WO2019146271A1 - Superconductive cable - Google Patents

Abstract

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

Description

Superconducting cable

The present disclosure relates to a superconducting cable. This application claims priority based on Japanese Patent Application No. 2018-008946 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 is a superconducting cable for transmitting power between a plurality of electric power devices mounted on an aircraft, the heat insulating pipe in which a solid refrigerant is sealed, and the heat insulating pipe housed in the heat insulating pipe And a core having a 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 cross-sectional view taken along line III-III of FIG. FIG. 4 is a cross-sectional view showing the core shown in FIG. FIG. 5 is a figure for demonstrating the process of filling solid nitrogen with the inside of a heat insulation pipe | tube and a terminal part. FIG. 6 is a diagram schematically showing temporal changes in temperature and amount of solid nitrogen present in the superconducting cable. FIG. 7 is a cross-sectional view of a superconducting cable according to a first modification of the present embodiment. FIG. 8 is a cross-sectional view of a core of a superconducting cable according to a second modification of the present embodiment. FIG. 9 is a schematic view of a superconducting cable according to a third modification of the present embodiment. FIG. 10 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG. FIG. 11 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG. FIG. 12 is a cross-sectional view schematically showing a configuration example of the gas-liquid separator shown in FIG.

[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 and 3) according to an aspect of the present disclosure transmits power between a plurality of power devices mounted on the aircraft 1000 (see FIG. 1). The superconducting cable 100 includes the heat insulating pipe 35 in which the solid refrigerant 20 is sealed, and the core 10 housed in the heat insulating pipe 35 and having a superconducting layer.

According to the superconducting cable 100 according to the above (1), the core 10 is cooled using the sensible heat of the solid refrigerant 20 enclosed in the heat insulation pipe 35. 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, so the weight of the power cable can be reduced.

Moreover, according to the superconducting cable 100 which concerns on said (1), the refrigerant | coolant is a state fixed without flowing in the inside of the heat insulation pipe | tube 35. As shown in FIG. Therefore, even when the longitudinal direction of the superconducting cable 100 is inclined from the horizontal direction with respect to the ground with the change of the attitude of the aircraft 1000 during the operation of the aircraft 1000, the refrigerant does not flow due to gravity, Uneven distribution of the refrigerant in a part of the heat insulating pipe 35 can be suppressed. According to this, since the state of the refrigerant is kept substantially uniform in the longitudinal direction of the core 10, the core 10 can be cooled substantially uniformly. In addition, when the refrigerant is unevenly distributed inside the heat insulating pipe 35, a large pressure is applied to the heat insulating pipe 35 in the portion where the refrigerant is unevenly distributed. Since the pressure increases as the length of the heat insulating pipe 35 increases, the heat insulating pipe 35 is required to be robust enough to withstand the pressure, and there is a concern that the heat insulating pipe 35 may be large and heavy. On the other hand, in the superconducting cable 100 according to the above (1), since the uneven distribution of the refrigerant can be suppressed as described above, the heat insulating pipe 35 can be reduced in size and weight.

(2) The superconducting cable 100 which concerns on said (1) is further provided with terminal part 120A, 120B which accommodates the terminal of the core 10 (refer FIG. 5). In the end portions 120A and 120B, an inlet 126 for injecting the liquid refrigerant 21 into the inside of the heat insulation pipe 35 is formed. The superconducting cable 100 further includes a connecting member 128 for connecting the refrigerator 200 to the terminal units 120A and 120B. The connection member 128 is opened when the refrigerator 200 is connected, and is connected when the refrigerator 200 and the end of the core 10 are connected, and is closed when the refrigerator 200 is not connected, and the inlet 126 is sealed. Configured as.

In this way, the liquid refrigerant 21 is injected into the inside of the heat insulation pipe 35 before takeoff of the aircraft 1000, and the liquid refrigerant 21 is cooled using the refrigerator 200 to form the solid refrigerant 20, so that the heat insulation pipe 35 is obtained. The solid refrigerant 20 can be filled inside the Moreover, after the liquid refrigerant 21 has solidified, the aircraft 1000 can be operated with the refrigerator 200 not mounted by removing the refrigerator 200 from the terminal units 120A and 120B.

