Emission Rates of Particulate Matter and Elemental and Organic Carbon from In-Use Diesel Engines

Abstract

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.

Dominant Mechanisms that Shape the Airborne Particle Size and Composition Distribution in Central California

“…Particles released directly from a source (primary PM) have a characteristic size and composition distribution that is determined by the generating mechanism (Hildemann et al 1991;Kleeman et al 1999;Kleeman et al 2000;Allen et al 2001;Wingfors et al 2001;McDonald et al 2003;Sturm et al 2003;Hays 2004;Laschober et al 2004;McDonald et al 2004;Shah et al 2004). Once in the atmosphere, the particle size and composition distribution can be modified by chemical reactions, condensation/evaporation of semi-volatile species, coagulation with other particles, activation during high humidity, wet deposition, and dry deposition.…”

Effects of a diesel oxidation catalyst on gaseous pollutants and fine particles from an engine operating on diesel and biodiesel

“…where the 1.2 accounts for hydrogen and oxygen present in the OC; EC and OC refer to the mass of EC and OC collected [5]. In this paper, the PM mass was calculated as the addition of CM and the mass of water-soluble ions.…”

“…At low load, the exhaust temperature was lower compared to that at high load, thus the OC fraction in PM was higher at low load. Shah et al also reported that the OC fraction in TC was higher at idle than at creep: 0.80 OC/EC at idle and 21.80 at creep [5]. A blend of 20% biodiesel with diesel fuel (B20) was prepared and tested at 25%, 50%, and 75% load of 2690 r$min -1 .…”

“…They reported that the two catalytic converters significantly decreased the SOF in PM. Shah et al examined the effect of four different control technologies on the PM emitted from two diesel fuels with different sulfur content [5]. The honeycombstructured DOC showed a slight reduction in EC, but a significant reduction in OC emissions (56%-77%).…”

“…EC is traditionally used as a marker for human exposure to diesel exhaust and OC provides a significant amount of the mutagenic and carcinogenic chemicals in the air. The emission rates of EC and OC from a diesel engine and the ratios of EC to OC can be influenced by many factors including engine load, vehicle type, fuel composition and exhaust aftertreatment [3][4][5].…”