FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 40 Article Thermodynamic and environmental performance of a Kalina-based multigeneration cycle with biomass ancillary firing for power, water and hydrogen production Fidelis I. Abam1*, Victor Umeh2, Ekwe Bassey Ekwe3, Samuel O. Effiom4, Jerome Egbe5, Adie J. Anyandi4, James Enyia4, Ugwu Hyginus Ubauike2, Macmanus C. Ndukwu6 1Energy, Exergy and Environment Research Group (EEERG), Department of Mechanical Engineering, University of Calabar, Nigeria 2Department of Mechanical Engineering, Michael Okpara University of Agriculture Umudike, Nigeria 3Department of Mechanical Engineering, Covenant University Ota, Nigeria 4Department of Mechanical Engineering University of Cross River State, Calabar, Nigeria 5Department of Civil and Environmental Engineering, University of Cross River State, Calabar, Nigeria 6Department of Agricultural and Bioresources Engineering, Michael Okpara University of Agriculture Umudike, Nigeria A R T I C L E I N F O Article history: Received 19 April 2023 Received in revised form 02 June 2023 Accepted 20 June 2023 Keywords: Energy, Exergy, Kalina cycle, Sustainability, Hydrogen *Corresponding author Email address: fidelisabam@unical.edu.ng DOI: 10.55670/fpll.futech.3.1.5 A B S T R A C T The performance of a Kalina-based multigeneration cycle for power, water, and hydrogen production is investigated from thermo-environmental, sustainability, and thermo-economic perspectives. The plant comprises a gas turbine (GT), Kalina cycle (KC), and vapor absorption system (VAS) as the bottoming cycle and an integrated domestic water heater and proton-electron membrane (PEM) electrolyzer for hydrogen production. The system's models were simulated with Engineering Equation Solver (EES) codes. The results indicate a net energy efficiency of 53.48% and exergy efficiencies of 50.05 %, with an additional 30,178 kW of products from the bottoming cycles. The GT contributed approximately 85.81 % of the overall exergy destruction. The system's exergo-thermal index (ETI) stood at 1.713, with the GT only having an ETI of 2.106. Similarly, the exergetic sustainability index (ESI) of the multigeneration plant was not greater than 2.04. The exergoeconomic analysis shows a low average energy cost from the GT, estimated at 0.836 $/GJ, compared to the Kalina subsystem, which stood at 6.53 $/GJ. The thermodynamic and cost evaluation of the system demonstrates substantial benefits from the plant, which kept the hydrogen production rate at 0.1524 kg/hr. 1. Introduction The role of energy availability in economic development cannot be over-emphasized. Energy remains the fulcrum for sustainable development [1]. For the past decades, the fundamental processes for energy generation, especially electricity, have been from burning fossil fuels in gas turbine plants, steam plants, and a combination of the two in cogeneration [2, 3]. Several plant configurations have been developed and implemented to increase these thermal plants' energy efficiency. Research is increasing to produce different products from these systems, which has increased in scope in recent times [4, 5]. However, the configuration of the lower bottoming cycles and the choice of operating parameters play vital roles in developing sustainable products with minimal exergy destruction and environmental impact. Among the many options for lower bottoming cycles to increase energy conversion system products are the organic Rankine cycle (ORC) [6-8], Kalina cycle [9, 10], Goswam cycle [11] steam turbine cycle [12], and for water electrolyzers [13]. Multigeneration plants have been presented in the literature. For example, Dev and Attri [12] presented a Multi-plant cycle based on ORC, which produces six products: electricity, Future Technology Open Access Journal https://doi.org/10.55670/fpll.futech.3.1.5 February 2024| Volume 03 | Issue 01 | Pages 40-55 Journal homepage: https://fupubco.com/futech ISSN 2832-0379 mailto:fidelisabam@unical.edu.ng https://doi.org/10.55670/fpll.futech.3.1.5 https://fupubco.com/futech https://fupubco.com/ FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 41 heating, hot water, hydrogen, cooling, and dry air. The results indicate an energetic coefficient of performance (COP) of approximately 60%, while that for the exergetic COP was estimated at 10%. Similarly, the study in reference [13] presented a primary Brayton cycle with several strings of bottoming cycles that can provide electrical power, domestic water heating, and cooling through refrigeration processes embedded in ORC and vapor absorption cycles. The study obtained energy and exergy efficiencies of 44.22 and 61.50 %, respectively, with an exergo thermal index of 0.675. Additionally, other lower cycles are reported to produce hydrogen, while some are used for the desalination of water [14, 15]. The study in [14] proposed a multi-cycle power plant for cooling, heating, and desalting water production. The result shows that the water production rate was 0.364 kg/s with a cooling rate and power output estimated at 1 MW and 30.5 MW, respectively. Similarly, Abam et al. [15] designed and developed a novel incorporated cycle based on the solid- oxide fuel cell-GT for concurrent fresh water, electricity, and hydrogen production. The exergetic efficiency was estimated at 54.2 % at refresh water rate production of 90.1 m3/h at a unit cost of 32.9 $/GJ. Furthermore, Anvari et al. [16] analyzed an innovative solar-based multigeneration plant. The system was developed for power generation, desalination, and hydrogen production. The thermodynamic assessment indicates that the multigeneration system had 23.2 % as energy efficiency and 6.2% for exergy efficiency. Ref [17] performed a thermodynamic and economic evaluation of a geothermal-based integrated plant which comprises ORC, domestic water heater, electrolyzer, and absorption refrigeration system to produce hydrogen and electricity, heating and cooling. The total efficiencies were estimated at 34.98% energy and 49.17% exergy, whereas the hydrogen production rate and unit cost of production stood at 0.052 g/s and 5.967 $/kg, respectively. Furthermore, Khalid et al. [18] presented a techno-economic valuation of a solar, geothermal-driven multigeneration system to produce; electricity cooling, hot water, heating, and hydrogen. The hydrogen production rate was estimated at 2.7 kg/h while $ 476,000 and $ 0.089/kWh were the net presents and the levelized cost of electricity. Ref [19] proposed a geothermal multigeneration plant comprising an electrolyzer, absorption cycle, Kalina, and flash cycles for hydrogen and ice production. The results show a maximum exergy efficiency of 26.25%. Multigeneration systems require adding bottoming cycles to gas-fired, geothermal, or solar-based topping cycles to generate multiple products. Thus, several choices on the mode of a bottoming cycle depend on several factors. These may include the exiting temperature of the topping cycle flue gas, the required