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。 Based on the measurement of temperature filed of piston and cylinder sleeve, the dynamic model of 2D25 diesel piston assembly was established. The effect of piston structural multi-parameters and single param eters on lub-oil consumption was analyzed respectively by orthogonal experimental design method and conventional method, and the single parameters which including the radial clearance between piston skirt, piston head and cylinder inner wall, and the piston pin offset. The results indicate that the radial clearance between piston skirt and cylinder inner wall was the greatest impact on the lub-oil consumption, then the piston head radial clearance and the piston pin offset. And the convex position of piston skirt profile, stiffness and ovality of piston skirt had little impact to oil consumption. The lub-oil consumption had little change with the radial clearance between piston skirt and inner wall from 0.06mm ∼ 0.09mm, but the lub-oil consumption increased rapidly when the radial clearance between piston skirt and inner wall was at the range of 0.09mm ∼ 0.15mm. The lub-oil consumption had a little increment with the piston head radial clearance. The lub-oil consumption was the lowest when the piston pin offset to main bearing surface was 0.5mm, and the lub-oil consumption was increasing with piston pin offset to main bearing surface was increasing, but the range was not obvious.

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。 A split exhaust turbocharger system is introduced in this article based on an initial study of the available exhaust energy of a four-stroke diesel engine. The split exhaust turbocharger system can save more available exhaust energy than an ordinary exhaust turbocharger system by over 20%. A larger four-stroke diesel engine with such system can save more energy by about 2% than with an ordinary exhaust booster system at rated condition while its boost pressure can be increased by 50% at low speed. The split exhaust turbocharger system can completely replace the role of a power turbine.

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。Renewable biomass energy, especially the high-grade liquid fuels such as esters and alcohols, has been adopted widely in internal combustion engines. As compared to pure diesel, when the engine is fuelled with ethanoldiesel, the combustion start timing is postponed, in-cylinder heat release process is relatively conc entrated, and so the cylinder peak pressure, maximum pressure rise rate and peak heat release rate increase, which leads to the higher conversion efficiency of heat into power. Ethanol-biodiesel could significantly improve the NOx and smoke emissions, except for the higher HC and CO emissions at low and moderate loads. With the increase of load, the HC and CO emissions from engine fueled with ethanol-diesel are roughly equal to that of diesel, and may be even lower than that of diesel at higher loads.The combustion processes of biodiesel and petrolic diesel are illustrated in the crank angle coordinate with the direct flame images combined with analysis of heat release. Due to the contribution of bigger bulk modulus and higher cetane number of biodiesel, the beginning of injection for biodiesel is 0.7°CA earlier than that for diesel, and the ignition time of biodiesel occurs earlier 1.5°CA than that of diesel, under the unimproved conditions of fuel supply system. During the rapid combustion period, both the brightness and its lasting time of biodiesel are less than that of diesel.The heat released by the chemical reactions without obvious flame at the end of combustion only accounts for 2 to 3 percent of the total cycle heat energy released by fuel. Although there are a few differences in properties between biodiesel and diesel, biodiesel still could achieve the perfect substitution for petrolic diesel.

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 sequential turbocharging technology is the most effective method to improve diesel engine performance at low condition (low speed and low load). The technology can extend engine operation range at low condition, improve engine economy performance and reduce engine exhaust emissions. A new type of sequential turbocharging system–a split intake and exhaust boosting system is proposed here. The new system consists of two turbochargers of a large one and a small one. The adjustment range of intake and exhaust flows of such system is twice that of a normal turbocharger system with two identical turbochargers. The adjustment of intake and exhaust flows of the new sequential turbocharging system is stepless, which can avoid some problems such as compressor surge, turbocharger overspeed and high oil consumption in engine transient process. The system enables a turbochargered engine to obtain high EGR rate at all operating points with the energy of a turbocharger system itself, thus meeting much stricter exhaust regulations.

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。This paper carried on the study of the influence of different EGR rate on combustion and emission performance when applying D30 impure DME-Diesel mixed fuel on 4100QBZL turboengine.The results show that: As the EGR rate increased, the cylinder pressure of premixed combustion, the maximum of combustion pressure and temperature were decreased, the crank angle of the peak delayed, ignition delay and combustion duration extended. NOx emissions decreased significantly, when the EGR rate exceeds a certain value, CO and HC emissions will increase rapidly.

