Low-temperature refrigerating system and superconducting maglev train with same

Abstract

The invention provides a low-temperature refrigerating system and a superconducting maglev train with the low-temperature refrigerating system. The system comprises a JT circulating precooler, a GM refrigerating machine, a storage tank, a first-stage heat exchanger, a second-stage heat exchanger, a third-stage heat exchanger, a throttling valve, a JT cold head, a liquid helium storage tank, a liquid nitrogen storage tank, a cold screen and a connecting assembly, wherein the JT circulating precooler is arranged at one end of the storage tank, a first-stage cold head and a second-stage cold head of the JT circulating precooler extend into the storage tank, the first-stage cold head is used for cooling a cold shield and carrying out first-stage precooling, and the second-stage cold head is used for carrying out second-stage precooling; the GM refrigerating machine is arranged at the other end of the storage tank, and a cold head of the GM refrigerating machine extends into the storage tank and is used for providing cold energy for the liquid nitrogen storage tank. The technical problems that in the prior art, a refrigerating machine is small in refrigerating capacity, large in power consumption and not suitable for vibration and magnetic field environments can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature refrigeration, and in particular to a low-temperature refrigeration system and a superconducting magnetic levitation train having the same. Background Art

[0002] At present, in the superconducting electric suspension system, the low-temperature superconducting coil can interact with the magnetic field to generate propulsion, suspension and guiding forces. However, if the low-temperature superconducting coil is to maintain the superconducting state, it needs to operate in the 4K temperature range. Among them, liquid helium immersion cooling can provide a stable low-temperature environment for the low-temperature superconducting coil to evenly cool the superconducting coil and maintain the stable operation of the superconducting coil. However, in order to prevent the liquid helium from volatilizing due to heat leakage from the magnet, a refrigerator is needed to cool the liquid helium. When the cooling capacity of the 4K refrigerator is greater than the heat leakage of the magnet, the liquid helium can achieve a closed circulation inside the magnet to avoid the vaporization and discharge of the liquid helium, which increases the refrigeration cost.

[0003] At present, commercial refrigerators are mainly used in static environments on the ground, and the 4K temperature zone is mainly based on GM refrigerators. The cooling capacity that the 4K temperature zone can provide is mainly 1.5W, 1.8W, and 2W. In maglev trains, the 4K heat leakage of the superconducting magnets required for the superconducting electric suspension system is above 4W, and the superconducting electric suspension system is in a vibrating environment. If a multi-cold head method is used to provide sufficient cooling for the magnet, the number of cold heads is generally 3 or more, and the power consumption exceeds 15kW. On the one hand, the weight of the magnet is increased, and at the same time, the power consumption will also increase significantly, which will bring a huge operating burden to the on-board power supply. Summary of the invention

[0004] The present invention provides a low-temperature refrigeration system and a superconducting magnetic levitation train having the same, which can solve the technical problems in the prior art that the refrigeration machine has a small cooling capacity, a large power consumption and is not suitable for vibration and magnetic field environments.

[0005] According to one aspect of the present invention, there is provided a low-temperature refrigeration system, the system comprising a JT cycle precooler, a GM refrigerator, a storage tank, and a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a throttle valve, a JT cold head, a liquid helium storage tank, a liquid nitrogen storage tank, a cold shield, and a connection assembly arranged in the storage tank;

[0006] The storage tank is kept in a vacuum state;

[0007] The first input end of the primary heat exchanger is connected to the output end of the first compressor, the first output end thereof is connected to the first input end of the secondary heat exchanger, the second input end thereof is connected to the second output end of the secondary heat exchanger, and the second output end thereof is connected to the input end of the first compressor; the first output end of the secondary heat exchanger is connected to the first input end of the tertiary heat exchanger, and the second input end thereof is connected to the second output end of the tertiary heat exchanger; the first output end of the tertiary heat exchanger is connected to the input end of the throttle valve; the input end of the JT cold head is connected to the output end of the throttle valve, and the output end thereof is connected to the second input end of the tertiary heat exchanger, and the JT cold head is used to provide coldness for the liquid helium storage tank;

[0008] The primary heat exchanger, the secondary heat exchanger, the tertiary heat exchanger, the throttle valve, the JT cold head, and the liquid helium storage tank are all arranged in the cold shield; one end of the cold shield is connected to one end of the storage tank through the connecting assembly; the liquid nitrogen storage tank is between the other end of the cold shield and the other end of the storage tank;

