Computational Fluid Dynamics Simulation and Experimental Investigation: Study of Two-Phase Liquid−Liquid Flow in a Vertical Taylor−Couette Contactor

Abstract

Two-fluid Taylor-vortex flow in coaxial cylinders with a stationary outer cylinder and a rotating inner cylinder has potential advantages over the conventional extraction equipment in chemical and bioprocess industries. The two phase flow behavior in the vertical annular region is either in the form of homogeneous dispersion, banded dispersion, segregated or the stratified flow with both the phases retaining individual integrity. Computational fluid dynamics (CFD) simulations have been carried out for the annular region. The effect of physical properties like density difference, interfacial tension, and the effect of geometrical parameters such as annular gap have been studied. The various regime transmissions have been investigated using CFD as well as flow visualization by particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF). The flow pattern has also been measured and compared with the CFD predictions. An attempt has been made to present the results on transition in the form of a regime map with the Eotvos and Taylor numbers as the two coordinates.

CFD Simulation of Annular Centrifugal Extractors

“…The simulated energy dissipation rate needs to be equal to the energy supply rate by the impeller rotation. Such a complete energy balance has been established by Vedantam and Joshi [3], Deshmukh et al [26,132], Sathe et al [28], and Tamhane et al [105]. The establishment of such energy balance has been considered to be an important criterion for the validity of CFD simulation.…”

“…Further, the flow was found to be tangential in the region below the rotating cylinder. Sathe et al [28], in their study of two-phase liquid-liquid flow, carried out CFD simulations for single phase and compared the data with the PIV measurements for a vertical configuration. They compared their simulation data with the vortex spacing and found the comparison to be inline with measured data.…”

“…Building on the previous work, they proposed a mechanism for the formation of banded liquid-liquid flowalternating aqueous-rich and organic-rich vortices-which occurs for the upper end of the range of relatively low Re studied (Re = 300 ∼ 5000). A very useful recent study by Sathe and coworkers [28] explores a broader range of flow regimes both experimentally and computationally for a vertically oriented Taylor-Couette mixer using a sodium iodide solution as the dispersed phase and kerosene as the continuous one. While no air-or air-liquid-free surface is present, a range of flow regimes spanning segregated to homogeneously dispersed liquid-liquid flows was explored.…”

“…To design this equipment, it is important to understand a priori the conditions under which the transition takes place from one type of flow regime to another. Industrial scale equipment typically has a vertical orientation [26][27][28]. Some published work is also available for horizontal orientation [4,29,30].…”

Liquid–Liquid Mixing Studies in Annular Centrifugal Contactors Comparing Stationary Mixing Vane Options

“…Sathe and co-workers also report measurements of droplet size distribution [15] using laser induced fluorescence and image processing. However, this study was conducted for a simple annular mixer that was liquid-full (no air) and under moderate mixing conditions.…”