JP2011226621A - Insulated tube and superconductive cable - Google Patents

Abstract

A heat insulating tube having excellent heat insulating performance and a superconducting cable including the heat insulating tube are provided.
A heat insulating tube 1 includes a heat insulating material 4 and a linear spacer 3 between an inner tube 21 and an outer tube 22, and the cross-sectional shape of the spacer 3 is surrounded by a plurality of sides 32. It has a plurality of vertices 31 that are adjacent to each other and protrude outward. All the sides 32 connecting the adjacent vertices 31 are located inside a virtual straight line 33 connecting the vertices 31 to each other. By reducing the contact area between the spacer 3 and the other components of the heat insulating tube 1, it is possible to suppress an increase in the amount of heat entering the inner tube 21 or the amount of heat radiation from the inner tube 21. The heat insulating performance of the heat insulating tube 1 can be improved.
[Selection] Figure 1

Description

  The present invention relates to a heat insulating tube and a superconducting cable including the heat insulating tube. In particular, the present invention relates to a heat insulating tube having excellent heat insulating performance.

  A typical structure of a heat insulating tube is a double-structured tube consisting of an inner tube and an outer tube, with a built-in heat insulating material between the inner tube and the outer tube, and evacuating the two tubes. It is done. Further, a spacer is built in between both the tubes, and the distance between the inner tube and the outer tube is maintained. Specifically, the structure which arrange | positioned the laminated heat insulating material in the outer periphery of an inner pipe, provided the spacer on it, and hold | maintained the space | interval of an inner pipe and an outer pipe | tube is mentioned.

  As a form of the spacer, Patent Document 1 discloses a configuration in which a plurality of cylindrical bodies are arranged in parallel at a predetermined interval and integrated with a belt-like body. As another spacer form, Patent Document 2 discloses a string-like spacer. In this example, a plurality of spacers are arranged along the longitudinal direction of the heat insulating material, and a plurality of spacers are provided in the circumferential direction. In order to position the spacers, grooves corresponding to the cross-sectional shape of the spacer are formed in the heat insulating material. .

Japanese Patent Laid-Open No. 11-007844 Japanese Patent Laid-Open No. 10-288293

  However, when the inner and outer pipes are unevenly distributed due to the bending or self-weight of the heat insulating pipe, the shape of the spacer that keeps the distance between the inner pipe and the outer pipe may be deformed. In particular, the inner tube is biased toward the outer tube so that the distance between the inner tube and the outer tube is narrowed, and the spacer may be deformed by pressing the double structure tube.

  In the form of the spacer of Patent Document 1, since the cross-sectional shape of the cylindrical body of the spacer is circular, the line contact is usually made along the longitudinal direction of the heat insulating tube at the contact point between the spacer and the outer tube and between the spacer and the heat insulating material. ing. However, when the spacer is pressed against the double-structure tube, the pressed portion tends to be a flat and wide area, and the spacer and the outer tube, and the contact portion between the spacer and the heat insulating material are wide along the longitudinal direction of the heat insulating tube. Surface contact. If the contact area between the two is wide at each contact location, the amount of heat intrusion into the inner tube or the amount of heat radiation from the inner tube increases.

  On the other hand, in the form of the spacer of Patent Document 2, in order to minimize the contact area between the spacer and the outer tube, the cross-sectional shape of the spacer is provided with a corner such as a rhombus or a drop, and the corner is in contact with the outer tube. I have to. However, in this case, it is necessary to install the spacer so as to come into contact with the outer tube at the corner of the spacer, and the spacer is pressed by the double structure tube, and its predetermined installation position with respect to the central axis in the longitudinal direction of the spacer. If it is rotated and shifted even a little, the contact area between the spacer and the outer tube becomes wide surface contact along the longitudinal direction. Further, in Patent Document 2, a groove corresponding to the cross-sectional shape of the spacer is formed in the heat insulating material for positioning the spacer, but reduction of the contact area between the spacer and the heat insulating material is not considered.

  This invention is made | formed in view of said situation, and one of the objectives is to provide the heat insulation pipe | tube excellent in heat insulation performance.

  Another object of the present invention is to provide a superconducting cable including the above-described heat insulating tube.

  The present invention achieves the above-mentioned object by devising the cross-sectional shape of the spacer and reducing the contact area between the spacer and other components (inner and outer tubes, heat insulating materials, etc.).

