A comparison between thermophoresis and Brownian effects in thermal precipitation of micro- and nanoparticles

In this paper a comparison is carried out between thermophoresis and Brownian effects in the process of thermal precipitation. A numerical analysis is conducted to characterize the flowfield and particle transport and deposition in a typical thermal precipitator under forced convection condition. To evaluate the flowfield inside the device, steady and incompressible form of the 2-D Navier-Stokes equations are solved. For particles transport and deposition, a Lagrangian particle trajectory analysis procedure is used. Also, thermophoresis and Brownian effects are calculated by the Talbot model and a Gaussian white noise, respectively. The results show that thermophoresis plays a significant role in deposition of nano- and fine microparticles and makes the collection efficiency higher for finer particles. Also, interaction between thermophoresis and Brownian diffusion is found to be important in deposition process of nanoparticles.

Keywords:

Thermophoresis , Brownian diffusion , Particle deposition , CFD