Study on Electrostatic Pesticide Spraying System for Low-Concentration, High-Volume Applications

Abstract

We have developed an electrostatic pesticide spraying system for low-concentration, high-volume applications to reduce vegetable production costs through savings in agricultural chemical usage and working hours for pest control. The electrostatic spray charging device (ESCD) has an outer annular induction charging electrode around a hydraulic nozzle with a high flow rate. The charge-to-mass ratio of spray droplets was -0.30 to -0.45 mC/kg at +4 kV, using a hollow-cone nozzle with a high flow rate delivering 1.0 to 2.6 L/min. No discharge or electric leakage occurred from the electrode. Using this device, we developed two types of sprayers. One type was an electrostatic boom-type sprayer for cabbage vegetables. Field tests showed that this boom-type sprayer reduced the amount of required pesticide application by 30% as compared to the conventional method. The other type was a spraying robot for greenhouse melons. There was no significant difference in the control of insect pests between robot spraying and the conventional manual spraying method. The effective field capacity of the robot was 3.8 a/h.

Review of electrostatic system parameters, charged droplets characteristics and substrate impact behavior from pesticides spraying

“…Electroplating copper with nickel material in an electrode design for electrostatic spraying was found to be suitable to enhance the effectiveness of spray when optimally positioned at a distance between 2.0-3.0 mm from the nozzle aperture [47] . A 1.6 mm electrode distance resulted in a reduction of charge-mass ratio up to 13%-18% [37,38] . Due to an interactive effect of Coulombic forces on charged liquid droplets, an electrodeposition in the nozzle aperture should be relatively close to the ruptured liquid film to enhance droplets charging effectivity [24,57] .…”

“…In crop protection, electrostatic spraying is widely used for the application of plant protection products. Ever since, many types of equipment ranging from manual or motorized backpack sprayers, tractor mounted sprayers, man-aerial sprayers, to the unmanned aerial vehicle (UAV) has been designed and tested for electrostatic spraying of pesticides [36][37][38][39][40][41] . However, to overcome the human risk factor during pesticide spraying, an electrostatic spraying technology could be incorporated into the robotic pesticide spraying system in plant protection.…”

“…There was an observable marginal increase in chargeability with respect to an increase in applied voltage until the highest charge-to-mass ratio of 1.686 mC/kg was obtained at the maximum 10 kV applied voltage. Yu et al [39] also applied 10 kV to a formulation to achieve smaller droplet sizes and spray distribution uniformity at an entrained charge of 2.65 mC/kg. It is therefore not clear about the maximum CMR for 10 kV applied voltage in the electrostatic spraying system, hence the need to investigate for the optimum level for pesticide application.…”

“…The smaller the droplet sizes, the greater the numbers for the same formulation. The optimum droplet sizes for effective spraying should be at about VDM of 81.8 μm [39] . The charge-mass ratio from larger droplets is also lower than smaller droplet sizes in electrostatic spraying system [66] .…”

Electrostatic Induction Spray-charging System (Embedded Electrode) for Knapsack Mist-blower

“…As the method has no direct contact with the working fluid, the chances of getting high voltage shock to the operator are negligible and the power consumption is also considerably lower than the other methods [15,16]. This made the electrostatic induction charging as the most suitable method for charging agricultural spray liquids [17,18]. Majority of agricultural chemicals are applied as water based formulations, which has a polar molecular structure and a large value of electric dipole moment due to hydrogen covalent bonds.…”