JP2596758B2 - Protection liquid and protection method for high-temperature superconducting material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective liquid for maintaining and protecting a high-temperature superconducting material at a permanent temperature, and a protective method using the same.

2. Description of the Related Art Development of high-temperature superconducting materials is progressing rapidly.Currently, materials that exhibit superconductivity at liquid nitrogen temperatures, as well as materials that exhibit unstable superconductivity even at dry ice temperatures, have been reported in the near future. It is expected that materials that exhibit superconductivity even at room temperature or higher will be developed.

Conventionally, the protective liquid for the superconducting material used was exclusively liquid helium, but with the development of the high-temperature superconducting material, liquid nitrogen has become available.

Problems to be Solved by the Invention The problem here is that no matter how the high-temperature superconducting material is developed, in order to put it to practical use, the inherent temperature range indicated by the superconducting material is maintained permanently, In addition, there is a need to develop an apparatus and method for protecting the material itself and further simplifying the transfer of electric energy. Further, it is necessary to control a magnetic field generated when superconductivity is working and to perform insulation.

However, current development trends seem to bias researchers' interest in competition for how to find materials that exhibit superconductivity at high temperatures.

In view of such circumstances, an object of the present invention is to provide a protective liquid for cooling and protecting a high-temperature superconducting material, and a protective method using the same.

Means for Solving the Problems The present inventors have studied the application of various inert liquids as a protective liquid for high-temperature superconducting materials, and found that an inert fluorine compound, particularly the following perfluorocarbon, is most suitable for this purpose. This led to the completion of the present invention.

That is, the protective liquid for the high-temperature superconducting material of the present invention is a protective liquid composed of an inert fluorine compound that is liquid or in a vapor phase formation state at the time of use, and the inert fluorine compound has a pour point. −170 to −20 ° C, boiling point 40 ° C or higher, 2
Specific gravity at 1.65 ~ 2.10 at 5 ° C, kinematic viscosity at 25 ° C
0.3-500cSt, thermal conductivity at 25 ° C is 0.0001-0.001ca
l / cm ・ sec ・ ℃ 、 Surface tension at 25 ℃ is 11 ~ 21dyne / cm
Characterized in that it comprises a substantially completely fluorinated chain or cyclic perfluorocarbon which does not contain Cl and H but may contain O and N in the molecule. .

Such non-active fluorine compounds (perfluorocarbons), _{typically, CF 3 - (CF 2)} n-CF 3, F - [(CF 2) p-O] q-
(CF ₂₎ r-F, And so on. Here, n, p, q, and r are positive integers.

Such an inert fluorine compound (perfluorocarbon) can be obtained, for example, by using an aliphatic compound, an alicyclic compound, or an aromatic compound as a raw material and substituting H in the compound with F (fluorination by F2, electrolytic fluorine). , Fluorination with metal fluoride, fluorination with CF3 OF, etc., F substitution of halogen (F2, MFx (M is metal, x is an integer of 1 or more)
, F substitution of O (C-OH to CF, C = O to CF2, etc.), F2 addition to olefin, fluorination of polychloride with KF, F2, tetrafluoro It is produced by a method such as oligomerization or telomerization of ethylene or hexafluoropropene.

Among the above perfluorocarbons, those having the following characteristic values are used. However, specific gravity, kinematic viscosity, and thermal conductivity are measured values at 25 ° C.

Pour point −170 to −20 ° C, Boiling point 40 ° C or more, Specific gravity 1.65 to 2.10, Kinematic viscosity 0.3 to 500 cSt, Thermal conductivity 0.0001 to 0.001 cal / cm ・ sec ・ ° C Surface tension 11 to 21 dyne / cm, like this Commercially available perfluorocarbons satisfying various characteristic values include, for example, the Fluorinert series of Minnesota Mining Manufacturing, Inc. of the United States, the GALDEN series of Montefluos Inc. of Italy, and Air Products of the United States.・ Multi-floor of M & C (Mult
ifluor) series, Imperial Smelting's Fulltec (FLUTEC) series in the UK, Daikin Industries, Ltd.'s DEMNUM series, Tokuyama Soda's Perfroed series, Mitsubishi Metal's F-top series, Dai Nippon Ink. There is a mega fuck series of Chemical Industry Co., Ltd.

