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A 5. 0 em. diameter column was used for gas absorption. The column contained internal baffling and was operated in a countercurrent mode. Oxygen comprised the gaseous phase and tap water the liquid phase. The column was operated both with and without pulsations. The injection and exhaustion of compressed air to the system provided the pulsation mechanism. The mixing as well as the mass transfer characteristics were examined. A Set of experiments independent of the mass transfer work was carried out in order to study mixing in the column. A refluxing mechanism is uncovered in the mixing experiments. Values for the axial dispersion coefficient, volumetric mass transfer coefficient and reflux ratio are reported over the range of the operating parameters. / Thesis / Master of Engineering (MEngr)

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The contamination of groundwater and soils has been a big issue of great interest and importance to human health. When organic compounds from leaking underground storage tanks or accidental spills on the surface infiltrate into the subsurface environment, they migrate downward through the unsaturated zone. These contaminants are dissolved into groundwater and move with groundwater flow. Thus, there is a need for remediation technologies. Air sparging is relatively cost-effective, as well as an efficient and safe technique for recovering organic contaminants in the subsurface. This technique introduces air into the subsurface system to enhance the volatilization and bioremediation of the contaminant in the groundwater system. In this operating system, the movement of air phase can take place either as a continuous air phase or as discrete air bubbles. However, the present research focused on continuous air phase assumption and mass balance equations of individual phases rather than taking into account the movement of air bubbles and colloidal particle capture on discrete air-water interface. Generally colloidal particles are treated as suspended particles in the water, so the hypothesis is that the rising air bubble can collect the particles and transport them up to the water table where the pump extracts the dirty bubbles from the groundwater system to the processing unit on the ground surface. This dissertation developed a pore-scale study to model the migration of discrete air phase in the presence of colloidal particles captured on the air-water interface. The model was based on the pore-scale balance equation for forces acting on a bubble rising in a porous medium in the presence of colloids. A dimensional analysis of the phenomenon was also conducted to provide a more generalized methodology to evaluate the effect of individual forces acting on an air bubble. The results indicate that the proposed model can predict the terminal velocity of a rising bubble without or with colloidal particles and provide the effect of numbers of colloidal particles, properties of colloidal particles, and solid grain size. The results showed that the terminal velocity of a discrete bubble was affected by the attachment of particles on a bubble, and then the volatile organic compound (VOC) removal rate was changed by the various radii of a bubble and the number of colloidal particles on a bubble.

The contamination of groundwater and soils has been a big issue of great interest and importance to human health. When organic compounds from leaking underground storage tanks or accidental spills on the surface infiltrate into the subsurface environment, they migrate downward through the unsaturated zone. These contaminants are dissolved into groundwater and move with groundwater flow. Thus, there is a need for remediation technologies. Air sparging is relatively cost-effective, as well as an efficient and safe technique for recovering organic contaminants in the subsurface. This technique introduces air into the subsurface system to enhance the volatilization and bioremediation of the contaminant in the groundwater system. In this operating system, the movement of air phase can take place either as a continuous air phase or as discrete air bubbles. However, the present research focused on continuous air phase assumption and mass balance equations of individual phases rather than taking into account the movement of air bubbles and colloidal particle capture on discrete air-water interface. Generally colloidal particles are treated as suspended particles in the water, so the hypothesis is that the rising air bubble can collect the particles and transport them up to the water table where the pump extracts the dirty bubbles from the groundwater system to the processing unit on the ground surface. This dissertation developed a pore-scale study to model the migration of discrete air phase in the presence of colloidal particles captured on the air-water interface. The model was based on the pore-scale balance equation for forces acting on a bubble rising in a porous medium in the presence of colloids. A dimensional analysis of the phenomenon was also conducted to provide a more generalized methodology to evaluate the effect of individual forces acting on an air bubble. The results indicate that the proposed model can predict the terminal velocity of a rising bubble without or with colloidal particles and provide the effect of numbers of colloidal particles, properties of colloidal particles, and solid grain size. The results showed that the terminal velocity of a discrete bubble was affected by the attachment of particles on a bubble, and then the volatile organic compound (VOC) removal rate was changed by the various radii of a bubble and the number of colloidal particles on a bubble.

Proposing a math model and using enthalpy method to solve the temperature and flow field distribution around the bubble. Find the influence for different coefficients.

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Abstract In this study, we use a fisheye lens (180o field of view) and Chare-Couple Device to take the all-sky 6300Å airglow images emitting from ionosphere. By analyzing these Images we can study the phenomenon of equatorial plasma depletions (plasma bubble). Plasma bubbles generate above the magnetic equator; and they drift up to higher altitude and spread to higher latitude area along magnetic lines. The all-sky imaging system was operated at Mt. A-Li (23.511oN, 120.823oE). Because this year is the most active time of sunspots in the solar cycle, we expect that we can take mounts of plasma bubble images in this year.

Heterogeneous nucleation of bubbles on an advancing solidification front during freezing of water containing a dissolved gas has been experimentally and analytically studied. The formation of bubbles resulting from supersaturation of liquids is commonly encountered in different fields such as heat transfer, manufacturing, and bioscience. In this work, sizes of nucleating bubbles and concentration profiles of dissolved oxygen and carbon dioxide gases in water ahead of the solidification front have been measured. From successful comparisons between the measured and predicted critical radii of nucleating bubbles and distributions of dissolved gas content, phenomena of heterogeneous nucleation in a binary weak solution during the freezing process are quantitatively confirmed. The results show that an increase in gas content at the solidification front in the liquid decreases the free energy barrier and critical radii of bubbles that are formed on the solidification front. In the early stage of solidification, sizes of the critical radii decrease and the number of nucleating bubbles increase. As solidification rates decrease later, content of the dissolved gas in the liquid on the advancing interface decreases and the critical radii of nucleating bubbles increase.