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。Due to ecological as well as economic reasons large size gas engines - especially within the medium speed range are gaining increasing interest. In addition to the already established power generation application, these types of engines are of increasing interest for marine or rail propulsion as well. Besides the obligatory fulfillment of the stringent emission legislation, the achievable fuel efficiency level is a key factor for the final customer. The present publication analyzes and describes the requirements given by the specific applications of large bore gas engines. Based on this, the particular challenges of their combustion system layout can be derived. Compared to passenger car or commercial vehicle engines, this requires a distinctly different conception. The paper is focused on the description of the development of a pre-chamber combustion system at FEV. For this, the combination of the well-established Charge Motion Design (CMD) process with experimental work on a single cylinder engine could be realized successfully. By the CMD supported layout of the pre-chamber, the development process could be shortened significantly due to the reduced number of variants in the test program. The excellent combustion stability of the optimized system allows BMEP levels in the range of 30 bar. By means of parameter variations the very good correlation between simulation and experimental results as well as the effect of different prechamber layouts can be shown. This is a basic prerequisite for a target oriented combustion system development.

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。The possibility to mix gas and liquid fuel could be a useful feature for vessels where the quantity of the boil-off gas is not sufficient for providing the needed vessel speed but where there still is a need to use the boil-off gas to a certain extent. In order to meet the demands from the market, this feature has now been introduced to Wärtsilä gas engines and the first ships have been delivered with this function in early 2015. Two main aspects of the operation have been emphasized in the development of the function. First of all is the robustness of the function, which means that the fuel sharing function has to be safe to use and the performance of the engine cannot be compromised regarding operation and loading. The second aspect is the operating area regarding both engine load and the gas and liquid fuel ratios to be used. The paper will present how the fuel sharing operating area has been defined according to optimal engine operation and how the engine will operate in this area and how the engine will be controlled if the operating area needs to be exceeded. The fuel sharing function has also been introduced as a new fuel mode, and tests and demonstrations have been carried out for classification societies and customers in order to release the function. Several failure mode operations have been demonstrated, and the paper will show how the engine behaves at different situations when running in the fuel sharing mode. Situations like loss of gas or loss of liquid fuel must be well defined in the engine automation system to have a safe operation of the ship even in an abnormal or failure situation. The ship operator also needs to know the impact on the engine performance when operating in the fuel sharing mode. This has been mapped all over the fuel sharing operating area, and the impact on engine emissions and engine total efficiency has been defined from these tests. With the new released function, the ship operator has been given yet another feature that will improve the flexibility of the ship operation.

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。Major changes are underway for Marine Trunk Piston Engine Oils (TPEO). Use of distillate fuels in combination with increased use of API group II base oils, longer drain intervals and lower specific lubricating oil consumption present significant technical challenges. Product to meet those challenges can’t be developed by only utilizing laboratory bench tests. To ensure reliable performance for the end users, validation of product performance in field applications is a must. On January-1st 2015 the 0.1% m/m fuel sulfur limit, or equivalent sulfur exhaust, came into force for ships operated inside Emission Control Areas (ECA). At this point in time the Baltic Sea area, the North Sea area, the North American area and the United States Caribbean Sea area are establish ECAs, however it is expected that the number of established ECAs will grow. Looking forward, considering the expected growth in the number of ECA’s, the use of low sulfur distillate fuel in shipping application will grow significantly. Likewise it is expected that the demand for engine lubricants that allow for operation of ships on such fuel will grow. As we anticipate changes in fuel usage in the market, changes in the base oil market continue to change as well. API group I heavy neutral base oil has been the base oil of choice for marine engine lubricants for decades. However as group I base oil plants have gradually been supplanted by newer, more cost efficient group II base oil plants, the use of API group II heavy neutral base oil in marine engine lubricants has increased significantly in recent years. As API group I heavy neutral base oil availability decreases so does the availability of API group I bright stock, which leads to the need for alternative lubricant thickening agents to allow for blending marine lubricant viscosity grades. Chevron Oronite has developed TPEO additive technology for engine operation on lower than 0.1% m/m fuel sulfur that combines in one formulation: • excellent piston cleanliness • excellent sludge control • excellent viscosity increase control • extended drain interval capability • base oil flexibility • significantly reduced need for bright stock Extensive statistical design of experiment studies on lab scale performance screening tests have been executed to select the most promising additive technology and formulating approaches. The best candidates have been further optimized utilizing our laboratory engine testing capabilities. The optimized candidates were thereafter evaluated in field applications to validate their performance. The data demonstrates that the use of laboratory scale performance screener tests provides valuable information that allows for developing additive technology and selecting viable formulation approaches. However there are always candidates which look very good in bench tests that do not perform well in engine stand tests or field trials. Engine testing and field performance evaluation is essential to ensure that the end user does indeed get the desired performance.

