factor for these compounds deviate from 1. the magnitude of the deviation from 1 is a measure of the degree of elastic anisotropy possessed by the crystal. the kleinmann parameter [8], ζ, is an important parameter describing the piezoelectric effect of solids [9]. it is given by the following relation: 11 12 11 12 8 7 2 c c c c     the obtained values of ζ for the materials are between 0.575 and 0.716 as shown table 1. the obtained results for studied binary compounds fairly coincide with previous first-principles calculations [2, 10].we have also found the anisotropy factor a = 2c44/(c11 − c12). for an isotropic crystal, a is equal to 1, while any value smaller or larger than 1 indicates anisotropy. from table 1, it is clearly seen that the calculated anisotropy factor for these compounds deviate from 1. the magnitude of the deviation from 1 is a measure of the degree of elastic anisotropy possessed by the crystal. the isotropic bulk modulus b0, which is related to c11 and c12, and shear modulus (g) are determined by the calculated elastic constants [11]. however, there is no distinct expression for the polycrystal-averaged shear modulus with respect to the cij, but one can evaluate approximate averages of the lower and upper bounds given by various theories [12]. voight [13] found upper bounds, while reuss [14] discovered lower bounds for all lattice. the upper bound due to voight is calculated as 11 12 44( 3 ) / 5  vg c c c and the lower bound due to reuss reads as 11 12 445 / 4 / ( ) 3 /  rg c c c according to hill [15], the arithmetic average of the voight and reuss values can be used as an estimated of the average shear modulus g=1/2 (gv+gr). another important mechanical parameter that is directly correlated to the ductility is the poisson’s ratio and given by where y is the young’s modulus and is related to the bulk and shear moduli 9bg y 3b g   y and v are frequently measured for polycrystal materials when investigating their hardness. young’s modulus is a measure of the stiffness of a given material, whereas poisson’s ratio is the ratio (when a sample is stretched) of the contraction or transverse strain to the extension or axial strain.the calculated average shear modulus (g), young’s modulus (y) and poisson’s ratio (v) are given in table 1. the obtained results for studied binary compounds fairly coincide with previous first-principles calculations [2, 10] and experimental results [16, 17]. materials with high g are likely to be hard materials. in studied compounds, gaas exhibits the largest value of g (54.551 gpa) being the most incompressible of all. the young modulus (y) determines the stiffness of the material, i.e., the larger value of y, the stiffer is the material [18] and the stiffer solids have covalent bonds [19].it can be seen from table 1 that the largest value of y (130.388 gpa) being the most stiffer of all occurs for gaas implying it to be more covalent in nature as compared to other studied compounds. the proportion between bulk modulus and average shear modulus (b0/g) has been proposed by pugh [20] to roughly determine the ductile or brittle character of a material. the critical value which separates ductile and brittle material is 1.75; i.e., if b0/g is smaller than 1.75, then the material behaves in a brittle manner; otherwise it miloud ibrir author et al ijeca-issn: 2543-3717. june 2019 page 25 will be of ductile nature [21]. the b0/g ratio of studied materials is presented in table 1. it is clearly seen from this table that b0/g ratio of considered structures should be classified as brittle character. to obtain the stiffness of these compounds, the microhardness parameter (h) is also calculated using the following equation [22]: (1 2 )y h 6(1 )     the calculated h values are 9.40gpa, 11.09gpa, 5.87gpa, 7.50gpa, 8.10gpaand 5.12foralas, gaas, inas, alsb, gasb and insb at zero pressure, respectively. the cauchy pressure is another interesting elastic parameter which describes the angular characteristic of atomic bonding in a material can be calculated by using the following relation [23]: c’= c12-c44 the positive value of cauchy pressure is responsible for a ionic bonding while a negative cauchy pressure, however, requires an angular or directional character in the bonding (covalent bonding). the more negative the cauchy pressure, the more directional and of lower mobility the bonding. moreover, a material with more negative value of cauchy pressure will have more brittle nature. the calculated values of c’ are summarized in table 2, which indicate that the sign of the cauchy pressure is negative for all studied materials. the kind of bonds can be also determined by means of the value of poisson’s ratio (υ). the value of poisson’s ratio is nearly 0.25 or more for a typical ionic material, while it is much less than 0.25 (around 0.1) for a typical covalent comp. c11 (gpa) c12 (gpa) c44 (gpa) c’ b0 (gpa) ƺ a g (gpa) y (gpa) ν b0/g alas 110,442 56,982 78,132 26,730 74,802 0,638 2,923 50,867 124,402 0,22 1,471 113.1 [2] 55.5 [2] 54.7 [2] 28.8 [2] 0.592 [2] 1.899 [2] 77.14 [10] 175.39 [10] 30.329 [2] 1.043 [10] 119.9 [3] 57.5 [3] 56.6 [3] 0.481 [10] 0.136 [10] gaas 113,589 50,115 78,401 31,737 71,273 2,470 54,551 130,388 0,195 1,307 115,1 [4] 51.5 [4] 56.8 [4] 36.4 [2] 72.7[4] 0,575 1.742 [2] 32.6 [16] 85.5 [16] 0.293 [2] 118.1 [5] 53.2 [5] 62.0 [5] 0.506 [2] 0.31 [17] inas 81,547 49,809 60,838 15,869 60,388 0,716 3,834 35,683 89,433 0,253 1,692 92.2 [2] 46.5 [2] 44.4 [2] 22.9 [2] 0.598 [2] 1.943 [2] 0.335 [2] 83.3 [5] 45.3 [5] 39.6 [5] 84,615 42,727 60,737 20,944 56,690 0,629 2,900 39,665 96,490 0,216 1,429 alsb 85.5 [2] 41.4 [2] 39.9 [2] 22.1 [2] 0.601 [2] 1.81 [2] 0.326 [2] 89.4 [5] 44.3 [5] 41.6 [5] gasb 84,169 38,939 59,841 22,615 54,016 0,593 2,646 40,517 97,238 0,200 1,333 92.7 [2] 38.7 [2] 46.2 [2] 27 [2] 0.530 [2] 1.711 [2] 0.295 [2] 88.4 [5] 40.3 [5] 43.2 [5] insb 65,062 38,348 50,121 13,357 47,253 0,699 3,752 29,636 73,535 0,241 1,594 72.0 [2] 35.4 [2] 34.1 [2] 18.3 [2] 0.603 [2] 1.863 [2] 0.487 [2] 66.7 [5] 36.5 [5] 30.2 [5] table 1 calculated elastic constants (c11, c12 and c44) and tetragonal shear constant (c'), kleinman’s internal-strain parameter (ƺ), shear modulus anisotropy (a), the average shear modulus (g), young’s modulus (y) and poisson’s ratio (v), and b0/g ratio of studied materials and the comparison of these quantities with available theoretical and experimental data. miloud ibrir author et al ijeca-issn: 2543-3717. june 2019 page 26 compound [24]. as indicated table 1, our calculation shows that υ < 0.25 for all studied materials. consequently, our cauchy pressure calculations are consistent with our poisson’s ratio values. the other interesting elastic parameters are lame constants ( λ, μ) which depend on a material and its temperature. these parameters are related to the young modulus and poisson’s ratio by using the following equations: y (1 )(1 2 )        and y 2(1 )     where y is the young’s modulus and υ poisson’s ratio. our calculated values of λ and μ are summarized in table 2. the two parameters together constitute a parametrization of the elastic moduli for homogeneous isotropic media, λ is known as lame’s first constant and μ is lame’s second constant. the lame’s first modulus, λ, is related to a fraction of young’s modulus. for an isotropic system one can show that λ=c12 and μ= c [25]. as shown from table 1 (from anisotropy factor, a) the studied materials are strongly anisotropic character; therefore our obtained results do not satisfy the later relations, which are valid only for the isotropic systems, which is in agreement with the obtained results. iii. thermodynamic properties the debye temperature (θd) which is a significant fundamental parameter closely related to many physical properties such as elastic constants, specific heat and melting point can be obtained from the average sound velocity (vm) by the following classical relation [26]: 1/3 2 0 6 d m b n k v            where v0 is atomic volume and vm the average wave velocity in the polycrystalline material is approximately calculated from the following equation [26]: 1/3 3 3 1 2 1 3 m t l               linear relationship between tm and the c11 elastic constant. the scatter of all the different points falls within plus or minus 300 k of the following equation for tm in units of k [28]: tm = 553 k + (591/mbar) c11 ± 300 k the calculated wave velocities (vt, vl, vm), debye temperature (θd) and melting point (tm) of studied binary compounds and ternary alloys estimated from elastic constants are listed in table 2. it is clearly seen from table 2, the debye temperature of the considered compounds decrease with increasing atomic number.the high value of the debye temperature for alas implies that its thermal conductivity is to be higher than other studied compounds. the sound velocities are related to the elastic moduli. therefore, for a material having larger elastic moduli means higher sound velocity. thermal conductivity, κ, is the property of a material that indicates its ability to conduct heat. so, in order to know if material is a potential candidate for thermal barrier coating application, its thermal conductivity need to be investigated. based on the debye model, clarke [29] suggested that the theoretical minimum thermal conductivity can be calculated after replacing different atoms by an equivalent atom with a mean atomic mass m/n: 2/ 3 1/ 6 1/ 2 2/ 3 min b a 2/ 3 n y 0.87k n m    where kb is the boltzmann’s constant, m is the molecular mass and n is the number of atoms per molecule, na the avogadro’s number, ρ the density. the calculated minimum thermal conductivity of studied materials is summarized in table 2. table 2 indicates that the value of minimum thermal conductivity decreases when one moves from al to in in the compound xas (sb) (x=al, ga and in). the reduction can be attributed mainly to the difference in young’s modulus, which is a measure of the second derivative of the bonding energy at the comp. h (gpa) c” (gpa) λ (gpa) μ (gpa) vt (m/s) vl(m/s) vm (m/s) θd (k) tm (k)±300 �min (wmk -1 ) alas gaas inas alsb gasb insb 9,40 11,09 5,87 7,50 8,10 5,12 -21,150 -28,286 -11,029 -18,009 -20,901 -11,773 40,891 34,905 36,599 30,247 27,005 27,496 50,867 54,551 35,683 39,665 40,517 29,636 3680,935 3193,605 2501,806 3036,484 2678,678 2258,360 6163,647 5188,860 4351,768 5046,935 4374,136 3864,231 4073,853 3523,838 2778,513 3358,187 2957,205 2504,483 428,576 371,173 273,101 325,907 288,857 230,170 1205,712 1224,314 1034,942 1053,074 1050,442 937,519 1,769 1,534 1,053 1,241 1,107 0,830 table 2.calculated microhardness parameter (h), cauchy pressure (c’’), and 1 st and 2nd lame constants (λ, μ), wave velocities (vt, vl and vm), debye temperature (θd), melting point (tm) and the minimum thermal conductivity (κmin) of studied materials. miloud ibrir author et al ijeca-issn: 2543-3717. june 2019 page 27 equilibrium interatomic distance x0, between the studied binary compounds. where vt and vl are the transverse and longitudinal elastic wave velocities, respectively, obtained using the shear modulus g and the bulk modulus b from navier’s equations [27]: t g    3 4 3 l b g     where ρ is the density. fine et al. [28] have studied many cubic metals and compounds and have obtained an approximate empirical. iv. conclusion in this study, the structural, mechanical and thermodynamic properties of iii-x ( x= as, sb) compounds have been investigated by means of the dft within wien2k code. our results for the optimized lattice parameters (a) and (c) are in good. agreement with the available experimental data. the elastic constants cij, and related polycrystalline mechanical parameters such as bulk modulus b, shear modulus g, young’s modulus e and poisson coefficient σ are calculated using voigt– reuss–hill approximations. the iii-x (x= as, sb) compound is mechanically stable according to the elastic stability criteria, while no experimental results of elastic moduli for comparison. the calculated zener factor indicates that iii-x (x= as, sb) compound is elastically anisotropic. the values of the ratio b/g and cauchy pressure (c12–c44) show a ductile manner for the iii-x ( x= as, sb) compound. the polycrystalline iii-x ( x= as, sb) turns out to be a low stiff material according to the calculated hardness parameter (h). finally, from the knowledge of the elastic constants and the average sound velocities, the debye temperature has been predicted successfully. references [1] p. blaha, k. schwarz, g. madsen, d. kvasnicka, j. luitz, “an augmented plane wave plus local orbital rogram for calculating the crystal properties”, revised edition wien2k_13.1, pp.132-135. [2] s. q. wang and h. q. ye, “phys. stat”. sol b 1, 2003, pp 45. [3] wei li and markus pessa, “lattice parameter in ganas epilayers on gaas: deviation from vegard’s law”, appl. phys. lett. 78, 2864, 2001. [4] g. stenuit and s. fahy, “first-principles calculations of the mechanical and structural properties of ganxas1−x: lattice and elastic constants”, phys. rev. b 76, 035201, 2007. [5] r. weil and w. o.groves, “elastic constants of gallium phosphide”, j. appl. phys. vol 39, 1968, pp 4049. [6] d.c. wallace, “thermodynamics of crystals,” john wiley, new york, 1972. [7] d. connetable, o. thomas, “first-principles study of the structural, electronic, vibrational, and elastic properties of orthorhombic nisi”, phys. rev. b 79, 2009, pp 094101. [8] l. kleinmann, “deformation potentials in silicon. i. uniaxial strain”, phys. rev. vol 128, 1962, pp 2614 [9] w. cady, “piezoelectricity (mcgraw-hill)”, new york, 1946. [10] m. sajjad, s.m. alay-e-abbas, h.x. zhang, n.a. noor,y. saeed, imran shakir, a. shaukat, “first principles study of structural, elastic, electronic and magnetic properties of mn-doped aly (y=n, p, as) compounds”, j mag mag mater, vol 390, 2015, pp 78-86. [11] w.a. harrison, “elastic structure and properties of solids, dover publications”, inc., new york, 1980. [12] v. i. razumovskiy, a. v. ruban, p. a. korzhavyi, “firstprinciples study of elastic properties of crand fe-rich fecr alloys”, phys. rev. b 84, 2011, pp 024106-8. [13] w. voight, ann. phys. (leipzig) 38 (1889) 573. [14] a. reuss, z. math. mech. vol 9, 1929, pp 49. [15] r. hill, “the elastic behaviour of a crystalline aggregate”, proc. phys. soc., london, sect. a 65, 1952, pp 349. [16] j. s. blakemore, “semiconducting and other major properties of gallium arsenide”, j app. phys. vol 53, 1982, r123. [17] s. m. sze, “semiconductor sensors”. new york: john wiley & sons,1994. [18] v. mankad, n. rathad, s. d. gupta, s. k. gupta, p. k. jha, mater. chem. phys. vol 129, 2011, pp 816. [19] c. h. jenkins, s. k .khanna, “mechanics of materials”, isbn 0-12-383852-5, 2005, pp. 62-72. [20] s.f. pugh, “relations between the elastic moduli and the plastic properties of polycrystalline pure metals”, philos. mag. vol 45, 1954, pp 823-843. [21] z. dang, m. pang, y. mo, y. zhan, “theoretical prediction of structural, elastic and electronic properties of si-doped ticu geintermetallics”, current appl. physics, vol 13, 2013, pp 549-555. [22] e.s. yousef, a. el-adawy, n. el-khesh khany, “effect of rare earth (pr2o3, nd2o3, sm2o3, eu2o3, gd2o3 and er2o3 ) on the acoustic properties of glass belonging to bismuth–borate system”, solid state commun. vol 139, 2006, pp 108. [23] d. g. pettifor, “theoretical predictions of structure and related properties of intermetallics”, mater. sci. technol. 8, 1992, pp 345. [24] m. jamal, s. j. asadabadi, i. ahmad, h. a: r. aliabad, “elastic constants of cubic crystals”, comput. mater. sci. vol 95 , 2014, pp 592-599. [25] http://en.wikiversity.org/wiki/introduction_to_elasticity/ [26] o. l. anderson, “a simplified method for calculating the debye temperature from elastic constants”, j. phys. chem. solids 24, 1963, pp 909-917. [27] e. schreiber, o.l. anderson, n. soga, “elastic constants and their measurements”, 3th ed., mcgraw-hill, new york, 1973. [28] m.e. fine, l.d. brown, h.l. marcus, “elastic constants versus melting temperature in metals”, scripta metall., 18, 1984, pp 951-956. [29] d. r. clarke, “materials selection guidelines for low thermal conductivity thermal barrier coatings”, surf. coat. tech. 163, 2003, pp 67-74. https://aip.scitation.org/author/li%2c+wei https://aip.scitation.org/author/pessa%2c+markus https://journals.aps.org/prb/abstract/10.1103/physrevb.76.035201 i. introduction references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 1. 2018 page 10-17 ijeca-issn: 2543-3717. june 2018 page 10 proposed algorithm mppt for photovoltaic system mohcene bechouat 1 , moussa sedraoui 1 , sami kahla 1 1 department of electronic and telecommunication, faculty of sciences and technology university of 08 may 1945 of guelma, bp 40, guelma, algeria mohcene.oui@gmail.com abstract – a proposed algorithm mppt (maximum power point tracking) is proposed in this paper. when the insolation change rapidly, the p&o (perturb and observe) algorithm is used to adjust the operating point of the pv (photovoltaic) array close to the mpp (maximum power point) for fast tracking; also, the inc (incremental conductance) algorithm and the fuzzy controller skip drawbacks of the p&o algorithm by decreasing oscillations around the mpp and the underestimated. in addition, to improve the control precision, the effectiveness of proposed algorithm is validated by simulation using matlab/simulink, the simulation results show that the proposed algorithm tracks the mpp quickly, reduces the oscillation around the mpp effectively and improves the energy conversion efficiency of the pv panel. keywords: mppt, photovoltaic, boost, simulation received: 30/05/2018 – accepted: 26/06/2018 i. introduction these instructions give you the guidelines for preparing papers for journal of scientific research edited by the university of bechar (algeria). use this document as a template if you are using microsoft word 6.0 or later. define all symbols used in the abstract. do not adjust the specified font sizes or line spacing to squeeze more text into a limited number of pages. solar energy is one of the most important sources of renewable energy, so that research has been increasingly important in recent years, it’s one of the most promising alternatives for traditional sources of energy for this reason has been used increasingly to produce electricity. many researchers focus on the control methods using a variety of algorithms called mppt to extract the maximum power in different weather conditions, especially when the sudden change, taking into account its impact on the overall system. in solar energy field, many researchers have worked to develop mppt algorithms. [1] has presented simulation and hardware to implement the inc algorithm applied to buck chopper by compared the different mppt methods, also apply pi (proportional integrator) control for the buck converter completely neglecting using pulse width modulation (pwm) direct way. [2] shown experimental results on the mppt when using the inc algorithm specified by a variable give good results, which could remedy the defect of the fixed step length of inc algorithm. the step length was changed by setting the threshold, and different threshold settings influenced the mppt speed. in 2011, the high performance adaptive p&o algorithm based on power grid photovoltaic presented in [3], the oscillation at the point of maximum power for the p&o has improved by adaptive control functioning to change that p&o value according to climate change in the system, in addition to tracing systems output capacity of the sun for dual and two-axis is higher than conventional support systems. in general, follow the maximum power point of the pv system which is made by mppt, thus depend on the algorithm and circuit, this circuit is a dc-dc converter which is considered as a variable resistance, the role of the algorithm is the mode between pv and the converter. the p&o algorithm is widely used because of its low implementation complexity. the shortcoming of this algorithm is that the operating point of the pv fluctuates around the mpp. therefore, the available energy is decreased. furthermore, if the solar insolation changes rapidly, the p&o fails to track the real point of maximum power but has a drawback; the operating point oscillates around the mpp giving rise to the waste of a more or less significant amount of available energy. the perturb oscillation around peak power point of p&o algorithm to track the peak power under fast varying insolation is overcome by inc algorithm and fuzzy controller . the inc and fuzzy can determine that the mppt has reached the mpp and stop perturbing the operating point. in this paper demonstrate that fuzzy better than the inc, also applied proposed algorithm based on the system is the best, the algorithm is inspired by calculated on the system, the duty cycle was calculated based on the power, voltage and load, so the duty cycle does not change with perturbation, shows that this very efficient and very fast simple algorithm at the other. the paper is organized as follows: after this introduction, the electrical model of pv system is presented. to prove the concept, a pv simulation based on one-diode model is explained. in the next section, a detailed description on the mppt is given. the proposed mailto:mohcene.oui@gmail.com mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 11 algorithm is described next. the three mppt algorithms (fuzyy, inc and p&o) are presented respectively, as well as results simulation and analyze as described above are carried out in the following section. finally, the conclusion is given. ii. model of the solar cell the photovoltaic cell is composed of a semiconductor material which absorbs light energy and converts it into electrical current. the solar cells are generally associated in series and in parallel, and then encapsulated in glass for a photovoltaic module. pv generator of inter connected modules to form a unit producing power continuous high compatible with the usual electrical equipment. the pv modules are usually connected in series-parallel to increase the voltage and current to the generator output. the interconnected modules are mounted on carriers metal and inclined at the desired angle depending on the location; this set is often referred module field [4, 5 and 6]. thus the characteristic i-v pv generator is based on that of a cell elementary modeled by the equivalent circuit well known in figure 1 [7, 8 and 9]. this circuitry introduces a current source and a diode in parallel, as well as series resistors 𝑅𝑠 and parallel (shunt) 𝑅𝑃 to reflect events dissipative at the cell level. figure 1. equivalent electrical circuit of a solar cell the series resistance is due to the contribution of the base resistors and the front of the junction and contacts the front and rear. the parallel resistance reflects the effects such as the leakage current through the edges of the cell is reduced because of the penetration of metal impurities in the junction (especially if this penetration is deep). this circuit can be used both for an elementary cell, for a module or a panel made up of several modules [10, 11]. the equation relating the current delivered by a solar cell and the voltage at its terminals is given by: 𝐼𝑝𝑣 = 𝐼𝑝𝑕 − 𝐼𝐷 + 𝑉𝑝𝑣 +𝑅𝑠∙𝐼𝑝𝑣 𝑅𝑝 (1) where ipv and vpv are respectively, the output current and the output voltage of the solar cell. the current passing through the diode is taken as: 𝐼𝐷 = 𝐼0 𝑒 𝑞∙ 𝑉𝑝𝑣 +𝑅𝑠∙𝐼𝑝𝑣 𝐾∙𝑇𝑎 − 1 (2) in addition, the photocurrent iph is also defined by: 𝐼𝑝𝑕 = 𝐺𝑎 𝐺𝑛 𝐼𝑠𝑐 + 𝐾𝐼 𝑇𝑎 − 𝑇𝑛 (3) where ta and tn are respectively, the temperature condition of work and the one given at standard test conditions (stc), i.e., 𝑇𝑛 = 25℃. the difference between both temperatures is weighted by the coefficient, called also ki . moreover, ga and 𝐺𝑛 are respectively, the insolation condition of work and the one given at stc, i.e., 𝐺𝑛 = 1000 𝑤 𝑚2 . where i0 is the reverse saturation current of the diode that given as: 𝐼0 = 𝑇𝑎 𝑇𝑛 3𝑛 ∗ 𝐼𝑠𝑐 𝑒 𝑞∙ 𝑉𝑝𝑣 +𝑅𝑠∙𝐼𝑝𝑣 𝐾∙𝑇𝑎 −1 ∗ 𝑒 𝑞∙𝑉𝑔 𝑛∙ 1 𝑇𝑎 − 1 𝑇𝑛 (4) table 1 summarizes the meaning and the corresponding value of diverse electrical components. we get: table 1. values used in equivalent electrical circuit. parameter quantity identification (unity) corresponding value isc short-circuit current (a) 3.80 q elementary charge (c) 1.6×10 -19 k boltzmann constant (j/k) 1.38×10 -23 voc open-circuit voltage (v) 22.00 vg energy gab (e-v) 1.20 n the diode quality factor 1.2 in the pv panel, the actual output power is determined by three factors [12]: solar insolation, temperature and load. the following table contains some of the parameter values used in the simulation: table.2 the specification of pv system module used in the simulation. parameter value maximum power 𝑃𝑚𝑎𝑥 59.43w maximum voltage 𝑉𝑚𝑎𝑥 18.00 v maximum current 𝐼𝑚𝑎𝑥 3.30 a number of cells 36 figure 2 shows i-v and p-v characteristics of the pv panel in different insolation and temperature conditions. mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 12 figure 2. characteristics of the pv panel from the characteristics (i-v) shown in figure 2, we can see that solar insolation affects the shortcircuit current, also from the characteristics (p-v) in the same figure we can see that the temperature affects the voltage open circuit, these properties conclude that the production of energy in photovoltaic panel is heavily dependent on insolation and temperature that’s mean the maximum power point changed, at the same time, the charge significant impact on the pv panel when weather conditions change. the only way to keep the system always works at maximum power point is to change the charge because the insolation and the temperature are uncontrolled variables. this is the mppt role. iii. maximum power point tracking when the internal resistance (rs ) minutes of photovoltaic generator corresponds to the load resistance (rl ), giving the power delivered to the load is maximum illustrated in figure 3. figure 3. mppt theorem: equivalent circuit the resistance (𝑅𝑆) is sensitive to sunlight, temperature, and other factors, so (𝑅𝐿), should be adjusted to track the pv mpp is the role of a power converter for (𝑅𝑠 = 𝑅𝐿) illustrated in figure 4. figure 4. role of power converter considering the way mppt is find voltage vmpp or current impp integrated mission planning for pv system should function to extract the maximum power pmpp output under a certain temperature and insolation. majority mppt algorithms respond to changes in climate change parameters “insolation and temperature”, others useful specifically if the temperature is almost constant and insolation varying. generally, the mppt is usually as figure 5. figure 5. mppt concept iii.1. proposed algorithm the duty cycle calculated by the mppt controller will be introduced into the converter to keep close to the maximum power point regardless of the external circumstances of the change in temperature and insolation, and adjusting the voltage across the use of a dc-dc converter, which can help increase the efficiency of the photovoltaic panel [13].this type of converter is called boost, where its electronic circuit, it composed of a switch 𝑆(mosfet, implement insulated gate bipolar transistor( igbt),…), inductor 𝐿, diode 𝑑 and capacitors 𝐶1 and 𝐶2. it is powered by a voltage delivered by the pv and against this part; it feeds a resistive load 𝑅 as illustrated in figure 6. figure 6. circuit of the boost converter the voltage and current output of the boost is given by the following relations [6]: 𝑉𝑜𝑢𝑡 = 𝑉𝑝𝑣 1−𝐷 (5) 𝐼𝑜𝑢𝑡 = 𝐼𝑝𝑣 ∙ (1 − 𝐷) (6) the principle of the proposed algorithm is based on the calculation of the relationship between the duty cycle 𝐷, pv power, pv voltage and the load 𝑅 . according to ohm's law: 𝑅 = 𝑉𝑜𝑢𝑡 𝐼𝑜𝑢𝑡 (7) we replace (5) and (6) to (7) we have: 0 10 20 30 0 0.5 1 1.5 2 2.5 3 3.5 4 v(volt) i( a ) i-v characteristics under different insolation levels 0 10 20 30 0 10 20 30 40 50 60 70 v(volt) p (w a tt ) p-v characteristics under different temperature levels ga=1000w/m 2 ga=800w/m 2 ga=500w/m 2 ta=0 o c ta=10 o c ta=25 o c mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 13 𝑅 = 𝑉𝑝𝑣 𝐼𝑝𝑣 (1−𝐷) 2 (8) multiplying the numerator and denominator of equation (8) by the panel voltage 𝑉𝑝𝑣 , so the equation (8) becomes: 𝑅 = 𝑉𝑝𝑣 2 𝑃𝑝𝑣 (1−𝐷) 2 (9) simplified the equation (9) given the following equation for 𝐷: 𝐷 = 1 − 𝑉𝑝𝑣 𝑃𝑝𝑣∗𝑅 (10) the proposed algorithm steps as follows: step 01: initialization 𝑃𝑝𝑣 = 0, 𝐷 = 0.5 " selected (50%) in the probability that the optimum value in all cases is less than or greater than 0.5", 𝑅 (arbitrary). step 02: measure the voltage and current 𝑉𝑝𝑣 , 𝐼𝑝𝑣 calculate 𝑃𝑝𝑣 . step 03: compare the actual power with the previous: if the two powers are different then calculate the new duty cycle from equation (10). if not: save the same duty cycle 𝐷. step 04: a comparison 𝐷 with extreme if 𝐷 > 0.99999 then 𝐷 = 0.99999 if 𝐷 <0 then 𝐷 = 0. step 05: replace 𝑃𝑝𝑣 and 𝐷 by their current values. step 6: return to step 2 and re run the algorithm. iii.2. fuzzy logic control fuzzy logic control (flc) of photovoltaic maximum power point