How ethanol and gasoline formula changes evaporative emissions of the vehicles

Abstract

China, the biggest vehicle market in the world, will implement nation-wide use of ethanol-added gasoline (contains 10% ethanol, E10) by 2020. This change will have significant impact on evaporative emissions which contribute 40% of total vehicular volatile organic compounds (VOCs) in China. This study performs the largest scale measurements on vehicle evaporation in China utilizing four types of market-based gasoline (three E10 gasolines versus one E0 gasoline) and 5 vehicles with two control levels: normal control (major fleet in Euro and China) and advanced control (US Tier 2 and future China 6). Add of thanol and aromatics components enhance emissions through permeation mechanism, while Reid Vapor Pressure (RVP) has more impacts on canister-venting emissions. Average hot soak emissions increased by 45.4%, 40.5% and 28.6% when using E10 fuels for Euro 4, China 6 prototype and Tier 2 vehicles compared to emissions using E0 fuel. The average permeation of Euro 4 vehicles increased by ∼60% compared emissions when using E0 fuel. While, the impacts on diurnal emissions are associated with the dominated emission mechanism. Considering the real-world control strategy, the best performance on evaporative emissions was achieved by Fuel 3 (E10 with low RVP and aromatic). Besides, an upgrade on emission standard could dramatically reduce the total emission amount and the effects due to fuel composition difference can be ignored, indicating using ethanol would not become an excuse for violating compliance with emission regulations including China 6, which would be implemented in China in 2020.