Dilution unit capable of rapidly cooling and dilution refrigerating machine

Abstract

The invention discloses a rapid cooling dilution unit. The rapid cooling dilution unit comprises a dilution unit inlet, a closed heat exchange structure and a dilution unit outlet, the closed heat exchange structure comprises an upper base plate, an inflation and deflation opening, a lower base plate, a dilution cavity, a heat exchanger set, a sealing wall face, a heating device and an adsorption device. The upper base plate, the lower base plate and the sealing wall face form a sealing cavity, the heat exchanger set is arranged in the sealing cavity, and pipelines in the heat exchanger set are connected with the dilution unit inlet, the dilution unit outlet and the dilution cavity in a sealed mode to form a circulating heat exchange pipeline. The inflation and deflation port is formed in the sealing cavity; the adsorption device is communicated with the interior of the sealed cavity and is filled with an adsorbent; the heating device is arranged on the adsorption device and is used for heating the adsorption device and the adsorbent in the adsorption device. The heat exchanger set is arranged in the sealing cavity, the heat exchange state is regulated and controlled by releasing and adsorbing gas, the cooling efficiency of the dilution refrigeration system is remarkably improved, and meanwhile the heat insulation performance of the dilution refrigeration system in a low-temperature steady state is ensured.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic refrigeration technology, and relates to a rapid cooling dilution unit and a dilution refrigeration machine. Background Technology

[0002] Dilution refrigerators, as devices capable of continuously providing mK-level temperatures, are widely used in fields such as quantum information science, condensed matter physics, cryogenic electronics, and astrophysics. Especially in the field of quantum information science, dilution refrigerators, utilizing their mK-level temperature environment, can significantly reduce system thermal noise and prevent the suppression of extremely weak quantum signals, thus finding widespread application in superconducting quantum computing, semiconductor quantum computing, and other fields.

[0003] In the field of quantum information, the cooling time of a dilution refrigerator is a very important indicator. A dilution refrigerator system with a short cooling time can enable rapid reuse of the system, shorten the response time, accelerate system experiments and applications, and thus enable rapid iteration of quantum computing hardware and software.

[0004] The cooling process of existing dilution refrigeration systems typically exhibits a phased characteristic. In the higher temperature phase starting from room temperature, the system can achieve relatively rapid cooling using mechanisms such as thermal switches or active gas circulation. However, once the system temperature drops to a certain lower range (e.g., below 15K), the efficiency of these mechanisms decreases significantly, and the subsequent cooling process mainly relies on the flow and heat exchange of the working fluid within the dilution refrigeration cycle itself. The cooling rate in this phase largely determines the overall cooling time of the system.

[0005] Analysis shows that in this critical low-temperature range, the cooling bottleneck of the system is often concentrated in the dilution unit itself. Traditional dilution units contain multi-stage discrete heat exchangers, and their structures often involve powder sintered materials with poor thermal conductivity. Furthermore, these internal components are often connected to the external cold source via structural parts with low thermal conductivity (such as stainless steel supports), creating significant thermal resistance. This structural limitation makes it difficult for the cooling capacity from the cold source to be efficiently transferred to the core area of ​​the dilution unit, thus severely delaying its own cooling process and limiting the overall cooling efficiency of the refrigeration system.

[0006] Therefore, there is an urgent need in this field for a novel dilution unit structure design, which aims to fundamentally improve its internal thermal conductivity in the low-temperature region in order to break through the cooling speed bottleneck of existing technologies. Summary of the Invention

[0007] Purpose of the invention: To address the technical problem that existing dilution units suffer from slow cooling in deep low-temperature regions due to high thermal resistance in their internal heat conduction paths, this invention provides a dilution unit and a dilution refrigerator for rapid cooling.

[0008] Technical solution: The present invention provides a rapid cooling dilution unit, comprising a dilution unit inlet, a closed heat exchange structure, and a dilution unit outlet; the closed heat exchange structure comprises an upper chassis, a gas filling / discharging port, a lower chassis, a dilution chamber, a heat exchanger assembly, a sealing wall, a heating device, and an adsorption device; The upper chassis, lower chassis, and sealing wall form a sealed cavity. The heat exchanger assembly is disposed inside the sealed cavity. The internal pipelines of the heat exchanger assembly are respectively sealed and connected to the inlet of the dilution unit, the outlet of the dilution unit, and the dilution cavity to form a circulating heat exchange pipeline. The charging and discharging port is disposed on the sealed cavity for charging or discharging heat exchange gas into or out of the sealed cavity. The adsorption device is connected to the inside of the sealed cavity and is filled with adsorbent. The heating device is disposed on the adsorption device for heating the adsorption device and the adsorbent inside it.

