Effect of Shear Rate Distribution on Particle Aggregation in a Stirred Vessel

Abstract

The modeling of particle aggregation under a simple shear flow and the extension of the model to a stirred vessel is described. The model quantitatively demonstrates the change of the number of aggregates with time for each shear rate. This number increased with higher shear rate and, conversely, the aggregate size became small when raising the shear rate. This was because aggregates were broken by the stronger shear force. The number of aggregates for different impellers was determined. The shear rate was back‐calculated from the experimentally obtained aggregate size and the model equation. This shear rate was different from that estimated from the Metzner‐Otto method, consequently, some revisions of the Metzner‐Otto equation might be necessary for its application to particle aggregation.

Effect of Particle Image Velocimetry Setting Parameters on Local Velocity Measurements in an Agitated Vessel

“…Fluctuation velocity gradients are used for determining the turbulent kinetic energy dissipation rate ε , which is a crucial factor for scaling up many processes, such as gas‐liquid dispersion, liquid‐liquid dispersion, flocculation, etc. . Therefore, precise determination of the velocity gradients is necessary for the correct determination of ε .…”

Intensification of Mixing Processes with Complex Fluids

“…Some researchers have reported that K s depends on not only an impeller type, but also rheological properties of a fluid (e.g., Rieger and Novak, 1973;Šesták et al, 1986;Carreau et al, 1992;Tanguy et al, 1996;Anne-Archard et al, 2006). Also, Masuda et al (2017a) indicated that some revisions for the Metzner-Otto method are necessary when their concept is applied to a particle aggregation process using a stirred vessel for the estimation of γ eff . In the future, revising the Metzner-Otto concept will be necessary including the application to viscoelastic fluid processes.…”