LAUSR

Abstract In order to reach the goal of energy conservation and pollution emissions reduction, the combustion and emissions of a combined injection engine with ethanol port injection and gasoline direct injection under lean burn conditions are investigated in this paper. The experiments are carried out by using different direct injection timing (DIT), gasoline addition ratio (αgasoline) and excess air ratios (λ). The results indicate that Tmax declines after gasoline addition at λ = 1, 1.2, while increases after gasoline addition at λ = 1.4. The IMEP reaches the maximum value at DIT = 90 or 105 °CA BTDC and 0%, 10% and 30% gasoline addition bring the highest IMEP at λ = 1, 1.2 and 1.4, respectively. The COVIMEP decreases continuously with the increase of αgasoline and the EPI+GDI mode has great advantages in improving the combustion stability under λ = 1.4 condition. As for gaseous emissions, from λ = 1 to λ = 1.4, HC emissions change from increasing trend to the decreasing trend with the increase of αgasoline, while the NOx emissions show the opposite. As for particle number, at λ = 1 and 1.2, the total particle number (TPN) shows an upward trend with the increase of αgasoline. When λ = 1.4, TPN decreases with the increase of αgasoline.