tracking maximum power point tracking system uses boost converter to compensate the output voltage of the solar panel to keep the voltage at the value which maximizes the output power. mpp fuzzy logic controller measures the values of the voltage and current at the output of the solar panel, then calculates the power from the relation (𝑃𝑝𝑣 = 𝑉𝑝𝑣 ∙ 𝐼𝑝𝑣) to extract the inputs of the controller. the crisp output of the controller represents the duty cycle perturbation. the flc examines the output pv power at each sample time (k), and determines the change in power relative to voltage (𝑑𝑃𝑝𝑣 𝑑𝑉𝑝𝑣 ). if this value is greater than zero the controller change the duty cycle to increase the voltage until the power is maximum or the value ((𝑑𝑃𝑝𝑣 𝑑𝑉𝑝𝑣 = 0), if this value less than zero the controller changes the duty cycle to decrease the voltage until the power is maximum as shown in figure 7. figure 7. power-voltage characteristic of a pv panel flc has two inputs which are: 𝐸𝑟𝑟𝑜𝑟 and the 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 , and one output is the duty cycle perturbation ∆𝐷. the two flc input variables 𝐸𝑟𝑟𝑜𝑟 and 𝐶𝑕𝑎𝑛𝑔𝑒 𝐸𝑟𝑟𝑜𝑟 at sampled times 𝑘 defined by [14]: 𝐸𝑟𝑟𝑜𝑟 𝑘 = 𝑃𝑝𝑣 𝑘 −𝑃𝑝𝑣 (𝑘−1) 𝑉𝑝𝑣 𝑘 −𝑉𝑝𝑣 (𝑘−1) (11) 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 (𝑘) = 𝐸𝑟𝑟𝑜𝑟 𝑘 − 𝐸𝑟𝑟𝑜𝑟(𝑘 − 1) (12) where: 𝑃𝑝𝑣 𝑘 is the instant power of the photovoltaic generator. the input 𝐸𝑟𝑟𝑜𝑟(𝑘) shows if the load operation point at the instant 𝑘 is located on the left or on the right of the maximum power point on the pv characteristic, while the input 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 (𝑘), expresses the moving direction of this point. the fuzzy inference is carried out by using mamdani method; flc for the maximum power point tracker contains three basic parts: fuzzification, base rule, and defuzzification. a twoinput (antecedent) rule of the mamdani type has the form: 𝑖𝑓 𝐸𝑟𝑟𝑜𝑟 𝑖𝑠 𝑥1 𝑎𝑛𝑑 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 𝑖𝑠 𝑥2 𝑡𝑕𝑒𝑛 ∆𝐷 𝑖𝑠 𝑥3 where: 𝑥1, 𝑥2 and 𝑥3 , are linguistic terms associated to the inputs and output variables (𝐸𝑟𝑟𝑜𝑟, 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 𝑎𝑛𝑑 ∆𝐷); the knowledge base defining the rules for the desired relationship is between the input and output variables in terms of the membership functions illustrated in table 3. the choice of knowledge base by the assessment. where many researchers use fuzzy as [15, 16]. this knowledge base resume how calculate duty cycle perturbation byt he 𝐸𝑟𝑟𝑜𝑟 and the 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 inputs. table 3. flc rules. changeerror error ng np ez pp pg ng ez ez pg pg pg np ez ez pp pp pp ez pp ez ez ez np pp np np np ez ez pg ng ng ng ez ez mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 14 figure 8 illustrates the fuzzy set of 𝐸𝑟𝑟𝑜𝑟 and 𝐶𝑕𝑎𝑛𝑔𝑒𝐸𝑟𝑟𝑜𝑟 inputs membership functions. figure 8. membership functions of inputs figure 9 illustrates the fuzzy set of the duty cycle output membership functions. figure 9. membership functions of output figure 10 shows the surface of the base rules using in flc. figure 10. rule surface of flc iii.3. incremental conductance algorithm the criteria for the inc algorithm, reported by wasynezuk [17], can then be given from the derivative of the power compared voltage: 𝑑𝑃𝑝𝑣 𝑑𝑉𝑝𝑣 = 0 𝑠𝑜 𝑉𝑝𝑣 ∙𝑑𝐼𝑝𝑣 + 𝐼𝑝𝑣 ∙ 𝑑𝑉𝑝𝑣 = 0 𝑠𝑜 𝑑𝐼𝑝𝑣 𝑑𝑉𝑝𝑣 = − 𝐼𝑝𝑣 𝑉𝑝𝑣 (13) so: ∆𝐼𝑝𝑣 ∆𝑉𝑝𝑣 = − 𝐼𝑝𝑣 𝑉𝑝𝑣 (14) the algorithm relies on the measurement of current and voltage at specific moments in the same sample time. to calculate the duty cycle will depend on the equation (14) will calculate any change in the voltage thus (∆𝑉𝑝𝑣 ) that did not pass teams to calculate the change in the current ((∆𝐼𝑝𝑣)). if this positive last here old duty cycle (𝐷) will be added to it duty cycle perturbation (∆𝐷) where is a fixed value and therefore is a new duty cycle. but if it is not that, there will be a decrease in the duty cycle by the same value of perturbation to calculate the new duty cycle. that there has been a change in voltage in this case calculate the value represented in the equation (14) if it were positive in this case would be a decrease in the duty cycle but if that is where there is increase, and so forth [18]. the flow chart having the algorithm that is shown in figure11: figure 11. flow chart inc algorithm iii.4. perturb &observe algorithm the perturbation and observation (p&o) is a widely used approach in the search for mppt because it is simple and requires only measures voltage and current of the pv module vpv and ipv respectively, its name suggests, the method works with p&o disturbance voltage vpv respectively, it can track the maximum power point. figure 12 shows the shortened flowchart of the p&o algorithm. at each cycle, vpv (k) and ipv (k) are measured to calculate ppv(k). ppv(k-1) value calculated in the previous cycle by vpv (k-1) and ipv (k-1). so the p&o work to generate the best duty cycle [14, 20 and 21]. -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0 0.2 0.4 0.6 0.8 1 error d e g re e o f m e m b e rs h ip ng pp pgeznp input1 -100 -80 -60 -40 -20 0 20 40 60 80 100 0 0.2 0.4 0.6 0.8 1 change error d e g re e o f m e m b e rs h ip pgng np ppez input2 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0 0.2 0.4 0.6 0.8 1 delta d d e g re e o f m e m b e rs h ip ng pgppeznp output -0.03 -0.02 -0.01 0 0.01 0.02 0.03 -100 -50 0 50 100 -0.02 -0.01 0 0.01 0.02 errorchangeerror d e lt a d mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 15 figure 12. flow chart p&o algorithm iv. system configuration and simulation results iv.1. modeling and simulations mppt-pv system is installed on the tool of simulation matlab/simulink considered as a good test, it shown in figure 13. the general system comprises a pv module and boost converter, so that pv module was created as the mathematical model of figure 1.the pv has the characteristics of table1. the variation of insolation illustrated in figure 14 and the temperature fixed at 25 ° c, the boost parameters are as follows: 𝐿 = 350 × 10−6𝐻, 𝐶1 = 𝐶2 = 560 × 10 −6𝐹, 𝑅 = 20ω. figure 13. the configuration of the pv-based system figure 14. rapidly change insolation other times to validate the operation of the algorithm proposed consider the daily evolution of the solar insolation, considered this evolution is in cloche shape shown in figure15. figure 15. cloche shape insolation iv.2. analysis of simulation results: in order to test the effectiveness of the improvement, four mppt algorithms (the p&o algorithm, the inc algorithm, the fuzzy controller and the proposed algorithm) are simulated on the pv system built in matlab. given the rapidity and the accuracy of the simulation, the simulation time is 10s, and zero-order holds of the mppt module has sampling period of 0.01s. simulation results of four mppt algorithms under sudden insolation change from 1000w/m2 to 800w/m2 at t=5s. simulation results show that: figure16 shows the ppv with and without mppt. figure16. simulation results of ppv with and without mppt algorithms 0 1 2 3 4 5 6 7 8 9 10 700 750 800 850 900 950 1000 1050 1100 time(s) in s o la ti o n (w /m 2 ) 0 1 2 3 4 5 6 7 8 9 10 400 500 600 700 800 900 1000 1100 1200 time(s) in s o la ti o n (w /m 2 ) 0 2 4 6 8 10 0 20 40 60 80 proposed algorithm time(s) p p v (w a tt ) 0 2 4 6 8 10 0 20 40 60 80 p&o times(s) p p v (w a tt ) 0 2 4 6 8 10 0 20 40 60 80 time(s) p p v (w a tt ) inc 0 2 4 6 8 10 0 20 40 60 80 fuzzy tim e (s) p p v (w a tt ) mppt controler without mppt mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 16 figure17 illustrates clearly the effectiveness of each algorithm exactly in the rapid change of the insolation. figure17. ppv illustrated exactly in the change of insolation figure 18 shows the optimum duty cycle. figure18. the optimum duty cycle figure 19 shows the 𝑃𝑝𝑣 where applying the proposed algorithm for cloche shape insolation. figure 19. ppv using cloche shape insolation applying proposed algorithm from the results obtained, we can note:  the energy increased by the mppt algorithms,  all mppt algorithms have a good dynamic response as three controllers could reach a steady state within 5s after the isolation changes rapidly except the inc algorithm, and proposed algorithm makes the system track the mpp more rapidly,  the p&o algorithm made a misjudgment when isolation changes rapidly, but the others algorithms overcome this drawback of the p&o algorithm. we observed that the proposed algorithm is the best,  the pv panel with the mppt proposed algorithm gives a good matching between the panel and the dc load under cloche shape insolation. v. conclusion mppt algorithm of the pv system is proposed in this paper. the traditional p&o algorithm shows a good dynamic response but poor stability and misjudgment. therefore the inc algorithm and the fuzzy controller are introduced to overcome these drawbacks, and the proposed algorithm is introduced to calculate the optimum duty cycle where has relationship with the power, the voltage and the load. the result shows that the pv system with the mppt gives a good matching between the panel and the dc load under various operating conditions, also it could reach the mpp rapidly, show better steady state performance and make no misjudgment. all in all, the proposed algorithm exhibits better overall performance than the p&o algorithm in both transient and steady-state response. references [1] safari a, mekhilef s. simulation and hardware. implementation of incremental conductance mppt with direct control method using cuk converter. ieee trans ind electron 2011; 58:1154–61. [2] mei q, shan m, liu l, guerrero jm. a novel improved variable step-size a novel improved variable step-size method for pv systems. ieee trans ind electron 2011;58:2427–34. [3] abdelsalam ak, massoud am, ahmed s, enjeti p. highperformance adaptive perturb and observe mppt technique for photovoltaic-based micro grids. ieee trans power electron 2011;26:1010–21. [4] anastasios i. dounis, panagiotis kofinas, constantine alafodimos, dimitrios tseles. adaptive fuzzy gain scheduling pid controller for maximum power point tracking of photovoltaic system. renewable energy, vol 60,202-214. doi:10.1016/j. renene.2013.04.014. [5] stefan daraban , dorin petreus , cristina morel. a novel mppt (maximum power point tracking) algorithm based on a modified genetic algorithm specialized on tracking the global maximum power point in photovoltaic systems affected by partial shading. energy, vol 74,374-388. doi:10.1016/j.energy.2014.07.001. [6] li.s. a mppt control strategy with variable weather parameter and no dc/dc converter for photovoltaic systems. solar energy, vol 108, 117-125. doi: 10.1016/j.solener.2014.07.002. [7] jun qi, youbing zhang, yi chen. modeling and maximum power point tracking (mppt) method for pv array under partial shade conditions. renewable energy, vol 66, 337-345. doi: 10.1016//j.renene.2013.12.018. 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 35 40 45 50 55 60 65 time(s) p p v (w a tt ) inc p&o proposed algorithm fuzzy 0 2 4 6 8 10 0.4 0.45 0.5 0.55 time(s) d u ty c y c le proposed algorithm 0 2 4 6 8 10 0.4 0.45 0.5 0.55 0.6 d u ty c y c le p&o time(s) 0 2 4 6 8 10 0.4 0.45 0.5 0.55 0.6 time(s) d u ty c y c le inc 0 2 4 6 8 10 0.4 0.45 0.5 0.55 time(s) d u ty c y c le fuzzy 4 5 6 0.4 0.6 0.8 4 5 6 0.4 0.6 0.8 4 5 6 0.4 0.6 0.8 4 5 6 0.4 0.6 0.8 0 1 2 3 4 5 6 7 8 9 10 0 10 20 30 40 50 60 70 time(s) p p v (w a tt ) mohcene bechouat et al. ijeca-issn: 2543-3717. june 2018 page 17 [8] kwei kwang chang. modeling of pv performance without using equivalent circuits. solar energy, vol 115, 419-429. doi: 10.1016/j.solener.2015.01.025. [9] aissa chouder, santiago silvestre, bilal taghezouit, engin karatepe. monitoring, modelling and simulation of pv systems using labview. solar energy, vol 91, 337– 349. doi: 10.1016/j.solener.2012.09.016. [10] abdelghani harrag , sabir messalti. variable step size modified p&o mppt algorithm using ga-based hybridoffline/online pid controller. renewable and sustainable energy reviews, vol 49, 1247–1260. doi: 10.1016/j.rser.2015.05.003. [11] jubaer ahmed, zainal salam. an improved perturb and observe (p&o) maximum power point tracking (mppt) algorithm for higher efficiency. applied energy, vol 150, 97–108. doi: 10.1016/j.apenergy.2015.04.006. [12] yanyun wang, dongwei xia and hao han. a dual-mode mppt algorithm based on the golden section point of the pv system. advanced materials research, vol 748(2013), 833-838. doi:10.4028/www.scientific.net/amr.748.833. [13] m. azzouzi. optimization of photovoltaic generator by using p&o algorithm under different weather conditions. ceai, vol.15, no.2 pp. 12-19, 2013. [14] mohamed a.eltawil, zhengmingzhao. mppt techniques for photovoltaic applications. newable and sustainable energy reviews, vol 25, 793–813. doi: 10.1016/j.rser.2013.05.022. [15] f. chekired, c. larbes, d. rekioua, f. haddad. implementation of a mppt fuzzy controller for photovoltaic systems on fpga circuit. energy procedia, , vol 6, 541–549. doi:10.1016/j.egypro.2011.05.062. [16] a. messai, a. mellit , a. massi pavan , a. guessoum, h. mekki. fpga-based implementation of a fuzzy controller (mppt) for photovoltaic module. energy conversion and management , vol 52, 2695-2704. doi:10.1016/j.enconman.2011.01.021. [17] o. wasynezuk. dynamic behavior of a class of photovoltaic power system. ieee trans. power app. syst., vol. pas-102, no. 9, pp. 3031–3037, sep. 1983. [18] guan-chyun hsieh, hung-i hsieh cheng-yuan tsai, and chi-hao wang. photovoltaic power-increment-aided incremental-conductance mppt with two-phased tracking. ieee transactions on power electronics, vol. 28, no. 6, june 2013. [19] parimita mohanty, g.bhuvaneswari, r.balasubramanian, navdeep kaur dhaliwal. matlab based modeling to study the performance of different mppt techniques used for solar pv system under various operating conditions. solar energy, vol 38, 581–593. doi: 10.1016/j.rser.2014.06.001. [20] n. femia, g. petrone, g. spagnuolo, m. vitelli. optimal sampling rate of p&o mppt technique. proceedings of pesc, aachen(germany), june 20-25.2004. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 37-43 ijeca-issn: 2543-3717. june 2019 page 37 fuzzy logic based robust dvc design of pwm rectifier connected to a pmsg wecs under wind/load disturbance conditions y. saidi 1* , a. mezouar 1 , y. miloud 1 , m. a. benmahdjoub 1 , m. yahiaoui 2 1 laboratory of electro-technical engineering, faculty of technology tahar moulay university of saïda (20000), algeria 2 university of mascara, road of mamounia, mascara (29000), algeria email*: saidi_youcef_20@yahoo.com abstract – permanent magnet generator has been widely used in variable-speed wind energy conversion system (vswecs). fuzzy logic control (flc) of the generator side converter has the ability to have a good regulation of the dc-link voltage to meet the requirements necessary to achieve optimal system operation, regardless of the disturbances caused by the characteristics of the drive train or some changes into the dc-load. the main focus of this paper is to present a model for a three phase voltage source space vector pulse width modulation (svpwm) rectifier which is connected to a pmsg in a wind turbine system, where a direct voltage control (dvc) using flc based on voltage orientation strategy is used to control the mentioned rectifier. the control algorithm employs fuzzy logic controller to effectively achieve a smooth control of dc-link voltage under wind/load perturbation conditions. some simulation results, using matlab/simulink, are presented to show the effectiveness of the svpwm rectifier connected to a pmsg wecs with the proposed control strategy. keywords: direct voltage control (dvc); permanent magnet synchronous generator (pmsg); wind energy conversion system (wecs); fuzzy logic controller (flc). received: 09/04/2019 – accepted: 20/05/2019 i. introduction recently, the ac-dc converter applications are increasing in industry, commerce and house utility. traditionally, the main parts of converters have been the diodes and thyristors bridges to rectify the ac power. these rectifiers have the advantages of being simple, robust and having low cost. however, they generate harmonics and reactive power in ac side, which results voltage distortion, poor power factor at power supply side and slowly varying rippled dc output at dc side. therefore, a threephase pwm rectifier is a more cunning solution for industrial applications, since it has more advantages such as adjustment and stabilization of dc-link voltage, sinusoidal line current, power factor control and bidirectional power flow [1]. one of the most considerable industrial applications is wind energy. nowadays, there are two types of generators which are used in large scale wind turbines to transform the wind power into electrical energy, such as: dfig and pmsg [2]. because of its ability to operate in all wind speed range and do not require excitation current, pmsg shows good performance in wind farm. as the fast development of wind power tech nology [3], the efficiency of converter device in wind power generation system has become another knotty problem to improve wind power generation system performance [2]. the three-phase voltage source pwm rectifier control based on dvc issues are traditionally treated by fixed gain pi controllers [4]. however, the fixed gain controllers are very sensitive to parameter variations and generally cannot provide good dynamic performance, such as discussed in [5]. so, the controller parameters have to be continually adapted. this problem can be solved by several adaptive control techniques such as sliding mode control (smc) [6]. the design of all of the above controllers depends on the exact system mathematical model. for the same purpose around solving these problems, the idea that a linear system is adopted as the consequent part of a fuzzy rule has evolved into the innovative takagisugeno (ts) model [7], which has become quite popular today. the fuzzy logic have gained great important, witnessed a rapid growth in industrial applications, proved their dexterity of many respects. flc can achieve satisfactory results in dealing with system, which is difficult abder image placée y. saidi et al. ijeca-issn: 2543-3717. june 2019 page 38 to de-scribe mathematically or is highly nonlinear behaviour, as described in [8], [9] which relates to the control of pwm rectifier whose energy derives from a purely electrical source. in this paper, a detail dynamic model and a simple direct voltage control (dvc) strategy using fuzzy logic controller for three-phase voltage source svpwm rectifier connected to a pmsg wind turbine with voltage orientation to improve the system’s robustness and dynamic response of the dc bus voltage is proposed. in order to improve the dynamic performances of the source current loop, the simulation results show that the flc can significantly reduce the three-phase rectifier’s voltage fluctuation, improve the dynamic response of the dcbus significantly and assist the system to operate in unit power factor with low harmonic content of current. ii. wind energy conversion system the topology of the wecs presented in this study is depicted in fig. 1. it consists of a wind turbine, a gearbox, a pmsg, generator side converter and grid side converter. in our strategy studied, the converter on the generator is used to control the dc link voltage whatever the disturbances caused by the characteristics of the wind turbine drive train or the variation in the dc load. turbine gearbox generator side converter pmsg grid side converter  grid network transformer pwm rectifier figure 1. wind energy conversion chain based on pmsg the converter on the generator is used to control the dc link-voltage whatever the disturbances caused by the characteristics of the wecs drive train or the variation in the dc load. ii.1. aerodynamic subsystem model the aerodynamic power is dependent on the power coefficient. it is given by [10], [11]:                            1311 643 2 1 32 1035.008.0 --, , 2 1 5       i c i p paer cecc c cc vrcp i (1) where:  – air density [ 3mkg ], r – blade length [m ], v – wind velocity [ sm ]. the power coefficient pc depends on the ratio  and the pitch angle  is shown in fig. 2. the aerodynamic torque aert is calculated by the ratio of the aerodynamic power aerp to the shaft speed t : t aer aer p t   (2) c p � 0 5 10 15 -0.2 0 0.2 0.4 0.6 � = �° � = ��° � = ��° � = ��° � = �° ���� ��� figure 2. power coefficient variation against tip speed ratio and pitch angle the turbine is usually attached to the generator via a gearbox whose gear ratio g is chosen to adjust the speed of the generator column at the required speed range. the torque and shaft speed of generator are given by:       g gtt tg aerg 1 (3) where: g – generator shaft speed, gt – torque of the generator. by using the equation (3), the shaft system dynamics can be described as [12]: gvemgg fttj   (4) where: emt – electromagnetic torque, j – equivalent inertia, vf – viscous friction. fig. 3 illustrates a typical characteristic giving the aerodynamic power of a wt-s which is also used in the simulation section. the extractable power is shown versus the rotor speed for different wind speed values. each diagram for a constant wind speed has a peak value in which the pair ( opt,g , max,aerp ) are relevant. y. saidi et al. ijeca-issn: 2543-3717. june 2019 page 39 p a er [ p u ] g [pu] 0 100 200 300 400 500 0 1 2 3 4 x 10 4m/s 6m/s 8m/s 10m/s 14m/s 12m/s 0.4 0.8 1.2 1.4 1.8 mppt pitch control 0 0.5 1 1.5 2 figure 3. aerodynamic powers various speed characteristics ii.2. electrical subsystem model the circuit diagram of the three-phase two level voltage source rectifier structure connected to a pmsg wind energy conversion system is shown in fig. 4. in order to set up math model, it’s assumed that the filter reactor is linear, igbt is ideal switch and lossless [13]. and gearbox voltage control dci ci rr lr , t a b c c li dcv lr pmsg turbine figure 4. circuit schematic of pwm rectifier connected to pmsg wecs where asi , bsi and csi , are phase currents, c is smoothing capacitor across the dc bus, lr is the load resistance, and li is load current. the classical electrical equations of the pmsg and converter in the park frame are written as follows [14], [15]:                      l dc qsqdsd dc qemqsrsqsrsqs demdsrsdsrsds r v isis dt dv c fi dt d llirrv fi dt d llirrv , , (5) with d,emf and q,emf are the crosses coupling terms between the d-axis and q-axis:          fdsrsqem qsrsdem illf illf , , (6) where sr , sl , rr , rl ,are the stator phase resistance and inductance, the rectifier line resistance and inductance, respectively and pmsgg p is the electrical speed and pmsgp is the pair pole number, dsi and qsi are the direct and quadrate stator currents, f is magnetic flux. ds , qs are input voltage of rectifier, switch function in synchronous rotating d-q coordinate, respectively and dcv is the dc-bus voltage. the electromagnetic torque is expressed as [16]: qsfpmsgem ipt  2 3 (7) iii. direct voltage control (dvc) strategy in this section, the principle of this control (dvc) based on voltage orientation consists of using a current loop, developed by analogy with the vector control of electrical machines. it consists of orienting the current vector in the same direction as that of the voltage vector, by controlling the current vector in the two revolving d-q axes. regarding fig. 5, the current of the d-axis is set to zero while the reference current qsi is set by the dc link voltage regulator. figure 5. voltage orientation once the rectifier is connected to an existing load, the transit of direct and quadrature axis currents must be controlled separately. to obtain a decoupled currents control of rectifier, the method based on voltage orientation can be regarded as the efficient one. there are three control loops in the dvc strategy. the error between the reference dc-bus voltage *dcv and the sampled dc-bus voltage dcv is processed by flc, which produces the reference active current *qsi . as in the inner loops, d-axis currents loop and q-axis current loop use pi controllers to make the actual currents ( dsi and qsi ) track their reference values ( *dsi and * qsi ). then, the errors are processed in two conventional pi controllers to produce the output signals of *dsv and * qsv , after coordinates transformation, *sav , *sbv and * scv o  qo  si  qsi dsi si α si  sv  sv α sv  do  o  sqs ii  , 0dsi y. saidi et al. ijeca-issn: 2543-3717. june 2019 page 40 which can be obtained and used to produce switching signals as , bs and cs by two-level space vector pulse with modulation (svpwm). consequently, the proposed currents control can then be applied, as depicted in fig. 6, considering that the direct and quadrature axis currents considered as variables to be controlled. with:    srssrs lltrra  1;1 st a s s 1 + * ds v dsi st a s s 1+ * qsv qsi 1,qsv demf , qemf , + + 1,dsv  dsicontroller  qsicontroller demf , ˆ qemf , ˆ + + * 1,dsv * 1,qsv dsi + + * dsi * qsi model of rectifier currents rectifier current control qsi figure 6. the block diagram of direct and quadrature axis currents control iv. controller design iv.1. pi regulator synthesis in order to control the converter used, we must perform a decoupling by compensation. to make the “d” and “q” axes completely independent. the parameters of the corrector are calculated with a method of imposition of the poles. it is possible to generate reference voltages from given reference quantities. the design of this controller is simple. fig. 7, 8 shows the system scheme regulated by a pi corrector. consequently, the proposed currents control can then st a s s 1 s k k s,i s,p  * ds i s + * ds v dsi figure 7. direct current regulation loop st a s s 1s k k s,i s,p  * qsi s + * qsv qsi figure 8. quadrature current regulation loop in fact, the errors ( ds * ds ii  ) and the errors  qs*qs ii  are processed by the pi corrector, in order to design the reference voltages * s,dqv . using the laplace transformation, the closed-loop transfer function is given as follows:   s si s sps sisp s s t ka t ka ss ksk t a cltf ,,2 ,, 1           (8) the calculated terms are in these tables: table 1. the calculated pi gains spk , sik , pi controller   ss at /1-2 0 ss at /20 value 150 10 4.2. fuzzy logic controller (flc) to regulate the dc voltage, flc is used because of the nonlinearity of the system. the basic formation of a flc is consisted of four parts: fuzzification block determining inputs membership values. the fuzzy inference system fis evaluates at each time which control rules are appropriate, using the fuzzy knowledge based block. the deffuzification block calculates the crisp output of the rules leading to the optimal plant control [17, 18]. fig. 9 shows the block diagram of the fuzzy control. d ef u zz if ic at io n f u zz if ic a ti o n inference system rules base u ukek dek dt d e de *y y + figure 9. fuzzy logic controller structure the input and output linguistic variables of the fuzzy controller have been quantized in the following five fuzzy subsets. where the error e and its rate of change de are the input variables; ek , dek and uk are inputs and outputs scaling gains. for the proposed flc of dc link voltage, we use diagram scheme of fig. 10. table 2. fuzzy rule-base for the controller ε dε nl ns ze ps pl nl nl nl nl ns ze ns nl ns ns ze ps ze nl ns ze ps pl ps ns ze ps ps pl pl ze ps pl pl pl there are two input signals to the flc; the first input is the error between the reference and the measured value of the dc voltage, the second one represents the variay. saidi et al. ijeca-issn: 2543-3717. june 2019 page 41 tion of this error. these two signals are expressed by:      )1()()( )()()( * * nvnvne nvnvne dcdcdc dcdcdc (9) v. results and discussion the fuzzy sets have been determined as: nl, negative large, ns, negative small and ze, zero, ps, positive small, pm positive medium, pl, positive large, respectively. the input/output variables used in this paper are fuzzified by seven symmetrical and triangular membership functions (mfs) (fig. 10(a), (b) and (c)) normalized in the universe of discourse between -1 and +1. the flc surface is depicted in fig. 10(d). then, the outputs of the dc-link voltage fuzzy controller are *qsi . finally, the overall simulation scheme of a three phase pwm rectifier under dvc strategy connected to a pmsg wecs is given in fig. 11. -1.00 -0.35 0 0.35 0.70 1.00 nl ze pl 1.0 ns ps -0.70 1.0 e e -1.00 -0.35 0 0.35 0.70 1.00 nl ze pl 1.0 ns ps -0.70 1.0 de de (a) (b) -1.00 -0.35 0 0.35 0.70 1.00 -0.70 nl ze pl 1.0 ns ps 1.0 du du (c) (d) figure 10. the memberships of the: (a) – error, (b) error variation, (c)command variation, (d) control surface turbine g pmsg t asi bsi csi dq abc dsi qsi qsrs ill )(  fdsrs ill  )(demf , qemf , s v p w m dq αβ demf , pi pi * qsv * sv qsi dsi * ds i * qsi * dc v dcv + dcv g s c  dt d encodeur  * sv qemf , * dsv + + + + lr gearbox figure 11. the block diagram of the proposed dvc approach fig. 12a shows the input phase current of svpwmrectifier. as can be seen in this figure, the current