Numerical simulation of macro-mixing in liquid-liquid stirred tanks

Numerical simulations of turbulent immiscible liquid-liquid mixing processes in cylindrical stirred tanks driven by a Rushton turbine are carried out based on an Eulerian-Eulerian approach using in-house codes. An isotropic standard k-epsilon turbulence model and an anisotropic two-phase explicit algebraic stress model (EASM) are used for flow field simulations. Quantitative comparisons of the homogenization curve and mixing time predicted by the EASM are conducted with reported experimental data and other predictions by the standard k-epsilon model and large eddy simulation (LES). The comparisons show that the EASM predictions are in satisfactory agreement with experimental data and better than the k-epsilon model ones. The variation of the continuous phase mixing time with impeller speed can be an effective method to determine the critical impeller speed for complete dispersion of oil phase. The key features of the complex liquid-liquid mixing processes in stirred tanks have been successfully predicted by the EASM, which can be an alternative tool for practical engineering applications with economical computational cost and good accuracy. (C) 2013 Elsevier Ltd. All rights reserved.

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