Characteristics Of Light Vehicle Emissions On Urban Road In Fuzhou City Based On PEMS

With the rapid growth of the number of motor vehicles in China,the problem of vehicle exhaust emission is becoming more and more serious,which has a great impact on the climate environment and human health.It has become a major concern of motor vehicle manufacturing and environmental protection of the government.In order to evaluate motor vehicle emission and urban vehicle emission control strategy,the essential work is to explore the characteristics of motor vehicle emissions and establish a driving cycle.This paper selects light duty vehicles in Fuzhou as the research object,establishing the driving cycle of Fuzhou by principal component and cluster analysis.SPSS21.0 and MATLAB software is used to realize the coupling speed-acceleration effect on emissions.Based on that,the emission characteristics of light vehicles with different emission standards in different road grades,and the effects of different parameters on emissions are discussed.The result would be the base of further study on emission characteristics of light duty gasoline vehicles.The main research conclusions are as follows:(1)Based on SEMTECH-ECOSTAR portable vehicle emission device、GPS and computer consisting of a set of vehicle emission test system(Portable Emission Measurement System,PEMS),three light duty vehicles with different emission standards are tested on the typical road network in Fuzhou.Real-time second-by-second data of emission and speed,temperature,humidity and other are obtained.(2)According to the large number of measured data from the experiment,cutting apart driving segments,and 26 representative feature parameters are selected for a more comprehensive description of vehicle motion processes.Using principal component and cluster analysis to descend dimens and classify.Then the driving segments are reorganized by the principle of minimum error,and a total of 3 driving conditions are finally obtained.The results show that the actual driving condition of light duty gasoline vehicles in Fuzhou are very different from the standard cycle,and the combined driving cycle can reflect the light duty vehicles in actual road driving situation of Fuzhou.more accurately.and more representatively.(3)The distribution characteristics from light duty gasoline vehicles emission on the speed-acceleration plane are discussed in depth.The results show that the NOx emission factor of the vehicle tends to be higher when the speed and acceleration are larger,but HC emission factor is higher in the smaller speed range.Calculating and collating the emission data of different road grade,the emission factor characteristics of experimental vehicles in different grade roads are obtained.The results show that,overall,the emission of NOx is the highest on the expressway and the lowest in the branch;the HC emission is the highest in the branch road and the lowest in the expressway.Due to the change of different emission standards,the emission of exhaust pollutants shows remarkable characteristics.Three types of vehicle emission standards from high to low is that:National Ⅲ>NationalⅣ>National Ⅴ,with the strictness emission standards for motor vehicles,the emission levels of the vehicle decreased gradually.The NOx emission in National Ⅴ decreased by 53.7%and 76.9%respectively compared with the emission in National Ⅳ and National Ⅲ,and the HC emission in National V decreased by 27.4%and 62.2%respectively compared with the emission in National Ⅳ and National Ⅲ.Furthermore,the relationship between speed、acceleration、slope、VSP and the actual vehicle exhaust emission are analyzed.The results show that acceleration and speed have a great influence on the emission.The emission factor of NOx decreases with the increase of speed and acceleration;the emission factor of HC decreases with the increase of speed,it keeps steady in a certain range of acceleration,and then increases with acceleration.The emission factors of NOx、HC increased with the increase of slope.The increase of pollutant emissions have a regular increase in most VSP bins.The influence of emissions and working conditions can be explained more clearly and accurately from the physical process of the whole vehicle driving,and it can reflect the relationship between various factors and vehicle emissions objectively.