[0009] Furthermore, the upper and lower chassis are made of oxygen-free copper or high-purity aluminum and are connected to the upper-level cold source via a thermal switch.

[0010] Furthermore, the two ends of the sealing wall are respectively sealed to the upper chassis and the lower chassis through a first sealing structure and a second sealing structure.

[0011] Furthermore, the first sealing structure and the second sealing structure are welded structures or metal sealing structures.

[0012] Furthermore, the heat exchange gas is selected from helium, hydrogen, or neon.

[0013] Furthermore, the adsorbent has the characteristic of reversibly adsorbing heat exchange gases under low temperature conditions.

[0014] Furthermore, the adsorbent is one of activated carbon, zeolite molecular sieve, or metal-organic framework materials.

[0015] Another aspect of the present invention is to provide a dilution refrigeration machine, including the above-mentioned rapid cooling and dilution unit.

[0016] Principle: The closed heat exchange structure achieves its function by regulating the gas environment within the sealed cavity. Before system startup, heat exchange gas is introduced into the sealed cavity through the filling and venting ports, maintaining the seal. When the system begins to cool down, the heating device is activated, causing the adsorbent to release the heat exchange gas, increasing the gas pressure within the cavity. This enhances heat transfer between the heat exchanger assembly and the upper and lower chassis through the gas's thermal conduction and convection effects, accelerating the cooling process. When the system reaches the target temperature and enters a steady-state operation phase, the heating device is turned off. The adsorbent re-adsorbs the gas at low temperatures, creating a high vacuum within the sealed cavity. This significantly reduces heat leakage caused by gas conduction and convection, ensuring the system's thermal isolation performance.

[0017] Beneficial effects: Compared with the prior art, the present invention realizes the switching between two working modes of dilution unit, namely "enhanced heat conduction" and "high-efficiency insulation", by constructing a closed heat conduction structure with integrated adsorption-heating regulation mechanism. This not only significantly accelerates the cooling process of dilution unit in the deep low temperature region, but also ensures its insulation performance during steady-state operation, thereby effectively improving the overall cooling efficiency and operating performance of the dilution refrigeration system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of Embodiment 1.

[0020] Figure 3 This is a schematic diagram of the structure of Embodiment 2. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0022] like Figure 1 As shown, a rapid cooling dilution unit includes a dilution unit inlet 1, a closed heat exchange structure 13, and a dilution unit outlet 12. The closed heat exchange structure 13 includes an upper chassis 2, a first sealing structure 3, a gas filling / discharging port 4, a second sealing structure 5, a lower chassis 6, a dilution chamber 7, a heat exchanger assembly 8, a sealing wall 9, a heating device 10, and an adsorption device 11. The two ends of the sealing wall 9 are sealed to the upper chassis 2 and the lower chassis 6 through the first sealing structure 3 and the second sealing structure 5, respectively, forming a sealed cavity. Specifically, the first sealing structure 3 and the second sealing structure 5 are welded structures or metal sealing structures. The upper chassis 2 and the lower chassis 6 are made of oxygen-free copper or high-purity aluminum and are connected to an upper-level cold source through a heat-conducting structure.

[0023] The heat exchanger group 8 is located inside the sealed cavity. The internal pipelines of the heat exchanger group 8 are respectively sealed and connected to the dilution unit inlet 1, the dilution unit outlet 12, and the dilution cavity 7 to form a circulating heat exchange pipeline.

[0024] The filling / discharging port 4 is located on the sealed cavity and is used to fill or remove the heat exchange gas into the sealed cavity. The heat exchange gas has a high thermal conductivity and is selected from helium, hydrogen, or neon.

[0025] The adsorption device 11 is connected to the interior of the sealed cavity and is filled with adsorbent. A heating device 10 is installed on the adsorption device 11 to heat the adsorption device 11 and the adsorbent inside. The adsorbent has the characteristic of reversibly adsorbing heat exchange gases at low temperatures and is selected from activated carbon, zeolite molecular sieves, or metal-organic framework materials. The heating device 10 is connected to an external power supply via current leads and can precisely heat the adsorption device 11 under control signals, causing the adsorbent to release the adsorbed heat exchange gases.

[0026] Example 1: This example enhances heat exchange by placing the mixing chamber and the stepped heat exchanger and continuous heat exchanger in the heat exchanger group 8 in a closed heat exchange structure.

[0027] like Figure 2 The dilution unit shown mainly includes a distillation chamber, a mixing chamber, a heat exchanger group 8, and a closed heat exchange structure 13.

