Article AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 072–078 Contents lists available at http://qu.edu.iq Al-Qadisiyah Journal for Engineering Sciences Journal homepage: http://qu.edu.iq/journaleng/index.php/JQES * Corresponding author. E-mail address: Mohamed.AlDawody@qu.edu.iq (Mohamed F. Al-Dawody) https://doi.org/10.30772/qjes.v12i2.587 2411-7773/© 2019 University of Al-Qadisiyah. All rights reserved. Numerical Simulation for the Effect of Biodiesel Addition on the Combustion, Performance and Emissions Parameters of Single Cylinder Diesel Engine Mohammed S. Edama and Mohamed F. Al-Dawodya* a Department of mechanical engineering, University of Al-Qadisiyah, Al-Qadisiyah, Iraq. A R T I C L E I N F O Article history: Received 07 May 2019 Received in revised form 18 June 2019 Accepted 29 June 2019 Keywords: Castor methyl ester Diesel engine Diesel-rk software Engine performance Emission A B S T R A C T This work examines the characteristics of combustion, performance and emissions of single cylinder diesel engine powered by diesel fuel and a different volume percentages of the caster methyl ester (CME). The selected biodiesel is studied numerically using the simulation program diesel-rk. The results reported that peak pressure is closer to the top dead center (TDC), as the percentage of CME. The brake specific fuel consumption (BSFC) is increased slightly as the blending of biodiesel is increased. All the selected biodiesel ratios are found to release higher NOx emission compared to diesel. Dramatic reduction in smoke levels 15.25 %, 35.3 %, 40.7 %, 45.71 %, 49.43 %, and 52.73 % with B10% CME, B20% CME, B30% CME, B50% CME, B70% CME and B100% CME respectively. B20% CME biodiesel was the best remarked ratio which gives slight variations in performance with a good reduction in the carbon emissions compared to diesel fuel. The results are compared with other researchers work and nice convergence is observed. © 2019 University of Al-Qadisiyah. All rights reserved. 1. Introduction Vegetable oil has been a competitive alternative to diesel since 1900, gaining considerable attention during the Second World War because of the lack of fuel at that time and the difficulty of obtaining it. After World War, the world turned to fossil fuel production, which was found affordable because of low production cost. However, after oil production was controlled by OPEC's, the problem of environmental pollution was greatly exacerbated and people's lives were threatened with great risks. It becomes necessary to find an alternative fuel. Access to oil from plant resources has attracted considerable attention. In many countries, vegetable oils are used after esterification as "biodiesel". Biodiesel has evolved to be one of the most widely used biofuels for the partial replacement of petroleum based diesel, especially in recent years. Vegetable oils are most commonly used for biodiesel production [1]. Biodiesel is a sustainable energy source to meet the growing global demand for transportation energy and significantly reduce greenhouse gas emissions. Non-edible vegetable oils are a highly suitable candidate for production of biodiesel where they can be grown in marginal and harsh lands requiring less soil fertility, less maintenance and less water than arable land for edible plant oils [2]. Bio-fuels, particularly castor oil and castor methyl ester, might help a lot to meet the future energy supply demands as well as contributing to the reduction of greenhouse gases emissions and other harmful products of the combustion process[3]. http://qu.edu.iq/ https://doi.org/10.30772/qjes.v12i MOHAMMED EDAM AND MOHAMED AL-DAWODY /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 0072–078 73 Nomenclature Ao, A2,A3 Constants. PM Particulate Matter B10 Volume blend contains 90 % diesel plus 10 % CME R Constant of gas (universal) B20 Volume blend contains 80 % diesel plus 20 % CME CME Castor Methyl Ester B30 Volume blend contains 70 % diesel plus 30 % CME rpm revolutions / minute B50 Volume blend contains 50 % diesel plus 50 % CME rps revolutions /second B70 Volume blend contains 30 % diesel plus 70 % CME T temperature in the cylinder B100 Volume blend contains 100 % CME t time BSFC Brake Specific Fuel Consumption (kg/kW.h) TDC Top Dead Centre DF Diesel Fuel U Instantaneous fuel velocity BSN Bosch Smoke Number U0 Spray Initial velocity [C] cylinder concentration soot Um The velocity of the spray’s front oC degrees centigrade V The cylindrical volume oCA crank angle degrees x heat release proportion CN Cetane Number of fuel xo The fraction of the fuel vapour forming in the delay period. Ea the apparent activation energy for the auto ignition process KT Constant of Evaporation Greek symbols l spray length σ cylinder fuel fractions lm Penetration distance σu Vapor fraction mf Fuel mass τ Delay period (second) NOx Nitrogen Oxides θ Crank angles (degree) p cylinder pressure (pa) 𝜙 Equivalence ratio ps fuel saturation vapour pressure  Exhaust gas exponent One of the most attractive features of biodiesel is its biodegradability and being more environmentally friendly than fossil fuels, resulting in less environmental impact when it releases harmful emissions. Where emissions such as total hydrocarbons and carbon monoxide were observed to be significantly lower with biodiesel than diesel fuel [1]. In addition, it contains about 10–15% oxygen by weight [2]. After the production of biofuels in the world has grown widely, some criteria have to be put in place to ensure the quality of production, including the specifications of the American standard of testing Materials (ASTM) and European Union (EU) specifications. Hence, researchers began to research the possibility of using biodiesel in diesel engines [3]. The researchers have been also using biodiesel as a renewable source to investigate the characteristics of emission, performance as well as combustion parameters. Lin et al. [4], studied diesel oil and 8 kinds of biodiesel in CI engine. Experimental results showed, an increase in BSFC, decreased engine performance slightly and decreased smoke emissions, which is due to the uniform mixing of air and fuel and the strengthening of oxygen due to using a vegetable oil methyl ester. The nitrogen oxides emission is increased as the temperature of combustion is increased total hydrocarbon emission (THC) are decreased because of many factors such as uniform mixing of Fuel-air, higher oxygen quantity and due to longer spray penetrations as well. R. Sattanathan [5] investigated the production of biodiesel (Castor Methyl Ester) (CME)) from castor oil with its performance and emission testing, and the study focused on testing the engine using a mixture of CME. The fuel mixture B25, B50, B75, and B100 is prepared and fed in the 4 strokes, one cylinder, direct injection engine, water cooled with a compression ratio of 17.5: 1. Results of author’s experiments indicate, the brake power of CME was almost similar for the diesel engine, while the specified fuel consumption was higher than diesel. Also, the emission of hydrocarbons and smoke for CME is less than diesel emissions. S. Lee et al. [6] studied the effects of the Karanja oil methyl ester (KOME) blending ratio on spray properties, engine performance analysis and exhaust emissions from the Karanja biodiesel mix. In the engine experience, lower torque, brake thermal efficiency (BTE) and exhaust gas temperature were observed, as well as higher fuel consumption for the biodiesel mix compared to diesel because of the lower heating value of the Karanja biodiesel. The research work is aimed to study the use of various CME biodiesel blending ratios on combustion, and parameters of emissions and performance of single cylinder diesel engine using Diesel-rk simulation program. 