Effects of exhaust port pressure on particulate matter emission and engine performance in gasoline direct injection engine

Abstract

In a gasoline engine, EGR has been applied to improve the efficiency of the engine and the exhaust gas discharged from the engine through the external EGR line is supplied to the intake air again. In the present study, the engine performance and exhaust emissions studied as a function of internal EGR rate by manipulating exhaust throttle valve. The study was carried out on a single cylinder engine with a direct injection system. The injection pressure was increased up to 50 MPa, and the equivalence ratio and the intake flow rate were kept constant. Experiments were conducted on the engine power and particulate matter emissions changes when the exhaust port pressure increased from atmospheric pressure to 0.2 MPa. Exhaust port pressure was controlled by throttle valve in emission line. Since exhaust port pressure is proportional to residual gas in cylinder, combustion speed is lower with increase of exhaust port pressure. It makes more time for mixing fuel with air and lower the maximum temperature.