Ozone Production in Coaxial DBD Using an Amplitude-Modulated AC Power Supply in Air

Abstract

ABSTRACTIn 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.