Effect of Dielectric Barrier Materials on Conversion Characteristics of Low Pressure CO2 Dielectric Barrier Discharge

Dielectric barrier discharge (DBD) plasma can generate a large number of charged particles and active radicals, with the advantages of high efficiency, low consumption, high controllability and long service life, which demonstrates good application potential in in-situ conversion of CO2 resources. Considering the special CO2 atmosphere with high concentration and low pressure on Mars, the kHz sinusoidal voltage was used to drive DBD, and the effect of different dielectric barrier materials on CO2 discharge conversion characteristics were investigated experimentally, so as to explore the influence mechanism of the type of dielectric barrier materials on the CO2 conversion effect during DBD. The results show that dielectric barriers arc quartz glass, epoxy resin, aluminum nitride, alumina, and zirconia (the relative dielectric constants arc 4.7, 6. 6, 9. 8, 10. 2 and 37. 1, respectively). The yield of O2 in the discharge product steadily rises, and is much higher than other materials when using zirconia as a barrier dielectric. The influence mechanism of the relative dielectric constant and secondary electron emission coefficient of the barrier dielectric on the CO2 conversion was examined by numerical simulation analysis. When secondary electrons emission coefficient is fixed and the relative dielectric constant of the barrier dielectric rises, several fundamental parameters arc increased, including the average electric field in the gas gap, the densities of electrons generated by discharge and CO2, and the maintaining time above the half-peak of the densities, as well as the primary reaction rate of O2 formation, thus leading to a rise in O2 production. The fixed relative dielectric constant in combination with an increase in the secondary electron emission coefficient of the dielectric barrier can lower the average electric field strength and electron temperature in the gap, and increase the average electron density. Therefore, higher electron density and lower electron temperature arc conducive to the recombination and decomposition reaction of electrons and ions, and promote the formation of O2. © 2023 Science Press. All rights reserved.