Numerical and microfluidic pore networks: Towards designs for directed water transport in GDLs

Based on a pore network representation of porous media, numerical and experimental methods are employed to explore the design of gas diffusion media in order to control and direct water transport. Randomized pore networks with structured biasing in both diagonal and radial directions show a marked influence on liquid water transport through the two-dimensional media. Radial biasing is shown to have the beneficial effect of decreasing the network saturation, which is a desirable quality in fuel cell gas diffusion layers. Similar flow patterns are obtained from both numerical simulations and experiments, and it is found that relatively small radial biasing can yield a 43% decrease in average saturation compared to pore networks without a prescribed radial gradient.