Development of a phenomenological cycle simulation for a natural gas-fuelled, compression-ignited, internal combustion engine

Engine cycle simulations have been developed for modeling both diesel and dual fuel combustion in compression ignition engines. The primary objective of this work was to investigate the dual fuel combustion process in an engine and to better understand the processes of ignition, flame propagation, and pollutant formation in the engine.{09}A multizone diesel combustion model was first developed to predict the diesel combustion process and emissions for diesel fueling. A phenomenological combustion model for dual fuel operation was then developed to simulate the combustion process and emissions of a micro-pilot diesel ignition natural gas fueled engine.; Coupled with the chemical equilibrium reactions for emission formation (i.e., extended Zeldovich NO_x mechanism, soot formation and destruction submodeling, unburned hydrocarbon emissions submodeling), models for diesel droplet evaporation, air entrainment, cylinder heat transfer, piston work, mass flow rates, flame propagation, crevice flow, and flame quenching have been combined with a thermodynamic analysis of the engine to yield instantaneous cylinder conditions, engine performance, and emissions.; Parametric and comparison studies of diesel operation, dual fuel combustion, and micro-pilot combustion have been conducted. The major conclusions that can be drawn from this work include (1) diesel evaporation and air entrainment can have significant influence on the ignition and combustion processes, (2) pressure and temperature of inlet air, compression ratio, and the start of fuel injection are important engine operating and design parameters, (3) the combustion process of the mixture of natural gas and air is dominantly premixed-combustion, and (4) the processes of crevice flow and flame quenching can have a substantial impact on the dual fuel/micro-pilot combustion and emission formation processes.