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Electrostatic Sprayer for Agricultural Application

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Electrostatic sprayer for agricultural application
In order to protect food and fibre crops against insect, disease and weed pests, usage of agricultural chemicals such as insecticides, fungicides and herbicide is essential. Entomological studies have established that in numerous cases, smaller droplets of pesticide spray provide greater biological efficacy per unit mass of pesticide than do the larger droplets for achieving insect control but drift was the major problem. Thus, the recent concept of spraying is to spray the target pest more efficiently by selecting optimum droplet size and density for maximum retention and coverage. Some cases in rather old data, 95% of the chemical applied can be wasted to the ground or at most 50% of mass transfer onto the desired plant. Electrostatic spraying would offer a possible solution to those environmental problems; by reducing spray drift and improving coverage of chemical to target plant. These application areas broadly include ground equipment for spraying plants of row crops, orchards and greenhouse, even aircraft spraying.
An inductive electrostatic sprayer was designed by Weidong, et al. The test result showed that the charge-to-mass ratio could reach 0.951 mC/ Kg when electrostatic voltage was 20 kV and working pressure was 0.25 to 0.4 MPa. The particle size distribution of charged droplets were more concentrated than that of uncharged droplets, the axial velocity of charged droplets was faster than that of uncharged droplets, and the velocity distribution uniformity was also improved. The average deposition rate under charging conditions was 14% higher than that in uncharged conditions. Moreover, the deposit rate of the back of the leaf was evident.
Previously designed and constructed electrostatic sprayer was evaluated in order to quantify the charging of droplets (Maynagh, et al). Liquid atomization was achieved by using an ultrasonic nozzle. The maximum flow rate of nozzle was 25 ml/ minute and vibration frequency was about 30 kHz. The induction method was used for charging the output droplets. The independent parameters in this study included: voltage at four levels of 1.5, 3, 5 and 7 kV; air flow speed at six levels of 14, 14.9, 17, 20.2, 21.6 and 23 ms-1; charging electrode radius in two levels of 10 and 15 mm, horizontal distance between the electrode and nozzle tip at four levels of 1.5, 6, 10 and 15 mm; and liquid flow rate at three levels of 5, 12 and 25 ml/ minutes. The maximum charging occurred at 5 ml/ min flow rate, voltage of 7 kV, air flow speed of 23 ms-1 and the resulting current was 0.24 μA. On dividing the electrical current by the liquid flow rate and changing the scale, the mean charge to mass ratio was 1.032 μC g-1.
References
Jai W; Xue F; Qui B. (2013). Design and Performance of Inductive Electrostatic Sprayer. Journal of Applied Sciences, Engineering and Technology 5(21): 5102-5106.
Maynagh B. M; Ghobadian B; Jahannama M. R. and Hashjin T. T. (2009). Effect of

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Electrostatic Sprayer for Agricultural Application

