Modeling of an anode supported solid oxide fuel cell focusing on thermal stresses

Abstract

A mechanical failure of a single component is sufficient to cause a solid oxide fuel cell (SOFC) breakdown. As an unfavorable issue for interfering the stable operation of SOFCs, thermal stress stemming from temperature gradient and mechanical mismatch can result in crack damage. Therefore, it is strongly significant to clarify the relationship of mechanical properties of the cell materials with distribution of the stress by taking into account the electrochemical reactions. A complete three-dimensional model for a planar anode-supported SOFC has been proposed and established in this study, which includes governing equations for momentum, gas-phase species, heat, electron and ion transport. The thermal gradients caused by the electrochemical reactions and heat transport processes of the counterflow leading to a maximum thermal stress is slightly larger than that is induced by the coflow. The influence of mechanical mismatch is analyzed and the results indicate that the strength of stress at two sides of a cell tends to be enlarged under fixed constraint conditions. Furthermore, the functional buffer layers can affect the stress between different components and inhibit the extent of degradation. This investigation is expected to offer a path to improve the matches of SOFC components and optimize the stack design.