Chapter 1 - Introduction to nanofluids

Abstract

The theory of nanofluids (NFs) was first suggested by Choi after performing experimental studies on various nanoparticle suspensions. NFs can be formed by dispersing metal or metallic oxide nanoparticles into selected base fluids, such as water, oils, ethylene, and glycol. Thermal conductivity, viscosity, specific heat, and density of the base fluid as its thermophysical properties can be changed after adding nanoparticles. Many NFs have been investigated to show the high degree of heat exchange with a little shortcoming in pressure drop. The convective heat transfer feature and flow performance of Cu–water NFs in a straight tube has been investigated by Xuan et al., experimentally and they found that Nusselt number could be increased by more than 39% for the NF with 2.0% of Cu nanoparticles volume fraction. Azmi et al. considered the heat transfer coefficient of TiO2 NF in a circular tube under turbulent flow, experimentally. They reported a maximum enhancement of 22.8% at 50°C for Nusselt number at 1.5% particle concentration. Experimental studies by Zhang et al. showed that the maximum heat transfer enhancement of 10.6% could be obtained using Al2O3–water NFs through a circular microchannel.