Feasibility study of liquid metal-based thermal management for solid oxide electrolyzer cell (SOEC)

Abstract

Solid Oxide Electrolyzer Cells (SOECs) operate at elevated temperatures (700 to 1000 °C), leading to thermal management challenges due to significant temperature gradients that affect durability and performance. This study investigates the feasibility of using liquid metals including tin (Sn), sodium (Na), gallium (Ga), lead bismuth eutectic (LBE), and lithium (Li) as cooling fluids, in comparison to conventional air cooling. A 3D SOEC model coupled with electrochemical reactions is developed to assess maximum temperature, temperature distribution, and the Temperature Uniformity Index (TUI). Results show that liquid metals significantly reduce thermal gradients, with Ga and LBE achieving the lowest gradients of 3 K and 3.5 K, respectively, compared to air cooling at 7.5 K. Gallium is selected for further analysis to optimise cooling conditions. Increasing the Reynolds number from 900 to 8960 improves convective heat transfer (Nusselt number increases from 3.5 to 3.75) but raises pumping power by 323 percent. Lowering the middle cooling channel temperature from 1063 K to 1043 K further improves temperature uniformity and reduces peak temperatures. Among all strategies, parallel flow at 1043 K and 0.4 m/s achieves the best balance between thermal performance and energy consumption. Overall, gallium emerges as a highly effective cooling fluid for enhancing SOEC thermal management and long term reliability.