  In the heat insulating tube of the present invention, a heat insulating material and a linear spacer are incorporated between the inner tube and the outer tube, and the cross-sectional shape of this spacer is a substantially polygon surrounded by a plurality of sides and is adjacent to each other. The sides are joined to each other and have a plurality of vertices protruding outward. And all the sides which connect the said adjacent vertex are located inside the virtual straight line which connects the said vertex.

  According to the said structure, the contact location of a spacer and the other structural member of a heat insulation pipe | tube is made into the vertex of a spacer, and both contact can be made into a line contact substantially along the longitudinal direction of a heat insulation pipe | tube. it can. And even if the spacer is pressed by the double-structured tube and the pressed part becomes flat surface contact, the spacer provided in the heat insulating tube of the present invention connects the vertices with the side connecting adjacent vertices. Since it is located inside the virtual straight line, the increase in the contact area due to the pressing of the double structure tube can be minimized. Further, even when the spacer is rotated and displaced with respect to the central axis in the longitudinal direction, it is possible to prevent the spacer and the other constituent members from coming into contact with each other except at the apex. That is, the surface connecting the vertices can be prevented from making wide surface contact with the other constituent members. Therefore, since the heat insulation pipe | tube of this invention can suppress the increase in the contact area of a spacer and said other structural member, the amount of heat penetration | invasion to the inner side of an inner pipe or the amount of thermal radiation from the inner side of an inner pipe | tube is reduced. An increase can be suppressed and the heat insulation performance of a heat insulation pipe | tube can be improved.

  As one form of this invention, the form whose number of the said vertex is 3-5 is mentioned.

  Regardless of the arrangement direction (rotation direction) of the spacer between the inner and outer tubes, the number of apexes is three or more in order to make contact between the spacer and the inner and outer tubes or the heat insulating material at the apex of the spacer. On the other hand, the smaller the number of vertices, the smaller the number of contact points between the spacer and other components of the heat insulation pipe, so the amount of heat penetration into the inner pipe or the amount of heat radiation from the inside of the inner pipe is suppressed. can do. On the other hand, when the number of vertices increases, the cross-sectional shape of the spacer approaches a circular shape, and when the spacer is pressed against the double-structured tube, the contact between the spacer and the other constituent member is as follows. It becomes easy to make wide surface contact along the longitudinal direction. Therefore, the number of vertices is preferably 5 or less.

  As one form of this invention, the form whose interior angle in the said vertex is an acute angle is mentioned.

  When the inner angle at the apex increases, the cross-sectional shape of the spacer approaches a circle, and when the spacer is pressed against the double-structured tube, the contact between the spacer and the other components of the heat insulating tube It becomes easy to make wide surface contact along the longitudinal direction. Therefore, since the inner angle at the apex is an acute angle, even if the spacer is pressed against the double-structured tube, the increase in the contact area due to the pressing can be minimized. If the inner angle at the apex is too small, when the spacer is pressed between the inner and outer tubes, it bends in the vicinity of the apex, increasing the contact area with the other components, and maintaining the distance between the inner tube and the outer tube This inner angle is preferably 20 ° to 80 °. More preferably, it is 30 ° to 40 °.

The internal angle is defined as follows depending on whether the two sides sandwiching the vertex are straight or curved.
(1) When two sides are straight lines, the inner angle at the apex is the angle between the two sides.
(2) If the two sides are curved, the interior angle at the vertex is the angle formed by the tangents described next to each curve. Of the tangent lines to the curve, the normal line at the contact point is the tangent line passing through the midpoint of the line segment connecting the center of gravity and the apex of the spacer.
(3) When one is a straight line and the other is a curved line, the interior angle at the vertex is the angle formed by the straight line and the tangent line of the curved line.

  As one form of this invention, the said cross-sectional shape has a form which is rotationally symmetric with respect to the central axis of a longitudinal direction.

  When the cross-sectional shape of the spacer is rotationally symmetric, it is not necessary to define the arrangement direction of the spacer and the arrangement of the spacer is easy.

  The heat insulating tube of the present invention can be suitably used as a constituent member of a superconducting cable. That is, as the superconducting cable of the present invention, a cable provided with the heat insulating tube of the present invention and a cable core having a superconducting conductor and housed inside the heat insulating tube can be mentioned.

  When the heat insulating tube of the present invention is used for a superconducting cable, the heat insulating tube of the present invention can have high heat insulating performance, and therefore, energy saving required for maintaining the temperature of the refrigerant flowing inside the inner tube can be expected.