In addition, based on the Joule loss (heat loss) generated during operation of the aircraft 1000, the amount of the solid refrigerant 20 that can be filled in the adiabatic pipe 35, etc., the target temperature for cooling the liquid refrigerant 21 is set. Thus, during operation of the aircraft 1000, the solid refrigerant 20 can be maintained at a temperature below the melting point, and the solid refrigerant 20 can be prevented from being liquefied.

(3) In the superconducting cable 100 according to the above (1) or (2), the core 10 (see FIG. 4) is formed on the former 12, the superconducting layer 13 disposed on the outer periphery of the former 12, and the outer periphery of the superconducting layer 13 It has the insulating layer 14 arrange | positioned, and the shield layer 15 arrange | positioned on the outer periphery of the insulating layer 14. As shown in FIG.

Thus, the solid refrigerant 20 is filled in the space formed between the shield layer 15 and the inside of the heat insulating tube 35, so that the superconducting layer 13 and the shield layer 15 of the core 10 can be efficiently cooled. it can.

(4) In the superconducting cable 100 according to (3) above, the core 10 may further have a heat conductive layer 17 (see FIG. 8) disposed at the outermost periphery.

In this way, in the process of cooling the liquid refrigerant 21 or the solid refrigerant 20 filled in the heat insulation pipe 35 using the refrigerator 200, the core 10 and the heat insulation pipe 35 are efficiently cooled using the heat conduction layer 17. can do. Therefore, the cooling time of the refrigerant can be shortened.

(5) The superconducting cable 100 according to any one of the above (1) to (4) may further include a heat conductor 34 (see FIG. 7) disposed on the inner peripheral side of the heat insulation pipe 35.

In this way, in the process of cooling the liquid refrigerant 21 or the solid refrigerant 20 filled in the heat insulation pipe 35 using the refrigerator 200, the core 10 and the heat insulation pipe 35 are efficiently cooled using the heat conductor 34. can do. Therefore, the cooling time of the refrigerant can be shortened.

(6) The superconducting cable 100 according to the above (2) is disposed at the end portions 120A and 120B, and the gas-liquid separator 130 for discharging the gas refrigerant having the liquid refrigerant vaporized out of the heat insulation pipe 35 (see FIG. 9) Further).

In this way, it is possible to suppress an increase in the refrigerant pressure in the heat insulating pipe 3530 due to the gas refrigerant generated by the cooling of the core 10.

(7) In the superconducting cable 100 which concerns on said (6), the gas-liquid separator 130 (refer FIG. 9) has the pressure control valve 132 arrange | positioned at the exit of a gaseous refrigerant.

Thus, the pressure regulating valve 132 can maintain the differential pressure between the refrigerant pressure in the heat insulating pipe 35 and the external pressure. Therefore, even when the attitude of the airframe is inclined during the 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 heat insulation pipe 35.

(8) In the superconducting cable 100 according to any one of the above (1) to (7), the solid refrigerant 20 is solid 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.

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.

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. Only one of the four engines, the motor 106 is shown. 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. If the power cable consists of an existing normal conducting cable (for example, an OF cable or CV cable), the weight of the power cable for transporting, for example, 4 MW three-phase AC power (AC frequency 400 Hz, rated voltage 230 V, rated current 10 kA) 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 Become.

In recent years, in power cables in 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 copper cable and can flow a large current, so the power cable can be made lightweight and compact. Therefore, from the viewpoint of reducing the weight of the power cable, application to power cables 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 this cooling structure, operation is performed by connecting a cooling system to the superconducting cable and 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. Therefore, there is a concern that the weight of the cooling system is increased, and 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 insulation pipe 35. The superconducting cable 100 cools the core 10 by the solid refrigerant so as to be in a superconducting state by sealing the solid refrigerant in the heat insulating pipe 35, and is used for transporting power. In the following description, solid nitrogen is used as the solid 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 35 may be single core or multiple cores. The following description exemplifies a three-core one-piece three-phase AC cable in which a three-core core 10 is twisted and housed in a heat insulation pipe 35.

FIG. 3 is a cross-sectional view taken along line III-III of FIG. FIG. 4 is a cross-sectional view showing the core 10 shown in FIG.

As shown in FIGS. 3 and 4, the superconducting cable 100 mainly includes a three-core core 10, a corrugated inner tube 30, a vacuum layer 31, a corrugated outer tube 32, and a reinforcing layer (corrosion preventing layer) 33. Prepare for The corrugated inner pipe 30, the vacuum layer 31, the corrugated outer pipe 32 and the reinforcing layer 33 constitute a heat insulating pipe 35.

