Apparatus for transmitting electrical energy using superconducting current carriers

Abstract

Device for transmitting electrical energy by means of superconducting current carriers In a device for transmitting electrical energy by means of superconducting current carriers, the superconducting current carrier to be cooled is accommodated in a first cooling path, which is connected via a coolant supply pipe to a supply device for a first coolant and is surrounded by at least one second cooling path for passing a second coolant, which is fluidly connected with a coolant discharge pipe for the warmed second coolant, in which a supercooled liquefied gas is used as the first coolant, and according to the invention the device is characterized in that a liquefied gas is used as the second coolant and in that the second cooling path is provided with means for discharging the gas phase resulting from evaporation of the second coolant.

Description

[Technical Field]

[0001] The invention relates to a device for transmitting electrical energy by means of a superconducting cable according to the preamble of patent claim 1. [Background technology]

[0002] Superconducting current carriers, especially superconducting cables or superconducting busbars, are heated to a sufficiently low temperature (transition temperature, T c ) superconducting state. The transition temperature of superconductors varies widely, with typical metallic superconductors having a T c T for ceramic high-temperature superconductors from <10K c It is not impossible that superconductors with even higher transition temperatures will be discovered and put to industrial use in the near future.

[0003] To maintain the superconducting state, the superconducting cable must be cooled by a suitable coolant. To achieve effective cooling, the superconducting current carrier is housed in a cooling channel (cryostat), e.g., cylindrical or rectangular, through which the coolant is guided during operation. Many superconducting current carriers of this type are known and are described, for example, in EP 2 328 156 A1, EP 2 608 223 A1 or EP 2 793 240 B1.

[0004] The coolant used to cool the superconducting current carrier is a supercooled liquefied gas, such as liquid nitrogen, liquid oxygen, liquid hydrogen, liquefied natural gas, or a liquefied noble gas, especially liquid helium. By "supercooled liquefied gas" is meant a gas that exists below its boiling point at the prevailing pressure. In this case, in contrast to the use of a non-supercooled liquefied gas, i.e., at its corresponding boiling point, the absorption of heat primarily results in a temperature increase in the liquefied gas without a change in its condensation state. Examples of such cooling systems are described in documents U.S. Pat. No. 6,732,536 (B1), WO 2007 / 005091 A1, EP 1 850 354 A1, U.S. Patent Application Publication No. 2006 / 0,150,639 (A1), or EP 3 017 238 A1. In all these systems, the liquefied gas is supercooled and pumped to the superconducting current carrier. After cooling, the coolant is returned to the subcooler to remove the heat absorbed during the process. In this case, the heat input during cooling of the superconducting current carrier is provided to a large extent by the supply pump and / or from the surroundings, for which reason the superconducting current carrier is usually equipped with good insulation, for example vacuum insulation.

[0005] Known systems have drawbacks that become apparent especially over long cooling distances. To be able to offset the heat input, more refrigerant must be guided through the pipe as the length of the current carrier increases. However, an increase in the volumetric flow rate can only be achieved by a larger flow cross-sectional area and / or a higher flow velocity. In the former case, the cost of the structure increases so rapidly that it becomes economically unjustifiable. In the latter case, a high flow velocity also increases the dissipative heat input due to friction of the refrigerant on the inner pipe walls, thereby reducing the cooling efficiency.

[0006] For these reasons, structures for transmitting electrical energy by means of superconducting current carriers are usually divided into hydraulically separated cooling sections, each having a length of, for example, one kilometer, for which separate circulation cooling systems are used, although the equipment costs for building such longer electrical energy transmission systems are considerable.

[0007] From WO2014026873A1 a method for cooling an object, in particular a superconducting cable, is known. In this method, a supercooled cryogenic coolant is guided through an annular passage arranged around the superconducting cable. Cooling is achieved by means of two storage vessels at either end of the cable, from which the coolant is guided in a reciprocating manner through the annular passage. This reciprocating movement avoids the need for a separate return pipe through which additional heat is input into the system, but the need for two storage vessels increases the cost of the device.

