Study On Electrostatic Atomization Droplets’Size Distribution And Vacuum Evaporation Freeze

Electrostatic atomization is a kind of technology by which a liquid drop in a high voltage electrical field can be divided into droplets whose diameters are in the micrometer grade. We study the electrostatic atomization mechanism and vacuum application in theory and experiment in this paper. In order to clarify characteristics of micro-scale electrostatic atomization and vacuum drying, we investigate general rules of electrostatic atomization and vacuum drying in theory, and design the experiments of electrostatic atomization and vacuum drying, which are conducted under atmospheric environment and vacuum environment. The primary coverage of the research work is shown as follows:1. The theoretical investigation on electrostatic atomization. Firstly, we introduce basic theory of electrostatic atomization, concluding the mechanism of liquid discharged, breaking up and atomization. Then, analyze the application conditions and limitations of the scaling law of estimation of electrostatic spray droplet size.2. The theoretical investigation on vacuum evaporation-freezing of the droplet. Firstly, we introduce the droplets of mass transfer and balance in a vacuum environment, and adopt the mathematical model of droplets’phase equilibrium with surface effect. Then, adopt the mathematical model of single droplet evaporation in a vacuum environment, and modify this mathematical model.3. The experimental investigation on atmospheric electrostatic atomization. Taking into account the limitation of the scaling law, the effects of electrical conductivity and liquid flow rate are examined with de-ionized water and glycerin (by adding appropriate CuSO4to change the electrical conductivity) as the main objects. The results show that droplets obtained under cone-jet mode accord with the scaling low for low viscosity liquids. The high viscosity liquids’ droplet size obtained under cone-jet mode is much smaller than low viscosity liquids. The experimental data accord with the relation(d～Q1/3) of the mean droplet sized and liquid flow Q, and we discover the relation (d～(I/K)0.62) between electrical conductivity K and the mean droplet size d after data fitting, finally have a check on it. Finally, we set up the scaling law d=f(εo,σ,ρ)Q1/3/K0.62of the high viscosity.4. The experimental investigation on electrostatic atomization and vacuum evaporation-freezing. Taking the0.005mol/L CuSO4solution as the main object, inspect electrostatic atomization and vacuum evaporation-freezing. Find the differences between the atmospheric electrostatic atomization and vacuum electrostatic atomization. Compared the experimental data with the mathematical model of single droplet evaporation, we find that experimental data accord with the mathematical model.