A novel heat pipe bipolar plate for proton exchange membrane fuel cells

The proton exchange membrane fuel cell (PEMFC) system is appealing for electric vertical takeoff and landing vehicles, but its power density needs to be improved for practical applications. Ultra-thin flat heat pipes (UTFHP) have potential to improve the power density of PEMFC system by reducing the complexity of thermal management subsystem, but the large stack volume have hindered their wider adoption. This paper proposes a novel design of heat pipe bipolar plates (HPBP) to reduce the volume of heat pipe cooled stack. A three-dimensional numerical model has been developed for analyzing and comparing the performance of the PEMFCs with HPBP and UTFHP. Compared to the UTFHP, the HPBP could significantly reduce the stack volume while maintaining comparable maximum heat load. It can also significantly reduce the maximum temperature and improve the temperature uniformity over the cathode catalyst layer middle plane. The operating range and the peak power density of the PEMFC cooled by HPBP are larger than that cooled by UTFHP. We also performed system-level evaluations and found that the PEMFC system with HPBP cooling exhibits 22% and 36% higher gravimetric and volumetric power densities than that with conventional liquid cooling, respectively.