Cylindrical Dielectric Barrier Discharge Reactor Research Articles

Degradation of methylene blue aqueous solution using atmospheric pressure dielectric barrier discharge

Methylene blue (MB) is toxic to humans and aquatic animals, and its removal from aqueous solutions requires high power consumption and long processing times. To improve the effect of dielectric barrier discharge (DBD) treatment of methylene blue and increase the energy utilization rate. In this study, we employed a novel approach, using a cylindrical DBD reactor, to treat MB in aqueous solutions. We found several factors, including input voltage, aqueous solution flow rate, number of high voltage electrodes, electrode size, and inside diameter of the dielectric tube influenced the MB removal rates with DBD. Our experimental results indicate that the change of electrode parameters can effectively improve the removal rate of methylene blue in DBD plasma treatment. At the same time, electrode parameters can lead to medium layer change of energy consumption; hence, the influence of electrode parameters on energy utilization efficiency also has an optimal value.

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.

Effect of voltage and oxygen on inactivation of E. coli and S. typhi using pulsed dielectric barrier discharge

This work presents the study of the voltage and oxygen effect on bacterial inactivation in water using a pulsed dielectric barrier discharge (DBD) under atmospheric pressure, where Escherichia coli (E. coli) and Salmonella typhi (S. typhi) bacteria were used as model microorganisms. A cylindrical DBD reactor was developed and tested in applications to assay the efficiency of bacterial inactivation in water on a volume of 500 mL flowing continuously throughout the system assisted with a peristaltic pump at 4.4 ± 0.1 mL/s. The efficiency of the treatment reached a 6-log10 reduction for both E. coli and S. typhi bacteria at 106 CFU/mL of concentration at the end of the first cycle of treatment at a minimum voltage of 12 kV with oxygen bubbling gas, concluding that there was a minimum voltage to produce inactivation of E. coli and S. typhi samples. Bacterial inactivation without the oxygen condition contrasted with the high rate of inactivation with oxygen at relatively low voltage discharges.

Integrated gasification and non-thermal plasma-catalysis system for cleaner syngas production from cellulose

An innovative integrated gasification and plasma-catalytic system has been developed to produce cleaner syngas from a model biofeedstock (α-cellulose). The influence of Co/γ-Al2O3 catalyst on the plasma reforming of tar-contaminated syngas has been investigated using a cylindrical dielectric barrier discharge reactor. The results show that plasma-catalytic processing of the syngas from biomass gasification significantly reduces the concentration of tars by 88% and enhances the total gas product yield and the syngas ratio (H2/CO) by up to 90%.

Effects of discharge parameters on carbon dioxide conversion in TiO2 packed dielectric barrier discharge at atmospheric pressure

A cylindrical dielectric barrier discharge reactor packed with TiO2 is developed to convert undiluted carbon dioxide (CO2) into CO and O2 at atmospheric pressure. Basing on linear regulation of instruments, a series of typical discharge parameters have been electrically controlled and measured in an attempt to find the maximum CO2 conversion and the best energy coupling. It is discovered that CO2 conversion has a stronger correlation with apply voltage, and further research manifested that lowering feed gas flow and increasing discharge frequency contribute to higher CO2 conversion within our controllable range. After comprehensive analysis of these trends and results of subsequent experiments, the maximum CO2 conversion of 12.72% is achieved at the voltage of 22 kV, with 9.09 kHz frequency and 20 ml/min flow rate, and the highest energy efficiency of 15.80% is achieved at the voltage of 22 kV, with 8.47 kHz frequency and 20 ml/min flow rate.

Real-time monitoring and quantification of organic by-products and mechanism study of acetone decomposition in a dielectric barrier discharge reactor.

Non-thermal plasma (NTP) degradation of low-concentration acetone was investigated in a cylindrical dielectric barrier discharge reactor. The effects of oxygen content and flow rate on the removal efficiency at various discharge powers were examined in real-time. The acetone removal efficiency decreases drastically and then remains stable or increases gradually as the O2 content increases from 0 to 25%, and further to 50%. The organic by-products were characterized and quantified using a real-time proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) instrument. The observed organic compounds, with concentrations about ppbv/ppmv by volume, were mainly formaldehyde, methanol, ketene, acetaldehyde, formic acid, acetone, and acetic acid. The discharge power was a critical factor affecting the concentration of the organic by-products and the selectivity toward CO2. The mechanism study based on the by-product monitor in real-time showed that acetone firstly fragments into methyl radicals, acetyl radicals, and H; then, the methyl and acetyl radicals are oxidized by O or OH radicals into acetaldehyde, methanol, and other compounds. It seems that acetaldehyde could be an intermediate in acetone decomposition. Firstly, most of the acetone molecules were decomposed into acetaldehyde molecules; then, the acetaldehyde molecules continued to be decomposed and oxidized into other compounds, such as acetic acid and formaldehyde. These investigations not only proposed a detail decomposition mechanism for acetone in dielectric barrier discharge reactor, but also provided a potential way to analyze and evaluate the practicability of NTP removal of VOCs.

