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Cimac Congress | Shanghai 2013 cylinders (three ECUs) in preparation. Common ECU SW with individual functions, e.g. twin air flow and fuel pressure control (left/right engine bank) for multi ECU systems are configurable in the SW build process. With SW sharing, the customer can realise its own SW functions on the supplied ECU HW and SW platform. Homologation for the most important ship classification societies for the ECU and a set of common used engine sensors is in progress. Pre-compliance tests have been performed and the final compliance test is in preparation. In cooperation with Bosch Rexroth an interface for the integration of the ECU engine control management system into the Rexroth ship automation system is developed. This technical paper will describe the Bosch electronic engine management system components for the medium- and high-speed engine applications. Wednesday May 15th / 15:30 – 17:00 Fundamental Engineering – Thermodynamics 1 Room A Optimal utilisation of air- and fuel-path flexibility in medium-speed diesel engines to achieve superior performance and fuel efficiency Alexander Knafl, MAN Diesel & Turbo SE, Germany Gunnar Stiesch, MAN Diesel & Turbo SE, Germany Markus Friebe, MAN Diesel & Turbo SE, Germany With the development of common rail fuel injection systems, variable geometry turbochargers, variable valve timing and combustion feedback systems, medium-speed diesel engines offer substantial control flexibility with the potential of significantly improving performance, fuel economy, emissions and thus customer value. Engine performance - traditionally governed solely by the mechanical system - is increasingly dependent on the interaction of the flexible subsystems and their proper control. This paper seeks to demonstrate the benefits offered by variable airpath control in combination with a fully flexible common rail fuel injection system. System interactions and optimisation are analysed and performed with design of experiment (DoE), response surface modelling and constraint merit functions. Above mentioned method is applied to design custom-tailored medium-speed engine maps for constant speed generator, controllable pitch as well as fixed pitch propeller operation. Engine performance data are obtained via engine dynamometer experiments augmented with analytical simulations. With constant speed generator operation, it is shown that through optimising the engine calibration in accordance with the typical load profile thereof, specific fuel oil consumption is reduced by several grams without related engine hardware changes. The potential of applying engine control maps specifically tailored to the mode of operation, e.g. fast steaming, slow steaming or manoeuvring, the operation is assessed and the potential quantified. This so-called multi-mapping approach allows for improved performance and reduced emissions over the entire operating regime of the engine. In addition to steady state operation, benefits in transient response are demonstrated by means of optimised air- and fuel-path control. Particularly load rejection and smoke emissions are substantially improved over conventional, mechanically rigid systems. Lastly the affect of Tier III exhaust gas treatment solutions - selective catalytic reduction (SCR) to reduce NOx and or scrubbers to capture SOx - on engine performance is investigated. It is shown that Tier III exhaust gas treatment systems may adversely affect engine performance through increased exhaust gas backpressure and the requirement of elevated exhaust gas temperatures. By means of optimally adjusting the engine control to the new boundary conditions, it is demonstrated that engine performance and efficiency can be restored to Tier II levels. Analysis and optimal design on air intake system of controllable intake swirl diesel Guixin Wang, Harbin Engineering University, China Xiaobo Li, Harbin Engineering University, China Gongmin Liu, Harbin Engineering University, China Xiaoli Yang, Harbin Engineering University, China Xiaoxiao Niu, Harbin Engineering University, China Choosing one marine controllable intake swirl diesel as the research object, this paper does some calculation and analysis on the intake flow field by using a 3D flow field analysis software, obtains the swirl ratio and the flow coefficient of the target diesel in different valve lifts and intake baffle angles, and finds that the intake swirl of the diesel has a two-stage characteristics, namely the value of the swirl changes from high to low. On the basis of the calculation and analysis of the diesel air intake system flow field, this article completes the structure optimisation design of the diesel intake, and gets the laws of the swirl ratio and the flow coefficient influenced by the structure of the diesel intake. At the same time, this paper verifies the calculating results