A large cooling capacity and ultra-low vibration dilution refrigerator

Abstract

The present invention proposes a high-cooling capacity, ultra-low-vibration dilution refrigerator, comprising a dilution refrigeration unit and a Jiao-Tang refrigeration cycle unit. The dilution refrigeration unit includes a dilution refrigeration circuit equipped with a primary pre-cooling heat exchanger and a secondary pre-cooling heat exchanger. The Jiao-Tang refrigeration cycle unit comprises the Jiao-Tang refrigeration circuit, a single-stage refrigerator with a single cold head, and a two-stage refrigerator with a primary cold head and a secondary cold head. The Jiao-Tang refrigeration cycle has two paths: one path is cooled by the cold head of the single-stage refrigerator and then enters the primary pre-cooling heat exchanger; the other path is cooled sequentially by the primary and secondary cold heads of the two-stage refrigerator and then enters the secondary pre-cooling heat exchanger. The energy efficiency ratio (COP) of this invention is twice that of conventional dilution refrigerators, while vibration is reduced. Furthermore, this invention addresses the problem that existing refrigeration technology can only improve the cooling source of dilution refrigerators to 4K, but cannot improve the cooling source to 50K.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration equipment, and in particular to a large-cooling-capacity ultra-low-vibration dilution refrigerator. Background Art

[0002] With the development and application of quantum computing technology, the demand for dilution refrigerators is increasing. Domestic research institutes have the technical capabilities to develop dilution refrigerators and are moving towards industrialization.

[0003] Currently, commercial dilution refrigerators generally use pulse tube refrigerators as cooling sources to account for factors such as vibration. The maximum cooling capacity of a dilution refrigerator using a single pulse tube refrigerator is 400uW@100mK, while a dual pulse tube refrigerator can reach a maximum cooling capacity of 1000uW@100mK, which is the current mainstream technical specification for commercial dilution refrigerators in China. Therefore, the cooling capacity of existing dilution refrigerators is primarily determined by the number of cooling sources (pulse tube refrigerators). Increasing the number of cooling sources can improve the cooling capacity of the dilution refrigerator. However, increasing the number of pulse tube refrigerators will exponentially increase the volume, weight, and electrical power consumption of the dilution refrigerator main unit, and will also lead to the negative effects of vibration caused by the stacking of multiple pulse tube refrigerators. Summary of the Invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a large cooling capacity and ultra-low vibration dilution refrigerator.

[0005] The present invention proposes a large cooling capacity and ultra-low vibration dilution refrigerator, comprising:

[0006] A dilution refrigeration unit includes a dilution refrigeration circuit; the dilution refrigeration circuit is provided with a primary pre-cooling heat exchanger and a secondary pre-cooling heat exchanger located below the primary pre-cooling heat exchanger;

[0007] A coke-soak refrigeration cycle unit, comprising a coke-soak refrigeration cycle, a single-stage refrigerator with a single cold head, and a double-stage refrigerator with a primary cold head and a secondary cold head;

[0008] The coke-tang refrigeration cycle is divided into two routes. One route is cooled by the cold head of the single-stage refrigerator and then enters the first-stage pre-cooling heat exchanger, and exchanges heat with the fluid from the dilution refrigeration circuit in the first-stage pre-cooling heat exchanger before returning to the coke-tang refrigeration cycle to form a branch circulation loop; the other route is cooled by the first-stage cold head and the second-stage cold head of the two-stage refrigerator in turn and then enters the second-stage pre-cooling heat exchanger, and exchanges heat with the fluid from the dilution refrigeration circuit in the second-stage pre-cooling heat exchanger before returning to the coke-tang refrigeration cycle to form a main circulation loop.

[0009] Preferably, the main circulation loop has multiple stages of heat exchangers, and the branch circulation loop is led out from the high-pressure side outlet end of the first heat exchanger in the main circulation loop and merged into the low-pressure side inlet end of the heat exchanger.

[0010] Preferably, the multi-stage heat exchanger includes a first-stage heat exchanger at the first stage, a second-stage heat exchanger located below the first-stage heat exchanger and installed on the first-stage cold head of the two-stage refrigerator, a third-stage heat exchanger located below the second-stage heat exchanger, a fourth-stage heat exchanger located below the third-stage heat exchanger and installed on the second-stage cold head of the two-stage refrigerator, and a last-stage heat exchanger at the last stage; the branch circulation loop is led out from the high-pressure side outlet end of the first-stage heat exchanger and merged into the low-pressure side inlet end of the first-stage heat exchanger.