As shown in FIG. 4, the core 10 includes a former 12, an inner superconducting layer 13, an insulating layer 14, an outer superconducting layer 15, and a protective layer 16 in this order from the inside.

The former 12 maintains mechanical characteristics such as rigidity and bending characteristics of the core 10 and functions as a shunt for abnormal current. Specifically, when an accident such as a short circuit occurs in a power device to which the superconducting cable 100 is electrically connected, an abnormal current exceeding the current in the steady state occurs in the superconducting cable 100. Then, when a large current exceeding the critical current value Ic flows to the superconducting layer, the superconducting layer is transitioned (quenched) to normal conduction, and Joule loss (heat loss) occurs due to this transition. If the Joule loss is large, the core 10 constituting the superconducting layer may be burnt or the critical current value Ic may be reduced due to a rapid temperature rise even if the burn does not occur. When a large current is generated due to an accident such as a short circuit, heat generation of the superconducting layer can be suppressed by shunting the accident current to the former 12.

The former 12 has a hollow structure or a solid structure, and a pipe made of a metal (for example, copper or aluminum) having a low electrical resistance value, or a stranded wire can be suitably used.

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 it simplifies and shows in FIG. 4, it is set as the superconducting layer 13 of a multilayer structure.

Insulating layer 14 is a layer for securing the insulation required for the working voltage in internal superconducting layer 13.

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.

Protective layer 16 is disposed on the outer periphery of outer superconducting layer 15. The protective layer 16 is intended to ensure the electrical insulation of the outer superconducting layer 15 and to mechanically protect the outer superconducting layer 15. The protective layer 16 is formed, for example, by spirally winding an insulating paper such as PPLP or kraft paper around the outer superconducting layer 15.

Returning to FIG. 3, the corrugated inner pipe 30 located at the innermost periphery of the heat insulation pipe 35 houses the core 10 (excluding the terminal). As a material of the corrugated inner tube 30, copper, stainless steel or aluminum (alloy) can be suitably used. The inside of the corrugated inner pipe 30 is filled with solid nitrogen 20.

Inside the corrugated inner tube 30, the core 10 is cooled using solid nitrogen 20. Sensible heat is used to cool the core 10. A corrugated outer pipe 32 is disposed on the outer circumference of the corrugated inner pipe 30. The corrugated outer tube 32 has, for example, a corrugated cylindrical shape made of stainless steel. The space between the corrugated inner pipe 30 and the corrugated outer pipe 32 is a vacuum layer 31 and is used as an adiabatic space. This space may be filled with a heat insulating material.

A reinforcing layer 33 (anticorrosion layer) is disposed on the outer periphery of the corrugated outer tube 32. The reinforcing layer 33 is formed using, for example, polyvinyl chloride or the like.

Returning to FIG. 2, the superconducting cable 100 has end portions 120A and 120B at both ends in the longitudinal direction. The terminal unit 120 </ b> A accommodates one of the terminals in the longitudinal direction of the core 10. The terminal unit 120 </ b> B accommodates the other terminal in the longitudinal direction of the core 10. The terminal of the core 10 is electrically connected to the electrode 122 in each of the terminal units 120A and 120B. 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 solid nitrogen, such as copper or aluminum.

The heat insulating pipe 35 is connected to the end portions 120A and 120B, and the space in the end portions 120A and 120B communicates with the inside of the heat insulating pipe 35, and is filled with solid nitrogen.

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

First, the process of filling solid nitrogen into the inside of the heat insulation pipe 35 and the end parts 120A and 120B will be described with reference to FIG. This process is performed before the start of operation of the aircraft 1000.

As shown in FIG. 5, the end portions 120A and 120B are in the form of a vacuum insulation container, and have a refrigerant container 124 for holding solid nitrogen and the end of the core 10 inside, and an outer part disposed so as to surround the refrigerant container 124. And an outer tank. A certain gap exists between the refrigerant container 124 and the outer tank, and by setting the gap in a vacuum state, it is possible to suppress the transfer of heat from the outer tank side to the refrigerant container 124 side.

