Evaluation of a Gasoline Particulate Filter to Reduce Particle Emissions from a Gasoline Direct Injection Vehicle

Gaseous compounds, particle number and size distribution measurements on a gasoline direct injection (GDI) vehicle and a port fuel injection (PFI) vehicle were conducted over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) on Tier 2 certification gasoline (E0) and a 10% by volume ethanol (E10). Overall the GDI test vehicle was observed to have lower fuel consumption than the PFI test vehicle by 6% and 3% for the FTP-75 and US06 drive cycles, respectively. When using E10, this GDI vehicle had a better fuel consumption than the PFI vehicle by 7% and 5% for the FTP-75 and US06 drive cycles, respectively. For particle emissions, the solid particle number emission rates for the GDI, equipped with a 3-way catalyst in its original equipment manufacturer configuration (i.e., stock GDI), were 10 and 31 times higher than the PFI vehicle for the FTP-75 and US06 drive cycles, respectively. However, when a non-catalyzed gasoline particulate filter (GPF) was installed, the solid particle number emission rates were only 2 and 8 times higher than that from the PFI vehicle. For the GDI vehicle, the number-weighted geometric mean particle diameters over both FTP-75 and US06 cycles were in the range of 50-70 nm. The situation was similar for the PFI vehicle over the FTP-75, however, over the US06, most of the emitted particles were ultrafine particles with a diameter of about 10 nm. E10 had little impact on particle diameter for both the GDI and PFI vehicles. The use of E10 fuel generally led to a reduction in particle number emissions on the PFI vehicle over both cycles. For the GDI vehicle, the use of E10 led to a reduction in particle emissions over the FTP-75 but the opposite was observed for the US06 drive cycle. Based on the test results, the unconditioned GPF had a particle filtration efficiency of 82 and 76% for the FTP-75 and US06 cycles, respectively. Results also revealed that the GPF filtration efficiency was strongly linked to the exhaust temperature and continued soot regenerations were the reason for the lower filtration efficiency being observed for the US06 drive cycle.