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。In practical applications, NOx removal efficiency and urea consumption rate of SCR system are strongly dependent on the spray atomization and mixing process of reducing agent in the exhaust gas. On the basis of computational fluid dynamics(CFD)coupled with chemical reaction kinetics, spray atomization characteristics and mixing performances for a SCR system in the marine diesel are studied in the paper. It is found that a uniform mixing of urea solution in the exhaust flow cannot be achieved by the limitation of large scales and high flow rates of marine diesel exhaust systems. However, the mixing performances can be enhanced obviously by the installation of multilayer mixer in the exhaust upstream of the catalyst. It is also proved that the calculated value of DeNOx rate of the marine diesel at full load is very close to the measured rate-91% at 5.3 gallons per hour of urea solution consumption rate, and working performances of the SCR system can be predicted well by the model built in the paper.

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 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 Kyushu University. The RCEM is utilized as a research model for GI engines. An electronically controlled high-pressure gas injection system enables injection pressures of up to 50 MPa. Diesel pilot sprays in dual fuel mode as well as glow plugs are used for ignition. Air conditions in the cylinder at the gas injection are about 10 MPa and 550 °C, simulating a current GI engine. In a first series of experiments, a cylinder head with a cubic shaped clearance volume and an observation view of 200 mm in width and 50 mm in height is applied to analyze the spray combustion. In the experiments, pure methane, the main component of natural gas, is used. At first, the GI combustion is compared to the diesel spray combustion. As a result, rates of heat release for GI and diesel combustion are comparable, while the emissions decrease by using gas. However, the direct photos taken with 20’000 fps show a different flame behavior between the two fuels. Such differences in the flame characteristics are examined in detail applying the ’Laser shadowgraph’ and the ’BDL (Back Diffused Laser)’ optical techniques. Furthermore, in order to meet IMO Tier III NOx regulations, the oxygen content of the intake air is reduced as a good approximation for an Exhaust Gas Recirculation (EGR) system. As expected, the brightness of the flame decreases and a NOx reduction of 75 % in 17 % O2 can be achieved. For a second series of experiments, a cylinder head with a cylindrical clearance volume is newly developed to allow different swirl velocities and an observation view over the whole 240 mm in diameter window; the side injection system corresponds to a common two-stroke engine. Injection nozzles with different numbers of injection holes are tested, applying different injection pressures, and multi flames are visualized. In conclusion it can be stated that experiments with the RCEM help to determine emission influencing parameters and optimization potential, to visualize and to analyze phenomena that have not been simulated yet.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The IMO (International Maritime Organization) Tier lll regulations against the emissions from vessels require rigorous reduction of SOx(Sulphuric Oxides) as well as PM(Particulate Matter) and NOx(Nitrogen Oxides). From 2015, LSFO (Low Sulphur Fuel Oil) required in ECA (Emission Control Area) should decrease its sulphur content to 0.1 mass% of fuel, which is equal to one tenth of the present sulphur level required of LSFO (Low Sulphur Fuel Oil). The NOx emission rate [g/kWh] should be reduced by as much as 75% from the present tier ll level from 2016. Although various anti-NOx-pollution technologies, like an EGR (Exhaust Gas Recirculation) or a SCR (Selective Catalytic Reduction) have been ardently investigated, there exist three strong obstacles to inhibit these technologies from practical use. The first is sulphur content of the LSFO still high enough to result in metal corrosions in the EGR system by sulphuric acid and in catalyst occlusion in the SCR system by ammonium hydrogen sulphate after long term use. The second is a wider load range required for propulsion engines by the emission regulation in marine sector. It is difficult in general to adjust the exhaust clarifying devices especially at low-load operations, since the enthalpy of the exhaust gas is not sufficient to activate such devices. For example, more EGR rate is necessary in lower-load conditions to avoid severe combustion deterioration due to the lack of oxygen, but this implies more power consumption of an EGR blower in the system and the total thermal efficiency could be disastrous. The third is the additional operation cost of the NOx-reduction systems. The EGR system needs a neutralizing treatment system of the sulphuric acid scrubbed down from the EGR gas and the SCR system consumes urea or ammonia water according to the NOx concentration in the exhaust pipes. Moreover, the LSFO would be very expensive marine fuel as long as it is supplied with gas oil classification of low sulphur content, so that other low-sulphur yet inexpensive components are desirable to burn in marine engines. On the whole, a supplementary and economical anti-NOx, pollution system is definitely wanted to cover the lower-load range without fear of the cost increase in fuel consumption and device