Effect of height/width-tapered flow fields on the cell performance of polymer electrolyte membrane fuel cells

Water flooding at the cathode is a critical issue in polymer electrolyte membrane fuel cells, since it will block the oxygen transport, resulting in a large concentration loss. To address this issue, two tapered flow fields with varying height or width are proposed in this study, as the tapered channels can gradually increase flow velocity which is beneficial in water removal. To confirm the proposed function, both experiments and simulation are performed. The results prove that the tapered flow fields with high velocity at the downstream region can significantly enhance water removal in flow channels, which avoids the mass transport limitation and improves the cell performance at high current densities. Additionally, the tapered design can also enhance the under-rib convection between adjacent channels, which helps to remove accumulated water in the gas diffusion layer.