The role of thermophoresis in trapping of diesel and gasoline particulate matter
Journal article, 2012

Thermophoresis is the phenomenon by which sub-micron particles suspended in a gas move in the direction of decreasing temperature. It occurs naturally in automotive catalysts and is responsible for improved particle deposition during transient operation when a hot, particle-laden exhaust gas flows through a cool monolith. Although the time-averaged effects of thermophoresis are expected to be relatively small, it is possible that the effect can be enhanced by a properly designed aftertreatment system. In the current work, thermophoretic effects on particle deposition in automotive catalysts are studied by means of numerical simulations. The potential gain in deposition efficiency obtainable by employing thermophoresis is investigated for both laminar and turbulent flow in a standard monolith channel. The monolith is also compared to a plate-to-plate thermal precipitator. We show here that a substantial enhancement of especially the intermediate-sized particulate matter may be obtained by taking advantage of thermophoresis. In addition, we investigate a number of design ideas for thermophoretic particle trapping devices. We also discuss the difficulties involved in using thermophoresis for particle capture, for example that the collecting surface must be cooler than the exhaust gas whereas catalytic activity for the oxidation of soot is still a challenge at low temperatures.

Automotive catalysis

Particulate matter

Computational fluid dynamics

Particle deposition

Thermophoresis

Author

Henrik Ström

Chalmers, Applied Mechanics, Fluid Dynamics

Srdjan Sasic

Chalmers, Applied Mechanics, Fluid Dynamics

Catalysis Today

0920-5861 (ISSN)

Vol. 188 1 14-23

Driving Forces

Sustainable development

Subject Categories

Chemical Process Engineering

Chemical Engineering

Fluid Mechanics and Acoustics

DOI

10.1016/j.cattod.2012.02.023

More information

Created

10/8/2017