Prucz J C, Clark N N, Gautam M, Lyons D W
Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506-6106, USA.
Environ Sci Technol. 2001 May 1;35(9):1755-64. doi: 10.1021/es001416f.
In the U.S.A., exhaust emissions from city buses fueled by diesel are not characterized well because current emission standards require engine tests rather than tests of whole vehicles. Two transportable chassis dynamometer laboratories developed and operated by West Virginia University (WVU) have been used extensively to gather realistic emission data from heavy-duty vehicles, including buses, tested in simulated driving conditions. A subset of these data has been utilized for a comprehensive introspection into the trends of regulated emissions from transit buses over the last 7 years, which has been prompted by continuously tightening restrictions on one hand, along with remarkable technological progress, on the other hand. Two widely used models of diesel engines manufactured by the Detroit Diesel Corporation (DDC) have been selected as a case-study for such an overview, based on full-scale, on-site testing of actual city buses, driven in accordance with the SAE J1376 standard of a Commercial Business District (CBD) cycle. The results provide solid, quantitative evidence that most regulated emissions from engines produced by DDC have declined over the years, especially with the transition from the 6V-92TA to the Series 50 models. This improvement is remarkable mainly for the emissions of particulate matter (PM), that are lower by over 70%, on average, for the Series 50 engines, though the emissions of nitrogen oxides (NOx) exhibit a reversed trend, showing a degradation of about 6%, on average, with the transition from 6V-92TA to the Series 50 engines. The expected trend of decreasing emission levels with the model year of the engine is clear and consistent for particulate matter (PM), hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx), starting with the 1990 models, although it is not conclusive for carbon dioxide (CO2) emissions.
在美国，柴油驱动的城市公交车尾气排放情况尚未得到很好的描述，因为现行排放标准要求进行发动机测试而非整车测试。西弗吉尼亚大学（WVU）开发并运营的两个可移动底盘测功机实验室已被广泛用于收集重型车辆（包括公交车）在模拟驾驶条件下测试的实际排放数据。这些数据的一个子集已被用于对过去7年公交车辆受管制排放趋势进行全面反思，一方面是由于限制不断收紧，另一方面是由于技术取得显著进步。基于对按照商业商业区（CBD）循环的SAE J1376标准驾驶的实际城市公交车进行的全面现场测试，已选择底特律柴油机公司（DDC）生产的两种广泛使用的柴油发动机型号作为此类概述的案例研究。结果提供了确凿的定量证据，表明多年来DDC生产的发动机的大多数受管制排放都有所下降，尤其是从6V - 92TA型向50系列型号的转变。这种改进主要体现在颗粒物（PM）排放方面，50系列发动机的颗粒物排放平均降低了70%以上，不过氮氧化物（NOx）排放呈现相反趋势，从6V - 92TA型向50系列发动机转变时，平均约有6%的恶化。从1990年型号开始，对于颗粒物（PM）、碳氢化合物（HC）、一氧化碳（CO）和氮氧化物（NOx），随着发动机车型年份的增加，排放水平下降的预期趋势清晰且一致，尽管对于二氧化碳（CO2）排放而言并非如此。