  The heat insulation pipe of the present invention is devised in the cross-sectional shape of the spacer, and by reducing the contact area between the spacer and other components of the heat insulation pipe, the amount of heat intrusion into the inner pipe or from the inner side of the inner pipe An increase in the amount of heat radiation can be suppressed, and the heat insulation performance of the heat insulation tube can be improved.

  Moreover, the superconducting cable provided with the heat insulation pipe | tube of this invention can anticipate the labor saving of the energy required for the heat insulation performance of a heat insulation pipe | tube to be improved, and the temperature maintenance of a refrigerant | coolant.

1 shows a heat insulating tube according to an embodiment of the present invention, in which (A) is a partial longitudinal sectional view, (B) is a transverse sectional view, and (C) is a partially enlarged view of a spacer. The cross-sectional shape of the modification of the spacer used for the heat insulation pipe | tube of embodiment is shown, (A) is a substantially square shape, (B) is a star shape. It is a cross-sectional view of a superconducting cable provided with the heat insulation pipe | tube of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals denote the same members.

<Embodiment 1>
The heat insulating tube 1 of the present invention will be described with reference to FIG. This heat insulating tube 1 includes a double-structure tube 2 composed of an inner tube 21 and an outer tube 22, a heat insulating material 4 wound around the inner tube 21, and an interval between the inner tube 21 and the outer tube 22. A spacer 3 for holding and a vacuum layer 5 formed between both the tubes 21 and 22 are provided. Hereinafter, each configuration of the heat insulating tube 1 will be described in more detail.

[Insulated pipe]
(Double structure pipe)
The double-structure tube 2 is composed of an inner tube 21 and an outer tube 22, and is a stainless corrugated tube having a bellows or a spiral shape in the longitudinal direction so as to be easily bent. In the inner tube 21, a normal fluid flows. The temperature of the fluid varies depending on the type of fluid and the intended use, and a wide range of temperatures from extremely low to high is used. Examples of the fluid include liquid nitrogen, liquid oxygen, liquefied natural gas, steam, hot water, and the like.

  As the material of the double structure tube 2, a metal such as flexible aluminum can be used in addition to stainless steel.

  In addition to the corrugated pipe, the double-structure pipe 2 can be a straight pipe having no irregularities on the surface for straight sections when there is no need for bending or when the heat insulating pipe is used at a short distance.

  The thickness of each of the inner and outer pipes 21 and 22 constituting the double-structure pipe 2 is determined by the pressure at which the double-structure pipe 2 expands in the circumferential direction due to the flow of fluid inside the inner pipe 21, The structural tube 2 is bent to a thickness that can withstand the tension applied in the longitudinal direction.

(Insulation material)
A heat insulating material 4 is wound around the outer periphery of the inner tube 21 and inside the spacer 3 in order to further improve the heat insulating performance. If the fluid temperature in the inner pipe 21 is lower than the outside air temperature of the heat insulating pipe 1 by arranging the heat insulating material 4, the entry of radiant heat from the outside is prevented, and the fluid temperature is higher than the outside air temperature of the heat insulating pipe 1 Can prevent the radiant heat from being dissipated from the fluid. Examples of the heat insulating material 4 include a laminated material obtained by laminating a belt-shaped material in which aluminum is vapor-deposited on one surface or both surfaces of a belt-shaped resin film and a mesh structure material made of synthetic fibers, and typically a super insulation (trade name). The heat insulating material 4 is wound around the entire outer circumference of the inner tube 21 to prevent the intrusion of radiant heat into the inner tube 21 or the radiant heat from the inner tube 21. The position where the heat insulating material 4 is disposed may be anywhere between the inner tube 21 and the outer tube 22. The heat insulating material 4 may be disposed on the outer periphery of the inner tube 21, and a spacer 3 described later may be disposed thereon. Conversely, the spacer 3 may be disposed on the outer periphery of the inner tube 21, and the heat insulating material 4 may be disposed thereon. May be arranged. As a method for installing the heat insulating material 4, besides the spiral winding, the heat insulating material 4 may be vertically attached so as to cover the entire outer peripheral surface of the inner tube 21.

(Spacer)
In order to maintain the distance between the inner tube 21 and the outer tube 22, the spacer 3 is installed. The spacer 3 is a linear body having a substantially polygonal cross section. As shown in FIG. 1 (C), this cross-sectional shape is a substantially polygonal shape surrounded by a plurality of sides 32, and has a plurality of vertices 31 that are adjacent to each other and that protrude outward. . All sides 32 connecting adjacent vertices 31 are located inside a virtual straight line 33 connecting the vertices 31 to each other.

