• Title/Summary/Keyword: 기포상승

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Bubble Properties in Bubble Columns with Electrolyte Solutions (전해질용액 기포탑에서 기포특성)

  • Yoo, D.J.;Lim, D.H.;Jeon, J.S.;Yang, S.W.;Kang, Y.
    • Korean Chemical Engineering Research
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    • v.54 no.4
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    • pp.543-547
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    • 2016
  • Bubble properties such as size (chord length) and rising velocity were investigated in a bubble column with electrolyte solutions, of which diameter was 0.152m and 2.5m in height, respectively. The size and rising velocity of bubbles were measured by using the dual electrical resistivity probe method. Effects of gas and liquid velocities and ionic strength of liquid phase on the size and rising velocity of bubbles were determined. The bubble size increased with increasing gas velocity but decreased with increasing liquid velocity or ionic strength of liquid phase. The rising velocity of bubbles increased with increasing gas velocity and decreased with increasing ionic strength of liquid phase, however, it showed a slight maximum value with varying liquid velocity. The size and rising velocity of bubbles were well correlated with operating variables.

A Study on the Heat Transfer Analysis of High-Temperature Single Bubble in Water (수중 고온 단일 기포의 열전달 해석 연구)

  • SeokTae Yoon
    • Journal of Korea Society of Industrial Information Systems
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    • v.29 no.1
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    • pp.117-123
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    • 2024
  • Bubbles generated in water receive an upward buoyant force due to the density and pressure difference of the surrounding fluid. Additionally, the behavior, shape, and heat exchange process of bubbles vary depending on the viscosity, surface tension, rising speed, and size difference with the surrounding fluid. In this study, we modeled speed, and heat transfer of a high-temperature single bubble rising in a cylindrical water tank. For this purpose, velocity, and temperature of the bubbles were calculated using theoretical equations, to be compared with numerical simulation results. The numerical analysis was performed using a commercial software, and the stability of the numerical analysis with mesh size was confirmed through calculation of the grid convergence index. The numerical analysis of the rising speed and temperature of a single bubble showed the values to converge when the minimum cell size was 1/160 of the bubble diameter, and the temperature decrease was confirmed to be the same as that of the surrounding fluid within 0.05 seconds.

A Review on Size, Shape and Velocity of a Bubble Rising in Liquid (총설: 액체 중에서 상승하는 기포의 크기, 형상 및 속도)

  • Park, Sung Hoon
    • Particle and aerosol research
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    • v.13 no.1
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    • pp.1-10
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    • 2017
  • Accurate prediction of size, shape and velocity of a bubble rising through a liquid pool is very important for predicting the particulate removal efficiency in pool scrubbing, for designing engineering safety features to prepare for severe accidents in nuclear power plants, and for predicting the emission of fission products from MCCI (molten core-concrete interaction) process during severe accidents. In this review article, previous studies on the determination of the size, shape and rising velocity of a bubble in liquid are reviewed. Various theoretical and parameterization formulas calculating the bubble size, shape and velocity from physical properties of liquid and gas flowrate are compared. Recent studies tend to suggest simple parameterizations that can easily determine the bubble shape and rising velocity without iteration, whereas iteration has to be performed to determine the bubble shape and velocity in old theories. The recent parameterizations show good agreement with measured data obtained from experiments conducted using different liquid materials with very diverse physical properties, proving themselves to be very useful tools for researchers in related fields.

Numerical Study on the Flow Characteristics of Bubble Particles in Bubble Reduction Device (기포 저감 장치의 기포입자 유동특성에 따른 수치해석에 관한 연구)

  • Mun, Hyun-Sik;Yoo, Young-Cheol;Park, Sung-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.10
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    • pp.144-149
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    • 2020
  • Bubble reduction devices are intended to solve problems related to the quantitative supply of oil. Therefore, in this study, numerical analysis was conducted to verify the flow characteristics of bubble particles during the operation of a bubble reduction device. As a result of the basic analysis, the area where the rise and fall of bubbles were most active was found, and numerical calculations were performed focusing on the points. Before the numerical calculations, a non-dimensional derivation was performed to secure homogeneity among the variables. Based on the data obtained from non-dimension derivation, 25 variable conditions for each particle size and fluid velocity were set. Through separate calculations, the equation for bubble rise and fall was derived. By calculating the ratio of drag and buoyancy for each variable, if the drag force acting on the bubble was greater than buoyancy, the bubble falls, and bubbles are not reduced. If the buoyancy is larger than drag, the bubble rises, and the bubble is reduced. Through the analysis, the rise and fall of the bubble were confirmed, and the results were consistent with the separate numerical calculations.

Effect of Water on the Lightweight Air-Mixed Soil Containing Silt Used for Road Embankment (도로성토체로 사용된 실트질 계열의 경랑기포혼합토에 대한 물의 영향)

  • Hwang, Joong-Ho;Ahn, Young-Kyun;Kim, Tae-Hyung
    • Journal of the Korean Geotechnical Society
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    • v.26 no.2
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    • pp.23-32
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    • 2010
  • This study was especially conducted to find out the characteristics of the lightweight air-mixed soil (slurry density 10 kN/$m^3$) containing silt related to water. Compression strength, permeability, and capillary height of the lightweight air-mixed soil were studied, and also to support these studies, the structure of that soil was analyzed in detail. Air bubbles of various sizes are inside the lightweight air-mixed soil, and its distribution in a location is almost constant. A numerous tiny pores are inside the air bubbles so that the lightweight air-mixed soil can be saturated with water. Porosity is also estimated through the image analysis. Peak strength of the lightweight air-mixed soil is not dependent on water, but behavior of stress-strain is affected by the water. Permeability is about $4.857{\times}10^{-6}cm/sec$, which is a little bit higher than the clay's permeability. Capillary rise occurs rapidly at the beginning of the test until the lapse of 100 minutes and then its increase rate becomes slow. The capillary rise causes the increase of the density of the lightweight air-mixed soil, and thus it is required to pay attention to this phenomenon during structure design and maintenance of the lightweight air-mixed soil.

