This research has been conducted to investigate the impact of chemical properties of gasoline on engine-out emissions, especially for the emissions of nitrogen oxides (NOx), through engine experiments using fifteen types of gasoline (model fuels) and the engine combustion analysis. Numerical simulations have also been conducted on the formation of nitrogen monoxide (NO) using the extended Zeldovich mechanism for a detailed analysis of the impacts of fuel properties on emissions, which including the analysis performed from the fundamental view-point of the formation mechanism of NO. The research reveals that concentrations of engine-out NOx emissions significantly vary by the type of fuels, which can be organized by two parameters: a parameter represented by adiabatic flame temperature and a parameter indicating the 50% combustion point which is determined from the experiment results. And the results of the numerical simulations indicate that these parameters are determined to represent the factor of thermodynamic characteristics of fuels and that of the changes in combustion duration caused by fuels, respectively, so that the numerical simulations serve to support the validity of the experiment results.
