The characteristics of convective heat transfer in microchannel heat sinks using Al2O3 and TiO2 nanofluids

The present study aims to provide an overall analysis about nanofluids flowing through microchannel heat sinks. Al2O3 and TiO2 nanofluids based on deionized water with particle volume fractions of 0%, 0.1%, 0.5%, 1.0% were prepared by the two-step dispersion method. Nonionic surfactant polyvinylpyrrolidone (PVP) was added into the nanofluids to avoid particle aggregation and enhance stability. An ImageIR 3350 was used to get the temperature distribution on the substrate of microchannel heat sinks. The results reveal that the thermal conductivity and dynamic viscosity of Al2O3 and TiO2 nanofluids are both improved with the increase of particle volume fraction. Compared with a rectangular microchannel heat sink, the performance of heat transfer in fan-shaped microchannel heat sink is more strengthened using Al2O3 nanofluids. The thermal motion of nanoparticles could promote the interruption of laminar flow and intensify the heat transfer between fluids and channel walls. The cyclical change with a fixed period on equivalent diameter could also help destroy the boundary layers. (C) 2016 Elsevier Ltd. All rights reserved.