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Abstract
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This study numerically investigates the hydrothermal performance of a biologically prepared silver-water nanofluid in a microchannel heat sink with various dimple geometries, using the two-phase mixture model. Six dimple shapes – spherical, elliptical, egg-shaped, and super-spherical – are analyzed over Reynolds numbers from 500 to 2000 and nanoparticle concentrations up to 1%. The novelty of this work lies in combining surface geometry optimization with biologically synthesized nanofluids, offering an environmentally friendly and efficient cooling approach not previously reported. Results showed that optimized dimples enhance heat transfer by intensifying boundary layer disruption, with spherical dimples reducing the maximum CPU temperature by up to ~0.4 K and enhancing the heat transfer coefficient by ~8–9% compared to a smooth wall at Reynolds number of 2000. Egg-shaped dimples also performed well, while elliptical geometries sometimes decreased the heat transfer coefficient by ~2%. On the hydraulic side, the inclusion of silver nanoparticles decreased pumping power by ~10%, and in specific cases (e.g. egg-shaped dimples at low Reynolds number), the pressure drop was even lower than that of the smooth wall. Overall, the findings provide practical guidance for designing compact and energy-efficient cooling systems for electronic devices and microchannel-based heat exchangers.
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