• Title, Summary, Keyword: cryogenic

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LIQUID FLOW AND EVAPORATION SIMULATION OF CRYOGENIC FLUID IN THE WALL OF CRYOGENIC FLUID CARGO CONTAINMENT SYSTEM (극저온 유체 화물창 방벽 내의 액체유동 및 기화 시뮬레이션)

  • Park, Bum-Jin;Lee, Hee-Bum;Rhee, Shin-Hyung;Bae, Jun-Hong;Lee, Kyung-Won;Jeong, Wang-Jo;An, Sang-Jun
    • Journal of computational fluids engineering
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    • v.14 no.2
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    • pp.9-18
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    • 2009
  • The cargo containment system (CCS) for ships carrying cryogenic fluid consists of at least two levels of barriers and insulation layers. It is because, even though there is a small amount of leak through the primary barrier, the liquid tight secondary barrier blocks further leakage of the cryogenic fluid. However, once the secondary barrier is damaged, it is highly possible that the leaked cryogenic fluid flows through the flat joint made of glass wool and reaches the inner hull of the ship. The primary objective of the present study is to investigate the influence of the damage extent in the secondary barrier on the amount of leaked cryogenic fluid reaching the inner hull and the temperature distribution there. Simulation results using a computational fluid dynamics tool were compared with the experimental data for the leaked cryogenic fluid flow and evaporation in the secondary insulation layer. The experimental and computational results suggest that, unless there is a massive leak, the cryogenic fluid mostly evaporates in the insulation layer and does not reach the inner hull in the state of liquid.

Micronization of Ibuprofen by Cryogenic Ball Milling (극저온 볼 밀링을 통한 Ibuprofen 분말의 마이크로화)

  • 조현갑;이경엽;백영남;박훈재;이상목
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.11
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    • pp.195-199
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    • 2004
  • For the present study, the cryogenic ball milling process was applied to make Ibuprofen microsized. The cryogenic ball milling was performed at low temperature of about -18$0^{\circ}C$ for 6 hours. The particle size distribution was determined before and after the cryogenic process. X-ray diffraction (XRD) measurement was made to determine the effect of cryogenic process on the crystallinity of Ibuprofen. The results showed that the size of Ibuproffn was reduced about 10 times by the cryogenic process. The degree of crystallinity of Ibuproffn was slightly reduced by the cryogenic process.

A Study on the Structural Analysis of Cryogenic Submerged Pump (극저온용 액중펌프 구조해석에 관한 연구)

  • Chin, Do-Hun;Yi, Chung-Seob
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.5
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    • pp.727-733
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    • 2020
  • Recently, reciprocating cryogenic pumps are mainly developed for small-and-mid sized fuel supply systems. Centrifugal type pumps are not actively developed. Most cryogenic submerged pumps are imported. For transportation, cryogenic liquefied natural gas requires the liquid pump technology that can works in extreme evironments. In order to transport liquefied natural gas, it is necessary to apply pump technology. This is the fundamental research for developing the submerged pump technology applicable to the transportation and storage system equipment of cryogenic liquefied system. It tries to secure basic design materials through reverse-engineering in the cryogenic submerged pump development. Regarding materials, STS-304 and STS-431 which are stainless materials widely used in the cryogenic area are applied. Aluminum alloy is applied to impeller and upper manifolder and the pump rotates at the high speed of 6,000rpm.

A new method fast measure cryogenic vessel heat leakage

  • LI, Zheng-Qing;LI, Xiao-Jin;LIU, Mo
    • Progress in Superconductivity and Cryogenics
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    • v.22 no.1
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    • pp.24-28
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    • 2020
  • Heat leakage is an important parameter to reflect heat insulated performance of cryogenic vessel. According to the current standard requirements, it needs to measure the daily evaporation rate to indicate heat leakage. The test needs-over 24h after cryogenic vessel in heat equilibrium as standard required, therefore test efficiency is poor and new efficient method is required to cut test time. First of all, the volume of instantaneous evaporated gas and heat leakage are calculated by the current standard corresponding to the maximum allowable daily evaporation rate of cryogenic vessel. Depending on the relationship between real daily evaporation rate and maximum allowable daily evaporation rate of cryogenic vessel, we designed a new test method based on the pressure changes over time in cryogenic vessel to determine whether its heat insulated performance meets requirements or not. Secondly, the heat transfer process was analyzed in measurement of cryogenic vessel, and the heat transfer equations of whole system were established. Finally, the test was completed in four hours; meanwhile the heat leakage and daily evaporation rate of cryogenic vessel are calculated basing on test data.

