Oxygen transport in proton exchange membrane fuel cells with metal foam flow fields

Metal foam flow fields have shown great potential in improving the performance of proton exchange membrane (PEM) fuel cells, while their effect on the oxygen transport process remains inadequately understood. In this study, oxygen transport in metal foam flow fields (under zero-humidity operating conditions) is simulated by using a three-dimensional multi-species lattice Boltzmann model. Comparison is done between the metal foam flow field and the conventional channel-rib flow field, and parametric studies are conducted on the metal foam porosity, pore density, and compression ratio. Results show that the metal foam flow field enhances mass transfer of oxygen to the catalyst layer and improves the oxygen distribution homogeneity. Within the range of parameters considered, decrease in the metal foam porosity yields nonmonotonic variation of the mass transfer rate of oxygen to the catalyst layer, which increases at high inlet velocities (higher than 2 m/s) but decreases at low inlet velocities (less than 2 m/s). The increase in metal foam pore density and compression ratio leads to enhanced mass transfer of oxygen, which becomes increasingly prominent at high inlet velocity. The results of this study could be insightful for the implementation of metal foam flow fields in PEM fuel cells.