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A new reaction scheme for NOx production is incorporated into a steady state quasi-dimensional engine combustion simulation. The reaction kinetics includes 67 reactions and 13 chemical species, and assumes equilibrium concentration for all other chemical species. The General Engine SIMulation (GESIM) developed by Ford Motor Company is used to model the engine cycle. The new reaction scheme is a super-extended Zel'dovich mechanism (SEZM) which predicts NOx formation levels to within 10% of engine test data for several engines, whereas the 3 reaction, extended Zel'dovich mechanism (EZM) is shown to have errors of approximately 50% or more for similar conditions. Analytical engine mapping, under NOx constrained calibration, requires accurate modeling of NOx emissions over varying engine operating conditions.

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.