Gas Exchange Process of a Spherical Bubble Rising in Water

摘要

We investigated the gas exchange process of a spherical bubble rising in water. We developed an experimental system that use a CCD camera coupled with a microscope to follow the rising bubble. By measuring the bubble size and the rising speed from the bubble motion data recorded with a personal computer, we could precisely estimate the gas exchange rate across the bubble-liquid interface. We also calculated the gas exchange process by estimating the drag coefficients and Sherwood number. The measured and calculated change of bubble radius agree well when the bubble is strongly affected by contaminants. The results also show that when the concentration of carbon dioxide in water is small, the normalized equilibrium radius can be estimated by the initial partial pressures in the bubble and by the pressure of dissolved gas in the water.