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Research Papers: Micro/Nanoscale Heat Transfer

# Prediction of Thermal Conductivity and Convective Heat Transfer Coefficient of Nanofluids by Local Composition Theory

[+] Author and Article Information

Department of Chemical Engineering, College of Engineering, Shahid Bahonar University of Kerman, 76175-133, Kerman, Iran

A. Mohebbi1

Department of Chemical Engineering, College of Engineering, Shahid Bahonar University of Kerman, 76175-133, Kerman, Iranamohebbi2002@yahoo.com

1

Corresponding author.

J. Heat Transfer 133(5), 052401 (Feb 01, 2011) (9 pages) doi:10.1115/1.4003042 History: Received August 29, 2009; Revised November 09, 2010; Published February 01, 2011; Online February 01, 2011

## Abstract

In this study, a new method based on the local composition theory has been developed to predict thermal conductivity, convective heat transfer coefficient, and viscosity of nanofluids. The nonrandom two liquid (NRTL) model is used for this purpose. The effects of temperature and particle volume concentration on thermal conductivity, convective heat transfer coefficient, and viscosity are investigated. The adjustable parameters of the NRTL model were obtained by fitting with experimental data. The results of the local composition theory are compared with the experimental data of CuO/water, $Al2O3$/water, $TiO2$/water, Cu/water, Au/water, Ni/water, $TiO2$/ethylene glycol, and Al/ethylene glycol (EG) nanofluids and a good agreement between the theory and the experimental data is observed. The absolute average deviation of the model for thermal conductivity was 1.51% in comparison to 42% in conventional models. This parameter for viscosity and convective heat transfer coefficient were 2.91% and 2.13%, respectively. Moreover, a new equation for calculating convective heat transfer coefficient of nanofluids is proposed and tested.

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## Figures

Figure 1

Two types of hypothetical pure fluids of binary mixtures

Figure 2

The comparison of calculated thermal conductivity by LCT with experimental data and Maxwell’s model for Al2O3/water, CuO/water, and TiO2/water nanofluids at room temperature

Figure 3

The comparison of calculated thermal conductivity by local composition theory with experimental data for TiO2/EG and Al/EG nanofluids at room temperature

Figure 4

The comparison of calculated thermal conductivity by local composition theory with experimental data for Ni/water and Au/water nanofluids

Figure 5

The comparison of calculated viscosity by local composition theory with experimental data for Al2O3/water and TiO2/water nanofluids at room temperature

Figure 6

Comparison of experimental data of viscosity for various volume concentrations of Al2O3 nanoparticles dispersed in water with respect to temperature and those predicted by local composition theory

Figure 7

The comparison of calculated convective heat transfer coefficient by local composition theory with experimental data for TiO2/water (dp=95 nm) nanofluid

Figure 8

Comparison between the experimental data (19) and the calculated values from Eq. 36 for fully developed laminar and flow for TiO2/water nanofluid

Figure 9

Comparison between the experimental data (19) and the calculated values from Eq. 36 for turbulent flow TiO2/water nanofluid

Figure 10

Comparison between the experimental data and the calculated values from Eq. 36 for SiO2/water nanofluid

Figure 11

Comparison between the experimental data and the calculated values from Eq. 36 for Cu/water nanofluid

## Errata

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