Design and development of centrifugal blower and rotary atomizer of air-assisted sprayer for mango orchard

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Date
2014
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MPUAT, Udaipur
Abstract
Precise and uniform application of chemicals on the target is needed for effective pest control. Air assisted spraying system improves deposition. Deposition of spray droplets, requirement of air volume and spray volume are influenced by canopy volume, leaf area and leaf density of tree. In developed countries high power air-carrier sprayer are used for blanket application. In India air-assisted sprayers, operated by small tractors are used for spraying on small fruits likes grapes, pomegranate and citrus .These designs are not suitable for tall tree orchards like Mango. A suitable alternative will be localized application by air-assisted system operated by 35 hp tractor. The rotary atomizer producing narrower range of spray droplets of 150-350 μm is needed for effective deposition .The centrifugal blower and rotary atomizer for air-assisted sprayer operated by 35 hp tractor was developed. To assess air and spray volume requirement for spraying on matured Mango tree parameters were measured and canopy volume was estimated. The mean leaf area, leaf density was measured and total leaf area of tree was estimated. Air volume and spray volume requirement per tree was calculated. The centrifugal blower with forward curved blade was designed to deliver the air of 3 m3/s for 35 hp tractor. Three impellers A, B, C with 36, 40 and 44 blades were fabricated and the performance was evaluated in the laboratory as per AMCA standard. The best performance was observed for Blower B and was selected for development of air assisted sprayer. A rotary atomizer was designed and developed. Field prototype of air assisted sprayer with centrifugal blower B and rotary atomizer was then developed which consisted of a frame , htp piston pump, 200 lit chemical tank, gear box ,spray delivery head, control panel , operator seat and spray hoses. Performance of rotary atomizer for spray deposition pattern at various distances from sprayer outlet was evaluated in the laboratory. Parameters consisting of 2.80 m3/s of air discharge, 3900 rpm of rotary atomizer speed and 5.5 l/min of discharge rate were observed for effective spray deposition in term of VMD, NMD, DD and UC. Air trajectories profile of the developed air assisted sprayer at various distances from spray delivery outlet was also evaluated in the laboratory. The developed airassisted sprayer was tested in the mango orchard in terms of spray deposition and its performance was compared with commercially available air assisted sprayer operated by 50 hp tractor. The droplet deposition in terms of VMD, NMD, V0.9, V0.1, DD, UC and RS was determined. At all zones and locations mean VMD was 190.10 μm. Bigger droplets were observed on the front as compared to back of leaves. The spray deposition at bottom zone was higher as compare to middle and top zone. Effective field capacity, field efficiency and cost of operation were evaluated. Drift and dripping during spraying was quantified. The commercial sprayer gave higher deposition than required at all zones and more variation of spray deposition, drift and dripping. The developed sprayer performed better in spray deposition with minimum drift and dripping losses, less spray solution requirement and lower cost of operation as compared to commercial sprayer. Keyword : Canopy volume, leaf area, spray volume, air volume, air assisted sprayer, centrifugal blower ,rotary atomizer,VMD ,NMD,UC ,V0.9, V0.1, DD, RS ,Spray deposition ,drift ,dripping .
Description
Design and development of centrifugal blower and rotary atomizer of air-assisted sprayer for mango orchard
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Citation
Ganpatrao and Mathur, 2014
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