A Dilution Refrigerator with Ultra-Large Refrigeration Capacity

Abstract

The present invention relates to a super-large cooling capacity dilution refrigerator, comprising a superfluid helium refrigeration module and a dilution refrigeration module. The super-large cooling capacity dilution refrigerator adopts a large superfluid helium refrigerator as a pre-cooling unit, which overcomes the shortcomings of the traditional pre-cooling method such as limited pre-cooling capacity and inconvenient operation, greatly improves the pre-cooling capacity, and thus makes the super-large cooling capacity dilution refrigerator possible; the dilution refrigeration module comprises a 5K 3 He low temperature circulation pump, distiller, heat exchanger group and mixing chamber, this ultra-large cooling capacity dilution refrigerator adopts 5K 3 He low temperature circulation pump replaces the traditional room temperature circulation pump, 5K 3 He cryogenic circulation pump has a compact structure and low vibration, which reduces the heat loss caused by vibration, and 5K 3 The He low-temperature circulating pump is set in the vacuum chamber, which avoids heat loss along the circulating pump pipeline from room temperature to the low-temperature vacuum chamber, reduces heat leakage, and greatly saves 3 The use of He is beneficial to the current extremely scarce 3 Development and application of large-capacity dilution refrigerator products under the current situation of He.

Description

Technical Field

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

[0002] Among the many technical routes to realize quantum computing, superconducting quantum computing is considered to be the most likely to achieve major breakthroughs first. Experiments in superconducting quantum computing must be carried out at ultra-low temperatures (<20mK). Dilution refrigerators are key devices that provide cooling for quantum computing. Quantum computing chips need to be placed in the mixing chamber of a dilution refrigerator for cooling. As the number of quantum bits in quantum computing continues to increase, there is an increasing demand for the cooling capacity of dilution refrigerators. The maximum cooling capacity that the current mainstream dilution refrigerators can provide at a temperature of 100mK is only a few hundred microwatts (10 -4 W), can only meet the heat dissipation needs within a hundred qubits, far from meeting the future quantum computing needs of 1,000 qubits or even more than a million qubits. With the continuous expansion of quantum computing equipment, the current small dilution refrigerators on the market can no longer meet the demand.

[0003] my country's research on watt-level ultra-large cooling capacity dilution refrigeration technology is still blank. On the one hand, it is restricted by the breakthrough of key technologies of dilution refrigerators. On the other hand, the current dilution refrigeration technology has certain technical bottlenecks in increasing cooling capacity, and it is necessary to develop innovative technical routes. The final cooling capacity and minimum cooling temperature of the dilution refrigerator depend on 3 He circulation flow and heat exchanger outlet temperature. The temperature of the mixing chamber is calculated as follows:

[0004] T MC / T L = 1 / 2.8 (1)

[0005]

[0006] In the above formula, T MC represents the temperature of the mixing chamber, T L express 3 The temperature at which He leaves the last heat exchanger, Heat leakage to the outside, for 3 The molar circulation rate of He.

[0007] From formulas (1) and (2), it can be seen that the temperature of the mixer T MC The level depends on two factors: and T L To obtain good dilution refrigerator performance, external heat leakage must be reduced as much as possible. LAs low as possible, a high-performance heat exchanger is essential. In order to obtain the maximum cooling capacity of the mixing chamber, it is necessary to increase the heat exchange area and adjust 3 He cycle working fluid flow rate. Generally speaking, increasing the flow rate will increase the cooling capacity, but the bigger the better is not necessarily true. There is an optimal flow rate cooling capacity point.

[0008] The cooling capacity of the dilution refrigerator precooling stage determines the total cooling capacity that the dilution refrigerator mixing chamber can generate. 3 He circulating fluid flow rate is 3 Under the premise of finding the best balance between the capacity of the He working medium circulation pump and the resulting vibration heat leakage, the design of the front cooling stage makes 3 The He cycle working fluid carries as much cold capacity as possible in advance, which becomes the decisive factor in determining the cooling capacity of the mixing chamber of the dilution refrigerator.

[0009] However, the traditional wet dilution refrigerator (including liquid helium pre-cooling) uses liquid helium Dewar pre-cooling. In the early closed dilution refrigerator, the circulating 3 He gas is condensed through a 1K condensation pool provided by superfluid helium. The dilution refrigerator operates in a liquid helium devariable and uses liquid helium for pre-cooling, which is inconvenient to operate and has high costs. Traditional small dry dilution refrigerators generally use GM refrigerators or pulse tube refrigerators for pre-cooling. Their cooling capacity at a temperature of 4.2K is only 1.5 to 2W, the compressor power is generally 6 to 10kW, and the specific power consumption is as high as 3000 to 6667W / W. In other words, the pre-cooling methods of traditional dilution refrigerators cannot meet the demand for more cooling capacity, and the specific power consumption is large. In addition, traditional dilution refrigerators use room temperature circulating pumps to 3 He is extracted from the distiller and circulated in the system. The exhaust pipe of the room temperature circulation pump spans the temperature range of 0.6 to 300K, and the heat loss along the way is very large. The room temperature circulation pump vibrates greatly, and the heat loss caused by vibration is large. In order to obtain the maximum cooling capacity, it is necessary to increase 3 The flow rate of the He working medium circulating pump, but the increase in flow rate increases the vibration heat leakage and increases the heat loss along the exhaust pipeline. Summary of the invention

[0010] An object of the present invention is to provide an ultra-large cooling capacity dilution refrigerator, which adopts a large superfluid helium refrigerator as a front pre-cooling unit and adopts a low-temperature circulation pump instead of a traditional room temperature circulation pump, so as to obtain an ultra-large cooling capacity, overcome the defects of the traditional pre-cooling method, such as limited pre-cooling capacity, inconvenient operation and large heat loss caused by the use of a traditional room temperature circulation pump.

