The geometry of the flow field is a key factor influencing the performance of proton exchange membrane fuel cells (PEMFCs), as it affects electrochemical reaction rates, mass transport, and gas diffusion. In this study, a 3D CFD model was developed to assess how different channel geometries and internal obstacle arrangements impact fuel cell performance. A base configuration with straight channels was validated using experimental polarization data at 0.6 V. Subsequently, a serpentine channel was introduced along with obstacles of varying heights (0.25–1 mm), arranged in two configurations: increasing and decreasing along the flow path. The increasing-height configuration yielded the highest performance, with a current density of 0.25546 A/cm2 at 0.6 V, showing improvements of 5.40 % at 0.6 V and 8.07 % at 0.3 V compared to the base case, and further enhancements of 2.86 % and 3.68 % compared to the plain serpentine setup. Based on the temperature, pressure, and vapor concentration analysis, the produced water in the fuel cell does not reach condensation, confirming that the single-phase flow assumption in the simulations is valid. The decreasing-height configuration resulted in a current density of 0.24810 A/cm2, improving performance by 2.37 % at 0.6 V and 2.91 % at 0.3 V relative to the base case. However, a slight decrease 0.10 % at 0.6 V and 1.27 % at 0.3 V was observed, when compared to the serpentine-only configuration. These findings demonstrate that geometric optimization particularly using increasing-height obstacles in serpentine channels can significantly enhance PEMFC efficiency and current density.

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