Modeling Aerosol Rainout -- Effect of Droplet MassTransfer

Abstract

The AIChE Center for Chemical Process Safety has coordinated research efforts aimed at characterizing and predicting the behavior of aerosols during accidental releases. Field tests designed to be used for validation of a predictive model (RELEASE) showed that aerosol rainout was a significant factor under the test conditions. In addition to summarizing the RELEASE model and the data from the field test, Johnson and Woodward (1999) corrected the measured aerosol rainout to account for the experimental conditions. Spicer and Havens (2001) proposed an alternate description of the jet expansion zone that predicted larger initial aerosol drop diameters and resultant larger fraction rainout than had been previously predicted with RELEASE. Since the original RELEASE model ignores mass transfer from the droplets (or droplet evaporation), this paper considers the importance of droplet evaporation (mass transfer) and the influence on RELEASE model predictions. This paper also discusses the jet expansion and droplet formation processes and considers how different models of these phenomena influence the predicted aerosol rainout of the RELEASE model. Agreement between revised RELEASE predictions and observed data are promising.