• 제목/요약/키워드: flammability limit

검색결과 74건 처리시간 0.03초

A mechanistic analysis of H2O and CO2 diluent effect on hydrogen flammability limit considering flame extinction mechanism

  • Jeon, Joongoo;Kim, Yeon Soo;Jung, Hoichul;Kim, Sung Joong
    • Nuclear Engineering and Technology
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    • 제53권10호
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    • pp.3286-3297
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    • 2021
  • The released hydrogen can be ignited even with weak ignition sources. This emphasizes the importance of the hydrogen flammability evaluation to prevent catastrophic failure in hydrogen related facilities including a nuclear power plant. Historically numerous attempts have been made to determine the flammability limit of hydrogen mixtures including several diluents. However, no analytical model has been developed to accurately predict the limit concentration for mixtures containing radiating gases. In this study, the effect of H2O and CO2 on flammability limit was investigated through a numerical simulation of lean limit hydrogen flames. The previous flammability limit model was improved based on the mechanistic investigation, with which the amount of indirect radiation heat loss could be estimated by the optically thin approximation. As a result, the sharp increase in limit concentration by H2O could be explained by high thermal diffusivity and radiation rate. Despite the high radiation rate, however, CO2 with the lower thermal diffusivity than the threshold cannot produce a noticeable increase in heat loss and ultimately limit concentration. We concluded that the proposed mechanistic analysis successfully explained the experimental results even including radiating gases. The accuracy of the improved model was verified through several flammability experiments for H2-air-diluent.

질소로 희석된 LPG 연료의 가연한계와 화염 안정성 (Flammability Limit and Flame Instability of Nitrogen-Diluted LPG Fuel)

  • 안태국;남연우;이경우;이원남
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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    • pp.319-321
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    • 2012
  • The flammability limit and the flame instability of nitrogen-diluted LPG fuel was experimentally studied on a co-flow flame configuration. The combustion reaction of nitrogen-diluted hydrocarbon with air could be interpreted as the equivalent reaction of pure fuel with nitrogen-diluted air. Nitrogen-diluted LPG with nitrogen up to 90 % of nitrogen mole fraction in fuel, which is close to the flammability limit, could form a co-flow flame. Various parameters such as laminar or turbulent flame, the existence of diffusion flame with pure fuel, air temperature could affect the limit of flame formation.

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할로겐화 탄화수소의 첨가에 의한 폭발한계의 변화 (The Change of Flammability Limit by the Addition of Halogenated Hydrocarbons)

  • 한우섭;신창섭;정국삼
    • 한국안전학회지
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    • 제9권1호
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    • pp.83-88
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    • 1994
  • The change of flammability limit of n-heptane by the addition of halogenated hydrocarbon was studied. Experimental results showed that halogenated hydrocarbon has a combustion suppression effect and the heat capacity was a Important factor on the flammability limit. The combustion suppression effect of halogenated hydrocarbon was lower than halon, but higher than nitrogen, and the order of effect was $C_3$C1$_3$F$_3$> $C_2$HC1$_2$F$_3$> $C_2$H$_2$F$_4$.

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점화에너지 방전특성이 희박연소한계에 미치는 영향 (Effects of Ignition Energy Discharge Characteristics on the Lean Flammability Limit)

  • 이중순;김진영;이종승;정성식;하종률
    • 한국자동차공학회논문집
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    • 제6권4호
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    • pp.47-55
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    • 1998
  • A new ignition system concept was developed to improve ignition performance, accuracy of control and the reliability of the ignition system. The new ignition system has ho호 frequency discharge characteristics with 1.5-2.0 ms discharge duration, in place of the usual solitary longer duration event. We applied the system to a commercial engine to study its influence on the maximum combustion pressure attained during the cycle, when this peak pressure occurred, imep, variation rate of the engine speed and the flammability limit of a lean mixture. In this study, we clarified that the new ignition system had a beneficial effect of the lean mixture flammability limit. Also for a given mixture strength we found that the mew ignition system gave a higher peak cylinder pressure than in the case of the conventional ignition system.

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전극위치에 따른 전기장 내 프로판 예혼합 화염의 특성 (Characteristics of Premixed Propane Flame in Electric Field according to Electrode Position)

  • 김태훈;김민석;김혜민
    • 한국분무공학회지
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    • 제28권3호
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    • pp.134-142
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    • 2023
  • Electric field assisted combustion is a method that reduces instability in lean combustion. In this study investigated the effects of electrode position on propane-air flame characteristic using a ring electrode. Results showed that burning velocity was not affected by electrode position, but positive voltage expanded the flammability limit while negative voltage contracted it. The effect of voltage polarity on the flammability limit decreased as the electrode position increased. Expanding the flammability limit with a positive voltage can reduce NOx emissions.

