Efficiency Enhancement on Solid Oxide Fuel Cell system with anode off-gas recycle by evaluating entropy and exergy change

The aim of this paper is to enhance the efficiency of the Solid Oxide Fuel Cell (SOFC) system through various system designs and parameters. To evaluate the effects of design configurations, the impact of high-temperature/low-temperature anode off-gas recycle (HT/LT-AGR) on system performance was investigated by calculating the entropy using the second law of thermodynamics. By analyzing the system with different AGR designs and considering the increasing entropy of heat components in the SOFC system, the efficiency calculations can be more practical and accurate. In this study, the working efficiency of the SOFC system with HT-AGR is 56.215 %, which is 4.7 % higher than with LT-AGR. The results show that the heat exchanger (HEX) experiences the largest increasing entropy during the power generation process due to the significant temperature difference. At the end of this project, a CO2 reformer will be used to optimize the system, decreasing the mole rate of CO2 and CH4 while increasing the mole rate of H2. Based on the simulation results, using a CO2 reformer can increase the mole rate of H2 by 3 %, improving the system efficiency up to 56.97 %. • According to the power generation results for the SOFC system, the loop of the SOFC system with HT-AGR can achieve the highest power output. • This is because the operating temperature of the heat components can be maintained when the parameter of RR is increased. • Comparing the loop of the SOFC system with HT- and LT-AGR, the temperature of the stack in HT-AGR is 15K higher than in LT-AGR, resulting in a power generation for HT-AGR that is 600W higher than LT-AGR. • The exergy of the system with HT-AGR is 8 % higher than that of LT-AGR, which is because HT-AGR can maintain the operating temperature of the heat components.