Droplet Dynamics and Removal from Polymer Electrolyte Fuel Cell Channels Using Acoustic Pressure Waves

Abstract

Liquid water management in polymer-electrolyte fuel cell (PEFC) reactant channels is critical to system performance, stability, and lifespan. This work investigates the effect that acoustic wave transmission in reactant flow gases has on liquid water droplets growing on the GDL surface. A speaker was connected in series with the feed gas and flow channel whereby acoustic signals were generated and passed through the reactant channel. Transducers measured pressure upstream and downstream of the droplet while a high speed camera captured images of the droplets motion from the side. Early results show that pressure waves effect droplets pinning behavior on the GDL surface. Previous work has shown that a maximum contact angle hysteresis exists for droplet removal from GDLs. While gas flow causes droplet contact angle hysteresis, this work shows that oscillations caused by the acoustic waves may shift the droplet over the max hysteresis tipping point enabling removal.