Refrigerant pipe for cryogenic refrigerants

Abstract

To provide a lighter refrigerant pipe for flowing a cryogenic refrigerant (120 Kelvin or less). [Solution] By constructing at least one pipe material that constitutes a refrigerant pipe, in part or in whole, from an amorphous thermoplastic, the weight of the refrigerant pipe can be reduced compared to conventional refrigerant pipes that are constructed from metal members. Amorphous thermoplastics that can be used include polyethersulfone (PESU), polysulfone (PSU), polyphenylsulfone (PPSU), and other materials that have excellent cold resistance. Furthermore, because the pipe material is transparent or translucent, the status of the refrigerant flowing through it can be visually confirmed.

Description

[Technical Field]

[0001] The present invention relates to a refrigerant pipe for flowing a cryogenic refrigerant (120 Kelvin or less), and relates to a refrigerant pipe for a cryogenic refrigerant that can be used to cool the cable core of a superconducting cable, for example. [Background technology]

[0002] In recent years, the market for superconducting power transmission using superconducting cables is expected to expand, with applications including power transmission systems for air mobility, including next-generation electric aircraft. In superconducting cables, metal pipes or metal corrugated pipes are generally used as refrigerant pipes that form a flow path for a refrigerant (such as liquid nitrogen) to cool the cable core inside the cable (see Patent Document 1). However, when applying a power transmission system using superconducting cables to air mobility such as the electric aircraft mentioned above, further weight reduction of the superconducting cables is an issue that needs to be resolved in order to reduce the weight of the entire aircraft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-12775 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, one of the objects of the present invention is to provide a lighter refrigerant pipe for flowing a cryogenic refrigerant (120 Kelvin or less). [Means for solving the problem]

[0005] The present invention, which has been made to solve the above problems, is a refrigerant pipe for flowing a cryogenic refrigerant (below 120 Kelvin), characterized in that it has at least one pipe material, and that part or all of the pipe material is made of an amorphous thermoplastic plastic. In addition, in the present invention, polyethersulfone (PESU), polysulfone (PSU) or polyphenylsulfone (PPSU) can be used as the amorphous thermoplastic. In the present invention, the pipe material can be transparent or semi-transparent. In addition, in the present invention, the pipe material can be configured as a member having a corrugated shape. In the present invention, a heat insulating layer may be provided on the inner and / or outer surface of the pipe material. In the present invention, the inner and / or outer surface of the pipe material may be provided with a coating layer that suppresses gas permeation. In addition, the present invention may be configured such that the refrigerant pipe has a multi-pipe structure including the at least one pipe material. In the present invention, the refrigerant pipe may be a member that constitutes a flow path of a refrigerant for cooling a cable core of a superconducting cable. In addition, the present invention may also be a component that forms a flow path of a refrigerant for cooling a cable core of a superconducting cable used in a power transmission system for air mobility, including an electric aircraft using a superconducting motor. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a lighter refrigerant pipe for flowing a cryogenic refrigerant (120 Kelvin or less). [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view showing an example of the configuration of a refrigerant pipe according to the present invention. [Figure 2] Photograph showing the appearance of test specimen 1 during the liquid injection test. [Figure 3] 10 is a schematic cross-sectional view showing another example of the configuration of the refrigerant pipe according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0009] <1> Refrigerant pipe (Figure 1) The refrigerant pipe according to the present invention constitutes a flow path for a cryogenic (120 Kelvin or less) refrigerant (liquid nitrogen, liquid helium, liquid hydrogen, etc.), and can be used for a variety of purposes. Among these various uses, there are possible uses such as cooling the cable core of a superconducting cable used in a power transmission line, and as a pipe for transporting a refrigerant. The superconducting cable shown in Figure 1 has a double-tube structure with an inner tubular material (inner tube) and an outer tubular material (outer tube) as the tubular material according to the present invention, and the inner tube houses a cable core made of superconducting wire and serves as a flow path for a refrigerant. In addition, the space between the inner and outer pipes is kept in a vacuum state to create an insulating space, thereby suppressing heat conduction between the outside of the refrigerant pipe and the inner pipe that forms the refrigerant flow path.