[0011] Preferably, a regulating valve is provided in the branch circulation loop.

[0012] Preferably, the branch circulation loop comprises a branch heat exchanger mounted on the cold head of the single-stage refrigerator.

[0013] Preferably, the main circulation loop includes a compressor, a throttle valve, and a high-pressure side pipeline that is led out from the outlet of the compressor and connects the high-pressure sides of the first-stage heat exchanger, the third-stage heat exchanger, and the final-stage heat exchanger in series in sequence and flows through the second-stage heat exchanger and the fourth-stage heat exchanger; and a low-pressure side pipeline that connects the low-pressure sides of the final-stage heat exchanger, the third-stage heat exchanger, and the first-stage heat exchanger in series in sequence and is introduced from the compressor inlet; and the end of the high-pressure side pipeline is connected to the low-pressure inlet end of the second-stage pre-cooling heat exchanger through the throttle valve, and the inlet end of the low-pressure side pipeline is connected to the low-pressure outlet end of the second-stage pre-cooling heat exchanger.

[0014] Preferably, the coke-soup refrigeration cycle unit is independently arranged outside the dilution refrigeration unit, and its main circulation loop, branch circulation loop and the first-stage pre-cooling heat exchanger and second-stage pre-cooling heat exchanger in the dilution refrigeration loop are connected through vacuum low-temperature pipes.

[0015] Preferably, the vacuum low-temperature tube has four channels, which include two 50K channels and two 4K channels; one of the 4K channels connects the outlet of the main circulation loop with the low-pressure inlet of the secondary pre-cooling heat exchanger, and the other 4K channel connects the low-pressure outlet of the secondary pre-cooling heat exchanger with the inlet end of the main circulation loop to constitute a circulation between the main circulation loop and the secondary pre-cooling heat exchanger; one of the 50K channels connects the outlet of the branch circulation loop with the low-pressure inlet of the primary pre-cooling heat exchanger, and the other 50K channel connects the low-pressure outlet of the primary pre-cooling heat exchanger with the inlet of the branch circulation loop to constitute a circulation between the branch circulation loop and the primary pre-cooling heat exchanger.

[0016] Preferably, the two-stage refrigerator is a pulse tube refrigerator or a GM refrigerator.

[0017] Preferably, the single-stage refrigerator is a GM refrigerator.

[0018] The present invention uses a Jiao-Tang refrigeration cycle unit as the cold source of the dilution refrigerator, and the Jiao-Tang refrigeration cycle unit in the present invention uses Jiao-Tang refrigeration technology superimposed on refrigerator refrigeration technology to complete the refrigeration cycle, thereby obtaining a large-capacity dilution refrigerator with a cooling capacity twice that of existing conventional dilution refrigerators. At the same time, since the dilution refrigeration unit is separated from the cold source, the dilution refrigeration unit is prevented from being affected by the vibration of the cold source, thereby achieving the purpose of low vibration. In addition, the refrigerator in the present invention includes a single-stage refrigerator and a two-stage refrigerator; the Jiao-Tang refrigeration cycle loop is divided into two routes, one is a branch loop and the other is a main loop. The branch loop is cooled by the cold head of the single-stage refrigerator and then enters the first pre-cooling heat exchanger of the dilution refrigeration loop. The main loop is cooled by the first cold head and the second cold head of the two-stage refrigerator in sequence and then enters the second pre-cooling heat exchanger of the dilution refrigeration loop. By adding a branch circuit and a single-stage refrigerator serving as the branch circuit's cooling source, a 50K cooling source is provided to the dilution refrigerator, thereby increasing the cooling capacity of the dilution refrigerator's 50K cooling source. This addresses the problem of existing refrigeration technology that only increases the dilution refrigerator's cooling source by 4K, but not its 50K cooling source. Furthermore, the increased 50K cooling source provided by the dilution refrigerator significantly shortens the dilution refrigerator's cooldown time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural schematic diagram of a large cooling capacity and ultra-low vibration dilution refrigerator proposed by the present invention. DETAILED DESCRIPTION

[0020] Reference Figure 1 The present invention proposes a large cooling capacity and ultra-low vibration dilution refrigerator, comprising: a dilution refrigeration unit 1 and a coke-soak refrigeration cycle unit 2 providing a cold source for the dilution refrigeration unit 1.

