Multi-hollow surface dielectric barrier discharge: an ozone generator with flexible performance and supreme efficiency

Abstract

This contribution investigates the effects of duty cycle and mass flow of synthetic air and oxygen on the efficiency of ozone generation in multi-hollow surface dielectric barrier discharge (MSDBD). It discloses that the efficiency of ozone generation in MSDBD is significantly higher compared with standard coplanar DBD, surface DBD and volume DBDs. Ozone production yield reached 205.5 ± 29.1 g (kW h)−1 (40% duty cycle, 8 slm) and 413.91 ± 58.7 g (kW h)−1 (100% duty cycle, 8 slm) at an energy cost of 8.7 and 4.3 eV/molecule for synthetic air and oxygen, respectively. Such high ozone yields arose out of the intrinsic characteristics of MSDBD ceramics, which were efficiently cooled by the flow of the working gas. The amplitude modulation of low-frequency 5 kHz high-voltage sine waveforms facilitates controlled O3 production at a nearly constant rate of yield. Since the correct evaluation of ozone production yield requires precise determination of the discharge power, the concentration of ozone and working gas-flow, considerable attention was paid to measurements of these parameters. It is confirmed and experimentally demonstrated herein that correct determination of discharge power lies with Lissajous figure methods, while the determination of power through the direct integration of product u(t)i(t), where i(t) is measured by Pearson current probe, leads to systematically lower values of calculated power with consequent overestimation of the ozone production yield. The correct determination of discharge power is clearly the key to the proper calculation of ozone production yield and efficiency. Under the DBD discharge conditions presented herein, ozone production yield and efficiency achieved figures as high as 19.5% and 35.2% of theoretical limits recently established for air and oxygen, respectively.