Development of low cost electrostatic spray-charging system for liquid formulations

Abstract

The introduction of electrically charged sprays in agricultural application has become inevitable for better control on droplet transference with reduced drift and increase in application efficiency with less spray chemical requirements. In the present study was under taken to develop an electrostatic induction spray charging system as attachment to powered knapsack mist-blower. A high voltage generator was fabricated on the basis of Cockcroft-Walton voltage multiplier principle with input of 6 V DC battery to provide high voltage required at the developed charging electrode assembly (Model III, Model IV and Model V) for inducing electrostatic charge on spray droplets. As the existing (Model I) and redesigned (Model II) nozzle failed to give fine atomization, a self-atomizing hydraulic nozzle was developed for delivering the droplet spectrum required for effective electrostatic charge induction. The three working models (III, IV and V) were evaluated for charge to mass ratio (mC.kg-1) at five electrode potentials (1 kV, 2 kV, 3 kV, 4 kV and 5 kV), four electrode placement positions (0 mm, 5 mm, 10 mm and 15 mm) and five distances (50 cm, 100cm, 150 cm, 200 cm and 250 cm) from the nozzle. Model V with electrode voltage potential at 5 kV and EPP at 5 mm shown the maximum CMR value (1.088 mC.kg-1), followed by Model III (0.888 mC.kg-1) and Model IV (0.777 mC.kg-1) with same combination of variables. In contrast with commercial system (ESS-MBP90) it was observed that except at 50 cm distance from nozzle, Model V (at 4 kV and 5 kV) surpassed commercial system in CMR from 100 cm to 250 cm distance. To avoid air blast injury of plant, the nozzle has to be 100 cm to 150 cm away from the plant. The droplet spectrum of the developed system was analysed and observed that the size of droplets were 100 to 200 μm. The deposition efficiency of the developed system was on par with that commercial unit, and was within the range of 60 to 70 per cent. The developed system found to be cost effective and significantly consistent than the commercial system.