[0028] The distillation chamber, mixing chamber, and heat exchanger assembly 8 constitute the basic structure of a conventional dilution unit. The distillation chamber consists of a dilution unit inlet 1, heat exchange coils 15, a distillation chamber base 21, a dilution unit outlet 12, and a distillation chamber cavity 14. The mixing chamber consists of a mixing chamber base 61 and a dilution cavity 7. The heat exchanger assembly 8 includes a shell-and-tube heat exchanger 16, an intermediate cooling plate 17, and a stepped heat exchanger 18 connected in sequence. The inner tube of the shell-and-tube heat exchanger 16 is sealed to the heat exchange coils 15, and the outer tube is sealed to the distillation chamber base 21. The stepped heat exchanger 18 is also sealed to the dilution cavity 7, thus forming a complete sealed-loop dilution unit structure.

[0029] In this dilution unit, the refrigerant enters from the inlet 1 as a mixed gas and flows sequentially through the heat exchange coil 15, the shell-and-tube heat exchanger 16, and the stepped heat exchanger 18. During this process, the refrigerant undergoes multi-stage counter-current heat exchange with the reflux refrigerant, and after being sufficiently pre-cooled, it enters the dilution chamber 7. Phase separation and dilution refrigeration effects occur in the mixing chamber, producing a cooling effect. The reflux refrigerant, after completing refrigeration, returns to the distillation chamber 14 sequentially through the stepped heat exchanger 18, the intermediate cooling plate 17, and the shell-and-tube heat exchanger 16, and is finally recovered by the circulating pump through the dilution unit outlet 12, forming a continuous refrigeration cycle.

[0030] Because the shells of the shell-and-tube heat exchanger 16 and the stepped heat exchanger 18 in heat exchanger group 8 of this structure are made of stainless steel, their thermal conductivity is poor. Furthermore, the stepped heat exchanger 18 and the mixing chamber contain a large amount of sintered powder, which is not only heavy but also has low thermal conductivity. These material characteristics combined result in high thermal resistance in this area, becoming a major bottleneck in the system's heat exchange process and directly affecting the cooling efficiency of the dilution unit.

[0031] Therefore, this invention integrates a closed heat exchange structure 13 on the basis of a conventional dilution unit structure to form a dilution unit with rapid cooling. The closed heat exchange structure 13 consists of a sealed cavity, a gas filling / draining port 4, an adsorption device 11, and a heating device 10. The sealed cavity consists of an upper base plate 2, a lower base plate 6, and a sealing wall surface 9. In this embodiment, the upper base plate 2 is a distillation chamber base plate 21, and the lower base plate 6 is a mixing chamber base plate 61. The distillation chamber base plate 21 and the mixing chamber base plate 61 are respectively connected to the two ends of the annular sealing wall surface 9 through a first sealing structure 3 and a second sealing structure 5 to form a rigid sealed cavity. The gas filling / draining port 4 is located on the sealing wall surface 9 and can be connected to an external gas source and a gas extraction system to fill or extract heat exchange gas with high thermal conductivity into the sealed cavity. The adsorption device 11 is connected to the inside of the sealed cavity. The adsorption device 11 is filled with an adsorbent, which has the characteristic of reversibly adsorbing heat exchange gas under low temperature conditions, adsorbing gas at low temperature and releasing it at high temperature. The heating device 10 is integrated on the surface of the adsorption device 11 and is connected to an external power source through a current lead. It can precisely heat the adsorption device 11 under the action of a control signal, causing the adsorbent to release the heat exchange gas it adsorbs.

[0032] The dilution refrigeration unit equipped with the rapid cooling and dilution unit of this invention achieves its function by regulating the gas environment within the closed heat exchange structure 13. The specific working process is as follows: Before the dilution refrigeration system starts cooling, heat exchange gas at a certain pressure is introduced into the sealed cavity through the charging and discharging port 4. After the charging is completed, the charging and discharging port remains sealed. When the system starts cooling, the heating device 10 is activated to heat the adsorption device 11, causing it to release the adsorbed heat exchange gas. During the subsequent cooling process, the heat exchange gas in the sealed cavity enhances the heat transfer between the distillation chamber chassis 21 and the mixing chamber chassis 61 (which are respectively connected to the upper-level cold source through a copper plate and a thermal switch) and the shell-and-tube heat exchanger 16, the intermediate cold plate 17, and the stepped heat exchanger 18 through heat conduction and convection, thereby accelerating the cooling process of the above-mentioned key components and shortening the time for the system to reach the target temperature. During the steady-state operation phase after the system reaches the target temperature, in order to reduce heat leakage from the upper-level cold plate to the lower-level cold plate, the sealed cavity needs to be switched to an adiabatic state. At this time, the heating device 10 is turned off, and the temperature of the adsorption device 11 drops accordingly. The adsorbent inside the device re-adsorbs the heat exchange gas in the cavity, which significantly reduces the heat conduction and convective heat leakage of the gas, ensuring that the system maintains a good thermal isolation state in the low temperature stage.

