Effective removal and transport of water in a PEM fuel cell flow channel having a hydrophilic plate

Abstract

Effective removal and transport of water in the flow channel of a proton exchange membrane (PEM) fuel cell (PEMFC) is significantly important to the critical water management in PEMFCs. In this study, the process of water removal and transport is investigated numerically by using the volume-of-fluid method for a flow channel having a hydrophilic plate in the middle of the channel. The results show that the liquid water droplet on the membrane-electrode assembly (MEA) surface can be removed effectively, and the removal process is facilitated significantly by the hydrophilic plate which should have a surface contact angle larger than the bottom channel surface but less than the MEA surface. Once the liquid water contacts the plate, it is detached from the MEA surface, and transported to the channel surface along the plate surface; whereas without the plate the water droplet is transported along the MEA surface under the same flow condition. The pressure drop associated with the flow in the channel can be reduced substantially by the presence of the plate due to a characteristic change in the water removal and transport process, when compared to the pressure drop in a conventional flow channel or a channel with a needle shown in literature. The wettability, the length and the height of the plate all can have an impact on the water transport and dynamics as well as the associated pressure drop in the flow channel. A parametric study is carried out to determine the optimal values for the surface contact angle, the length and height of the plate.