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。Beginning of 2016 IMO Tier III regulations came into force in designated NECA zones. Even as these zones are up to now limited to the US and Canadian coastline and the gulf of Mexico, great uncertainty is caused by national, local and harbor regulations, that are being discussed at the moment to limit the access of special areas to environmental friendly vessels or at least grant incentives to these vessels. Therefore the aim of the development of the MAN Diesel & Turbo (MDT) SCR system was not only to develop an aftertreatment system for fulfilling the IMO Tier III limit but to develop a system, that gives the customer the maximum flexibility and the possibility to minimize his operating costs even in the IMO Tier II areas. By doing so, the SCR system is no longer just an environmental driven device for NOx reduction but became an import tool for OPEX and EEDI reduction, that can be used even if the vessel is never intended to enter NECA zones. This was only possible as the engines and its SCR systems were optimized as an overall system and not as standalone, independent components. The MAN SCR system has proven its reliability by more than 15.000oph on a field test carrier operating on heavy fueloil (HFO) and its compliance with IMO regulations by receiving the first IMO Tier III EIAPP certificate worldwide as well as the approval in principle for the entire MDT four stroke engine portfolio following scheme B certification.

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。To comply with IMO Tier III, nitrogen oxides from engine shall be reduced about 80% compare to current IMO Tier I in emission control area. One of the most promising approaches to achieve substantial NOx reduction performance in marine application is SCR by using vanadium-based catalysts due to their relative insensitivity to sulfur in fuel with high NOx conversion. The SCR catalysts including substrate should be selected after considering condition of the marine application such as property of fuel, installation condition and operating condition. In case of the 4-stroke medium speed engines, typically allowed backpressure of SCR system is 10 to 15 mbar. Under such condition, the SCR catalysts have to be designed significantly low backpressure, whereas installation is under space constraints in vessel. Other requirements are sufficient mechanical strength and resistance against vibration from engine itself and complex vibration from ship. In addition, since the most of marine engines are operated in low load and used low quality fuel, catalysts are exposed to the exhaust gas including high dust and sulfur. Therefore catalysts also shall be designed to keep good performance in low temperature and durability against high dust and sulfur. Taking these into account, in this paper, we introduce new developed SCR catalyst which called WIW (Washcoat-In-the Wall) catalyst and compare with other types of catalysts which are commercially available for diesel engine application. Coated SCR catalyst on metal substrates and homogeneously extruded catalyst are used for comparing with WIW catalyst. These catalysts are analyzed the performance such as mechanical strength, ammonia storage capacity and NOx conversion rate depending on temperature by using the micro reactor in laboratory. And these catalysts are verified the NOx conversion rate, influence of differential pressure by particle matter and noise reduction in STX-SCR system with 2MW marine diesel engine. Additionally, to investigate durability and regeneration for SOF and ABS, WIW catalyst was subjected to aging cycle with high sulfur emission gas. The WIW catalyst has enough mechanical strength, NOx conversion performance and durability to apply to marine application. Accordingly, it has acquired Tier III confirmation classification society for STX-SCR system using WIW catalyst on 2MW marine diesel engine.

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。Balancing the combustions of different cylinders in a multi-cylinder internal combustion engine is a task dealt with for more than 100 years now. The assumption that all cylinders provide the same torque to the crankshaft has always been a basic precondition for the mechanical design of an engine. However, in practice, different factors disturb this assumption, resulting in cylinder-to-cylinder combustion variations. Already at the early beginning of multi-cylinder engine development, operators could adjust the fuel supply to each cylinder individually, for example with throttle devices in the fuel line upstream of each cylinder. Such devices were made for adjusting an engine literally “manually”. Operators had to use their human senses to assess engine operation. There wasn’t any sensor or technical measurement providing precise information about the combustions of different cylinders. Over the years, technical progress produced many new means facilitating the balancing task: Manufacturing tolerances were reduced significantly. Powerful sensors provide detailed information to electronic control systems. Actuators for both, liquid and gaseous fuels provide interfaces to electronic controllers, allowing for fast and precise closed loop control of cylinder individual fuel supply. As a result, balancing combustion can now be “simply” done by adding some software functions to an electronic engine control system. Nonetheless, balancing combustion is still becoming a more and more challenging task. The main reason for this is that modern engines are extremely sensitive to the aforementioned cylinder-to-cylinder variations. Even very small variations between two cylinders may result in strong deviations of their combustion behavior. This paper presents solutions to some of the main tasks in integrating balancing functions to controller software. The big challenge with these balancing functions is to handle their complexity. Complexity emerges from several issues: The mere number of actuators and sensors to choose from, the difficulty to find out the “right” balancing for a specific engine, the interdependencies between more than one balancing function, the interdependencies between balancing and further standard control functions and last but not least the problem that a well-balanced engine might seem to be running well, even though severe engine problems might be the reasons for its imbalance and should be repaired as soon as possible. The first point is the mere number of actuators and sensors resulting in a large number of possible balancing solutions. In case of typical gas and dual fuel engines, on the actuator side we can choose from spark plug timing, port injection gas valve, main Diesel fuel injector and pilot Diesel fuel injector. These actuators have effect on sensor information about structure borne sound, exhaust temperature, in-cylinder combustion temperature and in-cylinder combustion pressure. There is no general answer on the question which actuator and which sensor to choose for balancing. And usually, balancing the direct sensor information is only a first step to improve engine performance. For example, regarding pure exhaust temperatures, balancing is very simple. However, it is not really the task to balance exhaust temperatures. It is far more important to balance “combustion”. Therefore, the most important step in designing a combustion balancer is to find out the right control variable, which might be a combination of sensor information from different sensors. The paper emphasizes on this cylinder individual combustion control. It presents how to combine combustion balancing with conventional control functions. Especially, a new approach to anti-knock governing is presented. It is integrated into the combustion balancing, which enables the engine control system to avoid knocking combustion – instead of only reacting to knocking combustion.

