High Pressure Injection of Natural Gas in a Two Stroke Diesel Engine

Three methods of introducing gas into the DDC 8V92TA engine were evaluated: post-pilot in-cylinder injection; early in-cylinder injection just after exhaust valve closure; and port injection through an air inlet port.

Post-pilot injection consistently produced the best combustion and HC emissions.

Early in-cylinder injection often resulted in severe end gas knock, but gave higher thermal efficiency than diesel in some conditions. HC emissions were considerably higher than for post-pilot injection.

Port injection gave smoother combustion than early in-cylinder injection but higher HC emissions. Its full load thermal efficiency tell between, and part load efficiency below, the other methods.