• 제목/요약/키워드: Water-mist method

검색결과 35건 처리시간 0.022초

화재용 중저압 물분무 노즐의 분무특성에 관한 연구 (A Study on Spray Characteristics of Water Mist Nozzle with Mid-low Pressure for Fire Suppression)

  • 김성찬;유홍선;박현태;방기영
    • 한국안전학회지
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    • 제18권1호
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    • pp.28-32
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    • 2003
  • The present study investigates the spray characteristics of water mist nozzle with mid-low pressure for fire suppression. The examined nozzle types are swirl and spiral nozzle. The result shows that K factor of water mist nozzle is much smaller than those of general sprinkler. Spray angle of spiral nozzle is largest and more than $150^{\circ}$. SMD(Sauter Mean Diameter) of water mist nozzles is ranged between 100 and 200$\mu\textrm{m}$through measuring by image processing method. The spray pattern of spiral nozzle represent that water flux of first stream is 2 times larger than that of second stream. This study will contribute better understandings of the water-mist spray characteristics and useful daia for developing the water-mist nozzles.

Numerical analysis on the rapid fire suppression using a water mist nozzle in a fire compartment with a door opening

  • Lee, Jaiho
    • Nuclear Engineering and Technology
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    • 제51권2호
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    • pp.410-423
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    • 2019
  • Fire suppression using a water mist nozzle directly above an n-Heptane pool in a fire compartment with a door opening was numerically investigated using the Fire Dynamics Simulator (FDS) for the purpose of application in nuclear power plants. Input parameters for the numerical simulation were determined by experimental measurements. Water mist was activated 10 s after the fire began. The sensitivity analysis was conducted for three input parameters: total number of cubic cells of 6032-2,926,400, droplets per second of 1000-500,000, and extinguishing coefficient of 0-100. In a new simple calibration method of this study, the extinguishing coefficient yielding the fire suppression time closest to that measured by experiments was found for use as the FDS simulation input value. When the water mist jet flow made contact with the developed fire, the heat release rate instantaneously increased, and then rapidly decreased. This phenomenon occurred with a displacement of the flame near the liquid fuel pool. Changing the configuration of the door opening with different aspect ratios and opening ratios had impact on the maximum value of the heat release rate due to the flame displacement.

지하공동구의 연소방지설비에 관한 연구 (A Study of Smokeproof in Underground Culvert)

  • 홍경표;이영재;김선정
    • 한국화재소방학회논문지
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    • 제15권4호
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    • pp.57-63
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    • 2001
  • 최근 지하공동구내의 화재가 자주 발생, 도시의 기능이 마비되는 등 국민생활을 위협하고 있으며, 막대한 재산 및 인명피해를 초래하고 있다. 지하공동구 화재로 인한 조기진압은 소방법의 연소방지설비 기준에 적용하였을 경우 화재진압시 많은 문제가 있다고 판단된다. 지하공동구의 연소방지설비 중에는 여러 방식을 적용할 수 있으나, 본 연구에서는 물을 이용한 방식 중에 국내 및 소방법에서 적용되지 않고 있는 워터 미스트(water mist)방식에 대해서 연구하고 그 설치 방안을 제시하고자 한다.

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선박용 미분무수 소화설비의 성능평가연구 (A Study on the performance test of Water mist system as a fire extinguish system for Ships)

  • 김성윤;안병호;김동석;김유택
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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    • pp.155-156
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    • 2006
  • Developed and conducted a performance test of the Water mist system that is satisfied with the requirement of a fire test requiring Class 3 Engine Mock-up exceeding net volume $3,000m^3$ as per IMO's MSC/Circ. 668 Appendix B(Test method for fire testing equivalent water-based fire-extinguishing systems for machinery spaces of category A and cargo pump rooms).Even though fuel atomizing was continued for 15 sec. after stopping of the system according to the test method relating to the atomizing fire type, no fire was reignited. This result shows the excellence of the system. There was no damage to the contents of the system after the test.

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Numerical analysis to determine fire suppression time for multiple water mist nozzles in a large fire test compartment

  • Ha, Gaghyeon;Shin, Weon Gyu;Lee, Jaiho
    • 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.

