Heat transfer characteristics of liquid nitrogen for cyclic heating

Fuchino, S.; Tamada, Noriharu; Ishii, I.; Okano, Makoto

doi:10.1109/77.828532

Cited by 6 publications

(4 citation statements)

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“…Figure 4. Angular dependence of the E-J sc characteristics in an external magnetic field of 0.5 T at 75 K. The full circles and curves are, respectively, the experimental results and the theoretical values obtained by equations ( 1), ( 2), ( 3), ( 7) and (8).…”

Section: E-j Sc Properties As a Function Of Temperature And External ...mentioning

confidence: 98%

“…In this subsection, we discuss the contributions of the superconducting multifilaments and the silver sheath to the temperature increase. The difference of the thermal time constant between the superconducting filaments and the silver sheath is not considered to be large in this geometry of the tape [8]. Therefore, by omitting the heat transfer between the tape surface and the helium gas coolant here, one can roughly estimate the temperature increase by the specific heat.…”

Section: Current Sharing Rate and Its Effect On The Temperature Varia...mentioning

confidence: 99%

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Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Nakamura

Tsuchiya

Fujio

et al. 2002

Supercond. Sci. Technol.

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We study the angular dependence of E-J characteristics and dissipative properties due to thermal disturbance in the Bi-2223/Ag multifilamentary tape in the low-voltage region. In order to simulate the dissipative properties, we take into account the analytical expressions of the E-J characteristics as a function of temperature, external magnetic field and field direction, which agree well with the experimental data. It is shown that the simulation results of the dissipative properties agree with the experimental data semi-quantitatively. The relationship between the current sharing rate and its contribution to the temperature increase is also discussed, based on the simulation. These results are crucial for high-T c superconducting power application systems with a persistent current mode where even low-power dissipation is detrimental to the performance.

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Section: E-j Sc Properties As a Function Of Temperature And External ...mentioning

confidence: 98%

Section: Current Sharing Rate and Its Effect On The Temperature Varia...mentioning

confidence: 99%

Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Nakamura

Tsuchiya

Fujio

et al. 2002

Supercond. Sci. Technol.

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“…The device is usually immersed in a pool of liquid nitrogen. The heat transfer coefficient from the film to the liquid nitrogen is of the order of 10 4 W K −1 m −2 when the film temperature is about 10 K higher than the liquid nitrogen temperature [15][16][17]. Therefore, in the present discussion, we will neglect the direct cooling of the film from the surrounding fluid.…”

Section: The Modelmentioning

confidence: 99%

Simulation of the initial response of a highT_csuperconducting film submitted to a voltage source

Reymond¹,

Antognazza

Decroux

et al. 2004

Supercond. Sci. Technol.

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We present a model describing the response in the microsecond timescale of a superconducting high Tc thin film connected to a voltage source. The model is based on the existence of a critical current density j*(T), above which a highly dissipative state is observed in superconducting thin films. We use its experimental temperature dependence to calculate the current as a function of time, flowing into a Y Ba2Cu3O7 bridge deposited on a sapphire substrate. Unlike the usual hot spot picture, our model accounts for the similarity of the descriptions found in various reports treating the switching of fault current limiters based on superconducting thin films. In particular, our calculation exhibits the main observed features: after the voltage is turned on, the current density peaks in a few microseconds to a well defined value, then it decreases rapidly and stabilizes to approximately half of this peak value.

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“…From this reference, in a steady state and at 50 Hz, respectively, is about and . q is approximately proportional to [4], [5]. The theoretical lines can therefore be drawn assuming and .…”

Section: Comparison Of Dc-ac and Coil Placementmentioning

confidence: 99%

Thermal Runaway and Resistive Properties of a Bi2223 Pancake Coil Subjected to Overcurrent

Tanaka

Furuse

Arai

et al. 2005

IEEE Trans. Appl. Supercond.

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Various kinds of superconductivity-based fault current limiters (FCL's) have been studied. One type uses a superconductive reactor or magnet that loses its superconductive properties when subjected to excessive current flow. We examined the characteristics of a Bi2223 double pancake coil subjected to overcurrent. DC or AC overcurrent was passed through the coil cooled by saturated liquid nitrogen, and the resultant temperature difference was measured between the coil surface and the saturated liquid nitrogen. We then theoretically and experimentally investigated the starting conditions of the resultant thermal runaway. Our results confirmed that these conditions are decided by the product of critical heat flux and cooling area, and that the angle of the coil is important if the cooling channels are narrow.

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Heat transfer characteristics of liquid nitrogen for cyclic heating

Cited by 6 publications

References 0 publications

Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Simulation of the initial response of a highT_csuperconducting film submitted to a voltage source

Thermal Runaway and Resistive Properties of a Bi2223 Pancake Coil Subjected to Overcurrent

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Heat transfer characteristics of liquid nitrogen for cyclic heating

Cited by 6 publications

References 0 publications

Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Angular dependence ofE–Jcharacteristics and dissipative properties in Bi-2223/Ag tape

Simulation of the initial response of a highTcsuperconducting film submitted to a voltage source

Thermal Runaway and Resistive Properties of a Bi2223 Pancake Coil Subjected to Overcurrent

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Simulation of the initial response of a highT_csuperconducting film submitted to a voltage source