[0008] U.S. Patent No. 7,453,041 (B1) describes a structure for cooling a superconducting cable. In this structure, the superconducting cable is coaxially housed within a cylindrical first (inner) flow channel, which is connected to a coolant supply. The first flow channel is coaxially housed within a cylindrical second (outer) flow channel, which is fluidly connected to the inner flow channel at at least one end of the structure and includes a coolant outlet. During operation of the structure, a coolant at a temperature below the transition temperature of the superconducting cable material, such as supercooled liquid nitrogen, is guided through the inner flow channel to cool the superconducting cable. The coolant then returns via the outer flow channel, acting as a heat shield to protect the inner flow channel from heat input from the surroundings. In this way, heat input can be reduced throughout the entire length of the cable, thereby enabling longer structures to be designed.

[0009] However, a problem with this subject is that the nitrogen in both channels must be kept in a liquid state at all times to maintain circulation and cooling efficiency, which adds significant equipment costs and reduces the effective length of the cable section equipped with the cooling system. Summary of the Invention [Problem to be solved by the invention]

[0010] The problem underlying the present invention is therefore to provide an apparatus for transmitting electrical energy using superconducting current carriers, which allows for efficient cooling of even longer pipe sections at a relatively low equipment cost. [Means for solving the problem]

[0011] This problem is solved by a device with the features of patent claim 1. Advantageous embodiments of the invention are set out in the subclaims.

[0012] The device for transmitting electrical energy by means of superconducting current carriers, i.e. in particular cables or busbars, is characterized in that the current carrier to be cooled is accommodated in a first cooling channel, which is connected to a supply device for the first cooling channel via a cooling channel, the first cooling channel is provided with a heat shield surrounding the first cooling channel and thermally connected to at least one second cooling channel for passing a second cooling channel, a supercooled liquefied gas is used as the first cooling channel, i.e. according to the invention a liquefied gas is used as the second cooling channel, and at least one second cooling channel is provided with at least one gas phase separator.

[0013] Thus, the device according to the invention comprises a first (inner) cooling channel in which the superconducting current carrier to be cooled is located, and a heat shield surrounding the first cooling channel and thermally connected to a second cooling channel through which a second coolant flows. This heat shield may be, for example, the second cooling channel itself, arranged coaxially or otherwise around the first cooling channel, or may be, for example, a cylindrical structure made of a material with good thermal conductivity, surrounding the first cooling channel and thermally connected to one or more channels through which the second coolant flows. To cool the superconducting current carrier, a supercooled liquefied gas, such as supercooled liquefied nitrogen, supercooled liquefied oxygen, supercooled liquefied hydrogen, supercooled liquefied natural gas or a rare gas, is used, the temperature of which is regulated so that it always remains in a liquid state in the inner cooling channel and at a temperature below the transition temperature of the superconducting cable material.

[0014] The first refrigerant is introduced into the first cooling channel at an input point, which is located, for example, at an end of the device according to the invention or in the central region between the two ends of the device according to the invention, where the first refrigerant can also be circulated and subcooled each time when it enters the first cooling channel.

[0015] The refrigerant used in one or more second cooling channels is similarly a liquefied gas, which may be the same or different from the gas used in the first cooling channel. However, this gas exists at a higher temperature than the refrigerant in the first cooling channel and can at least partially evaporate due to heat input from the surroundings. Therefore, unlike prior art devices, the refrigerant in the second cooling channel does not need to be constantly kept in a liquid state, for example by cooling to a corresponding temperature or applying a corresponding pressure, thereby saving a considerable amount of refrigerant. Instead, the gas phase resulting from the evaporation of the refrigerant in the second cooling channel is separated from the still-liquid second refrigerant in one or more gas-phase separators and removed from the second cooling channel via an exhaust pipe. The gas phase is then released into the surrounding atmosphere via the exhaust pipe or supplied for another use. The exhaust pipe may also extend at least partially through a third cooling channel extending coaxially around the second cooling channel, in this case constituting an additional heat shield.

[0016] The separated liquid phase either remains in the second cooling channel or is returned to the second refrigerant flow. After passing through the second cooling channel, the liquid phase replaces part of the discharged gas phase and is then used again in a newly subcooled state in the first cooling channel to cool the superconducting cable or for other purposes, such as cooling a power supply connected to the superconducting cable.

[0017] A layer with a low heat transfer coefficient is provided between the first cooling channel and the heat shield and / or between the first cooling channel and the second cooling channel, so that as little heat as possible is transferred from the second cooling channel to the first cooling channel. Insulation, for example vacuum insulation, surrounds the heat shield and the one or more second cooling channels, or the second cooling channel if the second cooling channel is arranged coaxially with the first cooling channel and acts as a heat shield.