[0021] In this embodiment, the dilution refrigeration unit 1 includes a dilution refrigeration circuit; the dilution refrigeration circuit is provided with a primary pre-cooling heat exchanger 11 and a secondary pre-cooling heat exchanger 12 located below the primary pre-cooling heat exchanger 11. 3 He and 4 After the He mixed gas is pressurized by the compression vacuum pump in the dilution refrigeration circuit at room temperature, it enters the high-pressure side of the first-stage pre-cooling heat exchanger 11 and is heated by the low-pressure side of the coke-soak refrigeration cycle unit 2. 4 He is cooled to 50K and then enters the high-pressure side of the secondary pre-cooling heat exchanger 12 and is cooled by the low-pressure side of the coke-sodium refrigeration cycle. 4 He is cooled to 4 K. At this point, the refrigerant completes the cooling of 4 K and enters the standard refrigeration cycle process of the dilution refrigerator.

[0022] In this embodiment, the coke-soak refrigeration cycle unit 2 includes a coke-soak refrigeration cycle, a single-stage refrigerator 21 with a single cold head, and a double-stage refrigerator 22 with a primary cold head and a secondary cold head.

[0023] Specifically, the two-stage refrigerator 22 can be a GM refrigerator, a pulse tube refrigerator, or another type of refrigerator. In this embodiment, the two-stage refrigerator 22 is a GM refrigerator, with a primary cold head temperature of approximately 50K and a secondary cold head temperature of approximately 10K. The single-stage refrigerator 21 is a GM refrigerator, with a cold head temperature of approximately 50K.

[0024] The coke-soak refrigeration cycle consists of two routes. One route is cooled by the cold head of the single-stage refrigerator 21 and then enters the primary pre-cooling heat exchanger 11. It then exchanges heat with the fluid from the dilution refrigeration circuit in the primary pre-cooling heat exchanger 11 before returning to the coke-soak refrigeration cycle to form a branch circuit 23. The other route is cooled by the primary and secondary cold heads of the two-stage refrigerator 22 and then enters the secondary pre-cooling heat exchanger 12. It then exchanges heat with the fluid from the dilution refrigeration circuit in the secondary pre-cooling heat exchanger 12 before returning to the coke-soak refrigeration cycle to form a main circuit 24.

[0025] In this embodiment, the cooling temperature of the main circulation loop 24 is about 4K. The main circulation loop 24 includes a compressor 241, a throttle valve 242, a primary heat exchanger 243, a secondary heat exchanger 244 located below the primary heat exchanger 243 and installed on the primary cold head of the two-stage refrigerator 22, a tertiary heat exchanger 245 located below the secondary heat exchanger 244, a quaternary heat exchanger 246 located below the tertiary heat exchanger 245 and installed on the secondary cold head of the two-stage refrigerator 22, a final heat exchanger 247 located below the quaternary heat exchanger 246, and a heat exchanger 248 provided by the compressor 241. 1 and sequentially connects the high-pressure sides of the first-stage heat exchanger 243, the third-stage heat exchanger 245, and the final-stage heat exchanger 247 in series, then flows through the high-pressure side pipelines of the second-stage heat exchanger 244 and the fourth-stage heat exchanger 246, and the low-pressure side pipeline that sequentially connects the low-pressure sides of the final-stage heat exchanger 247, the third-stage heat exchanger 245, and the first-stage heat exchanger 243 in series and is introduced by the inlet of the compressor 241. The end of the high-pressure side pipeline is connected to the low-pressure inlet of the second-stage pre-cooling heat exchanger 12 through the throttle valve 242, and the inlet of the low-pressure side pipeline is connected to the low-pressure outlet of the second-stage pre-cooling heat exchanger 12. During operation, the compressor 241 compresses and increases the pressure of the working medium helium and discharges it through the exhaust port. The room-temperature high-pressure helium is pre-cooled through the high-pressure side channel of the first-stage heat exchanger 243 and then enters the second-stage heat exchanger 244 to exchange heat with the first-stage cold head in the two-stage refrigerator 22, reducing the temperature of the working medium helium to approximately 50K. It then enters the third-stage heat exchanger 245 in the next stage, and after heat exchange in the third-stage heat exchanger 245, it enters the fourth-stage heat exchanger 246 to exchange heat with the secondary cold head in the two-stage refrigerator 22, so that the temperature of the working medium helium gas drops to about 10K. It then passes through the high-pressure side channel of the final-stage heat exchanger 247 to be cooled, and is throttled to 4K atmospheric pressure helium gas through the throttle valve 242. The 4K atmospheric pressure helium gas is then transported to the secondary pre-cooling heat exchanger 12 in the dilution refrigeration circuit, and after flowing out from the low-pressure side of the secondary pre-cooling heat exchanger 12, it passes through the final-stage heat exchanger 247, the third-stage heat exchanger 245, and the low-pressure side channel of the first-stage heat exchanger 243 in sequence and returns to the suction port of the compressor 241, forming a closed circulation loop.

