Power consumption analysis DBD plasma ozone generator

Studies on the consumption of energy by an ozone generator with various constructions electrodes of dielectric barrier discharge plasma (DBDP) reactor has been carried out. This research was done to get the configuration of the reactor, that is capable to produce high ozone concentrations with low energy consumption. BDBP reactors were constructed by spiral- cylindrical configuration, plasma ozone was generated by high voltage AC voltage up to 25 kV and maximum frequency of 23 kHz. The reactor consists of an active electrode in the form of a spiral-shaped with variation diameter Dc, and it was made by using copper wire with diameter Dw. In this research, we variated number of loops coil windings N as well as Dc and Dw. Ozone concentrations greater when the wire's diameter Dw and the diameter of the coil windings applied was greater. We found that impedance greater will minimize the concentration of ozone, in contrary to the greater capacitance will increase the concentration of ozone. The ozone concentrations increase with augmenting of power. Maximum power is effective at DBD reactor spiral-cylinder is on the Dc = 20 mm, Dw = 1.2 mm, and the number of coil windings N = 10 loops with the resulting concentration is greater than 20 ppm and it consumes energy of 177.60 watts


Introduction
A dielectric barrier discharge (DBD) will appear in a gas gap when an ac or rf voltage is applied to an electrode system with one or both electrodes covered by a dielectric layer. The gas-filled gap is small. Typical materials used for the dielectric layer are glass, quartz,ceramics, and polymer coatings [1][2][3][4]. Ozone can be produced by using electrical discharge in pure oxygen gas or air that was in the between two electrodes in the DBD plasma system. The factors that can affect ozone formation in general are voltage, dielectric materials, the pressure, the system configuration of the plasma reactor and a gas insert in the plasma reactor [3][4][5][6]. The main mechanism of ozone formation are ionization, recombination, dissociation and association. The reaction of ozone formation can occur in a plasma reactor has been czc  [7]. Nur et al. produced ozone by using DBD plasma and it has been implemented in the rice storage for maintaining the quality of rice [8]. Experimental study on the current-voltage characteristics for atmospheric pressure DBD has been done by Pongsathon [9]. DBDP can be approximated by an equivalent electronic circuit. The equivalent circuit is based on the model proposed by F. Massines et al [10]. This paper tries to discuss the energy consumption of ozone generators and production capabilities. Several studies that have been done related to energy consumption and the concentration of ozone generated. The ozone chamber was developed using the RLC circuit base on RLC resonance tank circuit. This model was used to determine the resonance frequency for inverter as a power supply to ozone generator [11]. Research on quantification of capacitance and power consumption [12]. Influence of electrode configuration on ozone synthesis and micro-discharge property in dielectric barrier discharge reactor has been studied [13].
2. Research Methods. Figure 1 shows a series of experiments in this study. Ozone has been produced by using Dielectric Barrier Discharge Plasma (DBDP) with spiral-cylindrical reactor configured. DBDP generated by high voltage AC voltage up to 25 kV and maximum frequency of 23 kHz. Electrical parameters of DBPP determined through a voltage divider (HV Probe DC Voltage DC max 40 kV; 28 kV AC EC code number 1010, En G1010). Electrical signal from the probe detected by an Oscilloscope GOS-653, 50 MHz. The electric current, that was generated in the reactor was measured by using a multimeter (Sunwa TRXn 360). Photo taken from experiments using a CCD camera (Creative, DV Cam).

Figure 1. Experimetal set up
The concentration of ozone generated DBDP reactor with spiral-cylindrical configuration measured using an ozone monitor (Quant Ozone "2"). Measurements were taken at applied voltage variations and multiple electrode diameter cylinders/Pyrex tube.  The reactor used in this study was Dielectric Barrier Discharge Plasma reaktor (DBDP) reactor, with wire spiral -cylinder configuration ( Figure 2). The reactor consists of an active electrode in the form of a spiral-shaped copper wire (wire diameters variation (DW) are 0.4 mm and 1.2 mm), the diameters of the wire coil windings (DC) are 9.2 mm, 15 mm, 20 mm, number of loops coil windings (N) are 10, 20, 30, 40, 50 loops. Wire spiral was inserted in a dielectric barrier was shaped pyrex tube pyrex diemeter (DP = 30 mm) and pyrex thickness (TP = 1 mm) and pyrexlength (LP = 15 cm). the outer part of the dielectric barrier will be veiled with a copper plate that serves as a passive electrode, with copper thickness (TC = 0.4 mm) and copper length (LC = 13.70 cm).