efficiency, the quantity of desired products, and the economic and environmental impact of the bottoming cycle. The Kalina cycle can provide an efficiency gain of 10-50 % compared to the conventional thermodynamic cycles with equivalent output. However, system modification or adjustment in the thermodynamic pathways may be necessary to maximize the waste heat used in the bottoming cycles. The current study introduced a dual heat input to improve the thermal heat requirement of the PEM electrolyzer from the same energy source. The latter will increase the hydrogen production yield since hydrogen production yield is related to the quantity of electricity and heat in the PEM electrolyzer. An external thermal heat source for the electrolyzer may increase system costs and maintenance procedures. In the current study, an external heat source for the electrolyzer was avoided. The system was designed to utilize the dual heat input from the condensate of the two Kalina condensers. The latter innovation improved the hydrogen production yield and reduced the multigeneration plant's economic cost. In light of this development, this research proposes a modified Kalina-based multigeneration cycle incorporating biomass gasification for reheating in the combined topping cycle. The study thus determines the thermo-environmental and thermo-economic performance of the modified Kalina-based multigeneration cycle. The best operating parameters corresponding to low operating costs and environmental impact were equally evaluated. 2. System description The operation starts at state (1) in Figure 1, where the air is drawn to the low-pressure compressor (LPC), and the temperature and pressure are raised to state (2). An intercooler reduces the mechanical work required for compression from the state (2) to (3). The cooled air is recompressed by a high-pressure compressor (HPC) at state (3). The compressed air is heated partly by an expanded gas from the low-pressure turbine (LPT). Fuel is added to the combustion chamber (CC) at constant pressure, raising the energy level of the air stream to the high-pressure turbine (HPT), which expands to a pressure sufficient to drive both the HPC and LPC. The expanded gas is reheated with biomass gas for expansion in the LPT to produce shaft work which drives an alternator to produce electricity. After partly raising the air temperature in a heat exchanger, the expanded gas is made to pass through a vapor generator which powers the Kalina cycle embedded with a vapor absorption system (VAS). Ammonium water and lithium bromide drive the Kalina and VAS system, respectively. In the Kalina cycle, after the ammonia water solution receives heat, the energy level of the mixture increases at the state (17). The separator is provided to separate the ammonium water solution into rich and weak solutions. The rich solution expands in the turbine producing electrical energy. The expanded vapor, still rich, is further separated in another separating vessel. The rich part of the mixture is condensed and throttled, and evaporated, providing cooling in the first part of this cycle. Meanwhile, the weak solution already expanded in the turbine and separated is throttled to a pressure equal to the weak solution at state (24) and mixes with the hot vapor leaving at state (23) after being equally throttled. These two streams heat the desorber for powering the VAS. The exiting stream at the desorber is passed through a heat exchanger before being added up with the resulting stream used for refrigeration at state (31). The summation produces a stream at state (32), which passes through a heat exchanger and condenser and is finally pumped to the vapor generator to commence the next cycle. The heat obtained from the dual condensation of the expanded refrigerants in the Kalina cycle is used to heat the water directed for electrolysis in the PEM electrolyzer. Part of the electricity generated from the Kalina turbine is utilized for the electrolyser's operation to produce hydrogen. 3. Methodology and system modelling 3.1 Thermodynamic modelling The general energy flow balances in a thermodynamic system under steady for the kth component are presented in Eq (1) [20, 21]. FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 42 Figure 1. Schematic of the multigeneration plant ∑ �̇�𝑘 + ∑ �̇�𝑖 (ℎ1 + 𝐶𝑖 2 2 + 𝑔𝑧1) = ∑ �̇�𝑒 (ℎ𝑒 + 𝐶0 2 2 + 𝑔𝑧2) + ∑ 𝑊 (1) The general exergy balance for a control volume in a steady state, neglecting potential, kinetic, and electrical energy, is defined as: �̇�𝑥𝑑 = ∑ (1 − 𝑇0 𝑇𝑘 )𝑘 �̇�𝑘 − �̇�𝑐𝑣 + ∑ (𝑛𝑖�̇�𝑥𝑖) − ∑ (𝑛𝑒𝐸�̇�𝑒)𝑒𝑖 (2) Where �̇�𝑥𝑑 is the exergy destruction rate, (1 − 𝑇0 𝑇𝑘 ) �̇�𝑘 is the exergy flow rate accompanying heat transfer, �̇�𝑐𝑣 is the rate of work done within the control volume, 𝑛𝑖�̇�𝑥𝑖 and 𝑛𝑒𝐸�̇�𝑒 is the exergy flow rate in and out of the control volume. Exergy destruction is expressed in terms of product and fuel for a specific component. �̇�𝐷,𝑘 = �̇�𝐹,𝑘 − �̇�𝑃𝑘−�̇�𝐿,𝑘 (3) The exergy efficiency,𝜓𝑘, and the exergy destruction ratio is equally defined for the kth component as: 𝜓𝑘 = �̇�𝑃𝑘 �̇�𝐹,𝑘 (4) 𝑌𝐷,𝑘 = �̇�𝐷,𝑘 �̇�𝐹,𝑡𝑜𝑡𝑎𝑙 (5) Furthermore, Eqs (1) to (5) were applied to Figure 1 to derive the energy quantities for the system presented in Table 1 in Appendix. 3.1.1 Exergoeconomic modeling The components’ purchase and equipment cost (PEC) are written as functions of their operating parameters. The general cost balance for a control volume for the 𝑘𝑡ℎ component is presented [21]. �̇�𝑞,𝑘 + ∑ �̇�𝑖,𝑘𝑖 + �̇�𝑘 = ∑ �̇�𝑒,𝑘𝑒 + �̇�𝑤,𝑘 (6) Where �̇�𝑞,𝑘 , is the cost associated with the 𝑗𝑡ℎ sum of exergy streams to the system’s 𝑘𝑡ℎ, ∑ �̇�𝑖,𝑘𝑖 , is the levelized cost rate for the 𝑘𝑡ℎ component, �̇�𝑘. The cost associated with the 𝑗𝑡ℎ sum of exergy streams from the system’s 𝑘𝑡ℎ component is ∑ �̇�𝑒,𝑘𝑒 , while the work associated with the 𝑘𝑡ℎ component in the system is denoted with the term �̇�𝑤,𝑘. The cost of the 𝑗𝑡ℎ stream is related to the cost of specific cost and the exergy, work, or heat with the relationships: FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 43 �̇�𝑗 = 𝑐𝑗�̇�𝑥𝑗 (7) �̇�𝑤,𝑘 = 𝑐𝑤�̇� (8) �̇�𝑞,𝑘 = 𝑐𝑞�̇� (9) The cost rate �̇�𝑘 for the components is present as: �̇�𝑘 = 𝑃𝐸𝐶𝐹×𝐶𝑅𝐹×𝜙 𝑁×3600 (10) PECF, CRF, and 𝜙 represent the purchase of equipment cost function, capital recovery factor, and maintenance factor, respectively. The system’s annual operational hours are denoted with N while the capital recovery factor is expressed: 𝐶𝑅𝐹 = 𝑖|1+𝑖|𝑛 |1+𝑖|𝑛−1 (11) Where n is the estimated plant life in years, another exergy- related index is the cost of exergy of product and fuel for the component. A detailed description of the component cost of fuel and product is found in [22]. The general relationship for evaluating the specific cost of a product for the kth component 𝑐𝑃,𝑘 ($/𝑘𝐽), and that of fuel 𝑐𝐹,𝑘 ($/𝑘𝐽), as well as the exergoeconomic factor, 𝑓 is presented in Eqs (12) – (14), respectively. 