Effects of fuel-injection systems on particle emission characteristics of gasoline vehicles

In this study, the particle emission characteristics of gasoline vehicles with four different types of spark ignition engines, i.e., port fuel-injection (PFI), 150-bar side-mounted gasoline direct-injection (GDI), 200-bar side-mounted GDI, and 200-bar center-mounted GDI vehicles, were evaluated using Federal Test Procedure-75 (FTP-75) and worldwide harmonized light vehicles test cycle (WLTC). Particulate matter (PM), particle number (PN), and organic carbon/elemental carbon ratio (GC/EC) were evaluated using a PM holder, a solid particle counting system, and an OC/EC analyzer. The results of the PM and PN emissions tests indicated that GDI 200-bar vehicles emitted less than GDI 150-bar vehicles, and center-mounted vehicles emitted less than side-mounted vehicles. PFI vehicles showed 15% higher PN emission rates compared with GDI vehicles during acceleration conditions in FFP-75 mode. Additionally, PN emissions in WLTC hot mode indicated that speed affects PFI vehicles more than GDI vehicles. Furthermore, PFI vehicles did not show significant PN emissions in a low-speed phase, even at high acceleration. PFI vehicles showed 15% higher PN emission rates compared with GDI vehicles while accelerating in FTP-75 mode. PFI and GDI side-mounted vehicles showed higher OC emission rates in hot mode than in cold mode.