공기밸브형 맥동연소 시스템의 안정성 및 성능특성에 관한 연구 (A Study on Stability and Performance Characteristics in Aero - Valved Pulsating Combustion System)

  • 임광렬
    • Journal of Advanced Marine Engineering and Technology
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    • 제17권4호
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    • pp.11-19
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    • 1993
  • The experimental study was carried out to investigate the stability and the performance characteristics of the aero-valved pulsating combustion system with maximum operating capacity of 60KW. The effect of geometry of combustion system on the stable condition, the flammability limit, the total pressure oscillation amplitude, and the operating frequency can be identified, and the maximum turn-down-ratio is obtained up to 3.3. The total pressure oscillation amplitude can be controlled by tunning the length of the air inlet pipe. The empirical equation with which the operating frequency can be approximated is proposed and the discrepancy is within 5%. The volumetric efficiency is identified to be one of the important parameters determining the upper flammability limit and the maximum value of which is approximately 22%.

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난류 부분예혼합 화염을 이용한 난연성 유증기 처리에 관한 연구 (Combustion of Low Concentration VOC on a Turbulent Partially Premixed Flame)

  • 안태국;박선호;남연우;이원남
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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    • pp.207-210
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    • 2014
  • The potential of combustion treatment of low concentration VOC on a turbulent partially premixed flame has been studied experimentally. The significant decrease in hydrocarbon concentration from the low concentration VOC was observed with a turbulent partially premixed flame. The VOC/inert gas mixture whose fuel concentration is beyond the flammability limit could be treated in this method.

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A STUDY OF THE FLAMMABILITY LIMIT OF THE BACKWARD FACING STEP FLOW COMBUSTION

  • Tae-Ho Lee
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 1993년도 제1회 학술강연회논문집
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    • pp.55-61
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    • 1993
  • An experimental investigation was conducted in order to determine the flammability limit of the solid fuel ramjet using the backward facing step flow combustion of the plexiglass grain. In order to get the different step height ratio, the grain was drilled straight forward or stepwise. The Phoenics computer code was adopted in order to compare. the flow patterns of the some sample tests using a non-reacting cold turbulent flow model. The stepwise grain give some loading advantage; specially thin and long shape grain design.

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DBD 플라즈마 개질에 의한 탄화수소계 연료 화염의 가연한계 변화 (The Effect of DBD Plasma on Hydrocarbon Fuel Reforming and Change in Flammability Limits)

  • 송민철;안태국;남연우;박선호
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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    • pp.189-192
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    • 2015
  • An experimental study was conducted to find the effect of DBD plasma on the flammability limits of inert-gas-diluted fuel. The results showed that the concentration of diluting nitrogen at flammability limit increased when nitrogen-diluted methane and propane were reformed by plasma, while it decreased when nitrogen-diluted ethylene was reformed by plasma. Gas chromatography results suggested that the fuel type dependence of flammability limits is due to the difference in the concentrations of hydrogen and hydrocarbon species in reformed fuel.

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인젝터 리세스와 추진제 공급유량이 메탄-산소 확산화염의 가연한계와 구조에 미치는 영향 (Effects of the Recess and Propellants Mass Flow on the Flammability Limit and Structure of Methane-Oxygen Diffusion Flame)

  • 홍준열;배성훈;김정수
    • 한국추진공학회지
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    • 제22권1호
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    • pp.28-35
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    • 2018
  • 전단 동축형 인젝터를 통해 분사된 기체메탄-기체산소 확산화염의 가연한계와 구조분석을 위해 인젝터 리세스와 추진제 공급유량에 따른 연소실험이 수행되었다. 연구 결과, 추진제 운동량 플럭스 비가 증가함에 따라 높은 산화제 레이놀즈 수 구간에서도 안정적인 부착화염이 관찰되었으며, 인젝터 리세스는 화염의 형태와 가연한계에 큰 영향을 미치지 않음을 확인하였다. 자발광 기법을 통해 가시화된 부착화염은 추진제 분사조건이 변함에도 불구하고 항상 일정한 지점에서 최대 OH 라디칼 방사강도를 나타내었으며, 그 강도는 리세스에 의해 심하게 감소함을 확인하였다.