A dual-circuit refrigeration system

Abstract

The present invention discloses a dual-circuit refrigeration system, comprising a first main body with a first cavity, a second main body arranged in the first main body and having a second cavity, a third main body arranged in the second main body and having a third cavity, a liquid nitrogen dewar arranged in the second main body, a liquid helium dewar arranged in the third main body, a fourth main body arranged in the third main body and having a fourth cavity, and an outlet pipe whose one end is connected to the fourth main body and whose other end passes through the third main body, the second main body and the first main body in sequence; the dual-circuit refrigeration system also includes a precooling pipeline and a refrigeration pipeline: the precooling pipeline enters the first main body from the outside and is connected to the fourth main body after heat exchange with the liquid nitrogen dewar and the liquid helium dewar in sequence; the refrigeration pipeline enters the first main body from the outside and is connected to the fourth main body after heat exchange with the liquid nitrogen dewar and the liquid helium dewar in sequence, and then is connected to the fourth main body through an expansion valve, and the expansion valve is located in the third main body. The dual-circuit refrigeration system of the present invention can quickly reduce the temperature to 1-2K, and the refrigeration efficiency is relatively high.

Description

Technical Field

[0001] The invention relates to the technical field of JT refrigerators, and in particular to a dual-circuit refrigeration system. Background Art

[0002] The refrigeration system is an important means to achieve 1-2K low-temperature experimental conditions. The existing refrigeration system generally uses an expansion valve to increase the expansion ratio of helium to reduce the temperature to 1-2K. However, the flow rate of helium through the expansion valve is slow, and the adjustment of the expansion valve will also destroy the vacuum environment and the low-temperature environment. Therefore, the overall cooling speed of the refrigeration system is slow and the refrigeration efficiency is relatively low. Summary of the invention

[0003] The object of the present invention is to provide a dual-circuit refrigeration system which can quickly reduce the temperature to 1-2K and has a relatively high refrigeration efficiency.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A dual-circuit refrigeration system comprises a first body having a first cavity, a second body disposed in the first body and having a second cavity, a third body disposed in the second body and having a third cavity, a liquid nitrogen dewar disposed in the second body, and a liquid helium dewar disposed in the third body;

[0006] The dual-circuit refrigeration system further includes a fourth body disposed in the third body and having a fourth cavity, and an air outlet pipe having one end connected to the fourth body and the other end passing through the third body, the second body and the first body in sequence;

[0007] The dual-circuit refrigeration system also includes a precooling pipeline and a refrigeration pipeline:

[0008] The precooling pipeline enters the first main body from the outside and exchanges heat with the liquid nitrogen dewar and the liquid helium dewar in sequence before being connected to the fourth main body;

[0009] The refrigeration pipeline enters the first body from the outside and exchanges heat with the liquid nitrogen dewar and the liquid helium dewar in sequence, and then communicates with the fourth body after passing through an expansion valve, and the expansion valve is located in the third body.

[0010] Preferably, after the refrigeration pipeline exchanges heat with the liquid helium Dewar, it first passes through a countercurrent regenerative heat exchanger and then passes through the expansion valve. The countercurrent regenerative heat exchanger is located in the third body and is used for exchanging heat with the outlet pipe.

[0011] Preferably, the liquid nitrogen dewar and the liquid helium dewar are respectively arranged in an annular manner in the second body and the third body, and the gas outlet pipe extends upward from the central through holes of the liquid nitrogen dewar and the liquid helium dewar.

[0012] More preferably, the fourth body is located at the bottom of the central through hole of the liquid helium Dewar.

[0013] Preferably, the second body is hoisted in the first body, the top of the second body is a first heat sink connected to the liquid nitrogen Dewar for heat transfer, and the outlet pipe is provided with a first outlet heat exchanger for exchanging heat with the first heat sink.

[0014] More preferably, the third body is hoisted in the second body, the top of the third body is a second heat sink connected to the liquid helium Dewar for heat transfer, and the outlet pipe is provided with a second outlet heat exchanger for exchanging heat with the second heat sink.

