Optimization of gas distribution structure for a kW-class cross-flow SOFC stack based on 3D multiphysics simulation

Abstract

The efficient and stable operation of solid oxide fuel cell (SOFC) stacks heavily depends on the spatial uniformity of the internal electrochemical and thermal fields. The gas distribution structure of an SOFC stack governs the flow and distribution of fuel and air within the stack, thereby influencing the temperature, species distribution, and overall power output of each individual cell. This study uses multi-physics coupled simulations to investigate the flow field, thermal gradient, species distribution, and power output of an SOFC stack under various gas distribution designs. To improve the flow uniformity of the conventional central gas distribution structure, this study proposes three approaches: opposite corner end gas distribution (OCD), expanded gas distribution chamber for direct distribution (ECD), and a diverging main gas channel design, which are systematically evaluated and compared. The computational results show that the OCD and ECD schemes improve the anode-side flow uniformity by 4.34% and 6.39%, respectively, while increasing the stack output power and slightly reducing the maximum temperature gradient. These findings validate the key role of adjusting the geometric configuration of the gas distribution chamber in performance enhancement. Furthermore, the diverging main gas channel design (with an optimal diverging angle of 20°) maintains a reasonable flow velocity at the inlet section and a relatively high static pressure in the mid-downstream region, thereby increasing the anode-side flow uniformity by 4.71%, significantly reducing the inlet flow difference among layers, and also slightly decreasing the maximum temperature gradient. The above results provide a strong design basis and technical support for the development of high-efficiency, long-life SOFC stacks.