Pre-cooling type JT throttling refrigerating machine

Abstract

The utility model relates to the technical field of mechanical refrigeration, and provides a pre-cooling type JT throttling refrigerating machine which comprises a pre-cooler provided 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. According to the utility model, the compression unit for driving the throttling working medium is placed in the vacuum cover at a low temperature, so that the output performance of the compression unit is improved, and the system efficiency of the refrigerator 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] The utility model relates to the technical field of mechanical refrigeration, in particular to a precooling type JT throttling refrigerator. Background Art

[0002] With the continuous development of space exploration and ground refrigeration technology, the demand for cold environments in the liquid helium temperature zone and even the superfluid helium temperature zone is becoming more and more widespread. Especially in the field of space exploration, the liquid helium to superfluid helium temperature zone is not only the working temperature zone of some key detectors (such as superconducting quantum interference devices (SQUIDs), superconducting photon detectors (SNSPDs), and superconducting terahertz detectors), but also the pre-cooling temperature zone of refrigerators in lower temperature zones (such as adsorption refrigerators, dilution refrigerators, and adiabatic demagnetization refrigerators). Compared with other space refrigerators, the pre-cooling JT throttling refrigerator in the liquid helium to superfluid helium temperature zone has the characteristics of no moving parts in the cold head, long-distance transmission of cold, low vibration and electromagnetic interference, and high efficiency in the liquid helium temperature zone, making it a common choice for mechanical refrigerators in this temperature zone.

[0003] like Figure 1 As shown, it is a liquid helium temperature zone precooling refrigerator in the prior art, which is precooled by a two-stage precooler A01. The helium working fluid is compressed by the compressor to form high-pressure gas. The high-pressure side gas is cooled by the refluxed low-pressure side gas when flowing through the three-stage countercurrent partition heat exchangers A09, A10, and A11. When flowing through the two-stage precooling heat exchangers A12 and A13, it is cooled to the corresponding precooling temperature by the precooler cold heads A14 and A15, and then cooled by the throttle valve A17 to produce a refrigeration effect and drop to low pressure. The low-pressure gas absorbs the heat load through the cold head heat exchanger A18 to provide cooling capacity, and finally flows through the low-pressure side of the three-stage countercurrent partition heat exchangers A11, A10, and A09 in sequence to return to the compressor.

[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 in the cylinder A04, and the one-way flow of gas is formed by the alternating opening and closing of the intake valve plate A06 and the exhaust valve plate A07. Since the compressor is in a room temperature environment, the cold head of the precooler and the heat exchanger of the JT throttling refrigerator are in a vacuum low temperature environment and are installed inside the vacuum cover A08. The compressor is connected to the JT throttling component through a pipeline, and the efficiency of the compressor is low.

[0005] In addition, the cooling rate of the JT throttling refrigerator in the liquid helium temperature zone is slow after startup. The main reason is that the maximum conversion temperature of the helium working fluid is lower than the ambient temperature. At the initial stage of cooling, the intermediate wall heat exchangers and the cold end heat exchangers are still at room temperature. The low-temperature working fluid entering the high-pressure side of the heat exchanger A11 after precooling will be heated by the high-temperature working fluid on the low-pressure side, and the cold capacity is difficult to transfer to the throttle valve A17 and the evaporator A18. In order to achieve rapid cooling, a bypass valve A16 is generally set near the cold head of the JT throttling refrigerator. However, the introduction of the bypass valve requires a corresponding control system, which increases the complexity and unreliability of the system. Utility Model Content

[0006] The utility model provides a precooling type JT throttling refrigerator, which is used to solve the defect of low compression efficiency in the prior art and improve the output performance of the compression unit.

[0007] The utility model provides a precooling type JT throttling refrigerator, comprising:

[0008] A precooler having a cold head;

[0009] Linear drive mechanism;

[0010] A compression unit connected to the linear drive mechanism, wherein the compression unit outputs high-pressure gas working medium under the action of the linear drive mechanism;

[0011] A vacuum cover is used to provide vacuum insulation; the compression unit is coupled to the cold head and both are located in the vacuum cover;

[0012] A heat exchanger for precooling the high pressure incoming gas using the return cold gas;

[0013] a throttle valve, which passes through the heat exchanger and is in communication with the high-pressure end of the compression unit;

[0014] The evaporator has one end connected to the throttle valve and the other end passing through the heat exchanger and connected to the low-pressure end of the compression unit.

