Influence of ambient temperature on the CO₂ 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 CO₂ 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 CO₂ 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 CO₂ emission at the low-speed phase due to low average speed, frequent acceleration, and deceleration. The CO₂ temperature factor and the ambient temperature had a strong linear correlation (R² = 0.99). According to CO₂ temperature factors and their relationships, CO₂ emission factors of other ambient temperatures could be calculated when the CO₂ emission factor of 23℃ was obtained, and the method also could be used to obtain the CO₂ temperature factors of different vehicles. To separate the effect of load setting and temperature variation on CO₂ emission quantitatively, a method was proposed. And results showed that the load setting was dominant for the CO₂ emission variation. Compared with 23℃, the CO₂ 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.