[0010] <2> Pipe material In the present invention, amorphous thermoplastic plastic is used for part or all of the pipe material that constitutes part or all of the refrigerant pipe used for a specific application, as a material that has various usage characteristics (cold resistance, insulation, flexibility, rigidity, etc.) that do not interfere with use as a refrigerant pipe for that application, while being lighter than conventional metal refrigerant pipes. In the present invention, the proportion of amorphous thermoplastic plastic in the pipe material is not particularly limited, and the pipe material may be entirely made of amorphous thermoplastic plastic.

[0011] <2.1> Amorphous thermoplastics The amorphous thermoplastic that constitutes part or all of the pipe material used in the pipe material according to the present invention can be appropriately selected from polyethersulfone (PESU), polysulfone (PSU), polyphenylsulfone (PPSU), and the like. The density of these amorphous thermoplastics is approximately 1-3 g / cm 3 For example, the density of stainless steel (SUS304), which is commonly used as a refrigerant pipe for superconducting cables, is 7.93 g / cm 3 ) this contributes to reducing the weight of the refrigerant pipes.

[0012] An amorphous thermoplastic suitable for use as a material for the pipe material in the present invention is Ultrason (registered trademark) P, available from BASF Japan Ltd. Ultrason P is a polyphenylsulfone (PPSU) having the following chemical formula: [C1] TIFF2026043959000002.tif39145Ultrason P has excellent temperature stability and is also excellent in electrical insulation and mechanical strength, making it suitable for use in applications such as when the tubing material of the present invention is used as a refrigerant pipe for cooling the cable core of a superconducting cable. Furthermore, Ultrason P is a transparent resin, and uncolored products have high transmittance, making it suitable for visually checking the state of the refrigerant flowing through the pipe.

[0013] <3> Pipe shape In the present invention, the shape of the pipe material is not particularly limited, and various shapes can be adopted, such as a straight shape, a corrugated shape, or a shape in which the pipe thickness varies partially along the longitudinal direction of the pipe material.

[0014] <4> Number of pipes In the present invention, the number of pipe materials constituting the refrigerant pipe is not particularly limited, and any number can be adopted depending on factors such as the number of flow paths and whether or not a vacuum layer is secured. Therefore, the refrigerant pipe according to the present invention naturally includes a configuration in which at least one of the multiple pipe materials that make up the refrigerant pipe is made of an amorphous thermoplastic plastic.

[0015] <5> Adding outer and / or inner layers In the present invention, a layer made of a material different from the pipe material may be added to the outer peripheral surface side and / or inner peripheral surface side of the pipe material. These layers may include a layer having a heat insulating function and a layer that suppresses gas permeation. In the present invention, the method for forming these layers is not particularly limited, and methods such as molding resin, foaming resin formed by spraying on-site onto the pipe material, applying paint, and electroless plating are conceivable.

[0016] <6> Pipe weight When the refrigerant pipe of the present invention is used as a refrigerant pipe for a superconducting cable, it is preferable to select the material, shape, pipe thickness, etc. of the pipe so that the weight per unit length is at least 150 g / m or less when the inner diameter of the pipe is 20 mm or more, or at least 200 g / m or less when the inner diameter of the pipe is 35 mm or more.

[0017] <7> Performance test (liquid nitrogen injection test) (Figure 2) Liquid nitrogen was poured into the inner tube of the test piece 1 shown below, and the liquid transfer status was confirmed. [Test piece 1] ·Structure: Double tube structure (inner tube, outer tube) Material: Both inner and outer tubes are made of Ultrason P 3010 (polyphenylsulfone (PPSU)) Inner pipe shape: Corrugated (inner diameter: 21 mm, inner wave height: 2 mm, pipe thickness: 2 mm) Outer pipe shape: Corrugated (inner diameter: 27 mm, inner wave height: 2 mm, pipe thickness: 2 mm) Weight per unit length: 109g / m

[0018] As shown in Figure 2, after the liquid nitrogen was poured in, no breakage of the tubing or leakage of liquid nitrogen was observed. In addition, because this test specimen is a transparent material, it is advantageous in that it allows visual confirmation of the liquid nitrogen flow status (for example, whether it is full of liquid or not) inside the inner tube, compared to conventional metal pipe materials (opaque materials).

[0019] <8> Comparative Test When a metal pipe material applicable as a refrigerant pipe for a cryogenic refrigerant in a superconducting cable was designed to have at least the same level of usage characteristics (cold resistance, insulation, flexibility, rigidity, etc.) as those of the above-mentioned test specimen 1, the result was test specimen 2 as shown below.

