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The oxidation of ozone is very strong, and the products of oxidative decomposition will not cause secondary pollution, so the ozone has become widely used. Dielectric barrier discharge (DBD) is the main method of ozone generation. In recent years, the addition of outfield in the DBD is used to improve ozone generation. In this paper, a needle-plate DBD ozone generator with magnetic field enhanced was designed and manufactured. The authors found the magnetic field could significantly increase the number and amplitude of current pulses, discharge current and the discharge power. The magnetic field did not change the initial discharge voltage. With the discharge voltage increased, the enhancement of magnetic field on ozone concentration was more obvious while on ozone yield was very small. The maximum increment of ozone concentration was 35.4%. With the discharge frequency increased, the magnetic field had a more positive impact on the ozone concentration. And with the same gas flow rate increased, the ozone concentration was increased by the magnetic field. Keeping the SIE constant, the ozone concentration and ozone yield at higher discharge frequency was lower than those at lower discharge frequency. With the increase of SIE, the enhancement effect of magnetic field on ozone concentration would increase. [ABSTRACT FROM AUTHOR]

In this study, a traditional tubular reactor and an amplitude-modulated AC power supply are employed to develop a unique practical ozone generator with a widely adjustable ozone concentration and simultaneously a constant ozone yield. The amplitude-modulated AC high-voltage waveform driving the discharge consists of the TON (burst of four consecutive AC cycles) and TOFF periods. The characteristics of the ozone generation in air were experimentally investigated at different energy densities, duty cycles and air flow rates, as well as cooling conditions and frequencies. The experimental results show that a unique ozone generator has an almost constant ozone yield of 51.68 ± 2.97 g/kWh in the energy density range of 50–350 kJ/m3, while a wide range of ozone concentration and output can be developed through changing the applied voltage amplitude. A higher ozone yield of can be achieved by decreasing the duty cycle and increasing gas flow rate, while higher ozone concentration can be easily achieved by changing air flow rate. The maximum ozone yield of 92 g/kWh is achieved. In contrast to only a single AC cycle in one complete TON period, changing duty cycle for a consecutive AC cycles in one complete TON period cannot be employed to develop a unique ozone generator with a widely adjustable ozone concentration and simultaneously a constant ozone yield because of different Lissajous figures, discharge energies, positive peaks, negative peaks and their differences for each AC cycle. In addition, the total capacitance of the reactor is not only independent of energy density, duty cycle and cooling condition, but also of AC frequency. A higher AC frequency of the applied high-voltage waveforms leads to a lower dielectric capacitance while increasing gap capacitance. [ABSTRACT FROM AUTHOR]

A homogenous chemical kinetic model consisting of 21 species and 118 reactions is applied to investigate energy conversion and its temperature dependence in ozone generator fed by synthetic air. The portion of electric energy converted into reaction heat, gas heating and heat loss to surroundings (by convection) in terms of the total electric energy input, the conversion ratios ηreaction, ηgas, and ηloss, are obtained. The detailed reaction pathway including the degree of transformation among species for ozone production is also obtained via simulation of the reaction kinetics. In addition, sensitivity analysis and rate-of-production analysis for the three foremost species O3, O, and N2(A) are performed to understand quantitatively the temperature dependence of sensitivity coefficient and production rate for each individual reaction. ηreaction shows a steep rise at low specific energy, but then suffers a gradual decrease at high specific energy. ηloss has a contrary behavior. And ηgas increases steadily with the increase of specific energy. The ηreaction peak of 35.1% is achieved at specific energy of 0.17 J/cm3 at the conditions under investigation. Additionally, inlet gas temperature only has a small effect on energy conversion. Moreover, high gas temperature in discharge gap is confirmed to be not favorable for ozone formation from the view of reaction heat. The sensitivity coefficients of reactions with electron participation are sensitive to gas temperature. O+O2+O2→O2+O3 and O+O2+N2→N2+O3 account for about 70% and 30% of generated ozone respectively at the given conditions. And e+O2→e+O+O, N2(A)+O2→N2O+O, and N2(A)+O2→O+O+N2 are responsible for about 51.3%, 14.7%, and 32.0% of oxygen atom, respectively. [ABSTRACT FROM AUTHOR]

