Abstract
Six-stroke diesel engine proposed here has two combustion processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. However, soot emission increased due to weak swirl in combustion chamber at 2nd combustion process. In the previous study, in order to improve 2nd combustion, cam profile was changed to introduce the fresh air between 1st and 2nd combustion process. However, fresh air wasn't introduced into the cylinder at 2nd combustion process because of high cylinder pressure that was generated by 1st combustion. In this study, in order to introduce fresh air between two combustion processes, supercharging system was applied. And fuel injection ratio of 1st and 2nd combustion process was changed from original fuel injection ratio 8:8[mg/cycle] to 10:6[mg/cycle] or 6:10[mg/cycle]. As results, at 6:10[mg/cycle] with supercharging, soot, CO and NO emissions decreased due to introduction of fresh air into cylinder at 2nd combustion and low heat release rate of 1st combustion as compared with original fuel injection ratio.