2. Biodiesel properties The physical properties of the prepared biodiesel along with diesel fuel are measured accurately at ALDORA refinery factor according to the table reported below. Table 1. displays the characteristics of a different mix of DF and CME biodiesel. The numerical analysis was performed on a direct injection diesel engine and water cooled using a single cylinder. The engine specifications are displayed in Table 2. Table (1). Diesel and CME blends properties Property Density at 15oC (kg/m3) Viscosity at 40oC (pa.s) Calorific value (MJ/kg) Surface tension (N/m) Cetane number Diesel 830 0.002241 45.836 0.028 53.4 B10% CME 837 0.003068 45.686 0.02953 53.06 B20% CME 845.2 0.003925 45.556 0.03106 52.9 B30% CME 851 0.004724 45.386 0.03259 52.38 B50% CME 865 0.00638 45.086 0.03565 51.7 B70% CME 879 0.008036 44.786 0.03871 51.02 CME 900 0.01052 44.336 0.0433 50 Table (2) Engine Dimensions[7] Engine Brand Kirloskar TAF-1 Type of engine 4-Stroke, Diesel Engine, single cylinder Bore stroke 80 mm 110 mm The cylinder capacity 0.553 L The compression ratio 15.5 Rated power 3.7 kW , 1500 rpm Orifice diameter 0.15 mm Injection pressure 220 bar 74 MOHAMMED EDAM AND MOHAMED AL-DAWODY/AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 072–078 3. Numerical simulation approach The multizone combustion model has been used in this work. The fuel distribution is sprayed with 2 stages: free jet & wall jet as illustrated in Fig. 1. There are a specific condition of evaporation and combustion for each zone identified in the model. 1. Free wall (before impingement) - The conical nucleus of free spray. - Front dense spray free. - The diluted outer shell of the spray. 2. After wall impingement another 4 zones are formed: - The near-wall flow (NWF) nucleus - The NWF is dense on the surface of the piston. - Front dense of the NWF. - NWF extensible out zone. Figure 1. Diesel spray zones (M. F. Al-Dawody, [8]) The current speed and location of the elementary fuel mass (EFM) from the injector to the tip of the spray is given by to [9]: [𝑈 𝑈°⁄ ]^(3 ⁄ 2) = 1 − 𝑙/𝑙𝑚 (1) Fig. 2. presents the variation of spray evolution parameters as functions of time. The Governing evaporating details are described in [8]. Figure 2. Spray development v/s time [8]. 3.1. Heat release model The fuel combustion is normally divided into four phases, which have separate chemical and physical properties that restricted combustion speed. a. Delay period. The period of delay is estimated from the equation of Tolstov [10]: 𝜏 = 3.8 ∗ 〖10〗^(−6). 𝑛√(𝑇/𝑃) ∙ 𝑒𝑥𝑝(𝐸𝑎/8.312𝑇 − 70/(𝐶𝑁 + 25)) (2) b. The phase of uncontrolled combustion (Premixed) [11] 𝑑𝑥/𝑑𝜏 = 𝜑° [𝐴° (𝑚𝑓 /𝑉𝑖 )(𝜎𝑢𝑑 − 𝑥° )(0.1𝜎𝑢𝑑 + 𝑥° )] + 𝜑1 (𝑑𝜎𝑢/𝑑𝜏) (3) c- Diffusion phase.[11] 𝑑𝑥/𝑑𝑡 = 𝜑1 (𝑑𝜎𝑢/𝑑𝜏) + 𝜑2 (𝐴2 (𝑚𝑓 𝑉⁄ )(𝜎𝑢 − 𝑥)(∅ − 𝑥) (4) d- Combustion tail [12] 𝑑𝑥/𝑑𝜏 = 𝜑3 𝐴3 𝐾𝑇 (1 − 𝑥)(𝜀𝑏 ∅ − 𝑥) (5) During the process of simulations, Woschni’ s formula has used to predict coefficients of heat transfer in the cylinder[13]. 3.2. The nitrogen oxides model The nitrogen oxide reaction is[12]: 𝑁 + 𝑂2 ↔ 𝑁𝑂 + 𝑂 (6) T The reaction is depended on the oxygen concentration. The volumetric of NO concentration is given by: (7) 3.3. The soot concentration model Soot particle forms grow and oxidizes due to chemical reaction occurring through combustion. It has a deep impact on the pollution of the environment the concentration of soot particle is calculated[8]: [𝐶] = ∫ 𝑑[𝐶] 𝑑𝜏 480 𝜃𝐵 𝑑𝜃 6𝑛 [ 0.1 𝑃 ] 𝛾 (8) The Bosch smoke number (BSN) was obtained from Hartidge smoke equation given below[14]: 𝐻𝑎𝑟𝑡𝑖𝑑𝑔𝑒 = 100[1 − 0.9545 ∗ 𝑒(−24226[𝐶])] (9) The PM emissions (are obtained from[14]: [𝑃𝑀] = 565 [ln 10 10−𝐵𝑜𝑠𝑐ℎ ] 1.206 (10) 3.4. Basic equations of