through using the steady flow test of the diesel air intake system, and ensures the accuracy and reliability of the diesel air intake system calculating analysis and design optimisation. Investigation of extreme mean effective and maximum cylinder pressures in medium-speed diesel engines Peter Eilts, Technical University Braunschweig, Germany Claude-Pascal Stoeber-Schmidt, Technical University Braunschweig, Germany The current level of mean effective pressure (mep) of mediumspeed diesel engines is 25 to 28 bar. Maximum pressure (pmax) is about 230 bar. At the Technical University Hamburg Harburg, a research engine with a mep of 40 bar and a pmax of 350 bar has been operated successfully with good results. This led the authors to investigate what can be expected when operating at even higher pressures. In a theoretical study the mep of a 320mm bore medium-speed engine was increased up to 80 bar. A zero dimensional cycle simulation program was used for the calculations. Compression ratio, stoichiometric air ratio, valve timing and mechanical efficiency were kept constant. Several strategies concerning combustion and turbocharging efficiency (etaTC) were investigated. Some results: With a constant etaTC of 70% and constant rate of heat release (ROHR) an increase of mep above 60 bar is not possible, because the scavenge pressure difference becomes negative. Specific fuel oil consumption (sfoc) increases slightly. The exhaust temperature before turbine (TbT) rises significantly. With constant ROHR and a constant ratio of pressure before turbine and charge air pressure a mep of 80 bar is possible. TbT decreases slightly, sfoc decreases by 5%. The required etaTC is above 80%. Thermal load of course increases significantly. In all cases the required charge air pressure (pch) and pmax rise approximately proportional to mep. For a mep of 80 bar, the first reaches 15 to 16 bar and the latter 750 to 800 bar. Using a jet mixing model, two strategies for injection and combustion were investigated. In both the injection duration was kept constant. If the nozzle area is increased proportional to the injected fuel mass, the ROHR is unchanged and so are the operating data. The nozzle hole diameters become very large so smoke problems have to be expected. Injection pressure rises only moderately. If the nozzle area is increased 60 SPECIAL Schiff&Hafen | Ship&Offshore | May 2013
Monday, May 13th Tuesday, May 14th Wednesday, May 15th Thursday, May 16th proportional to the square root of the injected fuel mass injection pressure rises above 3,000 bar and the operating data improve. Sfoc for example is reduced by another 2.5%. Summarised it can be stated that improvements in operating data are possible. The challenge is to control the high mechanical and thermal loads and to provide the required high efficiency of the turbocharging system. A fundamental study on improvement of ignition behavior of low ignitability fuel with pilot injection Satoshi Kawauchi, National Maritime Research Institute, Japan Masahide Takagi, National Maritime Research Institute, Japan New regulations of the IMO, introducing drastic reductions in fuel sulphur content, allow 0.1% sulphur in fuels used in ECAs, starting from 2015. Together with the worldwide situation of decreasing fuel resources, the introduction of alternative fuels complying with future regulations of marine diesel fuel displays an important research these days. Light cycle oil (LCO) also referred to as ’cracked gas oil’, a sub-product from the FCC process in refining, has the potential to be used as an alternative for current marine fuels. LCO shows a high content of aromatic hydrocarbons, mainly composed of one and/or two ring aromatics. In general, aromatics are chemically less reactive compared with paraffinic compounds and therefore it can lead to a strong deterioration of the ignition and combustion characteristics. Especially for medium- and high-speed engines, the deteriorated combustion characteristics, such as long ignition delay, long after-burning and long flame-length, could result in the trouble for the piston ring and cylinder liner causing the dry-out of the lubricating oil film. Pilot injection is one of the techniques to reduce the difficulty in the engine operation with low ignitability fuel. Experimental results show that the pilot injection enables the engine to operate on the LCO smoothly without causing excessive pressure rise rate. On the other hand, the result shows that the heat release rate is significantly affected by the fuel injection quantity and timing. It implies that injection parameters for pilot fuel should be optimised in order to realise the reliable operation. Considering that the ignition behaviour of pilot fuel heavily depends on fuel ignitability, it is expected that optimal injection parameters depend on the fuel ignitability. Therefore, in order to utilise pilot injection