Dynamic characteristics of charged droplets in an electrostatic spraying process with twin capillaries

The experimental and simulated investigations on electrostatic spraying with twin capillaries are carried out. The starting electric voltage required for the cone-jet and the deposition characteristics of the droplets are measured.The whole spraying process, which includes jet and droplet motions, is simulated and the simulated results on the motions of jet and droplet are basically consistent with the experiments. According to the simulated results,the contributions of various electric forces to droplet movement are quantitatively analyzed and the droplet dynamic characteristics, especially the interaction mechanism between two sprays, are revealed. The test results on the droplet deposition characteristics partially support the simulated results on the droplet motion. The present work is useful for a better understanding on the interaction between sprays in double or multi-capillary system.

Process Optimization of Cu-en/AP Composite Microspheres Preparation by Electrostatic Spray Method Based on ANSYS Simulation

To investigate the process optimizationof Cu-en/AP composite microspheres preparation via electrostatic spraying,and to reveal the effects of droplet properties and flow rate variations on the experimental results during the electrostatic spraying process,the prepared process parameters of Cu-en/AP composite microspheres by electrostatic spray method under the orthogonal experimental design simulated by ANSYS(Fluent).The influence of flow rate,solvent ratio,and solid mass on the experimental results is examined using a controlled variable method.The results indicate that under the conditions of a flow rate of 2.67×10^(-3)kg/s an acetone-to-deionized water ratio of 1.5∶1.0,and a solid mass of 200 mg,the theoretical particle size of the composite microspheres can reach e nanoscale.Droplet trajectories in the electric field remain stable without significant deviation.The simulation results show that particle diameter decreases with increasing flow rate,with the trend leveling off around a flow rate of 1×10^(-3)kg/s.As the solvent ratio increases(with higher acetone content),particle diameter initially decreases,reaching a minimum around a ratio of 1.5∶1.0 before gradually increasing.Increasing the solid mass also reduces the particle diameter,with a linear increase in diameter observed at around 220 mg.Cu-en/AP composite microspheres with nanoscale dimensions were confirmed under these conditions by the final SEM images.

Precision orchard sprayer based on automatically infrared target detecting and electrostatic spraying techniques

There is an urgent need for new chemical application techniques and sprayers in Chinese orchard spraying.A new tractor-mounted automatic target detecting electrostatics,and air-assisted orchard sprayer was designed and developed to meet the demand of chemical pest control in orchards.This sprayer light weighted,highly efficient,reduces pesticide use and is friendly to the environment.The techniques of automatic target detecting,electrostatics,and air-assisted spraying were combined in this system.The electrostatically charged droplets are projected toward the target by the assistance of an air stream that increases the droplets penetration within canopy.Experimental results show that the new automatic target detecting orchard sprayer with an infrared sensor can save more than 50%to 75%of pesticides,improve the utilization rate(over 55%),control efficiency,and significantly reduce environmental pollution caused by the pesticide application.At the same time the key technological problems related to air-assisted low volume and electrostatic spraying were solved.

Development of a charge transfer space loop to improve adsorption performance in aerial electrostatic spray

In order to solve the problem of insufficient adsorption rate of droplets on the target back via aerial electrostatic spray,this study proposed a high-voltage electrostatic generator to charge the liquids in two isolated water tanks with positive and negative charges respectively.A charge transfer loop was developed in space between the aerial electrostatic spray system and the ground.This method greatly enhanced the adsorption performance under outdoor conditions that 16.7%droplets density increased on the target front,a nearly fourfold destiny increased on the target back compared with the conventional UAV spray system.The target back-to-front ratio of droplet density was improved from 6.1%to 25.7%,which validated the satisfactory performance of the developed system.

Hydrogen Gas Sensors Based on Electrostatically Spray Deposited Nickel Oxide Thin Film Structures

A simple, low-cost, and home-built electrostatic spray deposition （ESD） system with the stable cone-jet mode was used to deposit nickel oxide （NiO） thin films on glass substrates kept at temperature of 400 ℃ as the primary precursor solution of 0.1 M concentration hydrated nickel chloride was dissolved in isopropyl alcohol. Electrical measurements showed that these films were of n-type conductivity while their resistance response to hydrogen flow in air ambient was varied by 2.81% with the rise and recovery time of 48 s and 40 s, respectively.

Open channel-based microchip electrophoresis interfaced with mass spectrometry via electrostatic spray ionization

The coupling between open channel-based microchip electrophoresis and mass spectrometry via electrostatic spray ionization is proposed for in situ detection of fractionated analytes. Electrophoretic separation is performed in an open channel fabricated in a plastic substrate. The solvent of background electrolyte is evaporated from the open channel because of Joule heating during electrophoresis, leaving the dried electrophoretic bands to be directly analyzed by mass spectrometry via scanning electrostatic spray ionization. Proof-of-concept results are obtained with fluorescent dyes and antibiotics as the test samples, demonstrating an efficient on-chip detection platform based on the electrophoresis and electrostatic spray ionization mass spectrometry.

