Real-time evaluation of a detailed chemistry HCCI engine model using a tabulation technique

A storage/retrieval scheme has been implemented for a Stochastic Reactor Model (SRM) for Homogeneous Charge Compression Ignition (HCCI) engines which enables fast evaluation in transient multi-cycle simulations. The SRM models combustion, turbulent mixing, and convective heat transfer during the closed-volume part of the engine cycle employing detailed chemical kinetics. In contrast to previously developed storage/retrieval techniques which tabulate chemistry only, our method stores, retrieves, and interpolates output quantities of the entire internal combustion engine model, i.e. the SRM. These quantities include ignition timing, cumulative heat release, maximum pressure rise rate, and emissions of CO, CO2, unburnt hydrocarbons, and NOx, as functions of equivalence ratio, octane number, and inlet temperature for instance. The new tool is intended to be used for performing a variety of otherwise exceedingly expensive computational tasks such as multi-cycle multi-cylinder simulations, transient operation and control, optimization of engine operating parameters, design of experiments, and identification of parameters for achieving stable HCCI operation over a wide range of conditions. Using transient control as an example, we show that, when coupled to a commercial 1D CFD engine modelling package, the tabulation scheme makes such simulations feasible and convenient.