[0018] The gas phase separator preferably comprises a vessel in which the liquid and gas phases are separated by gravity, i.e., the gas phase collects in the geodesically upper part of the vessel and is discharged from there via an exhaust pipe. However, other mechanisms for phase separation, such as temperature or pressure control instruments or liquid-tight but gas-permeable membranes, can also be used advantageously in one or more gas phase separators. Also conceivable according to the invention are multiple gas phase separators arranged at a distance from one another along the length of the second cooling channel.

[0019] The gas phase separator is preferably located inside the external insulation surrounding the second and possibly third cooling paths of the device according to the invention, and / or the gas phase separator has its own highly effective insulation, such as being located inside a vacuum chamber.

[0020] An advantageous embodiment of the invention is characterized in that a subcooled second refrigerant is used as the first refrigerant.

[0021] In this configuration, the first and second refrigerants are composed of the same substance, such as liquid nitrogen, and may be drawn from the same storage container. However, the refrigerant is either supercooled before being introduced into the first cooling path, or is constantly circulated and supercooled each time before being introduced into the first cooling path, and is always in a supercooled liquid state within the first cooling path. The refrigerant introduced from the first cooling path into the second cooling path warms up by a temperature difference of, for example, 2 to 10 K due to heat input from the surroundings. During this time, the refrigerant may also reach its boiling point and partially evaporate. In the second cooling path, this refrigerant serves as a heat shield for the refrigerant in the first cooling path, absorbing less heat there.

[0022] In this case, the coolant from the second cooling channel, still in liquid form, can be supplied for another cooling task, for example, cooling a power supply. However, in a particularly preferred embodiment of the invention, at least one fluid connection is provided between the first and second cooling channels for introducing the coolant from the first cooling channel into the second cooling channel. In this case, the coolant conducted through the first cooling channel is therefore identical to the coolant conducted through the second cooling channel. That is, the coolant is supplied in a subcooled state to the first cooling channel, where it serves to cool the superconducting current carriers, and then, via this fluid connection or via multiple fluid connections, into the second cooling channel, where it serves as a heat shield for the first cooling channel or cools a heat shield thermally connected to one or more second cooling channels. In the second cooling channel, the coolant can evaporate at least partly due to heat input from the surroundings. The evaporated coolant is separated from the liquid phase and discharged. The coolant remaining in liquid form passes through the second cooling channel and can then be reused. For example, this coolant is brought to the operating temperature required for cooling the superconducting current carrier in a subcooler together with new coolant to replace the discharged gas phase, and is then freshly introduced into the first cooling channel.

[0023] The device according to the invention has two ends that define the boundary of the cooling device for the superconducting current carrier. In a preferred embodiment of the invention, a fluid connection between the first and second cooling channels is provided in the region of at least one of the ends, via which the coolant enters the second cooling channel from the first cooling channel during operation of the device. By locating the fluid connection at the end, the first coolant is guided along the superconducting current carrier to its end, thereby ensuring sufficient cooling of the entire current carrier. The coolant supply pipe for introducing the first coolant can be located at the opposite end or at another location, such as the center between the two ends. It is also conceivable within the scope of the invention for the coolant supply pipe to enter the first cooling channel, for example, centered between the two ends, with a fluid connection at each end between the cooling channels. However, this fluid connection or at least one fluid connection can also be located at any other location between the ends of the device.

[0024] Alternatively or in addition to the above, a plurality of fluid connections are provided between the first and second cooling passages, spaced apart along the length of the passages.

[0025] In this case, multiple fluid connections are provided along the entire length of the device, spaced apart in the direction of the device's length, through which small partial flows of the coolant flowing through the first cooling channel flow into the second cooling channel. The first coolant is continuously replaced by new supercooled liquefied gas from the coolant supply line. This maintains the low temperature required to maintain superconductivity in the inner cooling channel. At the same time, the flow velocity of the coolant flowing into the first channel decreases with increasing distance from the point of introduction of new coolant. This reduces heat input due to friction of the coolant on the channel walls. The number and diameter of the through-flow openings or channels provided as fluid connections between the first and second cooling channels depend, inter alia, on the length of the device and are selected so as to ensure sufficient cooling of the superconducting current carrier even at the farthest point from the introduction point.

