Effect of oscillatory flow on nucleation kinetics of butyl paraben

Huaiyu Yang, Xi Yu, Vishal Raval, Yassir Makkawi, Alastair Florence

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Abstract

More than 165 induction times of butyl paraben-ethanol solution in a batch moving fluid oscillation baffled crystallizer with various amplitudes (1-9 mm) and frequencies (1.0-9.0 Hz) have been determined to study the effect of COBR operating conditions on nucleation. The induction time decreases with increasing amplitude and frequency at power density below about 500 W/m3; however, a further increase of the frequency and amplitude leads to an increase of the induction time. The interfacial energies and pre-exponential factors in both homogeneous and heterogeneous nucleation are determined by classical nucleation theory at oscillatory frequency 2.0 Hz and amplitudes of 3 or 5 mm both with and without net flow. To capture the shear rate conditions in oscillatory flow crystallizers, a large eddy simulation approach in a computational fluid dynamics framework is applied. Under ideal conditions the shear rate distribution shows spatial and temporal periodicity and radial symmetry. The spatial distributions of the shear rate indicate an increase of average and maximum values of the shear rate with increasing amplitude and frequency. In continuous operation, net flow enhances the shear rate at most time points, promoting nucleation. The mechanism of the shear rate influence on nucleation is discussed.

Original languageEnglish
Pages (from-to)875-886
Number of pages12
JournalCrystal Growth and Design
Volume16
Issue number2
Early online date28 Dec 2015
DOIs
Publication statusPublished - 3 Feb 2016

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Keywords

  • computation theory
  • computational fluid dynamics
  • crystallizers
  • large eddy simulation
  • nucleation
  • parabens
  • shear deformation
  • classical nucleation theory
  • continuous operation
  • heterogebeous nucleation
  • nucleation kinetics
  • operating condition
  • oscillatory frequency
  • preexponential factor
  • temporal periodicity
  • shear flow

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