• 한국자동차공학회논문집
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• 제3권1호
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• pp.65-75
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The results indicated that even the vety lean mixture, which is normally not flammable in single chamber type, could be burned within. a comparatively short time by using sub-chamber with stratified charge method. And the lean inflammability limit of mixture in a main chamber was about ($\phi_m$cr=O.46, when the equivalence ratio of a sub-chamber was $\phi_s$= 1.0. Initial time of pressure increase and total burning times were decreased and maximum combustion pressure. was increased as the equivalence ratio of both sub and main chamber approached unity. Specifically, initial time of pressure increase and total burning times were greatly affected rather by. the equivalence ratio of sub-chamber than that of main chamber. The maximum combustion pressure was little affected if the total equivalence ratio lies in the same range.

• 한국수소및신에너지학회논문집
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• 제21권3호
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• pp.193-200
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• 2010

Anode off-gas of high temperature fuel cell still contains combustible components such as hydrogen, carbon monoxide and hydrocarbon. In this study, a catalytic combustor has been applied to the high temperature fuel cell so that the combustion of anode-off gas can be boosted up. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study is designed to perform the experimental investigation on the combustion characteristics of the three commercial catalysts with a different composition. Screening tests with three catalysts are preceded before the performance examination since it is necessary to determine the most suitable catalyst for design configuration of the catalytic combustor. The performance analysis shows that methane conversion rate strongly depends on gas hourly space velocity (GHSV) as well as inlet gas temperature. Additionally, the GSHV optimization results show that the optimum GHSV will be in the range between 18,000 $hr^{-1}$ and 36,000 $hr^{-1}$. It is also shown that the minimum inlet temperature of catalytic reaction of methane is from $100^{\circ}C$ to $150^{\circ}C$.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2003년도 추계 학술발표회 논문집
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• pp.113-116
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• 2003

• 한국가스학회:학술대회논문집
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• 한국가스학회 2000년도 추계학술발표회 논문집
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• pp.215-220
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• 2000

• 한국자동차공학회논문집
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• 제7권6호
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• pp.8-16
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• 1999

In this study, a new type of laser-induced ignition using a conical cavity has been developed to utilize all the available incident laser energy. In the method, it is possibile to ignite combustible methane/air mixtures by directing a laser beam of a constant small diameter into a small conical cavity, without focusing the laser beam. Shadow graphs for the early stage of combustion process show that a hot gas jet is ejected from the cavity, especially with lean mixture. After a very show time, the hot gas jet finishes issuing and the flame behavior is quite similar to flame propagation initiated by a conventional spark ignition. The combustion process using the new method exhibits more rapid pressure increase and a higher maximum pressure rise than that of the center ignition using laser-induced spark, with significant decrease in the combustion time. Also, the new ignition method is numerically modeled to simulate the flame kernel development and subsequent combustion process using the KIVA-IIcode. The calculated results show satisfactory agreement with experimental results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.277-280
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• 2009

본 연구는 v-gutter형 보염기를 장착한 연소기 내에 발생한 연소 주파수의 발생 메커니즘에 대해 규명 하는 것이다. 연소기는 $40{\times}40\;mm$의 단면적을 가진 긴 덕트 형상을 가지고 있으며, 14mm의 폭을 가진 v-gutter 형의 보염기를 장착하였다. 연료로 등유와 메탄를 수직 분무하여 실험을 수행하였다. 연소 시 발생하는 주파수는 연소기의 형상에 기인한 1L 종방향 모드와 보염기에서 발생하는 와류 주파수가 주로 발생함을 확인하였다. 또한 연료의 특성에 기인한 주파수와 노즐의 영향에 대한 주파수가 저주파 영역에서 발생함을 확인하였다.

• 한국연소학회지
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• 제20권1호
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• pp.32-42
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• 2015

The combustion instability was experimentally investigated in model gas turbine combustor with dual swirl burner. When such instability occurs, a strong coupling between pressure oscillation and unsteady heat release excites a self-sustained acoustic wave which results in a loud sound, and can even cause fatal damage to the combustor and entire system. In present study, to understand the combustion instability with a premixed mixture, the detailed periods of pressure and heat release data in unstable flame mode were investigated by various measurement methods at relatively rich condition and lean condition near flammable limits. Also, to prepare the utilization of synthetic natural gas (SNG) fuel in gas turbine system, an investigation was conducted using a simulated SNG including methane as a reference fuel to examine the effects of $H_2$ content on flame stability. These results provide that the instability due to flash-back behaviour like CIVB phenomenon occurred at rich condition, while the repetition of relighting and extinction caused the oscillation of lean condition near flammable limit. From the analysis of $H_2$ content effects, it is also confirmed that the instability frequency is proportional to the laminar burning velocity at both rich and lean condition.

• 한국연소학회지
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• 제14권4호
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• pp.33-40
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• 2009

Waste Thermal Pyrolysis Melting process was proposed and has been studied in order to prevent air pollution by dioxin and fly ash generated from combustion process for disposal of waste. In this study, applicability as the fuel of diffusion burner of synthesis gas formed from Waste Thermal Pyrolysis process was addressed. Results showed that there is no big difference in the flame shape between MNDF and SNDF, and lift off was detected in MIDF but flame is more stable in SIDF which contains hydrogen with high combustion velocity as flow rate in first nozzle is increased. And radiation heat flux in inverse diffusion flame of synthesis gas was found to be more by 1.5 times than that in inverse diffusion flame of methane because of higher mole fraction of $CO_2$ with high emissivity in product gas.

• 한국분무공학회지
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• 제16권3호
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• pp.126-133
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• 2011

In HCCI Engine, combustion is affected by change of compression speed corresponding to engine speed. The purpose of this study is to investigate the mechanism of influence of engine speed on HCCI combustion characteristics by using numerical analysis. At first, the influence of engine speed was shown. And then, in order to clarify the mechanism of influence of engine speed, results of kinetics computations were analyzed to investigate the elementary reaction path for heat release at transient temperatures by using contribution matrix. In results, as engine speed increased, in-cylinder gas temperature and pressure at ignition start increased. And ignition start timing was retarded and combustion duration was lengthened on crank angle basis. On time basis, ignition start timing was advanced and combustion duration was shortened. High engine speed showed higher robustness to change of initial temperature than low engine speed. Because of its high robustness, selecting high engine speed was efficient for keeping stable operation in real engine which include variation of initial temperature by various factors. The variation of engine speed did not change the reaction path. But, as engine speed increased, the temperature that each elementary reaction would be active became high and reaction speed quicken. Rising the in-cylinder gas temperature of combustion start was caused by these gaps of temperature.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.37-41
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• 2004

Quenching phenomena is one of major concern in development of millimeter or sub-millimeter scale micro combustor for the size of the combustor is near extinction condition. In this work we focused on the effect of combustor wall condition that was parameterized by Perovskite LSC($La_{0.8}$$Sr_{0.2}$$CoO_3$) redox catalyst. The experiment was done by variable gap-width 2D wall equipment. The flame was produced by premixed methane-air jet issuing from millimeter-scale slot burner and it propagated through the narrow gap of the walls. By comparison of flame behaviour near catalyst-coated wall and simple glass wall, we investigated the effect of possible surface reaction on quenching phenomena. The flame between two plates was observed where the gap of the plates was reduced stepwise from 20mm to a distance of quenching occurrence. The two flames with and without surface modification were almost same by observation. But the gap for the occurrence of quenching was increased between catalyst-coated wall. So we concluded that surface reaction close to combustor wall has a negative effect on micro combustion.