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 For years now, the industry, media and conferences on marine propulsion are putting a strong focus on gas as a marine fuel. One of the important enablers for the development of this concept from being accepted in a niche market in Norway to becoming a viable scenario for ECA-applications and even been taken into account for intercontinental traffic was the arrival of the dual fuel engine. The concept of being able to run on gas as a fuel while keeping the diesel fallback option for the case of gas supply shortage or problems with the more sophisticated engine and fuel system controls encourage ship owners to invest. For the time being, a kind of standard dual fuel engine concept has evolved for medium speed 4-stroke engines. There are of course important differences in the systems details, but the common features for a competitive dual-fuel engine today are gas supply via port-injection, AFR-control by the use of a wastegate and/or a compressor bypass valve, a pilot injection system for gas ignition, variable valve timing and in most cases an in-cylinder pressure measurement system supporting the engine control system. All these systems have their value for the engines capabilities, partly with no alternative at all, partly with advantages in terms of emissions and efficiency compared to alternative systems. And they have their cost. In a study conducted at Caterpillar different alternative and simpler dual fuel concepts were investigated in terms of engine performance and emissions on a testbed. Based on these results the overall profitability for the ship owner was analyzed looking at different market and application scenarios. Special attention was paid to the requirements of gas retrofits of vessels already in service. The results of the economic analysis depend heavily on the assumptions made for the fuel price development, especially on the price relation between liquid and gaseous fuels. But despite these strong dependencies, some basic lessons can be learned.

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 Gas engines have always been equipped with electronic controls that are vital for reliable start-up and safe operation with the non-standardized fuel gas. In the past, Engine Control Systems (ECS) were considered as external units. They kept speed, load and air-fuel ratio constant and prevented the engine from exceeding critical limits. Nowadays, high-end reciprocating engines are mechatronic systems whose properties are significantly determined by the ECS software. Therefore, most combustion developments and mechanical design changes involve additional software development. Some engine manufacturers spend considerable effort in developing their own control systems, others are seeking for appropriate cooperation partners. OpenECS describes a way of cooperation between an engine manufacturer and a control system supplier and integrator, granting the engine manufacturer direct access to the control code. As in combustion development, where it is quite common to consult external engineering companies with long experience and powerful development tools, the engine manufacturer has the choice to develop the software in-house or to use external experts. The OpenECS platform supports the PLCopen programming languages as well as MATLAB/SIMULINK code. In the last 10 years, various PLC (Programmable Logic Controller) manufacturers have established PLCopen as a standard for PLC programming in industrial automation. PLCopen offers interfaces to major professional software development tools for debugging, testing, documentation, source code management and tracking systems. Many classification societies require the use of such established tools to proof sufficient software quality. AVAT provides a large library of gas engine specific software modules for the control of the gas engine and its periphery. Among others, it includes synchronization and generator protection functions, built-in diagnostic tools for service engineers and well-tested communication drivers for the integration of various external units such as ignition systems. The development of a specific engine application program typically starts from one of the standard application programs which are available for different engine types. AVAT is ready to support engine manufacturers in any phase of the development or to take on full responsibility for the application.

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 In the past, technology transfer took place from large bore diesel engines to smaller diesel engines, e.g. in commercial vehicles and passenger cars. This transfer contained for instance supercharging technologies, commonrail injection as well as operating and combustion processes. But technology transfer also occurred in the field of exhaust gas treatment systems. The best example of this is the ammonia SCR technology which was initially introduced for large bore diesel engines in the late nineties of last century and represents nowadays the standard application for denitrification of exhaust gas in smaller diesel engines in order to comply to actual emission regulations. However, after this initial transfer of technologies the specific boundary conditions for on-road applications, i.e. the superior fuel quality as well as the faster development cycles and more strict emission regulations led to faster development and implementation of the transferred technologies. With that several technologies appeared such as high pressure common rail injection systems, EGR concepts as well as new exhaust gas treatment concepts. In the field of small diesel engines this contains diesel oxidation catalyst (DOC), NOx storage catalysts (NSC), ammonia SCR catalysts and coated particulate filter (CDPF) systems with additional DOC or SCR coatings. Furthermore the exhaust gas systems were completed with sensors and actuators in order to guarantee efficiency and reliability as well as emission monitoring. The functionality of a state-of-the-art exhaust gas system is based on closed loop control using model based approaches within the control algorithms instead of open loop control or operation based on fixed maps. Thus even the most stringent emission limits can be fulfilled with high reliability and limited system costs.

