Experimental Study on the Droplet Size and Charge-to-Mass Ratio of an Air-Assisted Electrostatic Nozzle

Abstract

An air-assisted electrostatic nozzle uses a combination of air-assisted atomization and electrostatic spray technology. This article optimizes the existing air-assisted electrostatic nozzles in terms of structural design to obtain a higher charge-to-mass ratio and a smaller droplet size. The optimized air-assisted electrostatic nozzle was studied experimentally, and the effects of liquid pressure, air pressure and applied voltage on the droplet size and charge-to-mass ratio were investigated. Comparing the effects of air pressure, liquid pressure and applied voltage on the charge-to-mass ratio and droplet size, the relationship curves of the droplet size and charge-to-mass ratio under each voltage were fitted using the Rayleigh charge limit theory. For a higher CMR during the spray operation, applied voltages between 2.5 kV and 3 kV, an air pressure between 0.4 bar and 0.6 bar, and a liquid pressure of less than 0.9 bar could be chosen. The optimized air-assisted electrostatic nozzles not only have small droplets but also have high charge-to-mass ratios, reducing the need for pesticide use and thus protecting human health and the environment.

Effects of sprayer speed, spray distance, and nozzle arrangement angle on low-flow air-assisted spray deposition

“…The spraying system mainly consists of an electric water pump powered by a 12V battery, a 200L polyethylene tank, and air-assisted nozzles. The air-assisted nozzle is a self-designed low-flow nozzle ( Dai et al., 2022 ). When the air pressure is 0.5bar and the liquid pressure is 0.7bar, the spray angle of the air-assisted nozzle is 18°, the volume flow rate is 0.21L/min, and the volume median diameter of the droplet is 35µm.…”

“…In this paper, a low-flow air-assisted sprayer for vineyards was designed based on a self-designed air-assisted nozzle to reduce the amount of pesticide spraying ( Dai et al., 2022 ). In order to improve the quality of sprayer operation, an orthogonal test on three factors, namely, sprayer speed, spray distance, and the nozzle arrangement angle, was designed to determine the optimal working conditions of the sprayer.…”

A Review: Development of Plant Protection Methods and Advances in Pesticide Application Technology in Agro-Forestry Production

“…Through the measurement of gas-liquid-solid multiphase flow fields, etc., the flow appearance and deposition characteristics of multiphase flow fields, as well as the influence of spraying parameters on droplet transportation and deposition, were analyzed, and the best operating parameters were determined [168,169]. For electrostatic pesticide spraying, the electric field distribution, the charge-to-mass ratio and the charge attenuation pattern of charged droplets could be tested [170]. A large number of studies have been carried out on the effects of spraying parameters and target characteristics on the deposition and drifting of pesticide droplets around the world [168][169][170][171][172][173][174][175][176].…”

Analysis of the Factors Affecting the Deposition Coverage of Air-Assisted Electrostatic Spray on Tomato Leaves

“…In addition, air-assisted electrostatic spraying technology also inherits many factors that can affect the deposition effect of air-assisted spray and electrostatic spray. These influencing factors mainly include charged voltage, spray distance, spray pattern, air velocity and spray pressure [19][20][21].…”

“…At present, there are few studies on the influence of air-assisted electrostatic spraying platform dynamics on droplet deposition coverage, and the related studies are not comprehensive. Dai et al examined the effects of spray pressure, air pressure and applied voltage on droplet size and charge-to-mass ratio [19]. Neto et al compared the effects of different spray volumes and charges on spray deposition [20].…”