Effect Of Dielectric Barrier Discharge Research Articles

Efficacy of atmospheric pressure dielectric barrier discharge for inactivating airborne pathogens

Atmospheric pressure plasmas have gained attention in recent years for several environmental applications. This technology could potentially be used to deactivate airborne microorganisms, surface-bound microorganisms, and biofilms. In this work, the authors explore the efficacy of the atmospheric pressure dielectric barrier discharge (DBD) to inactivate airborne Staphylococcus epidermidis and Aspergillus niger that are opportunistic pathogens associated with nosocomial infections. This technology uses air as the source of gas and does not require any process gas such as helium, argon, nitrogen, or hydrogen. The effect of DBD was studied on aerosolized S. epidermidis and aerosolized A. niger spores via scanning electron microscopy (SEM). The morphology observed on the SEM micrographs showed deformations in the cellular structure of both microorganisms. Cell structure damage upon interaction with the DBD suggests leakage of vital cellular materials, which is a key mechanism for microbial inactivation. The chemical structure of the cell surface of S. epidermidis was also analyzed by near edge x-ray absorption fine structure spectroscopy before and after DBD exposure. Results from surface analysis revealed that reactive oxygen species from the DBD discharge contributed to alterations on the chemistry of the cell membrane/cell wall of S. epidermidis.

Experimental Investigation on the Effects of DBD Plasma on the Film Cooling Effectiveness of a 30-Degree Slot

The effects of dielectric barrier discharge (DBD) plasma on the film cooling effectiveness of a 30-degree slot was experimentally investigated in a low-speed wind tunnel. The pressure sensitive paint (PSP) technique was used to measure the film cooling effectiveness, and two blowing ratios (0.5 and 1.0) were tested. A sinusoidal waveform with a 1-kHz frequency was supplied to the exposed electrode. Two input voltages (6 and 7 kV) and two exposed electrode locations were considered. The results showed that the film cooling effectiveness of the slot was higher for the blowing ratio of the 1.0 case than that for the blowing ratio of the 0.5 case regardless of plasma operation. The higher input voltage case (7 kV) showed higher film cooling effectiveness than the lower input voltage case (6 kV). The improvement in film cooling effectiveness facilitated by the DBD plasma was more significant when the coolant had less momentum. The maximum improvement of the area averaged film cooling effectiveness was 2.3% for the case with the exposed electrode located at the slot exit and a blowing ratio of 0.5.

Characterization of physicochemical and structural properties of atmospheric cold plasma (ACP) modified zein

Atmospheric cold plasma (ACP) has been widely reported as an efficient approach in material surface modification. The effects of dielectric barrier discharge (DBD) ACP technology on the physicochemical and structural properties of powdered zein were investigated. The results indicated that the average diameter of zein particles decreased significantly indicating a depolymerization of aggregations after ACP treatment. There was an increase of free SH group concentration and decrease of pH in zein solutions. Significant improvement of zein solubility in both neutral and acidic solutions could be observed after treatment with max solubility at 75V. Moreover, Differential Scanning Calorimetry (DSC) and X-ray diffraction (XRD) results indicated that ACP treatment rearranged the conformation. FTIR spectrum confirmed the change of secondary structure for amide I region (1600–1700cm−1) after ACP treatment. Furthermore, the film forming properties of zein were also studied. It was found that the increase of ACP treatment voltage level could reinforce the tensile strength (TS) and surface hydrophilicity of zein films. It is suggested that the DBD ACP technology can effectively modify the physicochemical properties for protein powders.