In order to supply the liquid refrigerant 21 to the inside of the refrigerant container 124, an inlet 126 for the liquid refrigerant 21 is formed at the end portions 120A and 120B. The superconducting cable 100 includes a connection member 128 for connecting the refrigerator 200 to the terminal units 120A and 120B. In the example of FIG. 5, the connection member 128 is attached to the inlet 126 of the liquid refrigerant 21.

The connection member 128 is opened when the refrigerator 200 is connected to the end portions 120A and 120B, and connects the cooling head of the refrigerator 200 and the end of the core 10. On the other hand, when the refrigerator 200 is not connected to the end portions 120A and 120B, the connection member 128 is in a closed state, and the inlet 126 is sealed.

In the process of filling solid nitrogen into the inside of the heat insulation pipe 35 and the end portions 120A and 120B, first, liquid nitrogen 21 is injected into the refrigerant container 124 through the injection port 126. The liquid nitrogen 21 injected into the refrigerant container 124 is also injected into the heat insulation pipe 35. Thus, the entire core 10 is immersed in liquid nitrogen 21.

After the liquid nitrogen 21 is filled in the end portions 120A and 120B and the heat insulating pipe 35, the connection member 128 is opened, and the refrigerator 200 is connected to each of the end portions 120A and 120B. Solid nitrogen is produced | generated by cooling liquid nitrogen 21 to the temperature below melting | fusing point (63. 1 K) using the refrigerator 200. As shown in FIG. The compressor 210 is connected to the refrigerator 200 via a circulating refrigerant pipe.

As shown in FIG. 5, the cooling head of the refrigerator 200 is disposed in the inner tank 124 and connected to the end of the core 10. Although both the cooling head and the core 10 are initially at the boiling point (77.3 K) of the liquid nitrogen 21, when the refrigerator 200 is operated and the cooling head falls below the melting point of the liquid nitrogen 21 (63. 1 K), the core 10 also melts The temperature is lower than that, and the liquid nitrogen 21 around the core 10 starts to solidify. The liquid nitrogen 21 is maintained at the melting point temperature until all the liquid nitrogen 21 solidifies. The refrigerator 200 finally reduces the solid nitrogen to a temperature below the melting point (for example, about 30 K) by continuing the cooling even after the liquid nitrogen 21 has completely solidified. The temperature of solid nitrogen at this time is the initial temperature of solid nitrogen when the aircraft 1000 takes off.

FIG. 6 schematically shows temporal changes in the temperature and amount of solid nitrogen present in superconducting cable 100. FIG. 6 shows temporal changes in the temperature and amount of solid nitrogen at the start of operation of the aircraft 1000.

As shown in FIG. 6, when the heat insulation pipe 35 and the end portions 120A and 120B are filled with liquid nitrogen at time t0, cooling of the liquid nitrogen is started. When the refrigerator 200 is operated, the liquid nitrogen is cooled, and when the temperature of the liquid nitrogen reaches the melting point at time t1, the amount of solid nitrogen gradually increases because the liquid nitrogen starts to solidify.

By continuing the cooling even after all the liquid nitrogen has solidified, the solid nitrogen is lowered to an initial temperature below the melting point (e.g. about 30 K). When the temperature of solid nitrogen reaches the initial temperature at time t2 after time t1, the operation of the refrigerator 200 is stopped.

After the operation of the refrigerator 200 is stopped, the refrigerator 200 and the compressor 210 are removed from the superconducting cable 100. When the refrigerator 200 is removed from the end portions 120A and 120B, the connection member 128 is closed, and solid nitrogen is trapped in the heat insulating pipe 35 and the end portions 120A and 120B.

As described above, in the present embodiment, the configuration in which liquid nitrogen is cooled to generate solid nitrogen using refrigerator 200 has been described, but the cooling means for cooling liquid nitrogen is limited to this. is not.

After the aircraft 1000 takes off at time t3, solid nitrogen is heated by AC loss and heat of external penetration generated in the core 10. Since the core 10 is cooled using the sensible heat of solid nitrogen, the temperature of the solid nitrogen gradually rises from the initial temperature (30 K). The solid nitrogen is kept in the solid state without being liquefied until the temperature of the solid nitrogen reaches the melting point (63. 1 K).

