• Journal of ILASS-Korea
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• v.2 no.3
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• pp.44-50
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• 1997

Bio-diesel oil is a great possibility to solve the pollution problem caused by the exhaust gas from diesel engine vehicles. Recently the use of bio-oils in disel engines has received considerable attention to the forseeable depletion of world oil supplies. So, Bio-diesel oil has been attracted with attentions as an alternative and clean energy source. The objective of this paper is to experimentally investigate the characteristic of performance using light oil, rice-bran oil, heated rice-bran oil, rice-bran oil treated with ultrasonic energy. We included rice-bran oil and applied ultrasonic energy to highly viscous bio-oils. These methods seems to have never been tried yet. The final data may be able to be applicated for the design of the diesel engine using an alternative fuel.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.551-558
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• 2004

Recently, fuel prices have been continually raised in diesel engine. Such a change in the fuel price influences enormously the development trend of marine diesel engines for slow speed, In other words, the focus was shifted from large diameter and high speed to low fuel consumption. Accordingly, more efforts are being made for engine manufacturing and development to develop highly efficient engines. In this study. a single cylinder 4 stroke cycle DI slow speed diesel engine was designed and manufactured, a 4 stroke cycle was configured and basic performances were evaluated. The results are as follows. The optimal fuel injection timing had the lowest value when specific fuel consumption was in BTDC 8~$10^{\circ}$, a little more delayed compared to high speed diesel engines. Cycle variation of engines showed about 5% difference at full loads. This is a significantly small value compared to the cycle variation in which stable operation is possible, showing the high stability of engine operation is good. The torque and brake thermal efficiency of engine increased with an increase of engine 250-450 rpm. but fuel consumption ratio increased from the 450 rpm zone and thermal efficiency abruptly decreased. Mechanical efficiency was maximally 70% at a 400 rpm that was lower than normal engines according to the increase of mechanical frictional loss for cross head part. The purpose of this study was to get more practical engines by comparing the above results with those of slow speed 2 stroke cycle diesel engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.65-77
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• 1996

A small-sized industrial diesel engine was converted to a spark ignited engine and then adapted for fuelling with natural gas. After conversion work, general combustion characteristics of the gas engine(such as ignition delay, main and total combustion durations, and heat release characteristics) were studied as a functio of major engine operating variables such as air to fuel ratio, spark timing, and spark plug type. Some other studies on cyclic variation characteristics in IMEP, Pmax and (dp/dφ)max, and also optimum combustion phasing angle were performed.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.49-54
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• 2003

The purpose of this work is to investigate the effect of premixed fuel on the reduction of exhaust emissions in premixed charge compression ignition engine. The premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber. The pre-mixture is ignited by a small amount of diesel fuel directly injected into the cylinder. In the case of gasoline as a premixed fuel of the engine, $NO_x$ and smoke concentration of exhaust emissions were reduced compared with the conventional diesel engine. But in the event of diesel fuel for premixed fuel, the rate of smoke reduction was small compared with the case of gasoline as a premixed fuel. HC and CO emissions were increased at high premixed ratio in the case of two premixed fuels. The combustion characteristics of the engine such as the combustion pressure, the rate of heat release, and other characteristics are compared.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.98-106
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• 2014

Emission standards for passenger diesel engines are becoming more and more stringent. Especially, Europe started the regulation of nano-particles from 2011 with EURO 5b. The objective of this study is to investigate the effect of fuel injection strategy on combustion and nano-particle emission in a small diesel engine. In this study, we conducted combustion analysis and measured both the weight of PM and number of nano-particels. At first, the optimum injection timing was determined with fixed engine operating conditions, such as engine speed, load, and fuel injection quantity. After that, the injection timing was controlled, and the effect of pilot injection was investigated. The number of nano-particles increased as engine load decreases, and it increased up to 10 times depending on the change of injection timing. The weight of PM emissions was increased at low load, and the PM emissions increased with increasing the number of pilot injections.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.3
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• pp.26-36
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• 1989

