Experimental and Numerical Evaluation of Curved Microchannel Heat Sinks Utilizing Alumina-Water Nanofluids for High-Power LED Array Cooling

Abstract

High-power light-emitting diode (LED) arrays generate extreme heat fluxes exceeding 180?" W/cm" ?^2 over micro-scale active footprints. Inadequate thermal dissipation drastically reduces luminous efficacy, causes color temperature drift, and accelerates catastrophic junction failure. This paper investigates the fluid flow and heat transfer performance of wavy sinusoidal microchannel heat sinks (WMHS) operating with functionalized alumina-water (?"Al" ?_2 "O" _3 "-water" ) nanofluids (0.2" vol" %" to " 0.8" vol" %). The periodic curvature of sinusoidal channels generates secondary flow structures (Dean vortices) that disrupt thermal boundary layers and enhance transverse fluid mixing. Conjugate heat transfer simulations, validated against experimental measurements, demonstrate that combining a 0.5" vol" %?" Al" ?_2 "O" _3 "-water" nanofluid with wavy microchannel geometries at Re=900 achieves a 36.2% reduction in total thermal resistance compared to pure water in straight microchannels. The average Nusselt number increases by up to 49.5%, accompanied by a 15.8% increase in pressure drop penalty. Local junction temperature non-uniformity across the LED substrate is reduced to 3.5" K" . Hydrodynamic boundary dynamics, thermal performance evaluation metrics, limitations, and future research scopes are comprehensively discussed.

KEYWORDS: Sinusoidal Microchannel, Alumina Nanofluid, Dean Vortices, LED Thermal Management, Conjugate Heat Transfer, Nusselt Number