In order to meet the pollutant emission targets, set by the International Maritime Organization (IMO), an increasing number of ships using Liquefied Natural Gas (LNG) as fuel have been put into service. However, de-fossilized fuels such as green Methanol and Hydrogen are also getting more and more into focus. In this context, many shipowners are particularly interested in the dual-fuel large engine technology, which enables ships to operate with both natural gas and conventional liquid fuels. The advantages of these engines can be fully exploited by a variable compression ratio (VCR) system, which improves efficiency at part-load operation for the premixed combustion with LNG, while allowing overall efficiency to be maintained in Diesel mode, if required. Therefore, a VCR system is a technology that enables fuel flexibility in large engines with respect to low pollutant emissions and fuel economy benefits. This paper presents an innovative VCR connecting rod design for modern dual-fuel large bore engines which adapts the piston position by changing the effective connecting rod length. The VCR connecting rod was developed by the Chair of Thermodynamics of Mobile Energy Conversion Systems of the RWTH Aachen University together with FEV Europe GmbH. It features a novel functional principle inside the connecting rod’s small eye specifically tailored to the boundary conditions of large bore engines. The system includes an advanced hydraulic circuit combining the function of a hydraulic freewheel, the oil supply for piston cooling and a mechanical locking device for both compression ratios. With results of comprehensive simulation & test studies, the layout of the system is presented. The paper includes CAE and test results of the mechanical and hydraulic components. Studies on the switching process between the two compression ratios and the position of the fixed compression ratio position during engine operation are shown. This provides a deeper system understanding and identification of critical operating conditions.
Variable Compression Ratio System for Next Generation Large Bore Engines - Latest Development Results
Proceedings
International ATZ Conference ; 2022 ; Wiesbaden, Deutschland April 05, 2022 - April 06, 2022
2024-06-30
19 pages
Article/Chapter (Book)
Electronic Resource
German
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