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。The prime movers used for ships today have certain limitations in their load response. As a ship accelerates, the diesel engine due to the temporary inability of the turbocharger to supply a sufficient amount of air to burn completely the fuel quantity required to meet the increasing load, emits smoke. One way of addressing this issue is the use of a diesel-electric hybrid configuration. Examples of ships with highly flexible power demand, where a hybrid system could be useful, are off-shore supply and anchor handling tug vessels. When hybridizing a diesel engine-powered powertrain, the reduction of emissions and the potential for further gain in fuel economy has to be analyzed carefully and suitable control strategies should be implemented. A diesel electric hybrid vehicle can save more fuel, but in some cases it can also emit more pollutants than its conventional counterpart. This work investigates the improvement in performance of a combustion engine with the assistance of an electric motor, with appropriate control systems, for transient smoke emission reduction, reduced pollutant emissions and fuel consumption. The Hybrid Integrated Propulsion POwertrain (HIPPO) test bed at NTUA/LME consists of a medium-duty, turbocharged marine diesel engine, with electronically controlled fuel injection, producing 448 kW, a water brake and an AC electric motor with frequency inverter rated at 110 kW, mechanically connected on the same main drivetrain shaft in a parallel hybrid configuration. The diesel engine runs without modifications, so that the injected fuel is independently regulated by the factory installed ECU. The main purpose of the electric motor in the HIPPO powertrain is to assist the diesel engine at lower speed bands, where the engine produces low torque, to meet up with the increasing torque demand faster. For the hybrid diesel electric powertrain, an energy control management strategy is put forward, which calculates the required torque from the electric motor in order to track the reference air-to-fuel ratio/stoichiometric (λ-value). The designed robust model-based controller, utilizes the measured IC engine λ-value as a feedback signal, while the control output is the command signal of the electric motor frequency inverter. The reference λ-values are stored in lookup tables (static maps) which consider engine parameters, such as produced torque, speed and intake manifold pressure, derived from experimental data during steady-state operation. Mathematical models from system identification were used in order to develop controllers that are fine-tuned to the dynamical system examined and take into account the uncertainty present. The linear models that describe the behavior of λ-values during loading transients, for the hybrid diesel-electric setup, are based on experimental data and system identification procedures, during transient operation. The control requirements in robust control are achieved through the specifications of the weighting functions. The feasibility and validity of the proposed control strategy was tested experimentally, using rapid prototyping development tools. A setup is developed in SIMULINK to implement the derived controller in the testbed through the A/D (sensors) and D/A (actuators) interfaces of a dSpace platform. The tested loading time series is based on measured performance data from a fast ferry during a standard schedule commercial trip, including several stops, with different transient engine loading conditions after departure from a number of harbors. A comparison between the hybrid powertrain and the standard engine setup (without the assistance from the electric motor), shows that during transient loading conditions, the benefits of the hybrid setup are lower visible smoke and reduced NOx emissions. The impact on the fuel consumption during transient loading is also evaluated, using a set of high accuracy fuel flow measurement

