Effect of mesoscale inhomogeneity and fibers size distribution on the initial stage of deep-bed filtration process

Abstract

Aerosol filtration in fibrous filters is one of the principal methods of accurate removal of particulate matter from gas stream. The classical theory of depth filtration in fibrous structures is based on the assumption of existence of single fiber efficiency, which may be used for calculation of overall efficiency of the filter. There are several reasons for inappropriate estimation of the single fiber efficiency including assumption of negligible effect of presence of neighbouring fibers and perpendicular orientation of the homogenous fibers in filter structure. The aim of this work is to investigate influence of mesoscale inhomogeneity on fibrous filters performance using Digital Fluid Dynamics in models of filters differed by internal structure and to compare obtained results with experimental data. The influence of both, irregularity of structure and fiber size distribution on macroscopic filter performance (initial fractional efficiency, initial pressure drop and their time evolutions) is presented. The neglection of fiber size distribution in theoretical models of filtration efficiency leads to the underestimation of both, filtration efficiency and pressure drop.