Experimental study of thermal conductivity and convective heat transfer enhancement using CuO and TiO2 nanoparticles

Abstract

Heat transfer characteristics of CuO/water and TiO2/water nanofluids were measured in a shell and tube heat exchanger under laminar and turbulent flow condition. In shell and tube heat exchanger, water based CuO and TiO2 based nanofluids with 0.02%, 0.04% and 0.06% volume fraction have been used as working fluids for different flow rates of nanofluids. This enhancement was investigated with regard to various factors; concentration of nanoparticles, types of base fluids, sonication time and temperature of fluids. The effects of Nusselt number and Reynolds number of suspended nanoparticles, on the heat-transfer characteristics were investigated. The experimental results have been compared to those of Dittus–Boelter correlation, Xuan & Li and Gnielinski correlation for the laminar and turbulent flow region. Low thermal conductivity is a major concern in the development of the energy-efficient heat transfer fluid. In this paper, the effect of CuO and TiO2 nanoparticles on the thermal conductivity of base fluids like monoethylene glycol and water was studied. The nanofluids showed an enhancement in effective thermal conductivity, and overall heat transfer coefficient. The thermal conductivity measurement has been made for different concentrations and temperatures. As the concentration of nanoparticles increased, there was a significant enhancement in thermal conductivity and overall heat transfer due to more interaction between particles. It was also observed an improvement in thermal conductivity of base fluid as temperature increases.