wave has a sinusoidal shape with very low harmonic distortion. the fft analysis is applied to the line current of phase a of the rectifier. this analysis gives 0.62 [pu] as an effective value for the fundamental component of line current (thd about 2.25%) that is shown in fig. 12b, is improved when compared to conventional voltage orientation technique (thd=16.06%) [5]. so, it is found that most of the harmonics are low ranks. s ig n a l [p u ] 0.445 0.45 0.455 0.46 0.465 -1 0 1 (a) time [s] m ag ( % o f f u n d am en ta l) 0 5 10 15 20 0 50 100 fundamental (50hz) = 0.9417 , thd= 2.25% 0 10 20 0 1 2 (b) harmonic order figure 12. harmonic spectra of line current of phase a of the rectifier all the simulation results were elaborated with a fixed-step size of 0.1 [ms] with a view to digital implementation in future works. three tests are under study to prove the robustness dynamic response of the proposed dvc approach, firstly the variation on the wind speed (9 to 7 [m/s]) at t=0.5[s] as shown in fig. 13a, then the variation on the reference voltage of dc link (0.8 to 1 [pu]) at t=1[s] is shown in fig. 13c and dc load resistance variation (500 to 5*500[ω]) at t=1.5[s] is seen in fig. 13b. fig. 13c shows the output dc voltage. as can be seen in this figure, the dc-link voltage, after a short transient time, is correctly regulated at its reference voltage (0.8 then 1 [pu]) with soft regulation without over-hoots. the mechanical speed of the pmsg shaft is given in fig. 13d, it is clear that it takes the same shape as the wind speed. y. saidi et al. ijeca-issn: 2543-3717. june 2019 page 42 the electromagnetic torque is shown in fig. 13e, with a negative value, which proves that the machine used functions as a generator. fig. 13f shows the setting of direct and quadrature axis currents. the d-axis current is maintained at its zero reference value, while the q-axis current regulation is done by reference dc-voltage control. however, the effect of the coupling between the two control axes (d and q) is observed, since the variation on the reference dc voltage at time t=1[s] induces low oscillation on the d-q axis currents. v [ m / s ] ω g [ p u ] 0 0.5 1 1.5 2 0 5 7 9 10 (a) time [s] 0 0.5 1 1.5 2 0 0.5 1 1.2 0.5 1 1.5 2 0.7 0.72 0.74 (d) time [s] r l [ ω ] t e m [ p u ] 0 0.5 1 1.5 2 500 1 500 2 500 0 3000 (b) time [s] 0 0.5 1 1.5 2 -2 -1.5 -1 -0.5 0 0.5 (e) time [s] v d c [ p u ] i d q , s [ p u ] 0 0.5 1 1.5 2 0 0.5 0.8 1 1.2 vdc* vdc 1.45 1.5 1.55 1.6 0.995 1 1.005 1.01 1.015 (c) time [s] 0 0.5 1 1.5 2 -1.5 -1 -0.5 0 0.5 1 iqs ids (f) time [s] figure 13. simulation results: (a) wind speed profile, (b) load resistance variation, (c) dc-link voltage, (d) generator speed, (e) electromagnetic torque, (f) d-q axis current appendix in this part, simulations are investigated with a 1.5 mw generator wind turbine [19]. the parameters of the turbine are presented below: turbine pmsg rectifier 3/22.1 mkg mwpsn 5.1 mhrr 37 mr 25.35 80pmsgp  3,0rl deg0  mrs 17.3 fc  1100 30g mhls 07.3 wbf 7.0172 vi. conclusion a cascaded control algorithm was properly designed to ensure the optimal operation of the whole system, based on fuzzy logic controller (flc) with voltage orientation technique. furthermore output dc link voltage is smooth despite a wind/load fluctuation. the control system based on dvc includes two pi controllers which are used to regulate the ac current and an outer dc voltage loop is composed by flc strategy. the simulation results shows a good performance and a robust control of dvc proposed method at startup and during wind/load variations, providing a good regulation of output dc voltage, sinusoidal ac current and low total harmonic distortion. it can be concluded from the simulation results, which demonstrate the inherent ability of the dvc fuzzy logic controller to deal with this kind of noise operation under wind/load disturbance conditions. references [1] y. saidi, a. mezouar, y. miloud, ma. benmahdjoub. “a robust control strategy for three phase voltage source pwm rectifier connected to a pmsg wind energy conversion system”, presented at the 3rd ieee international conference on electrical sciences and technologies in maghreb, algiers, algeria, 546-551, 2018. [2] a. ben amar, “direct torque control of a doubly fed induction generator”, international journal of energetica, vol. 2, pp.11-14, 2017. [3] y. saidi, a. mezouar, y. miloud, ma. benmahdjoub, m yahiaoui, “design of a maximum power tracking control strategys for pmsg wind turbine applications”, presented at the 1st national conference on electro-technics and renewable energies, saida, algeria, 15, 2018. [4] m. devadarshanam, m. chinnalal, b. shankaraiah, and s. manohareddy, “simulation of 3-phase pwm line converter based on direct voltage control,” int. jour. of adv. res. in comp. sci. and soft. eng., vol. 3, pp. 1085-1089, 2013. [5] m. p. kumar and k. p. mahavishnu, “an illustrative study on the control strategies for the boost type of three-phase bridge pwm rectifiers”. presented at the ieee international conf. in electrical, electronics, and optimization techniques, chennai, india, 4691-4698, 2016. [6] m. a. fnaiech, m. trabelsi, s. khalil, m. mansouri, h. nounou, and h. abu-rub, “robust sliding mode control for three-phase rectifier supplied by non-ideal voltage,” control engineering practice, vol. 77, pp. 73-85, 2018. [7] t. takagi and m. sugeno, “fuzzy identification of systems and its applications to modeling and control,” ieee transactions on systems, man, and cybernetics, pp. 116132, 1985. [8] l. hang, s. liu, g. yan, b. qu, and z.-y. lu, “an improved deadbeat scheme with fuzzy controller for the grid-side three-phase pwm boost rectifier,” ieee transactions on power electronics, vol. 26, pp. 11841191, 2011. [9] k. bhanu priya and d. r. r. pvv, “fuzzy based three phase voltage source pwm rectifier for rapidily varying active load,” international journal of advanced research in electrical, electronics and instrumentation engineering, vol. 2, pp. 2320-3765, 2013. [10] y. saidi, a. mezouar, y. miloud, “analyse dynamique d'une système éolienne à vitesse variable basée sur un gsap lors d’un creux de tension du réseau,” la y. saidi et al. ijeca-issn: 2543-3717. june 2019 page 43 première journée d’étude sur l’electrotechnique (jee’17), 2017. [11] k. d. e. kerrouche, a. mezouar, l. boumediene, and a. van den bossche, “modeling and lyapunov-designed based on adaptive gain sliding mode control for wind turbines, ” journal of power technologies, vol. 96, pp. 124-136, 2016. [12] y. saidi, a. mezouar, y. miloud, ma. benmahdjoub, “modeling and comparative study of speed sensor and sensor-less based on tsr-mppt method for pmsgwt applications”, international journal of energetica, vol. 3, pp. 6-12, 2018. [13] t. r. de freitas, p. j. menegáz, and d. s. simonetti, “rectifier topologies for permanent magnet synchronous generator on wind energy conversion systems: a review, ” renewable and sustainable energy reviews, vol. 54, pp. 1334-1344, 2016. [14] k. hartani and y. miloud, “control strategy for three phase voltage source pwm rectifier based on the space vector modulation,” advances in electrical and computer engineering, vol. 10, pp. 61-65, 2010. [15] y. saidi, a. mezouar, y. miloud, ma. benmahdjoub, “ speed sensor-less control for three phase voltage source pwm rectifier connected to a pmsg variable speed wind turbine”. presented at the 2nd international conference on artificial intelligence in renewable energetic, esc-koléa, tipasa, algeria, 2018. [16] y. saidi, a. mezouar, m. yahia. “modeling and control of a wind energy conversion system based on a pmsg”. presented at the 2nd algerian multi-conf. on comp., elec. and electro. eng., algiers, algeria, 1-5, 2017. [17] n. watanakul, “an application of wind turbine generator on hybrid power conditioner to improve power quality,” international review of electrical engineering (iree), vol. 7, pp. 5487-5495, 2012. [18] a. berboucha, k. djermouni, k. ghedamsi, d. aouzellag, “fuzzy logic control of wind turbine storage system connected to the grid using multilevel inverter”, international journal of energetica, vol. 2, pp. 15-23, 2017. [19] m. nasiri, j. milimonfared, and s. fathi, “a review of low-voltage ride-through enhancement methods for permanent magnet synchronous generator based wind turbines, ” renewable and sustainable energy reviews, vol. 47, pp. 399-415, 2015. i. introduction ii. wind energy conversion system ii.1. aerodynamic subsystem model ii.2. electrical subsystem model iii. direct voltage control (dvc) strategy iv. controller design iv.1. pi regulator synthesis v. results and discussion appendix vi. conclusion international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 2. issue 1. 2017 page 29-41 ijeca-issn: 2543-3717. june 2017 page 29 insight into rotational effects on a horizontal axis wind turbine nrel phase ii using cfd simulation and inverse bem riyadh belamadi 1 , mdouki ramzi 2 , adrian ilinca 3 , djemili abdelouaheb 1 1mechanical of materials and industrial maintenance laboratory lr3mi, university of annaba, algeria 2energy and turbomachinery laboratory, mechanical department, university of tébessa, algeria 3wind energy research laboratory, university of québec at rimouski 300, québec, canada belaamdi.riyadh@gmail.com abstract – the present work aims to study the aerodynamic characteristics of the nrel phase ii rotor (generated only with s809 profile along the span for an untwisted case) that is a horizontal axis downwind wind turbine rotor and which is assumed to stand isolated in the space. the threedimensional steady-incompressible flow reynolds averaged navier-stokes equations are solved by using the commercial cfd package ansys fluent and, the turbulence closure model k-ω with shear stress transport correction was adopted for all computations. the computations were done for wind speed of 7.2, 10.56, 12.85, 16.3, and 9.18 m.s -1 . results of pressure and torque for considered wind turbine rotor have been directly compared to the available experimental data. the comparisons show that cfd results along with the turbulence model can predict the spanwise loading of the wind turbine rotor with reasonable agreement. secondly, a comparison of lift and drag coefficients was made between the results obtained using the inverse algorithm bem based on the calculated pressure distributions and the experimental test data. the result show that the general trend is similar for all sections of the scale, however, large deviation exists between the 2-d and 3-d case. keywords:cfd computation, rans, horizontal axis wind turbine, inverse bem, rotational effect, turbulent flow. i. introduction wind energy is becoming a significant contributor to the world’s electrical energy generation systems and it is the fastest growing source of energy in the world today. numerical solution of flows through wind turbines is increasingly useful since it helps reduce time and costs in wind turbine development. the literature reports various methods that compare numerical predictions to experiments. the blade-element momentum method [1] consists of dividing the flow in annular control volumes and applying momentum balance and energy conservation in each control volume. the method is indeed computationally cheap and thus very fast, providing very satisfactory results [2]. in the actuator disc method, the rotor is represented by a permeable disc that allows the flow to pass through it. the classical actuator disc model is based on conservation of mass, momentum and energy, and constitutes the main ingredient in the 1-d momentum theory, as originally formulated by rankine and froude [3]. vortex lattice [4], lifting line, panel and vortex methods are also used to predict and design wind turbine rotors [5]. this list is far to be exhaustive. the first applications of cfd to wings and rotor configurations were studied back in the late seventies and early eighties, in connection with aircraft wings and helicopter rotors, using potential flow solvers. in the field of aerodynamic research this technique has become increasingly important and it is prominent for studying turbo machinery. natalino et al [6] used the rans (reynolds averaged navier-stokes) equations to solve the 3-d turbulent-steady incompressible flow of hawt, the results show that the predicted values of the power generated are in good agreement with those calculated with bem method using the spalart-allmaras and the kω sst turbulence models for closure. le pape and lecanu [7] performed several 2-d and 3-d navierstokes computations with the compressible elsa solver and compared with test results by nrel in the nasa ames large wind tunnel. the results of 2-d computation show that the k-ω with the addition of sst correction gives the best results. indeed the sst correction allows to detect the stall angle of the airfoil. according to the same authors, for the 3-d computation, the comparison of the torque with experiments shows good agreement at low wind speeds but important differences at high speeds. rans solver was also used for prediction of aerodynamic loads on nrel phase ii, iii and vi, the result showed good agreement with experimental results [8, 9]. wind turbine blades are strongly affected by the effects of rotation and 3-d flow and they often operate under stall conditions. however, the actual design approach is generally based on the use of the theory of riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 30 the blade element (bem), with the lift and drag forces determined from measurements in 2-d. the results obtained are reasonably accurate in the vicinity of the design point, but in stalled conditions, bem is known to under predict the forces acting on the blades [10]. in addition, the accurate prediction of the aerodynamic load of the rotor, even in stalled conditions, is of great importance for the dimensioning of the generator and other mechanical components. in 1945 himmelskamp [11] described by measurements the 3-d and rotational effects on the boundary layer of a propeller, where he found that the lift coefficient is higher when moving towards the axis of rotation. later, other experimental studies have confirmed these initial results. measurements were performed on wind turbine blades by ronsten [12], showing the differences between the pressure coefficient of a rotating and non-rotating blades. tangler and kocurek [13] combine the results of measurements with classical bem method to correctly compute lift and drag coefficients and the rotor power under stall conditions. the theoretical foundations of the analysis of the rotation effects of rotating blades come thereafter, with sears [14] who derived a set of equations for the potential flow field around a cylindrical blade infinite range in pure rotation. he said that the radial component (spanwise) of the speed depends only on the potential flow and is independent of the span. then fogarty and sears [15] extended the first study on the potential flow around a rotating blade. they confirmed that the tangential and axial velocity components are the same as in the case of 2-d at the local relative speed and the local angle of attack. a more complete work was done by fogarty [16], which consists of the numerical calculations of the laminar boundary layer of a hub and a blade with a thickness. it is shown that the line of separation of the boundary layer is not affected by the rotation, the spanwise velocity in the boundary layer appeared small compared to the chordwise direction, and no large effect of the rotation was observed, contrary to what has been described in the work of himmelskamp [11]. a theoretical analysis was made by banks and gadd [17], focused on demonstrating how the rotation delays the separation of the laminar boundary layer. they found that the point of separation is delayed due to the rotation. the so-called secondary effects in the laminar incompressible boundary layer propeller and the rotor helicopters are extensively studied in the nasa report by mccroskey and dwyer [18] by means of a combined numerical and analytical approach. they showed that approaching the axis of rotation, the coriolis force in the cross flow direction becomes more important. on the other hand, the centrifugal pumping effect is much lower than it was supposed before, but its contribution increases when the magnitude of the adverse pressure gradient increases. in the last decades, many studies were done on the rotating boundary layer using the computational fluid dynamics cfd. sorenson [19] numerically solved the 3d equations of the boundary layer on a rotating surface, using a viscous-inviscid interaction model. snel et al. [10] are introducing a quasi-3d approach, based on viscous-inviscid interaction approach and compared with measurement. du and selig [20] approached the problem by solving the 3-d incompressible steady boundary layer equations. also, a study of stall delay for wind turbines was done by hu et al. [21] using the full n-s computations, wind tunnel measurement and boundary layer analysis. the airfoil characteristics used in bem codes are mostly based on 2d wind tunnel measurements of airfoils with constant span. however, a bem code using airfoil data obtained directly from 2d wind tunnel measurements will not yield the correct loading and power. owing to the 3d nature of the flow over wind turbine blades, the measured airfoil characteristics will be different from the real characteristics. the flow will be altered partly due to the 3d properties of the blade geometry, which is most pronounced at the thick root section and near the blade tip, and partly because of rotational effects in the boundary layer. as a consequence, 2d airfoil characteristics have to be corrected before they can be used in a bem code. for this purpose, the work presented here aims at giving a better understanding of the main influence of the rotational effect on the boundary layer and the determination of the effective angle of attack based on the numerical investigation of a three-bladed small-sized rotor from the viscous and aeroelastic effects on wind turbine blades phase ii project [22]. the flow model is three-dimensional, at steady state, incompressible regime and the flow field is always assumed to be fully turbulent. ii. numerical procedure ii.1. turbine geometry the experimental data for nrel phase ii is obtained from the iea annex xiv database [22]. this database was built as a contribution of many european research labs and the nrel to store and document the experimental data for various tested wind turbines and make it available to researchers. nrel phase-ii rotor mounted on a downwind machine is a small three bladed hawt rotor with 5.029 m radius [23], as shown in figure 1. the blades of the phase-ii rotor are non-twisted and non-tapered with a constant cord of 0.4572 m. the nrel s809 airfoil (figure 2) series is used, except for the root. at 14.4% span the airfoil thickness is t/c=43% and decreases linearly to t/c=20.95% at 30% span, while outboard of 30%, thickness is constant at that value. the nominal rotation speed is 71.68 rpm and the pitch is 12 degree. ijeca-issn: 2543-3717. june 2017 table 1. nrel phase ii blade description number of blades 3 rotor diameter 10.06 m rpm 72 tour/min rotor location downwind root extension 0.723 m pitch angle 12° blade profile s809 blade chord length 0.4572 m, constant along the span twist angle 0° blade thickness at 14.4% span, t/c = 43% at 30% span, t/c = 21% outward t/c = 21% figure 1.nrel phase ii roto figure.1 nrel phase ii roto . figure 2.nrel s809 airfoil geometry riyadh belamadi et al. 7 table 1. nrel phase ii blade description 10.06 m tour/min downwind 0.723 m s809 0.4572 m, constant along the span at 14.4% span, t/c = 43% at 30% span, t/c = 21% outward 30%span, t/c = 21% nrel phase ii roto. figure.1 nrel phase ii roto figure 2.nrel s809 airfoil geometry ii.2. computational domain and grid at the initial stages of the project, efforts were focused on trying to create and compare different cells and types; structured, unstructured, c type. due to its advantage, it was decided to use a structured h-type mesh, therefore increasing the grid generation times. it also has to be noted that although the rotor is featured with three blades, only one blade is actually being treated by exploiting the 120 degrees periodicity of the three-bladed rotor (figure 3). the wind turbine tower and the ground effect were neglected; the computational domain is enclosed between a small inner cylinde euler-slip wall boundary condition was imposed and an outer cylinder with a symmetry boundary condition, the length of the radius of the domain equal to 3 times the rotor diameter (r) to eliminate far field effects. the inlet was placed at 2r upstream of the blade where a uniform wind speed was assumed as velocity inlet boundary condition. turbulence conditions also have to be defined here with the fixed value of turbulent intensity and viscosity ratio. pressure outlet boundary condition was applied at 10r on the downstream direction of the rotor and sets the pressure at the boundary at a specific static pressure value. in this study, the obvious choice was to put the value equal to zero so that the pressure at the outlet would be equal to the atmosp pressure. as shown in figure 4, the solution has been done for only one third of the domain, includes one blade, and uses periodic boundary condition in order to account for all three blades with full domain. a hexahedral mesh of approximately 3.5 million cells (255x168x75 in x, y and z respectively) was generated. the thickness of the first cell to the wall was kept at 0.00002 m (figure 5.c) so that the y+ value falls between 1 and 5 which is suitable for k-ω with sst correction model. figure 3.one third-cylindrical domain and boundary condition page 31 computational domain and grid at the initial stages of the project, efforts were focused on trying to create and compare different mesh cells and types; structured, unstructured, c-type and htype. due to its advantage, it was decided to use a type mesh, therefore increasing the grid it also has to be noted that although the rotor is blades, only one blade is actually being treated by exploiting the 120 degrees periodicity of bladed rotor (figure 3). the wind turbine tower and the ground effect were neglected; the computational domain is enclosed between a small inner cylinder where slip wall boundary condition was imposed and an outer cylinder with a symmetry boundary condition, the length of the radius of the domain equal to 3 times the rotor diameter (r) to eliminate far field effects. the inlet eam of the blade where a uniform wind speed was assumed as velocity inlet boundary condition. turbulence conditions also have to be defined here with the fixed value of turbulent intensity and viscosity ratio. pressure outlet boundary condition was at 10r on the downstream direction of the rotor and sets the pressure at the boundary at a specific static pressure value. in this study, the obvious choice was to put the value equal to zero so that the pressure at the outlet would be equal to the atmospheric operating as shown in figure 4, the solution has been done for only one third of the domain, includes one blade, and uses periodic boundary condition in order to account for all three blades with full domain. a hexahedral mesh of ely 3.5 million cells (255x168x75 in x, y and z respectively) was generated. the thickness of the first cell to the wall was kept at 0.00002 m (figure 5.c) so that the y+ value falls between 1 and 5 which is suitable for ω with sst correction model. cylindrical domain and boundary condition. ijeca-issn: 2543-3717. june 2017 (a) all domain (360°) (a) periodicity application (120 figure 4.structured mesh of the domain (a) blade root. (b) blade tip (c) wall modeling approach (d) surface mesh figure 5. 3-d mesh for nrel phase ii ii.3. solution method the equations of the fluid flow are usually solved by fluent in a stationary reference frame. however, there are many problems that require the equations be solved riyadh belamadi et al. 7 all domain (360°). periodicity application (120°). structured mesh of the domain. lade tip (d) surface mesh d mesh for nrel phase ii. solution method the equations of the fluid flow are usually solved by fluent in a stationary reference frame. however, there are many problems that require the equations be solved in a moving reference frame. a rotating rotor of a wind turbine is such case. the one used h moving reference frame (srf). this latter permits an unsteady problem respect to the absolute reference frame to become steady in respect to the moving reference frame (figure 6). in simple words, the whole computational domain is assu angular velocity of the turbine rotor [24]. this particular method is well suited for this problem since there is only one rotating wall. the fluid velocities can be transformed from a stationary frame to a rotating frame in respe flowing equations: �⃗�=�⃗ − where ��⃗ � = ���⃗ × where, v�⃗ �is the relative velocity (viewed from a rotating frame), v�⃗ is the absolute velocity (viewed from a stationary frame), and u�⃗ �is the whirl velocity due to the rotating coordinate system. figure 6.rotating reference frames in view of stationary reference frames [24] the pressure-based discretization scheme i applied with coupled algorithms, which solve in one step the system of momentum and pressure equation. the solution was initialized with first upwind discretization scheme for all variables; pressure, momentum and turbulence convergence is achieved, it can switch to second order. this is done in order to limit convergence problems. the number of iterations adjusted to reduce the scaled residual below the value of 10 convergence. for each run, the observations of the static pressure, lift and drag coefficient were appointed for convergence of the solution. in previous work [25], 2 page 32 in a moving reference frame. a rotating rotor of a wind the one used here is called single moving reference frame (srf). this latter permits an unsteady problem respect to the absolute reference frame to become steady in respect to the moving reference frame (figure 6). in simple words, the whole computational domain is assumed to be rotating at the angular velocity of the turbine rotor [24]. this particular method is well suited for this problem since there is only the fluid velocities can be transformed from a stationary frame to a rotating frame in respect with − ��⃗ � (1) �⃗ (2) is the relative velocity (viewed from a rotating is the absolute velocity (viewed from a is the whirl velocity due to the rotating reference frames in view of stationary reference frames [24]. based discretization scheme is being applied with coupled algorithms, which solve in one step the system of momentum and pressure-based continuity equation. the solution was initialized with first-order upwind discretization scheme for all variables; pressure, momentum and turbulence equations, when some convergence is achieved, it can switch to second order. this is done in order to limit convergence problems. the number of iterations adjusted to reduce the scaled residual below the value of 10-5 which is the criterion of for each run, the observations of the static pressure, lift and drag coefficient were appointed for the -d computations are first riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 33 performed on the “classical” s809 airfoil in order to validate the computational setup and define the most suitable turbulence model among four possible choices (standard k–ε, spalart–allmaras, k–ω and k–ω sst). based on comparison with experimental data, the computational results show that all the chosen turbulent models demonstrated good accuracy for solving the flow. the k-ω turbulence model with sst correction has been used for all steady state cfd simulations. iii. results iii.1. pressure distribution the quantity and type of results that can be extracted from this type of numerical study is large, starting from integral aerodynamics, to pressure distribution and up to wake study. provided the aim of this study, results will restrict to pressure distribution on the blade, lift and drag coefficient, generated torque and a general overview of the flow field around the rotor. the numerical pressure distribution is presented and compared with experimental results at 30, 47, 63 and 80% spanwise locations for wind speed 7.2, 12.9 and 19.18m.s -1 . at 7.2 m.s -1 , the computed pressure distribution at all sections of the blade is in good agreement with the experimental data (figure 7). at this wind speed, the flow is completely attached and no separation occurs except up to 30% span, where flow is separated on 30% chord length and we observe some deviation that is due to a known difficulty of rans turbulence models in solving separated flow. at 12.85 m.s -1 , important discrepancies between the computed and experimental pressure distribution on the suction side are observed in the r/r=0.30 section near the blade root (figure 8). disagreement seems to increase with wind speed and especially for the suction side of the blade; at this speed stronger vortices were formed close to the root which explains such discrepancy. at 19.18 m.s -1 , again there are differences at r/r= 0.3 on the suction side. at r/r=0.8 we observe a disagreement with the experimental result near the leading edge on the suction side as shown in figure 9. at this speed, due to the stronger vortices formed at the root and the tip of the blade it is very difficult to capture the separation characteristic using rans turbulence models. iii.2. flow visualization since the relative velocity magnitude gives a more information for airfoil aerodynamics, the separation is investigated by plotting the streamlines and contour of relative velocity magnitude at different spanwise blade sections. the plots were obtained for wind speeds of 7.2, 12.85 and 19.18 m.s-1. in (figure 10) can be observed that at 7.2 m.s-1 the flow is attached on most of the blade surface except for small regions at r/r= 0.3. the results obtained support the previous discussion (figure 7), where the pressure distribution in good agreement with experimental results. at 12.85 m.s-1, the results give more precise information figures 10; it can be observed that the separation with tow vortices occurs at r/r=0.3 on the suction side. the number of vortices decreases to one vortex at r/r=0.47 and vanishes at r/r=0.63 and r/r= 0.8. again, the results support the previous discussion (figure 8). the discrepancy in pressure distribution also decreases as one goes from root to tip. at 19.18 m.s-1, the separation effects are magnified at all blade sections (figure 10), this explains the deviation of computed pressure distribution from experimental results for these sections (figure 9). to give more precise information, the development of the limiting streamlines with static pressure contour for both blade sides is shown in figure 11. at 7.2 m.s -1 can be observed that on the suction side the separation starts from the root to r/r=30%, due to the strong 3-d effects. at 12.85 m.s -1 separation seems to be widely experienced at r/r=80 % of the blade, while the separation occupies most of the suction side at 19.18 m.s -1 except for a small area near to the blade tip. on a rotating blade there are two main forces play an important role in separated boundary layer, i.e. the centrifugal forces that produce a spanwise pumping effect that leads to the deviation of the streamlines in spanwise direction towards the tip. on the other hand, coriolis force, which acts in the chordwise direction as a favourable pressure gradient that tends to delay separation. riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 34 figure 7.pressure distribution comparison between experimental and calculated at different spanwise sections at 7.2 m.s-1 for nrel ii. figure 8.pressure distribution comparison between experimental and calculated at different spanwise sections at 12.83 m.s-1 for nrel ii. riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 35 figure 9.pressure distribution comparison between experimental and calculated at different spanwise sections at 19.18 m.s-1 for nrel ii. 12.85 m.s -1 figure 10.relative velocity contours for all radial stations for different wind speeds. 