Numerical studies on thermal performance of a novel edge cooling design in fuel cell stacks for unmanned aerial vehicles
Abstract
Air-cooled proton exchange membrane fuel cells (PEMFCs) are promising power sources for unmanned aerial vehicles because of their high specific energy and relatively simple balance-of-plant requirements. However, maintaining an acceptable and uniform stack temperature with low auxiliary power remains challenging. This study investigates a periodic edge-cooling configuration in which multiple fans are arranged at equal intervals along the long sides of a PEMFC stack. A three-dimensional steady conjugate heat-transfer model was developed to evaluate five heat fluxes, ranging from 2,400 to 3,600 W m −2 , and five fan spacings of 20–60 mm. For each of the 25 cases, the inlet velocity was iteratively adjusted until the maximum active-area temperature satisfied 358.15 ± 0.1 K. The effects of fan spacing and heat flux on the active-area temperature difference, airflow requirement, pressure drop, and representative-unit airflow hydraulic power were then analyzed. The results show that increasing heat flux requires a higher inlet velocity and increases both the pressure drop and temperature nonuniformity. As the fan spacing increases, the required airflow hydraulic power first decreases and then increases because of the competing effects of outlet-area enlargement, flow-path extension, and increased airflow demand. A second-order response-surface model fitted to the Computational Fluid Dynamics (CFD) results indicates a candidate low-airflow-power spacing region of approximately 38–40 mm over the investigated heat-flux range. This candidate spacing range is specific to the ideal periodic geometry and operating conditions investigated here. Because the full three-dimensional model has not been supported by a formal mesh-convergence study or independent experimental validation, the results should be interpreted as preliminary comparative design guidance rather than validated full-stack predictions.