Diffusion Media and Interfacial Effects on Fluid Storage and Transport in Fuel Cell Porous Media and Flow Channels

Abstract

The residual water content stored in fuel cell media under steady or time-varying operation is of great interest, because it can play a critical role in the operating performance, pressure loss, degradation via ionic contaminants or mechanical damage, and time to start and degradation from a frozen condition. Liquid water storage and distribution in the diffusion media of polymer electrolyte fuel cells (PEFCs) is not solely a function of the diffusion media properties, however, and although the diffusion media plays a strong role in water removal, the interface between the land and diffusion media also has an important influence on the water storage and removal rate under steady and transient operation. In this study, our current understanding of the relationship between the diffusion media, channel geometry, land area, and interfacial forces on the water storage in the fuel cell will be discussed, based on extensive imaging and analysis compiled at the FCDDL.