[0011] The present invention provides a large cooling capacity dilution refrigerator, comprising:

[0012] Dilution refrigeration module, which is used to dilute3 The He concentrated solution realizes refrigeration and provides cold capacity to the outside. The dilution refrigeration module is arranged in the vacuum chamber, including a mixing chamber, a heat exchanger group connected to the mixing chamber, a distiller connected to the heat exchanger group, and a low-temperature circulation pump connected to the distiller; and

[0013] A superfluid helium refrigeration module, which is a large superfluid helium refrigerator, used to provide pre-cooling for the dilution refrigeration module, and has a 4.5K temperature zone and a 1.2K temperature zone;

[0014] The low temperature circulating pump of the dilution refrigeration module 3 After the He gas is precooled to 4.5K in the 4.5K temperature zone of the superfluid helium refrigeration module, it enters the 1.2K temperature zone and is precooled to 1.2K. 3 He liquid, 3 After the He liquid enters the distiller and is cooled to 0.6K, it enters the heat exchanger group for heat exchange, and finally enters the mixing chamber for dilution refrigeration. 3 He flows through the heat exchanger group in countercurrent flow according to the osmotic pressure difference and then enters the distiller. 3 He enters the low-temperature circulation pump by relying on the suction force of the low-temperature circulation pump, thus completing a refrigeration cycle of the ultra-large cooling capacity dilution refrigerator.

[0015] In one embodiment of the present invention, the superfluid helium refrigeration module includes a 4.5K liquid pool, a 1.2K liquid pool, a heat exchanger group, a cold compressor group and a throttle valve group, all of which are arranged in the vacuum chamber, the 4.5K liquid pool is used to provide the 4.5K temperature zone, the 1.2K liquid pool is used to provide the 1.2K temperature zone, the heat exchanger group includes a first heat exchanger, a second heat exchanger, a third heat exchanger and a fourth heat exchanger, and the throttle valve group includes a first throttle valve and a second throttle valve;

[0016] The low temperature circulation pump of the dilution refrigeration module is 5K 3 He low temperature circulation pump;

[0017] The high-pressure helium is divided into two parts after passing through the first heat exchanger and the second heat exchanger in sequence for heat exchange, one part directly enters the 4.5K liquid pool, and the other part enters the 4.5K liquid pool after being throttled into gas-liquid two-phases by the first throttle valve; the saturated steam in the 4.5K liquid pool is returned to low pressure, and the liquid helium flowing out of the bottom of the 4.5K liquid pool is throttled into gas-liquid two-phases by the second throttle valve after heat exchange and cooling by the third heat exchanger, and the gas-liquid two-phase enters the 1.2K liquid pool for liquid accumulation, and when the liquid level in the 1.2K liquid pool reaches a preset value, the cold compressor unit is started to reduce the pressure and cool the 1.2K liquid pool, and the temperature of the 1.2K liquid pool is controlled at 1.2K, and the pressure is controlled to be negative pressure; the return gas of the 1.2K liquid pool countercurrently passes through the third heat exchanger, the cold compressor unit and the first heat exchanger, and then returns to the compressor station, thereby completing a refrigeration cycle of the superfluid helium refrigeration module;

[0018] The 5K 3 He low temperature circulation pump output 3 After the He gas enters the 4.5K liquid pool and is precooled to 4.5K, it enters the fourth heat exchanger for heat exchange and then enters the 1.2K liquid pool and is precooled to 1.2K. 3 He liquid, 3 He liquid enters the distiller and is cooled to 0.6K, and then further cooled by the heat exchanger group before flowing into the mixing chamber. 3 Follow 3 The He-concentrated phase migrates to 3 He in the scarce phase, generates cooling capacity, and the dilute phase in the mixing chamber 3 He enters the heat exchanger group in reverse flow according to the osmotic pressure difference and then enters the distiller. After evaporation in the distiller, He enters the distiller according to the 5K 3 The suction of the He low temperature circulation pump flows countercurrently through the fourth heat exchanger and enters the 5K 3 He low temperature circulation pump, thus completing a refrigeration cycle of the dilution refrigeration module.

[0019] In one embodiment of the present invention, the dilution refrigeration module further includes a 3 He cryogenic circulation pump and the limiting valve of the distiller, which is precooled to 1.2K 3 The He liquid enters the distiller after being limited by the limiting valve.

[0020] In one embodiment of the present invention, the superfluid helium refrigeration module further includes a first pipeline for connecting the first heat exchanger, the second heat exchanger and the 4.5K liquid pool, a second pipeline for connecting the 4.5K liquid pool, the third heat exchanger, the second throttle valve and the 1.2K liquid pool, a third pipeline for connecting the 4.5K liquid pool, the second heat exchanger and the first heat exchanger, and a fourth pipeline for connecting the 1.2K liquid pool, the third heat exchanger, the cold compressor unit and the first heat exchanger, wherein:

[0021] The high-pressure helium gas enters the first heat exchanger and the second heat exchanger in sequence through the first pipeline, a part of the high-pressure helium gas directly enters the 4.5K liquid pool through the first pipeline, and the other part of the high-pressure helium gas enters the 4.5K liquid pool after being throttled by the first throttle valve;

[0022] The liquid helium flowing out from the bottom of the 4.5K liquid pool enters the third heat exchanger through the second pipeline for heat exchange, is throttled into gas-liquid two-phases through the second throttle valve, and then enters the 1.2K liquid pool;

[0023] The saturated steam in the 4.5K liquid pool passes through the third pipeline in countercurrent through the second heat exchanger and the first heat exchanger and then returns to low pressure;

[0024] The gas phase in the 1.2K liquid pool flows countercurrently through the fourth pipeline into the third heat exchanger, the cold compressor unit and the first heat exchanger, and then returns to the compressor station.