7.2 m.s-1 12.83 m.s-1 19.18 m.s-1 riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 36 iii.3. performance the comparisons for the rotor torque are shown in table 2. at 7.2 m.s -1 the computed torque has a better agreement with strain gages measurement than with the generator measurement; while at 10.56 m.s -1 the trend is reversed. this is perhaps due to the fact that at low wind speeds the blade flapping is low, thus the strain gage measurement is accurate while the generator correlation is not accurate in this region because it is far from its design operating condition [26]. with increasing speed, the blade flapping strengthens while the generator gets closer to its design operating range, hence the reverse behavior. table 2.torque prediction errors at wind speeds 7.2 and 10.56 m.s-1 for nrel ii.. wind speed [m.s-1] cfd experiment strain gage generator torque [nm] torque [nm] error [%] torque [nm] error [%] 7.2 290.51 286.22 1.49 317.26 -8.43 10.56 1088.56 1207.39 -9.84 1190.04 -8.52 (a) suctionside (b) pressure side t.e l.e 7.2 m.s-1 12.85 m.s-1 19.18 m.s-1 figure 11. limiting streamlines with static pressure contour of nrel phase ii rotor at different wind speeds. ijeca-issn: 2543-3717. june 2017 in comparing the rotor torque derived power against the generator power, it was found that the efficiency did not match the published efficiency. as a result, a better curve fit between mechanical and generator power was found in [27], as described below: ���������� = 0.9036 ����������� − the computed power as a function of the wind speed is shown in figure 12 against the experimental iea data [22], numerical results of aerodyn/yawdyn by duque et al. [27] and bem results by ceyhan et al. [28]. for computed power results, the mechanical power was corrected to generator power using equation (3). the cfd results are found to be in good agreement with those obtained using the bem method and measured one, for the tested undisturbed wind speed, rangi to 12.83 m.s -1 for generally attached flow conditions. figure.12. variation of experimental (nrel phase ii) and computational power output as function of wind speed figure 12 shows a comparison of the measured and computed power for various wind speeds and tip speed ratio. it is interesting to note that the cfd computations performed with fluent have a similar trend with measured one and the other numerical results. in general, the numerical results for wind speed of 7.2 to 12.85 m.s are in good agreement with those obtained using the bem method and those measured. in fact, at 10.56 m.s the calculated power value is less than that measured by 1.80%, and gradually as the wind speed increases the error of the calculated power increases. at 12.85, 16.3 and 19.18 m.s -1 the calculated power is lower than that measured by 5.22, 20.36 and 28.19% respectively. the results show differences at higher wind speeds as expected, considering the inability of the rans model to accurately predict the aerodynamic loads in deep stall conditions. riyadh belamadi et al. 7 derived power against the generator power, it was found that the efficiency did not match the published efficiency. as a result, a better curve fit between mechanical and generator power was − 0.847 (3) the computed power as a function of the wind speed is shown in figure 12 against the experimental iea data [22], numerical results of aerodyn/yawdyn by duque et al. [27] and bem results by ceyhan et al. [28]. for the computed power results, the mechanical power was corrected to generator power using equation (3). the cfd results are found to be in good agreement with those obtained using the bem method and measured one, for the tested undisturbed wind speed, ranging from 7.2 for generally attached flow conditions. variation of experimental (nrel phase ii) and computational power output as function of wind speed. figure 12 shows a comparison of the measured and various wind speeds and tip speed ratio. it is interesting to note that the cfd computations performed with fluent have a similar trend with measured one and the other numerical results. in general, the numerical results for wind speed of 7.2 to 12.85 m.s -1 are in good agreement with those obtained using the bem method and those measured. in fact, at 10.56 m.s -1 the calculated power value is less than that measured by 1.80%, and gradually as the wind speed increases the es. at 12.85, 16.3 the calculated power is lower than that measured by 5.22, 20.36 and 28.19% respectively. the results show differences at higher wind speeds as expected, considering the inability of the rans model to e aerodynamic loads in deep stall figure 13 shows a comparison of measured and calculated power coefficients for different wind speeds values and tip speed ratio respectively. it is interesting to note that the numerical solution has a similar measures and with other numerical results. note that the maximum value of the calculated power coefficient is only about 0.15, achieved at the speed of 10.56 m.s tip speed ratio 3.59. the value is well below the betz limit (59.3%) and the maximum of modern wind turbines recently commercialized of approximately 45% [29]. at high wind speeds, the flow separation plays a major role in reducing the overall aerodynamic efficiency. (a) (b) figure.13. (a)variation of experimental (nrel computational coefficient as function of wind speed. (b) experimental (nrel phase ii) and computational coefficient function of tip speed ration. page 37 figure 13 shows a comparison of measured and calculated power coefficients for different wind speeds values and tip speed ratio respectively. it is interesting to note that the numerical solution has a similar trend with measures and with other numerical results. note that the maximum value of the calculated power coefficient is only about 0.15, achieved at the speed of 10.56 m.s -1 and tip speed ratio 3.59. the value is well below the betz maximum of modern wind turbines recently commercialized of approximately 45% [29]. at high wind speeds, the flow separation plays a major role in reducing the overall aerodynamic efficiency. variation of experimental (nrel phase ii) and as function of wind speed. (b) variation of experimental (nrel phase ii) and computational coefficient as ijeca-issn: 2543-3717. june 2017 iii.4. determination of the effective angle of attack the effects of rotation could be studied and identified, by comparing the 3-d calculations of the rotating blade with the corresponding 2-d situations. nevertheless, the flow conditions in both cases must be carefully chosen, i.e. in a consistent manner. it is well known that the flow properties have similarities if the reynolds number is kept the same [3], but in the wing sections theory the angle of attack is of equal importance. the angle of attack is a 2-d concept. it is defined as the geometric angle between the direction of the rela chord of theairfoil. therefore, finding an equivalent angle of attack for the local 3-d flow is not trivial. for a rotary blade, further complication arises from the 3 effects at the root and the tip of the blade. inverse blade element momentum method the inverse bem method, motivated by some previous work [10, 30, 31], using normal and tangential forces predetermined on the blade, fn and ft obtained from experiments or cfd calculations to calculate the local induction factor, as well as effective local angles of attack and lift and drag forces for each section of the blade (figure 14). the inverse algorithm bem based on the calculated pressure distributions (3 done previously) is summarized below: ��,� = ∮ �⃗. �⃗��� and ��,� = ∮ �⃗. �⃗��� 1initialization of the axial and tangential factors, typically: � = � = 0� compute the effective inflow angle as fallow: �� = ��� �� � (����)�� (���́�)�� 2compute the new values of axial and tangential factors: ����,� = � ���������� ����,� �� and �́���,� = � ��������� ����� ����,� � riyadh belamadi et al. 7 determination of the effective angle of attack studied and identified, d calculations of the rotating blade d situations. nevertheless, the flow conditions in both cases must be carefully chosen, i.e. in a consistent manner. it is well known that the flow operties have similarities if the reynolds number is kept the same [3], but in the wing sections theory the angle of attack is of equal importance. the angle of d concept. it is defined as the geometric angle between the direction of the relative flow and the chord of theairfoil. therefore, finding an equivalent d flow is not trivial. for a rotary blade, further complication arises from the 3-d effects at the root and the tip of the blade. momentum method the inverse bem method, motivated by some previous work [10, 30, 31], using normal and tangential forces predetermined on the blade, fn and ft obtained from experiments or cfd calculations to calculate the as effective local angles of attack and lift and drag forces for each section of the blade (figure 14). the inverse algorithm bem based on the calculated pressure distributions (3-d calculations (4) (5) initialization of the axial and tangential factors, (6) compute the effective inflow angle as fallow: ) � )�� � (7) compute the new values of axial and tangential (8) �� (9) 3if the difference between the new values of[a, á]and [a���, á���] tolerance, go to step 2. else, continue. 4compute c�, c� and the effective angle of attack as : ��,� = ��,� ��� ��,� = ��,� ��� and where θ� is the pitch angle. figure 14.cross-sectional airfoil element in this part, the inverse bem method was used to determine the angle of attack of nrel phase ii rotor. the navier were made previously for wind speeds of 4, 5, 6, 7.2, 8, 12.85, 16.3 and 19.18 m.s -1 software. a comparison was made between the results obtained using the method m experimental test data that has been achieved in the wind tunnel of colorado state university (csu) [32] and ohio state university (osu) [33], and the experimental data from nrel phase ii [32]. lift and drag coefficient for differen r/r = 0.3, 0.47, 0.63, 0.80 are shown in figures 15 and 16. we can see that the values of drag coefficient show good agreement with those of the experience for all sections of the blade, especially for the sections r/r = 0.63, 0.8. however, the values of the lift coefficient are in reasonable agreement for small values of aoa and begin to deviate from the experimental data when the angle of attack increases. page 38 rence between the new values ]is more than certain tolerance, go to step 2. else, continue. and the effective angle of attack ��� �� + ��,� ��� �� (10) ��� �� − ��,� ��� �� (11) ��=�� − �� (12) sectional airfoil element. in this part, the inverse bem method was used to determine the angle of attack of the 3-d flow over the nrel phase ii rotor. the navier-stokes calculations were made previously for wind speeds of 4, 5, 6, 7.2, 8, 1 with ansys fluent software. a comparison was made between the results obtained using the method mentioned above and the experimental test data that has been achieved in the wind tunnel of colorado state university (csu) [32] and ohio state university (osu) [33], and the experimental data lift and drag coefficient for different radial positions r/r = 0.3, 0.47, 0.63, 0.80 are shown in figures 15 and 16. we can see that the values of drag coefficient show good agreement with those of the experience for all sections of the blade, especially for the sections r/r = er, the values of the lift coefficient are in reasonable agreement for small values of aoa and begin to deviate from the experimental data when the riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 39 figure 15. a comparison between lift coefficient as predicted by the inverse bem method and cfd data at r/r: 0.3, 0.47, 0.63 and 0.8. the 2-d data is taken from wind tunnel experimental results at re=0.65 x 106 [32], and re = 1 x 106 [33] and the experimental data from nrel [32]. figure 16. a comparison between drag coefficient as predicted by the inverse bem method and cfd data at r/r: 0.3, 0.47, 0.63 and 0.8. the 2-d data is taken from wind tunnel experimental results at re=0.65 x 106 [32], and re = 1 x 106 [33] and the experimental data from nrel [32]. riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 40 at r/r = 0.30, we see that there is a considerable deviation of the lift coefficient with respect to 2-d experimental data, that disagreement due to the 3-d effect present in the boundary layer of a rotating blade . at the same section (30%), by comparing with experimental data from nrel we observed that they have almost the same trend. while the general trend is similar for all sections of the scale, large deviation exists between the 2-d and 3-d case. the determination of the effective angle of attack experimentally or numerically is a difficult task and it needs to be done to better determine the angles of attack of the 3-d flow with a rotary blade. iv. conclusion the aim of the current works is the numerical study of hawt rotor nrel phase ii; the validation of the computed results with experimental data has been done. the results were restricting to pressure and pressure distribution on the blade, generated torque and a general overview of the flow field around the rotor. firstly, the numerical pressure distribution is presented and compared with experimental results at 30, 47, 63 and 80% spanwise locations for wind speed 7.2, 12.9 and 19.18 m.s -1 . when the flow is completely attached and no separation occurs, the computed pressure distribution at all sections of the blade is in good agreement with the experimental data except up to 30% span. the differences increase with wind speed especially on the suction side of the blade as stronger vortices form close to the root which explains these discrepancies. secondly, the computed torque has a better agreement with strain gages measurement than with the generator measurement at wind speed 7.2 m.s -1 , while at 10.56 m.s 1 the trend is reversed. the cfd values of the power coefficient are found to be in good agreement with those obtained using the bem method and measured ones for the tested undisturbed wind speed. the maximum computed value of the power coefficient is only about 0.15, achieved at wind speed of 10.56 m.s -1 and tip speed ratio 3.59. the power values show considerable differences at higher wind speeds and for predicting the maximum value. for deep stall conditions, the inability of the rans model to predict aerodynamic loads is well documented. then, the invers method bem was used to determine the angle of attack of the 3-d flow over the nrel phase ii rotor. the general trend of lift and drag coefficients are similar for all sections particularly in the outer part of the blade. however the determination of the effective angle of attack is still a difficult task and it needs to be improved to predict the 3-d flow of a rotating blade. finally, the study confirms that rans simulations are capable of solving with a fair accuracy the different aspects involved in hawt flow field, thus this confirms that nowadays cfd simulations can be the most important tool for analysis and design of wind turbine rotors. riyadh belamadi et al. ijeca-issn: 2543-3717. june 2017 page 41 references [1] sorensen j.n. and shen w.z. numerical modeling of wind turbine wakes. journal of fluid engineering, 2002, 124, pp. 393–9. [2] e. hau, wind turbines. springer: berlin, 2000. [3] carlo enrico carcangiu. cfd-rans study of horizontal axis wind turbine.thesis for the degree of doctor of philosophy, gagliari.2008. [4] f.j. simoes and j.m.r. graham, a free vortex model of the wake of a horizontal axis wind turbine, 12th british wind energy association conference, 1990, pp. 161-165. [5] l. terrinonii, p. signoretti, d. iatauro, c. romeo, a. federici. performance calculation for a vertical axis wind turbine with variable blade pitch, international journal of heat and technology, 2010, 28(2), pp. 147-153 [6] natalinomandas.numerical prediction of horizontal wind turbine flow. european wind energy conference and exhibition 2006 [7] a. le pape, j. lecanu. 3d navier-stokes computations of a stall-regulated wind turbine. ewea delft (pays-bas), 19-21 avril 2004. [8] gupta, a, prediction of aerodynamic forces on wind turbine blades using computational fluid dynamics, master thesis, applied science in industrial systems engineering, university of regina, 2007. [9] monier ali elfarra, horizontal axis wind turbine rotor blade: winglet & twist aerodynamic design & optimization using cfd, phd thesis, in aerospace engineering, medal east technical university, 2011. [10] h snel. r. houwink, j. bosschers, w.j. piers, g.j.w. van bussel and a .bruining, sectional prediction of 3d effects for stalled flow on rotating blades and comparison with measurements, in proceedings of ewec 93:lübecktravemunde, 1993, pp. 395–9. [11] h. himmelskamp, profile investigation on a rotating airscrew, these doctorat, göttingen university: phd dissertation, 1945. [12] g. ronsten, static pressure measurements on a rotating and non-rotating 2.375m wind turbine bladecomparison with 2d calculations, journal of wind engineering and industrial aerodynamics, 1992, 39(1–3), pp. 105–18. [13] j.l. tangler and j.d kocurek, wind turbine post-stall airfoil performance characteristics guidelines for bladeelement momentum methods , in proc.of 43rd aiaa aerospace sciences meeting and exhibit, 2005, volume 591, pp. 1–10. [14] w.r. sears, potential flow around a rotating cylindrical blade, journal aeronautical sciences: readers’ forum, 1950, 17(3):183. [15] l.e. fogarty and w.r. sears, potential flow around a rotating, advancing cylinder blade, journal aeronautical sciences: readers forum, 1950, 17(9):599. [16] l.e. fogarty, the laminar boundary layer on a rotating blade, journal aeronautical sciences: readers’ forum, 1951, 18(4):247 [17] banks w.h.h. and gadd g.e. delaying effects of rotation on laminar separation, american institute of aeronautics and astronautics journal, 1963, 1(4):941–2. [18] w.j. mccroskey and h.a. dwyer, methods of analyzing propeller and rotor boundary layers with cross flows, technical report sp–228, nasa, 1969. pp. 473–514. [19] j.n sorensen, prediction of the three-dimensional stall on wind turbineblade using three-level, viscous-inviscid interaction model, in proceedings of ewec 86: rome, 1986, pp. 429–35. [20] z. du and m.s. selig the effect of rotation on the boundary layer of a wind turbine blade, renewable energy, 2000, 20, pp. 167–81. [21] hu d. hua o. and du z. a. study on stall-delay for horizontal axis wind turbine, renewable energy, 2006, 31, pp.821–36. [22] j.g. schepers, a.j. brand, a. bruining, j.m.r. graham, m.m. hand, d.g. infield, h.a. madsen, r.j.h. paynter and d.a. simms, final report of iea annex xiv: field rotor aerodynamics, ecnc97-027, energy research center of the netherlands, 1997. [23] d. simms, s. schreck, m. hand and l. fingersh, nrel unsteady aerodynamics experiment in the nasa-ames wind tunnel: a comparison of predictions to measurements, national renewable energy laboratory, nrel/tp-500-29494, 2001. [24] ansys inc, ansys fluent theory guide, november 2010. [25] riyadh belamadi, abdelouheb djemili, adrian ilinca, ramzi mdouki., aerodynamic performance analysis of slotted airfoils for application to wind turbine blades, journal of wind engineering and industrial aerodynamics, 2016, 151,2016, pp. 79–99. [26] chalothorn thumthae, tawit chitsomboon, optimal angle of attack for untwisted blade wind turbine’ renewable energy, 2009, 34, pp. 1279-1284. [27] earl p.n. duque .numerical predictions of wind turbine power and aerodynamic loads for the nrel phase ii combined experiment rotor, american institute of aeronautics and astronautics journal, 2000-0038. [28] ozlem ceyhan. aerodynamic design and optimization of horizontal axis wind turbines by using bem theory and genetic algorithm, master thesis of graduate school of natural and applied sciences of middle east technical university, 2008. [29] jang-oh mo and young-ho lee, cfd investigation on the aerodynamic characteristics of a small-sized wind turbine of nrel phase vi operating with a stallregulated method, journal of mechanical science and technology, 2012, 26-1, pp. 81-92. [30] c lindenburg, investigation into rotor blade aerodynamics: analysis of the stationary measurements on the uae phase-vi rotor in the nasa-ames wind tunnel tech, rep. ecn-c–03-025 ecn, the netherlands, 2003. [31] s guntur, c bak, n sorensen, analysis of 3d stall models for wind turbine blades using data from the mexico experiment, the 13th international conference on wind engineering, amsterdam, the netherlands, 2011. [32] c.p. butterfield, w.p. musial, g.n. scott, d.a. simms, nrel combined experimental final report-phase ii, nrel/tp-442-4807, 1992. [33] r.r ramsey, m.j hoffman, g.m gregorek, effects of grit roughness and pitch oscillations on the s809 airfoil, nrel tp-442-7817, december 1995. i. introduction ii. numerical procedure iii. results iv. conclusion references [1] sorensen j.n. and shen w.z. numerical modeling of wind turbine wakes. journal of fluid engineering, 2002, 124, pp. 393–9. [2] e. hau, wind turbines. springer: berlin, 2000. [3] carlo enrico carcangiu. cfd-rans study of horizontal axis wind turbine.thesis for the degree of doctor of philosophy, gagliari.2008. [4] f.j. simoes and j.m.r. graham, a free vortex model of the wake of a horizontal axis wind turbine, 12th british wind energy association conference, 1990, pp. 161-165. [5] l. terrinonii, p. signoretti, d. iatauro, c. romeo, a. federici. performance calculation for a vertical axis wind turbine with variable blade pitch, international journal of heat and technology, 2010, 28(2), pp. 147-153 [6] natalinomandas.numerical prediction of horizontal wind turbine flow. european wind energy conference and exhibition 2006 [7] a. le pape, j. lecanu. 3d navier-stokes computations of a stall-regulated wind turbine. ewea delft (pays-bas), 19-21 avril 2004. [8] gupta, a, prediction of aerodynamic forces on wind turbine blades using computational fluid dynamics, master thesis, applied science in industrial systems engineering, university of regina, 2007. [9] monier ali elfarra, horizontal axis wind turbine rotor blade: winglet & twist aerodynamic design & optimization using cfd, phd thesis, in aerospace engineering, medal east technical university, 2011. [10] h snel. r. houwink, j. bosschers, w.j. piers, g.j.w. van bussel and a .bruining, sectional prediction of 3d effects for stalled flow on rotating blades and comparison with measurements, in proceedings of ewec 93:lübeck-travemunde, 1993, pp. 395–9. [11] h. himmelskamp, profile investigation on a rotating airscrew, these doctorat, göttingen university: phd dissertation, 1945. [12] g. ronsten, static pressure measurements on a rotating and non-rotating 2.375m wind turbine bladecomparison with 2d calculations, journal of wind engineering and industrial aerodynamics, 1992, 39(1–3), pp. 105–18. [13] j.l. tangler and j.d kocurek, wind turbine post-stall airfoil performance characteristics guidelines for blade-element momentum methods , in proc.of 43rd aiaa aerospace sciences meeting and exhibit, 2005, volume 591, pp. 1–10. [14] w.r. sears, potential flow around a rotating cylindrical blade, journal aeronautical sciences: readers’ forum, 1950, 17(3):183. [15] l.e. fogarty and w.r. sears, potential flow around a rotating, advancing cylinder blade, journal aeronautical sciences: readers forum, 1950, 17(9):599. [16] l.e. fogarty, the laminar boundary layer on a rotating blade, journal aeronautical sciences: readers’ forum, 1951, 18(4):247 [17] banks w.h.h. and gadd g.e. delaying effects of rotation on laminar separation, american institute of aeronautics and astronautics journal, 1963, 1(4):941–2. [18] w.j. mccroskey and h.a. dwyer, methods of analyzing propeller and rotor boundary layers with cross flows, technical report sp–228, nasa, 1969. pp. 473–514. [19] j.n sorensen, prediction of the three-dimensional stall on wind turbineblade using three-level, viscous-inviscid interaction model, in proceedings of ewec 86: rome, 1986, pp. 429–35. [20] z. du and m.s. selig the effect of rotation on the boundary layer of a wind turbine blade, renewable energy, 2000, 20, pp. 167–81. [21] hu d. hua o. and du z. a. study on stall-delay for horizontal axis wind turbine, renewable energy, 2006, 31, pp.821–36. [22] j.g. schepers, a.j. brand, a. bruining, j.m.r. graham, m.m. hand, d.g. infield, h.a. madsen, r.j.h. paynter and d.a. simms, final report of iea annex xiv: field rotor aerodynamics, ecnc97-027, energy research center of the netherlands, 1997. [23] d. simms, s. schreck, m. hand and l. fingersh, nrel unsteady aerodynamics experiment in the nasa-ames wind tunnel: a comparison of predictions to measurements, national renewable energy laboratory, nrel/tp-500-29494, 2001. [24] ansys inc, ansys fluent theory guide, november 2010. [25] riyadh belamadi, abdelouheb djemili, adrian ilinca, ramzi mdouki., aerodynamic performance analysis of slotted airfoils for application to wind turbine blades, journal of wind engineering and industrial aerodynamics, 2016, 151,2016, pp. 79–99. [26] chalothorn thumthae, tawit chitsomboon, optimal angle of attack for untwisted blade wind turbine’ renewable energy, 2009, 34, pp. 1279-1284. [27] earl p.n. duque .numerical predictions of wind turbine power and aerodynamic loads for the nrel phase ii combined experiment rotor, american institute of aeronautics and astronautics journal, 2000-0038. [28] ozlem ceyhan. aerodynamic design and optimization of horizontal axis wind turbines by using bem theory and genetic algorithm, master thesis of graduate school of natural and applied sciences of middle east technical university, 2008. [29] jang-oh mo and young-ho lee, cfd investigation on the aerodynamic characteristics of a small-sized wind turbine of nrel phase vi operating with a stall-regulated method, journal of mechanical science and technology, 2012, 26-1, pp. 81-92. [30] c lindenburg, investigation into rotor blade aerodynamics: analysis of the stationary measurements on the uae phase-vi rotor in the nasa-ames wind tunnel tech, rep. ecn-c–03-025 ecn, the netherlands, 2003. [31] s guntur, c bak, n sorensen, analysis of 3d stall models for wind turbine blades using data from the mexico experiment, the 13th international conference on wind engineering, amsterdam, the netherlands, 2011. [32] c.p. butterfield, w.p. musial, g.n. scott, d.a. simms, nrel combined experimental final report-phase ii, nrel/tp-442-4807, 1992. [33] r.r ramsey, m.j hoffman, g.m gregorek, effects of grit roughness and pitch oscillations on the s809 airfoil, nrel tp-442-7817, december 1995. