WO2019146269A1

WO2019146269A1 - Superconductive cable

Info

Publication number: WO2019146269A1
Application number: PCT/JP2018/045060
Authority: WO
Inventors: 茂樹礒嶋
Original assignee: 住友電気工業株式会社
Priority date: 2018-01-23
Filing date: 2018-12-07
Publication date: 2019-08-01

Abstract

This superconductive cable according to one aspect of the present disclosure is for transferring electric power among a plurality of electric power devices mounted on an aircraft. The superconductive cable is provided with: a heat insulation pipe; a sealed pipe which is disposed in the heat insulation pipe and in which a liquid coolant is sealed; and cores that each have a superconductive layer and that are housed in the sealed pipe.

Description

Superconducting cable

The present disclosure relates to a superconducting cable. This application claims priority based on Japanese Patent Application No. 2018-008944 filed on Jan. 23, 2018. The entire contents of the description of the Japanese patent application are incorporated herein by reference.

As a technique for cooling a superconducting cable, a technique for performing circulating cooling using a subcooled refrigerant is known. In this method, the refrigerant is cooled to the subcooling state using a refrigerator, and the cooled refrigerant is sent to the superconducting cable using the pump, whereby the superconducting cable is cooled by the refrigerant cooled to the subcooling state by the refrigerator The refrigerant that has been used to cool the superconducting cable is returned to the refrigerator again.

As described above, for example, Patent Document 1 discloses a technique for circulating a refrigerant in the order of a refrigerator → a superconducting cable → a pump → a refrigerator, and cooling the superconducting cable in a path of a single stroke.

Unexamined-Japanese-Patent No. 2016-100221

A superconducting cable according to an aspect of the present disclosure transports power between a plurality of power devices mounted on an aircraft. The superconducting cable is provided with a heat insulating pipe, a sealing pipe disposed in the heat insulating pipe, in which a liquid refrigerant is sealed, and a core housed in the sealing pipe and having a superconducting layer.

FIG. 1 is a schematic view showing an outline of an aircraft equipped with the superconducting cable according to the present embodiment. FIG. 2 is a schematic view of a superconducting cable disposed between two power devices mounted on the aircraft shown in FIG. FIG. 3 is a schematic cross-sectional view of the superconducting cable shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. FIG. 5 is a cross-sectional view showing the core shown in FIG. FIG. 6 is a view schematically showing a configuration example of the gas-liquid separation filter. FIG. 7 is a schematic cross-sectional view of the end portion of the superconducting cable shown in FIG. FIG. 8 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG. FIG. 9 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG. FIG. 10 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG. FIG. 11 is a view schematically showing the process of filling the inside of the sealing tube with liquid nitrogen. FIG. 12 is a view schematically showing a process of filling the inside of the terminal portion with liquid nitrogen. FIG. 13 is a view schematically showing temporal changes in the temperature and amount of liquid nitrogen present in the inside of the sealing tube.

[Problems to be solved by the present disclosure]
An object of an aspect of the present disclosure is to provide a superconducting cable which transports power between a plurality of power devices mounted on an aircraft, and which has a novel configuration suitable for weight reduction.
[Effect of the present disclosure]
According to the present disclosure, it is possible to provide a superconducting cable that transports power between a plurality of power devices mounted on an aircraft, and which has a novel configuration suitable for weight reduction.

[Description of the embodiment of the present disclosure]
First, embodiments of the present disclosure will be listed and described.

(1) The superconducting cable 100 (see FIGS. 2 to 4) according to an aspect of the present disclosure transports power between a plurality of power devices mounted on the aircraft 1000. The superconducting cable 100 includes a heat insulating pipe 36, a sealing pipe 30 disposed in the heat insulating pipe 36, in which the liquid refrigerant 20 is sealed, and a core 10 housed in the sealing pipe 30 and having a superconducting layer 13 (see FIG. 1).

According to the superconducting cable 100 according to the above (1), the core 10 is cooled using the latent heat of vaporization of the liquid refrigerant 20 sealed in the sealing tube 30. Therefore, a refrigerator for cooling the liquid refrigerant to a supercooled state, a pump for circulating the liquid refrigerant, and the liquid refrigerant, as compared with the conventional superconducting cable cooling technology in which the core is cooled by using the subcooled refrigerant. This eliminates the need for a cooling system consisting of a reservoir tank or the like that stores Therefore, when the superconducting cable is applied to a power cable for transporting electric power in an aircraft, it is not necessary to construct a cooling system for the superconducting cable in the aircraft 1000, so the weight of the power cable can be reduced. Therefore, a superconducting cable suitable for a power cable for aircraft can be provided.

(2) In the superconducting cable 100 which concerns on said (1), the core 10 (refer FIG. 5) further has the heat conductive layer 16 in outermost periphery.

According to this, by providing the heat conduction layer 16 on the outermost periphery of the core 10, even though the liquid refrigerant remaining in the adiabatic pipe is reduced by evaporation of the liquid refrigerant 20, the heat conduction layer 16 is passed through. The entire core can be cooled by the liquid refrigerant 20. Thus, the core can be constantly cooled and maintained in the superconducting state while the aircraft 1000 is in operation.

(3) In the superconducting cable 100 according to the above (1) or (2), a plurality of partition members 30A for dividing the inside of the sealing tube 30 into a plurality of sections along the longitudinal direction of the core 10 inside the sealing tube 30 Is placed. Each of the plurality of partition members 30A is formed with a through hole through which the core 10 passes.

