• Title/Summary/Keyword: Hydrogen jet

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Characteristics of NOx Emission in a Swirl Flow in Nonpremixed Turbulent Hydrogen Jet with Coaxial Air (수소 난류 확산화염에서의 선회류에 의한 배기배출물 특성)

  • Oh, Jeong-Seog;Yoon, Young-Bin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.3
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    • pp.275-282
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    • 2010
  • The effect of swirl flow on NOx in a nonpremixed turbulent hydrogen jet with coaxial air was studied. The swirl vane angle was varied from $30^{\circ}$ to $90^{\circ}$. The fuel jet air velocity and coaxial air velocity were varied in an attached flame region as $u_F=85{\sim}160m/s$ and $u_A=7{\sim}14m/s$. The objective of the current study was to analyze the characteristics of nitrous oxide emission in a swirl flow and to propose a new parameter for EINOx scaling. The experimental results show that EINOx decreases with the swirl vane angle and increased with flame length. Further, EINOx scaling factors can be determined by considering the effective diameter ($d_{F,eff}$) in a far field concept. The EINOx increased in proportion to the flame residence time (${\sim}{\tau_R}^{1/2.8}$) and the global strain rate (${\sim}{S_G}^{1/2.8}$).

Development of Accident Scenarios for Hydrogen Refueling Station and Fuel Cell Vehicle (수소충전소 및 수소자동차의 사고 시나리오 개발)

  • Byoungjik Park;Yangkyun Kim;Ohk Kun Lim
    • Journal of Auto-vehicle Safety Association
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    • v.15 no.1
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    • pp.27-34
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    • 2023
  • The registration rate of eco-friendly vehicles, such as hydrogen vehicles, is increasing rapidly, however, few first responders have experienced related accidents. Accident scenarios at hydrogen refueling stations and hydrogen vehicles on a road were investigated, and the relative importance of each scenario was analyzed using AHP analysis. Leakage, jet flame, and explosion that occurred inside and outside the hydrogen refueling station were reviewed, and the hydrogen gas explosion in the compartment showed the highest importance value. In case of the hydrogen vehicle, traffic accident statistics and actual accidents were used. It was analyzed that the hydrogen vessel explosion on the road due to the failure of TPRD and the leakage in the underground parking area were difficult to respond. The developed accident scenarios are expected to be used for first responder training.

The Effect of Flame Radiation on NOx Emission Characteristics in Hydrogen Thrbulent Diffusion Flames (수소 난류확산화염에서 NOx 생성특성에 대한 화염열복사의 영향)

  • Kim, Seung-Han;Kim, Mun-Ki;Yoon, Young-Bin
    • Journal of the Korean Society of Combustion
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    • v.5 no.2
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    • pp.51-62
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    • 2000
  • The relationship among the flame radiation, NOx emissions, residence time, and global strain rate are examined for turbulent non-premixed jet flames with wide variations in coaxial air conditions. Measurements of NOx emission, flame geometry and flame radiation were made to explain the NOx emission scaling based on global parameters such as flame residence time, global strain rate, and radiant fraction. The overall 1/2-power scaling is observed in coaxial air flames, irrespective of coaxial air conditions, but the degree of deviation from the 1/2-slope curve in each case differs from one another. From the comparison between the results of pure hydrogen flames and those of helium diluted hydrogen flames, it is observed that flame radiation plays a significant role in pure hydrogen flames with coaxial air and the deviation from 1/2-power scaling may be explained in two reasons: the difference in the flame radiation and the difference in jet similarity in coaxial air flames. From the radiation measurements, more detailed explanations on these deviations were suggested.

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Hydrogneation and Electrochemical Characteristics of Gas-atomized Zr-based $AB_2$ Hydride for Ni-MH Secondary Battery (기체분무형 공정으로 제조된 Zr계 금속수소화물의 수소화반응 및 Ni-MH 2차전지 전극 특성에 관한 연구)

  • Kim, Jin-Ho;Hwang, Kwang-Taek;Kim, Byung-Kwan;Han, Jeong-Seb
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.6
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    • pp.505-511
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    • 2009
  • The hydriding and electrochemical characteristics of Zr-based $AB_2$ alloy produced by gas atomization have been extensively examined. For the particle morphology of the as-cast and gas-atomized powders, it can be seen that the mechanically crushed powders are irregular, while the atomized powder particles are spherical. The increase of jet pressure of gas atomization process results in the decrease of hydrogen storage capacity and the slope of plateau pressure significantly increases. TEM and EDS studies showed the increase of jet pressure in the atomization process accelerated the phase separation within grain of the gas-atomized alloy, which brought about a poor hydrogenation property. However, the gas-atomized $AB_2$ alloy powders produced by jet pressure of 50 bar kept up the reversible $H_2$ storage capacity and discharge capacity similar to the mechanically crushed particles. In addition, the electrode of gas-atomized Zr-based $AB_2$ alloy of 50 bar showed improved cyclic stability over that of the cast and crushed particulate, which is attributed to the restriction of crack propagation by grain boundary and dislocation with ch/discharging cycling.

