该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Winterthur Gas & Diesel Ltd. has developed a dynamic engine model of 2-stroke diesel and dual-fuel engines. The presented dynamic engine model provides the possibility to test the complete engine control software in Hardware-inthe-Loop fashion. The engine simulator is equipped with the real hardware modules needed to control an up to twelve cylinder diesel engine or an up to six cylinder dual-fuel engine, where the actuator outputs are connected to realistic electrical loads. The simulator also emulates external systems like the remote control system and gas valve unit, which makes it possible to test the entire automation setup as installed on the ship. The objective of this article is to describe the dynamic engine model designed in Matlab Simulink and embedded in a NI-Veristand environment that executes all necessary tasks in real-time. The engine model consists of a physical common rail system with multiple pumps and injectors, a thermodynamic model of the cylinder pressure with a simplified combustion as well as a mechanical model for the load computation related to operating point and engine specific inertia. It also computes all relevant engine feedback signals in real time, such as exhaust valve position, gas admission valve position, lubrication pressure feedback, cylinder pressure and more. Regarding the utilization of the dynamic engine model, the paper will also focus on the new possible control software tests that can be performed compared to the previously used steady state test rigs. The main purpose of this engine simulator is to test the behaviour of the engine control system in normal operation as well as in emergency conditions. Typical emergency cases are malfunctions of control modules, communication buses, actuators or sensors. It is also used for testing control sequences crucial for the correct engine operation, e.g., engine starting, fuel transfer from diesel to gas operation, redundancy functionalities. Additionally it enables the possibility to test and monitor the interaction of independently controlled closed loop systems, e.g., the interaction between the fuel pressure controller and the speed controller of the engine. By using an engine simulator which is able to represent engine hardware and its dynamic behaviour it is possible to develop a more robust engine control software in much shorter time.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Recent years have shown significant changes in the way, how marine two-stroke Diesel engines are operated. Slowsteaming has reduced average load of such engines and load profiles have become more disperse. The more frequent operation at low engine loads lead to a phenomenon called cold corrosion, which means the corrosion of cylinder liner running surface due to attack of sulphuric acid from burning sulphur-containing fuels, yielding pronounced wear and tear of cylinder liner and piston rings. This paper aims at displaying the measures taken by Winterthur Gas & Diesel Ltd. to investigate the physics behind the described phenomena and to implement design features to reduce the leverage of negative effects of slow-steaming in favor of ship operators and ship owners. The measures taken comprise the following: • Lubricant oil deposit control and optimised material combinations and surface machining to achieve minimal running-in wear and consecutive wear • Engine design adaptations to minimize condensation of sulphuric acid on the liner running surface and optimize distribution of cylinder lubricant strokewise and circumferentially • Investigations to understand the influence of recent engine layout (lower power and speed) and operation regimes (slow-steaming, turbocharger cut-off) and definition of measures to compensate adverse effects of these The success of above mentioned measures can be summarized as follows: • The current material combination with plateau-honed cylinder liner and Chrome-Ceramic piston ring running surface coating attains maximum corrosion protection and lowest possible wear over component life time. If, by any means, significant corrosive attack takes place, wear rate of cylinder liner and piston rings will increase during this period and goes back to regular level after suitable lubrication conditions have been re-established, because the piston ring coating does not disintegrate even under severe corrosive conditions. Corrosion scares will wear off in operation and normal wear regime will return • Gas-tight top piston ring lock design keeps lube oil and combustion deposits out of the ring pack and reduce the lubricant loss to both combustion chamber and piston underside space. Free moving piston rings are the prerequisite for trouble-free piston running over entire engine lifetime • Liner cooling bore insulation and - for latest engine designs - liner cooling water feed system with high temperature help to keep liner running surface temperature above dew point of water over the entire load range, which reduces the intensity of sulphuric acid condensation • Cylinder lubricant injection