A Numerical Study of Dispersion and Local Exhaust Capture of Aerosols Generated from a Variety of Sources and Airflow Conditions

Abstract

Focus is put on aerosol source parameters and their influence on aerosol dispersion and capture by a local exhaust. The studied parameters were particle diameter, density, and initial velocity. Included in the study was the influence of obstacles and airflow patterns. Direct capture efficiency of an exhaust above the contaminant source was used to compare the influence of the studied parameters. The study was based on a numerical model that computes the particle trajectories, taking inertia, drag forces, gravity, and turbulence into account. The relevance of particle relaxation time, aerodynamic diameter, and stopping distance is discussed. It is concluded that local exhaust capture of passively emitted particles can be described by particle relaxation time and the vertical air velocity at the emission point. The influence on direct capture efficiency from particle initial velocity is limited compared to imposed airflow patterns as jets and cross drafts. A table underneath the contaminant source may impro...