A Study Of The Effects Of Gasoline Components On Air Pollutants Of Exhaust And Evaporative Emissions From Light-duty Gasoline Vehicles

Volatile organic compounds(VOCs)in the atmospheric environment are both important precursors to near-surface ozone production and play an important role in the formation of atmospheric compound pollution.Vehicle exhaust and evaporative emissions of VOCs are important anthropogenic sources of pollution.The content of olefins and aromatics in gasoline components is an important environmental indicator that characterizes gasoline quality,and its changes can significantly affect vehicle pollutant emissions.At present,the studies on the effects of changing gasoline composition on exhaust and evaporative emission VOCs is relatively rare.In order to understand the effects of the reduction of olefin and aromatic content in gasoline on the characteristics of vehicles exhaust and evaporative emissions VOCs.In this paper,three light-duty gasoline vehicles with different olefin and aromatic contents were selected to conduct exhaust and evaporative emission tests based on chassis dynamometer and evaporative confinement chamber respectively,and the effects of gasoline component changes on VOCs species characteristics and ozone formation potential in exhaust and evaporative emission tests were investigated in detail.The effects of simultaneous reduction of olefins and aromatics content in gasoline on exhaust particulate matter,conventional gas pollutants,greenhouse gases,and fuel economy were evaluated.The results showed that(1)In general,the simultaneous reduction of olefin and aromatic content in gasoline has no significant effect on GHG CO2 emissions and fuel consumption;Particulate mass(PM)and Particulate number(PN)are more significantly affected by the olefin and aromatic content in gasoline,and their emission factors are reduced by 49%and 40.2%on average,respectively;NO_xemissions increased by 10.8%on average in the whole working condition;CO and NMHC emissions decreased by 9.2%and 11.9%on average in the whole working condition,respectively.(2)Reducing the content of olefins and aromatics in gasoline has little effect on the dominant species of tail gas emissions.The dominant species are mainly toluene,ethylene,benzene,propene,2,2,4-trimethylpentane,and ethane.From the perspective of hydrocarbon composition,after reducing the content of olefins/aromatics in gasoline,the amount of alkanes and olefins in VOCs was significantly increased,while the amount of aromatics in VOCs was reduced.(3)After reducing the olefins and aromatics content in gasoline,the overall reduction in hot soak and diurnal loss evaporation emissions HC for the two vehicles averaged 5.2%and 12.5%,respectively.(4)The reduction of olefin/aromatics content has little effect on the dominant species of vehicle hot soak and diurnal loss of evaporative emissions.The ozone formation potential(OFP)of vehicle hot soak and 48h diurnal loss of evaporative emission VOCs decreases with the decrease of olefins and aromatics content,while the 24h diurnal loss slightly increases.The above results indicate that the reduction of olefins and content in gasoline will have a large impact on vehicle exhaust and evaporative emission VOCs species characteristics and OFP.The results will provide data references for the improvement of VOCs emission inventory and further tightening of gasoline standards.