Quantitative investigation the influences of the injection timing under single and double injection strategies on performance, combustion and emissions characteristics of a GDI SI engine fueled with gasoline/ethanol blend

An experimental investigation of the single injection strategy and double injection strategy on the combustion phasing, performance and emissions characteristics in the GDI engine fueled with E10 was conducted. The effective expansion ratio (EER), effective expansion efficiency (EEE) and residual gas fraction (RGF) characteristics were further investigated under single injection strategy and double injection strategy. The result indicated that under the single injection strategy, the change trends of the EER and EEE were the same as the gasoline effective brake thermal efficiency (GEBTE). The maximum value of the EER and EEE were 7.86 and 0.513, and the maximum decrease magnitude of EER and EEE was 8.86% and 3.63%, respectively. However, the change trend of RGF was opposite to BTE, and its maximum increase magnitude of RGF was 4.72%. In addition, with the increase of the second end of injection timing, the peak combustion pressure (PCP), maximum heat release rate (HRR) and mean in-cylinder temperature gradually increased. The position of the maximum PCP and maximum HRR closed to the TDC. The CA50 combustion location advanced and the combustion duration shortened, and thereby increasing the EER, EEE and GEBTE. Finally, comparing the single injection strategy with the double injection strategy, the GEBTE decreased by 5.09%, while the NOx and HC emissions sharply decreased by 54.46%, 31.81%, respectively.