ディーゼル機関のNO_x低減

抄録

The authors systematically conducted experiments for determining the present levels of NO_x emission from small-size, high-speed to medium-size, medium-speed diesel engines. The effects of various control factors on NO_x emission were investigated through experiments and simulating calculations on the engines to find the factors that lower NO_x levels.
As a result, it has been found that the reduction in NO_x without degrading the specific fuel consumption not so much can be achieved by injection timing retarding and properly increasing the compression ratio and air boost pressure to maintain the P_max, which decreased by timing retarding, of the design point.
Furthermore, it has been found that the influences of ambient conditions such as ambient temperature, humidity and intake air temperature have to be taken into account for evaluating NO_x. And nitrogen content in fuel is also needed to take into account.