Numerical study on effects of CH4–CO2 internal reforming on electrochemical performance and carbon deposition of solid oxide fuel cell

Abstract

CH4–CO2 fueled solid oxide fuel cells (SOFCs) are the high-efficiency and low-carbon power generation technology. However, carbon deposition severely hinders its application. Here, the numerical model considering the complex anode CH4 internal reforming reactions, H2 electrochemical reaction, gas diffusion and charge transfer of SOFC using CH4–CO2 fuel has been established. The CH4–CO2 internal reforming and electrochemical reactions of SOFC under different CO2/CH4 ratios and temperatures are studied to reveal the optimal operating conditions. The distributions of different reaction rates, gas components and carbon deposition activity at the anode are analyzed. The results show that the increase of CO2 concentration can decrease the carbon activity but also cause the decrease of electrochemical performance. It is found that the good comprehensive performances including power density, carbon activity and methane conversion rate can be achieved under the CO2/CH4 molar ratio of 1. The thermodynamic calculation of three different methane reforming modes shows that CH4–CO2 reforming leads to the greatest carbon deposition risk compared with CH4–H2O and CH4–O2 reforming, implying the importance of anti-carbon for CH4–CO2 fueled SOFC.