[0015] According to a precooling type JT throttling refrigerator provided by the utility model, the compression unit comprises:

[0016] A cylinder and a piston; the cylinder provides a space for compressing and throttling a working medium during the linear reciprocating motion of the piston; the piston is slidably disposed in the cylinder, and the piston is connected to the linear drive mechanism to achieve reciprocating motion;

[0017] The intake valve and the exhaust valve are arranged on the cylinder, and are alternately opened and closed based on the gas pressure difference between the cylinder and the inlet and outlet pipelines to realize the unidirectional flow of gas; wherein, the exhaust valve is connected to the throttle valve, and the intake valve is connected to the other end of the evaporator.

[0018] According to a precooling type JT throttling refrigerator provided by the utility model, the compression unit also includes:

[0019] A piston rod is used to connect the piston and the linear drive mechanism.

[0020] According to a precooling type JT throttling refrigerator provided by the utility model, the compression unit also includes:

[0021] A bellows, one end of which is sealed and connected to the piston rod and reciprocates with the bellows, and the other end of which is sealed and connected to the cylinder.

[0022] According to a precooling type JT throttling refrigerator provided by the utility model, the linear drive mechanism and the compression unit are used in pairs, and are arranged in a back-to-back linear manner.

[0023] According to a precooling type JT throttling refrigerator provided by the utility model, the heat exchanger adopts a coaxial spiral sleeve structure.

[0024] According to a precooling type JT throttling refrigerator provided by the utility model, the precooling machine includes one of a GM refrigerator, a Stirling refrigerator or a pulse tube refrigerator.

[0025] According to a pre-cooling type JT throttling refrigerator provided by the utility model, the throttling valve is arranged as a metal plate with small holes, and the gas working medium expands through the small holes to produce a refrigeration effect.

[0026] According to a precooling type JT throttling refrigerator provided by the utility model, the vacuum cover adopts an internal multi-layer shell structure.

[0027] According to a pre-cooling JT throttling refrigerator provided by the utility model, the linear drive mechanism is arranged in a normal temperature and pressure environment, and the generated heat is dissipated through air cooling or water cooling.

[0028] The pre-cooling JT throttling refrigerator provided by the utility model improves the output performance of the compression unit by placing the compression unit driving the throttling working medium in a vacuum cover at a low temperature, thereby improving the system efficiency of the refrigerator, and the compression unit has the advantages of miniaturization and high reliability; in addition, the compression unit is directly coupled to the cold head, and compared with the prior art, the multi-stage heat exchanger is removed, the system structure is simplified, and the efficiency of the refrigeration system is improved; at the same time, the linear drive mechanism is arranged under normal temperature environment, and the Joule heat of the linear drive mechanism will not be brought into the throttling refrigeration cycle, thereby improving the system efficiency of the refrigerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a structural schematic diagram of a precooling throttling refrigerator in the prior art.

[0031] Figure 2 It is a structural schematic diagram of a precooling type JT throttling refrigerator provided by the utility model.

[0032] Reference numerals:

[0033] 1. Precooler; 2. Cold head; 3. Linear drive mechanism; 4. Vacuum cover; 5. Heat exchanger; 6. Throttle valve; 7. Evaporator; 8. Cylinder; 9. Piston; 10. Inlet valve; 11. Exhaust valve; 12. Piston rod; 13. Bellows. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] Combine the following Figure 2 The utility model is described as a precooling type JT throttling refrigerator.

[0036] The embodiment of the utility model provides a precooling type JT throttling refrigerator, comprising a precooling machine 1, a cold head 2, a linear drive mechanism 3, a compression unit, a vacuum cover 4, a heat exchanger 5, a throttling valve 6 and an evaporator 7.

[0037] The precooler 1 has a cold head 2. The precooler can be a small low-temperature refrigerator such as a GM refrigerator, a Stirling refrigerator or a pulse tube refrigerator. The interior of the precooler 1 is filled with a throttling gas working medium of appropriate pressure. The precooler 1 generally adopts a two-stage cold head or a multi-stage cold head refrigeration method. The embodiment shows a two-stage cold head 2, including a primary cold head and a secondary cold head. The primary cold head and the secondary cold head are both installed inside the vacuum cover 4.

[0038] The linear drive mechanism 3 can provide power for linear motion, and the linear drive mechanism 3 can adopt a linear motor, which can reciprocate linearly after applying an AC voltage. In addition, the linear drive mechanism 3 can also adopt other structures such as a cylinder or an electric cylinder to achieve linear motion.