According to this, the liquid refrigerant 20 sealed inside the sealing tube 30 is divided into a plurality of spaces and sealed. Therefore, even if the superconducting cable 100 is inclined at an angle close to perpendicular to the ground with the change in the attitude of the aircraft 1000, the liquid refrigerant 20 is collected on the lower side in the direction of gravity for each space, so The pressure applied to the enclosing tube 30 can be reduced as compared to the case where the inside of the tube 30 is a single space. In addition, since the occurrence of the deviation of the liquid refrigerant 20 inside the sealing tube 30 is suppressed, the state of the liquid refrigerant 20 becomes substantially uniform over the longitudinal direction of the core 10, so the core 10 is cooled substantially evenly. Can.

(4) In the superconducting cable 100 according to the above (1) or (2), a gas-liquid separation for discharging the gas refrigerant, which is disposed on the outer peripheral surface of the sealing pipe 30 and vaporized the liquid refrigerant 20 to the outside of the sealing pipe 30 It further comprises a filter 40 (see FIGS. 3 and 6).

In this way, it is possible to suppress an increase in the refrigerant pressure in the sealing pipe 30 due to the gas refrigerant generated by the evaporative cooling of the core 10.

(5) In the superconducting cable 100 according to (3), the gas-liquid separation filter 40 disposed on the outer peripheral surface of the sealing tube 30 for discharging the gas refrigerant vaporized of the liquid refrigerant 20 to the outside of the sealing tube 30 is further provided. Prepare. The gas-liquid separation filter 40 is provided corresponding to each of the plurality of sections (see FIGS. 3 and 6).

In this way, in each of the plurality of sections formed in the inside of the sealing pipe 30, it is possible to suppress an increase in the refrigerant pressure due to the generation of the gas refrigerant.

(6) In the superconducting cable 100 according to the above (4) or (5), the gas flow path 31 (see FIG. 4) disposed on the outer periphery of the sealing tube 30 for discharging the gaseous refrigerant to the outside of the superconducting cable 100 Further equipped.

In this way, the gas refrigerant discharged from the gas-liquid separation filter 40 is discharged to the outside of the superconducting cable 100 via the gas flow path 31, so that the internal pressure of the superconducting cable 100 is prevented from rising. it can.

(7) In the superconducting cable 100 according to (1) to (6) above, the heat insulating pipe is filled with the liquid refrigerant cooled to the boiling point or a temperature equal to or lower than the boiling point.

In this way, since the core 10 can be cooled using the sensible heat and the evaporation latent heat of the liquid refrigerant, more liquid refrigerant is used than when the core 10 is cooled using the evaporation latent heat alone. It can absorb heat. Therefore, even when the operation time of the aircraft 1000 is long or the Joule loss (heat loss) generated in the power cable is large, the core 10 can be constantly cooled and maintained in the superconducting state.

(8) In the superconducting cable 100 according to the above (1) to (7), the core 10 is disposed on the hollow spiral former 12, the superconducting layer 13 disposed on the outer periphery of the former 12, and the outer periphery of the superconducting layer 13 And the shield layer 15 disposed on the outer periphery of the insulating layer 14.

As a result, the liquid refrigerant 20 is filled in the hollow portion of the former 12 and the space formed between the outer periphery of the core 10 and the inner side of the sealing tube 30, so that the superconducting layer 13 and the shield layer 15 of the core 10 are filled. Can be cooled efficiently.

(9) The superconducting cable 100 according to (8) further includes a connecting member 210 for connecting the tank 200 storing the liquid refrigerant to the former 12 (see FIG. 11). The connection member 210 is opened when the tank 200 is connected, and connects the inside of the tank 200 and the hollow portion of the former 12 while it is closed when the tank 200 is not connected, and the hollow portion of the former 12 is sealed. It is configured to stop.

As a result, the tank 200 is detachably connected to the former 12 of the core 10 via the connection member 210. Therefore, by connecting the tank 200 to the former 12 before takeoff of the aircraft, it is possible to fill the inside of the sealed tube 30 with the liquid refrigerant through the former 12. Further, when the tank 200 is removed from the former 12 after filling with the liquid refrigerant, the connection member 210 is closed and the former 12 is sealed, so the liquid refrigerant is confined in the sealing pipe 30 during operation of the aircraft. Can.

(10) The superconducting cable 100 according to (1) to (9) above further includes a terminal unit 120 for housing the terminal of the core 10 (see FIG. 7). The terminal unit 120 includes a refrigerant container 124 that holds the liquid refrigerant 20 and the terminal of the core 10 therein, and a sealing member 128 that seals the liquid refrigerant inlet 126 formed in the refrigerant container 124.

Thus, before takeoff of the aircraft, the liquid refrigerant is injected from the inlet 126 into the refrigerant container 124, and after the refrigerant container 124 is filled with the liquid refrigerant, the inlet 126 is sealed using the sealing member 128. Thus, the liquid refrigerant can be confined in the refrigerant container 124 during operation of the aircraft.

(11) The superconducting cable 100 according to (10) further includes a gas-liquid separator 130 disposed at the end portion 120 and discharging the gas refrigerant having the liquid refrigerant vaporized out of the refrigerant container 124 (FIG. 7) reference).

In this way, it is possible to suppress an increase in the refrigerant pressure in the refrigerant container 124 due to the gas refrigerant generated by the cooling of the end of the core 10.

(12) In the superconducting cable 100 which concerns on said (11), the gas-liquid separator 130 (refer FIG. 7) has the pressure control valve 132 arrange | positioned at the exit of gaseous refrigerant.

Thus, the pressure regulating valve 132 can maintain the differential pressure between the refrigerant pressure in the cooling container 124 and the external pressure. Therefore, even when the attitude of the airframe is inclined during operation of the aircraft and the refrigerant pressure is increased, the gaseous refrigerant can be discharged without flowing out the liquid refrigerant from the inside of the refrigerant container 124.