[0009] The JT cycle precooler is arranged at one end of the storage tank, and the primary cold head and the secondary cold head of the JT cycle precooler extend into the storage tank, the primary cold head is used to cool the cold screen and perform primary precooling on the helium between the first output end of the primary heat exchanger and the first input end of the secondary heat exchanger, and the secondary cold head is used to perform secondary precooling on the helium between the first output end of the secondary heat exchanger and the first input end of the tertiary heat exchanger;

[0010] The GM refrigerator is arranged at the other end of the storage tank, and a cold head of the GM refrigerator extends into the storage tank, and the cold head is used to provide cold capacity for the liquid nitrogen storage tank.

[0011] Preferably, the storage tank includes an outer cylinder, a first cover plate, a first connecting piece, a first sealing ring, a second cover plate, a second connecting piece and a second sealing ring; one end of the outer cylinder has a first flange structure, the first cover plate is connected to the first flange structure through the first connecting piece, the first flange structure has a first groove on the side facing the first cover plate, and the first sealing ring is arranged in the first groove; the other end of the outer cylinder has a second flange structure, the second cover plate is connected to the second flange structure through the second connecting piece, the second flange structure has a second groove on the side facing the second cover plate, and the second sealing ring is arranged in the second groove.

[0012] Preferably, the system further comprises a liquid helium filling pipe and a liquid nitrogen filling pipe, both of which are mounted on the first cover plate; one end of the liquid helium filling pipe is connected to the liquid helium storage tank for filling liquid helium into the liquid helium storage tank; one end of the liquid nitrogen filling pipe is connected to the liquid nitrogen storage tank for filling liquid nitrogen into the liquid nitrogen storage tank.

[0013] Preferably, the liquid helium filling pipe and the liquid nitrogen filling pipe have the same structure, and the liquid helium filling pipe or the liquid nitrogen filling pipe comprises a double-layer pipeline, an end cap and a third sealing ring; a vacuum interlayer is formed between the inner and outer walls of the double-layer pipeline, one end of the double-layer pipeline is connected to the liquid helium storage tank or the liquid nitrogen storage tank, and the other end is used to insert an external filling pipeline; the end cap is threadedly connected to the other end of the double-layer pipeline; the third sealing ring is arranged between the double-layer pipeline and the end cap, and is used to achieve sealing between the liquid helium filling pipe or the liquid nitrogen filling pipe and the external filling pipeline; the inner wall of the double-layer pipeline is divided into two sections, the inner wall diameter of the section close to the end cap is larger than the diameter of the external filling pipeline, and the inner wall diameter of the section away from the end cap is smaller than the diameter of the external filling pipeline.

[0014] Preferably, the connection between the two sections of the double-layer pipeline is tapered.

[0015] Preferably, the system further comprises a precooling pipe for precooling the liquid helium, and the precooling pipe has the same structure as the liquid helium filling pipe.

[0016] Preferably, the primary heat exchanger, the secondary heat exchanger, and the tertiary heat exchanger each include two plate heat exchangers; the two plate heat exchangers used for the primary heat exchange are connected in series and are sequentially placed at the lower part of the storage tank along the axial direction of the storage tank; the two plate heat exchangers used for the secondary heat exchange are connected in series and are sequentially placed at the upper and lower parts of the storage tank along the radial direction of the storage tank; the two plate heat exchangers used for the tertiary heat exchange are connected in series and are sequentially placed at the upper part of the storage tank along the axial direction of the storage tank.

[0017] Preferably, the system further comprises a plurality of brackets, wherein the brackets are used to support the storage tanks, and the brackets are provided with hollow structures.

[0018] Preferably, the system further comprises a bursting pipeline, one end of which is connected to the liquid helium storage tank and the other end of which extends out of the storage tank, and the bursting pipeline is used to balance the internal pressure of the liquid helium storage tank.

[0019] Preferably, the system further comprises a pressure sensor for measuring the pressure of the liquid helium storage tank.

[0020] Preferably, a helium exhaust port and a nitrogen exhaust port are provided on the first cover plate, the helium exhaust port is connected to the liquid helium storage tank through a pipeline, and the nitrogen exhaust port is connected to the liquid nitrogen storage tank through a pipeline.

