Sub-cooled nitrogen cryogenic cooling system for superconducting fault current limiter by using GM-cryocooler

Kang, Hyoungku; Kim, Hyung Jin; Bae, Duck Kweon; Ahn, Min Cheol; Chang, Ho‐Myung; Ko, Tae Kuk

doi:10.1016/j.cryogenics.2004.07.007

Cited by 23 publications

(8 citation statements)

References 5 publications

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“…Another significant benefit of using subcooled liquid nitrogen as a cooling medium is to suppress bubbles that may be generated from an internal or external heat load [7]. Since bubbles play a critical role in deteriorating the breaking voltage of liquid nitrogen, the subcooled state is essential for electrical insulation in high-voltage applications such as HTS transformers [2], [3], HTS fault current limiters [4], [5], or HTS cables [6]. The typical subcooled-liquid region for these HTS magnets is indicated on phase diagram of nitrogen in Fig.…”

Section: Introductionmentioning

confidence: 99%

A Compact Cryocooling System With Subcooled Liquid Nitrogen for Small HTS Magnets

Chang

Kim

Sim

et al. 2008

IEEE Trans. Appl. Supercond.

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A compact cryogenic cooling system is developed for small HTS magnets to be continuously refrigerated in subcooled liquid nitrogen at temperatures below 77 K by a cryocooler. This thermal design is particularly useful when electrical insulation and compactness are significant at the same time. HTS elements are immersed in a cylindrical liquid-nitrogen vessel, and a copper band is brazed around the exterior sidewall of the cylinder at vertical location just under the liquid level in order to achieve peripherally uniform cooling with a GM cryocooler. The vapor space above liquid nitrogen in the vessel provides a fully open room for current leads and mechanical supports to the magnets. Heat is removed from the HTS magnets by natural convection of subcooled liquid nitrogen to the cold sidewall. The key components are designed based on heat transfer analysis. A prototype is fabricated, and it is successfully demonstrated that the thermal load is effectively removed and temperature is spatially uniform.

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Section: Introductionmentioning

confidence: 99%

A Compact Cryocooling System With Subcooled Liquid Nitrogen for Small HTS Magnets

Chang

Kim

Sim

et al. 2008

IEEE Trans. Appl. Supercond.

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“…Since the heat leak through current leads is a major source of cooling load, an optimal design to minimize the cryogenic load [1]- [7] is important in the commercialization of HTS FCL. This study is part of our ongoing efforts in Korea toward a practical scale of the prototypes to be continuously refrigerated in subcooled liquid nitrogen by a cryocooler [8]- [10]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Current-Lead Design for Cryocooled HTS Fault Current Limiters

Chang

Kim

et al. 2007

IEEE Trans. Appl. Supercond.

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A comprehensive design procedure is presented for the current leads in HTS fault current limiters continuously refrigerated by a cryocooler. Two specific aspects are focused here in addition to the standard lead-design. The first is an optimization with taking into account the heat conduction through electrical insulator needed for high-voltage applications. Through a rigorous analysis, it is verified that the standard design should be modified in order to minimize the overall heat leak. The second is the transient thermal behavior that may be caused by excessive current. A numerical analysis is performed to estimate the peak temperature after a short current-limiting period, including the effect of fins as enhanced local heat capacity. Some of the design details are demonstrated for the specifications of FCL's under development in Korean R&D Programs.

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“…The liquid properties in the above equations (3)(4)(5)(6)(7)(8)(9)(10) are evaluated at the film temperature ((T SAT +T S )/2); while the latent heat is evaluated at the saturation temperature. The required condensation rate in the condenser for 100 W heat load at the evaporator is given in FIGURE 3.…”

Section: Design Detailsmentioning

confidence: 99%

“…Mechanical refrigerators have become an alternative to the cryogens for a variety of applications such as superconducting magnet systems and space applications [1][2][3][4][5]. Most of these applications, however, require a thermal link between the refrigerator and the source from which heat is to be removed due to the physical distance between them.…”

Section: Introductionmentioning

confidence: 99%

Flexible cryogenic thermosyphon

Celik

Painter

2012

AIP Conference Proceedings

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Cryocooler and pulse tubes have been increasingly used in small and large scale cryogenic systems including the superconducting magnet systems as heat sinks to attain and keep the required temperatures. Designing the thermal link between the mechanical refrigerator and the system may present a challenge due to the mechanical stresses developed during the cool-down of the assembled systems. Also, the cross section may be too bulky for metallic conductors for given thermal specifications. In this paper, a thermosysphon with a flexible fluid link between the evaporator and condenser is presented. The working fluid used in preliminary testing is nitrogen. The results of the initial testing of the flexible thermosyphon are presented.

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Sub-cooled nitrogen cryogenic cooling system for superconducting fault current limiter by using GM-cryocooler

Cited by 23 publications

References 5 publications

A Compact Cryocooling System With Subcooled Liquid Nitrogen for Small HTS Magnets

A Compact Cryocooling System With Subcooled Liquid Nitrogen for Small HTS Magnets

Current-Lead Design for Cryocooled HTS Fault Current Limiters

Flexible cryogenic thermosyphon

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