• 한국자동차공학회논문집
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• 제15권1호
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• pp.49-55
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• 2007

The characteristics of auto-ignition and combustion process of a single droplet of emulsified fuel suspended in a high-temperature air chamber have been investigated experimentally with various droplet sizes, surrounding temperatures, and water contents. The used fuels was n-Decane and it was emulsified with varied water contents whose maximum is 30%. The high-speed camera has been adopted to measure the ignition delay and flame life time. It was also applied to observe micro-explosion behaviors. The increase of droplet size and chamber temperature cause the decrease of the ignition delay time and flame life-time. As the water contents increases, the ignition delay time increases and the micro-explosion behaviors are strengthened. The starting timings of micro-explosion and fuel puffing are compared for different droplet sizes and the amount of water contents.

• 한국화재조사학회지
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• 제5권1호
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• pp.25-28
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• 2004

Since the very first use of optical systems in the process industries there has been a tacit assumption that, because they are not electrical, they do not present an ignition risk when used in flammable atmospheres. This paper describes about an optical ignition mechanism from experimental work carnied out by Sira Safety Services Limited(UK) and whether there is sufficient of an ignition risk for precautions to be advisable when optical systems are used in flammable atmospheres.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.45-52
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• 2008

In order to investigate the initiation and propagation processes of a spherical detonation wave induced by direct initiation, numerical simulations were carried out using two-dimensional compressible Euler equations with an axisymmetric assumption and a one-step reaction model based on Arrhenius kinetics with various levels of ignition energy. By varying the amount of ignition energy, three typical initiation behaviors, which were subcritical, supercritical and critical regimes, were observed. Then, the ignition energy of more than $137.5{\times}10^6$ in non-dimensional value was required for initiating a spherical detonation wave, and the minimum ignition energy(i.e., critical energy) was less than that of the one-dimensional simulation reported by a previous numerical work. When the ignition energy was less than the critical energy, the blast wave generated from an ignition source continued to attenuate due to the separation of the blast wave and a reaction front. Therefore, detonation was not initiated in the subcrtical regime. When the ignition energy was more than the minimum initiation energy, the blast wave developed into a multiheaded detonation wave propagating spherically at CJ velocity, and then a cellular pattern radiated regularly out from the ignition center in the supercritical regime. The influence on ignition energy was observed in the cell width near the ignition center, but the cell width on the fully developed detonation remained constant during the expanding of detonation wave due to the consecutive formation of new triple points, regardless of ignition energy. When the ignition energy was equal to the critical energy, the decoupling of the blast wave and a reaction front appeared, as occurred in the subcrtical regime. After that, the detonation bubble induced by the local explosion behind the blast wave expanded and developed into the multiheaded detonation wave in the critical regime. Although few triple points were observed in the vicinity of the ignition core, the regularly located cellular pattern was generated after the onset of the multiheaded detonation. Then, the average cell width on the fully developed detonation was almost to that in the supercritical regime. These numerical results qualitatively agreed with previous experimental works regarding the initiation and propagation processes.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.247-248
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• 2012

Unidentified self-ignitions were reported when the high-pressure hydrogen gas suddenly leaked out. This paper presents a flow visualization study to investigate the self-ignition mechanism in a test tube how the ignition process is initiated and the flame propagates with measurement of a number of pressure and light sensors installed in the tube supported the analysis of the self-ignition. The test result showed the location of the self-ignition taken place and critical static pressure at the boundary layer for self-ignition.

• 한국안전학회지
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• 제32권2호
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• pp.66-71
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• 2017

The autoignition temperature (AIT) is crucial combustible characteristics which need attention in chemical process that handle hazardous materials. The AIT, also to as minimum spontaneous ignition temperature(MSIT), is the lowest temperature of a hot surface at which the substance will spontaneously ignite without any obvious sources of ignition such as a spark or flame. The AIT may be used as combustion property to specify operating, storage, and materials handling procedures for process safety. This study measured the AITs of n-propanol+acetic acid system from ignition delay time(time lag) by using ASTM E659 apparatus. The AITs of n-propanol and acetic acid which constituted binary system were $435^{\circ}C$ and $212^{\circ}C$, respectively. The experimental AITs of n-propanol+acetic acid system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D.(average absolute deviation). In the case of n-propanol and acetic acid system, the minimum autoignition temperature behavior (MAITB), which is lower than the lower AIT, is shown among the two pure substances constituting the mixture.

