论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。Engine designers and engine builders are striving to establish reliable and economical measures to have their engines meet the IMO NOx regulation Tier ll, which is coming into force in 2016, requiring a drastic level of NOx reduction from ships and needing in fact a different technology from those for previous Tiers I or ll. In order to ensure to provide ships with main engines complying with contemporary regulations even in/after the year 2016, Hitachi Zosen Corporation, who is not only an engine builder but also a catalyst manufacturer as well as an SCR manufacturer well-known in land applications, have developed a marine SCR system for large two-stroke diesel engines in collaboration with MAN Diesel & Turbo, an engine designer leading the market. The concepts of the system are (1) urea-SCR, (2) SCR located upstream turbine and(3) SCR operated on ordinary HFO. This paper presents mechanism and features of the system and test results from the testbed and the sea trial. Main themes are how such an SCR system works on a large two-stroke diesel engine run on HFO, of which exhaust gas generally is low temperature and contains a considerable amount of sulfur oxides, and how such an engine is controlled even in low load and/or transient conditions. The system ensures always high enough exhaust gas temperature to do SCR of high sulfur exhaust gas without utilizing any extra heating device, which consumes extra fuel, by making use of so-called ' cylinder bypass'. In low load conditions, a part of the scavenging air bypasses the cylinders and SCR line through the cylinder bypass line, and hence hot exhaust gas to the SCR. In transient conditions, the SCR bypass is controlled so as to charge the cylinders with an appropriate amount of scavenging air as necessary. This makes engine's quick acceleration possible. All these functions are automatically controlled. A number of various tests were performed not only in their SCR research laboratory but also with an actual product engine equipped with the SCR system on a testbed at Hitachi Zosen's engine factory in order to confirm that their technology was applicable also to marine-use and optimize it for marine application. After the successful tests on testbed, both the engine and the SCR system were transferred to install into a new-built ship, on board which the SCR system were intended to be field-tested in service, with the geometrically same SCR arrangement as well as the same control system as those for the testbed. The sea trial was performed to confirm that the engine with SCR functioned correctly and safely even in an actual ship system, and to measure and record its initial conditions before her delivery. During the sea trial, transient responses were tested in various cases, e.g.accelerations, decelerations, maneuverings and ahead/astern, and confirmed them as expected beforehand. Similar to the testbed results,80% of NO, reduction ratio was achieved, and IMO's E3-cycle value of NOx emission was confirmed to be less than 3.4 g/kWh, which is the limit for low speed engines, also in the sea trial.

论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。Fuel economy is more and more important for diesel engines. Emission levels become more and more stringent. To fulfill stringent emission levels，a common rail system is mandatory. Fuel economy yields for a zero static leakage common rail system. Additional to this two requirements, manufacturing costs should be as low as possible. According to this requirements a common rail system, mainly consisting fuel injector and high pressure pump, was designed, built and tested. Because of costs, the injector uses a solenoid actuator. As usual, the solenoid is about 20 mm in diameter. For smaller engines the slim body of the injector does not allow to place the solenoid near the injection nozzle. To avoid static leakage, the injector has a central fuel bore only. This means the injector needle is completely surrounded by pressurized fuel. The needle is very long to reach the on the top placed solenoid. This length can cause friction problems due to misalignment caused by manufacturing imperfections. To enhance the acceptance of manufacturing imperfections,a flexible needle was invented. This invention keeps manufacturing costs low and minimizes injector to injector deviations. To keep costs regarding high pressure fuel pump as low as possible, the pump is fuel lubricated. Fuel lubrication additionally minimizes the over all costs of the whole engine. The pump has a very simple crank drive with a so called race ring. This race ring is sitting on the eccentric part of the crankshaft. The plunger feet is rolling directly on this race ring. Except for the plunger spring, there is no need for an additional part transforming revolutions into strokes. The pump owns two plungers. This is the minimum number of plunger to make sure the pump is capable of delivering fuel all the time. The pump is designed for high speed, e.g.4000 rpm. If the engine builder uses this potential, the pump can be designed smaller and with less weight, which also improves fuel economy of the whole engine. High speed pumps also cause smaller pressure fluctuations. A further advantage. The tests and measurements of the components showed a good injection behavior for the injector and a high efficiency regarding high pressure fuel pump.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The IMO Tier 3 regulation will apply to ships constructed on or after 1st January 2016, operating in Emission Control Areas (ECA). The Tier 3regulation requires an 80% NOx emission reduction compared with IMO Tier 1. SCR (Selective Catalytic Reduction) and EGR (Exhaust Gas Recirculation) are expected to be the most feasible NO, reduction technology. SCR reduces NOx using catalysts and is well-known technology for land use. Mitsui Engineering and Shipbuilding Co., Ltd. (MES) has already established SCR technology to comply with NOx Tier 3. However, the catalyst reactor seems to be rather large as marine use. De-NOx principle of EGR is to reduce the generated NOx during the combustion process by decreasing O2content and increasing CO2 content in the scavenging air, which resulting in reduction of the peak combustion temperature. MAN, Diesel and Turbo (MDT) is investigating EGR system and is making a service test on Alexander Maersk. Mitsui Engineering and Shipbuilding Co., Ltd. (MES) under license of MDT set EGR system on our test engine 4S50ME-T9. This EGR system is the first built-in type on the engine. The purpose of this work is to design and experience built-in EGR equipments in terms of gas flow system components such as EGR scrubber, EGR cooler, EGR blower, control valve, etc. and scrubber water supply system such as scrubber pump, centrifuge, etc. More-over, the purpose is to decide optimum EGR and engine operating parameters such as fuel injection timing to obtain the best operating efficiency.

