A multi-stage cascade pulse tube cryocooler cooling type superconducting current lead device

Abstract

The application relates to a multi-stage cascade pulse tube refrigerator cooling type superconducting current lead device, which comprises a current lead and a multi-stage cascade pulse tube refrigerator, wherein the multi-stage cascade pulse tube refrigerator comprises several stages of cold heads arranged in cascade and capable of providing gradient refrigeration temperatures, and each stage of cold heads sequentially cools the current lead from a room temperature section to a low temperature section from high temperature to low temperature. Compared with the prior art, the multi-stage cascade pulse tube refrigerator cooling type superconducting current lead device can sequentially perform gradient cooling on the room temperature end to the low temperature end of the superconducting current lead, can significantly reduce the input power of the refrigerator, improve the refrigeration efficiency of the refrigerator, and greatly save power.

Description

Technical Field

[0001] This invention belongs to the field of superconducting current lead technology, and relates to a multi-stage tandem pulse tube refrigerator-cooled superconducting current lead device. Background Technology

[0002] In recent years, superconducting technology has developed rapidly, and the application and role of current leads in various superconducting devices have been continuously strengthened. Current leads serve as the link between room-temperature power supplies and cryogenic superconducting devices, acting as a transitional element during device operation. In today's world of increasingly scarce energy and severe environmental problems, society as a whole is paying more and more attention to energy consumption and environmental protection. Current leads involve a significant amount of Joule heat and conductive heat leakage. The resistivity of copper increases with temperature, generating substantial Joule heat in high-temperature regions. Traditional techniques using cryogenic cooling for current leads require cooling from the lowest possible temperature. Cooling from room temperature to cryogenic temperatures involves traversing a large temperature range, generating a large cooling load that cannot meet the requirements for low losses and increases cooling costs, directly impacting the economy and stability of the entire system. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-stage tandem pulse tube refrigerator-cooled superconducting current lead device. By employing a multi-stage tandem pulse tube refrigerator to provide a cold head with multi-stage cooling temperatures, the current lead is cooled in stages from room temperature to low temperature, reducing energy loss caused by existing cooling technologies, reducing power consumption caused by refrigeration equipment, and improving the economy and stability of the entire system.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A multi-stage tandem pulse tube refrigerator-cooled superconducting current lead device includes a current lead and a multi-stage tandem pulse tube refrigerator. The multi-stage tandem pulse tube refrigerator includes several cold heads arranged in series and capable of providing stepped cooling temperatures. Each cold head sequentially cools the current lead from room temperature to low temperature.

[0006] Furthermore, the cold heads of the multi-stage tandem pulse tube refrigerator are connected in series, with the pulse tube of the previous cold head connected to the adjacent next cold head.

[0007] Furthermore, each stage of the cold head is composed of a room temperature heat exchanger, a regenerator, a cold end heat exchanger, a flow equalizer, and a pulse tube connected in sequence. This part is conventional technology in this field and will not be described in detail here.

[0008] Furthermore, the expansion work of the previous stage cold head is recycled as the input work of the next stage cold head.

[0009] Furthermore, the multi-stage tandem pulse tube refrigerator also includes a compressor and a phase-adjusting structure, wherein the compressor is a stepped piston compressor, which generates multiple compression chambers, and the different stages of the multiple compression chambers are respectively connected to each stage of the cold head.

[0010] More preferably, the phase-adjusting structure includes an inertial tube and a phase-adjusting gas reservoir at the end, and together with the compression chamber, it is phase-adjusted through the inertial tube and the phase-adjusting gas reservoir.

[0011] More preferably, an empty container is also provided at the connection between the first stage cold head and the compressor of the multi-stage tandem pulse tube refrigerator.

[0012] Furthermore, the number of stages in the cold head of the multi-stage tandem pulse tube refrigerator is n, and n≥2.

[0013] Furthermore, the current lead includes a room temperature section connector and a low temperature section connected as one piece. The end of the low temperature section away from the room temperature section connector is connected to a superconducting material. The low temperature section is provided with several levels of cold-conducting connection units in a gradient distribution direction from high to low temperature. Each level of cold-conducting connection unit is connected to a level of the cold head.

[0014] Furthermore, the cold-conducting connection unit includes a cold head connection section connected to the low-temperature section and a cold-conducting block connected to the cold head, wherein the cold head connection section and the cold-conducting block are pressed together by a nut. Preferably, a G10 sleeve can be added inside the screw hole to ensure electrical insulation.

[0015] More preferably, the contact interface between the cold head connecting section and the cooling block is further provided with three layers of laminated sheets, including an aluminum nitride gasket in the middle and indium sheets on the upper and lower sides (which can be divided into first indium sheets and second indium sheets depending on their positions). The aluminum nitride gasket in the middle serves to provide electrical insulation while ensuring good thermal conductivity. The first indium sheets and second indium sheets on the sides fill the gaps in the solid contact surface to increase the actual contact area, effectively reducing the interface thermal resistance and enhancing the interface heat transfer efficiency.

