Convective Heat Transfer Enhancement with Nanofluids A State-of-the-Art Review

Abstract

Nanofluids have been utilized to enhance heat transfer rates by researchers and industrials as working fluids in various thermal systems. Base fluids, having low thermal conductivities, are mixed with nanoparticles-1-100 nm diameter particles, which have high thermal conductivities-to form the nanofluids for different applications. Metallic and nonmetallic materials have been used to produce the nanoparticles such as Al2O3, Ag, CuO, Cu, SiO2, and TiO2. These particles can enhance the thermal conductivities of their mixtures even at low concentrations [1, 2]. Nanofluid selection is based on nanofluid properties, sizes, shapes, and volume fractions of the nanoparticles, as well as thermophysical properties of nanofluids, which play important roles on the heat transfer performance [3]. In nanofluid researches, nanofluids were investigated numerically and experimentally. The early studies on nanofluids were mainly focused on the measurements of thermal conductivity. Later, more experimental and numerical studies regarding the convective heat transfer of nanofluids had been developed continuously. Experimental researches have shown that the thermal conductivity enhancements obtained with nanofluids exceed the enhancements obtained by using conventional fluids [1, 4]. © 2016 by Taylor and Francis Group, LLC.