Pre-cooling type JT throttling refrigerating machine

Abstract

The invention relates to the technical field of mechanical refrigeration, and provides a pre-cooling type JT throttling refrigerator which comprises a pre-cooler with a cold head. A linear driving mechanism; the compression unit is connected with the linear driving mechanism and outputs a high-pressure gas working medium under the action of the linear driving mechanism; the vacuum cover is used for providing a vacuum heat insulation effect; the compression unit and the cold head are coupled and are positioned in the vacuum cover; the heat exchanger is used for pre-cooling the high-pressure incoming flow gas by utilizing the backflow cold gas; the throttling valve penetrates through the heat exchanger and communicates with the high-pressure end of the compression unit; one end of the evaporator is connected with the throttle valve, and the other end penetrates through the heat exchanger and is connected with the low-pressure end of the compression unit. The compression unit for driving the throttling working medium is placed in the vacuum cover and located at the low temperature, the output performance of the compression unit is improved, and therefore the system efficiency of the refrigerating machine is improved; in addition, the compression unit is directly coupled with the cold head, the system structure is simplified, and the efficiency of the refrigerating system is improved.

Description

Technical Field

[0001] This invention relates to the field of mechanical refrigeration technology, and in particular to a pre-cooling type JT throttling refrigerator. Background Technology

[0002] With the continuous development of space exploration and ground-based cooling technologies, the demand for cold environments in the liquid helium temperature range and even the superfluid helium temperature range is becoming increasingly widespread. Especially in the field of space exploration, the liquid helium to superfluid helium temperature range is not only the operating temperature range of certain key detectors (such as superconducting quantum interference devices (SQUIDs), superconducting photon detectors (SNSPDs), and superconducting terahertz detectors), but also the pre-cooling stage temperature range for cryogenic refrigerators in even lower temperature ranges (such as adsorption refrigerators, dilution refrigerators, and adiabatic demagnetizing refrigerators). Compared with other space refrigerators, the JT throttling refrigerator, a pre-cooled type in the liquid helium to superfluid helium temperature range, has the advantages of no moving parts in the cold head, the ability to transfer cold energy over long distances, low vibration and electromagnetic interference, and high efficiency in the liquid helium temperature range, making it a common choice for mechanical refrigerators in this temperature range.

[0003] like Figure 1 As shown, this is a liquid helium temperature-range pre-cooling refrigerator in the prior art. Pre-cooling is provided by a two-stage pre-cooler A01. The helium working fluid is compressed by the compressor to form a high-pressure gas. The high-pressure gas is cooled by the returning low-pressure gas as it flows through three-stage counter-current indirect heat exchangers A09, A10, and A11. Then, as it flows through two-stage pre-cooling heat exchangers A12 and A13, it is cooled to the corresponding pre-cooling temperature by the pre-cooler cold heads A14 and A15. Subsequently, it is cooled by the expansion valve A17 to produce a cooling effect and is reduced to a low pressure. The low-pressure gas absorbs heat load through the cold head heat exchanger A18 to provide cooling capacity, and finally returns to the compressor via the low-pressure side of the three-stage counter-current indirect heat exchangers A11, A10, and A09.

[0004] The compressor is generally a linear compressor, which includes a linear drive mechanism A02, a cylinder A04, and a piston A05. The linear drive mechanism A02 drives the connecting rod A03 and the piston A05 to reciprocate within the cylinder A04. The unidirectional flow of gas is created by the alternating opening and closing of the inlet valve A06 and the exhaust valve A07. Because the compressor operates at ambient temperature, the cold head of the pre-cooler and the heat exchanger of the JT throttling refrigeration unit operate in a vacuum low-temperature environment, installed inside the vacuum enclosure A08. The compressor is connected to the JT throttling components via piping, resulting in low compressor efficiency.

