Effect of Injection Parameters on Particulate Matter Emission in a Direct Injection Gasoline Engine 2021-01-0628

PN(Particle Number) emission limits are more stringent for gasoline vehicles in Chinese VI emission standards (6×10¹¹ #/km). A EEPS engine exhaust particle size spectrometer was employed to characterize the effects of injection strategies on particulates emissions from a turbocharged gasoline direct injection (GDI) engine. The effects of operating parameters (injection pressure, second injection ratio and second injection end time) on particle diameter distribution and particle number density of emission was Investigated. The experimental result indicates that the quantity of particles decrease with the increase of injection pressure obviously, especially at high load including the 20% reduction of the particle number density. When the engine is at low load, the accumulation mode particle emissions are higher than the nucleation mode particle emissions compared with high load, which present opposite results. The second injection can restrain engine knock at low speed. With the increase of second injection ratio, the particle number density decreases initially and increases afterwards. The number of nucleation mode particle number density is relatively stable with the delay of the second injection end time. The accumulation mode particle number density decreases initially and increase afterwards. The optimal particle emission characteristic is obtained at an injection ratio of 8:2, with second injection end time of 70°CA.