Optimized Design and Testing of Enhanced Heat Transfer Secondary Micro-Channels on the Surface of Fuel Cell Bipolar Plate Flow Channels

Air-cooled proton exchange membrane fuel cells (PEMFCs) offer advantages such as light weight, compact size, and simple structure, and have been widely used in fields such as portable electronics, drones, and new energy electric vehicles. However, due to the influence of air convective cooling efficiency, air-cooled PEMFC can only operate at low power to avoid overheating. To improve the air-cooling efficiency and the maximum output power of PEMFCs, a new enhanced cooling structure has been proposed, which adds secondary micro-channels on the surface of the original bipolar plate flow channels. Thermal simulation analysis was conducted for flow channels with and without an array of micro-channels on the surface. Through orthogonal simulation experiments, the optimal geometric parameters for the secondary micro-channels were determined. The simulation results show that for flow channels with optimized secondary micro-channels, the maximum temperature at the center plane of the MEA is reduced by approximately 10 °C, the thermal resistance of heat transfer in the channel decreases by about 21.2%, and the experimental results on heat transfer in the channel indicate that the maximum heat flux density increases by approximately 22.5%. Finally, performance tests were conducted on air-cooled PEMFC stacks with and without enhanced cooling secondary micro-channels. The test results show that the fuel cell stack with enhanced cooling secondary micro-channels exhibits a temperature reduction of approximately 14 °C at a current density of 0.5 A/cm², a maximum output power increase of about 27%, and improved voltage uniformity across individual cells, demonstrating the effectiveness of the enhanced cooling secondary micro-channel structure.