[0033] Example 2: In this example, the mixing chamber and the stepped heat exchanger in the heat exchanger group 8 are arranged in a closed heat exchange structure, thereby enhancing the heat exchange of the mixing chamber and the stepped heat exchanger in the heat exchanger group 8.

[0034] like Figure 3As shown, this embodiment differs from Embodiment 1 in that the upper chassis 2 is an intermediate cold plate 17, and the lower chassis 6 is a mixing chamber chassis 61, meaning the closed heat exchange structure 13 is installed between the intermediate cold plate 17 and the mixing chamber chassis 61. The sealed cavity of the closed heat exchange structure 13 is formed by the intermediate chassis 17 and the mixing chamber chassis 61 being sealed and connected to both ends of the annular sealing wall surface 9 through the first sealing structure 3 and the second sealing structure 5, respectively. The charging / discharging port 4, the adsorption device 11, and the heating device 10 are still installed on the sealed cavity.

[0035] The system operates as follows: Before the dilution refrigeration system starts cooling, heat exchange gas at a certain pressure is introduced into the sealed cavity through the charging / discharging port 4. After charging, the charging / discharging port remains sealed. When the system begins cooling, the heating device 10 is activated to heat the adsorption device 11, causing it to release the adsorbed heat exchange gas. During subsequent cooling, the heat exchange gas in the sealed cavity enhances heat transfer between the intermediate cold plate 17 and the mixing chamber chassis 61 (which maintain good thermal connection with the upper-level cold source through a copper plate and a thermal switch, respectively) and the stepped heat exchanger 18 through conduction and convection, thereby accelerating the cooling process of the aforementioned key components and shortening the time it takes for the system to reach the target temperature. During the steady-state operation phase after the system reaches the target temperature, to reduce heat leakage from the upper-level cold plate to the lower-level cold plate, the sealed cavity needs to be switched to an adiabatic state. At this time, the heating device 10 is turned off, and the temperature of the adsorption device 11 drops accordingly. The adsorbent inside the device re-adsorbs the heat exchange gas in the cavity, significantly reducing the heat conduction and convection leakage of the gas, ensuring that the system maintains a good thermal isolation state during the low-temperature stage.

[0036] Through the above structural design, the present invention achieves efficient heat conduction of the dilution unit during the cooling stage and reliable heat insulation during the steady-state operation stage, effectively improving the overall performance of the dilution refrigeration system.

Claims

1. A flash chill dilution unit characterized by, The dilution unit comprises an inlet (1), a closed heat exchange structure (13) and an outlet (12); the closed heat exchange structure (13) comprises an upper bottom plate (2), a gas charging and discharging port (4), a lower bottom plate (6), a dilution cavity (7), a heat exchanger group (8), a sealing wall (9), a heating device (10) and an adsorption device (11); The upper bottom plate (2), the lower bottom plate (6) and the sealing wall (9) form a sealed cavity, the heat exchanger group (8) is arranged inside the sealed cavity, the internal pipeline of the heat exchanger group (8) is in sealed connection with the dilution unit inlet (1), the dilution unit outlet (12) and the dilution cavity (7) respectively, forming a circulating heat exchange pipeline; the gas charging and discharging port (4) is arranged on the sealed cavity and is used for charging or discharging heat exchange gas into the sealed cavity; the adsorption device (11) is in communication with the inside of the sealed cavity, and the adsorption device (11) is filled with an adsorbent; the heating device (10) is arranged on the adsorption device (11) and is used for heating the adsorption device (11) and the adsorbent inside the adsorption device (11).

2. The flash cooling dilution unit of claim 1, wherein, The upper bottom plate (2) and the lower bottom plate (6) are made of oxygen-free copper or high-purity aluminum and are connected to a higher-level cold source through a thermal switch.

3. The flash cooling dilution unit of claim 1, wherein, The sealing wall (9) is in sealed connection with the upper bottom plate (2) and the lower bottom plate (6) through the first sealing structure (3) and the second sealing structure (5) at both ends respectively.

4. The flash cooling dilution unit of claim 3, wherein, The first sealing structure (3) and the second sealing structure (5) are welding structures or metal sealing structures.

5. The flash cooling dilution unit of claim 1, wherein, The heat exchange gas is selected from one of helium, hydrogen and neon.

6. The flash thaw dilution unit of claim 1, wherein, The adsorbent has the characteristics of reversible adsorption of heat exchange gas under low-temperature conditions.

7. The flash thaw dilution unit of claim 6, wherein, The adsorbent is one of activated carbon, zeolite molecular sieve and metal organic framework material.

8. A dilution refrigerator, characterized by, The rapid cooling dilution unit comprises the rapid cooling dilution unit according to any one of claims 1-7.

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