Comparative Numerical Study on Flow Characteristics of 4 × 1 kW SOFC Stacks with U-Type and Z-Type Connection Configurations

In this study, a high-fidelity, full-scale three-dimensional Computational Fluid Dynamics (CFD) model was developed to analyze the effects of U-type and Z-type interconnection configurations on flow and distribution uniformity within a 4 × 1 kW planar solid oxide fuel cell (SOFC) stack composed of 40 unit cells. Mesh independence was verified using the Richardson extrapolation method. The results reveal that on the anode (fuel inlet) side, the Z-type configuration exhibits significantly better flow and pressure uniformity than the U-type configuration and shows low sensitivity to variations in fuel utilization (Uf = 0.3–0.8), maintaining stable flow distribution under different conditions. On the cathode (air inlet) side, however, the U-type configuration demonstrates superior flow stability at an air utilization rate of 0.3. Therefore, it is recommended to employ the Z-type configuration for the anode and the U-type configuration for the cathode to achieve more uniform gas distribution and enhanced operational stability. These findings provide valuable insights for optimizing the design and operation of solid oxide fuel cells (SOFCs) and offer guidance for the development of more efficient fuel cell systems.