[0021] According to another aspect of the present invention, a superconducting magnetic levitation train with a low-temperature refrigeration system is provided, wherein the train comprises any of the above-mentioned low-temperature refrigeration systems.

[0022] By applying the technical solution of the present invention, in the liquid helium temperature zone, the GM-JT principle is used for refrigeration to provide 5W of cold capacity to the liquid helium storage tank in the storage tank, and a JT cycle precooler is used as a precooler. The JT cycle is used to achieve large cold capacity output in the liquid helium temperature zone through three-stage heat exchange. While ensuring stable and sufficient cold capacity output, the present invention makes the refrigerator structure highly integrated and compact, adapts to the vehicle-mounted vibration environment, reduces the overall weight and power consumption of the refrigerator, and realizes the closed-loop operation of liquid helium inside the dynamic superconducting magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic structural diagram of a low-temperature refrigeration system provided according to an embodiment of the present invention is shown;

[0025] Figure 2 Shows Figure 1 Main view of the medium and low temperature refrigeration system;

[0026] Figure 3 Shows Figure 1 Left side view of the medium and low temperature refrigeration system;

[0027] Figure 4 Shows Figure 1 Schematic diagram of the structure of the middle filling pipe;

[0028] Figure 5 Shows Figure 1 Refrigeration flow chart of medium and low temperature refrigeration system;

[0029] Figure 6 Shows Figure 1 Schematic diagram of the layout of the medium and low temperature refrigeration system in the +Y axis direction;

[0030] Figure 7 Shows Figure 1Schematic diagram of the layout of the medium and low temperature refrigeration system in the -Y axis direction;

[0031] Figure 8 Shows Figure 1 Schematic diagram of the structure of the intercooler.

[0032] The above drawings include the following reference numerals:

[0033] 10. JT cycle precooler; 11. First stage cold head; 12. Second stage cold head; 13. Helium inlet; 14. Helium outlet; 20. GM refrigerator; 30. Storage tank; 31. Outer cylinder; 32. First cover plate; 33. First connector; 34. First sealing ring; 35. First groove; 40. First stage heat exchanger; 50. Second stage heat exchanger; 60. Third stage heat exchanger; 70. Throttle valve; 80. JT cold head; 90. Liquid helium storage tank; 100. Liquid nitrogen storage tank; 110. Cold screen; 120. Connecting assembly; 130. Liquid helium filling pipe; 131. Inner wall; 1311. First section inner wall; 1312. First section inner wall The second inner wall; 1313, the connection; 132, the outer wall; 133, the end cap; 134, the third sealing ring; 140, the liquid nitrogen filling pipe; 150, the precooling pipe; 160, the bracket; 170, the blasting pipeline; 180, the pressure sensor; 190, the helium exhaust port; 200, the nitrogen exhaust port; 210, the vacuum port; 220, the signal aviation plug; 230, the JT circulation helium inlet; 240, the JT circulation helium outlet; 250, the external filling pipe; 260, the first compressor; 270, the second compressor; 280, the annular support; 290, the base; 300, the support; 310, the interface. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0037] like Figure 1-Figure 8 As shown, the present invention provides a low-temperature refrigeration system, the system comprising a JT cycle precooler 10, a GM refrigerator 20, a storage tank 30, and a primary heat exchanger 40, a secondary heat exchanger 50, a tertiary heat exchanger 60, a throttle valve 70, a JT cold head 80, a liquid helium storage tank 90, a liquid nitrogen storage tank 100, a cold shield 110, and a connection assembly 120 arranged in the storage tank 30;

[0038] The storage tank 30 is kept in a vacuum state;

[0039] The first input end of the primary heat exchanger 40 is connected to the output end of the first compressor 260, the first output end thereof is connected to the first input end of the secondary heat exchanger 50, the second input end thereof is connected to the second output end of the secondary heat exchanger 50, and the second output end thereof is connected to the input end of the first compressor 260; the first output end of the secondary heat exchanger 50 is connected to the first input end of the tertiary heat exchanger 60, and the second input end thereof is connected to the second output end of the tertiary heat exchanger 60; the first output end of the tertiary heat exchanger 60 is connected to the input end of the throttle valve 70; the input end of the JT cold head 80 is connected to the output end of the throttle valve 70, and the output end thereof is connected to the second input end of the tertiary heat exchanger 60, and the JT cold head 80 is used to provide coldness for the liquid helium storage tank 90;

