Dynamic Simulation Of Ozone Generation In Pulsed Dielectric Barrier Discharge

As a powerful oxdant and environmentally friendly, ozone has been widely used in various applications. However, the low ozone producing efficiency has hindered a number of ozone applications. Therefore, reducing energy consumption of ozone generation has been a large chanllenge for domestic and international scholars. In this paper, a numerical model of parallel-plate pulsed dielectric barrier discharge in puer oxygen or air is developed to investigate the spatial-temporal distributions of species and streamer for ozone generation. This work woud provide a reference for increasing ozone producing efficiency and purchasing experimental facilities. Results are as follow:(1) The simplified computational domain with appropriate meshes is based on the parallel-plate dielectric barrier discharge ozone generator. The electron energy equation is added into govering equations. The related to important reactions about ozone generation in pure oxygen or air are selected into the numerical model, respectively. The validity of model is compared between numerical and experimental ozone concentration as a function of pulse peak voltage.(2) The temporal evolutions of each species density are shown at pulse peak voltage of 9k V. For pure oxygen discharge, the primary positive ion, negative ion and excited species are O2+, O3- and O2(1?+g), respectively. And the increase of pulse rise rate is favorable for ozone generation. For air discharge, the domaint positive ion, negative ion and excited species are O2+, O3- and O2(1?g), respectively. Ozone density reaches a peak value of about 2.38×1021m-3. The largest species density among nitrogen oxides is N2 O. The results are compared with other papers that can testify the validity of model.(3) The charged species distributions are presented at the time of electron avalanche transforming into streamer. Electron density increases nearly exponentially in the anode region. Other charged species have similar spatial density distributions to that of electron. But there is a violent oscillation because electron needs relaxation time to obtain enough energy again after colliding with heavy species.(4) With the development of electron avalanche, streamer emerges from the anode and towards the cathode. The average streamer propagation velocity is 5.56×104m/s in pure oxygen, and 5.26×104m/s in air.(5) Density distributions of main species are obtained during streamer propagation. For pure oxygen discharge, density distributions of e, O2+, O and O3 in discharge space are obtained, which of them increase in streamer head during streamer propagation. The reactions of ionization and excitation are intensified because of the streamer. The densities of O2+, O and O3 are increased in whole gas gap. For air discharge, density distributions of e, O2+, N2+, O, O3, N2(A3?) and N2 O are obtained, which of them are developed during streamer propagation. At the end of streamer propagation, the maximum densities of e and N2+ appear in streamer head. For O2+, O, O3, N2(A3?) and N2 O, their peak densities exist in the vicinity of anode.