Six Stroke Engine

Six Stroke Engine

Abstract

Diesel engines have wide range of utilization for automobiles, locomotives & marines and co-generation systems. However, large problem is still related to undesirable emission.
To improve exhaust emissions from DI diesel engines, a new concept of Six Stroke Engine has been proposed. This engine has a second com¬pression and combustion processes before exhaust pro¬cess.
As the fuel in one cycle was divided into two combus¬tion processes and the EGR effect appeared in the sec¬ond combustion process, the decreased maximum cylinder temperature reduced NO concentration in the exhaust gas It was further confirmed that soot formed in the first combustion process was oxidized in the second combustion process .Therefore, a six¬ stroke DI diesel engine has significant possibilities to improve combustion process because of its more control¬lable factors relative to a conventional four-stroke engine.
Since the cylinder temperature before the second combustion process is high because of an increased temperature in the first combustion process, ignition delay in the second combustion process should be shortened. In addition, typically less desirable low cet¬ane number fuels might also be suitable for use in the second combustion process, because the long ignition delays of these fuels might be improved by increased cyl¬inder temperatures from the first combustion process.
Methanol was chosen as the fuel of the second combustion. The cetane number of methanol is low and it shows low ignitability. However, since methanol will form an oxidizing radical (OH) during combustion, it has the potential to reduce the soot produced in the first combustion process.