Development of a battery operated electrostatic sprayer

Abstract

An experimental prototype of backpack type rechargeable battery powered air assisted electrostatic sprayer was developed, maintaining the commercial competence and affordability of the marginal and small farmer community in India. The developed prototype was analyzed for charge induction on spray droplet, deposition characteristics and field performance on brinjal crop at instructional farm of KCAET, Tavanur. The developed prototype electrostatic sprayer established good levels of charge induction on the spray particles at different stages of electrode potentials (1 kV to 12 kV). The maximum Charge to Mass Ratio (CMR) of electrostatically charged spray was observed to be 1.79 mC kg -1 at a charging electrode potential of 9 kV at 2 ml s -1 nozzle discharge. The Electric Ducted Fan (EDF) for high velocity air assistance was capable of carrying the charged spray droplets towards the distant targets such as orchard trees and longer (up to 5 m) spray throw for field crops. The high pressure atomization system produced the fine droplet spectrum having Volume Median Diameter (VMD) of 91.36 μm which aided better charge induction and the resultant wrap-around effect. The field study revealed that the electrostatic charged spray enhanced the on-target deposition nearly about two folds than the conventional spray. Also, the biological efficacy was observed to be 54.62 per cent superior to the conventional spraying method. As there were very less moving mechanical components, reduction in overall noise and vibrations of the spraying system could offer better operator comfort and reduced system maintenance. The cost of a commercial electrostatic (ESS ® MBP90TM) spraying system (Rs. 4.5 lakhs) was approximately 40 times higher than that of the developed system (Rs. 12000). The annual operating cost of the developed battery operated electrostatic sprayer was much lesser (Rs. 28302.00) than that of commercial gasoline engine powered knapsack mist-blower (Rs. 44677.50). Considering the annual operational hours as 250, the hourly operating costs of the developed electrostatic sprayer and the commercial knapsack mist-blower were Rs. 114.00and Rs. 178.00, respectively. The developed battery operated electrostatic sprayer could give an overall annual cost saving (Rs. 16376.00) of 36.65 per cent over the engine powered knapsack mist-blower. Moreover, the developed sprayer with reduced pesticide (active ingredient) dose could lessen the annual pesticide expenses by 40 per cent compared to the conventional high volume spraying. The environmental advantage was significant as a large quantity of harmful chemicals could be salvaged from spilling into the soil which eventually reach the ground water and enter into the biological system ultimately harming humans. The overall features and cost effectiveness of the developed prototype could encourage majority of the Indian famers to upgrade with the air assisted electrostatic spraying technology leading to their socio-economic welfare.