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...

This study examines the possibility to provide control over ignition timing in a homogeneous charge compression engine (HCCI) using fuel additive whose molecular structure can be adapted upon exposure UV light. The molecule has greater influence on retarding than original molecule, hence time modulated expose new is referred as ‘smart fuel’. form of 1,3-cyclohexadiene (CHD), it undergoes electr...

In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and the compression ratio were varied and their influence on the pressure, the heat release and the ignition delays were measured. The inlet temperature was changed from 25 to 70 °C and the equiva...

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...

in this study, an in-house multi-dimensional code has been developed which simulates the combustion of n-heptane in a homogeneous charge compression ignition (hcci) engine. it couples the flow field computations with detailed chemical kinetic scheme which involves the multi-reactions equations. a chemical kinetic scheme solver has been developed and coupled for solving the chemical reactions an...

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...

In the context of modern engine control, one important variable is the individual Air Fuel Ratio (AFR) which is a good representation of the produced torque. It results from various inputs such as injected quantities, boost pressure, and the exhaust gas recirculation (EGR) rate. Further, for forthcoming HCCI engines and regeneration filters (Particulate filters, DeNOx), even slight AFR unbalanc...