Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)

This paper is mainly concerned about the heat transfer behaviour of aqueous suspensions of multi-walled carbon nanotubes (CNT nanofluids) flowing through a horizontal tube. Significant enhancement of the convective heat transfer is observed and the enhancement depends on the flow conditions (Reynold...

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Main Authors: Ding, Yulong, Alias, Hajar, Wen, Dongsheng, Williams, Richard A.
Format: Article
Published: Elsevier BV 2000
Online Access:http://eprints.utm.my/9057/
http://dx.doi.org/10.1016/j.ijheatmasstransfer.2005.07.009
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author Ding, Yulong
Alias, Hajar
Wen, Dongsheng
Williams, Richard A.
author_facet Ding, Yulong
Alias, Hajar
Wen, Dongsheng
Williams, Richard A.
author_sort Ding, Yulong
building UTM Library
collection Institutional Repository
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
continent Asia
country Malaysia
description This paper is mainly concerned about the heat transfer behaviour of aqueous suspensions of multi-walled carbon nanotubes (CNT nanofluids) flowing through a horizontal tube. Significant enhancement of the convective heat transfer is observed and the enhancement depends on the flow conditions (Reynolds number, Re), CNT concentration and the pH, with the effect of pH smallest. Given other conditions, the enhancement is a function of axial distance from the inlet, increasing first, reaching a maximum, and then decreasing with increasing axial distance. The axial position of the maximum enhancement increases with CNT concentration and Re. Given CNT concentration and the pH level, there appears to be a Re above which a big increase in the convective heat transfer coefficient occurs. Such a big increase seems to correspond to the shear thinning behaviour. For nanofluids containing 0.5 wt.% CNTs, the maximum enhancement reaches over 350% at Re = 800, which could not be attributed purely to the enhanced thermal conduction. Particle re-arrangement, shear induced thermal conduction enhancement, reduction of thermal boundary due to the presence of nanoparticles, as well as the very high aspect ratio of CNTs are proposed to be possible mechanisms.
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institution Universiti Teknologi Malaysia
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publisher Elsevier BV
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spelling my.utm.eprints-90572009-07-27T03:29:18Z http://eprints.utm.my/9057/ Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids) Ding, Yulong Alias, Hajar Wen, Dongsheng Williams, Richard A. This paper is mainly concerned about the heat transfer behaviour of aqueous suspensions of multi-walled carbon nanotubes (CNT nanofluids) flowing through a horizontal tube. Significant enhancement of the convective heat transfer is observed and the enhancement depends on the flow conditions (Reynolds number, Re), CNT concentration and the pH, with the effect of pH smallest. Given other conditions, the enhancement is a function of axial distance from the inlet, increasing first, reaching a maximum, and then decreasing with increasing axial distance. The axial position of the maximum enhancement increases with CNT concentration and Re. Given CNT concentration and the pH level, there appears to be a Re above which a big increase in the convective heat transfer coefficient occurs. Such a big increase seems to correspond to the shear thinning behaviour. For nanofluids containing 0.5 wt.% CNTs, the maximum enhancement reaches over 350% at Re = 800, which could not be attributed purely to the enhanced thermal conduction. Particle re-arrangement, shear induced thermal conduction enhancement, reduction of thermal boundary due to the presence of nanoparticles, as well as the very high aspect ratio of CNTs are proposed to be possible mechanisms. Elsevier BV 2000 Article PeerReviewed Ding, Yulong and Alias, Hajar and Wen, Dongsheng and Williams, Richard A. (2000) Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids). International Journal of Heat and Mass Transfer, 49 (1-2). pp. 240-250. ISSN 0017-9310 http://dx.doi.org/10.1016/j.ijheatmasstransfer.2005.07.009 10.1016/j.ijheatmasstransfer.2005.07.009
spellingShingle Ding, Yulong
Alias, Hajar
Wen, Dongsheng
Williams, Richard A.
Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title_full Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title_fullStr Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title_full_unstemmed Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title_short Heat transfer of aqueous suspensions of carbon nanotubes (CNT nanofluids)
title_sort heat transfer of aqueous suspensions of carbon nanotubes (cnt nanofluids)
url http://eprints.utm.my/9057/
http://dx.doi.org/10.1016/j.ijheatmasstransfer.2005.07.009
url_provider http://eprints.utm.my/