Study On The Particle Number And Size Distribution From A Gasoline Direct Injection (GDI) Engine

With rapid advancement of control technology, GDI ( gasoline direct injection),which takes out throttle to decrease the fuel consumption and CO₂ emission, will became the main power of vehicle. However, GDI similar with diesel engine in the way of combustion indispensably increase the particulate matter emission. In this study, characteristic of particulate matter from a GDI engines was investigated, compared with a port fuel injection (PFI) gasoline engine and a low temperature combustion (LTC) diesel engine. Then, effect of combustion organization on particle number and size distribution was studied based on another GDI engine with controllable combustion parameter. The results showed as follow:First, in the idle condition, particle number concentration, surface area and mass of the GDI engine were more than that of the PFI engine, but less than the LTC diesel engine. Its Geometric mean diameter (GMD) is smaller than that of PFI gasoline and LTC diesel engine.Second, as the load increased, although number of nucleation particles of the GDI engine reduced, accumulation particles increased, as well as its surface area and mass. Total particle number of the GDI engine is lower than the PFI engine and the LTC engine, but its surface area and mass was higher with increasing load.Third, as the speed increased, particle number of the GDI engine reduced with the same tendency of the PFI engine. Its surface and mass showed the same change with that of the LTC engine, which is lower in the first, and then is higher.Forth, with the increasing air-fuel ratio, the cylinder combustion temperature and post-oxidation temperature changes, which caused that nucleation is less in the first and then is more. As for the accumulation, its number, surface and mass gradually decreased.Fifty, with the spark timing advanced, both nucleation and accumulation increased as well as its surface and mass, owing to the change of in-cylinder combustion temperature and post-oxidation temperature.Six, with the injection timing advanced, the nucleation of GDI engine first increased and then decreased; its accumulation continued to increase. Total particle number, surface and mass increased with the effect of fuel-air mixing time and wetted-wall.In sum, this study preliminarily formed an effective system of evaluation of GDI engine particulate emissions and an accurate method of measuring and analyzing s for further research. Moreover, this experiment provided an basis for provide the basis for controlling of particulate emissions from the GDI engine.