1990 Volume 25 Issue 5 Pages 306-317
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 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 not so much 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.
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 NOx. And nitrogen content in fuel is also needed to take into account.