Nitrogen Dilution Effects on Liftoff Flame Stability in Non-premixed Turbulent Hydrogen Jet with Coaxial Air (질소희석이 부상된 수소 난류확산화염의 화염안정성에 미치는 영향)

  • Oh, Jeong-Seog;Yoon, Young-Bin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.393-396
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    • 2008
  • The study of nitrogen dilution effect on flame stability was experimentally investigated in non-premixed turbulent lifted hydrogen jet with coaxial air. hydrogen gas was used as a fuel and coaxial air was injected to make flame liftoff. And both of the fuel jet and coaxial air velocity were fixed as $u_F$=200 m/s and $u_A$=16 m/s, while nitrogen diluents mole fraction was varied from 0 to 0.2. For the analysis of flame structure and flame stabilization mechanism, the simultaneous measurement of PIV/OH PLIF had been performed. It was found that the turbulent flame propagation velocity increased as decreasing of nitrogen mole fraction. We concluded that the turbulent flame propagation velocity was expressed as a function of turbulent intensity, even though the mole fraction of nitrogen diluents gas was changed.

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PROCESS OPTIMIZATION OF METHANE REFORMING IN ARC JET (아크젯 플라즈마에서의 메탄개질의 최적화)

  • Hwang, Na-Kyung;Lee, Dae-Hoon;Song, Young-Hoon
    • 한국연소학회:학술대회논문집
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    • 2006.10a
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    • pp.266-271
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    • 2006
  • Characteristic of partial oxidation of methane using arc-jet plasma by AC power is investigated. Arc-jet reactor used in this work is slightly modified from typical arc jet reactor so that it can make and sustain stable state of plasma. Methane conversion, selectivity of chemicals such as hydrogen and hydrocarbon materials in the product are analyzed. Parametric approach on the performance of the reactor or detail on the partial oxidation process is carried with $O_2/C$ ratio as parameter. In addition to the results, SED and arc length is changed to understand the effect of current-voltage correlation on the reforming performance and relative role of thermal process.

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The Experimental Research On The Electrical Characteristics For The Ignition Of Plasma Jet Using The Advance Discharge Of High Frequency Voltage With Attenuation (감쇠파 고주파전압의 선행방전을 이용한 Plasma jet의 전기적 기동특성에 대한 실험적 연구)

  • Choon Saing Jhoun
    • 전기의세계
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    • v.21 no.4
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    • pp.27-38
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    • 1972
  • This paper discusses the characteristics about the ignition of D.C. main discharge is a plasma jet generator, manufactured for trial as non-transferred type, when the electrical energy appropriate to the ignition is supplied to the gap between the electrodes by using advance discharge of attenuating high frequency voltage generated by a high frequency oscillator with mercury spark gap. These characteristics are under the influences of (a) the length of mercury gap in high frequency oscillator and the quantity of hydrogen flow supplied to it, (b) the condenser capacity of the high frequency oscillator circuit, (c) the length of plasma jet torch in D.C. main discharge circuit and the quantity of argon flow supplied to it, (d) the circuit constants of D.C. main discharge circuit. The results for these characteristics, obtained by this research, are considered to be helpful to the designs for the ignition of a plasma jet as well as the welding arc stabilizer by high frequency discharge and the high frequency arc welder.

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Review : The Advanced Inkjet Printing Technology - UV curable Jet Ink - (총설 : 최신 잉크제트 인쇄기술 - UV 경화형 제트잉크 -)

  • Jeong, Kyoung Mo;Won, Jong Myung;Lee, Yong Kyu;Koseki, Ken'ichi
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.46 no.2
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    • pp.46-56
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    • 2014
  • The aim of this reviews is to introduce the information concerning design of the UV-curable jet ink composition in order to provide a good adhesive property on non-porous surface. In order to clarify the viscosity dependence of flying speed for the UV curable jet ink, rheological analysis and observation of the flying state of the ink were carried out. The relationship between ink formulas and adhesive property on non-porous surface was investigated. It was examined the adhesive property of radical polymerization type UV curable jet ink included hydrogen abstraction type photo-initiator, it was expected that the strong adhesive strength can be obtained between the ink and non-porous surface in this study. UV curable jet ink with a slight amount of water was prepared. Optimum ratio of the cationic polymerization type UV curable jet ink shows an adequate adhesive strength towards two kinds of non-porous surface such as glass, poly(vinyl chloride) when tests were conducted on the ink jet-printing test machine.

Stability of Attached Flame in $H_2$/CO Syngas Non-premixed Turbulent Jet Flame ($H_2$/CO 합성가스 비예혼합 난류 제트화염에서 부착화염의 화염안정화)

  • Hwang, Jeong-Jae;Bouvet, Nicolas;Sohn, Ki-Tae;Yoon, Young-Bin
    • Journal of the Korean Society of Combustion
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    • v.17 no.1
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    • pp.22-29
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    • 2012
  • The detachment stability characteristics of syngas $H_2$/CO jet attached flames were studied. The flame stability was observed while varying the syngas fuel composition, coaxial nozzle diameter and fuel nozzle rim thickness. The detachment stability limit of the syngas single jet flame was found to decrease with increasing mole fraction of carbon monoxide in the fuel. In hydrogen jet flames with coaxial air, the flame detachment stability was found to be independent of the coaxial nozzle diameter. However, velocities of appearance of liftoff and blowout velocities of lifted flames have dependence. At lower fuel velocity range, the critical coaxial air velocity leading to flame detachment increases with increasing fuel jet velocity, whereas at higher fuel velocity range, it decreases. This increasing-decreasing non-monotonic trend appears for all $H_2$/CO syngas compositions (50/50~100/0% $H_2$/CO). To qualitatively understand the flame behavior near the nozzle rim, $OH^*$ chemiluminescence imaging was performed near the detachment limit conditions. For all fuel compositions, local extinction on the rim is observed at lower fuel velocities(increasing stability region), while local flame extinction downstream of the rim is observed at higher fuel velocities(decreasing stability region). Maximum values of the non-monotonic trends appear to be identical when the fuel jet velocity is normalized by the critical fuel velocity obtained in the single jet cases.

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.