• 제목/요약/키워드: GM cryocooler

검색결과 31건 처리시간 0.027초

물질분리를 위한 전도냉각형 초전도자석 시스템 개발 (Development of a Conduction-Cooled Superconducting Magnet System for Material Separation)

  • 최연석;김동락;이병섭;양형석;정원묵
    • Progress in Superconductivity
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    • 제10권1호
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    • pp.50-54
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    • 2008
  • A conduction-cooled superconducting magnet system is developed for material separation. The superconducting magnet for material separation has to be designed to have a strong magnetic field in a control volume. Since the magnetic field gradient is larger at the end rather than at the center of the magnet, we developed a design method to optimize the superconducting magnet for material separation. The safety of the superconducting magnet is evaluated, taking into account the electro-magnetic field, heat and structure. The superconducting coil is successfully wound by the wet-winding method. The superconducting coil is installed in a cryostat maintaining high vacuum, and cooled down to approximately 4 K by a two-stage GM cryocooler. The performance of the conduction-cooled superconducting magnet system is discussed with respect to the supplied current, cooling medium and cooling power of a cryocooler.

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600kJ급 SMES용 전도냉각시스템 열해석 (Thermal analysis of the conduction cooling system for HTS SMES system of 600 kJ class)

  • 홍용주;염한길;박성제;김효봉;고득용
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.1959-1963
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    • 2007
  • SMES systems need cryogenic cooling systems. Conduction cooling system has more effective, compact structure than cryogen. In general, 2 stage GM cryocoolers are used for conduction cooling of HTS SMES system. 1st stages of cryocoolers are used for the cooling of current leads and radiation shields, and 2nd stages of cryocoolers for HTS coil. For the effective conduction cooling of the HTS SMES system, the temperature difference between the cryocooler and HTS coil should be minimized. In this paper, a cryogenic conduction cooling system for HTS SMES is analyzed to evaluate the performance of the cooling system. The analysis is carried out for the steady state with the heat generation of the HTS coil and effects of the thermal contact resistance. The results show the effects of the heat generation and thermal contact resistance on the temperature distribution.

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고체 질소를 이용한 극저온 냉동의 해석 및 실험 (Analysis and Experiment on Cryogenic Refrigeration Using Solid Nitrogen)

  • 변정주;이윤숙;장호명
    • 한국초전도ㆍ저온공학회논문지
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    • 제3권2호
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    • pp.77-83
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    • 2001
  • The thermal characteristics of solid nitrogen are investigated by experiment and analysis for the purpose of evaluating its feasibility as a cooling medium for HTS (high T$_{c}$ superconductor) magnets. A cryostat to refrigerate a liquid-nitrogen container well below its freezing temperature with a 2-stage GM cryocooler is designed and constructed. The spatial distribution of temperature is measure as a function of time during the freezing and melting processes. from which the thermal diffusivity of solid nitrogen can be approximately calculated. the freezing process is formulated and solved by the integral method with an assumption of phase equilibrium at the solid-liquid interface and experimental observation. It may be concluded that the thermal diffusion in solid phase is much slower than in liquid and the degree of super-saturation is quite severe in the solidification of nitrogen.n.

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전도냉각에 의한 1.2 KV/80 A급 유도형 고온초전도 한류기의 설계, 제작 및 테스트에 관한 연구 (A Study on Design, Fabrication Techniques and Test Results of 1.2kV 180A Inductive Superconducting Fault Current Limiter by Conduction-Cooled System)

  • 강형구;전우용;이승제;안민철;배덕권;윤용수;고태국
    • 한국초전도ㆍ저온공학회논문지
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    • 제5권2호
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    • pp.30-35
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    • 2003
  • The inductive superconducting fault current limiter (SFCLJ limits the fault current with its dc reactor. To fabricate the optimal dc reactor for inductive SFCL, several design and manufacturing technologies are necessary. In this paper, the manufacturing technology for dc reactor and cryogenic cooling method are described in detail. GM-cryocooler was used enlarge the critical current of dc reactor by cooling down the temperature of dc reactor about 20 K. Moreover, the results of short circuit test were described. Finally, the thermal characteristics of conduction-cooled system were discussed and then, sub-cooled nitrogen system was proposed to enhance the thermal stability of dc reactor.

소형 GM 냉동기를 이용한 수소 액화에 관한 시뮬레이션 연구 (A Simulation Study on the Hydrogen Liquefaction through Compact GM Refrigerator)

  • 정하늘;한단비;양원균;백영순
    • 한국수소및신에너지학회논문집
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    • 제33권5호
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    • pp.534-540
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    • 2022
  • Liquid hydrogen has the best storage capacity per unit mass and is economical among storage methods for using hydrogen as fuel. As the demand for hydrogen increases, the need to develop a storage and supply system of liquid hydrogen is emphasizing. In order to liquefy hydrogen, it is necessary to pre-cool it to a maximum inversion temperature of -253℃. The Gifford-McMahon (GM) refrigerator is the most reliable and commercialized refrigerator among small-capacity cryogenic refrigerators, which can extract high-efficiency hydrogen through liquefied hydrogen production and boil of gas re-liquefaction. Therefore, in this study, the optimal conditions for liquefying gas hydrogen were sought using the GM cryocooler. The process was simulated by PRO/II under various cooling capacities of the GM refrigerator. In addition, the flow rate of hydrogen was calculated by comparing with specific refrigerator capacity depending on the pressure and flow rate of a refrigerant medium, helium. Simulations were performed to investigate the optimal values of the liquefaction flow rate and compression pressure, which aim for the peak refrigeration effect. Based on this, a liquefaction system can be selected in consideration of the cycle configuration and the performance of the refrigerator.