operation. From above point of view, PCCI (Premixed Charge Compression ignition), which has been studied in smaller on-road fields for long time, could be a practical remedy for the first time for the emissions from marine diesels. In this study, a new PCCI combustion system is proposed to achieve drastic NO, reduction for marine diesels. This system utilizes a set of sprays from closely aligned holes having injection directions intersecting one another so as to cause mutual interaction and merger of the sprays by overlapping injection periods and applying different injection rates. It can enhance the mixture stratification suitable for the PCCI combustion. As for the cheaper substitute of the low-Sulphur gas oil, neat LCO (Light Cycle Oil) was also firstly introduced as a potential LSFO in this study. LCO is composed from distillate components produced in a FCC (Fluid Catalytic Cracking) process in modern oil refinery plants and it has sometimes notoriety for its poor ignitability thanks to its high aromaticity. LCO was casted in a new light here by utilizing its good valorousness and its long ignition delay for the PCCI combustion. Lower-load operation also favours the PCCI concept because the abnormal combustion of the PCCI mode usually happens at higher-load conditions. The durability against the preignition of LCO was greatly enhanced by water emulsification. The potential of the strategy was examined through observation of the spray merging and combustion process in a rapid compression expansion machine. All in all, the ignition control of PCCI combustion in large engines was successfully realized for the first time.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 Tier lll emission control of the International Maritime Organization (IMO) requires the substantial reduction of nitrogen oxides(NOx) emission from marine diesel engine. Tier lll is expected to require a dedicated NOx emission control technology such as the selective catalytic reduction. In our experience of on-board catalyst test in an exhaust gas of heavy fuel oil (HFO) and the subsequent development and evaluation of the urea-SCR system are described in this paper. The preliminary catalyst test was con-ducted by the slipstream type reactor mounted onto a marine diesel engine which was fueled by high sulfur HFO.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The future emission legislation for marine applications stipulates a considerable reduction of nitrogen oxide pollutants. In 2016, the IMO will enact the emission standard Tier lIll for emission controlled areas (ECA). Whereas engines operated at open sea will keep the less stringent emission level Tier |Ⅱ. Dual fuel engines provide the possibility to run in different propulsion modes which are suitable for the permit-ted emission levels. On open sea, a dual fuel engine can be operated IMO Tier lI compliant in Diesel mode with cost efficient heavy fuel oil. In ECA, dual fuel engines run on natural gas to fulfill the upcoming emission regulation IMO Tier ll. The operation and inter-action of Diesel and gas mode result in complex control structures for dual fuel engines. In each propulsion mode, the engine shall provide a reliable operation with an excellent transient behavior. At the same time, engine durability and safety aspects may not be neglected. Hence, the development of an engine control system (ECS) for dual fuel engines represents a notable challenge. Generally, the development process for engine control systems includes the elaboration of control software which has to be tested and calibrated on engine test bed. This approach contains two major drawbacks. First, the availability of proto-type engines is limited especially at the initial development phase. Second, engine test bed operation is ex-pensive and increases the overall costs for the engine development. Within this paper, AVL shows a possibility to improve the development process of ECS software. A close interaction of the tools Simulink from The MathWorks and AV's BOOST RT is used to set up a simulation environment BOOST RT provides the plant model of the engine. Its thermodynamics and flow characteristics are simulated in the time domain using steady and unsteady OD and quasi-dimensional component models. Responsiveness of engine sensors as well as the behavior of actuators is also included in the BOOST RT model. ECS control concepts are modeled in Simulink. The BOOST RT inter-face in Simulink allows a model-in-the-loop (MiL) simulation of ECS software and engine plant model. Furthermore, BOOST RT is capable to generate a surrogate of the engine plant model. This also can be done for a part of the model and in combination with the remaining crank angle resolved model. Thus, the computing time can be tailored for real-time applications on a hardware-in-the-loop (HiL) test bench considering also slow computers or complex models. On the Simulink side, autocode and flash tools are used to implement the control functions into the target ECS hardware. As a consequence, a HiL simulation of the control functions running on the ECS hardware is set up to test and calibrate the ECS application software. In summary, the coupling of BOOST RT and Simulink allows a validation of ECS control functions in an early engine development phase. Engine test bed time can be reduced through the use of control functions with a relatively high maturity level and calibration efforts are minimized by pre-parameterized application datasets. The advantages of this improved development process will be shown by means of chosen engine control functions used in Diesel and gas mode of a dual fuel engine.