• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.869-874
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• 2011

In a CNG/diesel dual-fuel engine, CNG is used as the main fuel and a small amount of diesel is injected into the cylinder to provide ignition priming. In this study, a remodeling of the existing diesel engine into a CNG/diesel dual-fuel engine is proposed. In this engine, diesel is injected at a high pressure by common rail direct injection (CRDI) and CNG is injected at the intake port for premixing. The CNG/diesel dual-fuel engine had an equally satisfactory coordinate torque and power as the conventional diesel engine. Moreover, the CNG alternation rate is over 89% throughout the operating range of the CNG/diesel dual-fuel engine. PM emission by the dual-fuel engine is 94% lower than that by the diesel engine; however, NOx emission by the dual-fuel engine is higher than that by the diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.32-38
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• 2004

To evaluate the durability of direct injection diesel engine using biodiesel fuel, a small D. I. diesel engine was operated on a blend(BDF 20) of 20％ biodiesel fuel and 80％ diesel fuel for 200 hours. Engine dynamometer test was performed at a load of 90％ and a speed of 1900 rpm to monitor the engine performance and exhaust emissions. Engine performance parameters and exhaust emissions were sampled at 1 hour interval for analysis. The combustion maximum pressure and the crank angle at this maximum pressure as a combustion variation factor were considered to study the combustion characteristics of BDF 20 in diesel engine during durability test. As the results, the standard deviations and errors of combustion variation factors on BDF 20 were very little and combustion characteristics were very stable during the durability test. BDF 20 resulted in lower emissions of carbon monoxide, carbon dioxide, and smoke emissions with special increase of nitrogen oxides compared to diesel fuel. There was no also unusual change in engine oil composition from using BDF 20. Most of engine parts were clean and showed little wear, but soots were detected around the hole of fuel injector when BDF 20 was used in direct injection diesel engine for 200 hours.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.5-10
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• 2005

The effect of ultrasonic energy for diesel fuel and blend oil has been revealed in this paper. The experimental setup consisted of a high speed diesel engine with 4 cylinder, dynamometer and ultrasonic fuel feeding system. Ultrasonic energy was added to diesel fuel and blend oil, which is a blend of diesel fuel and rape-seed oil. As engine speed was changed, engine torque and power, brake specific fuel consumption and thermal efficiency were measured in detail. As the results, by adding ultrasonic energy to diesel fuel and blend oil, the engine performance was improved in range of the experiment. The effect of improvement on brake specific fuel consumption and thermal efficiency for blend oil is higher than that for diesel fuel. When ultrasonic energy was added to diesel fuel or blend oil, a rise in engine torque for diesel fuel was higher than that for blend oil, but the effect of ultrasonic energy was small. From these results, it may be desirable to add ultrasonic energy to blend oil for the use of blend oil to diesel engine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.43-49
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• 2014

This study was carried out to improve the design of an intercooler for a small marine diesel engine. Diesel engines for small marine ships have mainly been developed by changing the structure of the vehicle engine. Sea water was most commonly used in the intercooler of small marine diesel engines to cool the hot air compressed by the turbocharger. In this study, the intercooler is modeled and simulated using STAR-CCM+ in order to find optimal data for the design of an intercooler. In the results, the temperature differences between the data from a numerical analysis and experimental data were $0.38^{\circ}C$ in the hot air outlet and $3.63^{\circ}C$ in the cooling water outlet. Therefore, it was confirmed that both analysis and experimental results need to be considered when designing an intercooler. A closer degree of similarity in the two datasets can improve the confidence in the design of these intercoolers.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.3
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• pp.31-44
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• 1987

Nowadays, the problems of energy and environmental pollution become serious day by day and the diesel engine, which has been proved to be superior to gasoline engine with respect to fuel consumption and ecological problems of exhaust gas, has been adopted widely for various purposes from the marine diesel engine and the dynamo engine to all kinds of engine on land. Therefore, extensive parametric studies on combustion of diesel engine should be done for its desing and improvement. To predict the behavior of diesel engien according to variable operating conditions by means of cycle simulation, the reasonable pattern of heat release rate has to be asumed. But it is necessary to know the actual variation of heat release rate in order to assume the reasonable pattern of heat release rate according to the actual operating conditions. In this paper, on a high speed small bore diesel engine with pre-combustion chamber, experimental investigations were carried out to determine the relationship between the heat release pattern and parameters such as engine load and speed. And also, the theoretical investigations about the performance variations of the above diesel engine according to the predicted pattern of heat release rate variation were performed. From the above observations, it may be said that the Fanboro indicator, which was used to get the cylinder pressure, can be used to estimate a reasonable pattern of heat release rate and it is confirmed that the pattern of heat release rate for the pre-combustion type engine is different from that of the direct injection type engine.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.160-170
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• 1997

