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Research Papers: Micro/Nanoscale Heat Transfer

Measurement of Thermal and Electrical Properties of Multiwalled Carbon Nanotubes–Water Nanofluid

[+] Author and Article Information
Abdullah Al-Sharafi, Bekir S. Yilbas

Department of Mechanical Engineering,
King Fahd University of Petroleum and Minerals,
Dhahran 31261, Saudi Arabia

Ahmet Z. Sahin

Department of Mechanical Engineering,
King Fahd University of Petroleum and Minerals,
Dhahran 31261, Saudi Arabia
e-mail: azsahin@kfupm.edu.sa

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received February 18, 2015; final manuscript received February 18, 2016; published online April 5, 2016. Assoc. Editor: Andrey Kuznetsov.

J. Heat Transfer 138(7), 072401 (Apr 05, 2016) (12 pages) Paper No: HT-15-1129; doi: 10.1115/1.4032955 History: Received February 18, 2015; Revised February 18, 2016

The use of high conductive nanoparticles, such as carbon nanotubes (CNT), enhances the thermal and electrical conductivities of the carrier fluid. Depending upon the volumetric concentration of particles and their distribution in the carrier fluid, multifold enhancement of thermal and electrical properties is possible. Therefore, in the present study, thermal and electrical properties of CNT–water mixture are assessed at microscopic level. Special distribution of the CNT in water is obtained experimentally at microscale for different durations of the heating situation. Thermal and electrical properties are predicted numerically incorporating the particle distributions obtained from the experiment. The mass based analysis is also introduced to determine the thermal properties of the mixture. The findings are compared for those obtained from the simulations based on experimentally obtained micro-images. Algebraic equations are introduced to formulate the data obtained from the simulations for temperature dependent properties. It is demonstrated that the mass based estimation of thermal properties are significantly different than those obtained from the experimental based simulations because of the nonuniform particles distribution and their localized conductivity in the carrier fluid.

Copyright © 2016 by ASME
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References

Figures

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Fig. 1

Micro image as obtained from the optical microscope with 1% concentration of CNT in water (a), converted to black and white (b), and meshed using COMSOL multiphysics solver(c)

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Fig. 2

Mesh independence test results: (a) specific heat and (b) density

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Fig. 3

Experimental and numerical results comparison of the effective specific heat of the nanofluid as function of temperature at 1% CNT concentration ratio in water

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Fig. 4

Experimental and numerical results comparison of the effective electrical conductivity of the nanofluid as a function of temperature at 1% CNT concentration ratio in water

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Fig. 5

Contours of: (a) temperature (K) and (b) density (kg/m3) for 1% CNT in water mixture

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Fig. 6

Arrow field of the total heat flux plotted on contours of temperature distribution

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Fig. 7

Contours of x-direction heat flux (W/m2) magnified at two selected locations

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Fig. 10

The effective thermal conductivity of the nanofluid as function of temperature at different CNT concentration ratios in water

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Fig. 8

Effective density of the nanofluid as function of temperature at different CNT concentration ratios in water

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Fig. 9

Numerical results and mathematical expression calculated predictions using Eq. (8) of the effective density of the nanofluid as function of temperature at different CNT concentration ratios in water

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Fig. 14

Contours of electrical potential (volts) in the solution domain for 1% CNT in water mixture

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Fig. 15

Contours of x-direction current density in (A/m2) magnified at two selected locations

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Fig. 16

The effective electrical conductivity of the nanofluid as function of temperature at different CNT concentration ratios in water

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Fig. 17

Numerical results and mathematical expression calculated predictions using Eq. (20) of the effective electrical conductivity of the nanofluid as function of temperature at 0.5% CNT concentration ratio in water

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Fig. 11

Numerical results and mathematical expression calculated predictions using Eq. (12) of the effective thermal conductivity of the nanofluid as a function of temperature at different CNT concentration ratios in water

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Fig. 12

Effective specific heat of the nanofluid as function of temperature at different CNT concentration ratios in water

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Fig. 13

Numerical results and mathematical expression calculated predictions using Eq. (16) of the effective specific heat of the nanofluid as a function of temperature at different CNT concentration ratios in water

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