[0016] This invention, through research, reveals that the advantage of a multi-stage tandem pulse tube refrigerator is that it can provide cold heads with multiple cooling temperatures. These multi-stage cold heads can be matched to different temperature zones of superconducting current leads, achieving stepped cooling. The multi-stage tandem pulse tube refrigerator uses a multi-stage stepped piston compressor, which not only outputs power but also adjusts the phase of the cold heads. The advantage of the multi-stage cold head series connection is that the expansion work of the previous stage cold head is also the input work of the next stage cold head. The expansion work of the last stage is lost, and because the last stage has the lowest temperature and the smallest cooling capacity, the lost expansion work is also very small. The more stages in series, the closer the overall efficiency of the machine will be to Carnot efficiency, which is very beneficial for cooling superconducting current leads with large cooling capacity requirements.

[0017] Meanwhile, the temperature range of the current lead spans both room temperature and low temperature. The conduction heat leakage caused by the huge temperature difference on both sides and the Joule heat of the system operation become its main cooling load. This invention reduces the energy loss caused by existing cooling technology and the power consumption caused by refrigeration equipment by performing stepped cooling from the room temperature end to the low temperature end of the current lead, thereby improving the economy and stability of the entire system. Attached Figure Description

[0018] Figure 1 A simplified structural diagram of a three-stage tandem pulse tube refrigerator for cooling high-temperature superconducting current leads provided by the present invention;

[0019] Figure 2 This is a schematic diagram of the two-stage tandem pulse tube refrigerator for cooling high-temperature superconducting current leads of the present invention.

[0020] Figure 3 This is a schematic diagram of the cooling block connecting the cold head and the superconducting current lead of the present invention;

[0021] Figure 4 This is a schematic diagram of the connection between the primary cold head section and the primary cooling block of the present invention.

[0022] Explanation of markings in the diagram:

[0023] 10-Current lead; 11-Copper lead; 12-Superconducting material; 111-Room temperature range copper connector; 112-First-stage cold head connection section; 113-Second-stage cold head connection section; 114-Third-stage cold head connection section;

[0024] 20 - Multistage tandem pulse tube refrigerator; 21 - Compressor; 22 - First-stage cold head; 23 - Second-stage cold head; 24 - Third-stage cold head; 25 - Phase adjustment mechanism;

[0025] 221 - Primary cold head heat conduction block; 231 - Secondary cold head heat conduction block; 241 - Tertiary cold head heat conduction block;

[0026] 222 - First indium sheet; 223 - Aluminum nitride ceramic gasket; 224 - Second indium sheet. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] In this invention, unless otherwise specified, the functional components or structures are conventional components or structures used in the art to achieve the corresponding functions.

[0031] The present invention will now be described in detail.

[0032] In order to reduce energy loss caused by existing cooling technologies by performing stepped cooling from the room temperature end to the low temperature end of the current lead, in some embodiments, the present invention provides a multi-stage tandem pulse tube refrigerator-cooled superconducting current lead. The current lead (i.e., copper lead) is cooled from the room temperature range to the low temperature range by a multi-stage tandem pulse tube refrigerator with several stages of cold heads (i.e., multi-stage cold heads) that can provide stepped cooling temperatures.

[0033] In a specific implementation, the multi-stage cold head has n stages, where n ≥ 2. The multi-stage tandem pulse tube refrigerator consists of the first-stage cold head, the second-stage cold head, and so on, up to the nth-stage cold head, connected to the compressor. Based on the temperature distribution of the copper leads from room temperature to the low-temperature region, the copper leads are cooled in n stages.

[0034] Example 1:

[0035] like Figure 1As shown, this embodiment provides a three-stage tandem pulse tube refrigerator-cooled superconducting current lead, which includes two parts: a current lead 10 and a multi-stage tandem pulse tube refrigerator 20. The current lead 10 includes a copper lead 11 and a superconducting material 12. The copper lead 11 is divided into a room temperature section copper connector 111 and a low temperature section body. On the low temperature section body, a first-stage cold head connection section 112, a second-stage cold head connection section 113, and a third-stage cold head connection section 114 are arranged sequentially according to the temperature gradient change direction. The multi-stage tandem pulse tube refrigerator 20 includes a compressor 21, a first-stage cold head 22 (i.e., a high-temperature cold head), a second-stage cold head 23 (i.e., a medium-temperature cold head), a third-stage cold head 24 (i.e., a low-temperature cold head), and a phase adjustment mechanism 25. The first-stage cold head 22 is connected to the first-stage cold head heat conduction block 221, the second-stage cold head 23 is connected to the second-stage cold head heat conduction block 231, and the third-stage cold head 24 is connected to the third-stage cold head heat conduction block 241. The shapes of each heat conduction block are as follows: Figure 3 As shown.

