Visualization of Liquid Water Transport in a PEFC

Abstract

Using an optical /air polymer electrolyte fuel cell (PEFC), the mechanics of liquid water transport, starting from droplet emergence on the gas diffusion layer (GDL) surface, droplet growth and departure, to the two-phase flow in gas channels, is characterized under automotive conditions of 0.82 A/cm2, 70°C, and 2 atm. It is observed that water droplets emerge from the GDL surface under oversaturation of water vapor in the gas phase, appear only at preferential locations, and can grow to a size comparable to the channel dimension under the influence of surface adhesion. Liquid film formation on more hydrophilic channel walls and channel clogging are also revealed and analyzed. © 2004 The Electrochemical Society. All rights reserved.