Numerical simulation of holomorphic microscopic metal foam as cathode flow field in proton exchange membrane fuel cells

An enhanced flow field significantly improves reactant transfer and proton exchange membrane fuel cells (PEMFCs) performance. Metal foams with high porosity and electrical conductivity are promising flow field structures. This study aims to investigate the effect of metal foam porosity and pore density on PEMFC performance. A three-dimensional multi-physics PEMFC model with holomorphic microscopic metal foam (HMMF) as a cathode flow field was established using computational fluid dynamics (CFD). The HMMF with high porosity as a cathode flow field can enhance reactant transfer and accelerate the electrochemical reaction process. It is also observed that increasing the porosity of HMMF can significantly improve the peak power and current density of PEMFC. The simulation results show that the current density gains an increase of 15.3% by raising the porosity from 0.8 to 0.96. Besides, the current density increases by 4.3% when the pore density is 95 PPI compared to 21 PPI. Moreover, the effects of cathode stoichiometry ratios on oxygen molar fraction and polarization curves were studied to obtain better operating conditions for the HMMF flow field. The results indicate that increasing the cathode stoichiometry ratio can effectively enhance oxygen concentration. And the increase of the cathode stoichiometry ratio from 1.5 to 4.0 results in a 45.5% increment of current density.