| The acceleration of the urban process has increased the number of motor vehicles,but also brought many environmental pollution problems.At present,the proportion of vehicle nitrogen oxide emissions to total nitrogen oxide emissions is increasing.Although governments at all levels have taken a series of measures to control the nitrogen oxide emissions,the effect of emission reduction is not obvious.Based on the above reasons,it is of great significance to study the current situation and emission reduction countermeasures of vehicle nitrogen oxides in the region for improving the control level of nitrogen oxides.The main contents of this paper are as follows:(1)Based on the existing number of various types of motor vehicles in Hunan Province,the emission of vehicle nitrogen oxides in Hunan Province in 2018 is analyzed according to the vehicle type,fuel type and emission standard.The analysis results show that the heavy-duty vehicles,pre-National I vehicles and diesel vehicles in Hunan Province are the focus of emission reduction.The large number of pre-National I vehicles are the focus of emission reduction.Although the number of diesel vehicles is not large,the proportion of NOx generated has reached 66.2%.Diesel vehicles are the focus of emission reduction under different fuel vehicles.(2)According to the grey model,the paper predicts the number of different types of motor vehicles in Hunan Province.In the next three years,the growth rate of the total number of motor vehicles in Hunan Province will be more than 10%,and the main growth rate will be automobiles.Based on the study of the influencing factors and degree of vehicle emission factors and the average annual mileage of all kinds of vehicles,it is concluded that the emission factors of heavy-duty trucks are the most influential,and the average annual mileage of large-scale passenger cars and medium-sized trucks in Hunan Province is higher.The vehicle speed,vehicle type and driving condition affect the emission of nitrogen oxides.The most nitrogen oxides are produced when the vehicle is accelerating and the vehicle speed exceeds 50 km / h.From 2019 to 2021,the NOx emission will gradually increase,the growth rate will decrease,and the growth value will not be large,but the NOx emission base is large,which can not be ignored,so it is urgent to increase efforts to reduce emissions.(3)Based on the two methods of emission factor and linear regression,the emission of vehicle nitrogen oxides in Hunan Province is predicted.It is found that the emission of vehicle nitrogen oxides in the next three years in Hunan Province will gradually increase.It is more reliable to use the model based on emission factor to predict the emission of nitrogen oxides.Monte Carlo model and box model are used to analyze the uncertainty of emission inventory and atmospheric environmental carrying capacity respectively.It is concluded that the uncertainty of the average annual mileage is the leading factor leading to the uncertainty of vehicle NOx emission results,and the average annual mileage of medium-sized trucks is the main source of NOx pollutants uncertainty.From 2018 to 2021,the emission of NOx in Hunan Province all exceeded the allowable value of environmental carrying capacity.(4)Three scenarios of emission reduction are designed,and the key points and countermeasures of emission reduction are put forward.Among the three emission reduction scenarios,the best is to improve vehicle emission standards,and the worst is to encourage priority use of public transport.It can start with improving the emission standard of motor vehicles and eliminating the yellow-label vehicles,and at the same time optimize and improve the traffic facilities.The research content of this paper is helpful to promote Hunan Province to achieve the "13th five-year plan" total emission reduction target,so as to better improve air quality.At the same time,it provides a reference for the special remediation of vehicle exhaust pollution in Hunan Province. |
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