Development of a PEFC with parallel hybrid pattern gas channels (1st report, design and performance test of the gas channels)

We have developed hybrid gas channels for polymer electrolyte fuel cells (PEFCs) that can arbitrarily change the ratio of the flow rates between interdigitated and parallel flows. We study gas channel structure and the above ratio by analyzing overpotentials to improve the cell performance. The flow rates of the two flows are controlled by valves of the inlets and outlets of high and low pressure gas channels in the cathode. The flow coefficients of the valves (CV values) are measured beforehand for calibration. Differences between total flow rate and each the flow rate give the rate of in-plane flow passing through the GDL under the rib of the separator. Increasing the flow rate through the GDL under the rib of the cathode separator improves the cell performance although the effect of the flow rates in the high and low pressure gas channels of the cathode on the cell performance is small. This can be explained by that large amount of oxygen is consumed at the electrode (catalyst layer) under the rib where the electrode reaction takes place predominantly.