Numerical Simulation of Laminar Convective Heat Transfer and Pressure Drop of Water Based-Al2O3 Nanofluid as A Non Newtonian Fluid by Computational Fluid Dynamic (CFD)

Abstract

The convective heat transfer and pressure drop of water based Al2O3 nanofluid in a horizontal tube subject to constant wall temperature condition is investigated by computational fluid dynamic (CFD) method. The Al2O3 nanofluid at five volume concentration of 0.1, 0.5, 1.0, 1.5 and 2 % are applied as a non Newtonian power law and Newtonian fluid with experimentally measured properties of density, viscosity, thermal conductivity and specific heat capacity. The power law fluid determines the heat transfer coefficient and pressure drop better than that of the Newtonian fluid. The experimentally measured viscosity is used as consistency index and the flow behavior index (n) is computed in various Reynolds number and nanoparticle concentrations in order to minimize the difference between the experimental and computational results. It is revealed that n is a function of nanoparticle concentration and independent of nanofluid velocity and Al2O3 nanofluid behaves as a shear thickening fluid for n>1. Both the experimental and computational results show an increase in the heat transfer coefficient and pressure drop with an increase in the nanofluid concentration. By using the experimental data a correlation for the average Nusselt number estimation based on the dimensionless number (Re and Pr) and nanoparticles concentration (φ) is obtained. The results of this correlation introduce a 1.162 % average absolute deviation.