Water transport in the proton-exchange-membrane fuel cell: measurements of the effective drag coefficient

The water transport in proton-exchange-membrane fuel cells has been experimentally investigated by measurements of the effective or net drag coefficient. Results are presented for a wide range of operating conditions (current density, temperature, pressure, stoichiometry and humidity of the inlet gases), as well as for different types of membrane-electrode-assemblies. It was found that the humidity and the stoichiometry of the inlet gases had a large effect on the drag. Of the material properties investigated, the membrane thickness was found to be the most significant parameter. Inspection of the cell performances showed that drying of the cathode was much more detrimental for the cell performance than drying of the anode. This was ascribed to increased activation losses, which turned out to be extremely sensitive to the type of cathode used.