Emissions of toxic pollutants from compressed natural gas and low sulfur diesel-fueled heavy-duty transit buses tested over multiple driving cycles
Emissions of toxic pollutants from compressed natural gas and low sulfur diesel-fueled heavy-duty transit buses tested over multiple driving cycles
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DOI：
10.1021/es0491127
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发表时间：
2005-10-01
影响因子：
11.4
通讯作者：
Zafonte, L
中科院分区：
文献类型：
--
作者：
Kado, NY;Okamoto, RA;Zafonte, L
预计使用压缩天然气（CNG）和新型低硫柴油等替代燃料并配备后处理装置的重型车辆数量将会增加。然而，很少有同行评议的研究描述了这些车辆排放的颗粒物（PM）和其他有毒化合物。在这项研究中，使用化学和生物分析来表征CNG和低硫柴油燃料的重型公共汽车排放的可识别的有毒空气污染物，这些污染物在底盘测功仪上进行了三个瞬态驾驶循环和稳态巡航条件下的测试。CNG巴士没有后处理，柴油巴士首先安装了氧化催化剂（OC），然后安装了催化柴油颗粒过滤器（DPF）。排放分析了PM，挥发性有机化合物（VOCs；现场测定），多环芳烃（PAHs）和致突变活性。在本研究中测试的三种车辆配置中，2000年型号的cng燃料汽车的1,3-丁二烯、苯和羰基（如甲醛）排放量最高。1998年型号的柴油巴士配备了OC并使用低硫柴油，其PM和PAHs的排放率最高。在纽约公交车（NYB）行驶循环中，菌株TA98的CNG公交车的特异诱变活性（返生物/ μ g PM，或效力）和诱变物排放率（返生物/mi）最高。采用DPF的1998年型柴油客车的挥发性有机化合物、多环芳烃和致突变活性排放最低。总的来说，NYB驾驶循环的排放率最高（g/mi），而Urban Dynamometer driving Schedule （UDDS）在三个瞬态测试循环中所有有毒物质的排放率最低。此外，瞬态排放通常高于稳态排放。使用中的CNG公交车（不使用氧化催化剂）和使用低硫柴油（配备DPF）的车辆的有毒化合物排放量低于配备OC的低硫柴油车辆。与不受控制的柴油发动机相比，所有车辆配置的有毒物质排放普遍较低。隧道背景（车辆未行驶时的测量）在整个研究过程中都进行了测量，这有助于确定污染物排放的增量。此外，VOCs的现场测定，特别是1,3-丁二烯，有助于减少由于收集后样品降解造成的测量损失。
The number of heavy-duty vehicles using alternative fuels such as compressed natural gas (CNG) and new low-sulfur diesel fuel formulations and equipped with after-treatment devices are projected to increase. However, few peer-reviewed studies have characterized the emissions of particulate matter (PM) and other toxic compounds from these vehicles. In this study, chemical and biological analyses were used to characterize the identifiable toxic air pollutants emitted from both CNG and low-sulfur-diesel-fueled heavy-duty transit buses tested on a chassis dynamometer over three transient driving cycles and a steady-state cruise condition. The CNG bus had no after-treatment, and the diesel bus was tested first equipped with an oxidation catalyst (OC) and then with a catalyzed diesel particulate filter (DPF). Emissions were analyzed for PM, volatile organic compounds (VOCs; determined onsite), polycyclic aromatic hydrocarbons (PAHs), and mutagenic activity. The 2000 model year CNG-fueled vehicle had the highest emissions of 1,3-butadiene, benzene, and carbonyls (e.g., formaldehyde) of the three vehicle configurations tested in this study. The 1998 model year diesel bus equipped with an OC and fueled with low-sulfur diesel had the highest emission rates of PM and PAHs. The highest specific mutagenic activities (revertants/mu g PM, or potency) and the highest mutagen emission rates (revertants/mi) were from the CNG bus in strain TA98 tested over the New York Bus (NYB) driving cycle. The 1998 model year diesel bus with DPF had the lowest VOCs, PAH, and mutagenic activity emission. In general, the NYB driving cycle had the highest emission rates (g/mi), and the Urban Dynamometer Driving Schedule (UDDS) had the lowest emission rates for all toxics tested over the three transient test cycles investigated. Also, transient emissions were, in general, higher than steady-state emissions. The emissions of toxic compounds from an in-use CNG transit bus (without an oxidation catalyst) and from a vehicle fueled with low-sulfur diesel fuel (equipped with DPF) were lower than from the low-sulfur diesel fueled vehicle equipped with OC. All vehicle configurations had generally lower emissions of toxics than an uncontrolled diesel engine. Tunnel backgrounds (measurements without the vehicle running) were measured throughout this study and were helpful in determining the incremental increase in pollutant emissions. Also, the on-site determination of VOCs, especially 1,3-butadiene, helped minimize measurement losses due to sample degradation after collection.