  The cross-sectional shape of the spacer 3 shown in FIG. 1C has three vertices 31, and a side 32 connecting adjacent vertices 31 is a curve that is recessed inwardly from the virtual straight line 33. This curve (side 32) is an arcuate curve having the same curvature radius of 3.0 mm and the same length of 2.69 mm on all three sides. The maximum distance between the virtual straight line 33 and the side 32 is 0.30 mm. The internal angle θ at the vertex 31 is 36 °. Since the two sides 32 sandwiching the vertex 31 are curves, the inner angle θ is an angle formed by tangents described next to each curve. Of the tangent lines to the curve, the normal line at the contact point is the tangent line passing through the midpoint of the line segment connecting the center of gravity of the spacer 3 and the vertex 31.

  At the three apexes 31, the spacer 3 and the outer tube 22 and the spacer 3 and the heat insulating material 4 are brought into contact with each other, and the distance between the inner tube 21 and the outer tube 22 is maintained. Since the number of apexes 31 is 3, the contact point between the spacer 3 and the other components of the heat insulating tube 1 can be minimized, even if the spacer 3 is pressed against the double structure tube 2, It can hold 22 intervals. Since the cross-sectional shape is simple, the spacer 3 can be easily processed and the constituent materials can be reduced. In addition, since all the sides 32 have the same radius of curvature and the same length, it is not necessary to define the arrangement direction of the spacer 3, and the arrangement of the spacer 3 is easy.

  The number of the apexes 31 is not related to the arrangement direction (rotation direction) of the spacer 3 between the inner and outer pipes 21 and 22, and the contact between the spacer 3 and the outer pipe 22, and the spacer 3 and the heat insulating material 4 is the apex 31 of the spacer 3. In order to do in, it is 3 or more. On the other hand, it is preferable that the number of apexes 31 is smaller because the number of contact points between the spacer 3 and the other constituent members can be reduced. On the other hand, when the number of apexes 31 increases, the cross-sectional shape of the spacer 3 approaches a circular shape, and when the spacer 3 is pressed against the double-structure tube 2, the spacer 3 contacts the other structural member. Is likely to be wide surface contact along the longitudinal direction of the heat insulating tube 1. Therefore, the number of vertices 31 is preferably 5 or less.

  All the sides 32 connecting the adjacent vertices 31 may be curved or straight as long as they are inside the virtual straight line 33 connecting the vertices 31 to each other. Alternatively, a plurality of straight lines or curves may be combined to form an edge that connects the vertices 31 together. For example, the side 32 connecting the adjacent vertices 31 is composed of three straight lines [may be composed of three sides of the mold. Even if the spacer 3 is deformed or rotated with respect to the central axis in the longitudinal direction by pressing the spacer 3 against the double-structure tube 2, the spacer 3 and the spacer 3 A shape that is sufficiently recessed inside the virtual straight line 33 so as not to contact the other constituent members is preferable. The maximum distance between the virtual straight line 33 and the side 32 is preferably 0.20 mm to 0.40 mm.

  If the inner angle θ at the apex 31 is too small, when the spacer 3 is pressed between the inner and outer pipes 21 and 22, it bends in the vicinity of the apex 31 to increase the contact area with the other components, and the inner pipe The inner angle θ is preferably 20 ° to 80 °, and more preferably 30 ° to 40 °, because it is difficult to maintain a distance between 21 and the outer tube 22.

  As a modification of the spacer 3, one having a cross-sectional shape as shown in FIG. For example, the spacer 3 shown in FIG. 2 (A) has a substantially square cross-sectional shape. There are four vertices 31, and the sides 32 connecting the adjacent vertices 31 are all arc-shaped curves and are located on the inner side of the virtual straight line 33 connecting the vertices 31. The spacer 3 shown in FIG. 2B has a star-shaped cross section. There are five vertices 31 and the side 32 connecting the adjacent vertices 31 is composed of two sides arranged in a straight line in a V shape, and these two sides are located inside the virtual straight line 33 connecting the vertices 31 to each other. ing.

  If the spacers 3 having different cross-sectional shapes are extruded, arbitrary ones can be produced simply by changing the die hole shape. In addition, the cross-sectional shape of the spacer 3 shown in FIGS. 1 and 2 is rotationally symmetric with respect to the central axis in the longitudinal direction of the spacer 3, so that it is necessary to define and arrange the rotation direction of the spacer 3. The spacer 3 is easy to arrange.

