Electrification Of Droplets Research Articles

Air-assisted spraying and electrically charged droplets for Bemisia tabaci control in soybeans.

The improvement of surface coverage and plant protection products deposition can be obtained by electrifying droplets, which are strongly attracted by plants, including the abaxial part of the leaves. Moreover, air assistance improves droplet penetration into the crop canopy, especially in the lower third of the plants. These technologies can help control soybean (Glycine max) whitefly, which preferentially lodges on the abaxial surface of the leaves. Thus, this study aimed to assess the effect of air-assisted spraying and electrically charged droplets to control whitefly in soybean, besides assessing surface coverage, plant protection product deposition, droplet size, and crop yield. Droplet electrification and air assistance did not change droplet size and uniformity classified as Fine. Surface coverage was not enhanced using air assistance and electrically charged droplets, where maximum coverage in the middle third of the plants was 4.55%. The results were not significant for spray plant protection products deposition. The number of nymphs per leaflet in the 2019/20 growing season was reduced with the used technologies, reducing from 10.9 to 3.0 nymphs per leaflet in the application with air-assisted and charged droplets, but not enough to differ from the untreated. On the other hand, the reduction was significant from the first assessment in the 2020/21 growing season. Air-assisted spraying plus electrically charged droplets, under the conditions of this experiment which corresponds to the application carried out in production areas, were not effective to affect whitefly control and soybean yield in comparison to the conventional application method. © 2022 Society of Chemical Industry.

SPRAY DEPOSITION ON MAIZE USING AN ELECTROSTATIC SPRAYER

ABSTRACT It is a well-known fact that the application of pesticides can be improved using an electrostatic spray due to the reduction of the application rate and increase in deposition on plant targets. However, little information exists on the use of such technology in maize crops. Thus, this study is aimed to evaluate the spray deposition on maize resulting from spray application using an electrostatic sprayer in combination with low application rates and different spray compositions. A field experiment was conducted in a randomized block having a 2×2×2 factorial design with two application rates (95 and 52 L ha-1), with or without the spray electrification, and with or without the synthetic adjuvant. The droplet electrification ability, interference of the electrical conductivity of the spray solution, losses of spray solution to the soil, and spray deposition on maize plants were evaluated for two cases of insecticide applications. The Faraday cage method was used to determine the spray electrification ability of the equipment. The spray deposition on plants and the losses to the soil were analyzed using a tracer (food coloring dye) added to the spray solution that was subsequently detected by spectrophotometry. It was seen that the electrostatic sprayer improved the spray application efficiency, which responded positively to the increase in the electrical conductivity of the spray solution. The deposition of the electrified spray solution on the upper third canopy of maize was found to be higher; the spray solution electrification also reduced the losses to the soil, regardless of the application rate.

ELECTROSTATIC SPRAYING EFFECT ON SPRAY DEPOSITION AND POWDERY MILDEW CONTROL IN SOYBEAN

ABSTRACT Electrostatic spray can bring benefits to the pesticide application such as the reduction of application rate and the increase of deposits on targets. Therefore, this study aimed to evaluate the effect of electrostatic spraying using lower application rates and different adjuvants on soybean spray deposition and chemical control of powdery mildew (Microsphaera diffusa Cooke & Peck). The field experiment was conducted in duplicate. A randomized complete block design with four replications in a 2 × 2 × 2 + 1 factorial scheme was used. The factors were two application rates, with and without droplet electrification, two spray solution compositions, and one additional treatment. Deposition on upper and lower leaves, spray loss to the soil, and powdery mildew control effectiveness were evaluated. The electrical conductivity of the spray solution and the charge/mass ratio induced in droplets were also evaluated. All treatments reduced the soybean powdery mildew severity. Electrostatic spraying responded positively to an increase in the electrical conductivity of the spray solution regarding the charge/mass ratio, but it did not increase spray deposition on the lower third of the canopy and did not influence spray loss to the soil, which was higher as the application rate increased.

Mono-dispersed droplets formation from capillary jet of liquid metal by applying an electric field

Purpose of our research is to develop a manufacturing process of mono-dispersed metal balls for spherical silicon solar cell. The spherical solar silicon cell is a solar cell that uses silicon spheres of 1 mm in diameter and has drawn great attention due to its high productivity. Silicon spheres are manufactured by a jet dropping method. In this method, silicon droplets are generated from breakup of a capillary jet of molten silicon. The droplets are solidified while failing in a cooling tower, and then spherical silicon balls are obtained. However, it is found to occur that the silicon balls are not mono-dispersed due to coalescence of the droplets during falling. In order to solve this problem, we proposed the droplet electrification method by applying high voltage electric field. A repulsive force will act between each charged droplets and prevent them from coalescence. In our experiments, capillary jets of water, glycerol and molten gallium were used instead of molten silicon to investigate the effect of the electrification. The experimental results are found that coalescence frequency is depending on a dimensionless parameter, which represents a ratio of electrostatic potential over kinetic energy of droplets.

