Analysis of Flow Variation in a Straight Channel with Baffled Obstacles on a Bipolar Plate in a Proton-Exchange Membrane Fuel Cell

摘要

The channel structure of a proton-exchange membrane fuel cell (PEMFC) is very important for sustaining high performance with a reliable lifetime. There have been numerous computational studies to investigate the physics of electrochemical reactions with various flow field phenomena. Because straight channels reduce manufacturing costs, a straight channel was selected as the subject of a numerical study to investigate water removal and oxygen starvation in the channel. In this study, the liquid saturation distribution caused by the baffled obstacle geometry of a PEMFC with channels that were straight and parallel was analyzed in a computational study. Because baffled obstacles generate a vortex in the channel, the flow field structure improves the supply of reactants. When the operating pressure is reduced from 3 atm to 1 atm, the baffled obstacle structure interrupts the flow of reactant and product water so that the accumulation of liquid water increases from 0.75 to 0.86 in catalyst layer. As the number of baffled obstacles was increased from 13 to 19, the current density improved from 0.772 to 0.773 A/cm(2) in the reference condition. The baffled obstacle geometry also affects the liquid water accumulation flow field. Results show that the design of the baffled obstacles in a channel should consider the number of baffled obstacles along with the baffled obstacle geometry such that water removal is accelerated.