Visualization And Performance Analysis Of Gasoline Homogenous Charge Diesel Induced Ignition

The wide use of internal combustion engines has greatly propelled the development of the human society, while it also brings the worldwide problems like energy crisis and environment pollution. To increase the efficiency is always a target of the engine engineers. Based on the point to increase the combustion efficiency of gasoline, a combustion mode names Homogenous Charge Induced Ignition (HCII) including its combustion and emission characteristics was discussed in this paper.First of all, the reasons why the combustion efficiency of gasoline engines is lower than diesel were analyzed theoretically. Based on the results of literatures, the reason why HCII might enhance the efficiency of gasoline was also clarified. In this paper, the combustion images of HCII mode were taken on an optical engine through high-speed photographing. The results show that: the induced ignition phenomena can be observed; with a certain low diesel amount, as the increase of gasoline/diesel ratio, the ignition delay increase, the ignition position extends from the center towards the periphery of the combustion chamber, and the combustion velocity increases; the number of the injector holes is also an affective factor, the more it is, the more sufficient the combustion does. The performance of HCII was also examined on a modified four-cylinder turbo-charged diesel. The results show that: at high loads, HCII can enhance the combustion efficiency of gasoline comparable to diesel; NOx emission is lower and smoke can be greatly reduced to near zero level. The analysis of pressure process and heat release ratio shows that HCII has a higher initial heat release and shorter combustion duration than traditional gasoline engines. PM emission and its SOF ratio were also examined through a PM sampling instrument and extraction method. The results show that: HCII can greatly reduce the PM emission at high load, while the increase of SOF causes a high PM level at low load. The high THC and CO emission, and deterioration of fuel consumption at low load should still be studied.