荷电喷雾协同低温等离子体净化汽车尾气的实验研究

发布时间：2018-08-11 12:28

【摘要】：雾霾已经成为当前我国社会最关切的环境问题之一。在许多大中型城市中,随着汽车保有量的不断增加,汽车排放逐渐成为导致雾霾的重要因素,发展新型高效的汽车尾气净化技术对于降低污染、保护环境具有重要意义。荷电喷雾与低温等离子体作为防治颗粒物与有害气体污染的新技术,具有高效、节能等优点,在汽车尾气细颗粒物以及有害气体的脱除和控制等方面的应用前景十分广阔。荷电喷雾协同低温等离子体净化汽车尾气的机制十分复杂,开展荷电喷雾协同低温等离子体净化汽车尾气特性的研究是发展高效尾气净化技术的基础,具有重要的研究价值。本文结合荷电喷雾与低温等离子体技术,搭建了柴油机尾气净化实验系统,对静电喷雾的荷电特性、脱除细颗粒物的特性以及柴油机尾气的净化效果开展了实验研究工作,为荷电喷雾协同低温等离子尾气净化技术的发展与应用奠定了实验基础,主要研究如下:1.针对柴油机排气系统的结构特点,设计并制作了环状感应荷电喷头,并对静电喷雾的荷电特性以及喷雾特性进行了测量和分析,结果表明:液滴的荷质比随荷电电压的增大而先增大后减小;液滴荷电效果与雾化压力有关,且存在荷电效果最佳的雾化压力值;通过对喷雾荷电可以减小喷雾中液滴的粒径,且液滴粒径越大,荷电电压对其粒径的影响越强。2.基于柴油机尾气的排气速度和尾气颗粒粒径的分布范围,设计并搭建了荷电喷雾除尘实验系统;利用柴油燃烧产生的细颗粒物来模拟柴油机尾气颗粒进行预实验,探究了荷电喷雾脱除模拟尾气颗粒的特性,研究结果表明:通过对液滴荷电,装置除尘效率最高可提升27.5%,是液滴非荷电状态下除尘效率的3~4倍;单独对颗粒荷电时装置的除尘效率要高于单独对液滴荷电时的除尘效率,且当二者同时荷相反电荷时,装置除尘效率最高可达92.3%。3.对荷电喷雾协同低温等离子体净化柴油机尾气的效果进行了实验研究,研究结果表明:荷电喷雾的除尘效率随喷雾流量的增大而增大,在中低转速下,喷雾流量的提高对装置除尘效率的提升效果较为明显;NO、CO、HC三种有害气体的净化效率均随着发动机转速的提高而下降,其中CO的下降幅度最大,达40.2%,HC的下降幅度最小,为11.7%。4.通过实验测量,分析了尾气加湿对柴油机尾气颗粒物脱除以及有害气体净化的影响,研究发现:尾气加湿可以提高装置对颗粒物的净化效率,尤其是在中高转速下,效率提升可达17%;尾气加湿可以促进CO、NO的转化,但对HC的净化效率影响不大,当荷电电压较高时,对NO的促进作用会随着电压的进一步增大而逐渐减弱。
[Abstract]:Haze has become one of the most concerned environmental problems in China. In many large and medium-sized cities, with the continuous increase of vehicle ownership, vehicle emissions have gradually become an important factor leading to haze. It is of great significance to develop new and efficient vehicle exhaust purification technology to reduce pollution and protect the environment. As a new technology to prevent and control the pollution of particulates and harmful gases, charged electrospray and low temperature plasma have the advantages of high efficiency and energy saving, and have a broad application prospect in the field of removal and control of fine particulates and harmful gases from automobile exhaust. The mechanism of electrospray combined with low temperature plasma for purifying automobile tail gas is very complicated. It is the foundation of developing efficient exhaust gas purification technology to study the characteristics of charged spray and low temperature plasma for purifying automobile exhaust gas, which has important research value. Combined with charged spray and low temperature plasma technology, a diesel exhaust purification experiment system was set up in this paper. The characteristics of electrostatic spray, the characteristics of removing fine particles and the purifying effect of diesel exhaust were studied experimentally. It lays an experimental foundation for the development and application of the combined low temperature plasma tail gas purification technology, the main research is as follows: 1. According to the structure characteristics of diesel engine exhaust system, the ring induction charge injection head is designed and manufactured, and the charge and spray characteristics of electrostatic spray are measured and analyzed. The results show that the charge mass ratio of the droplet increases first and then decreases with the increase of the charged voltage, the charge effect of the droplet is related to the atomization pressure and there is the best atomization pressure value of the charge effect, and the particle size of the droplet in the spray can be reduced by the spray charge. The larger the droplet size is, the stronger the effect of charged voltage on the particle size is. 2. Based on the exhaust velocity of diesel engine exhaust gas and the distribution range of exhaust gas particle size, the experimental system of charged electric spray dust removal was designed and built. The characteristics of removing simulated tail gas particles by charged spray are investigated. The results show that the dust removal efficiency of the device can be raised by 27.5g by charging the droplet, which is 3 ~ 4 times of the dedusting efficiency under the non-charged state of the droplet. The dedusting efficiency of the device is higher than that of the liquid droplet charged alone, and when the two charge the opposite charge at the same time, the dedusting efficiency of the device can reach 92.3%. 3. The effect of charged spray and low temperature plasma on purifying diesel engine exhaust gas is studied experimentally. The results show that the dust removal efficiency of charged spray increases with the increase of spray flow rate, and at low speed and low speed, the dedusting efficiency increases with the increase of spray flow rate. With the increase of spray flow rate, the cleaning efficiency of the three harmful gases decreased with the increase of engine speed, and the decrease of CO was the biggest, and the decrease of 40.2% HC was the smallest, which was 11.7.4.The effect of increasing the spray flow rate on the dedusting efficiency of the plant was obvious, and the purification efficiency of the three harmful gases decreased with the increase of engine speed. The effects of tail gas humidification on the removal of particulate matter from diesel engine exhaust and the purification of harmful gas are analyzed. It is found that the humidification of exhaust gas can improve the purification efficiency of particulate matter, especially at medium and high speed. The humidification of tail gas can promote the conversion of CON no, but it has little effect on the purification efficiency of HC. When the charge voltage is high, the promotion of no will be weakened with the further increase of the voltage.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X734.2

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