论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。When designing fluid systems for 4stroke medium speed diesel engines it is beneficial to use modern simulation tools to achieve an optimized design in an early phase. Today's engines have become very compact and typically have a high degree of integration of fluid channels into castings. There-fore, changes to address flow problems after design is complete will require big re-design efforts and should be avoided. The heat balance of the engine determines the needed cooling water flow to achieve sufficient cooling without excessive temperature increasein the water. As the pumps used are of centrifugal type the flow in the system is determined by the system pressure drop. CFD simulation of complicated channeling as part of the design phase will ensure unnecessary pressure drop is avoided and thus the water flow through the system will be increased.A welldesigned cooling system will have the majority of the pressure drop in coolers and as little as possible in the channels and piping. Oil pumps for 4-stroke dieselen-gines must be dimensioned to ensure sufficient pressure is available in the critical components at all conditions. Overdimensioning of the oil pump will lead to unnecessary oil flow wasted through the pressure control valve. To determine the exact oil flow through the engine in the design phase is difficult, as the oil system has many consumers with different characteristics.1-D flow simulation of a complete oil system gives a sufficiently accurate prediction of the needed flow to avoid over-or under-dimensioning of the oil pump and avoid excessive pressure drop in any part of the oil system.Pressure pulsation from mechanical fuel pumps to the fuel supply line can be a source for vibration both on the engine itself but also in the external fuel piping of the installation,e.g. ship. By 1D-simulations of the fuel supply system the pulsation can be predicted and the need for damping can be determined. This paper presents successful simulation projects of all the above mentioned systems.

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。NOx emission from diesel engines is a principal toxic ingredient of environmental pollutants.Thus NO, from diesel engines has been limited by the global and local regulations which have been becoming more stringent in connection with the recent environmental problems. IMO(International Maritime Organization) Tier lll regulation which requires to reduce NOx by 75% from the current Tier ll regulation(20%reduction from Tier I regulation) will be effective in 2016. Several methods such as combustion optimization, EGR(Exhaust Gas Recirculation), water addition and high pressure turbo charger etc. have been developed to reduce NOx. Each method is not enough to abate NOx to comply with the IMO Tier ll regulation, but combination of the NOx reduction methods is able to satisfy the regulation. Hyundai Heavy Industries Co, Ltd.(HHI) has developed charge air moisturizer(ChAM) which humidifies charge air with water vapor and has also tested EGR system for NOx reduc-tion. HHI has enhanced NOx reduction efficiency by combination of the EGR and the ChAM systems on a medium speed diesel engine, and has confirmed that NOx emission was kept under the IMO Tier lIll regulation. The combination of the EGR and the ChAM system can be a candidate as the main NOx reduction technology to comply with the IMO Tier ll regulation.

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。 The choice of oil drain interval(oil life)in engines burning natural gas fuel represents a cost-benefit balance. Longer oil life lowers the costs for oil purchase, labour, and equipment downtime, the last usually being the most valuable. More frequent oil changes may extend the overall life of the engine and reduce long-term maintenance costs, as well as provide a margin of safety and psychological well-being. Somewhere in between is the optimum for a given engine make, model, fuel composition, and service. Oil drain intervals for large industrial gas engines are often determined by used oil analysis. Typical parameters, such as viscosity and acid number increase; basenumber decrease; oxidation and nitration by infrared; and wear metals content are compared to recommen-dations from the engine manufacturer, the analysislaboratory, or experience. However, oil analysis may not give a reliable indication of expected engine life or long-term engine condition.A series of field tests was conducted to determine the factors affecting oil life and engine durability. Differences among engine makes, models, and configurations that affect oil life are shown, including brake mean effective pressure （BMEP），oil sump volume，brake specific oil consumption（BSOC），and air:fuel ratio.Stoichiometric（入=1），lean burn（入= 1.5），and ultra-lean burn（入=2.0）configurations are shown to give significantly different stress on the oil and therefore，different oil life.Thevalidity of typical used oil condemning limits was explored by extending oil life beyond the recommended limits.Generally，oil drain intervals may be extended beyond common guidelines with no apparent harmful engine effects，although there may be warranty implications.In addition to used oil properties，wear and cleanliness resulting from the extension of oil drain intervals were examined.As expected，longer oil drain intervals-for constant engine model，fuel，service，and engine oil-led to increased deposits，which may or may not affect engine life.Wear was much less sensitive in these highly hydrodynamic engine designs. Based on these findings，a new engine oil formulation is demonstrated to double the oil drain interval of the previous best in class'product，without sacrific-ing wear，cleanliness，or used oil analysis parameters.The probable limitations of extended oil drain intervals are discussed and predicted.

