Research On The Particle Emission Characteristic During The Start And Warm Up Processes Of GDI Engine

With the maturing of vehicle manufacturing technology and the popularization ofcars, the GDI engine is more and more widely used in passenger cars due to its hugepotential of fuel saving and lower greenhouse gas emission. But its working mode ofinjecting fuel directly into the chamber mixing with air to form combustible mixturecauses deteriorate emission, especially during the start and warm up processes theparticle emission has a significantly increasing. The variation process of particlenumber concentration during the start and warm up processes of GDI engine underdifferent coolant temperature and the distribution of particle size on the idlingoperation mode are measured and analyzed in this article, investigating the influenceon the particle number、surface area、volume concentration and size distribution whenchanging the control parameters such as injection timing, ignition timing, air fuel ratioand engine speed, elaborating the particle emission characteristic during the start andwarm up processes of GDI engine. The main research conclusions are as follows:1、On the idling operation mode, as the ignition timing advanced, the numberconcentration, volume concentration and surface area concentration of particle matteris increasing. The particle number concentration grain size distribution presents asingle peak and the number concentration peak of nucleation modal particle is so smallthat is not obvious and the accumulation modal particle peak concentration moves tothe larger particles side.2、Along with engine speed rising the number concentration of nucleation andaccumulation modal particle matter is increasing, the particle number concentrationgrain size distribution presents a single peak and the peak of nucleation modal particlenumber concentration is very low so it is not obvious. As engine speed increasing thevolume and surface area concentration of particle matter is also rising.3、Both of the richer and leaner mixture will cause particle number concentrationincreasing. The particle number concentration reaches the minimum value when the airfuel ratio is1.0. The particle number concentration grain size distribution appears asingle peak, and the peak value of nucleation modal particle matter numberconcentration is lower1-2order of magnitudes than the accumulation modal particle. 4、The particle matter number concentration will reduce because of the longertime of fuel and air mixing along with spray timing advanced. Number concentrationof accumulation modal particle is higher than nuclear modal. The particle surface areaand volume concentration will also reduce as the spray timing advanced.5、During the wall induction4G15and inlet guidance1.4T GDI engine startprocess, the particle number concentration peak value is reducing as the coolanttemperature rising. After1-2seconds of engine starts, the particle numberconcentration rises rapidly and reaches its peak value, the particle numberconcentration peak value of4G15GDI engine is1-2order of magnitudes higher than1.4T GDI engine. During idling and warm up process, particle number concentrationdrops gradually and reaches steady state, there is no obvious influence to the particlenumber emission when using97#gasoline、commercial E93#gasoline and commercialE97#gasoline. The same as particle emission regular, the HC volume concentrationpeak value decreases slowly as the coolant temperature rising. When the engine runsinto idling and warm up operations mode, the HC volume concentration is reducingand runs into a steady state gradually and the HC emission of4G15GDI engine ishigher than the1.4T GDI engine.