• 한국자동차공학회논문집
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• 제18권2호
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• pp.97-103
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• 2010

The four combustion stages in a diesel engine have close correlation among them. Especially, the ignition delay period has significant effect on the following combustion stage. And the period is also one of inevitable combustion processes in the diesel engine. For example, the diesel knocking is a well-known phenomenon due to the long ignition delay period. The interval of the ignition delay period is affected by the mixture formation process in the cylinder. However, in the case of the D.I. diesel engine, the available duration to make the mixture formation of air-fuel is very short. In addition, the means of the mixture formation mainly depends on the injection characteristics and properties of the fuel. It is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this study, using the visible engine, we measured the ignition delay period by photo sensor which detect occurrence of flame and presented the factors of the injection characteristics such as kinds of injection system, the injection pressure and the injection timing. The relation between the ignition delay period and cylinder pressure diagram which was concurrently obtained was also estimated.

• 대한기계학회논문집B
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• 제20권9호
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• pp.3007-3014
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• 1996

The instantaneous flame temperature and soot formation and oxidation in a D.I. diesel engine are measured using a two-color method. The proposed method based on the continuous spectral radiation from the soot particles in the flame is applicable to industrial diesel engines without major modifications of their main characteristics. Measurements are performed at one location inside the combustion chamber of a D.I. diesel engine. Effects of different engine speeds and loads on flame temperature and KL factor which is an index of soot concentration were examined. Little temperature change were observed with increasing rpm, while increased with loads. The higher the flame temperature is, the lower the KL factor is.

• 한국분무공학회지
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• 제6권2호
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• pp.22-28
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• 2001

Recently, many researches have been performed to improve the combustion and emission in a D.I.Diesel engine. Especially reduction of the soot formation in the combustion chamber is the essential to acquire the improvement of the emission performance. This emission of the diesel combustion is effected by the characteristics of air-fuel mixing. Therefore, the optical measurement technique such as LII and LIS were established in order to visualize the distribution of the soot and analyze the particle including spray in the combustion chamber. In this study, we developed the algorithm for calculating relative diameter and density of particle and applied this method to measure stimultaneously the distribution of soot and spray in a D.I. diesel engine. From this experiment we found that the soot is existed in the rich region of spray and generated caused by incapable air fuel mixture.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.55-63
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• 2003

In a diesel engine, air-fuel mixture formation and ignition delay period have great influence on the performance of engine. Their main factors are combustion chamber shape, fuel injection system. air volume, air flow and so on. So, the combustion process in the cylinder is complex because of many factors which have direct and indirect effects on it. In this study, we take into consideration of scavenging pressure and scavenging temperature that are hewn as the main factor to the combustion process of two-stroke D.1. diesel engine. It is taken a picture of the combustion flame process for combustion chamber of re-entrant type and cylindrical type. So, it is applied to the basis data of combustion chamber design from an image analysis.

• 동력기계공학회지
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• 제17권6호
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• pp.25-32
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• 2013

Biodiesel is technically competitive with it and offers technical advantages over conventional petroleum diesel fuel. Biodiesel is an environment friendly alternative liquid fuel that can be used in any diesel engine without modification. In this study, (dP/dCA)max and heat release, emission characteristics with different fuel injection timings are compared between diesel fuel and biodiesel in the D.I. diesel engine with T/C. The engine was operated at five different fuel injection timings from BTDC 6deg to 14deg at 2deg intervals and with four different loads at engine speed of 1800rpm. The experiments in a test engine showed that ranges between low and high of (dP/dCA)max got narrower, as the engine load increased, BD blend rate increased, and fuel injection timing was delayed. Cumulative heat release increased with the advanced fuel injection timing. NOX emissions decreased with the delays of fuel injection timing.

