Ozone Generation Characteristics Research Articles

Characteristics of high-repetition-rate bipolar pulse DBD under various electrical conditions in atmospheric-pressure air

Numerous studies have been conducted on pulse dielectric barrier discharge (DBD) because it can produce powerful discharges uniformly at atmospheric pressure with a fast rise time. Although much research has been conducted on pulse DBD below 10 kHz, relatively little has been conducted on pulse DBD at high pulse repetition rates (PRRs). Therefore, in this study, the ozone generation and discharge characteristics of bipolar pulse DBD in atmospheric-pressure air at a high PRR of 10 kHz or above were investigated. According to the results of this study, with the exception of electron temperature, most discharge characteristics need for practical applications—like transfer charge, electron density, and discharge uniformity—improved as the voltage and duty ratio increased at high PRR. On the contrary, increasing the PRR exhibited trade-off features like low electron temperature, low discharge uniformity, and a high number of discharges per unit time. Ozone generation demonstrated good results at high voltage, appropriate PRR, and low duty ratio, but applying suitable electrical conditions is crucial considering ozone generation speed and power consumption. The findings of this study will be very beneficial for high-PRR pulse DBD applications that require quick and effective processing. Additionally, they will be useful for researching the characteristics of pulse DBD at high PRR.

Effect of megapore particles packing on dielectric barrier discharge, O3 generation and benzene degradation

Recently, packed-bed discharge plasma technologies have been widely studied for treatment of volatile organic compounds (VOCs), due to the good performance in improving the degradation and mineralization of VOCs. In this paper, a coaxial cylindrical dielectric barrier discharge reactor packed with porous material of micron-sized pores was used for degradation of benzene, and the discharge characteristics and ozone generation characteristics were studied. When the discharge length was 12 cm and the filling length was 5 cm, the packed particles in the discharge area significantly increased the number of micro-discharges, and the current amplitude and density increased with the pore size of packed particles, but the discharge power and ozone concentration showed a trend of first increasing and then decreasing. The discharge power and ozone production reached the maximum when the size of pore former was 75 μm, correspondingly, the degradation efficiency of benzene was the highest.

“STRING” TYPE OF BARRIERLESS PLASMA CHEMICAL REACTOR FOR GENERATION OZONE FROM AIR

The efficiency of ozone generation for barrierless plasma chemical reactors with different cathode designs was compared. The characteristics of ozone generation for a plasma chemical reactor with a string-type cathode in comparison with the previously developed star-shaped cathode for different combinations of bias and pulsed components of voltage have been investigated. The special feature of the operation of a plasma-chemical reactor with a string cathode is revealed. There is consisting in the absence of dependence of the transition of the discharge combustion mode into the spark breakdown phase from the presence of a bias voltage.

Engineering Model of Ozone Generation Considering Microdischarges

In a dielectric barrier discharge, countless pulsed microdischarges with a diameter of about $100~\mu \text{m}$ appear and disappear. Since such microdischarges will affect ozone generation, it is important to understand their characteristics. In the case of a short discharge gap, which has been adopted recently, the transferred charge of a microdischarge is treated as a sphere on the dielectric to simplify the modeling. In this article, we discuss how various parameters affect ozone generation by comparing simulation and experimental results. We also discuss the influence of the thickness and dielectric constant of the dielectric barrier on the characteristics of ozone generation.

The Effect of Needle Tips Interval Distance in Ozone Generation Using Triple Needle‐Plane Electrodes

Ozone has much attention in many industrial fields. To materialize higher ozone generation efficiency, it is necessary to elucidate the relationship between discharge characteristics for discharge electrode system and ozone generation concentration. To clarify the improvement of mechanism on the multiple needle‐to‐plane configurations, the discharge characteristics and ozone generation characteristics for a multiple needle electrode system with various needle tip distances have been investigated. In this experiment, the maximum ozone yield at needle tip interval of d = 0.5 mm was improved by the minimum discharge power, the local maximal at d = 0.5 mm of discharge volume and the same ozone generation compared with those for d = 0 mm and d = 1 mm. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Influence of Duty Cycle on Ozone Generation and Discharge Using Volume Dielectric Barrier Discharge

