Mixture Formation During Cold Starting and Warm-up in Spark Ignition Engines

A thermodynamic analysis of mixture formation in cylinders that takes into account mixture inhomogeneity and the wall film is presented.

Conditions for obtaining low hydrocarbon emission are clarified analytically as a function of the fuel mass of the wall film and inhomogeneity of the mixture.

Optimum processes for atomizing and vaporizing fuel are presented to reduce the inhomogeneity and the fuel mass of the film.