𝑐𝑃,𝑘 ($/𝑘𝐽) = �̇�𝑃,𝑘 �̇�𝑃,𝑘 (12) 𝑐𝐹,𝑘 ($/𝑘𝐽) = �̇�𝐹,𝑘 �̇�𝐹,𝑘 (13) 𝑓 = �̇�𝑘 �̇�𝑘+ �̇�𝐷,𝑘 (14) The cost of exergy destruction is expressed in Eq (15). A summary of the cost-related terms for Figure 1 is presented in Table 2, while the PEC for the plant components is shown in Table 3. �̇�𝐷,𝑘 = 𝑐𝑃,𝑘𝐸𝐷,𝑘 (15) 3.2 Thermoenvironmental analysis The environmental effect is evaluated by approximating the measure of pollutants produced by the plant. These include nitrogen oxide, �̇�𝑁𝑂𝑥 (kg/s), CO2, �̇�𝐶𝑂2 (kg/s) and CO, �̇�𝐶𝑂 (kg/s). The quantity of these emissions produced and their production rates depend on the following indices: retention time, τ (s), combustion chamber pressure drop, ∆𝑃𝐶𝐶 (kPa), adiabatic flame temperature, 𝑇𝑝𝑧 presented [23, 24]. Consequently, the emission rates of production and the harmful emission factor𝐹𝐸𝐹, are defined in Eqs (16) to (20). �̇�𝑁𝑂𝑥 = 1.5×1015𝜏0.5𝑒−(7110 𝑇𝑝𝑧⁄ ) 𝑃6 0.05( Δ𝑃𝐶𝐶 𝑃6 ) 0.5 (16) �̇�𝐶𝑂 = 1.79×108𝜏0.5𝑒(7800 𝑇𝑝𝑧⁄ ) 𝑃6 0.05𝜏( Δ𝑃𝐶𝐶 𝑃6 ) 0.5 (17) �̇�𝐶𝑂2 = 𝑦𝐶𝑂2�̇�𝑔 ( �̅�𝐶𝑂2 �̇�𝑔 ) (18) 𝑐𝑜2,𝑠𝑝 = 3600 ( �̇�𝐶𝑂2 �̇�𝑛𝑒𝑡 ) (19) 𝐹𝐸𝐹 = �̇�𝑁𝑂𝑥+�̇�𝐶𝑂+�̇�𝐶𝑂2 �̇�𝑔 (20) Where 𝐶𝑂2,𝑠𝑝(𝑘𝑔𝐶𝑂2/𝑀𝑊ℎ) describes the amount and the specific 𝐶𝑂2 emissions. Similarly, �̇�𝑔, �̅� , 𝑦𝐶𝑂2 and �̅�𝐶𝑂2 are the rate of mass flow of flue gas, flue gas molar mass, mass fraction and the 𝐶𝑂2 molar mass. The adiabatic flame temperature 𝑇𝑝𝑧 is defined by Eq (21). All parameters, constants and the terms x, y and z in Eq (21) are estimated according to the procedure in [24]. 𝑇𝑝𝑧 = 𝐴𝜎𝛼exp[ 𝛽(𝜎 + 𝜆)2]𝜋𝑥∗ 𝜃𝑦∗ 𝜓𝑧∗ (21) 3.3 Sustainability indicator 3.3.1 The exergetic utility index The exergetic utility index (EUI) is depicted in Eq (22) and measures the extent of exergy resource utilization in a system regarding the same system's net output. It is a function of combustion efficiency,𝜆𝐶𝐶 , net output,�̇�𝑛𝑒𝑡 , exergy input, �̇�𝑥𝑖𝑛 and the exergy efflux to the environment, �̇�𝑥𝑜𝑢𝑡 [15]. 𝐸𝑈𝐼 = 𝜆𝐶𝐶×�̇�𝑛𝑒𝑡 �̇�𝑥𝑖𝑛−�̇�𝑥𝑜𝑢𝑡 (22) 3.3.2 Exergo-thermal index The exergo-thermal index (ETI) measures the thermal impact of the system on the environment during the energy conversion process. Low values of ETI are desired and can be achieved by continuously utilizing high-temperature flue gas from energy conversion systems in powering other low-heat bottoming cycles, expressed as: 𝐸𝑇𝐼 = 𝐸𝑈𝐼 ℑ = 𝜆𝐶𝐶×�̇�𝑛𝑒𝑡 (�̇�𝑥𝑖𝑛−�̇�𝑥𝑜𝑢𝑡) × 1 𝛶 (23) Where 𝛶 denotes the enviro-thermal conservation factor, expressed as: Υ = 𝑇0 𝑇𝑓 (24) Where 𝑇0 is the ambient temperature and 𝑇𝑓 is the temperature of the flue gas. 3.3.3 Exergetic sustainability index The exergetic sustainability index (ESI) compares the magnitudes of a system’s net product to its exergy destruction. A system with ESI less than unity underutilizes the exergy resources, and it is not desirable. Conversely, a system with ESI greater than unity is desirable as its net output exceeds the total exergy destruction. The ESI is expressed by [25]. 𝐸𝑆𝐼 = 𝑊𝑁𝑒𝑡 �̇�𝐷,𝑇𝑜𝑡𝑎𝑙 (25) 4. Results and discussion 4.1 Thermodynamic properties and operating conditions The simulation results of the system were obtained using a developed computer code written in EES. The initial operating conditions are presented in Table 4. The model development was built on the succeeding assumptions: the surrounding temperature and pressure exist at 25 oC and 1.013 bar, respectively. The system and its subcomponents were evaluated at steady-state conditions. Pressure and temperature variations were neglected. The system's boundaries were treated as adiabatic. The working fluid for the Kalina system is ammonium water solution at 0.28. Likewise, the properties of the system, including the enthalpy and exergy flow rates used to calculate system performance, are shown in Table 5. FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 44 4.2 Performance analysis of the system based on operating data The performance indices considered for the study are presented in Table 6. The system net energy and exergy efficiency was calculated at 53.48 and 50.05 %, respectively. The multigeneration system improved the topping cycle by 19.03 and 2.58 % in energy and exergy efficiencies, respectively. The improvement was ascribed to the added products from the bottoming cycles estimated at 30,178 kW. These additional products include the power generated from the Kalina turbine, VAS and Kalina system cooling, and the quantity of hot water produced from the domestic water heater. The net power from the topping cycle stood at 55.605 MW. Also, the system hydrogen production rate stood at 0.1524 kg/h, with about 3498 kW of cooling and a coefficient of performance of 4.304. 4.3 Component exergy destruction (ED) rates The system components' ED rates are shown in Table 7. About 85.81 % of EDs were from the GT topping cycle due to significant ED rates around the combustion chamber (CC). The GT CC and reheater contributed approximately 54.65 and 22.57 % of the ED, respectively, to the total ED. The main reason for the large ED in the CC is the large temperature difference between the combustion gases and the hot air. Using alternative preheated fuels before combustion will reduce ED in the CC. In the present study, operating the reheater with biomass syngas at 154 oC reduced ED by nearly 25 %. Furthermore, with the integration of the bottoming cycles, about 15089.77 kW ED was avoided, equivalent to 14.19 % of the total ED. Also, an additional product of 30178 kW was achieved, which increased the exergetic sustainability of the bottoming cycle to approximately 1.99. The latter validates retrofitting the topping cycle, the Kalina and VAS cycles. 4.4 Exergoeconomic parameters of the plant The values of the initial investment, monetary flow rate and levelized capital cost (LECC) rate are shown in Table 8. The GT HPT has the highest levelized cost per hour, calculated at 41.5 $/hr, followed by GT LPT and GT LPC, estimated at 34.19 and 12.17 $/hr, respectively. Similarly, the exergoeconomic parameters of the subsystems are depicted in Tables 9-12. From Table 9, the combustion chamber and reheater contribute about 39.903 and 20.613 $/hr to the total ED cost calculated at 106.4 $.hr. The CC and reheater have the least exergoeconomic factors of 0.112 and 0.279, respectively. One method to reduce ED cost in the CC is to improve combustion efficiency and reduce the temperature difference Table 2. Component cost and auxiliary equations for the multigeneration plant Component Exergoeconomic balance Auxiliary equation GT LPC �̇�1 + �̇��̇�𝐿𝑃𝐶 + �̇�𝐿𝑃𝐶 = �̇�2 Nil GT intercooler �̇�2 + �̇�48 + �̇�𝐼𝑁𝑇 = �̇�3 + �̇�49 �̇�2�̇�3 − �̇�3𝐸2 = 0 GT HPC �̇�3 + �̇��̇�𝐻𝑃𝐶 + �̇�𝐻𝑃𝐶 = �̇�4 Nil GT Hex �̇�4 + �̇�11 + �̇�𝐻𝐸𝑋 = �̇�5 + �̇�12 �̇�11�̇�12 − �̇�12𝐸11 = 0 GT CC �̇�5 + �̇�6 + �̇� 𝐶𝐶 = �̇�7 Nil GT HPT �̇�7 + �̇� 𝐻𝑃𝑇 = �̇�8 + �̇��̇�𝐻𝑃𝐶 + �̇��̇�𝐿𝑃𝐶 �̇�7�̇�8 − �̇�8𝐸7 = 0 �̇��̇�𝐿𝑃𝐶 �̇�𝐻𝑃𝐶 − �̇��̇�𝐻𝑃𝐶 �̇�𝐿𝑃𝐶 = 0 GT REH �̇�8 + �̇�9 + �̇� 𝐻𝑃𝑇 = �̇�10 Nil GT LPT �̇�10 + �̇� 𝐿𝑃𝑇 = �̇�11 + �̇��̇�𝐿𝑃𝑇 �̇�10�̇�11 − �̇�11𝐸10 = 0 Kal. Vap Gen. �̇�12 + �̇�37 + �̇�𝑉𝐺 = �̇�13 + �̇�17 �̇�12�̇�13 − �̇�13𝐸12 = 0 Kal. Sep 1 �̇�17 + �̇�𝑆𝐸𝑃1 = �̇�18 + �̇�22 �̇�18�̇�22 − �̇�22𝐸18 = 0 Kal. Valve 1 �̇�22 + �̇�𝑉1 = �̇�23 Nil Kal. Valve 2 �̇�21 + �̇�𝑉2 = �̇�24 Nil Kal. Turb. �̇�18 + 𝑍𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏 = �̇�20 + �̇�𝑊𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏 + �̇��̇�𝑃𝑢𝑚𝑝1 �̇�18�̇�20 − �̇�20𝐸18 = 0 �̇�𝑊𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏 �̇�𝑃𝑢𝑚𝑝1 − �̇��̇�𝑃𝑢𝑚𝑝1 𝑊𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏 = 0 Kal. Sep 2 �̇�20 + �̇�𝑆𝐸𝑃2 = �̇�21 + �̇�28 �̇�21�̇�28 − �̇�28𝐸21 = 0 Kal. CND 1 �̇�28 + �̇�59 + �̇�𝐶𝑁𝐷1 = �̇�29 + �̇�60 �̇�28�̇�29 − �̇�29𝐸28 = 0 Kal. Valve 3 �̇�29 + �̇�𝑉3 = �̇�30 Nil Kal. Evap 1 �̇�30 + �̇�67 + �̇�𝐸𝑉𝑃 = �̇�31 + �̇�68 �̇�67�̇�68 − �̇�68𝐸67 = 0 Kal. HEX 1 �̇�26 + �̇�36 + �̇�𝐻𝐸𝑋 = �̇�27 + �̇�37 �̇�26�̇�27 − �̇�27𝐸26 = 0 Kal. HEX 2 �̇�32 + �̇�35 + �̇�𝐻𝐸𝑋 = �̇�33 + �̇�36 �̇�32�̇�33 − �̇�33𝐸32 = 0 Kal. CND 2 �̇�33 + �̇�57 + �̇�𝐶𝑁𝐷2 = �̇�34 + �̇�58 �̇�33�̇�34 − �̇�34𝐸33 = 0 Kal. Pump 1 �̇�34 + �̇��̇�𝑃𝑢𝑚𝑝1 + 𝑍𝑃𝑢𝑚𝑝̇ 1 = �̇�35 Nil VAS desorber �̇�25 + �̇�44 + �̇�𝐷𝐸𝑆𝐵 = �̇�26 + �̇�38 + �̇�45 �̇�25�̇�26 − �̇�26𝐸25 = 0 �̇�38�̇�45 − �̇�45𝐸38 = 0 VAS HEX 3 �̇�43 + �̇�45 + �̇�𝐻𝐸𝑋 = �̇�44 + �̇�46 �̇�45�̇�46 − �̇�46𝐸45 = 0 VAS Valve 4 �̇�39 + �̇�𝑉4 = �̇�40 Nil VAS Pump 2 �̇�42 + �̇��̇�𝑃𝑢𝑚𝑝2 + �̇�𝑃𝑢𝑚𝑝2 = �̇�43 Nil VAS Absorber �̇�41 + �̇�47 + �̇�65 + �̇�𝐴𝐵𝑆𝐵 = �̇�42 + �̇�66 |�̇�66 − �̇�65| ∗ �̇�42 − �̇�42 ∗ |�̇�66 − �̇�65| = 0 VAS EVP 2 �̇�40 + �̇�63 + �̇�𝐸𝑉𝑃 = �̇�41 + �̇�64 �̇�63�̇�64 − �̇�64𝐸63 = 0 VAS Valve 5 �̇�46 + �̇�𝑉5 = �̇�47 Nil VAS CND 3 �̇�38 + �̇�61 + �̇�𝐶𝑁𝐷3 = �̇�39 + �̇�62 �̇�38�̇�39 − �̇�39𝐸38 = 0 Water heater �̇�13 + �̇�15 + �̇�𝑊𝐻 = �̇�14 + �̇�16 �̇�13�̇�14 − �̇�14𝐸13 = 0 PEM Electrolyser �̇�52 + �̇�19 + �̇�𝐸𝐿𝐸𝐶𝑇𝑅. = �̇�53 + �̇�54 |�̇�52 + �̇�19||�̇�53 + �̇�54| − |�̇�53 + �̇�54||�̇�52 + �̇�19| = 0 PEM Hex �̇�58 + �̇�60 + �̇�50 + �̇�𝐻𝐸𝑋 = �̇�51 + �̇�69 |�̇�58 + �̇�60| ∗ �̇�69 − �̇�69 ∗ |�̇�58 + �̇�60| = 0 PEM O2 separator �̇�54 + �̇�𝑂𝑥𝑦𝑔𝑒𝑛𝑆𝑒𝑝 = �̇�55 + �̇�56 �̇�55�̇�56 − �̇�56𝐸55 = 0 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 45 between the working fluid and combustion fuel. However, this can be achieved by firing the CC with preheated fuel. In the Kalina subsystem (Table 10), the vapour generator (VG) cost improvement potential is primarily dependent on the equipment cost rates than the cost due to ED. Subsequently, since the VG cost is directly linked to the quantity of heat transfer, the choice of working fluid and efficient design of the heat transfer area is germane in reducing the cost of the system components. Table 3. Component cost functions, cost of product and cost of fuel [15, 18, 22] Component Cost function [$] Cost of product Cost of fuel GT LPC 39.5�̇�2 0.9 − 𝜂𝐿𝑃𝐶 | 𝑃2 𝑃1 | 𝑙𝑛 | 𝑃2 𝑃1 | �̇�2 − �̇�1 𝑥. �̇�𝐻𝑃𝑇 GT intercooler 130 | 𝐴𝐼𝑁𝑇 0.093 | 0.78 �̇�49 − �̇�48 �̇�2 − �̇�3 GT HPC 39.5�̇�4 0.9 − 𝜂𝐻𝑃𝐶 | 𝑃4 𝑃3 | 𝑙𝑛 | 𝑃4 𝑃3 | �̇�4 − �̇�3 |1 − 𝑥|. �̇�𝐻𝑃𝑇 GT Hex 130 | 𝐴𝐻𝐸𝑋 0.093 | 0.78 �̇�5 − �̇�4 �̇�11 − �̇�12 GT CC | 46.08�̇�5 0.995 − 𝑃7 𝑃5 | |1 + 𝑒𝑥𝑝(0.018𝑇7 − 26.4)| �̇�7 �̇�5 + �̇�6 GT HPT | 479.34�̇�7 0.92 − 𝜂𝐻𝑃𝑇 | 𝑙𝑛 | 𝑃7 𝑃8 | |1 + 𝑒𝑥𝑝[0.036𝑇7 − 54.4]| �̇�𝐻𝑃𝑇 �̇�7 − �̇�8 GT REH | 46.08�̇�8 0.995 − 𝑃10 𝑃8 | |1 + 𝑒𝑥𝑝(0.018𝑇10 − 26.4)| �̇�10 �̇�8 + �̇�9 GT LPT | 479.34�̇�7 0.92 − 𝜂𝐿𝑃𝑇 | 𝑙𝑛 | 𝑃10 𝑃11 | |1 + 𝑒𝑥𝑝[0.036𝑇10 − 54.4]| �̇�𝐿𝑃𝑇 �̇�10 − �̇�11 Kal. Vap Gen. 130 | 𝐴𝑉𝐴𝑆𝐺𝐸𝑁 0.093 | 0.78 �̇�17 − �̇�37 �̇�12 − �̇�13 Kal. Valve 1 37 | 𝑃22 𝑃23 | 0.68 �̇�23 �̇�22 Kal. Valve 2 37 | 𝑃21 𝑃24 | 0.68 �̇�24 �̇�21 Kal. Turb. | 479.34�̇�32 0.92 − 𝜂𝑇 | 𝑙𝑛 | 𝑃18 𝑃20 | |1 + 𝑒𝑥𝑝[0.036𝑇18 − 54.4]| �̇�𝐿𝑃𝑇 + �̇�𝐾𝑎𝑙𝑃1 + �̇�𝑉𝐴𝑆𝑃2 �̇�18 − �̇�20 Kal. CND 1 516.62 �̇�𝐾𝑎𝑙𝐶𝑁𝐷1 0.15∆𝑇𝐾𝑎𝑙𝐶𝑁𝐷1 �̇�60 − �̇�59 �̇�28 − �̇�29 Kal. Valve 3 37 | 𝑃29 𝑃30 | 0.68 �̇�30 �̇�29 Kal. Evap 1 309.4 | �̇�𝐾𝑎𝑙𝐸𝑉𝑃1 0.15∆𝑇𝐾𝑎𝑙𝐸𝑉𝑃1 | 0.85 �̇�31 − �̇�30 �̇�67 − �̇�68 Kal. HEX 1 130 | 𝐴𝐾𝑎𝑙𝐻𝐸𝑋1 0.093 | 0.78 �̇�37 − �̇�36 �̇�25 − �̇�26 Kal. CND 2 516.62 �̇�𝐾𝑎𝑙𝐶𝑁𝐷2 0.15∆𝑇𝐾𝑎𝑙𝐶𝑁𝐷2 �̇�58 − �̇�57 �̇�33 − �̇�34 Kal. Pump 1 705.5 |0.001𝑊̇ 𝐾𝑎𝑙𝑃𝑢𝑚𝑝1 | 0.71 |1 + 0.2 1 − 𝜂𝑃 | �̇�35 − �̇�34 �̇�𝐾𝑎𝑙𝑃1 VAS HEX 3 130 | 𝐴𝑉𝐴𝑆𝐻𝐸𝑋3 0.093 | 0.78 �̇�44 − �̇�43 �̇�45 − �̇�46 VAS Valve 4 37 | 𝑃39 𝑃40 | 0.68 �̇�47 �̇�46 VAS Pump 2 705.5 |0.001𝑊̇ 𝐾𝑎𝑙𝑃𝑢𝑚𝑝2 | 0.71 |1 + 0.2 1 − 𝜂𝑃 | �̇�43 − �̇�42 �̇�𝑉𝐴𝑆𝑃2 VAS EVP 2 309.4 | �̇�𝑉𝐴𝑆 𝐸𝑉𝑃2 0.15∆𝑇𝑉𝐴𝑆 𝐸𝑉𝑃2 | 0.85 �̇�41 − �̇�40 �̇�63 − �̇�64 VAS CND 3 516.62 �̇�𝑉𝐴𝑆𝐶𝑁𝐷3 0.15∆𝑇𝑉𝐴𝑆𝐶𝑁𝐷3 �̇�62 − �̇�61 �̇�38 − �̇�39 Water heater 130 | 𝐴𝐻𝐸𝐴𝑇𝐸𝑅 0.093 | 0.78 �̇�16 − �̇�15 �̇�13 − �̇�14 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 46 The pump has an exergoeconomic factor of 1, suggesting a zero contribution to ED costs. This is realistic as the system pumps operated in isentropic conditions. The total cost of product and fuel for the GT (Table 9) is calculated at 2.67 and 6.06 $/GJ, respectively, while that for the Kalina (Table 10) and VAS subsystems (Table 11) exist at 32.92 and 84.89 $/GJ, and 17.97 and 25.93 $/GJ, respectively. The results show a lower average energy cost from the GT (0.836 $/GJ) compared to the Kalina subsystem and the VAS. For the PEM electrolyzer, economic parameters are equally presented in Table 12. Furthermore, the exergoeconomic factors (𝑓𝑘) for all the subsystems are similarly presented in Tables 9-12, estimated at 59.59%, 68 %, 8.656%, 30.71%, 47.41% for GT, KAL, VAS, and PEM electrolyzer respectively. Low values of 𝑓𝑘 for any system component indicate high ED cost, which signifies a high prospective for improvement, while high values of relative cost difference (𝑟𝑘) indicate prospects for system optimisation. The 𝑟𝑘 for the GT, KAL, VAS, and PEM electrolyzer subsystems are calculated at 127 %, 157 %, 30% and 30.71 %, respectively. The joined effects of 𝑟𝑘 and 𝑓𝑘 show that the GT and KAL subsystems have the highest potential for improvement, followed by VAS and PEM electrolyzer, which have the narrow potential for optimisation. 4.5 Sensitivity analysis 4.5.1 Effect of dead state temperature on system efficiencies Figure 2 presents the effect of dead state temperature on system performance. The energy and exergy efficiencies of the GT and Kalina cycles and the coefficient of performance of the VAS were observed. The dead state temperature (DST) ranged between 288 and 302 K. The results show that the DST increase led to a reduction in system efficiency. At high DSTs, the compressor work increases, reducing the net system output, especially at the topping GT cycle. The results also show that for every 5 K rise in DST, the energy and exergy efficiency reduced by 0.40 and 0.44 %, respectively. The COP of the VAS was estimated at 4.30 and is constant throughout the DST range, showing that the DST has no direct link with COP measured parameters. 4.5.2 Effect of heat input on the PEM electrolyzer heat exchanger The effect of the required temperature of heating at the inlet to the PEM heat exchanger (HEX) is investigated on the hydrogen yield rate (Figure 3). The water inlet from the condenser of the Kalina system improves the quantity of the hydrogen production rate due to higher PEM water inlet rate to cater for the high energy exchange required in the HEX. Since the temperature of the water entering the PEM electrolyzer is fixed at 95oC, the figure demonstrates the range of water temperatures at the PEM HEX. At most, 102.02OC is required for optimum hydrogen yield with other operating PEM electrolyzer parameters constant as indicated in its modelling. 