Study on the Enhancement Effect of Dielectric Barrier Discharge on the Premixed Methane/Oxygen/Helium Flame Velocity**supported by the Fundamental Research Funds for the Central Universities of China (No. xjj2013086), Natural Science Basic Research Plan in Shaanxi Province of China (No. 2014JQ7254) and National Natural Science Foundation of China (No. 51477135)

Recently, plasma-assisted combustion has become a potentially applicable technology in many combustion scenarios. In this paper, a dielectric barrier discharge (DBD) plasma generator is designed to explore the effect of plasma on the CH4 oxidation process, and several properties of combustion are considered. First, in the presence or absence of plasma discharge, physical appearance of the flame is examined and analyzed. Second, the flame propagation velocity is calculated by the flame front extracted from the imaging data with the Bunsen burner method. Finally, the main molecular components and their intensity variation in the flame and the plasma zones are identified with an emission spectrograph to analyze the effect of active species on the combustion process. We also discuss the possible kinetic regime of plasma-assisted combustion. Experimental results imply that plasma discharge applied to the premixed CH4/O2/He mixture significantly raises the flame speed with equivalence ratios ranging from 0.85 to 1.10, with the flame speed improved by 17% to 35%. It can be seen that plasma can improve methane oxidation efficiency in the premixed fuel/oxidizer, especially at a low equivalence ratio.

Plasma Induced Physicochemical Changes and Reactive Dyeing of Wool Fabrics

This study focuses on the effect of dielectric barrier discharge (DBD) plasma treatment on physical and chemical properties of wool fabric and its relation to exhaustion of Drimalan Navy Blue FBI reactive dye. AFM analysis of plasma treated wool fabric has shown partial removal of epicuticle and thus reduced scale height. FD spectroscopy has shown improvement in hydrophilicity by many folds after plasma treatment. ATR graphs depict the removal of hydrophobic layer of 18-MEA and introduction of hydrophilic groups like cysteic acid after plasma treatment. Alkali solubility of wool fabric increases with increasing plasma treatment time. Wetting time for plasma treated fabric reduces drastically when compared to untreated wool fabric. It is found that plasma treated fabric takes much lesser time to reach maximum dye exhaustion than untreated fabric. Substantivity of the dye increases significantly after plasma treatment. Colour fastness properties improve with increase in plasma treatment time. Chemical oxygen demand (COD) of spent dyebath liquor is found to reduce with increase in plasma treatment time. Biological oxygen demand (BOD) is found to be higher for plasma treated samples, while ratio of COD/BOD has reduced with increase in the plasma treatment time.

Treatment of poly(ethylene terephthalate) foils by atmospheric pressure air dielectric barrier discharge and its influence on cell growth

In this contribution an effect of dielectric barrier discharge (DBD) sustained in air at atmospheric pressure on surface properties of poly(ethylene terephthalate) (PET) foils is studied. It is found that exposure of PET to DBD plasma leads to rapid changes of surface chemical composition, wettability, surface morphology as well as mechanical properties of PET surface. In addition, based on biological tests that were performed using two cell types (Saos-2 human osteoblast-like cells and HUVEC human umbilical vein endothelial cells), it may be concluded that DBD plasma treatment positively influences cell growth on PET. This effect was found to be connected predominantly with increased surface energy and oxygen content of the surface of treated PET foils.

0616 ナノ秒パルスプラズマアクチュエータを用いた翼上の流れ制御のための数値モデル

The significant effects of dielectric barrier discharge (DBD) driven by repetitive nanosecond (NS) pulse voltage on lift enhancement on stalled airfoils have been demonstrated. The essential effect of NS plasma is considered as thermal effect. The detailed effect of the thermal excitation on the vortex structures is, however, not fully understood. In the present work, a simple momentum model for incompressible Unsteady Reynolds-Averaged Navier-Stokes simulation was proposed, in which the effect of plasma was implemented as a wall velocity boundary condition on the airfoil. Although this simplified simulation does not take account of thermalization process and shock dynamics, the results showed discrete vortices generated by rolling-up shear layer over the leading edge. It qualitatively consisted with the trend of time-averaged pressure distribution obtained by the corresponding experiment.