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 Quality of marine fuels has changed for the last 10 years, and it is well known that they have been getting heavier and lower in viscosity resulting in poorer combustion quality. This is caused by recent advancement of oil refining process, eco-nomic trend and increasing needs for light distillates, and environmental regulations. Ignition and combustion performance are affected by various factors including the characteristics of the fuel, engine design, operational conditions and settings of the engine, ap-plied load, and ambient conditions. Residual fuels are mixture products consisting of vacuum residue (VR)and some intermediate products of oil refinery process. Thus, to analyze the blending process and characteristic of the residual fuels may lead to better under-standings of the combustion process in diesel engines and taking countermeasure against possible engine damages. In this study, the effect of chemical com-position of residual fuels on its ignition and combustion quality was investigated. The blend compositions were estimated by thermal and chemical analyses and discussed with the results of combustion characteristics. The sample fuels were blended with different pro-portions of a straight-run light gas oil (LGO), a vacuum gas oil (VGO), a FCC light cycle oil(LCO),a FCC clarified oil (CLO) and a VR. These blending components and sample fuels were also used to know the quality control of the commercial marine fuel oils. The chemical compositions of these fuels were analysed by using thermogravimetry (TG) and gas chromatography/mass spectroscopy (GC/MS). The TG analysis in a nitrogen gas flow and GC/MS gives a distillation curve of fuels and a detailed composition profile of the lower-boiling components, respectively. Their ignition and combustion analysis were also carried out by using Fuel Combustion Analyzer. According to the GC/MS, LCO and CLO were characterized by mainly2-ring (especially methyl-, dimethyl-and ethyl- naph- thalenes) and 4-ring polycyclic aromatic hydrocarbons (methyl-and dimethyl-pyrenes), respectively. The results suggest that the fuel ignition quality is significantly affected by the amounts of both 2-ring polycyclic aromatic hydrocarbons and relatively lower molecular weight alkane series(C14-C18), which are interpreted as the amounts of LCO and LGO. Some of the commercial marine fuel oils were found to be' gap-fuels', which were estimated to containing only LCO and VR.They exhibited a very low Estimated Cetane Number(ECN), almost the same as that of pure LCO, and can potentially result in serious engine damages.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The introduction of IMO-TIER ll in 2016demands a reduction of NOx-emissions by 75% compared to IMO-TIER lⅡ. This cut in emissions is only to be achieved by applying new technologies to ship diesel engines. One promising option to reduce emissions by engine internal measures is the introduction of exhaust gas recirculation (EGR). In order to control particulate emissions as well as fuel consumption, this technology can only be applied when significantly improving the fuel injection system at the same time. The presented work focuses on the impact of injection rate shaping on the emissions of a medium speed diesel engine. The approach is based on the idea to generate very specific injection rates, which are referred to have a positive effect on engine emissions, by simple hydraulic considerations. Therefore, the existing common-rail injection system of the medium speed research engine 1 VDS 18/15 has been modified and extensively tested. The engine measurement results show that injection rate shaping significantly influences engine emissions. In certain points, reductions of particulate emissions of up to 70% compared to a reference set-up were achieved at constant NOx while even providing advantages in indicated engine efficiency. It is shown that especially at 50% load conditions a RAMP-like injection rate does offer the highest potential. On the other hand, no advantage is detected for the given conditions at 75% engine load. These results are confirmed by cylinder pressure traces showing how rate shaping influences the pre-mixed and diffusive combustion phase. Based on the engine results it has to be stated that hydraulic measures to control injection rates can have a considerable potential to reduce engine emissions. The possibility to influence the combustion process by applying injection rate shaping allows a fundamental analysis of combustion parameters with respect to emission generation. The presented work so provides an important basis to improve the understanding of emission generation processes in large diesel engines.