[0015] More preferably, the second heat sink is also used for exchanging heat for the precooling pipeline and the refrigeration pipeline respectively.

[0016] Preferably, a first air inlet heat exchanger for respectively exchanging heat for the precooling pipeline and the refrigeration pipeline is provided at the bottom of the liquid nitrogen dewar.

[0017] Preferably, a second air inlet heat exchanger for respectively exchanging heat for the precooling pipeline and the refrigeration pipeline is provided at the bottom of the liquid helium dewar.

[0018] Preferably, the dual-circuit refrigeration system further comprises an air extraction pump disposed on the outside of the first main body and connected to the air outlet pipe.

[0019] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the dual-circuit refrigeration system of the present invention is provided with a precooling pipeline and a refrigeration pipeline, the precooling pipeline is not connected to the expansion valve, the precooling pipeline enters the first body from the outside, and the helium flow rate therein can be freely adjusted from the outside and set to be relatively large, so as to quickly reduce the temperature to about 4K; then the helium is further reduced to 1-2K through the refrigeration pipeline connected to the expansion valve. The dual-circuit refrigeration system can relatively quickly reduce the temperature to 1-2K, and the refrigeration efficiency is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Attached Figure 1 Schematic diagram of the structure of a dual-circuit refrigeration system according to a specific embodiment of the present invention.

[0021] Among them: 1. first main body; 2. second main body; 21. first heat sink; 22. first cold screen; 3. third main body; 31. second heat sink; 32. second cold screen; 4. liquid nitrogen dewar; 5. liquid helium dewar; 6. fourth main body; 7. outlet pipe; 8. expansion valve; 9. countercurrent regenerative heat exchanger; 10. first outlet heat exchanger; 11. second outlet heat exchanger; 12. first inlet heat exchanger; 13. second inlet heat exchanger; 14. vacuum pump; 15. experimental assembly; 16. precooling pipeline; 17. refrigeration pipeline; 18. third inlet heat exchanger. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with specific embodiments and drawings.

[0023] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0024] In the description of the embodiments of the present invention, it should be understood that the terms "length", "inside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure below provides many different embodiments or examples to implement different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present invention. In addition, the embodiments of the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0029] See also Figure 1 As shown, this embodiment provides a dual-circuit refrigeration system, including a first body 1 having a first cavity, a second body 2 disposed in the first body 1 and having a second cavity, a third body 3 disposed in the second body 2 and having a third cavity, a liquid nitrogen dewar 4 disposed in the second body 2, a liquid helium dewar 5 disposed in the third body 3, and a fourth body 6 disposed in the third body 3 and having a fourth cavity, wherein the fourth body 6 is used to connect the experimental component 15.

[0030] In this embodiment:

[0031] The second body 2 is hoisted in the first body 1, the top of the second body 2 is a first heat sink 21 connected to the liquid nitrogen Dewar 4 for heat transfer, the second body 2 also includes a first cold shield 22 connected below the liquid nitrogen Dewar 4, and the third body 3 is arranged in the first cold shield 22;

[0032] The third body 3 is hoisted in the second body 2 . The top of the third body 3 is a second heat sink 31 which is heat-transferably connected to the liquid helium dewar 5 . The third body 3 also includes a second cold shield 32 connected below the liquid helium dewar 5 . The fourth body 6 and the experimental assembly 15 are arranged in the second cold shield 32 .

[0033] The dual-circuit refrigeration system further includes an air outlet pipe 7 whose one end is connected to the fourth body 6 and whose other end passes through the third body 3, the second body 2 and the first body 1 in sequence, and an air extraction pump 14 arranged outside the first body 1 and connected to the air outlet pipe 7.

[0034] In this embodiment, the liquid nitrogen dewar 4 and the liquid helium dewar 5 are respectively arranged in the second body 2 and the third body 3, and the gas outlet pipe 7 extends upward from the central through holes of the liquid nitrogen dewar 4 and the liquid helium dewar 5. The fourth body 6 is located at the bottom of the central through hole of the liquid helium dewar 5, and the lower end of the gas outlet pipe 7 is connected to the fourth body 6. The gas outlet pipe 7 passes through the liquid helium dewar 5, the second heat sink 31, the liquid nitrogen dewar 4, the first heat sink 21 and the top of the first body 1 in sequence.

