Study On The Characteristics Of Particulate Emissions From Gasoline Direction Injection (GDI) Engine

Since entering the new century,with the increasing of China's comprehensive national strength and international status,people spent more and more attention to environmental problems.GDI(Gasoline Direct Injection)technology is widely used in the production of gasoline engines at home and abroad because of its flexible mixture formation and combustion more fully,good fuel economy,power performance and less emission.But compared with traditional PFI(Port Fuel Injection)engine,GDI engine has essential difference with combustion mode.In this paper,the GDI engine particulate emission properties were studied.In this paper,the research is mainly based on the type of 2.0L GDI engine for the characteristics of particulate matter using Electrical Low Pressure Impactor manufactured by DEKATI.The results of research in this paper are as follows:1.The PM emissions of GDI gasoline vehicles can meet the requirements of the EURO ? laws,but the PN emissions far exceeds the limiting value.2.GDI gasoline vehicles under the NEDC cycle for cold and hot start particle emission contrast,results no matter in which stage of the NEDC,the cold start of particulate emission are higher than that of hot start.Temperature has a great influence on the particulate emissions.3.Comparing to the various GDI engines,the PM2.5 in NEDC cycle under the same condition PM2.5 in the second stage is significantly lower than the first stage,GDI gasoline vehicles make a major contribution to the PM2.5 emissions in cold start-up stage.4.The particulate emissions of GDI engine is a bimodal distribution,As the ignition advance Angle in advance,the number of total particulate number concentration and total mass concentration was a trend of increase;Both nucleation and accumulation mode show decreasing trend when A/Fratio gets bigger;As the injection time constant delay,particle number concentration shows increase after reducing first change trend,particle number concentration of the lowest appears near the optimum injection time.5.The change of back pressure will not produce regular changes to the GDI engine particulate number emissions,but can cause serious influence on engine performance,with back pressure rise,engine power and torque decline,fuel consumption increase.6.In WOT mode,particle number concentration shows increase after reducing first change trend while engine speed changes,besides particle number concentration shows decreasing trend when engine speed rise.7.Under steady state conditions,load change in low and middle range,the particle concentration of the total number declined with the increase of engine load,In high load and full load,the total number concentration rising sharply;Under transient state conditions,the particle number concentration change with load is bigger.In addition,the load of exploding or sudden drop can make the particle number concentration rose sharply.8.Whether it is under the steady state condition or transient conditions,GPF will make the quantity and quality of the GDI engine particulate matter concentrations significantly decline,the filtration efficiency of GPF is about 90%.