Theoretical study of aerosol filtration by nucleopore filters: The intermediate crossover regime of Brownian diffusion and direct interception

We study the problem of aerosol filtration by formulating a unified approac h that incorporates the dominant mechanisms of particle capture in cylindri cal pores. The theoretical approach presented here takes into account the e ffects of flow slip at the pore wall and predicts an enhanced efficiency in the intermediate crossover regime between Brownian diffusion and direct in terception. We also suggest how the results obtained for cylindrical pores can be used to estimate the efficiency of granular ceramic filters in the r egion of the most penetrating particle size, where the enhanced efficiency effects are strongly amplified by the large number of pores, or more genera lly unit bed elements, acting in series. (C) 2001 Academic Press.