Cyclic variability (CV) in lean HCCI combustion at the limits of operation is a known phenomenon, and this work aims at investigating the dominant effects for the cycle evolution at these conditions in a multi-cylinder engine. Experiments are performed in a four-cylinder engine at the operating limits at late phasing of lean HCCI operation with negative valve overlap (nvo). A combustion analysi...

Premixed or partially premixed compression ignition modes, such as homogeneous charge compression ignition (HCCI), have been a particular focus among researchers because of their potential to deliver enhanced fuel efficiency and meet exhaust emissions mandates without the addition of costly after-treatment technologies as currently required with traditional spark ignition (SI) and direct inject...

Abstract The characteristics of auto-ignition in HCCI engines in the presence of charge stratification is studied theoretically using activation energy asymptotics. Some preliminary results on the effects of mixture stratification on the duration of burning and the sensitivity of ignition delay to initial temperature are presented. The analysis accounts for the effects of pressure rise due to p...

Future internal combustion engine technologies require an accurate combustion monitoring and control. This can be performed through high frequency recordings of cylinder pressure. However, this solution is limited by the sensor cost and reliability. Another method consist in reconstructing combustion related variables from indirect measurements. In this paper, we propose a combustion indicator ...

homogenous charge compression ignition (hcci) is a mode of combustion in ic engines in which premixed fuel and air are ignited spontaneously. there is a belief that hcci engines have a great potential to improve fuel consumption and reduce nox emissions. in this study, a single zone, zero dimensional, thermo-kinetic model has been developed and a computer program with matlab software is used to...

By modulating engine valves to reinduct hot exhaust gas together with air and fuel, a clean and efficient form of autoignition can be created. Control of this combustion process, known as homogeneous charge compression ignition (HCCI), requires not only precise valve control but also a combustion control strategy that accounts for the cycle-to-cycle coupling through the exhaust. This paper outl...

This thesis deals with numerical simulations of the turbulent combustion process in Homogeneous Charge Compression Ignition (HCCI) engines. An accurate and computationally efficient Large Eddy Simulation (LES) model was developed and used throughout this thesis to investigate the development of in-cylinder turbulence, temperature stratification, onset of auto-ignition, and development of the re...

Ignition timing in Homogeneous Charge Compression Ignition (HCCI) engines is dominated by thermo-kinetic reactions that are dependant on the charge properties. A single zone thermodynamic model, coupled to a kinetic mechanism, is developed to predict the ignition timing of Primary Reference Fuels (PRFs) in an HCCI engine. The model, consisting of 120 chemical reactions and 58 species, is valida...

We present a computational tool to develop an exhaust gas recirculation (EGR) – air-fuel ratio (AFR) operating range for homogeneous charge compression ignition (HCCI) engines. A single cylinder Ricardo E-6 engine running in HCCI mode, with external EGR is simulated using an improved probability density function (PDF) based engine cycle model. For a base case, the incylinder temperature and unb...