Experimental and kinetic modeling study of the effect of fuel composition in HCCI engines

The chemical behavior of three different fuel surrogates, containing n-heptane, iso-octane, toluene, and 1-pentene, under HCCI conditions is analyzed. New experimental measurements of the in-cylinder composition have been carried out on a running HCCI engine equipped with a special customized cylinder head allowing the direct sampling of the gas. These data were compared with calculation obtained from a detailed kinetic mechanism coupled with a 1-D/quasi-D engine model. This model allows to study the autoignition and the combustion behavior of different fuel surrogates. After a preliminary analysis on the model parameters and of stoichiometry effect, the combustion chemistry of different fuel surrogates is discussed. Model calculations correctly reproduce the combustion behavior of the three surrogates. Moreover the parametric analysis allowed better interpretation of the engine measurements. The coupled approach adopted in this work showed to be suited to analyze the effect of different fuel formulation and help the synergistic development of both engines and fuels. Published by Elsevier Inc. on behalf of The Combustion Institute.