[0040] The primary heat exchanger 40, the secondary heat exchanger 50, the tertiary heat exchanger 60, the throttle valve 70, the JT cold head 80, and the liquid helium storage tank 90 are all arranged in the cold shield 110; one end of the cold shield 110 is connected to one end of the storage tank 30 through the connecting assembly 120; the liquid nitrogen storage tank 100 is between the other end of the cold shield 110 and the other end of the storage tank 30;

[0041] The JT cycle precooler 10 is arranged at one end of the storage tank 30, and the primary cold head 11 and the secondary cold head 12 of the JT cycle precooler 10 extend into the storage tank 30, the primary cold head 11 is used to cool the cold shield 110 and perform primary precooling on the helium between the first output end of the primary heat exchanger 40 and the first input end of the secondary heat exchanger 50, and the secondary cold head 12 is used to perform secondary precooling on the helium between the first output end of the secondary heat exchanger 50 and the first input end of the tertiary heat exchanger 60;

[0042] The GM refrigerator 20 is disposed at the other end of the storage tank 30 , and a cold head of the GM refrigerator 20 extends into the storage tank 30 , and the cold head is used to provide cold energy for the liquid nitrogen storage tank 100 .

[0043] The present invention uses the GM-JT principle to provide 5W of cold capacity to the liquid helium storage tank 90 in the storage tank 30 in the liquid helium temperature zone, adopts the JT cycle precooler 10 as a precooler, and adopts the JT cycle to achieve large cold capacity output in the liquid helium temperature zone through three-stage heat exchange. While ensuring stable and sufficient cold capacity output, the present invention makes the refrigerator structure highly integrated and compact, adapts to the vehicle-mounted vibration environment, reduces the overall weight and power consumption of the refrigerator, and realizes the closed-loop operation of liquid helium inside the dynamic superconducting magnet.

[0044] According to an embodiment of the present invention, the system further comprises a plurality of brackets 160 , wherein the brackets 160 are used to support the storage tanks 30 , and the brackets 160 are provided with a hollow structure.

[0045] like Figure 1As shown, there are three brackets 160, and the cryogenic storage tank 30 is placed horizontally. It is installed and fixed with the superconducting magnet through three brackets 160. The bracket 160 is made of aluminum alloy. The support of the bracket 160 adopts a triangular hollow design, which can ensure the strength and stability of the support of the storage tank 30 while achieving lightweight. A JT cycle precooler 10 is installed at the end of the storage tank 30 for JT cycle precooling, and a GM refrigerator 20 is installed at the tail of the storage tank 30 to provide cold for 77K liquid nitrogen. There are two interfaces 310 connected to the outer dewar of the magnet on the side of the outer cylinder 31 of the storage tank 30, which can be connected with the vacuum interlayer of the superconducting magnet. Pipelines can be designed inside the interface 310 to realize the connection and interaction between the cryogenic storage tank 30 and the inner dewar of the magnet to form internal liquid helium, liquid nitrogen, helium and nitrogen. A vacuum port 210 is designed on the side of the outer cylinder 31 of the storage tank 30 near the end, which can be connected to the vacuum unit to perform vacuum operation to maintain the low temperature environment inside the storage tank 30. When the vacuum is completed, the angle valve at the vacuum is closed to ensure the vacuum degree inside the low-temperature storage tank 30.

[0046] According to an embodiment of the present invention, the storage tank 30 includes an outer cylinder 31, a first cover plate 32, a first connecting piece 33, a first sealing ring 34, a second cover plate, a second connecting piece and a second sealing ring; one end of the outer cylinder 31 has a first flange structure, the first cover plate 32 is connected to the first flange structure through the first connecting piece 33, the first flange structure has a first groove 35 on the side facing the first cover plate 32, and the first sealing ring 34 is arranged in the first groove 35; the other end of the outer cylinder 31 has a second flange structure, the second cover plate is connected to the second flange structure through the second connecting piece, the second flange structure has a second groove on the side facing the second cover plate, and the second sealing ring is arranged in the second groove.