[0025] In one embodiment of the present invention, the dilution cooling module further includes a device for connecting the 5K 3 He low temperature circulation pump, the 4.5K liquid pool, the fourth heat exchanger, the 1.2K liquid pool, the limiting valve, the distiller, the heat exchanger group and the fifth pipeline of the mixing chamber, a sixth pipeline for connecting the mixing chamber, the heat exchanger group and the distiller; and a sixth pipeline for connecting the distiller, the fourth heat exchanger and the 5K 3 The seventh pipeline of the He cryogenic circulation pump, wherein

[0026] The 5K 3 He cryogenic circulation pump 3 After He gas enters the 4.5K liquid pool, the fourth heat exchanger and the 1.2K liquid pool in sequence through the fifth pipeline and is precooled to 1.2K, 3 He liquid, 3 After the He liquid is limited by the limiting valve, it enters the distiller and the heat exchanger group in sequence, and finally enters the mixing chamber;

[0027] The dilute phase in the mixing chamber3 He relies on the osmotic pressure difference to enter the distiller through the sixth pipeline in countercurrent through the heat exchanger group;

[0028] The evaporated 3 He gas relies on the 5K 3 The suction force of the He low temperature circulation pump is sucked into the 5K 3 And low temperature circulation pump.

[0029] In one embodiment of the present invention, the heat exchanger group includes a continuous heat exchanger and a stepped heat exchanger, wherein the cooling to 0.6K 3 The He liquid flows into the mixing chamber after passing through the continuous heat exchanger and the stepped heat exchanger in sequence.

[0030] In one embodiment of the present invention, there are a plurality of mixing chambers, the plurality of mixing chambers are connected in parallel, and each of the mixing chambers corresponds to at least one sample rack.

[0031] In one embodiment of the present invention, the distiller is originally filled with liquid 4 He.

[0032] In one embodiment of the present invention, the cold compressor unit includes a first cold compressor, a second cold compressor, a third cold compressor, a fourth cold compressor, a fifth cold compressor and a sixth cold compressor which are connected in series in sequence along the return air direction of the 1.2K liquid pool.

[0033] In one embodiment of the present invention, the 4.5K liquid pool and the 1.2K liquid pool are both 4 Heating liquid pool.

[0034] The ultra-large cooling capacity dilution refrigerator provided by the present invention adopts a large superfluid helium refrigerator as a front pre-cooling unit, which can provide an ultra-large pre-cooling capacity, overcomes the shortcomings of the traditional dry dilution refrigerator adopting a GM refrigerator / pulse tube refrigerator as a front pre-cooling unit, which has a limited pre-cooling capacity, and the traditional wet dilution refrigerator needs to be immersed in a liquid helium dewar for pre-cooling, which is inconvenient to operate, etc., greatly improves the pre-cooling capacity, thereby making the ultra-large cooling capacity dilution refrigerator possible.

[0035] The ultra-large cooling capacity dilution refrigerator provided by the present invention adopts a low-temperature circulating pump to replace the traditional room temperature circulating pump, 5K 3 Compared with the traditional room temperature circulating pump, the He low temperature circulating pump has a compact structure and small vibration, which reduces the heat loss caused by vibration. 3 The He low-temperature circulating pump is set in the vacuum chamber, which avoids the heat loss of the traditional room-temperature circulating pump pipeline from room temperature to the low-temperature vacuum chamber, reduces heat leakage, and greatly saves 3The use of He is to benefit the currently extremely scarce 3 Development and application of large-capacity dilution refrigerator products under the current situation of He.

[0036] The ultra-large cooling capacity dilution refrigerator provided by the present invention can generate a cooling capacity of more than 100mW@100mK (even reaching a cooling capacity of 1W@100mK), which can meet the needs of more than 1000 high-performance superconducting quantum bits, and can meet the current demand for ultra-large cooling capacity dilution refrigerators.

[0037] The ultra-large cooling capacity dilution refrigerator provided by the present invention adopts a parallel structure of multiple mixing chambers, each mixing chamber corresponds to at least one sample rack, the multiple sample racks are independent of each other, the GPU chips (quantum computing chips) placed on the sample racks do not interfere with each other, and the leads of different GPUs do not interfere with each other, so that the ultra-large cooling capacity dilution refrigerator can be applied to distributed quantum computer clusters.

[0038] Further objects and advantages of the present invention will be fully apparent from an understanding of the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the ultra-large cooling capacity dilution refrigerator according to the first embodiment of the present invention.

[0040] Figure 2 It is a structural schematic diagram of the ultra-large cooling capacity dilution refrigerator according to the second embodiment of the present invention.

[0041] The direction of the arrow in the figure represents the direction of fluid flow.

[0042] Description of Figure Numbers:

[0043] Superfluid helium refrigeration module 100; 4.5K liquid pool 10; 1.2K liquid pool 20; first heat exchanger 11; second heat exchanger 12; third heat exchanger 13; fourth heat exchanger 14; first throttle valve 21; second throttle valve 22; first cold compressor 31; second cold compressor 32; third cold compressor 33; fourth cold compressor 34; fifth cold compressor 35; sixth cold compressor 36; first pipeline 41; second pipeline 42; third pipeline 43; fourth pipeline 44;

[0044] Dilution refrigeration module 200 ; mixing chamber 201 ; heat exchanger group 202 ; distiller 203 ; low-temperature circulation pump 204 ; fifth pipeline 205 ; sixth pipeline 206 ; seventh pipeline 207 ; flow limiting valve 208 . DETAILED DESCRIPTION

[0045] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The embodiments described below are for example only, and those skilled in the art may think of other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0046] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "vertical", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0047] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, 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 present invention can be understood according to specific circumstances.

