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Technical Paper

Oxidation Stability of Some Phosphorus - Free Fully Formulated Crankcase Oils

Legislation world-wide has made it necessary to find ways to control the level of engine emissions and reduce the damage to our environment. Increasing restrictions have made the elimination of zinc dithiophosphates from crankcase oils and increasing the effectiveness of catalytic converters viable options. Lead and phosphorus containing compounds in the exhaust are known catalyst poisons that shorten the life of current automotive catalysts. Unleaded fuel has successfully resulted in a reduction of harmful emissions due to the fuel. Current government and industry research is actively pursuing replacement of phosphorus additives with phosphorus free additives. Several phosphorus-free oils were developed and are evaluated in bench tests in this study. Test comparisons with phosphorus- containing oils demonstrated satisfactory oxidation stability and wear performance of the phosphorus free oils.
Technical Paper

Oxidation of 1-Butene and n-Butane at Elevated Pressures

The oxidation of 1-butene and n-butane in air at elevated pressure was investigated in a high pressure chemical flow reactor. Results are presented for pressures of 3, 6, and 10 atm, temperatures near 900K, and lean equivalence ratio. Gas samples were analyzed using gas chromatography with aldehydes sampled using a dinitrophenylhydrazine/acetonitrile procedure employing gas chromatography/mass spectrometry analysis. Major common products observed include CO, CH2O, C2H4, C3H6, and CO2. Additional major products included 1,3-C4H6 for 1-butene and 1-C4H8 for n-butane. Fuel conversion was increased with increased pressure, temperature, and equivalence ratio with 1-butene more reactive than n-butane. Large levels of lower molecular weight carbonyls resulted from 1-butene whereas significant amounts of conjugate and lower molecular weight alkenes resulted from n-butane. Trends in product distributions with increasing pressure were successfully accounted for by current autoignition theories.
Technical Paper

The Effect of Platinum Catalysts on Propane Oxidation at Elevated Pressure

The potential for catalytically enhanced ignition in low-heat rejection Diesel engines has been experimentally studied under engine simulated conditions in a high pressure chemical flow reactor. Results are presented for propane oxidation on platinum at 6 and 10 atmospheres, at temperatures from 800K to 1050K, and at equivalence ratios from 0.5 to 4.0. For turbulent transport rates which are typical of those in an engine, as much as 20% of the fuel was found to react on the catalyst before the onset of the gas-phase ignition reactions. Depending on the adiabaticity of the combustion chamber walls, this could lead to significant thermal enhancement of the gas-phase ignition process. Evidence of chemical enhancement was also observed, at 10 atm under very fuel rich conditions, in terms of a change in the concentration and distribution of the hydrocarbon intermediate species. Possible mechanisms for the observed chemical enhancement due to surface generated species are discussed.
Technical Paper

The Lean Oxidation of Iso-Octane | at Elevated Pressures

Experimental results are presented from plug flow reactor studies of the lean oxidation of iso-octane and compared to modeling results using a detailed kinetic mechanism. Two sets of experiments performed at 9 atm are presented: a temperature sweep from low temperature through the NTC region and temporal species profiles for an initial temperature within the low temperature regime. Species observed include C8 conjugate olefins, C8 cyclic ethers, acetone, acetaldehyde, iso-butyraldehyde, 2,2-dimethyl-propanal, iso-butene, propene, C7 olefins, and iso-butene oxide. In general the model predicts the overall trends observed in the experimental results, including the temperatures at which the NTC region begins and ends. However, it significantly over-predicts the extent of reaction in the low temperature regime.