A comparative study of ozone generation using pulsed and continuous AC dielectric barrier discharges

Abstract

Summary form only given. Dielectric barrier discharges provide an effective method of industrial ozone generation. The process is usually driven by an ac power supply at a few hundred hertz, although attempts have been made to apply higher frequencies to increase the power density and ozone concentration. However, the population of low-energy electrons produced under continuous ac energization makes a large contribution to ozone dissociation and heat production, leading to an electrical ozone-conversion efficiency lower than 20%. By replacing the continuous ac excitation with a high voltage pulsed excitation, with short duration pulses, it should be possible to reduce the low energy electron population and therefore increase the electrical ozone conversion efficiency. This paper presents a comparative study of ozone generation under both pulsed and continuous ac conditions, using a specially-designed, oxygen-fed ozone generator. The pulsed voltages were generated using a self-matched transmission line and spark gap switch designed to produce 100 ns pulses. The continuous sinusoidal voltage with frequency of 2.6 kHz was obtained from a thyristor-controlled frequency inverter, together with a series resonant circuit. Experiments have been carried out to measure the discharge voltage and current waveforms under various energization modes. Optical measurements were also conducted using a photomultiplier (H10721-01) to determine the discharge mode. The corresponding ozone concentrations were measured against specific power and the ozone conversion efficiency was calculated. Results show that application of short pulsed voltage results in strong emitted light and there is no filamentary current impulses detected during the discharge, while continuous ac voltage leads to weak emitted light but short lived filamentary currents were detected. It was found that the diffuse discharge mode obtained by employing short pulsed voltage can improve the ozone generation efficiency.