Emission characteristics of light-duty vehicles based on portable emission measurement system (PEMS)

The emission characteristics of gaseous pollutants and the fuel consumption from eleven gasoline light-duty gasoline cars were studied, using the portable emission measurement system (PEMS). The results showed that the emission factors of light-duty gasoline cars were (910.4±822.6) mg/km for carbon monoxide (CO), (58.0±48.3) mg/km for nitrogen oxides (NO_x), and (21.6±16.1) mg/km for total hydrocarbons (THC), respectively. The emission rates of CO, NO_x, and THC increased with the increase of vehicle specific power-velocity (VSP-v), and the emissions in the cold start phase accounted for 11.2%±2.1%, 3.7%±5.4%, and 52.7%±4.6% of the total CO, NO_x, and THC mass, respectively. The transient fuel consumption rates of the light-duty gasoline cars increased with the increase of VSP-v. Vehicle relative fuel consumption increased significantly as the vehicle average speed was less than 15 km/h, and increased slightly as the vehicle average speed was over 40 km/h. The emission rates of CO, NO_x, and THC at 20 ℃ were higher than those at 1 ℃. Ambient temperature also dramatically influenced vehicle fuel consumption rate. Especially when the vehicle was running at high speed, the fuel consumption rate at 1 ℃ was 27.1%±24.5% higher than that at 20 ℃.