Dispersion of oil droplets in rotor-stator mixers: Experimental investigations and modeling

Forming emulsions by mixing of immiscible liquids, water and silicone oils was carried out by applying the in-line high-shear rotor-stator mixers. In experimental part investigations were carried out using experimental rig consisting of two tanks and an in-line Silverson rotor-stator (150/250) MS; the system was operated in a multiple pass (MP) mode, which can be compared with a single pass (SP) mode experiments. Emulsification of 1 wt.% silicone oils (Dow Corning 200 fluid) with viscosities of 9.4, 48 and 339 mPas was investigated. Emulsions were stabilized by adding 0.5 wt.% of sodium laureth sulphate. Effects of rotor speed, number of passes and the drop viscosity on the drop size were investigated. Numerical simulations were carried out using the k-epsilon model of turbulence and the multiple reference frame method (MRF) linked to the population balance equation. The population balance was expressed and solved using the quadrature method of moments (QMOM). The breakage kernel for drops whose diameter falls within the inertial subrange of turbulence was defined based on the multifractal model of intermittent turbulence. (C) 2014 Elsevier B.V. All rights reserved.