Effects of Oxygenates and Aromatics in Gasoline on Vehicle Particulate Emissions 2021-01-0542
There have been tremendous improvements in China fuel quality in recent years in conjunction of newly implementing vehicle emissions standards to combat air pollutions in China. As the focus of the concern in the particulate emissions on the gasoline engine with ever popular gasoline direct inject (GDI or SIDI) engines, China 6 emission standard introduces PM/PN requirements for all spark ignition gasoline vehicles. Furthermore, ethanol and aromatics are widely used as octane booster changing the structure of gasoline pool. Nevertheless, the composition of gasoline is one of the factors affecting PM/PN emissions. In this study, different gasoline samples with two oxygenates in ethanol and methyl tert-butyl ether (MTBE), and heavy aromatic hydrocarbons were studied on a vehicle with a GDI engines. Vehicle tests were performed on Worldwide Harmonized Light Vehicles Test Cycle (WLTC).
In order to investigate the effect of oxygenates on PM/PN emissions, one group of the test fuels were designed with a base fuel blending either ethanol or MTBE or mix of the two in different levels. Another group of the test fuels were designed with different levels of aromatics by carbon numbers. For the oxygenates group, emission results illustrate that the PN emissions have poor correlation with either fuel indices or oxygen contents meaning that the fuel indices need to be corrected based on oxygenates. The base fuel blends with 10% of ethanol shows a relatively higher PN emissions than other oxygenated test fuels. For the aromatics group, results show a good correlation between particulate emissions, fuel indices and heavy aromatic hydrocarbons. PN emissions increase with the raise of heavy aromatics content while the total aromatics content is consistent of test fuels. Furthermore, reduction of heavy aromatics hydrocarbons is more important while the increase of total aromatics does not necessarily lead to a raise of PN emissions.
Lu Han, Huayu Tian, Susan Zhang, Pat Geng, Xin Guo, Bo Li, Yu Zheng, Na Li, Shuntao Liu, Zhiping Tao, Jianrong Zhang, Han Zhou
Sinopec RIPP, Pan Asia Technical Automotive Center Co, General Motors LLC