nozzles optimized by simulation algorithms in combination with distribution and retaining grooves on the cylinder liner surface ensure a perfect circumferential distribution of the cylinder lubricant • Optimised piston ring running surface profiling on the three-piston ring pack on latest engine designs keeps cylinder lubricant longer in the ring pack before releasing it for disposal • By choosing suitable (fuel-dependent) cylinder lubricant and controlling cylinder lube oil feed rate by appropriate piston underside drain oil sample analysis for remaining base number according to specified limit, cold corrosion of cylinder liners and consequential damage on piston rings can be avoided • Extensive operator information released for improving and optimizing operation on slow-steaming regime and with turbocharger cut-off translates innovation in technology to a monetary benefit for ship owners and operators Further design features planned for release during the next years will enhance the position of engine designs engineered by Winterthur Gas & Diesel Ltd., such as reduction of piston rings from three to two or one, inclined inlet ports, improved piston centering by a revolutionary piston skirt and closed-loop piston underside lube oil base number control. Investments into skilled pers

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Low speed two stroke diesel engines operate with a superb efficiency being integrated by many cylinders, which pistons are linked to a flexible large crankshaft. These components together can be considered a torsional system that can be simulated by a lumped-mass model. This work shows the development and operation of a torsional model of a 10 cylinders two stroke low speed diesel engine that currently is implemented in a diesel power plant. 1. Torsional system model The nature of the torsional system makes it be highly non-lineal. A lumped-mass non-lineal torsional system model with sixteen degrees of freedom (dof) is formulated where excitation comes from the combustion pressure in each cylinder. 2. System identification Data provided by the engine maker do not fulfill the real engine parameters and therefore the model needs a system identification analyses. For this purpose combustion pressure on the ten cylinders and the instantaneous mechanical torque are measured. An optimization procedure allows the fitting between the measured torque and the torque provided by the model, which is fed with the combustion pressure. 2.1. Torque measurement The real mechanical torque delivered by the engine is measured from strain gages located in the engine-generator shaft. Because of generator efficiency has been measured and the electrical power is known the mechanical torque is correctly calibrated. The torque curve along an engine cycle is far to be flat, being maximum torque about 50% of the mean torque. 3. Model application 3.1. Acute indicated engine power measurement Indicator diagrams from combustion pressure measurement allow the evaluation of indicated engine power and the correct balancing of the cylinders. If the crankshaft dynamic torsion is not considered, the combustion chamber volume is poorly evaluated and therefore the cylinder power is overvalued. In a two stroke ten cylinders low speed diesel engine, the maximum error in the evaluation of the power of one cylinder has been of 5%, giving an error in the engine power higher than 10%. This error affects not only the engine efficiency calculation but also the cylinders power balancing. 3.2. Estimation of Combustion Pressure The lumped-mass non-lineal torsional system model allows the estimation of the combustion pressure of each cylinder. From the measured pressure at plenum intake and considering polytrophic compression and expansion processes, a functional law of two parameters is formulated for combustion pressure description. In the case of a ten cylinder engine this structure supposes 20 unknowns that are evaluated from an optimization procedure. Although the combustion pressure provided is not as accurate as the measured one, it is enough for diagnostic. 3.3. Identification of crankshaft cracks The torsional model fitted to the engine at section 2 is sensitive to changes in the mechanical engine parameters. Mass and inertia are invariant but in the case of the existence of a crankshaft crack, there is a reduction of the dof stiffness that grows with the crack progress. From a simulated combustion pressure curve that accounts the different engine load, the torsional model is excited and the crack on each crank (modeled as stiffness reduction) are free parameters to be estimated from an optimization procedure. 4. Conclusions A precise model of the torsional system applied to current engine data it is a valuable tool for diesel engine management that it has important applications: • Acute indicated engine power measurement • Estimation of Combustion Pressure Curve per cylinder • Identification of crankshaft cracks The system is successfully in operation on three diesel generators of 15 MW at Balearic Islands in Spain.