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Large-bore natural gas engines are a promising technology to meet future demands for ervironment-friendly cogeneration and industrial applications. The challenge to develop ultra-lean mixture combustion processes with the highest thermal efficiency and power output, under terms of lowest level of raw emissions is strongly affected by the capability for a stable and reliable ignition process. The ignition in the main combustion chamber is usualy initiated by flame jets of a gas-scavenged prechamber spark-ignition system. To examine the potential of an increased equivalence ratio level in the main combustion chamber,a detailed knowledge and understanding of the prechamber jet propagation process is essential. An exclusive thermodynamic investigation is not able to show spatial and temporal details of lean mixture combustion processes. For a comprehensive study, the thermodynamic investigations have to be combined with optical measurement techniques. The results presented in this technical paper were carried out using an MAN 32/40 multi-cylinder research gas engine, equipped with a prechamber spark-ignition system. The integration of the endoscopic optics was realized so that design changes were maintained at the lowest possible level. This ensured that the engine could be operated during these optical investiga-tions very much like a corresponding series production variant. The optical access was prepared as a kink-angle arrangement which enables observation of the prechamber jets, beginning with the initial penetration and continuing with the ignition of the lean mixture in the main combustion chamber. An improvement of the lean mixture combustion process requires the detailed observation of the prechamber jet characteristics. This was realized with an endoscopic high-speed camera system in combination with a UV-intensifier, visualizing the chemiluminescence intensity of the flame front propagation. The camera framing rate was set to 9kHz. The measurement setup was used to analyse the characteristics of three different prechamber de-signs.A precise observation of the orifice diameter's influences was arranged in a way so that an individual prechamber jet wasoptically isolated' in the field of view. This arrangement offers a selective detection of an individual prechamber jet. Three different orifice pattern designs with various diameters have been tested. The total cross section area of the orifices was kept constant for all prechamber designs. The tests, performed at various operating points, reveal theprechamber characteristics in the context of jet propagation area, spatial and temporal formation, penetration length, and chemiluminescence signal intensity. In addition, the measurement setup was used to identify and evaluate irregular combustion phenomena occurring before and even during the prechamber jet propa-gation. The results, presented in this technical paper, show exemplarily the potential of high-speed imaging investigations to enhance understanding of prechamber jet ignition characteristics and to be an effective method to help meet the challenge to improve future lean mixture large-bore natural gas engines.

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。 In this study, experimental and simulated investigations on the effects of charge density(p tdc), temperature(Ttdc) and oxygen concentration(9 O2) on the emissions and thermal efficiency of high brake mean effective pressure(BMEP) diesel engines were conducted. Experimental studies were conducted in a modified single cylinder engine equipped with variable mechanisms of boost, exhaust gas recirculation(EGR), intake valve closing timing(IVCT)and a flexible fuel injection system to regulate the p tdc,p O2 and Ttdc. Simulations of engine combustion processes were performed with an ECFM-3Z combustion model. The results revealed that higherp tdc, leading to lower overall fuel/oxygen equivalence ratio, enhanced the rate of mixing and chemical reaction and benefited improvement of the thermal efficiency. It was found that increasing charge density played two opposite roles in NOx formation: one was inhibiting combustion temperature rise due to in-creased total heat capacity of the charge and another was increasing the mixing rate. The role of less EGR ratio used in high brake mean pressure (BMEP) was essentially to decrease mixing rate of fuel and oxygen and then the chemical reactivity of the fuel/gas mixture. Higher charge density, combined withmoderate EGR ratio, resulted in decreasing over rich mixture(Φ>2) due to increased mixing rate with higher charge density and reserving the in burning fuel as incomplete combustion products CO in beginning phase of combustion, because a larger amount of richer mixture(local equivalence ratio 2>Φ>1) was formed due to relatively lower mixing rate with the existing EGR gas. Thereby the soot formation rate was drastically reduced. Higher charge density combined with moderate EGR ratio led to a retardation of the rate of heat release(ROHR),a reduction of the tempera-ture of combustion gases(Tb) and the high temperature abidance scale(HTAS), which was defined in this study as a measurement of mass averaged temperature in the cylinder, decreased NO, emissions. And it was confirmed that finally exhaust soot depends on the later phase burning rate of CO formed in combustion first phase as mentioned above. The reduction in the temperature at the top dead center Ttdc was realized by retarding IVCT, which was proved to be an effective strategy for controlling combustion in high BMEP-clean diesel engines at meddle-full loads operating conditions. Keywords: High BMEP diesel en-gine; Combustion path; Emissions, Efficiency, Charge density; Oxygen concentration; LTC-Diesel

