posted on 2004-05-01, 00:00authored bySandip D. Shah, David R. Cocker, J. Wayne Miller, Joseph M. Norbeck
Elemental carbon (EC), organic carbon (OC), and particulate
matter (PM) emission rates are reported for a number
of heavy heavy-duty diesel trucks (HHDDTs) and back-up
generators (BUGs) operating under real-world conditions.
Emission rates were determined using a unique mobile
emissions laboratory (MEL) equipped with a total capture full-scale dilution tunnel connected directly to the diesel
engine via a snorkel. This paper shows that PM, EC, and
OC emission rates are strongly dependent on the mode of
vehicle operation; highway, arterial, congested, and
idling conditions were simulated by following the speed
trace from the California Air Resources Board HHDDT cycle.
Emission rates for BUGs are reported as a function of
engine load at constant speed using the ISO 8178B Cycle
D2. The EC, OC, and PM emission rates were determined
to be highly variable for the HHDDTs. It was determined that
the per mile emission rate of OC from a HHDDT in
congested traffic is 8.1 times higher than that of an
HHDDT in cruise or highway speed conditions and 1.9
times higher for EC. EC/OC ratios for BUGs (which generally
operate at steady states) and HHDDTs show marked
differences, indicating that the transient nature of engine
operation dictates the EC/OC ratio. Overall, this research
shows that the EC/OC ratio varies widely for diesel engines
in trucks and BUGs and depends strongly on the operating
cycle. The findings reported here have significant
implications in the application of chemical mass balance
modeling, diesel risk assessment, and control strategies such
as the Diesel Risk Reduction Program.