Thermophoresis of nanoparticles hotter/colder than the surrounding dilute gases--颗粒学报PARTICUOLOGY

Su, J., Cui, J., Wang, J., & Xia, G. (2022). Thermophoresis of nanoparticles hotter/colder than the surrounding dilute gases. Particuology, 63, 95-102. https://doi.org/10.1016/j.partic.2021.04.018

Thermophoresis of nanoparticles hotter/colder than the surrounding dilute gases

Junjie Su, Jie Cui, Jun Wang ^*, Guodong Xia

MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, Beijing University of Technology, Beijing 100124, China

10.1016/j.partic.2021.04.018

Volume 63, April 2022, Pages 95-102

Received 10 October 2020, Revised 28 January 2021, Accepted 29 April 2021, Available online 19 May 2021, Version of Record 18 November 2021.

E-mail: jwang@bjut.edu.cn

Highlights

• Particle temperature effect on thermophoresis of nanoparticles is studied.

• Theoretical formulas for the thermophoresis on nanoparticles are obtained.

• Error due to equal gas–particle temperature assumption can be larger than 30%.

Abstract

Aerosol particles suspended in a diluted gas with non-uniform temperature distribution are expected to experience a thermophoretic force. In theoretical treatment of thermophoresis, it is usually assumed that the particle temperature is equal to the surrounding gas temperature. However, this might not always be the case. In some particular applications, the particle temperature can significantly differ from the gas temperature. In the present paper, we theoretically investigate the effect of the particle temperature on the thermophoresis of nanoparticles in the free molecule regime. Theoretical formulas for the thermophoretic force and thermophoretic velocity are obtained based on the gas kinetic theory. As examples, a spherical Ag nanoparticle suspended in a dilute He gas is considered, and the Rudyak–Krasnolutski potential is employed to model the gas–particle interaction. It is found that the influence of the particle temperature on the thermophoresis of nanoparticles can be significant. With increasing particle size, the error due to the equal gas–particle temperature assumption can be neglected.

Graphical abstract

Keywords

Thermophoresis; Particle temperature; Nanoparticles; Free molecule regime

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