[0005] Furthermore, the JT throttling refrigerator in the liquid helium temperature range experiences a slow cooling rate after startup. This is primarily because the highest conversion temperature of the helium working fluid is lower than the ambient temperature. During the initial cooling phase, the indirect heat exchangers and cold-end heat exchangers at each stage are still at room temperature. After pre-cooling, the low-temperature working fluid entering the high-pressure side of heat exchanger A11 is heated by the high-temperature working fluid on the low-pressure side, making it difficult for the cooling capacity to be transferred to the throttling valve A17 and the evaporator A18. To achieve rapid cooling, a bypass valve A16 is typically installed near the cold head of the JT throttling refrigerator. However, the introduction of the bypass valve requires a corresponding control system, which increases the system's complexity and unreliability. Summary of the Invention

[0006] This invention provides a pre-cooled JT throttling refrigerator to solve the problem of low compression efficiency in the prior art and improve the output performance of the compression unit.

[0007] This invention provides a pre-cooling JT throttling refrigerator, comprising: Precooling unit, equipped with a cold head; Linear drive mechanism; A compression unit is connected to the linear drive mechanism, and the compression unit outputs a high-pressure gaseous working fluid under the action of the linear drive mechanism. The vacuum chamber provides vacuum insulation; the compression unit is coupled to the cold head, and both are located inside the vacuum chamber. A heat exchanger is used to precool high-pressure incoming gas using reflux cold gas; A throttle valve passes through the heat exchanger and is connected to the high-pressure end of the compression unit; The evaporator is connected at one end to the throttling valve and at the other end through the heat exchanger and connected to the low-pressure end of the compression unit.

[0008] According to the present invention, a pre-cooled JT throttling refrigerator is provided, wherein the compression unit comprises: A cylinder and a piston; the cylinder provides space for compressing and throttling the working fluid during the linear reciprocating motion of the piston; the piston is slidably disposed within the cylinder and is connected to the linear drive mechanism to achieve reciprocating motion; An intake valve and an exhaust valve are mounted on the cylinder. They alternately open and close based on the gas pressure difference between the cylinder and the inlet and outlet pipes to achieve unidirectional gas flow. The exhaust valve is connected to the throttle valve, and the intake valve is connected to the other end of the evaporator.

[0009] According to the present invention, a pre-cooled JT throttling refrigerator further includes: A piston rod is used to connect the piston and the linear drive mechanism.

[0010] According to the present invention, a pre-cooled JT throttling refrigerator further includes: A bellows, one end of which is sealed to the piston rod and reciprocates with the bellows, and the other end of which is sealed to the cylinder.

[0011] According to the present invention, a pre-cooled JT throttling refrigerator is provided in which the linear drive mechanism and the compression unit are used in pairs and are arranged back-to-back in a straight line.

[0012] According to the present invention, a pre-cooling JT throttling refrigerator is provided, wherein the heat exchanger adopts a coaxial spiral sleeve structure.

[0013] According to the present invention, a pre-cooling type JT throttling refrigerator is provided, wherein the pre-cooling refrigerator includes one of a GM type refrigerator, a Stirling type refrigerator, or a pulse tube refrigerator.

[0014] According to the present invention, a pre-cooled JT throttling refrigerator is provided, wherein the throttling valve is configured as a metal plate with a small hole structure, and the gaseous working fluid expands through the small hole to generate a cooling effect.

[0015] According to the present invention, a pre-cooling JT throttling refrigerator is provided, wherein the vacuum shroud adopts an internal multi-layer shell structure.

[0016] According to the present invention, a pre-cooled JT throttling refrigerator is provided, wherein the linear drive mechanism is set in a normal temperature and pressure environment, and the heat generated is dissipated through air cooling or water cooling.

[0017] The pre-cooled JT throttling refrigerator provided by this invention improves the output performance of the compression unit by placing the compression unit driving the throttling working fluid inside a vacuum chamber at a low temperature, thereby improving the system efficiency of the refrigerator. The compression unit also boasts advantages of miniaturization and high reliability. Furthermore, the direct coupling between the compression unit and the cold head eliminates the need for multi-stage heat exchangers compared to existing technologies, simplifying the system structure and improving the efficiency of the refrigeration system. Simultaneously, the linear drive mechanism is positioned at room temperature, preventing the Joule heat generated by the linear drive mechanism from being introduced into the throttling refrigeration cycle, thus further enhancing the system efficiency of the refrigerator. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a structural schematic diagram of a pre-cooling throttling refrigerator in the prior art.

