Analysis of ozone generation in a planar atmospheric pressure air dielectric barrier discharge reactor

Abstract

Abstract This work investigates O3 production in a planar atmospheric pressure air dielectric barrier discharge reactor numerically and experimentally. The surface temperature of the reactor is measured by an infrared (IR) thermal imager, and the O3 densities of cases in the reactive zone are measured by ultraviolet absorption spectroscopy. The 1.5D plasma fluid model (PFM) with transverse convection is employed to capture the average properties of a single microdischarge (MD) generated in the reactor. The concept of equivalent reaction is proposed to calculate spatial-cyclic average species sources obtained by the 1.5D PFM and provided to the chemical model of a 3D gas flow model (GFM) for obtaining density distributions of reactive species generated by MDs in the reactive zone. The simulated temperature distribution of the reactor surface is validated by that measured with the IR thermal imager since the gas temperature was reported as a critical discharge parameter for O3 generation. The simulated O3 densities show the same trend as the flow rate changes, which demonstrates the proposed model captures the average discharge dynamics in different operating conditions. In the 1.5D PFM, the simulated results show that the O3 molecules produced in the case of 4 SLM are much more than those produced in the case of 1 SLM though the O atoms produced in the case of 1 SLM are around 20% more than those produced in the case of 4 SLM. In the case of 1 SLM, more than 48% of O3 molecular generated are destructed, while only around 14% of O3 molecules are destructed in the case of 4 SLM. The analysis shows that around 73% of O atoms generated in the 1.5D PFM are consumed in the formation of O3 molecules in the case of 4 SLM, while only 18% of O atoms generated in the case of 1 SLM are consumed in the formation of O3 molecules. In the 3D GFM, the O3 destructed is around 24% of that destructed in the 1.5D PFM in the case of 4 SLM due to the oxidation reaction of NO, while only 11% of O3 molecules destructed as that destructed in the 1.5D PFM in the case of 1 SLM. The amounts of O3 molecules generated in the 3D GFM are minor if they are compared with those generated in the 1.5D PFM in all cases. The overall O3 yield efficiency reaches 97 g kWh−1 with the O3 concentration increasing up to 2700 ppm in the case of 4 SLM, while the O3 yield efficiency decreases to 10 g kWh−1 and O3 concentration drops to 1400 ppm in the case of 1 SLM.