Journal of Electrostatics最新文献

Electric charges in liquids are at the basis of numerous applications and may drive industrial hazards. The Thermal Step Method is applied to liquid/solid interfaces to validate the use of thermal stimuli techniques for space charge measurements in dielectric liquids. Experimental results obtained for different electrical double layers are presented and discussed. They show that thermal convection has no significant contribution to the signal compared to the response of the charges from the solid/liquid interface. The measured signals are in accordance with the classical theory of thermal methods in solids and are consistent with the behavior expected from numerical simulations.

An air-assisted electrostatic spraying unit along with a set-up to measure the spray current was developed. Response surface methodology was used to optimize the performance of the developed electrostatic spraying unit. The optimum parameters such as electrode diameter, electrode voltage, electrode position and target distance for maximizing charge-to-mass ratio (CMR) were determined to be 30 mm, 2000 V, 0 mm and 400 mm, respectively Predicted CMR under optimal conditions was experimentally validated. Furthermore, charged spray demonstrated 1.5 to 4.6 times higher droplet deposition with lower uniformity coefficient (2.13–2.14) and relative span factor (0.84–0.9) compared to uncharged spray.

This study presents a new electrostatic separation device for recovering high-purity metals and plastics from waste electrical and electronic equipment. The device is constituted by a rotating plate conveyor, an air suction system, and a vibrating hopper. It utilizes electro-adhesion force to selectively attract metal particles onto the conveyor surface, while precisely calibrated suction air effectively collects plastic particles into a dedicated box. A key feature is the employment of a low-level AC high voltage, significantly enhancing operational efficiency and safety compared to conventional electrostatic methods. Experimental results demonstrate high performance, achieving recovery and purity rates of up to 100 % depending on applied voltage and airflow settings.

An established formula for capacitance C of a thin metal disc printed on a dielectric substrate with height h and relative permittivity ${\epsilon }_r\ge 2.2$, backed by a conducting ground plane, is inverted into a closed formula. The latter yields disc's radius r for a given C and a given substrate, with an accuracy of 5 % of C or better if $r\ge h/2$. It will save the design engineer time, whose alternative is to resort to a numerical field solver and go by trial and error.

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Carbon dioxide captured from the atmosphere can be reduced to carbon monoxide, which can then be used as a fuel or material for conversion to organic compounds and for gas synthesis. However, currently, this energy source has low efficiency and its use is impractical because of the relatively low atmospheric CO₂ concentration, which disperses input energy. Therefore, it is important to concentrate atmospheric CO₂ during pretreatment. In this study, a plasma reactor is partially filled with an adsorbent and atmospheric air is allowed to flow into the reactor after the removal of water vapor using a condenser and silica gel to adsorb atmospheric CO₂ (i.e., the adsorption process). During desorption and reduction, nonthermal plasma flow is generated via dielectric barrier discharge, while nitrogen is flowed into the reactor to reduce atmospheric CO₂ (i.e., the desorption–reduction process). As a result, the CO₂ concentration reaches 545 ppm in 230 min during the adsorption process and 5519 ppm in 12 min during the desorption–reduction process. The CO concentration increases to 60 ppm in 12 min during the desorption–reduction process. The conversion and energy efficiencies are 1.1 % and 1.9 × 10⁻² %, respectively. The introduction of the adsorption process not only increases the concentrates CO₂ but also decreases the concentration of water vapor in the reactor and generates more CO, thereby increasing the energy efficiency. Therefore, the introduction of an adsorption process is extremely important for improving the concentration and reduction of CO₂.

This paper presents the design of a novel atomized corona discharge coupled screen electrode dust collector, which integrates electrostatic capture and wet electrostatic dust removal technologies. The upper part of the dust collector features an atomized corona discharge electrode utilizing a threaded-wire hole design with uniform water distribution. This design effectively addresses the issue of electrode fatness that may arise from uneven distribution of the discharge electrode. In contrast, the lower part of the collector is equipped with four side-by-side silk screen electrodes, which serve to expand the dust collection area, facilitate secondary particle capture, and consequently enhance dust removal efficiency. The study delves into a detailed analysis of the impact of various parameters on discharge characteristics and dust removal efficiency, culminating in the identification of optimal parameters.

