• 한국산학기술학회논문지
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• 제10권7호
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• pp.1433-1438
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• 2009

본 논문의 목적은 점화시기의 변화가 LPG/가솔린 겸용차량에 미치는 영향을 살펴보기 위한 것으로 가솔린 전용연료 모드를 LPG 전용연료 모드로 진각시킨 제어시스템을 제안하여 엔진회전수(1500rpm, 2000rpm) 및 점화시기 ($5^{\circ}$,$10^{\circ}$,$15^{\circ}$,$20^{\circ}$)의 변화에 따른 실린더내의 가스압력, 압력상승률 및 열발생률을 측정하였다. 그 결과 실런더내의 가스압력 및 압력상승률은 기관의 회전속도가 1500rpm 및 2000rpm 모두 점화시기가 진각될수록 증가하였으나, $20^{\circ}$부근에서의 압력상승률값만 약간 낮게 나타났다. 또한, 열발생률은 1500rpm에서 점화시기가 진각될수록 증가하였으며 2000rpm의 $20^{\circ}$부근에서 감소하는 경향을 볼 수 있었다.

• International Journal of Automotive Technology
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• 제8권4호
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• pp.413-419
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• 2007

Experimental study of additives on the ignition performance of a compression ignition natural gas engine is introduced, followed by results of a simulation of its working mechanism. From the experimental results, it is understood that engine ignition performance can be improved when a certain amount of Di-tertiary-butyl peroxide additive is added. If the mass fraction of Di-tertiary-butyl peroxide additive reaches as high as 14.2%, engine ignition can be realized at ambient temperatures with a glow plug temperature of about $750^{\circ}C$. From the simulation results, we verify that the Di-tertiary-butyl peroxide additive, by cracking its radicals at lower temperature, can accelerate reaction rate. Therefore, the additive is able to improve the ignition performance of natural gas significantly.

• 오토저널
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• 제11권6호
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• pp.48-56
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• 1989

A shock tube technique was developed in which a freely falling droplets column produced by an ultrasonic atomizer was ignited behind reflected shock. In the present study, the effects of turbulent mixing on the ignition delay of a cetane was decided, also, ignition process was investigated. For the purpose of disturbance of droplets column and mixing, authors installed turbulent lattice in shock tube. Usually, the ignition delay is so called Arrhenius plot which found break point in the Arrhenius plot on the high temperature side. The rate of misfiring increased rapidly below 1080K, but ignition took place from 838k and luminous flame was seen to spread over the whole section by turbulent lattice. Length, from end plate to turbulent lattice, was varied with 60,40,20mm. Also, ignition process was detected by Photo transistor. As a result, it was found that physical factors changed ignition delay greatly and turbulent mixing had a considerable effects in the ignition process.

• 한국연소학회지
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• 제15권4호
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• pp.58-64
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• 2010

Spontaneous ignition tests of five different coals with non-iso-thermal and iso-thermal test method based on the standard test procedure of NF T20-036 were carried. These five coals included the 2 low rank coals and 3 bituminous coals. Test results showed that the ignition temperatures of all coals at the iso-thermal conditions were higher than that of non-isothermal condition, and those of low rank SM and BR coal in both nonisothermal and isothermal conditions were lower than bituminous AN and CN coals. The chemical species of coals such as oxygen and hematite also plays an important role in enhancing the ignition rate that the ignition temperature of SM coal was lowered. The heat accumulation tendency of five coals inside outdoor stack pile was monitored with emphasis on the change in the temperature of the coal depth in stack pile. In case of low rank BR coal, its temperature inside coal stack pile due to the rate of high heat accumulation and oxidation was $59^{\circ}C$ compared to $51^{\circ}C$ for other SW bituminous coal. And the heat accumulation rate inside coal stack piles was increased with increased the Cp value which it was defined as the specific heat of coal at constant pressure, whereas other factors such as thermal diffusivity and conductivity of coal relatively had less effect on heat accumulation.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.1-7
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• 2007

The effect of the di-tertiary butyl peroxide (DTBP) additive on the heat release rate and emissions of a homogeneous charge compression ignition (HCCI) engine fueled with high Research Octane Number (RON) fuels were investigated. The experiments were performed using 0%, 1%, 2%, 3%, and 4% (by volume) DTBP-RON90 blends. The RON90 Fuel was obtained by blending 90% iso-octane with 10% n-heptane. The experimental results show that the operation range was remarkably expanded to lower temperature and lower engine load with the DTBP additive in RON90 fuel. The first ignition phase of HCCI combustion was observed at 850 K and ended at 950 K while the hot ignition occurred at 1125 K for all fuels at different engine working conditions. The chemical reaction scale time decreases with the DTBP addition. As a result, the ignition timing advances, the combustion duration shortens, and heat release rates were increased at overall engine loads. Meanwhile, the unburned hydrocarbon (UHC) and CO emissions decrease sharply with the DTBP addition while the NOx emissions maintain at a lower level.

