PDA Measurement of Drop Size Distribution for Liquid-Liquid Dispersing in Agitated Tanks

Abstract

The dispersion characteristics of different axial‐ and radial‐flow impellers at the same average specific power and energy input are investigated in this paper. The impact of turbulent shear stresses is decisive for the breakup of deformable particles like droplets, since dispersion usually is carried out under turbulent flow conditions.

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

“…25 However, the studies in particulate systems reveal that the particle stress caused by these impellers is higher. 13,14,26,28,36 This statement is in general agreement with the results of the present study with the exceptions of PBT-6×45°and PROPRing-h/d=0.33. The interpretation of the increased hydromechanical stress caused by axial impellers was proven to be challenging.…”

Numerical and experimental analysis of particle strain and breakage in turbulent dispersions

“…Primarily the differences between axial and radial stirrers are obvious and well described in literature (Gandhi and Kumar, 1990;Henzler and Biedermann, 1996;Langer and Deppe, 2000;Wille et al, 2001;Gabriele et al, 2009). The reason for these differences has not been analysed yet.…”

“…Concluding from 2D particle image velocimetrymeasurements, Wille et al (2001) assume that the ratio of strain to shear forces is higher for axial agitators compared with radial agitators. With this work we want to establish a base to analyse the different shear and strain forces created by different stirrer types in an in-house developed breakage cell.…”

Multiphase Stirred Tank Bioreactors – New Geometrical Concepts and Scale‐up Approaches

“…and Wille et al. , , reported that the arithmetic mean droplet diameter or/and the median number‐based diameter ( d 50 ) failed to describe the breakage process in their stirred tank experiments. Single quantities as the Sauter mean diameter can represent numerous different distribution types .…”

“…Otherwise, important information might be lost leading to misinterpretation of results. For instance, Bliatsiou et al, Zhou et al and Wille et al [10,50,51] reported that the arithmetic mean droplet diameter or/and the median number-based diameter (d 50 ) failed to describe the breakage process in their stirred tank experiments. Single quantities as the Sauter mean diameter can represent numerous different distribution types [50].…”