Results and Discussion
We used air as source of ozone generator. The air most constituent is nitrogen and oxygen. The air introduced into the reactor with a pump and with certain flow rate. According to Lofthus and Krupenie [14], O2 molecules have ionization and dissociation energies lower than N2 molecules. So the O2 molecule more susceptible to ionize and dissociate of than nitrogen molecules. Energy levels of molecules O2 and N2 molecules that can be found in [15] and the ionization energy of O2 molecule is 12 eV. If the O2 molecules gain energy 12 eV can ionize the O2. Because the conditions of ionized molecules in an unstable state and tends to return to its normal state (recombination), O2 + ions can capture electrons and emit an energy of 12 eV. How the same is true of N2 molecules having ionization energy of 15 eV can ionize and go back to the normal state (recombination) to emit an energy of 15 kV.

Effect of Impedance and Capacitance Against Ozone Concentration
The influence of impedance to ozone production was investigated to get the best value of the parameters for an ozone generator that constructed base on DBDP. In this study, the impedance value was obtained by calculation using equation (9).  Figure 3 for the number of wire windings (N = 50 coils), the diameter of the wire windings (DC = 20 mm) and wire diameter (DW = 0.4 mm). We found that the greater the value of the impedance then the concentration of ozone generated is getting smaller. This is because the electric field near the electrode active decline. So the process of ionization and recombination also decreased. Capacitance influence on ozone production also investigated in this study. In the DBD reactor, the electrical equivalent circuit consists of two capacitances, the capacitance of gas (Cg) and dielectric capacitance (Cd). Total capacitance can be obtained with equation 1 = 1 + 1 . The reactance value was  The effect of power consumption to produce ozone The influence of power by generator to the ozone concentration produced is shown in Figure 5. From all the reactors that tested, we select on the DBD reactor with a construction which was capable to produce large ozone concentration. Construction selected is reactor that has components such as: DW = 1.2 mm, DC = 20 mm and DP = 30 mm, LP= 150 mm. Figure 6 shows that the change in the number of windings coil (N) affect the value concentration of ozone generated. It is closely related to the electric field distribution and decomposition of ozone.
When the number of windings coil on the more active electrode electric field between the electrodes is much more uniform and almost complete in the area so that the ionization electrode is also much more intense and uniform. The concentration of ozone produced is also higher. In the figure 6, we can see that windings coil N = 50 coil spools produce ozone concentration is more high than N= 30 and 40 coil spools, with less power consumption.  Figure 7 is ozone concentration as a function of power. From the figure it can be seen that no ozone is generated for all input power. It is very influential here is the distance between the active electrode with Pyrex tube. This graph is for diameter spiral made of copper wire of 9.2 mm or 4.8 mm from the axis (radius).  So that the edge of the active electrode to a distance of 11.2 mm tube (tube radius = 15 mm). The distance is so large that the electron energy is not enough to dissociate the oxygen molecules. Furthermore, tree bodies reaction does not take place so that ozone is not formed. Results are shown in Figure 7 corresponds with previous research that has been reported [16]. Differences in diameter spiral-shaped of the active electrode give effect to the concentration of ozone generated. The larger the diameter spiral-shaped of the active electrode closer to the Pyrex, it can generate the greater the concentration of ozone.

Conclusions
Ozone concentrations greater when the wire's diameter DW and the diameter of the coil windings applied was greater. We found that impedance greater will minimize the concentration of ozone, in contrary to the greater capacitance will increase the concentration of ozone. The ozone concentrations increase with augmenting of power. Maximum power is effective at DBD reactor spiral-cylinder is on the diameter of coil winding (DC = 20 mm), diameter of wire (DW = 1.2 mm), and the number of coil windings (N = 10 loops) with the ozone concentration produced is greater than 20 ppm and it consumes energy of 177.60 watts. Differences in diameter spiral-shaped of the active electrode give effect to the concentration of ozone generated. The larger the diameter spiral-shaped of the active electrode closer to the Pyrex, it can generate the greater the ozone concentration.