Investigations on the Influence of Chemical Compounds on Fog Microphysical Parameters

Abstract

Lab experiments related to artificial fog studies are limited due to instrument sensitivity to small fog and aerosol particles; therefore, the goal of this work is to evaluate aerosol solute effects on fog physical properties in a lab environment. To reach the goal, an automated fog-generating system was designed and that includes controlled chemical compounds dissolved in pure water. In the analysis, the impact of changing the mass concentration of potassium dihydrogen phosphate—KH2PO4, urea-CO(NH2)2, and potassium hexacyanoferrate trihydrate-K3(Fe(CN)6) on fog droplet size spectra is studied, because visibility is directly related to fog droplet spectra and aerosol composition. In the experiment, various microphysical conditions, including fog droplet size and volume concentration, were analyzed as a function of changing aerosol composition/spectra and fixed thermodynamic conditions. The results showed that fog droplet size spectra vary with the addition of chemical impurities to the pure water volume. For example, increasing KH2PO4 concentration compared to distilled water volume resulted in a higher mean particle size, which led to faster droplet settlement, and that resulted in cleaning air more efficiently compared to pure water fog. Overall, both issues and challenges of the experimental fog generating system with respect to water and aerosol solutions resembling CRBN (chemical, radiological, biological, and nuclear agents) characteristics are provided and evaluated.