Experimental Study On NO Removal With Dielectric Barrier Discharge (DBD) Plasma At Atmospheric Pressure

Nitrous oxides as one of the main air pollutants can cause acid rain and photochemistry fog,endanger the humanity as well as ecological environment.Now, how to control and treat these pollutions has become one of the most important issues on environment protection.For their particular advantages in the cleaning of air pollution,such as high removal efficiency and low energy consumption,DBD (dielectric barrier discharge) plasma technologies have gradually attracted more and more attentions.A coaxial DBD reactor system which can be operated safely is designed and built. With the DBD reactor the influences on the NO removal effects of different factors including the gas flow rate,initial NO concentration,applied voltage are systematically studied.The experiment results indicate that NO can be highly efficiently removed by dielectric barrier discharges on proper conditions.The NO removal efficiency will decrease with the increasing of the gas flow rate and the initial NO concentration,and will increase with the increasing of the applied voltage when fixing other reflect experiment parameters.It is indicated that the NO removal efficiency is depended on the average consumption energy of each NO molecule.The larger average consumption energy density,the higher NO removal efficiency.The relationships about flux,NO initial concentration and applied voltage with the NO₂ generation efficiency have been studied.It is shown from the experimental result that NO₂ generation efficiency will increase with the increasing of the gas flow rate and initial NO concentration,and decrease with the increasing of the applied voltage while fixing other experiment parameters.Say other words,when the average consumption energy density become high,the NO₂ generation efficiency will decline, sometimes even become negative.The influences on the NO removal effect of different factors including the diameter of the central electrode,and the length of the discharge area are studied also.The experimental results indicate that there should be an optimal value for the diameter of the central electrode to achieve the best NO removal efficiency when other conditions are given.The NO removal efficiency can be improved with increasing the length of the discharge area.In addition,the NO₂ generation efficiency is not strongly related to the discharge area length and the central electrode diameter.It has been compared the different influence about the applied voltage,gas flux and the NO initial concentration to the NO removal efficiency and the NO₂ generation efficiency when using N₂ and A_r as the background gas respectively.It is indicated that the NO₂ generation efficiency in A_r plasma is higher than which in N₂ plasma. When the average NO consumption energy density high,the NO removal efficiency in A_r plasma will lower than which in N₂ plasma.And there will be a contrary result when the average NO consumption energy density is low.