Performance of Parallel, Interdigitated, and Serpentine Flow Field PEM Fuel Cells with Straight or Wavelike Channels

This work used a three-dimensional, two-phase, and nonisothermal model to compare performances of proton exchange membrane (PEM) fuel cells with a parallel, interdigitated, or serpentine flow field when wavelike gas channels (GCs) are or not employed, to determine which flow field needs wavelike GCs more than the others. The comparisons showed that the performance enhancement is the most pronounced for the parallel flow field, whereas the enhancement was significantly reduced for the serpentine and interdigitated flow fields when wavelike GCs are adopted. For the parallel flow field, oxygen transport into the gas diffusion layer (GDL) and liquid water removal from the cathode porous electrode were enhanced remarkably by wavelike GCs. As a result, more oxygen was transported into the catalyst layer (CL) to participate in electrochemical reactions, leading to better cell performance. However, subrib convection in the interdigitated and serpentine flow fields weakened the role of wavelike GCs, so that the performance was not improved greatly for the two flow fields. The influence of the amplitude to wavelength ratio, aspect ratio of wavelike GCs, and cathode flow rate in the parallel flow field were investigated. The results show that the optimal amplitude to wavelength ratio is 0.6, which yields a 13.44% increase in the power density compared with straight GCs. The wavelike GCs had greater enhancement when small channel aspect ratios were employed or when the cell operated at larger cathode flow rates. The simulations provide useful guidance for practical PEM fuel cell flow field designs. (c) 2020 American Society of Civil Engineers.