Enhanced PEM fuel cell cooling using Al₂O₃ and TiO₂ nanofluid-based thermal models

Nanofluid-based cooling of polymer electrolyte membrane fuel cell (PEMFC) stacks is investigated numerically for a five-cell configuration with parallel cooling channels. A three-dimensional coupled model is implemented in COMSOL Multiphysics by combining heat transfer, porous-medium (Darcy) flow in the cooling plate domain, and electrochemical heat generation. The simulations were conducted at a coolant inlet temperature of 299.15 K, atmospheric pressure, and uniform inlet velocity, utilizing the Brinkman and Maxwell mixture correlations for viscosity and thermal conductivity. Pure water is compared with Al₂O₃/water and TiO₂/water nanofluids at volume fractions of 1–5%, where effective properties are evaluated using established mixture correlations. The simulations indicate that Al₂O₃/water reduces the maximum temperature and improves temperature uniformity in the membrane–electrode assemblies relative to pure water, while TiO₂/water yields a smaller improvement under the same operating voltages (0.55–0.85 V). Improved thermal regulation is accompanied by more spatially uniform reactant distribution indicators (hydrogen and oxygen molar fraction) and water activity. The findings are limited to the modeled geometry and the adopted single-phase nanofluid correlations; experimental validation and a quantified pumping-power penalty remain necessary for assessing practical applicability.