Since the economical crisis was recognised worldwide in the autumn of 2008, owners have been looking into cost savings, such as slow steaming and optimised low-load operation with turbocharger cut-out, exhaust gas bypass, etc. This has led to research into optimised propulsion efficiency, available propeller sizes and possibilities regarding stroke size for crankshafts. The result is now known as the G engine series, including the G/40/45/50ME-B9.3, G60/70/80ME-C9.2, S30ME-B9.3 and S90ME-C9.2. With the G engine series, a new generation of superlong-stroke engines has been introduced to the market and, in many cases, a new design of the aft ship is needed to fully utilise the low revolutions of these engines. However, the interest in the new engines is very high, and firm orders have already now been received for 7, 9, 10, 11 and 12-cylinder S90ME-C9.2 engines, 6 and 7-cylinder G80ME-C9.2 engines as well as 6G70ME-C9.2, 5 and 6-cylinder G60ME-C9.2 engines and 6G50ME-B9.3. One of the present goals in the marine industry is to reduce CO2 emissions from ships and, therefore, to reduce the fuel consumption for ship propulsion to the widest possible extent at any load. This goes hand in hand with the focus on fuel cost savings, including the newly introduced variable exhaust valve timing for ME-B9 engines. This new system will improve the part load fuel consumption for the ME-B engines, and they will be designated ME-B9.3. Furthermore, the newly introduced Energy Efficiency Design Index (EEDI) will also have an impact on future ship development and engine design. One possible solution to improve the EEDI for a ship is to optimise the aft body and hull lines of the ship, including bulbous bow and operation in ballast condition - making it possible to install propellers with a larger diameter and, thereby, obtaining higher propeller efficiency at a reduced propeller speed. As the two-stroke main engine is directly coupled to the propeller, the introduction of the super-long-stroke G engine series with an even lower-than-usual shaft speed will meet this target. This paper will deal with the overall design platform for these engines, which is mainly based on the service experience as well as production experience with the 80ME-C9 and 35-50ME-B9 engines. Furthermore, dedicated design requirements in order to be able to operate with, for instance, the biggest strokebore ratio ever of 5 for the G40/45 and G50-ME-B9.3 engines will also be described. Similar to the situation with the S80ME-C9 and 35/40ME-B9, the new G engine series are only offered as electronically controlled versions so as to obtain the lowest possible fuel oil consumption at all loads as well as optimising NOx emissions. However, if needed, the G engines can be delivered as MC-C engines on request.


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    Title :

    State-of-the-art MAN B&W Two-stroke Super-long-stroke Engines


    Contributors:


    Publication date :

    2013


    Size :

    11 Seiten, 30 Bilder


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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