(13) In the superconducting cable 100 according to the above (1) to (12), the liquid refrigerant is liquid nitrogen.

In this way, it is possible to realize a reduction in weight and cost of a superconducting cable that transports power between a plurality of power devices mounted on an aircraft. The liquid refrigerant may be liquid hydrogen, but in that case an explosion proof design is required.

Details of Embodiments of the Present Disclosure
Hereinafter, embodiments of the present disclosure will be described based on the drawings. In the following drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated.

(Example of application of superconducting cable)
First, with reference to FIG. 1, an example of a scene where the superconducting cable 100 according to the present embodiment is applied will be described. FIG. 1 is a schematic view showing an outline of an aircraft 1000 on which the superconducting cable 100 according to the present embodiment is mounted. The aircraft 1000 is a hybrid electric aircraft using an engine and a motor as a power source.

Superconducting cable 100 according to the present embodiment is applied to a power cable for transporting power between a plurality of power devices mounted on aircraft 1000. In the example of FIG. 1, the aircraft 1000 is equipped with a plurality of power devices such as a generator 102, a motor 106,

power converters

104 and 108, a power distributor 110, and a power storage device 112. In FIG. 1, the motor 106 is shown for only one of the four engines. The superconducting cable 100 is disposed between these power devices to transport power.

The power cables mounted on the aircraft 1000 may have a total length of several tens of meters. When this power cable is constituted by an existing normal conducting cable (for example, OF cable or CV cable), for example, of the power cable for transporting 4 MW three-phase AC power (AC frequency 400 Hz, rated voltage 230 V, rated current 10 kA) The weight is about 15 tons. Assuming two lines per motor, the total weight of the power cable is about 60 tons when replacing the two engines with the motor, and the ratio of the weight of the power cable to the total weight of the aircraft 1000 can not be ignored It can be a level.

In recent years, in power cables used for power facilities such as substations, development for practical use of superconducting cables is in progress. A superconducting cable has a smaller power transmission loss than a conventional normal conducting cable and can flow a large current, so that a lightweight and compact power cable can be realized. Therefore, from the viewpoint of reducing the weight of the power cable, application of the superconducting cable to a power cable for aircraft is expected.

Here, a superconducting cable typically employs a structure in which a core having a superconducting layer is accommodated in a heat insulating pipe, and the core is cooled by circulating liquid refrigerant (for example, liquid nitrogen) in the heat insulating pipe. . In such a cooling structure, usually, a cooling system is connected to the superconducting cable, and the operation is performed by supplying and circulating the liquid refrigerant from the cooling system into the heat insulating pipe. The cooling system includes a refrigerator for cooling the liquid refrigerant, a pump for pumping the liquid refrigerant, a reservoir tank for storing the liquid refrigerant, and the like, and constitutes a refrigerant flow path for circulating the liquid refrigerant together with the heat insulation pipe of the superconducting cable. . The liquid refrigerant cooled by the refrigerator is fed into the heat insulating pipe, and the core is cooled by circulating the liquid refrigerant by the pump.

Therefore, when the superconducting cable is applied to a power cable for an aircraft, it is necessary to construct the cooling system described above in the aircraft 1000. According to this, the weight of the cooling system is increased, and there is a concern that sufficient benefits can not be obtained from the viewpoint of weight reduction.

In the present embodiment, the configuration of a superconducting cable suitable as a power cable for an aircraft will be described.

(Superconducting cable)
Next, the configuration of the superconducting cable 100 according to the present embodiment will be described.

First, the overall configuration of the superconducting cable 100 will be described with reference to FIG. FIG. 2 is a schematic view of a superconducting cable 100 disposed between two power devices mounted on the aircraft 1000 shown in FIG.

As shown in FIG. 2, the superconducting cable 100 includes a core 10 having a superconducting layer. The core 10 is housed inside the heat insulating pipe 36. Specifically, the core 10 is disposed in the heat insulating pipe 36 and is housed in the sealing pipe 30 in which the liquid refrigerant is sealed. The superconducting cable 100 is used in a state in which the core 10 is cooled to a cryogenic temperature with a liquid refrigerant. In the following description, liquid nitrogen is used as the liquid refrigerant. Nitrogen has a melting point of about 63.1 K and a boiling point of about 77.3 K (atmospheric pressure).

The number of cores 10 stored in the heat insulation pipe 36 may be a single core or a plurality of cores. In the following description, a three-core batch type three-phase AC cable in which the three-core core 10 is twisted and housed in the heat insulation pipe 36 is exemplified.

The superconducting cable 100 has end portions 120 at both ends in the longitudinal direction. The terminal unit 120 accommodates the terminal in the longitudinal direction of the core 10. Inside the terminal unit 120, the terminal of the core 10 is electrically connected to the electrode 122. The electrode 122 is electrically connected to a power device (not shown). The electrode 122 is formed of, for example, a conductive material such as a metal having a low electric resistance value near the temperature of liquid nitrogen, such as copper or aluminum.

As described later, in the core 10, the terminals and the wire portions other than the terminals are cooled by separate cooling structures.

FIG. 3 is a schematic cross-sectional view of the superconducting cable 100 shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. FIG. 5 is a cross-sectional view showing the core 10 shown in FIG.

As shown in FIGS. 3 and 4, the superconducting cable 100 has a three-core core 10, a sealing pipe 30, a gas flow path 31, a corrugated inner pipe 32, a vacuum layer 33 and a corrugated outer pipe 34. , Reinforcement layer (anticorrosion layer) 35 mainly. The corrugated inner pipe 32, the vacuum layer 33, the corrugated outer pipe 34 and the reinforcing layer 35 constitute a heat insulating pipe 36.

