A model is developed to explain the water movement in a hydrophilic gas diffusion layer (GDL) of PEFC. In the model, a fine hydrophilic columnar fiber is set perpendicular to the surface of the catalyst layer covered by water film. The fiber stands in the channel air flow of the PEFC. The water climbs along the fiber surface up to several tens micron meters for fibers with a diameter range between 3 to 30 micron meters. The calculated results of the evaporation rate from a set of parallel fibers simulating GDL with a void fraction of 0.5 are shown to be much higher than the water generation rate at the catalyst layer with a power density of 1A/cm^2.
