Combustion and emission characteristics of direct injection compression ignition engine fueled with wide distillation fuel (WDF)

摘要

To overcome the drawback of using diesel in LTC, a new fuel concept called WDF was proposed in recent years. WDF refers to fuels with a wide distillation range from initial boiling point (IBP) of gasoline to final boiling point (FBP) of diesel. In this work, two kinds of WDF (GDBF and FDF) were studied for both short-term and long-term consideration. In the study of GDBF, 50% gasoline proportion is selected as the optimal choice due to the load adaptability; at the same NO_x emissions level for Euro VI, G50 and diesel have similar ITE, G50 has the soot emissions around the target value of Euro V, while diesel has one order higher soot emissions at high load. In the long term, it is not necessary to employ different distillation and refinery processes to produce gasoline and diesel fuels. A novel fuel concept named FDF is proposed and an exploration of the feasibility was conducted. The measured physical and chemical properties of FDF indicate that C/H ratio, density and heat value of FDF vary between those of gasoline and diesel fuel and kinematic viscosity is close to the lower limit of diesel, which is benefit to high pressure injection. Cetane number of FDF is in the lower range of diesel fuel. The thermal efficiency, combustion and emission characteristics of a common-rail diesel engine fueled with FDF were experimentally investigated and compared with those burning the conventional diesel fuel and GDBF. The ignition delay, combustion duration changes little compared to diesel fuel while thermal efficiency is higher than diesel and GDBF; the pressure rise rate and heat release rate of FDF are higher than diesel fuel but lower than GDBF, and as the engine load increases, the combustion characteristics of FDF are close to diesel fuel; the soot, NO_x and CO emissions of FDF are close to diesel fuel, however, the THC emissions are slightly higher than diesel fuel.