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Bubble Velocity

The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

S G Bankoff – 1st expert on this subject based on the ideXlab platform

  • structure of air water bubbly flow in a vertical pipe ii void fraction Bubble Velocity and Bubble size distribution
    International Journal of Heat and Mass Transfer, 1993
    Co-Authors: S G Bankoff

    Abstract:

    Abstract In a companion paper (Liu and Bankoff, Int. J. Heat Mass Transfer 36, 1049–1060 (1993)) measurements were presented of liquid-phase Velocity and turbulence properties in air-water bubbly upflow under a range of flow conditions. In this paper measurements of the radial profiles of void fraction, Bubble Velocity and bubbly size, using a miniature dual-sensor resistivity probe, under the same conditions are presented. A new digital processing method, based on threshold combinations of level and slope, was developed for phase identification by the resistivity probe. Local mean Bubble sizes ranged from 2 to 4 mm. The profiles of void fraction, Bubble frequency and Bubble size are found to show distinct peaks near the wall, becoming flat at the core. Experimental findings and parametric trends based on the effects of superficial velocities of both phases are summarized and discussed.

  • Structure of air-water bubbly flow in a vertical pipe—II. Void fraction, Bubble Velocity and Bubble size distribution
    International Journal of Heat and Mass Transfer, 1993
    Co-Authors: S G Bankoff

    Abstract:

    Abstract In a companion paper (Liu and Bankoff, Int. J. Heat Mass Transfer 36, 1049–1060 (1993)) measurements were presented of liquid-phase Velocity and turbulence properties in air-water bubbly upflow under a range of flow conditions. In this paper measurements of the radial profiles of void fraction, Bubble Velocity and bubbly size, using a miniature dual-sensor resistivity probe, under the same conditions are presented. A new digital processing method, based on threshold combinations of level and slope, was developed for phase identification by the resistivity probe. Local mean Bubble sizes ranged from 2 to 4 mm. The profiles of void fraction, Bubble frequency and Bubble size are found to show distinct peaks near the wall, becoming flat at the core. Experimental findings and parametric trends based on the effects of superficial velocities of both phases are summarized and discussed.

J A Finch – 2nd expert on this subject based on the ideXlab platform

  • gas holdup and single Bubble Velocity profile
    International Journal of Mineral Processing, 2011
    Co-Authors: Abdollah Rafiei, M Robbertze, J A Finch

    Abstract:

    Abstract Single Bubble Velocity profile (Velocity vs. distance) has been measured for a 1.45 mm diameter Bubble to try to explain reported differences in gas holdup in two systems: F150 vs. 1-pentanol, and MIBC vs. NaCl. It was found that in F150 the Bubble slowed rapidly to reach the terminal Velocity stage of the profile while in 1-pentanol the Bubble remained in the deceleration stage and was consequently moving faster, at almost twice the speed. The lower rise Velocity in F150 means longer Bubble residence time and corresponding higher gas holdup than with 1-pentanol, as reported. In the second system, the Bubble in MIBC reached terminal Velocity more rapidly than in NaCl which agrees with the reported higher gas holdup in MIBC compared to NaCl. An implication for gas holdup evaluation is that the value may depend on the part of the Velocity profile over which it is measured. Possible exploitation of this reagent effect on Bubble rise Velocity in flotation is considered.

  • temperature effect on single Bubble Velocity profile in water and surfactant solution
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003
    Co-Authors: Yanyan Zhang, J A Finch

    Abstract:

    Abstract Surfactants called frothers control Bubble properties in flotation. Two properties of single Bubbles, the rise Velocity profile (Velocity vs. time from release) and terminal Velocity, are investigated as a function of temperature (6–45 °C) in water and solutions of Triton X-100 (12.5×10−5 mol m−3) and Dowfroth 250 (0.06 and 0.25 ppm). The Bubbles sizes (diameter) were 130. This corresponds to the finding of Karamanev [AIChE J. 40 (1994) 1418], namely that the drag coefficient is constant (∼0.95) for this Re region. The profile showed the time to reach constant Velocity tended to decrease as temperature increased. This is analyzed by considering factors that may increase the mass transfer rate of the surfactant. Some observations are offered of possible relevance to flotation.

