Investigation of the Lateral Water Distribution in a Proton Exchange Membrane in Fuel Cell Operation by 3D-MRI

Abstract

Lateral distribution of water content in a proton exchange membrane in an operating fuel cell was measured by using three- dimensional magnetic resonance imaging (3D-MRI), which clearly visualized not also lateral water distribution in the membrane but also condensed water in flow channels in the cell. Both a parallel flow and a serpentine flow were investigated in a variety of current density. In the parallel flow, the membrane near the gas inlet shows lower water content compared to those near the gas outlet. It was also shown that with increase of current density, overall water content in the membrane decreased, presumably due to dehydration of the membrane triggered by electro-osmotic effect. In the serpentine flow, dehydration area across the membrane from the flow inlet to the outlet was found. These MRI observations indicate that condensed water droplets strongly affect overall flow behaviors in the operating fuel cell.