전도냉각형 HTS 자석의 전류도입부에서의 열적 퀜치 (Thermal Quench at Current Terminals of the Conduction-Cooled HTS Magnet)

  • 배준한;배덕권;박해용;손명환;성기철
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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    • pp.358-359
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    • 2008
  • The heat generated in the high-Tc superconducting (HTS) devices is related with the cost efficiency and safe factor of HTS devices. This paper deals with the quench at the conduction-cooled joint between the HTS wire and copper terminals. The 3-D numerical simulation of this phenomenon was implemented and compared with the experimental results. The experiment was implemented with the HTS wire mounted on the copper blocks cooled with a Gifford McMahon (GM) cryocooler.

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6.6kV/200A급 유도형 한류기용 과냉질소 냉각시스템의 특성 (Characteristic of sub-cooled nitrogen cryogenic system for 6.6kV/200A Inductive Superconducting Fault Current Limiter)

  • 박동근;강형구;윤경용;주민석;김태중;고태국
    • 한국초전도저온공학회:학술대회논문집
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    • 한국초전도저온공학회 2003년도 추계학술대회 논문집
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    • pp.234-236
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    • 2003
  • The cryogenic system for inductive superconducting fault current limiter (SFCL) has been investigated recently. In this investigation, the sub-cooled nitrogen cryogenic system was adopted to enhance the performance of DC reactor for 6.6㎸/200A inductive SFCL. In sub-cooled nitrogen state at 64K, the critical current value and the thermal conductivity are larger than those of saturated nitrogen state at 77K and the electrical insulation capacitance should be remarkably enhanced. The solenoid type of 84mH superconducting DC reactor was fabricated and cooled down to 64K by using sub-cooled cooling method with GM-cryocooler and rotary pump. The fabrication techniques of cryogenic system and some experimental results such as cooling down characteristic are introduced in this study. Moreover, the sub-cooled nitrogen cryogenic system was detailedly introduced in this paper.

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Estimation of surface emissivity for conduction-cooled metal plates at cryogenic temperatures

  • Chang, Ho-Myung;Lee, Gyong-Hyon
    • 한국초전도ㆍ저온공학회논문지
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    • 제10권2호
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    • pp.38-41
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    • 2008
  • The relation between surface emissivity and temperature distribution is experimentally and analytically investigated for a conduction-cooled metal plate in vacuum. Experimental set-up consists of a rectangular metal plate placed vertically in a cryostat and thermally anchored to the coldhead of a GM cryocooler at the top. Temperature is measured at a number of locations over the plate with platinum resistors mounted on the plate. A parallel analysis on the balance of heat conduction through the plate and thermal radiation on its surface is performed to numerically calculate the temperature distribution having the same boundary conditions as experiment. By comparing the two results, an average emissivity of the plate is roughly estimated for different metal plates and different surface conditions. The estimated emissivity in present study is less than the listed values for highly polished stainless steel, and meets a fairly good agreement for oxidized copper surface.

Development of large bore superconducting magnet for wastewater treatment application

  • Liu, Huiming;Xu, Dong;Shen, Fuzhi;Zhang, Hengcheng;Li, Laifeng
    • 한국초전도ㆍ저온공학회논문지
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    • 제19권1호
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    • pp.13-16
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    • 2017
  • Water issue, especially water pollution, is a serious issue of 21st century. Being an significant technique for securing water resources, superconducting magnetic separation wastewater system was indispensable. A large bore conduction-cooled magnet was custom-tailored for wastewater treatment. The superconducting magnet has been designed, fabricated and tested. The superconducting magnet was composed of NbTi solenoid coils with an effective horizontal warm bore of 400 mm and a maximum central field of 2.56T. The superconducting magnet system was cooled by a two-stage 1.5W 4K GM cryocooler. The NbTi solenoid coils were wound around an aluminum former that is thermally connected to the second stage cold head of the cryocooler through a conductive copper link. The temperature distribution along the conductive link was measured during the cool-down process as well as at steady state. The magnet was cooled down to 4.8K in approximately 65 hours. The test of the magnetic field and quench analysis has been performed to verify the safe operation for the magnet system. Experimental results show that the superconducting magnet reached the designed magnetic performance.

Design and Fabrication of 1 MVA Single Phase HTS Transformer for Power Distribution with Natural Convection Cooling System

  • Kim, W. S.;Kim, S. H.;Park, K. D.;H. G. Joo;G. W. Hong;J. H. Han;Park, J. H.;H. S. Son;S. Y. Hahn
    • Progress in Superconductivity
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    • 제5권2호
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    • pp.149-152
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    • 2004
  • The design and the fabrication of a 1 MVA single-phase HTS transformer are presented in this paper, The rated voltages are 22.9 ㎸ for primary and 6.6 ㎸ for secondary, and the rated currents are 44 A and 152 A respectively. The transformer has HTS double pancake type windings. This type of winding has many advantages such as ease of fabrication and maintenance, good distribution of surge voltage and insulation of windings. Single HTS wire was used for primary winding and four HTS parallel wires were used for secondary winding. These windings are arranged reciprocally with the shell type iron core. An FRP cryostat with room temperature bore was fabricated to isolate the iron core from the coolant. The winding will be cooled down to 65 K with sub-cooled liquid nitrogen using a GM-cryocooler. The sub-cooled liquid nitrogen has advantages of good insulation because of no bubbles as well as increased current capacity of HTS wire.

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