Modelling the Impacts of Shape and Volume Fraction of Nanoparticles on Water Based Nanofluid Flow with Variable Thermophysical Properties

Abstract

In some applications, nano-sized particles are used to enhance heat transfer in thermal energy systems. Two important practical concerns are the shape of the nanoparticles and the volume fraction that could lead to optimal performance. This study investigates the effects which the shape and volume fraction of copper nanoparticles may have on the velocity and temperature of water based nanofluid. To account for more physical reality, we incorporate the variability of the viscosity and thermal conductivity. The Hamilton-Crosser’s model of nanofluid thermal conductivity is also adopted. It is proposed that for a fluid with temperature-dependent thermo-physical properties, the fluid thermal conductivity in the Hamilton-Crosser’s relation should be replaced with a constant (temperature-independent) thermal conductivity. The governing system of nonlinear partial differential equations is solved by using a convergent finite difference scheme. The results show that increasing the volume fraction decreases the velocity but increases the temperature, while copper nanoparticles of spherical shape lead to enhanced temperature than other shapes.