||p‒SOFC is an appropriate fuel cell type to be applied in the power generating system. p‒SOFC is combined with MGT and CHP to utilize the hydrogen and oxygen unreacted from the stack. Some parameters are fixed by using Matlab / Simulink such as 50 cells, membrane area of 0.1 m2. Furthermore, three cases, cases 1, 2, and 3, are analyzed, and the best case, case 2, is installed with anode and cathode recycling, to increase system performance. Some parameters are varied to be analyzed such as fuel utilization, steam to fuel, air stoichiometry, and fuel stoichiometry. In case comparison, case 2 shows the better performance than case 1 and case 3, where installation of a fuel heat exchanger before reformer is highly recommended in order to increase the reaction rate in reformer. Operating temperature in each component in every case is difference. Case 1 produces higher hydrogen production than case 2 and case 3 due to heat used to heat the reformer in case 1 is higher than other cases, however, the power in case 1 is lower than case 2 due to heat output of reformer in case 1 is lower than other cases. Furthermore, the result of exergy analysis shows that case 2 has lower exergy destruction (5.193 kW) than case 1 (6.170 kW) and case 3 (6.635 kW), where installation of heat exchanger can decrease exergy destruction around 0.977 kW. For parameters analysis results: First, the result of fuel utilization shows that increasing fuel utilization from 60 % to 90 % can increase p‒SOFC power output from 3 kW to 3.9 kW due to stack consumes more fuel, however, MGT power output decreases from 1.9 kW to 1.4 kW due to decreasing fuel unreacted in the combustor. The efficiency of p‒SOFC, power system, and CHP increases from 45 % to 58 %, 66 % to 73 %, and 72 % to 79 %, respectively. Second, increasing steam to fuel from 3 to 3.5 can increase p‒SOFC power output from 3.7 kW to 3.8 kW due to increasing hydrogen production from 28.7 mmol/s to 29.1 mmol/s. However, increasing steam to fuel ratio from 3.5 to 5 can decrease p‒SOFC power output from 3.8 kW to 3.4 kW due to fuel dilution in the reformer, and decreasing hydrogen production from 29 mmol/s to 26.9 mmol/s. The efficiency of p‒SOFC, power system, and CHP decreases from 57 % to 52 %, from 72 % to 68 %, and 79 % to 74 %, respectively. Third, increasing air stoichiometry from 2 to 4 can decrease p‒SOFC power output from 3.9 kW to 3.1 kW due to decreasing hydrogen production from 27.6 mmol/s to 27.2 mmol/s. Consequently, p‒SOFC electrical current decreases from 95.92 A to 94.54 A. In another hand, MGT power output increases from 1.4 kW to 2.1 kW due to increasing mass flow rate from 100 mmol/s to 150 mmol/s, however, compressor power also increases from 0.5 kW to 1 kW. The efficiency of p‒SOFC, power system, and CHP decreases from 58 % to 47 %, from 73 % to 65 %, and from 79 % to 71 %, respectively. Fourth, increasing fuel stoichiometry from 1 to 1.3 can increase p‒SOFC power out from 3 kW to 4 kW due to increasing hydrogen production from 22 mmol/s to 33 mmol/s, where there is an increase significantly of p‒SOFC power output when fuel stoichiometry is set from 1.0 to 1.2, and p‒SOFC efficiency increases from 53 % to 58 %. However, fuel stoichiometry from 1.2 to 1.3 can decrease p‒SOFC efficiency from 58 % to 54 % due to fuel is not balance with water in the reformer. Consequently, hydrogen production only increases slightly. Briefly, the optimum parameters are fuel utilization of 83 %, steam to fuel ratio of 3, air stoichiometry of 2, and fuel stoichiometry of 1.2. The last, Combination between cathode recycling and anode recycling shows promising performance, where power system efficiency increases up to 6.81 % due to increasing hydrogen production, increasing operating temperature in each component, and decreasing compressor work.|
Keywords: air stoichiometry, CHP, ethanol, fuel stoichiometry, fuel utilization, MGT, p‒SOFC, Recycling, and steam to fuel
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