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Research Papers: Micro/Nanoscale Heat Transfer

# Convective Performance of Nanofluids in a Laminar Thermally Developing Tube Flow

[+] Author and Article Information
Babajide Kolade, Kenneth E. Goodson, John K. Eaton

Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-3030

J. Heat Transfer 131(5), 052402 (Mar 19, 2009) (8 pages) doi:10.1115/1.3013831 History: Received February 11, 2008; Revised October 07, 2008; Published March 19, 2009

## Abstract

While many of the published papers on nanofluids focus on measuring the increased thermal conductivity of the suspension under static conditions, the convective performance of these fluids has received relatively little attention. The present work measures the effective thermal conductivity of nanofluids under developing convective boundary layer conditions in tubes of diameter 5 mm. The experiments use a hydrodynamically fully developed laminar tube flow in the range $500≤Re≤1600$ with constant wall heat flux. The experiments were validated through measurements on pure de-ionized (DI) water, which results in a thermal conductivity value that agrees within 0.4% of handbook value. The increase in effective thermal conductivity for DI-water/$Al2O3$ nanofluids is 6% for 2% volume concentration of $Al2O3$, which is consistent with the previously reported conductivity values for this sample. For a suspension of multiwall carbon nanotubes in silicone oil, the thermal conductivity is increased by 10% over that of the base fluid for a concentration of 0.2% by volume. Scanning electron microscopy was utilized to examine the structure of the dry state of the nanotubes and elucidate the performance differences of carbon nanomaterials.

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Copyright © 2009 by American Society of Mechanical Engineers
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## Figures

Figure 1

Schematic of experimental setup

Figure 2

Comparison of the measured and calculated temperature profiles in tube for nominal Re=800 and power output of 50 W

Figure 3

Comparison of the measured and calculated temperature profiles in tube for nominal Re=1200 and power output of 50 W

Figure 4

Comparison of temperature rise in stainless steel tube for water and Al2O3 nanofluid at nominal Re = 800 and power input of 50 W

Figure 5

Temperature rise in stainless steel tube for silicone oil and oil/MWCNT nanofluid at nominal Re = 500 and power input of 150 W and 200 W

Figure 6

Effective thermal conductivity for DI-water and DI-water/Al2O3 nanofluid at nominal Re = 800 and power input of 50 W

Figure 7

Effective thermal conductivity of silicone oil and oil/MWCNT nanofluid at nominal Re = 500 and power input of 200 W

Figure 8

Measurement of effective thermal conductivity of silicone oil and oil/MWCNT using parallel plate method (22)

Figure 9

Comparison of effective thermal conductivity of different nanofluids and silicone oil

Figure 10

SEM imaging of Sigma-Aldrich nanoparticles at a magnification of 100,000×. The inset is a 1500× magnification of the same sample.

Figure 11

SEM imaging of alternate carbon nanomaterial at a magnification of 90,000×. The inset is a 1500× magnification of the same sample.

## Errata

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