Coupling between mass transfer from dissolving bubbles and formation of bubble-surface wave

The dynamic process of gas dissolution from a single CO2-containing bubble into a liquid is studied for bubbles with surface oscillations. Both experimental and theoretical analyses are conducted. In the experiment, the bubble behavior is continuously monitored by holding the bubble in the liquid flowing downward. For detailed observation of the bubble-surface motion, high-speed imaging is applied. The fluctuating surface, often associated with bubble deformation, is viewed as a surface with propagating waves. The dissolution rate, claimed to be largely influenced by the liquid-phase contamination level, is found to depend more inherently on the extent of wave motion. The persisting wave propagation is only observable for large bubbles with distinctive rim. The lower critical diameter is roughly 4 mm. The theoretical analysis lays its basis on modeling the dissolution process of a singled bubble comprising two components of different solubility. The model demonstrates good predictive capability for the time variations in bubble diameter and gas-phase composition, the latter being measured via gas chromatography by sampling the gas from the suspended bubble. For pure CO2 bubbles in the liquid pressurized using N-2, in particular, the complete dissolution process is characterized by little change in the CO2 Mole fraction near unity followed by a transitory decrease down to zero. (C) 2001 Elsevier Science Ltd. All rights reserved.