Enhancement of Heat Transfer in Microchannel Heat Sinks Using Nanofluids

Abstract

Microchannel heat sinks offer a compact way to remove high heat flux from small devices. Their small channels create a large heat transfer area. Nanofluids are often proposed as better coolants for these systems. They can raise thermal conductivity and improve heat removal. Yet they can also raise viscosity, pressure drop, and stability risk. This paper reviews public experimental and numerical studies on heat transfer enhancement in microchannel heat sinks using nanofluids. The review gives more weight to practical studies, because they show what can work in real devices. The literature shows that alumina-water, copper oxide-water, and titanium dioxide-water nanofluids can improve average heat transfer coefficient and reduce thermal resistance under many test conditions. The best gains usually appear at low or moderate particle loading, careful dispersion, and suitable Reynolds number. The gains become weaker when viscosity growth, particle clustering, erosion risk, or pumping power are ignored. Recent studies also show that channel design matters as much as coolant choice. Spoiler cavities, circular passages, and serpentine layouts can change mixing and boundary layer growth. The main finding of this review is simple. Nanofluids can improve microchannel cooling, but only when thermal benefit is judged together with hydraulic cost, long-term stability, and material compatibility. The paper closes with design guidance, research gaps, and a balanced view for future work.