Kinetics of drop breakup during emulsification in turbulent flow

Systematic set of emulsification experiments is performed to elucidate the role of several factors, which control the process of drop breakup during emulsification in turbulent flow. As starting oil-water premixes we use emulsions containing monodisperse oil drops, which are generated by the method of membrane emulsification. By passing these premixes through a narrow-gap homogenizer working in turbulent regime, we study the evolution of the number concentration of drops with given diameter, as a function of emulsification time. The experiments are performed at high surfactant concentration and low oil volume fraction to eliminate the process of drop-drop coalescence. The experimental data are analyzed by using a kinetic scheme, which takes into account the generation of drops of a given size (as a result of breakup of larger drops) and their disappearance (as a result of their own breakup process). The analysis allowed us to determine the rate constant of the process of drop breakup, as a function of drop diameter, hydrodynamic conditions during emulsification, interfacial tension and viscosity of the drop phase. The breakup rate constants, determined in this way, are compared with available theoretical expressions in the literature and their modifications. An explicit expression is designed to describe the experimental data, which accounts for: (a) the frequency of collisions between drops and turbulent eddies, and (b) the efficiency of drop breakup, which is related to the energy required for drop deformation and breakup into smaller drops. The energy for drop deformation contains two contributions, originating from the drop surface extension and from the viscous dissipation inside the drop, respectively. Initial emulsions Final emulsion Narrow gap homogenizer