Hydrodynamics in unbaffled liquid-solid stirred tanks with free surface studied by DEM-VOF method

Kang, Qing; He, Dandan; Zhao, Na; Wang, Jingtao

doi:10.1016/j.cej.2019.122846

Cited by 38 publications

(30 citation statements)

References 41 publications

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“…The mathematical model mainly consists of two parts: the governing equations of fluids and the equation of motion for particles. 23,27 For ease of reading, the most important formulas are summarized in this section. Others could be found out in the supporting information.…”

Section: Mathematical Modelsmentioning

confidence: 99%

Study of free‐surface and solids suspension in top‐sealed tanks stirred by pitched blade turbine impellers through DEM‐VOF method

Bao

Kang

Wang

et al. 2022

Asia-Pacific J Chem Eng

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A coupled method of discrete element method (DEM) and volume of fluid (VOF) is applied to study the particle suspension in top‐sealed solid–liquid tanks with a free‐surface. VOF is used to track the gas–liquid free‐surface, and DEM is used to calculate the movement and interaction of particles. As the air between the cover and free‐surface in a sealed tank is very limited, the free‐surface evolution process that a big vortex is generated quickly and then shrinks to a smaller one in sealed stirred tanks is reported first in this paper. In addition, the effects of pitched blade turbine (PBT) with different blade pitched angles (including 30°, 45°, 60°, 75°, and 90°) on solid suspension, free‐surface, and power number are investigated. Finally, the relationships between particle motion and fluid flow during the stirring are studied carefully. Fluid flow plays a dominant role during the start‐up of the stirring; and then, due to the contact of particles, some particles could obtain the larger velocity than the fluid. The results obtained here are helpful to design the sealed stirred tanks with PBT.

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Section: Mathematical Modelsmentioning

confidence: 99%

Study of free‐surface and solids suspension in top‐sealed tanks stirred by pitched blade turbine impellers through DEM‐VOF method

Bao

Kang

Wang

et al. 2022

Asia-Pacific J Chem Eng

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“…As a Lagrangian method, the discrete phase model (DPM) treats the particles as the mass points and does not consider the volume effects of particles. It is also limited due to its solid volume fraction is generally less than about 10% [22]. The discrete element model (DEM) is popular for calculating the interactions of solid particles with almost real properties and provides several contact models to describe particle collisions.…”

Section: Introductionmentioning

confidence: 99%

“…Although many researchers have used CFD-DEM to calculate heat transfers, there are few studies on the mixing process of liquid-solid two-phase flows involving heat transfers. In our previous work, a coupled VOF-DEM model was developed to capture the free surface in gas-liquid-solid systems [22,30,31]. Although they consider the collision among particles and the effects of the particle volume on the continuous phase, no heat transfer has been involved.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer and Hydrodynamics in Stirred Tanks with Liquid-Solid Flow Studied by CFD–DEM Method

Luo

Wang

et al. 2021

Processes

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The heat transfer and hydrodynamics of particle flows in stirred tanks are investigated numerically in this paper by using a coupled CFD–DEM method combined with a standard k-e turbulence model. Particle–fluid and particle–particle interactions, and heat transfer processes are considered in this model. The numerical method is validated by comparing the calculated results of our model to experimental results of the thermal convection of gas-particle flows in a fluidized bed published in the literature. This coupling model of computational fluid dynamics and discrete element (CFD–DEM) method, which could calculate the particle behaviors and individual particle temperature clearly, has been applied for the first time to the study of liquid-solid flows in stirred tanks with convective heat transfers. This paper reports the effect of particles on the temperature field in stirred tanks. The effects on the multiphase flow convective heat transfer of stirred tanks without and with baffles as well as various heights from the bottom are investigated. Temperature range of the multiphase flow is from 340K to 350K. The height of the blade is varied from about one-sixth to one-third of the overall height of the stirred tank. The numerical results show that decreasing the blade height and equipping baffles could enhance the heat transfer of the stirred tank. The calculated temperature field that takes into account the effects of particles are more instructive for the actual processes involving solid phases. This paper provides an effective method and is helpful for readers who have interests in the multiphase flows involving heat transfers in complex systems.

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“…The rotating impeller in the tank not only determines the liquid‐solid mixing but also exerts shear stress on the membrane surface. Until now, liquid‐solid flow in stirred tank reactors without filtration has been extensively investigated by computational fluid dynamics (CFD) simulation 17–23. However, there is still an evident lack of research on the topic of membrane‐assisted stirred slurry reactors.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Simulation of Hydrodynamics and Filtration in a Membrane‐Assisted Stirred Slurry Reactor

Qiu

Liu

et al. 2021

Chem Eng & Technol

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A membrane‐assisted stirred slurry reactor is developed by equipping a membrane tube into a stirred tank. Liquid‐solid flow is simulated by the Euler‐Lagrange method with filtration and particle deposition models. Acceptable predictions on the cake mass and particle deposition patterns are achieved by comparing with experimental data. The introduction of the membrane tube generates an asymmetric flow field. Shear stress on the membrane surface has a direct influence on the particle deposition. Increasing the impeller rotating speed leads to larger shear stress and mitigates the particle deposition. The cake mass is reduced by placing the membrane tube close to the impeller. The upward liquid flow pumped by the pitched‐blade impeller results in low shear stress and the vertical‐blade impeller is preferable.

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Hydrodynamics in unbaffled liquid-solid stirred tanks with free surface studied by DEM-VOF method

Cited by 38 publications

References 41 publications

Study of free‐surface and solids suspension in top‐sealed tanks stirred by pitched blade turbine impellers through DEM‐VOF method

Study of free‐surface and solids suspension in top‐sealed tanks stirred by pitched blade turbine impellers through DEM‐VOF method

Heat Transfer and Hydrodynamics in Stirred Tanks with Liquid-Solid Flow Studied by CFD–DEM Method

Modeling and Simulation of Hydrodynamics and Filtration in a Membrane‐Assisted Stirred Slurry Reactor

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