Recently digital governor system is commonly adapted for the speed control of the marine diesel engine because of too much fluctuation of rpm resulted by the low speed, long stroke, high efficiency and a small number of cylinder of it, and versatile studies on the development of digital governor system are progressed. On this subject the new control method in which the fuel is controlled by feedforwarding the change of load as well as the feedback of angular velocity in case of disregarding the engine dead time and influence of scavenging air was proposed by the authors, and found the method has shown quite a good control performance in comparision to the conventional control method by the simulation using a digital computer for various load change. In this paper the speed control system of a diesel engine is simulated in case of regarding the engine dead time by the proposed method, and also confirm a good control performance of it under even more realistically simulated environment.

• Journal of Biosystems Engineering
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• v.17 no.1
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• pp.5-17
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• 1992

To develop an analytic method of combustion characteristics in a small sized and single cylinder type diesel engine for a power tiller, 1) the theoritical analysis of combustion gas in engine cylinder was performed based on thermoscience and 2) the computer program which could be used to calculate those values of the apparent burning rate, the heat loss, the gas temperature and the fuel-air equivalence ratio with the experimental cylinder pressure data, was developed. This method would provide the practical and quantative data for the diesel combustion process. Through the use of this method, following details would be obtained: 1) the application in the modeling of combustion process without detail knowledeg of combustion process, 2) the basis for the complete modeling of diesel engine, and 3) the basic information for the design of combustion chamber by the prediction of engine performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.9-15
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• 2004

The characteristics of combustion and emissions were investigated in a single cylinder DI diesel engine equipped with a common rail injection system. This study presents an experimental study of the effect of engine speed, injection timing, injection pressure and pilot injection timing on the combustion and exhaust emissions. The engine speeds were 1000 and 2000rpm and the corresponding injection pressures were 50 and 100MPa. Experimental results show that NOx emissions decrease with retarded injection timing, while HC and CO emissions increases. Higher injection pressure increases NOx with lower soot emissions. For the case with the pilot injection prior to main injection, the ignition delay is shortened and the premixed combustion ratio decreases. Also NOx and soot emissions are decreased with increase of pilot injection advance.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.159-169
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• 1985

The calculation of torsional vibration for marine diesel engine propulsion shafting is normally carried out by equalizing exciting energy to damping energy, or using the dynamic magnifier. But, with these methods, the vibration amplitudes are calculated only for resonance points and vibration amplitudes of other running speeds of engine are determined by the estimation. Recently, many energy-saving ships have been built and on these ships, two-stroke, supercharged, super-long stroke diesel engines which have a small number of cylinders are usually installed. In these cases, the first order critical-torsional vibrations of these engine shaftings appear ordinarily near the MCR speed and the stress amplitudes of their vibration skirts exceed the limit stress defined by the rules of classification society. To predict the above condition in the design stage, the synthesized vibration amplitudes of all orders which are summed up according to their phase angles must be calculated from the drawings of propulsion shaft systems. In this study, a theoretical method to fulfill the above calculation is derived and a computer program is developed according to the derived method. And a shafting system of two-stroke, super-long stroke diesel engine which was installed in a bulk carrier is analyzed with this method. The measured values of this engine shafting are compared with those of calculated results and they show a fairly good agreement.

• Journal of ILASS-Korea
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• v.18 no.1
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• pp.16-20
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• 2013

The investigation was conducted to analyze the exhaust emission characteristics in diesel engine according to intake air mass flow. In this study, the test diesel engine with a 5,899 cubic centimeter displacement and power of the 260 ps was used to analyze the emission characteristics according to the intake air mass flow. In addition, the test modes were applied by the ND-13 and ETC mode. In order to analyze the emission characteristics, the engine dynamometer with 440 kW and emission gas analyzer (AMA-4000) were utilized. From the experimental results, it is revealed that the NOx and HC emissions in the intake air mass flow of large amount have high levels compared to those in the intake air mass flow of small amount in the ND-13 mode. However, the PM emission was shown the opposite trend in the NOx and HC emission due to the trade-off relation between the NOx and PM.