A detailed reaction kinetic model consisting of 10 species and 63 reactions is developed to investigate the energy conversion and temperature dependence in an ozone generator using oxygen pulsed discharge. The energy conversion ratios of total electric energy converted into reaction heat, heat carried by gas and heat loss to ambient, namelyηreaction, ηgasandηloss, are obtained for the first time. The ratio of reaction heatηreactiondecreases substantially with increasing specific energy and inlet gas temperature, which represents how much energy is utilized effectively to synthesize ozone. Correspondingly,ηlossandηgasincrease gradually.ηreactiondeclines from 55.4% to 27.7% at inlet gas temperature of 298 K when specific energy changes from 0.06 J/cm3to 0.78 J/cm3. The detailed reaction pathway including the degree of transformation among species for ozone formation is also obtained via kinetics simulation. Meanwhile, sensitivity analysis and rate-of-production analysis for the four most important species O3, O, O(1D) and O2(b1∑) obtained from the reaction pathway are executed to understand quantitatively the temperature dependence of sensitivity coefficient and production rate for each individual reaction. The production rate of ozone via the most important ozone generation reaction O+O2+O2 = > O3+O2increases linearly with the increase of gas temperature, as well as the destruction rates of ozone via the most important ozone decomposition reactions O3+O3 = > O2+O2+O2and O3 + O = > O2(b1∑)+O2. [ABSTRACT FROM AUTHOR]

This article investigates the effect of inert gas addition He, Ar, Kr, and Xe on gas breakdown voltage within a dielectric barrier discharge reactor with air feed gas. The density-normalized effective ionization coefficients are calculated for inert gas/air mixtures; the critical reduced field is then obtained where the electron ionization exactly balances the attachment. Adding inert gases would lead to the decreasing critical reduced field strength due to the enhancement of effective ionization coefficient. In addition, inert gas additions have shown to reduce the breakdown voltage. Moreover the calculated breakdown voltage values and the experimental data are plotted for the sake of comparison and results show that calculated results are in agreement with the experimental values. Parametric studies offer substantial insight in plasma physics, as well as in ozone generation applications. [ABSTRACT FROM AUTHOR]

This experiment studies the effect of inert gases He, Ar, Kr and Xe on ozone generation within a dielectric barrier discharge reactor fed by dry air. The results show that increasing inert gas content leads to a lower applied voltage, discharge power and reduced field. Although the addition of inert gas would lead to a lower reduced field, however, the electron energy distribution function still shifts to the right. The electron density increases slightly at first and then decreases steadily with increasing Xe content, but it decreases monotonically with increasing content of He, Ar and Kr. With regard to dry air/Kr and air/Xe mixtures, ozone concentration and ozone yield show a slight initial increase, followed by a steady decrease forand, which are favorable for ozone production through the Penning dissociation of O2due to their lower excitation energy. [ABSTRACT FROM AUTHOR]

This paper reports the results of an experimental study of effect of SF6 on ozone generation within a Dielectric Barrier Discharge (DBD) fed by both pure oxygen and dry air. The chemical reaction mechanisms relevant to the process of ozone generation (and destruction) are discussed. The experimental results show the oxygen source should avoid the presence of SF6 but the addition of a small amount of SF6 in an air discharge can improve ozone concentration and ozone produce efficiency. [ABSTRACT FROM AUTHOR]

The influence of silica catalyst on ozone generation in oxygen-fed dielectric barrier discharge is investigated experimentally. The load of a silica film on ceramic plate surface does not evidentially change the filamentary discharge pattern, meanwhile, both ozone concentration and ozone yield increase owing to the catalysis of silica. The catalysis that is related to adsorption will prolong the retention time of active species and enhance surface reactions. The specific surface area of 16.31 m2/g of the dielectric with a silica film is about 8 times larger than that of the dielectric without a silica film. Meanwhile, there are some hydroxyl groups on the former but nothing on the latter. When the thickness of the silica film is 940 nm, ozone concentration and ozone yield can maximally increase by about 7.1% and 72.6% at 5 kHz and 1 slpm, respectively. However, the silica film cannot be too high because it will be not beneficial for ozone generation due to the decreasing thermal conductivity of the loaded dielectric. • Silica film has positive effect on ozone generation and no impact on discharge. • Adsorption is the main reason for the catalysis of silica film for ozone generation. • Active species retention time is prolonged and surface reactions are enhanced. • Silica film has not only larger specific surface area but also more hydroxyl groups. • Silica film thickness needs to be optimized due to changing thermal conductivity. [ABSTRACT FROM AUTHOR]