Transient thermomechanical analysis of a solid oxide fuel cell stack based on 3D multiphysical field model

The transient thermal behavior and thermomechanical response of solid oxide fuel cells (SOFCs) will endanger the structural reliability of these cells. We use, in this study, a comprehensive three-dimensional (3D) multiphysical field model to analyze the effects of flow configuration and transient stress response on cell stacks. The nonlinear material behavior extracted from the experiments is implemented, and the effects of heat flux boundary conditions and configurations are investigated. Results show that radiation greatly affects the temperature distribution in the stack. The counterflow with the highest temperature in the middle part has a higher temperature difference than the co-flow with the highest temperature in the outlet zone. The maximum temperature differences of three cooling rates are rapidly decreased during the first 60 min in the shutdown stage and then become steady. A maximum Mises stress with the maximum plastic strain is observed in the corners of the manifold. Elastic and thermal strains co-dominate the stress in steady operation, whereas thermal strain dominates the stress during the cooling process. The maximum Mises stress decreases initially and then increases continually in the shutdown stage. The front and rear edges and the lateral edges of the electrolytes are subjected to the high first-principle stress in steady operation, but the stresses move to the front and rear edges in the shutdown stage.