A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions

J. Koo, Yong Tae Kang, C. Kleinstreuer

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

It has been experimentally demonstrated that suspensions of carbon nanotubes (CNTs) and nanofibers (CNFs) significantly increase the thermal conductivity of nanofluids; however, a physically sound theory of the underlying phenomenon is still missing. In this study, the nonlinear nature of the effective thermal conductivity enhancement with the particle concentration of CNT and CNF nanofluids is explained physically using the excluded volume concept. Specifically, the number of contacting CNTs and CNFs could be calculated by using the excluded volume concept, where the distance for heat to travel in a cylinder between the contacting cylinders in the thermal network of percolating CNTs and CNFs increased with the excluded volume. In contrast to the effective thermal conductivity model of Sastry et al (2008 Nanotechnology 19 055704) the present revised model could reproduce the nonlinear increase of the thermal conductivity with particle concentration, as well as the dependence on the diameter and aspect ratio of the CNTs and CNFs. It was found that the alignment of CNTs and CNFs due to the long range repulsion force decreases the excluded volume, leading to both the convex and concave nonlinear as well as linear increase of the thermal conductivity with particle concentration. The difference between various carrier fluids of the suspensions could be explained as the result of the change in the excluded volume in different base fluids.

Original languageEnglish
Article number375705
JournalNanotechnology
Volume19
Issue number37
DOIs
Publication statusPublished - 2008 Sep 17
Externally publishedYes

Fingerprint

Thermal Conductivity
Nanofibers
Carbon Nanotubes
Carbon nanofibers
Carbon nanotubes
Thermal conductivity
Suspensions
Hot Temperature
Nanotechnology
Fluids
Aspect ratio
Acoustic waves

ASJC Scopus subject areas

  • Materials Science(all)
  • Bioengineering
  • Chemistry(all)
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions. / Koo, J.; Kang, Yong Tae; Kleinstreuer, C.

In: Nanotechnology, Vol. 19, No. 37, 375705, 17.09.2008.

Research output: Contribution to journalArticle

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