In the present embodiment, the initial temperature is set to a sufficiently low temperature so that the temperature of solid nitrogen does not exceed the freezing point during the period from the takeoff to landing of the aircraft 1000. The initial temperature is set based on the loss occurring in the period from the takeoff to landing of the aircraft 1000, the amount of solid nitrogen stored in the heat insulation pipe 35 and the terminals 120A and 120B, and the like. For example, in a 24-hour operation time, when the time when the load is 100% is 1 hour and the time when the load is 33% is 23 hours, the heat insulation pipe 35 and the terminal portions 120A and 120B are initially filled The amount of nitrogen that should be about 3200 kg.

After time t4, in order to prepare for the next operation of the aircraft 1000, cooling of solid nitrogen filled in the heat insulating pipe 35 and the end portions 120A and 120B is performed. Thereby, solid nitrogen is cooled again to the initial temperature (about 30 K).

As described above, according to the superconducting cable 100 according to the present embodiment, the core 10 is cooled using sensible heat of the solid refrigerant 20 sealed in the heat insulating pipe 35. Therefore, a cooling system for cooling the liquid refrigerant to the supercooling state is not required as compared with the conventional cooling technique of the superconducting cable in which the core is cooled by circulation using the subcooled refrigerant. 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, even when the longitudinal direction of the superconducting cable 100 is inclined from the horizontal direction with respect to the ground with the change of the attitude of the aircraft 1000 during the operation of the aircraft 1000, the refrigerant is fixed inside the heat insulation pipe 35 Because the refrigerant is in a stagnant state, uneven distribution of the refrigerant in a part of the heat insulating pipe 35 can be suppressed. According to this, since the state of the refrigerant is kept substantially uniform in the longitudinal direction of the core 10, the core 10 can be cooled substantially uniformly.

(Modified example of superconducting cable)
FIG. 7 is a cross-sectional view of a superconducting cable 100 according to a first modification of the present embodiment. As shown in FIG. 7, the superconducting cable 100 according to the present modification further includes a heat conductor 34 disposed on the inner peripheral side of the heat insulation pipe 35.

Thus, in the step of cooling liquid nitrogen or solid nitrogen 20 filled in the heat insulation pipe 35 using the refrigerator 200 (see FIG. 5), the core 10 and the heat insulation pipe 35 are utilized using the heat conductor 34. Can be cooled efficiently. Therefore, the cooling time of the refrigerant can be shortened.

FIG. 8 is a cross-sectional view of a core 10 of a superconducting cable 100 according to a second modification of the present embodiment. As shown in FIG. 8, in the superconducting cable 100 according to the present modification, the core 10 further includes a heat conduction layer 17 disposed at the outermost periphery.

Thus, in the step of cooling the liquid refrigerant or solid refrigerant 20 filled in the heat insulation pipe 35 using the refrigerator 200 (see FIG. 5), the core 10 and the heat insulation pipe 35 are utilized using the heat conduction layer 17. Can be cooled efficiently. Therefore, the cooling time of the refrigerant can be shortened.

FIG. 9 is a schematic view of a superconducting cable 100 according to a third modification of the present embodiment. As shown in FIG. 9, the superconducting cable 100 according to the present modification further includes a gas-liquid separator 130. The gas-liquid separator 130 is connected to each of the terminal units 120A and 120B. The gas-liquid separator 130 discharges nitrogen gas to the outside of the heat insulation pipe 35 while suppressing the outflow of liquid nitrogen from the heat insulation pipe 35 and the end portions 120A and 120B.

As described above, solid nitrogen is basically maintained in a solid state during the operation of the aircraft 1000, but if the joule loss generated in the core 10 increases beyond expectations, heated solid nitrogen will By liquefying and further vaporizing, nitrogen gas may be generated inside the heat insulation pipe 35. If nitrogen gas is generated inside the heat insulation pipe 35, the refrigerant pressure in the heat insulation pipe 35 may increase, and cooling of the core 10 may be insufficient, and the temperature of the core 10 may increase. Therefore, in order to maintain the temperature of the core 10, it is necessary to discharge nitrogen gas.

Therefore, as shown in FIG. 9, the gas-liquid separator 130 is connected to the terminal units 120A and 120B. Thereby, nitrogen gas can be efficiently discharged to the outside of the heat insulation pipe 35. Although the gas-liquid separator 130 is connected to each terminal in the example of FIG. 9, the gas-liquid separator may be connected to any one of the terminals 120A and 120B.

