Two-phase flow and evaporation in model fibrous media: Application to the gas diffusion layer of PEM fuel cells

Two-phase flow dominated by capillary effects in model fibrous media is studied combining pore-network simulations and visualisations on transparent micromodels. It is shown that the process of liquid water invasion in a hydrophobic medium can be simulated using the classical invasion percolation algorithm provided that the contact angle (measured in air, which is the wetting phase) is sufficiently far below 90°. For contact angles approaching 90°, changes in the interface local growth mechanisms lead to changes in the invasion pattern.