• Title/Summary/Keyword: Maximum Heat Release Rate

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Fire Resistance Study of PP Thermoplastic Composites with Particulate Reinforcements and Br Flame Retardants (무기 입자 강화제와 브롬(Br) 난연제에 따른 폴리프로필렌 복합재료의 난연성 향상에 관한 연구)

  • 곽성복;황성덕;남재도;고재송;최형기
    • Polymer(Korea)
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    • v.26 no.2
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    • pp.260-269
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    • 2002
  • The fire resistance of particulate polypropylene composite systems were investigated by using various reinforced particles such as zeolite, talc, $CaCO_3$ particles. In this study, The effect of particle size on the thermal properties of composite and the effect of reinforced particles on the fire resistance were studied. The inorganic reinforced particles used in this study were recycled zeolite(average particle diameter=85.34 $mu extrm{m}$), $CaCO_3$ (33.93 $mu extrm{m}$), and talc (18.51 $mu extrm{m}$). The fire resistance of composite systems was thoroughly examined by measuring limited oxygen index (LOI, ASTM D2863) and cone calorimetry (ASTM E1354, ISO 5660). Thermal stability of composite systems was thoroughly examined by measuring TGA. The flame retardants (DBDPO) and reinforced particles reduce the maximum heat release rate (M-HRR) in the order of Talc > $CaCO_3$ > recycled Zeolite. Comparing the cone calorimetry experimental results of the particle reinforced polymer composite system exhibited twice higher efficiency than DBDPO in polypropylene systems, and the LOI also showed similar trends to the cone calorimetry experiments. The optical and scanning electron microscopy techniques were used to investigate the composites ash layer and the core fracture surfaces in the burning process. The reinforcing inorganic particles seemed to accumulate at the surface of ash layer, and subsequently intercept the oxygen transport and heat transfer into the core area.

Assessment of the Habitability for a Cabinet Fire in the Main Control Room of Nuclear Power Plant using Sensitivity Analysis (민감도 분석을 이용한 원전 주제어실의 케비닛 화재에 대한 거주성 평가)

  • Han, Ho-Sik;Lee, Jae-Ou;Hwang, Cheol-Hong;Kim, Joosung;Lee, Sangkyu
    • Fire Science and Engineering
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    • v.31 no.2
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    • pp.52-60
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    • 2017
  • Numerical simulations were performed to evaluate the habitability of an operator for a cabinet fire in the main control room of a nuclear power plant presented in NUREG-1934. To this end, a Fire Dynamics Simulator (FDS), as a representative fire model, was used. As the criteria for determining the habitability of operator, toxic products, such as CO, were also considered, as well as radiative heat flux, upper layer temperature, smoke layer height, and optical density of smoke. As a result, the probabilities of exceeding the criteria for habitability were evaluated through the sensitivity analysis of the major input parameters and the uncertainty analysis of fire model for various fire scenarios, based on V&V (Verification and Validation). Sensitivity analyses of the maximum heat release rate, CO and soot yields, showed that the habitable time and the limit criterion, which determined the habitability, could be changed. The present methodology will be a realistic alternative to enhancing the reliability for a habitability evaluation in the main control room using uncertain information of cabinet fires.

Experimental Study of Fire Characteristics by Isocyanate Functional Parameter (이소시아네이트 관능기 매개인자에 의한 화재 특성의 실험적 연구)

