Numerical Analysis of the Effect of Liquid Water during Switching Mode for Unitised Regenerative Proton Exchange Membrane Fuel Cell.

As unitised regenerative proton exchange membrane fuel cell (URPEMFC) is progressing in terms of its performance, more emphasis should be placed on the understanding of the interaction between multiphase reactants and products and its effect during the switching mode. A 3D transient computational fluid dynamics model was utilised in this study to simulate the supply of liquid water into the flow field when the system switched from fuel cell mode to electrolyser mode. Different water velocities were investigated to identify their effect on the transport behaviour under parallel, serpentine, and symmetry flow fields. From the simulation results, 0.5 m·s water velocity was the best-performing parameter in achieving optimal distribution. Among different flow field configurations, the serpentine design achieved the best flow distribution due to its single-channel model. Modification and refinement in the form of flow field geometric structure can be performed to further improve the water transportation behaviour in URPEMFC.