Characteristics of ozone generation by a diffuse glow discharge at atmospheric pressure using a double discharge method

In this research, a diffuse glow discharge generated by a double discharge is used to improve the efficiency of ozone generation. In this method, corona discharge occurs in the space between the cathode and the trigger electrode covered by Pyrex glass tubes, set in a groove cut on the cathode. Thus, many initial electrons are generated around the cathode. In the present research, experiments were done in air (O₂/N₂ mixture) at atmospheric pressure and the discharge repetition frequency was 1 Hz for all experiments. The maximum ozone concentration generated was about 150 ppm. The average ozone yield was about 400 g O₃/kWh, much higher than the typical yield of about 100 g O₃/kWh. The efficiency of energy transfer from energy stored in storage capacitor C₁ to the main discharge zone was about 40% to 50%. © 1999 Scripta Technica, Electr Eng Jpn, 127(2): 8–14, 1999     

Hydrogen peroxide and ozone formation in hybrid gas-liquid electrical discharge Reactors

Ozone in the gas phase and hydrogen peroxide in the liquid phase were simultaneously formed in hybrid electrical discharge reactors, known as the hybrid-series and hybrid-parallel reactors, which utilize both gas phase nonthermal plasma formed above the water surface and direct liquid phase corona-like discharge in the water. In the series configuration the high voltage needle-point electrode is submerged and the ground electrode is placed in the gas phase above the water surface. The parallel configuration employs a high voltage electrode in the gas phase and a high voltage needle-point electrode in the liquid phase with the ground electrode placed at the gas-liquid interface. In both hybrid reactors the gas phase concentration of ozone reached a power-dependent steady state, whereas the hybrid-parallel reactor produced a substantially larger amount of ozone than the hybrid series. Hydrogen peroxide was produced in both hybrid reactors at a similar rate to that of a single-phase liquid electrical discharge reactor. The resulting concentration of H/sub 2/O/sub 2/ in the hybrid reactors, however, depended on the pH of the solution and the gas phase ozone concentration since H/sub 2/O/sub 2/ was decomposed by dissolved ozone at high pH.     

Production of ozone by surface and glow discharge at cryogenictemperatures

The generation of ozone at cryogenic temperatures is investigated with a special interest in increasing the yield of ozone by using low temperatures of liquid natural gas. Two modes of plasma chemical processes are studied, both based on electric discharges: one is the high-frequency surface discharge mode under ordinary gas pressure and at a temperature above the liquid temperature of ozone at this pressure (-111°C); the other is the glow discharge mode under a low gas pressure (0.5-2.0 torr) and low gas temperature (-190°C). The surface discharge mode uses a novel ozonizer developed by the authors made of 92% high-purity alumina and tungsten electrodes sintered together. This ozonizer has an extremely high resistance to large temperature gradients and thermal shock, which is a prerequisite for cryogenic operation. The glow discharge mode uses a Pyrex glow tube with a separate liquid-ozone collector. A dramatic improvement in the energy yield of ozone generation is achieved in both modes of cryogenic operation. The results of preliminary test for cryogenic ozone generation are very encouraging     

臭氧发生器放电管故障诊断的研究

文中提出利用电磁感应原理,设计电磁线圈感应出电压,驱动LED发光管发光,观察发光管的亮暗即可判断放电管故障与否并且显示出哪根管故障,为检修提供指示功能。从理论与实验验证可行性,并以此设计出可靠的臭氧发生器放电管故障诊断系统。     

Investigations on the VUV emissions of Ne-Xe-Cs gas mixturesexcited by an electrical discharge

UV emissions of Ne-Xe-Cs mixtures excited by a pulsed electrical discharge were investigated experimentally as a function of gas pressure and gas composition. For the studied discharge plasmas no fluorescence emissions originating to the radiative decay of the ionic excimer molecule (XeCs)⁺ at 160 nm were observed. Discharge excitation seems to be unsuitable for the generation of this ionic excimer. Previously reported fluorescence emissions due to the radiative transitions in the discharge-excited (XeCs)⁺ molecule could not be confirmed in our experimental conditions. An upper Limit for the unknown rate constant of the formation reaction Xe*+Cs⁺+Ne→Xe⁺Cs+Ne was given     

