David L. Hilden

THE CONTRIBUTION OF ENGINE OIL TO DIESEL EXHAUST PARTICULATE EMISSIONS

A radioactive tracer technique was developed to determine the contribution of oil from an engine sump to exhaust particulates collected on a filter. The technique was applied to particulate emissions produced by an automotive diesel engine which was operated on an engine dynamometer over a range of steady-state conditions. Results indicated that from 1.5 to 25 mass percent of particulate matter, depending on speed and load, consisted of material from engine oil. The oil contribution to particulate matters extractable organic portion varied from 16-80%. The greatest contribution from oil was generally observed at high test speeds.

The Contribution of Engine Oil to Particulate Exhaust Emissions from Light-Duty, Diesel-Powered Vehicles

An apparatus was developed for the determination of the engine oil contribution to both total and extractable particulate exhaust emissions from diesel-powered vehicles during cyclic operation on a chassis dynamometer. For the five vehicles tested, the percentage of the total particulate material that was derived from engine oil ranged from 7 to 14%. Between 14 and 26% of the total particulate material was extractable with benzene-ethanol (80-20) solvent. Oil contributed from 30 to 55% of the extractables in most cases. Engine design and oil formulation generally appeared to have only small effects on the oil contribution to the particulate emissions. A 1982 model-year vehicle with a 1.8L engine was an exception, since its oil contribution to the total and especially to the extractable particulate emissions (14 and 95%, respectively) was significantly greater than for any of the other vehicles.

The effect of manganese fuel additive and exhaust gas recirculation on diesel particulate emissions

A study was undertaken to determine the combined effect of methylcyclopentadienyl manganese tricarbonyl (MMT) fuel additive and exhaust gas recirculation (EGR) on particulate and oxides of nitrogen (NOx) emissions from a single-cylinder light-duty diesel engine. Further, the physical and chemical properties of the particulate material were determined to better understand MMT and EGR effects on these emissions. The results showed that EGR always decreased NOx emissions, and that MMT had no significant effect on them. In addition, EGR always increased particulate emissions, but MMT was effective in limiting this increase especially at high EGR levels.

The Exhaust Emissions of Prototype Ultra-Low Sulfur and Oxygenated Diesel Fuels

A 1.3-L direct injection diesel engine was used in steady-state testing to determine the emissions performance of a matrix of ultra-low sulfur diesel fuels encompassing two types of sulfur removal and the use of fuel oxygenates. As expected, exhaust gas recirculation was the most effective technique for NOx reduction. With regard to fuel effects, an oxygenated diesel fuel produced with a conventional sulfur removal process reduced particulate emissions substantially, and these particulate reductions could be converted into NOx reductions by using higher levels of exhaust gas recirculation. On a simulated FTP, this oxygenated fuel simultaneously decreased NOx emissions by 30% and total particulate emissions by 50% compared to a baseline fuel.

The Relationship of Gasoline Diolefin Content to Deposits in Multiport Fuel Injectors

The diolefin content of unstable gasolines has been implicated in the restriction of multiport fuel injectors by deposits. Vehicle tests of the effect of adding a diolefin mixture to a stable (olefinic) gasoline indicated that a deposit-producing gasoline resulted. Laboratory oxidation tests showed that addition of a «dienophile» to an unstable gasoline significantly reduced deposit formation, increased oxidation stability, and reduced gum formation

Emissions of Toxicologically Relevant Compounds Using Dibutyl Maleate and Tripropylene Glycol Monomethyl Ether Diesel Fuel Additives to Lower NOx Emissions

A previous paper reported (SAE Paper 2002-01-2884) that it was possible to decrease mode-weighted NOx emissions compared to the OEM calibration with corresponding increases in particulate matter (PM) emissions. These PM emission increases were partially overcome with the use of oxygenated diesel fuel additives. We wanted to know if compounds of toxicological concern were emitted more or less using oxygenated diesel fuel additives that were used in conjunction with a modified engine operating strategy to lower engine-out NOx emissions. Emissions of toxicologically relevant compounds from fuels containing triproplyene glycol monomethyl ether and dibutyl maleate were the same or lower compared to a low sulfur fuel (15 ppm sulfur) even under engine operating conditions designed to lower engine-out NOx emissions. The emissions of toxicologically relevant compounds using a 100% Fisher Tropsch fuel, a recognized clean fuel, were equivalent to or less than emissions from the two oxygenated diesel fuels. These results suggest that these oxygenated diesel fuel additives can be used to lower engine-out NOx emissions without risking any increase in tailpipe emissions of compounds of toxicological concern.

Emissions of toxicologically relevant compounds using fischer-tropsch diesel fuel and aftertreatment at a low NOx, low power engine condition

Previously we reported (SAE Paper 2005-01-0475) that emissions of toxicologically relevant compounds from an engine operating at low NOx conditions using Fischer-Tropsch fuel (FT100) were lower than those emissions from the engine using an ultra-low sulfur (15 PPM sulfur) diesel fuel (BP15). Those tests were performed at two operating modes: Mode 6 (4.2 bar BMEP, 2300 RPM) and Mode 11 (2.62 bar BMEP, 1500 RPM). We wanted to evaluate the effect on emissions of operating the engine at low power (near idle) in conjunction with the low NOx strategy. Specifically, we report on emissions of total hydrocarbon (HC), carbon monoxide (CO), NOx, particulates (PM), formaldehyde, acetaldehyde, benzene, 1,3-butadiene, gas phase polyaromatic hydrocarbons (PAHs) and particle phase PAHs from a DaimlerChrysler OM611 CIDI engine using a low NOx engine operating strategy at Mode 22 (1.0 bar BMEP and 1500 RPM). Mode 22 did produce some differences in emissions levels and aftertreatment performance for toxicologically relevant species compared to Modes 6 and 11. Further, uncontrolled step changes in these emissions were observed to occur at the low exhaust temperature of Mode 22. Nevertheless the emissions for Mode 22 with Fischer-Tropsch diesel fuel were generally consistent with Modes 6 and 11.