Influences Of Environmental Humidity On Droplet Evaporation And Particle Deposition

The evaporation of droplets is widespread in nature and human life,and has long been concerned and studied.The evaporation process of pesticide droplets on the surface of plant leaves will affect the deposition pattern of pesticide components on the leaves,which will affect the utilization of pesticides and the prevention and control of forest pests and diseases.Therefore,accurately controlling the evaporation process of pesticide droplets and controlling the deposition shape of pesticide components on the leaves after evaporation is an important issue in improving the utilization rate of pesticides and protecting forestry resources.In addition,in the fields of printing,coating,medicine,refrigeration,and new material preparation,particle deposition after droplet evaporation also plays a very important role.For droplets,the flow characteristics of the liquid during evaporation have an important effect on the movement and deposition of particles in the droplet.Therefore,it is of great academic significance and application value to understand the liquid flow inside the droplet during evaporation and to detect the movement and deposition process of solute particles in the droplet.So far,there has been a lot of research on droplet evaporation,but there are few studies on the effects of environmental humidity on droplet evaporation process and particle deposition,especially the evaporation characteristics of droplets in saturated steam environment.This paper first developed a set of precise humidity control device,which can realize the precise control of the environmental humidity during droplet evaporation.Combined with particle imaging velocity measurement technology,using fluorescent particles as tracer particles,the droplets under different environmental humidity were studied.Evaporation and particle deposition.Studies have shown that as the ambient humidity increases,the deposition pattern of droplets gradually changes from boundary deposition to uniform deposition.In this paper,the motion law of particles in droplets under saturated steam environment is also studied experimentally.It was found that the particles in the droplets undergo random Brownian motion under saturated vapor pressure without significant directional movement,which indicates that the droplets evaporate slowly and almost without evaporation.The experiment also found that droplets of the droplets deposited in a saturated environment were deposited very uniformly.The research in this paper will provide a theoretical basis for the prediction and control of particle deposition in evaporative droplets.