[0026] In a still further advantageous embodiment of the invention, the fluid connection between the first cooling channel and the at least one second cooling channel is provided with a meter for controlling the flow of coolant, so that the supply of coolant can be precisely adapted to the current requirements, such as the ambient heat input and the ambient temperature.

[0027] At the outer end of the device, the superconducting current carrier is connected to an electrical element, for example either a power supply or a consumer with normal conductivity, for example a magnet or a machine, or there is another device according to the invention located there, which is used to cool another part of the superconducting current carrier.

[0028] In another advantageous embodiment of the invention, a plurality of devices according to the invention are assembled to form a larger structure for transmitting electrical energy, similar to the structure described in U.S. Pat. No. 7,453,041 B2. In addition, these devices are arranged in a row one behind the other and used to cool correspondingly long superconducting current carriers. In this way, the operation of very long superconducting current carriers, with lengths of 10 km to 100 km or more, is possible.

[0029] The embodiments of the present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic diagram showing a part of a device according to the invention in a first embodiment in longitudinal section; [Figure 2] 3 is a schematic diagram showing a part of the device according to the invention in longitudinal section in another embodiment; [Figure 3] 3 is a schematic diagram of the device from FIG. 2 in cross section along section line III-III in FIG. 1; [Figure 4] 3 is a schematic diagram showing a cross-section of a device according to the invention in a further embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0031] The apparatus 1 shown in Figure 1 includes a superconducting current carrier. In the embodiment shown, the superconducting current carrier is a superconducting cable 2, or at least a portion of a superconducting current carrier 2, contained within a cooling structure 3 for cooling the superconductor 2. The cooling structure 3 has a cylindrical or box-like housing 4, e.g., several hundred meters to several kilometers in length, and terminated at opposite ends 5, 6.

[0032] The superconducting cable 2 is essentially arranged along the axis of the housing 3. A first cooling channel 7, e.g., cylindrical or box-shaped, extends coaxially around the superconducting cable 2, and a second cooling channel 8, e.g., cylindrical or box-shaped, extends coaxially around the first cooling channel 7, and the second cooling channels 8 are separated from each other by an outer shell 9 made of a material with good thermal insulation properties. In the region of the ends 5, 6, the cooling channels 7, 8 are fluid-dynamically connected to each other at the penetrations 11a, 11b; 12a, 12b; elsewhere, in the embodiment according to Fig. 1, there is no fluid connection between the cooling channels 7, 8.

[0033] An exhaust duct 13 is arranged radially outside the second cooling duct 8, which is also surrounded by insulation, for example vacuum insulation 14. There is no fluid connection between the second cooling duct 8 and the exhaust duct 13, except for a fluid connection in the region of a gas phase separator 15, which will be explained in more detail later. The exhaust duct 13 is fluidly connected to an exhaust pipe 16, which in this example is provided in the region of an end, here end 5.

[0034] The apparatus 1 further comprises a refrigerant supply pipe 17 which establishes a fluid connection between the cooling device 18 and the first cooling circuit 7. The cooling device 17 is, for example, a subcooler for subcooling a liquefied cryogenic medium, such as liquid nitrogen. In addition, the cooling device 18 is fluidly connected to the second cooling circuit 8 via a return pipe 19. Furthermore, the cooling device 18 is connected to a storage container 20 from which fresh refrigerant can be supplied as needed during operation of the apparatus 1.

[0035] The gas phase separator 15 is geodetically arranged in the upper part of the housing 3 and includes a vessel 21 that is fluidly connected to the second cooling channel 8 via a supply pipe 22 and a return pipe 23. Furthermore, a gas pipe 23 extends from the upper part of the vessel 21 and merges into the exhaust channel 13.

[0036] The device 1 is part of an overall structure for transmitting electrical energy. Connected to end 6 is an identical device 25, which is only suggested in the example shown here, with the superconducting cable 2 being led through the front end walls 26, 27 of both devices 1, 25. However, instead of device 25, other electrical elements may also be connected to end 5, 6, as shown here by way of example in the region of end 5. At end 5, the superconducting cable 2 is led through the front end wall 28 and connected to an electrical element 29, which may be, for example, an electrical consumer or power supply or similarly a device according to the invention.