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Slow steaming has been a trend of the current shipping industry to reduce fuel costs. In our capacity as a turbocharger manufacturer, the authors of the present report believe that new technologies developed specifically for low load operation will enable turbocharger performance improvement with respect to the market needs for slow steaming. Mitsubishi Heavy Industries Marine Machinery & Engine Co., LTD. (MHI-MME) has put their focus on turbocharger efficiency improvement, especially on optimizing low load efficiency, as a new generation development for Mitsubishi turbochargers. Optimized turbocharger efficiency under low load conditions will contribute to higher combustion efficiency of main propulsion engine resulting in fuel consumption reduction and minimizing the need of auxiliary blower over its operation range. Furthermore, for ships employing turbo-compound system, surplus of turbocharger improved efficiency can be used towards electrical power generation, thus enabling power turbine’s generation at load lower than ever. This can also benefit reduction of fuel used for electrical power generation at low load. Moreover, MHI-MME’s new compressor wheel with higher scavenging air pressure, wider rage, and more air flow can achieve overall turbocharger size downsizing and more applicability to main engine’s scavenging various pressure requirements. The new compressor wheel with wider range will be a remarkable fit to applications especially involving change in engine operation line during operation such as turbo-compound system and turbocharger with variable turbine inlet (VTI) for two-stroke engines. This paper introduces MHI-MME’s new technologies employed for next generation turbocharger improvement.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Large Diesel Engines which fulfill the EPA tier4 final emissions have just entered the market. The EPA deterioration factor tests and the field validation are positively completed and the ramp up is ongoing. Robustness, reliability and durability statistics are currently not available. Field inspections will support the learnings. They will set the targets for further evolutionary improvements on the EPA Tier 4 engines to ensure mature systems. The current publications show following solutions on the market. CRS > 1800 bar +SCR and CRS 2200 bar + EGR and DOC. Due to further combustion optimization we will also see CRS 1600 bar + SCR + DOC in future. All solutions lead to significant cost increase compared to EPA Tier 2 engines. EGR and SCR costs, as well as cooling- and packaging requirements made the application of Tier 4 solutions very complex and cost intensive. Although learning on the EPA Tier 4 systems is not completed already new emission limits are under discussion. A proposal for EU Stage 5 has been published. It shows further significant reductions on PM and NOx emissions. This paper is trying to give an outlook on the requirements for the injection system and the exhaust after treatment. What emissions can be achieved with a 2200 bar CRS on a large high speed engine and is this sufficient to fulfill upcoming emission legislation? The injection system is described and its performance at the emission relevant load points is documented and brought into relation to the emission and fuel consumption results. The injection rate, the spray performance and the spray velocity at the spray hole exit is analyzed in detail. The investigations include engine measurements with a one and two stage turbo charger like setting on a high end single cylinder high speed large engine. Based on the experience of heavy duty on and off highway engines a prediction on the requirements for the injection system and the exhaust after treatment for a high speed LE engine can be given to fulfill future emission legislations. Current EU Stage 4 and EPA Tier 4 heavy duty off highway applications (<560 kW) fulfill already today the emissions limits which are close to future LE (>560 kW) EU Stage 5 limits. EU Stage 4 with 0,4 g/kWh NOx and 0,025 g/kWh PM. EPA Tier 4 with 0,4 g/kWh NOx and 0,02 g/kWh PM. Current on highway emission legislations are on a comparable level, but with additional PM limitation and already applied in service conformity testing. Existing heavy duty solutions and existing LE engine results enable the prediction on possible technologies to fulfill LE EU Stage 5emissions. Solutions which prevent further increase of costs, packaging and complexity are beneficial. Robustness,durability and reliability requirements must be fulfilled with all solutions.