• 한국기계가공학회지
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• 제15권5호
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• pp.117-124
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• 2016

In this paper, we developed a breather valve with a water mist system for use near an oil storage tank. Our process applied a water mist system to the flame arrester to evaluate the fire suppression characteristics. For the fire suppression evaluation of the water mist system, we evaluated the angle of the nozzle, fire suppression, spray particle size, flashback, fire suppression time, and fire suppression test of antifreeze. Through the fire suppression test, the best fire suppression nozzle used an angle of $140^{\circ}$, and the flashback phenomenon of flame arrester did not occur. The fire suppression time of water mist system time was within three seconds, and the antifreeze was no problem with the fire suppression.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1157-1166
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• 2021

In this study, a numerical sensitivity analysis was performed to determine the fire suppression time for a large number of water mist nozzles in a large fire compartment. Fire simulations were performed using FDS (Fire dynamics simulator) 6.5.2 under the same condition as the test scenario 5 of the International Maritime Organization (IMO) 1165 test protocol. The sensitivities of input parameters including cell size, extinguishing coefficient (EC), droplets per second (DPS), and peak heat release rate (HRR) of fuel were investigated in terms of the normalized HRR and temperature distribution in the compartment. A new method of determining the fire suppression time using FDS simulation was developed, based on the concept of the cut-off time by cut-off value (COV) of the heat release rate per unit volume (HRRPUV) and the cooling time by the HRR cooling time criteria value (CTCV). In addition, a method was developed to determine the average EC value for the simulation input, using the cooling time and cut-off time.

• 대한기계학회논문집B
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• 제27권3호
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• pp.367-373
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• 2003

The present study investigates the fire suppression characteristics using a water mist fire suppression system. The fire extinguishing times are measured for various fire sources, fuel types, and different total flooding rates of water mist. Pool fire with hydrocabon fuel is successfully extinguished within a minute under the operating conditions of the water mist system. Two different regimes of the smoke layer cooling are observed, such as rapid and slow cooling processes. The regimes are divided by threshold time which is calculated with auto-correlation function. The threshold time for the initial cooling decreases with increasing water flow-rates and fire sources. These initial cooling effects play an important role in preventing the occurance of flashover fire by the initial fire suppression.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.542-549
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• 1997

HFC-227ea and HCFC Blend A were evaluated using full-scale fire tests to obtain information on their fire suppression performance, drop-in capability, thermal decomposition products and physical behaviour of the agent such as its flow characteristics in the piping system. Also, full-scale tests were conducted with Halon 1301 to provide a basis for comparison. Halon 1301, at concentrations of 5% to 7.5%, showed effective total-flooding fire- extinguishing performance for all test scenarios. HFC-227ea, at a design concentration of 7.6% or higher, and HCFC Blend A, at a design concentration of 12%, extinguished all fires in the test facility, however, these agents produced higher concentrations of acid gases than Halon 1301. The quantity of the acid gases generated during fire suppression was dependent on agent concentration, agent discharge time, fire type and size as well as extinguishment time.

• 동력기계공학회지
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• 제13권5호
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• pp.25-33
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• 2009

In the present study, the numerical investigation has been carried out to see the effects of water mist sprays on the fire suppression mechanism. The special-purposed program named as FDS was used to simulate the interaction of fire plume and water mists. This program solves the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The computational domain was composed of a rectangular space dimensioned as $L{\times}W{\times}H=4.0{\times}4.0{\times}2.5\;m^3$ with a mist-injecting nozzle installed 1.0 m high from the fire pool. In this paper, two types of nozzles were chosen to compare the performance of the fire suppression. Numerical results showed that the nozzle, type A, with more orifices having smaller diameters had poorer performance than the other one, type B because the flow injected through side holes deteriorated the primary flow. The fire-extinguishing time of type A was 2.6 times bigger than that of type B.

• 보존과학연구
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• 통권31호
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• pp.155-171
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• 2010

Wooden cultural heritages have many factors of fires and structural characteristics vulnerable to the fire extinguishing. Also, they are surrounded with forests and so remote from fire stations, which make it difficult to handle it quickly when fires break out. Wooden cultural heritages made of wood materials belong to the general fire in a Class A. Taking characteristics such as a smoldering and a backfire from the that fire of wooden materials into consideration, extinguishing the fire by the cooling system is the most effective. If the fire can't be put out at the early stage, it is almost impossible to protect wooden cultural heritages from the fire, because wooden structures can be destroyed in a high temperature and in a short time and it takes around average 7 minutes to reach its peak of flames in the process of a fire. According to the geographical and environmental situation of the cultural heritages, currently, the fire-prevention facilities such as the auto fire detector for the prompt detection, the water mist fire suppression system for the 1st early and urgent fire suppression and the outdoor fire hydrant and the water curtain etc. for the 2nd full-scale suppression and the prevention of the fire gaining force are being installed for the wooden cultural heritages.

