Numerical Modeling of the Ignition Process of a HCCI Engine With Reduced Chemical Mechanisms

A numerical simulation of ignition process for propane/air and heptane/air mixtures are conducted on an homogeneous charge compression ignition (HCCI) engine. The objective of this work is to obtain reduced chemical mechanisms of these fuel mixtures and to test their effectiveness on software based on Finite Element Method (FEM). Reduced mechanisms instead of detailed fuel mechanisms will allow future simulations in 2 and 3 dimensions of HCCI engines without using complex computer equipment. In this investigation, a kinetic chemistry code (CHEMKIN) was used to reduce detailed chemistry mechanisms. This study let reduce a propane mechanism from 46 reactions to 35 reactions. On the other hand, the heptane mechanism was reduced from 55 to 33 reactions. In both cases, the pressure-temperature interval ranks were obtained. Then the FEM based software was used and the reduced chemical kinetics was incorporated to simulate a zero-dimensional HCCI engine. For the numerical model, the mass and energy equations with heat generation due to ignition were included. The results of the numerical simulation on the FEM based software show that temperature and ignition times are equal to the CHEMKIN results, which is widely recognized in the combustion field like reference in process calculation with chemistry reactions.