As shown in FIG. 5, the core 10 mainly includes a former 12, an inner superconducting layer 13, an insulating layer 14, an outer superconducting layer 15, and a heat conducting layer 16 in this order from the inside.

The former 12 maintains mechanical properties such as stiffness and bending properties of the core 10. The former 12 has a hollow structure, and a spiral tube formed by spirally winding an elongated plate made of a metal (for example, copper or aluminum) having high thermal conductivity can be suitably used. The former 12 is also used as a flow path of liquid nitrogen 20 as described later. In the former 12, the inner peripheral side and the outer peripheral side of the spiral pipe are in communication, and the liquid nitrogen 20 can be circulated between the inner peripheral side and the outer peripheral side.

The inner superconducting layer 13 is disposed on the outer periphery of the former 12. The inner superconducting layer 13 constitutes a power transmission path. As the inner superconducting layer 13, for example, a tape-shaped wire provided with an oxide superconductor can be suitably used. As the tape-shaped wire, for example, a Bi2223-based superconducting tape wire or an RE123-based thin film wire can be used. Examples of the Bi2223-based superconducting tape wire include a sheath wire in which a filament made of a Bi2223-based oxide superconductor is disposed in a stabilized metal such as Ag—Mn or Ag. The Bi2223 superconductor has a Bi2223 phase represented by a ratio of (Bismuth and Lead): Strontium: Calcium: Copper at an approximate ratio of 2: 2: 2: 3 as the main phase, with the balance being the Bi2212 phase and the Bi2223 phase. It means a material consisting of unavoidable impurities. Examples of the RE123-based thin film wire include a laminated wire in which an oxide superconducting phase of a rare earth element RE such as Y (yttrium), Ho (phornium), Sm (samarium), and Gd (gadolinium) is formed on a metal substrate. The RE123-based superconductor means a superconductor represented as REBa ₂ Cu ₃ O _y (y is 6 to 8, more preferably 7). The thing of the single layer structure formed by winding the said tape-shaped wire material helically, or a multilayer structure is mentioned. Although illustrated in a simplified manner in FIG. 5, the superconducting layer 13 has a multilayer structure.

Insulating layer 14 is a layer for securing the insulation required for the working voltage in internal superconducting layer 13. For the insulating layer 14, an insulating paper through which liquid nitrogen can pass can be suitably used.

In a conventional superconducting cable, when the superconducting layer has a multilayer structure, an interlayer insulating layer is provided by winding kraft paper or the like between layers in order to reduce AC loss. In addition, in order to achieve high dielectric strength, insulating paper such as polypropylene laminated paper (PPLP (registered trademark)) is impregnated with liquid nitrogen to ensure electrical insulation. Therefore, conductive cooling of the core 10 is performed using liquid nitrogen and insulating paper. However, when liquid nitrogen is vaporized and nitrogen gas is generated, a thick insulating layer prevents the conduction cooling performance to about 1/20.

On the other hand, in the case of transmitting a three-phase AC power having an AC frequency of 400 Hz, a rated voltage of 230 V and a rated current of 10 kA, the insulating layer 14 needs to have a thickness of about 24 μm. For this, the insulating layer 14 can be formed, for example, by gap winding of insulating paper having a thickness of 135 μm. In the case of a power cable for a substation with a rated voltage of 66kV, the thickness of the insulating layer can be reduced to about 1/50 compared to requiring an insulating layer having a thickness of about 7mm, so nitrogen gas is generated Even conductive cooling can be performed.

In addition, since the insulating layer 14 needs to have a thickness of about 24 μm, the insulating layer 14 can be formed of thin insulating paper, so that liquid nitrogen can pass through the insulating layer 14. According to this, in the step of filling the inside of the sealing tube 30 with liquid nitrogen, liquid nitrogen can be supplied from the inside (former portion) of the core 10.

The outer superconducting layer 15 is disposed on the outer periphery of the insulating layer 14. As the outer superconducting layer 15, a tape-shaped wire including an oxide superconductor as in the case of the inner superconducting layer 13 can be suitably used. The oxide superconductor used for the outer superconducting layer 15 may be the same as that used for the formation of the inner superconducting layer 13. When the superconducting cable 100 is a three-phase AC cable, the outer superconducting layer 15 can be used as a shield layer for flowing a shield current induced by the current flowing in the inner superconducting layer 13.

The heat conduction layer 16 is disposed on the outer periphery of the outer superconducting layer 15. The heat conduction layer 16 is disposed at the outermost periphery of the core 10. The heat conduction layer 16 is for transferring the heat generated in the core 10 to the liquid refrigerant 20 filled in the sealing tube 30. The heat conductive layer 16 can be formed, for example, by spirally winding a tape-shaped wire having high heat conductivity.

Returning to FIG. 3 and FIG. 4, the enclosing tube 30 houses the core 10 (excluding the terminal). Copper, stainless steel, aluminum (alloy) or the like can be suitably used as the material of the sealing tube 30. Liquid nitrogen 20 is sealed in the inside of the sealing tube 30.

Inside the encapsulation tube 30, the core 10 is cooled using liquid nitrogen 20. Sensible heat and latent heat of vaporization are used to cool the core 10. Specifically, sensible heat is utilized until the liquid nitrogen 20 reaches the boiling point (77.3 K) from the initial temperature, and the latent heat of vaporization is utilized after the liquid nitrogen 20 reaches the boiling point.

