Modeling And Simulation Of Marine Low-Speed Diesel Engine With Waste Heat Recovery System

The proportion of the fuel cost share of the transport cost has become increasingly high with the international oil price rise rapidly, saving energy and reducing emission have become an inevitable trend in the development of the ship building industry. In order to alleviate the greenhouse effect, reduce CO2 emissions, adapt the newly amended International Maritime Organization (IMO) Energy Efficiency Design Index (EEDI) rules, we must take effective messures to ensure optimal utlisation of the fuel used for main engines on board ships.Through analysis of the situation of the development of marine diesel engine at home and abroad, the waste heat recovery technology of the two-stroke heavy-duty marine diesel engine has become a research hotspot in the field of ship. WHRS not only utilizes the main engine exhaust gas energy, but can also utilize the energy in the jacket-cooling water,improving the overall energy efficiency of ships. On the basis of comprehensive analysis of the marine diesel engine waste heat recovery technology development and research achievements at home and aborad, this paper determines the research program of the waste heat recovery system based on the MAN 6S50ME-C8.2, then builds a simulation model for the waste heat recovery system.Based on a detailed analysis of the diesel engine working process, a filling and emptying simulation mode of the 6S50ME-C8.2 marine diesel engine has been established in the Matlab/Simulink platform. According to the propulsion characteristics of the 6S50ME-C8.2 diesel engine, we can verify the simulation mode based on test data. The result shows that simulation results agree well with the experimental value approximately. In other words, the simulation model is very accurate. In order to improve the thermal efficiency of the waste heat recovery system, with no loss of the dynamic characteristic and fuel economy of the marine main engine, we can add the exhaust bypass module and establish the marine diesel engine simulation model of the waste heat recovery system by adjusting the injection timing,exhaust timing and wastegate amount. In the steady-state condition and the transient condition of the system, we can complete the simulation calculation analysis. The result shows that the actual operation of diesel engine can be simulated well, the exhaust gas temperature increases,which can help the waste heat boiler make full use of the energy in the exhaust gas, thereby the energy utilization of the entire vessel can be improved.In this paper, based on the function and feature of each module, dynamic simulation model of the waste heat boiler has been established by using modularization model.According to the waste heat recovery system links between modules, we can complete the overall system simulation model. At last,in order to verify the accuracy of the system,the steady-state performance and dynamic characteristics of the waste heat recovery system has been studied with the change of the diesel engine loads.The research results of this paper can provide reference for the design of the waste heat recovery system, and lay the foundation for the research of the system control strategy.