[0020] Figure 2 This is a schematic diagram of the pre-cooling JT throttling refrigerator provided by the present invention.

[0021] Figure label: 1. Precooling unit; 2. Cold head; 3. Linear drive mechanism; 4. Vacuum hood; 5. Heat exchanger; 6. Throttling valve; 7. Evaporator; 8. Cylinder; 9. Piston; 10. Inlet valve; 11. Exhaust valve; 12. Piston rod; 13. Bellows. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The following is combined with Figure 2 The present invention describes a pre-cooled JT throttling refrigerator.

[0024] An embodiment of the present invention provides a pre-cooled JT throttling refrigerator, including a pre-cooler 1, a cold head 2, a linear drive mechanism 3, a compression unit, a vacuum shroud 4, a heat exchanger 5, a throttling valve 6, and an evaporator 7.

[0025] The precooler 1 has a cold head 2. The precooler can be a small low-temperature refrigerator such as a GM-type refrigerator, a Stirling-type refrigerator, or a pulse tube refrigerator. The precooler 1 is filled with a throttling gas working fluid at an appropriate pressure. The precooler 1 generally uses a two-stage or multi-stage cold head cooling method. This embodiment illustrates a two-stage cold head 2, including a primary cold head and a secondary cold head, both of which are installed inside a vacuum chamber 4.

[0026] The linear drive mechanism 3 provides the power for linear motion. It can be a linear motor, which can reciprocate linearly after an AC voltage is applied. Alternatively, the linear drive mechanism 3 can also employ other structures such as a pneumatic cylinder or an electric cylinder to achieve linear motion.

[0027] The compression unit is connected to the linear drive mechanism 3, and the compression unit outputs high-pressure gas working fluid under the action of the linear drive mechanism 3.

[0028] Vacuum shroud 4 provides vacuum insulation; the compression unit is coupled to the cold head 2, and both are located inside the vacuum shroud 4; the compression unit is arranged in a low-temperature vacuum environment, which improves the output performance of the compression unit. Directly coupled to the cold head 2, the cold head 2 directly cools the compression unit and the throttling working fluid, eliminating the need for multi-stage heat exchangers, simplifying the system structure, and improving the efficiency of the JT throttling refrigerator.

[0029] Heat exchanger 5 is used to precool high-pressure incoming gas using return cold gas, and the high-pressure gas pipeline of heat exchanger 5 is connected to the inlet end of throttle valve 6.

[0030] The throttle valve 6 passes through the heat exchanger 5 and is connected to the high-pressure end of the compression unit; a small hole is opened on the metal plate of the throttle valve 6, and the high-pressure gas expands through the small hole to generate a cooling effect.

[0031] One end of the evaporator 7 is connected to the throttle valve 6, and the other end passes through the heat exchanger 5 and is connected to the low-pressure end of the compression unit. The evaporator 7 is a heat exchanger used to absorb heat from the target load.

[0032] The refrigeration process of the pre-cooled JT throttling refrigerator provided by this invention is as follows: First, a throttling gas working fluid at an appropriate pressure is charged into the pre-cooler. The compression unit is started to pre-cool the gas working fluid. Then, the linear drive mechanism 3 is started, and the gas working fluid is compressed by the throttling compression unit to form high-pressure gas, which is discharged to the throttling valve 6. The throttling valve 6 cools the gas, producing a refrigeration effect and reducing the pressure to low. The low-pressure gas absorbs heat load through the evaporator to provide refrigeration capacity, and finally flows through the low-pressure side of the heat exchanger 5 back to the compression unit. The high-pressure gas is further cooled by the returning low-pressure side gas when it flows through the heat exchanger 5.