[0037] During operation of the device 1, the superconducting cable 2 is cooled with a supercooled liquefied gas, such as supercooled nitrogen, LNG, oxygen, or rare gas. For this purpose, the coolant is taken from a storage container 20, brought to a temperature below its boiling point in a cooling device 18 (i.e., supercooled), and injected into the first cooling channel 7 via a cooling device supply line 17 by a conveying device (not shown), e.g., a pump. The coolant passes through the cooling channel 7 in both directions to the ends 5 and 6 at a temperature at which the superconductor elements of the superconducting cable 2 are in the superconducting state. In the region of the ends 5 and 6, the coolant flows into the second cooling channel 8, and from both ends 5 and 6, it passes through this second cooling channel 8 and into a return line 19. Through the return line 19, the coolant is supplied to the cooling device 18, where it is cooled and injected again into the first cooling channel 7. When the coolant supply pipe 17 is located in the region of one of the ends 5, 6, the coolant flows through the first cooling channel 7 only in the direction of the other end 6, 5.

[0038] The refrigerant in the second cooling channel 8 serves as a heat shield against heat ingress from the surroundings. The heat input raises the temperature of the refrigerant in the cooling channel 8 to its boiling point, eventually evaporating part of it. The refrigerant is therefore present in the second cooling channel 8 as a phase mixture consisting of liquid and gaseous components. The gas phase contained in the refrigerant is separated from the liquid phase in the gas phase separator 15. The liquid phase is returned to the cooling device 18, while the separated gas phase passes through the exhaust path 13 and eventually leaks out via the exhaust pipe 16. In an alternative configuration, the exhaust path 13 is not provided, and the gas phase is led directly from the gas phase separator 15 to the surrounding air. Leading the gaseous refrigerant through the exhaust path 13 further improves protection against heat ingress from the surroundings. The gaseous refrigerant is eventually released into the surrounding air or supplied for further use. As a result, part of the refrigerant circulating through the cooling channels 7, 8 and the cooling device 18 is lost and must be replaced with new refrigerant from the storage tank 20.

[0039] Instead of the coaxial arrangement of the first and second cooling channels 7 and 8 shown here, a structure made of an otherwise heat-conducting material may also be provided as a heat shield. This structure is arranged around the first cooling channel 7, for example in the form of a sleeve arranged around the first cooling channel 7. In this case, the second cooling channel is configured as a pipe running parallel to the first cooling channel inside the vacuum insulation 14 and is thermally connected to said structure. In this case, several second cooling channels thermally connected to this structure may also be used inside the vacuum insulation 14.

[0040] The device 101 shown in Figures 2 and 3 also comprises a housing 103. The housing 103 comprises a first cooling channel 107 coaxially surrounding a superconducting current carrier, such as a superconducting cable 102, and a second cooling channel 108 arranged coaxially around the inner cooling channel 107, the cooling channels being separated from one another by an outer shell 109 made of a material with good thermal insulation properties and surrounded by vacuum insulation 104. In the embodiment according to Figure 2, several gas phase separators are provided between the hydrodynamic cooling channel 108 and the exhaust channel 116, arranged at a distance from one another along the cooling channel 108, although only one of them, gas phase separator 115, is shown here. The gas phase separator 115 is provided with an exhaust pipe for discharging the gas phase separated in the gas phase separator 115.

[0041] However, unlike device 1, the fluid connection between the cooling channels 7, 8 is not located in the end region of the housing 103, but via penetrations 116a, 116b, 116c in the outer shell 109 that are spaced apart from one another along the length of the housing 103, for example at a distance of 100 m to 1000 m, and in other respects device 101 is configured similarly to device 1.

[0042] During operation of device 101, a coolant flows from a coolant supply unit (not shown) through cooling path 107 in the direction of the arrow to cool superconducting cable 102. At this time, small partial flows of the coolant flow through penetrations 116a, 116b, and 116c into cooling path 108. As a result, the mass flow rate of the coolant flowing through cooling path 107 decreases with increasing distance from the coolant supply unit, and the heat input caused by the flow velocity and friction on the inner wall of outer shell 9 decreases.

