• Title/Summary/Keyword: Fire Expansion

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A Study on Enhancement of Combustion Performance by Dilution of Hydrogen in Heavy-Duty Hydrogen Engine (수소기관의 수소연료의 희석에 의한 역화억제효과에 관한 연구)

  • KIM, S.Y.;KIM, Y.Y.;Kim, Y.T.;LEE, JONG T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.4
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    • pp.348-354
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    • 2004
  • Hydrogen gas has several merits such as lower ignition energy, wide flammability and shorter quenching distance. It leads to high thermal efficiency but backfire occurrence. In this study, feasibility of expansion of BFL(Back-Fire Limit) equivalence ratio and combustion characteristics by a dilution of hydrogen fuel are experimently examined by using experimental heavy duty single cylinder hydrogen fueled engine. As results, it is found that BFL equivalence ratio is expanded to rich range and torque is increased.

An Experimental Study on the Explosion of Hydrogen Tank for Fuel-Cell Electric Vehicle in Semi-Closed Space (반밀폐공간에서 발생되는 차량용 수소연료탱크 폭발 실험)

  • Park, Jinouk;Yoo, Yongho;Kim, Hwiseong
    • Journal of Auto-vehicle Safety Association
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    • v.13 no.4
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    • pp.73-80
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    • 2021
  • Recently, Korea has established a plan for the supply of hydrogen vehicles and is promoting the expansion of the supply. Risk factors for hydrogen vehicles are hydrogen leakage, jet fire, and explosion. Therefore Safety measures are necessary for this hazard. In addition, risks in semi-closed spaces such as tunnels, underground roads, and underground parking lots should be analyzed. In this study, an explosion experiment was conducted on a hydrogen tank used in a hydrogen vehicle to analyze the risk of a hydrogen vehicle explosion accident that may occur in a semi-closed space. As results, the effect on the structure and the human body was analyzed using the overpressure and impulse values for each distance generated during the explosion.

Tracking Propagation Mechanism on the Surface of Polyvinyl-Chloride-Sheathed Flat Cord based on Electric Field Analysis and Gas Discharge Physics (전계해석과 기체방전 이론을 기반으로 한 Polyvinyl-Chloride-Sheathed Flat Cord 표면의 트래킹 진전 메커니즘)

  • Lim, Dong-Young;Park, Herie;Jee, Seung-Wook
    • Fire Science and Engineering
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    • v.33 no.2
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    • pp.30-38
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    • 2019
  • Tracking, which is one of the main causes of electrical fires, is perceived as a physical phenomenon of electrical discharge. Hence tracking should be explained based on electric field analysis, conduction path by electron generation, and gas discharge physics. However, few papers have considered these details. This paper proposes a tracking mechanism including their effects on tracking progress. In order to prove this mechanism, a tracking experiment, an electric field analysis for the carbonization evolution model, and an explanation of the tracking process by gas discharge physics were conducted. From the tracking experiment, the current waveforms were measured at each stage of the tracking progress from corona discharge to tracking breakdown. The electric field analysis was carried out in order to determine the electric field on the surface of a dry-band and the high electric field region for electron generation during the generation and progress of carbonization. In this paper, the proposed tracking mechanism consisted of six stages including electron avalanche by corona discharge, accumulation of positive ions, expansion of electron avalanche, secondary electron emission avalanche, streamer, and tracking by conductive path. The pulse current waveforms measured in the tracking experiment can be explained by the proposed tracking mechanism. The results of this study will be used as the technical data to detect tracking phenomenon, which is the cause of electric fire, and to improve the proof tracking index.

An Applicability Estimation of Plastic Vertical Pipes using Electric Fusion Fittings through Measurement (실측을 통한 융착식 플라스틱 입상배관 성능 평가)

  • Park, Yool;Ahn, Young-Chull;Kim, Hyun-Dae;Kim, Jeong-Su;Goark, You-Shik;Kim, Young-Kyoung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.11
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    • pp.595-599
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    • 2013
  • The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.

An Experimental Study for the Strength Variations of High-strength Lightweight Concrete According to Grain-size of Artificial Lightweight Aggregate (인공경량골재의 입도에 따른 고강도 경량콘크리트의 강도변화에 대한 실험적 연구)

  • Kim, Sung Chil;Park, Ki Chan;Choi, Hyoung Wook
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.209-217
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    • 2011
  • In recent days, while taller and more massive structures such as huge bridges and super skyscrapers have been welcomed, the structural stabilization in design and construction have been gradually limited due to the major weakness of current concrete which is relatively heavier when compared with its strength. To improve the weakness of the current concrete, The lightweight concrete with light weight and high strength should be used; however, not many researchers in Korea have studied on the lightweight concrete. Generally, artificial lightweight aggregate produced through high-temperature-plasticization has a possibility of its body-expansion with many bubbles. Therefore, depending on the size of aggregate, the effects of bubbles on the specific weight and strength of the lightweight concrete should be studied. In this study, considering grain-size, the mix design of the artificial lightweight aggregate produced through the high-temperature-plasticization and the body-expansion of waste and clay from the fire power plant in Korea was conducted. The experiment to analyze the variation in specific weight and strength of the lightweight concrete was followed. From these experiments, the optimized grain-size ratio of the artificial lightweight aggregate for the enhancement of high-strength from the lightweight concrete was revealed.

