Numerical study of porous flow field designs for proton exchange membrane fuel cells

The structure of the flow field can directly affect the gas distribution and the performance of proton exchange membrane fuel cells (PEMFCs). This work presents the modifications of porous flow fields in PEMFCs using the computational fluid dynamics method. Different designs of porous flow fields are employed and evaluated, so as to improve the uniformity of the cell performances over the entire cell area. The effects of manifold structure on the distribution of the key operating parameters including the reactant molar fraction, temperature, current density, etc. are discussed. It is found that the manifold designs can significantly affect the flow behaviors in the porous flow fields, especially in the corner area. The convergent inlet and divergent outlet manifold channels favor homogenizing the flow distribution and reducing the pressure drop. Moreover, a proper porosity of the flow field can benefit the uniform distribution of the reactant and improve the cell performance.