The Effect on Engine Performance and NO Emissions of a Two-Stage Expansion Cycle in a Spark Ignition Engine

This paper presents the development of an engine simulation program for SI engines and its application to a two-stage expansion cycle.

The two-stage expansion analysis is performed using the engine simulation, where a sudden expansion much faster than the normal expansion takes place during the expansion stroke. The changes in NO emissions and knock tolerance of the resulting new engine cycle are investigated for the same compression ratio. The changes in NO emissions and specific fuel consumption through increasing the compression ratio in order to return to the same amount of work done within the cycle are also studied.