Modeling And Simulation Of Marine Dual Fuel Diesel Engine

Conventional marine diesel engines use diesel as fuel,and the exhaust gas generated during operation contains a variety of substances that are harmful to the atmosphere,including nitrogen oxides,fine particulate matter and sulfur oxides.With the increasingly stringent requirements of maritime conventions for ship exhaust emissions,it has become a mainstream trend to study new fuels for marine diesel engines.Natural gas,as a clean fossil energy,has the characteristics of low emission and low cost,thus entering people's vision.A dual-fuel diesel engine model using diesel and natural gas as fuel was established.The effect of fuel substitution rate on combustion performance of dual-fuel diesel engine is studied,the main research contents are as follows.The 8L51/60DF dual-fuel diesel engine produced by MAN is the simulation object.Firstly,the dual-fuel power generation diesel engine is divided into cylinders,inlet pipe,exhaust pipe,turbocharger,medium cooler and other subsystems,each subsystem is modeled by volumetric method,then each subsystem is connected according to a certain order,and finally the simulation model of dual-fuel diesel engine is constructed.The combustion model of dual-fuel diesel engine is established.The Wiebe function is used to represent the combustion exothermic rate of fuel,and the complex combustion law is simplified,and the combustion is divided into diesel combustion model and natural gas combustion model.According to the fuel substitution rate to adjust the proportion of diesel and natural gas into the cylinder,while burning,the combustion process of the dual-fuel diesel engine is composed of the combustion of the ignition diesel and homogeneous mixed gas.By simulating the different loads of the all-diesel model and the dual-fuel mode,the data are compared with the bench test,and the error is less than 5%,which verifies the correctness of the model.In the dual-fuel mode,the relationship between the injection advance angle and the burst pressure in the cylinder is obtained by simulating the same load and different injection starting point,and the burst pressure in the cylinder increases gradually with the increase of the advance angle of the injection oil.By simulating the same load and different substitution rate of dual-fuel mode,it is proved that the maximum temperature in the cylinder of dual-fuel diesel engine is lower than that of conventional diesel generator.It is proved that the use of dual-fuel diesel engine can effectively improve ship emission performance.