[0047] like Figure 2 As shown, taking one end of the storage tank 30 as an example, the first connecting member 33 of the storage tank 30 adopts screws, the first sealing ring 34 adopts an O-ring, and the first cover plate 32 and the first flange structure adopt an O-ring for mechanical sealing, which can improve the convenience of disassembly and maintenance of the cylinder body of the low-temperature storage tank 30. The first cover plate 32 and the first flange structure of the outer cylinder 31 are fixed with 16 screws evenly distributed along the circumference to ensure the reliability of the seal. The O-ring can be made of silicone rubber or fluororubber according to the operating temperature range.

[0048] According to one embodiment of the present invention, the system further includes a bursting pipeline 170, one end of which is connected to the liquid helium storage tank 90, and the other end of which extends out of the storage tank 30, and the bursting pipeline 170 is used to balance the internal pressure of the liquid helium storage tank 90. ​​The system further includes a pressure sensor 180, which is used to measure the pressure of the liquid helium storage tank 90. ​​The first cover plate 32 is provided with a helium exhaust port 190 and a nitrogen exhaust port 200, the helium exhaust port 190 is connected to the liquid helium storage tank 90 through a pipeline, and the nitrogen exhaust port 200 is connected to the liquid nitrogen storage tank 100 through a pipeline. The system further includes a liquid helium filling pipe 130 and a liquid nitrogen filling pipe 140, both of which are installed on the first cover plate 32; one end of the liquid helium filling pipe 130 is connected to the liquid helium storage tank 90 for filling liquid helium into the liquid helium storage tank 90; one end of the liquid nitrogen filling pipe 140 is connected to the liquid nitrogen storage tank 100 for filling liquid nitrogen into the liquid nitrogen storage tank 100. The system further includes a precooling pipe 150 for precooling the filled liquid helium.

[0049] like Figure 3 As shown, through the +X axis direction, the interface layout diagram of the first cover plate 32 at the end of the cryogenic storage tank 30 can be seen. Figure 3 In the embodiment, the signal air plug 220 can be connected to an external monitoring device, and the temperature and liquid level inside the cryogenic system can be monitored through the electrical interface. The end of the bursting pipeline 170 is sealed with a bursting disc. The liquid helium inside the storage tank 30 evaporates in large quantities, causing internal pressure. When the absolute pressure exceeds 3 bar, the bursting disc will automatically open, quickly releasing the helium in the liquid helium storage tank 90 in the cryogenic system, balancing the internal pressure, and protecting the safety and stability of the internal structure of the cryogenic system. The JT cycle helium inlet 230 and outlet are connected to the external first compressor 260, and the helium can form a JT (Joule-Thomson) refrigeration cycle system under the drive of the first compressor 260. The helium inlet and outlet (13, 14) of the JT cycle precooler 10 are connected to the external second compressor 270. The helium exhaust port 190 and the nitrogen exhaust port 200 on the first cover plate 32 are mainly used for gas discharge when the liquid helium and liquid nitrogen stored inside the cryogenic system evaporate. The three filling pipelines on the first cover plate 32 are inclined at an angle of 60° to the horizontal line, which can achieve a compact layout in the case of multiple interfaces on the cover plate of the storage tank 30 and facilitate manual filling operations.

[0050] According to an embodiment of the present invention, the liquid helium filling pipe 130 , the liquid nitrogen filling pipe 140 and the precooling pipe 150 have the same structure. Specifically, the liquid helium filling pipe 130 or the liquid nitrogen filling pipe 140 includes a double-layer pipeline, an end cap 133 and a third sealing ring 134; a vacuum interlayer is formed between the inner and outer walls 132 of the double-layer pipeline, one end of the double-layer pipeline is connected to the liquid helium storage tank 90 or the liquid nitrogen storage tank 100, and the other end is used to insert the external filling pipe 250; the end cap 133 is threadedly connected to the other end of the double-layer pipeline; the third sealing ring 134 is arranged between the double-layer pipeline and the end cap 133, and is used to achieve sealing between the liquid helium filling pipe 130 or the liquid nitrogen filling pipe 140 and the external filling pipe 250; the inner wall 131 of the double-layer pipeline is divided into two sections, the inner wall 1311 of a section close to the end cap 133 has a diameter greater than the diameter of the external filling pipe 250, and the inner wall 1312 of a section away from the end cap 133 has a diameter smaller than the diameter of the external filling pipe 250.