under several conditions for fuel ignitability, it is important to obtain deeper understanding on the roles of how pilot injection influences the improvement of the ignition behaviour. This study investigates the effects of pilot injection on the ignition behaviour using a rapid compression machine. Pilot injection parameters were varied systematically under different two ambient gas temperatures with two types of fuel. Shadowgraph was applied in order to obtain detail information on ignition process promoted by pilot injection. Visualisation results provided detailed explanation on the roles of pilot injection in ignition event of main fuel. Wednesday May 15th / 15:30 – 17:00 Room B Environment, Fuel and Combustion Gas and Dual-Fuel Engines – Combustion Aspects The MAN ME-GI engine: From initial system considerations to implementation and performance optimisation Lars Ryberg Juliussen, MAN Diesel & Turbo, Denmark Stefan Mayer, MAN Diesel & Turbo, Denmark Michael Kryger, MAN Diesel & Turbo, Denmark The ME-GI concept is based on a diesel-type combustion process of a gas jet that is injected into the combustion chamber with high pressure between 150 and 315 bar depending on engine load. The ignition of the gas is ensured by the injection of a small amount of diesel oil prior to gas injection - the pilot injection. This paper describes the ME-GI concept and its implementation on a dedicated test engine as well as on a production type engine. Furthermore, it also presents performance and emission results from a subsequent optimisation effort. Successful development of the ME-GI concept required a suitable research facility platform for thorough investigations and engine tests. Therefore, it was decided to retrofit an electronically controlled two-stroke low-speed marine diesel research engine, 4T50MEX, to gas operation. Retrofitting the research engine to gas operation required the development and installation of gas engine components as well as the development of a new control and safety system, which is added to the standard electronic control system. Before adopting all new components and software to the research engine, preliminary tests were carried out on a one-cylinder gas test rig in order to verify the functionality and reliability of the ME-GI concept. The establishment of the gas research platform also required considerable preparations in order to achieve authority approval of the gas supply installation, which was established according to EU’s ATEX regulations (e.g. Directive 94/9/EC, concerning equipment and protective systems intended for use in potentially explosive atmospheres). The ATEX regulations required for example risk analysis, zone classification plans and education of engineering staff. The engine tests performed can be divided into a two groups. Firstly, the ME-GI engine is benchmarked directly against operation on liquid diesel oil. This benchmark confirms a significant reduction in NOx emission. The NOx reduction exceeds 25% on average, which is consistent with simple theoretical estimates based on adiabatic flame temperature equilibrium NOx predictions, where the main driving force is a lower flame temperature due to a higher stoichiometric air amount for methane compared with diesel. Secondly, in order to explore the possibility of even further optimisation of the ME-GI concept a more elaborate study, applying theory from Design of Experiment (DoE) as well as Response Surface Methodology (RSM), is conducted, in which parameters related to the gas injection system are included as well. It is demonstrated that the ME-GI concept offers potential SFOC savings of 3-6 g/kWh in the part load range (below 85% engine load). The engine test data are furthermore supplemented with results from optical diagnostics. High-pressure natural gas injection (GI) marine engine research with a rapid compression expansion machine Dino Imhof, Kyushu University, Japan Daisuke Tsuru, Kyushu University, Japan Hiroshi Tajima, Kyushu University, Japan Koji Takasaki, Kyushu University, Japan The use of natural gas as fuel for vessels is a highly promising solution to meet the challenges of technical compliance requested by upcoming CO2, SOx, NOx and soot emission regulations. In gas injection (GI) engines, gas sprays burn as diffusive combustion without knocking or misfiring. The thermal efficiency is high because a high compression ratio, equal to diesel engines, can be applied. However, unlike lean burn gas engines, an additional device, such as an EGR or SCR system, is required to meet IMO Tier III NOx regulations. In order to analyze and understand the combustion processes of such potential concepts to reduce emissions, a rapid compression expansion machine (RCEM) with relevant dimensions of marine engines has been developed at May 2013 | Schiff&Hafen | Ship&Offshore SPECIAL 61
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