Dynamic Behavior and Drainage Characteristics of Water Droplets within Channel-Type Collection Zone in Proton Exchange Membrane Fuel Cells

The water transport processes in the bipolar plate, especially within the collection zone with water accumulation, are significant to the water management and performance enhancement of proton exchange membrane fuel cells (PEMFCs). In this article, a three-dimensional two-phase numerical model for the channel-type collection zone is constructed. The dynamic behavior of droplets is first studied. The droplets are drained in the form of a liquid film. Furthermore, the water drainage characteristics are quantified, and the effect of the channel geometry is clarified. It is indicated that the smaller the width of the collection channel, the less water accumulation. The reason lies in the reduction in the backflow area. Finally, an optimized elbow structure with 0.5 mm inner and 1.0 mm outer fillets is proposed in which case the water removal ratio increases by 8.58%, 9.16%, and 23.36% for 8, 6, and 10 m/s gas flow rates compared with the right-angle structure.