论文已在上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。The launch of the Wartsila X-engines marks the introduction of a new generation of low-speed engines to the market. The new engines have been developed out of the requirements for lowest Total Cost of Ownership and highest reliability, while manufacturing cost for Wartsila's licensees is reduced from the onset of the design. The new engine types are being developed for the actual IMO Tier ll NO, legislations,

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The Product Portfolio of Diesel Engines by MAN Diesel & Turbo contains several diesel engines adapted to special market segments. There are several challenges driving the actual development of diesel engines. Most important are the rules and regulations regarding emissions, the trend of global eco-nomics and the significance of new markets like off-shore exploration. Especially the diesel engines have to include new technologies in order to manage the tradeoff between emissions and specific fuel oil consumption. This paper shows diesel engines with con-sequent design for a special market segment. Some new technologies introduced into the market some years ago have passed now a reasonable operation time. Hence it is time to analyze the field issues in order to evaluate the technology readiness. The study of problems in diesel engine operation is also a method to show the need of new technologies due to the change of mixtures of heavy fuel or the like. The market specific design is shown for the 28/33D engine, which is developed for the High speed ferry market and the navy market. The 32/44K engine is an example for an optimized design for auxiliary gensets. The well-known 32/40CD is taken as an example for the need of new design adapted to new heavy fuel oil mixtures. Long term experience with Common Rail technology is available for the 32/44 CR engine type. This engine is also an example for the potential to increase output or adapt new technologies. A damage of an injection part will be used as example to show pitfalls with long term validation for optimized parts. This engine is also an example for the adaption of new technologies like variable valve timing, common rail and two stage turbo charging.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 This paper addresses the critical role of evolving spark ignition technologies in expanding the envelope of effective operation specific to both in-cylinder combustion stability and the overall performance and efficiency of the associated engine. The reviewed advances in spark ignition technology de-scribe a new means whereby previous boundaries of gas engine design and operation might be extended. Optimization of key engine performance parameters such as consistency and phasing of individual cylinder firing pressures and accelerated flame kernel development are fully explored. Additionally, the practical impacts of these fundamental changes in performance as observed in documented engine test results are discussed with respect to the successful management of difficult to ignite mixtures inclusive of those engines operating in a low emissions environment, on suboptimum fuels, or even in off-design conditions.

论文已在中国上海举办的2013年CIMAC大会上发表，论文的版权归CIMAC所有。 Across the entire Natural Gas engine industry, operators and OEMs are faced with increased expenses and the deterioration of engine performance as they struggle in meeting the mandated lower emission levels. In the sector of large bore engines, greater than 250mm, the field is populated by two combustion strategies aiming at meeting lower emissions. A significant percentage of large bore, low speed engines, use two spark plugs per cylinder to enhance the combustion rate. The remaining population of engines uses precombustion chambers with a dedicated fuel feed and controls to generate a rich air-fuel mixture in the vicinity of a conventional spark plug. Using a precombustion chamber adds complexity, cost and reduces reliability. Although lower emissions are achieved with fuel fed prechambers, the engine stability with leaner mixtures still remains the limiting factor compromising the performance of the engine. This paper de-scribes a cost effective solution for each of the combustion strategies. These solutions aim at extending the lean limit of operation, hence, meeting the lower emission requirements with improved combustion stability. In the case of large bore, low speed engines currently using conventional spark plugs, it is possible to avoid the costs associated with the conversions to fuel-fed precombustion chambers by simply replacing the conventional spark plugs with specially designed passive prechamber spark plugs. These highly effective designs are obtained with the latest technology in computational flow dynamic (CFD) that uses the CONVERGE detail chemistry CFD software. Results from engine testing indicate that specially de-signed passive prechamber spark plugs achieve stable engine operation at NO, emission levels below500mg/Nm3(1.0g/bhp-hr).n the case of engines which already have a fuel-fed precombustion chamber, lower emissions can be achieved with the use of a passive prechamber spark plug in place of the conventional spark plug to form a two stage precombustion chamber operating with significantly leaner mixtures. The flame jets emerging from the passive prechamber spark plug compensates for the slower flame propagation rates associated with lean prechamber combustion. The optimum design of the two-stage precombustion chamber, the amount of fuel required, the fuel injection timing and the spark discharge characteristics are also determined with the latest technology in computational flow dynamic(CFD) that uses the CON-VERGE detail chemistry CFD software. An electronic fuel control valve provides the amount of fuel required at the correct timing. Furthermore, an ignition system with a tunable high energy spark discharge waveform achieves the desired combustion stability while maintaining a long plug life. Engine test results from this system indicate stable engine operations at NOx emissions levels below 250mg/Nm3(0.5g/bhp-hr). The solutions demonstrated in this paper provide enough evidence to warrant consideration by OEMs for immediate use in large bore gas engines.