• International Journal of Safety
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• 제1권1호
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• pp.47-51
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• 2002

This study was performed by measuring the minimum ignition temperature of polyurethane form recovered from the recycling process of the end-of-life home appliances. The critical ignition temperature of polyurethane form was lower as the size of the sample vessel was increased, and that of polyurethane form using cyclopentane as the forming agent was relatively lower than the polyurethane form using CFC and the combustion of cyclopentane-polyurethane form occurred fiercely. It is considered that the recycling process of end-of-life home appliances using cyclopentane-polyurethane form as the insulator would require a special fire and dust explosion prevention measures since there exists a high potential hazard of fire and dust explosion during crushing and storage processes.

• 대한기계학회논문집
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• 제9권5호
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• pp.627-637
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• 1985

본 논문에서는 종래의 방법을 개량해서 연소과정의 휘도변화를 전기적신호로 변환시키고, 이 전기신호와 연료분사개시기에 발생하는 전기신호와의 시간차를 시간 간격측정기에 의해 계측하는 방법을 택했다. 이 방법에 의해 측정하고저 하는 온도 또는 연료의 종류별로 매 1,000개의 시간차 데이터를 퍼스널.컴퓨터(personal compu- ter)에 기억시켜 통계처리했다.그리고 착화지연기간의 측정결과에 대해서는 보조연 료로서 사용한 유기화합물의 반응성으로 부터 고찰했다.

• 청정기술
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• 제26권3호
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• pp.204-210
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• 2020

본 연구에서는 F-T 공정을 통해 합성하여 제조한 바이오항공유(Bio-7629, Bio-5172)와 기존에 사용 중인 석유계항공유(Jet A-1)의 점화특성을 비교하여 분석하였다. Combustion research unit (CRU) 장비를 활용하여 각 항공유의 점화지연시간을 측정하였고, 그 결과를 연료의 물성 및 구성 화합물에 대한 분석을 통해 해석하고자 하였다. 점화지연시간은 Bio-5172가 가장 짧게 측정되었으며 Jet A-1이 가장 길게 측정되었다. 이는 물리적 점화지연시간에 영향을 줄 수 있는 연료의 물성 측면에서 Jet A-1이 가장 큰 표면장력을 가지며 Bio-5172가 가장 낮은 점도를 갖기 때문인 것으로 해석된다. 또한, 각 연료를 구성하는 화합물의 종류 및 비율에 대하여 분석한 결과, 실험 대상 바이오항공유에 없는 방향족화합물이 Jet A-1에는 약 22.8%의 비율로 존재함을 확인하였다. 이는 산화 과정 시에 비교적 반응성이 낮은 benzyl radical을 생성하여 점화지연시간이 길게 측정되는 데에 영향을 주는 것으로 판단된다. Bio-7629와 Bio-5172는 paraffin으로만 구성되어 있으며, n-/iso-의 값은 각각 0.06, 0.80으로 큰 차이를 보였다. 가지화 된 정도가 낮은 paraffin일수록 산화 시에 생성되는 peroxy radical의 이성질화가 빠르게 진행되어 점화의 전파속도 또한 빨라진다. 따라서 n-paraffin의 함량이 비교적 높은 Bio-5172의 경우에 점화지연시간 또한 짧게 측정된 것으로 해석된다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.83-90
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• 2004

A flywheel-driven rapid compression and expansion machine is developed and utilized for experimental study of homogeneous charge compression ignition combustion. Compression ignition of homogeneous charge in IC engines offers possibilities of realizing ultra-lean engine operation with greatly reduced NOx and particulate formation. Fundamental investigations are carried out in order to better understand this ideal engine combustion mechanism. Perfectly premixed propane-air mixtures of various equivalence ratio are compression-ignited in the rapid compression and expansion machine, and the characteristics of the auto-ignition and the following combustion process are analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1704-1709
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• 2004

New reduced chemical kinetic mechanism for prediction of autoignition process of HSDI diesel engine was investigated. For precise prediction of the ignition characteristics of diesel fuel, mechanism coefficients were fitted by the experimental results of ignition delay of diesel spray in a constant volume vessel. Ignition delay of diesel engine on various operation condition was calculated based on the new reduced chemical mechanism. The calculation results agreed well with experimental data.