  • Lee, Jae-Geol;Han, Kyoung-Ho;Jo, Hyung-Won;Yoon, Do-Young
    • Journal of the Korean Institute of Gas
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    • v.26 no.3
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    • pp.27-37
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    • 2022
  • With the recent increase in the spread of ESS (Electric Storage System), the damage to human life and property is also rapidly increasing due to continuous fires caused by ESS. In the manufacture of urethane sandwich panels used in ESS, it is necessary to improve the flame retardant performance. In this study, in order to realize the flame retardant properties of flexible polyurethane foam, the effect of the tissue density of the product due to the change of the isocyanate functional group parameter that changes the physical properties of the product on the fire performance was studied. The product was manufactured by changing the density of the urethane structure, and combustion performance tests, gas toxicity tests, and smoke density tests were performed. As a result, it was confirmed that the total amount of heat released had excellent performance when the isocyanate functional group was high, and had no correlation with the maximum heat release rate. When the value of the isocyanate functional group was 2.7 or more, the collapse of the shape could be prevented. In the gas hazard test, the performance was increased when the isocyanate functional group was relatively high, so a flame retardant for the Char system, which had a dense structure and easy to form a carbonized film, was added. confirmed to be. Therefore, as a result of this study, it is thought that it will be possible to lay the foundation for the development of a flame retardant to replace the cheap urethane sandwich panel used in the past.

INVESTIGATION OF RUNNING BEHAVIORS OF AN LPG SI ENGINE WITH OXYGEN-ENRICHED AIR DURING START/WARM-UP AND HOT IDLING

  • Xiao, G.;Qiao, X.;Li, G.;Huang, Z.;Li, L.
    • International Journal of Automotive Technology
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    • v.8 no.4
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    • pp.437-444
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    • 2007
  • This paper experimentally investigates the effects of oxygen-enriched air (OEA) on the running behaviors of an LPG SI engine during both start/warm-up (SW) and hot idling (HI) stages. The experiments were performed on an air-cooled, single-cylinder, 4-stroke, LPG SI engine with an electronic fuel injection system and an electrically-heated oxygen sensor. OEA containing 23% and 25% oxygen (by volume) was supplied for the experiments. The throttle position was fixed at that of idle condition. A fueling strategy was used as following: the fuel injection pulse width (FIPW) in the first cycle of injection was set 5.05 ms, and 2.6 ms in the subsequent cycles till the achieving of closed-loop control. In closed-loop mode, the FIPW was adjusted by the ECU in terms of the oxygen sensor feedback. Instantaneous engine speed, cylinder pressure, engine-out time-resolved HC, CO and NOx emissions and excess air coefficient (EAC) were measured and compared to the intake air baseline (ambient air, 21% oxygen). The results show that during SW stage, with the increase in the oxygen concentration in the intake air, the EAC of the mixture is much closer to the stoichiometric one and more oxygen is made available for oxidation, which results in evidently-improved combustion. The ignition in the first firing cycle starts earlier and peak pressure and maximum heat release rate both notably increase. The maximum engine speed is elevated and HC and CO emissions are reduced considerably. The percent reductions in HC emissions are about 48% and 68% in CO emissions about 52% and 78%; with 23% and 25% OEA, respectively, compared to ambient air. During HI stage, with OEA, the fuel amount per cycle increases due to closed-loop control, the engine speed rises, and speed stability is improved. The HC emissions notably decrease: about 60% and 80% with 23% and 25% OEA, respectively, compared to ambient air. The CO emissions remain at the same low level as with ambient air. During both SW and HI stages, intake air oxygen enrichment causes the delay of spark timing and the increased NOx emissions.

Effects of Multi-stage Pilot Split Injection Strategy on Combustion and Emission Characteristics in a Single-Cylinder Diesel Engine (단기통 디젤엔진에서 다단 파일럿 분할 분사 전략이 연소 및 배기가스 특성에 미치는 영향)

  • Lee, Hyungmin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.7
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    • pp.692-698
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    • 2020
  • This paper examines the effects of a multi-stage pilot split injection strategy on combustion and exhaust emission factors in a single-cylinder diesel engine. One analysis noted that in the single-injection condition, the maximum in-cylinder pressure and rate of heat release were highest. The pilot injection quantity was evenly divided, showing a tendency to decrease as the number of injections increased. In another injection condition, when the multi-stage pilot split injection strategy was applied, IMEP, engine torque, and combustion increased. The COVIMEP was greatest with the lowest combustion efficiency. The combustion ability was poor. In a single injection condition, the O2 concentration in the exhaust gas was the lowest and the CO2 was the highest. When the multi-stage split injection strategy was applied, the low temperature combustion process proceeded, and the oxidation rate of CO2 decreased while the emission level increased. In a single injection condition in which a locally rich mixture was formed, the HC emission level showed the highest results. A 55.6% reduction of NOx emission occurred under a three-stage pilot injection condition while conducting a multi-stage pilot split injection strategy.

