The performance and emissions of a single-cylinder natural gas fueled engine using a pilot ignition strategy have been investigated. Small diesel pilots (2–3% on an energy basis), when used to ignite homogeneous natural gas-air mixtures, are shown to possess the potential for reduced emissions while maintaining good engine performance. The effects of pilot injection timing, intake charge pressure, and charge temperature on engine performance and emissions with natural gas fueling were studied. With appropriate control of the above variables, it was shown that full-load engine-out brake specific emissions could be reduced to the range of 0.07–0.10 g/kWh from the baseline diesel (with mechanical fuel injection) value of 10.5 g/kWh. For this reduction, the decrease in fuel conversion efficiency from the baseline diesel value was approximately one to two percentage points. Total unburned hydrocarbon (HC) emissions and carbon monoxide (CO) emissions were higher with natural gas operation. The nature of combustion under these conditions was analyzed using heat release schedules predicted from measured cylinder pressure data. The importance of pilot injection timing and inlet conditions on the stability of engine operation and knock are also discussed.
Strategies for Reduced NOx Emissions in Pilot-Ignited Natural Gas Engines
Contributed by the Internal Combustion Engine Division of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received by the ICE Division October 2002; final revision received September 2003. Associate Editor: D. Assanis.
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Krishnan , S. R., Srinivasan , K. K., Singh , S., Bell, S. R., Midkiff, K. C., Gong , W., Fiveland , S. B., and Willi, M. (August 11, 2004). "Strategies for Reduced NOx Emissions in Pilot-Ignited Natural Gas Engines ." ASME. J. Eng. Gas Turbines Power. July 2004; 126(3): 665–671. https://doi.org/10.1115/1.1760530
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