[0033] The precooling temperature of the precooler 1 can be lower than the maximum conversion temperature of the throttling working fluid. Compared with the existing technology, the bypass valve is eliminated, the structure is simplified, and the reliability is improved.

[0034] In addition, installing a heat exchanger 5 before the throttling valve 6 can accelerate cooling and make full use of the low-temperature cold energy returning after throttling.

[0035] In a feasible embodiment of the present invention, the compression unit includes a cylinder 8, a piston 9, an intake valve 10, and an exhaust valve 11. The cylinder 8 provides space for compression and throttling during the linear reciprocating motion of the piston 9. The piston 9 is slidably disposed within the cylinder 8 and is connected to a linear drive mechanism 3. Under the action of the linear drive mechanism 3, the piston 9 can achieve reciprocating motion. The intake valve 10 and the exhaust valve 11 are disposed at the front end of the cylinder 8, which can be understood as the end away from the linear drive mechanism 3. The intake valve 10 and the exhaust valve 11 alternately open and close based on the gas pressure difference between the cylinder 8 and the inlet and outlet pipelines, realizing unidirectional gas flow. The exhaust valve 11 is connected to the throttle valve 6, and the intake valve 10 is connected to the other end of the evaporator 7.

[0036] In a feasible embodiment of the present invention, the compression unit further includes a piston rod 12, which connects the piston 9 and the linear drive mechanism 3 to achieve a rigid connection between the piston 9 and the linear drive mechanism 3. The piston rod 12 can be made of a material with low thermal conductivity and high rigidity, such as ceramic or polyetheretherketone (PEEK). Using a material with low thermal conductivity and high rigidity, the piston rod 12 can reduce heat loss at the cold end while also possessing a high ability to transmit axial alternating forces.

[0037] In a feasible embodiment of the present invention, the compression unit further includes a bellows 13. One end of the bellows 13 is sealed to the piston rod 12 and reciprocates with the piston rod 12. The other end of the bellows 13 is sealed to the cylinder 8 to ensure that the gaseous working fluid does not leak into the vacuum chamber 4. The bellows 13 is welded and sealed using a folded metal sheet, is expandable, can withstand certain gas pressures, and possesses good toughness and fatigue resistance at low temperatures. The bellows 13 isolates the throttling working fluid from the linear drive mechanism 3 to prevent heat loss caused by the low-temperature throttling working fluid shuttling between the room-temperature linear drive mechanism 3.

[0038] In a feasible embodiment of the present invention, the linear drive mechanism 3 and the compression unit are used in pairs, arranged back-to-back in a straight line. Taking the linear drive mechanism 3 as a linear motor as an example, the two linear motors are driven by the same voltage and move in opposite directions, reducing vibration caused by the movement.

[0039] In a feasible embodiment of the present invention, the heat exchanger 5 can be a set, and the heat exchanger 5 adopts a coaxial spiral sleeve structure. By utilizing the flow of hot and cold gases, the cooling can be accelerated, and the low-temperature cold energy returned after throttling can be fully utilized.

[0040] In one feasible embodiment of the present invention, the precooling machine 1 includes one of a GM type refrigerator, a Stirling type refrigerator, or a pulse tube refrigerator.

[0041] In a feasible embodiment of the present invention, the evaporator 7 is a slit-type, spiral tube-type, needle-rib type, or porous-filled evaporator.

[0042] In a feasible embodiment of the present invention, the vacuum cover 4 adopts an internal multi-layer shell structure, which serves to provide vacuum insulation and shield thermal radiation. Except for the linear drive mechanism 3, the cold head 2, the compression unit, the heat exchanger 5, the throttling valve 6 and the evaporator 7 are all arranged inside the vacuum cover 4.

[0043] In a feasible embodiment of the present invention, the linear drive mechanism 3 is disposed in a normal temperature and pressure environment, and the heat generated is dissipated by air cooling or water cooling.

