High NO_2/NO_X emissions downstream of the catalytic diesel particulate filter:An influencing factor study  

作　　者：Chao He Jiaqiang Li Zhilei Ma Jianwei Tan Longqing Zhao 

机构地区：[1]School of Mechanical and Traffic Engineering, Southwest Forestry University [2]National Lab of Auto Performance and Emission Test, Beijing Institute of Technology

出　　处：《Journal of Environmental Sciences》2015年第9期55-61,共7页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51006085);the Applied Basic Research Project of Yunnan Province (No. 2013FB052);Department of Education, Yunnan province (No. 2013Z081)

摘　　要：Diesel vehicles are responsible for most of the traffic-related nitrogen oxide（NO x） emissions,including nitric oxide（NO） and nitrogen dioxide（NO2）. The use of after-treatment devices increases the risk of high NO2/NO x emissions from diesel engines. In order to investigate the factors influencing NO2/NO x emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter（CDPF）. NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NO x ratios downstream of the CDPF range around 20%–83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NO x emissions. The maximum NO2/NO x emission appears at the exhaust temperature of 350°C. The space velocity,engine-out PM/NO x ratio（mass based） and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NO x emissions decreased with increasing space velocity and engine-out PM/NO x ratio. When the CO conversion ratios range from 80% to 90%,the NO2/NO x emissions remain at a high level.Diesel vehicles are responsible for most of the traffic-related nitrogen oxide（NO x） emissions,including nitric oxide（NO） and nitrogen dioxide（NO2）. The use of after-treatment devices increases the risk of high NO2/NO x emissions from diesel engines. In order to investigate the factors influencing NO2/NO x emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter（CDPF）. NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NO x ratios downstream of the CDPF range around 20%–83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NO x emissions. The maximum NO2/NO x emission appears at the exhaust temperature of 350°C. The space velocity,engine-out PM/NO x ratio（mass based） and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NO x emissions decreased with increasing space velocity and engine-out PM/NO x ratio. When the CO conversion ratios range from 80% to 90%,the NO2/NO x emissions remain at a high level.

关 键 词：Diesel engine Nitrogen dioxide Diesel particulate filter Exhaust temperature Space velocity 

分 类 号：X734.2[环境科学与工程—环境工程]