Yoann Viollet

Numerical Simulations of Hollow-Cone Injection and Gasoline Compression Ignition Combustion With Naphtha Fuels

We acknowledge the help and support from Saurav Mitra and Sarangarajan Vijayraghavan from Convergent Science, Inc. (CSI). This work was sponsored by the Fuel Technology Division at Saudi Aramco R&DC. The work at King Abdullah University of Science and Technology (KAUST) was funded by KAUST and Saudi Aramco under the FUELCOM program.

Effects of In-Cylinder Mixing on Low Octane Gasoline Compression Ignition Combustion

This work was sponsored by the Fuel Technology Division at Saudi Aramco R&DC. The surrogate formulation work at King Abdullah University of Science and Technology (KAUST) was supported by KAUST and Saudi Aramco under the FUELCOM program. We also acknowledge the helpful discussions with Janardhan Kodavasal from Argonne National Laboratory.

Standardized Gasoline Compression Ignition Fuels Matrix

Direct injection compression ignition engines running on gasolinelike fuels have been considered an attractive alternative to traditional spark ignition and diesel engines. The compression and lean combustion mode direct injection of fuel eliminates throttle losses yielding higher thermodynamic efficiencies and the better mixing of fuel/air due to the longer ignition delay times of the gasoline-like fuels allows better emission performance such as nitric oxides (NOx) and particulate matter (PM). These gasoline-like fuels which usually have lower octane compared to market gasoline have has been identified as a viable option for the gasoline compression ignition (GCI) engine applications due to its lower reactivity and lighter evaporation longer ignition delay characteristics compared to diesel and lighter evaporation compared to gasoline fuel. The properties, specifications and sources of these GCI fuels are not fully understood yet because this technology is relatively new. In this work, a GCI fuel matrix is being developed based on the significance of certain physical and chemical properties in GCI engine operation. Those properties were chosen to be density, temperature at 90 volume % evaporation (T90) or final boiling point (FBP) and research octane number (RON) and the ranges of these properties were determined from the data reported in literature. These proposed fuels were theoretically formulated, while applying realistic constraints, using species present in real refinery streams gasoline-like fuels. Finally, three-dimensional (3D) engine computational fluid dynamics (CFD) simulations were performed for using the proposed GCI fuels and the similarities and differences were highlighted.

Numerical Simulations of Hollow Cone Injection and Gasoline Compression Ignition Combustion With Naphtha Fuels

Gasoline compression ignition (GCI), also known as partially premixed compression ignition (PPCI) and gasoline direct injection compression ignition (GDICI), engines have been considered an attractive alternative to traditional spark ignition engines. Lean burn combustion with the direct injection of fuel eliminates throttle losses for higher thermodynamic efficiencies, and the precise control of the mixture compositions allows better emission performance such as NOx and particulate matter (PM). Recently, low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and lighter evaporation compared to gasoline fuel [1]. The feasibility of such a concept has been demonstrated by experimental investigations at Saudi Aramco [1, 2]. The present study aims to develop predictive capabilities for low octane gasoline fuel compression ignition engines with accurate characterization of the spray dynamics and combustion processes. Full three-dimensional simulations were conducted using CONVERGE as a basic modeling framework, using Reynolds-averaged Navier-Stokes (RANS) turbulent mixing models. An outwardly opening hollow-cone spray injector was characterized and validated against existing and new experimental data. An emphasis was made on the spray penetration characteristics. Various spray breakup and collision models have been tested and compared with the experimental data. An optimum combination has been identified and applied in the combusting GCI simulations. Linear instability sheet atomization (LISA) breakup model and modified Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) break models proved to work the best for the investigated injector. Comparisons between various existing spray models and a parametric study have been carried out to study the effects of various spray parameters. The fuel effects have been tested by using three different primary reference fuel (PRF) and toluene primary reference fuel (TPRF) surrogates. The effects of fuel temperature and chemical kinetic mechanisms have also been studied. The heating and evaporative characteristics of the low octane gasoline fuel and its PRF and TPRF surrogates were examined.Copyright