An experimental determination of thermal conductivity and viscosity of BioGlycol/water based TiO2 nanofluids

Nanofluid as a new brand of cooling fluid consisting of nanometer-sized particles dispersed in base fluid. In this study, nanofluids have been prepared by dispersing TiO2 nanoparticles in different base fluids such as 20:80% and 30:70% by volume of BioGlycol (BG)/water (W) mixtures. Thermal conductivity and viscosity experiments have been conducted in temperatures between 30 degrees C and 80 degrees C and in volume concentrations between 0.5% and 2.0%. Results show that thermal conductivity of nanofluids increases with increase of volume concentrations and temperatures. Similarly, viscosity of nanofluid increases with increase of volume concentrations but decreases with increase of temperatures. The maximum thermal conductivity enhancement among all the nanofluids was observed for 20:80% BG:W nanofluid about 12.6% in the volume concentration of 2.0% at a temperature of 80 degrees C. Correspondingly among all the nanofluids maximum viscosity enhancement was observed for 30:70% BG:W nanofluid about 1.53-times in the volume concentration of 2.0% at a temperature of 70 degrees C. The classical models and semi-empirical correlations failed to predict the thermal conductivity and viscosity of nanofluids with effect of volume concentration and temperatures. Therefore, a nonlinear correlation has been proposed with 5% maximum deviation for the estimation of thermal conductivity and viscosity of nanofluids. (C) 2016 Elsevier Ltd. All rights reserved.