A Computationally Efficient Method for the Solution of Methane - Air Chemical Kinetics With Application to HCCI Combustion

The Rate-Controlled Constrained-Equilibrium (RCCE) method is applied to the numerical solution of methane-air combustion. The RCCE method offers a reduction in computation time for complex chemically reacting systems because the rate equations for a small number of slowly evolving constraints need to be solved. The current work focuses on presenting both the principles of the RCCE method and its application to methane-air Homogeneous Charge Compression Ignition (HCCI) combustion. This work takes into consideration some of the previously unexplored numerical issues associated with solving the RCCE equation set. Application of the RCCE method is first demonstrated in constant and variable volume adiabatic environments and compared to the integration of the full set of kinetic rate equations for each species. Results presented here show a reduction in computational time. For large molecules, which require larger chemical mechanisms, it is expected that the computational time associated with the RCCE method should continue to improve over direct integration. The latter part of this work uses a thermo-kinetic HCCI model coupled with the RCCE method to simulate the combustion process in a methane-fueled internal combustion engine operating under HCCI conditions. This is the first known application of this method to HCCI simulations. Results are compared in light of HCCI experiments.