The objective of this study is to investigate the atomization characteristics and the performance characteristics of a C. I. engine by using the changes of the injection nozzle type and the ultrasonic-energy-added system. In order to evaluate the effect of ultrasonic energy and of change of injection nozzle type in the performance characte- ristics of a diesel engine, measurements of droplet size of diesel fuel were carried out by using Malvern system. In all types of injection nozzles, SMD of the ultrasonic- energy -added diesel fuel was smaller than that of the conventional diesel fuel and the more injection pressure increased, the more SMD decreased. There was a small increase in SMD with the distance from injection nozzle under all conditions of the injection nozzle types. The minimum SMD was found in the injection nozzle of B type. In the diesel engine test, there were three results about the engine performance. Compared with the injection nozzle of A type, B type had excellent effects in the engine performance. The most excellent effects about the engine performance were obtained in the case of ultrasonic-energy-added diesel fuel. In addition, the torque diagram in the case of ultrasonic-energy-added diesel fuel was more stable and periodical than others.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.209-220
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• 2001

This study was carried out to investigate the usability of the used frying oil, which was extracted from soybean, as one of the alternative fuel of a small diesel engine. For the experiment, NO. 2 diesel oil [D], used frying oil [UF], and their volumetric blends were applied and analysis of the properties and compositions of the experimental fuels were conducted. A four cycle diesel engine with single cylinder, water cooling system, maximum output 8.1 ㎾/2,200 rpm was selected and a direct injection chamber and a precombustion chamber were attached alternately. The results obtained were as follows: 1. Engine power (BHP) were increased from 4.13~4.27㎾ to 9.08~9.15㎾ for diesel oil, from 4.05~4.19㎾ to 8.44~8.92㎾ for UF, and from 4.01~4.48㎾ to 8.69~9.16㎾ for blend fuel, as the engine speed increased from 1,000 rpm to 2,200 rpm. The BHP in case of the direct combustion chamber were fluctuated higher than those of the pre-combustion chamber. 2. With the engine speed increased, torque of the engine were increased from 39.50~40.80 N.m to 42.89 N.m, then decreased to 39.44~39.77 N.m for diesel oil, and increased from 38.73~40.04 N.m to 40.12~40.82 N.m then decreased as 36.53~38.76 N.m for UF. Torque of the blend fuels were increased from 38.75~41.76 N.m to 40.47~42.89 N.m then decreased to 37.73~39.78 N.m. There is no significant difference of torque between the type of combustion chambers. 3. The specific fuel consumption of the UF was increased about 20 percent depending on the engine speed variations. And in case of direct injection chamber, about 12 percent lower fuel consumption was observed than that of precombustion chamber. 4. NOx emission of the UF was higher than that of diesel oil at above 1,800rpm of the engine speed. In case of the direct injection chamber, NOx emission was revealed higher about 59 percent than that of the precombustion chamber, depending on the range of the engine speeds. 5. Smoke emission was decreased in case of UF compared with diesel oil on direct injection chamber. When using precombustion chamber smoke emission was a little higher than that of the direct injection chamber were showed at the engine speed range. 6. At all the engine speed range, exhaust gas temperatures were decreased 2~3$^{\circ}C$ for UF used engine compared with those of the diesel oil. The exhaust gas temperature of the direct injection chamber was higher than that of the precombustion chamber by 72$^{\circ}C$. 7. Unburnt materials remained in the cylinder in case of the pre-combustion chamber was smaller and softer than that of the direct combustion chamber. 8. The feasibility of the blend fuel B-1 and B-2 were verified as a direct combustion chamber was attached to the diesel engine, with respect to the power performance of the engine.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.12-17
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• 2007

Recently, many small and medium size diesel vehicles have been equipped with turbocharger and EGR system to get high performance and reduce $NO_x$ emissions but its application to heavy-duty diesel engine is not common yet. In this work, the simulation model for EURO-3 engine was developed using WAVE and then its performance and emission level were verified by comparing with experimental results. The possibility of current EURO-3 engine equipped with LPL EGR system which would be satisfied the EURO-5 regulation are examined. ESC 13 mode was chosen as the primary engine test mode, and the injection timing and fuel quantity were changed to compensate the lost engine performance caused by EGR. The system developed in this study shows that the current EURO-3 engine could satisfy EURO-5 $NO_x$ regulation by applying LPL EGR.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.20-26
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• 1998

Heat release data were obtained by analysis of cylinder diagrams from a test engine, naturally-aspirated small-size four-stroke DI diesel engine. These data were used to decide empirical coefficients of Whitehouse-Way's model, single zone combustion model. Finally, the comparison of calculated with experimental results was performed, and the accuracy of calculated versus experimental data of the model in predicting engine heat release and cylinder pressure was demonstrated.