Parametric Study of Operating Conditions on Performances of a Solid Oxide Electrolysis Cell

The operating conditions greatly affect the electrolysis performance and temperature distribution of solid oxide electrolysis cells (SOECs). However, the temperature distribution in a cell is hard to determine by experiments due to the limitations of in-situ measurement methods. In this study, an electrochemical-flow-thermal coupling numerical cell model is established and verified by both current-voltage curves and electrochemical impedance spectroscopy (EIS) results. The electrolysis performance and temperature distribution under different working conditions are numerically analyzed, including operating temperature, steam and hydrogen partial pressures in the fuel gas, inlet flow rate and inlet temperature of fuel gas. The results show that the electrolysis performance improves with increasing operating temperature. Increasing steam partial pressure improves electrolysis performance and temperature distribution uniformity, but decreases steam conversion rate. An inappropriately low hydrogen partial pressure reduces the diffusion ability of fuel gas mixture and increases concentration impedance. Although increasing the flow rate of fuel gas improves electrolysis performance, it also reduces temperature distribution uniformity. A lower airflow rate benefits temperature distribution uniformity. The inlet temperature of fuel gas has little influence on electrolysis performance. In order to obtain a more uniform temperature distribution, it is more important to preheat the air than the fuel gas.