Papers by Keyword: Atmospheric Pressure

Abstract: Two kinds of multiple-pulse were reported on atmospheric plasma jet (APPJ) of dielectric barrier discharge (DBD) configurations in this study. Meanwhile, the investigation on electrical characteristics of APPJ in helium and helium/air was carried out with the aim of shedding light on the electrode parameters for dissipated power and jet length. The typical bacteria, E. coil, were employed to study the effect by the two APPJ devices (PJ-1 and PJ-2). For PJ-1, multiple-pulse appears in both sides of every half-cycle, but only in the positive half-cycle for PJ-2. A wider power electrode of PJ-1 and further distance from the nozzle to grounding electrode of PJ-2, whether in ambient helium or helium/air, are all conducive to improvement of dissipated power. With the increase of gas flow rate, the jet length will become longer at laminar flow mode, then get shorter, and a permanent to the end. Generally, the introduction of air leads a better sterilization effect, especially for PJ-1. Keywords: Atmospheric Pressure, multiple-pulse, Electrode parameters, dissipated power, jet length, plasma jet. PACS: 52.80.-s, 52.77.-j

Abstract: In order to obtain stable cold plasma jet under atmospheric pressure condition, we designed a high-voltage DC power supply based on the principle of multilayer piezoelectric ceramic transformer (MPT). At the same time, we developed a cold plasma jet device that its shape is similar to the gun structure. The total weight of device, including the power supply and the generator, is less than 500 g. In the experiments of argon plasma under atmospheric pressure, current–voltage measurements show that the discharge actually appears periodically pulsed with a frequency of about 30 kHz. The discharge current has a pulse-width that is about 100 ns, while its peak value reaches about 32 mA. The maximum length of the plasma is about 3 cm. The further study showed that the discharge current pulse frequency is determined by the ion drift mechanism.

Abstract: Polyimide (PI) has good mechanical properties, heat resistance and low temperature performance, and thus shares a wide range of applications. Atmospheric pressure plasma jet was designed for polyimide films surface modification in this paper. The impacts of exposure time and gas ratio on the film surface morphology and property were studied. Scanning Electron Microscope (SEM) results prove that the treated film surface becomes rough and the contact angle decreases rapidly with exposing to plasma. The contact angle did not decrease anymore after extending plasma exposing time to 20 seconds Moreover the intensity of C=O absorption band increases as shown in the Fourier transform infrared spectroscopy (FTIR).

Abstract: To study the effect of the biodiesel on the performance of the high pressure common rail diesel engine performance, a experiment is conducted about the high pressure common rail diesel engine uses diesel fuel and different blending ratio of biodiesels. The results show that with the rising of the altitude, the engine power and the brake specific fuel consumption reduce, exhaust gas temperature increases; At the same altitude, the engine fueled with different blending ratio of bio-diesel has higher brake specific fuel consumption in comparison with fueled engine, but it has lower power, with the increase in bio-diesel blending ratio, engine power, fuel consumption increase.

Abstract: In this study, functional-group-retaining polymerization of hydroxyethyl methacrylate (HEMA) was carried out by using an atmospheric pressure non-equilibrium Ar plasma jet. The polymeric films deposited under different conditions were characterized by Fourier transform infrared spectroscopy (FT-IR). The FT-IR spectra show that HEMA was polymerized (carbon-carbon double bond disappeared) and the main functional groups were successfully retained in the plasma-polymerization films. The plasma-polymerization mechanism and the polymerization reaction kinetics will be discussed.

Abstract: In this study, a 35-μm-thick copper sub-micron paste (particle diameter of 700 - 900 nm) was printed on an alumina substrate, and then sintered by conventional heating treatment and by atmospheric pressure plasma (APP) treatment, respectively. Surface micro-structures of the printed films sintered by both methods were observed by SEM. As a result, copper sub-micron particles were successfully sintered at a relatively low temperature by APP treatment. Through the SEM micrographs we suppose that the sintering processes by both methods are quite different.

Abstract: The theory of Least Squares Support Vector Machines was applied to metal surfaces cleaning by atmospheric pressure plasma arc. An intelligent predictive model of the non-linear relationship between cleaning quality and process parameters was established with the k-fold cross training of sample data. An orthogonal experiment was conducted to assess the effect of processing parameters on surface quality. The experimental results and predicted values show that the atmospheric pressure plasma arc (APPA) cleaning is effective in reducing considerably the amount of lubricant. Furthermore, it is feasible to apply LS-SVM in forecasting the cleaning quality and determining processing parameters, and the mean absolute percent error e_MAPE between predictive value and experimental value of water contact angle is 6.09%. Otherwise, the e_MAPE of working current is 4.46%.

Abstract: Atmospheric pressure changes on the fully mechanized top-coal caving has very significant effect to gas emission produce, through discussion to the mine gas emission source,and analysis the actual measured data.Get the result:with the rise of the ground atmospheric pressure ,the mine gas emission is absolutely reduced,and gas changes in return flow is after atmospheric pressure changes 0.5-1h later. Summarized measures to the gas emission suddenly increased.To the coal mine has guiding significance for production safety.

Abstract: Due to safety consideration of storage and transportation of liquid fuel at low atmospheric pressure region, the influence of low atmospheric pressure on heptane jet fire was numerically investigated, based on LES and mixture-fraction combustion model. Injection heptane diameters satisfy Rosin-Rammler distribution. The simulation shows that, low atmospheric pressure has an evident effect on jet fire. It extends the fire length and shortens the lift-off height. The centerline temperature rises to the maximum value more rapidly and then it decays more slowly. The maximum centerline temperature is not sensitive to various atmospheric pressure.

Abstract: This article describes the three dimensional electromagnetic modeling of a microwave (2.45 GHz) plasma device, based on an axial injection torch (AIT). The model solves Maxwell's equations by the finite integration technique (FIT). We are interested in obtaining the optimal position of the short circuit in order to obtain the best percentage of coupling at 2.45 GHz. and understanding the influence of various geometrical parameters on the physical distribution of the electromagnetic field and on the power transfer within the structure.