4.5.3 Effect of gasifier temperature on hot water rate power output Figure 4 shows the effect of gasifier temperature in the topping cycle on the quantity of hot water production at a given hot water temperature and the magnitude of power in the Kalina turbine. Very high gasifier temperatures result in slightly reduced biomass syngas calorific value. Thus, the energy level of the bottoming cycles, including the water heater, is reduced, affecting the quantity of hot water at 95oC. However, the power output from the Kalina turbine was constant at 181 kW. This is attributable to the fixed operating conditions of the Kalina system within a range of heat transfer requirements around the Kalina vapour generator. 4.5.4 Effect of ammonia mass fraction on cooling and turbine output The effect of ammonia mass fraction on the power output and cooling rate of the Kalina system is presented in Figure 5. In the design condition, a mass fraction of 0.28. The result indicates that increasing ammonium mass fraction leads to a higher turbine work and cooling rate. However, at mass fractions higher than 30 per cent, and with the operating pressures in the system, the pump work requirements are significantly higher than the turbine output. Therefore, it is not feasible to operate the system with an ammonia mass fraction in excess of 0.30. Table 4. Design operating data [15, 23] Parameter Unit Value Ambient temperature o C 25 Ambient pressure Bar 1.013 GT Lower compression ratio Dim. 3.162 GT Higher compression ratio Dim. 3.162 Overall pressure ratio Dim. 10 GT Heat exchanger effectiveness % 75 Low pressure turbine isentropic efficiency % 85 High pressure turbine isentropic efficiency % 85 Low pressure compressor isentropic efficiency % 80 High pressure compressor isentropic efficiency % 80 mass of air to the topping cycle kg/s 200 mass of gas at the inlet to the first combustion chamber kg/s 3.131 mass of gas at the inlet to the reheater kg/s 21.49 High pressure turbine inlet temperature o K 1350 Low pressure turbine inlet temperature o K 1200 The exit temperature of intercooler water o C 85 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 47 Table 5. Thermodynamic properties at the state points State Temperature [oC] Pressure [Bar] Enthalpy [kJ/kg] Entropy [kJ/kg.K] Mass [kg] Exergy [kW] 1 25 1.013 298.40 5.695 200 0.00 2 170.1 3.203 445.00 5.765 200 25150.00 3 120 3.203 397.90 5.643 200 22965.00 4 311.3 10.13 590.90 5.72 200 57016.00 5 523.2 10.13 818.10 6.051 200 82706.00 6 25 10.13 42300.00 - 2.533 124996.00 7 977 10.13 1337.00 6.565 202.5 157799.00 8 689.7 2.843 1004.00 6.628 202.5 86580.00 9 427 2.843 19841.00 - 2.991 62661.00 10 927 2.843 1278.00 6.882 205.5 128628.00 11 696.6 1.013 1012.00 6.932 205.5 70840.00 12 484.7 1.013 776.00 6.658 205.5 39178.00 13 471 1.013 761.10 6.638 205.5 37326.00 14 349.6 1.013 631.20 6.448 205.5 22305 15 20 1.013 83.30 0.294 85 0.00 16 95 1.013 397.40 1.248 85 2523.00 17 180 20 1264.00 3.639 2.5 862.60 18 180 20 2164.00 5.901 0.97 606.80 19 - - - - - 4.774 20 136.9 7 1971.00 5.901 0.97 419.60 21 136.9 7 509.50 1.753 0.0644 4.69 22 180 20 694.10 2.205 1.53 206.70 23 79.8 0.8 694.10 2.39 1.53 122.20 24 77.6 0.8 509.50 1.821 0.0644 3.39 25 79.7 0.8 686.70 2.367 1.594 125.60 26 60 0.8 176.80 0.8905 1.594 14.33 27 55 0.8 146.50 0.799 1.594 9.42 28 136.9 7 2080.00 6.209 0.9056 412.80 29 42.9 7 -42.60 0.48 0.9056 36.90 30 -5.5 0.8 -42.60 0.5609 0.9056 15.08 31 15 0.8 332.40 1.909 0.9056 -9.22 32 43.3 0.8 213.80 1.236 2.5 25.78 33 38 0.8 123.00 0.9479 2.5 13.61 34 25 0.8 -73.38 0.3073 2.5 -0.06 35 25.1 20 -71.24 0.3073 2.5 5.28 36 40 20 -7.27 0.5168 2.5 9.19 37 50 20 35.55 0.6514 2.5 15.91 38 79.7 0.07424 2649.00 8.478 1.5 189.40 39 41 0.07424 171.10 0.5836 1.5 2.20 40 1.7 0.006812 171.10 0.6229 1.5 -15.35 41 1.7 0.006812 2503.00 9.114 1.5 -312.80 42 34.6 0.006812 92.00 0.1987 11.16 3.02 43 34.6 0.006812 92.00 0.1987 11.16 3.02 44 67 0.006812 156.30 0.3978 11.16 58.69 45 79.7 0.006812 229.30 0.4167 9.661 40.51 46 45 0.006812 169.30 0.2361 9.661 -19.08 47 35 0.006812 169.30 0.1817 9.661 137.40 48 20 1.013 83.30 0.294 37.58 0.00 49 80 1.013 334.30 1.073 37.58 705.30 50 20 1.013 83.30 0.294 5 0.00 51 95 1.013 397.40 1.248 5 148.40 52 85 1.013 355.30 1.132 10 221.60 53 85 1.013 4843.00 56.17 0.0000423 0.00 54 85 1.013 355.30 1.132 5 110.80 55 85 1.013 55.01 0.1683 0.000336 0.00 56 85 1.013 355.30 1.132 5 110.80 57 20 1.013 83.30 0.294 8.383 0.00 58 34 1.013 141.90 0.4893 8.383 3.18 59 20 1.013 83.30 0.294 7.065 0.00 60 85 1.013 355.30 1.132 7.065 156.60 61 20 1.013 83.30 0.294 44.42 0.00 62 40 1.013 166.96 0.5702 44.42 59.99 63 25 1.013 298.42 5.695 151.5 0.00 64 2 1.013 275.30 5.614 151.5 142.40 65 20 1.013 83.30 0.294 69.55 0.00 66 35 1.013 146.00 0.5029 69.55 35.41 67 25 1.013 298.40 5.695 13.01 0.00 68 -1 1.013 272.30 5.603 13.01 15.73 69 33 1.013 137.80 0.4762 15.45 4.14 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 48 Table 6. Performance parameters of the energy system Performance Index Unit Value LPC Power MW 29.151 HPC Power MW 38.743 LPT Power MW 55.605 HPT Power MW 68.754 GT Net Power Output MW 55.605 GT Relative Exergy Efficiency % 29.63 Kalina Relative Exergy Efficiency % 11.13 Kalina Relative Energy Efficiency % 16.97 VAS COP - 4.304 Kalina turbine power kW 187.2 Kalina pump power kW 5.337 Kalina evaporator cooling kW 339.6 Kalina Exergy of cooling kW 24.3 Kalina net power kW 181.9 VAS evaporator cooling kW 3498 Exergy of cooling kW 297.4 VAS desorber heat kW 812.9 PEM hydrogen output kg/h 0.1524 System net output MW 86.320 System net input MW 161.403 System net energy efficiency % 53.48 System net exergy efficiency % 50.05 4.5.5 Gasifier mass flow rate on thermo environmental parameters and hot water production rate The effect of the gasifier mass flow rate at the reheater was investigated on the quantity of hot water production and thermo-environmental parameters, as shown in Figure 6. The result indicates that the gasifier mass flow rate increases the amount of hot water production when maintained at 95 oC. This slight increase in gasifier mass flow rate has a negligible impact on ETI, decreasing slightly from 2.115 to 2.109 units. The trend is attributed to the variation in the flue gas temperature after the water heater. Also, similar thermodynamic conditions are responsible for a low comparative variation on the EUI when the gasifier mass flow rate increases. Conversely, increasing the gasifier mass flow rate reduces the overall ESI. The system’s ESI dropped from 0.822 to 0.358, which is attributed to large exergy destruction in the reheater and LPT. 4.5.6 Effect of ammonia mass fraction on thermo- environmental parameters Figure 7 shows the effect of ammonia mass fraction on thermo-environmental parameters. The variations in the ammonia mass fraction slightly affect the ETI, EUI, and ESI. Higher ammonia concentration results in a rich and increased quantity of ammonium vapour for expansion in the turbine and evaporation in the evaporators. Thus, the power output of the Kalina system rises. Nonetheless, since the EUI, ETI, and ESI are wholly affected by the variation of the net output from the entire multigeneration plant, the effect of Kalina output is negligible on these thermo-environmental parameters. However, due to high exergy destruction in the Kalina vapour generator resulting from the increase in the ammonium concentration, the ESI reduces slightly from 0.5279 to 0.5251 between ammonia concentrations of 0.25 and 0.40. 