Experimental studies on the convective heat transfer performance and thermophysical properties of MgO-water nanofluid under turbulent flow

This study present results of experiments on thermal conductivity, viscosity and Turbulent heat transfer behavior of Magnesium Oxide-water nanofluid in a circular pipe, where the volume fraction of nanopartides in the base fluid is less than 1% (low concentration). Pure water and nanofluid with particle volume fraction of 0.0625%, 0.125%, 0.25%, 0.5% and 1% are used as working fluid. It is observed that most conventional models fail to predict the thermal conductivity and dynamic viscosity of the MgO-water nanofluid accurately, especially in case of viscosity. Therefore a new correlation of the dynamic viscosity will be presented based on the obtained experimental results. The experiments are carried out in the fully-developed turbulent regime. The results indicate that addition of low value of nanoparticles to the base fluid motivates the heat transfer to increase remarkably. The measurements also show that the pressure drop of nanofluid is slightly higher than that of the base fluid and does not increase with increasing the nanoparticles volume fraction. In this paper, experimental results have been compared with the existing correlations for nanofluid convective heat transfer coefficient in turbulent regime. Also Nusselt number and friction factor were considered in definition of thermal performance factor. The results show that the thermal performance factor for all cases are greater than unity which indicate that this nanofluid enhances the heat transfer without huge penalty in pumping power. Hence, applying the methods studied here could be considered as a good choice in practical application. (C) 2013 Elsevier Inc. All rights reserved.