Development of electrostatic pressure-swirl nozzle for agricultural applications

International Journal of Agricultural and Biological Engineering

et al. 2019

Electrostatic spraying application is adopted in crop protection to prevent pest infestation, to improve product quality and to maximize yield. It involves a superposition of charges to pesticide spray droplets to attract substrate ions at obscured surfaces. The droplets wraparound effect reduces off-target deposition, enhances on-target spray and invariably improves spray efficiency. Electrostatic spraying system works effectively at optimum parameters in combination with charging voltages, application pressures, spraying height regimes, flow rate, travel speed, electrode material, and nozzle orientation. Many combinations of the system parameter settings have been systematically used by researchers for the electrostatic application, but there are unknown specific optimum parameters combinations for pesticide spraying. Since droplets chargeability influences the effectiveness of electrostatic spraying system, the parameters that produce ideal charge to mass ratio determine the functionality of the spraying deposition, retention and surface coverage. This article, therefore, analyses electrostatic system parameters that produce suitably charged droplets characteristics for effective impacting behavior of pesticides on substrates. Increasing applied voltages consequently maximizes charge-mass ratio to optimum and starts declining upon further increase in voltages beyond a critical point. This review further proposes the selection of an optimum electrostatic parameters combination that yields optimum droplets chargeability in pesticide application. Also, it is necessary to investigate the charge property of substrates prior to pesticide application in order to superpose the right opposite charge on spray droplets at rupture time during electrostatic spraying system.

Section: Electrostatic Spraying Application Of Pesticidesmentioning

confidence: 99%

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

Appah

International Journal of Agricultural and Biological Engineering

et al. 2019

“…The electrostatic sprayer is a system that electrically charges the finely divided particulate matter inductively [1][2][3][4][5]. To use the technology efficiently, it is very important to optimize the parameters of the spray nozzle.…”

Section: Introductionmentioning

confidence: 99%

Computational Modeling and Experimental Evaluation of the Effects of Electrode Geometry and Deposition Target on Electrostatic Spraying Processes

Patel¹,

Sharma²,

Nayak³

et al. 2015

IJCA

Electrostatic force field application is one of the most promising methods for spraying protective liquid sprays onto the biological surfaces of crops, orchards, vineyards and trees, because electrostatic space charge and image deposition forces enhance the uniformity of spray on the target surface and increases the transfer efficiency, mass transfer and adhesion. The study has been carried out to know the effects of electrode geometry, deposition target and spray cloud through computational modeling using COMSOL Multiphysics. In this work, four different shaped targets, four different geometry of electrodes and four stages of spray cloud are analyzed to know the effects of resultant electric field to charge the conductive liquid sprays. Comparative study of electric field among all the four shaped targets resulted that elliptical target has the maximum resultant electric field followed by conical, spherical and cylindrical target respectively. Similarly in case of electrode geometry, electric field of square electrode with circular cross-section found to be optimum followed by circular electrode with circular cross-section, circular electrode with square cross section and square electrode with square cross section respectively. The experimental results are in good agreement with computational modeling of charging the liquid sprays.

“…In the past 30 years, extensive studies and experiments have been carried out to avoid the disadvantages, improve the atomization quality, and expand the applications of the electrostatically assisted twin-fluid atomization for processing different nozzles, electrodes, and charging methods and using a variety of theoretical, numerical and experimental approaches [8][9][10][11][12][13][14][15][16][17]. Compared to conventional atomization techniques mainly by means of the aerodynamic forces, the electrostatically assisted twin-fluid atomization device generates a desired size distribution and sufficient surface charge droplets, which could be facilitated to improve deposition on various targets especially on the underside of the part and significantly reduce the drift of small inhalable droplets due to electrical forces.…”

Section: Introductionmentioning

confidence: 99%

“…Im et al experimentally investigated detailed information on the electrostatic rotary-bell paint spray structure and transfer processes and provided qualitative information on the atomization mechanism [12]. Laryea and No developed an electrostatic pressure-swirl nozzle and the result proved to be relevant due to the minimum pesticide input, increase deposition, and reduction in drift [13]. Jahannama et al experimentally and theoretically investigated a two-flow, concentric, internal-mixing induction-charging nozzle for electrostatic spraying and found a significant difference between the uncharged and charged cases [14].…”

Section: Introductionmentioning

confidence: 99%

PDPA Investigation on an Electrostatically-Assisted Twin-Fluid Atomization Flow

Wen

Advances in Mechanical Engineering

et al. 2014

The Phase Doppler Particle Analyzer (PDPA) technique is utilized for characterizing the droplet sizes and velocity profiles in an electrostatic spray flow which is atomized using the aerodynamic forces assisted with electrostatic forces. An electrostaticallyassisted twin-fluid atomization system is presented and spatial distributions of the droplet size and two-dimensional velocity components are measured simultaneously at each specified point. The droplets are firstly ejected from a liquid jet through the nozzle by aerodynamic shear forces, and the breakup mechanism of such an electrostatically-assisted twin-fluid atomization is investigated using the Rayleigh instability conditions through studying the specific surface charges on these droplets measured by a Faraday canister. The discrepancies between experiment data and Rayleigh limit for specific charges of droplets are presented and discussed due to energy transforming from electrical energy to surface energy, energy loss, Taylor instability breakup and nonexcess charge polarization. The measured average velocity profiles and their RMS (root mean square) velocity values for two different scale drops further reveal the effects of the aerodynamic and electrostatic forces on the atomization process.