[0026] In this embodiment, the cooling temperature of the branch circuit 23 is approximately 50K. The branch circuit 23 is drawn from the high-pressure outlet of the primary heat exchanger 243 and merges into the low-pressure inlet of the primary heat exchanger 243. A regulating valve 231 is provided in the branch circuit 23. During operation, the high-pressure, room-temperature helium gas generated by the compressor 241 in the main circulation circuit 24 is cooled by the primary heat exchanger 243 and then diverted to the branch circuit 23, where it is cooled to 50K by the single-stage refrigerator 21. The 50K helium gas is flow-regulated by the regulating valve 231 and then transported to the low-pressure side of the primary pre-cooling heat exchanger 11 in the dilution refrigeration circuit. After exiting the low-pressure side of the primary pre-cooling heat exchanger 11, the helium returns to the low-pressure inlet of the primary heat exchanger 243, forming a closed circulation loop. The branch circuit 23 includes a branch heat exchanger mounted on the cold head of the single-stage refrigerator 21.

[0027] The refrigeration principle of the present invention is: refrigeration medium 4 He is pressurized to high pressure gas by the compressor 241 in the main circulation loop 24 at room temperature, enters the high pressure side of the first stage heat exchanger 243, is cooled by the reflux helium gas on its low pressure side, and is then divided into two paths. 4 He enters the secondary heat exchanger 244 installed on the first cold head of the double-stage refrigerator 22 and is cooled to 50K. It then enters the high-pressure side of the third-stage heat exchanger 245 and is cooled by the helium reflux from its low-pressure side. It then enters the fourth-stage heat exchanger 246 installed on the second cold head of the double-stage refrigerator 22 and is cooled to 10K. It then enters the high-pressure side of the final-stage heat exchanger 247 and is refluxed from its low-pressure side. 4 After cooling, He is throttled by throttle valve 242 to a 4K low-pressure gas-liquid mixed two-phase state. 4 He; two phase 4 He enters the low-pressure side of the secondary pre-cooling heat exchanger 12 of the dilution refrigeration circuit, absorbs the load heat, and then returns to the low-pressure side inlet of the final heat exchanger 247. It then passes through the final heat exchanger 247, the third heat exchanger 245, and the first heat exchanger 243, where it absorbs the heat on their high-pressure sides and returns to the suction port of the compressor 241 to complete the refrigeration cycle. 4 He enters the branch heat exchanger installed at the cold head of the single-stage refrigerator 21 and is cooled to 50K by the cold head of the single-stage refrigerator 21. It enters the regulating valve 231 for flow regulation and then enters the low-pressure side of the first-stage pre-cooling heat exchanger 11 of the dilution refrigeration circuit. After absorbing the load heat, it returns to the low-pressure side inlet of the first-stage heat exchanger 243 and the low-pressure side of the mainstream. 4 He flows through the low-pressure side of the primary heat exchanger 243 and returns to the suction port of the compressor 241. 4 The He refrigeration cycle provides the cooling sources of 50K and 4K required for the operation of the dilution refrigerator host.

[0028] In this embodiment, the circulation flow of the branch circulation loop 23 can be increased by regulating the valve 231 to increase the cooling capacity of the 50K cold source of the dilution refrigeration unit 1 during the cooling stage, thereby shortening the cooling time.

