Computational study on effect of geometric shape of flow channel and oscillatory gas supply on hot spot mitigation in PEM fuel cell with a 3D model of reconstructed gas diffusion layer

This study presents a transient, three-dimensional, non-isothermal simulation of the cathode side of a proton exchange membrane fuel cell (PEMFC) incorporating a realistically reconstructed, randomized carbon paper gas diffusion layer (GDL) based on SEM-inspired microstructure geometry. Unlike conventional models that treat the GDL as a homogeneous porous medium, the present work explicitly resolves individual fibrous layers and couples this structure with varied channel geometries-straight, bumped, wavy, and two variable-wavy designs-to investigate their effects on local hot spot mitigation. Additionally, the combined influence of channel geometry and oscillatory inlet gas composition is studied for the first time in such a configuration. The results show that the reconstructed GDL yields 23 K lower peak temperatures compared to equivalent 2D homogeneous GDL simulations. Wavy and variable-wavy designs reduce hot spot intensity by up to 12 K compared to the straight channel, while oscillatory inlet modulation (δ = 0.03) achieves an additional 70–76 K reduction through periodic suppression of inlet-side reaction heat generation and enhanced unsteady convective cooling. The findings establish that coupling realistic GDL structures with oscillatory inlet strategies offers an effective pathway for improving PEMFC thermal management while identifying the trade-off between thermal benefits and increased pressure drop.