The Optical Measurement Of Oh Radicals In The Process Of Pulsed Corona Discharge

The research of the measurement of the OH radicals in the process of pulsed corona discharge with emission spectrum system and planar laser induced fluorescence (PLIF)-ICCD imaging joint system was introduced in this dissertation, with the purpose for studying the mechanism of the generation of OH radicals, and the disappearance of them through chemical and physical reactions. The key status of OH radicals in the process of simultaneous removal of mutli-pollutants by pulsed corona discharge, and the effects that various factors had on the generation of OH radicals were also studied, to know the principles how the generation of OH radicals changed with according to different factors, and to support the research of the technology for the simultaneous removal of multi-pollutants by pulsed corona discharge as references.The main research contents are presented below:1. The velocity distribution of gases in the discharge reactor had been studied with the method of simulation by Fluent, and a reactor with better flow state of gas in it had been designed. The gas went in the reactor through the lateral of the gas-mixing area and went out through the lateral of the end side of the reactor, considerating the light request of the PLIF system, and an air ventilation board should better be set between the gas-mixing area and the discharge area. The velocity of the air stream changed a little more rapidly but not in a large extent in the discharging area in the central reactor.2. The OH radicals in the processes of pulsed corona discharge with Air, N2 or Ar as a background gas were measured by emission spectroscopy, and the effects that different peak voltages, different discharge frequencies and different relative humidity in background gases had on the generation of OH radicals were studied, as well as the distributions of OH radicals in the discharge field. Experiments'results proved:the relative concentration of OH radicals grew as the peak voltages and frequencies of pulsed corona discharge grew; the relative concentration showed different behaviors in different background gases when the relative humidity changed, and the principle was:when the relative humidity in background gases increased, the relative concentration also increased in the air, but increased at first then decreased in N2, and decreased at fist then increased in Ar; The relative concentration of OH radicals decreased as the distance grew between the center axes of the optical lens and the wire-electrode. In the end the concentration distributions of OH radicals in the air when SO2 and NO existed were investigated and few OH radicals were found.3. The design and construction of the PLIF-ICCD joint system had been consummated. The 2D distributions of OH radicals were detected when the peak values of voltages in pulsed corona discharge and gas humidity changed in different backgrounds such as air, N2 and Ar, as well as the principle of the generation of OH radicals when the amount of O2 changed, and OH radicals were also measured when SO2 and NO existed. We had got the 2D distributions of OH radicals in different situations and had validated the influence of pulsed corona discharge voltages and gas humidity on the process of generation of OH radicals, and had proved that the number of OH radicals decreased when there were more O2 molecules. We also found SO2 molecules were largely excitated when laser irradiation came, which affected the measurement result. OH radicals cannot be easily detected by PLIF system too, however, there was also a trend of decrease when the amount of NO increased.The present research about OH radicals mainly controls the air stream bring H2O with inert gases as a background, but seldom focuses on the accurate supervision and control of humidity, as well as the distribution measurement based on accurate space scales, so both of the two aspects were paid attention in this dissertation. OH radicals generated when SO2 and NO existed were also detected as an attempt. All the works above provided some reference to the research on removing mulit-pollutants simultaneously by pulsed corona discharge. Besides, the optical measurement of radical were mostly carried with emission spectrum method, but we creatively used the PLIF-ICCD imaging joint system to get to the same destination, and showed its unique predominance. The technique of PLIF-ICCD imaging system had been managed through the design and construction of the joint system, as a research base of further works.