Optimal water management in proton-exchange-membrane fuel cells at lower temperatures requires the efficient removal of liquid water from the cell. This pathway is intimately linked with liquid-water-droplet removal from the surface of the gas-diffusion layer (GDL) and into the flow channel. In this study, these liquid-water phenomena are investigated experimentally to improve the understanding of water transport through, and removal from, the GDL. Specifically, an experiment using a sliding-angle measurement is designed and used to quantify and measure directly the adhesion force for liquid-water droplets and to understand the droplets{\textquoteright} growth and detachment from the GDL. The results show that unlike the static contact angle, the adhesion force, as measured by sliding angles, provides a good indicator of water-droplet removal as it is a direct measure of the dominating force that is holding a droplet on the GDL surface and preventing its detachment. It is also observed that injection through the GDL, as is representative of operating fuel cells, results in a higher adhesion force than a droplet placed on the top surface. Finally, it is shown that aged GDLs demonstrate higher adhesion forces, which dominate GDL degradation response and fuel-cell water holdup.
}, year = {2012}, booktitle = {Journal of The Electrochemical Society}, journal = {Journal of The Electrochemical Society}, series = {Journal of The Electrochemical Society}, volume = {159}, pages = {B489}, month = {02/2012}, issn = {00134651}, doi = {10.1149/2.052205jes}, note = {This was Paper 783 presented at the Boston, Massachusetts, Meeting of the Society, October 9{\textendash}14, 2011.
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