Enhancing mass transfer and water drainage in proton exchange membrane fuel cells via active-passive synergistic composite flow channels

Appropriate design and optimization of cathode flow fields are crucial for enhancing the overall performance of proton exchange membrane fuel cells (PEMFCs). This study proposes an Active-Passive Synergistic Hybrid Channel (APSHC) to optimize central mass transfer in the channel center and water drainage in the rib regions. The core unit consists of a central teardrop-shaped deflector and wall-mounted semi-teardrop grooves arranged alternately along the flow direction. A 3D multiphysics model is built to evaluate mass transfer and water drainage performance and explore the influence of core unit parameters (height H , radius R , and pitch P ) and the number of units ( N ). Simulation results at 0.45 V show that the APSHC delivers better performance than conventional parallel channels. It yields 18.7% higher net power density and 5.6% higher oxygen concentration, and reduces liquid water saturation by 6.1%. Parametric analysis reveals that H and N require optimal thresholds to mitigate excessive lateral flow and the flow shielding effect. Furthermore, the preferred value of R screened by single-factor analysis yields a favorable trade-off between mass transfer efficiency and pumping losses. In contrast, increasing pitch ( P ) impairs device performance, thereby demonstrating the superiority of compact structural layouts. By integrating geometry and spatial layout, the proposed APSHC balances trade-offs among mass transfer, water drainage, and flow resistance.