Experimental and Numerical Study of Boundary Layer Transition Control Over an Airfoil Using a DBD Plasma Actuator

In this paper, the effects of Dielectric Barrier Discharge (DBD) actuation on the boundary layer transition have been studied on an ONERA-D airfoil both experimentally and numerically. The experiment has been conducted in a subsonic windtunnel for freestream velocities up to 24 m/s and for two different actuator locations. Hot-wire probing enabled to quantify the influence of the ionic wind on the boundary layer mean velocity profiles and on the resulting transition shifts. The maximum measured transition delay was about 6% of chord. These measurements served as references to establish a numerical model of the body force induced by a plasma actuator. Linear stability analysis is then applied to the mean flow induced by the body force model and compared to the measured mean velocity profiles.

Dielectric Barrier Discharge Plasma Efficiently Delivers an Apoptotic Response in Human Monocytic Lymphoma

In this paper, we demonstrate the effect of dielectric barrier discharge (DBD) plasma on lymphoma and normal blood mononuclear cells. Results indicates enhanced level of reactive oxygen species in U937 cells, which presented a compromised redox status evident from increased NADP+/NADPH levels, reduced GSH/GSSG ratios and decreases in the total endogenous antioxidant activity of cells. A plasma treatment drastically reduces cell viability, causing more severe damage to DNA and mitochondria, as determined by means of apoptosis indicators and related genes expression. Taken together, these findings indicate a significant level of apoptosis in plasma‐treated lymphoma cells. This report lends insight into progress toward an appropriate therapy for blood cancers using non‐thermal DBD plasma.

Study on the Effects of Dielectric Barrier Discharge on the Bunsen Flame Structure With OH-PLIF Technique

Nonthermal equilibrium plasma has been reported to be potentially applicable in many combustion scenarios. In this paper, the effects of dielectric barrier discharge (DBD) on the flame structure of a Bunsen flame have been investigated by using the OH planar laser-induced fluorescence technique. Results show that the increase of discharge intensity significantly enhances the local burning. In coaxial-cylinder DBD reactor, the flame structure can be varied from conic shape to M shape with discharge power increasing.

Numerical modeling of coanda effect in a novel propulsive system

Coanda effect (adhesion of jet flow over curved surface) is fundamental characteristics of jet flow. In the present paper, we carried out numerical simulations to investigate Coanda flow over a curved surface and its application in a newly proposed Propulsive system “A.C.H.E.O.N” (Aerial Coanda High Efficiency Orienting jet Nozzle) which supports thrust vectoring. The ACHEON system is presently being proposed for propelling a new V/STOL airplane in European Union. This system is based on cumulative effects of three physical effects such as (1) High speed jet mixing speeds (2) Coanda effect control by electrostatic fields (3) Coanda effect adhesion of an high speed jet to a convex surface. The performance of this nozzle can be enhanced by increasing the jet deflection angle of synthetic jet over the Coanda surface. This newly proposed nozzle has wide range of applications. It can be used in industrial sector such as plasma spray gun and for direct injection in combustion chamber to enhance the efficiency of the combustion chamber. Also, we studied the effect of Dielectric barrier discharge (DBD) plasma actuators on A.C.H.E.O.N system. Dielectric barrier discharge (DBD) plasma actuators are active control devices for controlling boundary layer and to delay the flow separation over any convex surfaces. Computations were performed under subsonic condition. Two dimensional CFD calculations were carried out using Reynolds averaged Navier stokes equations (RANS). A numerical method based on finite volume formulation (FVM) was used. SST k-ω model was considered to model turbulent flow inside nozzle. DBD model was used to model the plasma. Moreover, a body force treatment was devised to model the effect of plasma and its coupling with the fluid. This preliminary result shows that, the presence of plasma near Coanda surface accelerates the flow and delays the separation and enhances the efficiency of the nozzle.