[0051] like Figure 4 The figure shows the cross-sectional structure of the three filling pipelines. Figure 4 In the figure, there are two sections of the inner wall 131 of the pipeline. The first section of the inner wall 1311 is the inserted channel of the filling pipeline, and the thicker diameter is used for the liquid nitrogen and liquid helium filling pipe 130 insertion structure. The end of the inserted channel is a conical structure, and the acute angle between the cone and the horizontal line is 45°. The second section of the inner wall 1312 after the conical structure is a thin tube with a variable diameter, which is the flow channel for the refrigerant. After the external filling pipe 250 is inserted into the inserted channel of the filling pipeline, the end contacts the conical structure, which can automatically align the external filling pipe 250 with the refrigerant flow channel pipe mouth at the bottom to prevent the liquid nitrogen and liquid helium from flowing unobstructed. The end cap 133 at the top of the filling pipeline is rotatably fixed to the pipe mouth with threads, and the pipe mouth is sealed with an O-type rubber sealing ring. After the external filling pipe 250 passes through the O-type rubber sealing ring, the O-type rubber sealing ring is squeezed by the end cap 133 and the filling port and deformed toward the middle, squeezing the external filling pipe 250, thereby sealing and fixing the external filling pipe 250 and the pipe port, avoiding the overflow and loss of the filled liquid helium and liquid nitrogen, or the inability to complete the liquid helium filling due to insufficient sealing and vaporization of the liquid helium.

[0052] like Figure 5As shown, it is a refrigeration flow chart of the low-temperature refrigeration system. The JT cycle adopts a three-stage heat exchanger 60, based on the JT cycle precooler 10, to provide a precooling cold source. The first compressor 260 is used to provide high-pressure helium. When the helium flows from the first-stage heat exchanger 40 to the second-stage heat exchanger 50, the first-stage cold head 11 of the JT cycle precooler 10 is used to perform the first-stage precooling of the JT cycle helium pipeline; when the helium flows from the second-stage heat exchanger 50 to the third-stage heat exchanger 60, the second-stage cold head 12 of the JT cycle precooler 10 is used to perform the second-stage precooling of the JT cycle helium pipeline. After capillary throttling, a low temperature of 4.5K is obtained to provide 5W cooling capacity for the liquid helium storage tank 90, thereby realizing helium liquefaction. At the same time, the cold head of the GM refrigerator 20 is placed in the liquid phase area of ​​the liquid nitrogen storage tank 100 to increase the cooling capacity of the liquid nitrogen storage tank 100, thereby realizing nitrogen liquefaction. At the same time, the JT cycle precooler 10 and the GM refrigerator 20 share a compressor to drive the helium to circulate in two ways at the same time, so as to realize GM machine refrigeration.

[0053] like Figure 6 and Figure 7 As shown, they are schematic diagrams of the structure of the low-temperature refrigeration system from the perspectives along the +Y and -Y axis directions, respectively. The first-stage cold head 11 of the JT cycle precooler 10 is installed and fixed on the end panel of the cold shield 110. The cold shield 110 can be cooled by the JT cycle precooler 10 to keep the temperature of the cold shield 110 at about 65K, mainly to reduce the radiation heat leakage from the outside to the JT cycle internal heat exchanger, pipeline, and liquid helium storage tank 90. ​​The internal cold shield 110 is designed with aluminum alloy, which has a high thermal conductivity and can quickly conduct the cold energy of the JT cycle precooler 10 to the entire cold shield 110, so that the cold shield 110 can be quickly cooled. At the same time, the weight of the aluminum alloy is lighter, which can effectively reduce the weight of the storage tank 30 and achieve lightweight to adapt to the vehicle-mounted use environment. The primary heat exchanger 40, the secondary heat exchanger 50, and the tertiary heat exchanger 60 each include two plate heat exchangers; the two plate heat exchangers for primary heat exchange are connected in series and are sequentially placed at the lower part of the storage tank 30 along the axial direction of the storage tank 30; the two plate heat exchangers for secondary heat exchange are connected in series and are sequentially placed at the upper and lower parts of the storage tank 30 along the radial direction of the storage tank 30; the two plate heat exchangers for tertiary heat exchange are connected in series and are sequentially placed at the upper part of the storage tank 30 along the axial direction of the storage tank 30. The JT cold head 80 is placed in the gas phase area of ​​the liquid helium storage tank 90, and the large amount of cold energy generated by the JT cold head 80 liquefies the helium in the upper part of the storage tank 30, realizing the closed cycle of the liquid helium storage tank 90. The cold head of the GM refrigerator 20 is placed on the upper part of the liquid nitrogen storage tank 100, mainly for cooling the liquid nitrogen. The overall temperature of the liquid nitrogen storage tank 100 is about 77K, which can serve as a cold shield 110 for the end of the liquid helium storage tank 90 close to the tail of the storage tank 30, thereby reducing the radiation heat leakage of the liquid helium storage tank 90 from the outside.