Furthermore, as shown in FIG. 5, the outermost periphery of the core 10 is covered with the heat conduction layer 16. Even in a state where the amount of liquid nitrogen 20 remaining in the sealing tube 30 is reduced, conduction cooling of the core 10 can be efficiently performed by contacting the heat conductive layer 16 with the liquid nitrogen 20.

During the period from the takeoff to the landing of the aircraft 1000, the liquid nitrogen 20 is heated by the AC loss generated in the core 10 and the heat entering from the outside of the enclosed tube 30. Here, liquid nitrogen has a sensible heat of 28.8 kJ / kg (at a temperature difference from the melting point to the boiling point) and a latent heat of vaporization of 199.1 kJ / kg. Before takeoff of the aircraft 1000, the liquid nitrogen filled in the enclosed tube 30 is cooled to the melting point (63. 1 K) by circulating cooling and conduction cooling with an external refrigerator. After takeoff of the aircraft 1000, the temperature of the liquid nitrogen 20 is raised to the boiling point with the melting point as the initial temperature, and thereafter maintained at a temperature near the boiling point until all the liquid nitrogen 20 in the enclosing tube 30 is vaporized. The enclosed tube 30 is filled with liquid nitrogen 20 in an amount necessary to cool the core 10 to a superconducting state, based on the loss that occurs in the period from the takeoff to the landing of the aircraft 1000. For example, if the time when the load is 100% is 24 hours and the time when the load is 33% is 23 hours, the amount of liquid nitrogen to be initially stored is about 750 kg. According to this, it is possible to prevent all the liquid nitrogen 20 in the enclosed tube 30 from being vaporized before the aircraft 1000 lands. Note that the internal diameter of the sealing tube 30 is determined based on the amount of liquid nitrogen 20 filling the sealing tube 30, the entire length of the core 10, and the like, so that the capacity of the sealing tube 30 can be increased while securing predetermined cooling. The accompanying enlargement of the superconducting cable 100 can be avoided.

A plurality of partition members 30A are disposed in the inside of the enclosing tube 30 along the longitudinal direction of the superconducting cable 100. The interior of the enclosing pipe 30 is divided into a plurality of spaces by the plurality of partition members 30A. For example, the partition members 30A are arranged at equal intervals at predetermined pitches of the three-core core 10. The predetermined pitch is, for example, about 1 m.

While the aircraft 1000 is operating, the aircraft 1000 can assume various attitudes. For example, if the aircraft 1000 is inclined at an angle close to perpendicular to the ground, the superconducting cable 100 may also incline at an angle close to perpendicular to the ground. In such a case, the liquid nitrogen 20 in the inside of the enclosing tube 30 gathers downward according to gravity. In the case where there is no partition member 30A inside the enclosing tube 30 and it is a single space, the liquid nitrogen 20 is collected downward in the direction of gravity. This state can be compared with the state in which the elongated container contains liquid nitrogen 20. Therefore, in the sealing tube 30 serving as the container, a pressure corresponding to the depth from the liquid surface of the liquid nitrogen 20 is applied to the portion located on the lower side in the direction of gravity. Since the pressure increases as the length of the sealing tube 30 increases, the sealing tube 30 needs to be robust enough to withstand the pressure. As a result, there is a concern that the sealing tube 30 has a large and heavy structure.

On the other hand, in the present embodiment, since the inside of the sealing tube 30 is divided into a plurality of spaces by the partition member 30A, the liquid nitrogen 20 is divided into a plurality of spaces and sealed. Therefore, when the superconducting cable 100 is inclined at an angle close to perpendicular to the ground, the liquid nitrogen 20 is collected downward in the direction of gravity in each space, and thus added to the enclosing tube 30 as compared with the case without the partition member 30A. The pressure can be reduced.

In the absence of the partition member 30A, when the superconducting cable 100 is inclined at an angle close to perpendicular to the ground, the liquid nitrogen 20 is biased inside the sealing tube 30, so the liquid nitrogen 20 is in the longitudinal direction of the core 10. There may be parts that do not touch. Since this portion is not cooled by the liquid nitrogen 20, uniform cooling over the entire length of the core 10 becomes difficult. In the present embodiment, by arranging the partition member 30A, it is possible to suppress the occurrence of the deviation of the liquid nitrogen 20 inside the sealing tube 30. Since the state of the liquid refrigerant 20 becomes substantially uniform over the longitudinal direction of the core 10, the core 10 can be cooled substantially uniformly.

A gas-liquid separation filter 40 is disposed on the outer peripheral surface of the sealing tube 30. The gas-liquid separation filter 40 is disposed corresponding to each of the plurality of spaces. The gas-liquid separation filter 40 discharges nitrogen gas to the outside of the sealing tube 30 while suppressing the outflow of the liquid nitrogen 20 from the sealing tube 30 by using the permeability of the membrane. FIG. 6 is a view schematically showing a configuration example of the gas-liquid separation filter 40. As shown in FIG. In the example of FIG. 6, the gas-liquid separation filter 40 includes a sheet-like filter 42 and reinforcing

members

41 and 43.

The filter 42 has a property of transmitting a gas while collecting a liquid. Although the type of the filter 42 is not particularly limited, it may be made of, for example, a microporous porous material, a nonwoven fabric, or a laminate of polyester fibers or the like. The filter 42 may be a simple mesh structure.

As described above, since the core 10 is evaporated and cooled using the liquid nitrogen 20 inside the sealing tube 30, the liquid nitrogen 20 is vaporized to generate nitrogen gas. The nitrogen gas passes through the gas-liquid separation filter 40 and is discharged to the outside of the sealing pipe 30.

