Thermophoresis

:: Section 1

Introduction

If you immerse a heated metal rod in smoke, you can observe the smoke particles being repelled away and a particle-free layer is formed as a consequence. The layer is usually thinner than 1 mm and has a clear boundary, as shown in the animation below:

The physics behind this phenomenon are known as thermophoresis. It is a force resulting from a temperature gradient established in the gas medium. An aerosol in that temperature gradient experiences a force in the direction of decreasing temperature. In this module, let's find out the principles of this phenomenon, the parameters that influence the process and its applications.

The content of each section is listed below:

• Section 1 - Introduction
• Section 2 - Thermophoresis Force and Velocity
• Section 3 - Application
• Section 4 - Summary

Resources:

	Environmental Engineers	American Academy of Environmental Engineers
	Chemical Engineers	American Institute of Chemical Engineers
	Mechanical Engineers	American Society of Mechanical Engineers

Valuable Reading:

• W. C. Hinds, Aerosol Technology, 2nd Edition, Wiley Interscience