Experimental Study on the Fire Behavior in Double Deck Tunnel (복층터널내 화재특성에 대한 실험적 연구)

  • Park, Jin-Ouk;Yoo, Yong-Ho;Kim, Hwi-Seung;Park, Byoung-Jik
    • Fire Science and Engineering
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    • v.30 no.2
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    • pp.75-80
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    • 2016
  • In the wake of expanding and overpopulating urban areas, traffic congestion has been worsening increasingly, causing huge economic losses. In a bid to effectively use the space of metropolitan areas, the construction and operation of a double deck tunnel has been on the rise. On the other hand, a lower height of a double deck tunnel is expected to generate more smoke and soot in a fire than other usual tunnels. Therefore, it is undesirable to apply the standard for fire intensity or smoke generation, which were designed for existing road tunnels. A part of an effort to propose a design fire curve that is useful for double deck tunnel, is intended to obtain and analyze the fire characteristics in a double deck tunnel through a real scale fire test. The test was conducted according to the fire scenario with one passenger car and two passenger cars; the monitored fire intensity was a maximum of 2.4 MW and 3.5 MW, respectively.

A numerical study on effects of thermal buoyance force on number of jet fans for smoke control (도로터널 화재시 열부력이 제연용 제트팬 댓수에 미치는 영향에 대한 해석적 연구)

  • Yoo, Ji-Oh;Shin, Hyun-Jun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.3
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    • pp.301-310
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    • 2013
  • Jet fans are installed in road tunnels in order to maintain critical velocity when fire occurs. Generally the number of jet fans against fire are calculated by considering critical velocity and flow resistance by wall friction, vehicle drag force, thermal buoyance force and natural wind. In domestic case, thermal buoyance force is not considered in estimating the number of jet fans. So, in this study, we investigated the pressure loss due to the thermal buoyance force induced by tunnel air temperature rise and the impact of thermal buoyance force on the number of jet fans by the numerical fire simulation for the tunnel length(500, 750, 1000, 1500, 2000, 3500m) and grade (-1.0, -1.5, -2.0%). Considering the thermal buoyance force, number of jet fans have to be increased. Especially in the case of 100MW of heat release rate, the pressure loss due to thermal buoyance force exceed the maximum pressure loss due to vehicle drag resistance, so it is analyzed that number of 2~11 jet fans are needed additionally than current design criteria. Thus, in case of estimating the number of jet fans, it must be considered of thermal buoyance force induced tunnel air temperature rise by fire.

Method for Preventing Asphyxiation Accidents by a CO2 Extinguishing System on a Ship (선박 내 CO2 소화설비에 의한 질식사고 방지 기법)

  • Ha, Yeon-Chul;Seo, Jung-Kwan;Hwang, Jun-Ho;Im, Kichang;Ryu, Sang-Hoon
    • Fire Science and Engineering
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    • v.29 no.6
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    • pp.57-64
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    • 2015
  • Carbon dioxide extinguishing systems are broadly used for onshore and offshore fire accidents because of excellent performance and low cost. However, there is risk with carbon dioxide systems, which have caused many injuries and deaths by suffocation associated with industrial and marine fire protection applications. In this study, a numerical analysis was performed to predict the fire suppression characteristics of a carbon dioxide system in the compressor room of ships. A double protection safety system is suggested to prevent suffocation accidents from carbon dioxide extinguishing systems. Four scenarios were selected to study the variation of the heat release rate, maximum temperature, a $CO_2$ and $O_2$ mole fraction, and fire suppression characteristics with the carbon dioxide system. The importance of proper design is suggested for a ventilation system in the compressor room of ships.