  • Bubble Velocity profile and model of surfactant mass transfer to Bubble surface
    Chemical Engineering Science, 2001
    Co-Authors: Yongqin Zhang, John B Mclaughlin, J A Finch

    Abstract:

    Abstract Single Bubble Velocity profiles for a 0.8 mm diameter Bubble in solutions of Triton X-100 are simulated by solving the Navier–Stokes equation combined with the Marangoni effect under pseudo-steady state conditions assuming the stagnant cap model and applying different mass transfer control steps. The fit between the experimental and simulated Velocity profiles indicated that the mass transfer mechanism for Triton X-100 from bulk solution to the surface of a rising Bubble is boundary layer mass transfer controlled.

Robert F. Mudde – 3rd expert on this subject based on the ideXlab platform

  • Bubble Velocity, size, and interfacial area measurements in a Bubble column by four‐point optical probe
    Aiche Journal, 2008
    Co-Authors: Muthanna H. Al-dahhan, M P Dudukovic, Robert F. Mudde

    Abstract:

    The four-point optical probe is applied in a Bubble column with an air–water system to investigate the Bubble properties (local gas holdup, Velocity, chord length, specific interfacial area, and frequency) over a range of gas superficial velocities. Both Bubbles moving upward and downward are recorded and measured as opposed to only upward Bubbles measured and reported in other studies involving probes. The probe worked efficiently in both bubbly flow and highly churn-turbulent flow at very high superficial gas velocities. Bubble properties at the conditions of churn-turbulent flow are obtained and investigated for the first time. The changes in the Bubble Velocity distribution, Bubble chord length distribution, and specific interfacial area with superficial gas Velocity, sparger design, and with axial and radial positions in the column are discussed. © 2007 American Institute of Chemical Engineers AIChE J, 2008

  • Bubble Velocity size and interfacial area measurements in a Bubble column by four point optical probe
    Aiche Journal, 2008
    Co-Authors: Muthanna H Aldahhan, M P Dudukovic, Robert F. Mudde

    Abstract:

    The four-point optical probe is applied in a Bubble column with an air–water system to investigate the Bubble properties (local gas holdup, Velocity, chord length, specific interfacial area, and frequency) over a range of gas superficial velocities. Both Bubbles moving upward and downward are recorded and measured as opposed to only upward Bubbles measured and reported in other studies involving probes. The probe worked efficiently in both bubbly flow and highly churn-turbulent flow at very high superficial gas velocities. Bubble properties at the conditions of churn-turbulent flow are obtained and investigated for the first time. The changes in the Bubble Velocity distribution, Bubble chord length distribution, and specific interfacial area with superficial gas Velocity, sparger design, and with axial and radial positions in the column are discussed. © 2007 American Institute of Chemical Engineers AIChE J, 2008

  • Bubble Velocity and Size Measurement with a Four‐Point Optical Fiber Probe
    Particle & Particle Systems Characterization, 2003
    Co-Authors: S Guet, Robert F. Mudde, Robbert V Fortunati, G Ooms

    Abstract:

    The possibility to measure the Velocity and size of individual Bubbles in a high-void fraction bubbly flow is investigated by using a four-point optical fiber probe. The air Bubbles have an initial spherical equivalent diameter ranging from 4 to 10 mm and the void fraction is up to 0.3. Firstly, single Bubble experiments show that intrusiveness effects, i.e. Bubble deformations due to the probe, are negligible provided that the Bubble approaches the probe at the axis of the central fiber. A selection criterion is utilized for multiple Bubble experiments. A good compromise can be found between the required accuracy, the duration of the measurements and the number of validated Bubbles required for reliable statistical averaging. In an air-water high-void fraction vertical bubbly pipe flow, the void fraction obtained with the instrument is found to be in good agreement with both local single-fiber probe measurements, and with the volume average void fraction obtained from pressure gradient measurements. The area average volumetric gas flow rate, based on the Bubble Velocity and void fraction as measured with the four-point probe, agree with the measured gas flow rate. Also, the liquid Velocity is measured by means of a laser-Doppler anemometer, to investigate the slip Velocity. The results show that reliable and interesting measurements can be obtained by using a four-point optical fiber probe in high void fraction flows.