Compositional Effect of Gasoline on Fuel Economy and Emissions

In the paper, fuel economy and emissions of a port-fuel-injection engine fueled with four gasoline were experimentally investigated to verify the validity and universality of the conclusions from the previous experiment conducted in a gasoline-direct-injection engine. On the basis of the previous results, which showed that aromatics and short-chain alkanes were beneficial to improving fuel economy and that oxygenated fuels could reduce emissions to some extent, commercial gasoline with a research number of 92 and three customized gasoline with different aromatic, short-chain alkane, and oxygen contents were chosen to conduct comparative tests in a wide range of working speeds (1000-3600 rpm) without any modification on the engine systems. Results show that aromatics do have great advantages on fuel economy under all operating conditions, while the mean fuel-saving ratio (FSR) of gasoline F with the highest aromatic content could reach 5.25% under stable operating conditions. Moreover, short-chain alkanes show good superiority of saving fuel consumption at light and medium loads of medium speeds, while the mean FSR of gasoline L with a higher short-chain alkane content is 3.55%. With regard to oxygenated fuels, gasoline E with a higher oxygen content, in which methyl tertiary butyl ether is used as an oxygen additive, shows good capability of balancing fuel consumption and emissions. Therefore, it has been proven that the previous results are valid and that the practical impacts on the performances of main engines applied in the markets are in accordance with the expectations.