Comparison of Analytically and Experimentally Obtained Residual Fractions and NOX Emissions in Spark-Ignited Engines 982562
Using a fast-sampling valve, residual-fraction levels were determined in a 2.0L spark-ignited production engine, over varying engine operating conditions. Individual samples for each operating condition were analyzed by gas-chromatography which allowed for the determination of in-cylinder CO and CO2 levels. Through a comparison of in-cylinder measurement and exhaust data measurements, residual molar fraction (RMF) levels were determined and compared to analytical results. Analytical calculations were performed using the General Engine SIMulation (GESIM) which is a steady state quasi-dimensional engine combustion cycle simulation. Analytical RMF levels, for identical engine operating conditions, were compared to the experimental results as well as a sensitivity study on wave-dynamics and heat transfer on the analytically predicted RMF. Similarly, theoretical and experimental NOx emissions were compared and production sensitivity on RMF levels explored. A new heat transfer algorithm is developed which produced favorable agreement between the experimental and analytical RMF measurements. Improved NOx predictions were similarly observed over varying operating conditions using the super-extended Zel'dovich mechanism (SEZM) in conjunction with the new heat transfer algorithms. The SEZM produces NOx emissions within 10-15% of experimental data, while errors by more than 40% are obtained using the extended Zel'dovich mechanism (EZM).
Citation: Miller, R., Russ, S., Weaver, C., Kaiser, E. et al., "Comparison of Analytically and Experimentally Obtained Residual Fractions and NOX Emissions in Spark-Ignited Engines," SAE Technical Paper 982562, 1998, https://doi.org/10.4271/982562. Download Citation
R. Miller, S. Russ, C. Weaver, E. Kaiser, C. Newman, G. Davis, G. Lavoie
Ford Motor Company
International Fall Fuels and Lubricants Meeting and Exposition
SI Engines: Combustion and Emission Formation-SP-1393, SAE 1998 Transactions - Journal of Fuels and Lubricants-V107-4