[0036] Specifically, the first-stage cold head connecting section 112 is connected to the first-stage cold head cooling block 221, the second-stage cold head connecting section 113 is connected to the second-stage cold head cooling block 231, and the third-stage cold head connecting section 114 is connected to the third-stage cold head cooling block 241. Three-stage cooling is achieved, and to enhance heat exchange, each stage of the cold head connecting section is securely pressed against the cooling block using nuts.

[0037] Specifically, such as Figure 1 The three-stage tandem pulse tube refrigerator includes a compressor 21, a first-stage cold head 22, a second-stage cold head 23, a third-stage cold head 24, and a phase adjustment mechanism 25. The compressor 21 is a three-stage stepped reciprocating compressor, with each cold head connected in series. Each cold head includes a room temperature heat exchanger, a regenerator, a cold-end heat exchanger, a pulse tube, and a flow equalizer.

[0038] Example 2:

[0039] like Figure 2 As shown, this embodiment provides a two-stage tandem pulse tube cryocooler-cooled superconducting current lead. Unlike embodiment 1, it can perform two-stage cooling for low-power current lead applications, which can reduce the cost of the current lead. The cryocooler is equipped with two-stage cold heads, which correspondingly provide two-stage cooling for the room temperature and low temperature sections of the copper lead.

[0040] Specifically, to enhance thermal conductivity and electrical insulation, multiple layers of gaskets are installed at the connection points between each stage of the cold head and the superconducting cable. These multiple layers consist of three gaskets, such as... Figure 4As shown, from top to bottom, the components are: first indium sheet 222, aluminum nitride ceramic gasket 223, and second indium sheet 224; the aluminum nitride ceramic gasket can also be aluminum oxide powder or diamond film. The cold head cooling block, cold head connecting section, and multi-layer gasket are connected by nuts, and an insulating sleeve is installed in the screw hole. The insulating sleeve is made of G10 fiberglass and epoxy resin, which has excellent insulation, mechanical properties, and low-temperature resistance.

[0041] Meanwhile, in this embodiment, the room temperature section copper connector 111 is connected to the room temperature end of the copper lead 11 by soldering. The cooling blocks of each stage of the cold head are connected to the cold head by soldering.

[0042] It should be noted that any of the embodiments described in detail above can be implemented individually, or in any combination of two or more.

[0043] In summary, the multi-stage tandem pulse tube refrigerator-cooled superconducting current lead device provided by this invention features a compact structure and achieves highly efficient energy utilization. It significantly reduces the refrigerator's input power while meeting the cooling requirements of the superconducting current lead. This device has a wide range of applications, including superconducting current lead devices, and shows promising development prospects.

[0044] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A multistage cascade pulse tube refrigerator cooled superconducting current lead device, characterized by, The application relates to a current lead and a multi-stage cascade pulse tube refrigerator, wherein the multi-stage cascade pulse tube refrigerator comprises several stages of cold heads arranged in cascade and capable of providing cascade refrigeration temperatures, and each stage of cold heads sequentially cools the current lead from a room temperature section to a low temperature section from high temperature to low temperature. The stages of cold heads of the multi-stage cascade pulse tube refrigerator are sequentially connected in series, and the pulse tube of a front stage of cold heads is connected with an adjacent stage of cold heads. The number of stages of cold heads of the multi-stage cascade pulse tube refrigerator is n, and n>=2.

2. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 1, characterized in that, The expansion work of a front stage of cold heads is recycled as input work of a rear stage of cold heads.

3. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 1, wherein, The multi-stage cascade pulse tube refrigerator further comprises a compressor and a phase modulation structure, wherein the compressor is a stepped piston compressor, the stepped piston compressor generates a multi-stage compression cavity, and different stages of the multi-stage compression cavity are respectively connected with stages of cold heads.

4. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 3, wherein, The phase modulation structure comprises an inertia tube and a phase modulation gas reservoir arranged at the end, and the inertia tube, the phase modulation gas reservoir and the compression cavity are collectively phase modulated.

5. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 3, wherein, An empty container is additionally arranged at a connection position of the first stage of cold heads and the compressor.

6. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 1, wherein, The current lead comprises a room temperature section joint and a low temperature section connected as a whole, one end of the low temperature section away from the room temperature section joint is connected with superconducting material, and a plurality of stages of cold lead connection units are arranged on the low temperature section according to a temperature gradient distribution direction from high to low, and each stage of cold lead connection unit is connected with one stage of cold head.

7. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 6, wherein, The cold lead connection unit comprises a cold head connection section connected with the low temperature section and a cold lead block connected with the cold head, and the cold head connection section and the cold lead block are press-connected through a nut.

8. A multi-stage tandem pulse tube cryocooler cooled superconducting current lead device according to claim 7, characterized in that, A three-layer laminated sheet is further arranged at a contact interface between the cold head connection section and the cold lead block, and the three-layer laminated sheet comprises an aluminum nitride gasket arranged in the middle and indium sheets arranged on the upper and lower sides.

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