performance[15].: a. Brake thermal efficiency (BTE) Using equation (11) to calculate the brake thermal efficiency BTE = BP ṁf ∗ LCV⁄ (11) where: LCV- Lower heating value of blended fuel (kJ/kg) b. Brake specific fuel consumption The Brake Specific Fuel Consumption (BSFC) is calculated by using the equation (12). BSFC = (ṁf BP)⁄ ∗ 3600 (12) where: ṁf = Fuel consumption rate 4. Results and Discussion The range of operating conditions were constant engine speed 1500 rpm, injection pressure 220 bars and 20o BTDC injection timing. The condition of full load is selected as it gives maximum smoke as well as minimum air/fuel ratio. This gives the right situations to confirm any differences among the fuel blends under study.                                     rps ONOeTRT NONOONep d NOd e T ZZ eee T Z Z 1 . /../23651 /1.10*33.2 2 3365 2 2 38020 7  MOHAMMED EDAM AND MOHAMED AL-DAWODY /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 072–078 75 4.1. Combustion parameters Fig.3 presents the variation of pressure verse crank shaft angle for DF and biodiesel blends at full load. It is found that Pmax is 73.4436 bars for DF at 369 crank angle while it comes nearer to TDC for B100 CME where the maximum pressure was 80.2889 bars at 366o crank angle. The pressure of 10% and 20 % CME are noticed closer to that of DF Figure 3. Variation of cylinder pressure with crank angle The predicted zonal temperature is described in Fig. 4. The higher combustion temperatures for CME mixtures are reported. The high flame temperature is an indicator of the high NOx emissions. The maximum temperature difference between 20% CME and DF is 49 K at 362ᵒ crank angle. It's the direct cause of the high NOx emission of biodiesel. The same observations were noted in the results of [16]. Figure 4. Variation of zonal temperature with crank angle Figs. 5 and 6 present the computed heat release rate and the fraction of heat release for DF and CME biodiesel respectively. The heat release fraction can be defined as the ratio of heat release rate to the lower heat value of the fuel. All CME blends have an earlier start of combustion but lower combustion rates. In the diffusion phase, most fuel has been vaporizing and burning as well, because of the rapid combustion of CME biodiesel. Figure 5. Show the heat release rate vs. crank angle. Figure 6. Show the heat release fraction vs. crank angle Fig. 7. shows the effect of CME ratio on the delay period. Fuel ignition quality is affected by auto ignition. The shorter delay period comes as a result of the difference in cetane number the combustion starts too early, and reduction in the heat released is expected. The same findings are confirmed by [17]. Figure 7. Effect of CME blending on ignition delay 150 200 250 300 350 400 450 500 550 Crank angle (deg.) 0 10 20 30 40 50 60 70 80 90 100 C y li n d e r p re s s u re ( b a r) Simulation results Full load 1500 rpm Diesel 10 % CME 20% CME 30 % CME 50% CME 70% CME CME 340 350 360 370 380 390 400 410 420 Crank angle (deg.) 500 1000 1500 2000 2500 3000 Z o n a l c o m b u s ti o n t e m p e ra u re ( K ) 340 350 360 370 380 390 400 410 420 Crank angle (deg.) 0 10 20 30 40 50 60 H e a t re le a s e r a te ( J /d e g .) 340 350 360 370 380 390 400 410 420 Crank angle (deg.) 0.00 0.20 0.40 0.60 0.80 1.00 H e a t re le a s e f ra c io n ( % ) 0 20 40 60 80 100 CME (%) 2 4 6 8 10 D e la y p e ri o d ( d e g .) Simulation results Full load, 1500 rpm 76 MOHAMMED EDAM AND MOHAMED AL-DAWODY/AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 072–078 4.2. Performance parameters Fig. 8 shows the effect of CME blending on BSFC. BSFC was found to increase with the increase in CME ratio in fuel. To obtain the same torque and output power for each tested fuel, BSFC was higher for CME and its mixtures. BSFC for the B20%CME is higher than the DF by 4.85%, while it is 7.39% higher for the CME B100. The higher level of density and lower heating energy are responsible for the increase in BSFC. These results are similar to those of [18] and [19]. Figure 8. The variation of BSFC with CME biodiesel blends Fig. 9. shows BTE variation with CME ratios. It was observed that the BTE of the CME mixtures were less than the DF. The efficiency is slightly reduced as a result of increasing CME percentages because of lower calorific value of biofuel over that of ordinary diesel fuel. Figure 9. The BTE vs. CME blends. 