Autoignition and combustion of n-butane/air mixtures in homogeneous charge compression ignition engine (effects of internal EGR on auto ignition and combustion)

In this study, effects of internal EGR ratio on the ignition and the combustion of homogeneous charge compression ignition (HCCI) engine are investigated experimentally. At first, using single cylinder test engine, relation between exhaust valve close timing and internal EGR (Exhaust Gas Re -circulation) ratio is clarified. Effects of an internal EGR gas on autoignition timing, combustion duration and knocking limits are discussed. As a result of an experiment, it became clear the following facts; with advancing exhaust valve close timing, i ) internal EGR ratio is increasing, ii) both knocking limits at high load and misfiring limits at low load are expanding, iii) ignition timing is advancing, iv) combustion duration is decreasing and v) combustion efficiency is increasing.