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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 four different candidate fuels which were prepared by blending different components with a typical No. 2 diesel. Two fuels were blended with a synthetic diesel prepared from natural gas condensate, and all candidate fuels were splash blended with a proprietary additive package from International Fuel Technology Inc. (IFT). These fuels were then compared to the No. 2 diesel and to a California Air Resources Board (CARB) equivalent diesel fuel. The comparisons included fuel properties such as sulfur content, aromatics, cetane, lubricity, distillation; emissions; and fuel consumption. Emission testing was conducted on a 1991 Detroit Diesel Series 60. The Environmental Protection Agency (EPA) transient cycle was utilized for emissions, fuel characterization was performed according to ASTM standards, and fuel consumption was calculated by the carbon balance method.

Particulate and regulated gaseous emissions were characterized in a feasibility study for a 1994 Ford Taurus Flexible Fuel Vehicle (FFV) operating on five fuels. The five fuels included Federal Reformulated Gasoline (RFG); 85% fuel grade methanol and 15% gasoline (M85); 85% denatured ethanol and 15% gasoline (E85d); liquefied petroleum gas (LPG) meeting HD-5 specifications; and industry average compressed natural gas (CNG). The vehicle was operated fuel-rich to simulate a vehicle operating condition leading to increased production of particulate matter. This simulation was accomplished by using a universal exhaust gas oxygen sensor (UEGO) in connection with an external controller. Appropriate aftermarket conversion kits involving closed-loop control and adaptive learning capabilities allowed operation on the gaseous fuels. Particulate emissions were characterized by total mass and particle size.

Two additive blends proposed for improving the flame luminosity in neat methanol fuel were investigated to determine the effect of these additives on the exhaust emissions in a dual-fueled Volkswagen Jetta. The two blends contained 4 percent toluene plus 2 percent indan in methanol and 5 percent cyclopentene plus 5 percent indan in methanol. Each blend was tested for regulated and unregulated emissions as well as a speciation of the exhaust hydrocarbons resulting from use of each fuel. The vehicle exhaust emissions from these two fuel blends were compared to the Coordinating Research Council Auto-Oil national average gasoline (RF-A), M100, and M85 blended from RF-A. Carter Maximum Incremental Reactivity Factors were applied to the speciated hydrocarbon emission results to determine the potential ozone formation for each fuel. Toxic emissions as defined in the 1990 Clean Air Act were also compared for each fuel.

Neat methanol fuel (M100) has many advantages for achieving low emission levels as an automotive fuel, but there are several items that require attention before this fuel can replace conventional fuels. One item involves the low flame luminosity of methanol. An extensive literature search and laboratory evaluation were conducted to identify potential additive candidates to improve the luminosity of a methanol flame. Potential compounds were screened based on their concentration, luminosity improvement, and duration of luminosity improvement during the burn. Three compounds were found to increase the flame luminosity for segments of the burn at relatively low concentrations: toluene, cyclopentene, and indan. In combination, these three compounds markedly improved the luminosity of methanol throughout the majority of the burn. The two combinations were 1) 4 percent toluene plus 2 percent indan and 2) 5 percent cyclopentene plus 5 percent indan in methanol.