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 3. issue 2. 2018 page 13-21 ijeca-issn: 2543-3717. december 2018 page 13 optimal planning of on-grid hybrid microgrid for remote island using homer software, kish in iran saeedeh ebrahimi 1 , mehdi jahangiri 2,* , heidar ali raiesi 3 , afrooz rahimi ariae 1 1 department of architecture, sepehr institute of higher educational, isfahan, iran. 2 department of mechanical engineering, shahrekord branch, islamic azad university, shahrekord, iran. 3 department of electrical engineering, shahrekord branch, islamic azad university, shahrekord, iran. jahangiri.m@iaushk.ac.ir abstract – homer software functions as a tool for modeling and optimization of an energy generation micropower system based on renewable technologies. in this paper for the first time the monthly real load data have been used in homer to design a renewable-based microgrid in grid-connected mode for kish island, iran. the calculations were performed in a way that the designed system could supply the load demand of the studied area with the lowest cost, least pollution, and highest reliability. to overcome the intermittency of renewable energy sources such as wind and solar, a combination of these sources in a hybrid system and installation of battery storage systems were considered. the solar radiation and wind speed data required by the software were obtained from the country’s meteorology and nasa website and used in the software. the analysis results of four scenarios, including national grid/diesel generator, national grid/diesel generator/solar cell, national grid/diesel generator/wind turbine, and national grid/diesel generator/solar cell/wind turbine, showed the prices per kwh of $0.483, $0.505, $0.472, $0.537, respectively. in these scenarios, the share of renewable energies was 0%, 8%, 11%, and 26%, respectively. the highest amount of electricity sold to the national grid was 1597095 kwh/y for the fourth scenario which had also the lowest rate of co2 emissions by 4128650 kg/y. keywords:microgrid; hybrid system; homer software, total npc, coe. received: 27/08/2018 – accepted: 19/10/2018 i. introduction renewable energy sources are clean and unlimited, therefore they can be good substitutions for fossil fuels. the reduction in fossil fuels, higher ghgs, and higher energy consumption have led to increased use of renewable energy sources in grid-connected mode. other factors contributing to higher application of renewable energies include the availability of various kinds of these sources, low production costs in the long run, low maintenance costs, and their safety. integration of these sources to provide for local loads has resulted in a concept named microgrid. one of the most important issues about microgrids is their optimal operation. according to a 2016 report, 19.2% of world energy consumption and 23.7% of power production have been supplied by renewable energies. of these, 8.9% has been provided by traditional biomass, 4.2% from thermal energy (modern biomass, solar heating, and geothermal), 3.9% from hydroelectricity, and 2.2% electricity from wind, solar, geothermal, and biomass energies [1]. conserving sources by developing renewable and clean energies in iran until september 2018 was shown in figure 1 [2]. figure 1. conserving sources by developing renewable energies in iran [2] mailto:jahangiri.m@iaushk.ac.ir saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 14 many researchers have investigated the optimal planning and economic viability of a hybrid gridconnected microgrid from various standpoints some of which are reviewed in the following. lipu et al. (2017) used homer to conduct a design optimization and sensitivity analysis on hybrid renewable energy systems in saint martin village, bangladesh [3]. their studied system consisted of solar cells, wind turbine, diesel generator, battery, and converter. they studied 6 various scenarios for supplying 299 kwh/d. the results indicated that wind turbine/solar cell/generator scenario, which costed $359729, had the lowest price per kwh of energy equivalent to $0.27. peerapong et al. (2017) attempted to optimize electrification development in a diesel generator-based microgrid in an island, thailand [4]. they used homer for analyses and wanted to observe how increased use of solar panels would affect the microgrid. the analyses results suggested that in case of using solar cells as well as diesel generator, the price per kwh of electricity would reduce from $0.429 to $0.374. also, that would lead to around 797 tons of co2 saving annually which is due to 30251 l reduction in diesel consumption, for solar cells could provide for 41% of demand. soukeyna et al. (2018) used homer to perform a feasibility study on producing power from hybrid renewable systems for northern coasts of mauritania [5]. the sensitivity analysis was performed on five different prices of diesel and wind speed. results showed that by increasing the diesel price, the price per kwh of energy would raise. furthermore, higher wind speeds led to lower prices per kwh of energy. it is noteworthy that for wind speed more than 7 m/s, the price of energy produced would be independent of diesel price so that for 7 and 8 m/s wind speeds the price per kwh of energy generated would be $ 0.089 and $0.086, respectively. sadati et al. (2018) studied a hybrid wind turbine/solar cell/battery system for an island in mediterranean area using homer [6]. their aim was to calculate and optimize the net present cost, the price per kwh of energy, and total energy generated. two various scenarios were studied with and without batteries. results indicated that in both scenarios, the price per kwh of energy was $0.15 which was lower than that of produced by the national grid ($0.175). hantoro et al (2018) analyzed the energy demand and design of hybrid system in bawean island, indonesia, by using homer [7]. the results of sensitivity analysis showed that for supplying the maximum load of 131 kw, the optimal system included solar cells (150 kw), two wind turbines (10 kw each), diesel generator (75 kw) and battery. in the optimal state, around 48% of energy was produced by solar cell, 2% by wind turbine, and the rest by diesel generator. moreover, about 76600 kwh of surplus energy would be produced annually. regarding the prioritizing of different locations to harness renewable energies, rezaei-shouroki et al. [8] used data envelopment analysis (dea), analytical hierarchy process (ahp) and fuzzy technique for order of preference by similarity (ftopsis) and examined six essential criteria influencing on location optimization in order to select the most promising place in terms of providing wind energy for hydrogen production purpose. also, rezaei et al. [9] investigated seven different cities for establishment of a hybrid wind-solar site using five main factors including climate, geographical conditions, economy, natural disasters and social conditions. in another research, ten cities of the most suitable province of iran, kerman, in terms of exploiting solar energy were analyzed for the purpose of establishing a solar/hydrogen energy conversion system [10]. in another research, a hybrid model composed of dea, balanced scorecard (bsc) and game theory was proposed to rank several photovoltaic sites based on four criteria including the net cost of construction, earnings, the amount of power generated, and pollution produced per plant [11]. in terms of using solar energy for practical and applicable aims, such as water desalination and heating water, mostafaeipour et al. [12] proposed photovoltaic systems to desalinate seawater using solar energy in coastal districts of bushehr province in iran, after assessing techno-economic feasibility, the results showed that these systems are technically viable as well as economically. several factors influencing on utilizing solar water heating systems in dry arid areas of iran were investigated, the results indicated that environmental issues have direct effect on the use of solar water heater in the region under study [13]. one of the most important analyses before embarking on any construction is techno-economic assessment; in this regard qolipour et al. [14] utilized homer and matlab software to propose a mathematical model for optimizing the renewable electricity price and construction of new wind power plants, simultaneously. in terms of clean hydrogen production, a wind-powered system was proposed to generate hydrogen after desalinating seawater in coastal areas of iran [15]. alavi et al. [16] analyzed the amount of wind energy available in five cities situated in the south eastern of iran and examined wind turbines with different power rates to utilize them for generating hydrogen. in another research, qolipour et al. [17] assessed constructing a hybrid solarwind plant technically as well as analyzing economically in order to generate electricity and hydrogen using homer software to compare different alternatives. in iran, power is generally produced from fossil fuels. given the fact that this study investigates the power supply of kish island, the storage limitations of fossil fuels and their resultant pollution should be taken into account. these issues as well as the fact that, in the near future, the higher fuel prices and numerous problems caused by fuel transport will hinder further development of the island, show the necessity of using alternative and renewable sources of energy. the main renewable energy saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 15 sources in kish island are wind and solar. based on the above issues, this study is the first one to investigate the power supply of the whole island using homer software. the studied parameters are total npc, coe and the amount of pollutants produced. ii. the studied area as it is obvious in figure 2, kish island is a resort island in the persian gulf off the southern coast of iran. it is part of the bandar-e lengeh county in hormozgan province. it has a nearly elliptical shape and it is located 12 km off shibkooh coast. the island has an outer boundary of 44 km, having a length of around 15.45 and a width of 7.5 km it covers an area of 90 km 2 . the most elevated area is around 35 m above the sea. it lacks permanent rivers but enjoys many sources of underground fresh water. the air travel distance is 1052 km from kish to tehran, 250 km to bandar abbas, 90 km to bandar-e lengeh, and 28 km to hendourabi island. furthermore, the nearest island to kish is aftab island which is 13 km away. figure 2. the location of kish on iran’s map [18] kish has a hot and humid climate. the median temperature is usually 27˚c and it rarely exceeds the maximum value of 32˚c. the minimum temperature never goes lower than 3˚c which occurs on a few days of winter. according to 2011 census of population and housing, kish has a population of 24819 people which are mostly located in kish county. the economy of kish is under development; the main development goals include tourism and business development. according to the statistics, more than 1700000 tourists visit kish island every year. it has also many markets and shopping centers which constitute part the county’s economy. kish is not connected to the national grid and there is only one power-plant active in kish. traditionally, upon the technical problems in the power-plant or during peak hours in summers, many power blackouts occurred. therefore, a second power-plant was planned to be constructed in the southwest of the island which realized in 2016. in addition to gas-powered plants in kish, there is also a diesel-powered plant with 10 mw capacity which is used for emergency [19]. iii. software presentation homer functions as tool for evaluating and designing an optimal micropower in two off-grid and grid-connected modes to achieve the goals of desired applied programmers. when designing a power generation system, many decisions have to be made about its configuration: which components, such as panel, wind turbine, diesel generator, etc. will be required for building a power system? how many components are needed and what is the required size for each? the numerous number of related technologies, their cost variability, and the availability of energy sources render decision making difficult. the optimization algorithms and sensitivity analysis of homer make easier the evaluation of many feasible systems [20]. homer shows simulation results in various tables and charts which helps in comparing different configurations based on their technical and economical rankings and enables tables and graphs to be drawn out in reports and presentations. when one intends to evaluate the effect of changes in variables such as resource availability and economic conditions on the effectiveness and economic efficiency of various system configurations, they can utilize the sensitivity analysis capability of homer. the results of sensitivity analysis are used for determination and identification of factors with the highest effect on the system design and operation. also, homer utilizes sensitivity analysis results to answer general equations of technology options for planning and design making. homer simulates the operation of a system by making energy balance equations in each of the 8760 hours of the year (time step). for each time step, homer compares the electric and thermal demand in that time step to the energy that the system can supply in that time step, and calculates the flows of energy to and from each component of the system. for systems that include batteries or fuel-powered generators, homer also decides in each time step when is more costeffective to operate the generators and whether to charge or discharge the batteries. it then determines whether a configuration is feasible, i.e. whether it can meet the electric demand under the conditions that the user specifies, and estimates the cost of installing and operating the system over the lifetime of the project. the system cost calculations account for the costs such as capital, replacement, operation and maintenance, fuel, and interest [20]. iv. the required data iv.1. power consumption profile the most important data input to the homer is the amount of power required to be supplied by the system. saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 16 load profile for various months of the year was shown in figure 3. figure 3. load profile for various months of the year it is clear from figure 3 that there is a need for more electricity in the warm months of the year, from may to october, which requires cooling installations. the maximum and minimum required electric load is required in august and february respectively. also, the minimum electricity required is happen at 6 to 12. iv.2. solar radiation monthly average solar radiation values used in homer are taken from nasa website [21]. to this end, the geographical latitude of 26˚32’ and longitude of 53˚58’ (geographical coordinate of kish island) were used. the monthly average solar radiation graph is shown in figure 4. figure 4. monthly average radiation. by inputting the monthly average radiation (kwh/m 2 day), the software will calculate the air clearness index by the following relation [22]: (1) k� = ���� ��.��� where have and ho‚ave are the solar radiation received at earth surface and top-of-atmosphere radiation, respectively. have was taken from nana website and according to the latitude of the studied area, the 0 6 12 18 24 500 1,000 1,500 mar 0 6 12 18 24 500 1,000 1,500 feb 0 6 12 18 24 500 1,000 1,500 jan 0 6 12 18 24 500 1,000 1,500 jun 0 6 12 18 24 500 1,000 1,500 may 0 6 12 18 24 500 1,000 1,500 apr 0 6 12 18 24 500 1,000 1,500 sep 0 6 12 18 24 500 1,000 1,500 aug 0 6 12 18 24 500 1,000 1,500 jul 0 6 12 18 24 500 1,000 1,500 dec 0 6 12 18 24 500 1,000 1,500 nov 0 6 12 18 24 500 1,000 1,500 oct 0.0 0.2 0.4 0.6 0.8 1.0 jan feb mar apr may jun jul aug sep oct nov dec 0 2 4 6 8 d a il y r a d ia ti o n ( k w h /m ²/ d ) global horizontal radiation c le a rn e s s i n d e x daily radiation clearness index saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 17 software will calculate ho‚ave by the following relation [22]: (2) ��.��� = ∑ �� п ��� ����� ���� ����� + п�� ���° ���� ���� ����� � where � is the longitude and n is the number of day in each month. other parameters are described in the help window of the software and will not be repeated here. homer considers only the rated capacity of a pv (kw) not its area (m 2 ). this software does not need to know the efficiency and assumes that the pv output is directly proportional to the amount of radiation [23,24]. defining a derating factor at the input of a pv in homer entails no cost. this factor is used to compensate for reduced efficiency due toenvironmental conditions which are less desirable compared to standard testing conditions. the default value for this factor is 80%. in warm weather, a slightly smaller value must be selected. the power generated by pv is calculated by the following relation [22]: (3) ��� = ������ � �̅ ��.����������� ��1 + ��(�� − ��.���)� the parameters in the above equation are described in the help window of the software and will not be repeated here. iv.3. wind speed kish island is one of iran's windy regions. wind speed is taken from wind statistics provided by wind atlas stations from renewable energy and energy efficiency organization (satba) which are measured separately for each 8760 hours of the year that adds to the accuracy and precision of results [25]. figures. 5 and 6 show the wind speed probability distribution function and average wind speed graphs for various months in kish island.as shown in fig. 5, the highest percentage of wind speed distribution is belong to 4.5 to 5.5 m/s. figure 6 also shows that the maximum monthly average wind speed is about 7 m/s and happened in march. the months of july and august with an average speed of 4 m/s are the weakest months for using wind turbines. figure 5. probability distribution function of wind speed in kish island. figure 6. average wind speed in kish island. homer uses the following relation to calculate the power output of wind turbines [22]: (4) ���� = � �ₒ ����،��� in this relation for calculating wind power (pwtg) in kw, pwtg.stp should be obtained based on the power curve of turbine for standard conditions. the power curve for the used wind turbine is shown in fig. 7.it is clear from figure 7 that the cut-in, rated and cut-out speed of the used wind turbine are 3, 13 and 21 m/s, respectively. figure 7. the power curve of the used wind turbine. iv.4. cost of equipment since diesel generator is used in the studied hybrid systems, the price input of 0.09 $/l [26] was used for diesel. also, to take account of the annual interest rate, 18% [27] was considered as the annual real interest rate with a useful lifetime of 25 years and zero pollution penalties. table 1 summarizes the prices, types, and sizes of equipment. since the studied system is connected to the national grid, the power purchasing price from the national grid was considered based on the consumption bills of 2017 in low-load, mid-load, and high-load modes to be 0.05, 0.07, and 0.12 $/kwh, respectively. according to satba tariffs, the power selling prices to the national grid were considered on average for low-load, midload, and high-load modes to be 0.318, 0.445, and 0.763 $/kwh, respectively [29]. low-load, mid-load, and high-load hours were 23:00-8:00, 8:00-16:00, and 16:00-23:00, respectively. 0 2 4 6 8 10 0 2 4 6 8 10 f re q u e n c y ( % ) scaled data pdf value (m /s) wind speed data best-fit weibull (k=4.41, c=5.70 m/s) jan feb mar apr may jun jul aug sep oct nov dec 0 1 2 3 4 5 6 7 w in d s p e e d ( m /s ) wind resource 0 5 10 15 20 25 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 p o w e r (k w ) wind speed (m/s) saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 18 table 1. the price of equipment, the type and size of equipment [28]. schematic other information size (kw) cost ($) equipment o & m replacement capital life time: 20 years derating factor: 80% 1 0 6900 6900 pv lifetime: 15 years efficiency: 90% 1 100 700 800 converter lifetime: 25 years hub height: 10 m 1 100 3900 3900 wind turbine bwc xl.1 life time: 15000 h 1 0.04 900 900 diesel generator nominal specs: 6v, 1156 ah 1 50 1100 1200 battery surrette 6cs25p v. results load supply of 21 mwh/d with a maximum value of 3.1 mw was studied in 4 scenarios. the first to fourth scenarios were to provide the power demand from the national grid, the national grid as well as solar cells, the national grid plus wind turbines, and the national grid in addition to solar cells and wind turbines. for all four scenarios, a diesel generator provided the emergency power demand. simulation results showed that for all four scenarios the cost per kwh of power generated is $0.483, $0.505, $0.472, and $0.537. the share of renewable energies is 0, 8, 11, and 26%, and total savings in co2 emitted by diesel-powered generator are 6701140, 5173898, 5395389, 4128650 kg, respectively. as it could be seen in fig. 8, in the first scenario 47% of electricity demand is supplied by diesel generator and 53% by the national grid. from fig. 8 it can be observed that in january, february, march, april, and december, the national grid alone can meet the demands and the diesel generator is most needed in august. in this scenario the diesel generator runs for 2364 h/y and 2000 batteries are also used. inverter and rectifier losses in this scenario are 185952 and 408573 kwh/y, respectively. from table 2, which presents the data about buying/selling power from/to the national grid, it can be seen that the higher amount of power is purchased in may and the highest amount is sold in october. in this scenario, 2000 kw generator, 2000 batteries, and 1000 kw converter have been used. figure. 8: monthly average electric production in the first scenario tab. 2: power exchange with the grid in the first scenario month energy purchased (kwh) energy sold (kwh) net purchases (kwh) jan 535,292 103,983 431,309 feb 482,669 91,508 391,161 mar 550,082 93,536 456,546 apr 510,227 101,942 408,285 may 548,196 91,127 457,069 jun 336,016 102,206 233,810 jul 316,947 99,213 217,733 aug 276,072 87,291 188,782 sep 276,698 89,096 187,602 oct 348,102 109,409 238,693 nov 524,033 102,880 421,153 dec 551,092 80,085 471,007 annual 5,255,426 1,152,276 4,103,150 in the second scenario, as it could be seen in fig. 9, 18% of power is generated by solar cell, 29% by diesel generator, and 53% by the national grid with the total power generation of 10457491 kwh/y. from fig. 9 it is clear that in all times of the year solar cells are used and the national grid is the least needed in april. in this scenario, solar cells produce electricity for 4381 hours of the year and generator runs for 1066 hours/y consuming 1012326 l of diesel. in the second scenario, the rectifier and inverter losses are 296062 and 306502 kwh/y, respectively. from table 3, which summarizes the data on buying/selling power from/to the national grid, it could be seen that in all months of the year, power has been purchased purely from the national grid. in this scenario, 1000 kw solar cells, 3000 kw generator, 3000 batteries, and 1000 kw converter have been utilized. figure. 9: monthly average electric production in the second scenario jan feb mar apr may jun jul aug sep oct nov dec 0 500 1,000 1,500 2,000 p o w e r (k w ) generator grid jan feb mar apr may jun jul aug sep oct nov dec 0 500 1,000 1,500 2,000 p o w e r (k w ) pv generator grid saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 19 tab. 3: power exchange with the grid in the second scenario month energy purchased (kwh) energy sold (kwh) net purchases (kwh) jan 438,971 136,733 302,238 feb 386,475 120,542 265,933 mar 433,159 126,243 306,916 apr 389,549 137,377 252,172 may 509,452 124,033 385,419 jun 500,749 119,942 380,807 jul 487,897 139,101 348,796 aug 437,220 161,787 275,433 sep 476,916 131,249 345,667 oct 508,068 136,304 371,764 nov 490,398 100,003 390,395 dec 449,965 106,977 342,987 annual 5,508,818 1,540,290 3,968,528 in the third scenario where the price per kwh of power generated is $0.472, 1000 kw wind turbine, 1000 kw generator, 1000 kw battery, and 1000 kw converter have been used. in this scenario, of the total 9818430 kwh of electricity produced during the year, 16% is supplied by wind turbine, 47% by diesel generator, and 37% by the national grid as is shown in fig. 10. the important point here is that wind turbines have worked for 8553 hours in the year. consuming 1534046 l of diesel, the generator has been run for 4650 hours in the year. the rectifier and inverter losses in this scenario are 90287 and 176427 kwh/y, respectively. from table 4, which shows the data on buying/purchasing power from/to the national grid, it can be seen that during a year, 3642711 kwh of electricity is bought from the national grid and 1497550 kwh of electricity is sold to the national grid. as in the second scenario, the electricity bought is higher than that sold during one year. in this scenario, in 5 months of the year (january, february, march, april, and december), the electricity sold to the national grid is higher than that bought with its peak in march. figure. 10: monthly average electric production in the third scenario tab. 4: power exchange with the grid in the third scenario month energy purchased (kwh) energy sold (kwh) net purchases (kwh) jan 140,128 206,947 -66,819 feb 84,725 255,376 -170,651 mar 78,688 310,927 -232,239 apr 85,382 245,100 -159,718 may 282,354 95,971 186,383 jun 452,516 22,674 429,842 jul 511,307 14,790 496,517 aug 569,019 6,578 562,442 sep 519,630 8,291 511,339 oct 495,745 20,833 474,912 nov 267,048 98,327 168,722 dec 156,168 211,737 -55,569 annual 3,642,711 1,497,550 2,145,162 in the fourth scenario which is associated with the lowest amount of pollution and the higher use of renewable energies, wind and solar combination has been used for supplying the electricity demand through a hybrid system connected to the national grid and diesel generator. in this scenario, 1000 kw solar cell, 1000 kw wind turbine, 2000 kw diesel generator, 2000 kw battery, and 1000 kw converter have been used for power generation. 19% of the electricity is generated by solar cells, 15% by wind turbines, 31% by diesel generator, and the rest by the national grid as is shown in fig. 11. from this figure it can also be seen that in all times of the year solar cells and wind turbines have been used and the highest use of diesel generator occurs in august. the running hours of solar cell, wind turbine, and diesel generator for the whole year are 4381, 8553, and 1609 hours, respectively. in this scenario, as in the second and third ones, batteries are used and therefore the rectifier losses are equal to 132046 kwh. also, annual inverter losses in this scenario are 370194 kwh/y which is the highest among four scenarios. due to more power generation from renewable energies in this scenario, it has the highest annual rate of selling electricity to the national grid by 1597095 kwh (table 5). figure. 