4.3. Emission parameters Fig. 10. describes the effect of CME blends on the smoke quantity (BSN). The smoke level for all CME blends is lower than that of the DF. The numerical findings reported a promising reduction in soot emissions by 15.25 %, 35.3 %, 40.7%, 45.6%, 49.43% and 52.7 % for B10, B20, B30, B50, B70 and B100 respectively. This due to a higher quantity of oxygen exist in biodiesel which has deep impact on oxidation of fuel, hence the tendency to produce smoke is greatly reduced [20]. Figure 10. The BSN vs. CME blends Fig. 11. explains the relation between the NOx emissions with different percentages of CME blend. The emission of NOx is higher for all CME blends as compared to diesel fuel. This is because of higher oxygen quantity in the biofuel. The higher cylinder pressure, as well as combustion temperature caused by early start of combustion, are the main reasons for increasing NOx emission. The message in Fig. 10 as well as Fig. 11. says that B20% CME was the best compromise blending ratio, where 20% gives a good reduction in BSN but a sharp increase in NOx emissions is reported hence the B20% CME is the best promising ratio chosen in this study. Figure 11. The relation between NOx emissions with CME biodiesel blends. 5. Results Verification In this section, the point of discussion is to compare some of the results obtained from an experimental investigation of other researchers[17, 21, 22] at the same conditions of the present study with the numerical results 0 20 40 60 80 100 CME (%) 0.38 0.40 0.42 0.44 B S F C ( k g /k W .h ) Simulation results Full load 1500 rpm BSFC Vs CME % 0 20 40 60 80 100 CME (%) 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 B S N Simulation results Full load 1500 rpm 0 20 40 60 80 100 CME (%) 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 N O x ( p p m ) Full load, 1500 rpm simulation results 0 20 40 60 80 100 CME (%) 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 B T E ( % ) Simulation Results Full load 1500 rpm BTE Vs CME MOHAMMED EDAM AND MOHAMED AL-DAWODY /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 12 (2019) 072–078 77 of Diesel-rk software. From Figs. 12 and 13 a slight difference between the two is recorded which indicate accepted reasonable accuracy of the present work. Figure 12. Verification of the spray tip penetration between different researchers. Figure 13. Verification of the cylinder pressure between different researchers 6. Conclusions  CME blends are found to shift maximum pressure closer to the TDC.  The substitution of CME blending make an early combustion atarting as compared with DF due to the shorter delay period.  The CME ratio was observed to increase BSFC as well as decrease brake thermal efficiency slightly.  Promising reduction in BSN with all CME mixtures as compared to DF.  It was observed that all CME mixtures emit higher NOx emissions compared to DF.  Best mixing percentage is 20% CME that reports lower emissions compared to pure diesel and promising results of performance is noticed as well. REFERENCES [1] M. Siddiqur Rahman, M. Hossain, M. Nawsher Ali Moral, Production of Biodiesel Fuels from Castor Oil Using H2SO4 as Catalyst, 2016. [2] M.F. Al_Dawody, S. 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