Numerical investigation of water droplet impact on PEM fuel cell flow channel surface

Abstract

Proton exchange membrane (PEM) fuel cell is a clean energy conversion device. Water management is one of the critical issues limiting the PEM fuel cell performance and service life. Liquid water impact on fuel cell surface significantly influences water transport and removal in the PEM fuel cell. In this study, a numerical investigation of water impact on the channel surface opposite to the GDL is carried out using the volume of fluid (VOF) method. The effects of impact velocity, droplet size, surface contact angle, temperature and impact angle on the water impact process are investigated. Water droplet impact on the wet flow channel surface is also considered. The results reveal that the water droplet experiences spreading and retraction stages in the impact process on a dry surface, determined by the interactions among the surface tension, inertial force and viscous force. Increasing the impact velocity, droplet size, surface hydrophilicity, temperature and impact angle lead to greater maximum water spreading factor on the surface. The water motion modes mainly include merging, crown-shaped jet flow and splashing on a wet surface, based on the magnitude of the impact velocity. The splashing is easier to occur for water droplet impact on a wet surface.