11: monthly average electric production in the fourth scenario tab. 5: power exchange with the grid in the fourth scenario month energy purchased (kwh) energy sold (kwh) net purchases (kwh) jan 271,284 138,233 133,052 feb 180,622 124,174 56,447 mar 149,039 144,696 4,343 apr 155,062 148,227 6,836 may 421,780 113,852 307,928 jun 396,863 125,524 271,338 jul 366,348 151,579 214,769 aug 294,294 164,486 129,808 sep 343,348 120,883 222,464 oct 436,998 134,254 302,744 nov 404,091 120,162 283,928 dec 331,319 111,022 220,297 annual 3,751,048 1,597,095 2,153,953 jan feb mar apr may jun jul aug sep oct nov dec 0 400 800 1,200 1,600 p o w e r (k w ) wind generator grid jan feb m ar apr may jun jul aug sep oct nov dec 0 500 1,000 1,500 2,000 p o w e r (k w ) pv wind generator grid saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 20 vi. conclusion in order to reduce greenhouse gas emissions and encouraging higher use of renewable energies in iran and consistent with the previous research by the authors [30-46], this paper is the first one to investigate the real data of electricity consumption in an island for 12 months of the year using homer in four various scenarios to analyze hybrid wind-solar systems in gridconnected mode. results indicated that: economically, the national grid/diesel generator is the most cost-effective system having price per kwh of electricity of $0.483. the highest use of renewable energies by 26% is related to the national grid/diesel generator/solar cell/wind turbine scenario which also produces the least co2 emissions by 4128650 kg/y. in none of the scenarios the annual net electricity sold to the national grid is higher than that bought from the national grid. the most amount of electricity sold to the national grid occurs in the national grid/diesel generator/solar cell/wind turbine system by selling 1597095 kwh of electricity annually. the solar cell-based scenario is more costly than wind turbine-based but it produces less pollution. due to low price of diesel in iran compared with national grid and renewable-based electricity, diesel generator is used in all scenarios necessarily. references [1] renewables 2017 global status report, renewable energy policy network for the 21st century,http://www.ren21.net/status-of-renewables /global-status-report. [2] renewable energy and energy efficiency organization, conserving sources by developing renewable and clean energies, http://www.satba.gov.ir/suna_content/media/image/2018 /09/6251_orig.jpg [3] m.s.h. lipu, m.g. hafiz, m.s. ullah, a hossain, f.y munia,. design optimization and sensitivity analysis of hybrid renewable energy systems: a case of saint martin island in bangladesh. international journal of renewable energy research (ijrer), 2017, 7(2), pp.988-998. [4] p peerapong, b.limmeechokchai, optimal electricity development by increasing solar resources in dieselbased micro grid of island society in thailand. energy reports, 2017. 3, pp.1-13. [5] m. soukeyna, i.b. ramdhane, d. ndiaye, m. elmamy, m.m menou, a.m yahya, a.k mahmoud, i. youm, feasibility analysis of hybrid electricity generation system by homer for mauritanian northern coast. international journal of physical sciences, 13(8), 2018. pp.120-131. [6] s.s sadati, e. jahani, o. taylan, d.k. baker, sizing of photovoltaic-wind-battery hybrid system for a mediterranean island community based on estimated and measured meteorological data. journal of solar energy engineering, 140(1), 2018. p.011006. [7] hantoro, r., budiono, c., ketter, r.k. and satwika, n.a., 2018. energy demand analysis and design of a hybrid power system in bawean islands, indonesia. in matec web of conferences (vol. 164, p. 01038). edp sciences. [8] rezaei-shouroki, m., mostafaeipour, a., qolipour, m., 2017. prioritizing of wind farm locations for hydrogen production: a case study. international journal of hydrogen energy, 42, pp. 9500-9510. [9] rezaei, m., mostafaeipour, a., qolipour, m., tavakkolimoghaddam, r., 2018. investigation of the optimal location design of a hybrid wind-solar plant: a case study. international journal of hydrogen energy, 43, pp. 100-114. [10] mostafaeipour, a., sedaghat, a., qolipour, m., rezaei, m., arabnia, h.r., saidi-mehrabad, m., shamshirband, s., alavi, o., 2017. location of solar-hydrogen power plants in the province of kerman, iran. advances in energy research, 5(2), pp. 179-205. [11] mostafaeipour, a., qolipour, m., mohammadi, k., 2016. evaluation of installing photovoltaic plants using a hybrid approach for khuzestan province, iran. renewable and sustainable energy reviews, 60, pp. 6067. [12] mostafaeipour, a., qolipour, m., rezaei, m., babaeetirkolaee, e., 2018. investigation of off-grid photovoltaic systems for a reverse osmosis desalination system: a case study. desalination, corrected proof. [13] mostafaeipour, a., zarezade, m., goudarzi, h., rezaeishouroki, m., qolipour, m., investigating the factors on using the solar water heaters for dry arid regions: a case study. renewable and sustainable energy reviews, 78, 2017. pp. 157-166. [14] qolipour, m., mostafaeipour, a., rezaei, m.,. a mathematical model for simultaneous optimization of renewable electricity price and construction of new wind power plants (case study: kermanshah). international journal of energy and environmental engineering, 9(1), 2017, pp. 71-80. [15] rezaei, m., mostafaeipour, a., qolipour, m., arabnia, h.r., hydrogen production using wind energy from sea water: a case study on southern and northern coasts of iran. energy & environment, 29(3), 2018. pp. 333-357. [16] alavi, o., mostafaeipour, a., qolipour, m., analysis of hydrogen production from wind energy in the southeast of iran. international journal of hydrogen energy, 41(34), 2016. pp. 15158-15171. [17] qolipour, m., mostafaeipour, a., mohseni tousi, o., techno-economic feasibility of a photovoltaic-wind power plant construction for electric and hydrogen production: a case study. renewable and sustainable energy reviews, 78, 2017. pp. 113-123. [18] google earth, www.googleearh.com, available: 22.07.2016. [19] the kish business hub, www.kishtpc.com, available: 22.07.2016. [20] energy information, http://www.energyinformation.ir, available: 22.07.2016. [21] nasa prediction of worldwide energy resources, https://power.larc.nasa.gov, available: 22.07.2016. [22] lambert, t., gilman, p., lilienthal, p., micropower system modeling with homer. integration of alternative sources of energy, 2005. pp. 379-418. saeedeh ebrahimi et al ijeca-issn: 2543-3717. december 2018 page 21 [23] demiroren, a., yilmaz, u., analysis of change in electric energy cost with using renewable energy sources in gökceada, turkey: an island example. renewable and sustainable energy reviews, 14(1), 2010. pp.323333. [24] jafarian, m. dg planning by homer software, ms thesis, sharif university of technology, tehran. 2007 [25] renewable energy and energy efficiency organization, http://www.satba.gov.ir/fa/regions/hormozgan, available: 22.07.2016. [26] https://www.globalpetrolprices.com/gasoline_prices, available: 22.07.2016. [27] https://tradingeconomics.com/country-list/interestrate?continent=asia, available: 06.06.2018. [28] vahdatpour, s., behzadfar, s., siampour, l., veisi, e., jahangiri, m., evaluation of off-grid hybrid renewable systems in the four climate regions of iran. journal of renewable energy and environment, 4(1), 2018. p.61. [29] http://www.satba.gov.ir/fa/guidance/investmentguidefor smallpowerplants, available: 22.07.2018. [30] nematollahi, o., alamdari, p., jahangiri, m., assessing the wind energy potential locations in province of ardabil for generate electricity. 1st regional conference on electrical engineering-rcee, ramhormoz, iran. 2011. [31] jahangiri m., abdollahi a., sedaghat a., saghafian m., assessing the wind energy potential locations in province of qazvin in iran. proceedings of the 1st international conference on emerging trends in energy conservation-etec, tehran, iran. 2011. [32] jahangiri m., abdollahi a., malayeri a.h., sedaghat, a., feasibility of installing wind turbines in qazvin province case study: jarandagh station. 4th national conference of mechanical engineering-ncme2011, islamic azad university, khomeinishahr branch, iran. november 2011 [33] jahangiri m., abdollahi a., sedaghat a., saghafian m., statistical analysis of wind energy in markazi province case study: saveh station. proceedings of the 1st international conference on emerging trends in energy conservation-etec, tehran, iran. 2011. [34] hajagah onour, k., jahangiri, m., sedaghat, a., theoretical aerodynamic analysis of six airfoils for use on small wind turbines. proceedings of the 1st international conference on emerging trends in energy conservation-etec, tehran, iran. 2011. [35] hajagah onour, k., jahangiri, m., sedaghat, a., 2011. feasibility of installing wind turbine to generate electricity power in iran, case study: the khuzestan province. proceedings of the 1st international conference on emerging trends in energy conservation-etec, tehran, iran. [36] alamdari, p., nematollahi, o., jahangiri, m., hajji malayeri, a., 2012. feasibility study of wind energy potential in alborz province for generate electricity, a case study: eshtehard. 1st specialty conference of the wind and sun, tehran, iran. [37] jahangiri, m., hajji malayeri, a., sedaghat, a., aghaei, e., investigating wind potential for clean energy production in khorasan razavi province, case study: jangal station. 1st specialty conference of the wind and sun, tehran, iran. 2012. [38] jahangiri, m., hajji malayeri, a., aghaei, e., statistical analysis of wind data for installation of wind turbine to generate electricity power in the khuzestan province, case study: abadan station. 1st specialty conference of the wind and sun, tehran, iran. 2012. [39] alamdari, p., jahangiri, m., nematollahi, o., hajji malayeri, a.,. assessing the wind energy potential locations in province of east azerbaijan for generate electricity. 1st specialty conference of the wind and sun, tehran, iran. 2012 [40] alamdari, p., nematollahi, o., jahangiri, m., feasibility study of wind energy for generate electricity in province of sistan and baluchistan, case study: nosrat abad. the 3rd international scientific conference of iranian students in belarus, minsk, belarus. 2012. [41] jahangiri, m., nematollahi, o., sedaghat, a. and saghafian, m., techno-economical assessment of renewable energies integrated with fuel cell for off grid electrification: a case study for developing countries. journal of renewable and sustainable energy, 7(2), 2015. p.023123. [42] riahi zaniani, j., heydarian dehkordi, r., bibak, a., bayat, p., jahangiri, m., examining the possibility of using solar energy to provide warm water using retscreen4 software (case study: nasr primary school of pirbalut). special issue of current world environment; 10 (special issue may 2015). [43] alidadi shamsabadi, a., jahangiri, m., koohi faeghm a., raeisi dehkordi, a., biogas production in a dairy cow unit to provide a sustainable solution for reducing the environmental pollutions and pathogens. the 11th international energy conference (iec 2016), iran, tehran. 2016. [44] jahangiri, m., khosravi, a., raiesi, h.a. and mostafaeipour, a., analysis of standalone pv-based hybrid systems for power generation in rural area. in international conference on fundamental research in electrical engineering, tehran. 2017. [45] jahangiri, m. and shamsabadi, a.a., designing a horizontal-axis wind turbine for south khorasan province: a case study. international journal of precision engineering and manufacturing, 18(10), 2017. pp.1463-1473. [46] jahangiri, m., rizi, r.a. and shamsabadi, a.a., feasibility study on simultaneous generation ofelectricity and heat using renewable energies in zarrin shahr, iran. sustainable cities and society, 38, 2018. pp.647-661. i. introduction ii. the studied area iii. software presentation iv. the required data iv.1. power consumption profile iv.2. solar radiation iv.3. wind speed iv.4. cost of equipment v. results vi. conclusion references international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 01-10 ijeca-issn: 2543-3717. june 2019 page 1 selection of parameters to predict dew point temperature in arid lands using grey theory: a case study of iran mojtaba qolipour 1 , ali mostafaeipour 1 , mostafa rezaei 1* , elham behnam 1 , hossein goudarzi 2 , ali razmjou 3 1industrial engineering department, yazd university, yazd, iran. 2school of architecture and planning, university of new mexico, nm, usa 3escolla técnica superior d’enginyeria industrial de barcelona, universitat politècnica de catalunya, barcelona, catalunya, spain email * : mm.sr6870@yahoo.com abstractdew point is the temperature at which water vapor in the air condenses into liquid with the same rate it evaporates. dew point study is important in arid lands with low rainfall, also in other regions with various hydrological and climatological conditions. in this study, the grey theory is applied for the first time to propose a framework approach to identify the important parameters affecting the prediction of dew point temperature. the ability of grey theory to estimate and rank the parameters of a problem with missing data and uncertain conditions means that it has a good potential for mentioned application. for this research, 8 parameters are selected using literature review including: global solar radiation on a horizontal surface (h), water vapor pressure (vp), atmospheric pressure (p), sunshine duration (n), minimum air temperature (tmin), maximum air temperature (tmax), average air temperature (tavg), and relative humidity (rh). the study is conducted for the city of abadeh in iran by using the data pertaining to a 10 year period between 2005 and 2015. the findings show that rh, tavg, p, tmax, tmin, h, n and vp with the grey possibility degrees of, respectively, 0.534, 0.551, 0.608, 0.622, 0.635, 0.695, 0.697 and 0.712, are the most important and effective parameters in prediction of dew point temperature. the proposed method also prioritizes the studied parameters in the order of their effectiveness on predicted dew point temperature. keywords:dew point temperature; grey theory; daily dew point temperature; fuzzy; abadeh city. received: 01/01/2019 – accepted: 27/02/2019 nomenclature dpt dew point temperature g fuzzy number ann artificial neural network )(x g  fuzzy membership function anfis adaptive neuro fuzzy inference system )( gl  length of grey number ],[ gg svr support vector regression id i-th grey's dimension svm support vector machine parameters elm extreme learning machine h horizontal global solar radiation mlp multi-layer perceptron n sunshine hour rbnn radial basis neural networks vp water vapor pressure grnn generalized regression neural networks p atmospheric pressure canfis coactive neuro fuzzy inference system tmin minimum air temperatures abder image placée mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 2 mlr multiple linear regression tmax maximum air temperatures gep gene expression programming tavg average air temperatures greece letters rh relative humidity w grey's attribute weight td daily dew pointtemperature r grey's attribute range t temperature xi the i-th value of variable ''x'' xmin the minimum value of variable ''x'' xo normalized value of variable ''x'' xmax the maximum value of variable ''x'' i. introduction dew point is the temperature at which water vapor in the air (at constant barometric pressure) condenses into liquid with the same rate it evaporates. when air temperature goes below the dew point temperature, some portion of the water vapor in the air condenses until reaching a new equilibrium. the water vapor condenses on a solid surface is called dew [1, 2]. in fact, dew point temperature (td) is the temperature below which the air can no longer hold its water vapor. in this process, pressure (p) and mixing ratio (r) of moist air remain constant [3, 4]. when air pressure is constant and no water vapor gets added or removed from the air, the mixing ratio of air remains constant. at the dew point temperature, water content of the air is at saturation point; therefore throughout the process the mixing ratio remains equal to its value at the point of saturation (at dew point temperature). in other words, at this temperature, the relative humidity is always 100% [5]. the presence of a relatively cool layer of air near the ground at night can push the temperature down to dew point. a basic method of measuring dew point is to acquire a container with a fully smooth outer wall, fill it with a mixture of water and ice, and then measure the temperate of water at the moment when water droplets (dews) gradually appear on the outer wall [6]. as regards the high importance of dew, many researches have been done into it. several are summarized in the following. meng and wen [7] investigated the amount, frequency, and also duration of dew events in two croplands, arid and sub-humid, in order to quantify the characteristics of dew events and analyze the underlying mechanism of dew formation in different ecosystems. their finding show that dew events play a more important role in crop growth in arid areas in comparison to sub-humid areas considering the dew occurrence frequency and the amount per night. in another research, zhuang and zhao [8] scrutinized the effects of dew events on non-mucilaginous seed germination of annual desert plant species during dry seasons. finally the results showed that the presence of dew significantly increased seed germination percentages and decreased the nonviable seed percentages. wang et al. [9] studied dew formation, amount, and duration of rain-fed jujube trees in a semiarid loess hilly region of china. in this regard they used dew intensity and duration, relative humidity, temperature, and wind speed. the results indicated that atmospheric conditions of relative humidity of >78% and dew point temperature of 1°c–3°c are significantly favorable to dew formation. pan and wang [10] performed measurement of accumulated dew formation amount and duration in order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats. the results showed that the accumulated dew formation amount was four times larger at open spaces as compared to under the canopy, and it was nearly twice as much under living artemisia ordosica plants as compared to under living caragana korshinskii plants. these mentioned studies show that dew is of significant importance and needs more investigation into its different aspects, as a result, it is attempted to predict dew point temperature in this study. the accurate and reliable data for dew point is very important in agronomical and climatological related research works. usually, dew point is used with relative humidity for identifying of the moisture level in the air. dew point can also be used for providing the estimation of the humidity for near-surface of plants that influences the stomatal closure. dew point study is important in arid lands with low rainfall, also in other regions with various hydrological and climatological conditions [11]. the majority of studies on dew point temperature prediction and evaluating the factors affecting this process have used a variety of artificial neural networks or in other words the soft computing methods. some researchers have employed the soft computing techniques to evaluate and determine the most important parameters affecting the dew point prediction for a variety of case studies. the following researches were also found in the literature. amirmojahedi et al. [11] utilized a hybrid computational intelligence method for predicting dew. mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 3 they used a hybrid approach including the extreme learning machine (elm) with wavelet transform (wt) algorithm for prediction of daily dew point temperature for city of bandar abbas in iran. in a study by baghban et al. [2], the dew point of atmospheric moist air was estimated by lssvm and anfis methods. the model developed in this study was tested with 100 data instances, and the mse and rsquare (r 2 ) of results were found to be 0.000016, 1.0000 for lssvm model and 0.382402, 0.9987 for anfis model respectively. in a study by sarkar [12], a new theoretical formulation for dew point temperatures was developed with the use of modified clausius–clapeyron equation. the developed formulation was aimed for comfort aircooling systems. this study reported that the error of proposed method is far less than that of standard psychrometric measures. these authors also used the dpt equation to plot the wet sensible and latent loads of a cooling dehumidifying coil based on discretized temperature and humidity. evaluation and determination of the most important and most effective parameter in prediction of dew point temperature with due consideration given to availability and reliability of data is of utmost importance. the majority of research conducted to determine the most effective parameter in dew point temperature prediction has neglected an issue, and that is the uncertainty in the accuracy of data pertaining to parameters and the number of samples available for each parameter. although most studies have used an acceptable number of samples, the accuracy of the data used in earlier researches and the effect of human and instrument error in data recorded and collected by meteorological offices have been overlooked. therefore, when evaluating and determining the most effective parameter in dew point temperature prediction, it is crucial to use a method that can deal with inaccuracy and the possibility of errors in data and provide a satisfactory output with the lowest possible error. in this regard, grey theory, which can use consecutive formulation, standardize the data, and take the environmental uncertainty for each parameter into account (through fuzzy calculation), can be employed to prioritize the parameters and determine the most important and effective ones. this paper seeks to use the grey theory to cover the mentioned gap in the research on this subject and provide a decision making framework for ranking and determination of the most important parameters in dew point temperature prediction. the rest of paper is structured as follows: in section 2, geographic characteristics are presented. the methodology is brought in section 3. in section 4, analysis of the research is done. finally, conclusion remarks are drawn in section 5. ii. area of study iran as a developing country is located in western asia with a population of about 81 million people and an area of approximately 1,648,195 km 2 [13-15]. the country has different types of climates including mild and wet, mediterranean, cold, cold semi-desert, dry and hot dry [16,17], which fars province lays in areas with semi-arid, cold and mediterranean climates [18]. abadehis capital of abadeh county in fars provinceof iran that is located in 31°09′39"n52°39′02"e[18]. as of 2014, the population was estimated to be 94042 [19]. it features a continental semi-arid climate with extreme heat and dryness over summer, and cold (extreme at times) and wet winter, with huge variations between daytime and nighttime throughout the year [20]. figure 1 illustrates map of iran including location of abadeh. figure 1.map of iran including abadeh area. iii. methodology in this research, a new methodology by using grey theory for selection of parameters to predict dew point temperature is proposed. in this section, the description of the proposed theorem is presented. grey theory was introduced in 1982 by deng. this theory is a modern mathematical theory developed from the concept of grey set [21]. its general procedure includes obtaining a set of initial data and repetitively processing them to weaken the effect of random information on these data with the intention of establishing a robust order (rule) in the data arrangement. the theory consists of five main parts: grey prediction, grey relational analysis, grey decision, grey programming and grey control [22, 23]. based on the degree of https://en.wikipedia.org/wiki/fars_province https://en.wikipedia.org/wiki/iran https://tools.wmflabs.org/geohack/geohack.php?pagename=abadeh_county&params=31_15_n_52_30_e_type:city_region:ir ijeca-issn: 2543-3717. june 2019 information, the grey theory calls the system “white” when its information is fully known, calls it “black” when its information is fully unknown, and calls it “grey” when it information is partly known.this fuzzy approach is a very effective method for solving problems involved with uncertainty, discrete data and incomplete information [24]. other reasons behind the widespread use of this method include its simple calculati small size of its required sample, lack of need for distribution of the initial sample, its ability to deal with discrete data, and the fact that qualitative output obtained from grey relational grade cannot be seen in the results of quantitative analyses [25]. application of grey theory is classified into 5 categories of evaluation, modeling, predicting, decision-making and control [ in an empirical formula provided by the researchers, dew point is a function of temperature and relative humidity [27]: )1121.0()9.0112( 125.0  trhttd researchers have introduced the following eight parameters for predicting the dew point temperature and evaluating the factors affecting the prediction of dew point: global solar radiation on a horizontal surface (h), water vapor pressure (vp), atmospheric pressure (p), sunshine duration (n), minimum air temperature (t maximum air temperature (tmax), average air temperature (tavg), relative humidity (rh) [12, 28 these eight parameters are used to achieve the research objective. grey set is defined as a set of uncertain data that can be described by a series of grey numbers, grey equations, grey matrices, etc. the grey set g is defined by reference set x with )(xg and g lower bounds of the membership function [ where  , and when these two variables are equal grey set turn into a fuzzy set. this means that grey set is a fuzzy set that is flexible in dealing with different problems. figure 2 shows a representation of grey system procedures. ]1,0[:)( ]1,0[:)(   xx xx g g   mojtaba qolipour et al information, the grey theory calls the system “white” when its information is fully known, calls it “black” when its information is fully unknown, and calls it it information is partly known.this fuzzy approach is a very effective method for solving problems involved with uncertainty, discrete data and incomplete ]. other reasons behind the widespread use of this method include its simple calculations, the small size of its required sample, lack of need for distribution of the initial sample, its ability to deal with discrete data, and the fact that qualitative output obtained from grey relational grade cannot be seen in the results ]. application of grey theory is classified into 5 categories of evaluation, modeling, making and control [26]. in an empirical formula provided by the researchers, dew point is a function of temperature and relative (1) researchers have introduced the following eight parameters for predicting the dew point temperature and evaluating the factors affecting the prediction of dew horizontal surface (h), water vapor pressure (vp), atmospheric pressure (p), sunshine duration (n), minimum air temperature (tmin), ), average air temperature 28]. in this study, parameters are used to achieve the research grey set is defined as a set of uncertain data that can be described by a series of grey numbers, grey equations, grey matrices, etc. the grey set g is defined )(x g as upper and lower bounds of the membership function [29]: (2) )()( xx gg   , and when these two variables are equal grey set turns into a fuzzy set. this means that grey set is a fuzzy set that is flexible in dealing with different problems. figure 2 shows a representation of grey system procedures. figure 2.grey system [ assuming each fuzzy number as the fuzzy relationships between two grey numbers ],[ 111 g and [2  g follows [31]: ],[ 212121   gg ,[ 12121   gg )],,,max( ,,[min(* 21212121 212121   gg ] 1 , 1 [*],[ 22 1121   gg ],[],[*. 11111  kkkgk  length of grey number ],[ gg gggl  )( in a grey set, an option can be chosen over another only when we can establish that those two options are actually comparable and one can be considered more preferable. in deterministic sets, this fact can be established one through simple judgment, but in fuzzy sets this can be done via multi objective decision making techniques [ in the following, the instruments of grey evaluation of dew point temperature parameters are described. 5 evaluated dimensions are represented by  521 ,...,, ddddi  . the scale of attribute ratings (shown in table 1) are used to assess the qualitative judgments of respondents for each criterion and, the scale of attribute weights (shown in table 2) a evaluate the weight of parameters [ amounts of table 1, we first normalized abadeh's meteorology data (including the parameters) using following formula and then multiply them in 10 to changed abadeh's meteorology data in g have: minmax min 0 xx xx x i      xxi page 4 grey system [30] assuming each fuzzy number as ],[  g , the fuzzy relationships between two grey numbers ], 22  can be defined as (3) ]2 (4) ),, 2121  (5) (6) ] (7) ] is defined as: (8) in a grey set, an option can be chosen over another only when we can establish that those two options are actually comparable and one can be considered more preferable. in deterministic sets, this fact can be established one through simple judgment, but in fuzzy sets this can be done via multi-parameters or multiobjective decision making techniques [32]. in the following, the instruments of grey evaluation of dew point temperature parameters are described. here, 5 evaluated dimensions are represented by . the scale of attribute ratings (shown in table 1) are used to assess the qualitative judgments of respondents for each criterion and, the scale of attribute weights (shown in table 2) are used to evaluate the weight of parameters [31]. for calculate the amounts of table 1, we first normalized abadeh's meteorology data (including the parameters) using following formula and then multiply them in 10 to changed abadeh's meteorology data in grey data. so we 100 x (9) mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 5 table 1 illustrates the scale of attribute ratings, and table 2 shows the scale of attribute weights. table 1. the scale of attribute ratings scale attribute ratings ( r ) very poor(vp) [0, 1] poor(p) [1, 4] moderate(m) [4, 6] good(h) [6, 9] very good (vg) [9, 10] table 2. the scale of attribute weights scale attribute weights ( w ) very low(vl) [0.0, 0.1] low(l) [0.1, 0.4] medium(m) [0.4, 0.6] high(h) [0.6, 0.9] very high(vh) [0.9, 1.0] equation 10 is used to assess the opinions of received data [29]: ]...