Simulation of the purging process of liquid water in a gas diffusion layer with a wetting gradient using the lattice Boltzmann method

The gas diffusion layer (GDL) is a key component affecting water management. A multi-component multiphase lattice Boltzmann method is used to simulate the liquid water purging process in the GDL of a proton exchange membrane fuel cell with a interdigitated flow field. For the transverse and longitudinal wettability gradient variation of GDL, the effects of different initial water contents are investigated separately considering the random distribution of droplets. By analyzing the change of liquid water distribution and remaining water content in the GDL with time, it is found that for the transverse wetting gradient, the wettability of 100°–140° gradient variation at 20% water content has the best purging effect, but the improvement is not obvious, and the wettability of 140°–100°–140° gradient variation at 100% water content has the smallest remaining water content of 7.30%. For the longitudinal wetting gradient, there is no positive effect on purging at 20% water content, and the smallest remaining water content of 6.95% for the wettability of 140°–100° gradient variation at 100% water content.