• 한국안전학회지
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• 제21권1호
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• pp.53-58
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• 2006

This paper has been addressed on the discharge characteristics of the ignition coil by Weibull function. It analyzed discharge number and amount of discharge using Weibull distribution to know the inter-relationship between partial discharge and mileage. We detected the discharge which happens for 10 seconds. The applied voltage increased by 0.5[kV] at discharge inception voltage. We diagnosed failure rate using the shape parameters. As a result, we confirmed that the failure rate was increased, because the shape parameter showed the value of 5 according to increasing mileage degradation. Also, it is considered to increase the degradation of inner insulator of ignition coil. Because failure rate of virgin was increased from 0[%] to 25[%] after degradation, stability analysis of the ignition coil using Weibull analysis is possible.

• 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 Mechanical Science and Technology
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• 제14권8호
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• pp.891-899
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• 2000

The flame speed may be decomposed into the burning speed and the flame transport speed. The flame transport speed is affected considerably by the flow direction, variation rate of flow direction, and flow speed in the combustion chamber. Especially, the flow direction and the variation rate of flow direction at the spark plug location during the ignition period have an important effect on the ignition process and the early flame propagation process. We measured the flow direction component and the variation rate of flow direction with a hot wire probe at the spark plug location. It was shown that the representative flow direction of ignition period is the right-vertical direction of crank shaft and it was used to investigate the variation rate of flow direction.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.590-596
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• 2019

산업이 발달함에 따라 석탄, 석유등 화석연료의 사용이 증대되고 있다. 그 결과 온실가스의 증가와 더불어 이상기후 등의 문제가 발생하게 되었다. 이로 인해 주 자원을 대체 할 수 있는 친환경적인 신재생에너지에 관한 연구가 활발히 진행 중이며, 그 중 열효율이 높은 우드펠릿이 화력발전소, 가스보일러 등에서 대체연료로서 각광받고 있다. 그러나, 우드펠릿의 사용량은 꾸준히 증대 되고 있는 반면 우드펠릿의 사용 시 발생할 수 있는 화재 및 자연발화 등의 위험성에 대한 선행연구가 부족한 실정이다. 이에 본 연구에서는 길이 20 cm, 높이 20 cm, 두께 14 cm의 시료용기를 사용하여 항온조 내부 유량변화에 따른 우드펠릿 최소자연발화온도와 발화한계온도를 구하여 발화특성을 예측하였다. 그 결과 유량이 0 NL/min일 때 $153^{\circ}C$에서 주위온도보다 시료의 중심온도가 상승하여 발화하였고 이때의 발화한계온도는 $152.5^{\circ}C$를 구하였으며, 유량이 0.5 NL/min, 1.0 NL/min에서 발화한계온도인 $149.5^{\circ}C$를 구하였다. 또한 유량이 1.5 NL/min일 때 발화한계온도인 $147.5^{\circ}C$를 구하였으며, 동일한 저장량에서 유량이 증가할수록 발화한계온도가 낮아지는 결과를 도출하였다.

• 한국화재소방학회논문지
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• 제24권1호
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• pp.116-121
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• 2010

n-dodecane 연료 액적의 고온면 점화특성을 파악하기 위해 본 연구에서는 공기의 공급과 제어가 가능한 실험실 규모의 실험 장치를 제작하였다. 표면온도는 적외선 측정법에 의해 계측되었으며 적외선 측정법에 의해 계측된 온도는 k-type 열전대에 의해 측정된 온도와 비교하여 $10^{\circ}C$ 이내의 오차를 보였다. 각 공기 공급유량에 대하여 약 400회의 점화실험이 수행되었으며 점화실험결과로부터 점화확률 분포와 최소 점화온도에 관한 결과를 얻었다. 공기 공급유량이 3.0lpm인 경우를 제외하고 냉염과 열염 점화특성을 보였으며 공기 공급유량에 따라 냉염점화가 일어나는 온도범위가 큰 차이를 보였다. 실험결과 n-dodecane 연료의 최소고온면점화온도(MHSIT)는 공기공급 유량이 0.5lpm인 경우에 대하여 약 $300^{\circ}C$를 나타냈다. 본 연구에서는 외기조건에 따른 점화특성을 파악함으로써 초기 발화 메커니즘을 이해하고 조기화재 진압을 위한 시스템 설계의 기초적 자료로 활용된다.