Brownian-motion-based convective-conductive model for the effective thermal conductivity of nanofluids

Ravi Prasher, Prajesh Bhattacharya, Patrick Phelan

Research output: Contribution to journalArticle

402 Scopus citations

Abstract

Here we show through an order-of-magnitude analysis that the enhancement in the effective thermal conductivity of nanofluids is due mainly to the localized convection caused by the Brownian movement of the nanoparticles. We also introduce a convective-conductive model which accurately captures the effects of particle size, choice of base liquid, thermal interfacial resistance between the particles and liquid temperature, etc. This model is a combination of the Maxwell-Garnett (MG) conduction model and the convection caused by the Brownian movement of the nanoparticles, and reduces to the MG model for large particle sizes. The model is in good agreement with data on water ethylene glycol, and oil-based nanofluids, and shows that the lighter the nanoparticles, the greater the convection effect in the liquid, regardless of the thermal conductivity of the nanoparticle.

Original languageEnglish (US)
Pages (from-to)588-595
Number of pages8
JournalJournal of Heat Transfer
Volume128
Issue number6
DOIs
StatePublished - Jun 1 2006

Keywords

  • Brownian motion
  • Colloid
  • Nanofluid
  • Nanoscale heat transfer
  • Thermal conductivity

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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