Effect of inlet temperature and equivalence ratio on HCCI engine performance fuelled with ethanol: Numerical investigation

Abstract

A numerical model is presented to investigate the performance of homogeneous charge compression ignition (HCCI) engines fueled with ethanol. Two approaches are studied. On one hand, two-step reaction mechanisms with Arrhenius reaction rates are implemented in combustion chemistry modeling. On the other hand, a reduced mechanism containing important reactions of ethanol involving heat release rate and reaction rates compatible with experimental data is employed. Since controls of combustion phenomenon and ignition timing are the main issues of these engines, the effects of inlet temperature and equivalence ratio as the controlling factors on the operating parameters such as ignition timing, burn duration, in-cylinder temperature and pressure of HCCI engines are explored. The results show that the maximum predicted pressures for thermodynamic model are about 71.3×10⁵ Pa and 79.79×10⁵ Pa, and for chemical kinetic model, they are about 71.48×10⁵ Pa and 78.123×10⁵ Pa, fairly comparable with corresponding experimental values of 72×10⁵ Pa and 78.7×10⁵ Pa. It is observed that increasing the initial temperature advances the ignition timing, decreases the burn duration and increases the peak temperature and pressure. Moreover, the maximum temperature and pressure are associated with richer mixtures.

Keywords

HCCI engine / ethanol / two-step reaction mechanism model / chemical kinetic model

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