[Measurements of OC and EC Emission Factors for Light-duty Gasoline Vehicles]

Organic carbon (OC) and elemental carbon (EC) emission factors from 27 State 3-5 light-duty gasoline vehicles (LDGVs) were tested in this study using a CVS (Constant Volume Sampling) system on a dynamometer. The influences of start conditions, driving cycles, and fuel injection technologies on the OC and EC emissions were analyzed. The results show that the OC emission factors of the tested State 3 to 5 LDGVs were (2.09±1.03), (1.59±0.78), and (0.75±0.31) mg·km^-1, respectively, and the EC emission factors were (1.98±1.42), (1.57±1.80), and (0.65±0.49) mg·km^-1. Both OC and EC emissions significantly decreased with the promotion of emission standards. The OC/EC ratios were 1.54±0.92, 1.53±0.91, and 1.47±0.66, respectively. OC1, OC2, EC1, and EC2 were the most important carbonaceous components from LDGVs, accounting for 15%, 20.6%, 22.2%, and 21.7%, respectively. OC and EC emission factors under cold-start conditions were 1.4 and 1.8 times those under hot-start conditions. OC and EC emission factors for highway cycles were 2 and 4 times those for urban cycles. OC emission factors from GDI (Gasoline Direct Injection) engines were close to those from PFI (Port Fuel Injection) engines. However, their EC emission factors were 1.7 times those from PFI engines. With the increasing popularity of GDI engines in LDGV fleets in China, the EC emissions from these engines should be paid more attention in the future.