Reduction of NOx Emission in Medium-Speed Diesel Engines

The authors systematically conducted experiments for determining the present levels of NOx emission from small-size, high-speed to medium-size, medium-speed diesel engines. The effects of various control factors on NOx emission were investigated through experiments and simulating calculations on the engines to find the factors that lower NOx levels.

As a result, it has been found that the reduction in NOx without degrading the specific fuel consumption can be achieved by injection timing retarding and properly increasing the compression ratio and air boost pressure to maintain the Pmax, which decreased by timing retarding, of the design point.