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Multiscale study and modeling of dispersion properties relevant for liquid-liquid extraction : adaptation of breakup and coalescence kernels to industrial processes, 2019

— Authors: Castellano, S. —

State Key LPhd-thesis, Université de Lyon. (link)

This thesis project focuses on the study of the hydrodynamics of dispersions in liquid-liquid extractors used in the nuclear recycling industry. In the first part of the project, a homogeneous population balance model (0D-PBM), based on the evaluation of volume-average coalescence and rupture rates, is proposed. The method takes into account spatial inhomogeneities in the mixture, including the probability density function of the dissipation of turbulent kinetic energy in the device. The model is capable of reproducing low-viscosity turbulent liquid-liquid dispersion experiments. In the second part of this study, a generalized model for rupture and coalescence nuclei, valid for the whole spectrum of turbulence, is proposed and validated. Most of the cores available in the literature are based on the Kolmogorov second-order structure function, which is valid only in the inertial domain. However, in many industrial situations, most of the drops can have a size in the dissipative domain, where the Kolmogorov second-order structure function does not apply. The generalized model is based on Davidson’s second-order structure function, which is valid across the entire spectrum of turbulence. In the last part of the study, a model to simulate the hydrodynamic behaviour of a pulsed column is proposed. The model is based on a 1D population balance, the source terms of which were modelled using generalized Coulaloglou and Tavlarides nuclei. Turbulent inhomogeneities in the pulsed column were taken into account by the probability density function of the turbulent dissipation rate.