Effect of gasoline aromatic compositions coupled with single and double injection strategy on GDI engine combustion and emissions

Gasoline direct injection (GDI) engines are facing the great challenge of particulate matter emission. In this work, three gasoline fuels meeting the latest China 6b gasoline standard but with different total and heavy aromatic contents were tested in a three-cylinder 1.0 L turbocharged GDI engine from the Chinese market. An experimental study of the single and double injection strategy on engine combustion, emissions and fuel consumption was conducted. The effect of the heavy aromatic components in the gasoline fuels was discussed in detail under different injection strategies as the Chinese market gasoline was abundant in aromatics for obtaining high octane number and there was no limit on heavy aromatics in the gasoline standard. The results showed that gasoline aromatic compositions were critical to the in-cylinder combustion and particulate emissions under the high-level emission operating conditions. The heavy aromatic contents presented a greater influence than the total aromatic content. It was also found that a late injection timing had significant negative impact on engine combustion, particulate emissions and fuel economy. Using the double injection strategy can reduce the particulate emissions, THC emissions and fuel consumption with all the test fuels, and the optimal strategy for low particulate emissions between different fuels was roughly the same. For the heavy aromatic fuel, compared with the results under the optimal single injection strategy, the particle number emission, THC emission and indicated specific fuel consumption were reduced by around 43.0%, 8.9% and 1.77% respectively under the optimal double injection strategy.