Using experimental data to estimate the heat transfer and pressure drop of non-Newtonian nanofluid flow through a circular tube: Applicable for use in heat exchangers

This study estimates the effect of functionalized multi walled carbon nanotubes on heat transfer and pressure drop of ethylene glycol-water flow in a tube. For this purpose, at the first, two-variable correlations as functions of temperature and solid volume fraction were proposed to predict the viscosity and thermal conductivity ratio of the nanofluid using experimental data. Then, the relative values of pressure drop and heat transfer coefficient were calculated by employing proposed correlations. Results revealed that the ratio of pressure drop decreased with increasing shear rate while increased with increasing solid volume fraction and temperature. Therefore, F-MWCNTs/EG-water nanofluid was more suitable for applications with higher shear rates. In addition, the ratio of heat transfer coefficient increased with augmentation of solid volume fraction and temperature. This ratio improved to 44%, which corresponded to the volume fraction of 1% and the temperature of 50 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.