The Experiment And Numerical Simulation Study On The Preparation Of Micro-nano Emulsions By High Pressure Microfluidization

High pressure homogenization had been widely applied in preparation of micro-emulsions,while there were many problems need to be resolved such as: the change of flow field parameters in homogeneous process,the distribution features of flow field,influencing factors of droplet size.In this paper,the high pressure homogenizer,Niro-Soavi NS1001 L,was experimental model,theoretical analysis experimental research and the numerical simulation method was used to research the influence on the change of droplet size under different operating parameters and the changing mechanism of droplet size.On the macro the fragmentation process of the droplet was analyzed based on the Breaking Theory,on the micro the breakup and reformulation process of droplet was analyzed on the vision of liquid sheet.Through analyzing,the understanding of change of droplet size in High pressure homogeneous process was deepened,it also laid a theoretical basis for analysis of experimental and simulation results.Single factor and orthogonal experiments were carried on through constructing experimental platflat high pressure homogenization so as to study three variables homogenization pressure,homogenization time and volume fraction of dispersed phase.Through observing the distribution state of droplet in continuous phase under the microscope and orthogonal experiments,effect law of each parameter on droplet size and the most obvious influence factors was get.In addition finding out the shortage of experiment,experimental reference was provided for the following simulation.The high pressure homogenization model was built and meshed by pre-processing software,Gambit,and refined partial grid.The realizable K-ε turbulence model was used to simulate the continuous phase.PBM(Population Balance Model)was used to simulate fragmentation and recoalescence processes of dispersed phase.The pressure field,velocity field,turbulent kinetic energy field and effects of pressure on speed and turbulent kinetic energy was get in high pressure homogeneous cavity.The result showed that fragmentation and recoalescence processes of droplet was dominated by turbulent,with the increase of homogeneous pressure,recoalescence phenomenon was more obvious,volume fraction of discrete phase determined the number of collisions between droplets.