Investigating the effects of operating conditions and flow field structures on the performance and thermal stress for solid oxide electrolysis cells

This study investigates thermo fluid coupling mechanisms governing temperature distribution and thermal stress evolution in Solid Oxide Electrolyzer Cells (SOEC) under varying operating conditions. A multiphysics model integrating electrochemistry, gas flow and diffusion, heat transfer, and thermo mechanical response is developed to examine the effects of operating temperature, steam ratio, air flow rate, and flow configuration on electrolysis performance, internal temperature fields, and stress distributions. The numerical model is validated against the experimental data of Tu et al., showing a maximum polarization curve deviation of 9.84%. Results show that increasing operating temperature from 973 K to 1073 K raises current density by approximately 31.7%, while increasing peak temperature by about 11.5% and electrolyte tensile stress from 439.9 MPa to 518.6 MPa. Increasing the cathode side steam fraction from 60% to 90% improves current density by about 11.7%, with minor increases in peak temperature below 1% and stress near 1%. Increasing the anode side air flow rate from 10 sccm to 50 sccm reduces temperature spread and decreases maximum electrolyte tensile stress by approximately 7%. These results highlight the role of thermo fluid interactions in temperature gradient development and thermal stress evolution in SOECs.