Effects of dielectric barrier discharge in air on morphological and electrical properties of graphene nanoplatelets and multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) have been functionalized by dielectric barrier discharge (DBD) in air. The extent of functionalization of MWCNTs and GNPs reaches a maximum at the delivered discharge energy of 720 and 240Jmg−1, respectively. Further exposure to plasma leads to reduction of functional groups from the surface of the treated nanomaterials. It has also been demonstrated that DBD plasma does not produce dramatic structural changes in MWCNTs, while flakes of the treated GNPs become thinner and smaller in the lateral size. Conductive thin films, obtained by drop casting a solution of the treated nanomaterials in N-methyl-1-pyrrolidone on poly(methyl methacrylate) substrate, show significantly lower sheet resistance.

The combination effect of dielectric barrier discharge (DBD) and TiO2 catalytic process on styrene removal and the analysis of the by-products and intermediates

A wire-tube dielectric barrier discharge (DBD) reactor was established to treat styrene, which is a typical industrial pollutant with high toxicity and odorous smell, with TiO2 coated on the surface of the electrode and inner tube wall, respectively, by a simple and economic sol–gel method. The degradation and mineralization performance were comprehensively compared in the original reactor without TiO2 and in the reactor with TiO2 coated on the electrode and inner tube wall, respectively. As well as high catalytic efficiency, TiO2 also has high photocatalytic activity and can be excited by the energetic particles and ultraviolet radiation generated in the DBD reactor. Extra UV lamps were employed to verify the photocatalytic process in the presence of TiO2 during the reaction. The results showed that the degradation and mineralization efficiency obtained in the TiO2/inner tube wall reactor was much higher than that obtained in the TiO2/electrode reactor, and both of them were better than the original reactor. The types and the amounts of by-products during the reaction decreased in the order of the TiO2/inner tube wall reactor, the TiO2/electrode reactor, and the original reactor. The amounts of nitrogenous by-products and NO x decreased significantly in the reactors with the TiO2 coating, which indicated that the energy of the particles decreased in the presence of the high resistance TiO2 catalyst and scarcely destroyed N2, while improving the degradation and mineralization efficiency during the reaction.

Antimicrobial viscose fabric prepared by treatment in DBD and subsequent deposition of silver and copper ions—Investigation of plasma aging effect

In this work, the effect of dielectric barrier discharge (DBD) in ambient air on preparation of antimicrobial viscose fabric was studied. DBD plasma treatment was applied under constant discharge power and different exposure times. Vertical wicking test was used to evaluate optimal conditions for plasma treatment of viscose in order to increase fabrics' wettability and consequently improve sorption properties. Investigation of aging effect of plasma treatment revealed that there was no significant change in wettability of viscose samples 21days after plasma treatment, which suggests good durability of treatment. After DBD plasma treatment, fabrics were modified with silver and copper ions in order to impart antimicrobial properties on viscose fabric. Viscose samples, modified with Ag (I) and Cu (II) ions immediately and 1, 7, 14 and 21days after DBD treatment were tested in vitro against microorganisms S. aureus, E. coli and C. albicans using agar diffusion test. Obtained results showed that modification with DBD, prior to sorption of Ag (I) and Cu (II) ions, leads to improvement of antimicrobial activity of viscose samples, with a possibility to provide specific activity against different microorganisms by altering the days after DBD treatment prior ions sorption.

Effects of AC Dielectric Barrier Discharge Plasma Actuator Location on Flow Separation and Airfoil Performance

The goal of this work is to characterize the effect of Dielectric Barrier Discharge (DBD) plasma actuator on the lift and drag coefficients generated by the flow around a NACA 4415 airfoil model using force-balance and Particle Image Velocimetry (PIV) measurements. DBD actuators are mounted at the leading edge, at 30% and 60% of the chord length. The effect of actuation on the airfoil lift and drag at these different locations are studied. It is found that for increasing angles of attack, the actuators need to be located closer to the leading edge and in front of the separation area to produce the best lift or drag coefficient improvements. If located within the flow separation zone, their effects on the airfoil lift and drag coefficients are limited.

