Integrated Numerical Model for Investigating Droplet Breakup and Escape in Gas-Water Separators of PEMFC Systems

In this article, we present a numerical model of two-phase flow in a separator. It couples turbulent and multiphase volume of fluid (VOF) models with discrete phase model (DPM) for droplet track. The shear stress transport (SST) k-ω model and symmetric drag force model can accurately reflect the flow behavior through contrastive analysis. Subsequently, the droplets flow characteristics and the effect of surface tension on the droplet breakup were investigated. Results showed reducing surface tension promotes droplet breakup and leading to more small-diameter droplets in the inlet pipe. At the junction, large-diameter droplets are captured by the wall liquid film and partly break up into small-diameter droplets. Some are carried away by the gas flow and others aggregate and are discharged. The droplet size at the overflow port typically does not exceed 5 μm. As the hydrogen inlet increases, average droplet size at the overflow port decreases, causing more large-diameter droplets to be captured, thereby improving the separation performance.