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Marine Engines are fitted with several filters in the fuel line to keep out substances that may enter the engine and cause damages. In the last few ears, partial to complete blockages of filters have been experienced in several marine engines. The consequence has been unscheduled stoppages of engines, blackout due to complete power loss in some cases and drifting in high seas risking the safety and security of the ship. There are no standards and pro cedures to assess the filterability of bunker fuels as they pass through the fuel systems of the engines Some work was carried out by shell in this area. How ever this did not gain industry acceptance since it called for a very large quantity of bunker fuel sample3 liters). There is an existing astm method for determining Filter Blocking Tendency. However this covers only distillate fuels, biodiesel fuel and blends of these fuels and not bunker residual heavy fuels. The current method adopted to identify potential filter blocking in fuels is to carry out a GCMS/FT-IR analysis and iden tify and quantify substances/contaminants that cause this problem. This method takes much longer time and is much more expensive. This paper describes a Fil-ter Blocking Tendency test which will need only 300mL of the fuel sample (which is available in the cur- rent bunker fuel sampling procedures). In this setup300 mL of fuel is pumped at a constant rate and pres sure and temperature developed are recorded simul-taneously. Using proprietary software, the changes in pressure and temperature of the fuel oil are recorded at set intervals as they pass through the filter medium A pressure v/s volume curve is plotted and the Filte Blocking Tendency Number(FBTN) is generated after each test. By correlating the lab test result with the actual filter blocking problems experienced by ships, FBTN number has been fine-tuned to provide a clear indication if the fuel is likely to block the filters on the ships main and auxiliary engines. Various parame ters have been adjusted to reflect the conditions on the ship so that a realistic FbtN can be generated

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Natural gas has received much attention as the new energy source due to its cleanness and low price. There are a lot of interests and researches about gas engines and Hyundai heavy Industries co LTD(HHI)also developed H35/40G gas engine successfully in 2010. Further researches including experiments and simulations proceeded to improve efficiency. For the minimization of the methane slip, the optimization of the gas supply timing and pressure was conducted and effect of the reduction in crevice volumes was evaluated. Ignition timing and AFR were varied to investigate the gas engine operating characteristics. The operating condition for the highest efficiency could be estimated and the maximum efficiency and limiting factors to the higher efficiency were found with the initial engine specifications. The numerical simulations were carried out to optimize the main components of the gas engine combustion systempre chamber, valve timing intake port and piston bowl The volume of prechamber was the dominant factor to control combustion speed. Advanced miller timing with the turbocharger matching was investigated and the higher flow coefficient and proper swirl ratio were mainly regarded in the intake port design Proper piston bowl shape was searched to have better combustion phase. New designs of the main components of the gas engine combustion system were suggested through the simulation and their effects were confirmed by the experiments. Finally, EGR test was conducted to evaluate the efficiency improvements by reducing NOx and suppressing the knocking