The influence of duty cycle on ozone generation and discharge characteristics was investigated experimentally using volume dielectric barrier discharge in both synthetic air and pure oxygen at atmospheric pressure. The discharge was driven by an amplitude-modulated AC high voltage–power supply producing TON (a single AC cycle) and TOFF periods with a widely variable duty cycle. The experimental results show that the energy delivered to the discharge during each AC cycle remains roughly constant and is independent of feed gas, duty cycle and TOFF. Both average discharge power and ozone concentration show an initial linear increase with duty cycle, and deviate gradually from linearity owing to an increase in gas temperature at higher duty cycles. Nevertheless, ozone yield remains nearly constant (45.7 ± 3.5 g/kWh in synthetic air and 94.7 ± 3.1 g/kWh in pure oxygen) over a wide range of applied duty cycles (0.02–1). This property can be conveniently employed to develop a unique ozone generator with a widely adjustable ozone concentration and simultaneously a constant ozone yield. Additionally, the discharges in synthetic air and pure oxygen have similar electrical characteristics; however, there are observable differences in apparent luminosity, which is weak and white-toned for synthetic air discharge, and bright and blue-toned for pure oxygen discharge.

Effect of nitrogen addition to ozone generation characteristics by diffuse and filamentary dielectric barrier discharges at atmospheric pressure

Ozone is widely used for gas treatment, advanced oxidation processes, microorganisms inactivation, etc. In this research, we investigated the effect of nitrogen addition to ozone generation characteristics by atmospheric pressure Townsend discharge (APTD) type and filamentary dielectric barrier discharge (DBD) type ozone generators. The result showed that the ozone generated by the filamentary DBD increases rapidly with the increase of O2 content, and is higher than that by the APTD. On the other hand, it is interesting that the ozone generated by the APTD gradually decreases with the increase of O2 content. In order to clarify why the characteristics of ozone generation by the two kinds of discharge modes showed different dependency to the N2 content, we analyzed the exhaust gas composition using FTIR spectroscopy and calculated the rate coefficients using BOLSIG+ code. As a result, we found that although O2 content decreased with increasing N2 content, additional O atoms produced by excited N2 molecules contribute to ozone generation in case of APTD.

Development of a High Performance Ozonizer System in Environment Improvement for Green Growth

In order to develope high performance ozonizer system, silent discharge of a new type ozonizer(SDTO) has been designed and manufactured. SDTO is equipped with three electrodes(central, internal and external electrodes), and it is composed of double gaps(gap between central electrode and internal electrode, gap between internal electrode and external electrode). Ozone is generated by overlapping silent discharge, which is respectively came from double gaps. This paper describes the following two characteristics : ① The characteristics of discharge with variation of output voltage of AC H.V source and quality of supplied gas ② The characteristics of ozone generation with variation of quality of supplied gas, discharge power and operating number. As a result, the maximum ozone concentration, generation, and yield can be obtained 20,187ppm, 13.7g/h and 350.8g/kwh respectively.

Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air**supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3− and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode.

Al2O3유전체를 이용한 산소/공기 원료에 따른 오존발생기의 특성

The ozone generation is commonly made with silent discharge method using quartz glass dielectric. In this paper, using dielectric to instead of the traditional quartz glass dielectric to improve the system efficiency is presented. The dielectric was manufactured as tube shape (Internal diameter Outside diameter: ) using 99% ceramic. The characteristics of dielectric discharge and ozone generation were studied of experiments with variation of discharge power, discharge electrode space and rate of flow for supplied gas (/Air). As the experimental results, in the same discharge space, the ozone concentration continuously increased with input power increasing, and ozone yield increased until saturation happened. Also, the expended power increased with discharge space extended due to discharge power increased. In additional, the ozone concentration of oxygen ozone was higher than air that was observed when using oxygen ozone in proposed experiments.

Ozone Zero Phenomenon in Ozone Generator Equiped with Coaxial Cylinder Electrodes Covered by Dielectrics

Ozone generators of dielectric barrier discharge (DBD) are mainly used for water and waste water treatment. Recently, they are also used for cleaning of food product machines, semiconductors processes, pulp bleaching field and so on. It is well-known that ozone concentration composed by DBD type ozone generator decreases with time when high purity oxygen used for feed gas. This is named by us, ozone zero phenomenon (OZP). The causes of the phenomena have been investigated experimentally in the world wide industries us. One of the causes is considered as an electrode material by discharge in the generator metal oxides formed from stainless steel electrode. We have studied the ozone generation characteristics using high purity oxygen as a feed gas and ozone generator of which both electrodes covered with dielectrics. It was found that using only high purity oxygen as a feed gas, ozone concentration decreased from 200g/m3(N) to 54g/m3(N) during about 5 hours. However, adding 0.1vol% of nitrogen into oxygen, ozone concentration increased rapidly over the initial maximum ozone concentration of 216g/m3(N). After that, the concentration of ozone gradually decreased with time. Therefore, adding nitrogen into oxygen has the effect of recovery of ozone concentration in the same generator. The maximum ozone concentration was obtained when 0.1-0.6vol% of nitrogen gas was added to oxygen gas. OZP is caused by ozone generator even when both electrodes are covered with dielectrics. The metal oxide is produced on electrode is not the cause of OZP. Ozone concentration can be increased by adding nitrogen into oxygen.

