基于IVE模型的杭州市机动车实际行驶工况下排放因子的研究

首先,利用台架试验对IVE模型中的基础排放率进行地域性差异的修正;然后,利用GPS系统获得杭州市机动车在不同道路类型和时间下的实际行驶工况;最后,应用修正后的IVE模型确定杭州市实际行驶工况下轻型车和出租车的CO和NOx综合排放因子.结果表明,对IVE模型基础排放率的修正能较好地提高模型的模拟精度;在杭州市区高峰期实际行驶工况下,轻型车CO和NOx综合排放因子分别是2.92和1.03g/km,出租车的排放因子分别为轻型车的2.0和1.7倍.     

Real world vehicle emissions: Their correlation with driving parameters

Vehicular population in developing countries is expected to proliferate in the coming decade, centred on Tier II and Tier III cities rather than large metropolis. WLTP is being introduced as a global instrument for emission regulation to reduce gap between standard test procedures and actual road conditions. This work aims at quantifying and discernment of the gap between WLTC and real-world conditions in an urban city in a developing country on the basis of driving cycle parameters and simulated emissions for gasoline fuelled light passenger cars. Real world driving patterns were recorded on different routes and varying traffic conditions using car-chasing technique integrated with GPS monitoring and speed sensors. Real-world driving patterns and ambient conditions were used to simulate emissions using International Vehicle Emissions model for average rate (g/km) and Comprehensive Modal Emissions Model for instantaneous emission (g/s) analysis. Cycle parameters were mathematically calculated to compare WLTC and road trips. The analyses revealed a large gap between WLTC and road conditions. CO emissions were predicted to be 155% higher than WLTC and HC and NOx emissions were estimated to be 63% and 64% higher respectively. These gaps were correlated to different driving cycle parameters. It was observed that road driving occurs at lower average speeds with higher frequency and magnitudes of accelerations. The positive kinetic energy required by road cycles, was 100% higher than WLTC and the Relative Positive Acceleration (RPA) demanded by road cycles, was found to be 60% higher in real-world driving patterns and thereby contribute to higher emissions.     

基于PEMS技术的重型柴油客车排放实测与IVE模型预测对比分析

利用先进的尾气检测技术(PEMS)收集了重型柴油客车的逐秒排放数据,并分析了CO、HC、NOx、PM等排放物与机动车比功率(VSP)的关系,发现当VSP值小于O时,各污染物排放速率较小;当VSP值大于O时,随VSP值增大而显著提高.在此基础上,利用IVE模型对重型柴油客车的整体排放以及不同速度下排放进行预测,并将结果与实测值、国Ⅱ标准进行了对比分析.结果表明,车辆在低速行驶时污染物排放较为严重,进入中高速行驶状态后排放明显下降;相比拥堵多发的路段,IVE模型更适用于预测运行较为通畅的路段上的污染物排放.