EXPERIMENTAL INVESTIGATION OF DIELECTRIC BARRIER DISCHARGE EFFECT ON VELOCITY AND PRESSURE PULSATIONS IN A SUBSONIC JET

As applied to the problem of noise reduction of reactive jets in aviation engines, an investigation of the effect of dielectric barrier discharge (DBD) on velocity and static pressure pulsations was performed. The discharge was created inside an axisymmetrical subsonic nozzle near the nozzle exit section. The investigation was carried out in the jet formed by the nozzle at jet speeds of 80‐135 m/s. The data describing the DBD effect on the distribution of the average velocity at the nozzle exit, on the spectra of the velocity and pulsations, and also on the transformation of such an effect as long as we move from the nozzle section, are presented.

放电频率对DBD气动激励影响的数值分析

The effect of dielectric barrier discharge (DBD) plasma to enhance the aerodynamic characteristics of an airfoil was numerical studied, and the effect of different discharge frequencies on the DBD plasma aerodynamic actuation was analyzed. The results show that DBD plasma flow control could restrain the flow separate phenomena at low Re condition. As the discharge frequency increased, the plasma induced flow velocity will increase first and then decrease. But the velocities oscillating frequencies change in no rules. The velocities oscillating frequencies will increase as the discharge frequencies increase at the range of multiple frequencies of vortex break off frequency or not. The lift drag ratio of airfoil will increase as the discharge frequencies increase, but the difference is tiny in different cases with different discharge frequencies. The oscillate frequencies of airfoil aerodynamic change in a big range as the discharge frequencies changed, and it have the same rule as the velocities oscillate frequencies in the air.

Effect of DBD plasma on human cells in presence of osmolytes and denaturant

ABSTRACTNon thermal plasma is emerging as a novel tool for the treatment of living tissues for biological and medical purpose. In this study we described the effect of DBD (dielectric barrier discharge) plasma on both cancer and normal cell line in presence of osmolytes. Osmolytes having unique protective metabolic roles and also found in animal body, they are acting as antioxidants, providing redox balance, detoxifying sulfide, protect macromolecules, enhance protein folding and regulate cell volume. Based on these interesting properties of osmolytes, non thermal plasma in presence of osmolytes appears to provide a new outlook. Results of this study reveals that osmolytes in presence of plasma act as protecting agent for normal cells however, not to cancer cells in the presence of plasma. The main goal of this study is to protect normal cells from the toxic effect of DBD plasma.

Effect of dielectric barrier discharge on the airflow around a cylinder

Fluids in a dielectric barrier glow discharge at atmospheric pressure have attracted interest from communities of thermo and fluid dynamics, as well as control. This work investigated the effects of a plasma actuator, operating at 8.0 kV and 4.4 kHz, on the pressure distribution around a polyvinyl chloride circular cylinder in low-velocity airflow. The experiment was repeated with the actuator at various angles. The results show an acceleration of the flow demonstrated by a 60% lower pressure coefficient at the actuator area. The flow separation was also delayed by an angle of as much as 30o. These effects were shown to be greater when the actuator was positioned at an angle closer to the separation area.

Effect of dielectric barrier discharge on semiconductor Si electrode surface

Electrode materials and shapes affected the discharge modes. Meanwhile, the discharge has influence upon electrode surface. In order to study the effect of discharge on semiconductor electrode, the experiments were carried out using single crystal Si wafer as high voltage electrode of atmospheric pressure dielectric barrier discharge in air. The effects of dielectric barrier discharge on Si electrode surface are analyzed by means of field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). The results show that surface roughness and oxidation increase with discharge time, while surface nitridation is not observed on Si electrode surface. It is different from Cu electrode. The difference is due to different chemical reactions between electrode surface and air plasma but could also be ascribed to the different analysis techniques used.