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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.

Semi-volatile organic compounds (SVOC) are a group of compounds in engine exhaust that either form during combustion or are part of the fuel and lubricating oil. Since these compounds occur at very low concentrations in diesel engine exhaust, the methods for sampling, handling, and analyzing these compounds are critical to obtaining good results. An improved dilute exhaust sampling method was used for sampling and analyzing SVOC in engine exhaust, and this method was performed during transient engine operation. A total of 22 different SVOC were measured using a 2012 medium-duty diesel engine. This engine was equipped with a stock diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) catalyst in series. Exhaust concentrations for SVOC were compared both with and without exhaust aftertreatment. Concentrations for the engine-out SVOC were significantly higher than with the aftertreatment present.

The effects of fuel properties and emission control systems on exhaust hydrocarbon emissions have been studied. Using fourteen fuels with different properties, exhaust hydrocarbon emissions were measured for the two vehicle types with different emission control systems, under body catalyst and closed coupled catalyst, under the Federal Test Procedure. The fuel properties included high and low concentrations of olefins and aromatics as well as high and low T90. In addition, two fuels contained MTBE. The hydrocarbon emissions were discussed from the view point of the ozone reactivity and ozone formation potential. The results show that the high ozone reactivity of exhaust emissions are mainly caused by the olefins and aromatics in fuels. And also, the effects of fuel property change on exhaust emissions for the vehicle with an under body catalyst are more sensitive than the case of the vehicle with a closed coupled catalyst.

Results of engine bench tests on a 1998 heavy-duty diesel engine have confirmed the emissions reduction performance of a U.S. Environmental Protection Agency (EPA) registered platinum/cerium bimetallic fuel borne catalyst (FBC) used with several different catalyzed and uncatalyzed diesel particulate filters (DPF's). Performance was evaluated on both a 450ppm sulfur fuel (No.2 D) and a CARB 50ppm low sulfur diesel (LSD) fuel. Particulate emissions of less than 0.02g/bhp-hr were achieved on several combinations of FBC and uncatalyzed filters on 450ppm sulfur fuel while levels of 0.01g/bhp-hr were achieved for both catalyzed and uncatalyzed filters using the FBC with the low sulfur CARB fuel. Eight-mode steady state testing of one filter and FBC combination with engine timing changes produced a 20% nitrogen oxide (NOx) reduction with particulates (PM) maintained at 0.01g/bhp-hr and no increase in measured fuel consumption.

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.

As part of a study to analyze used catalysts, radiographs (x-rays) were taken of a number of used catalysts. Originally the radiographs were taken to aid in the disassembly of the catalysts. It was later found that the radiographs could be used to determine the amount of lead contained in the catalyst. The technique used to determine lead content is discussed and examples presented. Possible future uses of this technique in both research and after-market used catalyst screening are also discussed.