Numerical investigation of water dynamics in a novel proton exchange membrane fuel cell flow channel

摘要

Water dynamics in the flow channel of a proton exchange membrane fuel cell is significantly important to water management and removal. In this study, volume-of-fluid method is used to investigate numerically the three-dimensional water dynamics in a flow channel with a hydrophilic needle. It is found that water transport and dynamics in this novel flow channel are quite different from the conventional channel. Liquid water droplet, introduced on the electrode surface, is removed through capillary effect once touching the hydrophilic needle. This is desirable since the electrode surface becomes free of liquid water, avoiding the flooding and blockage of reactant gas transport into the electrode. Increasing the contact area between the water droplet and needle, through an increase in the diameter or length of the needle, can facilitate water removal from the electrode surface because of greater capillary effect, but it also increases the pressure drop in the channel due to greater blockage by the needle. Overall, the pressure drop in the modified channel is still small compared to the pressure drop in a serpentine flow channel, making the present approach viable for use in the conventional parallel flow channels for proton exchange membrane fuel cells.