Spraying performance and deposition characteristics of an improved air-assisted nozzle with induction charging

Electrostatic spraying technology can improve the efficiency of pesticide deposition on the surface of leaves and reduce the environmental pollution caused by pesticide drift, which has an important prospect in agricultural pesticide application. To improve the deposition and penetration of droplets in the crop canopy, we designed and optimized an air-assisted electrostatic nozzle and conducted the spraying performance experiment. Parameters, such as charge-to-mass ratio (CMR) and particle size, were tested and analyzed to obtain the suitable operating parameters of nozzle. The results proved that the improved air-assisted electrostatic nozzle has good atomization and chargeability. There is a good charging effect with a charging voltage of 3,000–5,000 V, the CMR increased 127.8% from 0.86 to 1.97 mC/kg as the charge voltage increases from 1,000 to 4,000 V, at an air pressure of 1.0 bar and liquid flow rate of 200 ml/min. Furthermore, we designed a multi-factor orthogonal experiment, which was conducted using a four-factor, three-level design to investigate the effects of operational parameters and canopy characteristics on droplet deposition and penetration. Analysis of variance (ANOVA) and F-test were performed on the experiment results. The results showed that the factor effect on droplet penetration, in descending order, was as follows: spray distance, leaf area index, air pressure, and air pressure × spray distance. The factor effect on abaxial leaf deposition, in descending order, was as follows: air pressure, spray distance, air pressure × charge voltage, spray distance × charge voltage, and charge voltage. For optimal droplet penetration and abaxial leaf deposition, option A3B1D2 (air pressure 1.5 bar, spray distance 0.2 m, charge voltage 2,500 V) is recommend. The spray nozzle atomization performance and deposition regulation were studied by experimental methods to determine the optimal values of operating parameters to provide a reference for electrostatic spray system development

Development and Experiment of an Online Measuring System for Spray Deposition

To realize the online evaluation of spray quality, an online measuring system for spray coverage and deposition quality is developed. The measuring theory of spray coverage and deposition quality on an LWS (leaf wetness sensor) surface is analyzed. When the spray conditions are constant, there is a linear correlation between the spray coverage on the sensor surface, the spray deposition quality and the LWS output voltage increment. The results of calibration experiments show that when the spray conditions are constant, the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray coverage on the sensor surface is more than 0.75, and the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray deposition quality on the sensor surface is more than 0.90. Based on ZigBee wireless sensor technology, this paper reports an online measuring system for spray coverage and deposition quality at multiple points in the field. The test results show that the online measuring system has good uniformity. Field test results show that the LWS voltage increment and the coverage rate of water-sensitive paper have a good correlation, and the measuring results of the spray deposition quality trend are in good agreement. The fit of the spray deposition quality curves measured by the two methods was 0.8924. The research results in this paper can provide a reference for using LWS sensors to measure spray coverage and deposition quality

A CBM development well type optimization method based on the long-run marginal cost

Reasonable optimization of development well type is the prerequisite to realize the economic and effective development of coalbed methane (CBM). However, the existing CBM development well type optimization methods are disadvantageous in many aspects. CBM is a kind of typical unconventional natural gas resource, and its study focuses on single-well evaluation. In this paper, the assessment method and the evaluation index (EI) for CBM development well type optimization based on the long-run marginal cost (LRMC) were constructed on the basis of CBM characteristics from the perspective of economic feasibility. Then, the corresponding decision making criteria were established. Finally, this newly developed method was applied to the well-type optimization of different development blocks in two important CBM development basins in China. And the following research and application results were obtained. First, under the current technical and economic conditions, both directional well and horizontal well are economically feasible to the development of Block A in the Qinshui Basin and Block B in eastern margin of the Ordos Basin, and the economically optimal well type is a horizontal well in Block A and a directional well in Block B. Second, compared with single-well steady daily gas production and single-well investment, the evaluation results on the schemes of different well types present critical value, above which the economic benefit of different schemes are equivalent. Third, EI of different well types is affected by many factors, e.g. geological characteristic of gas reservoirs, single-well production profile, CBM selling price, investment and cost. Therefore, it is necessary to carry out dynamic analysis and update in time based on the change of various influential factors so as to ensure the rationality of decision-making. In conclusion, this newly developed method is intrinsically consistent with traditional evaluation methods, and it is more advantageous with strong operability, intuitive evaluation results and quick and accurate optimization of CBM development well types. Keywords: Coalbed methane (CBM), Long-run marginal cost (LRMC), Development well, Well-type optimization, Directional wells, Horizontal wells, Surface development, Decision making criteria, Critical poin

