Lattice-Boltzmann Simulations of Multiphase Flows in PEM Fuel Cell GDLs and Micro-channels

The lattice Boltzmann (LB) method is employed to simulate single and multiphase flow through porous gas-diffusion-layer (GDL) of a Proton Exchange Membrane Fuel Cell (PEMFC). The porous layer is composed of layers of fibers. The structure is reconstructed numerically and validated by other published data on porosity and pore-size distributions. The in-plane gas-permeability is greater than the through-plane values and has greater sensitivity to fiber orientations. The permeability decreases as the GDL is compressed. When liquid is introduced, multiple droplets emerge from the other side of the GDL through surface pores. On hydrophobic GDL, the liquid advancing inside the GDL is in the form of several interconnected streams leading to surface openings. As the hydrophobicity is increased the liquid break-through occurs at lower saturation.