[0049] The present invention provides a dilution refrigerator with a large cooling capacity. The dilution refrigerator with a large cooling capacity includes a large superfluid helium refrigerator pre-cooling unit, a 5K 3 He low temperature circulation pump, distiller, high-efficiency helium 3 / helium 4 heat exchanger and multiple mixing chambers. This ultra-large cooling capacity dilution refrigerator uses a large superfluid helium refrigerator as the pre-cooling unit, overcoming the shortcomings of the traditional dry dilution refrigerator using GM refrigerator / pulse tube refrigerator as the pre-cooling unit, the limited pre-cooling capacity, the traditional wet dilution refrigerator needs to be immersed in liquid helium dewar for pre-cooling, and the inconvenience of operation. It greatly improves the pre-cooling capacity, making the ultra-large cooling capacity dilution refrigerator possible. Using 5K 3 He low temperature circulation pump replaces the traditional room temperature circulation pump, 5K 3Compared with the traditional room temperature circulating pump, the He low temperature circulating pump has a compact structure and small vibration, which reduces the heat loss caused by vibration. 3 The He low-temperature circulating pump is set in the vacuum chamber, which avoids the heat loss of the traditional room-temperature circulating pump pipeline from room temperature to the low-temperature vacuum chamber, reduces heat leakage, and greatly saves 3 The use of He is to benefit the currently extremely scarce 3 The development and application of large-capacity dilution refrigerator products under the current situation of He. This ultra-large-capacity dilution refrigerator can generate a cooling capacity of more than 100mW@100mK (even reaching 1W@100mK), which can meet the needs of more than 1,000 high-performance superconducting quantum bits and can be applied to distributed quantum computer clusters.

[0050] like Figure 1 As shown, the specific structure of the ultra-large cooling capacity dilution refrigerator according to the first embodiment of the present invention is specifically explained.

[0051] Specifically, the ultra-large cooling capacity dilution refrigerator includes a superfluid helium refrigeration module 100 and a dilution refrigeration module 200. The superfluid helium refrigeration module 100 is a pre-cooling module of the ultra-large cooling capacity dilution refrigerator, which is used to provide pre-cooling cold capacity for the dilution refrigeration module 200, and specifically adopts a large superfluid helium refrigerator; the dilution refrigeration module 200 is an extremely low temperature module, which is used to provide cold capacity to the outside.

[0052] The superfluid helium refrigeration module 100 is used as a pre-cooling unit of the dilution refrigeration module 200 to produce 4.5K liquid helium, fill the 4.5K liquid pool 10 with liquid, and maintain the temperature of 4.5K. The superfluid helium refrigeration module 100 also produces 1.2K superfluid helium, fills the 1.2K liquid pool 20 with superfluid helium, and uses a set of cold compressor units to reduce pressure and maintain the temperature and pressure of the 1.2K liquid pool 20.

[0053] Specifically, the superfluid helium refrigeration module 100 specifically adopts a large 4 The He superfluid helium refrigerator comprises a 4.5K liquid pool 10, a 1.2K liquid pool 20, a heat exchanger group, a cold compressor group and a throttle valve group, all of which are arranged in a vacuum chamber. The superfluid helium refrigeration module 100 comprises a 4.5K temperature zone and a 1.2K superfluid helium temperature zone, which respectively produce 4.5K liquid helium and 1.2K superfluid helium, which are used in the present invention to inject liquid into the 4.5K liquid helium pool and inject liquid into the 1.2K superfluid helium liquid pool at the same time. The 4.5K liquid pool 10 and the 1.2K liquid pool 20 are both 4 Heating liquid pool.

[0054] More specifically, the heat exchanger group of the superfluid helium refrigeration module 100 includes a first heat exchanger 11, a second heat exchanger 12, a third heat exchanger 13 and a fourth heat exchanger 14; the first heat exchanger 11 is a 20K heat exchanger, the second heat exchanger 12 is a 5K heat exchanger, and the third heat exchanger 13 is a 4K heat exchanger; the throttle valve group includes a first throttle valve 21 and a second throttle valve 22; the cold compressor group includes a first cold compressor 31, a second cold compressor 32, a third cold compressor 33, a fourth cold compressor 34, a fifth cold compressor 35 and a sixth cold compressor 36 which are connected in series in sequence along the return direction of the 1.2K liquid pool 20.

[0055] Furthermore, the superfluid helium refrigeration module 100 also includes a first pipeline 41 for connecting the first heat exchanger 11, the second heat exchanger 12 and the 4.5K liquid pool 10, a second pipeline 42 for connecting the 4.5K liquid pool 10, the third heat exchanger 13, the second throttle valve 22 and the 1.2K liquid pool 20, a third pipeline 43 for connecting the 4.5K liquid pool 10, the second heat exchanger 12 and the first heat exchanger 11, and a fourth pipeline 44 for connecting the 1.2K liquid pool 20, the third heat exchanger 13, the cold compressor unit and the first heat exchanger 11.

[0056] Specifically, the first pipeline 41 is connected to the high-pressure helium inlet of the first heat exchanger 11, the helium inlet of the second heat exchanger 12 and the helium inlet of the 4.5K liquid pool 10, and is used to introduce high-pressure helium to form a main gas path for high-pressure helium.

[0057] Specifically, the second pipeline 42 is connected to the liquid helium outlet at the bottom of the 4.5K liquid pool 10, the liquid helium inlet of the third heat exchanger 13, the inlet and outlet of the second throttle valve 22 and the inlet of the 1.2K liquid pool 20, forming a flow pipeline for liquid helium.

[0058] Specifically, the third pipeline 43 is connected to the gas outlet of the 4.5K liquid pool 10 , the second heat exchanger 12 , and the first heat exchanger 11 , forming a low-pressure gas return path of the 4.5K liquid pool 10 .

[0059] Specifically, the fourth pipeline 44 is connected to the gas outlet of the 1.2K liquid pool 20, the third heat exchanger 13, the cold compression unit, and the first heat exchanger 11, forming a negative pressure return gas circuit of the 1.2K liquid pool 20. The first heat exchanger 11 and the third heat exchanger 13 are negative pressure heat exchangers.

