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Two methods of sampling exhaust emissions are typically used for characterizing emissions from diesel engines: total dilution which uses a constant volume sampling (CVS) system and partial flow dilution which relies on proportionally diluting a small part from the main exhaust stream. The CVS dilutes the entire exhaust flow to a constant volumetric flowrate which allows for proportional sampling of the exhaust species during transient engine operation. For partial dilution sampling during transient engine operation, obtaining a proportional sample is more rigorous and dilution of the extracted sample must be continuously changed throughout the cycle in order for the extracted sample flowrate to be proportional to the continuously changing exhaust flow. Typically, regulated emissions measured using both methods for an engine platform have shown good correlation. The focus for this work was on the experimental investigation of the two methods for the measurement of unregulated species.

Gasoline direct injection (GDI) has changed the exhaust composition in comparison with the older port fuel injection (PFI) systems. More recently, light-duty vehicle engine manufactures have combined these two technologies to take advantage of the knock benefits and fuel economy of GDI with the low particulate emission of PFI. These dual injection strategy engines have made a change in the combustion emission composition produced by these engines. Understanding the impact of these changes is essential for automotive companies and aftertreatment developers. A novel sampling system was designed to sample the exhaust generated by a dual injection strategy gasoline vehicle using the United States Federal Test Procedure (FTP). This sampling system was capable of measuring the regulated emissions as well as collecting the entire exhaust from the vehicle for measuring unregulated emissions.

Since the conception of the internal combustion engine, smoky and ill-smelling exhaust was prevalent. Over the last century, significant improvements have been made in improving combustion and in treating the exhaust to reduce these effects. One group of compounds typically found in exhaust, polycyclic aromatic hydrocarbons (PAH), usually occurs at very low concentrations in diesel engine exhaust. Some of these compounds are considered carcinogenic, and most are considered hazardous air pollutants (HAP). Many methods have been developed for sampling, handling, and analyzing PAH. For this study, an improved method for dilute exhaust sampling was selected for sampling the PAH in diesel engine exhaust. This sampling method was used during transient engine operation both with and without aftertreatment to show the effect of aftertreatment.

Advanced combustion strategies used to improve efficiency, emissions, and performance in internal combustion engines (IC) alter the chemical composition of engine-out emissions. The characterization of exhaust chemistry from advanced IC engines requires an analytical system capable of measuring a wide range of compounds. For many years, the widely accepted Coordinating Research Council (CRC) Auto/Oil procedure[1,2] has been used to quantify hydrocarbon compounds between C1 and C12 from dilute engine exhaust in Tedlar polyvinyl fluoride (PVF) bags. Hydrocarbons greater than C12+ present the greatest challenge for identification in diesel exhaust. Above C12, PVF bags risk losing the higher molecular weight compounds due to adsorption to the walls of the bag or by condensation of the heavier compounds. This paper describes two specialized exhaust gas sampling and analytical systems capable of analyzing the mid-range (C10 - C24) and the high range (C24+) hydrocarbon in exhaust.

Newly designed Teflon® O-rings along with XAD-2 resin, stainless steel screens, lock rings, and glass cartridges were used to construct a new semi-volatile organic compounds (SVOC's) sampling device. This new sampling device allows direct and repeated sampling, extraction, and cleaning without ever having to be disassembled or reassembled. This new XAD-2 glass cartridge (X2) was compared with three other sampling methods namely Empore® membrane (EM), hexane impinger (HI), and “Cold Trap” (CT) for SVOC sampling efficiency on diesel engine exhaust emissions. The X2 method showed the highest overall SVOC collection efficiency, followed by the EM and HI methods. The X2 method has higher trapping efficiency for the oxygenates, polycyclic aromatic hydrocarbons (PAH's), alkyl cyclohexanes, and the alkyl aromatics than the other three SVOC sampling methods. The HI method has the highest trapping efficiency for the normal alkanes.

A two-phase study was performed to establish a standard diesel exhaust composition which could be used in the future development of light-duty diesel exhaust aftertreatment. In the first phase, a literature review created a database of diesel engine-out emissions. The database consisted chiefly of data from heavy-duty diesel engines; therefore, the need for an emission testing program for light- and medium-duty engines was identified. A second phase was conducted to provide additional light-duty vehicle emissions data from current technology vehicles. Engine-out diesel exhaust from four 2004 model light-duty vehicles with a variety of engine displacements was collected and analyzed. Each vehicle was evaluated using five steady-state engine operating conditions and two transient test cycles (the Federal Test Procedure and the US06). Regulated emissions were measured along with speciation of both volatile and semi-volatile components of the hydrocarbons.

This study compared diesel exhaust emission from four different diesel fuels: a conventional low sulfur D2 diesel (0.03% sulfur, 28% aromatics), California Air Resources Board (CARB) diesel (0.015% sulfur, 8% aromatics), “Swedish” diesel (<0.001% sulfur, 4% aromatics), and a Fischer-Tropsch (F-T) diesel (<0.0001% sulfur, <0.1% aromatics) fuel. The comparison included regulated emissions, hydrocarbon speciation, air toxics, aldehydes and ketones, particle size distribution, and greenhouse gas emissions. Testing was conducted using a Cummins B-Series engine installed both in a heavy light-duty truck operating on a chassis dynamometer and on an engine dynamometer. The chassis driving cycles included city, highway, and aggressive driving operation. Engine dynamometer tests included the U.S. transient cycle.