Operation limitations from studies of an ambient pressure PEM fuel cell stack for portable applications

A small 10-cell proton exchange membrane fuel cell (PEWC) stack for demonstrational purposes was designed and tested, The stack was operated on pure hydrogen and ambient air without inlet gas humidification or external heating. Polarization curves for individual cells were obtained up to a current density of 0.40 A/cm(2) with a corresponding stack peak power of 41 W. The temperature distribution in the air channels of the stack was mapped showing temperature gradients of up to 10 degrees C. Polarization curves show very similar single cell performances despite these substantial temperature gradients. The simplicity of the PEMFC system limits the operation to low power densities. With the reactant air as the only means of stack cooling, long term operation at higher power densities was not possible due to stack overheating with subsequent risk of membrane failure.