• 한국화재소방학회논문지
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• 제17권1호
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• pp.1-7
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• 2003

통상 소형 건물이나 일반주택은 자동화설비 대신 수동식소화기에 의존하고 있어서 사람이 없거나 노약자만 있을 시에는 화재에 매우 취약하다. 이에 대한 대책으로 발생한 화재를 초기에 자동으로 진압할 수 있도록, 자동감지장치가 탑재된 경제성 있는 자동식소화기가 개발되었다. 본 논문에서는 이에 대한 소화 특성을 현장 화재시험을 통하여 규명하고 그 실용화 방향을 제시하였다. 실험 결과, 제반성능은 우수하였으나, 열감지부인 이융성금속의 작동시간이 공간크기에 따라 크게 변화하고 5분을 초과하는 경우도 발생하므로, 이를 $ 12\m^2$이내의 공간에 대하여 작동시간을 3분 이내로 단축하기 위해서는 용융온도가 더욱 낮은 금속을 사용하고, 설치 위치도 1.5 m 이하보다는 천장부로 하는 것이 바람직한 것으로 나타났다.

• 한국화재소방학회논문지
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• 제33권6호
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• pp.1-8
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• 2019

본 연구에서는 물 분무 액적 특성 변화가 화재 진압에 미치는 영향을 FDS 6.5.2를 이용하여 수치적으로 분석하였다. 물 분무 노즐의 소화계수, 액적 분포함수, 중간체적 직경 및 초당 액적 수 변화에 대한 화재진압 특성은 정규 열방출률 곡선의 감소율와 냉각시간의 측면에서 평가되었다. 소화계수가 증가하면 정규열방출률 곡선이 더 급격하게 감소하고, 중간체적입경 변화가 화재진압에 영향을 미치는 것을 확인하였다. 단일 액적분포에서 초당액적수의 증가에 따라 정규 열방출률 곡선은 더 완만하게 감소하였으며, 다중분포에서는 초당액적수가 작은 조건에서만 정규 열방출률 곡선이 급격하게 감소하는 것을 확인하였다.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.215-221
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• 2003

A series of experiments were conducted to study the effectiveness of the extinction of a liquid pool fire with two different water atomizing nozzles. Fire source is small-scale circular stainless steel pan of 120mm in diameter with the fuels of hexane and ethanol. K-type thermocouples were used to measure the flame and fuel temperature along the pool centerline and under fuel surface. A digital camera was used to visualize the process of the fire suppression. The experimental results show that water mist droplet size is $115{\sim}180{\mu}m$ with nozzle A and $130{\sim}190{\mu}m$ with nozzle B. The extinguishing time of pool fire was reduced with the increase of pressure. When water droplets are small, they do not reach the flame base since they may be deflected or evaporated by the fire plume. However, influence of flow rate is more important than droplet size on fire extinction. Among the fire extinction mechanisms, drop of flame temperature is superior to suffocation of O2 concentration.

• 한국안전학회지
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• 제29권4호
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• pp.78-84
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• 2014

Viscosity agents were added to water to improve extinguishing performance of low pressure water mist suppression system on wood cribs fire, and a small scale wood cribs fire experiment was conducted to measure the extinguishing performance. CMC and agar were used for viscosity agent and as the amount of viscosity agent enlarges, it showed the increase of the viscosity of aqueous solution and the decrease of the fluidity. On wood cribs fire experiment, the extinguishing efficiency was improved with supplemental viscosity agent as it enhanced the adhesive time of aqueous solution on the wood, and therefore expanded the contact time of fire surface. The surface tension of aqueous solution was decreased with the addition of agar which to be assumed as an increase factor of extinguishing efficiency. By the extinguishing experimental result, the most effective extinguishing agent was CMC 0.6 wt.%, with the flame suppression time and the extinguishing time were reduced by 70s and 93s respectively at this concentration.