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 In this day and age, emission regulations such as GHG and NOx become gradually strict for marine engines. Premixed gas engine is in spotlight because of the advantage of its reduction on GHG and NOx emissions. In particular, lean premixed combustion technology has great potential to reduce NOx emission without an exhaust gas after treatment system, and it has been mostly developed in 4-stroke medium speed gas engines. On the other hand, to satisfy lean pre-mixture in 2-stroke low speed gas engines, there are the following technical difficulties to overcome because of its gas injection during scavenging period. (1) Gaseous fuel slipping through exhaust valve (2) Unexpected ignition due to contact with hot residual gas and gas mixture (3) Quick gas mixing is needed to inhibit abnormal combustion (pre-ignition, rapid combustion and end gas autoignition). Therefore, the technology concerning mixture formation is a key point for developing 2-stroke premixed gas fueled engines. This paper describes the mixture formation process and feasibility in 2-stroke lean premixed combustion gas engine by using CFD analysis and elementary test. Gaseous fuel is injected from the injectors mounted on the cylinder liner between the scavenging port and exhaust valve. The mixture formation process is investigated by CFD simulation and visualization experiment using 200 mm diameter acrylic cylinder. The CFD result shows that gaseous fuel jets in crossed swirl flow reach the cylinder center and mix with fresh air. The jet trajectory of CFD has good agreement with the visualization result. Optimization of injection timing can almost control non-contact with hot residual gas, and also minimize gaseous fuel slipping through exhaust valve. Furthermore, the effect of injection system on mixing process is studied by CFD simulation. The result shows that the scavenging port injection system, which gas nozzles are mounted on each scavenging port, improves mixing and in addition, optimizing swirl flow provides further mixing.

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 Since many years the reduction of emissions has been one of the major drivers of combustion engine design. After the implementation of Euro 6, IMO Tier III and various other local emission standards, now the focus lies on fuel efficiency and reduction of CO2 emissions. In the recent years, the engine operation conditions have been studied intensively and start-stop operation has been widely introduced to passenger car engines to further contribute to a further reduction of fuel consumption. This trend is now rolled out to larger engines and subject of further studies. However, CO2 emissions and fuel efficiency are linked and directly influenced by the internal friction of the combustion engine. Among other, a major part of this internal friction is coming from the crank train system, with all its mechanical and tribo-chemical interactions. Additionally to the engine operating conditions like full load, idle and start-stop, there are several factors influencing the internal friction of this tribo-system. Design factors like the number and width of bearings have a major influence on the potential reduction of friction. However, also the used lubricant viscosity and its interaction with the bearing surface influence the total friction of the crank train. The current trend towards reduced oil viscosity is reducing the hydrodynamic friction significantly, but also leads to an increasing share of mixed friction running conditions. These changed operating conditions may result in extreme cases in increased friction instead of a friction reduction, and together with the above described trend and more startstop cycles it may also result in a reduced bearing life. In order to fulfill the demands of the latest emission legislations there is a trend to low SAPS lubricant formulations (LowSAPS: lubricants containing low levels of sulphated ash, phosphorus and sulphur). The combination of the two trends in lubricant formulation, low SAPS and low viscosity, additionally seems to reduce the tribologic robustness of a journal bearing system. For a holistic picture on the potential of friction reduction in the crank train is not enough to look only on changing crank train design, operation conditions and oil viscosity. Additionally there will be a deeper focus on tribologic effects on friction reduction and lifetime of components. In this paper the amount of potential friction reduction based on simulation as a function of different operating conditions will be estimated. In the well-known ring-on disc tribotest set-up the mixed friction behavior of several bearing surfaces, like AlSn sputter bearings, polymer coated bearings and AlSn bimetal bearings and their tribo-chemical interactions with latest generation low viscosity, low SAPS lubricants will be compared. Additionally, we will introduce a new test set-up to show the tribologic interactions between bearing materials and lubricants also in the hydrodynamic regime. This new test set-up is an excellent complement to a deeper understanding of the tribo-chemical interactions of the crank train system, allowing the holistic estimation of the friction reduction potential of low viscosity, low SAPS oils together with lifetime estimations of the bearings. Finally, a new robust, start-stop capable low friction bearing material, which is able to maintain excellent bearing lifetime also under severe lubricant conditions will be introduced.