Pulsed streamer discharge characteristics of ozone production indry air

Experimental investigation of HV short pulsed streamer discharges in dry air-fed ozonizers under various operating conditions are reported. Ozone concentration, energy input and ozone production yield (efficiency) were measured at various voltages (14 to 37 kV), pulse repetition rates (25 to 400 pulses per second, pps), flow rates (1.5 to 3.0 1/min) and different gap spacings (10 to 20 mm) at a pressure of 1.01×10⁵ Pa in dry air. A spiral copper wire (1 mm in diameter) made to a cylindrical configuration (18 to 38 mm in diameter) in a concentric coaxial electrode system of various dimensions was employed. A magnetic pulse compressor provided the HV and current pulses. Higher voltage and higher repetition rates yielded higher concentrations of ozone at a fixed air flow rate. The present investigation was extended to assess the performance of this pulsed ozone generator using dry air under desired conditions of high concentration and high yield of ozone for industrial applications     

First electron availability and partial discharge generation in insulation cavities: effect of light irradiation

An experimental investigation of the behavior of partial discharges occurring in insulation cavities as a function of light irradiation conditions is presented in this paper. Partial discharge inception voltage (PDIV) measurements were performed for different irradiation conditions of the test objects (visible light, of variable intensity, ultra violet (UV) light or absence of irradiation), defect geometry and conductivity of insulating material. It is shown that changes of such factors involve considerable alteration of partial discharge inception features, in terms of both inception voltage and delay time. Depending on applied field, defect geometry, insulating material characteristics and irradiation condition, in fact, partial discharge inception voltage may be influenced prevailingly by background radiation, as generally stated in literature, or by field-assisted electron detrapping from material-cavity interface.     

Production of high average power UV by second-harmonic andsum-frequency generation from copper-vapor lasers

Progress in high average power UV generation by nonlinear frequency conversion of the output of copper-vapor lasers (CVL's) is reviewed. The specific parameters controlling the efficiency of nonlinear frequency conversion using CVL's are highlighted, with CVL beam quality and matching the optical beam delivery system to the characteristics of the nonlinear crystal being identified as the most significant issues. Recent experimental studies of second harmonic generation (SHG) with single-CVL oscillators and CVL oscillator-amplifier systems show that by careful optimization of the CVL pump laser and beam delivery systems, it is now possible to generate multiwatt average powers in the UV with high optical conversion efficiency (up to 35%) and overall electrical efficiency (approaching 0.1%)     

The influence of antioxidants on electrical tree generation in XLPE

In conjunction with previous experiments studying the effect of decomposition products of dicumyl peroxide (DCP) and antioxidants (AOs) in cross‐linked polyethylene (XLPE) insulation on electrical tree generation, the authors conducted experiments investigating tree inhibition by phenolic AOs. The experiments were conducted using XLPE slabs containing four different phenolic AOs. Among the specimens containing these AOs, the specimen containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) was found to show the highest tree inception voltage. To examine the reasons for the significant increase in tree inception voltage in this specimen, further experiments were carried out on XLPE specimens containing both phenolic AO and a sulfur‐containing AO. The results demonstrated that the tree inception voltages of specimens containing both phenolic AO and sulfur‐containing AO were higher than those of the specimens containing only one of these two types of AOs. The roles of antioxidants in XLPE dielectrics are discussed with reference to the mechanisms of autoxidation of polymeric materials. The great increase in the tree inception voltage of XLPE specimens containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) appears to be due to a synergistic effect between the phenolic AO and the sulfur‐containing AO. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 1–7, 2001     

TCE decomposition by the nonthermal plasma process concerning ozone effect

Dilute trichloroethylene (TCE) and other volatile organic compounds (VOC) in air were decomposed by using the nonthermal plasma process combined with catalysts. To enhance the energy efficiency of the TCE decomposition, some catalysts were tested including their location. It was found that the newly proposed indirect process (VOC cannot be exposed in the plasma region) can also decompose TCE and other VOCs which is due to the ozone dissociation effect. The manganese oxide dissociates ozone to generate oxygen radicals which decompose TCE and other VOCs.     

空气源高频圆管型DBD臭氧产生的实验研究

电源频率和放电管长度是介质阻挡放电(DBD)臭氧产生的两个重要影响因素,在前期的研究基础上,采用合适的放电管长度和电源频率进行实验研究。实验研究了干空气源放电管长度、放电电压和气体流量对臭氧产生的影响,并进行了系统优化。研究结果表明:放电管长度由500 mm变为200 mm,在几乎不降低臭氧浓度下放电平均功率约降低了60%;臭氧浓度随放电电压和气体流量的增大先增大后降低;当流量为200 L/h、放电电压为2 698 V时,臭氧浓度与臭氧产率同时达到相对较高值,此时,臭氧浓度为5.3 g/m3时,臭氧产率为43.62 g/kWh。     

Discharge and ozone generation characteristics of aferroelectric-ball/mica-sheet barrier

