An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes

Recently, there has been considerable interest in the use of nanofluids for enhancing thermal performance. It has been shown that carbon nanotubes (CNTs) are capable of enhancing the thermal performance of conventional working liquids. Although much work has been devoted on the impact of CNT concent...

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Main Authors:	Sadri, Rad, Ahmadi, Goodarz, Togun, Hussein, Dahari, Mahidzal, Kazi, Salim Newaz, Sadeghinezhad, Emad, Zubir, Nashrul
Format:	Online
Language:	English
Published:	Springer 2014
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006636/

id	pubmed-4006636
recordtype	oai_dc
spelling	pubmed-40066362014-05-07 An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes Sadri, Rad Ahmadi, Goodarz Togun, Hussein Dahari, Mahidzal Kazi, Salim Newaz Sadeghinezhad, Emad Zubir, Nashrul Nano Express Recently, there has been considerable interest in the use of nanofluids for enhancing thermal performance. It has been shown that carbon nanotubes (CNTs) are capable of enhancing the thermal performance of conventional working liquids. Although much work has been devoted on the impact of CNT concentrations on the thermo-physical properties of nanofluids, the effects of preparation methods on the stability, thermal conductivity and viscosity of CNT suspensions are not well understood. This study is focused on providing experimental data on the effects of ultrasonication, temperature and surfactant on the thermo-physical properties of multi-walled carbon nanotube (MWCNT) nanofluids. Three types of surfactants were used in the experiments, namely, gum arabic (GA), sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS). The thermal conductivity and viscosity of the nanofluid suspensions were measured at various temperatures. The results showed that the use of GA in the nanofluid leads to superior thermal conductivity compared to the use of SDBS and SDS. With distilled water as the base liquid, the samples were prepared with 0.5 wt.% MWCNTs and 0.25% GA and sonicated at various times. The results showed that the sonication time influences the thermal conductivity, viscosity and dispersion of nanofluids. The thermal conductivity of nanofluids was typically enhanced with an increase in temperature and sonication time. In the present study, the maximum thermal conductivity enhancement was found to be 22.31% (the ratio of 1.22) at temperature of 45°C and sonication time of 40 min. The viscosity of nanofluids exhibited non-Newtonian shear-thinning behaviour. It was found that the viscosity of MWCNT nanofluids increases to a maximum value at a sonication time of 7 min and subsequently decreases with a further increase in sonication time. The presented data clearly indicated that the viscosity and thermal conductivity of nanofluids are influenced by the sonication time. Image analysis was carried out using TEM in order to observe the dispersion characteristics of all samples. The findings revealed that the CNT agglomerates breakup with increasing sonication time. At high sonication times, all agglomerates disappear and the CNTs are fragmented and their mean length decreases. Springer 2014-03-28 /pmc/articles/PMC4006636/ /pubmed/24678607 http://dx.doi.org/10.1186/1556-276X-9-151 Text en Copyright © 2014 Sadri et al.; licensee Springer. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Sadri, Rad Ahmadi, Goodarz Togun, Hussein Dahari, Mahidzal Kazi, Salim Newaz Sadeghinezhad, Emad Zubir, Nashrul
spellingShingle	Sadri, Rad Ahmadi, Goodarz Togun, Hussein Dahari, Mahidzal Kazi, Salim Newaz Sadeghinezhad, Emad Zubir, Nashrul An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
author_facet	Sadri, Rad Ahmadi, Goodarz Togun, Hussein Dahari, Mahidzal Kazi, Salim Newaz Sadeghinezhad, Emad Zubir, Nashrul
author_sort	Sadri, Rad
title	An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
title_short	An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
title_full	An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
title_fullStr	An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
title_full_unstemmed	An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
title_sort	experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes
description	Recently, there has been considerable interest in the use of nanofluids for enhancing thermal performance. It has been shown that carbon nanotubes (CNTs) are capable of enhancing the thermal performance of conventional working liquids. Although much work has been devoted on the impact of CNT concentrations on the thermo-physical properties of nanofluids, the effects of preparation methods on the stability, thermal conductivity and viscosity of CNT suspensions are not well understood. This study is focused on providing experimental data on the effects of ultrasonication, temperature and surfactant on the thermo-physical properties of multi-walled carbon nanotube (MWCNT) nanofluids. Three types of surfactants were used in the experiments, namely, gum arabic (GA), sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS). The thermal conductivity and viscosity of the nanofluid suspensions were measured at various temperatures. The results showed that the use of GA in the nanofluid leads to superior thermal conductivity compared to the use of SDBS and SDS. With distilled water as the base liquid, the samples were prepared with 0.5 wt.% MWCNTs and 0.25% GA and sonicated at various times. The results showed that the sonication time influences the thermal conductivity, viscosity and dispersion of nanofluids. The thermal conductivity of nanofluids was typically enhanced with an increase in temperature and sonication time. In the present study, the maximum thermal conductivity enhancement was found to be 22.31% (the ratio of 1.22) at temperature of 45°C and sonication time of 40 min. The viscosity of nanofluids exhibited non-Newtonian shear-thinning behaviour. It was found that the viscosity of MWCNT nanofluids increases to a maximum value at a sonication time of 7 min and subsequently decreases with a further increase in sonication time. The presented data clearly indicated that the viscosity and thermal conductivity of nanofluids are influenced by the sonication time. Image analysis was carried out using TEM in order to observe the dispersion characteristics of all samples. The findings revealed that the CNT agglomerates breakup with increasing sonication time. At high sonication times, all agglomerates disappear and the CNTs are fragmented and their mean length decreases.
publisher	Springer
publishDate	2014
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006636/
_version_	1612084267908595712

An experimental study on thermal conductivity and viscosity of nanofluids containing carbon nanotubes

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