Study On Temperature Field Of Microchannel And Influencing Factors In Ozone Generation

With the wide application of ozone in industrial production and daily life,the demand for ozone is increasing,which drives the process of industrial production of ozone.Because of the low efficiency of ozone production,its application and promotion are restricted.In the process of ozone formation,the synthesis of O and O₃mainly takes place in the microchannels formed by streamer breakdown.More and more attention has been paid to exploring the flow field changes in microchannels and the influencing factors of ozone synthesis in surface dielectric barrier discharge.In this paper,on the one hand the variation of temperature field in discharge chamber with single microchannel,double microchannel and 27 microchannel simultaneously discharging and microchannel hysteresis discharging is simulated and studied.The range of the distance between adjacent microchannels and the reference range of the inlet gas velocity and the influence of the hysteresis time on the temperature field are obtained.On the other hand the factors of ozone synthesis characteristics in surface dielectric barrier discharge（DBD）were also studied experimentally,including the effects of discharge voltage,discharge frequency,inlet air flow rate and inlet direction on the ozone concentration and ozone yield,respectively.The main conclusions are as follows:（1）The simulation results show that the velocity of all heat carrier particles in a single microchannel is not uniform.When most of the high temperature（>400K）heat carriers reach the lower plate,the time required for the particles to reach the lower plate is 2.4 times than the time required for the uniform heat carrier particles to reach the lower plate.The time required for the streamer to develop to the formation is 2.4 ns.At this time,the region near the lower plate of the microchannel decays along the direction of the inlet gas flow.The intersection area between two microchannels affects the whole temperature field distribution.The distance between two microchannels is reduced by half.The temperature field in the intersection area begins to overlap earlier than 0.2ns.The increase of the distance between microchannels will weaken the temperature field overlap between microchannels in the intersection area,thus reducing the degree of temperature field interaction between microchannels,and determining the adjacent distance between microchannels is 0.5L-L,L=0.185mm.（2）The distribution of temperature field and velocity field along the direction of intake gas flow and vertical intake gas flow in the middle section of 27microchannels was studied,and the heat transfer enhancement was obtained through the flow of velocity field around different regions.The influence of the range of flow velocity on temperature field was studied.The range of flow velocity is 0.1m/s-0.2m/s,which is more meaningful to study.（3）The variation of temperature field in adjacent microchannels with lag discharge time ranging from 0.2ns to 2.3ns is studied.When the time interval is 1.2 ns,the streamer of the lagging channel develops to 1.2 ns,which has a great influence on the temperature of the first discharge microchannel,and the average temperature is the lowest in the whole time period.When the distance between adjacent microchannels is halved,the temperature of the microchannel with lagging discharge time decreases from linear to convex arc distribution.（4）In the experimental study,the voltage is 5KV,the frequency is 6Hz and the gas flow rate is 1 L/min-2 L/min,which is beneficial to obtain higher ozone concentration and ozone yield at the same time.The changed inlet direction is beneficial to ozone synthesis.