Multibody Dynamics Simulation and Vibration Test for High Clearance Orchard Sprayer

High clearance sprayer is a high-efficiency pesticide application machine in orchard management. In this paper, operational safety of high clearance sprayers is validated by using finite element simulation and vibration testing. The 3D model of the frame is simplified by using shell units instead of solid units, the static performance of high clearance sprayer frames under static full load and ultimate torsional conditions was studied by means of finite element simulation tests, the mechanical properties of the frame under step excitation were studied by multi-body dynamic simulation test. The simulation results show that, at a safety factor of 1.5, the maximum stress extremes in the frame are within the safe permissible stress range. During the dynamics analysis, a tire-ground contact simplified model was proposed. The results of the modal analysis show that the inherent frequency distribution of the high clearance sprayer is compact, and the vibration test has measured a large difference between the engine vibration frequency with the inherent frequency of the frame, this means that resonance will not occur. The theoretical analysis shows that the designed high clearance sprayer meets the requirements of large cross-row field operations, the study provides a reference for the overall design of the high clearance sprayer

Development and Experiment of an Online Measuring System for Spray Deposition

To realize the online evaluation of spray quality, an online measuring system for spray coverage and deposition quality is developed. The measuring theory of spray coverage and deposition quality on an LWS (leaf wetness sensor) surface is analyzed. When the spray conditions are constant, there is a linear correlation between the spray coverage on the sensor surface, the spray deposition quality and the LWS output voltage increment. The results of calibration experiments show that when the spray conditions are constant, the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray coverage on the sensor surface is more than 0.75, and the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray deposition quality on the sensor surface is more than 0.90. Based on ZigBee wireless sensor technology, this paper reports an online measuring system for spray coverage and deposition quality at multiple points in the field. The test results show that the online measuring system has good uniformity. Field test results show that the LWS voltage increment and the coverage rate of water-sensitive paper have a good correlation, and the measuring results of the spray deposition quality trend are in good agreement. The fit of the spray deposition quality curves measured by the two methods was 0.8924. The research results in this paper can provide a reference for using LWS sensors to measure spray coverage and deposition quality

Effects of sprayer speed, spray distance, and nozzle arrangement angle on low-flow air-assisted spray deposition

Air-assisted spraying technology is widely used in orchard sprayers to disturb canopy leaves and force droplets into the plant canopy to reduce droplet drift and increase spray penetration. A low-flow air-assisted sprayer was developed based on a self-designed air-assisted nozzle. The effects of the sprayer speed, spray distance, and nozzle arrangement angle on the deposit coverage, spray penetration, and deposit distribution were investigated in a vineyard by means of orthogonal tests. The optimal working conditions for the low-flow air-assisted sprayer working in the vineyard were determined as a sprayer speed of 0.65m/s, a spray distance of 0.9m, and a nozzle arrangement angle of 20°. The deposit coverages of the proximal canopy and intermediate canopy were 23.67% and 14.52%, respectively. The spray penetration was 0.3574. The variation coefficients of the deposit coverage of the proximal canopy and intermediate canopy, which indicate the uniformity of the deposition distribution, were 8.56% and 12.33%, respectively

Experimental Study on the Droplet Size and Charge-to-Mass Ratio of an Air-Assisted Electrostatic Nozzle

An air-assisted electrostatic nozzle uses a combination of air-assisted atomization and electrostatic spray technology. This article optimizes the existing air-assisted electrostatic nozzles in terms of structural design to obtain a higher charge-to-mass ratio and a smaller droplet size. The optimized air-assisted electrostatic nozzle was studied experimentally, and the effects of liquid pressure, air pressure and applied voltage on the droplet size and charge-to-mass ratio were investigated. Comparing the effects of air pressure, liquid pressure and applied voltage on the charge-to-mass ratio and droplet size, the relationship curves of the droplet size and charge-to-mass ratio under each voltage were fitted using the Rayleigh charge limit theory. For a higher CMR during the spray operation, applied voltages between 2.5 kV and 3 kV, an air pressure between 0.4 bar and 0.6 bar, and a liquid pressure of less than 0.9 bar could be chosen. The optimized air-assisted electrostatic nozzles not only have small droplets but also have high charge-to-mass ratios, reducing the need for pesticide use and thus protecting human health and the environment