A comprehensive engine to drive-cycle modelling framework for the fuel economy assessment of advanced engine and combustion technologies

Abstract

A comprehensive engine to drive-cycle modelling framework has been developed for evaluating fuel economy improvements of new engine technologies. The framework comprises three key components: (a) full engine system models and routines for the generation of engine performance and fuel consumption maps; (b) an improved experimental heat release analysis and model calibration tool, which was created by coupling an in-house heat release analysis program to an engine cycle simulation, and which can be used for model calibration and validation when experimental data are available; and (c) an integrated vehicle modelling and drive-cycle simulation platform for fuel economy assessment. The framework implementation has been demonstrated through a fuel economy study of three engine and combustion technologies: a conventional spark-ignition (SI) engine, a high compression ratio SI engine with early intake valve closing (EIVC), and a homogeneous-charge compression ignition engine (HCCI) employing a recompression valve strategy, used in dual-mode SI-HCCI operation. Simulation results for three drive cycles indicate potential fuel economy gains of the order of 7–11% for the high-compression EIVC SI engine and 7–21% for the dual-mode HCCI engine configurations. Further analysis of the latter, however, reveals frequent mode switching and short excursions in the HCCI region, which could be a challenge during practical implementation, and potentially result in reduced fuel economy gains.