Research On The Emission Factors And Emission Models Of Automobiles On Urban Roads

The birth of cars has greatly facilitated people's travel.Our car ownership is increasing rapidly in recent years.The consequent pollution of automobile exhaust is also more serious.Therefore,it is very important to study the exhaust emission of motor vehicles in China,analyze the law of pollutant discharge,and formulate emission standards which conform to the national conditions of our country.There are great differences between the standard test cycle of the laboratory and the actual road vehicle operation characteristics.The test results of the laboratory often do not reflect the actual emission level of the actual road vehicle.Therefore,it is of great significance to study the emission characteristics of the actual road of motor vehicles.In this paper,the emission rule of exhaust pollutants from vehicle under actual driving conditions is studied according to the driving characteristics,road morphology and specific power of vehicles under urban road traffic conditions.The emission model of exhaust pollutants on the actual road of light vehicle is constructed,and the accuracy of the model is verified.The SEMTECH-ECOSTAR vehicle exhaust gas analyzer to build an accurate measurement of the actual road light vehicle exhaust pollutant emission platform,a comparison of the data on the chassis dynamometer is fixed under the conditions measured,this method can be more accurate,real-time measurement of city light-duty vehicle driving conditions and three kinds of exhaust emissions of pollutants the statistical analysis of Chongqing light vehicle driving on the road in the urban areas,accelerating condition of the largest proportion,uniform conditions of decelerating again,idle speed has the smallest proportion,respectively 31.29%,30.93%,29.97% and 7.81%.The average driving speed of motor vehicles in Chongqing urban area is relatively low,which is basically around 28km/h.The emission rate under different working conditions is the highest under the accelerated condition,the second is under uniform speed,the second is under the slow working condition,the second is under idle speed.The contribution rate of the vehicle to the whole driving process is the highest at the speed of acceleration and uniform speed.Different sections under the light vehicle emissions is also very different,on the main road,NOx,CO,HC average emission rate of three is relatively high,this is mainly because the main road speed is relatively high,but the traffic density,vehicle speed is frequent,so are conducive to the generation of the three.In the expressway,the speed of the vehicle reaches the highest,about 50km/h,and the speed is more stable,so it is good for the generation of NOx,and the emission rate of NOx is high.On the secondary road,the emission rate of CO and HC is higher and the emission rate of NOx is relatively low.On the branch road,the ramp resistance is large,so the emission rates of the three are high.The introduction of the concept of emission factors and emission factors of various sections and calculate actual emission factors of test vehicles on the roads in the city of three kinds of pollutants,and compared with the national emission standard limits,three kinds of pollutants test vehicle emissions seriously exceed the standard,for CO,the actual emission factor is 3.13g/km,higher than the current the country V emission limits of 2.27g/km,exceeding the rate of about 38%;for HC,the actual emission factor is 0.47g/km,is also higher than the country V emission limit 0.16g/km,is about 3 times;for NOx,the situation is more serious,the actual test vehicle emission factor is about 4.8 times the country V emission limits.Study on the distribution of vehicles in the city on the road with three kinds of exhaust pollutants of acceleration and velocity of the vehicle,the three-dimensional joint distribution of pollutants with acceleration,speed rendering,and obtained certain rules,introduced the concept of vehicle specific power,and the acceleration,speed,power ratio of three factors respectively.Effect of three kinds of pollutant emission factors,through the regression analysis method is established based on the vehicle speed and vehicle specific power emission rate model,typical section ratio based on power emission rate model under typical operating conditions of city road light vehicle,and the accuracy of the model are analyzed.The results show that the model has a certain effect for prediction light vehicle on city road emission rate.