Air filtration simulation with focus on slip effects

L. Cheng, D. Kehrwald, A. Latz, S. Rief, K. Schmidt and A. Wiegmann, Fraunhofer-Institut für Techno- und Wirtschaftsmathematik, Kaiserslautern, Germany

Abstract 

The combined effects of interception, inertia and
diffusion are well known to govern the efficiency of fibrous
filters. Their influence, however, varies with the geometric filter
structure and with the process parameters. Even the most penetrating
particle size, a simplified measure of filter efficiency, varies
significantly around the generally assumed particle diameter of 0.3
Ám. Our filtration model takes into account the filter geometry, flow
velocity and the aforementioned filtration mechanisms. But previously,
interception, inertia and diffusion were always seen as combined
contributors. In order to study individual effects, the simulation
software is now configured to disable one or several effects, and thus
to measure the individual contributions in the simulation just as in
analytical studies. In particular, we illustrate how enhancing the
simulation by slip flow and Cunningham correction for the Brownian
motion of particles below 1 Ám changes the predicted filter
efficiency.


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Last modified: Sat May 24 09:56:24 Eastern Daylight Time 2008