As part of the US-DOE`s on-going interest in the use of alternative automotive fuels, the University of Dayton Research Institute has been conducting research on pollutant emissions resulting from the combustion of candidate fuels. This research, under the direction and sponsorship of the NREL, has been concerned primarily with the combustion of compressed natural gas, liquefied petroleum gas (LPG), methanol, and ethanol. In the first 24 months of this program, studies of the oxygen rich, stoichiometric, and fuel-rich thermal degradation of these fuels in the temperature range of 300 to 1100{degrees}C at atmospheric pressure and for reaction times of 1.0 and 2.0 s were completed. Trace organic products were identified and quantified for each fuel as a function of temperature. The results of these studies agreed well with the results of tail-pipe emission studies in that the types and quantity of emissions measured in both the laboratory and engine tests were shown to be very similar under certain operating conditions. However, some chemicals were observed in the laboratory studies that were not observed in the engine studies and vice versa. This result is important in that it has implications concerning the origin of these emissions. Experiments concerning the NO perturbedmore » oxidation of methanol, M85, ethanol, and E85 indicated the presence of complex oxidation chemistry. At mild temperatures, NO addition resulted in enhanced fuel conversion. At elevated temperatures, an inhibitory effect was observed through increased yields of both partial oxidation and pyrolysis-type reaction products. Comparison of flow reactor product distributions with engine test results generally indicated improved comparisons when NO was added to the fuel. Analysis of secondary components of alcohol fuels resulted in some unexpected observations. Several previously unidentified species were observed in these experiments which may impact atmospheric reactivity assessments of these fuels.« less

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The origin of organic pollutants from the combustion of alternative fuels: Phase IV report

The objective of this project was to determine the impact of alternative fuels on air quality, particularly ozone formation. The alternative fuels of interest are methanol, ethanol, liquefied petroleum gas, and natural gas. During the first year of study, researchers obtained qualitative data on the thermal degradation products from the fuel-lean (oxidative), stoichiometric, and fuel-rich (pyrolytic) decomposition of methanol and ethanol. The thermal degradation of ethanol produced a substantially larger number of intermediate organic by-products than the similar thermal degradation of methanol, and the organic intermediate by-products lacked stability. Also, a qualitative comparison of the UDRI flow reactor data with previous engine test showed that, for methanol, formaldehyde and acetone were the organic by-products observed in both types of tests; for ethanol, only very limited data were located.

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P.H. Taylor

Papers

Impacts of alternative fuels on air quality