• 한국자동차공학회논문집
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• 제9권6호
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• pp.40-46
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• 2001

An experimental investigation is proceeded to study on the relationship between spark ignition characteristics and the performances of an S. I. engine. The ignition parameters examined in this study are the ignition energy and discharging duration. The combustion pressure and exhaust gas are measured during the experiment. From the measured data of cylinder pressure, the heat release rate, the mass fraction burned, and the COV of IMEP are calculated. The dwell time and the injection time are varied. A single cylinder engine and a 30kW dynamometer are employed. Four different kinds of ignition systems are assembled, and one commercial ignition system is adopted. The experimental results show that the ignition energy is increased as the dwell time extended until the ignition energy is saturated. The higher ignition energy is effective in achieving the laster burning velocity and less producing HC emission. However, when the amount of ignition energy is similar, while the discharge duration becomes longer, the burning velocity is reduced but the engine operation becomes stable in terms of the COV of IMEP.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.132-137
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• 2002

Recently, impinging spray is used for atomization of diesel engine, but it bring on adhesion of fuel. Therefore, we studied about droplet behavior on high temperature plate changing the size of droplet, surface temperatures, and surface roughness of plate. In this study, We studied to confirm experimentally about mechanism of evaporation and ignition process of single fuel droplet. We observed evaporation time, evaporation appearance and ignition delay time by the photopraphs of 8mm video camera. Experimental results are summarized as follows: 1. The boiling point of fuel affect a evaporation and ignition process. 2. The surface roughness affect a evaporation time. 3. The ignition delay time relate to evaporation characteristic.

• 한국화재소방학회논문지
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• 제17권4호
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• pp.117-123
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• 2003

본 연구에서는 Setchkin 착화성시험장치와 산소소비원리를 이용한 콘칼로리미터를 사용하여 난연처리되지 않은 경질우레탄폼의 착화특성 및 열방출특성 및 플래쉬오버 가능성에 대하여 연구하였다. 연구결과 경질폴리우레탄폼의 유도발화온도(FIT)는 $383^{\circ}C$∼$390^{\circ}C$, 자연발화온도(SIT)는 $493^{\circ}C$∼$495^{\circ}C$로 나타났으며 자연발화온도가 유도발화온도에 비해 약 $100^{\circ}C$ 높게 나타났다. 콘칼로리미터실험에서는 착화시간은 heat flux의 크기가 증가할수록 빨라졌으며 동일한 heat flux 크기에서는 밀도가 작을수록 착화시간은 짧게 나타났다. 열방출율은 $50 ㎾\m^2$에서 가장 크게 나타났으며, 최대열방출율의 경우 heat flux의 크기와 밀도가 커질수록 증가하는 경향을 보였다. 착화시간과 열방출율의 관점에서 경질폴리우레탄폼의 화재성능은 가해진 heat flux의 크기와 밀도에 큰 영향을 받는 것으로 나타났으며, Petrella의 제안방법에 의해 플래쉬오버 가능성을 분류한 결과 플래쉬오버 가능성이 큰 것으로 분류되었다.

• 한국추진공학회지
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• 제22권4호
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• pp.85-90
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• 2018

본 논문에서는 점화 위치 및 시간에 따른 점화 지연 및 연소 불안정에 미치는 영향을 관찰하는 것이 목표이다. 산화제는 기체 산소를 사용하였고 연료는 액체 케로신을 사용하였다. 점화 지연 및 연소 불안정 정도를 관찰하기 위해 압력 트랜스듀서를 이용하여 정압을 측정하였다. 모든 경우의 점화기 작동시기를 제외한 점화 시퀀스는 동일하게 설정하였고 점화 시간은 25 ms 간격으로 설정하였다. 점화 시간이 늦어질수록 초기 압력 피크값과 점화 지연 시간이 증가하는 경향을 보였다. 점화 위치가 분사기로부터 멀어질수록 초기 압력 피크 이후 불안정한 화염 발달 구간이 존재하였다.

• 한국화재소방학회논문지
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• 제33권1호
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• pp.7-14
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• 2019

우드펠릿은 화력발전소 및 화목 보일러의 연료로 많이 사용되고 있으나 발열량이 높은 우드펠릿을 장기간 보관 시 자연발화의 위험성이 있다. 본 연구에서는 시료 용기의 크기에 따라 유량의 변화에 따른 최소자연발화온도와 발화한계온도를 구하였으며, 발화한계온도를 이용하여 겉보기 활성화 에너지를 측정함으로써 우드펠릿의 발화 특성을 예측하였다. 겉보기 활성화 에너지는 190.224 kJ/mol을 구하였다. 용기에 저장된 시료량이 두꺼워질수록 시료 표면에서 중심까지의 열전달이 어려워 발화유도시간이 긴 것으로 나타났으며, 용기의 크기가 같을 경우 유량의 양이 많아 질수록 자연발화온도는 낮아졌다. 또한 시료용기가 커질수록 자연발화온도는 낮아지고 발화유도시간은 길어지는 것으로 나타났다.

