Evaluation of the Effect of Adding Ethanol to Gasoline at Different Percentages on Evaporative Emissions (Regulated and Non-regulated Pollutants)

摘要

Recent interest in ethanol has increased due to the promotion of its use by the authorities and because it can be combined with gasoline at different percentages: low percentages with not specially modified gasoline vehicles and up to 85% of ethanol (even up to 100%), in flexifuel vehicles. The question has arisen of whether the increase in volatility for ethanol/gasoline blends and the presence of ethanol (small molecule compared with the majority of hydrocarbons in gasoline) in the fuel have a significant influence on evaporative emissions, also taking into account permeation through materials used in the fuel system. The long-term effect on emissions of the addition of ethanol also needs to be evaluated. This paper assesses the impact of adding ethanol to gasoline on the evaporative emissions of vehicles by differentiating the sources (complete car, canister and fuel tank) and by differentiating evaporation and permeation effects. To achieve this objective, several evaporative emission tests were performed on a Euro 4 vehicle, a flexifuel vehicle and various fuel system components. The fuel blends used were E0, E5 splash and E10 for the Euro 4 vehicle and its components and E0 and E85 for the flexifuel vehicle and its components. Then the hydrocarbon measurements were completed with the speciation of the emissions determining the different contributions of some aldehydes, ketones, ethanol and more than 100 individual hydrocarbons, determined by GC and HPLC. This long list of pollutants and their ozone formation potential was used to estimate the ground-level ozone formation. The type of fuels and fuel systems components analyzed allow this paper to conclude with an evaluation of the results obtained in order to determine the effects of adding different percentages of ethanol to gasoline on evaporative emissions of vehicles and their fuel systems components.