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Due to the well-known reasons, such as the reduction of operating costs and emissions, the number of gas engines has increased a lot over the last years. Thereby Dual Fuel engines enable high flexibility and operating reliability. So unlimited engine operation is guaranteed, even if gas supply was interrupted. Furthermore gas operation with pilot injection also shows advantages in comparison to operation with spark plug, for example an increased ignition and lifetime. As global market leader for Dual Fuel injections systems L’Orange possesses more than 20 years of experience in research and development; both for engines with homogeneous combustion (low pressure gas) and also with heterogeneous combustion (high pressure gas). The appropriate engines from Wärtsilä convice on the market for many years. Despite many advantages the actual Dual Fuel injection systems show one disadvantage: they are complex and extensive and therefore need equivalent constructed size. Usually DF injection systems have two separated fuel circuits, one for pilot injection with gas operation and one for liquid fuel operation. This requires several pumps for pressurization, a double needle injector with a common rail and a pump line nozzle site respectively two separate injectors per cylinder. Currently L’Orange develops a new, obviously simplified injection system. The injection system consists only of one fuel circle with one high pressure pump plus one injector per engine cylinder. The injector possesses a one-needlenozzle, with which the pilot quantity and the full load in the fluid fuel operation are injected. Thereby challenges for the development are the realization of a stable injection quantity for the pilot injection at a sufficient fuel atomization - with the same nozzle respectively the same blowholes for the pilot- and main injection. To guarantee the required engine performance and emissions, the injection quantity has to remain stable for the whole lifetime which demands a closed control loop for drift compensation. Furthermore design-measurements are required to ensure the thermal balance of the high pressure pump and the nozzle in gas operation. Besides the design and simulation activities extensive tests on component test rigs and on the spray diagnostic rig at L’Orange plus on the engine were realized. These tests have provide good results, so first series operations are expected soon.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。This paper provides in-depth research, analysis and testing results of the impact of significant volumes of water contamination in diesel fuel oil on the ability of large, medium-speed diesel engines to successfully start and operate under emergency conditions. This investigation came about from the discovery of degraded vent pipes on diesel fuel oil day tanks that could have allowed rain water to collect at the bottom of the diesel fuel oil system and potentially prevent satisfactory engine start-up and operation. Analytical and empirical results for those conditions, where there is no known analysis or operating experience, are described in detail. For the past several decades, a number of diesel engine manufacturers investigated the effect of introducing water into the combustion process by different methods such as water emulsion, direct water injection or inlet air fumigation. The goal of these tests was to demonstrate the positive effect of water in reducing diesel engine exhaust emissions. These efforts proved successful in achieving that goal, but the results have not seen wide-spread application by today’s engine suppliers and there remained the concern about the potential disadvantages of water and diesel fuel oil systems. In contrast to past investigations, this effort focused on completing a series of diesel engine combustion analyses using Ricardo’s WAVE©, 1D engine performance simulation software. The WAVE Diesel-Jet predictive combustion model was enhanced by combining the ignition delay predictions with external combustion efficiency calculations in order to predict the power loss and water concentration where the engine would still operate and sustain efficient combustion. Two different medium-speed diesel engine models were analyzed with added water content ranging from 10% to 40% water in the diesel fuel oil. The analyses demonstrated that the engines could start and operate with those percentages of water in the fuel, but that the engine output would experience a power loss or derate proportional to the water content. The validity of the analytical findings above was demonstrated by full-scale tests conducted by MPR Associates on a large diesel engine. To accomplish this, Entergy, the nuclear power plant owner constructed a simulation of the diesel fuel oil supply system at a facility having the same make and model emergency diesel generator (EDG) set. Water was introduced into the diesel fuel oil day tank by two different approaches; slow trickle flow and large slugs of water. These conditions simulated either a steady rainfall while the EDG was operating or a large volume of water collected in the system while the EDG was in standby. Under both conditions, which consisted of more than 50 hours of testing, the diesel engine and generator set responded with negligible loss of frequency or voltage. Further, the engine was confirmed to have undergone no increased wear or degradation as a result of the high levels of water in the combustion chambers.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。