A novel double-frustum pin-fin microchannel heat sink for simultaneous heat transfer enhancement and geometry-driven thermal uniformity control

This study proposes, a novel double-frustum (DF) pin-fin microchannel heat sink that simultaneously achieves enhanced thermo-hydraulic performance and improved base temperature uniformity under high heat-flux conditions. A three-dimensional conjugate computational fluid dynamics (CFD) model is employed to investigate laminar single-phase water flow over a Reynolds number range of 200–800 and heat flux up to 800 kW m −2 . The DF geometry is benchmarked against conventional square, circular, tapered, and inverse-tapered pin-fin configurations. Results show that the DF design reduces the maximum base temperature and thermal resistance by approximately 26% compared to the square-fin heat sink, while improving the performance factor by up to 23%, despite a moderate increase in pressure drop. A parametric study based on a non-dimensional diameter ratio demonstrates that increasing the frustum mid-section significantly enhances convective heat transfer, achieving up to 73.7% increase in heat transfer coefficient and 45.8% reduction in peak temperature, albeit with increased hydraulic resistance. To address downstream thermal non-uniformity, an isothermal double-frustum (IDF) configuration is introduced, enabling geometry-driven thermal uniformity control through streamwise diameter redistribution. The IDF design effectively suppresses temperature gradients along the flow direction, reducing base temperature non-uniformity and standard deviation by up to 78% and 81%, respectively, while improving the overall thermo-hydraulic performance by 45% relative to the square-fin configuration. The results demonstrate that the proposed DF and IDF configurations provide a robust geometry-based strategy for advanced microchannel heat sink design, offering significant potential for high heat-flux electronic cooling applications.