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For pulsed corona plasma applications, it becomes important to develop pilot systems with large average power and high-energy conversion efficiency. Since the beginning of 2000, we have been working on an industrial corona plasma system with tasks of 10-30 kW in average power and higher than 90% of total energy conversion efficiency. The pulsed-power source should have the following specifications: rise time of 10-25 as, pulsewidth of 50-150 as, pulse repetition rate of up to 1000 pulses per second, peak voltage pulse of 70 kV, peak current of 3.5 kA, dc bias voltage of 10-35 kV, and energy per pulse of up to 30 J. Sixteen parallel wire cylinder reactors are used to match the source. Gas and reactor temperatures can be controlled individually with water flow around the outside of those cylinders. The system is designed for gaseous oxidation and electrostatic dust precipitation. The system has been used for up to 17 kW in average power. This paper reports the system in detail, discusses issues related to the matching between the source and the reactor, and presents an example of industrial demonstrations on odor abatement at 1000 m³/h. Finally, this paper also gives a general guideline for design of corona plasma systems. [ABSTRACT FROM AUTHOR]

Presents a study which investigated the effects of the applied voltage modes on the positive corona discharge morphology and nitric oxide removal characteristics from air stream. Methodology; Typical time averaged current-voltage characteristics under the direct current (DC) and alternating current (ac)/dc operating modes; Principles of ac/dc corona plasma energization.

• Performance evaluation of a new micro cyclone with body diameter of 1 cm. • Higher flow rates yielded greater efficiencies, pressure drop and smaller cut size. • The larger particles that have been collected were greater than smaller ones. • The highest efficiency of 79%, collected the fine particles range from 1.9 to 10 μm. • It could be recommended to be utilized for indoor environmental purposes. The aim of this study was evaluating a micro gas cyclone performance with a body diameter of 10 mm to collect indoor fine particles. The design of a cyclone requires minimizing the pressure drop and maximizing the separation efficiency. Overall and grade efficiencies, pressure drops, and cut sizes have been investigated through a theoretical model, simulation, and experimental studies. The experimental part was conducted using an Electrical Low-Pressure Impactor (ELPI) device to measure particle concentration for flow rates of 10–13.3 (l/min). In order to study the pressure drop and velocity behavior for different flow rates, COMSOL software was utilized. The obtained results from experimental work have met the theoretical and simulation outcomes adequately. It has been confirmed by all the obtained results that by increasing the flow rate and subsequently inlet velocity, the particle collection efficiency and pressure drop increase while the cut size decreases. [ABSTRACT FROM AUTHOR]

An intense luminescence flash can be induced during the collapse phase of bubbles generated by pulsed discharge in water. To gain insight into this special phenomenon, we experimentally investigated the optical characteristics and luminescence temperature inside collapsing bubbles. The duration of the luminescence flash generated by pulsed discharge was around tens of microseconds, which was confirmed by high-speed recording and the photodiode output, and the inception time of the luminescence flash was approximately 32.5 μs before the bubble collapsed to its minimum size. The temperatures of the luminescence flash at discharge energies of 25 and 30 J/pulse calculated according to the two-line radiance ratio method were 6673 and 6728K, respectively. [ABSTRACT FROM AUTHOR]

This letter presents an experimental observation of luminescence flash at the collapse phase of an oscillating bubble produced by a pulsed discharge in water. According to the high speed records, the flash lasts around tens of microseconds, which is much longer than the lifetime of laser and ultrasound induced luminescence flashes in nanoseconds and picoseconds, respectively. The pulse width of temperature waveform and minimum radius calculated at the collapse phase also show that the thermodynamic and dynamic signatures of the bubbles in this work are much larger than those of ultrasound and laser induced bubbles both in time and space scales. However, the peak temperature at the point of collapse is close to the results of ultrasound and laser induced bubbles. This result provides another possibility for accurate emission spectrum measurement other than amplification of the emitted light, such as increasing laser energy or sound energy or substituting water with sulphuric acid. [ABSTRACT FROM AUTHOR]

The main technical challenges for the treatment of volatile organic compounds (VOCs) with plasma-assisted catalysis in industrial applications are large volume plasma generation under atmospheric pressure, byproduct control, and aerosol collection. To solve these problems, a back corona discharge (BCD) configuration has been designed to evenly generate nonthermal plasma in a honeycomb catalyst. Voltage-current curves, discharge images, and emission spectra have been used to characterize the plasma. Grade particle collection results and flow field visualization in the discharge zones show not only that the particles can be collected efficiently, but also that the pressure drop of the catalyst layer is relatively low. A three-stage plasma-assisted catalysis system, comprising a dielectric barrier discharge (DBD) stage, BCD stage, and catalyst stage, was built to evaluate toluene treatment performance by BCD. The ozone analysis results indicate that BCD enhances the ozone decomposition by collecting aerosols and protecting the Ag-Mn-O catalyst downstream from aerosol contamination. The GC and FTIR results show that BCD contributes to toluene removal, especially when the specific energy input is low, and the total removal efficiency reaches almost 100%. Furthermore, this removal results in the emission of fewer byproducts. [ABSTRACT FROM AUTHOR]

In this paper, the matching between a pulsed-power modulator and a streamer plasma reactor is discussed. The total process of energizing the reactor is divided into three different steps: before, during, and after plasma generation. Equivalent circuit models are used to obtain insight in the relevant mechanisms. Experiments are used to validate the results of the modeling. Based upon the results, design criteria are derived that can be used to design energy efficient streamer plasma systems. [ABSTRACT FROM AUTHOR]

Considering electrical control of electrostatic precipitation, this paper discusses particle collection in terms of corona ionic wind, gas flow pattern and high-voltage power sources. Experiments and simulations were conducted with lab-scale and industrial electrostatic precipitators. In general, a larger electrostatic precipitator (ESP) index value leads to better ESP performance. To maintain the voltage, simulation results show that a three-phase power source could operate at a lower ripple factor of 0.8% and a shorter recovery time of 5 ms after spark-over than single-phase or high frequency transformer rectifiers. For an industrial ESP with several electric fields, optimal voltage or electric field strength drops from its inlet to outlet fields. It is normally around 3.3 kV cm−1 with a large corona input power for the inlet field, and it drops to about 2.3 kV cm−1 with a small input power to limit ionic wind induced reentrainment for the last field. For a typical Chinese 660 MW coal-fired boiler with a four-field colder-side ESP, its outlet ash concentration and its PM10 and PM2.5 are usually around 15 mg m−3, 12 mg m−3 and 2 mg m−3, respectively. According to particle image velocimetry observation and particle collection measurements, we found that the corona wind generated vortex can result in not only enhancement of collection but also particle reentrainment and/or the so-called ‘bypass flow’. An optimum electric field inside the ESP exists to save energy and collect particles. For present ESPs, a higher electric field (>3.5 kV cm−1) generates strong electrohydrodynamic flow, which consequently undermines the collection due to turbulent flow. Advanced industrial automatic voltage controllers for three-phase transformer rectifier and double-wire ESPs have been developed according to those experimental results for both reducing emission and corona energy consumption. [ABSTRACT FROM AUTHOR]