Modeling of droplet detachment using dynamic contact angles in polymer electrolyte fuel cell gas channels

Climate change, energy security and air pollution are all motivators for the further development of fuel cells. A volume of fluid approach was used to investigate the impact of dynamic contact angle boundary conditions (Kistler model), mainly at the gas diffusion layer surface but also at the channel wall, of a polymer electrolyte fuel cell gas channel. From this study, it is clear that a dynamic contact angle boundary condition, with advancing and receding contact angles, influences the droplet detachment characteristics, for example, the detachment time and droplet size. Implementing dynamic contact angle boundary conditions for a thin channel causes the droplet, after being reattached to the wall on the side opposite the GDL, to flow very slowly when attached to the wall, until it is merged with a second droplet and they exit the channel (but remain attached to the wall) fairly quickly. Similar phenomena are not observed while using a static contact angle.