[0039] The compression unit is connected to the linear drive mechanism 3 , and the compression unit outputs high-pressure gas working medium under the action of the linear drive mechanism 3 .

[0040] The vacuum cover 4 is used to provide vacuum insulation; the compression unit is coupled to the cold head 2 and both are located in the vacuum cover 4; the compression unit is arranged in a low-temperature vacuum environment, which improves the output performance of the compression unit. It is directly coupled to the cold head 2, and the cold head 2 directly cools the compression unit and the throttling medium, removing the multi-stage heat exchanger, simplifying the system structure, and improving the efficiency of the JT throttling refrigerator.

[0041] The heat exchanger 5 is used to precool the high-pressure incoming gas using the reflux cold gas, and the high-pressure gas pipeline of the heat exchanger 5 is connected to the air inlet end of the throttle valve 6 .

[0042] 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 produce a refrigeration effect.

[0043] 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 the heat of the target load.

[0044] The refrigeration process of the precooling JT throttling refrigerator provided by the utility model is as follows: first, a throttling gas working medium of appropriate pressure is filled into the precooling machine, and the compression unit is started to cool the gas working medium and precool it; the linear drive mechanism 3 is started, and the gas is compressed by the throttling compression unit to form high-pressure gas, which is discharged to the throttle valve 6. The throttle valve 6 cools down to produce a refrigeration effect and drops to a low pressure. The low-pressure gas absorbs the heat load through the evaporator to provide refrigeration capacity, and finally flows through the low-pressure side of the heat exchanger 5 to return to the compression unit. Among them, the high-pressure gas is further cooled by the refluxed low-pressure side gas when flowing through the heat exchanger 5.

[0045] The precooling temperature of the precooler 1 can be lower than the maximum conversion temperature of the throttling medium. Compared with the prior art, the bypass valve is removed, the structure is simplified, and the reliability is improved.

[0046] In addition, a heat exchanger 5 is provided before the throttle valve 6 to accelerate the cooling and make full use of the low-temperature cooling capacity of the return flow after throttling.

[0047] In a feasible embodiment of the utility model, the compression unit includes a cylinder 8, a piston 9, an intake valve 10 and an exhaust valve 11. The cylinder 8 is used to provide a space for compression and throttling work in the linear reciprocating motion of the piston 9. The piston 9 is slidably arranged in the cylinder 8, and the piston 9 is connected to the linear drive mechanism 3. The piston 9 can realize reciprocating motion under the action of the linear drive mechanism 3. The intake valve 10 and the exhaust valve 11 are arranged at the front end of the cylinder 8. The front end can be understood as an end away from the linear drive mechanism 3. The intake valve 10 and the exhaust valve 11 are alternately opened and closed based on the gas pressure difference between the cylinder 8 and the inlet and outlet pipelines to realize the unidirectional flow of gas. Among them, 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.

[0048] In a feasible embodiment of the present invention, the compression unit further includes a piston rod 12, which is used to connect the piston 9 and the linear drive mechanism 3 to achieve a rigid connection between the piston 9 and the linear drive mechanism 3, wherein the piston rod 12 can be made of a material with low thermal conductivity and high rigidity, such as ceramics and polyetheretherketone (PEEK for short). The piston rod 12 is made of a material with low thermal conductivity and high rigidity, which can reduce the heat loss at the cold end while having a high ability to transmit axial alternating force.

[0049] In a feasible embodiment of the utility model, the compression unit also includes a bellows 13, one end of the bellows 13 is sealed and connected to the piston rod 12, and reciprocates with the bellows 13, and the other end of the bellows 13 is sealed and connected to the cylinder 8 to ensure that the gas working medium will not leak into the vacuum cover 4. Among them, the bellows 13 is welded and sealed in the form of folded metal sheets, which is retractable, can withstand a certain gas pressure, and has good toughness and good fatigue resistance at low temperatures. The throttling working medium is isolated from the linear drive mechanism 3 by the bellows 13 to prevent the low-temperature throttling working medium from shuttling between the normal temperature linear drive mechanism 3 and causing heat loss.

[0050] In a feasible embodiment of the utility model, the linear drive mechanism 3 and the compression unit are used in pairs, and are 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 to reduce vibration caused by movement.

