Single-zone Thermo-kinetic Modeling of Direct Injection Homogeneous Charge Compression Ignition (DI-HCCI) Engines

Homogeneous charge compression ignition (HCCI) is an advantageous combustion concept in terms of efficiency and pollutant emissions. However, its limited operating range suppressed its successful utilization. One applicable method to use this concept is to combine it with other combustion strategies. Direct fuel injection into the combustion chamber is an applicable strategy aiming at this target. To make this concept an applicable one for engines, there should be validated models both for performance prediction and control applications. Single zone models are good and rapid performance predictors and can be used in control applications. Due to the intrinsic characteristics of HCCI being a kinetically controlled combustion, chemical kinetics should be incorporated in modeling it. Therefore, in this study a stand-alone single-zone thermo-kinetic model is developed and validated against experimental measures. Since the main assumption of the developed model is the immediate vaporization of the injected liquid fuel, the validity of the model confirms the idea which states that in the case of early direct fuel injection, in-cylinder combustion can be regarded as HCCI. Furthermore, the results show good agreement with the measurements. The model predicts combustion phasing within 0.5 crank angle degrees while engine power is estimated with an acceptable accuracy of 90 percent.