[0035] Since the temperature of the helium gas outputted from the fourth body 6 is relatively low, the outlet pipe 7 is provided with a first outlet heat exchanger 10 for exchanging heat with the first heat sink 21 and a second outlet heat exchanger 11 for exchanging heat with the second heat sink 31. This arrangement is used to cool the first heat sink 21 and the second heat sink 31 to save cooling capacity.

[0036] The above-mentioned dual-circuit refrigeration system further includes a precooling pipeline 16 and a refrigeration pipeline 17:

[0037] The precooling pipeline 16 enters the first main body 1 from the outside, passes through the first section of the precooling stainless steel capillary tube into and out of the liquid nitrogen dewar 4, and exchanges heat through the first air inlet heat exchanger 12 at the bottom of the liquid nitrogen dewar 4, then passes through the second section of the precooling stainless steel capillary tube, and exchanges heat with the second heat sink 31 through the third air inlet heat exchanger 18 on the second heat sink 31, and finally passes through the third section of the precooling stainless steel capillary tube into and out of the liquid helium dewar 5, and exchanges heat through the second air inlet heat exchanger 13 at the bottom of the liquid helium dewar 5, and then enters the fourth main body 6 for expansion and refrigeration, and the precooled helium after endothermic expansion is pumped out by the vacuum pump 14;

[0038] The refrigeration pipeline 17 enters the first main body 1 from the outside, passes through the first section of the refrigeration stainless steel capillary tube to pass through the liquid nitrogen dewar 4, and exchanges heat through the first air inlet heat exchanger 12 at the bottom of the liquid nitrogen dewar 4, then passes through the second section of the refrigeration stainless steel capillary tube, and exchanges heat with the second heat sink 31 through the third air inlet heat exchanger 18 on the second heat sink 31, and finally passes through the third section of the refrigeration stainless steel capillary tube to pass through the liquid helium dewar 5, and exchanges heat through the second air inlet heat exchanger 13 at the bottom of the liquid helium dewar 5, then enters the countercurrent regenerative heat exchanger 9 to exchange heat with the outlet pipe 7 and further cool down, and then increases the expansion ratio through the expansion valve 8 to improve the refrigeration effect, and finally enters the fourth main body 6 for expansion and refrigeration, and the refrigerated helium after endothermic expansion is extracted by the exhaust pump 14;

[0039] The expansion valve 8 and the counterflow recuperator 9 are respectively located in the third body 3 .

[0040] In this embodiment, two groups of second heat sinks 31 are arranged from top to bottom. The lower second heat sink 31 has a relatively low temperature and is used to perform heat exchange for the helium in the precooling pipeline 16 and the refrigeration pipeline 17 .

[0041] The comparative example is a single-circuit refrigeration system having only the refrigeration pipeline 17. After the single-circuit refrigeration system and the dual-circuit refrigeration system of this embodiment are respectively filled with liquid nitrogen and liquid helium, the fourth body 6 reaches about 10K in about 15 hours.

[0042] In the comparative example, only the refrigeration pipeline is opened to allow helium refrigeration, and the fourth body 6 can reach near 1K after about 2 hours; in this embodiment, the precooling pipeline 16 and the refrigeration pipeline 17 are opened in sequence to allow helium refrigeration, and the fourth body 6 can reach near 1K after only about 40 minutes. Since the precooling pipeline 16 enters the first body 1 from the outside, the helium flow in the precooling pipeline 16 can be adjusted at will without worrying about damaging the vacuum environment and the low temperature environment.