АНАЛІЗ ЧАСОВОГО РОЗПОДІЛУ КІЛЬКОСТІ ВИПАДКІВ ГРОЗ НА АЕРОДРОМІ ОДЕСА

Thunderstorm is an atmospheric phenomenon that manifests itself in the form of electrical discharges in cumulonimbus clouds of lightning. Usually, lightning arise between the surfaces of the earth and the clouds. Sometimes electric flashes can go inside the cloud. At the same time on Earth there are about one and a half thousand thunderstorms, the average intensity of discharges is estimated at 46 zips per second. On the surface of the planet thunderstorms are distributed unevenly. Above the ocean thunderstorm is observed about ten times less than over continents. In the tropical and subtropical zone, about 78% of all bursts of lightning are concentrated. The maximum thunderstorm activity is in Central Africa. The intensity of thunderstorms follows the sun: the maximum of thunderstorms is observed in the summer (in medium latitudes) and in the afternoon. The minimum of registered thunderstorms falls on time before sunrise. Storm in Ukraine is constantly happening even in the winter months. They are especially dangerous in the steppe zone, the strikes of lightning strike all that, at least slightly rising above the grass or shrub. Lightning - an electrical discharge between the clouds or between the cloud and the earth. Inthe process of formation of rainfall in the cloud, the electrification of droplets or ice particles occurs. As a result of strong upward flow of air in the cloud, separate regions are formed, charged with different charges. When the intensity of the electric field in the cloud or between the lower charged region and the ground reaches a breakdown value, lightning arises. In such a weather, there are stormy clouds. As a rule, this event is accompanied by thunder, shower, hail and strong wind. The high density of settlements and agro-industrial facilities in the south of Ukraine, the intensity of air transportation at the international airport of Odessa and the construction of high-rise buildings require increased attention to prevent the devastating effects of natural hydrometeorological phenomena. One of the most dangerous HMAs for a society's life is a variety of convective phenomena, that is, showers, thunderstorms, hailstones, squalls, and tornadoes. They significantly affect the life, health and economic activity of man. For example, the defeat of people, aircraft with lightning, radio interference, interruptions in electrical supply - this is not a complete list of negative factors associated with thunderstorms. The purpose of the work was to study lightning activity at the Odessa airfield for 2013-2017 years. Daily observation of atmospheric phenomena was used as the source data for the study.

Post-dispersion electrification of droplets

Electrification of aerosol particles dispersed by a pneumatic atomizer is presented in the paper. For post dispersion electrification of droplets a contact method with external high voltage electrode was proposed. Experiments were carried out using supersonic atomizing head, equipped with a high voltage mesh electrode, placed co-axially and perpendicularly to the droplets stream and closely to the atomizing head. Results of experimental investigations have shown, that the Q/m ratio values depends on the liquid feed rate according to the power type function. Two steps electrification model with a space charge was proposed for explanation of the observed dependence. Calculations carried out on the basis of proposed model confirmed, that the space charge component of the electric field is significant for the final Q/m ratio value, and allow to determine Q/m value with accuracy on the level of 10%. The model suggests bipolar nature of charge carried by droplets leaving the electrification system.

Adjuvantes nas propriedades físicas da calda, espectro e eficiência de eletrificação das gotas utilizando a pulverização eletrostática

Os adjuvantes têm sido empregados na pulverização de agrotóxicos, entretanto, ainda se carece de informações sobre o efeito destes produtos, principalmente quando se emprega o sistema eletrostático. O presente trabalho foi conduzido com o objetivo de avaliar dez soluções de pulverização (nove adjuvantes e uma testemunha), quanto às propriedades físicas (viscosidade e condutividade elétrica) e quanto ao espectro e a eficiência de eletrificação da gota na pulverização eletrostática. Utilizou-se um pulverizador eletrostático da marca Electrostatic Spraying Systems e modelo MB 4.0. Para avaliar a viscosidade, a metodologia de Ostwald foi utilizada, enquanto a condutividade elétrica foi determinada com uso de um condutivímetro, marca Marte e modelo MB-11. Na análise da carga elétrica presente na gota, utilizou-se a metodologia da gaiola de Faraday e a avaliação do espectro foi realizada por meio de um analisador de partículas a laser (Spraytech Malvern(r)). Os adjuvantes testados alteraram a viscosidade da calda, variando entre 0,94 e 1,03mPa s. Para a condutividade elétrica, observou-se que a água apresentou 67,7µS cm-1 e, com o uso de adjuvantes, o valor obtido foi de até 607,5µS cm-1. Quanto à eletrificação das gotas, houve aumento de até 50,14% na relação Q/M com o uso de adjuvantes, demonstrando que auxiliam na pulverização eletrostática. De forma geral, os adjuvantes reduziram o diâmetro das gotas pulverizadas

Post-dispersion electrification of droplets in a system with pneumatic atomization

