Experimental and theoretical analysis of axial dispersion in the liquid phase in external-loop airlift reactors

Vial, Christophe; Poncin, Souhila; Wild, Gabriel; Midoux, N.

doi:10.1016/j.ces.2005.04.028

Cited by 34 publications

(20 citation statements)

References 33 publications

(61 reference statements)

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“…published showing the capability of handling the complex problem of multiphase flow in ALRs (97,133,274,(331)(332)(333)(334)(335)(336)(337)(338)(339)(340)(341)(342)(343)(344). CFD gives much more detailed information, reaching the level of local velocities and local holdup (Fig.…”

Section: Computational Fluid Dynamics Cfd Tools Have Beenmentioning

confidence: 99%

Bioreactors: Airlift Reactors

Merchuk

Camacho

2010

Encyclopedia of Industrial Biotechnology

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ALRs are popular in modern bioprocess research and development and, in many cases, they have found industrial uses. The distinctive characteristics of ALRs are conferred by the fluid dynamics of the liquid‐gas or liquid gas‐solid mixtures: holdup, liquid velocity, and mixing in the riser, gas separator, and downcomer. Only a correct understanding of the interconnection of these regions can make possible the scale‐up of a laboratory device, to pilot or industrial size. Several correlations are available in the literature for the prediction of the fluid dynamic characteristics of the reactor and of the mass and heat transfer coefficients, and a selection is presented in this review. Significant progress has been made in the application of modern computational tools to the simulation and design of ALRs. In parallel, innovative and sophisticated methods have been applied to obtain a deeper insight into the mechanisms of fluid motion and the flow patterns in the reactor. However, no single research group has managed to cover all the variables over a wide range. The engineer confronting scale‐up or de novo design of an ALR must analyze the validity of the correlations and computation methods used for the calculations.

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Section: Computational Fluid Dynamics Cfd Tools Have Beenmentioning

confidence: 99%

Bioreactors: Airlift Reactors

Merchuk

Camacho

2010

Encyclopedia of Industrial Biotechnology

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“…Weiland and Onken [12], Verlaan [13], Gavrilescu and Tudose [14], and Vial et al [15] have performed experimental studies and reported values of axial dispersion coefficients in the risers of external loop airlift reactors. Joshi et al [16] have done a detailed hydrodynamic modeling of different sections of external loop air lift reactors and have proposed a unified correlation for the axial dispersion coefficient D L .…”

Section: Introductionmentioning

confidence: 99%

Effect of Liquid Velocity on Axial Mixing in Gas‐Liquid Dispersions: A CFD Simulation

Roy

Joshi

2006

Chem Eng & Technol

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A CFD analysis has been carried out to elucidate the characteristic features of axial mixing in gas-liquid dispersed upflow when the flow changes between two extremes: from bubble column, with very low/no liquid velocity, to pipe flow with very high liquid velocity. The CFD model was validated by simulating flow both in multiphase and in single phase. An agreement was observed between the predictions and the experimental data available in the published literature. The validated CFD model has been extended for the simulation of the axial dispersion coefficient for both multiphase and single phase. CFD predictions of the axial dispersion coefficient show good agreement with experimental values published in the literature. A systematic numerical study was done by varying the superficial liquid velocity, from a very low value to a very high value, to understand its effect on axial dispersion.

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“…The density difference between riser and down-comer produces a driving force which causes the liquid circulation [5][6][7]. Suitable heat and mass transfer, simple design concept, high and flexible capacity, low shear rate, high mixing performance, closer contact between the phases, shorter reaction time, long life time, low energy consumption, and low maintenance cost are the most important advantages of such reactors [8][9][10]. Bubble diameter and flow regime are two important parameters that have been neglected in many researches; on the other hand, they are two significant items in simulation and evaluation of simulation results validity, respectively [11].…”

Section: Introductionmentioning

confidence: 99%

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in an airlift reactor

Sajjadi

Moraveji

Davarnejad

2011

Front. Chem. Sci. Eng.

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In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%-1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/ v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

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Experimental and theoretical analysis of axial dispersion in the liquid phase in external-loop airlift reactors

Cited by 34 publications

References 33 publications

Bioreactors: Airlift Reactors

Bioreactors: Airlift Reactors

Effect of Liquid Velocity on Axial Mixing in Gas‐Liquid Dispersions: A CFD Simulation

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in an airlift reactor

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