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 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 Xray 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 13% to 23% when the number of inlets ranged from 20 to 300; however, the microporous layer/catalyst layer delamination dominated water transport behaviour.