Experimental Study On Automobile Exhaust Purification Under The Synergistic Effect Of Charged Spray And Non-thermal Plasma

Haze has been one of the most concerned problems of the whole society.Among large and medium-sized cities,with the increasing of automobile inventory,automobile emission has gradually become an important factor which contributes to the haze.To develop a new type of high efficient automobile exhaust purification technology has a vital significance for reducing pollution and protecting the environment.As two kinds of automobile exhaust purification technology,charged spray and non-thermal plasma technology have a broad application prospect as they have the characteristics of high efficiency and energy saving.The mechanisms of charged spray and non-thermal plasma for exhaust gas purification are complicated,carrying out the study on the characteristics of charged spray cooperating with non-thermal plasma for the purification of automobile exhaust is the basis of developing a new type of high efficient automobile exhaust purification technology and it has great research value.Based on the set up of charged spray cooperating with non-thermal plasma for the purification of automobile exhaust,a deep research on charged characteristics of spray,characteristics of charged spray for particle removal and diesel exhaust purification effect under the synergistic action of charged spray and non-thermal plasma has been carried out,which laid an experimental foundation for the development and application of charged spray cooperating with non-thermal plasma technology,research related is developed as follows:1.According to the structure characteristics of diesel engine exhaust system,we designed and made an induction charging nozzle;to explore the key factors which affect the droplet charging performance,a research on the charged characteristics and spray characteristics of spray in the process of induction charging was carried out,the experimental results show that the charge-mass ratio of droplet increased first then decreased as the increase of charged voltages;the charging of spray is related to the atomization pressures,and there is a optimal atomization pressure value for each nozzle;the droplets size decreased as the charged voltage increased,the bigger droplet size is,the stronger impact charged voltage has on the droplet size.2.Based on the speed of diesel exhaust and exhaust particle size distribution,the charged spray for particle removal experimental system was designed and set up;fine particulate matter came from diesel oil burning was used as the diesel exhaust particulates,the characteristics of charged spray for particle removal was studied,the experimental results show that charged spray has obvious advantages than traditional spray in removing fine particles like PM2.5,the overall particle removal efficiency was increased by 27.5% through charging the droplets which was 3 to 4 times than that of uncharged droplets;the particle removal efficiency by charging particles alone was higher than that of droplets;when both the particles and droplets were oppositely charged,a particle removal efficiency as high as 92.3% could be obtained.3.The effect of automobile exhaust purification under the synergistic action of charged spray and non-thermal plasma was researched,the experimental results show that the particle removal efficiency of charged spray increased as the increase of spray flow rate and the enhancing effect on the particle removal efficiency was obvious at the low engine speed;the purification efficiency of NO,CO and HC decreased as the increase of engine speed,the purification efficiency declining volume of CO reach a 40.2% which ranked the first among the three harmful gas and the purification efficiency declining volume of HC was 11.7% which declined the least.4.The influence of exhaust humidification on the particle removal and harmful gas purification was researched,the experimental results show that exhaust humidification could improve the removal efficiency of particles,especially at the high engine speed,an increase of 17% could be reached;exhaust humidification could promote the transformation of CO and NO while it has little effect on the transformation of HC,the promote effect to NO would weaken with the increase of charged voltage when it was at high charged voltage.