Assessment of nanofluids for laminar convective heat transfer: A numerical study

In this article, a numerical study of laminar forced convective heat transfer in a circular tube is presented, incorporating entropy generation and wall shear stress analysis. Three different nanofluids, Al2O3-water, ZrO2-water and TiO2-water, are considered under constant heat flux boundary condition using single phase approach. Performance of nanofluids is compared with the base fluid by keeping the Reynolds number, mass flow rate and discharge criteria constant for various volume fractions of nanoparticles. A non linear dependence of base fluid thermo-physical properties with temperature is considered in this study. For same Reynolds number comparison criteria, the heat transfer coefficient for nanofluids is found to be significantly higher as compared to the base fluid. However, for same mass flow rate and same discharge comparison criteria, an increment in the heat transfer coefficient is found to be insignificant. The performance factor is found to be poor for the nanofluids and also, it decreases with an increase in particle loading. However, it is nearly similar for all kinds of comparisons. The entropy generation decreases for the nanofluids under same Reynolds number comparison, but the decrement is found to be negligible for the other two comparison bases. The wall shear stress increases with an increase in particle loading for all three comparisons. (C) 2015, Karabuk University. Production and hosting by Elsevier B.V.