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Cold Temperature and Biodiesel Fuel Effects on Speciated Emissions of Volatile Organic Compounds from Diesel Trucks
Citation:
George, I., M. Hays, R. Snow, J. Faircloth, BJ George, T. Long, AND R. Baldauf. Cold Temperature and Biodiesel Fuel Effects on Speciated Emissions of Volatile Organic Compounds from Diesel Trucks. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 48(24):14782-14789, (2014).
Impact/Purpose:
This manuscript presents speciated measurements of mobile source air toxics from diesel exhaust during the most recent dynamometer study on biodiesel and cold temperature effects on diesel emissions. This paper will significantly improve emission inventories of speciated volatile organics from modern diesel vehicles that are needed for air quality models. This product falls under ACE 032 and ACE 004 tasks.
Description:
Speciated volatile organic compounds (VOCs) were measured in diesel exhaust from three medium heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a chassis dynamometer at two ambient temperatures (-6.7°C and 21.7°C) operating on two fuels (ultra-low sulfur diesel and 20% soy biodiesel blend) over three driving cycles: cold start, warm start and urban dynamometer driving cycle (UDDS). VOCs were measured for each drive cycle separately. Carbonyls, such as formaldehyde and acetaldehyde, dominated VOC emissions, making up ~72% of VOCs overall. Biodiesel use led to minor reductions in aromatics and variable changes in carbonyls. Cold temperature and cold start conditions caused dramatic enhancements in VOC emissions, mostly carbonyls, compared to the warmer temperature and other drive cycles, respectively. Different 2007+ aftertreatment technologies involving catalyst regeneration led to significant modifications of VOC emissions that were compound-specific and highly dependent on test conditions. A comparison of this work with literature showed that these newer technologies resulted in lower emission rates of aromatics. However, other toxic partial combustion products, such as carbonyls, continue to have relatively high emission rates in modern diesel vehicles.