[0060] Furthermore, the dilution refrigeration module 200 includes a mixing chamber 201, a heat exchanger group 202 connected to the mixing chamber 201, a distiller 203 connected to the heat exchanger group 202, and a low-temperature circulation pump 204 connected to the distiller 203 and arranged in a vacuum chamber. The mixing chamber 201 is a device that produces a dilution refrigeration effect and outputs cold to the outside. The heat exchanger group 202 is a high-efficiency helium 3 / helium 4 heat exchanger group 202, and the heat exchanger group 202 includes a continuous heat exchanger and a stepped heat exchanger. The outlet temperature of the continuous heat exchanger is lower than 100mK, and a common spirally arranged coaxial heat exchange tube structure can be used; the stepped heat exchanger is used to obtain a lower temperature, and a commonly used disc-shaped heat exchange structure composed of a large surface area sintered body can be used. The present invention does not limit the specific structure of the continuous heat exchanger and the stepped heat exchanger. The distiller 203 is originally filled with 4 He liquid, used to 3 The He solution is further cooled to 0.6K due to 3 Diffusion of He molecules, the actual 3 He / 4 The concentration of He solution depends on the temperature of the solution. The lower the temperature, the 3 The greater the concentration of He.

[0061] The mixing chamber 201, the heat exchanger group 202, the distiller 203, and the low-temperature circulation pump 204 are all installed in a vacuum chamber. Figure 1 The arrows in the 3 In particular, the low temperature circulation pump 204 is 5K 3 He low temperature circulation pump 204.

[0062] It is worth mentioning that the dilution cooling module 200 also includes a 3 He low temperature circulation pump 204 and the flow limiting valve 208 of the distiller 203, the flow limiting valve 208 is used to act as a flow limiter to control the precooling to 1.2K 3 He liquid flow rate and maintain the required condensing pressure.

[0063] like Figure 1 As shown, the 4.5K liquid pool 10, the fourth heat exchanger 14 and the 1.2K liquid pool 20 of the superfluid helium refrigeration module 100 are used to heat the 5K 3 He low temperature circulation pump 204 output 3 He was precooled step by step, and finally 1.2K was obtained. 3 And liquid.

[0064] Furthermore, the dilution cooling module 200 also includes a device for connecting the 5K3 He low temperature circulation pump 204, the 4.5K liquid pool 10, the fourth heat exchanger 14, the 1.2K liquid pool 20, the limiting valve 208, the distiller 203, the heat exchanger group 202 and the fifth pipeline 205 of the mixing chamber 201, the sixth pipeline 206 for connecting the mixing chamber 201, the heat exchanger group 202 and the distiller 203; and the sixth pipeline 206 for connecting the distiller 203, the fourth heat exchanger 14 and the 5K 3 The seventh pipeline 207 of the He low temperature circulation pump 204.

[0065] Specifically, the fifth pipeline 205 is connected to the 5K 3 The gas outlet of the He low temperature circulation pump 204 passes through the 4.5K liquid pool 10, the fourth heat exchanger 14 and the 1.2K liquid pool 20 in sequence, and is connected to the inlet and outlet of the flow limiting valve 208, and is connected to the inlet of the mixing chamber 201 after passing through the distiller 203 and the heat exchanger group 202 in sequence, so as to provide the mixing chamber 201 with a very low temperature gas. 3 And liquid.

[0066] Specifically, the sixth pipeline 206 is connected to the mixing chamber 201. 3 The He dilute phase outlet, the inlet and outlet of the heat exchanger group 202 and the inlet of the distiller 203 constitute 3 He recovery line.

[0067] Specifically, the seventh pipeline 207 is connected to the gas outlet of the distiller 203, passes through the fourth heat exchanger 14 and is connected to the 5K 3 The gas inlet of He low temperature circulation pump 204 is composed of 3 He gas recovery pipeline.

[0068] It is worth mentioning that Figure 1 The partial structure of the superfluid helium refrigeration module 100 is shown. The superfluid helium refrigeration module 100 also includes a compressor station and a turbine expansion unit and a refrigerator heat exchanger unit which are not shown in the figure.

[0069] The working process of the ultra-large cooling capacity dilution refrigerator is described below.

[0070] The working process of the superfluid helium refrigeration module 100 is as follows:

[0071] (1) Figure 1As shown, after the high-pressure helium gas sent from the first pipeline 41 passes through the first heat exchanger 11 and the second heat exchanger 12 and exchanges heat with the reflux cold helium gas, a part of it directly enters the 4.5K liquid pool 10, and another part is separated and throttled into gas-liquid two-phase through the first throttle valve 21. The gas-liquid two-phase enters the 4.5K liquid pool 10 and accumulates liquid, and the saturated helium vapor returns to low pressure through the third pipeline 43. The liquid helium flowing out of the bottom of the 4.5K liquid pool 10 is further cooled through the third heat exchanger 13 through the second pipeline 42, and then throttled into gas-liquid two-phase through the second throttle valve 22, and the gas-liquid two-phase enters the 1.2K liquid pool 20. The gas phase in the 1.2K liquid pool 20 is returned through the fourth pipeline 44, countercurrently enters the third heat exchanger 13, then passes through the cold compressor unit, countercurrently passes through the first heat exchanger 11, and finally returns to the compressor station.

[0072] It is worth mentioning that according to the specific design of the superfluid helium refrigerator, if a negative pressure room temperature pump design is adopted, the air will be returned to the low pressure of the compressor; if a negative pressure compressor design is adopted, the air will be returned to the medium pressure of the compressor.

