Effect of turbulent kinetic energy dissipation rate on the prediction of droplet size distribution in stirred tanks

Large blade impeller application for turbulent liquid–liquid and solid–liquid mixing

“…As it can be observed, the large blade impeller gives rise to almost uniform turbulent characteristics in the vessel volume, which is a significantly different feature with respect to conventional fast impellers (e.g., in the work of Maluta et al [ 31 ] ). As already highlighted, for instance, by Avazpour et al, [ 3 ] advantages associated to this aspect can be expected in liquid–liquid dispersion operations, where uniform characteristics of the dispersed phase is often of interest and the size distribution is strictly dependent on the local turbulent field features.…”

Numerical and Experimental Analysis of the Daughter Distribution in Liquid‐Liquid Stirred Tanks

“…As previously done by Buffo et al [19], the spatial distribution of e was used to calculate the breakage rate, which in the present work was modeled with the kernel developed by Alopaeus et al [14]. The kernel was modified with the adoption of a scalar correction to account for the grid dependence of the parameters, as was done in a previous study [18], and the resulting breakage (h) kernel is reported in Eq. ( 2).…”

“…The system studied in this work was a stirred tank previously employed in liquid-liquid investigations [17,18]; it consists of a cylindrical, flat-bottom, fully baffled tank with both its diameter T 1) and its height equal to 0.23 m. The agitation was provided by a Rushton turbine with a diameter equal to T/3, mounted on a central shaft with an off-bottom clearance equal to T/2. The total volume of the mixture was equal to 9.8 L.…”

“…A simplified zero-spatial dimensional model was adopted to describe the evolution of the DSD in the operating conditions presented in Sect. 2, just considering the volume distribution of the turbulent dissipation rate e. To obtain the distribution of e, single-phase Reynolds-averaged Navier-Stokes (RANS) CFD simulations were performed in OpenFOAM 5.0 with a highquality mesh and a modeling approach that produced gridindependent turbulent flow fields in good agreement with experimental data [18]. The model is based on the Eulerian description of both liquid phases, the two-fluid model, and the turbulence closure was achieved by means of the standard k-e turbulence model [18].…”

“…where the values of the grid-independent parameters in the breakup kernel, C 0 1 = 2.98, C 0 2 = 0.12, and C 0 3 = 0.25, were taken from a previous investigation [18], and the scalar correction F results from the ratio of the presumed turbulent dissipation rate in the impeller zone predicted with an infinitely fine mesh and the turbulent dissipation rate predicted with the adopted computational grid, and it is equal to 1.17 in this work [18]. In the very dilute conditions considered in this work, one common assumption is to neglect the coalescence inside the stirred tank [20].…”