1-D simulation of HCCI engine performance using knock-integral ignition prediction with Wiebe function combustion modeling, and comparison to advanced SI engine performance

A study of the fuel consumption benefits of Homogeneous Charge Compression Ignition (HCCI) engine operation has been done using GT-POWER 1-D engine simulation software. A port fuel injection spark ignition engine model was used as a starting point for making modifications to create an HCCI model by implementing a negative valve overlap breathing scheme and a simple knock-integral ignition timing and Wiebe combustion model based on the in-cylinder conditions at a 2000 RPM and 2 bar BMEP test point. Simulations run over a wide range of valve timing schemes produced a range in which brake specific fuel consumption from this HCCI engine are expected to fall. Further variations of the base PFI SI model were also developed to explore the fuel consumption benefits of other competing current or near production-ready technologies aimed at improving fuel consumption, and the simulation results of these models at the same load and speed test point were compared with those of the HCCI model. These models included variations on variable cam phasing, direct injection, intake valve throttling, and lean combustion. In the SI simulations, results showed expected decreases in BSFC as model complexity was increased. The HCCI simulations showed further reductions in BSFC, and the improvements fell very much in line with published experimental HCCI data. It was shown that simple model modifications can enable the use of GT-POWER for effective approximate results for HCCI operation.