| Spray disinfection technology with chicken is one of the key technologies for safe production of large-scale chicken farms.At present,the traditional spray technology is often used for disinfection with chicken.In recent years,the advantages of electrostatic spray in spray sterilization have been increasingly valued by researchers.In order to explore the role of electrostatic spray in the poultry house,this paper explored the key technology of upgrading the common hydraulic fan nozzle into electrostatic nozzle,and carried out electrostatic spray in the laboratory using to study the Distribution of Droplets in the cascading cage.The main research contents of this topic are as follows:(1)Theoretical analysis of the charging mechanism of three electrode induction electrostatic spray and three electrode contact electrostatic spray has been carried out.It is found that the charged regions of the two charging modes are liquid film fracture regions.(2)The charging effect of three electrode induction and three electrode contact electrostatic spray under different electrode parameters was studied and compared.Electrode parameters are: charge polarity,electrode shape,electrode material,electrode distance from the nozzle,electrode spacing.The results show that:(a)When the charging voltage is 0.5-3KV,the charging performance is arranged from good to bad in order: negative high-voltage contact charging,positive high-voltage induction charging,positive high-voltage contact charging and negative high-voltage induction charging.When the charging voltage is 3-5KV,the order of charging performance is negative high voltage contact charge,positive high voltage contact charge,positive high voltage induction charge and negative high voltage induction charge.At lower voltage,the charge to mass ratio of negatively charged droplets is higher than that of positively charged droplets under the same electrostatic spray charging mode.(b)When using three electrode induction electrostatic spray.The electrode material has a significant effect on the droplet charge ratio.The charging effect is brass > stainless steel > aluminum.When using three electrode contact electrostatic spray,the charge to mass ratio of droplet obtained by three different materials has no obvious difference.(c)When two different charging modes are used,The law between the charge-to-mass ratio and the distance between the nozzle and the electrode is same.(d)Under the same conditions,the smaller the electrode spacing,the higher the droplet charge to mass ratio,but the too close electrode spacing will cause the insulation between the nozzle and the electrode to decrease.(3)A method of optimizing electrode parameters based on the electrostatic field analysis of charged liquid film breaking zone was proposed,and the correlation between charged liquid film breaking zone and the charge-mass ratio of droplets was analyzed.The results show that the charged liquid film breaking zone obtained by simulation has a very significant correlation with the charge to mass ratio of droplets obtained by corresponding experiments.The total R square of the two charging modes is 0.948 and 0.963,respectively.(4)The electrode support device was designed and improved,and the theoretical analysis and experimental comparison of the charging area characteristics and the conveying area characteristics of the improved electrostatic nozzle under two charging modes were carried out.The theoretical analysis agrees with the experimental results: the electric field of the two charging modes is similar in the charging area,but in the conveying area,the three-electrode contact charging will be beneficial to the deposition of charged droplets to the target,while the three-electrode induction charging will hinder the deposition of charged droplets to the target.Therefore,the three electrode contact electrostatic spray has more deposition on the target surface under the same conditions,and the loss of droplet winding is less than three electrodes induction electrostatic spray.The charge-to-mass ratio of the two types of charging method decreases as the distance from the nozzle to the mesh target increases.When the distance from the mesh target is 20 cm,the contact electrostatic charge-to-mass ratio can reach 1.82 mC/kg,and the inductive electrostatic spray charge The ratio can reach 1.68mC/kg.(5)In this paper,the dynamic mesh is used to consider the movement of the nozzle in the spray process.The Fluent user defined function and user defined scalar are used to solve the electric field formed by charging electrodes and charged droplets.A CFD model which can completely simulate the dynamic spray process of the hydraulic fan-shaped nozzle is established,and the accuracy of the model is preliminarily verified by qualitative and quantitative analysis.(6)Experiments show that electrostatic spray can increase the deposition distribution at the inaccessible location of ordinary spray,but at the same time,we should also pay attention to selecting suitable parameters. |
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