• Title/Summary/Keyword: Sulfur Hexafluoride ($SF_6$)

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On the Short Term Air Pollution Dispersion Model for the Single Souce -Diffusion Experiment With Tracer Gas- (單一 排出源大氣汚染 短期모델에 관한 硏究 -Tracer Gas에 의한 擴散實驗-)

  • 李鍾範;姜寅求
    • Journal of Korean Society for Atmospheric Environment
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    • v.5 no.2
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    • pp.84-96
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    • 1989
  • To evaluate the short term air pollution dispersion model, the diffusion experiment was conducted on the flat terrain near Chuncheon. Sulfur hexafluoride $(SF_6)$ gas was used to determine the horizontal spread of plume $(\sigmay)$ for calculated by CRSTER model. Results show that CRSTER model underestimates $\sigma$y because averaging time adjustment is not applied to calculate the $\sigma$y. The scheme that can estimate the atmospheric stability more accurate than Turner method, was presented.

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Shape Design of Disk Seal in $SF_6$ Gas Safety Valve using Taguchi method (다구찌법을 이용한 $SF_6$가스 안전밸브용 디스크 시일 형상의 설계)

  • Cho Seunghyun;Kim Chungkyun;Kim Younggyu
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.237-240
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    • 2004
  • Sulfur Hexafluoride, SF6 is widely used for leak detection and as a gaseous dielectric in transformers, condensers and circuit breakers. SF6 gas is also effective as a cleanser in the semiconductor industry. This paper presents a numerical study of the sealing force of disk type seal in SF6 gas safety valve. The sealing force on the disk seal is analyzed by the FEM method based on the Taguch's experimental design technique. Disk seals in SF6 gas safety valve are designed with 9 design models based on 3 different contact length, compressive ratio and gas pressure. The calculated results of Cauchy stress and strain showed that the sealing characteristics of Teflon PTFE is more effective compared to that of FKM(Viton), which is related to the stiffness of the materials. And also, the contact length of the disk seal is important design parameter for sealing the SF6 gas leakage in the safety valve.

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Field Gas-Sparging Tests for In Situ Aerobic Cometabolism of Trichloroethylene(TCE)

  • Kim Young;Istok Jonathan D.;Semprini Lewis;Oa Sung-Wook
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2006.04a
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    • pp.54-56
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    • 2006
  • Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

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Morphological study of $SF_6$ clathrate hydrate crystal ($SF_6$ 하이드레이트 결정 성장의 특성)

  • Lee, Yoon-Seok;Lee, Hyun-Ju;Lee, Eun-Kyung;Kim, Soo-Min;Lee, Ju-Dong;Kim, Yang-Do
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.06a
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    • pp.711-711
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    • 2009
  • Global warming has been widely recognized as a serious problem threatening the future of human beings. It is caused by the buildup in the atmosphere of greenhouse gases, such as carbon dioxide, methane, hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6). Particularly, SF6 has extremely high global warming potential compare to those of other global warming gases. One option for mitigating this greenhouse gas is the development of an effective process for capturing and separating these gases from anthropogenic sources. In general, gas hydrates can be formed under high pressure and low temperature. However, SF6 gas is known to form hydrate under relatively milder conditions. Therefore, technological and economical effects could be expected for the separation of SF6 gas from waste gas mixtures. In this study, we carried out morphological study for the SF6 hydrate crystals to understand its formation and growth mechanisms. The observations were made in high-pressure optical cell charged with liquid water and SF6 gas at constant pressure and temperature. Initially SF6 hydrate formed at the surface between gas and liquid regions, and then subsequent dendrite crystals grew at the wall above the gas/water interface. The visual observations of crystal nucleation, migration, growth and interference were reported. The detailed growth characteristics of SF6 hydrate crystals were discussed in this study.

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