جستجوی مقالات مرتبط با کلیدواژه « Dielectric Barrier Discharge » در نشریات گروه « علوم پایه »

In this work, plasma has been used as a simple, very fast, low energy and efficient method for modification of the zinc oxide nanopowder to improve its photocatalytic activity. Zinc oxide is one of the effective photocatalysts in degradation of the organic contaminants, e.g. dyes. The purpose of the zinc oxide photocatalyst modification is to reduce the band gap and thus to increase its photocatalytic activity in the visible light range. To achieve nitrogen-doped zinc oxide nanoparticles (N-Doped ZnO), the zinc oxide nanopowder was suspended in melamine solution, as nitrogen precursor, and then treated with a non-thermal atmospheric pressure plasma. Different concentrations of melamine and different times of plasma exposure were considered for optimizing the nitrogen-doped zinc oxide structure. The photocatalyst properties of the pure zinc oxide and optimized nitrogen-doped zinc oxide samples were investigated by XRD, FESEM, EDX, BET, DRS and PL analyses. The photocatalytic activity of the pure zinc oxide nanopowder and plasma-treated samples were performed in the photocatalytic degradation of methylene blue dye contaminant. The degradation efficiency of methylene blue by the pure zinc oxide was 71.7%. By applying plasma to the zinc oxide nanopowder for 5 minutes with a concentration of 500 mg/L of melamine solution, the degradation efficiency was enhanced to 90%. According to the results, it can be seen that the plasma treatment has succeeded in the nitrogen doping process to the zinc oxide structure and improved its photocatalytic activity.

In this work, we investigated generating argon cold plasma jet at atmospheric pressure based on dielectric barrier discharge configuration using three electrical power supplies of sinusoidal, pulsed and saw tooth high voltage shapes at 8 KHZ. At first; we describe the electronic circuit features for generating high voltage (HV) wave forms including saw tooth, sinusoidal and pulsed forms. Then, we consider the effect of voltage shape on the electrical breakdown. Relative concentrations of chemical reactive species such as Oxygen, atomic Nitrogen and OH were measured using optical emission spectroscopy. Using a simple numerical model, we showed a HV with less rise time increases electron density, therefore a cold plasma jet can be produced with a minimal consumption electrical power.

Arrays of dielectric barrier discharge are used for control of various aerodynamic phenomena such as control flow separation. In order to control this phenomenon by the generated momentum، it is needed to determine the maximum discharge voltage required to the momentum generation. By image processing، maximum momentum produced and consequently maximum discharge voltage can be determined with using plasma flame length and light intensity. The advantage of this method compared to other methods is simplicity and availability of a camera as the only required equipment. In this study، an array of 8DBD actuators arranged perpendicular to flow on NACA0012 is installed in a wind tunnel. Performance and maximum discharge voltage can be determined by processing the images captured from the arrays in different discharge voltages and dynamic pressures. Using image processing method for evaluating the efficiency of DBD actuators and accessing the maximum discharge voltage for flow separation control is unprecedented.