[0029] Taking the cooling capacity index of 2000uW@100mK as an example, a conventional dilution refrigerator needs to integrate 4 pulse tube refrigerators as cold sources, with an input power of 48KW; to achieve the same index, the input power of the Jiao-Tang refrigeration cycle is 20KW, and the COP of its cold source part is more than twice that of the conventional one.

[0030] In this embodiment, the Jiao-Tang refrigeration cycle unit 2 is independently installed outside the dilution refrigeration unit 1. Its main circulation loop 24 and branch circulation loop 23 are connected to the primary pre-cooling heat exchanger 11 and the secondary pre-cooling heat exchanger 12 of the dilution refrigeration circuit via vacuum cryogenic tubes 3. The present invention utilizes a separate structural design for the Jiao-Tang refrigeration cycle unit 2 and the dilution refrigeration unit 1, separating the dilution refrigerator's cold source from the main unit. The vacuum cryogenic tubes 3 connect the two, effectively isolating the cold source from vibrations generated during operation.

[0031] Specifically: the vacuum low-temperature tube 3 has four channels, including two 50K channels and two 4K channels; one of the 4K channels connects the outlet of the main circulation loop 24 and the low-pressure inlet of the secondary pre-cooling heat exchanger 12, and the other 4K channel connects the low-pressure outlet of the secondary pre-cooling heat exchanger 12 and the inlet of the main circulation loop 24 to form a circulation between the main circulation loop 24 and the secondary pre-cooling heat exchanger 12; one of the 50K channels connects the outlet of the branch circulation loop 23 and the low-pressure inlet of the primary pre-cooling heat exchanger 11, and the other 50K channel connects the low-pressure outlet of the primary pre-cooling heat exchanger 11 and the inlet of the branch circulation loop 23 to form a circulation between the branch circulation loop 23 and the primary pre-cooling heat exchanger 11.

[0032] As can be seen from the above, the present invention utilizes a Jiao-Tang refrigeration cycle unit 2 as the cold source for the dilution refrigerator. The Jiao-Tang refrigeration cycle unit 2 utilizes Jiao-Tang refrigeration technology combined with chiller refrigeration technology to complete the refrigeration cycle, resulting in a high-capacity dilution refrigerator with a cooling capacity twice that of conventional dilution refrigerators and a COP twice as high. Furthermore, since the dilution refrigerator unit 1 is separated from the cold source, it is protected from the effects of cold source vibration, achieving low vibration. Furthermore, the refrigerator of the present invention includes a single-stage refrigerator 21 and a two-stage refrigerator 22. The Jiao-Tang refrigeration cycle has two paths: a branch loop 23 and a main loop 24. The branch loop 23 is cooled by the cold head of the single-stage refrigerator 21 before entering the primary pre-cooling heat exchanger 11 of the dilution refrigerator circuit. The main loop 24 is cooled sequentially by the primary and secondary cold heads of the two-stage refrigerator 22 before entering the secondary pre-cooling heat exchanger 12 of the dilution refrigerator circuit. By adding a branch circuit 23 and a single-stage refrigerator 21 serving as a cooling source for this branch circuit 23, a 50K cooling source is provided for the dilution refrigerator, thereby increasing the cooling capacity of the 50K cooling source. This addresses the problem of existing refrigeration technology that only increases the 4K cooling source of the dilution refrigerator, but not the 50K cooling source. Furthermore, the increased 50K cooling source provided by the dilution refrigerator significantly shortens the dilution refrigerator's cool-down time.