A corrugated inner pipe 32 is disposed on the outer periphery of the sealing pipe 30. The corrugated inner pipe 32 has, for example, a corrugated cylindrical shape made of stainless steel. A space between the sealing pipe 30 and the corrugated inner pipe 32 is used as a gas flow path 31 for discharging nitrogen gas to the outside of the superconducting cable 100.

A corrugated outer pipe 34 is disposed on the outer circumference of the corrugated inner pipe 32. The space between the corrugated inner pipe 32 and the corrugated outer pipe 34 is a vacuum layer 33 and is used as an adiabatic space. This space may be filled with a heat insulating material.

A reinforcing layer 35 (anticorrosion layer) is disposed on the outer periphery of the corrugated outer tube 34. The reinforcing layer 35 is formed of, for example, polyvinyl chloride or the like.

FIG. 7 is a schematic cross-sectional view of the terminal portion 120 of the superconducting cable 100 shown in FIG. As shown in FIG. 7, the terminal portion 120 is in the form of a vacuum insulation container, and has a refrigerant container 124 for holding the liquid nitrogen 20 and the terminal of the core 10 inside, and an outer part arranged to surround the refrigerant container 124. And a tank (outer tank). A certain gap exists between the refrigerant container 124 and the outer tank, and by setting the gap in a vacuum, it is possible to suppress the transfer of heat from the outer tank side to the refrigerant container side.

In order to supply the liquid refrigerant 20 to the inside of the refrigerant container 124, an inlet 126 for the liquid refrigerant 20 is formed in the terminal portion 120. When the inside of the refrigerant container 124 is filled with the liquid refrigerant 20, the inlet 126 is sealed by the sealing member 128. Thus, the liquid refrigerant 20 can be confined inside the refrigerant container 124.

During operation of the aircraft 1000, the terminals of the core 10 are cooled to the superconducting state by the liquid nitrogen 20 in the refrigerant vessel 124. When liquid nitrogen 20 is vaporized and nitrogen gas is generated inside the refrigerant container 124, the pressure of the refrigerant in the refrigerant container 124 is increased and the temperature of the refrigerant is increased. Therefore, it is necessary to discharge the nitrogen gas. Therefore, as shown in FIG. 7, the gas-liquid separator 130 is connected to the terminal unit 120. A pressure control valve 132 is disposed at the gas outlet of the gas-liquid separator 130.

During operation of the aircraft 1000, the refrigerant pressure in the refrigerant container 124 may increase due to the attitude of the airframe being inclined. Since the outside of the refrigerant container 124 is at atmospheric pressure or lower than atmospheric pressure, in such a case, there is a risk that both liquid nitrogen 20 and nitrogen gas may be discharged from the gas outlet of the gas-liquid separator 130. The pressure control valve 132 is installed at the gas outlet, and can maintain the pressure difference between the refrigerant pressure in the refrigerant container 124 and the external pressure. Thus, the nitrogen gas can be efficiently discharged to the outside of the refrigerant container 124 without flowing out the liquid nitrogen 20 from the refrigerant container 124, including the case where the airframe is greatly inclined.

8 to 10 are cross-sectional views schematically showing a configuration example of the gas-liquid separator 130 shown in FIG. In the gas-liquid separator 130, generally, a gas-liquid separator using centrifugal force (FIG. 8), a gas-liquid separator using surface tension (FIG. 9), and a gas-liquid separation coalescer (FIG. 10) And so on can be used.

FIG. 8 is a cross-sectional view schematically showing the structure of a centrifugal gas-liquid separator. As shown in FIG. 8, a gas-liquid two-phase inlet 140 into which a gas-liquid two-phase refrigerant flows is provided on the side of the separator body 143. A gas outlet 141 from which gas is output is provided at the top of the separator body 143, and a liquid outlet 142 from which liquid is output is provided at the bottom of the separator body 143. A spiral flow passage is formed inside the separator body 143, and one end of the spiral flow passage communicates with the gas-liquid two-phase inlet 140. A liquid outlet 142 is provided on the other end side of the spiral flow channel and in communication with the outer peripheral side portion of the spiral flow channel viewed from the axial direction of the spiral flow channel, and viewed from the axial direction of the spiral flow channel A gas outlet 141 is provided to communicate with the inner peripheral side portion of the helical flow passage.

The gas-liquid two-phase refrigerant flowing from the gas-liquid two-phase inlet 140 is given a swirling component by a spiral flow path, and is separated into liquid nitrogen and nitrogen gas by its centrifugal force. That is, since liquid nitrogen having a large specific gravity is subjected to a larger centrifugal force, it gathers on the outer peripheral side of the spiral channel, while nitrogen gas having a small specific gravity collects on the other part, that is, the inner peripheral side of the spiral channel. It will be.

FIG. 9 is a cross-sectional view schematically showing the structure of a surface tension type gas-liquid separator. As shown in FIG. 9, a gas-liquid two-phase inlet 140 is provided at the top of the separator body 143, a gas outlet 141 is provided at the side of the separator body 143, and a lower portion of the separator body 143. A liquid outlet 142 is provided.

A bellows-like groove 144 is formed on the inner peripheral surface of the separator body 143. Between the upper portion of the groove 144 and the gas-liquid two-phase inlet 140, the gas-liquid two-phase flow is guided to the groove 144, and the gas released from the groove 144 is prevented from backflowing to the gas-liquid two-phase inlet 140 The partition 143A for doing is arranged. Between the lower portion of the groove 144 and the gas outlet 141 and the liquid outlet 142, a partition 143B for guiding the gas and liquid having passed through the groove 144 to the respective outlets is disposed.