  The material of the spacer 3 is preferably low thermal conductivity, and polyamide resin, fluororesin, glass fiber, GFRP, etc. can be used.

  The spacer 3 only needs to be able to maintain the interval between the inner tube 21 and the outer tube 22, and the installation method is, for example, arranged along the longitudinal direction of the heat insulating tube 1 and may be provided in the circumferential direction. One or a plurality of spacers 3 may be spirally wound.

(Vacuum layer)
A vacuum layer 5 is formed by evacuating the inner tube 21 and the outer tube 22 held by the spacer 3. The higher the degree of vacuum of the vacuum layer 5, the higher the heat insulation performance. Note that the double-structure tube 2 shown in FIG. 1 is shown with the left end open, but in practice it is sealed after evacuation.

[Function and effect]
According to the heat insulating tube 1 of the present invention, the contact point between the spacer 3 and the inner and outer tubes 21, 22 or the heat insulating material 4 is the apex 31 of the spacer 3, so that the contact point between the two is in the longitudinal direction of the heat insulating tube 1. Can be substantially line contact along. And even if the spacer 3 is pressed against the double-structured tube 2 and the pressed portion is in flat surface contact, the heat insulating tube 1 of the present invention has the side 32 connecting adjacent vertices 31 with the vertex 31. Since it is located inside the imaginary straight line 33 that connects them, the increase of the contact area due to the pressing can be minimized. Further, even if the spacer 3 is rotated and displaced with respect to the central axis in the longitudinal direction, it is possible to prevent the spacer 3 and the other constituent members of the heat insulating tube 1 from contacting each other at the apex 31. That is, it is possible to prevent wide contact with the other constituent members at the side 32 connecting the vertices 31 to each other. Therefore, since an increase in the contact area between the spacer 3 and the other constituent member can be suppressed, an increase in the amount of heat entering the inner tube 21 or an amount of heat radiation from the inner tube 21 is suppressed. And the heat insulation performance of the heat insulation pipe 1 can be improved.

<Embodiment 2>
Next, a schematic configuration of the superconducting cable 10 including the heat insulating tube 1 of the present invention will be described with reference to FIG. The superconducting cable 10 has a configuration in which a three-core cable core 11 is accommodated in the heat insulating tube 1 of FIG. Hereinafter, each configuration of the superconducting cable 10 will be described in detail.

[Superconducting cable]
(Cable core)
The cable core 11 typically includes a former 12, a superconducting conductor layer 13, an electrical insulating layer 14, an external superconducting layer 15, and a protective layer 16 in order from the center. Of these layers, superconductors are used for the superconducting conductor layer 13 and the external superconducting layer 15.

  As the former 12, a solid one obtained by twisting metal wires or a hollow one using a metal pipe is used. When the hollow former 12 is used, the inside thereof can be used as a refrigerant flow path. The superconducting conductor layer 13 has a configuration in which a tape-like wire rod having an oxide superconductor, for example, a Bi2223 series superconducting tape wire (Ag-Mn sheath wire) is spirally wound in a single layer or multiple layers. In addition, RE123-based thin film wires (RE: rare earth elements such as Y, Ho, Nd, Sm, Gd, etc.) can also be used for the superconducting conductor layer 13. The electrical insulation layer 14 is made of an insulating paper tape such as kraft paper, or a semi-synthetic insulating tape obtained by combining kraft paper and plastic, for example, a tape-like insulating material such as PPLP (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. Configuration. The external superconducting layer 15 has a configuration in which the same superconducting wire as the superconducting conductor layer 13 is spirally wound. The external superconducting layer 15 is used, for example, as a magnetic shielding layer in the case of AC power transmission and as a return conductor in the case of DC power transmission. The protective layer 16 may be configured by winding kraft paper or the like. An anticorrosion layer 18 made of polyvinyl chloride or the like is formed on the outer tube 22.

(Refrigerant flow path)
A refrigerant flow path 17 is formed between the inside of the heat insulating tube 1 and each cable core 11. A refrigerant (for example, liquid nitrogen) that cools the superconductor flows through the refrigerant flow path 17.

  The refrigerant rises in temperature due to intrusion heat or the like from the outside and affects the superconducting state of the superconducting conductor layer 13 and the external superconducting layer 15. However, by using the heat insulating tube 1 of the present invention, the contact area between the spacer and other components such as the outer tube and heat insulating material can be reduced, and the amount of heat penetration from the outside to the inside of the inner tube is increased. Can be suppressed.

