The effect of a containing cylindrical boundary on the velocity of a large gas bubble in a liquid

Collins, R.

doi:10.1017/s0022112067001922

Cited by 106 publications

(43 citation statements)

References 5 publications

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“…More recently, Krishna and van Baten (2001) adapted the Davies-Taylor relation for Geldart A powders by adding two multiplication factors. Firstly, they added a size factor (SF) accounting for the influence of the bed diameter on the rise velocity of a single bubble, which was measured by Collins (1967) for gas-liquid systems:…”

Section: Bubble Rise Velocitymentioning

confidence: 99%

Modelling of large-scale dense gas–solid bubbling fluidised beds using a novel discrete bubble model

Bokkers

Laverman

Annaland

et al. 2006

Chemical Engineering Science

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In order to model the complex hydrodynamic phenomena prevailing in industrial scale gas-solid bubbling fluidised bed reactors and especially the macro-scale emulsion phase circulation patterns induced by bubble-bubble interactions and bubble coalescence, a discrete bubble model (DBM) has been developed. In the DBM, the (larger) bubbles are modelled as discrete elements and are tracked individually during their rise through the emulsion phase, which is considered as a continuum. The DBM, originally developed for the description of gas-liquid flows, has been adapted to cope with bubbles with a diameter larger than the size of an Eulerian cell, which is required in view of the large bubble size distribution at higher gas flow rates. Moreover, a new drag model for a single bubble rising in a fluidised bed derived from empirical correlations has been implemented, as well as a simple model to account for bubble coalescence and break-up. The strong advantage of the DBM compared to other models previously reported in the literature for the description of large-scale fluidised beds is that it fully accounts for the two-way coupling between the bubbles and the emulsion phase, which enables direct computation of the emulsion phase velocity profiles. Comparison of the results of simulations ignoring bubble coalescence and simulations taking bubble coalescence properly into account demonstrated the significant effect of bubble coalescence on the large-scale circulation patterns prevailing in bubbling fluidised beds. The simulation results for the lateral profiles of the visible bubble flow rate have been compared qualitatively with experimental results reported by Werther [1974. Influence of the bed diameter on the hydrodynamics of gas fluidized beds. A.I.Ch.E. Symposium Series 70(141), [53][54][55][56][57][58][59][60][61][62]. The effect of the superficial gas velocity on the velocity and porosity profiles has been studied. In general, it can be concluded that the DBM is able to capture the salient features of the hydrodynamics of bubbling fluidised beds. However, further research is required to improve the closure equations for the bubble behaviour, bubble-bubble interactions and bubble coalescence and break-up to enable a complete quantitative description. ᭧

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Section: Bubble Rise Velocitymentioning

confidence: 99%

Modelling of large-scale dense gas–solid bubbling fluidised beds using a novel discrete bubble model

Bokkers

Laverman

Annaland

et al. 2006

Chemical Engineering Science

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“…, ' , For spherical-cap bubbles in confined vessels, an excellent ~ theoretical and experimental study was carried out br Collins (1967aCollins ( , 1967b. He considered tbe flow around a spberical cap bubble and its ' '. associated spherical wake to be given by a doublet·, at.…”

Section: ~9mentioning

confidence: 99%

Bubbles in viscous liquids: shapes, wakes and velocities

1981

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The shapes and terminal velocities of bubbles rising in viscous liquids have been determined. For Morton numbers (M) greater than 4 × 10−3 the drag coefficient and dimensionless bubble shape are functions only of Reynolds number (R). Shape regimes and terminal rise velocities have been correlated. The flow field around a rising bubble was visualized through the hydrogen bubble tracer technique. For M > 4 × 10−3 and R < 110 the bubbles trailed closed, laminar toroidal wakes. For R > 110 the wake was open and unsteady. Streamlines for the flow were obtained by raising a ciné camera at the same speed as the bubble and filming the H2 tracer bubbles. Results are presented for R < 150 and 7·4 × 10−4 < M < 850.

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“…Bubbles with diameters of greater than 60% of the channel diameter will be more of cylindrical shape and might be termed Taylor bubbles. Collins [32] provided a correction term in three parts which links velocities of more isolated bubbles to those filling the column. Subsequently, an alternative, a single continuous equation (tanh function) has been proposed [33].…”

Section: Relationships Characterising Bubble Behaviourmentioning

confidence: 99%

“…Collins [32]; -----Allahwala and Potter [33] As originally proposed, C0 = 1.2 but it was noted that this parameter took higher values as the Reynolds number, Re, decreased [37]. Subsequently [38], this has been quantified as 0 = 2.27…”

Section: Figmentioning

confidence: 99%

Characterisation of an analogue liquid for hydrodynamic studies of gas-ionic liquid flows

Azzopardi

Agunlejika

Zhao

et al. 2017

Chemical Engineering Journal

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Ionic liquids are liquid salts at low temperatures (normally less than 100°C). They are powerful solvents with very low vapour pressure. They have great potentials in many applications such as gas absorption and chemical synthesis. However, they are expensive. This limits extensive studies towards establishing phenomenological models. To address this limitation, an analogue liquid, with properties similar to an ionic liquid, has been identified which on the grounds of cost and safety appears to be suitable.In this paper, the hydrodynamic behaviour of an ionic liquid in a bubble column is compared with those of water and other liquids with similar physical properties. Average gas holdup, bubble coalescence, bubble size and specific interfacial area with different liquids are examined. Gas hold-up was determined by monitoring the change of conductivity between two flush mounted rings. The differences in bubble size and coalescence are revealed by analysing the stills taken from a high speed video camera. The dominant flow pattern in a small diameter column with ionic liquids or other fluids having similar viscosity is slug flow. The small bubbles in the liquid slugs make a smaller contribution to the specific interfacial area than Taylor bubbles. It is observed that Taylor bubbles can coalesce. The hydrodynamics of an ionic liquid in a bubble column can be estimated from that of a fluid with similar physical properties.

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The effect of a containing cylindrical boundary on the velocity of a large gas bubble in a liquid

Cited by 106 publications

References 5 publications

Modelling of large-scale dense gas–solid bubbling fluidised beds using a novel discrete bubble model

Modelling of large-scale dense gas–solid bubbling fluidised beds using a novel discrete bubble model

Bubbles in viscous liquids: shapes, wakes and velocities

Characterisation of an analogue liquid for hydrodynamic studies of gas-ionic liquid flows

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