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In a port fuel injection engine, Optimized kinetic process (OKP) technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55?C, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

With a combination of dual-fuel injection and exhaust gas recirculation or intake air temperature control to retard the homogeneous charge compression ignition combustion phase, the potential of expanding the homogeneous charge compression ignition load range was investigated. The experimental work was carried out on a real-time control dual-fuel homogeneous charge compression ignition operation test bench, which was based on a four-cylinder optimized kinetic process engine. It was observed that, with gasoline and n-heptane injection, the acceptable ranges of the exhaust gas recirculation rate and the intake air temperature were enlarged, and the load range of the homogeneous charge compression ignition engine was expanded. The intake air flow quantity can be raised by reducing the intake air temperature, and the indicated thermal efficiency of homogeneous charge compression ignition can be increased by utilizing sufficient n-heptane in the fuel. Compared with exhaust gas recirculation, intake air temperature control might be a better method to improve the indicated thermal efficiency of homogeneous charge compression ignition combustion. Also, from the viewpoint of deterioration in the emissions, exhaust gas recirculation is a better strategy for load expansion in homogeneous charge compression ignition with a high ratio of gasoline to fuel.