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。The IMO Tier III legislation applicable from 1 January 2016 has forced engine designers to develop new engine technologies that require new comprehensive control strategies. MAN Diesel & Turbo has chosen a two-technology approach for its two-stroke engines, supplying both exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) to the engine makers. Both systems will be controlled by the emission reduction control system (ERCS). While some features of the SCR and EGR solutions on large two-stroke engines are inspired by similar and well-known solutions from the car industry; other features have completely new challenges. Some of the challenges may be that the technology is placed upstream of the turbocharger, the sulphur-containing fuels used, the application of the technology on a two-stroke engine or a combination. The basic control principle for EGR is feedback control of scavenge O2. However, as O2 sensors have slow responses, model-based control is proposed for improved O2 control in transient operation. As EGR changes the smoke margin, the EGR rate must be taken into consideration especially during vessel acceleration; though with proper control, acceleration may even be improved on an EGR engine. Furthermore, as the recirculated gas is cleaned with water, the water requires proper control of pH. As SCR reactant dosing is similar to that of the car industry, the primary challenge on marine engines is to avoid formation of ABS in the reactor or boiler by the applied dosing strategy. From a thermodynamic perspective, when the SCR is placed upstream of the turbocharger, the heat capacity of the SCR heavily affects the energy balance and thus the airflow of the engine. This requires dedicated control, not least while engaging and heating the SCR with the exhaust gas. This paper presents details on the above challenges and solutions as well as presenting the basic operating and failure handling principles, the system layout and not least compliance in practice.

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。Diesel is a complex nonlinear device. This is a challenge to the control system.MAP is widely used to achieve proper performance. MAP calibration is time-consuming and even special skill needing. Intelligent control algorithm has been proposed to improve this situation. Intelligent control theory has been discussed many times so the focus of this paper is on engineering realization. Application target is diesel speed control. Three parts is included in this research: principle design and simulation validation, controller development and software framework, and the last part bench test and result analysis. A self-adaptive diesel speed governor strategy based on BP neural network and PID is designed. BP neural network is used to modify the speed-loop PID parameters, while the rack-loop is controlled by traditional PID. To validate the feasibility of the new control strategy a MATLAB/SIMULINK mean value model is built. A physics model of proportion electro-magnet actuator and an experiment data based oil pump mode are included in the model. Loading experiment confirms the self-adaptive competence of designed BP-PID control algorithm. Neural network can be used to learn any nonlinear system, but the fact is that neural trend to learn the non-existed correlation during the transient process of diesel engine, it is also called over-learning. To avoid this phenomenon, learning method with supervision is developed. Base on the characteristic of neural network calculation requirement analysis is discussed in detail, especially the demand for MCU. A neural network controller is designed based on STM32F103 micro control unit. To meet real time requirement of diesel control system software framework of key function should be specially built. Foreground and background, time sharing concept of OS has been adopted. Finally, the last part is performance contrast experiment. Bench experiment is carried out on a D6114 diesel to verify the governing performance of the system. Start experiment, steady state experiment and load sudden change experiment are conducted. Attention is paid on starting overshot, setting time and overshot during load sudden change, system robustness in the whole operating range. The experiment results are compared with that of traditional PID. The data analysis suggests that BP-PID control strategy may have similar performance with tradition PID but the improvement of robustness and idle speed performance is obvious. Consideration can be given to high speed, low speed, high temperature and low temperature. Speed fluctuation in idling speed is improved. The most important the system stabilize is reliable enough. STM32F103 MCU is capable of running a neural network control system.

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。In the field of marine application, natural gas fuelled engine is a promising successor of Diesel engine, owing to lower emissions and fuel cost. However, the marine application imposes vast requirements on transient responses, such as ship manoeuvring requires fast response to the load demand, in rough weather the engine is exposed to large load fluctuation, etc. Moreover, the engine can be coupled to a fixed pitch propeller (FPP), controllable pitch propeller (CPP) or electric generator specifying various modes of operation. In respect that the gas engine combustion process differs from that in Diesel engine, the load acceptance is subject to specific limitation due to a knock and misfiring phenomena. Thus, for the gas engine to be efficient and safe propulsion unit, it is necessary to consider the problems related to transient response behavior and develop countermeasures. The paper employs mean value approach for constructing the engine model where non-linear dynamics are modelled from first principles using available non-linear characteristics of essential components. In order to capture the particularities inherent to the gas engine, notably air throttle valve and fuel gas admission valve, the nonlinear model of components has been developed and discussed in details. The nonlinear model is parametrized from the engine test data and model fitness is then confirmed. Finally, the paper discusses the derivation of a linearized model of the target engine which is necessary for transfer function model describing the transition from the inputs to the desired outputs. The transfer functions constituent parameters can be readily obtained from the fully parametrized nonlinear model at any operating point, thus facilitating study on engine frequency characteristics and uncertainty of model parameters. In this study the experimental data obtained from the lean burn gas engine of Yanmar AYG20L were used to develop a simulation model suitable for purpose of control algorithm development, also the engine model unit can be used as a part of power plant model facilitating the development of clever load management system.