Effects of Gas Composition on Engine Performance and Emissions. Topical Report,January 1990-December 1991

摘要

The use of natural gas as a fuel for internal combustion engines that are used inhighway transportation applications presents several engine and vehicle design problems. One of the main concerns is whether a fuel specification is needed to accommodate the special requirements that these vehicle applications create. The objective of this project was to determine the role of gas composition on the performance and emissions from natural gas fueled engines. A special gas mixing and control system was developed to supply blends of pure gases to a single cylinder research engine. A statistically designed test matrix of 31 gas mixtures was used to develop relationships between the composition and the knock resistance, measured as methane number, of the gas mixture. The range of composition of the test gases was selected to be representative of natural gases found in the United States. An abbreviated test matrix of six gas mixtures was used to examine the effects of composition on the performance and emissions. The results showed that the direct chemical effects of composition on the combustion process and the emissions were secondary to the effects caused by the corresponding variations in stoichiometric air-fuel ratio. The measurements were performed at different representative equivalence ratios and operating conditions.