The Study On Mechanism And Monitoring Of Ozone Generation Under Corona Discharge

With the continuous development of economy and society,environmental problems are becoming more and more prominent.The quantity of indoor air has been more and more widely concerned in recent years.Low-temperature plasma technology in the field of indoor air purification has attracted much attention in recent years,because its simplicity,convenience and low cost.Coming with it is the problem of ozone generated by corona discharge.When the ozone concentration in the environment reaches a certain level,it will have a series of negative impacts on the human body.Therefore,the study of the mechanism of ozone production in corona discharge and the detection of ozone in the process of discharge is of great importance.First of all,in this paper,the fluid-chemical hybrid model is established.The fluid model is used to describe the macro-law of corona discharge,while the chemical reaction model is to solve the process of particle formation and extinction in discharge.By coupling the Boltzmann equation,the Electron Energy Distribution on Function(EEDF)is solved based on two terms approximation method.The main microscopic processes of ozone generation and decomposition during corona discharge are analyzed.Secondly,through the established hybrid simulation model,the corona discharge under structure of line plate at room temperature and atmospheric pressure is numerically analyzed.The single pulse current characteristics in the process of positive and negative corona discharge are compared.The distribution of electric field of positive corona discharge is analyzed,and the trend of "pushing" of the wire electrode towards the earth electrode is presented.The electrons in the negative corona discharge are generated near the inline electrode,and filled with the whole discharge gap through the development.The maximum ozone generation rate in negative discharge is nearly an order of magnitude higher than the positive corona at the same voltage.After a pulse current the ozone concentration is presented,ozone is mainly concentrated near the line electrode under positive polarity conditions.Under negative corona conditions though ozone has the maximum density near the line electrode.It also has a higher concentration during the entire discharge gap,and this distribution trend is more obvious with the increase of voltage level.Thirdly,the absorption cross-section of ozone is studied.The standard absorption crosssection under laboratory conditions is compared with the standard database,and the feasibility of laboratory measurement of ozone is verified.A set of ozone detection platform is set up and the system components are introduced in detail.The system’s maximum detection limit of 516 ppm and the minimum detection limit of 0.31 ppm are given.The signal characteristics of noise are removed by Savitzky-Golay filtering,by using Ultra Violet absorption method and Differential Optical Absorption Spectroscopy method,in which the ozone concentration is reflected in the range of 250-265 nm.It comes out that the trend of the two detection results was consistent,but the results had some difference.Compared with the high sensitivity of Ultra Violet absorption method,the Differential Optical Absorption Spectroscopy method is strong anti-interference.And meanwhile,the on-line detection of ozone concentration is realized through the procedure.Finally,the device of corona discharge with the structure of wire plate is designed.The discharge characteristics of the wire plate under positive and negative discharge conditions are analyzed,the discharge phenomena and current waveforms under these two conditions are compared.Besides,the ozone generation under the positive and negative corona is studied on the basis of the laboratory ozone detection platform.The result is that the generation of ozone is linearly related to the current when the current small,and that the ozone concentration in the negative corona is 5 times as much as that in the positive with same current.Meanwhile,the effect of other factors on ozone concentration is conclude in this paper,the ozone concentration is linearly related to the reciprocal of gas flow,the discharge material does not affect the voltage current characteristics but affects the ozone concentration,and the effect in the positive corona is more obvious,besides,the increase of air humidity will reduce ozone production.