Study On Physical Properties And Emission Characteristics Of Fine Particles In Diesel Vehicles

With the rapid growth of economy and the rapid increase in the traffic of highways,the problem of pollution from diesel vehicles is becoming more urgent. Chemical compositions of particulate matter(PM) from diesel vehicles impact climate,meteorology and human health badly. To address this issue, it is important for making policy to control emissions from diesel vehicles.In this study, a new proportional sampling system were established, by which we can collect particles from current 92 diesel vehicles under city and high way driving patterns in three cities of Jinan, Yichang and Xiamen. The physical properties and chemical composition characteristic of PM from diesel vehicle are analyzed by means of other techniques. Quantitative analysis of the relationship between the vehicle driving cycle and PM2.5 chemical composition, this study established chemical compositions matrix based on driving cycle.The chemical and physical emission characteristics of diesel vehicles in China were studied by firstly establishing a PEMS(Portable Emission Measurement System), then carrying out on-road emissions testing with PEMS, and finally developing the diesel vehicle emission factor model.Based on the real-world emission test, this study analyzed the relationship between vehicle driving cycle and emission. The results indicate that on freeway driving cycle,the EC(elemental carbon) ration of PM from diesel vehicle tend to be a little higher than those on urban driving cycle. The higher EC emission can be attribute to the heavy engine load on freeway driving cycle; Due to the higher engine load on acceleration mode, EC/OC(organic carbon) ration was increasing from 1.5 to 2.8 with the higher vehicle driving speed when the speed are in 0-30km/h. When vehicle speed were above30 km/h, EC/OC ratio tended to be fluctuating from 2.8 to 3.0. This is because of the lower engine load and vehicle acceleration.9 Bins were determined by a direct-observation method, and then the chemical composition emission rate database and the simulation model for diesel vehicles were developed based on the 9 Bins. Comparison of the modeling results with the real world testing results demonstrates that the relative errors of EC and OM are less than ±10%respectively, and EC and OM are less than ± 14% respectively. Therefore, the simulation model is reliable.From developing the chemical composition emission inventory of diesel vehicle,EC emitted 235.5±37.8 Tg, and OM emitted 106.5±8.7 Tg, and ions emitted 21.9±3.8Tg, and trace elements is 11.9±3.7 Tg. Chemical composition emissions from the medium and heavy duty vehicles accounted for more than 93% of all diesel vehicles.