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Open Access Nano Express

A new heat propagation velocity prevails over Brownian particle velocities in determining the thermal conductivities of nanofluids

Kenneth D Kihm13*, Chan Hee Chon2, Joon Sik Lee3 and Stephen US Choi4

Author Affiliations

1 Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA

2 Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada

3 World Class University (WCU) Multiscale Mechanical Design Division, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Korea

4 Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA

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Nanoscale Research Letters 2011, 6:361  doi:10.1186/1556-276X-6-361

Published: 27 April 2011

Abstract

An alternative insight is presented concerning heat propagation velocity scales in predicting the effective thermal conductivities of nanofluids. The widely applied Brownian particle velocities in published literature are often found too slow to describe the relatively higher nanofluid conductivities. In contrast, the present model proposes a faster heat transfer velocity at the same order as the speed of sound, rooted in a modified kinetic principle. In addition, this model accounts for both nanoparticle heat dissipation as well as coagulation effects. This novel model of effective thermal conductivities of nanofluids agrees well with an extended range of experimental data.