[0044] Therefore, the pre-cooled JT throttling refrigerator provided by the present invention improves the output performance of the compression unit by arranging the compression unit at the low temperature of the vacuum chamber 4, thereby improving the system efficiency of the refrigerator. At the same time, the compression unit has the advantages of miniaturization and high reliability.

[0045] Since the linear drive mechanism 3 is arranged in a normal temperature environment, the Joule heat of the linear drive mechanism 3 will not be carried into the throttling refrigeration cycle, thereby improving the system efficiency of the refrigeration machine.

[0046] Because the compression unit is directly coupled to the cold head 2, the multi-stage heat exchanger is eliminated, the system structure is simplified, and the system efficiency of the refrigeration unit is improved.

[0047] Compared to existing technologies, the elimination of the bypass valve accelerates the throttling cooling speed, simplifies the structure, and improves reliability.

[0048] In summary, the pre-cooling JT throttling refrigerator provided by this invention has the characteristics of fast cooling speed, high cooling capacity, simple system structure, high reliability, and high system efficiency.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pre-cooling type JT throttling refrigerator, characterized in that, The pre-cooling machine (1) has a cold head (2); A linear drive mechanism (3); A compression unit connected with the linear drive mechanism (3), which outputs high-pressure gas working medium under the action of the linear drive mechanism (3); A vacuum cover (4) for providing vacuum heat insulation; the compression unit is coupled with the cold head (2) and both are located in the vacuum cover (4); A heat exchanger (5) for pre-cooling high-pressure gas using backflow cold gas; A throttle valve (6) penetrating through the heat exchanger (5) and communicating with the high-pressure end of the compression unit; An evaporator (7) connected with the throttle valve (6) at one end and penetrating through the heat exchanger (5) and connected with the low-pressure end of the compression unit at the other end. The compression unit comprises:

2. The pre-cooled JT throttle cryocooler of claim 1, wherein A cylinder (8) and a piston (9), the cylinder (8) provides a space for compressing throttling working medium in the linear reciprocating motion of the piston (9); the piston (9) is slidingly arranged in the cylinder (8), and the piston (9) is connected with the linear drive mechanism (3) to realize reciprocating motion; An intake valve (10) and an exhaust valve (11) arranged on the cylinder (8) and alternately opened and closed based on the gas pressure difference between the cylinder (8) and the gas inlet and outlet pipeline to realize one-way flow of gas working; wherein the exhaust valve (11) is connected with the throttle valve (6), and the intake valve (10) is connected with the other end of the evaporator (7). The compression unit further comprises:

3. The pre-cooled JT throttle cryocooler of claim 2, wherein, A piston rod (12) for connecting the piston (9) and the linear drive mechanism (3). The compression unit further comprises:

4. The pre-cooled JT throttle cryocooler of claim 3, wherein A bellows (13) having one end sealingly connected with the piston rod (12) and reciprocating with the bellows (13), and the other end sealingly connected with the cylinder (8). The linear drive mechanism (3) and the compression unit are used in pairs in a back-to-back linear arrangement.

5. The pre-cooled JT throttle cryocooler according to any one of claims 1 to 4, characterized in that, The heat exchanger (5) adopts a coaxial spiral sleeve structure.

6. The pre-cooled JT throttle cryocooler of any one of claims 1-4, wherein, The pre-cooling machine (1) comprises one of a GM-type refrigerator, a Stirling-type refrigerator or a pulse tube refrigerator.

7. The pre-cooled JT throttle cryocooler of any one of claims 1-4, wherein, The throttle valve (6) is provided as a metal plate with a small hole structure, and the gas working medium expands to produce a refrigeration effect through the small hole.

8. The pre-cooled JT throttle cryocooler of any one of claims 1-4, wherein, The vacuum cover (4) adopts an internal multi-layer shell structure.

9. The pre-cooled JT throttle cryocooler of any one of claims 1-4, wherein, The linear drive mechanism (3) is arranged in a normal temperature and pressure environment, and the generated heat is dissipated by air cooling or water cooling.

10. The pre-cooled JT throttle cryocooler of any one of claims 1-4, wherein, ​

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