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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.

Premixed Lean Diesel Combustion (PREDIC) has very low NOx combustion because of early injection timing, for example, at -120 degrees ATDC; however, it has some problems. One problem is that so much fuel spray reaches the cylinder wall, which causes high HC emission and high fuel consumption. The other problem is that compression ignition timing control is difficult due to the dependence on the in-cylinder temperature. To solve these problems, an impingement spray system with two nozzles is attempted to obtain the spray increasing at the center of the combustion chamber instantaneously. This impingement spray system has two nozzles, which are located diagonally. Two sprays, one injected from each side injector, impinge each other at the center of the cylinder to create an air-fuel mixture.That is,this impingement spray system creates the air-fuel mixture by using the penetration of both sides of the sprays instead of early timing injection.