es502949a_si_001.pdf (606.9 kB)
Cold Temperature and Biodiesel Fuel Effects on Speciated Emissions of Volatile Organic Compounds from Diesel Trucks
journal contribution
posted on 2014-12-16, 00:00 authored by Ingrid
J. George, Michael D. Hays, Richard Snow, James Faircloth, Barbara
J. George, Thomas Long, Richard W. BaldaufSpeciated
volatile organic compounds (VOCs) were measured in diesel
exhaust from three heavy-duty trucks equipped with modern aftertreatment
technologies. Emissions testing was conducted on a chassis dynamometer
at two ambient temperatures (−7 and 22 °C) operating on
two fuels (ultra low sulfur diesel and 20% soy biodiesel blend) over
three driving cycles: cold start, warm start and heavy-duty urban
dynamometer driving cycle. VOCs were measured separately for each
drive cycle. Carbonyls such as formaldehyde and acetaldehyde dominated
VOC emissions, making up ∼72% of the sum of the speciated VOC
emissions (∑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 emission rates from
different diesel engines under various test conditions showed that
these newer technologies resulted in lower emission rates of aromatic
compounds. However, emissions of other toxic partial combustion products
such as carbonyls were not reduced in the modern diesel vehicles tested.