[0073] (2) When the liquid level in the 1.2K liquid pool 20 reaches a certain value, the cold compressor unit (in this embodiment, composed of 6 cold compressors) starts to reduce the pressure and temperature of the 1.2K liquid pool 20, and the temperature in the 1.2K liquid pool 20 is controlled at 1.2K, and the pressure is controlled to be negative pressure. The return gas in the 1.2K liquid pool 20 flows through the third heat exchanger 13 through the fourth pipeline 44 in reverse flow and enters the cold compressor unit, and then flows through the first heat exchanger 11 in reverse flow and returns to the compressor station, completing a cycle.

[0074] It can be understood that the ultra-large cooling capacity dilution refrigerator adopts a large superfluid helium refrigerator as a front pre-cooling unit, which can provide an ultra-large pre-cooling capacity, overcomes the shortcomings of the traditional dry dilution refrigerator adopting a GM refrigerator / pulse tube refrigerator as a front pre-cooling unit, which has a limited pre-cooling capacity, and the traditional wet dilution refrigerator needs to be immersed in a liquid helium dewar for pre-cooling, which is inconvenient to operate, etc., greatly improves the pre-cooling capacity, thereby making the ultra-large cooling capacity dilution refrigerator possible.

[0075] The working process of the dilution refrigeration module 200 is as follows:

[0076] 1) After the 5K 3 He low temperature circulation pump 204 circulation 3 He gas is precooled to 4.5K in the 4.5K liquid pool 10, enters the fourth heat exchanger 14 and mixes with the reflux cold helium gas (i.e., the refluxed helium gas from the distiller 203). 3 He gas) for further heat exchange, and then enters the 1.2K liquid pool 20 to be further precooled to 1.2K to form3 The limiting valve 208 acts as a flow limiter to control 3 He liquid flow rate and maintain the required condensing pressure. 3 He liquid first enters the distiller 203 through the limiting valve 208, is cooled to about 0.6K in the distiller 203, then flows through the continuous heat exchanger and the stepped heat exchanger of the heat exchanger group 202 in sequence, is further cooled, and finally flows into the mixing chamber 201 for dilution refrigeration; in this process, 3 The cooling capacity required by the He liquid from the limiting valve 208 to the heat exchanger group 202 is determined by the reverse flow. 3 He (i.e., refluxed from the distiller 203 3 The above equipment constitutes the dense phase system of the dilution refrigeration module 200, which is used to continuously supply a very low temperature liquid to the mixing chamber 201. 3 He, that is 3 He concentrated solution.

[0077] It is worth mentioning that the distiller 203 was originally filled with 4 He liquid, and keep the temperature at about 0.6K. 3 Diffusion of He molecules, the actual content of the distiller 203 is 3 He / 4 The concentration of He solution depends on the temperature of the solution. The lower the temperature, the 3 For example, when the temperature of the distiller 203 is 0.7K, the concentration of the solution in the distiller 203 is x=1%, and the concentration of He in the steam is 3 The He partial pressure is 10.67 Pa, 4 The partial pressure of He accounts for only 1.4% of the total pressure. 3 He cryogenic circulating pump 204 mainly pumps away 3 He, among them 4 The He content can be ignored.

[0078] It is also worth mentioning that the distiller 203 3 He evaporates continuously, so heat needs to be added per unit time.

[0079] 2) The mixing chamber 201 is a device that generates and outputs cold energy. The mixing chamber 201 contains extremely low temperature 3 He / 4 He solution, and phase separation has occurred. 3 After the He liquid enters, it becomes a dense phase and floats on top. 4 He has reached a superfluid state, in which3 He can diffuse freely without any resistance. 3 When He passes through the phase interface and enters the dilute phase, 3 He is diluted, accompanied by an endothermic effect, thus generating cold.

[0080] It is worth mentioning that in this embodiment of the present invention, the upper layer in the mixing chamber 201 is 85% 3 He, the dense phase 3 He, 6.4% in the lower layer 3 He, that is, dilute phase 3 He.

[0081] 3) In order to make the dilution refrigeration process in the mixing chamber 201 continue, it is necessary to continuously remove the dilute phase. 3 He, in order to maintain the temperature T MC ) corresponding to the concentration. 3 The He molecules are removed from the mixing chamber 201 by two forces, namely, the osmotic pressure difference and the 5K 3 The suction force of the He low temperature circulation pump 204. Specifically, first, the dilute phase in the mixing chamber 201 3 He first diffuses from the mixing chamber 201 through the sixth pipeline in reverse flow through the heat exchanger group 202 into the distiller 203 based on the difference in osmotic pressure, evaporates in the distiller 203, and then diffuses into the distiller 203 based on the 5K 3 The suction of the He circulation pump is sucked into the 5K 3 And circulation pump.

[0082] It is understandable that the conventional dilution refrigerator uses a room temperature circulation pump and has a problem of large heat loss, while the present invention uses the 5K 3 He low temperature circulation pump 204 replaces the traditional room temperature circulation pump, the 5K 3 Compared with the conventional room temperature circulating pump, the He low temperature circulating pump 204 has a compact structure and small vibration, which reduces the heat loss caused by vibration. 3 He low temperature circulation pump 204 is set in the vacuum chamber, which avoids the heat loss of the traditional room temperature circulation pump pipeline from room temperature to the low temperature vacuum chamber, reduces heat leakage, and greatly saves 3 The use of He is beneficial to the current extremely scarce 3 Development and application of large-capacity dilution refrigerator products under the current situation of He.

[0083] According to the formula To calculate the cooling capacity of the dilution refrigerator, if you want to get 1W of cooling capacity at 0.1K, the pre-cooling capacity at 1K needs to reach 123.6W. According to the Carnot efficiency, 1K cooling capacity is equivalent to 2K cooling capacity. If you want to get 1W of cooling capacity at 0.1K, you need 247.2W of 2K equivalent cooling capacity. It can be estimated that a 500W@2K superfluid helium refrigerator can meet the pre-cooling demand of a dilution refrigerator that produces about 2W@100mK of cooling capacity, that is, using a 500W@2K superfluid helium refrigerator for pre-cooling, the dilution refrigerator can produce about 2W@100mK of cooling capacity.

