NOx Reduction in Natural Gas RI Augmented Large Bore Four-Stroke SI Engines 2011-26-0005

A preliminary study is made of the effectiveness of internally generated “Radical Ignition (RI) species” for NOx reduction in a NG (natural gas) Spark-Ignition (SI) 4-stroke test engine operating under lean fuel conditions at a typical SI compression ratio. The study includes both experimental and simulation analysis components. Investigated in this study is the potential for augmenting SI using a controlled presence of these RI species. The aim of their use is to lower the heat required for flame propagation under leaner than otherwise attainable fuel conditions. This lowers the NOx production. The primary generating site for these species is a set of passive mini-chambers located within the cylinder head. A modified single cylinder SI engine is used for the experimental studies. The simulation involves the chemical-kinetics of 32 species and 97 chemical reactions: solved simultaneously within the mini and main chambers as these chambers interact with each other, with the engine housing and with the manifold (exchanging energy, momentum, mass and chemical species). The study suggests that significant NOx reductions can be accomplished.