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

• Published in: Energy conversion and management 2021-06, Vol.237, p.114095, Article 114095
• Main Authors: Mojica, Felipe, Rahman, Md Azimur, Sarker, Mrittunjoy, Hussey, Daniel S., Jacobson, David L., LaManna, Jacob M., Chuang, Po-Ya Abel
• Format: Article
• Language: English
• Subjects: Convergence; Converging-diverging channel; Diffusion layers; Finite element method; Fuel cells; Fuel technology; Gaseous diffusion; Limiting current; Mass transport; Neutron flux; Neutron radiography; Nozzle design; Oxygen; Oxygen transport; PEM Fuel cell; Proton exchange membrane fuel cells; Protons; Simulation; Straight channels; Water; Water management; Water transfer
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2021.114095

•Experiments and modeling are performed to study channel design in a PEMFC.•Limiting current method is used to measure oxygen transport resistance.•In-situ liquid water distribution is visualized using neutron radiography.•Performance improvement of 25% was achieved by the 3D-Nozzle channel design.•Channel induced convective flux was observed in the gas diffusion layer. 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.