Cross-sectional insight in the water evolution and transport in polymer electrolyte fuel cells

The evolution of liquid water and its transport through the porous gas diffusion media in an operating fuel cell were investigated applying an experimental setup for high spatial resolution of 3 mu m. Fundamental aspects of cluster formation in hydrophobic/hydrophilic porous materials as well as processes of multiphase flow are addressed. The obtained water distributions provide a detailed insight in the membrane electrode assembly and the porous electrode with regard on the existence and transport of liquid water. In addition, the results approve transport theories used within the framework of percolation theory and demonstrate the need for adapted modeling approaches. (C) 2008 American Institute of Physics.