Drag force of bubble swarms and numerical simulations of a bubble column with a CFD-PBM coupled model

Yang, Gaoyuan; Zhang, Huahai; Luo, Jiajia; Wang, Tiefeng

doi:10.1016/j.ces.2018.07.012

Cited by 59 publications

(36 citation statements)

References 55 publications

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“…Drag force was calculated using the model of Tomiyama et al, 49 which is widely used in the air–water system: 31 , 35 , 50 where C D0 is the drag coefficient of a single bubble, and C D i is the drag coefficient of the bubble with diameter d b i , and f i is the volume fraction of the bubble with diameter d b i in the gas phase: where Re i = d b i | u l – u g | ρ l / μ l ; the Eotvos number Eo i of a bubble with diameter d b i is given by where σ is the surface tension.…”

Section: Computational Fluid Dynamics Modelmentioning

confidence: 99%

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Computational Fluid Dynamics Simulation of Hydrodynamics in a Two-Stage Internal Loop Airlift Reactor with Contraction-Expansion Guide Vane

et al. 2021

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Global circulation and liquid back mixing adversely affect the continuous production of a multistage internal airlift loop reactor. A contraction-expansion guide vane (CEGV) is proposed and combined with a two-stage internal loop airlift reactor (TSILALR) to suppress the liquid back mixing between stages. A computational fluid dynamics (CFD) simulation is conducted to evaluate the performance of the CEGV in the TSILALR. The bubble size distribution and turbulent flow properties in the TSILALR are considered in the CFD simulation by using the population balance model and RNG k - ε turbulence model. The CFD model is validated against the experimental results. The deviations in the gas holdup and mean bubble diameter between the simulation and experimental results are less than 8% and 6%, respectively. The streamlines, flow pattern, bubble size distribution, and axial liquid velocity in the TSILALRs with and without the CEGV at superficial velocities of 0.04 and 0.08 m/s are obtained by CFD simulation. It has been shown that the CEGV generated local circulation flows at each stage instead of a global circulation flow in the TSILALR. The average global gas holdup in the TSILALR with a CEGV increased up to 1.98 times. The global gas holdup increased from 0.045 to 0.101 and the average axial velocity in the riser decreased from 0.314 to 0.241 m/s when the width of the CEGV increased from 50 to 75 mm at the superficial gas velocity of 0.08 m/s.

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Section: Computational Fluid Dynamics Modelmentioning

confidence: 99%

“…The virtual mass force is expressed by 50 where the virtual mass force coefficient, C VM , was set to 0.25.…”

Section: Computational Fluid Dynamics Modelmentioning

confidence: 99%

Computational Fluid Dynamics Simulation of Hydrodynamics in a Two-Stage Internal Loop Airlift Reactor with Contraction-Expansion Guide Vane

et al. 2021

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“…In the past few years, several attempts have been made to deepen the understanding of break-up and coalescence phenomena by combining computational fluid dynamics (CFD) and population balance models (PBM). [126][127][128][129][130][131][132][133] In these works, the spatial dependencies of the break-up and coalescence rates are incorporated by simulating the geometry in question with a proper mesh and solving the equations with a finite elements method or similar. This methodology results in a greater physical accuracy but demands higher computational costs.…”

Section: Drop Breakage and Coalescence Processes In Liquid-liquid Dmentioning

confidence: 99%

“…Wake effects are also considered as partly responsible for break-up in this model since a difference in shape in contact with the continuous phase (head-tail instability) causes necking of the particle and surface shear stress may subsequently lead to splitting. Few authors incorporate this effect into their models; a recent example is the one by Yang et al [130] Shearing-off process Also coined erosive breakage, this mechanism is most commonly found in larger particles, whose surface instability is higher than smaller ones. A velocity gradient around the particle surface causes a number of smaller daughter particles to be sheared-off from its mother.…”

Section: Turbulent Pressure Fluctuation or Particle-eddy Collisionmentioning

confidence: 99%

Mechanisms and conditions that affect phase inversion processes: A review

2020

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The phenomenon of phase inversion occurs in liquid-liquid dispersions found in a variety of chemical engineering fields. From simple oil-water mixtures to complex polymeric systems, the operating variables that affect this physical phenomenon are discussed in this work. The contribution on this matter by a large number of researchers is critically assessed, outlining both coherent and conflicting results. A detailed review of the mechanisms by which phase inversion takes place is also provided. While this subject has been studied for the past fifty years, this multivariate nonlinear process is This article is protected by copyright. All rights reserved. not yet comprehensively understood, and this review article aims to describe the conclusions so far reached to provide insight for future research.

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“…The breakup of fluid particles, i.e., bubbles or drops, in a turbulent flow plays a crucial role in many situations and understanding of the mechanism is essential to improve the modeling of complex multiphase flows by numerical methods. Population balance modeling (PBM) is a numerical approach successfully used to model the dispersed flows in stirred-tank reactors or bubble columns [1][2][3]. The usage of PBM requires the knowledge of breakup frequency, b 1) , and of the size distribution of particles generated during the breakup denoted as daughter size distribution.…”

Section: Introductionmentioning

confidence: 99%

Experiments on Bubble Breakup Induced by Collision with a Vortex Ring

et al. 2019

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The bubble breakup after collision with a vortex ring was validated as source of breakup parameters for population balance modeling. This system was chosen as a deterministic alternative to the stochastic nature of bubble breakup studies under turbulent flow. The vortex ring was characterized by combining experimental visualization and numerical simulations. Breakup frequency, mean number of daughter bubbles, and its size distribution were obtained by high‐speed camera recording of the collision process. The dependence of breakup parameters on the size of the mother bubble and Weber number was determined.

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Drag force of bubble swarms and numerical simulations of a bubble column with a CFD-PBM coupled model

Cited by 59 publications

References 55 publications

Computational Fluid Dynamics Simulation of Hydrodynamics in a Two-Stage Internal Loop Airlift Reactor with Contraction-Expansion Guide Vane

Computational Fluid Dynamics Simulation of Hydrodynamics in a Two-Stage Internal Loop Airlift Reactor with Contraction-Expansion Guide Vane

Mechanisms and conditions that affect phase inversion processes: A review

Experiments on Bubble Breakup Induced by Collision with a Vortex Ring

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