[0054] like Figure 8As shown, the cold shield 110 is mainly used to reduce the external radiation heat leakage for the JT circulation system and the liquid helium storage tank 90. ​​The cold shield 110 is a thin-walled cylindrical structure, designed with aluminum alloy. The connecting assembly 120 adopts a tie rod. The end flange of the storage tank 30 is connected to the end of the cold shield 110 through three low-temperature insulation composite tie rods. The cold shield 110 can be restricted in the X-axis direction to prevent the storage tank 30 from being displaced in the X-axis direction due to operation vibration. The cold shield 110 is respectively covered with two cold shield 110 annular support members 280 in the circumferential direction for limiting and supporting. The annular support member 280 is respectively provided with two low-temperature insulation composite support members 300 in the Z-axis and Y-axis directions, which are fixed on the aluminum alloy base 290. The aluminum alloy base 290 is welded to the cold shield 110, thereby playing a role in fixing and supporting the cylinder of the cold shield 110 in the radial direction. In addition, the tie rods and annular support members 280 of the cold shield 110 are made of low-temperature insulation composite materials, which can effectively reduce the conduction heat leakage from the outer cylinder 31 of the storage tank 30 to the cold shield 110 from 300K by utilizing thermal conductivity, thereby reducing the heat load of the GM refrigerator 20.

[0055] The present invention also provides a superconducting magnetic levitation train with a low-temperature refrigeration system, wherein the train comprises any of the above-mentioned low-temperature refrigeration systems.

[0056] In summary, the present invention provides a low-temperature refrigeration system and a superconducting maglev train having the same. In the liquid helium temperature zone, the GM-JT principle is used for refrigeration to provide 5W of cold capacity to the liquid helium storage tank 90 in the storage tank 30, and the JT cycle precooler 10 is used as a precooler. The JT cycle is used to achieve large cold capacity output in the liquid helium temperature zone through three-stage heat exchange. While ensuring stable and sufficient cold capacity output, the present invention makes the refrigerator structure highly integrated and compact, adapts to the vehicle-mounted vibration environment, reduces the overall weight and power consumption of the refrigerator, and realizes the closed-loop operation of liquid helium inside the dynamic superconducting magnet.

[0057] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0058] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0059] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low temperature refrigeration system, It is characterized in that The system includes a JT cycle precooler, a GM refrigerator, a storage tank, and a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a throttle valve, a JT cold head, a liquid helium storage tank, a liquid nitrogen storage tank, a cold screen, and a connection component arranged in the storage tank; The storage tank is kept in a vacuum state; The first input end of the primary heat exchanger is connected to the output end of the first compressor, the first output end thereof is connected to the first input end of the secondary heat exchanger, the second input end thereof is connected to the second output end of the secondary heat exchanger, and the second output end thereof is connected to the input end of the first compressor; the first output end of the secondary heat exchanger is connected to the first input end of the tertiary heat exchanger, and the second input end thereof is connected to the second output end of the tertiary heat exchanger; the first output end of the tertiary heat exchanger is connected to the input end of the throttle valve; the input end of the JT cold head is connected to the output end of the throttle valve, and the output end thereof is connected to the second input end of the tertiary heat exchanger, and the JT cold head is used to provide coldness for the liquid helium storage tank; The primary heat exchanger, the secondary heat exchanger, the tertiary heat exchanger, the throttle valve, the JT cold head, and the liquid helium storage tank are all arranged in the cold shield; one end of the cold shield is connected to one end of the storage tank through the connecting assembly; the liquid nitrogen storage tank is between the other end of the cold shield and the other end of the storage tank; The JT cycle precooler is arranged at one end of the storage tank, and the primary cold head and the secondary cold head of the JT cycle precooler extend into the storage tank, the primary cold head is used to cool the cold screen and perform primary precooling on the helium between the first output end of the primary heat exchanger and the first input end of the secondary heat exchanger, and the secondary cold head is used to perform secondary precooling on the helium between the first output end of the secondary heat exchanger and the first input end of the tertiary heat exchanger; The GM refrigerator is arranged at the other end of the storage tank, and a cold head of the GM refrigerator extends into the storage tank, and the cold head is used to provide cold capacity for the liquid nitrogen storage tank.

