Numerical simulation of scavenging of an urban aerosol by filtration taking into account the presence of coagulation, condensation, and gravitational settling

Abstract

This work studies the scavenging efficiencies of an average urban aerosol by means of filtration after a given mechanism of removal (coagulation, heterogeneous nucleation, and gravitational settling) as a function of time. Filtration is a simple, versatile, and economical mean for collecting samples of aerosol particles. The capture of aerosol particles by filtration is the most common method of aerosol sampling and is a widely used method for air cleaning. At low dust concentrations, fibrous filters are the most economical means for achieving high-efficiency collection of submicrometer particles. Aerosol filtration is used in diverse applications, such as respiratory protection, air cleaning of smelter effluent, processing of nuclear and hazardous materials, and clean rooms. The process of filtration is complicated, and although the general principles are well known there is a gap between theory and experiment. In this paper, we review filtration in order to provide an understanding of the properties of fibrous and porous membrane filters, the mechanisms of collection, and how collection efficiency and resistance to airflow change with filter properties and particle size.