Controlled Three-Dimensional Numerical Comparison of Parallel and Serpentine Flow Field Designs in a Self-Humidified Low-Temperature PEM Fuel Cell

Proton exchange membrane fuel cells (PEMFCs) are critical parts of new-age green hydrogen energy systems where reactant distribution and water management determine performance and reliability. A three-dimensional, steady-state, and single-phase model of a self-humidified low-temperature PEMFC was developed in COMSOL Multiphysics to compare parallel, single-serpentine and double-serpentine bipolar plate flow fields under identical active area membrane electrode assembly, material properties and operating conditions, so that flow field geometry was the only variable. The model is verified via grid independence and validated in terms of published experimental polarization data with mean absolute deviation under 2%. At 0.1 relative humidity of the cathode inlet, the single-serpentine flow field provides 717 mA cm−2 current density at 0.6 V and 595.7 mW cm−2 peak power density in contrast to 582 mA cm−2 and 492.3 mW cm−2 for the double-serpentine and 577 mA cm−2 and 463.2 mW cm−2 for the parallel flow field. These two designs therefore behave almost identically in electrochemical terms but differ hydraulically; their peak channel pressure drops, being 3.8 and 0.8 kPa against 14 kPa for the single-serpentine design. Once pumping power is included, the single-serpentine design remains the best net power choice below an active area of approximately 54 cm2.