Health & Environmental Research Online (HERO)


Print Feedback Export to File
1059290 
Journal Article 
Sulfur dioxide absorption and desorption by large free falling water droplets 
Lepinasse, E; Marion, M; Guella, S; Alexandrova, S; Saboni, A 
2005 
1 
Revue des Sciences de l'Eau
ISSN: 0992-7158 
18 
1 
5-23 
French 
Mass transfer in dispersed media is of interest to fields such as nuclear engineering, process engineering and environmental engineering. It occurs when two phases, not under chemical equilibrium, are in contact. Knowledge of mass transfer mechanisms in the case of gas absorption from and/or into droplets is necessary to understand the scavenging of trace gases in clouds, rain and wet scrubbers. Our studies focus on absorption and desorption phenomena involving free falling water droplets in a mixture of air and gas. For example, acid rain is formed when a drop of rain falls through an atmosphere contaminated with gaseous acid precursors. A similar phenomenon occurs in specific atmospheric scrubbers, where pollution is trapped at the source. In all cases, the transfer of trace gases from the air into the falling droplets is controlled by molecular diffusion and by convection outside and inside the drops. For droplets, falling inside a soluble gas medium, the main transfer resistance is located in the gas phase. A survey of published studies shows that a number of good numerical models exist, as well as experimental correlations for predictions of the mass transfer coefficient in the gas film. For the liquid phase controlled resistance, SABONI (1991) proposed a model based on local scales, interfacial liquid friction velocity and drop diameter. The model was validated experimentally by AMOKRANE et al. (1994). The experimental study and model validation in the case of sulfur dioxide absorption by water droplets falling through air with a high gas concentration (few %) has been described previously in detail by AMOKRANE et al. (1994). 
Pollution Abstracts; Water Resources Abstracts; Aqualine Abstracts; Sulfur; Convection; Fluid Drops; Resistance; Absorption; Diffusion; Films; Acid rain; Mass Transfer; Surveys; Model Studies; Clouds; Pollutant deposition; Gases; Nuclear Engineering; Prediction; Air pollution control; Atmosphere; Sulfur dioxide; Scrubbers; Pollution control equipment; Acid deposition; Environmental Engineering; Mathematical models; Desorption; Velocity; Air pollution; Equilibrium; Friction; Acids; P 0000:AIR POLLUTION; SW 3070:Water quality control; AQ 00002:Water Quality