Research on the NOx Emission and Exhaust Gas Temperature Characteristics of City Bus under the City Driving Cycle

摘要

Using portable emission measurement system, an experimental study on the NOx emission characteristics of city bus in practical operation are conducted, the eigenvalue of driving cycle are analyzed by short trip method. The results show that: idling time accounted for 20.392%, ratio of acceleration vvhicl between -0.5 m/s2 and 0.5 m/s2 accounted for as high as 83.314%.NOx emissions are greatly affected by the speed of vehicle: the instantaneous rate and total amount of NOx emission under high speed are much higher than low speed, the average urea injection under high speed is 3.5 times than low speed. When the vehicle speed is between 20-25km/h, the average emission rate of NOx is about 0.074g/s, while the time proportion of urea injection is under 40%;while the vehicle speed is above 55km/h, the average emission rate of NOx is about 0.025g/s, while the time proportion of urea injection can reach as high as 80%.