[0084] Traditional small dry dilution refrigerators generally use GM refrigerators or pulse tube refrigerators for precooling, and their cooling capacity at 4.2K is only 1.5-2W, the compressor power is generally 6-10kW, and the specific power consumption is as high as 3000-6667W / W. The ultra-large cooling capacity dilution refrigerator of the present invention uses the superfluid helium refrigeration module 100 as a precooling module. The superfluid helium refrigeration module 100 uses a turbine expansion unit as a refrigeration component, combined with cold compression technology, the precooling temperature can reach as low as 1.2K, and the cooling capacity at 4.2K can exceed 200W, and its specific power consumption will also be much lower than that of small mechanical refrigerators. According to the cooling capacity calculation formula of the dilution refrigerator and the aforementioned estimation process, the ultra-large cooling capacity dilution refrigerator provided by the present invention can generate a cooling capacity of more than 100mW@100mK (even reaching 1W@100mK cooling capacity), which can meet the needs of more than 1000 high-performance superconducting quantum bits, and can meet the current demand for ultra-large cooling capacity dilution refrigerators.

[0085] Figure 2 The structure of the ultra-large cooling capacity dilution refrigerator of the second embodiment of the present invention is shown, and the second embodiment is a modified embodiment of the first embodiment. Figure 1 The difference between the ultra-large cooling capacity dilution refrigerator shown in the figure is that the ultra-large cooling capacity dilution refrigerator of the second embodiment of the present invention adopts multiple mixing chambers 201, the multiple mixing chambers are connected in parallel, and each of the mixing chambers 201 corresponds to at least one sample rack, and the structures of other parts are the same as those of the first embodiment of the present invention.

[0086] It is worth mentioning that the conventional dilution refrigerator adopts a single mixing chamber 201 structure, and many GPUs (i.e., quantum computing chips) can be placed on the sample rack. There are many wires on each GPU chip, and the wires of multiple GPUs are prone to influence and interfere with each other. The ultra-large cooling capacity dilution refrigerator of the second embodiment of the present invention adopts a distributed mixing chamber 201, that is, a parallel structure of multiple mixing chambers 201, each mixing chamber 201 corresponds to at least one sample rack, and the multiple sample racks of the ultra-large cooling capacity dilution refrigerator are independent of each other, and the GPU chips placed on the sample rack do not interfere with each other, and the leads of different GPUs do not interfere with each other. Therefore, the ultra-large cooling capacity dilution refrigerator of the present invention can be applied to distributed quantum computer clusters, which can meet the current demand for ultra-large cooling capacity dilution refrigerators.

[0087] It can be understood that the second embodiment of the present invention is the best embodiment of the present invention.

[0088] In general, the present invention provides a large-capacity dilution refrigerator, which uses a large superfluid helium refrigerator as a pre-cooling unit, and uses a low-temperature circulation pump 204 to replace a traditional room temperature circulation pump. The low-temperature circulation pump 204 is placed in a vacuum chamber, so that the large-capacity dilution refrigerator can obtain a large cooling capacity, overcome the limited pre-cooling capacity and inconvenient operation of the traditional pre-cooling method, and the large heat loss and the large cooling capacity of the traditional room temperature circulation pump. 3 And the defect of high demand.

[0089] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A super large cooling capacity dilution refrigerator, characterized in that: include: Dilution refrigeration module, which is used to dilute 3 The He concentrated solution realizes refrigeration and provides cold capacity to the outside. The dilution refrigeration module is arranged in the vacuum chamber, and includes a mixing chamber, a heat exchanger group connected to the mixing chamber, a distiller connected to the heat exchanger group, and a low-temperature circulation pump connected to the distiller; and A superfluid helium refrigeration module, which is a large superfluid helium refrigerator, including a cold compressor unit arranged in the vacuum chamber, used to provide pre-cooling cooling capacity for the dilution refrigeration module, the superfluid helium refrigeration module has a 4.5K temperature zone and a 1.2K temperature zone, and the cold compressor unit includes a first cold compressor, a second cold compressor, a third cold compressor, a fourth cold compressor, a fifth cold compressor and a sixth cold compressor connected in series in sequence along the return air direction of the 1.2K liquid pool; The low temperature circulating pump of the dilution refrigeration module 3 After the He gas is precooled to 4.5K in the 4.5K temperature zone of the superfluid helium refrigeration module, it enters the 1.2K temperature zone and is precooled to 1.2K. 3 He liquid, 3 After the He liquid enters the distiller and is cooled to 0.6K, it enters the heat exchanger group for heat exchange, and finally enters the mixing chamber for dilution refrigeration. There are multiple mixing chambers, and the multiple mixing chambers are connected in parallel. 3 He flows through the heat exchanger group in countercurrent flow according to the osmotic pressure difference and then enters the distiller. 3 He enters the low-temperature circulation pump by relying on the suction force of the low-temperature circulation pump, thus completing a refrigeration cycle of the ultra-large cooling capacity dilution refrigerator; The low temperature circulation pump of the dilution refrigeration module is 5K 3 He low temperature circulation pump; The superfluid helium refrigeration module further includes a 4.5K liquid pool, a 1.2K liquid pool, a heat exchanger group and a throttle valve group, all of which are arranged in the vacuum chamber. The 4.5K liquid pool is used to provide the 4.5K temperature zone, the 1.2K liquid pool is used to provide the 1.2K temperature zone, the heat exchanger group includes a first heat exchanger, a second heat exchanger, a third heat exchanger and a fourth heat exchanger, the throttle valve group includes a first throttle valve and a second throttle valve, and the dilution refrigeration module also includes a 4.5K liquid pool, a 1.2K liquid pool, a heat exchanger group and a throttle valve group connected to the 5K 3 He low temperature circulation pump and the limiting valve of the distiller; wherein the 5K 3 He low temperature circulation pump output 3 After the He gas enters the 4.5K liquid pool and is precooled to 4.5K, it enters the fourth heat exchanger for heat exchange and then enters the 1.2K liquid pool and is precooled to 1.2K. 3 He liquid, precooled to 1.2K 3 The He liquid enters the distiller after being limited by the limiting valve. 3 He liquid enters the distiller and is cooled to 0.6K, and then further cooled by the heat exchanger group before flowing into the mixing chamber. 3 Follow 3 The He-concentrated phase migrates to 3 He in the scarce phase, generates cooling capacity, and the dilute phase in the mixing chamber 3 He enters the heat exchanger group in reverse flow according to the osmotic pressure difference and then enters the distiller. After evaporation in the distiller, He enters the distiller according to the 5K 3 The suction of the He low temperature circulation pump flows countercurrently through the fourth heat exchanger and enters the 5K 3 He low-temperature circulation pump, so far a refrigeration cycle of the dilution refrigeration module is completed, the high-pressure helium is separated into two parts after heat exchange through the first heat exchanger and the second heat exchanger in turn, one part directly enters the 4.5K liquid pool, and the other part enters the liquid in the 4.5K liquid pool after throttling into gas-liquid two-phase through the first throttle valve; the saturated steam in the 4.5K liquid pool is returned to low pressure, and the liquid helium flowing out of the bottom of the 4.5K liquid pool enters the second section after heat exchange and temperature reduction through the third heat exchanger. The flow valve throttles the gas-liquid two-phase flow, and the gas-liquid two-phase flow enters the 1.2K liquid pool and accumulates liquid. When the liquid level in the 1.2K liquid pool reaches a preset value, the cold compressor unit starts to reduce the pressure and cool the 1.2K liquid pool, and the temperature of the 1.2K liquid pool is controlled at 1.2K, and the pressure is controlled to be negative pressure; the return air of the 1.2K liquid pool countercurrently passes through the third heat exchanger, the cold compressor unit and the first heat exchanger, and then returns to the compressor station, thereby completing a refrigeration cycle of the superfluid helium refrigeration module.