Effectiveness of Friction Loss Calculation Used for Water Mist Fire Extinguishing System on Marine Vessels

  • Lee Kyung-Woo;Kim You-Taek;Lee Young-Ho;Kim Mann-Eung
    • Journal of Advanced Marine Engineering and Technology
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    • 제29권1호
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    • pp.86-97
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    • 2005
  • Nowadays, Water Mist Fire Extinguishing System is increasingly used in maritime field for various application. The fire extinguishing capability of the system should be verified by hydraulic calculation in the same manner as the conventional water based fire extinguishing system such as sprinkler system. water spray system and etc. Additionally, the review of effectiveness of friction loss calculation method used for hydraulic calculation is needed because the pipe flow characteristic of its piping system has higher Reynolds number than that of the conventional system. In this paper the review work was carried out based on the NFPA Code 750.

노즐 특성 변화에 따른 미분무수와 화염과의 상호작용에 관한 수치해석 (Numerical Analysis on Interaction between Fire Flame and Water Mist according to the Variation of Nozzle Performance)

  • 배강열;정희택;김형범
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.2983-2988
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    • 2007
  • In the present study, the numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes 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 numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m$ and a water mist nozzle that be installed 1.8m from fire pool. In the study, the parameters of nozzle for simulation are the droplet size and the spray velocity. Finally, the droplet size influences to fire flume on fire suppression than spray velocity because of the effect of terminal velocity, and the optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20m/s, respectively.

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미분무수 특성이 화재억제 메커니즘에 미치는 영향에 대한 수치해석적 연구 (Numerical Study on the Effects of Spray Properties of Water Mist on the Fire Suppression Mechanism)

  • 배강열;정희택;김형범
    • 한국분무공학회지
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    • 제22권4호
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    • pp.175-184
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    • 2017
  • The numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes 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 numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m^3$ and a water mist nozzle that be installed 1.8 m from fire pool. In the present study, the parameters of nozzle for simulation are the droplet size and the spray velocity. The droplet size influences to fire flume on fire suppression more than the spray velocity because of the effect of the terminal velocity. The optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20 m/s respectively.

LSP법에 의한 미세 물 분무 입자 고도분포계측에 관한 연구 (A study on the velocity distribution measurement for the fine water mist spray by using LSP method)

  • 이동호
    • 한국안전학회지
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    • 제11권4호
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    • pp.24-28
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    • 1996
  • The speckle photography technique is one of the novelest velocity measurement methods. This study examines the possibility that this technique will become practically applicable. In this study, LSP is applied to the fine water mist spray. Moreover, a He-Ne gas laser is employed as the light source in order to enhance the validity of this technique. It becomes clear that this technique using a He-Ne gas laser can obtain a whole instantaneous two-dimensional velocity distribution and also apply to test the performance of fine water spray.

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Radical Mist Generator Using a Water Plasma Jet and Its Sterilization Effect

  • Huh, Jin Young;Ma, Suk Hwal;Kim, Kangil;Choi, Eun Ha;Hong, Yong Cheol
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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    • pp.175.1-175.1
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    • 2016
  • In recent, tract infections such as atopic dermatitis, allergic rhinitis and a respiratory disease are increasing, giving rise to the atmospheric pollution, inflow of micro-size dust and side effect of humidifier disinfectant. In this context, the environment-friendly technology is required to eliminate airborne pathogens. We propose solution of the previous problems, making use of Radical Mist Generator (RMG). Existing technologies of air purification using a gas discharge produce harmful substances such as ozone, NOx, etc. However, the RMG uses a pure water as a plasma forming material. The RMG sprays the water mist, which contains reactive radicals to sterilize microorganisms. RMG is comprised of a power supply, plasma electrodes and a nozzle. In order to analyze the electrical characteristic and concentrations of reactive radicals, we employ an oscilloscope and a titration method. To test the sterilization effect of RMG, we used E.coli. We confirmed that E.coli was killed over 90%. Eventually, we expect that RMG can be promising tool for a purified system.

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