Investigating Inlet Condition Effects on PEMFC GDL Liquid Water Transport through Pore Network Modeling

In this work, the influence of the liquid water inlet boundary conditions at the gas diffusion layer (GDL)/catalyst layer interface on the spatial distribution of liquid water within the GDL was studied. We used pore network modeling with invasion percolation to simulate liquid water transport in a commercially available GDL, where the detailed, 3D microstructure of the GDL was obtained through X-ray imaging. Three inlet boundary conditions were studied: uniform pressure (single reservoir), uniform flux (completely discretized reservoirs), and distributed uniform pressure (random spatial- and size-distributions of reservoirs). We presented the distributed uniform pressure boundary condition as a more realistic inlet, where inlets are randomly distributed reservoirs that are connected to multiple inlet pores. It was found that the overall saturation ranged from 6% to 28% when the number of inlets ranged from 20 to 300; however, the GDL/catalyst layer delamination dominated water transport behavior.