A Lattice Boltzmann Simulation of Gas Purge in Flow Channel with Real GDL Surface Characteristics for Proton Exchange Membrane Fuel Cell

Gas purge is considered as an essential shutdown process for a PEMFC (Proton Exchange Membrane Fuel Cell), especially in subfreezing temperature. The water flooding phenomenon inside fuel cell flow channel have a marked impact on performance in normal operating condition. In addition, the residual water freezes in the subzero temperature, thus blocking the mass transfer from flow channel to porous media. Therefore, the gas purge course is of primary importance for improvement of performance and durability. The water droplet residing in the flow channel can be purged out due to shearing force of gas. In fact, the flow channel is not completely flat due to surface roughness of gas diffusion layer (GDL), meaning the water droplet may climb over obstacles. Moreover, the water droplet may block the flow channel and then be sheared into films on the surface of GDL. The lattice Boltzmann method (LBM), based on the mesoscopic kinetic theory, has recently become a powerful simulation tool for multiphase flow. The main advantages of LBM over traditional computational fluid dynamics (CFD) include capacity for investigating complicated geometries, simple implementation, high computation efficiency and easy implementation of parallel-processing. In the present work, the multicomponent multiphase lattice Boltzmann (LB) model is developed and applied to simulate the gas purge process in the flow channel with real GDL surface characteristics for PEMFC. The real GDL surface characteristics (obstacle, wettability, blockage of channel, etc.) is investigated mainly. We hope to have a better understanding of gas purge mechanism from a mesoscopic way.