[0051] In a feasible embodiment of the utility model, the heat exchanger 5 can be a group, and the heat exchanger 5 adopts a coaxial spiral sleeve structure, and the reverse flow of cold and hot gases can be used to accelerate the cooling and make full use of the low-temperature cooling capacity of the reflux after throttling.

[0052] In a feasible embodiment of the present invention, the precooler 1 includes a GM refrigerator, a Stirling refrigerator or a pulse tube refrigerator.

[0053] In a feasible embodiment of the present invention, the evaporator 7 is a slit type, spiral tube type, pin-fin type or porous filling type evaporator.

[0054] In a feasible embodiment of the present utility model, the vacuum cover 4 adopts an internal multi-layer shell structure to play the role of vacuum insulation and shielding thermal radiation. In addition to the linear drive mechanism 3, the cold head 2, compression unit, heat exchanger 5, throttle valve 6 and evaporator 7 are all arranged in the vacuum cover 4.

[0055] In a feasible embodiment of the present invention, 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.

[0056] Therefore, the precooling JT throttling refrigerator provided by the utility model improves the output performance of the compression unit because the compression unit is arranged at the low temperature of the vacuum cover 4, thereby improving the system efficiency of the refrigerator. At the same time, the compression unit has the advantages of miniaturization and high reliability.

[0057] 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 brought into the throttling refrigeration cycle, thereby improving the system efficiency of the refrigerator.

[0058] Since the compression unit is directly coupled to the cold head 2, the multi-stage heat exchanger is removed, the system structure is simplified, and the system efficiency of the refrigerator is improved.

[0059] Compared with the prior art, the bypass valve is removed, so the throttling refrigeration speed is accelerated, the structure is simplified, and the reliability is improved.

[0060] In summary, the precooling JT throttling refrigerator provided by the utility model has the characteristics of fast cooling speed, high cooling capacity, simple system structure, high reliability and high system efficiency.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A precooling type JT throttling refrigerator, characterized in that: include: A precooler (1) having a cold head (2); Linear drive mechanism (3); A compression unit connected to the linear drive mechanism (3), wherein the compression unit outputs high-pressure gas working medium under the action of the linear drive mechanism (3); A vacuum cover (4) is used to provide a vacuum heat insulation function; the compression unit is coupled to the cold head (2) and both are located in the vacuum cover (4); A heat exchanger (5) for precooling the high pressure incoming gas using the return cold gas; a throttle valve (6) passing through the heat exchanger (5) and communicating with the high-pressure end of the compression unit; An evaporator (7) has one end connected to the throttle valve (6) and the other end passing through the heat exchanger (5) and connected to the low-pressure end of the compression unit.

2. The precooling type JT throttling refrigerator according to claim 1, characterized in that: The compression unit comprises: A cylinder (8) and a piston (9), wherein the cylinder (8) provides a space for compressing and throttling a working medium during the linear reciprocating motion of the piston (9); the piston (9) is slidably disposed in the cylinder (8), and the piston (9) is connected to the linear drive mechanism (3) to achieve reciprocating motion; An intake valve (10) and an exhaust valve (11) are arranged on the cylinder (8), and are alternately opened and closed based on the gas pressure difference between the cylinder (8) and the inlet and outlet gas pipelines, so as to realize a one-way flow of gas; wherein 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).

3. The precooling type JT throttling refrigerator according to claim 2, characterized in that: The compression unit further comprises: A piston rod (12) is used to connect the piston (9) and the linear drive mechanism (3).

4. The precooling type JT throttling refrigerator according to claim 3, characterized in that: The compression unit further comprises: A bellows (13), one end of which is sealedly connected to the piston rod (12) and reciprocates with the bellows (13), and the other end of which is sealedly connected to the cylinder (8).

5. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The linear drive mechanism (3) and the compression unit are used in pairs and are arranged in a back-to-back linear manner.

6. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The heat exchanger (5) adopts a coaxial spiral casing structure.

7. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The precooler (1) comprises a GM refrigerator, a Stirling refrigerator or a pulse tube refrigerator.

8. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The throttle valve (6) is configured as a metal plate with a small hole structure, and the gas working medium expands through the small hole to produce a refrigeration effect.

9. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The vacuum cover (4) adopts an internal multi-layer shell structure.

10. The precooling type JT throttling refrigerator according to any one of claims 1 to 4, characterized in that: The linear drive mechanism (3) is arranged in a normal temperature and pressure environment, and the generated heat is dissipated through air cooling or water cooling.

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