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 µm. 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 µm changes the predicted filter efficiency.
Air filtration simulation with focus on slip effects