Numerical simulation of carbon monoxide emissions from spark ignition engines

This work describes a numerical model for calculation of carbon monoxide (CO) emissions from spark ignition engines. The model calculates CO concentration from a kinetic mechanism and from the equilibrium combustion equation. A computer program that simulates the cycle of spark ignition engines performs the CO model calculations. The model was validated against experimental data from a single-cylinder research engine and from a production multi-cylinder engine. The varied parameters were air/fuel ratio, load and engine speed. From comparison with calculated equilibrium concentration, it is shown that CO should be modeled by chemical kinetics for better agreement with measured exhaust values.