Aerosol are ubiquitous in many areas of scientific interest. They are employed in industrial techniques such as spray drying and fuel injection, in medicine to deliver drugs to the lungs, and play an important role in the atmosphere due to their interaction with radiation and their influence on clouds. A characterisation of the properties and processes common to aerosol in all these fields is facilitated by measurements on single droplets, free of the complicating particle-particle interactions of an aerosol ensemble. This thesis describes a laboratory-based approach to explore the thermodynamic properties and kinetic processes which influence the rate of evaporation and condensation mass transport of volatile and semi-volatile species in aerosol. A new implementation of an electrodynamic balance CEDB), consisting of cylindrical electrodes, was used to tightly confine single aerosol droplets in an electric field . Coupled with elastic light scattering methods, the time-dependence of the radius of droplets undergoing evaporation and condensation was determined. A method for conducting comparative measurements of the evaporation of droplets with different compositions in the EDB was developed, allowing evaporation kinetics to be interpreted with unprecedented accuracy Evaporation measurements were used to determine thermodynamic equilibrium properties of droplets, such as the saturation vapour pressure and hygroscopicity The influence of kinetic limitations in the bulk-condensed phase were investigated, showing that significant slowing of evaporation and condensation occurs under conditions where highly viscous condensed states develop. The influence of interfacial transport kinetics were explored for pure water surfaces and surfactant coated surfaces, demonstrating conclusively that significant limitations to evaporation are only encountered when condensed films form at the surface.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:653067 |
| Date | January 2014 |
| Creators | Davies, James F. |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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