Gas ionizator is a device for electrostatic precipitation and is widely used to separate fine particulate matter (FPM) from small- and large-scale industrial exhaust gases. Two variations of electrodes design, rod and rectangle-toothed saw were used. The mass and number concentrations of six FPM fractions were detected. Stronger vortices occur at higher EAD/Re² ratios compared to the secondary electroaerodynamic (EAD) gas velocities. A deposition efficiency higher than 94.9 % was achieved at a gas velocity of 0.2 m/s. The FPM capture efficiency at voltage up to 20 kV is higher more than 7 % than at a voltage of 15 kV.

In the past few decades, atmospheric plasma propulsion has sustained a growth of interest. Recent studies have demonstrated the feasibility of light air-breathing plasma-propelled aircraft near ground level. Typically, corona discharge actuators are employed. Yet, the effects of the freestream velocity on the discharge current, ionic wind, and thrust must be characterized. The present study focuses on a wire-to-cylinder and a wire-to-airfoil actuators in a wind tunnel in a co-flow configuration. Discharge current and PIV (particle image velocimetry) measurements were used to determine both the differences between the two collecting electrodes and the aforementioned effects of the freestream velocity. The measured current follows the modeling already reported in the literature with a linear increase of the current with the freestream velocity. Besides, an interaction occurs with the charge density between the electrodes, which strengthens the rise of the current with the velocity as the voltage increases. In the study, the charge density increases linearly with the voltage with a slope of 0.75 mC/m²/kV for both collectors. However, the airfoil collector results in a higher current than the cylinder at the same voltage. The local velocity increases in three main regions thanks to the ionic wind. With both actuators, a higher velocity was captured with actuation on the upper and lower surfaces of the collectors. With the cylinder, the interelectrode region experiences a notable rise in velocity as well. In all cases, the air velocity downstream of the actuators is increased by the actuation. The ionic wind is usually less than 1 m/s (around 0.3–0.5 m/s on average) and its effect on the incoming flow decreases when the velocity increases up to 10 m/s. The force was calculated in control volumes around the actuators. For both actuators, the electroaerodynamic (EAD) force is governed by the current, and at constant current, the same EAD force is obtained with the two collectors. Yet, the force decreases with the drag of the collector, leading to a cancellation of the thrust when the drag exceeds the EAD force. At the maximum current tested in the study, the cylinder collector cancels the thrust at around 3 m/s of freestream against 5 m/s with the airfoil, showing that this type of propulsion is currently only applicable to low-speed aircraft.

Presented study investigated the impact of a stationary electric field with an average value of 185 kV/m on the germination process and early growth of radish (Raphanus sativus – a eudicot plant) and oat (Avena sativa – a monocot plant). Electric field stimulation may prove to be one method to sustainably increase crop efficiency. The research is aimed to increase knowledge of the effect of a static electric field on the plant growth process, because understanding of the topic is still limited. The plants were grown on a viscose substrate in a dark room without any light. Studies have shown that the electric field can affect the germination and growth process depending on the plant species. The findings indicate a positive influence of the electric field on radish germination. The presence of the electric field accelerates the germination process and growth of young plants. On the first day of germination (the 3rd day of cultivation), about 3.2 times as many plants germinated in the samples exposed to a stationary electric field compared to the control samples. On the last day of the experiment (the 8th day of cultivation), the tallest plants in the samples subjected to the electric field were 8 % higher, compared to the tallest plants in the control samples. On the other hand, the results demonstrate a negative impact of the electric field on oat seed germination. The presence of an electric field delays the germination process and reduces the number of germinated seeds. On the last day of the experiment (the 11th day of cultivation), about 1.25 times fewer oat plants germinated in the samples exposed to a stationary electric field compared to the control samples. The tallest plants in the samples subjected to the electric field were 1.1 times smaller than the tallest plants in the control samples.

The tendency of aerosols to carry viral particles featured significantly in public discourse during the SARS Covid-19 pandemic. In this research, the potential significance of the aerosol electric charge, especially as it relates to indoor relative humidity (RH) is considered. While electrostatic interactions may occur at any level of humidity, the level of humidity has a strong influence on these interactions. Above 55 % RH, there is sufficient moisture in the air to facilitate neutralization of the electric charges of particles and surfaces, whereas, at lower humidity levels, less moisture and higher surface resistivities enable increasingly stronger electrostatic interactions. Experiments were designed and conducted to study the behavior of electrically charged aerosols in fields emanating from capacitive touchscreens and permanent magnets. These preliminary experimental results suggest that operating indoor environments closer to the 55–60 % RH range could reduce interactions between these charged aerosols and capacitive touchscreens. This relative humidity range is within the acceptable ranges of humidity recommended by ASHRAE standard 55 which defines thermal environmental conditions for human occupancy.