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 comfort and environment protecting of modern ship are required strictly with the development of marine technology. In 2012, IMO finished the revision of IMO Res. A 468(XII) ’Code of Noise Level On Board Ships Resolution’ .In this revision, the noise level of diesel cabin is required to reduce 5 dB,compared with the initial 110 dB of cabin noise level.The noise level of marine diesel has the important influence on the comfort and acoustic concealment of navy ship, as the main noise source. The noise level evaluation and acoustic contribution analysis of marine diesel are key technical approaches of low noise diesel design. Diesel Structure-borne noise prediction method is first expounded. The acoustic contribution of the main parts of diesel such as oil pan, inlet and exhaust ports, cylinder heads, valve covers is analyzed,and the structure- borne noise level of diesel in different working conditions are calculated by Virtual Lab software aiming at representative large power marine diesel. Noise test of diesel are finished, and the noise distribution of diesel is acquired based on noise test data. Finally, noise control measures of diesel are proposed on the basis of the above analysis. The research result can be applied to the vibration and noise control of marine diesel.

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 formation of urea deposit in the SCR system leads the reduction of NOx conversion efficiency and catalyst lifetime. In order to investigate the formation of urea deposit at exhaust inner pipe, the weight of urea deposit and NH3 which is decomposition product of urea were measured and analyzed under different conditions. According to the experiment results, it was found that the mass of deposit is more and concentration of NH 3 is less when the temperature is lower, and it’s no significant growth of urea deposit when the duration time gets longer. The mas of deposit increases with the increase of gas flow velocity, but it will decrease when the velocity continually increase. The mass of deposit reduced with the increase of the concentration of urea water solution.CFD model of urea spray impingement which is coupled spray injection, droplet atomization, evaporation and gas flow was established for airless injection system. And the model was validated by experiments.Based on the established model, the mass rate of urea water solution at exhaust inner wall (Qwall) was investigated with the variation of flow velocity, temperature,pipe diameter and spray angle for two typical injection positions which are at the elbow and pipe wall of exhaust pipes. It is found that Qwall increased with the increase of gas flow velocity, but Qwall is almost constant with continue increasing of velocity. Qwall is lower for spray injection position at pipe wall than elbow. The experimental and numerical results and conclusions are significant for reduction of urea deposit, increase of NOx conversation efficiency and extension of catalyst lifetime.

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。Due to the strict rules and regulations of environmental organizations on pollutant emissions control, the engine manufacturers are encouraged to develop new combustion systems that are compatible with the environment. Consequently, natural gas is being considered as one of the most outstanding alternatives between the fuels. In order to have a good combustion, mixture of air and fuel that enters into the combustion chamber must have acceptable speed and turbulence. Also, in order to create maxi- mum power by the minimum amount of fuel, this mixture should be ignited at the right time and right place. Various researches have been conducted in order to compensate power loss caused by using natural gas rather than the conventional fuels. In this research activity, the open cycle engine simulation was performed to examine the influence of location of the spark plug on better combustion This can occur when having better,stronger and more disciplined spark plug ignition. So,the position of spark plug can affect on the maximum temperature, pressure and also efficiency. 3D computational fluid dynamic modeling is used to simulate the D87 gas engine

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。 Large gas engines are gaining more and more importance within the global energy mix. The long-term availability of natural gas is comparatively secure and gas engine power plants are reaching high efficiency levels while meeting stringent emission limits worldwide as well as customer needs for matching electricit generation with demand. This makes large gas engines a clean technology for supplying electricity and heat around the globe as part of a decentralized energy concept. Emission legislation always drives technology, and there is a clear trend towards decreasing the emission limits for large combustion plants. For example, the European Union has issued the Industrial Emission Directive (IED) with a NO x limit for new gas engine plants of 75 mg/Nm 3 @ 15% O2 and 100 mg/Nm3 for CO. These limits have been inforce since 2011 and are mandatory for power plants with an energy input above 50 MW that consist of engines above 15 MW. Due to the IED and other emission legislation, it is necessary to decrease plant emissions. As a result, customers are requesting engines with lower NOx , CO and THC emissions. Up to date engines with 500 mg/Nm 3 NOx @ 5% O 2 dominate the market share, but it is likely that there will be a shift to low NOx engines. From the perspective of both technology and life cycle cost, there is always the question of what technology fits best. Consequently, this paper discusses the trade-off between emissions and engine performance and also highlights various technological approaches which are used to achieve the highestengine efficiency with the lowest possible engine-out emissions. The focus is on the design of the prechamber and the main combustion chamber, operational strategy and the turbocharging system including gas exchange. Finally, the engine-internal measures are compared with competing exhaust aftertreatment solutions.

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。High oil consumption and blow by rates are often related to piston ring sticking and carbon deposit. Engine tests were carried out and test results were analysed to investigate and verify factors and correlations of the problems. Designs of cylinder block and head water jacket were optimized and combustion system was improved in the solution of piston sticking and carbon deposit. Results of engines with improved design are quite satisfactory.