Modeling of Spray Combustion for the Prediction of Nitric Oxide Emission from Large-Sized Marine Diesel Engines

A new model of spray combustion with a flame boundary and two NO formation regions was developed in order to predict NO emission from large marine diesel engines. The basic prediction characteristics were studied by using the actual engine specifications and several parameters such as a droplet initial diameter, a fuel injection period, and a flame angle. The simulation could show the change of chemical species composition in the inside and outside of a spray during their combustion. As a result, it was found that this model predicts that the NO formation is frozen after the end of combustion, and the flame angle influences the NO exhaust rate and the thermal efficiency more sensitively than the other parameters.