Liquid droplet detachment and dispersion in metal foam flow field of polymer electrolyte membrane fuel cell

Abstract

Porous metal foams have gained much attention as the reactant distributor in polymer electrolyte membrane (PEM) fuel cell due to their high porosity, good distribution capacity, and excellent electrical and thermal conductivity. Water management is a major concern hindering their wide adoption in PEM fuel cells. In this study, two different pore size metal foam flow fields are digitally reconstructed based on their morphological analysis. Then, the two-phase flow field microstructures are simulated using the volume of fluid method (VOF) to investigate liquid droplet removal and dispersion. Various droplet diameters and ligament surface wettability are investigated. It is found that a comparable sized liquid droplet to the foam pore requires a high critical air velocity for droplet removal. Liquid dispersion in the metal foam flow field improves liquid removal, especially for large droplets. Moreover, increasing the ligament surface hydrophobicity or reducing the foam pore size helps liquid removal at a high-velocity air flow. The proposed method can be used to optimize the contact angle and pore size in the metal foam design for water removal in porous media flow fields.