[0020] [Test piece 2] ·Structure: Double tube structure (inner tube, outer tube) Material: Both inner and outer tubes are made of SUS304 Inner pipe shape: Corrugated (inner diameter: 32.5 mm, inner wave height: 2 mm, pipe thickness: 0.4 mm) Outer pipe shape: Corrugated (inner diameter: 41 mm, inner wave height: 2 mm, pipe thickness: 0.4 mm) Weight per unit length: 1185g / m

[0021] The weights per unit length of specimens 1 and 2 are shown in Table 1. [Table 1] TIFF2026043959000003.tif25151

[0022] As shown in Table 1, the weight per unit length of the inner and outer pipes that make up the double pipe structure was reduced by approximately 10% when the refrigerant pipe of the present invention was used compared to when conventional metal pipe material was used. Therefore, when the refrigerant pipe of the present invention is applied to a superconducting cable that constitutes a power transmission system in air mobility, including electric aircraft using superconducting motors, the total weight of the power transmission system can be reduced, which is beneficial in that it can suppress the increase in weight of the entire electric aircraft. [Example]

[0023] Another example of the configuration of the refrigerant pipe according to the present invention will be described with reference to FIG.

[0024] (1) Configuration example 1 (Figure 3(a)) The refrigerant pipe shown in Fig. 3(a) has a structure in which a heat insulating layer is provided on the outer surface of a pipe material made of a non-metallic member containing an amorphous thermoplastic, and the outer pipe and heat insulating space shown in Fig. 1 are omitted. With this structure, the volume of the superconducting cable can be reduced compared to the case of a double pipe structure as shown in Fig. 1.

[0025] (2) Configuration example 2 (Figure 3(b)) The refrigerant pipe shown in Figure 3(b) is a double-walled pipe (inner pipe, outer pipe) made of a non-metallic material containing amorphous thermoplastic plastic, with a coating layer on the outer surface of the outer pipe to suppress gas permeation. This configuration can suppress the outflow of nitrogen gas generated in the flow path and the inflow of gas from the outside of the outer pipe into the thermally insulated space.

[0026] (3) Configuration example (Fig. 3(c)) The refrigerant pipe shown in Fig. 3(c) has a double-pipe structure in which the inner pipe is made of a non-metallic material containing amorphous thermoplastic plastic, and the outer pipe is made of a metal pipe. This structure allows for partial weight reduction of the inner pipe that forms the refrigerant flow path. [Explanation of symbols]

[0027] A: Refrigerant pipe B: Cable core 10: Tube material 20: Flow path 30: Insulated space 40: Heat insulating layer 50: Covering layer 60: Metal tube

Claims

1. A refrigerant pipe for flowing a cryogenic refrigerant (120 Kelvin or less), At least one tubing A part or all of the pipe material is made of an amorphous thermoplastic plastic. Refrigerant pipe for cryogenic refrigerants.

2. The amorphous thermoplastic is made of polyethersulfone (PESU), polysulfone (PSU) or polyphenylsulfone (PPSU), The refrigerant pipe for cryogenic refrigerant according to claim 1.

3. The pipe material is transparent or translucent. The refrigerant pipe for cryogenic refrigerant according to claim 1.

4. The pipe material has a corrugated shape. The refrigerant pipe for cryogenic refrigerant according to claim 1.

5. A heat insulating layer is provided on the inner and / or outer surface of the pipe material. The refrigerant pipe for cryogenic refrigerant according to claim 1.

6. The pipe material is characterized in that a coating layer that suppresses gas permeation is provided on the inner and / or outer surface of the pipe material. The refrigerant pipe for cryogenic refrigerant according to claim 1.

7. The refrigerant pipe has a multi-pipe structure including the at least one pipe material. The refrigerant pipe for cryogenic refrigerant according to claim 1.

8. 2. The refrigerant pipe for a cryogenic refrigerant according to claim 1, wherein the refrigerant pipe is a member that constitutes a flow path of a refrigerant for cooling a cable core of a superconducting cable.

9. the refrigerant pipe is a member that constitutes a flow path of a refrigerant for cooling a cable core of a superconducting cable used in a power transmission system of air mobility including an electric aircraft using a superconducting motor, The refrigerant pipe for cryogenic refrigerant according to claim 1.

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