A Control-Oriented Two Zone Thermo-Kinetic Model of a Single Cylinder HCCI Engine

Over the past two decades, homogeneous charge compression ignition engine technology (HCCI) has aroused a great deal of interest in the automotive sector owing to its ability to generate ultra-low exhaust emissions and to be fuel-flexible. The current work proposes a control-oriented two-zone thermo-kinetic model of such a single cylinder HCCI engine. Earlier control laws were derived by using single zone mathematical models of HCCI combustion; however, these models fail to accurately capture the combustion dynamics of an HCCI engine owing to the assumption of homogeneous composition and temperature in the cylinder. Certain multi-zone models of HCCI engines emphasizing the shortcomings of these single zone models have also been reported in literature. However, such models are far too complex and unwieldy for the development of fast and efficient controllers for HCCI engines. The present work outlines the modeling approach of a single-cylinder two-zone HCCI engine by incorporating the first law of thermodynamics and the temperature and concentration inhomogeneities. The results showed good conformity to those obtained from literature-based multi-zone models. A comparative analysis between the single zone and two-zone models, in the context of predicting cylinder pressures, exhaust gas temperatures, emission concentrations, and start of combustion (SOC), is also discussed.