【作者】 张零零；

【导师】 朱益民；

【作者基本信息】 大连海事大学 ， 环境科学与工程， 2010， 硕士

【摘要】 针-板式直流电晕放电具有能耗低,对低浓度污染物去除效率高等特点。但目前针对电晕放电电离区与迁移区内电流密度与电场分布的估算、自由基等活性物种特性等微观特性方面的研究还不多见。本实验用光学发射光谱(OES)诊断多针对板直流电晕放电电离区N2第二正带跃迁。通过对电离区内空间各点ISPB的检测,确定ISPB空间分布,分析电离区微观放电特性。利用泊松方程对多针对板直流电晕放电电场分布和电流密度进行理论分析。结合ISPB空间分布,分析电离区微观特性及其与宏观电参数的对应关系。然后,对OH进行检测,研究负电晕放电电参数(包括放电电压、放电电流、放电功率、电极间距)和相对湿度对OH特性的影响。确定宏观参数与OH微观特性之间的关系。利用正电晕流光阶段OH空间分布的数据,拟合出OH的空间分布,确定了流光放电间隙OH分布特性。得到的结论有：正辉光放电电离区ISPB先增大后减小。从电离区中层到外层,ISPB反应高能电子密度分布,逐渐减小。负辉光放电ISPB分布与正电晕一致；根据泊松方程求得放电区电场强度与电流密度的表达式。电离区电场强度随距离r先增大再减小。实验中ISPB最大值处与理论推导的电场强度最大值较一致；电离区电流密度沿针尖轴向呈减小趋势,并与ISPB在电离区中层和外层呈良好的线性关系。电离区外层离子迁移对电流形成起一定作用；迁移区内,电流强度与原点的距离无关。负电晕辉光放电,OH随电压和电流的升高而增加。单位功率OH随总功率增大而减小；电离区内OH沿针尖轴向先增大后减小。随电极间距增大,OH强度减小；流光放电,几乎整个放电间隙均可测到OH。针电极附近OH分布沿针尖径向呈“子弹状”,由内向外逐渐减小。距针电极较远处OH沿针尖径向先增大后减小；正、负电晕放电OH随相对湿度的增大均先增大后减小。应用中正、负电晕放电可选择40%-60%和40-55%的范围。更多还原

【Abstract】 DC corona discharge in the configuration of needle-plate electrode has been widely used in decomposing contaminants. It has advantages of low energy consumption and high removal efficiency. However, there is not enough study of its microscopic properties, such as current density, distribution of electric field, radicals, active species and etc.In this thesis, the emissions of N2 second positive band produced by multi-needle-to-plate DC corona discharge were detected using OES. The spectral intensity ISPB at different point was calculated by detecting the intensity ISPB in different area of the ionization region, and the distribution of ISPB was drawn accurately. The microscopic electrical properties of the ionization region were analyzed according to the trend line of the distribution of ISPB. The electric field and the current density were analyzed theoretically according to Possion equation. Thus, the relationships between microscopic and macroscopic electrical properties were analyzed. Then, the emissions of excited OH radicals were detected in multi-needle-to-plate negative corona discharge and streamer discharge. The effects of relative humidity and electrical properties in the negative corona discharge (including U, I, P and d) on excited OH radicals were investigated experimentally, and some important rules of the characteristics of OH radicals were obtained. The distribution of excited OH radicals in streamer discharge was drawn accurately according to the detected data, and the distribution characteristics of excited OH radicals were summarized.The main conclusions are as follows:The intensity of N2 second positive band firstly increases and then reduces in the ionization region. The distribution of ISPB in the middle and outer layers of the ionization region is corresponding to the density of energetic electrons, and the ISPB reduces from the middle layer to the outer layer. The distribution of ISPB in negative glow discharge is similar to that in positive glow discharge; According to Poisson equation, the expressions of the electric field intensity and the current density were deduced respectively. In the ionization region, the electric field intensity firstly increases and then reduces with the increase of r. The position of the maximum value of ISPB is consistent with that of the maximum electric field intensity obtained from theoretical analysis. The current density reduces along the needle axis, and it is linearly proportional toISPB in the middle and outer layers of the ionization region. The mobility of charged particles in the outer layers of ionization region plays a certain role in discharge current formation. The current is irrelevant to r in the migration area.With the increases of the applied voltage U and the discharge current I, the number of excited OH radical increases in negative glow discharge. The number of excited OH radical per unit power reduces with the discharge power increase. In the ionization region, the density of excited OH radical firstly increases and then reduces along the needle axis. With the space between electrodes increase, the density of excited OH radical reduces; In streamer discharge, the emission spectrum of excited OH radical can be detected almost in whole discharge gap. The shape of the region around the needlepoint looks like a bullet, and the density of excited OH radical reduces with the r increase. The distribution of OH radical farther away from the needlepoint firstly increases and then reduces along the radius direction; Both in positive and negative corona discharges, the number of excited OH radical firstly increases and then reduces with the relative humidity increase. In practical application, the better RH ranges for positive and negative corona discharges are 40-60% and 40-55% respectively.更多还原