【作者】

Jöran Ritzke

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC大会上发表，论文的版权归CIMAC所有。ABSTRACT Nowadays the ship is still the most important means of transportation for goods of the globalized trade. Due to increasing demands concerning NOx and SOx emissions, cost of operation and efficiency the large marine engines as the main propulsion system of these ships require a consistent development. One approach are dual-fuel operated engines which offer a variety of advantages in respect thereof. An ongoing research project at the University of Rostock, funded by the Federal Ministry of Economic Affairs and Energy, investigates innovative approaches regarding this topic. It combines 0/1D and 3D CFD techniques with a focus on modelling the detailed kinetic of the specific chemical reactions. The 0/1D simulation is used as a more general approach to model the overall system of the large engine including the intake and exhaust manifolds, the turbocharger and the cylinder with its auxiliary parts, each in terms of reduced models. This allows for the calculation of the boundary conditions for the 3D CFD models in a fast manner. It is also possible to obtain results of certain parametervariations, e.g. valve timing, within reasonable time. A second part is the investigation of the complex chemical reaction mechanisms of the dual-fuel combustion. In a first attempt the flame speed of burning methane at relevant temperatures and pressures is addressed and leads to a wellgrounded estimation of the flame spread speed. Another important aspect is the ignition delay. Due to the lack of experimental and theoretical data of the interaction between methane and the diesel pilot spray at the relevant conditions the ignition delay is modeled by a mechanism for n-heptane as a reference fuel for diesel and acts as the pilot fuel. Thus existing mechanisms are adapted and combined to fulfill the requirements of a capable dual-fuel mechanism taking into account the flame speed and ignition delay. The main task of the 3D CFD simulation is the calculation of the Cold-Flow within the power unit of the engine thus focusing on a small part of the intake and exhaust manifold and the combustion chamber. These calculations are combined with a detailed reaction mechanism of the dual-fuel combustion of natural gas ignited with a diesel pilot spray and will be validated with experimental results from a test rig of a large single cylinder research engine regarding cylinder pressure, rate of heat release and certain emissions. Finally this leads to a better understanding of the complex processes of dual-fuel fluid mechanics and combustion and therefore can support an optimized development of next generation dual-fuel engines. The authors would like to present first results in each section of this complex topic.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

2

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