• 오토저널
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• 제10권5호
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• pp.61-68
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• 1988

This paper reports the basic performance of a naturally aspirated DI diesel engine which is used widely in industry and agriculture when vegetable oils are used as fuel substitutes. In this paper, the properties of vegetable oils as diesel fuel were investigated and the load-performance of diesel engine when vegetable oils were used, as tested compared against diesel fuel. The general objective of this investigation is to realize an efficient, clean, and low carbon deposit combustion of the vegetable oils in diesel engines, showing their feasibility as diesel fuel substitutes. The results of this experiment were as follows; (1) Compared with diesel fuel, the droplet size of vegetable oil is very large. (2) Compared with diesel fuel, rapeseed oil, palm oil, and their blend fuels offered lower smoke, lower NOx, ower engine noise, and high thermal efficiency in a D.I. diesel engine However, there were carbon deposit and piston ring sticking problems with long-term operation. (3) For ethanol-rapeseed oil blends, a 10-20% of ethanol content is recommended to enable lower BSHC and less smoke without a remarkable increase in engine noise compared with pure rapeseed oil. (4) A 10% oxygen content in the vegetable oils is contributed to reduced smoke emission.

• 한국분무공학회지
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• 제3권3호
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• pp.23-32
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• 1998

The effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the aspect ratio (Bowl Diameter / Bowl Depth) of bowl of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the 4 kinds of the combustion chamber were meadured. Also, the combustion characteristics compared of the experimented and the calculated values which is used by the Hiroyasu's combustion model. The results are as follows; The effect of $d_c/H$ on ignition delay period are small. The smoke is corerelated to the heat release of the premixed and the diffusion combustion, i.g, the smoke decreased by decreasing the premixed combustion or increasing the diffusion combustion on cumulative heat release. The premixed combustion process has more effect than the diffusion combustion on smoke. The formal tendency of $d_c/H$ on engine performance has not appear.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.15-22
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• 2002

Lately, our world is faced with very serious problems related to the increased air pollution of the exhaust emissions from automobiles. In particular, the exhaust emissions of diesel engines are recognized as a main cause which strongly influence environment. Lots of researchers have attempted to develop various alternative fuels to reduce these harmful emissions in diesel engine. The purpose of this investigation is to evaluate the possibility of esterfied rice bran oil for diesel fuel substitution in a naturally aspirated D. 1. diesel engine, and also find means to reduce smoke emissions in esterfied rice bran oil combustion. The smoke emission of esterfied rice bran oil is reduced remarkably in comparison with commercial gas oil, that is, it was reduced approximately 58.2% at 2500rpm. But, power, torque and brake specific energy consumption didn't have no large differences. It was concluded that esterfied rice bran oil can utilize effectively as an alternative and renew- able fuel fur diesel engine.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.150-156
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• 2006

Recently, the tightening of available crude oil supplies has resulted in the development of intense consciousness for saving fuels. At the same time, some research programs have been launched to secure substitute energy sources for petroleum-derived fuels, and to reduce unhealthy products, such as CO, HC, NOx and smoke. To keep up with these trends in society, the regulation affecting diesel smoke may be greatly strengthened in a short time. In not too distant future, LPG and LNG are the most hopeful substitute fuels for automobile and truck uses. This paper discusses how to use such gaseous fuels in a diesel engine, and how to find out introducing these fuels affect the engine performance.

• 오토저널
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• 제15권1호
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• pp.37-44
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• 1993

Fuel injection system is an important tool in the exhaust emission and performance of a diesel engine. Effects of the fuel injection system in diesel combustion was investigated experimentally by measuring the performance and analyzing the combustion phenomena in a D.I. diesel engine. The selected injection parameters were nozzle opening pressure, nozzle projection length, and nozzle spray angle. From the measured results, it is shown that the fuel injection pipe diameter is an effective means to improve engine performance in a middle and high speed range and the 2 stage spring nozzle holder has the advantage of increasing the engine performance due to the initial injection pressure in a low speed range. It has been also shown that increasing nozzle opening pressure resulted in decrease in smoke, but increase in NO$_{x}$ from the engine.e.