基于工况分布的轻型车速度排放修正因子的建立方法

速度排放修正因子(Speed Correction Factors,SCF)是评估速度变化对车辆排放影响的重要参数.然而,传统的SCF建立方法耗时长、成本较高,且获取的SCF分辨率较低.为了得到高分辨率的SCF,基于北京市大量的实测工况数据和排放率数据,提出了北京市轻型车SCF的建立方法.首先,对采集的工况数据进行60 s短行程划分及2 km/h行程速度的聚类;在此基础上,建立不同道路类型和速度区间下的比功率分布(Vehicle Specific Power,VSP);然后,结合排放率和建立的VSP分布,建立不同道路类型、排放标准的各污染物的SCF.经过分析,得出相比传统的SCF建立方法,本文提出的方法更能反映车辆的实际行驶特征、且获得的SCF的速度分辨率更高.

Development of SCF Based on Operating Mode Distributions for Light-duty Vehicles

Developing speed correction factors (SCF) are important for the evaluation of the effect of speed variations on vehicle emissions. However, the existing methods is time consuming and costly, and the developed SCF are in low resolution. In order to develop the SCF in high resolution, this study develops a method for deriving SCF for Light-duty vehicles in Beijing based on vehicle trajectory data. Massive 60’s speed-specific trajectories is divided from the vehicle activity data and grouped into speed-specific trajectory pools, and each trajectory pool is defined by the average speed with an equal interval of 2 km/h. Then, the vehicle-specific power (VSP) distribution is established for different speed and road types. Further, based on the emission rates and VSP distributions, the SCF for the pollutants are derived for different road types and emission standards. The analysis result shows that, the proposed method can generate SCF in higher resolution compared with the traditional methods, and it can capture more accurate traffic characteristics.