Effects of homogeneous charge compression ignition (HCCI) control strategies on particulate emissions of ethanol fuel.

Abstract

This thesis presents a systematic investigation into the formation of particulate matter in homogeneous charge compression ignition (HCCI) engines. These engines are representative of the emerging generation of low sooting engine technology. Early research in the field concluded that engines operating with this combustion strategy could offer Diesel like efficiency while simultaneously reducing emissions of particulate matter and the oxides of nitrogen to nearly negligible levels. While quantification of gas phase emissions has changed little through modern regulatory history, the metrics defining particulate emissions and the state of understanding of the research community are rapidly evolving. Advances in technology for characterizing particulate emissions from spark ignition and compression ignition engines have been applied to HCCI emissions and the results indicate the production of significant quantities, by both number and mass, of particles from the HCCI combustion strategy. A relationship has been identified between in-cylinder behavior, and both gaseous and particulate emissions. It has been shown to be valid for 2 different fuels and multiple engine loads. Characteristics of the particulate matter suggest it is formed via gas to particle conversion, or nucleation, of the lighter distillates from the engines lubricating oil.