• 대한기계학회논문집B
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• 제26권6호
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• pp.833-841
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• 2002

The present study examined the possibility of NOx reduction in the high temperature industrial furnaces, duct burner of gas turbine cogeneration and two-stage gas turbine combustor. The experimental study was carried out for the non-premixed flame of second stage combustor with the variations of oxygen concentration in the hot exhaust gas of first stage combustor. It also examined the flammability range, temperature and NOx, $CO_2$, $O_2$formation in the combustor with respect to oxygen concentration in which the fuel(natural gas) is supplying into the hot exhaust gas. The results show that the inner temperature of flame reaches 1,20$0^{\circ}C$ at EGR $O_2$23% and that 15ppm of NOx at EGR $O_2$15.5% increases up to 60ppm at EGR $O_2$23%. It is believed that Fenimore＇s prompt NOx mechanism is more influential on the NOx formation than Zeldovich＇s thermal NOx mechanism does.

• 산업기술연구
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• 제26권A호
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• pp.39-46
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• 2006

As an automobile fuel, LPG has many environmental advantages compared to gasoline or diesel. However, current LPG engine which is provided with LPG fuel as gas form has lower power and worse fuel efficiency than gasoline engine. These problems of low power and bad fuel efficiency come from lower volumetric efficiency. Also there is a new rising problem of high failure ratio in an engine emission test. Although there are many factors which affect engine performance of exhaust gas emission, one believes that the fact that ECM of gasoline engine is used for LPG engine when retrofitting gasoline engine to LPG engine is one of the main problems, which lower engine power and emit more noxious gas due to wrong ignition timing. To solve these problems, one studied the effects of ignition timing on the exhaust gas to find out the optimum condition of ignition timing. The experimental results show that noxious exhaust gas is reduced and engine power is increased if the optimum control of ignition timing is applied in accordance to the revolution speed of engine.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.85-91
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• 2003

In this study, the potential possibility of oxygenated fuel such as Methyl tertiary butyl ether (MTBE) was investigated for the sake of exhausted smoke reduction from diesel engine. MTBE has been used as a fuel additive blended into unleaded gasoline to improve octane number, but the study of application for diesel engine was incomplete. Because MTBE includes oxygen content approximately 18%, it is a kind of oxygenated fuel that the smoke emission of MTBE is reduced remarkably compared with commercial diesel fuel. But, the NOx emission of MTBE blended fuel is increased compared with commercial diesel fuel. And, it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from $C_1$ to $C_6$ in exhaust gas using gas chromatography to seek the reason for remarkable reduction of smoke emission. Individual hydrocarbons($C_1$~$C_6$) as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with diesel fuel. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated, too. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.

• 대한기계학회논문집B
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• 제28권3호
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• pp.359-364
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• 2004

For the development of high efficiency and low emission combustion systems, high temperature air combustion technology has been tested by utilizing preheated air over 1100 K and exhaust gas recirculation. In this system, combustion air is diluted with large amount of recirculated exhaust gases, such that the oxygen concentration is relatively low in the reaction zone, leading to low flame temperature. Since, the temperature fluctuations and sound emissions from the flame are small and flame luminosity is low, the combustion mode is expected to be flameless or mild combustion. Experiment was performed to investigate the turbulent flame structure and NO$_x$ emission characteristics in the high temperature air combustion focused on coflowing jet diffusion flames which has a fundamental structure of many practical combustion systems. The effect of turbulence has also been evaluated by installing perforated plate in the oxidizer inlet nozzle. LPG was used as a fuel. Results showed that even though NO$_x$ emission is sensitive to the combustion air temperature, the present high temperature air combustion system produce low NO$_x$ emission because it is operated in low oxygen concentration condition by the high exhaust gas recirculation.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.76-85
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• 2000

Stirling cycle was actualized as so called ‘hot air engine’. It has been focused again lately as one of measures for exhaust gas emission problem, but as small power engine because of its method of heat addition. Recently marine power plants commenced to meet a stringent environmental restrictions by international convention, Marpol so that diesel engines as main and auxiliarly power plants are urged to be reformed to reduce NOx emission. Author devised a compression ignition engine as a large marine power plants combined with turbo charger based on stirling cycle, and analyzed the performance by means of basic thermodynamic calculation. Analyzed in this paper, were theoretical efficiency, mean effective pressure, required equivalence ratio, gas turbine power ratio, maximum pressure, states of turbo-charger inlet gas and exhaust gas, manifesting that the engine could be proposed as one of the future power plants of marine use.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.114-120
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• 2011