[0043] The working process of this embodiment is described in detail below:

[0044] The precooling pipeline 16 is opened, and the helium in the precooling pipeline 16 is heat-exchanged to 77K through the first air inlet heat exchanger 12 at the bottom of the liquid nitrogen dewar 4, and then heat-exchanged with the second heat sink 31 and heat-exchanged to 20K, and finally heat-exchanged to 4K through the second air inlet heat exchanger 13 at the bottom of the liquid helium dewar 5, and then enters the fourth body 6 for expansion and refrigeration, and the precooled helium after endothermic expansion is pumped out by the vacuum pump 14;

[0045] When the temperature of the fourth body 6 reaches about 4K, the precooling pipeline 16 is closed and the refrigeration pipeline 17 is opened. The helium in the refrigeration pipeline 17 exchanges heat through the first air inlet heat exchanger 12 at the bottom of the liquid nitrogen Dewar 4 to reach 77K, then exchanges heat with the second heat sink 31 and reaches 20K, and finally exchanges heat through the second air inlet heat exchanger 13 at the bottom of the liquid helium Dewar 5 to reach 4K, then enters the countercurrent heat exchanger 9 for further cooling and enters the fourth body 6 through the expansion valve 8 for expansion and refrigeration. The refrigerated helium after endothermic expansion is extracted by the vacuum pump 14 until the temperature of the fourth body 6 reaches about 1K.

[0046] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-circuit refrigeration system, characterized in that: The invention comprises a first body having a first cavity, a second body disposed in the first body and having a second cavity, a third body disposed in the second body and having a third cavity, a liquid nitrogen dewar disposed in the second body, and a liquid helium dewar disposed in the third body; The dual-circuit refrigeration system further includes a fourth body disposed in the third body and having a fourth cavity, and an air outlet pipe having one end connected to the fourth body and the other end passing through the third body, the second body and the first body in sequence; The dual-circuit refrigeration system also includes a precooling pipeline and a refrigeration pipeline: The precooling pipeline enters the first main body from the outside and exchanges heat with the liquid nitrogen dewar and the liquid helium dewar in sequence before being connected to the fourth main body; The refrigeration pipeline enters the first body from the outside and exchanges heat with the liquid nitrogen dewar and the liquid helium dewar in sequence, and then communicates with the fourth body after passing through the expansion valve, and the expansion valve is located in the third body; After the refrigeration pipeline exchanges heat with the liquid helium dewar, it first passes through the countercurrent regenerative heat exchanger and then passes through the expansion valve. The countercurrent regenerative heat exchanger is located in the third body and is used for exchanging heat with the outlet pipe. The second body is hoisted in the first body, the top of the second body is a first heat sink connected to the liquid nitrogen Dewar for heat transfer, and the outlet pipe is provided with a first outlet heat exchanger for heat exchange with the first heat sink; The third body is hoisted in the second body, the top of the third body is a second heat sink connected to the liquid helium Dewar for heat transfer, and the outlet pipe is provided with a second outlet heat exchanger for heat exchange with the second heat sink; The second heat sink is also used for exchanging heat for the precooling pipeline and the refrigeration pipeline respectively.

2. The dual-circuit refrigeration system according to claim 1, characterized in that: The liquid nitrogen dewar and the liquid helium dewar are respectively arranged in a circle in the second body and the third body, and the gas outlet pipe extends upward from the central through holes of the liquid nitrogen dewar and the liquid helium dewar.

3. The dual-circuit refrigeration system according to claim 2, characterized in that: The fourth body is located at the bottom of the central through hole of the liquid helium Dewar.

4. The dual-circuit refrigeration system according to claim 1, characterized in that: The bottom of the liquid nitrogen dewar is provided with a first air inlet heat exchanger for respectively exchanging heat for the precooling pipeline and the refrigeration pipeline.

5. The dual-circuit refrigeration system according to claim 1, characterized in that: A second air inlet heat exchanger for respectively exchanging heat for the precooling pipeline and the refrigeration pipeline is provided at the bottom of the liquid helium dewar.

6. The dual-circuit refrigeration system according to claim 1, characterized in that: The dual-circuit refrigeration system further includes an air extraction pump which is arranged outside the first main body and communicated with the air outlet pipe.

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