Performance enhancement of oval-shaped mini-channel heat sinks using hBN nanofluids: An experimental thermo-hydraulic analysis

This study experimentally investigates the thermo-hydraulic performance of plain and oval-shaped mini-channel heat sinks using deionized water and hexagonal boron nitride (hBN) nanofluids at concentrations of 0.05% and 0.10%. The influence of Reynolds number, channel geometry, and nanoparticle concentration on Nusselt number, heat transfer coefficient, pressure drop, friction factor, and pumping power was quantified. Results showed that the oval mini-channel with 0.10% hBN nanofluid produced the highest thermal enhancement, achieving a 220% increase in Nusselt number and a 240% rise in heat transfer coefficient at Reynolds number 900 compared to plain deionized water. Increasing nanoparticle concentration from 0.05%-0.10% further improved the Nusselt number by 35%, indicating strong particle-driven thermal enhancement. Geometry effects alone contributed an additional 20% improvement, demonstrating the significance of flow restructuring via oval cross-sections. Pressure drop penalties remained moderate, increasing by 11.03% for the oval channel with 0.10% hBN and 7.40% for deionized water relative to plain channels. Overall, the combined effects of optimized channel geometry and hBN nanofluid significantly improved convective heat transfer with acceptable hydraulic losses, establishing oval mini-channels as a superior design for compact high-heat-flux thermal management systems.