Combustion Improvement of a Premixed Charge Compression Ignition Methanol Engine using Flash Boiling Fuel Injection 2001-01-3611

A premixed charge compression ignition methanol engine targeting a drastic decrease in NOx emissions and a brake specific energy consumption equivalent to that of a DI diesel engine has been developed ⁽¹⁾. The problems of this combustion system are that the brake thermal efficiency decreases, and CO and THC emissions increase due to a deterioration of high load combustion. The purpose of this study is to improve the high load combustion of a premixed charge compression ignition methanol engine using a flash boiling fuel injection technique.

The results of this study have shown that the premixed charge compression ignition methanol combustion system using a flash boiling fuel injection technique increases the brake thermal efficiency, decreases CO and THC emissions, while maintaining low NOx emissions in the high load region. The reason may be that heating the fuel prior to injection causes flash boiling to occur, and the spray penetration is reduced, so that a suitable mixture is formed in the cylinder. With regard to the performance of the premixed charge compression ignition methanol combustion system using flash boiling fuel injection, the NOx emissions were cut by over one half, and the brake specific energy consumption was superior than that of a conventional diesel engine, at high loads. Particularly, when the brake specific energy consumption was 10 MJ/kWh at high load operation, NOx emissions decreased to as low as 3 g/kWh.