Effect of Packing Materials of Frozen Boar Semen on Sperm Characteristics and Reproductive Performance (동결정액 포장방법이 돼지정액의 성상 및 번식성적에 미치는 영향)

  • 김인철;이장희;김현종;이성호;박창식
    • Korean Journal of Animal Reproduction
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    • v.26 no.2
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    • pp.119-124
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    • 2002
  • This study was carried out to investigate the effects of packing materials of frozen boar semen to improve reproductive performance efficiency in pig. Boars were raised at Swine Artificial Insemination Center in National Livestock Research Institute, Sunghwan, Chungnam, Korea. We compared packing protocols for frozen boar semen among 5$m\ell$ maxi-straw, 5$m\ell$ cryogenic-vial, and aluminum-pack. Cryogenic-vial packing material showed similar sperm characteristics compared with maxi-straw packing material when the sperm was frozen above 15cm from liquid nitrogen and thawed at 52$^{\circ}C$ for 190 seconds. We investigated different thawing times to find out the optimal condition of freezing and thawing protocol with cryogenic-vial. Freezing above 15cm from liquid nitrogen and thawing at 52$^{\circ}C$ for 190 seconds were the optimal protocol compared with 120 and 150 seconds. However, normal acrosome rates did not show any differences among thawing times. Post-thawing results of maxi-straw in water at 52$^{\circ}C$ for 45 seconds had better total motility and curve linear velocity than those of cryogenic-vial in water 52$^{\circ}C$ for 190 seconds. However, there were no differences on straightness and normal apical ridge of sperm between maxi-straw and cryogenic vial. Non-return rate, farrowing rate and litter size of sows inseminated with frozen boar semen of commercial farms were higher in the maxi-straw than cryogenic-vial, but there were no significant differences between maxi-straw and cryogenic-vial. In conclusion, there were no significant differences between maxi-straw and cryogenic-vial and so, we may replace cryogenic-vial packing method instead of maxi-straw packing method by improvement of freezing and thawing rate.

Nanocrystallization of Ibuprofen by Cryogenic Ball Milling II (극저온 볼 밀링을 통한 Ibuprofen 분말의 나노화II)

  • 조현갑;이경엽;백영남;박훈재;이상목
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.442-446
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    • 2004
  • Reducing the particle size of drug materials down to submicron is an important matter in pharmaceutical industry. Cryogenic milling technology is one of the mechanical milling processes, which is mostly utilized in refining grain size of metal and ceramics at extremely low temperature environment. This technique has not been readily studied in application to medical and biotechnology. This paper, therefore, describes the application of cryogenic milling process to reduce particle size of Ibuprofen. The shape and size of the Ibuprofen particle before and after the cryogenic ball milling process were analyzed. XRD analysis was performed to examine a change in crystallinity of Ibuprofen by the cryogenic ball milling process. The results showed that the size of Ibuprofen particles was reduced to 1/10 or less of its initial size. The results also showed that the degree of crystallinity of Ibuprofen was slightly reduced after cryogenic ball milling with nitrogen

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Thermal stress and Flow Analysis of a Cryogenic Ball Valve (초저온 볼밸브의 열 응력 및 유동해석)

  • Bae, S.K.;Lee, W.H.;Kim, H.S.;Kim, D.S.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.4
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    • pp.8-13
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    • 2006
  • The high pressure cryogenic ball valve is used to transfer the liquefied natural gas which temperature is $-196^{\circ}C$, supplied pressure is $168kgf/cm^2$. In the present work, the temperature distribution and thermal deformation is calculated numerically. The CAR and CFD methods are useful to predict the thermal matter and the inner flow field of high pressure cryogenic ball valve. For this reason, to optimum design of the cryogenic ball valve, the theological behavior of the supplied LNG in a cryogenic valve has been studied. The governing equations are discredited and solved numerically by the finite-volume method and finite-element method. In this study, we designed the high pressure cryogenic ball valve that accomplishes zero leakage by elastic seal at normal temperature and metal seal at high temperature.

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