Evaporation and crystallization of salt solution droplets

Abstract

The paper proposes a new mathematical model of evaporation and crystallization of salt solution droplets based on the diffusion approximation. The model describes heat and mass transfer processes both between the components of the solution and with the surrounding air. Using a given ratio for the salt concentration in a droplet makes the model fairly simple and, as a result, attractive for implementation in numerical calculations of aerosol dynamics. The control parameters introduced into the model – the number of single crystals in the resulting dry particle and the ratio of the lengths of the sides of a single crystal – can be determined experimentally. Due to this, the model is convenient for analyzing the morphology of crystal structures and optimizing technological processes. In the study, the model predictions were compared with experimental data on the evaporation and crystallization of a droplet of sodium chloride solution at different air humidities. The comparison showed good qualitative and quantitative correspondence between the measured and calculated characteristics. The patterns of change in the droplet temperature over time were calculated, which showed the possibility of the existence of two time intervals with a virtually constant temperature. Due to the lack of similar experimental data for temperature, such behavior requires further study.