  1. 1. Chairman Dr. P. K. Sahoo Principal Scientist Bholuram Gurjar M.Tech Scholar Bholuram Gurjar M.Tech Scholar IARI IARI Seminar Leader Dr. Tapan kumar khura Senior Scientist
  2. 2. YIELD LOSS YIELD LOSS Diseases Weeds Insects The estimated crop loss was of the value of Rs 1,40,000 Crores / Year The estimated crop loss was of the value of Rs 1,40,000 Crores / Year (Up to 37% of the total food production is lost) (Up to 37% of the total food production is lost) (Pimentel and Levitan 2008)
  3. 3. Advantages of pesticides Improving productivity Protection of crop from losses/yield reduction Quality of food Disadvantages contamination of the environment  leaving residues in food risk of poisoning of farm workers
  4. 4. Spraying technology HHiigghh vvoolluummee sspprraayyiinngg LLooww vvoolluummee sspprraayyiinngg UUllttrraa llooww vvoolluummee sspprraayyiinngg
  5. 5. PPaarraammeetteerr aaffffeeccttiinngg sspprraayyiinngg
  6. 6. SSpprraayy ddrriifftt Physical movement of pesticide droplets or particles through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target Physical movement of pesticide droplets or particles through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site (Bradley et al 2010) site (Bradley et al 2010)
  7. 7. There are two kinds of drift:- Particle drift is off-target movement of the spray particles Vapor drift is the volatilization of the pesticide modules and their movement off target There are two kinds of drift:- Particle drift is off-target movement of the spray particles Vapor drift is the volatilization of the pesticide modules and their movement off target
  8. 8. DDrriifftt MMaannaaggeemmeenntt Choose appropriate nozzle which can have better converge on surface with optimum size droplet Choose appropriate nozzle which can have better converge on surface with optimum size droplet RReedduucciningg t hthee d disistatannccee b beetwtweeeenn t atarrggeet ta anndd n noozzzzlele i sis u usseeffuul lf foorr d deeccrreeaassiningg d drrifift t SSoommee a adddditiitvivee c caann b bee u usseedd a at ts spprraayyiningg c chheemmicicaal lf foorr r reedduucciningg d drrififtt The reduction in drift used electrostatic force on smaller droplets than the gravitational force The reduction in drift used electrostatic force on smaller droplets than the gravitational force
  9. 9. EEllEEccttrroossttaattiicc sspprraayyEErr wwoorrkkss oonn tthhEE pprriinncciippllEE ooff ccoouulloommbb''ss llaaww Electrostatic force of attraction (F): F = q*E + + + + + + +
  10. 10. Electrostatic Charging System Induction charging (5 to 20 kV) corona charging (30 to 70 kV) Direct charging (25 to 30 kV) Induction charging (5 to 20 kV) corona charging (30 to 70 kV) Direct charging (25 to 30 kV)
  11. 11. CCAASSEE SSTTUUDDYY --II Design and performance of inductive electrostatic sprayer Location: China Objective: Design inductive electrostatic sprayer and evaluates their parameter Jai et al., 2013  Charge to mass ratio  Particle size  Velocity of droplets  Deposit rate of pesticide
  12. 12. CChhaarrggee ttoo mmaassss rraattiioo FFaarraaddaayy ccyylliinnddeerr
  13. 13. CChhaarrggee--ttoo--mmaassss rraattiioo Voltage=20KV
  14. 14. PPhhaassee DDoopppplleerr ppaarrttiicclleess aannaallyyzzeerr
  15. 15. DDrroopplleett ssiizzee ooff cchhaarrggeedd aanndd uunncchhaarrggeedd ddrroopplleettss Droplets size (μm) Uncharged droplets (μm) Charged droplets (μm) D 10 28.1 18.2 D 30 34.8 26.1 D 43 59.2 50.0
  16. 16. DDeeppoossiittiioonn rraattee
  17. 17. PPaarrttiiccllee ssiizzee ddiissttrriibbuuttiioonn Particle size distribution Particle size distribution oof fu unncchhaargrgeedd d droroppleletsts PPaartritciclele s sizizee d disistrtirbibuutitoionn o of fc chhaargrgeedd d droroppleletsts
  18. 18. Distribution of mean axial velocity of charged and uncharged droplets Distribution of mean axial velocity of charged and uncharged droplets Working pressure =0.3 MP
  19. 19. Charge-to-mass ratio increases with working pressure High-pressure electrostatic force can reduce the number and improve the distribution of droplet particles Charged droplets can also improve and enhance the uniformity of mean velocity distribution Deposition rate of charged droplets is better than that of uncharged droplets
  20. 20. CCAASSEE SSTTUUDDYY --IIII Effect of Electrostatic Induction Parameters on Droplets Charging for Agricultural Application Location: Iran Objective: Evaluate and quantify the charging of droplets created by an electrostatic sprayer Maynagh et al., 2009
  21. 21. Experimental set up
  22. 22. R=15 mm R=10 mm Relationship between voltage and current for a 15 mm radius the electrode Relationship between voltage and current for a 10 mm radius electrode N#1 N#2 N#3 N#4 N#5 N#6 (RPM)9300 (RPM)10300 (RPM)11350 (RPM)12100 (RPM)13200 (RPM)14050 (ms-1)14 (ms-1)14.9 (ms-1)17 (ms-1)20.2 (ms-1)21.6 (ms-1)23
  23. 23. Effect on current of distance between electrode and nozzle tip Effect on current of distance between electrode and nozzle tip for R= 15. mm L = Horizontal distance between electrode and nozzle tip (mm) N#4=12100(rpm)
  24. 24. R=10mm, L=10mm R=10mm, L=10mm Effect of liquid flow rate on current Charge to mass ratio versus flow Rate N#3=11350(rpm) 5 12
  25. 25. Voltage on the electrode increases, more charge of the opposite sign to that of the induction surface (electrode) is induced on the droplets Slope of a portion of the curves between 1.5 to 3 kV is greater than that for the other parts for all curves Increasing liquid flow rate, the charged current spray is first increased and then starts dropping
  26. 26. Increment in the relative number of droplets and weakening of the field through wetness of the electrode for liquid flow rates of between 12 to 25 ml min-1 Optimum combination different parameters : Q= 5 ml min-1, V= 3 kV, L= 10 mm, N #4=12100(RPM), and R= 15 mm
  27. 27. CCoonncclluussiioonn Deposition rate of charged droplets is better than that of uncharged droplets (directional movement on the crops and affect the deposition rate on the underside of leaves) High-pressure electrostatic force can reduce the number and improve the distribution of droplet particles Savings of pesticides for the farmers as well as to lesser environmental contamination
  28. 28. Thank you . .

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