Nano Archive

Effects of variable viscosity and thermal conductivity of Al2O3-water nanofluid on heat transfer enhancement in natural convection

Abu-Nada, Eiyad (2009) Effects of variable viscosity and thermal conductivity of Al2O3-water nanofluid on heat transfer enhancement in natural convection. International Journal of Heat and Fluid Flow, 30 (4). 679 - 690.

Full text is not hosted in this archive but may be available via the Official URL, or by requesting a copy from the corresponding author.

Official URL: http://www.sciencedirect.com/science/article/B6V3G...

Abstract

Heat transfer enhancement in horizontal annuli using variable properties of Al2O3–water nanofluid is investigated. Different viscosity and thermal conductivity models are used to evaluate heat transfer enhancement in the annulus. The base case uses the Chon et al. expression for conductivity and the Nguyen et al. experimental data for viscosity which take into account the dependence of these properties on temperature and nanoparticle volume fraction. It was observed that for Ra 104, the average Nusselt number was reduced by increasing the volume fraction of nanoparticles. However, for Ra = 103, the average Nusselt number increased by increasing the volume fraction of nanoparticles. For Ra 104, the Nusselt number was deteriorated every where around the cylinder surface especially at high expansion ratio. However, this reduction is only restricted to certain regions around the cylinder surface at Ra = 103. For Ra 104, the difference in Nusselt number between the Maxwell Garnett and Chon et al. model prediction is small. But, there was a deviation in prediction at Ra = 103 and this deviation becomes more significant at high volume fraction of nanoparticles. The Nguyen et al. data and Brinkman model gives completely different predictions for Ra 104 where the difference in prediction of Nusselt number reached 30%. However, this difference was less than 10% at Ra = 103.

Item Type:Article
Uncontrolled Keywords:Nanofluid; Viscosity; Thermal conductivity; Natural convection; Annulus
Subjects:Material Science > Nanostructured materials
ID Code:8977
Deposited By:SPI
Deposited On:03 May 2010 17:55
Last Modified:03 May 2010 17:55

Repository Staff Only: item control page