论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。The two stroke crosshead low speed diesel engine has been a preferred prime mover in the merchant marine for mostly a century. Although its basic working principle has not been changed, the demand for still higher power, produced at the lowest possible fuel consumption, from a machine occupying a minimum of space, has constantly increased the demands to its cylinder liner. This relates to both the thermal and mechanical loading, and the tribological behaviour under ever changing conditions. This pa-per gives a view on the development in loading on the cylinder liner as one of the main engine components as it has developed over time. Special attention is given to the recent development as a result of the high focus on specific fuel oil consumption, and the thereby introduced changes in the combustion conditions. New application of advanced analysis method for acid attack on the running surface of the cylinder liner is demonstrating how the new operating conditions will affect the behaviour of the cylinder conditions, and in consequence the cylinder liner. Countermeasures in way of design and operational measures will be presented and service examples will illustrate the validity of the conclusions and countermeasures. As for the increased mechanical loading of the cylinder liners, two main new designs will be demonstrated:1) One new design relates to the mechanical design of the cylinder liner, and how this design is able to withstand the increased pressure from the diesel process. The cylinder liner consists of a so called ' strong back' consisting of a steel bandage shrink fitted to the upperpart of the cylinder liner. The increased strength of the steel in comparison with the cast iron material thus results in a higher load capability. Service experience of several years of operation is presented for reliability confirmation.2) The other design feature allowing the increased pressure is based on development of a new material application: the so called CGI or Compacted Graphite lron. This application has been developed in tight cooperation with the Japanese cylinder liner manufacturer Toa Koki. The paper describes the production technique applied to achieve a high a stable yield. The merit in terms of mechanical properties of the CGI is shown. Tribological test data will be presented, and finally service experience will be shown for a number of different engines. In summary it will be illustrated how modern diesel engine process and application affects the cylinder liner, and how these effects are overcome.

论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。The onset of end gas knock remains one of the primary factors limiting the thermal efficiency, fuel flexibility, specific power output, and transient capability of lean burn natural gas engines. In the past two decades, huge strides have been taken to improve the performance of these engines, based largely on a fundamental understanding of the impact of thermodynamic design and fuel properties on the resistance of a given combustion platform to engine knock. Simulation tools based on this knowledge have led to optimized designs as regards expansion ratio, Miller Cycle utilization, and other design approaches aimed at limiting end gas temperatures. Two basic engine phenomena whose impact on knock is less well understood are in-cylinder heat transfer and overall combustion rate, phasing, and stability. In-cylinder heat transfer has a profound impact on charge temperatures and can lead either to increased or decreased knock tolerance for a given design depending on a number of factors. Combustion chamber surface temperatures are a function of detail design, engine load, and engine operating condition and have a direct impact on heat transfer rates during compression and the early part of combustion. In-cylinder bulk flow and turbulence level induced, for example, by swirl and squish also impact the heat transfer rate and thus the unburned gas temperature. The influence of these heat transfer effects on knock tendency is not well documented. Combustion rate and stability affect knock behavior as well for a given engine geometry. The faster heat release rates that are desirable from a thermal efficiency standpoint can either increase or decrease detonation margin as they tend to drive up peak temperatures while at the same time reducing the time avail-able for end gas chemistry and pushing the engine operating point to leaner conditions in order to maintain constant NOx emissions levels. Poor combustion stability which often results from very lean operating conditions can also impact knock margin as some very fast burning cycles give end gas conditions far away from the mean operating point typically analyzed with simulation tools. A combination of test results, simulation data and statistical tools can be utilized to under-stand these combustion stability effects. This paper seeks to provide insight into the relationship between these secondary effects (heat transfer and combustion behavior) and combustion system development as regards knock avoidance. Simulation results and engine test data are provided that highlight the role of heat transfer and heat release on knock tendency. De-tailed single cylinder engine measurements including surface temperatures, heat release rates, and inferred heat transfer rates are provided to clarify the performance trends. Multiple zone cycle simulation results are used to provide further clarification of the knock impact of heat transfer and heat release for a given engine geometry. Combustion system development that includes an understanding of these processes inevitably yields production engines with superior market potential. The availability of a fundamental framework for these physical processes, supported by research grade test and simulation results will be a key enabling technology for the next generation of high performance natural gas engines.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The level of peak cylinder pressure and indicated mean effective pressure have increased rather constantly in compression ignition internal combustion engines over the past decades. Present medium-speed engines are capable of running with about 20 MPa peak cylinder pressure. In this study the new values of high peak cylinder pressure level of 30 MPa are reviewed for the first time.