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Recent progress of fuel injection sys tem like a common rail system makes higher fuel injection pressure possible. With such a state-of-the-art higher injection pressure technology, diesel engine has been improved in all aspects of performance such as higher power density, lower fuel consumption, cleaner exhaust emissions, etc. Injection pressure of atest FiE systems for or passenge car reach around 3000 bar, but the most of such high injection pressure FlE systems are still under development. Their spray characteristics are investigated by using constant volume vessel, although condition are different from todays engines pressure and tem-perature. Soot and NOx emission from the engine uipped with such a higher injection pres till under investigation. Also, the optimal nozzle di mensions(i.e. number of holes and hole diameter)in accordance with higher injection pressure is still der investigation. In order to estimate emission perfor-nances, CFD coupled with many kinds of sub-models about spray combustion is applied as one of the avail-able method. However. a lot of constants in the simulation code have to be calibrated by use of spray measurement data. On the other hand, in this study, soot and NOx emission data from higher injection pressure is estimated by using engine equipped with practical fuel injection system. And optimized number of holes d hole-diameter for higher injection pressure is estimated. Increase in injection pressure causes the in rease in spray penetration and the promotion of at omization. As for the atomization, higher the injection ressure,less the improvement in atomization. Thus, in this study, spray penetration is focused on as a main parameter. According to the many empirical models of spray penetration, penetration is mainly determined by the difference between pressure of fuel injection and that of ambient gas. Emissions from higher injection pressure under the same excess air ratio is as sumed to be obtained by decreasing in-cylinder gas pressure instead of increasing injection pressure obtaining certain pressure difference that can keep same spray penetration. As for the calculation of spray penetration, this study applied Dents formula (1971)However. under the constant excess air ratio condition, decreasing in-cylinder gas pressure automatically yields to shorter injection duration. In this study, con injection pressure(as is shown in figure)is proposed to estimate how high injection pressure is required without decreasing in-cylinder gas pressure Converted injection pressure is calculated by Dent's ormula whose input is spray penetration experimen tally linked with engine out emission. In order to verify the concept of converted injection pressure, two different engines are applied in this study. At first, a natural aspirated engine with maximum 1600 bar common rail injection system is applied for building soot and NOx estimation models. In this engine test, wide range of emission data is obtained under the various conditions of excess air ratio and pressure difference between injection and in-cylinder gas. The result shows good relationship between converted injection pressure and measured soot. Using this re lationship, soot estimation model is built and proposed. In terms of NOx, it has a good relationship with injection duration. Then, in this study NO estimation model is also built base on injection duration. Next, a turbo charged engine with maximum 2000 bar injection common rail system is applied for evaluating this soot and NOx estimation model. It is found that relative changes of measured emissions follow estimated results. But there is a gap in their absolute value because of different combustion chamber shape and direction of nozzle hole axishus, it is found that proposed soot and NOx estimation model is only effective for their relative change against increase in injection pressure. At last, a trend of the optimal nozzle dimensions accomp

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。When volume fraction of mine gas reaches 5%~15%, it will explode in case of fire. Forthe mine gas with concentration under 25%, the traditional approach is to extract the wet mine gas and discharge it to the air, which is a waste of resources, and endangers environmental protection. China has rich gas geological storage. According to estimation of concerning department, the annual emission of mine gas is about 13.5 billion cubic meters during the process of coal mining, more than 90% of which has a methane concentration under 25%. In order to effectively utilize the low concentration gas, Shengli Power Machinery Co. Ltd. developed 12V190 gas engine, which can use mine gas with methane concentrations in the range of 6%~30%. This paper introduces low concentration gas safety conveying technology, engine control system, as well as research on en-gine performance improvements. Gas delivery system uses techniques including water-block fire arrestor technology with automatically controlled water level, corrugated-metal-strip gas pipeline fire extinguishing technology and water mist fire extinguishing tech-nology. Engine control technologies include double-butterfly-gate mixer, low-pressure and large-flow pilot valve pressure control and TEM electronic management system. Through the use of pre-chamber spark plug and high efficiency turbocharger, the engine power was increased from 550kW to 900kW, further power improvement is expected through the use of Miller cycle technology. Until now, low concentra-tion gas generator has a nationwide application, and achieved good economic benefit and environmental benefit.

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。Recently, the four stroke engines are developed mainly with the environmental preservation as well as taking economy, durability and maintainability, etc. Nigata has developed high power density new four-stroke medium speed diesel engine The 17AHX'The 17AHX' has 165 mm bore and 265 mm stroke, engine speed 900rpm,1000rpm and 1200rpm. The 17AHX covered with 500kW to 1125kW output ranges of marine auxiliary engines, marine propulsion and electric propulsion engines that run on MDO and heavy fuel oil. Niigata achieved shorten development period around one year by using front loading such as performance simulation, CFD, FEA were carried out early development stage. Nigata improved durability and reliability by the advanced analysis technology such as performance simulation, FEA, and CFD.In order to improve environmental concerned, Nigata considered optimizing compression ratio, valve timing, piston bowl shape, turbocharger matching and fuel injection system by using performance simulation. Niigata carried out simulation analysis for the optimumfuel injection system at the beginning of development stage. The fuel injection system performances such as the stable injection, improved performance duringidle and full loads were confirmed by the component tests. The combustion chamber is most critical compo- nents for life time. Nigata has designed carefully the combustion chamber to achieve longer life time. Especially, FEA and CFD were applied to produce a highly rigid construction and effective cooling on the combustion chamber. The moving parts were optimized and reduced weight through FEA. It was tested the engine with two exhaust systems such as constant pressure and pulse. The valve timing is inference of engine per-formance. Nigata tested the engine with cam timing variants and turbocharger matching optimization. Ni-igata investigates main components of prototype engine stress distribution and temperature profiles. Theprototype engine verify the durability of the new engine, endurance tests have been performed. This paper describes the design features of the main components of ' the 17AHX', simulation results and engine test results.