Effect of Thermoporesis on 10-NM-Diameter Nanoparticles in Gas Flow Inside a Tube

Abstract

Nanoparticles that are uniformly dispersed in a Poiseuille (gas) flow inside a tube experience a thermophoretic force if the tube wall temperature is high compared to the temperature of the gas. The use of this thermophoresis effect is advantageous for the transport of nanoparticles in the tube in two ways: (i) it avoids particle adsorption on the wall surface, and (ii) it makes it possible to use a small cross sectional diameter for the flux of particles at the outlet of the tube. So-called gas deposition may benefit from both of these advantages, especially when a small-diameter deposit is desirable. This paper contains examples of calculations of the thermophoretic effect and describes relevant test results. For example, a radial uniform distribution of nanoparticles at the inlet of the tube shrinks to roughly 50 % in cross sectional area near the outlet of gas flow.