4.5.7 Effect of primary zone temperature on environmental emissions Figure 8 present the effect of the primary zone temperature on the production of 𝐶𝑂, CO2 and 𝑁𝑂𝑋 emissions. The parameters of the primary zone temperature in the combustion chamber were estimated using the methodology in [24]. Table 7. Summary of systems component and total exergy destruction Component Exergy destruction (ED) [kW] [%] ED/cycle and component [%] total of ED GT CC 49903.00 54.652 46.901 GT HEX 5971.00 6.539 5.612 GT HPC 4692.00 5.139 4.409 GT HPT 2466.00 2.701 2.318 GT INTCL 1481.00 1.621 1.392 GT LPC 4001.00 4.382 3.760 GT LPT 2183.00 2.391 2.052 GT reheater 20613.00 22.575 19.373 GT total ED 91310.00 100.000 85.818 KAL. CND1 219.3.00 15.517 0.206 KAL. CND2 10.480 0.742 0.009 KAL. EVP1 8.568 0.606 0.008 KAL. HEX1 1.813 0.128 0.002 KAL. HEX2 8.265 0.585 0.008 KAL. PUMP1 0.003 0.00018 2.5E-06 KAL. SEP1 49.040 3.469 0.046 KAL. SEP2 2.147 0.151 0.002 KAL. TURB 0.000 0.000 0.000 KAL. VALVE1 84.560 5.983 0.079 KAL. VALVE2 1.301 0.092 0.001 KAL. VALVE3 21.820 1.544 0.021 KAL. VG 1006.00 71.181 0.945 Kalina total ED 1413.290 100.00 1.328 VAS absorber 213.900 21.543 0.201 VAS condenser 2 127.200 12.811 0.119 VAS desorber 318.800 32.108 0.299 VAS evaporator 2 155.100 15.621 0.146 VAS HEX 3 3.942 0.397 0.004 VAS pump 2 0.000 0.000 0.000 VAS valve 4 17.550 1.768 0.016 VAS valve 5 156.400 15.752 0.147 VAS ED 992.890 100.000 0.933 Water heater 12502.00 100.000 11.750 PEM electrolyzer 115.600 63.658 0.109 PEM HEX 65.990 36.338 0.062 PEM oxygen separator 0.0060 0.0032 5.5E-06 The primary zone temperature affects the emission rates at critical temperatures in excess of 1895 o K. The rate of 𝑁𝑂𝑋 emissions are higher (10.57 kg at 2400 oK) compared to 𝐶𝑂 (0.01380 kg at 2400 oK). Consequently, it is recommended to operate the system at optimum primary zone temperature to reduce 𝑁𝑂𝑋 emissions. The CO2 emissions from the system are not directly related to the primary zone temperature but to the emissions coefficient of the natural gas after combustion and its mass flow rate. However, this system calculated the instantaneous CO2 emissions at 27.35 kg/s at a flue gas mass flow rate of 205.5 kg/s. FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 49 Table 8. Summary of initial investment, monetary flow rate and Levelized capital cost rate Plant component Purchase of equipment cost ($) * Levelized cost per year ($/yr.)* Levelized cost per hour ($/hr.) * GT CC 213978 38022 5.038 GT HEX 155098 27559 3.652 GT HPC 517708 91992 12.19 GT HPT 1762604 313198 41.5 GT INTCL 93214 16563 2.195 GT LPC 517708 91992 12.19 GT LPT 1452180 258038 34.19 GT reheater 213093 37864 5.017 KAL. CND1 1953 347 0.04598 KAL. CND2 1953 347 0.04598 KAL. EVP1 1953 347 0.04598 KAL. HEX1 3353 595.9 0.07895 KAL. HEX2 3353 595.9 0.07895 KAL. PUMP1 5405 960.5 0.1273 KAL. SEP1 13067 2322 0.3076 KAL. SEP2 13067 2322 0.3076 KAL. TURB 156801 27862 3.692 KAL. VALVE1 325.5 57.83 0.007663 KAL. VALVE2 325.5 57.83 0.007663 KAL. VALVE3 325.5 57.83 0.007663 KAL. VG 191786 34079 4.515 VAS absorber 1060 188.3 0.02495 VAS condenser 3 1137 202.1 0.02678 VAS desorber 2679 476.1 0.06308 VAS evaporator 2 1017 180.7 0.02395 VAS HEX 3 1254 222.8 0.02952 VAS pump 2 5321 940.3 0.0123 VAS valve 4 325.5 57.83 0.007663 VAS valve 5 325.5 57.83 0.007663 Water heater 2444 434.3 0.05755 PEM electrolyser 3823 679.2 0.0225 PEM HEX 955.6 169.8 0.0225 PEM oxygen separator 1147 203.8 0.027 4.5.8 Effect of gasifier temperature and mass flow on the unit cost of electricity The effect of gasifier temperature and mass flow rate on the unit cost of electricity is shown in Figure 9. The temperature of the gasifier and the mass flow correlate with the unit cost of electricity (UCOE) regarding the system power output. The UCOE based on the initial design conditions was obtained as 21.44 N/kWh (USD 0.0329/kWh), which is more attractive than the current tariff plan in Nigeria of 54 N/kWh (USD 0.083/kWh). The gasifier temperature and the mass flow rate increase leads to a decrease in the UCOE following a high output generation from the system. Therefore, the reduction in UCOE is more with respect to the gasifier temperature increase than the gasifier mass flow rate. 4.5.9 Effect of ammonium mass fraction on the unit cost of electricity The effect of ammonia mass fraction on the UCOE and PEC for the entire system is shown in Figure 10. The increase in ammonia mass fraction leads to a slight increase in the UCOE. High ammonium mass fraction results in high turbine output, which increases the turbine purchase equipment cost. Although there is an additional power generation from a high ammonium mass fraction, the UCOE increase is negligible. Figure 2. Dead state temperature on performance parameters Figure 3. Effect of heat input on the PEM electrolyzer heat exchanger Figure 4. Gasifier temperature effect on hot water production rate and power output 288 290 292 294 296 298 300 302 49 50 51 52 53 54 55 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Dead state temperature (K) E n er g y a n d e x er g y e ff ic ie n cy ( % ) Exergy efficiencyExergy efficiencyEnergy efficiencyEnergy efficiency V A S C O P VAS COPVAS COP 500 600 700 800 900 24 26 28 30 32 34 36 100 120 140 160 180 200 Gasifier temperature ( o C) H o t w a te r p r o d u c ti o n r a te ( k g /s ) Hot waterHot water K a li n a t u r b in e o u tp u t (k W ) Kalina turbine outputKalina turbine output FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 50 4.5.10 Effect of gasifier temperature and mass flow on system total cost In Figure 11, the effect of gasifier mass flow rate and temperature is investigated on the system's total cost. The system’s net cost was estimated at $ 5335411.5 based on the operating conditions in Table 6. The total cost comprises purchasing equipment (PEC) for all system components. Thus an increase in both the gasifier temperature and mass flow rate significantly raises the total PEC of the system. The resultant effect of increased gasifier temperature and mass flow rate cumulatively enhances the power requirements of the LPT. Consequently, the PEC of the LPT, GT HEX, Kalina vapour generator, and water heater contributes about 33.76 % of the entire plant's PEC. 4.6 Optimum parameters For optimal performance, the study considered the following objective functions (OBF): total exergy efficiency Table 9. Exergoeconomic parameters for the GT and reheater topping cycle Component �̇�𝑭 ($/GJ) �̇�𝑷 ($/GJ) �̇�𝑫 (MW) �̇�𝑫 ($/hr.) 