Quantification of particle separation using electrostatically charged spray mist in a dust chamber

In order to improve the efficiency of reducing fine dust emissions from diffuse sources,the commonly used water mist can be electrostatically charged.Thus,the attraction between particles and droplets increases due to electrostatic field forces.In the experimental investigations carried out,an electrostatic two-fluid nozzle was used to generate a charged spray mist according to the principle of charging by induction.In a chamber,dispersed dust was precipitated with the spray mist,while detecting the laser light attenuation.By means of comparative measurements it could be shown that faster sedimentation and separation takes place through electrostatic attraction.Parameter variations regarding the use of compressed air and water were investigated and the sedimentation time of the particle-droplet mixture in the chamber was shown.A size distribution was then calculated from the laser light attenuation,which shows that the proportion of small particles decreases with spray application.Furthermore,the influence of the polarity of droplets and solid particles on the reduction measure was determined.

Deposition Effects of Electrostatic and NonElectrostatic Aerial Spray

In this study,we compared the aerial electrostatic spray with non-electrostatic spray by helicopter R44 and fixed-wing aircraft Y5B equipped with an own-made aerial electrostatic spraying system.The results showed that the spray deposits on targets and leaves of tree crowns were notable enhanced comparing with the non-electrostatic and conventional aerial spray.The spray deposits were fine,uniform and the densities were 1.0-1.75 times higher than the non-electrostatic spray.Deposit rate of the electrostatic spray on the backs of leaves by helicopter R44 was 2.15 times of the non-electrostatic, and 3.31 times of the conventional aerial spray.The deposit rate of the electrostatic spray on the backs of leaves by the Y5B was 2.38 times of the non-electrostatic,and 3.44 times of the conventional aerial spray.

Preparation of polypyrrole-coated CuFe_2O_4 and their improved electrochemical performance as lithium-ion anodes

CuFe2O4 network,prepared via the electrostatic spray deposition technique,with high reversible capacity and long cycle lifetime for lithium ion battery anode material has been reported.The reversible capacity can be further enhanced by coating high electronic conductive polypyrrole（PPy）.At the current density of 100mA·g-1.Li/CuFe2O4 electrode delivers a reversible capacity of 842.9 mAh·g-1 while the reversible capacity of Li/PPy-coated CuFe2O4 electrode increases up to 1106.7 mAh-g’.A high capacity of 640.7 mAhg＂1 for the Li/PPy-coated CuFe2O4electrode is maintained in contrast of 398.9 mAh·g-1 for CuFe2O4 electrode after 60 cycles,which demonstrates good electrochemical performance of the composite due to the increase of electronic conductivity.The electrochemical impedance spectroscopy（EIS） further reveals that the Li/PPy-coated CuFe2O4 electrode has a lower charge transfer resistance than the Li/CuFe2C〉4 electrode.

Development and experiments of low frequency ultrasonic electrostatic atomizing nozzle with double resonators

Fine droplets with high adhesion can greatly improve the efficiency of atomization culture.Therefore,the development of a spray nozzle that can produce fine fog droplets with high adhesion is of great significance for aeroponics.Compared to piezoelectric ultrasonic atomizer,Hartmann resonator low-frequency ultrasonic electrostatic atomizer has the advantages of large atomization volume and constant liquid chemical structure,but the droplet size is larger.High-speed gas can generate low-frequency ultrasonic vibration sound waves in Hartmann resonator.The frequency and intensity of sound waves determine the atomization performance of supersonic atomizer nozzle.However,very few research literatures can be found on how the structure and operating parameters of Hartmann resonator affect the atomization performance.In order to improve the atomization performance of ultrasonic atomizer,a two-stage Hartmann resonator low-frequency ultrasonic electrostatic atomizer was designed.The shrinkage-type Laval tube was designed by fluid mechanics theory,and the design results were verified by fluent software.The virtual orthogonal test method was used to optimize the structure parameters of two-stage resonator and spray test was carried out.The results showed that when the included angle between the two stage resonators was 80°,the diameter was 4.86 mm,the tube length ratio was 1.0 and the gas pressure was 0.5 MPa,the droplet size could reach 22.05μm.Additionally,compared with the traditional Hartmann cavity with 90°included angle,the droplet size was decreased by 63%.The annular electrode was used as the charging electrode,and Comsol Multiphysics software was used to simulate and calculate the deformation and crushing process of electrostatic droplets and the influence of different voltage,surface tension and droplet diameter on the droplet deformation rate.The results showed that:(1)the optimum charge range of the electrode ring was within 20 mm of the axial distance along the electrode ring.(2)The higher the voltage U,the smaller the surface tensionσ;the larger the droplet diameter d and the larger the droplet deformation rate.(3)The experimental results showed that the droplet size was inversely proportional to the gas pressure P0,electrostatic voltage U and spray height h.When the gas pressure and electrostatic voltage were 0.4 MPa and 18 kV,0.4 MPa and 18 kV,respectively,the droplet sizes were 7.8μm and 43.9μm respectively,the droplet size difference between the two conditions was 82.2%.