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Research Papers

Heat Transfer Enhancement of Low Volume Concentration of Carbon Nanotube-Fe3O4/Water Hybrid Nanofluids in a Tube With Twisted Tape Inserts Under Turbulent Flow

[+] Author and Article Information
L. Syam Sundar

Centre for Mechanical Technology
and Automation (TEMA),
Department of Mechanical Engineering,
University of Aveiro,
Aveiro 3810-193, Portugal
e-mail: sslingala@gmail.com

Antonio C. M. Sousa

Centre for Mechanical Technology
and Automation (TEMA),
Department of Mechanical Engineering,
University of Aveiro,
Aveiro 3810-193, Portugal
e-mail: antoniosousa@ua.pt

Manoj Kumar Singh

Centre for Mechanical Technology
and Automation (TEMA),
Department of Mechanical Engineering,
University of Aveiro,
Aveiro 3810-193, Portugal
e-mail: mksingh@ua.pt

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received August 7, 2014; final manuscript received December 12, 2014; published online March 3, 2015. Assoc. Editor: Samuel Sami.

J. Thermal Sci. Eng. Appl 7(2), 021015 (Jun 01, 2015) (12 pages) Paper No: TSEA-14-1183; doi: 10.1115/1.4029622 History: Received August 07, 2014; Revised December 12, 2014; Online March 03, 2015

In this paper, it is estimated the heat transfer coefficient and friction factor for fully developed turbulent flow of carbon nanotube (CNT)-Fe3O4/water hybrid nanofluids flow through a tube with twisted tape inserts at constant heat flux conditions. The nanocomposite of CNT-Fe3O4 was prepared by in situ method; which contains dispersion of carboxylated-CNTs in distilled water followed by mixing of ferrous chloride and ferric chloride in the molar ratio of 2:1. Sodium hydroxide was used as reducing agent to form CNT-Fe3O4 nanocomposite. The detailed surface morphology and magnetic properties were performed by X-ray diffraction and scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The stable hybrid nanofluids were prepared by dispersing nanocomposite in distilled water, and the heat transfer and friction factor experiments were conducted for particle volume concentrations of 0.1% and 0.3%. The results indicate that a maximum of 31.10% enhancement in Nusselt number with a penalty of 1.18-times increase of pumping power was observed for particle concentration of 0.3% at a Reynolds number of 22,000 as compared to base fluid data. The Nusselt number is further enhanced to 42.51% for 0.3% nanofluid flow through a tube with twisted tape of H/D = 5 at a Reynolds number of 22,000 compared to base fluid data. The empirical correlations were proposed for the estimation of Nusselt number and friction factor to match well with the experimental data.

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References

Figures

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Fig. 1

(a) Schematic diagram of an experimental setup. (b) Photograph of twisted tape insert.

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Fig. 2

XRD patterns of CNT, Fe3O4, and CNT-Fe3O4 nanocomposite materials

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Fig. 3

SEM results (a) Fe3O4 nanoparticles and (b) CNT-Fe3O4 nanocomposite

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Fig. 4

(a) Magnetic hysteresis loop of Fe3O4, CNT-Fe3O4 nanocomposite, (b) CNT-Fe3O4/water nanofluid, and (c) CNT-Fe3O4 nanocomposite showing magnetic behavior while dispersed in water

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Fig. 5

Thermal conductivity of different volume concentrations of CNT-Fe3O4 nanofluids

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Fig. 6

Viscosity of different volume concentrations of CNT-Fe3O4 nanofluids

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Fig. 7

Experimental Nusselt number of water data is compared with the data of Gnielinski [37] and Notter and Rouse [38]

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Fig. 8

Experimental Nusselt number of CNT-Fe3O4 nanofluids data is compared with the data of Pak and Cho [2] for Al2O3 and TiO2 nanofluid; Duangthongsuk and Wongwises [9] for TiO2 nanofluid

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Fig. 9

Experimental Nusselt number of CNT-Fe3O4 nanofluids data is compared with the data of Sundar et al. [15] for Fe3O4 nanofluid

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Fig. 10

Experimental Nusselt number of different volume concentrations of CNT-Fe3O4 nanofluid flow in a tube and with twisted tape inserts

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Fig. 11

Experimental Nusselt number of CNT-Fe3O4 nanofluid flow in a tube and with twisted tape inserts data is compared with the data of Naik et al. [29] and Sundar et al. [26]

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Fig. 12

Experimental Nusselt number of CNT-Fe3O4 nanofluid flow in a tube and with twisted tape inserts data is compared with the proposed Nusselt number correlation

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Fig. 13

Experimental friction factor of water data is compared with the data from Eq. (19) of Blasius [39] and Eq. (20) of Petukov [40]

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Fig. 14

Experimental friction factor of CNT-Fe3O4 nanofluids data is compared with the data of Sundar et al. [15] for Fe3O4 nanofluid

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Fig. 15

Experimental friction factor of CNT-Fe3O4 nanofluid flow in a tube and with twisted tape inserts

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Fig. 16

Experimental friction factor of CNT-Fe3O4 nanofluid flow in a tube with twisted tape inserts data is compared with Sundar et al. [26]

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Fig. 17

Experimental friction factor of CNT-Fe3O4 nanofluid flow in a tube and with twisted tape inserts data is compared with the proposed friction factor correlation

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