| The formation and subsequent breaking of emulsions play important roles in many industrial applications. Although the general mechanism by which emulsions are 'broken', or separated into their two constituent phases, has been well documented, there is a lack of fundamental, quantitative research describing emulsion behavior.; This study provides the means to describe, quantitatively, the effect of hydrodynamic and colloidal forces on a droplet deposition process that is analogous to droplet aggregation. Aggregation is the first stage in any demulsification process.; An impinging jet cell, in which droplets from a flowing emulsion are impinged on a glass microscope slide, was used to study a number of oil-in-water emulsions, as well as one type of nonaqueous (water-in-hydrocarbon) emulsion. The deposition experiments were modeled by solving the governing mass transfer and flow field equations, using analytical expressions from DLVO theory to describe the electric double layer and van der Waals forces.; The results of this study represent the development of a comprehensive data base of experimental measurements that describe: (1) the effect of flow intensity on droplet deposition rates (expressed as Sherwood number, or dimensionless mass transfer). (2) the effect of electrolyte concentration on droplet deposition rates. (3) the effect of collector surface character (hydrophilic, hydrophobic, bitumen-coated) on droplet deposition rates. (4) the effect of dispersed phase viscosity on droplet deposition rates. (5) the effect of stabilizing agent concentration (Athabasca bitumen) on the deposition rates of water droplets suspended in a 4:1 (by volume) mixture of toluene and hexane. (6) the collector surface coverage at high flowrates, using statistical analysis. (7) the use of droplet coagulation studies to complement the results of droplet deposition experiments.; Numerical simulations showed that DLVO theory can provide reasonable predictions for complex emulsion systems. In some situations. such as the nonaqueous emulsion deposition experiments. DLVO theory could not be used to predict the variation of mass transfer rates with the bitumen concentration used to stabilize the emulsion.; This study emphasizes the importance of considering droplet surface structure and characteristics in the assessment of emulsion stability. |
