Abstract
We present a novel idea to utilize a parallel channel design with a pressure difference between channels in an effort to maintain a short flow path, while attaining the cross flow inherent in serpentine flow fields. For this study, a polymer electrolyte membrane (PEM) fuel cell with the ability to control the back pressure on every other flow channel (high pressure channels, HPCs), in order to induce cross flow from the high pressure to the low pressure channels (LPCs), was designed and built. Polarization curves for different back pressures on the HPCs and for different stoichiometries on the cathode were measured. Performance gains were found at the end of the ohmic and mass transport loss regimes (voltages under 0.55 V). Secondly, the current density and net power (subtracting approximate pumping work) were determined based on HPC back pressure at steady state voltages of 0.5 V, 0.3 V, and 0.1 V. The parallel flow field with induced cross flow at the optimal back pressure had up to a 24% improvement in current density and a 14% improvement in net power over the standard parallel channel design.