Three-dimensional multi-phase numerical study for the effect of coolant flow field designs on water and thermal management for the large-scale PEMFCs

The multi-phase numerical study is performed for the large-scale proton exchange membrane fuel cells (PEMFCs) regarding coolant flow field design. In this study, three coolant flow fields were designed to explore the effect of different temperature distributions on the water management of the PEMFCs. The numerical results show that increasing the temperature gradient along the gas flow direction and improving the temperature uniformity perpendicular to the gas flow direction enhances PEMFC performance and makes the liquid water distribution in the gas diffusion layers more reasonable. The co-flow for the cathode gas stream and the coolant flow is beneficial to raise the temperature along the cathode gas flow direction and reduce the risk of flooding near the cathode outlet. Then, it is noted that the coolant flow field design is not necessary to keep the temperature absolutely uniform for the PEMFCs. Although increasing the coolant volume flow rate will reduce the IUT, it dramatically increases the risk of flooding near the cathode outlet. Therefore, the moderate volume flow rate is preferred. Finally, the effect of the coolant manifold on the volume flow rate uniformity in the coolant channels is investigated, and it is found that reducing the number of coolant channels is the best strategy to improve volume flow rate uniformity and thermal management performance.