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 Engine and FIE manufacturers are facing an increased number of complaints on abnormal engine functioning related to internal diesel injector deposits (IDID). Possible consequences are increased emissions, rough engine running and misfiring due to impairments in the timing of the injector, modified injection quantities or sticking injector needles. Along with the introduction of new emission legislations regarding SOx and NOx it is expected that the risk of dysfunctioning may exacerbate for future marine diesel engine applications. On the one hand this is caused by more complex combustion processes utilized for IMO-TIER3 EGR-concepts by means of multiple injection strategies. These concepts rely on sophisticated common-rail injection systems which are, however, potentially more sensitive against injector internal deposits then conventional mechanical unit pump injection systems. On the other hand the introduction of substantially reduced sulfur oxide emission limits in the sulfur control areas (SECA) demand frequent changes of the fuel type, i.e. from HFO to MDO and back when entering and leaving SECAs unless SOx scrubbers are installed on the vessels. Changing the fuel can be accompanied with the fall out of specific insoluble fuel components because of mixture incompatibilities of the different fuel types followed by increased generation of deposits in the injection system of an engine. In order to understand the different processes implied, this work describes the basic mechanisms and influencing parameters on the formation of fuel related deposits. These results have been obtain from extensive experimental measurement campaigns, theoretical modelling of the fuel oxidation process and comparison with the literature. The experimental work implies laboratory scale tests as well as durability runs with real common-rail injectors at engine like conditions. Different analytical methods were applied to characterize the formed deposits on the test objects in order to validate hypothesized chemical pathways and their influencing factors. The majority of the presented work on the fundamental processes leading to deposit formation has been performed in the scope of the FVV-funded research projects “Alteration of fuel properties I-III”. Based on the findings, general recommendations are derived to control the formation of deposits. Considering marine engine conditions and typical fuel compositions these recommendations are specifically extended to marine applications.

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 In field operations, generating sets are often subject to highly fluctuating loading conditions and anomalous phenomena imposed on the generator by the electric grid. Examples of such events are unstable grids with possible short circuits, heavily varying loading in peaking power plants, or frequency fluctuations. On the other hand, in a marine operating environment, the internal grid of the vessel is rather small, also leading to highly fluctuating loading conditions, in particular in special applications. To ensure robust operation in such a harsh environment, testing has been traditionally the preferred validation methodology. However, with the continuous improvement of simulation tools, more and more complex systems are within the scope of virtual validation. A clear benefit of virtual validation of such transient loading conditions is the easy adaptability of the simulation also to hard-to-test loading conditions at very little cost. Thus the engine can be optimized always for the loading conditions of the final customer destination even before leaving the factory, guaranteeing fault-free operation from the beginning. The methodology described in this paper allows us to directly check the stress response of a given engine component due to a load fluctuation in the network with a multibody dynamics model coupled to an electric model of the generator and also a model of the electric grid. Additionally, by coupling the engine automation system to control the gas pressure given as an input to the multibody model, we can easily simulate transient phenomena, such as starting and stopping the engine. As a demonstrator, we present a multibody model of a generating set, including a model of the electric machine coupled to an automation model for controlling the firing pressure. With such a setup, we can demonstrate how the whole generating set responds to predefined network events, such as short circuits. The goal of this paper is to give the reader an introduction into the possibilities of coupling electrical and automation system models to flexible multibody dynamics to enhance and optimize the engine design for varying loading conditions.

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 The steady development of Diesel Engines in the scope of Marine and Power Engineering, focus on mainly two main targets – the simultaneous reduction of fuel consumption and exhaust gas emissions at low life cycle costs. Many new engine concepts have been developed in order to achieve the high market and emission requirements. One indispensable feature of future Diesel engines is a high performance Injection System, which allows to control the mixture formation and the combustion process precisely, in order to achieve the high-sophisticated consumption- and emission-goals. MAN Diesel & Turbo SE has a long history in developing and producing Conventional and Common-Rail Injections Systems for medium speed Diesel engines. In the future, especially in combination with exhaust gas aftertreatment systems, the control of the mixture formation in the combustion chamber, for example with multiple injections and variable injection timing, plays a major role for the Diesel Engine combustion process. Due to this reason, MAN Diesel & Turbo SE decided to develop a new modular Common Rail System with 2200 bar rail-pressure, the CR 2.2 – System. In this paper MAN Diesel & Turbo SE wants to show the main features of the new developed MAN CR 2.2 – System and give also a precise description of all the efforts and optimizations made during the engineering work. Beginning with a detailed hydraulical simulation analysis of the systems main concept and the injector layout, the paper will show performance test bench results, like the injection rate and highlight the possibility of stable multipleinjection events, which are needed to achieve further emission goals. From these simulation and test bench results, the benefits for the atomization-, mixture formation- and subsequently the combustion process will be shown and described. 2200 bar rail-pressure increases the fuel atomization process and subsequently the mixture formation. Unfortunately, Cavitation is also increased due to high fluid velocities. One major development goal is to optimize the cavitation in the nozzle and the whole injection system. To achieve a better understanding of cavitation formation, two-phase CFD Methods and CT – Scan Analysis for detailed nozzle cavitation prediction have been used during the development process. The optimization of nozzle fluid flow is a crucial development task to achieve high service life, and will be discussed in the paper. In order to evaluate the spray process and gain a better understanding of the atomization, optical investigations on the MAN Injection Spray Chamber have been carried out. The analysis of spray data, like penetration length and spray angle, allows the evaluation of the spray process as a function of geometrical nozzle parameters. The use of optical diagnostic methods during the development phase will be discussed and the results linked to engine mixture formation. The paper will also describe the performance tests of the CR 2.2 – Injection System on various test Engines. The MAN Diesel & Turbo SE tool chain contains, besides Single Cylinder Research Engine Tests, in-house engine test and field test with customer engines in real operation mode. The achieved results will be described and discussed. The paper will summarize the benefits of the new developed MAN CR 2.2 – Injection System compared to conventional injection systems and the well-established MAN CR 1.6 – Injection System, and will finish with an outlook of future developments. Powered