This paper presents the design of the Ganser CRS common rail injectors with the proprietary poppet valve, the state of the art hydraulic switching component for common rail injectors. Thanks to its unique design, the combustion process is optimized by stable and rapid injection profiles, which are allowing for reliable multiple injection driving strategies to further reduce the in-cylinder emissions. Due to its universal characteristics, the poppet valve is applicable in numerous fields, of which two of them are specifically presented in this paper. The first exemplary application of the poppet valve is the common rail retrofit of a 16V ALCO locomotive engine with a power output of 3MW. In this retrofit project, the existing mechanical fuel injection system is replaced by a tailor-made common rail system. Thanks to the unique injector design, no changes to the cylinder head are necessary. The injector includes an integrated accumulator for maximized and constant injection pressures during the whole injection process. Each cylinder bank is equipped with a separate slim rail and a dedicated high pressure pump, allowing for a freely configurable injection up to 1600bar. The poppet valve is also successfully applied in the field of micro pilot injection for new dual fuel engines. On these marine engines, the micro pilot injection quantity to ignite the gas is typically 0.5-2% of the total power output. This maximized substitution is possible thanks to the accurate switching characteristics of the poppet valve at these small injection quantities. With the application of the proprietary Wave Dynamics and Dampening System (WDD) and injector-integrated accumulators, the rail can be replaced completely by so-called jumper lines.

该论文已在芬兰赫尔辛基举行的第28届CIMAC大会上发表。论文的版权归CIMAC所有。Natural gas constantly expands its percentage share of the worldwide total energy consumption. This trend is expected to continue during upcoming decades. Facing varying emissions legislation and individual customer requirements, flexibility of modern gas engines for electric power generation gains in importance. In order to meet these requirements, different applications of the G20CM34 lean burn otto-gas engine were developed. The goal was to provide the nominal engine power output of 10 MW at high engine efficiency and low NOx emissions within a wide range of changing boundary conditions (altitude, ambient temperature, fuel composition, plant operation mode). The applications were placed in diverging spots regarding the tradeoff between applied Miller cycle, required intake manifold air pressure and maximum compression ratio below the knock limit. As a result customized engine setups can be provided, serving customer individual needs at specific sites. The capability of simulation tools is permanently enhanced, but some impacts of design changes on engine performance can still not be reproduced or predicted. That is why a validation of an entire development concept at the first prototype engine involves a high risk not to achieve the stated development target. This was the main driver to implement a 3-cylinder test engine in an iterative gas engine development process. The highly flexible test setup provides the possibility to assess gas engine operation within a wide range of adjustable boundary conditions at the required high turbocharging efficiency. Optimizations like crevice volume reduction and improved pre chamber designs were realized by the use of various simulation tools. The resulting impact on combustion performance could separately be assessed by the analysis of the obtained test engine data. Adjoining, the durability of selected components could be proved during according endurance runs. So a substantial portion of the development effort could be shifted to the test engine, where the thermodynamic concept could be validated in an early stage of the project. As a consequence, engine settings could be determined in advance and the required test time for prototype engines significantly reduced. The lean burn concept with pre chamber enables high engine efficiency at relatively low NOx emissions. Whereas power density of modern gas engines is still restricted by events like knock, misfire, abnormal combustion and pre ignition. Cylinder balancing in combination with advanced engine controls represents a reasonable approach to generate several benefits to mitigate these limitations. Potentially engine efficiency or power density can be increased. Furthermore, the operating range under challenging boundary conditions can be extended. Parameters to characterize the combustion process are required as input for cylinder balancing and advanced control efforts. A cylinder pressure based control system was chosen to provide this input. Being applied at the 3-cylinder test engine, its global functionality could be validated and different control strategies evolved. Enabled by the described gas engine development process, costs were reduced and the development cycle of the project significantly shortened. Outcome of the G20CM34 gas engine concept are different applications to satisfy customer individual requirements all around the world.