Experimental Study Of Particle Emission Characteristics From GDI Engines

This paper experimentally studies the particle emissions from the Gasoline DirectInjection (GDI) engine powered passenger cars and the GDI engines fuelled withdifferent octane fuels. Three types of GDI passenger cars and one kind of Port FuelInjection (PFI) passenger car from Chinese market are tested on the chassisdynamometer. Two types of GDI engines and one kind of diesel engine are tested on theengine test bench. The Particle Mass (PM), the Particle Number (PN) and particlediameter distribution are measured on the cars and the engines.The chassis dynamometer test results show that the PM emission of GDI and PFIcars can meet Euro6regulation requirements, but the PN emission of the GDI cars isover Euro6limit. There is a large quantity of particle emission from GDI and PFI carsduring the cold start, and there is obvious PN emission under the transient conditions forGDI cars after the engine is warmed up. For the GDI cars, the particles are concentratedin accumulation mode. The peak diameter of the nucleation mode particles is about15nm, and the peak diameter of the accumulation mode particles is about80nm. It canbe observed from the microstructure of particles that, both of particles from the GDIcars and the PFI car aggregate as clusters on the filter paper. These clusters areagglomerated from primary particles whose diameters are between10nm to20nm.Whenthe GDI car calibrated with a high RON fuel runs with a low RON gasoline, theknocking will occur in high load with an increase of both the nucleation andaccumulation particles.The engine test bench results show that the PM and PN emission increase with theincrease of the load. Both of the PM and PN emissions decrease with the increase ofexcess air ratio and the delay of the ignition timing. The three-way catalystmeasurements show that the catalyst reduces the organic component in the particulatematter and the nucleation mode particles. The GDI engine and diesel engine whichcomply with the Euro4regulation have the same particle size range. The diesel enginehas higher PM and PN emissions in low load, while the GDI engine has higer PM andPN emissions in high load. The analysis results of the Soluble Organic Fractions (SOF)in the particulate matters show that there is no significant difference in the SOF components forms between the GDI and diesel engines, but the there are more SOF inthe particulate matters from the diesel engine.