2. The ultra-large cooling capacity dilution refrigerator according to claim 1, characterized in that: The superfluid helium refrigeration module further includes a first pipeline for connecting the first heat exchanger, the second heat exchanger and the 4.5K liquid pool, a second pipeline for connecting the 4.5K liquid pool, the third heat exchanger, the second throttle valve and the 1.2K liquid pool, a third pipeline for connecting the 4.5K liquid pool, the second heat exchanger and the first heat exchanger, and a fourth pipeline for connecting the 1.2K liquid pool, the third heat exchanger, the cold compressor unit and the first heat exchanger, wherein: The high-pressure helium gas enters the first heat exchanger and the second heat exchanger in sequence through the first pipeline, a part of the high-pressure helium gas directly enters the 4.5K liquid pool through the first pipeline, and the other part of the high-pressure helium gas enters the 4.5K liquid pool after being throttled by the first throttle valve; The liquid helium flowing out from the bottom of the 4.5K liquid pool enters the third heat exchanger through the second pipeline for heat exchange, is throttled into gas-liquid two-phases through the second throttle valve, and then enters the 1.2K liquid pool; The saturated steam in the 4.5K liquid pool passes through the third pipeline in countercurrent through the second heat exchanger and the first heat exchanger and then returns to low pressure; The gas phase in the 1.2K liquid pool flows countercurrently through the fourth pipeline into the third heat exchanger, the cold compressor unit and the first heat exchanger, and then returns to the compressor station.

3. The ultra-large cooling capacity dilution refrigerator according to claim 2, characterized in that: The dilution refrigeration module also includes a device for connecting the 5K 3 He low temperature circulation pump, the 4.5K liquid pool, the fourth heat exchanger, the 1.2K liquid pool, the limiting valve, the distiller, the heat exchanger group and the fifth pipeline of the mixing chamber, a sixth pipeline for connecting the mixing chamber, the heat exchanger group and the distiller; and a sixth pipeline for connecting the distiller, the fourth heat exchanger and the 5K 3 The seventh pipeline of the He cryogenic circulation pump, wherein The 5K 3 He cryogenic circulation pump 3 After He gas enters the 4.5K liquid pool, the fourth heat exchanger and the 1.2K liquid pool in sequence through the fifth pipeline and is precooled to 1.2K, 3 He liquid, 3 After the He liquid is limited by the limiting valve, it enters the distiller and the heat exchanger group in sequence, and finally enters the mixing chamber; The dilute phase in the mixing chamber 3 He relies on the osmotic pressure difference to enter the distiller through the sixth pipeline in countercurrent through the heat exchanger group; The evaporated 3 He gas relies on the 5K 3 The suction force of the He low temperature circulation pump is sucked into the 5K 3 And low temperature circulation pump.

4. The ultra-large cooling capacity dilution refrigerator according to any one of claims 1 to 3, characterized in that: The heat exchanger group includes a continuous heat exchanger and a stepped heat exchanger, wherein the cooling to 0.6K 3 The He liquid flows into the mixing chamber after passing through the continuous heat exchanger and the stepped heat exchanger in sequence.

5. The ultra-large cooling capacity dilution refrigerator according to any one of claims 1 to 3, characterized in that: Each of the mixing chambers corresponds to at least one sample holder.

6. The ultra-large cooling capacity dilution refrigerator according to any one of claims 1 to 3, characterized in that: The distiller was originally filled with liquid 4 He.

7. The ultra-large cooling capacity dilution refrigerator according to any one of claims 2 to 3, characterized in that: The 4.5K liquid pool and the 1.2K liquid pool are both 4 Heating liquid pool.

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