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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 Aromatics and Cycloparaffins on Dl Diesel Emissions

The effects of the chemical composition of Diesel fuels on emissions is a critical issue for future Diesel fuels and synthetic fuels. In order to understand these effects, a series of fuels prepared from blends of pure hydrocarbons were studied in a single cylinder, DI Diesel engine. The base fuel was a 2:1 mixture by volume of iso-octane and tetradecane with a Cetane number of 40.5. The additive compounds chosen for this study were 1-methylnaphthalene, tetralin, and decalin; each additive was blended into the base fuel at several concentrations so that the effect of the chemical compound on emission trends could be determined. To minimize changes in the combustion process, as fuel composition changed, the injection timing was varied in order to adjust for Cetane number differences between fuels. Comparisons were made on the basis of performance, regulated exhaust emissions, including CO, NOx UHC, and particulates, aldehyde emissions, and soluble organic fraction.
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

Chemical and Biological Character of Particulate Matter for a Variety of Oxidants in a Constant-Volume Combustion Bomb

Diesel engines are a source of suspended ambient particulate matter, and some concerns have been raised about the health effects from the inhalation of these particles. Nitrated polycyclic aromatics adsorbed on these particles have been shown to have the potential to cause mutations in living cells. Particulate matter collected on teflon-coated glass fiber filters produces results that may be open to question because of the possible generation of artifactual nitrated aromatics during the filtration process. An experiment using a constant-volume combustion bomb was used with four oxidants (air, nitrogen-free oxidant (29% O2 21% Ar 50% CO2), 50% O2/50% N2, and O2 (99.95% pure)), to address the concern over artifactual generation of nitrated-PAH on the filtration medium. Soot samples were collected both in situ on a cooled plug and on teflon-coated glass fiber filters in the exhaust line. Chemical comparisons of the collected samples were accomplished using chromatographic procedures.