Mechanism of PEMFC output performance improvement via non-uniform bluff body structures in bipolar plate flow channels: Flow field regulation and mass transfer enhancement

The flow channel architecture of bipolar plates critically determines the mass transfer efficiency and high-power-density performance of proton exchange membrane fuel cells (PEMFCs), and is pivotal to the efficient operation of renewable energy systems. Embedding bluff bodies in the cathode channel enhances convection, yet the collective influence of their geometry and arrangement on net power output still lacks systematic investigation. Herein, we innovatively reveal the dynamic balance mechanism of flow resistance-mass transfer gain-net power governed by bluff body geometry and dimensions. More importantly, this study elucidates the core principle that non-uniform configurations serve to achieve lengthwise differential mass transfer enhancement in the channel and enhance the uniformity of multi-physical fields within the MEA. Quantitatively, the effects of bluff body shape, size, density and distribution on cell performance are systematically investigated, and the optimal geometric parameters and distribution strategy are preliminary identified. Notably, the bluff body parameters interact in complex synergistic and restrictive ways, with no simple uniform influence mechanism. These findings improve PEMFC performance in applications where hydrogen is produced from renewable energy sources.