Characteristics of Partial Discharge and Ozone Generation for Twisted-pair of Enameled Wires under High-repetitive Impulse Voltage Application

In recent years, inverter drive machines such as a hybrid vehicle and an electric vehicle are operated under high voltage pulse with high repetition rate. In this case, inverter surge is generated and affected the machine operation. Especially, the enameled wire of a motor is deteriorated due to the partial discharge (PD) and finally breakdown of the wire will occur. In order to investigate a PD on a resistant enameled wire, characteristics of PD in the twisted pair sample under bipolar repetitive impulse voltages are investigated experimentally. The relationship between the applied voltage and discharge current was measured at PD inception and extinction, and we estimated the repetitive PD inception and extinction voltages experimentally. The corresponding optical emission of the discharge was also observed by using an ICCD camera. Furthermore, ozone concentration due to the discharge was measured during the life-time test of the resistant enameled wires from a working environmental point of view.

Fundamental Study of Barrier Discharge and Ozone Generation Characteristics for Multiple Needles to Plane Configuration

A multiple needles electrode system is one of the good configurations because of easy generation of corona and dielectric barrier discharge suitable to ozone production. On this configuration, discharge and ozone generation characteristics are affected by needle configuration such as needle density, adjacent needles, but their influence has not been clarified in detail until now. In this study, the relationship between barrier discharge characteristics and ozone generation under AC voltage application has been investigated for triple needles-plane configuration with two different needle-tip curvatures (r = 15, 80 m) in dry air, which is a simpler multiple needles configuration. Characteristics of barrier discharge and ozone generation depend on the needle-tip distance and need-tip radius. In the case of the multiple needles configuration with a smaller needle-tip's distance, the barrier discharge characteristics have been strongly affected by the adjacent needles each other. Especially, the ozone production characteristics depend on the needles configurations. The configuration with a smaller needles distance has good ozone productivity compared with other configurations. In addition, ozone concentration and ozone generation efficiency for the triple needles with r = 80 m were higher than those for the needles with r = 15 m. These results can be interpreted by the effect of the space charges and accumulated charges induced by corona discharge and barrier discharge on the space for ozone generation.

Effect of Pulse Width on Oxygen-fed Ozonizer

Though general ozonizers based on silent discharge (barrier discharge) have been used to supply ozone at many industrial situations, there is still some problem, such as improvements of ozone yield.In this work, ozone was generated by pulsed discharge in order to improve the characteristics of ozone generation. It is known that a pulse width gives strong effect to the improvement of energy efficiency in exhaust gas processing. In this paper, the effect of pulse duration on ozone generation by pulsed discharge in oxygen would be reported.

Development of dielectric barrier discharge-type ozone generator constructed with piezoelectric transformers: effect of dielectric electrode materials on ozone generation

The dependence of ozone generation on the types of dielectric electrode material has been investigated using an ozone generator constructed with the piezoelectric transformer developed in our laboratory. The ozone generator is based on the excitation of the dielectric barrier discharge (DBD), which has the advantage of a compact configuration for generating ozone. Four kinds of dielectric materials are prepared for dielectric barrier electrodes. Electrical properties of the DBD and the ozone generation characteristics are investigated for the different dielectric materials. Differences in the discharge mode among the barrier electrode materials are recognized and discussed on the basis of the results of the Lissajous figures and voltage–current waveforms. During the continuous running of the generator, a temporal decrease in ozone concentration is observed owing to the temperature increase inside the reactor. Although the ozone generation characteristics are influenced by many properties of dielectrics, two important factors for achieving high-efficiency ozone generation are identified in this study. One is the use of a high-thermal conductivity material for the dielectric electrode, which functions well as a heat sink for transferring the generated heat to the outside through the material. The other factor is the control of the discharge mode. Our results show that the discharge mode that is considered as Townsend-like DBD is suitable for high-efficiency ozone generation.

