Multispecies aerosol evolution and deposition in a bent pipe.


Authored by  M Asgari, F Lucci, A Kuczaj

Published in Journal of Aerosol Science     Journal of Aerosol Science 129: 53-70.

ABSTRACT

Many aerosols present in nature (e.g., atmosphere) or artificially generated for various purposes (e.g., inhalation) are composed of liquids that are prone to continuous evolution due to thermodynamical changes of surrounding conditions as for example temperature and humidity. Thermodynamical changes influence the aerosol dynamics causing condensation or evaporation and subsequent aerosol size growth or shrinkage. These evolution mechanisms simultaneously influence the aerosol deposition due to particle size dependent nature of the aerosol deposition mechanisms (i.e., inertial and diffusional deposition). As the experimental measurements of evolving liquid aerosol deposition are challenging, development and validation of computational models allowing aerosol simulations are important to explore and understand the underlying physics. In this manuscript, we present our multispecies evaporation/condensation model implemented in an Eulerian aerosol framework. The model is validated by comparing with the available literature data for droplet evaporation/condensation under controlled conditions. We applied the model to explore the effect of the temperature and humidity variations on the aerosol size change and its consequent influence on the aerosol deposition in a bent pipe for single- and multispecies mixtures. We show influence of condensation on the aerosol deposition efficiency for various particle sizes. Our results demonstrate that particle size growth favoring inertial deposition and inhibiting diffusional deposition can significantly influence the number of depositing particles and result in an increase of the deposited liquid mass on the walls. These effects are caused by subtle interaction of flowing aerosols in the laminar boundary layer with surrounding vapors available for condensation and they are dependent on the gradient of temperature between flowing mixture and walls.

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