[Function and effect]
The superconducting cable 10 provided with the heat insulating tube 1 of the present invention is expected to improve the heat insulating performance of the heat insulating tube 1 and to save energy necessary for maintaining the temperature of the refrigerant.

<Example of trial calculation>
The contact area at the contact portion between the spacer and the outer tube was calculated using spacers having the same circumscribed circle diameter and different cross-sectional shapes. Specific calculation conditions are shown below.

[Example 1]
Double structure tube Material: Stainless steel Shape: Corrugated tube Dimensions: Inner tube outer diameter 123mm, inner diameter 113mm
Outer tube outer diameter 137mm, inner diameter 127mm
1000mm length
Spacer Material: PTFE (Polytetrafluoroethylene)
Shape: Linear body with a substantially cross-sectional shape (see Fig. 1 (b) and (c))
3 vertices: round at R0.5mm
Edge connecting vertices: Curve with a curvature radius of 3.0mm
Interior angle at the apex: 36 °
Cross section: 1.44mm ²
Dimensions: circumscribed circle diameter 3mm, length 8000mm
Arrangement: spiral wound around the outer circumference of the inner pipe [Comparative example]
The configuration is the same as in the trial calculation example 1 except that the spacer has a circular cross-sectional shape. The spacer has a circular cross-sectional shape with a diameter of 3 mm and a cross-sectional area of 7.0686 mm ² .

[result]
When the spacer is pressed by the self-weight of the double structure pipe, the contact length in the circumferential direction of the double structure pipe is calculated at the contact point between the spacer and the outer pipe. mm. Further, when the cross-sectional area of the spacer at that time was calculated, it was 1.4445 mm ² in the trial calculation example 1, and 7.0875 mm ^{2 in} the comparative example.

  Trial calculation example 1 has a shorter contact length than the comparative example because the heat insulating tube of the present invention is located on the inner side of the imaginary straight line connecting the vertices, so that the spacer is It is considered that even if the double structure pipe is pressed by its own weight, the pressed portion does not have a wide flat area.

  Trial calculation example 1 using the heat insulating tube of the present invention has a contact length in the circumferential direction of the spacer and the outer tube of about 1/7 compared to the comparative example, and thus suppresses an increase in the amount of heat penetration from the outside. be able to. Moreover, since the cross-sectional area of the spacer is about 1/5 as compared with the comparative example, the trial calculation example 1 can be expected to reduce the constituent material of the spacer and suppress the increase of intrusion heat due to heat transfer.

  The above-described embodiments can be appropriately changed without departing from the gist of the present invention, and the scope of the present invention is not limited to the above-described configuration.

  The heat insulation pipe of the present invention can be used as a fluid transport pipe or the like that can cope with a wide range of temperatures of fluid flowing in the heat insulation pipe. A superconducting cable provided with the heat insulating tube of the present invention can be suitably used as a component of a power transmission line.

1 Insulated pipe
2 Double structure pipe
21 Inner pipe 22 Outer pipe
3 Spacer
31 Vertex 32 Side 33 Virtual line
4 Insulation
5 Vacuum layer
10 Superconducting cable
11 Cable core 12 Former
13 Superconducting conductor layer 14 Electrical insulating layer 15 External superconducting layer 16 Protective layer
17 Refrigerant flow path 18 Anticorrosion layer

Claims (5)

A heat insulating pipe in which a heat insulating material and a linear spacer are incorporated between the inner pipe and the outer pipe,
The cross-sectional shape of the spacer is a substantially polygonal shape surrounded by a plurality of sides, and has a plurality of vertices that are adjacent to each other and that protrude outward.
All the sides which connect the said adjacent vertexes are located inside the virtual straight line which connects the said vertexes, The heat insulation pipe | tube characterized by the above-mentioned.   The heat insulation pipe according to claim 1, wherein the number of the apexes is 3 to 5.   The heat insulation pipe according to claim 1 or 2, wherein an inner angle at the apex is an acute angle.   The heat insulation pipe according to any one of claims 1 to 3, wherein the cross-sectional shape is rotationally symmetric with respect to a central axis in a longitudinal direction. The heat insulation pipe according to any one of claims 1 to 4,
A superconducting cable comprising a cable core having a superconducting conductor and housed in the heat insulating tube.

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