An Experimental Study of Homogeneous Charge Compression Ignition (HCCI) with Various Compression Ratios, Intake Air Temperatures and Fuels with Port and Direct Fuel Injection

A promising approach for reducing both NO_x- and particulate matter emissions with low fuel consumption is the so called homogeneous charge compression ignition (HCCI) combustion process. Single-cylinder engine tests were carried out to assess the influence of several parameters on the HCCI combustion. The experiments were performed both with port fuel injection (PFI) and with direct injection (DI) under various compression ratios, intake air temperatures and EGR-rates. Special emphasis was put on the fuel composition by using different gasoline and diesel fuels as well as n-heptane. Besides engine out emissions (CO₂, CO, NO, O₂, HC, soot) and in-cylinder pressure indication for burning process analysis, the combustion itself was visualised using an optical probe.