Heat and Mass Transfer in Polymer Electrolyte Fuel Cells in Ultra-Low Humidity Operation

A computational and experimental study on the operation and performance of polymer electrolyte fuel cells (PEFC) under low humidity conditions is performed. It is postulated that high ohmic overpotentials due to low hydration in the membrane and catalyst layers cause a significant increase in temperature, which in turn further increases the ohmic resistance. The model results show that as the cell voltage decreases, the temperature increases and causes a decrease in water activity of the ionomer phase despite the larger amount of water produced at higher current densities. This finding is supported by the measured increased in the ohmic resistance of experimental cells.