Study On The Modeling And Simulation Of Dual Fuel Marine Engine Of LNG Carrier

In recent years,the limitation of MARPOL Convention on the emission of pollutants from ships is becoming more and more severe.Natural gas is the ideal cho-ice for alternative fuels in the internal combustion engine,which has the advantages of abundant reserves,low cost,high energy density and green environmental protection.Based on Wartsila 9L34DF dual fuel engine,the working principle of Wartsila 9L34DF was introduced,and the Wartsila 9L34DF fuel and gas supply system and working modes were analyzed.Calculation model of Wartsila 9L34DF was established by using one-dimensional simulation software of AVL BOOST,including cylinder model,combustion model,heat transfer model,turbocharger model and pipeline model etc.Referring to the real ship equipment specifications,the detailed parameters of each module were disposed.Under the condition of constant speed,the simulation of the fuel and gas mode was carried out,and the model is verified.The simulation results show that the simulation error of the Wartsila 9L34DF model is small,and the simulation results coincide with the actual law of the engine.The dynamic performance of the engine was simulated by AVL BOOST and Matlab.The software interface of AVL BOOST and Matlab is realized by configuring the simulation environment.The engine simulink control mode was built in matlab,and two simulation constrained conditions were set by changing the gas supply cycle upper limit range.Under different conditions,the dynamic joint simulation of the engine was finished.Through the analysis and calculation of the curve of the joint simulation,it is concluded that the optimal AF ratio of the engine is 19.1 under the 750rpm and the 100%load mode.The steady state simulation model based on AVL BOOST is easy to build up,the speed of calculation is very fast,and the simulation results are convenient to analysis.In addition,the joint simulation of AVL BOOST and Matlab can make up for the defects of AVL BOOST to dynamic simulation.In this paper,the simulation and modeling ideas can provide a theoretical basis for the design and optimization of dual fuel engine,and can be used for modeling and simulation of engine performance.