The method for protecting a high-temperature superconducting material according to the present invention uses the above-mentioned protective liquid (1) using the above-mentioned protective liquid composed of the above-mentioned inert fluorine compound (perfluorocarbon) which is in a liquid or vapor phase-formed state at the time of use. A high-temperature superconducting material (3) is placed in a heat-insulating chamber (2) in which the protective liquid (1) or its vapor phase can be contacted, and the protective liquid (1) or its vapor phase is brought to a predetermined temperature. A cooling mechanism (4) is provided for keeping the high-temperature superconducting material (3) in contact with the protective liquid (1).

As the heat insulating chamber (2), various shapes including a container shape and a tube shape are used.

As a method of contacting the high-temperature superconducting material (3) with the protective liquid (1) or its vapor phase, a method of immersing the high-temperature superconducting material (3) in the protective liquid (1) and a method of contacting the protective liquid (1) with the high-temperature superconducting material (3) Spray method, high temperature superconducting material (3)
Is brought into contact with the vapor phase of the protective liquid (1) having a boiling point.

Then, an appropriate cooling mechanism (4) is provided to keep the protective liquid (1) or its vapor phase at a predetermined temperature.

 EXAMPLES Next, the present invention will be further described with reference to examples.

Embodiment 1 FIG. 1 is an explanatory view showing an example of an apparatus according to the method of the present invention.

(2) is a heat insulating chamber, in which a protective liquid (1) described later is stored.

(3) is a coil-shaped or loop-shaped high-temperature superconducting material provided so as to be immersed in the protective liquid (1). (3a)
Is a first switch made of a high-temperature superconducting material, and the first switch (3a) is also provided so as to be immersed in the protective liquid (1).

(5) is a normal switch, and (5a) is a second switch made of a normal conductor. (6) is a power supply, and (10) is a packing material.

(7) is an expansion chamber, which is provided outside the heat insulation chamber (2). Between the expansion chamber (7) and the gas phase in the heat insulation chamber (2),
It is communicated via line (8).

(4) is a cooling mechanism, which is arranged in the middle of the pipe (8). Usually, a heat exchanger is used as the cooling mechanism (4).

Although the high-temperature superconducting material (3) is immersed in the protective liquid (1) in FIG. 1, the high-temperature superconducting material (3) is positioned in the vapor phase of the protective liquid (1), and Can be cooled by the vapor phase of the protective liquid (1).

Embodiment 2 FIG. 2 is an explanatory view showing another example of the apparatus according to the method of the present invention.

As in the case of the first embodiment, (1) is a protective liquid, (2) is a heat insulating chamber, (3) is a high-temperature superconducting material, (3a) is a first switch, (4) is a cooling mechanism, and (5) is A normal conductor, (5a) is a second switch, (6) is a power supply, (8) is a pipeline, and (10) is a packing material.

In the second embodiment, the high-temperature superconducting material (3) is disposed in a gas phase in the heat insulating chamber (2).

(9) is a showering means, which in this embodiment comprises a tank (9a) and a nozzle (9b).

A line (8) communicates between the liquid phase in the heat insulation chamber (2) and the showering means (9), and is provided in the middle of the line (8) as an example of a cooling mechanism (4). A heat exchanger is located.

Protective liquid (1) As the protective liquid in Example 1 or Example 2, for example, perfluorocarbon having the following characteristic values is used.

(A) Minnesota mining having the characteristic values in Table 1
Fluorinert series manufactured by Manufacturing Co. (B) Galden series manufactured by Montefluorose Co. having the characteristic values shown in Table 2 (C) Demnum S-20 manufactured by Daikin Industries, Ltd. (boiling point is 40 ° C. or higher) having the following characteristic values Pour point −75 ° C. Specific gravity 1.860 (20 ° C.) Kinematic viscosity 53 ± 10 cSt (20 ° C.) Surface tension 17.7 dyne / cm (20 ° C.) (D) Air products and products having the following characteristic values
Chemicals Multifloor APF-215 Pour point -48 ° C, Boiling point 215 ° C, Specific gravity 2.01 (25 ° C), Kinematic viscosity 14 cSt (25 ° C), Thermal conductivity 0.00013 cal / cm · sec · ° C (25 ° C) Surface Tension 18 dyne / cm (25 ℃), Operation Next, the operation of the present invention will be described for the case of the above embodiment.

