Elucidating the Influence of Bubble Surface Area on Mass Transfer Kinetics in Gas/Liquid Systems

Abstract

The separation of gas from liquid and the hydrodynamic phenomena that govern this behaviour has numerous engineering applications, particularly in the field of hydrocarbon separations where such information is critical for designing separation equipment. In these systems, liquid is typically super-saturated with a gas under pressure, and the rate at which this gas exits the liquid is needed in order to properly predict the residence time required for separation. Several physical parameters govern the separation behaviour including the presence of bubbles, surfactants, and emulsions. This presentation specifically addresses the role that bubble surface area plays in determining the mass transfer rate of gas exiting liquids. The influence of viscosity and surface tension are also explored in the context of bubble generation. An optical technique was developed and validated to determine bubble surface area using a highdefinition camera. By utilizing a unique experimental setup that facilitates the measurement of mass transfer rates at elevated pressures in conjunction with quantitative visual observations, data is obtained that reveals the connection between bubble surface area and mass transfer. Data will also be presented for systems that include surfactants, particles of varying wettability, and emulsions. The outcomes of this work will improve understanding of the processes that govern gas evolution in super-saturated conditions, thereby leading to improved designs that facilitate more efficient separation.