Combustion and Emission Behavior of Ethanol Fuelled Homogeneous Charge Compression Ignition (HCCI) Engine

The Homogeneous charge compression ignition (HCCI) is the third alternative for the combustion in the reciprocating engine. HCCI a hybrid of well-known spark ignition (SI) and compression ignition (CI) engine concepts and has potential of combining the best features of both. A two cylinder, four stroke, direct injection diesel engine was modified to operate one cylinder on the compression ignition by detonation of homogeneous mixture of ethanol and air. The homogeneous mixture of the charge is prepared by port injection of ethanol in the preheated Intake air. This study presents results of experimental investigations of HCCI combustion of ethanol at intake air temperature of 120°C and at different air-fuel ratios. In this paper, the combustion parameters, pressure time history, rate of pressure rise, rate of heat release, mean temperature history in the combustion chamber is analyzed and discussed. The HCCI operating region criteria is defined based on the cycle-to-cycle variation of indicated mean effective pressure (IMEP) and rate of pressure rise. The results presented in this study for air fuel ratio, which satisfies the HCCI operating region criteria. The results show that controlled HCCI combustion is possible with extremely low emission and high efficiency.