In the first embodiment, the evaporated protective liquid (1) reaches the expansion chamber (7) via the pipe (8), during which it is cooled and liquefied by the cooling mechanism (4), and is liquefied in the heat insulating chamber (2). , The temperature of the system is always kept constant, including the liquid phase and the gas phase.

In Example 2, the protective liquid (1) in the tank (9a) was used.
Is showered from the nozzle (9b), wets the high-temperature superconducting material (3) and cools it,
Fall to the bottom of the. The protective liquid (1) stored at the bottom returns to the tank (9a) again, while being cooled by the cooling mechanism (4), and the temperature of the system is always kept constant.

In either case of Example 1 and Example 2,
When the first switch (3a) is opened and the second switch (5a) is closed, a power source (6) -normal conductor (5) -high-temperature superconducting material (3) -normal conductor (5) is formed. Current flows through the closed circuit.

Then, when the second switch (5a) is opened,
When the switch (3a) is closed, the high-temperature superconducting material (3) -first
A current will flow permanently through the closed circuit formed by the switch (3a).

The current flowing through this circuit can be supplied to the outside by connecting an appropriate actuator or storage battery instead of the power supply (6), opening the first switch (3a) and closing the second switch (5a). Can be taken out.

Effects of the Invention The inert fluorine compound, particularly perfluorocarbon, in the present invention is a liquid or a vapor phase at a use temperature, and has a low viscosity, a good heat transfer property, and a high-temperature superconducting material. Properties such as good wettability to water, electrical insulation, non-flammability and non-flammability, inertness to high-temperature superconducting materials and packing materials, no toxicity to human body Therefore, it is most suitable as a protective liquid for a high-temperature superconducting material.

Further, by using such a protective liquid, the device can be completely closed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus according to the method of the present invention. FIG. 2 is an explanatory view showing another example of the apparatus according to the method of the present invention. (1) Protective liquid, (2) Thermal insulation chamber, (3) High-temperature superconducting material, (3a) First switch, (4) Cooling mechanism, (5) Normal conductor , (5a)... Second switch, (6)... Power supply, (7)... Expansion chamber, (8)... Pipeline, (9)... Showering means, (9a).
(9b) ... Nozzle, (10) ... Packing material

Claims (2)

(57) [Claims] 1. A protective solution for a high-temperature superconducting material, comprising an inert fluorine compound which is in a liquid or vapor phase formation state at the temperature at the time of use, wherein the inert fluorine compound has a pour point of -170 to -20 ° C,
Boiling point is 40 ℃ or more, specific gravity at 25 ℃ is 1.65 ~ 2.10, 25 ℃
Has a characteristic value of a kinematic viscosity of 0.3 to 500 cSt, a thermal conductivity at 25 ° C. of 0.0001 to 0.001 cal / cm · sec · ° C., and a surface tension of 11 to 21 dyne / cm at 25 ° C., and Cl and H in the molecule. A protective liquid for a high-temperature superconducting material, comprising a substantially completely fluorinated chain or cyclic perfluorocarbon which does not contain but may contain O and N. 2. A protective liquid comprising an inert fluorine compound which is liquid or forms a vapor phase at a temperature at the time of use,
The inert fluorine compound has a pour point of -170 to -20 ° C,
Boiling point is 40 ℃ or more, specific gravity at 25 ℃ is 1.65 ~ 2.10, 25 ℃
Has a characteristic value of a kinematic viscosity of 0.3 to 500 cSt, a thermal conductivity at 25 ° C. of 0.0001 to 0.001 cal / cm · sec · ° C., and a surface tension of 11 to 21 dyne / cm at 25 ° C., and Cl and H in the molecule. Using a protective liquid consisting of a substantially completely fluorinated chain or cyclic perfluorocarbon which does not contain O but may contain O or N, in an insulating chamber (2) containing the protective liquid (1). A high-temperature superconducting material (3) arranged so as to be able to come into contact with the protective liquid (1) or its vapor phase, and a cooling mechanism (4) for keeping the protective liquid (1) or its vapor phase at a predetermined temperature. A method for protecting a high-temperature superconducting material, comprising bringing the high-temperature superconducting material (3) into contact with the protective liquid (1).