[ 1 ],[ 21 t ijijij t ij t ij t ij ggg t ggg  (10) in the above equation, t ijg isvalue for the t-th data for i-thobservation with respect to j-th parameter, and can be represented by the grey number ],[ tij t ij t ij ggg  . the value of j-th parameter can be calculated via equation 11 [33]: 3,2,1; 7 7 1   j g g t tj j (11) after calculating the weights of parameters, options need to be evaluated. this evaluation is conducted via equation 12. the obtained grey values t ijg is then used to form grey decision matrix d:              mnm n gg gg d    1 111 (12) the evaluation numbers are all positive, so the decision matrix can be normalized. equation 13 shown below is used to obtain normalized matrix *d [31]. ),( maxmax * j ij j ij ij gg g   (14) s.t }1;{maxmax mig ijj   (13)              ** ** * 1 111 mnm n gg gg d    multiplying the normalized decision matrix by the obtained weight matrix gives the normalized weighted decision matrix: ijijij wgn  *               mnm n n nn nn d    1 111 (15) hypothetical and important parameter of dew point temperature in case study, which is denoted by maxb , is calculated via the following equation [32]: ]}max,[max],...,max,{[max },...,,{ 111111 maxmax 2 max 1 max inmiinmiimiimi ngggb    (16) the concept of preference degree is used to compare two grey numbers with each other. preference degree of grey number 1g with respect to grey number 2g is calculated via equation 17 [34]: )()( ),0max(),0max( )( 121 2121 21 gggg gggg ggp     (17)and when 1g equals 2g , equation 18 holds true: )( 21 ggp   = 5.0)( 12  ggp   )( 21 ggp   + 1)( 12  ggp  (18) this means that sum of the preference degrees of two grey numbers always equal with 1. the grey possibility degree between each decision parameter (dew point temperature) and the important parameter is then calculated via equation 19. parameters with a lower grey possibility are more suitable [29]:   n j jiji gnp n bbp 1 maxmax }{ 1 )( (19) next section will describe the research findings. iv. case study and data collection first, the data concerning the eight study parameter was collected from the meteorology office of abadeh. this data pertained to a 10-year period from 2005 to 2015. figure 3 shows the average monthly minimum temperature, maximum temperature and mean temperature of the study area during the period of 2005 to 2015. according to figure 3, during this period, the maximum temperature of abadeh has been 35°c s and its minimum temperature has been -5°c. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 01-10 ijeca-issn: 2543-3717. june 2019 page 6 figure 3.monthly average of tmax, tmin and tavg for case study over a period of 10 years from 2005to2015 figure 4 illustrates the graph of average monthly precipitation and monthly mean temperature of abadeh during the period of 2005 to 2015. according to figure 4, during this period, the minimum precipitation has been zero and maximum precipitation has been 16 mm. figure 4. monthly average of temperature and precipitation for case study over a period of 10 years from 2005to2015 figure 5 displays the graph of minimum humidity, maximum humidity, and monthly mean humidity of abade during the period of 2005 to 2015 (the va figure 5. monthly average of rhmax, rhmin and rhavg for case study over a period of 10 years from 2005to2015 -5 0 5 10 15 20 25 30 35 40 t o c t max t avg. t min 0 10 20 30 40 50 60 0 5 10 15 20 25 30 p re c ip it a ti o n m m t o c temprature percipitation 0 10 20 30 40 50 60 70 80 90 h u m id it y % rh min rh max rh avg. ijeca-issn: 2543-3717. june 2019 figure 6 presents the graph of monthly mean hours of sunshine and monthly means water vapor in study area (in millimeter). according to figure 6, in the period between 2005 and 2015, the maximum monthly mean water vapor has been 390 mm in july, and the minimum figure 6. monthly average of n and v v. analysis equations 10 and 11 were used to calculate the attribute weight of each parameter for the given data. table 3 illustrates attribute weights of dew point's parameters as follows: table 3. attribute weights of dew point's parameters parameters attribute weights h [0.00,0.08] n [0.08,0.14] vp [0.14,0.18] p [0.18,0.24] tmin [0.24,0.30] tmax [0.30,0.32] tavg [0.32,0.36] rh [0.36,0.40] attribute weights of each parameter were evaluated via equation 12 to assess the priority and selection dew point temperature's parameters. grey decision table of the obtained data is illustrated in table 4: table 4. grey decision table d1 d2 d3 d4 h [0.5, 1.5] [2.4, 5.0] [3.4, 6.6] [7.5, 8.5] n [0.4, 2.5] [2.3, 4.0] [4.0, 7.8] [3.0, 6.2] vp [0.5, 1.9] [2.5, 3.6] [4.2, 5.7] [5.5, 8.0] 0 100 200 300 400 500 w a te r v a p o r m m , h o u rs mojtaba qolipour et al re 6 presents the graph of monthly mean hours of sunshine and monthly means water vapor in study area (in millimeter). according to figure 6, in the period between 2005 and 2015, the maximum monthly mean water vapor has been 390 mm in july, and the minimum monthly mean water vapor has been 5 mm in january and february. meanwhile, the maximum monthly mean hours of sunshine has been 340 hours in june, and the minimum monthly mean hours of sunshine has been 200 hours in december monthly average of n and vp for case study over a period of 10 years from 2005to2015 equations 10 and 11 were used to calculate the attribute weight of each parameter for the given data. table 3 illustrates attribute weights of dew point's attribute weights of dew point's parameters ights attribute weights of each parameter were evaluated via equation 12 to assess the priority and selection dew point temperature's parameters. grey decision table of the grey decision table 4 d5 [7.5, 8.5] [6.5, 9.0] [3.0, 6.2] [7.5, 9.8] [5.5, 8.0] [8.5, 9.5] p [0.8, 2.7] [2.0, 3.2] [3.3, 5.1] tmin [0.1, 3.5] [0.9, 2.7] [3.0, 4.4] tmax [0.6, 2.3] [1.8, 2.5] [3.7, 6.3] tavg [0.2, 2.8] [1.5, 4.4] [2.9, 6.1] rh [0.3, 3.1] [0.6, 2.3] [3.5, 5.6] using equation 13, the matrix of table 4 is normalized which is shown in table 5: table 5. normalized grey decision table d1 d2 d3 h [0.2238, 0.8339] [0.1386, 0.7694] [0.3501, 0.4879] n [0.2588, 0.7513] [0.1493, 0.3499] [0.1966, 0.4090] vp [0.2551, 0.8622] [0.0349, 0.2577] [0.2511, 0.4172] p [0.3188, 0.5060] [0.1407, 0.7254] [0.3160, 0.6715] tmin [0.3077, 0.6991] [0.0631, 0.2543] [0.2075, 0.4733] tmax [0.4336, 0.8909] [0.2050, 0.7147] [0.3517, 0.7172] tavg [0.3426, 0.5993] [0.2435, 0.8143] [0.6302, 0.8308] rh [0.1093, 0.6591] [0.1241, 0.9293] [0.4889, 0.5853] finally, the normalized decision weighted matrix of table 6 was obtained by multiplying the normalized matrix by the weight matrix. vp n page 7 monthly mean water vapor has been 5 mm in january and february. meanwhile, the maximum monthly mean hours of sunshine has been 340 hours in june, and the minimum monthly mean hours of sunshine has been 200 over a period of 10 years from 2005to2015 [3.3, 5.1] [5.9, 7.2] [7.7, 9.0] [3.0, 4.4] [5.3, 8.2] [7.0, 9.4] [3.7, 6.3] [6.2, 7.4] [8.5, 10.0] [2.9, 6.1] [5.4, 8.0] [8.2, 9.9] [3.5, 5.6] [4.5, 7.0] [7.3, 9.7] using equation 13, the matrix of table 4 is normalized normalized grey decision table d4 d5 [0.3501, 0.4879] [0.0347, 0.5497] [0.0540, 0.8095] [0.1966, 0.4090] [0.3034, 0.9172] [0.5308, 0.9443] [0.2511, 0.4172] [0.2858, 0.7269] [0.4384, 0.7792] [0.3160, 0.6715] [0.2934. 0.7528] [0.3256, 0.9340] [0.2075, 0.4733] [0.2174, 0.6832] [0.1299, 0.7549] [0.3517, 0.7172] [0.3804, 0.8884] [0.3705, 0.5688] [0.6302, 0.8308] [0.1471, 0.5678] [0.4694, 0.7115] [0.4889, 0.5853] [0.0689, 0.7590] [0.0119, 0.8637] finally, the normalized decision weighted matrix of 6 was obtained by multiplying the normalized mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 8 table 6. standard grey weighted decision matrix d1 d2 d3 d4 d5 h [0.0000, 0.1649] [0.0532, 0.1558] [0.1209, 0.1749] [0.1256, 0.2106] [0.1063, 0.2328] n [0.0192, 0.1277] [0.1381, 0.1812] [0.1470, 0.2173] [0.1818, 0.2802] [0.2012, 0.3509] vp [0.0301, 0.1326] [0.0154, 0.1961] [0.1963, 0.2687] [0.1811, 0.2638] [0.1111, 0.2085] p [0.0135, 0.1742] [0.0872, 0.1427] [0.1844, 0.2414] [0.1455, 0.2294] [0.1259, 0.2502] tmin [0.0112, 0.1655] [0.0430, 0.1491] [0.1890, 0.2868] [0.1316, 0.2707] [0.1948, 0.2759] tmax [0.0632, 0.1943] [0.1067, 0.1535] [0.2835, 0.3685] [0.1693, 0.2620] [0.2305, 0.3176] tavg [0.0630, 0.1133] [0.1690, 0.2614] [0.2998, 0.3001] [0.2350, 0.2893] [0.1832, 0.3234] rh [0.0524, 0.1022] [0.0046, 0.1477] [0.2599, 0.3314] [0.2468, 0.3797] [0.1707, 0.3722] equation 16 was then used to calculate the value of important parameter: maxb = ([0.00, 0.1934], [0.0046, 0.2614], [0.1209, 0.3685], [0.1256, 0.3797], [0.1111, 0.3722]) equation 19 was then used to compare the values of weighted decision matrix with the ideal values. table 7 shows the grey possibility degrees of parameters of dew point temperature in abadeh with respect to important parameters. table 7. grey possibility degree possibility degree p{h ≤ bmax} 0.695 p{vp ≤ bmax} 0.712 p{p ≤ bmax} 0.608 p{n ≤ bmax} 0.697 p{tmin ≤ b max} 0.635 p{tmax ≤ b max} 0.622 p{tavg ≤ b max} 0.551 p{rh ≤ b max} 0.534 options with lower grey possibility degrees with respect to ideal option are more suitable [27]. according to the results of table 7, among the assessed parameter's grey possible, parameters including: rh, tavg, p, tmax, tmin, h, n and vp these parameters were determined –in that orderas the most effective parameters in dew point temperature prediction. rh and tavg were determined as the most important parameters in dew point temperature prediction, and p was obtained as the third most important factor in this process. given that at a fixed p, formula (1) holds true, these findings seem reasonable and acceptable. therefore, the proposed method can properly evaluate the importance of parameters in dew point temperature prediction and prioritization of the parameters in the order of their effective and general importance. the findings of this study were found to be consistent comparing with previous studies. options with lower grey possibility degrees with respect to ideal option are more suitable [27]. according to the results of table 7, among the assessed parameter's grey possible, parameters including: rh, tavg, p, tmax, tmin, h, n and vp are important and effective respectively. then, in spite of rh and tavg, it received that p (air pressure) has noticeable effect on dew point temperature. to sum up, the grey approach would be efficient for precise predictions of daily dew point temperature and also higher accuracy. also, the findings are compatible to pervious research. vi. conclusions the aim of this paper was to use grey theory to evaluate and determine the most important parameters in prediction of dew point temperature for the city of abadeh located in southern iran. the used method is able to properly assess the problem and its dimensions in presence of any number of data, and has been used extensively by many researchers for different applications. in this study, 8 parameters affecting the dew point temperature including vp, n, h, p, tmin, tmax, tavg and rh were obtained from literature and then the data pertaining to these parameters was gathered from meteorological organization of the study area. then, the proposed method was used to devise the table of parameter weights, grey decision table, normalized grey decision table, standardized weighted decision matrix and the grey possibility degree of each parameter. the results showed that rh, tavg, p, tmax, tmin, h, n and vp with the grey possibility degrees of, respectively, 0.534, 0.551, 0.608, 0.622, 0.635, 0.695, 0.697 and 0.712, were the most important and effective parameters in predicting the dew point temperature. the results obtained through the use of proposed method were also found to be consistent with the results of previous works, except that parameter p was found to be the third most important parameter, after rh and tavg, in the prediction of dew point temperature. references [1] y.c.wang, g.h. tang. prediction of sulfuric acid dew point temperature on heat transfer fin surface. applied thermal engineering. vol. 98, 2016, pp 492–501. mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 9 [2] a. baghban, m. bahadori, j. rozyn, m. lee, a. abbas, a. bahadori, a. rahimali. estimation of air dew point temperature using computational intelligence schemes. applied thermal engineering. vol 93, 2016, pp 1043– 1052. [3] t. zhang, y. jiang. development of temperature and humidity independent control (thic) air-conditioning systems in china a review. renewable and sustainable energy reviews. vol. 29, 2014, pp 793–803. [4] d.b. jani, p.k. manish mishra. solid desiccant air conditioning – a state of the art review. renewable and sustainable energy reviews. vol 60, 2016, pp 1451–1469. [5] c. forman, i. kolawole, r. muritala, p. bernd meyer. estimating the global waste heat potential. renewable and sustainable energy reviews. vol 57, 2016, pp 1568–1579. [6] d. pandelidis, s. anisimov. numerical analysis of the heat and mass transfer processes in selected m-cycle heat exchangers for the dew point evaporative cooling. energy conversion and management. vol 90, 2015, pp 62–83. [7] y. meng, x. wen. characteristics of dew events in an arid artificial oasis cropland and a sub-humid cropland in china. journal of arid land. vol 8, no. 3, 2016, pp 399-408. [8] y. zhuang, w. zhao. the ecological role of dew in assisting seed germination of the annual desert plant species in a desert environment, northwestern china. journal of arid land. vol. 8, no. 2, 2016, pp 264-271. [9] x. wang, z. gao, y. wang, z. wang, s. jin. dew measurement and estimation of rain-fed jujube (zizyphus jujube mill) in a semi-arid loess hilly region of china. journal of arid land. vol. 9, no. 4, 2017, pp 547-557. [10] y. pan, x. wang. effects of shrub species and microhabitats on dew formation in a revegetation-stabilized desert ecosystem in shapotou, northern china. journal of arid land. vol. 6, no. 4, 2014, pp 389-399. [11] m. amirmojahedi , k. mohammadi, s. shamshirband, a. seyed danesh, a. mostafaeipour, a. kamsin. a hybrid computational intelligence method for predicting dew point temperature. environmental earth sciences. vol. 75, 2016. 415. doi 10.1007/s12665-015-5135-7. [12] m. sarkar. a new theoretical formulation of dew point temperatures applicable for comfort air-cooling systems. energy and buildings.vol. 86, 2015, pp 243–256. [13] s. ebrahimi, m. jahangiri, h.a. raiesi, a. rahimi ariae. optimal planning of on-grid hybrid microgrid for remote island using homer software, kish in iran. international journal of energetica. vol. 3, no. 2, 2018, pp 13-21. [14] m. rezaei, m. salimi, m. momeni, a. mostafaeipour. investigation of the socioeconomic feasibility of installing wind turbines to produce hydrogen: case study. international journal of hydrogen energy. vol. 43, no. 52, 2018, pp 23135-23147. [15] a. mostafaeipour, a. sedaghat, m. qolipour, m. rezaei, h.r. arabnia, m. saidimehrabad, s. shamshirband, o. alavi. localization of solar-hydrogen power plants in the province of kerman, iran. advances in energy research. vol. 5, no. 2, 2017, pp 179205. [16] m. rezaei, a. mostafaeipour, m. qolipour, h.r. arabnia. hydrogen production using wind energy from sea water: a case study on southern and northern coasts of iran. energy & environment. vol. 29, no. 3, 2018, pp 333357. [17] a. mostafaeipour, m. zarezade, h. goudarzi, m. rezaei-shouroki, m. qolipour. investigating the factors on using the solar water heaters for dry arid regions: a case study. renewable and sustainable energy reviews. vol. 78, 2017, pp 157-166. [18] m. rezaei, a. mostafaeipour, m. qolipour, r. tavakkoli-moghaddam. investigation of the optimal location design of a hybrid wind-solar plant: a case study. international journal of hydrogen energy. vol. 43, no. 1, 2018, pp 100-114. [19] census of the islamic republic of iran, 2006. mojtaba qolipour et al ijeca-issn: 2543-3717. june 2019 page 10 [20] m. rezaei-shouroki, a. mostafaeipour, m. qolipour. prioritizing of wind farm locations for hydrogen production: a case study. international journal of hydrogen energy. vol. 42, no. 15, 2017, pp 9500-9510. [21] w. ming-dong, k. bin, l. xiang-yang, w. xue-ke. grey prediction theory and extension strategy-based excitation control for generator. electrical power and energy systems. vol. 79, 2016, pp 188-195. [22] s.f. liu, y. yang, y. cao, n.m. xie. a summary on the research of gra models. grey systems: theory and application.vol. 3, no. 1, 2013, pp 7–15. [23] q. zhou, v.v. thai. fuzzy and grey theories in failure mode and effect analysis for tanker equipment failure prediction. safety science.vol. 83, 2016, pp 74-79. [24] x. li, w. hipel, y. dang. an improved grey relational analysis approach for panel data clustering. expert systems with applications. http://dx.doi.org/10.1016/ j.eswa.2015.07.066. [25] g. li, d. yamaguchi, m. nagai. a grey based decision making approach to the supplier selection problem. mathematical and computer modeling. vol 36, 2007, pp 573581. [26] o. gassmann, m. keupp. the competitive advantage of early and rapidly internationalizing smes in the biotechnology industry: a knowledge-based view. journal of world business. vol. 42, 2007, pp 350–366. [27] meteorological organization of fars province. [28] j. lin, k. thu, t.d. bui, r.z. wang, k.c. ng, k.j. chua. study on dew point evaporative cooling system with counter-flow configuration. energy conversion and management. vol. 109, 2016, pp 153–165. [29] m. taqavifard, a. mehdimalek. using of grey approach for priority key indexes to enhance strategic syllabuses effects. quant. of industrial management researches. vol. 9, no. 22, 2011, pp 135-165. [30] a. dabaghi, a. mahdimalek. a new method to assessment & priority organizations goals. journal of industry management.vol. 2, no. 4, 2010, pp 57-74. [31] p. bhattacharrya. a grey theory based multiple attribute approach for r&d project portfolio selection. fuzzy information and engineering.vol. 7, 2015, pp 211-225. [32] g. dong, d. yamaguchi, m. nagai. a greybased decision making approach to the supplier selection problem. mathematical and computer modeling. vol. 46, 2007, pp 573581. [33] w. cheng pen, l. fuguo, l. hongya, y. zhanwei, c.h. bo. optimization of structural parameters for elliptical cross-section spiral equal-channel extrusion dies based on grey theory. chinese journal of aeronautics. vol. 26, no.1, 2007, pp 209–216. [34] j. wei, l. zhou, f. wang, d. wu. work safety situation in mainland china using grey theory. applied mathematical modelling. vol.39, no. 2, 2014, pp 924-933. http://dx.doi.org/10.1016/ international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 44-55 ijeca-issn: 2543-3717. june 2019 page 44 a review of requirement engineering process models, tools and methodologies saeed faroom ms software engineering, department of cs&it, university of lahore, gujrat, punjab, pakistan email: saeedfaroom114@gmail.com abstract – as we are living in the era of computer science and almost all individuals and the organizations are completely relying on software systems. the requirement engineering is the most vital and important aspect in the success of any software engineering project. requirement engineering is a set of different process that works at different levels, which are incorporated at individual and organizational level projects we need to consult different sources to find requirements. we need to involve personals from the different fields to find a set of quality requirements. the security issues undergoes as soon as early in the 1st phase of requirements. it is shown from the studies that if we consider quality process of requirement engineering at the phase it results in saving of million dollars. this paper contains the details study and comparison of different re process models and requirement elicitation techniques. this paper elaborates the vital aspects of different requirement engineering process models that help in the selection of appropriate model for the requirement engineers and practitioners working in the industry. this paper also focus on the giving a detailed view of elicitation techniques and comparative study including the characteristics and their strengths and weakness. some strengths and weakness found during detailed study are also structured and listed that is also the helpful for the appropriate selection of re process model. keywords: requirement engineering process models; requirement engineering elicitation tools; comparison of re models received: 20/05/2019 – accepted: 27/06/2019 i. introduction generally the requirements are the definition of desired features ore capabilities of any proposed system. it is highly accepted in the whole software development industry that the requirement engineering is critical in success of any project [4].software systems are subjects to security threats which may influence the organization assets. the security requirements are very important which undergoes at the beginning of the development of the phase. some security threats are technical rather than social, as they define the interaction between social actors like human and organization. also explain the dependencies of actors. in term of security an hacker always in search of vulnerability by performing unwarranted actions. the fixing of software after release is very costly. it is obvious that a better way to achieve secure software is to incorporate security in the software starting from the beginning of the development process, an effective way of development secure software is to educate and train software developers on artificial software security issues [5]. software developers should gain more software security knowledge and know how to follow the best practice of developing security software through various educational and training programs [13]. it is shown from the studies that there are multiple challenges for security requirement engineering which are may as follows: • mostly actual stake holders are not included or consulted at the stage of requirement identification [4]. • requirement analysis phase is limited to the functional requirements and mostly non function requirements are ignored at this stage [4]. • the quality and design requirements are not effectively included at the requirement analysis phase [4]. requirement engineering is a set of different process that works at different levels, which are incorporated at individual and organizational level projects. security requirement engineering deals with specification of security requirements for the system [12]. it is understood that it is very necessary that team must have a good understanding of requirement abder image placée saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 45 engineering process models and their strengths and weakness for any quality software development. this paper focuses on the detailed study and comparison details of different requirement engineering process models defined from the existing literature review and defined some pros and cons that will be very helpful for the professionals for the selection of appropriate models [6]. this paper focuses on the giving a detailed view of requirement engineering process models, and elicitation techniques and comparative study including the characteristics of both and their strengths and weakness [10]. the rest paper contains following sections: the section two contains detailed survey of the re process models the next section three contains the strengths and weakness of the process models which are discussed in the third section and finally in section 4 we have comparison of the different process models. section 5 contains the conclusion of the paper along with future wok and then section contains acknowledgement and finally references. ii. requirement engineering phases figure 1 shows the software engineering community (sec) identifies the following activities as majors in the process of requirement engineering [9]: 1. background research 2. requirement elicitation and analysis 3. requirement prototyping 4. requirement verification and validation 5. requirement specification figure 1. the process of requirement engineering iii. literature review iii.1 requirement engineering process model in our wish to enhance the learning and understanding of different “requirement engineering process models” that already exists we find and explore the some standard “requirement engineering process models” and some other models that were presented by the other researchers that specify the behavior and working of models [6]. iii.1 .1 detail description of re process models a. “kotonya and sommerville linear requirements engineering process model” figure 2 present this abstract linear “requirement engineering process model” in 1980. this model incorporates the repetition between the different requirement engineering activities [6]. these activities are as follows:  requirements elicitation,  requirements analysis and negotiation,  requirements documentation  requirements validation. this model defines that the all these stages in this model overlaps repeatedly during the execution of the process [14]. this mod el includes the iterations which used for validation of requirement engineering repeatedly. this process of iterations continues as the all stakeholders are agreed and to finally system specification document is achieved. this model is highly useable incase where the all the requirements are highly accurate or called as pin point accuracy and these are validated through potential stakes a number of times [7]. figure 2. kotonya and sommerville model b. “macaulay linear requirements engineering process model” this is a pure linear “requirement engineering process model” suggested by macaulay. it does not contain and support the overlapping of requirement engineering activities incorporated in re process. this model contains five stages which are sequentially arranged as shown in the figure below [14]. this model comprises of following stages:  concept  problem analysis  feasibility study  analysis & modeling  requirement documentation. macaulay stated that this model shown in figure 3 is the re process is depend on the relationship of supplier and the customer [6].it is the most simple re model which is mostly used for the small level and less complex projects. this is not a good approach for the large projects [7]. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 46 figure 3. macaulay model c. “loucopoulos and karakostas iterative requirements engineering process model” this model is iterative as well as cyclic model presented by “loucopoulos and karakostas”. this model shows the connection between different re phases. there are following phases [6, 14]:  requirement elicitation  requirements specification  “validation to the problem domain” requirement engineering performed in this model is consisting of several iterations and this is suitable for those systems which uses the approach of delivery by version by version which may be called as iterative development as shown in figure 5[8]. figure 5. loucopoulos and karakostas model d. “spiral model of requirements engineering process” this model “is prosed by by kotonya and sommerville in 1998”.this models operates in spirals. reuirenement engineering process completed in one spiral round in depends on the product under development. every spiral round is divided in two four quads which are as follows:  specification elicitation,  requirements analysis and negotiation,  requirements documentations  requirements validations. the major characteristic of spiral model is easy handling of risks[14]. such as:  speciation delay  requirements change  low roi these risk badly the effect the quality as well as cost of the project. new concepts in the spiral model are that the design of system also created on the base of requirement as shown in figure 6 [7]. figure 6. kotonya and sommerville model e. “mr. shams-ul-arif, mr. qadeem khan, s. a. k. gahyyur tools cost benefit analysis (tcba) re process model” this “requirement engineering model” proposed by “shams-ul-arif, mr. qadeem khan, s. a. k. gahyyur”. this model proposed two processes which are as follows:  if the users are in excess then this model proposed to use the method of surveys for the requirement elicitation.  