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Title:

Energy Management for Large-Bore, Medium Speed Diesel Engines

Document type:
Konferenzbeitrag
Contribution type:
Textbeitrag / Aufsatz
Author(s):
Kudicke, R.; Wachtmeister, G.; Knafl, A.; Stiesch, G.
Abstract:
In an environment of ever rising fuel prices and stricter emission regulations, manufacturers of large-stroke medium speed diesel engines need to discover new ways to reduce the fuel oil consumption and the overall costs of their systems. As fuel efficiency has always been the major goal, those engines convert a large percentage of the chemical energy into mechanical energy. Unused fuel energy leaves the combustion chamber as waste heat and enthalpy of 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 Universität München (TUM) has been 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 the environment. With the introduction of two-stage turbocharged engines, the heat load and the complexity of 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 has shown 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 disadvantages of each system? The cooling water and lubrication oil systems are crucial for a safe operation of the engine. However, there exists a trade-off between fuel consumption on the one hand and reliability on the other hand. Smaller coolant and oil flow rates require less pumping power but at the same time the maximum heat load of the cooling system is reduced. A deeper knowledge about these systems’ behavior will help to further close the gap to the optimum of the trade-off in the future. For the simulation two different tools have been used in this project. The engine is modeled and simulated in GT-Suite (Gamma Technologies Inc.). Dymola (Dassault Systems) based on the open multi-physical modeling language Modelica, is used for the cooling system. Different cooling systems for large-bore medium speed diesel engines were modeled, simulated and analysed. The simulations were validated using measurement data provided by MAN Diesel & Turbo. The results of the simulation at different stationary load points are discussed, considering the application (marine propulsion, power generation, etc.) and environmental conditions (e.g. temperature and humidity). 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 temperature levels will be shown in a variation of the coolant and lubrication oil temperatures. A profound understanding of the components, their dependencies and interactions is important for a system optimization. This knowledge will make it possible to further narrow design margins, the dimension of heat exchangers and to use smaller pumps. This will improve the overall system’s efficiency.
Book / Congress title:
27th CIMAC Wolrd Congress 2013
Organization:
CIMAC
Congress city:
Shanghai
Year:
2013
Quarter:
2. Quartal
Language:
en
Semester:
SS 13
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