Numerical and Experimental Investigation of Liquid−Liquid Two-Phase Flow in Stirred Tanks

Abstract

The experimental data on the holdup of the dispersed phase in a Rushton impeller agitated stirred tank are presented. Experimental measurement is performed utilizing the sample withdrawal method to obtain the local dispersed-phase holdup in a laboratory-scale stirred tank under a variety of operating conditions. Three-dimensional turbulent two-phase liquid−liquid flow in the stirred tank is also numerically simulated by solving the Reynolds-averaged Navier−Stokes equations of two phases formulated by the two-fluid model. The turbulence effect is formulated using a simple two-phase extension of the well-known k−ε turbulence model by adding an extra source term generated from the presence of the dispersed phase in the turbulent kinetic energy transport equation of the continuous phase. A modified “inner−outer” iterative procedure is employed to model the interaction of the rotating impeller with the wall baffles. The model-predicted mean velocity, turbulence characteristics of the continuous phase, and holdup profiles of the dispersed phase are compared against the published experimental data and the present measurements to validate the computational procedure, and good agreement is found up to a rather high overall dispersed-phase holdup case (30 vol %).