Thermal conductivity of glass fiberepoxy composite support bands for cryogenic dewars, phase II

Hust, J G

doi:10.6028/nbs.ir.84-3003

Cited by 8 publications

(6 citation statements)

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“…We used the thermal conductivity of insulator (GFRP) from [12]. In Case 1, the cooling load can be reduced with the present method only by 0.4 W (1.5%), since the heat conduction through the insulator is very small.…”

Section: B Design Examplesmentioning

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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Section: B Design Examplesmentioning

confidence: 99%

Current-Lead Design for Cryocooled HTS Fault Current Limiters

Chang

Kim

et al. 2007

IEEE Trans. Appl. Supercond.

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“…9 [10]. In order to reduce the heat leak to the cold mass, the straps are intercepted by cold shielding.…”

Section: Analysis Of Suspension Structure For a Superconducting mentioning

confidence: 99%

Theoretical Model of a Cold Mass Strap Suspension System for Superconducting Magnets

Wang

Zhao

et al. 2011

IEEE Trans. Appl. Supercond.

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Strap suspension structures are widely used in superconducting magnet systems for high strength and low heat leak. A theoretical model is developed to design and analyze strap suspension structures. The supported cold mass, the tensile stress due to a cooldown, and a quasi-static acceleration load are considered in the model. In addition, the load conditions during transportation and operating the superconducting magnet system are analyzed. Design rules composed of mechanical strength, minimum resonant frequency, and heat load are presented. A suspension structure consisting of eight strap assemblies for a superconducting magnet is analyzed based on the model. The maximum pretension force is calculated, and the allowable accelerations for the maximum pretension are given. The vertical dynamic performance is better than the horizontal directions for the given strap configuration.

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“…The apparatus used here to measure thermal conductivity is a previously described unguarded "fixed-point" apparatus [10], based on a method of axial one-dimensional heat flow. Some modifications have been made since the original publication appeared.…”

Section: Apparatusmentioning

confidence: 99%

“…Knowledge of the power Q spec through the specimen, specimen geometry (length i and cross-sectional area A) and temperature difference AT across the specimen allow the mean thermal conductivity, A, to be calculated using the one-dimensional approximation of Fourier's law, Q sp ec " -A-A-(dT/dx) (9) recast into the approximate form A -(Q spec /AT).(i/A). (10) Here the ratio (AT/i) in Eq. (10) approximates the derivative dT/dx in Eq .…”

Section: Computation Of Thermal Conductivitymentioning

confidence: 99%

“…The accuracy of the original apparatus for moderate conducting material was ±10% [10]. After some modifications to the apparatus and automating the system, further tests on a stainless steel standard reference material (SRM 735) have indicated an overall system accuracy of ±5% (when measuring specimens having a conductivity similar to that of stainless steel) .…”

Section: Thermal Conductivity Of Alloy X2095 (4%cu-l%li)mentioning

confidence: 99%

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Aluminum-lithium alloys :

Purtscher¹,

Austin²,

Kim³

et al. 1992

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Surface-cracked tension fracture tests were conducted in the T-S orientation at 295, 76, and 4 K on two plate alloys (X2095-T851, plate thickness of 12.7 mm and 2090-T81, plate thicknesses of 12.7 and 19.1 mm).The cryogenic toughness to room temperature toughness ratio for alloy 2090 is generally higher than that found for alloy X2095. Both alloys have significantly lower tensile properties near the surface of rolled plate than in the center of the plate.The physical properties of seven plate specimens were measured from liquid helium to room temperature.Three variations in chemical composition of alloy X2095, three different samples of alloy 2090, and a single sample of alloy 2219-T87 were included.The mass density of Al alloys decreases by 4% / mass % of Li.The influence of texture on elastic properties is considered minimal because there is less than 5% variation in elastic-stiffness in the Al-Li alloys. The shear and Young's moduli increase 3 to 4% / mass % Li. The bulk modulus and Poisson ratio decrease by 3% / mass % Li.Thermal expansion between 4 and 320 K was measured on the same seven plate specimens included in the physical properties study. All of the materials showed a typical temperature dependence where the slope of the coefficient of thermal expansion (CTE) vs. temperature curve has a zero slope near absolute zero and a smooth monotonic increase to a constant slope near room temperature.The thermal conductivity of alloy X2095 (4%Cu-l%Li) was determined over the temperature range 4.2 to 300 K using a steady-state apparatus. The conductivity at 290 K was approximately 40% higher than at 77 K and was 37 times that at 4.6 K.The thermal conductivity of alloy X2095 is approximately twice that of alloy 2090, previously measured in the same apparatus.Compared to that of a published literature value for alloy 2219, the thermal conductivity of alloy X2095 is about 65% lower than for alloy 2219.

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Thermal conductivity of glass fiberepoxy composite support bands for cryogenic dewars, phase II

Cited by 8 publications

References 0 publications

Current-Lead Design for Cryocooled HTS Fault Current Limiters

Current-Lead Design for Cryocooled HTS Fault Current Limiters

Theoretical Model of a Cold Mass Strap Suspension System for Superconducting Magnets

Aluminum-lithium alloys :

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