Optimal Utilization of Air- and Fuel-Path Flexibility in Medium-Speed Diesel Engines to Achieve Superior Performance and Fuel Efficiency
With the development of common rail fuel injection systems, variable geometry turbochargers, variable valve timing and combustion feedback systems, medium speed diesel engines offer substantial control flexibility with the potential of significantly improving performance, fuel economy, emissions and thus customer value. Engine performance - traditionally governed solely by the mechanical system - is increasingly dependent on the interaction of the flexible subsystems and their proper control. This paper seeks to demonstrate the benefits offered by variable air-path control in combination with a fully flexible common rail fuel injection system. System interactions and optimization are analyzed and performed with design of experiment (DoE), response surface modeling and constraint merit functions. Above-mentioned method is applied to design custom tailored medium speed engine maps for constant speed generator, controllable pitch as well as fixed pitch propeller operation. Engine performance data are obtained via enginedynamometer experiments augmented with analytical simulations. With constant speed generator operation, it is shown that through optimizing the engine calibration in accordance to the typical load profile thereof, specific fuel oil consumption is reduced by several grams without related engine-hardware changes. The potential of applying engine-control maps specifically tailored to the mode of operation e.g. fast steaming, slow steaming or maneuvering operation is assessed and the potential quantified. This so-called multi-mapping approach allows for improved performance and reduced emissions over the entire operating regime of the engine. In addition to steady state operation, benefits in transient response are demonstrated by means of optimized air- and fuel-path control. Particularly load rejection and smoke emissions are substantially improved over conventional, mechanically rigid systems. Lastly the effect of Tier III exhaust gas treatment solutions - selective catalytic reduction (SCR) to reduce oxides of nitrogen (NOx) and / or scrubbers to capture sulfur oxide (SOx) - on engine performance is investigated. It is shown that Tier III exhaust gas treatment systems may adversely affect engine performance through increased exhaust gas backpressure. By means of optimally adjusting the engine control strategy to the new boundary conditions, it is demonstrated that engine performance and efficiency are restored to Tier II levels.
Alexander Knafl Stiesch Gunnar Markus Friebe
MAN Diesel and Turbo SE,Germany
国际会议
上海
英文
1-11
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）