Study of converging-diverging channel induced convective mass transport in a proton exchange membrane fuel cell

The flow channel design in a proton exchange membrane fuel cell is critical for transporting reactant gases and removing product water efficiently. Herein, we proposed and performed a comprehensive study of four flow channel designs: straight, wavy, 2D-Nozzle, and the novel 3D-Nozzle. Using the limiting current method, we discovered that the oxygen transport resistance of straight, wavy, and 2D-Nozzle designs are similar confirming the diffusive transport mechanism. In contrast, the oxygen transport resistance of the 3D-Nozzle design is significantly less than that of the other three designs due to the channel-induced convective flux in the gas diffusion layer. As a result, the peak power density of the 3D-Nozzle design is 25% higher than all other designs. The in situ neutron images confirm that the 3D-Nozzle design has less and more evenly distributed water than the straight channel design. Lastly, the simulation results using a three-dimensional finite element COMSOL model show notable in-plane and through-plane convective flux in the gas diffusion layer promoting oxygen and liquid water transfer. The combined experimental and simulation results validate that the novel three-dimensional converging?diverging channel design provides superior water management capability, which in turn improve the performance and robustness of a fuel cell.