Parametric Sensitivity Analysis and Damage Estimation for BLEVE and Fireball (BLEVE와 Fireball의 매개변수 민감도분석 및 피해 산정)

  • Kim Hyung Seok;Kim In Tae;Song Kwang Ho;Ko Jae Wook;Kim In Won
    • Journal of the Korean Institute of Gas
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    • v.2 no.3
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    • pp.25-36
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    • 1998
  • Explosion and fires can occur in all segments of chemical and petroleum industries because of complexity of process, usage and storage of flammable and reactive chemicals, and operating conditions of high pressure and temperatures. Especially chemical plants have high possibility of the occurrence of BLEVE(Boiling Liquid Expanding Vapor Explosion)and Fireball. In this study, a computer program was developed for the effect assessment of BLEVE and Fireball. BLEVE was analysed by three explosion models of physical explosion model, isothermal expansion model and adiabatic expansion model and Fireball using solid model. The parametric sensitivity analysis has been done for the models of BLEVE and Fireball. The damage by BLEVE and Fireball of Benzene and Toluene and m-Xylene were estimated.

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Analysis of DC insulation and properties of epoxy/ceramic composites with nanosized ZnO/TiO2 fillers

  • Kwon, Jung-Hun;Kim, Yu-Min;Kang, Seong-Hwa;Kim, Pyung-Jung;Jung, Jong-Hoon;Lim, Kee-Joe
    • Journal of Ceramic Processing Research
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    • v.13 no.spc2
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    • pp.332-335
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    • 2012
  • A molded transformer is maintenance-free, which makes it unnecessary to replace the insulating material, like in an oil-filled transformer, because the epoxy, which is a molded insulating resin, does not suffer variations in its insulating performance for heat cycles over a long time, as compared to insulating oil. In spite of these advantages, a molded transformer may still be accessed by the user, which is not good in regards to reliability or noise compared to the oil transformers. In particular, a distrust exists regarding reliability due to the long-term insulating performance. These properties have been studied in regards to the improvement of epoxy composites and molded transformer insulation. There have nevertheless been insufficient investigations into the insulation properties of epoxy composites. In this study, it is a researching of the epoxy for insulating material. In order to prepare the specimens, a main resin, a hardener, an accelerator, and a nano/micro filler were used. Varying amounts of TiO2 and ZnO nano fillers were added to the epoxy mixture along with a fixed amount of micro silica. This paper presents the DC insulation breakdown test, thermal expansion coefficient, and thermal conductivity results for the manufactured specimens. From these results, it has been found that the insulating performance of nano/micro epoxy composites is improved as compared to plain molded transformer insulation, and that nano/micro epoxy composites contribute to the reliability and compactness of molded transformers.

Analysis of the Use of Ambulance Services Among Pregnant, Childbearing, and Postpartum Women Using Data from the Korea Health Panel (한국의료패널을 이용한 구급 이송 서비스 이용 특성 분석: 임신, 출산, 산후기 여성을 중심으로)

  • Kang, Kyunghee
    • Fire Science and Engineering
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    • v.33 no.6
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    • pp.152-158
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    • 2019
  • This study examined the socio-economic and clinical characteristics associated with the use of ambulance services among pregnant, childbearing, and postpartum women based on data from the 2008-2016 Korea Health Panel. The analysis revealed that among the pregnant, childbearing, and postpartum women, the proportion using all ambulance services was 18.9% whereas 12.0% used private and 119 ambulances. Moreover, among those using ambulance services, delivery was the most common reason (38.7%) followed by complications of labor and delivery (20.0%) and pregnancy with abortive outcome (17.3%). There were statistically significant differences between the users and non-users of ambulance services in terms of the average annual household income, emergency arrival time, and delayed arrival at the emergency room. As childbirth becomes more complicated due to low fertility and elderly mothers, the expansion and improvement of ambulance services as a social safety net for pregnant, childbearing, and postpartum women will become increasingly important.

Effects of Drag Models on the Hydrodynamics and Heat Transfer in a Conical Fluidized Bed Combustor (원추형 유동층 연소기의 수력학적 특성 및 열전달에 항력 모델이 미치는 영향에 대한 연구)

  • Kang, Seung Mo;Abdelmotalib, Hamada;Ko, Dong Guk;Park, Woe-Chul;Im, Ik-Tae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.11
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    • pp.861-869
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    • 2015
  • In this study, wall to bed heat transfer and hydrodynamic characteristics in a conical fluidized bed combustor was investigated using computational fluid dynamics method. A two-fluid Eulerian-Eulerian model was used with applying the kinetic theory for granular flow(KTGF). The effects of the two drag models, Gidaspow and the Syamlal-O'Brien model, different inlet velocities($1.4U_{mf}{\sim}4U_{mf}$) and different particle sizes on the hydrodynamics and heat transfer were studied. The results showed that the hydrodynamic characteristics such as bed expansion ratio and pressure drop were not affected significantly by the drag models. But the heat transfer coefficient was different for the two drag models, especially at lower gas inlet velocities and small particle sizes.

Failure Analysis of the Rate of Rise Spot Type Heat Detector on Artificially Accelerated Aging (인공 가속열화에 따른 차동식 스포트형 열감지기의 고장 원인분석)

  • Kim, Chan-Young
    • Fire Science and Engineering
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    • v.25 no.4
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    • pp.48-55
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    • 2011
  • This paper presents the failure analysis of the rate of rise spot type heat detectors on artificially accelerated aging. The failures of heat detector turned out by two reasons. The first one is the separation of binder from plastic moulding, resulting in the leakage of air from heat chamber. The second reason is the crack of plastic. The large cracks were maybe created by these reasons, thermal expansion difference, mechanical stress, or growth of microcrack. In the sound detector, the separation and the crack were not occurred or not developed to the critical size. The glass fibers which increase the mechanical strength were added in the binder of detector 2010G. The densities of binder or plastic of each detector were similar. However, the TGA result shows that the thermal characteristics of 2005A and 2005B were not similar.