• Title/Summary/Keyword: cryogenic temperatures

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Modeling of Thermodynamic Properties of Saturated state Hydrogen using Equation of State (상태방정식을 이용한 포화상태 수소의 열역학적 물성 모델링)

  • Bong-Seop Lee;Hun Yong Shin;Choong Hee Joe
    • Korean Chemical Engineering Research
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    • v.61 no.4
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    • pp.550-554
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    • 2023
  • Fossil energy sources are limited in their sustainable use and expansion due to global warming caused by carbon dioxide emissions. Hydrogen is considered as a promising alternative to traditional fossil fuels. To ensure the stable long-term storage, it is necessary to accurately predict its thermodynamic properties at cryogenic temperatures. Therefore, this study aimed to investigate thermodynamic properties, such as saturated vapor pressure and density, enthalpy, and entropy of liquid and gas, using cubic equations of state that demonstrate relatively simple relationships. Among the three types of equations of state (Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), and Peng-Robinson (PR)), the SRK model exhibited relatively accurate prediction results for various physical properties.

Non-linear tensile behavior of high manganese steel based on elasto-plastic damage model (탄-소성 손상모델을 활용한 고망간강의 인장거동 모사에 관한 연구)

  • Kim, Jong-Hwan;Lee, Jeong-Ho;Kim, Seul-Kee;Chun, Min-Sung;Lee, Jae-Myung
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.3
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    • pp.222-229
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    • 2017
  • High manganese steel exhibits excellent mechanical properties with respect to strength and durability at low temperatures. Recently, high manganese steel has been considered as an alternative to existing materials, such as nickel steel and SUS304L for application as tank material for Liquefied Natural Gas (LNG) cargo containment systems. In the present study, tensile tests were performed at room and cryogenic temperatures in order to investigate the mechanical properties and non-linear tensile behavior of high manganese steel. In addition, elasto-plastic damage model was applied using the finite element analysis software ABAQUS via a user defined material subroutine (UMAT) to describe the material behavior. Finally, the results of the finite element simulations using the UMAT were compared to those of the tensile tests in order to validate the proposed UMAT. It has been demonstrated that the UMAT can effectively describe the non-linear tensile behavior of high manganese steel.

DEVELOPMENT OF CCD IMAGING SYSTEM USING THERMOELECTRIC COOLING METHOD (열전 냉각방식을 이용한 극미광 영상장비 개발)

  • Park, Young-Sik;Lee, Chung-Woo;Jin, Ho;Han, Won-Yong;Nam, Uk-Won;Lee, Yong-Sam
    • Journal of Astronomy and Space Sciences
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    • v.17 no.1
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    • pp.53-66
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    • 2000
  • We developed low light CCD imaging system using thermoelectric cooling method collaboration with a company to design a commercial model. It consists of Kodak KAF-0401E(768$\times$512 pixels) CCD chip, thermoelectric module manufactured by Thermotek. This TEC system can reach an operative temperature of $-25^{\circ}C$. We employed an Uniblitz VS25s shutter and it has capability a minimum exposure time 80ms. The system components are an interface card using a Korea Astronomy Observatory (hereafter KAO) ISA bus controller, image acquisition with AD9816 chip, that is 12bit video processor. The performance test with this imaging system showed good operation within the initial specification of our design. It shows a dark current less than 0.4e-/pixel/sec at a temperature of $-10^{\circ}C$, a linearity 99.9$\pm$0.1%, gain 4.24e-/adu, and system noise is 25.3e-(rms). For low temperature CCD operation, we designed a TEC, which uses a one-stage peltier module and forced air heat exchanger. This TEC imaging system enables accurate photometry($\pm$0.01mag) even though the CCD is not at 'conventional' cryogenic temperatures(140k). The system can be a useful instrument for any other imaging applications. Finally, with this system, we obtained several images of astronomical objects for system performance tests.

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A study of feasibility of using compressed wood for LNG cargo containment system (압축목재를 사용한 LNG 화물창 단열시스템의 적합성 평가에 관한 연구)

  • Kim, Jong-Hwan;Ryu, Dong-Man;Park, Seong-Bo;Noh, Byeong-Jae;Lee, Jae-Myung
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.4
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    • pp.307-313
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    • 2016
  • When liquefied natural gas (LNG) is stored in a tank, it is necessary to maintain low temperature. It is very important that insulation techniques are applied to the LNG cargo because of this extreme environment. Hence, laminated wood, especially plywood, is widely used as the structural member and insulation material in LNG cargo containment systems (CCS). However, fracture of plywood has been reported recently, owing to sloshing effect. Therefore, it is necessary to increase the strength of the structural member for solving the problem. In this study, compressed wood, which is used as a support in LNG independent type B tanks, was considered as a substitute for plywood. Compression and bending tests were performed on compressed wood under ambient and cryogenic temperatures to estimate the mechanical behaviors and fracture characteristics. In addition, the direction normal to the laminates surface was considered as an experimental variable. Finally, the feasibility of using compressed wood for an LNG CCS was evaluated from the test results.

Investigation of ground condition charges due to cryogenic conditions in an underground LNG storage plant (지하 LNG 저장 시험장에서 극저온 환경에 의한 지반상태 변화의 규명)

  • Yi Myeong-Jong;Kim Jung-Ho;Park Sam-Gyu;Son Jeong-Sul
    • Geophysics and Geophysical Exploration
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    • v.8 no.1
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    • pp.67-72
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    • 2005
  • To investigate the feasibility of a new concept of storing Liquefied Natural Gas (LNG) in a lined hard rock cavern, and to develop essential technologies for constructing underground LNG storage facilities, a small pilot plant storing liquid nitrogen (LN2) has been constructed at the Korea Institute of Geoscience and Mineral Resources (KIGAM). The LN2 stored in the cavern will subject the host rock around the cavern to very low temperatures, which is expected to cause the development of an ice ring and the change of ground condition around the storage cavern. To investigate and monitor changes in ground conditions at this pilot plant site, geophysical, hydrogeological, and rock mechanical investigations were carried out. In particular, geophysical methods including borehole radar and three-dimensional (3D) resistivity surveys were used to identify and monitor the development of an ice ring, and other possible changes in ground conditions resulting from the very low temperature of LN2 in the storage tank. We acquired 3D resistivity data before and after storing the LN2, and the results were compared. From the 3D images obtained during the three phases of the resistivity monitoring survey, we delineated zones of distinct resistivity changes that are closely related to the storage of LN2. In these results, we observed a decrease in resistivity at the eastern part of the storage cavern. Comparing the hydrogeological data and Joint patterns around the storage cavern, we interpret this change in resistivity to result from changes in the groundwater flow pattern. Freezing of the host rock by the very low temperature of LN2 causes a drastic change in the hydrogeological conditions and groundwater flow patterns in this pilot plant.