Multi-physicochemical modeling of direct methane fueled solid oxide fuel cells

Both H2-H2O and CO-CO2 electro-oxidation processes are considered in direct methane fueled SOFC model and incorporated into the comprehensive couplings between multi bulk transport processes, diffusion processes, surface chemical processes and the cell polarization performance. The model is validated using the experimental data of polarization performance at 600 °C, 650 °C and 700 °C respectively. Upon the model validation, extensive simulations are carried out to elucidate the complicated interaction mechanisms with emphasis on surface reaction processes and surface adsorbates under SOFC operating conditions. Results show that the surface reactions of methane are strongly dependent on the cell operating conditions and increase with increasing the operating temperature and cell current. The bulk gas species and surface adsorbates show different degree of sensitivities to cell operating conditions. Surface carbon deposition can be mitigated through increasing the operating temperature, the cell operating current, and the exchange current of electrodes as well as suitable increasing H2O content in the fuel. Surface carbon deposition may also be mitigated through suitable reducing the content of CH4, CO, and/or CO2 in the fuel.