Effect of a Thin Wire Insert on the Bubble Rise in a Miniature Tow-Phase Closed Thermosyphon (소형 밀폐형 이상 열싸이펀에서 삽입 세선이 기포상승에 미치는 영향)

  • 김원태;이윤표
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.8 no.1
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    • pp.99-109
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    • 1996
  • Experimental investigations are carried out for the characteristics of bubble rise in the Miniature Two-Phase closed Thermosyphon(MTPCT) with a thin wire insert. The working fluids applied as experimental media are of three kinds: water, methanol, and ethanol. The effects of combination of the inclination with diametric ratio $\alpha$(=d$_{0}$/D$_{I}$) on rising velocity of a large bubble in the thermosyphon are explicitly analyzed. The realm of a movable bubble and the critical value of $\alpha$ are iteratively pursued to interpret the region Figures-of-Break, rooted in the governing physics relations, according to the application of working fluid. Experimental results are compared with those of analysis and critical ranges for $\alpha$ and D$_{I}$ were ascertained from comparisons.isons.

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Fractional gas hold-up in trayed bubble column (Trayed 기포탑 반응기에서 높이에 따른 기포입자의 거동분석)

  • Yang, Jung Hoon;Hur, Young Gul;Yang, Jung-Il;Kim, Hak-Joo;Chun, Dong Hyun;Kim, Byung Kwon;Lee, Ho-Tae;Jung, Heon
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.77.1-77.1
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    • 2011
  • 슬러리 기포탑 반응기는 열 및 물질 전달의 용이성, 낮은 운전비용 및 장치의 간단성의 장점을 가지고 있어서 Fischer-Tropsch 반응, bio-reaction 등에 많이 응용되고 있다. 특히, 반응물은 기체 상태로 반응기에 투입이 되는데, 이 기포입자의 상승하는 힘을 바탕으로 기상/액상/고상이 균일하게 혼합되게 된다. 많은 연구자들이 이러한 기포탑 반응기의 성능을 개선하고자, 다양한 반응기 디자인에 대하여 보고하고 있다. 특히 반응기 내부에 tray를 설치함으로써, 기포 포집율을 증진시기고 액상의 역류를 최소화시키는 연구가 활발히 진행되고 있다. 본 연구에서는, 다양한 기공크기를 갖는 tray를 활용함으로써 높이에 따른 기포 포집율의 변화 및 반응기 내에 기포 입자의 거동 특성에 대하여 살펴보았다.

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A Study on the Behavior of Bubbles in Fluidized Bed (유동층내의 기포거동에 대한 연구)

  • 김용섭
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.5
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    • pp.24-28
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    • 1994
  • In the present paper, the behavior of bubbles in a fluidized bed has been investigated experimentally. The bubble size, distribution of bubble, bubble rising velocity and pressure fluctuation in the fluidized bed are obtained at different air velocity. The results are discussed and compared study the effect of air velocity on the behavior of a bubbles in fluidized bed.

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A Study on the Shape and Movement in Dissolved Air Flotation for the Algae Removal (수중조류제거(水中藻類除去)를 위한 가압부상(加壓浮上)에 있어서 기포(氣泡)의 양태(模態)에 관한 연구(研究))

  • Kim, Hwan Gi;Jeong, Tae Seop
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.4 no.4
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    • pp.79-93
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    • 1984
  • The dissolved air flotation(DAF) has been shown to be efficient process for the removal of algae ftom water. The efficiency of DAF can be affected by the volume ratio of pressurized liquid to sample, the pressure pressurized liquid, the contact time, the appropriate coagulant and its amount, the water temperature, the turbulence of reactor, the bubble size and rising velocity etc. The purpose of this paper is to compare the practical bubble rising velocity with the theoretical one, to investigate the adhesion phenomenon of bubbles and floc, and the influence of bubble size and velocity upon the process. The results through theoretical review and experimental investigation are as follows: Ives' equation is more suitable than Stokes' equation in computation of the bubble rising velocity. The collection of bubble and algae floc is convective collection type and resulted from absorption than adhesion or collision. The treatment efficiency is excellent when the bubble sizes are smaller than $l00{\mu}m$, and the turbulence of reactor is small. In the optimum condition of continuous type DAF the volume ratio of pressurized liquid to sample is 15%, the contact time in reactor is 15 minutes, the pressure of pressurized liquid is $4kg/cm^2$ and the distance from jet needle to inlet is 30cm.

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Numerical Simulation of the Coalescence of Air Bubbles in Turbulent Shear Flow: 1. Model Development (난류전단 흐름에서의 기포응집에 관한 수치모의: 1. 모형의 개발)

  • Jun, Kyung Soo;Jain, Subhash C.
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.6
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    • pp.1357-1363
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    • 1994
  • A Monte-Carlo simulation model is developed to predict size distribution produced by the coalescence of air bubbles in turbulent shear f1ow. The simulation consists of generating a population of air bubbles into the initial positions at each time step and tracking them by simulating motions and checking collisions. The radial displacement of air bubbles in the simulation model is produced by numerically solving an advective diffusion equation. Longitudinal displacements are generated from the logarithmic flow velovity distribution and the bubble rise velocity. Collision of air bubbles for each time step is detected by a geometric test using their relative positions at the beginning of the time step and relative displacements during the time step. At the end of the time step, the total number of bubbles, their positions, and sizes are updated. The computer program is coded such that minimum storages for sizes and positions of bubbles are required.

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