Thermal uniformity enhancement of solid oxide fuel cell stacks using alternated air flows

Abstract

Solid oxide fuel cell (SOFC) is a promising energy conversion device with high efficiency and low emissions. Among the various types, the planar SOFC is widely used due to its compactness and high power density. However, when multiple cells are vertically stacked, thermal non-uniformity inevitably occurs, leading to mechanical failures and reduced durability. To overcome this issue, effective thermal management at the stack level is essential. This study proposes a novel SOFC stack design that introduces two alternated air flows: one passing through the odd-numbered layers and the other through the even-numbered layers with a counter-flow arrangement. Based on the position of the inlet and outlet ports, four configurations with different air flow patterns are developed: U-type, H-type, X-type, and Z-type flows. Thermal uniformity is analyzed using threedimensional computational fluid dynamics for a commercial-scale SOFC stack composed of 30 unit cells. Simulation results show that all four proposed designs significantly improve thermal uniformity in the planar direction compared to the conventional design, decreasing the planar temperature gradient by up to 60.6%. Furthermore, the H-type and Z-type flow designs, which distribute the air inlets separately at the top and bottom of the stack, reduce the vertical temperature gradient by 50.8% and 45.7%, respectively. These findings provide new design strategies to enhance thermal uniformity in SOFC stacks by mitigating temperature imbalances in both planar and vertical directions.