Abstract
By dividing combustion chamber, the homogeneous charge compression ignition (HCCI) combustion can be achieved the multi-stage. The combustion system has two parts of combustion chamber, one is small inside piston and the other is large. At first, ignition takes place in the small chamber inside piston, and then the burned gas ejected into the large chamber to ignite the mixture in the large chamber. This combustion system is promising to reduce maximum pressure rise rate so can be achieved high load operation without knocking. The 3D-CFD results have shown that over 50% (maximum 51.4%) of indicated thermal efficiency at IMEP 1.1 MPa operation with exhaust gas recirculation (EGR) and fueled with iso-octane and iso-octane mixed with ethanol 10vol.% and 15vol.% (E10 and E15, respectively).