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Characterization of commercial vehicles' start-up operations from in-use data

机译：商业车辆的初始运作表征来自内使用数据

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Diesel engines produce disproportionate levels of emissions when the engine and after-treatment systems are operating at low temperatures. This situation arises most commonly when the vehicle is first started after overnight. To quantify emissions attributable to vehicle starts, a sizable collection of on-road commercial vehicle operating data is analyzed to identify start-up events and inspect associated emissions. Data was obtained from the National Renewable Energy Laboratory's (NREL's) Fleet DNA and from the Center for Environmental Research & Technology (CE-CERT). Included are 500 + diesel vehicles with more than 42,000 recorded days, drawn from 25 vocational categories across the United States. Analysis shows that vehicle behavior, in terms of engine cold- and warm-operation, starts per day, soak time, and warm-up duration, differs significantly between vehicle vocations. Also, weighting factors for cold- and hot-starts currently used in the U.S. Environmental Protection Agency's Federal Test Procedure (FTP) for heavy-duty emissions certification accurately represent real-world operations. Although the FTP includes a comparable fraction of cold operation, the hot fraction is much shorter than real-world operation due to limited test duration. The investigation also revealed that real-world engines operate for a significant amount of time when the engine coolant is in the "hot-stabilized" region, but the selective catalytic reduction (SCR) temperature is below its effective operating temperature of 200 degrees C. Of the vehicles under investigation, almost 20% of their operational time is within this condition. Thus, novel approaches to raise and maintain SCR temperature are highly required to further reduce engine emissions.
机译：当发动机和后处理系统在低温下运行时，柴油发动机产生不成比例的排放水平。当车辆在过夜后开始时，这种情况最常出现。为了量化归属于车辆的排放开始，分析了一系列通道商用车操作数据，以识别启动事件并检查相关的排放。数据是从国家可再生能源实验室（NREL）的舰队DNA和环境研究与技术中心（CE-CERT）获得。包括500 +柴油车辆，录制日为42,000多天，从美国两侧的25个职业大小写。分析表明，车辆行为在发动机冷和热操作方面，每天开始，浸泡时间和预热持续时间，在车辆职业之间显着不同。此外，目前在美国环境保护局的联邦试验程序（FTP）中使用的冷和热启动的加权因素准确地代表了现实世界的运营。虽然FTP包括相当的冷操作分数，但由于测试持续时间有限，热部分比实际运作短得多。调查还透露，当发动机冷却剂处于“热稳定”区域时，现实世界的发动机在很大程度上运行，但选择性催化还原（SCR）温度低于其200摄氏度的有效工作温度。在调查的车辆中，其运作时间的近20％在这种情况下。因此，强烈需要进一步降低发动机排放的新型提高和维持SCR温度的方法。

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