Modeling and synchrotron imaging of droplet detachment in gas channels of polymer electrolyte fuel cells

A computational fluid dynamics model of a channel (one liquid inlet, one liquid inlet and one two-phase outlet), applicable for PEFC gas channel water transport, is developed. A volume of fluid approach is used to study the two-phase flow behavior (interface-resolved) inside the gas channel, including the surface of GDL (gas diffusion layer), which is verified by experimental results from synchrotron based X-ray radiography and tomography imaging. A reasonably good agreement is found between the model and the measurements in terms of droplet dynamics, shape, and size. The channel height strongly influences the droplet transport behavior, with the droplet being attached to the GDL surface, as well as to the wall on the opposite side to the GDL at the same time for the shallowest channel (150 μm). The GDL contact angle influences the droplet size, with an increased GDL contact angle creating smaller droplets