For example, in the case where the gas-liquid separator 130 is connected only to the terminal portion 120A, all solid nitrogen in the heat insulation pipe 35 is liquefied and a gas-liquid two-phase refrigerant in which liquid nitrogen and nitrogen gas are mixed Assume a changing state. In this state, when the attitude of the machine is inclined so that the terminal unit 120A is at a lower position than the terminal unit 120B, the gas-liquid two-phase refrigerant is biased to the terminal unit 120A side. Nitrogen gas can be exhausted without being discharged. On the other hand, when the attitude of the airframe is inclined such that the terminal unit 120B is at a lower position than the terminal unit 120A, the gas-liquid two-phase refrigerant is biased to the terminal unit 120B side. In this case, since the nitrogen gas rises and gathers on the terminal portion 120A side, the nitrogen gas can be discharged from the gas-liquid separator 130. That is, nitrogen gas can be discharged to the outside of the heat insulation pipe 35 regardless of the attitude of the airframe.

In the gas-liquid separator 130, 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 heat insulation pipe 35 may increase due to the inclination of the attitude of the airframe. Since the outside of the heat insulation pipe 35 is at atmospheric pressure or lower than atmospheric pressure, in such a case, both liquid nitrogen 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 heat insulation pipe 35 and the external pressure. As a result, nitrogen gas can be efficiently discharged to the outside without flowing out liquid nitrogen from the inside of the heat insulation pipe 35 including the case where the airframe is greatly inclined.

10 to 12 are cross-sectional views schematically showing an example of the configuration of the gas-liquid separator 130 shown in FIG. The gas-liquid separator 130 generally includes a gas-liquid separator using centrifugal force (FIG. 10), a gas-liquid separator using surface tension (FIG. 11), and a gas-liquid separation coalescer (FIG. 12). And so on can be used.

FIG. 10 is a cross-sectional view schematically showing the structure of a centrifugal gas-liquid separator. As shown in FIG. 10, 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. 11 is a cross-sectional view schematically showing the structure of a surface tension type gas-liquid separator. As shown in FIG. 11, 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 the 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. 12 is a cross-sectional view schematically showing the structure of the gas-liquid separation coalescer. As shown in FIG. 12, inside the separator 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.

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, 14 insulating layer, 15 outer superconducting layer (shield layer), 16 protective layer, 17 thermal conductive layer, 20 solid nitrogen, 21 liquid nitrogen, 30 corrugated inner tube, 31 vacuum layer, 32 corrugated outer tube, 33 reinforcing layer, 34 heat conductor, 35 heat insulating tube, 100 superconducting cable, 102 generator, 104, 108 power converter, 106 motor, 110 power distributor, 112 power storage device, 120A, 120B terminal part , 122 electrode, 124 inner tank, 126 inlet, 128 connection 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, 143B partition, 144 groove, 145 coalescer cartridge 200 refrigerator, 210 compressor, 1000 aircraft.

Claims (8)

A superconducting cable for transmitting power between a plurality of power devices mounted on an aircraft, comprising:
An insulating pipe in which a solid refrigerant is sealed;
And a core housed in the heat insulating pipe and having a superconducting layer. The terminal unit further includes a terminal unit for housing the terminal of the core, and the terminal unit is formed with an inlet for injecting a liquid refrigerant into the inside of the heat insulating pipe.
It further comprises a connection member for connecting a refrigerator to the terminal unit,
The connecting member is in an open state at the time of connection of the refrigerator, and is in a closed state at the time of disconnection of the refrigerator while connecting the refrigerator and the end of the core, and seals the inlet. The superconducting cable according to claim 1 configured as follows. The core is
With the 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 claim 1 or 2, further comprising: a shield layer disposed on an outer periphery of the insulating layer. The superconducting cable according to claim 3, wherein the core further comprises a thermally conductive layer disposed at the outermost periphery. The superconducting cable according to any one of claims 1 to 4, further comprising a heat conductor disposed on the inner circumferential side of the heat insulation pipe. The superconducting cable according to claim 2, further comprising: a gas-liquid separator, disposed at the terminal portion, for discharging the gas refrigerant having the liquid refrigerant vaporized to the outside of the heat insulation pipe. The superconducting cable according to claim 6, wherein the gas-liquid separator has a pressure control valve disposed at an outlet of the gas refrigerant. The superconducting cable according to any one of claims 1 to 7, wherein the solid refrigerant is solid nitrogen.

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