A study on liquid‐liquid dispersions in a continuous mixer via computational fluid dynamics (CFD) simulation combined with population balance model (PBM)

Tang, Qiao; Ye, Sishi; Wang, Yundong; Liu, Zuohua

doi:10.1002/cjce.23361

Cited by 11 publications

(5 citation statements)

References 26 publications

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“…Considering this, PBM has attracted more and more attention from scholars in recent years. [ 17,44–46 ] PBM could predict the size distribution of bubbles by describing the aggregation and breakup of bubbles in multiphase flow, as well as calculate the average diameter of bubbles. In order to simulate the effect of bubble distribution on solids holdup, PBM was adopted in combination with the Euler model.…”

Section: Resultsmentioning

confidence: 99%

Euler multiphase‐CFD simulation on a bubble‐driven gas–liquid–solid fluidized bed

2022

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An integrated flow model was developed to simulate the fluidization hydrodynamics in a new bubble‐driven gas–liquid–solid fluidized bed using the computational fluid dynamic (CFD) method. The results showed that axial solids holdup is affected by grid size, bubble diameter, and the interphase drag models used in the simulation. Good agreements with experimental data could be obtained by adopting the following parameters: 5 mm grid, 1.2 mm bubble diameter, the Tomiyama gas–liquid model, the Schiller–Naumann liquid–solid model, and the Gidaspow gas–solid model. At full fluidization state, an internal circulation of particles flowing upward near the wall and downward in the centre is observed, which is in the opposite direction compared with the traditional core‐annular flow structure in a gas–solid fluidized bed. The simulated results are very sensitive to bubble diameters. Using smaller bubble diameters would lead to excessive liquid bed expansions and more solid accumulated at the bottom due to a bigger gas–liquid drag force, while bigger bubble diameters would result in a higher solid bed height caused by a smaller gas–solid drag force. Considering the actual bubble distribution, population balance model (PBM) is employed to characterize the coalescence and break up of bubbles. The calculated bubble diameters grow up from 2–4 mm at the bottom to 5–10 mm at the upper section of the bed, which are comparable to those observed in experiments. The simulation results could provide valuable information for the design and optimization of this new type of fluidized system.

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Section: Resultsmentioning

confidence: 99%

Euler multiphase‐CFD simulation on a bubble‐driven gas–liquid–solid fluidized bed

2022

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“…39−41 Meanwhile, coalescence and breakage models of droplets were employed to describe the variation of DSD and extraction behavior in a single stage mixer. 42 In addition, the effect of mixing on coalescence and breakage of droplets in the mixer were also investigated numerically and experimentally. 43,44 Although CFD-PBE simulation was used to predict the spatial and temporal distribution of droplets in single-stage extractors, the effect of volume fraction and DSD on mass transfer parameter, namely volumetric mass transfer coefficient (k L α) has not been clearly identified.…”

Section: Introductionmentioning

confidence: 99%

“…In order to evaluate the influence of flow field on the mass transfer in a liquid–liquid extraction column, a CFD-PBE simulation was proposed by Gourdon et al Since then, CFD-PBE simulation has become a standard tool to predict the performances of industrial-scale extractors. The binary coalescent interface in the settler was applied to CFD-PBE simulations to predict the time evolution of the settling interface, volume fraction, and DSD of the dispersed phase. − Meanwhile, coalescence and breakage models of droplets were employed to describe the variation of DSD and extraction behavior in a single stage mixer . In addition, the effect of mixing on coalescence and breakage of droplets in the mixer were also investigated numerically and experimentally. , Although CFD-PBE simulation was used to predict the spatial and temporal distribution of droplets in single-stage extractors, the effect of volume fraction and DSD on mass transfer parameter, namely volumetric mass transfer coefficient ( k L α) has not been clearly identified.…”

Section: Introductionmentioning

confidence: 99%

CFD-PBE Simulation of Flow Dynamics and Mass Transfer in Two-Stage Countercurrent Mixer-Settler

Zheng

Yang

Xiao

et al. 2023

Ind. Eng. Chem. Res.

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Flow condition and mass transfer behavior of liquid−liquid extraction in a two-stage countercurrent extractor are investigated experimentally and numerically. CFD-PBE simulation is adopted to analyze the impact of operating parameters, including impeller speed, residence time, and organic-aqueous ratio of feed flow on volume fraction and droplet size of dispersed phase and volumetric mass transfer coefficient. Droplet size distribution is calculated by considering breakage and coalescence of dispersed phase. The allocation of dispersed phase between stages is found to be determined by impeller speed. Meanwhile, the allocation of dispersed phase between mixers and settlers is governed by residence time and organic-aqueous ratio of feed flow. Turbulence intensity, volume fraction, and droplet size distribution are revealed to be dominating parameters that affect the spatial nonuniform distribution of volumetric mass transfer coefficient. The mass transfer rate can be improved by increasing impeller speed in two stages. Higher residence time and organic-aqueous ratio of feed flow, however, have opposite effects on mass transfer rate in stage-1 and stage-2.

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“…Tang et al also published a study in a square-tank continuous pump-mixer with CFD combined with PBM relying on flow field PIV measurements [15]. They correlated their data but only investigated a flow rate of 3 L/min, which was controlled by a peristaltic pump [16].…”

Section: Introductionmentioning

confidence: 99%

Fluid Dynamics in a Continuous Pump-Mixer

et al. 2022

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The fluid dynamic (flow rates) and hydrodynamic behavior (local droplet size distributions and local holdup) of a continuous DN300 pump-mixer were investigated using water as the continuous phase and paraffin oil as the dispersed phase. The influence of the impeller speed (N = 375 to 425 rpm), the feed phase ratio (φF = 10 to 30 vol.-%), and the flow rate (V˙tot ≈ 0.5 to 2.3 L/min) were investigated by measuring the pumping height, local holdup of the disperse phase, and the droplet size distribution (DSD). The latter one was measured at three different vessel positions using an image-based telecentric shadowgraphic technique. The droplet diameters were extracted from the acquired images using a neural network. The Sauter mean diameters were calculated from the DSD and correlated with an extended model based on Doulah (1975), considering the impeller speed, the feed phase ratio, and additionally the flow rate. The new correlation can describe an extensive database containing 155 experiments of the fluid and hydrodynamic within a 15% error range.

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A study on liquid‐liquid dispersions in a continuous mixer via computational fluid dynamics (CFD) simulation combined with population balance model (PBM)

Cited by 11 publications

References 26 publications

Euler multiphase‐CFD simulation on a bubble‐driven gas–liquid–solid fluidized bed

Euler multiphase‐CFD simulation on a bubble‐driven gas–liquid–solid fluidized bed

CFD-PBE Simulation of Flow Dynamics and Mass Transfer in Two-Stage Countercurrent Mixer-Settler

Fluid Dynamics in a Continuous Pump-Mixer

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