Real Fuel Modeling for Gasoline Compression Ignition Engine 2020-01-0784
Increasing regulatory demand for efficiency has led to development of novel combustion modes such as HCCI, GCI, and RCCI for gasoline light duty (LD) engines. In order to realize HCCI as a compression ignition combustion mode system, in-cylinder compression temperatures must be elevated to reach the autoignition point of the premixed fuel/air mixture. 3D CFD combustion modeling is used to model auto-ignition of gasoline fuel under compression ignition condition necessitating the need for a gasoline fuel properties and chemistry model. Using the entire fuel consisting of thousands of components in the CFD simulations is computationally expensive. To overcome this challenge, the fuel is represented by few major components of the desired fuel. Real fuel modeling consists of modeling the physical properties (e.g. evaporation) using the spray model and the chemical kinetic properties (e.g. combustion) using the chemistry model.
In this study, 9 variations of gasoline fuel sets were chosen as candidates to run in HCCI combustion mode. The fuels differentiate in the number and concentration of components in their surrogate models, which are between 10 and 20 components. Initial modeling for the individual components used in 9 gasoline surrogate models showed alterations in prediction of the ignition delay time for a range of temperature between 700 K and 2000 K.
The spray model is constructed using a database consisting of 81-component physical surrogate components. Examples consist of 14-component gasoline, 21-component F-76 diesel, 5-component hydro treated renewable diesel (HRD) and 19-component Naphtha. Chemical kinetics of fuels will be modeled using a 55 chemical surrogate component database. A master mechanism developed for the database consists of integration of skeletal reaction mechanisms with 375 species and 1868 reactions.
A study detailing the development of a gasoline real fuel model was performed and various surrogates for gasoline fuel were investigated. The importance accurate prediction of fuel spray characteristics and wall wetting, auto-ignition and emissions for the HCCI combustion process under a wide range of operating conditions was stressed. The gasoline real fuel model will be used in subsequent CFD modeling activities for the development of an advanced mixed-mode combustion systems as part of the Department of Energy funded project.
Mayuri Wagh, Nahm Roh Joo, Philip Zoldak, Hyejun Won, Youngchul Ra, Yu Shi
Hyundai-Kia America Technical Center Inc., Michigan Technological University, Phillips 66