Technical Paper
A Three-Zone Heat Release Model for Combustion Analysis in a Natural Gas SI Engine. -Effects of Crevices and Cyclic Variations on UHC Emissions
2000-10-16
2000-01-2802
A thermodynamic analysis based on a pressure-time history measured during the combustion in a SI engine is a commonly used tool used for analyzing the combustion process. Both one-zone and two-zone models have been applied for this purpose. One of the major sources of the emission of unburned hydrocarbons from SI engines is the presence of crevices in the combustion chamber where a part of the unburned fuel-air mixture is trapped during the compression and the combustion. In this paper a three-zone heat release model including the effect of crevices is presented. The model is based on a thermodynamic analysis of three connected zones consisting of burned gas, unburned gas and gas trapped in crevices. Engine experiments have been carried out on a natural gas SI engine. The results from these experiments have been analyzed by the model.