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RESEARCH PAPERS: Micro/Nanoscale Heat Transfer

Heat Conduction in Nanofluid Suspensions

[+] Author and Article Information
Peter Vadasz

Department of Mechanical Engineering,  Northern Arizona University, P.O. Box 15600, Flagstaff, AZ 86001peter.vadasz@nau.edu

J. Heat Transfer 128(5), 465-477 (Oct 07, 2005) (13 pages) doi:10.1115/1.2175149 History: Received March 02, 2005; Revised October 07, 2005

The heat conduction mechanism in nanofluid suspensions is derived for transient processes attempting to explain experimental results, which reveal an impressive heat transfer enhancement. In particular, the effect of the surface-area-to-volume ratio (specific area) of the suspended nanoparticles on the heat transfer mechanism is explicitly accounted for, and reveals its contribution to the specific solution and results. The present analysis might provide an explanation that settles an apparent conflict between the recent experimental results in nanofluid suspensions and classical theories for estimating the effective thermal conductivity of suspensions that go back more than one century (Maxwell, J.C., 1891, Treatise on Electricity and Magnetism). Nevertheless, other possible explanations have to be accounted for and investigated in more detail prior to reaching a final conclusion on the former explanation.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 1

(a) An embedded platinum (tantalum) hot wire within a nanofluid suspension in a cylindrical container. (b) Graphical representation of the averaging method for suspended solid particles in a fluid using a REV.

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Figure 2

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−4 and for copper nanoparticles suspended in ethylene glycol. (a) Transient solution for the time range 0.5s<t*<120s; (b) detail within the time range 1s<t*<10s.

Grahic Jump Location
Figure 3

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−5 and for copper nanoparticles suspended in ethylene glycol. (a) Transient solution for the time range 0.5s<t*<100s; (b) detail within the time range 0.5s<t*<5s.

Grahic Jump Location
Figure 4

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−6 and for copper nanoparticles suspended in ethylene glycol. Detail of the transient solution for the time range 0.5s<t*<5s.

Grahic Jump Location
Figure 5

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−4 and for for carbon nanotubes suspended in oil. (a) transient solution for the time range 1s<t*<100s; (b) detail within the time range 1s<t*<10s.

Grahic Jump Location
Figure 6

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−5 and for carbon nanotubes suspended in oil. Detail within the time range 0.5s<t*<5s.

Grahic Jump Location
Figure 7

The dimensionless wire temperature corresponding to the Fourier as well as the DuPhlag solutions as a function of time, on a logarithmic time scale, for a Fourier number of Foq=10−6 and for for carbon nanotubes suspended in oil. Detail within the time range 0.5s<t*<5s.

Grahic Jump Location
Figure 8

The ratio between the “apparent” and “actual” effective thermal conductivities following Eq. 60 and corresponding to copper nanoparticles suspended in ethylene glycol compared with carbon nanotubes suspended in oil for a Fourier number of Foq=10−4

Grahic Jump Location
Figure 9

The ratio between the “apparent” and “actual” effective thermal conductivities following Eq. 60 and corresponding to copper nanoparticles suspended in ethylene glycol compared to carbon nanotubes suspended in oil for a Fourier number of Foq=10−5

Grahic Jump Location
Figure 10

The ratio between the “apparent” and “actual” effective thermal conductivities following Eq. 60 and corresponding to copper nanoparticles suspended in ethylene glycol compared with carbon nanotubes suspended in oil for a Fourier number of Foq=10−6

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