Droplet Breakage and Coalescence Processes in an Agitated Dispersion. 2. Measurement and Interpretation of Mixing Experiments

Ross, Seymour L.; Verhoff, F. H.; Curl, Rane L.

doi:10.1021/i160066a006

Cited by 43 publications

(19 citation statements)

References 6 publications

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“…Therefore, these values are considered universal and will be kept unchanged throughout this investigation. However, the value of these constants were found to be several orders of magnitude larger than those obtained by previous authors who used the same model to simulate liquid-liquid dispersions using MATs [50,[54][55][56][57]. The discrepancy depicted in Table 5 is most probably due to the simplifying assumptions used by these authors in which they assumed a uniform local energy dissipation rate throughout the entire volume of the MAT.…”

Section: Matching Model Predictions With Experimental Datamentioning

confidence: 69%

Turbulently flowing liquid–liquid dispersions. Part I: Drop breakage and coalescence

Azizi¹,

Taweel²

2011

Chemical Engineering Journal

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Section: Matching Model Predictions With Experimental Datamentioning

confidence: 69%

Turbulently flowing liquid–liquid dispersions. Part I: Drop breakage and coalescence

Azizi¹,

Taweel²

2011

Chemical Engineering Journal

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“…The appropriate valué of m can only be determined if experimental data is available. Hsia and Tavlarides (1983) found that the truncated normal model proposed by Coulaloglou and Tavlarides (1977) was unable to predict the results obtained by Ross (1971), Verhoff et al (1977), and Ross et al (1978). Consequently, they modified the earlier work, assuming binary break-up and a beta distribution, rather than the truncated normal distribution.…”

Section: Statistical Modelsmentioning

confidence: 94%

A review of statistical models for the break-up of an immiscible fluid immersed into a fully developed turbulent flow

Lasheras

Eastwood

Martı́nez-Bazán

et al. 2002

International Journal of Multiphase Flow

210

180

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We consider the statistical description of the break-up of an immiscible fluid lump immersed into a fully developed turbulent flow. We focus on systems where there is no relative velocity between the continuous and dispersed phases. In this case, particle fragmentation is caused only by turbulent velocity fluctuations. The most relevant models proposed for the particle break-up frequency and for the shape of the daughter particle size distribution are reviewed. Their predictions are compared to recent experimental data, obtained for the break-up of an air cavity immersed into a high Reynolds number, turbulent water jet. Models based on purely kinematic arguments show the best agreement with the experimental data.

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“…Similarly, measurement of bubble sizes in turbulent flows does not provide information on the independent contributions of break-up and coalescence rates, both of which determine bubble size. While various models consider these rate processes independently for the case of liquid-liquid systems (Coulaloglou and Tavlarides, 1977;Ross et al, 1978; Valentas and Amundson, 1966), these models have not been tested due to a lack of experimental data on the individual rate processes. There are also differences in behavior between liquid-liquid and gas-liquid systems which must be considered in modeling bubble coalescence and break-UP.…”

mentioning

confidence: 99%

Bubble coalescence and break‐up in air‐sparged bubble columns

1990

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A phenomenological model is proposed for the rates of bubble coalescence and bubble break-up in turbulent gas-liquid dispersions. Bubble coalescence is modeled by considering bubble collisions due to turbulence, buoyancy, and laminar shear, and by analysis of the coalescence efficiency of collisions. Bubble break-up is analyzed in terms of bubble interactions with turbulent eddies. A method for the measurement of coalescence and break-up events in turbulent systems is described and used to test the validity of the proposed model. The measurement technique relies on the mixing of tracer gases within bubbles upon coalescence, in conjunction with Monte-Carlo simulations of coalescence events. Both distilled water and salt solutions are examined. Favorable agreement is found between the model and the individual coalescence and breakage rates, as well as with data obtained for the average bubble size and bubble size distribution. Michael J. Prince Harvey W. Blanch Department of Chemical EngineeringUniversity of California Berkeley, CA 94720Introduction Gas-liquid contactors find broad application as reactors and separation units in the chemical, mining, pharmaceutical and biochemical industries. In these systems the rate of transport of the gas to the liquid phase often limits productivity and is therefore a critical design criterion. Current design methods rely on empirical correlations which may not be confidently applied beyond the narrow range of operating conditions and geometries over which they were determined.The uncertainty in bubble column design arises from a lack of fundamental understanding of the hydrodynamics and rate processes which govern bubble size and thus interfacial area. Bubble size depends on a balance of coalescence and break-up rates in the vessel. No broadly applicable model for these rate processes in turbulent systems has yet been presented. This has been due to the inability to measure bubble coalescence and break-up in systems where high gas flow rates prevent direct visual observation.The objective of this study is to measure bubble coalescence and break-up rates in turbulent gas-liquid dispersions and to develop a model for these rate processes based on physicochemical and hydrodynamic principles. The ability of the model to adequately predict the individual experimental rate of coales- cence and break-up is used to judge its validity. In addition, the model is tested against its ability to'predict bubble size and bubble size distributions.The coalescence process is analyzed by examination of bubble collision events and the likelihood of collisions resulting in coalescence. Bubble break-up is examined in terms of bubble interactions with turbulent eddies. In addition to the theoretical development, an experimental method for the measurement of bubble coalescence and break-up rates in turbulent systems is described.The effect of inorganic electrolytes on coalescence and break-up rates is also examined. Much of the current interest in the prediction of bubble size stems from the desire t...

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Droplet Breakage and Coalescence Processes in an Agitated Dispersion. 2. Measurement and Interpretation of Mixing Experiments

Cited by 43 publications

References 6 publications

Turbulently flowing liquid–liquid dispersions. Part I: Drop breakage and coalescence

Turbulently flowing liquid–liquid dispersions. Part I: Drop breakage and coalescence

A review of statistical models for the break-up of an immiscible fluid immersed into a fully developed turbulent flow

Bubble coalescence and break‐up in air‐sparged bubble columns

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