Multiparametric Optimization of Phase Change Material–Nanofluid Enhanced Microchannel Geometry Heat Sinks With Segmented Cavities and Trapezoidal Flow Domains

Abstract The escalating demand for efficient thermal management in high-performance electronics necessitates advanced heat dissipation strategies beyond conventional cooling. This study presents a three-dimensional numerical analysis of hybrid microchannel heat sinks (MCHS) integrated with phase change materials (PCMs), composite PCM (CPCM), and thermally conductive nanoadditives. Twelve configurations were evaluated by varying PCM placement (top, bottom, divided cavities), microchannel geometry (rectangular, trapezoidal), and working fluid composition (base fluid and nanofluids with Cu, CuO, Al2O3, graphene nanoplatelets). The selected Reynolds number range (100–2100) spans laminar to transitional regimes typical of compact microchannel cooling in electronics and battery modules, where the flowrate is constrained by pumping power and space. Applied heat fluxes (up to 140 W/cm2) match the thermal loads of modern high-performance processors, power electronics, and laser diodes. Results show that CPCM-based designs significantly outperform conventional PCM and pure-fluid systems through combined latent heat absorption and enhanced conductivity. The optimal configuration (model-11: top-mounted CPCM with 10% Cu) reduced thermal resistance by 28.4% and increased Nusselt number by 31.7% over the baseline plain MCHS–PCM, with 24.6% better temperature uniformity. Distributed cavity designs (e.g., model-12) achieved superior axial temperature control, while bottom-mounted designs (model-10) promoted faster melting but incurred higher resistance from localized heating. Cu- and CuO-enhanced CPCMs exhibited superior thermal dispersion, with up to 24% lower axial wall temperature standard deviation and 20% higher temperature uniformity index compared to Al2O3 and GnP under identical conditions. This work establishes design guidelines for next-generation MCHS, highlighting the synergistic impact of optimized PCM placement, cavity segmentation, and nanoparticle enhancement for compact, high–heat-flux electronics cooling.