Application of Microplasma for $\hbox{NO}_{\rm x}$ Removal

In this paper, microplasma is investigated, which occurs between the narrow gap of the electrodes covered with dielectric materials. The discharge gap is set on the order of micrometers by changing a spacer from 0 to 100 mum. In this paper, the characteristics of microplasma, such as discharge voltages, discharge currents, and discharge power that is obtained with the help of Lissajous figures, and the relationships between these electric characteristics are presented. The characteristics of ozone generation by a microplasma electrode are investigated. Treatment by microplasma for the simulated exhaust gas, which contains NOx and C3H8 as a role of HC and CO, is estimated experimentally. In the absence of O2, the exhaust gas is decomposed by nitrogen atomic species in particular. In the presence of O2, it is decomposed by nitrogen atomic species and oxidized by ozone. By-product analysis of treated gases is carried out by Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. When HC, NOx, and N2 are included in the simulated exhaust gas, HCN, N2O, and CH4 are confirmed as by-products of the microplasma treatment.

새로운 형태의 평판형 오존발생기 특성과 응용

본 연구는 실내공기와 상수의 수질개선을 위하여 소형 평판형 오존발생기(plate-type ozonizer: PTO)를 개발하여 그 특성을 규명한 논문이다.BR 평판전극의 크기, 개수 및 배치에 따라 다양한 형태의 오존발생기가 고안되었다. 각 형태의 오존발생기의 방전 면적은 60[cm²]로 동일하며 방전전력은 최대 30[W]이다.BR 주요 연구 대상은 방전전력 오존생성농도 특성, 방전전력-오존생성수율 특성, 유량-오존생성능도 특성 및 유량-오존생성수율 특성이다. 오존생성특성은 PTOL-P가 가장 우수하게 나타났으며, 나머지 3종류의 오존발생기 (PTOSUBP-P/SUB, PTOSUBC-P/SUB, PTOSUBT-P/SUB)에서는 유사한 결과를 얻을 수 있었다.

Effective Ozone Generation With a Wire–Wire-Type Nonthermal Plasma Reactor With a Slit Barrier

The corona discharge and ozone generation characteristics of a wire-wire-type nonthermal plasma reactor (PR), with a slit dielectric barrier, have been experimentally investigated. When a slit mica barrier is installed between corona wires, a significant increase in the generation of ozone could be obtained. From the photographs of the corona discharges, this type of nonthermal PR with a slit barrier (SB) produces two corona discharges, one from the corona wires and another from the slits of the SB. This second corona discharge is caused by the rapid relaxing of the charges, which are migrated from the corona wire and stored on the surface of the barrier, through the slits. As a result, the proposed nonthermal PR has the potential to significantly increase ozone production, and it may be useful as an effective means for removing pollutant gases.

Corona discharge and ozone generation characteristics of a wire-plate discharge system with a glass-fiber layer

Corona discharge and ozone generation characteristics of a wire–-plate-type discharge system with a porous glass-fiber layer on the meshed-plate electrode have been investigated experimentally. The experimental results were compared with a conventional wire-plate discharge system. When a double glass-fiber layer is installed on the meshed-plate electrode of a wire-plate-type discharge system, the discharge system can generate a corona discharge twice, once from the corona wire, and again from the glass-fiber layer. As a result, the ozone output is significantly increased by a factor of 2.4–2.6, and increased ozone yields of about 3.1 and 1.5 times were obtained compared with those without the glass-fiber layer for positive and negative discharges, respectively. As a result, removal efficiency could be enhanced. By adopting a meshed plate instead of a solid plate, the pollutant gases to be treated were able to pass through the corona-discharging porous glass-fiber layer and the meshed plate with less pressure drop. This result meant that the removal capability could be increased. Consequently, the proposed wire-plate discharge system, with its porous glass-fiber layer and meshed-plate electrode, has the potential to be used as an effective discharge system for removing the pollutant gases and/or dust particles.

전극 형태에 따른 평판형 오존발생기의 특성

최근 오존은 그 활용성을 인정받아 다양한 분야에서 사용되고 있으며, 그 수요 또한 계속 증가하는 추세이다. 이에 다양한 종류의 오존발생기가 연구되고 있으며, 고농도 및 고수율을 얻는 것이 연구목표라 할 수 있다. 본 논문에서는 전극 형태에 따른 평판형 오존발생기를 제작하여 원료가스의 유량 및 방전전력의 변화에 의한 오존생성농도, 오존생성량 및 오존생성수율 특성을 연구하였다.