Effect of Channel Materials on the Behavior of Water Droplet Emerging From GDL into PEMFC Gas Channels

Abstract

Water accumulation in the gas channels of proton exchange membrane fuel cells (PEMFCs) significantly affects the gas diffusion and the overall performance. Hence, understanding the growth and detachment of liquid water droplets from the gas channel becomes critical. In this study, the behavior of liquid water droplets within the gas channel in the presence of air flow (0.2 - 2.4 m/s) is experimentally investigated for different GDL types (MRC105, SGL-25BC, TGP-H-060) and channel wall materials (stainless steel, copper, graphite composite, polycarbonate) that are commercially used in PEMFC for automotive applications. Experimental results were analyzed through Concus-Finn condition using instantaneous dynamic contact angle (IDCA) to determine the filling of the corners with liquid water. It was found that the droplet detachment is influenced by air flow within the channel and the contact angle hysteresis. Air flow produces oscillations in the droplet and changes the IDCA the droplet makes with the sidewalls and hence determines the corner filling.