2. The system according to claim 1, It is characterized in that The storage tank includes an outer cylinder, a first cover plate, a first connecting piece, a first sealing ring, a second cover plate, a second connecting piece and a second sealing ring; one end of the outer cylinder has a first flange structure, the first cover plate is connected to the first flange structure through the first connecting piece, the first flange structure has a first groove on the side facing the first cover plate, and the first sealing ring is arranged in the first groove; the other end of the outer cylinder has a second flange structure, the second cover plate is connected to the second flange structure through the second connecting piece, the second flange structure has a second groove on the side facing the second cover plate, and the second sealing ring is arranged in the second groove.

3. The system according to claim 1 or 2, It is characterized in that The system further includes a liquid helium filling pipe and a liquid nitrogen filling pipe, both of which are installed on the first cover plate; one end of the liquid helium filling pipe is connected to the liquid helium storage tank for filling liquid helium into the liquid helium storage tank; one end of the liquid nitrogen filling pipe is connected to the liquid nitrogen storage tank for filling liquid nitrogen into the liquid nitrogen storage tank.

4. The system according to claim 3, It is characterized in that The liquid helium filling pipe and the liquid nitrogen filling pipe have the same structure, and the liquid helium filling pipe or the liquid nitrogen filling pipe comprises a double-layer pipeline, an end cap and a third sealing ring; a vacuum interlayer is formed between the inner and outer walls of the double-layer pipeline, one end of the double-layer pipeline is connected to the liquid helium storage tank or the liquid nitrogen storage tank, and the other end is used to insert an external filling pipeline; the end cap is threadedly connected to the other end of the double-layer pipeline; the third sealing ring is arranged between the double-layer pipeline and the end cap, and is used to achieve sealing between the liquid helium filling pipe or the liquid nitrogen filling pipe and the external filling pipeline; the inner wall of the double-layer pipeline is divided into two sections, the inner wall diameter of the section close to the end cap is larger than the diameter of the external filling pipeline, and the inner wall diameter of the section away from the end cap is smaller than the diameter of the external filling pipeline.

5. The system according to claim 4, It is characterized in that The connection between the two sections of the double-layer pipeline is tapered.

6. The system according to claim 3, It is characterized in that The system further comprises a precooling pipe for precooling the liquid helium filling, and the precooling pipe has the same structure as the liquid helium filling pipe.

7. The system according to claim 1, It is characterized in that The primary heat exchanger, the secondary heat exchanger, and the tertiary heat exchanger all include two plate heat exchangers; the two plate heat exchangers used for primary heat exchange are connected in series and are placed in sequence at the lower part of the storage tank along the axial direction of the storage tank; the two plate heat exchangers used for secondary heat exchange are connected in series and are placed in sequence at the upper and lower parts of the storage tank along the radial direction of the storage tank; the two plate heat exchangers used for tertiary heat exchange are connected in series and are placed in sequence at the upper part of the storage tank along the axial direction of the storage tank.

8. The system according to claim 1, It is characterized in that The system further comprises a plurality of brackets, wherein the brackets are used to support the storage tanks and the brackets are provided with hollow structures.

9. The system according to claim 1, It is characterized in that The system further comprises a bursting pipeline, one end of which is connected to the liquid helium storage tank and the other end of which extends out of the storage tank, and the bursting pipeline is used to balance the internal pressure of the liquid helium storage tank.

10. The system according to claim 1, It is characterized in that The system further includes a pressure sensor for measuring the pressure of the liquid helium storage tank.

11. The system according to claim 2, It is characterized in that The first cover plate is provided with a helium exhaust port and a nitrogen exhaust port. The helium exhaust port is connected to the liquid helium storage tank through a pipeline, and the nitrogen exhaust port is connected to the liquid nitrogen storage tank through a pipeline.

12. A superconducting magnetic levitation train with a low-temperature refrigeration system, It is characterized in that The train comprises the low-temperature refrigeration system as claimed in any one of claims 1-11.

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