𝒁 ($/hr.) 𝒁 + �̇�𝑫 ($/hr.) 𝒇𝒌 (%) 𝒓𝒌 (%) GT CC 0.2217 0.3007 49.903 39.8243 5.038 44.8623 11.30 35.63 GT HEX 0.2139 0.3028 5.971 4.597719 3.652 8.2497 44.30 41.55 GT HPC 0.3649 0.6516 4.692 6.165175 12.19 18.355 66.40 78.53 GT HPT 0.3007 0.4851 2.466 2.669287 41.5 44.169 93.40 61.34 GT INTC 0.6967 3.0239 1.481 3.714362 2.195 5.909 37.10 334.06 GT LPC 0.4851 0.6969 4.001 6.986962 12.19 19.177 63.50 43.67 GT LPT 0.2139 0.3930 2.183 1.680655 34.19 35.871 95.30 83.77 GT REH 0.1749 0.2139 20.613 12.98443 5.017 18.001 27.90 22.22 Table 10. Exergoeconomic parameters for the Kalina power-cooling bottoming cycle Component �̇�𝑭 ($/GJ) �̇�𝑷 ($/GJ) �̇�𝑫 (MW) �̇�𝑫 ($/hr.) 𝒁 ($/hr.) 𝒁 + �̇�𝑫 ($/hr.) 𝒇𝒌 (%) 𝒓𝒌 (%) KAL. CND1 2.5492 6.1994 0.2193 2.0126 0.0460 2.0585 2.230 143.190 KAL. CND2 2.4799 14.579 0.0105 0.0935 0.0459 0.1395 32.95 487.876 KAL. EVP1 1.0000 2.1805 0.0086 0.0000 0.0459 0.0459 100.00 118.051 KAL. HEX1 1.9857 4.7164 0.0018 0.0130 0.0789 0.0919 85.89 137.515 KAL. HEX2 2.4787 13.327 0.0083 0.0738 0.0789 0.1527 51.70 437.671 KAL. PUM1 8.0153 14.968 2.6E-06 7.5E-05 0.1273 0.1274 99.94 86.738 KAL. SEP1 2.1012 2.3329 0.0490 0.3710 0.3076 0.6786 45.33 11.025 KAL. SEP2 2.3329 2.5496 0.0022 0.0180 0.3076 0.3256 94.46 9.2890 KAL. TURB 2.3326 7.5825 0.0000 0.0000 3.6920 3.6920 100.00 225.064 KAL. VAL1 2.3329 3.9644 0.0846 0.7102 0.0077 0.7179 1.07 69.928 KAL. VAL2 2.5474 4.1527 0.0013 0.0119 0.0077 0.0196 3.91 63.019 KAL. VAL3 2.5542 6.3918 0.0218 0.2006 0.0077 0.2083 3.68 150.247 KAL. VG 0.2129 1.9493 1.0060 0.7713 4.5150 5.2864 85.41 815.217 Table 11. Exergoeconomic parameters for the vapor absorption bottoming cycle Component �̇�𝑭 ($/GJ) �̇�𝑷 ($/GJ) �̇�𝑫 (MW) �̇�𝑫 ($/hr.) 𝒁 ($/hr.) 𝒁 + �̇�𝑫 ($/hr.) 𝒇𝒌 (%) 𝒓𝒌 (%) VAS ABS 0.0909 1.2461 0.2139 0.0701 0.0250 0.0950 26.26 1269.62 VAS CON 3 1.4121 4.5304 0.1272 0.6466 0.0268 0.6734 3.980 220.82 VAS DESB 0.8303 1.4123 0.3188 0.9529 0.0631 1.0160 6.210 70.097 VAS evaporator 2 1.0001 1.0224 0.1551 0.0000 0.0240 0.0240 100.00 2.23 VAS HEX 3 0.3313 0.6916 0.0039 0.0047 0.0296 0.0342 86.26 108.76 VAS pump 2 15.014 17.473 0.0000 0.0000 1.02E-07 1.02E-07 100.00 16.38 VAS valve 4 0.1408 0.3406 0.0176 0.0089 0.0077 0.01660 46.28 141.91 VAS valve 5 20.663 24.9180 0.0031 0.2290 0.0050 0.2340 97.69 20.59 Table 12. Exergoeconomic parameters for the PEM electrolyzer Component �̇�𝑭 ($/GJ) �̇�𝑷 ($/GJ) �̇�𝑫 (MW) �̇�𝑫 ($/hr.) 𝒁 ($/hr.) 𝒁 + �̇�𝑫 ($/hr.) 𝒇𝒌 (%) 𝒓𝒌 (%) WATER heater 0.2140 1.2793 12.502 9.6297 0.05755 9.6873 5.9 497.93 PEM Electrolyzer 4.5650 9.3813 0.116 1.8998 0.0225 1.9223 1.17 105.50 PEM HEX 6.3660 6.7198 0.066 1.5124 0.0225 1.5348 1.47 5.56 PEM oxygen separator 9.3813 9.4491 5.79E-06 0.0002 0.0270 0.027196 99.28 0.723 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 51 (𝜓) and the total product cost rate. The 𝜓 is to be maximized, while the total cost rate is to be reduced or maximized. The total cost rate model equation of the multigeneration plant is integrated with the cost rate of the pollution damage. Figure 5. Effect of ammonia mass fraction on Kalina cycle performance Figure 6. Gasifier mass flow rate on environmental parameters and hot water production rate Figure 7. Effect of ammonia mass fraction on thermo environmental parameter The OBFs are described as follows: 𝜓𝑜𝑣𝑒𝑟𝑎𝑙𝑙 = {�̇�𝑊𝐿𝑃𝑇 +�̇�𝑊𝐻𝑃𝑇 +�̇�𝑊𝐾𝑇 +�̇�𝑅𝐾𝑎𝑙𝑖𝑛𝑎 +�̇�𝑅𝑉𝐴𝑆 }−{�̇�𝑊𝐿𝑃𝐶 +�̇�𝑊𝐻𝑃𝐶 +∑ �̇�𝑊𝑃𝑖 6 𝑖=1 } 𝐴𝑑 (26) Where 𝐴𝑑 of Eq (26) is expressed in Eq (27). 𝐴𝑑 = ‖[1 − 𝑇0 𝑇6 ] �̇�6 + [1 − 𝑇0 𝑇9 ] �̇�9‖ (27) Where �̇�6 and �̇�9 are the heat addition into the GT combustion chamber and the complementary firing process (the reheater) Figure 1. Figure 8. Effect of primary zone temperature on environmental emissions Figure 9. Effect of gasifier temperature and mass flow on the unit cost of electricity Figure 10. Effect of ammonia mass fraction on the unit cost of electricity 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 24.0 24.1 24.2 24.3 24.4 24.5 0.0 0.5 1.0 1.5 2.0 2.5 Gasifier mass flow rate (kg/s) H ot w at er p ro d u ct io n r at e (l it re s) Hot waterHot water T h er m oe n vi ro n m en ta l p ar am et er s ESIESIETIETI EUIEUI 1500 2000 2500 0 5000 10000 15000 20000 25000 30000 Primary zone temperature ( o K) E m is si on s (g ra m s) NOxNOx COCO CO2CO2 500 600 700 800 900 1000 20 22 24 26 28 30 32 34 1.5 2 2.5 3 3.5 4 4.5 5 21.3 21.4 21.5 21.6 Gasifier temperature ( o C) U C O E ( N /k W h ) at d if f. g as if ie r te m p . UCOE at diff. gasifier temp.UCOE at diff. gasifier temp. Gasifier mass flow rate (kg/s) U C O E ( N /k W h ) at d if f. g as if ie r m as s fl ow UCOE at diff. gasifier mass flowUCOE at diff. gasifier mass flow 0.25 0.3 0.35 0.4 21.0 21.5 22.0 22.5 23.0 120000 140000 160000 180000 200000 220000 240000 Ammonia mass fraction in water U C O E ( N /k W h ) UCOEUCOE K a li n a T u rb in e P E C ( $ ) Kalina Turbine PECKalina Turbine PEC 0.250 0.300 0.350 0.400 0.50 1.00 1.50 2.00 Ammonia mass fraction in water T h er m o -e n v ir o n m en ta l p a ra m et er s ESIESI ETIETI EUIEUI 0.25 0.3 0.35 0.4 150 200 250 300 200 300 400 500 600 Ammonia mass fraction in water K a li n a t u rb in e o u tp u t (k W ) Kal turb. outputKal turb. output K a li n a e v a p o ra to r co o li n g r a te ( k W ) Kalina evap. coolingKalina evap. cooling FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 52 The total cost rate of the system and the cost rate due to environmental impact are presented in Eqs (28) and (29). The components of the optimization function, objective functions, constraints and key performance indices are depicted in Table 13. �̇�𝑇𝑜𝑡 = �̇�𝑓𝑢𝑒𝑙 + �̇�𝑒𝑛𝑣. + ∑ �̇�𝑘𝑘 (28) �̇�𝑒𝑛𝑣 = 𝐶𝑁𝑂𝑥 �̇�𝑁𝑂𝑥 + 𝐶𝐶𝑂2 �̇�𝐶𝑂2 + 𝐶𝐶𝑂�̇�𝐶𝑂 (29) Where the unit damage costs 𝐶𝑁𝑂𝑥 , 𝐶𝐶𝑂2 and 𝐶𝐶𝑂 are taken as 0.02186 $/kg, 6.863$/kg and 0.023 $/kg, respectively. The GA (genetic algorithm) was applied in the optimization due to its flexibility in simplifying multi-variable and multi- objective problems. In this analysis, Ninety groups of the Pareto-frontiers from the GA were described following the OBFs and the equivalent constraints. The 17th Pareto-front correspond to the optimum (𝜓) and minimum cost rate calculated at 45.32 % and 125.84 $/hr, separately. The corresponding parameters occur at a compression ratio (CR) of 8, with isentropic efficiencies of LPC, HPC, LPT, and HPT existing at 88%. Also, the intercooler exit temperature and the inlet temperature to the combustion chamber and reheater were calculated at 386.7K, 1140 K and 1240.3 K. The optimal 500 600 700 800 900 1000 5.100x10 6 5.150x10 6 5.200x10 6 5.250x10 6 5.300x10 6 5.350x10 6 1.5 2 2.5 3 3.5 4 4.5 5 5.320x10 6 5.325x10 6 5.330x10 6 5.335x10 6 5.340x10 6 5.345x10 6 5.350x10 6 5.355x10 6 Gasifier temperature ( o C) Sy st em to ta l c os t ( $) ( fr om b io m as s ga s. te m p. Total cost at varying gasifier temp.Total cost at varying gasifier temp. Gasifier mass flow rate (kg/s) Sy st em to ta l c os t ( $) ( fr om b io m as s m as s va ri at io n) Total cost at varying gasifier mass flowTotal cost at varying gasifier mass flow Table 13. Components of optimization functions and parameters Performance index Optimization function Decision variables Optimization constraints 𝐖𝐋𝐏𝐂 �̇�1𝑐𝑝 𝑇1 𝜂𝐿𝑃𝐶 [(𝑟𝑝) 𝑘 − 1] 𝜂𝐿𝑃𝐶 , 𝑟𝑝 0.80 ≤ 𝐿𝑃𝐶 ≤ 0.90 𝐖𝐇𝐏𝐂 �̇�3𝑐𝑝 𝑇3 𝜂𝐻𝑃𝐶 [(𝑟𝑝) 𝑘 − 1] 𝜂𝐿𝑃𝐶 , 𝑟𝑝 0.80 ≤ 𝐿𝑃𝐶 ≤ 0.90 𝐖𝐋𝐏𝐓 �̇�10𝑐𝑝𝑇10𝜂𝐿𝑃𝑇 |1 − 1 (𝑟𝑝) 𝑘| 𝜂𝐿𝑃𝐶 , 𝑟𝑝, 𝑇10 0.80 ≤ 𝐿𝑃𝐶 ≤ 0.9 8≤ 𝑟𝑝 ≤ 16,1150 ≤ 𝑇10 ≤ 1250 𝐖𝐇𝐏𝐓 �̇�7𝑐𝑝𝑇7𝜂𝐻𝑃𝑇 |1 − 1 (𝑟𝑝) 𝑘| 𝜂𝐿𝑃𝐶 , 𝑟𝑝, 𝑇7 0.80 ≤ 𝐿𝑃𝐶 ≤ 0.9, 8 ≤ 𝑟𝑝 ≤ 16, 1150 ≤ 𝑇7 ≤ 1250 𝐾 𝐖𝐊𝐚𝐥.