The process of electrifying aerosol particles dispersed by a pneumatic sprayer with supersonic air flow is presented. To avoid the electric-field shielding effect, confirmed by investigations of induction charging of aerosol droplets with application of a concentric induction electrode placed in the region of liquid dispersion, the droplet electrification process following the dispersion of liquid was proposed. The supersonic atomizing head was equipped with an external high voltage contact electrode placed concentrically and perpendicularly to the droplets stream and closely to the atomizing head. Experiments were conducted in air, at ambient conditions (T = 18±2 °C, RH = 55±3%), for standard air feeding rate (0.5 m3/min, 0.4 MPa) and regulated dispersed liquid rate (0.1 – 0.55 l/min). Results of the applied electrification process, characterized by a (Q/m) factor measured as a function of liquid feed rate, have shown that the (Q/m) values achieved for post-dispersion electrification are comparable to the values obtained for typical induction electrification with application of a concentric electrode.

Self-excitation of vibrations of a string under the electrification of droplets

Self-excitation of vibrations of a string under the electrification of droplets

イオン生成とエレクトロスプレー

Scientist observed natural phenomena and found the existence of ions more than 100 years ago. When the historical background of electrospray was surveyed from the view point of the ionization technique, the origin started by the awareness of the charged drops in nature. Our earth is positively charged and abounds in the positive ion. Iribarne noticed that ions were produced by bubbles at the surface of sea water forming the electric double layer and utilized these fact to create ions. Dole ionized polymers by the hydrostatic electrification of droplets from the hypodermic needle with the Faraday cage as a function of the repeller voltage and originated the electrospray ionization. Cluster ions were separated by the skimmer technique and the positive and the negative ion peaks were obtained. The multiply charged macroion from electrospray ionization was determined. Now electrospray ionization of liquids with quadrupole mass analysis to analyze proteins and nucleotides is one of the main streams of the structural characterization.

Effect of electrode configuration on efficiency of induction electrification of droplets

Numerical calculation of the electric field in an induction electrification unit is used to determine the charges of droplets formed for various axisymmetric electrode systems.

Electrification of Aerosols by Ionic Diffusion

The distribution of free electrical charges transferred to cloud droplets by ionic diffusion provides an illuminating example of a simple statistical process. Tables are constructed from first principles, shown to agree with successive terms of the binomial point equation of statistics, and applied to the initial stages of droplet electrification. The final equilibrium distribution, described by the basic electrification equation for aerosols, corresponds to an equipartition between the electrostatic energy of the droplets and their thermal kinetic energy.

The Electrification of Individual Cloud Droplets

The results of some observations of the electric charges carried by individual cloud elements are described. Measurable charges were found on many droplets, and a reversal of polarity was observed which appeared to be associated with the presence of ice particles. The different mechanisms of charging are discussed in the light of the experimental results, and reference is made to the possible significance of droplet electrification in the precipitation process. DOI: 10.1111/j.2153-3490.1956.tb01247.x

The Electrification of Individual Cloud Droplets

The results of some observations of the electric charges carried by individual cloud elements are described. Measurable charges were found on many droplets, and a reversal of polarity was observed which appeared to be associated with the presence of ice particles. The different mechanisms of charging are discussed in the light of the experimental results, and reference is made to the possible significance of droplet electrification in the precipitation process.

DROPLET-ELECTRIFICATION PROCESSES AND COAGULATION IN STABLE AND UNSTABLE CLOUDS

Abstract The fundamental electromechanics of droplet electrification and coagulation within stable and unstable clouds is investigated. The analysis shows that atmospheric ions formed by cosmic rays or other means normally diffuse onto cloud droplets and electrify them. A nearly Gaussian distribution is established in which about half of the droplets in any selected volume of a stable cloud acquire a positive charge that is typically eleven electronic units, while the other half is negative. More than 9.5 per cent of the droplets of a typical cloud are electrified. When droplet association is negligible, an equipartition is established between the thermal kinetic energy of the droplets and their electrical potential energy. In an unstable cloud, these electrified droplets mechanically associate by relative motion in the gravitational field. Thus, the growing droplets accumulate charge and a statistical distribution of highly charged droplets is established. Expressions are derived for the distribution and...

The statistical electrification of aerosols by ionic diffusion

A quantitative investigation of the diffusion of atmospheric ions onto spherical particles is reported. Special emphasis is given to random charging processes. The analysis shows that in typical cases about half of the particles are positively charged and the other half negatively charged. Nearly every particle carries at least one electronic charge and some twenty or more. Expressions are developed for the statistical distribution of the fractional number of droplets in relation to their charge. When particle collisions are infrequent, the average free charge of the positive and negative fractions depends only on the square root of the radius and the mean thermal energy of each droplet. It is shown that an equipartition is established between the electrical potential energy of each drop and its thermal kinetic energy. Typical particle electrification somewhat increases the coagulation rate normally attributable to diffusion alone. Systematic droplet electrification of a selected sign is superimposed on this random charging if the positive and negative light ion conductivities of the environment have appreciably different values. The calculated distribution and average charge magnitude agree with those observed on silica dust and new measurements on cloud particles.