Development of a PEFC with serpentine hybrid pattern gas channels (2nd report, effects of the flow velocity in a low pressure channel)

We have developed hybrid pattern gas channels consisting of high and low pressure channels for polymer electrolyte fuel cells (PEFCs). The pressure difference between them gives rise to in-plane flow in the gas diffusion layer (GDL) under the rib. The high pressure channel is an interdigitated gas channel and the low pressure channel is a serpentine gas channel having smaller cross-sectional area than that in the 1st report of this work. An in-house separator is used for the cathode to vary the air flow velocity in the low pressure channel. By taking advantage of the hybrid pattern gas channels, maximum current density and stability of the cell voltage are significantly improved by an increase in the flow velocity in the low pressure channel. In contrast, a decrease in the flow velocity in the low pressure channel leads to a decrease in the current density at which sudden rise of IR overpotential due to the drying of the membrane electrode assembly occurs.