[0033] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A large cooling capacity ultra-low vibration dilution refrigerator, characterized in that: include: A dilution refrigeration unit (1) includes a dilution refrigeration circuit, wherein the dilution refrigeration circuit is provided with a primary precooling heat exchanger (11) and a secondary precooling heat exchanger (12) located below the primary precooling heat exchanger (11); A coke-soak refrigeration cycle unit (2), comprising a coke-soak refrigeration cycle, a single-stage refrigerator (21) having a single cold head, and a double-stage refrigerator (22) having a primary cold head and a secondary cold head; The coke-soak refrigeration cycle is divided into two paths, one of which is cooled by the cold head of the single-stage refrigerator (21) and then enters the first-stage pre-cooling heat exchanger (11), and exchanges heat with the fluid from the dilution refrigeration circuit in the first-stage pre-cooling heat exchanger (11) before returning to the coke-soak refrigeration cycle to form a branch circulation loop (23); the other path is cooled by the first-stage cold head and the second-stage cold head of the two-stage refrigerator (22) in sequence and then enters the second-stage pre-cooling heat exchanger (12), and exchanges heat with the fluid from the dilution refrigeration circuit in the second-stage pre-cooling heat exchanger (12) before returning to the coke-soak refrigeration cycle to form a main circulation loop (24); The main circulation loop (24) has a multi-stage heat exchanger, and the branch circulation loop (23) is drawn out from the high-pressure side outlet end of the first heat exchanger in the main circulation loop (24) and merged into the low-pressure side inlet end of the heat exchanger; The multi-stage heat exchanger includes a first-stage heat exchanger (243) at the top, a second-stage heat exchanger (244) located below the first-stage heat exchanger (243) and installed on the first-stage cold head of the two-stage refrigerator (22), a third-stage heat exchanger (245) located below the second-stage heat exchanger (244), a fourth-stage heat exchanger (246) located below the third-stage heat exchanger (245) and installed on the second-stage cold head of the two-stage refrigerator (22), and a final-stage heat exchanger (247) at the final stage; the branch circulation loop (23) is led out from the high-pressure side outlet end of the first-stage heat exchanger (243) and merged into the low-pressure side inlet end of the first-stage heat exchanger (243); The main circulation loop (24) includes a compressor (241), a throttle valve (242), and a high-pressure side pipeline that is led out from the outlet of the compressor (241) and sequentially connects the high-pressure sides of the first-stage heat exchanger (243), the third-stage heat exchanger (245), and the final-stage heat exchanger (247) in series and flows through the second-stage heat exchanger (244) and the fourth-stage heat exchanger (246); and a low-pressure side pipeline that sequentially connects the low-pressure sides of the final-stage heat exchanger (247), the third-stage heat exchanger (245), and the first-stage heat exchanger (243) in series and is introduced from the inlet of the compressor (241); and the end of the high-pressure side pipeline is connected to the low-pressure inlet end of the second-stage precooling heat exchanger (12) through the throttle valve (242), and the inlet end of the low-pressure side pipeline is connected to the low-pressure outlet end of the second-stage precooling heat exchanger (12).

2. The large cooling capacity and ultra-low vibration dilution refrigerator according to claim 1, characterized in that: A regulating valve (231) is provided in the branch circulation loop (23).

3. According to the large cooling capacity and ultra-low vibration dilution refrigerator of claim 1, the branch circulation loop (23) comprises a branch heat exchanger installed on the cold head of the single-stage refrigerator (21).

4. A large cooling capacity ultra-low vibration dilution refrigerator according to any one of claims 1 to 3, characterized in that: The coke-soup refrigeration cycle unit (2) is independently arranged outside the dilution refrigeration unit (1), and is connected to its main circulation loop (24), branch circulation loop (23) and the first-stage pre-cooling heat exchanger (11) and the second-stage pre-cooling heat exchanger (12) in the dilution refrigeration loop through a vacuum low-temperature tube (3).

5. The large cooling capacity and ultra-low vibration dilution refrigerator according to claim 4, characterized in that: The vacuum low-temperature tube (3) has four channels, which include two 50K channels and two 4K channels; one of the 4K channels connects the outlet of the main circulation loop (24) and the low-pressure inlet of the secondary precooling heat exchanger (12), and the other 4K channel connects the low-pressure outlet of the secondary precooling heat exchanger (12) and the inlet of the main circulation loop (24) to form a circulation between the main circulation loop (24) and the secondary precooling heat exchanger (12); one of the 50K channels connects the outlet of the branch circulation loop (23) and the low-pressure inlet of the primary precooling heat exchanger (11), and the other 50K channel connects the low-pressure outlet of the primary precooling heat exchanger (11) and the inlet of the branch circulation loop (23) to form a circulation between the branch circulation loop (23) and the primary precooling heat exchanger (11).

6. The large cooling capacity and ultra-low vibration dilution refrigerator according to claim 1, characterized in that: The two-stage refrigerator (22) is a pulse tube refrigerator or a GM refrigerator.

7. The large cooling capacity and ultra-low vibration dilution refrigerator according to claim 1, characterized in that: The single-stage refrigerator (21) is a GM refrigerator.

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