An Experimental Study of the Effects of Coolant Temperature on Particle Emissions from a Dual Injection Gasoline Engine

Euro VI emission standards have set a very strict limitation on particulate matter emissions of Gasoline Direct Injection (GDI) engine. It is difficult for GDI engine to meet the Euro VI PN regulation (6×10¹¹#/km) without a series of complicated after-treatment devices such as Gasoline Particulate Filter (GPF). Previous research shows that GDI vehicles under cold start condition account for more than 50% of both particle number and mass emissions during the entire NEDC driving cycle. Dual Injection Gasoline engine is based on the GDI engine by adding a set of port fuel injection system. The good mixing characteristics of the port fuel injection system can help to reduce the particulate matter emissions of the GDI engine during the cold start condition. In this study, a Cambustion DMS500 fast particle spectrometer was employed to characterize the effects of coolant temperature and direct injection ratio on particulate emissions from a turbocharged four-cylinder dual-injection gasoline engine. The experimental results showed that with the coolant temperature increasing the particulate matter tended to be consistent under the port fuel injection mode. The particulate matter showed significantly drop with the coolant temperature increasing both in the dual injection mode and the direct injection mode. At the same coolant temperature, with the decrease of the direct injection ratio, the particulate matter showed notably reductions, and with the increase of coolant temperature, the magnitude of the reductions gradually declined. The experimental results provided important guidance to reduce the particulate matter via dual injection mode during the cold start condition.