if the users are in less size then this model proposed to use the method of interviews for the requirement elicitation. the most special characteristic is its ability of “return on investment (roi)” before to the start of the project i.e [15].  computation of costs involving in staff payments  software / hardware  maintenance  recreational  library  networking  employee pensions  health facility the risk management and customer feedback is a plus point of this model as shown in figure 7 [6]. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 47 figure 7. shams-ul-arif, mr. qadeem khan, s. a. k. gahyyur model f. “dhirendra pandey and u. suman an effective requirements engineering process model” the model is presented by “dhirendra pandey and u. suman”.this model made a relation between the “requirements engineering process” and the software development process. for the development of a high quality software product it introduces all important “requirement engineering process which is:  business requirements  customer requirements  user requirements  constraints  security requirements  information requirements  standards to address the problem of hanging requirement this method includes the features of requirement planning phase and requirement management phase as shown in figure 8 [16]. figure 8. dhirendra pandey and u. suman model g. “p.b.f. arts requirements development & management model in highly turbulent environments” this model includes three main phases which are as follows:  intake phase  startup phase  initiation phase this model recommends different three techniques for all the tree phases listed above which are as follows:  in the startup phase brainstorming technique is used for requirement elicitation  in the initiation phase prioritization the requirement as shown in figure 9 [17]. figure 9. the different three techniques [6] h. “k s swarnalatha, g.n srinivasan, and pooja s bhandary bee hive mode” this model is proposed by “k s swarnalatha, g.n srinivasan, and pooja s bhandary”. this model makes the process of requirement elicitation speedy to design the prototype. this model consists of following phases [6, 1]: saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 48 a) background research b) elicitation, analysis c) prototyping d) verification, validation e) requirement specification iv. strengths and weakness of models during the detailed study of “requirement engineering process models” we found the following deferent strengths n weakness in the models [6, 1] [14-17]. table a . kotonya and sommerville linear requirements engineering process model sr. no. strengths weakness i. a) it is highly useable for small level projects. b) this model also called as base for the other methods. a) this model lacks the validation activity b) this model lacks the feed back activity c) this model lacks the support for dynamic requirements. d) this model lacks the support for effort management. e) this model lacks the policies for performing risk management. f) this model lacks the activities of requirement pre processes. table b. macaulay linear requirements engineering process model sr. no. strengths weakness ii. a) this model provide the support to analyze the feasibility of system. b) this model provides the facility of validating customer requirements. c) this is linear model so, it was not support overlapping in activities. a) this model does not support the reverse engineering process. b) this model lacks the policies for performing risk management. c) this model lacks the support for effort management. d) this model lacks the feed back activity e) this model lacks the activities of requirement pre processes. f) this model lacks the facility of requirement changing. table c. loucopoulos and karakostas iterative requirements engineering process model table d. spiral model sr. no. strengths weakness iii. a) this model provide support for user feedback. b) this supports the prototyping . a) this model lacks the policies for performing risk management. b) this model lacks the support for dynamic requirements. c) this model lacks the support for effort management. d) this model lacks the activities of requirement pre processes. sr. no. strengths weakness iv. a) this model provide the facility of contribution of active user. b) this model provides the means of client’s feedback. c) faults can be found in the early stages of software development. d) this model supports the policies for performing risk management. a) this was lack the computing of effort in starting requirement phases. b) this model lacks the activities of requirement pre processes. c) this model lacks the process of requirement prioritization. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 49 a. “the tools cost benefit analysis (tcba) re process model” table d sr. no. strengths weakness v. d) this model provides the means of client’s feedback. e) faults can be found in the early stages of software development. f) this model supports the policies for performing risk management g) the major aspect of this model is reckoning of roi. h) this model lacks the activities of requirement pre processes. i) this model lacks the process of requirement prioritization. j) this model lacks the facility of selecting appropriate selection of elicitation technique. k) this will lack the facility of measuring accuracy of cost used to fix a bug. e. “an effective requirement engineering process model by dhirendra pandey” sr. no. strengths weakness vi. a) this model provide the facility of contribution of active user. b) this model provides the means of client’s feedback. c) this model provide the facility of changing requirement. d) for the software development this provides the means of requirement management and requirement planning. a) this model lacks the support for effort management. b) this model lacks the activities of requirement pre processes. c) this model lacks the policies for performing risk management. d) this model lacks the facility of selecting appropriate selection of elicitation technique. f. “p.b.f. arts requirements development & management model in highly turbulent environments” g. “k s swarnalatha, g.n srinivasan, and pooja s bhandary bee hive model” sr. no. strengths weakness vii. e) this model provide the facility of changing requirement. f) this model provides the facility of requirement prioritization. g) this model provide support for user feedback. h) this model lacks the support for effort estimation. i) this model lacks the activities of requirement pre processes. j) this model lacks the policies for performing risk management. k) this model lacks the activities of requirement documentation. sr. no. strengths weakness viii. l) this model combines both parallel and serial prototyping. m) this model runs the feasibility study along with other phases. n) this model focuses on the vital requirements. o) due to the large time involvement in feasibility phase required a lot of time for the other development phases. p) this model lacks the support for effort estimation. q) this model lacks the activities of requirement pre processes. r) this model lacks the policies for performing risk management. s) this model lacks the facility of selecting appropriate selection of elicitation technique. international journal of energetica (ijeca) https://www.ijeca.info issn: 2543-3717 volume 4. issue 1. 2019 page 44-55 ijeca-issn: 2543-3717. june 2019 page 50 v. requirement engineering tools/techniques requirement engineering is the process of understanding of the actual functionality needed from the system. it is the continues interactions from the stakeholders to know what they want exactly from the system. “requirement engineering” is a complex process and it includes following stages/activities [10]: a) seeking b) determining c) learning d) acquiring e) discovering f) elaborating requirements it is always impossible to get quality requirements form a single source. we need to consult different sources to find requirements. we need to involve personals from the different fields to find a set of quality requirements. to get high quality requirements one must need to find and involve the actual user and get these requirement through the process of requirement elicitation. there is a technique named as prioritization which used to compare the requirements get from different sources. there is no proficient technique for all the cases. may be we find one technique best for a project butt it become useless when we moved on to another project. there may be some weakness and strengths of any technique so, any weakness found in one technique is covered by using another technique parallel to the first one used. it is found from the studies that a number of projects failed only because inappropriate selection and use of elicitation technique [10].there are different tools and techniques available and used for the process of requirement elicitation. the selection of any technique is purely dependent of the type of project and its complexity. we are going to discuss following tools / techniques: 1. interviews 2. surveys 3. questionnaires 4. task analysis 5. domain analysis 6. introspection 7. repertory grids 8. card sorting 9. class responsibility collaboration 10. laddering 11. group work 12. brainstorming 13. joint application development (jad) 14. requirements workshops 15. ethnography 16. observation 17. protocol analysis this section contains the description of above listed “requirement elicitation techniques” and their strengths and weakness also the process and detail for the selection of particular tools [7]. 1. surveys: this technique is used mainly where we have large number of peoples involved or mostly for the “market driven products”. this is used mostly for the surveys such as charity or census [20, 21]. strengths of this technique: a) this technique is helpful for collecting of information samples from a large scale. b) it’s any quick an easy way for information collection if it is design correctly. c) it is relatively a cheap way. weakness of this technique: d) in this process we lack the rich collection of data. e) it is not suitable to get a holistic view of system under consideration. 2. questionnaires it is the simplest tool used. this will contain the open or closed questions. it is useful for the rapid response. in order to get rapid response must make the questioners clearly, concisely with clear definitions. questionnaire is always problem focused. it’s good to avoid the redundancy in the questions [19]. strengths of this technique: a) it is efficient way to get information from a multiple stakes. b) commonly questionnaires consider as useful tool for build foundation for requirement elicitation. weakness of this technique: a) this process lacks the facility of more discussion on the same topics. b) if we get information once it’s tough to find or correct misunderstanding. 3. task analysis this technique uses the working style in hierarchical fashion. in this technique main task and sub task are divided in a hierarchical way. it is also known as tree technique as this works starts from top of the tree and comes down till the roots [22]. strengths of this technique: c) this technique provides the interaction both for the system and the user. d) this task analysis used by manager to analysis the tasks. weakness of this technique: a) this technique requires extra effort in comparison with interviews. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 51 4. domain analysis this technique involves the domain knowledge also called as background knowledge of the domain for which the system is being built. this technique is mostly used when we are going to replace the existing system [23]. strengths of this technique: a) this technique is very useful for the requirement elicitation also include the design document. b) this technique always used as an extension of other technique as an input. weakness of this technique: a) it is complex to find the all hidden details of the domain. b) there is need of highly professional staff and experienced to perform the domain analysis. 5. introspection as it is clear from the name that introspection, it is the process of gathering information before moving for any other technique. it is preprocess to start any “elicitation technique” for the requirement gathering [09, 24]. strengths of this technique: a) it works as parent technique for all other techniques. b) it is helpful to start and work with any other technique. c) it is mainly free technique with respect to cost factor. weakness of this technique: a) to perform this technique analyst must have core knowledge of the business process. b) this technique needs a highly experienced analyst. 6. repertory grids this technique used to make a grid around the requirements for assigning the numbers to requirements [25]. strengths of this technique: a) it is used to find the differences and similarities between requirement information. b) in this technique traceability is quite easy. weakness of this technique: a) it is works with limited framework in case of complex requirements. 7. card sorting in this technique we provide different cards to customer and the responsibility of sorting cards is with the customer accordance with entities of domains [26, 27]. strengths of this technique: a) the main task performed in this technique is the prioritization. weakness of this technique: b) analyst need to be a highly experienced background. c) the group work is most preferable than card sorting. 8. laddering this is a set of series of simple question developed to ask from the customer / client/stakeholder [28]. strengths of this technique: a) this provides a very close contact to the among stake holder and requirement engineer. b) these techniques arrange the requirements of the customer in proper way. weakness of this technique: a) this technique is not recommended in case of large number of requirement or for a large scale system. b) the maintenance of requirements becomes very hard when you come to the operations of deletion. 9. group work in this technique more than one stakeholder are involved and a group meeting is conducted to elicit requirements [29]. strengths of this technique: a) the conflicts occur due to the different requirement this is useful in resolving the issue. b) this process supports the suggestion from all members who joined the group. weakness of this technique: a) this technical need a high effort. b) some time there is a possibility that all stakes are not available at the same time. 10. brainstorming this technique involves the informal discussion of stake holders and they put their input on the specific topic that is started in the discussion [30]. strengths of this technique: a) this useful in means of where multiple stake holders comes up with their ideas. b) every requirement is discussed and finalized. c) this is results in innovative ideas. weakness of technique: a) this technique is not usable to discuss in major issues. 11. joint application development (jad) this technique is used where we have a large number of stakeholders involved. this technique commonly used in the agile methodology where a number of requirements elicited quickly. discussion made in this technique is useful in providing new ways to solve the problems [11, 31]. strengths of this technique: a) this technique provides the means of decision making rapidly and moving towards the solution. b) this will handle those requirements that are changing rapidly. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 52 c) this will provide a well-structured and managed approach. d) it provides the means of direct communication among all stakeholders. weakness of this technique: a) sometime this technique failed to produce the exhaustive validation in a limited time. b) experts working with this technique are must have a strong background knowledge of the domain. 12. requirements workshops requirement workshops is the name of collection of all the meetings that are arranging for the purpose of gathering requirements [32]. strengths of this technique: a) this technique is better than “brainstorming and group interviews” as these results in a good requirement gathering. b) mostly the requirements remain unchanged if these are elicited using this technique. c) the main advantage is that this technique is suitable for the projects of larger size and complex. weakness of this technique: a) with reference to the time and cost this technique is very costly as compared to other techniques. b) it is not feasible for the small level projects. c) the requirements gathering process is relatively slow in this process. 13. ethnography the name of technique “ethnography” relates to the meaning that it relates to the term what the peoples understand from the problem. in other words this is what the peoples understand of the problem and what they think regarding the solution. in re context what the peoples need from the software [33]. strengths of this technique: a) this technique is mostly used in gathering of quality related requirements. b) this is very effective incase when we have to consider the social factor in the problem solution. weakness of this technique: a) this technique failed badly when there are different peoples came with different social issues. b) it is a very tough task to find the social requirements belonging to different peoples. 14. observation it is the requirement gathering process where the requirement engineers are supposed to visit that place number of time to find the domain requirements are called as mutable requirements. this technique is mostly used in collaboration with other elicitation techniques [7]. strengths of this technique: a) as these requirements gathered by this techniques are directly collected by the requirement engineer by their visit of that particular domain so these requirements are highly authentic. b) it’s a post process mainly uses for the validation of requirements gather by using other techniques. weakness of this technique: a) as the travelling costs are too high so this results in a high cost. protocol analysis this is discussion of all possible stakeholders in which they are talk and discuss the requirements loudly [34, 35]. strengths of this technique: a) this provides the analyst working on a specific project with information that is specific to the system processes. b) this provides all the stakeholders to involve and participate. weakness of this technique: a) sometime we cannot get the true requirement picture by this technique. b) as all the participants are talking loudly so there are chances of conflicts among stakeholders. the selection of tool always depends upon the two factors:  type of the project  size of the project  complexity of project vi. methodologies for requirement elicitation to represent the systems modular structure requirement engineering uses different types of methodologies. for the requirement elicitation process model driven approach (mda) is best. as this technique results in the form of easy requirements from the view of both the developer and the designer. this approach is also understandable by the stake holder which has a basic understanding of mda approach [37].  agent based  scenario  goal these are some modeling techniques that are also used for the process of requirement elicitation. these techniques will define the run time process of system as a user interacts with system. methodologies that are commonly used are as follows: a) data flow diagram (dfd) b) entity relationship diagram (erd) c) unified modeling language (uml) saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 53 vii. comparison of models of re models we find a number of “requirement engineering process models” in existing literature. every model contains some strengths and weakness as we discuss those in the above section named “strengths and weakness”. earlier we have studied all the models with respect to the requirement phase. now we will shape the study in a tabular shape. for the comparison we use the following parameters [6, 18]:  linearity  support for changing requirements  iterative in nature  user feedback  support for reverse engineering  risk assessment  criteria for application specific elicitation technique  requirements preprocessing  requirements prioritization  effort estimation characteristics “linear requirements engineering process model” “macaulay linear requirements engineering process model” “iterative requirements engineering process model” “spiral model” “tools cost benefit analysis (tcba)” an effective requirement engineering process model p.b.f. arts requirements development & management model in highly turbulent environments bee hive model linearity   x x x x x x support for changing requirements x x x      iterative in nature x x       user feedback x x   x x x “support for reverse engineering” x x x  x x x x risk assessment x x x   x x x “criteria for application specific elicitation technique” x x x x x x x x requirements preprocessing x x x x x x x x requirements prioritization x x x x x x x  effort estimation x x x x x x x x viii. motivation the major concern of this research is to do a review of different requirement engineering process models along with their strengths and weakness and different requirement engineering tools along with their strengths and weakness to help the professionals in the selection of better set of process model and requirement engineering tool for their project. ix. conclusion in this paper we deeply explain and discussed “requirement engineering process models” their “strengths and weakness” along with the requirement engineering tools and their details along with the “strengths and weakness” of these tools followed by the process of selection of appropriate tool. we have also done comparative study of requirement engineering process models on the basis of some matrices. in case of complex projects one can use more than one models by combining them as it make the usage easy but sometimes it may result in the complexity while moving saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 54 towards the other phases of software development. it is recommended that must be careful in case of combining two models. besides this we will do the comparative study of these models and shape this study in a tabular form. this is also helpful for the selection of any appropriate “requirement engineering process model”. multiple research areas are presented in this paper on the basis of existing literature which helps other researchers to extend the research. the right selection of process model along with right technique is helpful for any professional in terms of cost and time. generally papers are composed of introduction, nomenclature, main parts of the body, conclusions. it must be in two column format in 1 cm spacing between them. manuscripts should be divided into numbered sections and subsections, starting with a numbered introductory text. subsections should be numbered i.1, i.2, ii.1 etc…; appendices with a, b etc… the font sizes of each section heading are bold 12 pts centered and those of the subsection heading italic 10 pts centered, respectively. section and subsection headings must be formatted with 18 pts spacing before the headings and 6 pts spacing after the heading. the text body has to be times new roman 10 pts, single spaced, justified on both margins. flush the first line of each paragraph at 0.4 cm from the left hand margin. x. references [1] k s swarnalatha, g.n srivasam, pooja s bhandary, “ a constructive anddynammic frame workfor requirnment engineering process models – bee ive model,” in ijcet, vol. 5, issue 7, pp. 48-54, july 2014. [2] b. charles haley, robinlaney, d. jonathan moffett, bashar nuseibeh, “ security requirnment engineering : a framework for representationand analysis,” in ieee transaction on software engineering, vol. 34 issue 1, january february 2008. [3] k s swarnalatha, gn srinivasan, megana dravid, raunak kasera, kopal sharma, a survey on requirnment engineering for real time systems based oncustomer requirnments,” in ijarcce, vol. 3, issue 1, january 2014. [4] nancy r mead, ted stehney, security quality requirnment engineering (square) model,” in ijcet, vol. 5, issue 7, pp. 48-54, july 2014. [5] smriti jain , maya ingle, “software security requirnments gathering instrument,” inijacsa, vol. 2, issue 7, 2011. [6] mona batra , dr. archana bhatnagar, “acomparative study of requirnment engineering process model,” in ijarcs, vol. 8, issue 3, march 2017. [7] mr. shams-ularif, mr. qadeem khan, s.a.k gahyyur,“requirnments engineering process, tools/technologies and methodologies,” in ijric, 20092010. [8] dr. rajinder singh,” positive trends in software engineering paractices for higher quality software ,” in ijarimss. [9] pooja s bhandary, kishore pv, swarnalatha ks,“requirnments verification and validation in beehive model,” inijsetr, vol. 5, issue 9, sep 2017. [10] masooma yousaf, m. asger,“comparison of different requirnment elicitation techniques,” inijca, vol. 116, issue 4, april 2015. [11] nabil mohammad ali,“comparison between five models of sofware engineering,” inijcsi, vol. 7, issue 5, sep 2010. [12] ms hafeez, farhan rasheed, mr khan, “an improved model of requirnment management system,” in jitse, 2017. [13] chitreshh banerjee, arpita banerjee,“research on security requirnment engineering :problemand prospects,” in maiojet, vol. 3, issue 3, april 2015. [14] sacha martin, aybuke aurun, ross jeffrty and barbara paech, “requirnement engineering process models in paractice,” in the seventh australian workshop on requirnments engineering, december 2002. [15] shams-ul-arif, mr. qadeem khan, s. a. k. gahyyur, “requirementsengineeringprocesses,tools /technologies, methodologies” in international journal of reviews in computing, 2009-2010. [16] dhirendra pandey, u. suman, “an effective requirement engineering process model for software development and requirements management”, in international conference on advances in recent technologies in communication and computing, ieee society, 2010. [17] p.b.f. arts, “a flexible method for requirements engineering”, master thesis information science radboud university nijmegen. [18] mona batra, archana bhatnagar: “descriptive literature review of requirements engineering models”, international publication in international journal of advanced research in computer science and software engineering, volume 5, issue 2, february 2015. [19] foddy w, constructing questions for interviews and questionnaires, “cambridge university press, cambridge”, (1994). [20] zowghi didar and coulin chad,”requirements elicitation: a survey of techniques, approaches, and tools”. [21] kaufmann morgan “understanding your users:a practical guide to user requirements methods, tools, and techniques”, february 2005. [22] j richardson, tc ormerod, a shepherd,”the role of task analysis in capturing requirements for interface design”,interacting with computers, 1998. [23] a sutcliffe, n maiden, “the domain theoryfor requirements engineering”,1998. [24] m jackson, “problem frames analyzing and structuring software development problems”, 2000. [25] ja goguen, c linde,”techniques for requirements elicitation”, in: proceedings of the ieee international symposium on requirements engineering, san diego, ca,1993. [26] g kelly,“the psychology of personal constructs”,in norton, new york, 1955. [27] r jed. wood, larry e wood, “card sorting: current practices and beyond”, journal of usability studies, november 2008. [28] perini anna, ricca filippo, susi angelo, “tool-supported requirements prioritization: comparing the ahp and cbrank methods”, 2009. [29] perini anna, ricca filippo, susi angelo, “tool-supported requirements prioritization: comparing the ahp and cbrank methods”,in elsevier, pp. 1021-1032, 2009. [30] hinkle d “the change of personal constructs from the viewpoint of a theory of implications”, doctoral dissertation, ohio state university, usa, 1965. [31] stetar bill, re-tool your workers,” advance manufacturing” march 2000. [32] af osborn, “applied imagination. charles scribner’s sons”, new york, 1979. [33] ashish chaudhary, anil punia, malhar pujar,” requirements engineering role in agile development”, 2008. saeed faroom et al ijeca-issn: 2543-3717. june 2019 page 55 [34] gottes diener e, “requirements by collaboration. addison wesley” in boston, ma, 2002. [35] lj ball, tc ormerod, “putting ethnography to work”, in the case for a cognitive ethnography, 2000. [36] j nielsen, t clemmensen, c yssing, “getting access to what goes on in people’s heads: reflections on the thinkaloud technique”, in: proceedings of the 2nd nordic conference on human-computer interaction, aarhus, denmark, 2002. [37] e burge janet, c brown david, “software engineering using rationale” in the journal of systems and software ,vol. 81,issue 13,pp. 395-413, 2008. i. introduction ii. requirement engineering phases iii. literature review iv. strengths and weakness of models� v. requirement engineering tools/techniques vi. methodologies for requirement elicitation vii. comparison of models of re models viii. motivation ix. conclusion x. references