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Controlled auto ignition combustion mode has become a topic of major interest in recent years, mainly due to its potential in achieving high thermal efficiencies combined with significant reductions in NOx and soot emissions. However, expanding the controlled operation over a wide range of speeds and loads is a significant challenge, which must be addressed to achieve commercial success. Control analysis to date has been done by developing models which are engine specific, such models often rely on extensive parameters which are to be experimentally identified. Moreover, these models were valid only for a narrow operating range. In this paper, a detailed mathematical model of an HCCI engine, which is fuel flexible and valid for a transitions in engine speed, is developed based on ideal gas laws and basic thermodynamics and conservation principles.

Combustion in HCCI engines depends on several parameters such as temperature, pressure, thermochemistry of the cylinder gases, etc. These variables affect the two significant combustion parameters: ignition timing and combustion duration. Controlling ignition timing and burn rate in such engines over a range of engine speeds and loads is an inherently challenging task. Existing single-zone HCCI engine-control models fail to accurately estimate the combustion parameters. Moreover, such models lacked the absolute dynamic control of all the valves. Although certain CFD based multi-zone models have been reported in literature, they are quite unwieldy for the development of fast and efficient HCCI-engine controllers. This paper outlines a physics-based two-zone model of an HCCI engine with an empirical mean burn duration model in order to better predict combustion parameters and facilitate controller development.