Numerical simulation and analysis of the thermal stresses of a planar solid oxide electrolysis cell

Hydrogen production using solid oxide electrolysis cells (SOECs) is a highly efficient and low-carbon pathway to generate high purity hydrogen. However, high working temperatures may result in high thermal stress due to a mismatch in the coefficient of thermal expansion (CTE) between components with a nonuniform temperature distribution. Serious stress concentration may lead to structural failure of the SOEC stack. Hence, this work investigated the thermal stress of SOECs through a three-dimensional planar SOEC unit model. A stress analysis method was proposed via a multi-physics coupling model of SOECs using Comsol Multiphysics software. The impacts of voltage, flow direction, water mole fraction, and operating pressure on the thermal stress were evaluated. Numerical results show that the highest maximum principal stress is located in the electrolyte in the SOEC unit. Raising the water mole fraction and the CTE of the electrolyte could reduce the thermal stress if the voltage is below the thermoneutral voltage.