Analysis on thermal stress of a planar solid oxide fuel cell

A thermal stress finite element model for a planar solid oxide fuel cell (SOFC) was established to study the structural performance of SOFC and improve its reliability. Numerical simulations for both co-flow and counter-flow planar SOFCs were performed by coupling the SOFC electrochemical model with the Naive-Stokes equations. The distribution characteristics of temperature, electric potential and current density were analyzed based on the simulation results. The distribution characteristics of thermal stress in the SOFC positive electrode-electrolyte-negative electrode were investigated using the developed SOFC thermal stress finite-element model. The simulation results indicate that the temperature gradient near the fuel entrance for the counter-flow pattern is much greater than that for the co-flow pattern. The thermal stress is mainly attributed to the mismatches of coefficients of thermal expansion between different materials and is closely related to the temperature gradient and distribution. The thermal stress may lead to cracks and destroy the SOFC structure. This research provides theoretical basis for design and optimization of the SOFC cell and stack.