Numerical study on carbon deposition of SOFC with unsteady state variation of porosity

In order to research the failure mechanism of Solid Oxide Fuel Cell (SOFC), an unsteady state two-dimensional model that considers the carbon deposition is presented. Navier–Stokes (N–S) equations, heat transfer equation, mass transfer equation, electron and ion transport equation are solved by COMSOL 3.5. In the numerical model, with the operating temperature at 800 °C, gas phase chemical reaction kinetics is used to predict the carbon deposition molar mass. Furthermore, the unsteady state variation of anodic porosity and the electrical conductivity that caused by carbon deposition is taken into account. From the numerical results, it can be found that the effect of the variation of anodic porosity on SOFC electronic performance is about 7%. Therefore, it is necessary to consider the variation of anodic porosity when come up against carbon deposition problems of SOFC. The increased inlet water/methane ratio could eliminate carbon deposition, but the current density would decline dramatically.

► Unsteady two-dimensional SOFC model considering carbon deposition is presented. ► Gas phase chemical reaction kinetics is used to predict carbon deposition molar mass. ► Unsteady variation of anodic porosity and electrical conductivity is considered. ► It is necessary to consider the variation of anodic porosity for SOFCs.