Particle Growth by Condensation in a System with Limited Vapor

ABSTRACT

Condensational growth of monodisperse aerosols in a system with limited vapor is studied. The equations for particle size and vapor concentration variation due to condensation are derived for the free molecular and continuum regimes, respectively. The corresponding condensation characteristic times for both size regimes are also developed. The particle size increase and vapor concentration decrease in a system with a limited vapor source are examined for varying surface vapor concentration and particle loading. The differences in the characteristic time expression derived in this work and those developed previously for constant particle size and unlimited vapor source are discussed. The expression of the condensation characteristic time developed is used to study the effect of sample aerosol concentration on the operation of the condensation particle counter, and compared to the characteristic times of other mechanisms such as nucleation, coagulation, and chemical reaction. The characteristic time estimation is shown to be a convenient and effective tool for estimating the relative importance of condensation in comparison to other concurrently occurring mechanisms in the system.