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Identification and Mapping of Three Distinct Breakup Morphologies in the Turbulent Inertial Regime of Emulsification—Effect of Weber Number and Viscosity Ratio

Håkansson, Andreas LU ; Olad, Peyman LU and Innings, Fredrik LU (2022) In Processes 10(11).
Abstract

Turbulent emulsification is an important unit operation in chemical engineering. Due to its high energy cost, there is substantial interest in increasing the fundamental understanding of drop breakup in these devices, e.g., for optimization. In this study, numerical breakup experiments are used to study turbulent fragmentation of viscous drops, under conditions similar to emulsification devices such as high-pressure homogenizers and rotor-stator mixers. The drop diameter was kept larger than the Kolmogorov length scale (i.e., turbulent inertial breakup). When varying the Weber number (We) and the disperse-to-continuous phase viscosity ratio in a range applicable to emulsification, three distinct breakup morphologies are... (More)

Turbulent emulsification is an important unit operation in chemical engineering. Due to its high energy cost, there is substantial interest in increasing the fundamental understanding of drop breakup in these devices, e.g., for optimization. In this study, numerical breakup experiments are used to study turbulent fragmentation of viscous drops, under conditions similar to emulsification devices such as high-pressure homogenizers and rotor-stator mixers. The drop diameter was kept larger than the Kolmogorov length scale (i.e., turbulent inertial breakup). When varying the Weber number (We) and the disperse-to-continuous phase viscosity ratio in a range applicable to emulsification, three distinct breakup morphologies are identified: sheet breakup (large We and/or low viscosity ratio), thread breakup (intermediary We and viscosity ratio > 5), and bulb breakup (low We). The number and size of resulting fragments differ between these three morphologies. Moreover, results also confirm previous findings showing drops with different We differing in how they attenuate the surrounding turbulent flow. This can create ‘exclaves’ in the phase space, i.e., narrow We-intervals, where drops with lower We break and drops with higher We do not (due to the latter attenuating the surrounding turbulence stresses more).

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
direct numerical simulation, drop breakup, emulsification, high-pressure homogenizer, rotor-stator mixer, turbulence
in
Processes
volume
10
issue
11
article number
2204
pages
20 pages
publisher
MDPI AG
external identifiers
  • scopus:85149581982
ISSN
2227-9717
DOI
10.3390/pr10112204
language
English
LU publication?
yes
additional info
Funding Information: This research was funded by The Swedish Research Council (VR), grant number 2018–03820, and Tetra Pak Processing Systems AB. Publisher Copyright: © 2022 by the authors.
id
1784cd18-e9d6-42f3-b974-49ae00d2d494
date added to LUP
2023-03-20 08:35:07
date last changed
2023-12-20 09:51:11
@article{1784cd18-e9d6-42f3-b974-49ae00d2d494,
  abstract     = {{<p>Turbulent emulsification is an important unit operation in chemical engineering. Due to its high energy cost, there is substantial interest in increasing the fundamental understanding of drop breakup in these devices, e.g., for optimization. In this study, numerical breakup experiments are used to study turbulent fragmentation of viscous drops, under conditions similar to emulsification devices such as high-pressure homogenizers and rotor-stator mixers. The drop diameter was kept larger than the Kolmogorov length scale (i.e., turbulent inertial breakup). When varying the Weber number (<i>We</i>) and the disperse-to-continuous phase viscosity ratio in a range applicable to emulsification, three distinct breakup morphologies are identified: sheet breakup (large <i>We </i>and/or low viscosity ratio), thread breakup (intermediary <i>We </i>and viscosity ratio &gt; 5), and bulb breakup (low <i>We</i>). The number and size of resulting fragments differ between these three morphologies. Moreover, results also confirm previous findings showing drops with different <i>We </i>differing in how they attenuate the surrounding turbulent flow. This can create ‘exclaves’ in the phase space, i.e., narrow <i>We</i>-intervals, where drops with lower <i>We </i>break and drops with higher <i>We </i>do not (due to the latter attenuating the surrounding turbulence stresses more).</p>}},
  author       = {{Håkansson, Andreas and Olad, Peyman and Innings, Fredrik}},
  issn         = {{2227-9717}},
  keywords     = {{direct numerical simulation; drop breakup; emulsification; high-pressure homogenizer; rotor-stator mixer; turbulence}},
  language     = {{eng}},
  number       = {{11}},
  publisher    = {{MDPI AG}},
  series       = {{Processes}},
  title        = {{Identification and Mapping of Three Distinct Breakup Morphologies in the Turbulent Inertial Regime of Emulsification—Effect of Weber Number and Viscosity Ratio}},
  url          = {{http://dx.doi.org/10.3390/pr10112204}},
  doi          = {{10.3390/pr10112204}},
  volume       = {{10}},
  year         = {{2022}},
}