Influence of ambient temperature on the CO emitted of light-duty vehicle.

Because of global warming, people have paid more attention to greenhouse gas emitted by vehicles. To quantify the impact of temperature on vehicle CO emissions, this study was conducted using the world light vehicle test cycle on two light-duty E10 gasoline vehicles at ambient temperatures of -10, 0, 23, and 40℃, and found that CO emission factors of Vehicle 1 in the low-speed phase were 22.07% and 20.22% higher than those of Vehicle 2 at cold start and hot start under -10℃. The reason was vehicle 1 had a larger displacement and more friction pairs than vehicle 2. There was the highest CO emission at the low-speed phase due to low average speed, frequent acceleration, and deceleration. The CO temperature factor and the ambient temperature had a strong linear correlation (R = 0.99). According to CO temperature factors and their relationships, CO emission factors of other ambient temperatures could be calculated when the CO emission factor of 23℃ was obtained, and the method also could be used to obtain the CO temperature factors of different vehicles. To separate the effect of load setting and temperature variation on CO emission quantitatively, a method was proposed. And results showed that the load setting was dominant for the CO emission variation. Compared with 23℃, the CO emission for vehicle 1 caused by load setting variation were 62.83 and 47.42 g/km, respectively at -10 and 0℃, while those for vehicle 2 were 45.01 and 35.63 g/km, respectively.