Quantitative study of the effect of center tube geometric parameters in SOFC stack based on a three-dimensional model with multi-physics fields

Solid oxide fuel cells (SOFCs) can provide stable and dispatchable green electricity for energy systems with high renewable integration. Tubular SOFCs have emerged as a highly promising configuration for high-power generation in industrial applications, primarily due to their advantages such as simplified sealing, excellent thermal stability, and high mechanical strength. However, the immaturity of tubular SOFC manufacturing processes results in an unclear relationship between structural/operating conditions and overall cell performance. To advance the structural design and mechanistic understanding of tubular SOFCs, this study developed a comprehensive three-dimensional single-tube anode-supported SOFC model by integrating computational fluid dynamics (CFD) with electrochemical reaction kinetics. Factors influencing the output performance were examined through orthogonal experimental design and parametric sensitivity analysis. The results indicated that the temperature impact contributes approximately 58.4% to the peak power density of the cell by regulating the balance between electrochemical reaction activity and mass transport, followed by oxygen electrode thickness (37.2%), hydrogen electrode porosity (2.8%) and hydrogen electrode thickness (0.9%). The electrode structural design is typically limited by the oxygen electrode. The oxygen domain geometry dictates tubular stack scalability, with a recommended volumetric ratio of fuel cell to oxygen domain not exceeding 71.2%. Given manufacturing constraints, hydrogen electrode thickness and porosity should be maintained within established operational bounds to ensure baseline electrochemical performance. This paper summarizes operating conditions and structural design patterns for tubular SOFCs, while elucidating an inherent design constraint that demonstrates extensibility to stack-level tube arrangement guidance.