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

Håkansson, Andreas LU ; Arlov, Dragana LU ; Carlsson, Fredrik and Innings, Fredrik LU (2017) In Canadian Journal of Chemical Engineering 95(4). p.806-816
Abstract

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... (More)

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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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
emulsification, fluid flow, mixing, rotor-stator mixer, turbulence
in
Canadian Journal of Chemical Engineering
volume
95
issue
4
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85014390636
  • wos:000398079200022
ISSN
0008-4034
DOI
10.1002/cjce.22718
language
English
LU publication?
yes
id
52f58abe-d3b0-4f4a-889a-20f8ad0dfee0
date added to LUP
2017-03-14 11:51:02
date last changed
2018-01-07 11:55:09
@article{52f58abe-d3b0-4f4a-889a-20f8ad0dfee0,
  abstract     = {<p>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.</p>},
  author       = {Håkansson, Andreas and Arlov, Dragana and Carlsson, Fredrik and Innings, Fredrik},
  issn         = {0008-4034},
  keyword      = {emulsification,fluid flow,mixing,rotor-stator mixer,turbulence},
  language     = {eng},
  month        = {04},
  number       = {4},
  pages        = {806--816},
  publisher    = {Wiley-Blackwell},
  series       = {Canadian Journal of Chemical Engineering},
  title        = {Hydrodynamic difference between inline and batch operation of a rotor-stator mixer head - A CFD approach},
  url          = {http://dx.doi.org/10.1002/cjce.22718},
  volume       = {95},
  year         = {2017},
}