• 한국추진공학회지
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• 제23권2호
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• pp.13-20
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• 2019

본 연구에서는 석유계항공유와 혼합하여 사용이 가능한 바이오항공유의 혼합 비율에 따른 점화지연 특성의 변화를 확인하기 위하여, 두 항공유를 일정한 비율로 혼합한 시료의 점화지연시간을 측정하여 분석하였다. 측정한 모든 온도 조건에서 Bio-6308의 점화지연시간이 Jet A-1의 점화지연시간보다 짧게 나타났으며, 두 항공유를 일정한 비율로 혼합한 경우에도 Bio-6308의 함량이 증가할수록 점화지연시간은 짧아지는 경향을 보였는데, 이는 Jet A-1을 구성하는 방향족 화합물의 영향 때문임을 n-heptane/Toluene의 점화지연시간 측정을 통해 확인하였다.

• 대한기계학회논문집B
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• 제22권3호
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• pp.294-302
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• 1998

Ignition characteristics of a vertical solid fuel plate with block have been investigated experimentally. For low radiant heat flux, ignition does not occur in a vertical solid fuel plate without block. In the case with the block on a vertical fuel plate, however, ignition can occur by increasing the residence time and the time to absorb the incident radiation flux by fuel vapor in gas phase. The ignition occurs below block and the point varies according to the block location and the block height. As the block height increases, the block locates at higher position, and the hot wall temperature increases, the ignition delay time decreases. Also as the initial temperature of fuel plate rises, the ignition delay time of the solid fuel plate decreases. The temperature distribution of solid fuel plate with block is nearly proportional to the radiant heat flux distribution. Therefore, the effect temperature by natural convection heat transfer is of the same order as that of inhibition of temperature increase by pyrolysis.

• 제어로봇시스템학회논문지
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• 제13권2호
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• pp.179-186
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• 2007

This paper presents new ignition method and ignition recognition logic for a microturbine. New ignition method is designed by constant speed control of a microturbine with pre-determined time during a ignition period. It make more accurate air-fuel ratio as well as give enough time to ignition system to have full performance under cold temperature. And ignition recognition logic is designed by observing output current change of inverter by generating output torque of a microturbine in the instant of ignition. For filtering a output torque current of inverter with high frequency, we applied a moving average method. So far, ignition recognition is usually implemented by measuring of exhausted gas temperature(EGT) of microturbine. The proposed logic can give more accurate judgement of ignition as well as keep a good working of starting system under out of order a temperature measuring system and biased initial value of EGT sensor. Finally, the two proposed logics are proved by field operating a microturbine under various conditions.

• 한국자동차공학회논문집
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• 제12권3호
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• pp.75-82
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• 2004

The allowable exhaust standard has been intensified as a part of the countermeasure to decrease air pollution in the world. As the cars with an alternative fuel starts to get into the spotlight, the cars with low emission has been introduced and exhaust gas regulation forced in this country. These days, LPG vehicles, which infrastructure of fuel was already built up, and CNG vehicles are recognized for alternative fuel cars in this country. In this study, the constant volume combustion chamber was manufactured and used for experiments to obtain the ignition characteristics of LPG fuel and the optimal ignition energy. The experiment measured the combustion characteristics, in regard to the change of combustion variable, and the change of ignition energy. During the combustion of fuel, the maximum temperature inside the combustion chamber is higher when the initial pressure is higher. The burning velocity also seems to have the same characteristic as the temperature. However, the heat flux did not change much with the theoretical correct mixture but the various initial temperature of the combustion chamber. The heat flux got faster and ignition energy bigger as the dwell time of the ignition system expanded. When the dwell time get longer, the ignition energy also increased then fixed. The ignition energy increased as the initial pressure inside the combustion chamber higher. The heat flux got faster as the dwell time expanded.

• 한국연소학회지
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• 제22권3호
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• pp.35-40
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• 2017

Jet aviation fuel is one of liquid fuel which are used in aircraft engines. Korean domestic jet fuel, called Jet A-1, is tested for measurement of ignition delay time by using a shock tube manufactured recently. The temperature varies from 680 to 1250 K and the pressure and equivalence ratio of Jet A-1/air are fixed 20 atm and 1.0, respectively, for this experiment. The ignition delay time data of Jet A-1 are compared with those of Jet A, which has similar properties to Jet A-1. The behavior of negative-temperature-coefficient (NTC) is observed in the temperature range 750-900 K. In addition, ignition delay time of iso-octane is measured, which is one of the surrogate components for jet aviation fuel. The experimental data are compared and validated with the previous results from the literatures. A surrogate fuel for the present Jet A-1 consists of 45.2% n-dodecane, 32.1% iso-octane, and 22.7% 1,3,5-trimethylbenzene. The predicted ignition delay time for the surrogate agrees well with the measured one for Jet A-1.