𝐓𝐮𝐫𝐛 �̇�28|ℎ28 − ℎ29| + |�̇�28 − �̇�29|. |ℎ29 − ℎ33| 𝑃28, pressure at 𝑇28, ℎ28 435 ≤ 𝑇28 ≤ 439 K 𝐐𝐄𝐕𝐏𝟏 �̇�30|ℎ31 − ℎ32| 𝑇30 𝑇61, -3 and -1.5 OC 𝐕𝐏𝐠𝐞𝐧𝐞𝐫𝐚𝐭𝐨𝐫 �̇�12|ℎ12 − ℎ13| 𝑇12 270 ≤ 𝑇60 ≤ 282 𝐐𝐄𝐕𝐏𝟐 �̇�40|ℎ41 − ℎ40| 𝑇40 𝑇44, -5.8 and -1.5 OC �̇�𝐨𝐬𝐭,𝐓𝐨𝐭𝐚𝐥 �̇�𝑓𝑢𝑒𝑙 + �̇�𝑒𝑛𝑣. + ∑ �̇�𝑘 𝑘 Described parameters Figure 11. Effect of gasifier temperature and mass flow on system total cost FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55 53 inlet pressures of the Kalina system were obtained at 20 kPa. The specific emissions rate at the optimum operating conditions are calculated at 123.34, 2.87E-07 and 0.214 kg/ MWh for CO2, CO and NOx, respectively. The improvement potential of the environmental discharges is for CO2, 1.56 %, NOx, 4.33 % and CO, 3.65 %, with optimum hydrogen production. 5. Conclusion A Kalina-based multigeneration cycle with increased heat addition to the PEM electrolyzer for hydrogen and water production was performed. The results are summarised as follows: The multigeneration energy system has a net energy and exergy efficiency of 53.48 and 50.05 %, respectively. Additionally, the system has improved topping cycle efficiency by 19.03 and 2.58 %, respectively, from the original values of 34.45 and 47.47 %. At the cycle level, the gas turbine contributed up to 85.81 % of the ED. The combustion chamber and reheater contributed about 54.65 and 22.57 % of the total ED destructions. The system overall exergo- thermal index (ETI) stood at 1.713 with the gas turbine system alone the ETI was obtained as 2.106, which suggests a higher thermal impact on the environment without the addition of the lower cycles. The system has a hydrogen production rate of 0.1524 kg/h with cooling rate and COP calculated at 3498 kW and 4.304 respectively. The ESI for the system was relatively low, with a value of 0.5242. The low ESI arises from the large ED in the topping cycle, which contributed about 66 % of total system ED. The exergoeconomic result indicates a low average cost of energy from the gas turbine (0.836 $/GJ) compared to the Kalina subsystem (6.53 $/GJ) and vapour absorption system (3.24 $/GJ). Ethical issue The authors are aware of and comply with best practices in publication ethics, specifically with regard to authorship (avoidance of guest authorship), dual submission, manipulation of figures, competing interests, and compliance with policies on research ethics. 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Summary of the energy and exergy balances, as well as the exergy of fuel and product for the system Component Energy Balance Exergy Balance Exergy of Fuel Exergy of Product GT LPC �̇�1ℎ1 + �̇�𝐿𝑃𝐶 = �̇�2ℎ2 �̇�1 + �̇�𝐿𝑃𝐶 = �̇�2 + �̇�𝐷,𝐿𝑃𝐶 �̇�𝐿𝑃𝐶 �̇�2 − �̇�1 GT intercooler �̇�2ℎ2 + �̇�48ℎ48 = �̇�3ℎ3 + �̇�49ℎ49 �̇�2 + �̇�48 = �̇�3 + �̇�49 + �̇�𝐷, 𝐼𝑁𝑇 �̇�2 − �̇�3 �̇�49 − �̇�48 GT HPC �̇�3ℎ3 + �̇�𝐻𝑃𝐶 = �̇�4ℎ4 �̇�3 + �̇�𝐿𝑃𝐶 = �̇�4 + �̇�𝐷,𝐻𝑃𝐶 �̇�𝐻𝑃𝐶 �̇�4 − �̇�3 GT Hex �̇�4ℎ4 + �̇�11ℎ11 = �̇�5ℎ5 + �̇�12ℎ12 �̇�4 + �̇�11 = �̇�5 + �̇�12 + �̇�𝐷,𝐺𝑇 𝐻𝐸𝑋 �̇�11 − �̇�12 �̇�5 − �̇�4 GT CC �̇�6|𝐿𝐻𝑉6| + �̇�5ℎ5 = �̇�7ℎ7 �̇�5 + �̇�6 = �̇�7 + �̇�𝐷,𝐺𝑇 𝐶𝐶 �̇�5 + �̇�6 �̇�7 GT HPT �̇�7ℎ7 = �̇�8ℎ8 + �̇�𝐻𝑃𝑇 �̇�7 = �̇�8 + �̇�𝐻𝑃𝐶 + �̇�𝐿𝑃𝐶 +�̇�𝐷,𝐻𝑃𝑇 �̇�7 − �̇�8 �̇�𝐻𝑃𝐶 + �̇�𝐿𝑃𝐶 GT REH �̇�9|𝐿𝐻𝑉9| + �̇�8ℎ8 = �̇�10ℎ10 �̇�8 + �̇�9 = �̇�10 + �̇�𝐷,𝐺𝑇 𝑅𝐸𝐻 �̇�8 + �̇�9 �̇�10 GT LPT �̇�10ℎ10 = �̇�11ℎ11 + �̇�𝐿𝑃𝑇 �̇�10 = �̇�11 + �̇�𝐿𝑃𝑇 + �̇�𝐷,𝐿𝑃𝑇 �̇�10 − �̇�11 �̇�𝐿𝑃𝑇 Kal. Vap Gen. �̇�12ℎ12 + �̇�37ℎ37 = �̇�13ℎ13 + �̇�17ℎ17 �̇�12 + �̇�37 = �̇�13 + �̇�17 + �̇�𝐷,𝑉𝑎𝑝𝐺𝑒𝑛 �̇�12 − �̇�13 �̇�17 − �̇�37 Kal. Sep 1 �̇�17ℎ17 = �̇�18ℎ18 + �̇�22ℎ22 �̇�17 = �̇�18 + �̇�22 + �̇�𝐷,𝐾𝑎𝑙 𝑆1 �̇�17 �̇�18 + �̇�22 Kal. Valve 1 �̇�22ℎ22 = �̇�23ℎ23 �̇�22 = �̇�23 + �̇�𝐷,𝐾𝑎𝑙 𝑉1 �̇�22 �̇�23 Kal. Valve 2 �̇�21ℎ21 = �̇�24ℎ24 �̇�21 = �̇�24 + �̇�𝐷,𝐾𝑎𝑙 𝑉2 �̇�21 �̇�24 Kal. Turb. �̇�18ℎ18 = �̇�20ℎ20 + �̇�18𝑊𝑇𝐾𝑎𝑙 + �̇�34𝑊𝑃1 + �̇�42𝑊𝑃2 �̇�18 = �̇�20 + �̇�𝑊𝑇𝐾𝑎𝑙 + �̇�𝑊𝑃1 + �̇�𝑊𝑃2 + �̇�𝐷𝑇𝐾𝑎𝑙 �̇�18 − �̇�20 �̇�𝑊𝑇𝐾𝑎𝑙 + �̇�𝑊𝑃1 + �̇�𝑊𝑃2 Kal. Sep 2 �̇�20ℎ20 = �̇�28ℎ28 + �̇�21ℎ21 �̇�20 = �̇�28 + �̇�21 + �̇�𝐷,𝐾𝑎𝑙 𝑆2 �̇�20 �̇�28 + �̇�21 Kal. CND 1 �̇�28ℎ28 + �̇�59ℎ59 = �̇�29ℎ29 + �̇�60ℎ60 �̇�28 + �̇�59 = �̇�29 + �̇�60 + �̇�𝐷,𝐶𝑁𝐷1 �̇�28 − �̇�29 �̇�60 − �̇�59 Kal. Valve 3 �̇�28ℎ28 = �̇�29ℎ29 �̇�28 = �̇�29 + �̇�𝐷,𝐾𝑎𝑙 𝑉3 �̇�28 �̇�29 Kal. Evap 1 �̇�12ℎ12 + �̇�37ℎ37 = �̇�13ℎ13 + �̇�17ℎ17 �̇�12 + �̇�37 = �̇�13 + �̇�17 + �̇�𝐷,𝑉.𝐺𝐸𝑁 �̇�12 − �̇�13 �̇�17 − �̇�37 Kal. HEX 1 �̇�26ℎ26 + �̇�36ℎ36 = �̇�27ℎ27 + �̇�37ℎ37 �̇�26 + �̇�36 = �̇�27 + �̇�37 + �̇�𝐷,𝐾𝑎𝑙 𝐻𝑋𝐸1 �̇�26 − �̇�27 �̇�37 − �̇�36 Kal. HEX 2 �̇�32ℎ32 + �̇�35ℎ35 = �̇�33ℎ33 + �̇�36ℎ36 �̇�32 + �̇�35 = �̇�33 + �̇�36 + �̇�𝐷,𝐾𝑎𝑙 𝐻𝐸𝑋2 �̇�32 − �̇�33 �̇�36 − �̇�35 Kal. CND 2 �̇�33ℎ33 + �̇�57ℎ57 = �̇�34ℎ34 + �̇�58ℎ58 �̇�33 + �̇�57 = �̇�34 + �̇�58 + �̇�𝐷,𝐾𝐴𝐿 𝐶𝑁𝐷2 �̇�33 − �̇�34 �̇�58 − �̇�57 Kal. Pump 1 �̇�34ℎ34 + �̇�34𝑊𝑃1 = �̇�35ℎ35 �̇�34 + �̇�𝑊𝑃1 = �̇�35 + �̇�𝐷,𝑃1 �̇�𝑊𝑃1 �̇�35 − �̇�34 VAS desorber �̇�25ℎ25 + �̇�44ℎ44 = �̇�26ℎ26 + �̇�38ℎ38 + �̇�45ℎ45 �̇�25 + �̇�44 = �̇�26 + �̇�38 + �̇�45 + �̇�𝐷,𝐷𝐸𝑆𝐵 �̇�25 − �̇�26 + �̇�44 �̇�38 − �̇�45 VAS HEX 3 �̇�43ℎ43 + �̇�45ℎ45 = �̇�44ℎ44 + �̇�46ℎ46 �̇�43 + �̇�45 = �̇�44 + �̇�46 + �̇�𝐷,𝑉𝐴𝑆 𝐻𝐸𝑋3 �̇�45 − �̇�46 �̇�44 − �̇�43 VAS Valve 5 �̇�46ℎ46 = �̇�47ℎ47 �̇�46 = �̇�47 + �̇�𝐷,𝑉𝐴𝑆 𝑉5 �̇�46 �̇�47 VAS Pump 2 �̇�42ℎ42 + �̇�42𝑊𝑃2 = �̇�43ℎ43 �̇�42 + �̇�𝑊𝑃2 = �̇�43 + �̇�𝐷,𝑃2 �̇�𝑊𝑃2 �̇�43 − �̇�42 VAS Absorber �̇�41ℎ41 + �̇�47ℎ47 + �̇�65ℎ65 = �̇�42ℎ42 + �̇�66ℎ66 �̇�41 + �̇�47 + �̇�65 = �̇�42 + �̇�66 + �̇�𝐷,𝐴𝐵𝑆𝐵 �̇�41 + �̇�47 �̇�66 − �̇�65 + �̇�42 VAS EVP 2 �̇�40ℎ40 + �̇�63ℎ63 = �̇�41ℎ41 + �̇�64ℎ64 �̇�40 + �̇�63 = �̇�41 + �̇�64 + �̇�𝐷,𝑉𝐴𝑆 𝐸𝑉𝑃2 �̇�63 − �̇�64 �̇�41 − �̇�40 VAS Valve 4 �̇�39ℎ39 = �̇�40ℎ40 �̇�39 = �̇�40 + �̇�𝐷,𝑉𝐴𝑆 𝑉4 �̇�39 �̇�40 VAS CND 3 �̇�38ℎ38 + �̇�61ℎ61 = �̇�39ℎ39 + �̇�62ℎ62 �̇�38 + �̇�61 = �̇�39 + �̇�62 + �̇�𝐷,𝑉𝐴𝑆 𝐶𝑁𝐷3 �̇�38 − �̇�39 �̇�62 − �̇�61 Water heater �̇�13ℎ13 + �̇�15ℎ15 = �̇�14ℎ14 + �̇�16ℎ16 �̇�13 + �̇�15 = �̇�14 + �̇�16 + �̇�𝐷,𝐻𝐸𝐴𝑇𝐸𝑅 �̇�13 − �̇�14 �̇�16 − �̇�15 PEM Electr. �̇�52ℎ52 + �̇�19ℎ19 = �̇�53ℎ53 + �̇�54ℎ54 �̇�52 + �̇�19 = �̇�53 + �̇�54 + �̇�𝐷,𝐸𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑠𝑒𝑟 �̇�52 + �̇�19 �̇�53 + �̇�54 PEM HEX �̇�58ℎ58 + �̇�60ℎ60 + �̇�50ℎ50 = �̇�51ℎ51 + �̇�69ℎ69 �̇�58 + �̇�60 + �̇�50 = �̇�51 + �̇�69 + �̇�𝐷,𝑃𝐸𝑀 𝐻𝐸𝑋 �̇�58 + �̇�60 − �̇�69 �̇�51 − �̇�50 PEM O2 separator �̇�54ℎ54 = �̇�55ℎ55 + �̇�56ℎ56 �̇�54 = �̇�55 + �̇�56 + �̇�𝐷,𝑂𝑥𝑦.𝑠𝑒𝑝 �̇�54 �̇�55 + �̇�56 FI Abam et al. /Future Technology February 2024| Volume 03 | Issue 01 | Pages 40-55