Liquid Transport in Superhydrophobic Walled Minichannels for Polymer-Electrolyte Fuel Cell Flow-Fields

Abstract

This work explores the impact of a superhydrophobic sidewall coating on liquid build up and pressure drop in polymer-electrolyte fuel cell minichannels. Using ex-situ experimental methods and optical imaging, time series liquid water distributions were captured along with pressure drop in a transparent test channel. The minichannel sidewalls were treated with a commercial superhydrophobic coating to achieve a contact angle of ~150⁰. The liquid was injected at a single point through the gas-diffusion layer to simulate liquid transport from the catalyst layer to the GDL surface. During the tests the liquid injection was cycled on and off to capture a diverse dataset including purge and start up scenarios. Two minichannels with identical widths but different heights were probed. The superhydrophobic walls, while resulting in higher pressures, were observed to reduce the water content (especially during purging) for the thicker channel, while achieving mixed results in the thinner.