Fuel reforming technology for the fuel cell vehicles has been frequently applied to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this paper, syngas was feed to a 2.0 liter SI engine with MPI to improve exhaust emissions under cold start and early state of idle condition. Syngas fraction is varied to 0%, 10%, 25%, with various ignition timings. Exhaust emission characteristics and the exhaust system temperature were measured to investigate the effects of syngas addition on cold start. Result showed that HC emission could be dramatically reduced due to the fact that syngas has $H_2$ and no HC as components. The amount of $NO_x$ emission was decreased with the increase of syngas fraction. Because the dilution effect of $N_2$ and the retard of ignition timing reduces the peak combustion temperature inside the cylinder. Exhaust gas temperature was lower than that of gasoline feeding condition. Retarded ignition timing, however, resulted in increased exhaust gas temperature approximated to gasoline condition. It is supposed that the usage of syngas in an SI engine is an effective solution to meet the future strict emission regulations.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.67-72
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• 1997

The purpose of this study os to investigate how the natural gas in fuel blend influences the polutant emission of diesel engine. Four stroke cycle single cylinder engine is used for this experiment and four kind of fuel blends were made. Fuel blends show four different torque ratios between diesel oil and natural gas, which are 4 : 0. 3 : 1, 2 : 2 and 1 : 3. The constituents of exhaust gases of engine are analyzed for every fuel blend. The experimental results say that the mixing of natural gas into diesel fuel is an very effective way to reduce the amount of soot in the exhaust gas.

• 대한기계학회논문집B
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• 제31권3호
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• pp.234-241
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• 2007

The regulations for hydrocarbon emission from vehicles have become much more stringent in recent years. These more stringent regulations request vehicle manufacturers to develop the advanced exhaust system for reducing exhaust emissions. The exhaust emissions has many sources in vehicle. In order to investigate the characteristics of hydrocarbon(HC) in the exhaust manifold, concentrations of individual HC species were measured in exhaust process. Using sampling valve, the light hydrocarbon emissions were captured in the exhaust manifold(catalyst before and after) and analyzed from LPLi engine exhaust manifold(catalyst before and after) using different fuel properties. Then exhaust samples were measured by gas chromatography(GC) and exhaust gas analyzer. Catalyst conversion efficiency for fuel properties of Butane 100% was better than Propane 100%. Start delay of LPLi engine was observed as increment of propane contents in LPG fuels.

• 한국대기환경학회지
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• 제30권6호
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• pp.545-554
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• 2014

In general, odorant was added to fuel gases, such as LPG, LNG and city gas, to prevent gas poisoning, ignition, explosion, or other accident caused by fuel gases, and to enable immediate and easy detection of fuel-gas leakage by emitting an offensive smell. This study describes a study on the exhaust emissions characteristics and fuel economy of liquefied petroleum gas (LPG) vehicle using LPG fuel with new sulfur free odorant. New sulfur free odorant was added to LPG to reduce sulfur content of the LPG. Its performance and exhaust emission were compared to those of LPG with sulfur containing odorant (EM, ethyl mercaptan). Engine performance using LPG with sulfur free odorant was similar to that with sulfur-containing odorant. Exhaust emissions from the LPG vehicle with LPG including sulfur free odorant were also similar to those with LPG including sulfur containing odorant in the FTP 75 and NEDC mode. There experimental results suggest that the sulfur free odorant may substitute for the sulfur containing odorant in LPG fuel.

• 한국산학기술학회논문지
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• 제19권12호
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• pp.54-61
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• 2018

자동차의 엔진에서 불완전 연소는 유해 배기가스 생성의 주요 원인이다. 따라서 본 연구에서는 자동차 엔진에서 불완전 연소를 방지하고 배출되는 배기가스의 양을 줄이기 위하여 흡기 매니폴드에 가스켓 블레이드를 적용하여 유입되는 공기의 유속 증가에 따른 배기가스의 변화를 해석과 실험을 통하여 고찰하였다. 먼저 3D 유동 해석 프로그램을 사용하여 가스켓 블레이드의 개수와 각도에 따른 유동 해석을 수행하였으며, 해석 결과 가스켓 블레이드를 적용한 흡기 매니폴드 출구에서 공기의 평균 유속은 블레이드 개수가 6개와 $30^{\circ}$각도에서 가장 좋게 나타났다. 해석 결과를 기반으로 무부하 엔진 시뮬레이션 시스템에서 가스켓 블레이드가 배기가스에 미치는 영향을 확인하기 위하여 실험을 진행하였으며 엔진 회전수가 2000 rpm에서 4000 rpm으로 증가함에 따라 배기가스인 HC, CO, NOx는 평균적으로 각각 23.4%, 16.5%, 3.8% 감소하였으며 배기가스의 배출량 감소 효과는 점점 줄어드는 것으로 나타났다.