Effect of Mixture Preparation on Combustion of Gasoline HCCI Engine

Homogenous Charge Compression Ignition (HCCI) combustion has beenregarded as a promising technology to realize a reciprocating engine with high thermalefficiency and low environmental impact. HCCI combustion engines are characterizedby use of a premixed gas phase charge, unthrottled operation, high compression ratio,and mixture auto-ignition. In this thesis, a practical experiment is used to study theeffect of mixture preparation on gasoline HCCI combustion under more controlledparameters.To carry out the experiment, a specific intake system has been designed andinstalled in a small single cylinder engine to analyze the effects of intake airtemperature, air fuel ratio and EGR composition on characteristic combustion andemission. The engine used to carry out this experiment is modified from a Yamaha XC-125M engine. The cylinder head is originally designed for a spark ignited, port fuelinjected engine. The compression ratio is increased from 10.3 to 14.3 by using a largerpiston and a cylinder liner adaptor bolted onto the block. With the intake system setup,different compositions of mixture preparation are allowed to be established.