Bubble Coalescence and Gas Transfer in Aqueous Electrolytic Solutions

Lessard, Richard R.; Zieminski, Stefan A.

doi:10.1021/i160038a012

Cited by 374 publications

(240 citation statements)

References 19 publications

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“…(Orvalho et al, 2009;Ruzicka et al, 2008) for a literature survey on this topic (i.e., the influence of inorganic compounds on the gas holdup). The critical concentration is a property of the inorganic compound (i.e., it is unique for each salt, (Lessard and Zieminski, 1971)), is valid for swarm of bubbles (see refs. (Craig et al, 1993;Nguyen et al, 2012)), and is not highly dependent G. Besagni et al Chemical Engineering Science 158 (2017) 509-538 on U G (see refs.…”

Section: Comparison With the Dual Effect Observed In Binary Systems Wmentioning

confidence: 99%

The dual effect of viscosity on bubble column hydrodynamics

Besagni

Inzoli

Guido

et al. 2017

Chemical Engineering Science

112

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A B S T R A C TSome authors, in the last decades, have observed the dual effect of viscosity on gas holdup and flow regime transition in small-diameter and small-scale bubble columns. This work concerns the experimental investigation of the dual effect of viscosity on gas holdup and flow regime transition as well as bubble size distributions in a large-diameter and large-scale bubble column. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, and can be operated with gas superficial velocities in the range of 0.004-0.20 m/s. Air was used as the dispersed phase, and various water-monoethylene glycol solutions were employed as the liquid phase. The water-monoethylene glycol solutions that were tested correspond to a viscosity between 0.9 mPa s and 7.97 mPa s, a density between 997.086 kg/m 3 and 1094.801 kg/m 3 , a surface tension between 0.0715 N/m and 0.0502 N/m, and log 10 (Mo) between −10.77 and −6.55 (where Mo is the Morton number). Gas holdup measurements were used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. An image analysis method was used to investigate the bubble size distributions and shapes for different gas superficial velocities, for different solutions of watermonoethylene glycol. In addition, based on the experimental data from the image analysis, a correlation between the bubble equivalent diameter and the bubble aspect ratio was proposed. The dual effect of viscosity, previously verified in smaller bubble columns, was confirmed not only with respect to the gas holdup and flow regime transition, but also for the bubble size distributions. Low viscosities stabilize the homogeneous flow regime and increase the gas holdup, and are characterized by a larger number of small bubbles. Conversely, higher viscosities destabilize the homogeneous flow regime and decrease the gas holdup, and the bubble size distribution moves toward large bubbles. The experimental results suggest that the stabilization/destabilization of the homogeneous regime is related to the changes in the bubble size distributions and a simple approach, based on the lift force, was proposed to explain this relationship. Finally, the experimental results were compared to the dual effect of organic compounds and inorganic compounds: future studies should propose a comprehensive theory to explain all the dual effects observed.

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Section: Comparison With the Dual Effect Observed In Binary Systems Wmentioning

confidence: 99%

The dual effect of viscosity on bubble column hydrodynamics

Besagni

Inzoli

Guido

et al. 2017

Chemical Engineering Science

112

View full text Add to dashboard Cite

show abstract

“…Laboratory studies have found that spectra of larger bubbles entrained in simulated breaking waves possess an order of magnitude greater number of bubbles in seawater than in fresh water [Haines and •1ohn-son, 1995]. The traditional explanation of these phenomena is that ions in seawater inhibit or prevent coalescence of bubbles [Lessard and Zieminski, 1971;Keitel and Onken, 1982;Craig et al, 1993].…”

Section: Paper Number 1998jc900064mentioning

confidence: 99%

“…Shatkay and Ronen [ 1992] found that the number of bubbles formed in MgSO4 solutions by passing air through a glass frit actually decreased when the concentration of the salt was increased above 2.5 M and that polyvalent MgC12 was no more effective in suppressing coalescence than monovalent NaC1. From their results they suggested that in addition to the mechanisms proposed by Lessard and Zieminski [ 1971 ] coalescence was affected by "bubble flocculation," caused by compression of the electrical double layer at high ionic strength, as well as by ion-ion associations. Hofmeier Kolaini et al [1994] have investigated the production of bubbles from capillary-gravity waves.…”

