Research On Emulsification Process In LL-Triangle Micromixer

Emulsion is a dispersion system containing two kinds of immiscible liquids,which has a wide range of applications in industry.The conventional emulsification method is mixing,colloidal grinding and homogenization and other mechanical methods.This droplet breaking technology is based on uneven stretching and shear flow,which can achieve the purpose of forming smaller emulsion droplets,but at the same time it is very It is easy to cause a wide droplet size distribution and poor monodispersity,making it difficult to improve the overall quality of the emulsion.Therefore,improving the controllability of emulsion size,temperature,shape,etc.is the top priority of improving emulsification technology.In the past decade,microfluidic technology has been significantly developed.Microfluidic uses microchannels with a size of tens to hundreds of microns to process or manipulate tiny fluids.It is a new material involving chemistry,fluid physics,The cutting-edge technology of many emerging interdisciplinary subjects.The microfluidic-based method is more reliable for the preparation of monodisperse emulsified droplets.It can enhance the heat and mass transfer between the dispersed phase,the continuous phase and the inner wall of the device;the size,shape and composition of a single droplet can be more Precise control.This article first introduces the overview of microchannel emulsification,then builds a microreactor experimental device,and finally combines theory and practice to analyze the mechanism of emulsified droplet breakage at different flow rates and flow rate ratios.The mechanism of the emulsification process is complicated.The liquid/liquid two-phase flow process at the micro scale is very different from the traditional macro scale flow process.It is usually the interfacial tension,viscous force,inertial force,the force generated by hydrodynamic pressure and The result of a balance between external stimuli.Droplet rupture is mainly affected by geometric configuration and flow state.Under different operating conditions,there are different flow patterns such as squeeze,drip,and jet in the micromixer,as well as pressure-driven,shear-driven,and co-driven liquids.The droplet formation mechanism and the variation rule of the droplet size under different formation mechanisms are also very different.In this experiment,diiodomethane was used as the oil phase,and deionized water was used as the water phase.An oil-in-water(O/W)emulsion was prepared by a LL-Triangle micromixer within a relatively large flow rate ratio,and the liquid was collected by a high-speed camera.Visualize the droplet rupture process:from the microscopic T-shaped structure,explore the force process of the droplet from the blocked channel to the deformation and rupture;study the different flow patterns from the larger cavity,and analyze the influence of the particle size Physical property parameters and establish a fitting equation to explore the best emulsification conditions.