Computational fluid dynamics analysis to effects of geometrical design and physical property on complete suspension of floating solids in stirred tanks

Qiao, Shengchao; Wang, Rijie; Ying, Yiming; Yang, Xiaoxia

doi:10.1002/apj.1835

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…This is because at the same rotation speed, the larger the inner impeller diameter, the greater is the linear velocity at the blade tip. Hence, according to the Kolmogorov’s turbulence theory about turbulent length scales and turbulent energy transfer process, , stronger surface turbulence and larger central vortex would be produced, which draw the floating particles into the liquid phase easier, and the corresponding N ijd becomes smaller. In addition, a relatively large decline of N ijd is caused by a relatively small increase in the diameter of inner impeller, so the P Vjd would still decrease significantly even if the diameter of the inner impeller increases.…”

Section: Results and Discussionmentioning

confidence: 99%

Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers

Liu

Gao

et al. 2019

Ind. Eng. Chem. Res.

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In view of the current situation of single form and low efficiency, a coaxial mixer with wide adaptability was combined with the drawdown of floating particles in viscous systems, and the effects of operation mode, impeller type, impeller diameter, impeller submergence, system viscosity, solid concentration and particle size were investigated experimentally. It is found that the coaxial mixer under corotation mode can achieve the critical drawdown of floating particles with lower speed and power than the corresponding single-shaft mixer, and the advantage becomes more obvious with increasing system viscosity and solid volume fraction. Under the same conditions, compared with the axial and radial flow impellers, the mixed flow impeller with down-pumping mode can effectively draw the floating particles down with the lowest critical speed and power. Moreover, a larger impeller diameter and smaller impeller submergence are recommended for the drawdown of floating particles, but the impeller diameter should not exceed half of the vessel diameter.

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Section: Results and Discussionmentioning

confidence: 99%

Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers

Liu

Gao

et al. 2019

Ind. Eng. Chem. Res.

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“…The conservation equations pertaining to the liquid (continuous) phase are given as follows (without considering mass transfer) [15] :…”

Section: Cfd Simulationmentioning

confidence: 99%

“…Takahashi et al [14] conducted CFD simulation to study impacts of mixing paddles with different slopes on SRs and mixing time, without the investigation the blade's geometry. Qiao et al [15] studied effects of geometrical design and physical property on mixing quality of floating solids in the up-pumping PBT stirred tanks by using CFD technique qualitatively, didn't conduct the blade's optimal design. Alfaro-Ayala et al [16] just evaluated the optimal location of impellers on the central shaft in the down-pumping PBT stirred tanks by using combination techniques of CFD and Evolutionary Programming (EP).…”

Section: Introductionmentioning

confidence: 99%

Computational and experimental investigation of laminar flow mixing system in a pitched-blade turbine stirred tank

Cui

Zhang

et al. 2018

International Journal of Agricultural and Biological Engineering

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The flow distribution and mixing performance of the laminar flow in the PBT impeller-stirred tank were investigated in this study. The variation along with mixing time of the flow distribution and concentration at the selected positions was visualized by means of the CFD and experiment methods. The CFD simulations results had a good agreement with the experimental results. In order to minish the Segregated Regions, the PBT impeller was optimally designed by means of orthogonal factorial experiment with selecting the θ 99 mixing time as evaluation criteria. With the aim to increase the mixing efficiency, the optimal design results were obtained with the geometrical parameters of impeller diameter of 0.084 m, discharge angle of 45º, blade width of 0.018 m, and clearance of 0.05 m, and the mixing time of the optimal impeller-stirred flow was about 180 s, so this optimal design PBT impeller is more proper for the agricultural industries.

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“…Both experimental and theoretical studies were carried out with constant reactor geometries and agitator types [9,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Furthermore, cylindrical type reactors are selected for most of these particle size distribution investigations.…”

Section: Literaturementioning

confidence: 99%

Polistirenin Süspansiyon Polimerizasyonuyla Üretiminde Tanecik Boyutu Dağılımının Reaktör Geometrisi ve Karıştırma Koşulları ile İlişkisi

Erünal

2018

Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi

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The relation between the reactor geometry and agitation conditions on particle size distribution for suspension polymerization of polystyrene was analyzed. The reactor geometries were selected as cylindrical and spherical, respectively. Mechanical agitation was provided via double-impeller Marine type propeller at 1600 rpm and 2000 rpm. The diameters of the reactors were selected approximately the same for cylindrical and spherical reactors in order to keep effective mixing area similar in both geometries. All experiments were conducted around 8 hours to complete the polymerization reaction. Particle size distribution analyses showed that at faster agitation conditions in cylindrical reactor narrower and smaller particles are obtained as expected. On the other hand, in spherical reactor, vortex formation and non-uniform particle size distribution were observed at faster agitation. Interestingly, when agitation speed was decreased in spherical reactor, quite narrower and smaller particle size distributions with respect to cylindrical reactor were obtained. However, the number and average molecular weight analyses suggested that the particles obtained from spherical reactor has a lower molecular weight distribution than particles from cylindrical reactor. This was attributed to the decrease in effective mixing area due to the non-homogenous changes of the distance between reactor walls and impellers throughout the spherical reactor. The geometry change to spherical geometry obviously causes diminishing in mass transfer of initiators and suspension stabilizers so that a shortening of polymer chains lead to a slight increase in polydispersity index.

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Computational fluid dynamics analysis to effects of geometrical design and physical property on complete suspension of floating solids in stirred tanks

Cited by 8 publications

References 27 publications

Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers

Experimental Investigation on Drawdown of Floating Particles in Viscous Systems Driven by Coaxial Mixers

Computational and experimental investigation of laminar flow mixing system in a pitched-blade turbine stirred tank

Polistirenin Süspansiyon Polimerizasyonuyla Üretiminde Tanecik Boyutu Dağılımının Reaktör Geometrisi ve Karıştırma Koşulları ile İlişkisi

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