An experimental study of the high-load extension of a homogeneous charge compression ignition engine with gasoline and n-heptane

Abstract

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.