Section: Paper Number 1998jc900064mentioning

confidence: 99%

Bubble shattering: Differences in bubble formation in fresh water and seawater

Slauenwhite¹,

Johnson²

1999

J. Geophys. Res.

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Abstract. Breaking waves result in very different populations of bubbles in fresh water and seawater. The differences in sizes and numbers of bubbles in the two media cause significant differences in many natural processes including gas transfer and generation of aerosols as well as affect sound and light propagation and ambient sound production. Observed differences in bubble populations in seawater and fresh water have in the past been attributed to coalescence inhibition in seawater, but bubble-shattering studies described here suggest that other factors may be important. When air bubbles are expanded through an orifice at constant pressure drop, they can be made to shatter into clouds of smaller bubbles. We report here measurements showing that the number and size distribution of resulting populations depend on the physical and chemical characteristics of the water samples. In particular, bubbles were found to break up into 4-5 times more small bubbles in seawater than in fresh water. The number of bubbles produced in shattering was found to be a function of salt concentration but was especially sensitive to the types of ions present. In addition, medium from the marine diatom Phaeodactylum tricornutum was found to further double production numbers, and a decrease in temperature from 20øC to 3øC was found to increase bubble production in seawater by nearly 50%. These effects appear to be separate from coalescence inhibition, the factor usually cited for differences in bubble populations in fresh water and seawater.

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“…1. For this case, the ratio of channel width h to particle radius a is about 20. We see that the average nondimensional velocity of the particles over the width of the channel is less than 1, indicating that the presence of the wall causes a reduction in the average velocity of the particles.…”

Section: Numerical Simulations and Comparison With A Standard Kinmentioning

confidence: 80%

“…[8][9][10]13,15 The potential flow approximation is expected to be valid when the Reynolds number based on the bubble radius and characteristic velocity is large compared with unity but the Weber number, the ratio of inertial to surface tension forces, is small enough so that the bubbles are approximately spherical, and the liquid is free of surface-active impurity. [16][17][18][19][20] This somewhat ideal case can be studied experimentally, 21,22 numerically using large scale simulations which account for the hydrodynamic interactions among bubbles, 15 and analytically using the methods of statistical mechanics 23 and kinetic theory of dense granular materials. [24][25][26][27][28][29][30][31][32][33] A complete set of equations of motion derived using these numerical simulations and analytical techniques for spherical bubbles is given by Spelt and Sangani.…”

Section: Introductionmentioning

confidence: 99%

A kinetic theory for particulate systems with bimodal and anisotropic velocity fluctuations

et al. 2008

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Observations of bubbles rising near a wall under conditions of large Reynolds and small Weber numbers have indicated that the velocity component of the bubbles parallel to the wall is significantly reduced upon collision with a wall. To understand the effect of such bubble-wall collisions on the flow of bubbly liquids bounded by walls, a model is developed and examined in detail by numerical simulations and theory. The model is a system of bubbles in which the velocity of the bubbles parallel to the wall is significantly reduced upon collision with the channel wall while the bubbles in the bulk are acted upon by gravity and linear drag forces. The inertial forces are accounted for by modeling the bubbles as rigid particles with mass equal to the virtual mass of the bubbles. The standard kinetic theory for granular materials modified to account for the viscous and gravity forces and supplemented with boundary conditions derived assuming an isotropic Maxwellian velocity distribution is inadequate for describing the behavior of the bubble-phase continuum near the walls since the velocity distribution of the bubbles near the walls is significantly bimodal and anisotropic. A kinetic theory that accounts for such a velocity distribution is described. The bimodal nature is captured by treating the system as consisting of two species with the bubbles (modeled as particles) whose most recent collision was with a channel wall treated as one species and those whose last collision was with another bubble as the other species. The theory is shown to be in very good agreement with the results of numerical simulations and provides closure relations that may be used in the analysis of bidisperse particulate systems as well as bounded bubbly flows.

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Bubble Coalescence and Gas Transfer in Aqueous Electrolytic Solutions

Cited by 374 publications

References 19 publications

The dual effect of viscosity on bubble column hydrodynamics

The dual effect of viscosity on bubble column hydrodynamics

Bubble shattering: Differences in bubble formation in fresh water and seawater

A kinetic theory for particulate systems with bimodal and anisotropic velocity fluctuations

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