In this study we summarize and analyze experimental observations of cyclic variability in homogeneous charge compression ignition (HCCI) combustion in a single-cylinder gasoline engine. The engine was configured with negative valve overlap (NVO) to trap residual gases from prior cycles and thus enable auto-ignition in successive cycles. Correlations were developed between different fuel injecti...

A miniature homogenous charge compression ignition (HCCI) free-piston engine compressor aimed at an ankle-foot orthosis application is described. Analysis of the human ankle shows that a fluid power source in the neighborhood of 10 W is needed. To account for compressor and actuator inefficiencies, the power output at the engine cylinder is designed to be 30 W. A compact engine compressor packa...

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...

The present work investigates the performance and emission characteristics of hydrous methanol fuelled Homogeneous Charge Compression Ignition (HCCI) engine. In the present work a regular diesel engine has been modified to work as HCCI engine. Hydrous methanol is used with 15% water content in this HCCI engine and its performance and emission behavior is documented. A spark plug is used for ass...

An on-the-fly mechanism reduction approach is employed in this paper to integrate detailed chemical kinetics with a computational fluid dynamics (CFD) code. The reduction methodology employs an instantaneous element flux analysis to identify redundant species and reactions for given local conditions. The emphasis of this work is focused on the numerical study of homogeneous charge compression i...

Homogeneous Charge Compression Ignition (HCCI) is an advanced combustion strategy that able to reduce nitric oxides (NOx) emissions and increase fuel efficiency simultaneously. This study investigated the effects of premixed kerosene fuel on the auto-ignition characteristics in a light-duty compression ignition engine. A partial HCCI engine was modified from a single cylinder, four-stroke, dire...

The present study uses a numerical model to investigate the effects of flow turbulence on premixed iso-octane HCCI engine combustion. Different levels of in-cylinder turbulence are generated by using different piston geometries, namely a disc-shape versus a square-shape bowl. The numerical model is based on the KIVA code which is modified to use CHEMKIN as the chemistry solver. A detailed react...

Fuel efficient Homogeneous Charge Compression Ignition (HCCI) engine combustion phasing predictions must contend with non-linear chemistry, non-linear physics, period doubling bifurcation(s), turbulent mixing, combustion deposits, model parameters that can drift day-to-day, and air-fuel mixture state information that cannot typically be resolved on a cycle-to-cycle basis, especially during tran...

Combustion in homogeneous charge compression ignition (HCCI) engine is controlled auto ignition of well-mixed fuel, air and residual gas. Since onset of HCCI combustion depends on the auto ignition of fuel/air mixture, there is no direct control on the start of combustion process. Therefore, HCCI combustion becomes unstable rather easily especially at lower and higher engine load. Charge strati...