Effect of Glass Additions on Ca 0.8 Sr 0.2 TiO 3 Ceramics as Dielectrics for a Cylindrical Dielectric Barrier Discharge Reactor in CO 2 Plasma

The Ca 0.8 Sr 0.2 TiO 3 ceramics with different amounts of glass addition were prepared by liquid phase sintering and used as dielectric barriers in a cylindrical dielectric barrier discharge reactor to decompose carbon dioxide at atmospheric pressure. Results show that the surface resistivity increases with increasing glass content. While the dielectric constant does not change obviously with the increase of the glass content in the investigated temperature range. The scanning electron microscope observations indicate that both the grain size and the thickness of intergranular glassy phases increase with the increase of the glass content. More importantly, the conversion rate and conversion efficiency of carbon dioxide improve with the increase of glass content in the ceramics. Furthermore, a combined discharge analysis and dielectric characterization are modeled with a Malter effect approach. From this model, it is possible to interpret the relationship between the conversion characteristics and the glass content in the ceramic samples.

Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

Non-thermal plasma (NTP) treatment reactors have recently been developed for elimination of diesel particulate matter for reducing both the mass and number concentration of particles. The role of the plasma itself is obscured by the phenomenon of particle deposition on the reactor surface. Therefore, in this study, the Lagrangian particle transport model is used to simulate the dispersion and deposition of nano-particles in the range of 5 to 500 nm in a NTP reactor in the absence of an electric field. A conventional cylindrical dielectric barrier discharge reactor is selected for the analysis. Brownian diffusion, gravity and Saffman lift forces were included in the simulations, and the deposition efficiencies of different sized diesel particles were studied. The results show that for the studied particle diameters, the effect of Saffman lift is negligible and gravity only affects the motion of particles with a diameter of 500 nm or larger. Time histories of particle transport and deposition were evaluated for one-time injection and a continuous (multiple-time) injection. The results show that the number of deposited particles for one-time injection is identical to the number of deposited particles for multiple-time injections when adjusted with the shift in time. Furthermore, the maximum number of escaped particles occurs at 0.045 s after the injection for all particle diameters. The presented results show that some particle reduction previously ascribed to plasma treatment has ignored contributions from the surface deposition.

DBD Reactor Electric Field Distribution and Influence Factor

As an effective method in automobile tail gas treatment, dielectric barrier discharge（DBD）is introduced. There are many parameters In DBD reactor that influence nitrogen oxide treatment reaction including discharge voltage, discharge frequency, discharge distance, gas influence and electrode structure. Discuss the influence of discharge voltage, discharge distance and medium thickness to electric field distribution in cylindrical DBD reactor through 2D numerical simulation

Ethylene Epoxidation in Cylindrical Dielectric Barrier Discharge: Effects of Separate Ethylene/Oxygen Feed

The effects of separate C2H4/O2 feed and C2H4 feed position on the ethylene epoxidation reaction in an AC cylindrical dielectric barrier discharge reactor were investigated. The highest EO selectivity of 34 % and EO yield of 7.5 %, as well as the lowest power consumption of 1.72 × 10−16 Ws/molecule of EO produced, were obtained at a C2H4 feed position of 0.25, an O2/C2H4 feed molar ratio of 1/4, an applied voltage of 13 kV, an input frequency of 550 Hz, and a total feed flow rate of 75 cm3/min. The results demonstrated, for the first time, that the separate feed of C2H4 and O2 could provide better ethylene epoxidation performance in terms of higher EO selectivity and yield, and lower power consumption, as compared to the mixed feed. All undesired reactions including C2H4 cracking, dehydrogenation, oxidation, and coupling reactions are lowered by the ethylene separate feed because of a decrease in opportunity of ethylene molecules to be activated by generated electrons.

Investigation of Cracking by Cylindrical Dielectric Barrier Discharge Reactor on the n-Hexadecane as a Model Compound

The main process in oil refinery technologies is the cracking of the heavy fraction of oil into light and valuable hydrocarbons. Dielectric barrier discharge (DBD) reactors, working at atmospheric pressure and low temperature, is one of the newest methods for cracking hydrocarbons, which has been successfully used to crack low-carbon-containing molecules. Therefore, in this paper, the cracking of n-hexadecane as a heavy hydrocarbon fed by using the cylindrical DBD reactor (nonthermal plasma) has been investigated. We studied the effects of gas type, applied voltage, and gas flow rate quantitatively and qualitatively by using gas chromatography with flame ionization detector and mass spectrometry detector. Results showed that methane has better effects on both conversion and cracking percentage in comparison with air. Also, it has been shown that increasing the applied voltage and working gas flow rate enhances the conversion and the cracking percentages. The highest conversion percentage obtained was 9.26% when the applied voltage and methane flow rate were 12 kV and 50 sccm. In this condition, the cracking percentage obtained was 84.34% of the products.

Methane Oligomerization in a Dielectric Barrier Discharge at Atmospheric Pressure

AbstractThe conversion of methane into more valuable higher hydrocarbons has been more and more fascinating for both the industry and the scientific community. Recently, the direct conversion of methane by using various plasma technologies has received particular attention. This work reports on the formation of a liquid deposit during the plasma treatment of methane mixtures in a coaxial cylindrical dielectric barrier discharge reactor at atmospheric pressure. In order to investigate its nature, the liquid deposit has been analyzed by spectroscopic and mass spectrometric techniques. The material consists of a mixture of hydrocarbons, the most represented moiety being the gem‐dimethyl group CC(CH3)2C.magnified image

Conduction heat transfer in a cylindrical dielectric barrier discharge reactor

The thermal behaviour of a dielectric barrier discharge reactor is studied. The experimental tests are performed on a laboratory reactor with two working fluids: helium and air. A simple heat conduction model for calculating the heat loss is developed. By using temperature measurements in the internal and external electrodes, a thermal resistance of the reactor is defined. Finally, the percentage of the input power that is dissipated to the environment is given.