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 Abstract: Gas and dual fuel engines applying the Otto cycle are commercially available solutions undercutting the NOx limits set out by the IMO Tier 3 regulation. Furthermore, it has been demonstrated that the concept of the strong Miller process enabled by two stage turbocharging and variable valve timing is an attractive solution to considerably improve the tradeoff between fuel consumption and NOx emissions for diesel engines. For gas engines, the concept can be utilised to bring the trade-off between fuel consumption and power density to a new level. The potential has been confirmed on real gas and diesel engines with excellent results. A comprehensive simulation study has been carried out in order to transfer the concept of strong Miller cycle, two-stage turbocharging and variable valve timing to dual fuel engines. The study identified great potential for improving fuel consumption in both diesel and gas mode when integrating ABB's two-stage turbocharging Power2 and variable valve train VCM ®into a seamless concept. Furthermore, the flexibility of VCM resolves some of the compromises needed when designing an engine capable of running according to the Diesel and the Otto cycle. In addition, FPP operation as well as improved manoeuvrability and load pickup for gas and dual fuel engines may be realised, as the extensive thermodynamic simulation work indicates. The publication presents the assumptions and boundary conditions that were used, the underlying modelling approach and the potential found, while also discussing expected challenges.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 Marine diesel engine face the double pressure from both the energy sources and more strict IMO emission regulation. According to a Chinese engine builder's commission, SMDERI developed a new medium speed marine diesel engine together with FEV. The new medium speed marine diesel engine must satisfy the high endurance, the fuel consumption and IMO emission regulation at the same time. Present the technical solution to meet the requirement of good BSFC and NOx emission. The success development of the new medium speed marine diesel engine will promote Chinese medium speed marine diesel engine to new technical level. This article present the combustion development of the new medium speed marine diesel engine: through performance and combustion simulation, to define the main characteristic of performance. To define the suitable miller timing, together with one stage high compression turbocharger; Through CFD and DOE technique, define the experiment case of combustion system, which contain the piston bowl, the nozzle pattern and so on. The experiment was carried out based on SCE21/32, which is specially developed for the new technical investigation and new engine combustion de-elopement. Different miller timing, different piston bowl and nozzle pattern were test, and the performance of the common rail fuel system have been studied in de-tail. Through SCE21combustion and 6CS21/32 performance test, the experiment results presented show that, for the new medium-speed engine of CS21, the NOx emission can meet the IMO Tier2 emission regulation, and the fuel consumption can achieve 185g/kW·h at the same time.

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 Increasing economic and ecological de-mands on Diesel engines have raised the injection pressures up to 3000 bar. One of the favourite ways to increase the fatigue resistance of injection parts is autofrettage, where an initial overload near the plastic limit load and following unloading generates favourable compressive stress fields around the notches. In the endurance regime, autofrettage can yield a tremendous increase of fatigue limit with crack arrest in the compressive stress field. In the finite life regime the crack initiation life benefits from the com-pressive mean stress at the notch surface, and the crack propagation from crack growth retardation in the compressive stress field. Focus is put on endurance and on fatigue strength under variable amplitude loading. Test results on tubes and notched specimens representing typical design features in pumps, rails, injectors etc. demonstrate the advantages of autofrettage and serve as basis for the validation of design methods. For variable amplitude loading the standardized load sequence CORAL (COmmon RAil Loading) is shown, representing the life of an injection system of a Diesel passenger car as well as ' CORAL ex-tended' with a large amount of additional small cycles. A variety of different life prediction approaches have been investigated. The following two design methods are discussed in the paper as they are of practical use:1. Nominal Approach using Miner's rule 2.Local Approach for crack initiation life and explicit 3D finite element simulation for crack propagation using LEFM, with crack closure and automatic remeshing Fatigue analyses using design method 2 could predict these experimental results with a high accuracy, proving the significance of advanced design methods. For practical application, design method 2 can be recommended. Method 1 can only be applied with a high level of experience usually not yet available in design groups of the industry. A considerable advantage of autofrettage is the very small scatter in life or in fatigue strength, respectively, resulting in remark-ably small safety factors for the allowable pressures at small failure probabilities. The methods developed in research for life and endurance prediction have been successfully transferred to the industry, where it has been implemented and adapted to practical needs. MAN Diesel & Turbo SE has accompanied the re-search work and has used the know-how from the very beginning. The know-how has also been applied in the development of the new Common Rail Injection System CR 2.2 for 4-stroke engines operating at 2200bar to fulfill future requirements for fuel consumption and emissions. An outlook is given on unsolved design problems concerning high frequency of small cycles, temperatures up to 200℃ and load spectra with maximum pressures below endurance.