Premixed Lean Diesel Combustion (PREDIC) using Impingement Spray System

Premixed lean Diesel Combustion (PREDIC) provides low NOx, however, it has some challenges associated with high HC emission, high fuel consumption and difficult timing control of compression ignition. To solve these problems, an impingement spray system with two injectors was tested to obtain positional controllability and larger volume of the air-fuel mixture formation in our previous study. The positional controllability means mainly the fuel mixture formation is the center of the cylinder with some space from the cylinder wall. The larger volume means the fuel mixture formation is leaner air-fuel mixture than that of free spray, which results in a possibility of higher thermal efficiency. Thus, the impingement spray system has a possibility of HC reduction and fuel consumption improvement in PREDIC.

In this study, we applied this system to PREDIC using a heavy-duty single cylinder engine with two injectors to evaluate the effects of injection timing, boost pressure and injection pattern etc. It has a possibility to reduce CO and HC by split injection pattern without increasing NOx.