• 한국위험물학회지
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• 제6권2호
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• pp.95-104
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• 2018

Gas-liquid bubble column reactors are extensively used in industrial processes. A detailed knowledge of bubble size distribution is needed for determining the mass transfer in gas-liquid film. Experimental data on bubble size distribution and liquid-side mass transfer coefficient($k_L$) were used to calculate the estimated time to saturation in bubble column reactor. Also, the gas flux was evaluated to the liquid-side mass transfer coefficient($k_L$) and solubility data for hydrogen sulfide($H_2S$) and chlorine($Cl_2$) absorption into water. Simulation results show that $H_2S$ absorption time to 50 % of saturation concentrations are 611 sec and 1,329 sec when bubble diameters are 0.5 mm and 4.5 mm, while absorbing 1 % $H_2S$ gas. In case of $Cl_2$, absorption time range 657 to 1,400 sec when bubble size range 0.5 mm to 4.5 mm, while absorbing 1 % $Cl_2$ gas. Calculated simulation results can be used in the design of emergency relief bubble reactors.

• 한국가시화정보학회지
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• 제17권1호
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• pp.60-68
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• 2019

Flow visualizations have been carried out to analyze the characteristics of bubby flows exhausted from a venturi-type bubble generator with an air vent. For various design parameters and operating conditions of the bubble generator, the images of bubbly flows was recorded using a high-speed camera and a microscope. Then the amount and size distribution of bubble was evaluated by an image processing technique. The results show that for increasing the amount of bubble, it is more effective to reduce the venturi throat than to enlarge the air vent diameter. If the water flow rate increases, the bubble generation rate increases but reaches a status of saturation, whose condition depends on Reynolds number at a given air vent diameter. The bubble size increases as the diameter of venturi throat decreases and Reynolds number increases. However, the air vent diameter is not a significant factor on bubble size.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4395-4407
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• 2023

Bubble columns are widely encountered in several industries, especially in the field of nuclear safety. The Eulerian-Eulerian and the Eulerian-Lagrangian methods are commonly used to investigate bubble columns. Eulerian approaches require additional tasks such as strict volume conservation at the interface and a predefined well-structured grid. In contrast, the Lagrangian approach can be easily implemented. Hence, we introduce a fully Lagrangian approach for the simulation of bubble columns using the discrete bubble model (DBM) and moving particle semi-implicit (MPS) methods. Additionally, we propose a rigorous method to estimate the volume fraction accurately, and verified it through experimental data and analytical results. The MPS method was compared with the experimental data of Dambreak. The DBM was verified by analyzing the terminal velocity of a single bubble for each bubble size. It agreed with the analytical results for each of the four drag correlations. Additionally, the improved method for calculating the volume fraction showed agreement with the Ergun equation for the pressure drop in a packed bed. The implemented MPS-DBM was used to simulate the bubble column, and the results were compared with the experimental results. We demonstrated that the MPS-DBM was in quantitative agreement with the experimental data.

• 해양환경안전학회지
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• 제6권1호
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• pp.69-76
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• 2000

Bubble boom may be a good alternative for the prevention of oil spill pollution due to its easy deployment and clean post-process tasks. The present work is focused on the experimental investigation of air bubble movement for the bubble boom by visualization and quantitative PIV measurements. Bubble plume was generated by adjusting the pressure of pressure vessel ranging 6.7 kpa to 14.7 kpa. The results showed at lower inlet velocity and higher supply air flow rate that bubble boom maintained its containing capability reasonably well up to the maximum containing limit.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1228-1233
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• 2003

The molecular cluster model for the homogeneous bubble nucleation was extended to predict the bubble nucleation events in elastomers, polymers and polymer solutions. For the bubble nucleation in elastomers and polymers, the strain energy overcome by a critical bubble was also considered. The calculation results for the number of bubbles nucleated are in good agreement with observed ones.

• 폴리머
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• 제28권1호
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• pp.51-58
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• 2004

탄성체 (가교된 고분자) 가스가 용해된 고분자 또는 유기 용매에 용해된 고분자 용액에서 기포 생성을 예측하기 위하여 균일한 기포 생성은 고전적인 이론에서의 임계 기포의 생성이 아닌 임계 뭉치의 생성을 통하여 이루어진다는 분자 뭉치 이론을 적용하였다. 또한 탄성체나 고분자 내에서 기포가 생성하는 경우 임계 기포가 극복해야 할 탄성 에너지를 고려하였다. 대략 $10^{8}$∼$10^{12}$개에 달하는 분자 뭉치 이론에 의해 계산된 단위 부피당 생성된 기포 수는 실험치와 잘 일치하였다.

• Architectural research
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• 제2권1호
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• pp.7-15
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• 2000

A bubble diagram is understood as a graphic medium which bridges program and plan in architectural design process. The role of a bubble diagram is either to generate or to explain a plan in relation to its program. Despite the explicit role of a bubble diagram in architectural design process, what a bubble diagram indicates exactly is very ambiguous. Here I attempt to reveal the nature of the bubble diagram more sharply. My main argument is that the ambiguity of a bubble diagram results from the fact that it is used to range two different types of representational formats. Reviewing the theories of shape recognition and shape representations in vision science, I will also argue that the procedural description of architectural design process should be criticized and that the focus of design method research has to be shifted into the representational format of form description in architectural design process.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.353-356
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• 2006

A set of solutions of the Navier-Stokes equation for the gas inside a spherical bubble with heat transfer through the bubble wall permits to predict correctly behavior of an ultrasonically driven bubble in aqueous solutions of sulfuric acid. Calculation results of the minimum velocity of bubble wall and the peak temperature and pressure are in excellent agreement with the observed ones. Further the calculated bubble radius-time curve displays alternating pattern of bubble motion as observed in experiment.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.376-379
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• 2010

Bubble rising phenomenon is widely founded in many industrial applications such as a stream generator in power plant. Many experimental and numerical researches have been already performed to predict dynamic behavior of the bubble rising process. Recently numerical approaches are getting popular since it can offer much detailed information which is almost impossible to obtain from the experiments. Rising bubble could penetrate through the top free surface which makes the problem much more complicate in addition to the phase changing effect even with latest numerical techniques. In this paper, the top free surface effect on rising bubble has been investigated. The gas-liquid interface was explicitly tracked using high-order Level Contour Reconstruction Method(LCRM) which is a hybridization of Front-Tracking and Level-Set method. Break-up behavior of rising bubble at free surface showed different characteristics with initial diameter of bubble.

• 대한기계학회논문집
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• 제19권2호
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• pp.418-426
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• 1995

A bubble-powered microactuator is designed conceptually. And the actuation mechanism due to bubble growth and collapse is studied numerically and analytically. In this analysis, it is estimated that the time lag for bubble formation on micro line heater, the duration of the bubble growth and collapse and the pressure change in actuator due to the bubble evolution. Based on these calculations, the actuator control scheme is visualized. This actuator may be applicable to the system which needs to pump liquid correctly and regularly.