When the gas-liquid two-phase refrigerant flows in from the upper portion of the bellows-like groove portion 144, the gas-liquid two-phase refrigerant contacts the groove portion 144. The gas-liquid two-phase refrigerant in contact with the groove 144 is separated into liquid nitrogen and nitrogen gas by the surface tension of the liquid nitrogen. The separated liquid nitrogen is collected after flowing along the groove 144 and flows out from the liquid outlet 142. Nitrogen gas is exhausted from the gas outlet 141.

FIG. 10 is a cross-sectional view schematically showing the structure of the gas-liquid separation coalescer. As shown in FIG. 10, inside the separator main body 143, a coalescer cartridge 145 having a microfiber structure is installed. The gas-liquid two-phase refrigerant flowing from the gas-liquid two-phase inlet 140 flows into the coalescer cartridge 145. While passing through the coalescer cartridge 145, liquid nitrogen contained in the gas-liquid two-phase refrigerant is separated and collected at the lower part of the separator body 143. Liquid nitrogen flows out of a liquid outlet 142 provided at the bottom of the separator body 143. After passing through the coalescer cartridge 145, the nitrogen gas is exhausted from a gas outlet 141 provided on the top of the separator body 143.

(Example of operation of superconducting cable)
Next, an operation example of the superconducting cable 100 according to the present embodiment will be described.

First, before the takeoff of the aircraft 1000, the inside of the enclosed tube 30 and the terminal portion 120 is filled with liquid nitrogen. FIG. 11 is a view schematically showing the process of filling the inside of the sealing tube 30 with liquid nitrogen.

As shown in FIG. 11, the superconducting cable 100 includes a connecting member 210 for connecting a tank 200 in which liquid nitrogen is stored to the former 12. The connection member 210 is provided at the terminal of the core 10.

The connecting member 210 is opened when the tank 200 is connected to the former 12, and is closed when the former 12 and the tank 200 are disconnected, while connecting the inside of the tank 200 with the hollow portion of the former 12 , And the hollow portion of the former 12 is sealed.

A refrigerator 202 is connected to the tank 200. The liquid nitrogen in the tank 200 is cooled to a temperature equal to or lower than the boiling point (77.3 K) or the refrigerator 202. The liquid nitrogen is pressed into the former 12 and filled in the sealing tube 30. Thereafter, liquid nitrogen may be circulated to the external refrigerator to further reduce the temperature, and then it may be cooled to a temperature close to the melting point (63. 1 K) by conductive cooling. As the refrigerator 202, a small cryogenic refrigerator represented by a GM refrigerator (Gifford McMahon refrigerator) or the like is used. The compressor 204 is connected to the refrigerator 202 via a circulating refrigerant pipe.

In the process of filling liquid nitrogen into the sealing tube 30, the connection member 210 is opened, and the inside of the tank 200 and the hollow portion of the former 12 communicate with each other, so that the tank 200 to the inside of the former 12 of the core 10 are formed. Is injected with liquid nitrogen. When the inside of the sealing tube 30 is fully filled with liquid nitrogen, the injection of liquid nitrogen is stopped.

FIG. 12 is a view schematically showing a process of filling the inside of the terminal unit 120 with liquid nitrogen. As shown in FIG. 12, liquid nitrogen 20 is injected from the tank 200 into the inside of the refrigerant container 124 through the injection port 126 of the terminal portion 120.

When the inside of the refrigerant container 124 is filled with the liquid refrigerant 20, the inlet 126 is sealed by the sealing member 128 (see FIG. 7).

FIG. 13 is a view schematically showing temporal changes in the temperature and amount of liquid nitrogen present in the inside of the sealing tube 30. As shown in FIG.

As shown in FIG. 13, the inside of the sealing tube 30 is fully filled with liquid nitrogen at time t1. In the example of FIG. 13, the liquid nitrogen is cooled to a temperature close to the melting point.

After the aircraft 1000 takes off at time t2 after time t1, the liquid nitrogen is heated by AC loss and heat of external penetration generated in the core 10. The temperature of liquid nitrogen gradually rises from around the melting point (63. 1 K). The core 10 is cooled using the sensible heat of liquid nitrogen. When the temperature of liquid nitrogen reaches the boiling point at time t3 after time t2, the transition from conduction cooling to evaporation cooling is made. In evaporative cooling, since the core 10 is cooled using the latent heat of liquid nitrogen, the temperature of liquid nitrogen is maintained near the boiling point. The nitrogen gas generated by the evaporative cooling is discharged from the gas-liquid separation filter 40 to the outside of the sealing pipe 30. After time t3, the amount of liquid nitrogen gradually decreases. When the aircraft 1000 lands at time t4, most of the liquid nitrogen in the enclosed tube 30 has been vaporized. After time t4, in preparation for the operation of the aircraft 1000, the supply of liquid nitrogen to the sealing tube 30 is performed again.

As described above, according to the superconducting cable 100 according to the present embodiment, since the core 10 is cooled using the latent heat of evaporation of the liquid nitrogen 20 sealed in the sealing tube 30, it is possible to use the supercooled refrigerant. As compared with the conventional superconducting cable cooling technology that performs core cooling, there is no need for a cooling system for cooling the liquid refrigerant to a subcooling state. Therefore, when the superconducting cable is applied to a power cable for transporting electric power in an aircraft, it is not necessary to construct a cooling system for the superconducting cable in the aircraft, so the weight of the power cable can be reduced. Therefore, superconducting cable 100 according to the present embodiment can contribute to the realization of an electric aircraft capable of reducing fuel consumption and environmental load.

