【作者】

Robert Kudicke,Georg Wachtmeister

【摘要】

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。In an environment of ever rising fuel prices and stricter emission regulations, manufactur-ers of large-stroke medium speed diesel engines needto discover new ways to reduce the fuel oil consumption and the overall costs of their systems. As fuelefficiency has always been the major goal, those engines convert a big percentage of the chemical energy into mechanical energy. Unused fuel energy leaves the combustion chamber as waste heat and enthalpyof the exhaust gases. This paper will focus on the engine's heat transfer from the combustion chamber into the surrounding parts and the cooling system. For a better understanding of the cooling systems a research project with MAN Diesel & Turbo SE and the Institute of Internal Combustion Engines(LVK) at the Technische Universitaet Muenchen(TUM) was initiated. The overall goal is to analyse and understand the heat transfer from its origin during the combustion via the engine block and cooling system to theenvironment. With the introduction of two-stage turbocharged engines the heat load and the complexityof the cooling systems will increase. The knowledge of the cooling system's behavior is essential, to face this challenge in the near future. An analysis of three large-bore diesel engines with a similar cylinder geometry and shaft power showed three different topologies of the cooling system. From this analysis the following question was deduced: Why are different topologies used and what are the technical advantages and drawbacks of each system? The cooling andlubrication oil systems are crucial for a safe operation of the engine. However, there exists a trade-off betweenfuel consumption on the one hand and reliability on the other hand. Smaller coolant and oil flow rates re- quire less pumping power but at the same time the maximum heat load of the cooling system is reduced.A deeper knowledge about the system's behavior willhelp to further close the gap to the optimum of the trade-off in the future. For the simulation two different tools are used in this project. The engine is modeled and simulated in GT-Suite(Gamma TechnologiesInc.). For the cooling system Dymola(Dassault Systems) based on the open multi-physical modeling language Modelica is used. Different cooling systems for large-bore medium speed diesel engines were mod-eled, simulated and analysed. The simulations werevalidated using measurement data provided by MAN Diesel & Turbo. The results of the simulation at different stationary load points considering the application (marine propulsion, power generation, etc.) and envi-ronmental conditions(e.g. temperature and humidity) are discussed. The paper will show the influence of the topology of the cooling water and lubrication oil systems on heat exchanger and pump size. At high temperatures energy can be used more efficiently and heat exchanger surface areas can be reduced. But the temperature level also affects the engine's heat transfer. So the influence of the cooling water and lubrication oil temperature on the friction and the heat transfer from the cylinder to the cooling fluids needs to be taken into account. The effect of different temperaturelevels will be shown in a variation of the coolant and lubrication oil temperature.A profound understanding of the components, their dependencies and interactions is important for a system optimization. With thisknowledge it will be possible to further narrow design margins, the dimension of heat exchangers and to use smaller pumps. This will improve the overall system's efficiency.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

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