Evaluation Method of Homogenization Effect for Different Stator Configurations of Internally Circulated Batch Rotor-Stator Mixers

Rotor‐stator mixers (RSMs) can be operated in either batch or inline mode. When operating a rotor‐stator geometry in batch mode, it typically experiences an order of magnitude higher volumetric flow through the stator than in inline mode. This is expected to cause differences in the flow and turbulence in the rotor‐stator region. This study uses computational fluid dynamics (CFD) to study the hydrodynamic differences in and near the stator hole as a function of volumetric flow rates between those experienced in inline and batch modes of operation. It is concluded that both radial flow profiles and turbulent kinetic energy across a range of rotor speeds and flow rates can be described by a velocity ratio: average tangential fluid velocity in the stator hole divided by the rotor tip speed. Moreover, the position where dissipation of turbulent kinetic energy takes place—and hence the effective region of dispersion or mixing—differs between the two modes of operation. The relative importance of the two regions can be described in terms of the velocity ratio and the transition can be predicted based on the relative power input due to rotational and pumping power of the mixer. This study provides a starting point for understanding differences between emulsification efficiency between inline and batch modes of operation with relevance for both equipment design and process scale‐up.

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“…The fill‐ratio is also proportional to what is sometimes referred to as the inline RSM flow number:

N_{F} = \frac{Q}{N D^{3}} = F \cdot \frac{π A_{t o t}}{D^{2}}

…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic difference between inline and batch operation of a rotor‐stator mixer head ‐ A CFD approach

Håkansson

Arlov

Carlsson³

et al. 2016

Can J Chem Eng

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“…Utomo et al (2008) investigated flow characteristics of a rotor-stator mixer computationally and reported that about 70% of energy is dissipated near the mixing head and jet velocity scales with the rotor speed N, while the energy dissipation scales with N 3 . Kamiya et al (2010) proposed the homogenization coefficient, based on the power number, the flow number and shear frequency between rotor blades and stator holes to assess the homogenization effect for different rotor-stator combinations.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics of CNT dispersion in high shear dispersion mixers

Park

Lee

Hwang

et al. 2014

Korea-Aust. Rheol. J.

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In this work, we investigate the carbon nanotube (CNT) fragmentation mechanism and dispersion in high shear homogenizers as a plausible dispersion technique, correlating with device geometries and processing conditions, for mass production of CNT-aluminum composites for automobile industries. A CNT dispersion model has been established in a turbulent flow regime and an experimental method in characterizing the critical yield stress of CNT flocs are presented. Considering CNT dispersion in ethanol as a model system, we tested two different geometries of high shear mixers -blade-stirrer type and rotor-stator type homogenizers -and reported the particle size distributions in time and the comparison has been made with the modeling approach and partly with the computational results.

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The dissipation rate of turbulent kinetic energy and its relation to pumping power in inline rotor-stator mixers

Håkansson

Innings

2017

Chemical Engineering and Processing: Process Intensification

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Evaluation Method of Homogenization Effect for Different Stator Configurations of Internally Circulated Batch Rotor-Stator Mixers

Cited by 4 publications

References 6 publications

Hydrodynamic difference between inline and batch operation of a rotor‐stator mixer head ‐ A CFD approach

Hydrodynamic difference between inline and batch operation of a rotor‐stator mixer head ‐ A CFD approach

Hydrodynamics of CNT dispersion in high shear dispersion mixers

The dissipation rate of turbulent kinetic energy and its relation to pumping power in inline rotor-stator mixers

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