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 The abundance of natural gas in North America has driven natural gas prices to a relatively low price with respect to diesel fuel. The expectation is that diesel fuel prices will continue to fluctuate and rise in the future while natural gas prices will remain stable. Due to the expected long term price differential between diesel fuel and natural gas, there is an interest by the North American railroads in being able to burn natural gas in their existing diesel locomotive fleets. This paper will detail the technical hurdles and development of two dual fuel locomotives that were used for demonstration purposes on a class 1 North American railroad. The development started in early 2012 with Single Cylinder Engine (SCE) testing at the GE research facility in Niskayuna, NY. The SCE testing included feasibility studies, in-cylinder studies to maximize gas substitution rates, and an initial knock detection investigation. The development then progressed to Multi-Cylinder Engine (MCE) testing where the demonstrator engine control system was developed, detailed engine performance mapping was performed, knock detection and mitigation strategy was developed, and various engine hardware configurations were tested. The SCE and MCE optimization techniques and results will be discussed. The two demonstrator locomotives were built in 2013 and went through validation testing at the GE Transportation locomotive production facility in Erie, PA before being shipped to a Class 1 North American railroad for in-use testing in the spring of 2014. The in-use testing included performance testing at TTCI in Pueblo, CO to validate that overall locomotive performance was not impacted by dual fuel operation. After that, high elevation testing was performed in southern Colorado to identify any altitude impact on performance and then cold weather testing was performed in Minnesota and Wisconsin in early 2015. Mainline testing was then carried out on the southern trans-con between Barstow, CA and Kansas City, MO for the remainder of 2015. Results and lessons learned will be presented.

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 In addition to emissions and environmental pollution, the availability of fossil fuels is and will be one of the main questions for the world to solve. For Wärtsilä, combustion efficiency has been prioritized for several decades in the engine design to achieve low operational cost and secure compliance with emissions regulations. During the Nor-Shipping exhibition, the new Wärtsilä 31 engine platform was released, on 2 June 2015, to set a new industry standard for fuel consumption worldwide. The Wärtsilä 31 is designed for fuel flexibility with an engine platform consisting of three different products – a diesel engine, a gas engine, and a dual-fuel engine. In comparison with the competition, the specific fuel oil consumption has been lowered by 8 g/kWh, which has resulted in a new world record and registered in Guinness Book of World records. This paper will describe the benefits and customer values of the Wärtsilä 31 engine platform and outline the technologies that have been used to reach the set targets. More specifically, to reduce the life-cycle cost of the engine as well as minimize the environmental footprint, such as CO2 emissions, the thermal combustion efficiency was identified as one of the key factors. To further reduce the operational cost of the engine, a new maintenance concept has been taken into use with longer maintenance intervals and with shorter down-times. As marine solutions and applications tend nowadays to become more and more customer-specific, the flexibility has been another key priority. In particular, the Wärtsilä 31 engine has been designed to accommodate the utilization of a large variety of fuels and fuel qualities, both liquid and gas fuels, such as heavy fuel oil, marine diesel oil, low viscosity and low-sulphur fuels, liquefied natural gas, ethane gas, or petroleum gas. Moreover, in terms of operational flexibility, it has been essential to provide outstanding loading capabilities despite variations in the fuel quality. In conclusion, the Wärtsilä 31 engine platform is the world’s most advanced and efficient medium-speed four-stroke engine that has lifted the game to the next level for marine and power plant engines.