Study On The Generation Method And Efficacy Of Hybrid Surface/Volume DBD

Dielectric barrier discharge (DBD) is a special discharge types in which a dielectric is inserted between discharge electrodes, DBD device has many configuration for generation of volume discharge, surface discharge, etc. Configuration of DBD devices affect the discharge uniformity, plasma characteristics, and spatial distribution of active species, etc. The initiation voltage of surface DBD plasma is low, but the discharge plasma is generated mainly along the dielectric surface. The discharge area of volume DBD is larger because it is generated in high voltage electrode and grounded electrode, but the initiation voltage is higher. In this paper a novel hybrid surface/volume DBD discharge device is designed. The hybrid DBD device is supplied with one power supply, and surface discharge and volume discharge can be produced at the same through changing the arrangement of discharge electrodes, which combines the advantages of the two kinds of forms of discharge plasma. The novel electrode configuration can enlarge the spatial distribution of plasma and increase the production of active species. The main experimental results are as follows:1. For different high voltage electrode configurations including the needle array electrode, the parallel metal strip array and plate electrode, the highest energy efficiency (20.05 g/kW·h) of ozone generation is obtained by the parallel metal strip, followed by the needle array electrode with a maximum of 13.86 g/kW·h, and plate electrode with a maximum of 14.65 g/kW·h. Moreover, the energy efficiency of ozone generation first increased with the applied voltage to reach a peak, and then decrease with the applied voltage.2. Comparing two kinds of hybrid surface/volume DBD devices, the discharge power and the discharge intensity of hybrid DBD device sharing the same high voltage electrode is greater than that of sharing the same grounded electrode under the same ac voltage peak. Compared with surface DBD device and volume DBD device, the discharge intensity of hybrid surface/volume DBD device is more intense, and more active species is produced. The highest energy efficiency (44.15 g/kW·h) of ozone generation is obtained by the hybrid DBD device, followed by volume DBD device with a maximum of 40 g/kW·h, and surface DBD device with a maximum of 21.94 g/kW. h.3. For hybrid surface/volume DBD device discharge gap and dielectric thickness influence the discharge intensity and active species production. Under the ac voltage peak 16 kV, the discharge power of hybrid DBD device decreases and the generated ozone concentration reduces from 1.3 mg/L to 1.23 mg/L, as the air gap increases from 1.6 mm to 4.4 mm. The discharge power of hybrid DBD device decreases and the generated ozone concentration reduces from 1.23 mg/L to 1.18 mg/L, as the dielectric thickness increases from 2.2 mm to 5.0 mm.4. Decolorization experiments of dye wastewater show that the decolorization efficiency of AO7 using hybrid DBD device is higher than that using the surface DBD device and volume DBD device. The decolorization of AO7 using hybrid DBD device reaches 89.7%, higher than that of 81.9% using the surface DBD device and that of 67.9% using volume DBD device with the processing time 60 min, the results demonstrate more reactive species can be produced by the hybrid DBD device.