Construction of a transient multi-physics model of solid oxide fuel cell fed by biomass syngas considering the carbon deposition and temperature effect

Abstract

Carbon deposition is a thorny issue for the SOFC fueled by low carbon hydrocarbons such as biomass syngas. Moreover, long-term large temperature gradients would reduce SOFC durability. Regarding these two issues, a two dimensional transient multi-physical model considering carbon deposition and temperature effect is developed for SOFC in this work. Typically due to the carbon deposition, the SOFC anode porosity decreases from 0.5 to 0.267, and the reaction activity decreases from 1.0 to about 0.45 after running 140 day. Accordingly, the current density decreases by 1.6 % at t = 42 d and 6% at t = 140 d, which indicates the damage of SOFC durability compared to the durability target (1%/1000 h) of commercial SOFC. The maximum temperature difference of the cell is predicted to be about 106 °C. It was found that the carbon deposition and large temperature gradient are closely related to the operating parameters. With the increase of operating voltage from 0.4 V to 0.8 V, the porosity and reaction activity respectively increase by 50% and 55%, and the maximum temperature difference is reduced from 150 °C to 16 °C after running 140 day. The increase of the inlet temperature could improve the overall temperature and decrease the porosity. Besides, the reduction in the ratio of CH4 to H2O helps to suppress carbon deposition, thus to improving the performance.