The discharge and ozone generation characteristics of a ferroelectric-ball (FEB) and mica-sheet double barrier were investigated to study the fundamentals of barrier discharges and to establish better conditions for the efficient control of pollutant gases. Five kinds of FEB's, the dielectric constants of which are 33, 150, 660, 1500, and 10000, were investigated in atmosphere with various pulse frequencies ranging between 0.2-4.0 kHz. It was found that the double barrier has better discharge characteristics for ozone generation than an FEB single barrier. In addition, ozone generation is greatly influenced by both the dielectric constant of the FEB barrier and the applied pulse frequency. As a result, there were optimum conditions for the dielectric constant and the applied pulse frequency to generate ozone effectively which, for the given experimental conditions, were about r=660 and the frequencies higher than 4 kHz     

Modelling of partial discharge development in electrical tree channels

A model of partial discharge development in electrical tree structures is presented. The model considers channel conductivity, charge transport, and electric field redistribution during propagation of the discharge along the channels. It has been used for numerical investigation of temporal-spatial and electric characteristics of the partial discharges in capillaries and electrical trees exposed to AC voltage in a needle-plane geometry. The simulation results have been compared with experimental data given in the literature.     

Monte Carlo simulation of electrical corona discharge in air

Electrical discharges play a key role in technologies; there are many industrial applications where the corona discharge is used. Air as insulator is probably the best compromise solution for many applications. All of this reflects on the great importance of the evaluation of the corona performance characteristics. Numerical simulation of the corona discharge helps to better understand the involved phenomena and optimize the corona devices. This paper is aimed at calculating the corona discharge in negative point-plane air gaps. To describe the non-equilibrium behavior of the electronic avalanches and to simulate the development of corona discharge the method of Monte Carlo has been used. This model provides the spatial-temporal local field and particles charged densities variations as well as the ionization front velocity.     

变频电源进行感应电机叠频试验的分析

通过电机叠频试验的研究,总结了变频电源进行叠频试验的的原理及结构,分析了采用变频电源进行电机叠频试验时电机损耗及温升过高的原因,并提出了解决问题的方法。     

Initiation of a discharge channel in water by means of electrical explosion of aluminum foil

This paper reports the results of an experimental investigation into initiation of the electric discharge in service water by means of explosion of aluminum foil having various mass and dimensions. The electric discharge was formed in a chamber with a movable wall (the piston). As an electric energy storage, the capacitor bank having the capacity C = 200–600 μF with charging voltage U ₀ = 2–5 kV (stored energy Q ₀ = 0.4–7.5 kJ) and the rate of rise of the discharging current dI/dt = (3–4) × 10⁹ A/s. The results of experiments showed that destruction (loss of conductivity) of foil occurs at the value of the integral of the current density h _j = (0.3–0.65) × 10⁹ (A²/cm⁴)/s. The stage of the repeated breakdown in the electric discharge occurs when the value of the intensity of the electric field along the discharge channel is of E _rb ≥ 50 V/mm. Geometric dimensions and mass of the initiating conductor that provide the maximum efficiency of conversion of the value of Q ₀ into kinetic energy of the piston have been determined.     

基于太阳能发电的光伏阵列电气系统设计

清洁能源的使用是未来社会发展的趋势。以光伏发电为研究模型,对实现太阳能的高效利用展开研究,提出了一种高效的光伏阵列,使太阳能发电系统的能源利用率得到了显著的提升。通过对太阳能发电的电气系统进行一次设计,提出了35 kV侧无功补偿装置,使得系统更加合理、有效。     

基于局部放电量的环氧树脂脉冲电应力老化特性研究

针对GIS内出现的冲击型电应力老化现象,设计一套特斯拉脉冲电源发生器,通过控制调节脉冲电压的输出幅值及频率,研究纳米Al2O3填料与环氧树脂共混填充在不同电压幅值、频率试验条件下的绝缘特性和局部放电量的变化规律.结果 表明,较高的脉冲幅值与脉冲频率会加快空间电荷的入射与脱陷过程,加剧复合材料内部局部放电过程,促进导电通道分支的发展,进而使复合材料的老化程度更加严重.该研究结果有利于提升电气设备缺陷发现能力,减小故障几率,缩短停电检修时间,为设备异常故障分析提供参考依据.     

电力市场和节能发电调度的关系

从分析"节能发电调度"对现有电力市场交易的影响入手,阐述了两者协调运作的现实意义,并结合江苏省电力市场交易现状和节能发电调度试运行情况,设计了机组物理调度和市场金融结算并行运作的模式,建立了经济补偿的电力交易机制,阐述了节能发电调度下电力交易机制的运作全流程,分析探讨了电力市场实现电力行业节能减排的必要条件.