Thermal Performance of Hybrid Pin-Fin/Metal Foam Heat Sinks: Toward Enhanced Cooling of Power Electronics in Renewable Energy Applications

Abstract

The present work reports an experimental investigation into the coupled thermo-hydraulic behavior of hybrid heat sink assemblies consisting of aluminum pin fins integrated with open-cell copper metal foam, tested under steady-state and transient forced convection conditions. A structured parametric matrix was established to independently resolve the contributions of pin-fin outer diameter (10 mm and 15 mm), copper foam porosity (90% and 95%), inlet air velocity (0.75 m/s and 1.5 m/s), and applied thermal power (20–60 W). The measured data reveal a pronounced geometry-dependent dichotomy: for the compact 10 mm series, foam encapsulation consistently augmented cooling performance, attaining a maximum thermal enhancement ratio of 22.5% relative to the uncoated baseline. Conversely, in the 15 mm series, the enlarged foam-wrapped fins introduced severe macro-scale aerodynamic bypass, culminating in a thermal degradation of up to 24.6%. Doubling the inlet velocity yielded cooling improvements of up to 29.4% and progressively reduced the sensitivity to foam porosity, implying a convergence in convective behavior at elevated flow rates. Transient post-heating experiments further disclosed that thermally superior configurations retain appreciably higher thermal inertia during the cool-down phase. Taken together, the findings establish that the viability of porous media augmentation is critically conditioned on the geometric scale of the fin array and provide quantitative design criteria for reconciling heat transfer enhancement with aerodynamic permeability in next-generation hybrid thermal management systems.