Emission Characteristics Of Volatile Organic Compounds From Diesel Vehicles Based On Portable Emission Measurement System

In this study, the emission data of volatile organic compounds (VOCs) for differenttypes of diesel vehicles were acquired based on the Portable Emission MeasurementSystems (PEMS). The VOC emission characteristics for diesel vehicles were analyzed, andthe emission amounts of VOCs and Ozone Formation Potential (OFP) for diesel vehicles in2012in Beijing were calculated.19diesel trucks and11low speed vehicles covering different types and differentemission control technologies were tested in Bejing and Xiamen by using the VOCssampling system developed by ourselves. Tedlar bag sampling and2,4-dinitrophenyhydrazine (DNPH) cartridge sampling were used to collect VOC species,and gas chromatography-mass spectrometry (GC/MS) and high-performance liquidchromatography (HPLC) were used to quantified these samples. Finally, VOC emissionfactors and composition proportion of diesel vehicles were obtained.The effects of different types of diesel vehicles on VOC emissions were analyzedbased on the test data. The results show: the average VOC emission factors of testedlight-duty diesel trucks (LDDTs), medium-duty diesel trucks (MDDTs) and heavy-dutydiesel trucks (HDDTs) were74.1mg/km,64.0mg/km and110.2mg/km, respectively. Thecomposition proportion of VOCs for LDDTs were alkenes <aromatics <alkanes <carbonyls, and MDDTs and HDDTs both were alkenes <alkanes <aromatics <carbonyls.The average emission factors of VOCs from tested low-speed trucks and three-wheelerstrucks were326.2mg/km and198.3mg/km, and the composition proportion of both werealkenes <alkanes <aromatics <carbonyls.The effects of different emission standards and driving patterns on VOC emissionswere determined based on the test data. The results show: the total VOCs emission factorspresenting a significant decline trend with the implementation of strict emission standards.The VOCs emission factors of tested China III diesel trucks were reduced about37.5%compared with tested China II diesel trucks. The composition proportion of tested differentemission standards diesel trucks presented the same trend that alkenes <alkanes <aromatics <carbonyls. The VOC emission factors of diesel trucks driven on non-highwayroutes were approximately three times higher than those of diesel trucks driven on thehighway.Different VOC species had different contribution to OFP. Carbonyls had the largest contribution to the VOCs atmospheric chemical activity for all diesel vehicles, and theaverage contribution to OFP were about73.05%. Followed by aromatics, alkenes andalkanes, the average contribution to OFP were about15.20%,6.79%and4.56%,respectively. Formaldehyde, acetaldehyde, propaldehyde, butenal,1,3-xylene,1,2,3-trimethylbenzene,1,3,5-trimethylbenzene and ethane were the key active VOCspecies for tested diesel vehicles in Bejing.Based on the IVE model which revised by messured data of this study, and combinedwith activity level data of diesel vehicles, the generation of VOCs and O3were acquired in2012in Beijing. The generation of VOCs in2012in Beijing for diesel trucks and lowspeed vehicles were about3722.1tons and501.1tons, and O3production were602.0tonsand316.1tons, respectively. The VOCs emission of low speed vehicles cannot be ignored.