Further, by providing the heat conduction layer 16 on the outermost periphery of the core 10, even if the liquid nitrogen remaining in the sealing tube 30 is reduced by vaporization of the liquid nitrogen, the liquid via the heat conduction layer 16 The entire core 10 can be cooled by nitrogen. This allows the core to be constantly cooled and maintained in the superconducting state during the operation of the aircraft.

In addition, by dividing the inside of the sealing tube 30 into a plurality of sections along the longitudinal direction of the core 10 and dividing and sealing liquid nitrogen in the plurality of spaces, a superconducting cable is obtained along with the change in the attitude of the aircraft 1000. Even if 100 is inclined at an angle close to perpendicular to the ground, liquid nitrogen 20 is collected downward in the direction of gravity in each space, so compared to the case where the inside of the enclosed tube 30 is a single space Thus, the pressure applied to the sealing tube 30 can be reduced. In addition, since the occurrence of uneven distribution of liquid nitrogen in the inside of the sealing tube 30 is suppressed, the state of the liquid refrigerant 20 becomes substantially uniform over the longitudinal direction of the core 10, so that the core 10 can be cooled substantially evenly. it can.

Furthermore, a gas-liquid separation filter 40 for discharging the gas refrigerant in which the liquid refrigerant 20 is vaporized to the outside of the sealing pipe 30 is disposed on the outer peripheral surface of the sealing pipe 30 for each of the plurality of spaces. In each of the plurality of sections, a rise in the refrigerant pressure due to the generation of the gaseous refrigerant can be suppressed.

In the embodiment described above, although the configuration in which the superconducting cable 100 is used for AC power transmission (for example, three-phase AC power transmission) has been described, the superconducting cable according to this embodiment is DC power transmission (for example, bipole power transmission, mono It can also be used for pole power transmission.

It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the embodiments described above but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

Reference Signs List 10 core, 12 former, 13 inner superconducting layer or conductor layer, 14 insulating layer, 15 outer superconducting layer or shield layer, 16 heat conductive layer, 20 liquid nitrogen, 30 sealed tube, 30 A partition member, 31 gas flow path, 32 corrugated Inner tube, 33 vacuum layers, 34 corrugated outer tube, 35 reinforcing layers, 36 heat insulating tubes, 40 gas-liquid separation filters, 42 filters, 100 superconducting cables, 102 generators, 104, 108 power converters, 106 motors, 110 power distribution , 112 power storage device, 120 terminal part, 122 electrode, 124 refrigerant container, 126, 216 inlet, 128 sealing member, 130 gas-liquid separator, 132 pressure control valve, 140 gas-liquid two-phase inlet, 141 gas outlet , 142 liquid outlet, 143 separator body, 143A, 1 3B partition body, 144 groove, 145 coalescer cartridge, 200 tanks, 202 refrigerator 204 a compressor, 210 connecting member, 1000 an aircraft.

Claims

A superconducting cable for transporting power between a plurality of power devices mounted on an aircraft,
With an insulation pipe,
A sealing pipe disposed inside the heat insulating pipe and in which a liquid refrigerant is sealed;
A superconducting cable housed in the enclosed tube and having a core having a superconducting layer.
The superconducting cable according to claim 1, wherein the core further comprises a heat conductive layer at the outermost periphery.
A plurality of partition members are disposed in the interior of the encapsulation tube to divide the interior of the encapsulation tube into a plurality of sections along the longitudinal direction of the core,
The superconducting cable according to claim 1, wherein each of the plurality of partition members is formed with a through hole through which the core passes.
The superconducting cable according to claim 1 or 2, further comprising: a gas-liquid separation filter disposed on an outer peripheral surface of the sealing pipe and discharging a gas refrigerant having the liquid refrigerant vaporized out of the sealing pipe.
It further comprises a gas-liquid separation filter disposed on the outer peripheral surface of the sealing pipe and discharging the gas refrigerant having the liquid refrigerant vaporized out of the sealing pipe.
The superconducting cable according to claim 3, wherein the gas-liquid separation filter is provided corresponding to each of the plurality of sections.
The superconducting cable according to claim 4 or 5 further provided with a gas channel which is arranged on the outer periphery of said enclosed tube and for discharging said gaseous refrigerant to the outside of said superconducting cable.
The superconducting cable according to any one of claims 1 to 5, wherein the sealing tube is filled with the liquid refrigerant cooled to a boiling point or a temperature below the boiling point.
The core is
A hollow spiral former,
The superconducting layer disposed on the outer periphery of the former;
An insulating layer disposed on the outer periphery of the superconducting layer;
The superconducting cable according to any one of claims 1 to 7, further comprising: a shield layer disposed on an outer periphery of the insulating layer.
It further comprises a connecting member for connecting a tank for storing the liquid refrigerant to the former,
The connecting member is opened when the tank is connected, and connects the inside of the tank and the hollow portion of the former, and is closed when the tank is disconnected, and the hollow portion of the former is closed. The superconducting cable of claim 8 configured to seal.
And a terminal unit for housing the terminal of the core,
The terminal unit is
A refrigerant container that holds the liquid refrigerant and the end of the core therein;
The superconducting cable according to any one of claims 1 to 9, further comprising: a sealing member for sealing an inlet of the liquid refrigerant formed in the refrigerant container.
The superconducting cable according to claim 10, further comprising: a gas-liquid separator, disposed at the terminal portion, for discharging a gas refrigerant obtained by vaporization of the liquid refrigerant to the outside of the refrigerant container.
The superconducting cable according to claim 11, wherein the gas-liquid separator has a pressure control valve disposed at the outlet of the gaseous refrigerant.
The superconducting cable according to any one of claims 1 to 12, wherein the liquid refrigerant is liquid nitrogen.