[0043] The coolant flows through the second cooling channel 108 in the direction of a coolant discharge pipe (not shown). The coolant absorbs heat from the surroundings, partially evaporates, and is therefore present in the second cooling channel 108 as a phase mixture of liquid and gaseous components. The gas phase contained in the coolant is separated from the still-liquid coolant in a number of gas phase separators 115 arranged at equal intervals in the cooling channel 108, as described above, and is then led away from the liquid phase into the surrounding air via an exhaust pipe 113. The still-liquid coolant is cooled, for example, in a cooling device as described above, and is then supplied again to the cooling channel 107. However, the coolant can also be used in other ways, for example, to cool a non-superconducting power supply (not shown) connected to the superconducting cable 102.

[0044] The only difference between the embodiment according to Fig. 4 and the embodiment shown in Fig. 3 is that the fluid connection between the cooling channels 107, 108 is not realized simply via the penetrations 116a, 116b, 116c, but instead a conduit 117 is provided, which can be controlled by means of a meter 118 according to a predetermined program or in response to a measured parameter, such as, for example, the ambient temperature or the temperature of the coolant in one of the cooling channels 117, 118. Explanation of symbols

[0045] 1 device 2. Superconducting cable 3 Cooling structure 4. Housing 5 End 6 End 7 First cooling path 8 Second Cooling Passage 9 Outer shell 10 - 11a, 11b penetration part 12a, 12b penetrations 13 Exhaust duct 14 Vacuum insulation material 15 Gas Phase Separator 16 Exhaust pipe 17 Refrigerant supply pipe 18 Cooling device 19 Return pipe 20 Storage Container 21 Container 22 Supply pipe 23 Return pipe 24 Gas pipe 25 Equipment 26 End Wall 27 End Wall 28 End Wall 29 Electrical Elements 101 Equipment 102 Superconducting Cable 103 Housing 104 - 105 - 106 - 107 First cooling path 108 Second Cooling Path 109 Outer Shell 110 - 111 - 112 - 113 Exhaust pipe 114 Vacuum insulation material 115 Gas Phase Separator 116a, 116b, 116c penetrations 117 Pipeline 118 Instruments

Claims

1. A device for transmitting electrical energy by means of a superconducting current carrier, the device comprising: a current carrier (2, 102) to be cooled housed in a first cooling channel (7, 107), the first cooling channel (7, 107) being connected to a supply device (20, 18) for a first cooling medium via a cooling medium supply pipe (17); the first cooling channel (7, 107) being provided with a heat shield surrounding the first cooling channel (7, 107) and thermally connected to at least one second cooling channel (8, 108) through which a second cooling medium flows; and a supercooled liquefied gas being used as the first cooling medium, a liquefied gas is used as a second refrigerant, and at least one second cooling path (8, 108) is provided with at least one gas phase separator (15, 115), and the temperature of the second refrigerant in the second cooling path is higher than the temperature of the first refrigerant in the first cooling path; at least one fluid connection (11a, 11b; 12a, 12b; 116a, 116b, 116c) is provided between the first cooling channel (7, 107) and the at least one second cooling channel (8, 108) for introducing a coolant from said first cooling channel into the at least one second cooling channel, 1. An apparatus comprising: a first cooling channel (7, 107) and at least one second cooling channel (8, 108) between which a plurality of fluid connections (116a, 116b, 116c) are provided, the fluid connections being spaced apart from one another in the longitudinal direction of the cooling channels (7, 107; 8, 108).

2. 2. The apparatus according to claim 1, characterized in that the gas phase separator (15, 115) comprises a vessel fluidly connected to the second cooling channel, the geodetic upper part of the vessel being fluidly connected to an exhaust pipe (16) for discharging the gas phase.

3. 3. The device according to claim 1 or 2, characterized in that the gas phase in the gas phase separator is led off via a float valve, a meter or a (15, 115) liquid-tight but gas-permeable membrane.

4. 4. The device according to claim 1, wherein a subcooled second refrigerant is used as the first refrigerant.

5. 5. The device according to claim 1, wherein at least one fluid connection (11a, 11b; 12a, 12b) between a first cooling channel (7, 107) and at least one second cooling channel (8, 108) is arranged in the region of an end (5, 6) of the device (1) remote from the refrigerant supply pipe (17) of the first cooling channel (7, 107).

6. 6. The device according to claim 1, wherein the fluid connection between the first cooling channel (7, 107) and at least one second cooling channel (8, 108) is provided with a meter for controlling the flow of refrigerant.

7. 10. A structure for transmitting electrical energy using superconducting current carriers, comprising a plurality of devices (1) according to any one of claims 1 to 6 connected to each other.

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