Characterization of liquid‐liquid dispersions with variable viscosity by coupled computational fluid dynamics and population balances

Abstract

in Wiley Online Library (wileyonlinelibrary.com) Sustaining stable liquid-liquid dispersion with the desired drop size still relies on experimental correlations, which do not reflect our understanding of the underlying physics and have a limited prediction capability. The complex behavior of liquid-liquid dispersions inside a stirred tank, which is equipped with a Rushton turbine, was characterized by a combination of computational fluid dynamics and population balance equations (PBE). PBE took into account both the drop coalescence and breakup. With the increasing drop viscosity, the resistance to drop breakage also increases, which was introduced by the local criteria for drop breakup in the form of the local critical Webber number (We c ). The dependency of We c on the drop viscosity was derived from the experimental data available in the literature. Predictions of Sauter mean diameter agree well with the experimentally measured values allowing prediction of mean drop size as a function of variable viscosity, interfacial tension, and stirring speed.

Droplet breakage and coalescence in liquid–liquid dispersions: Comparison of different kernels with EQMOM and QMOM

“…The model was later modified to include the possible effect of additional disruptive stresses due to interfacial tension changes. 17 There exists also a large group of models based on an analogy to the kinetic theory of gases, accounting for different effects 3,[18][19][20][21][22][23] and accounting for the influence of the turbulent energy spectrum distribution on the vortex number density. [24][25][26][27] Purely kinematic break-up model was proposed by Martinez-Bazan et al 28 Another problem relates to the number of daughter drops.…”

Viscosity and drop size evolution during suspension polymerization

“…The flow was characterized by the Computational Fluid Dynamics (CFD), which utilized multiphase Euler‐Euler model with Reynolds‐Averaged Navier Stokes (RANS) equations solved for each phase. A detailed description of the combined CFD‐PBE model as well as the choice of the kernels, which reflect the variable interfacial tension, dispersed viscosity and mixing speed, is discussed in our recent publication …”

“…The viscosity model is validated by a set of rheometric measurements. The CFD‐PBE model presented recently by our group was here utilized to describe the drop size along the polymerization reaction.…”

Extension of Einstein's Law for Power‐Law Fluid to Describe a Suspension of Spherical Particles: Application to Recycled Polymer Flow

“…So, by mixing two polymers, complex interfaces are formed due to deformation, breakup and coalescence of droplets caused by shear and interfacial tension. For that reason, the morphological development of the polymer blends is difficult to predict [6][7][8] and their rheological properties can be written in function of the matrix fluid viscosity η m , the dispersed polymer viscosity η d , the volume fraction ϕ and the surface tension γ [9,10]. Of these factors, the ratio of the viscosities as well as the volume fraction will be of a great interest in the present work concerned by recycled polymers.…”