Study of droplet flow characteristics on a wetting gradient surface in a proton exchange membrane fuel cell channel using lattice Boltzmann method

Abstract

Effective water management is essential to improve the performance of proton exchange membrane fuel cells (PEMFCs). A pseudopotential multiple relaxation time (MRT) multi-component lattice Boltzmann method (LBM) is used to simulate the droplet flow behavior in the channel with different wetting gradient surfaces under air purge. The model is verified by thermodynamic consistency, large density ratio and viscosity ratio, surface tension independent regulation, Laplace's law, and static contact angle test. The results indicate that the shape of the droplet moving on the surface with different wetting gradients changes differently, resulting in different pressure differences between the inlet and outlet of the flow channel. Considering only the discharge time, the surface with a continuous variation of contact angle from 140° to 100° has the best purging effect. The motion of two droplets on this surface is simulated, and it is found that the short distance and large size difference between the two droplets facilitate the rapid discharge of the droplets from the flow channel. However, the shorter the distance, the more violent the droplet deformation during the coalescence process and the greater the pressure difference caused.