Experimental studies on optimal operating conditions for different flow field designs of PEM fuel cells

Abstract

In this work, the main focus is to measure the optimal cathode fuel flow rate effects with different flow field designs. In addition, the effects of different flow field designs (flow channel number, flow channel length, corner numbers and baffle effects) on the cell performance of the PEM fuel cells under the different operating conditions are examined. The experimental results reveal that the temperature effects generate the same trend in the five cathode flow field designs. When the cell temperature increases from 50 to 70 °C, the proton exchange membrane (PEM) experiences an insufficient hydration which causes an increase in ionic transport resistance. Therefore, the cell performance decreases with an increase in the cell temperature. In addition, increasing the cathode humidification improves the cell performance through enhancing the hydration level of the membrane and hence its ionic conductivity. For the effects of the cathode fuel flow rate on the cell performance, the PEM fuel cell with interdigitated flow field shows a better cell performance than that with the conventional flow field due to the baffle effect which forces the reactant gas through the gas diffuser layer. Furthermore, compared with conventional flow field, the PEM fuel cell with an interdigitated flow field can reach the same cell performance with a lower fuel consumption rate. Under the optimal fuel flow rate conditions, the PEM fuel cell with a parallel flow field with baffle provides the best cell performance among the five flow field designs.