CN107940790B - Mixed circulation low-temperature refrigerator - Google Patents
Mixed circulation low-temperature refrigerator Download PDFInfo
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- CN107940790B CN107940790B CN201711346463.3A CN201711346463A CN107940790B CN 107940790 B CN107940790 B CN 107940790B CN 201711346463 A CN201711346463 A CN 201711346463A CN 107940790 B CN107940790 B CN 107940790B
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- 238000005057 refrigeration Methods 0.000 claims abstract description 32
- 230000006835 compression Effects 0.000 claims abstract description 24
- 238000007906 compression Methods 0.000 claims abstract description 24
- 238000004891 communication Methods 0.000 claims description 4
- 239000007789 gas Substances 0.000 abstract description 47
- 239000001307 helium Substances 0.000 abstract description 21
- 229910052734 helium Inorganic materials 0.000 abstract description 21
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 abstract description 21
- 239000007788 liquid Substances 0.000 abstract description 21
- 230000008901 benefit Effects 0.000 abstract description 11
- 230000000737 periodic effect Effects 0.000 abstract description 8
- 239000001257 hydrogen Substances 0.000 abstract description 7
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 5
- 238000001816 cooling Methods 0.000 abstract description 4
- 238000010521 absorption reaction Methods 0.000 abstract 2
- 230000001172 regenerating effect Effects 0.000 description 15
- 230000009471 action Effects 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 238000013459 approach Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 235000014347 soups Nutrition 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/02—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using Joule-Thompson effect; using vortex effect
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/10—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point with several cooling stages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
- F25B9/145—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle pulse-tube cycle
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
- Compressor (AREA)
Abstract
The invention relates to the technical field of low-temperature refrigeration, in particular to a mixed-cycle low-temperature refrigerator which comprises a gas compression unit and a first refrigeration unit connected with the gas compression unit of a first gas absorption valve, wherein a second refrigeration unit is arranged on the first refrigeration unit of the first gas absorption valve in parallel. The invention utilizes a Stirling refrigerator or a Stirling type pulse tube refrigerator to pre-cool a JT throttling refrigerator, adopts a single oil-free linear compressor to generate periodic reciprocating pressure fluctuation, and combines a one-way valve to generate high-pressure and low-pressure gas. Wherein the cyclically reciprocating pressure fluctuations are used to drive a multi-stage stirling cooler; the single compressor is adopted to simultaneously generate periodic alternating flow and high-low pressure driven unidirectional flow, and the advantages of high efficiency and high power density of the Stirling cycle in a temperature region above liquid hydrogen are utilized to exert the high efficiency, large cooling capacity, high reliability and no moving part of the helium throttling refrigerating machine in the liquid helium temperature region, so that the high-efficiency compact low-temperature refrigerating machine without the moving part, which operates in the liquid helium temperature region, is formed.
Description
Technical Field
The invention relates to the technical field of low-temperature refrigeration, in particular to a mixed-cycle low-temperature refrigerator.
Background
At present, a cryogenic refrigerator working in a liquid helium temperature region has wide application requirements in the fields of superconducting electronics, cryophysics, outer space exploration, quantum communication and the like, particularly for superconducting materials, the working temperature region of the cryogenic refrigerator is generally positioned in the liquid helium temperature region, and the development of the efficient and reliable cryogenic refrigerator has important significance for promoting scientific progress and development of related industries. At present, in the temperature region, widely used technologies comprise a GM refrigerator and a GM type pulse tube refrigerator.
GM refrigerator and GM type pulse tube refrigerator, it adopts oil compressor to compress helium, store in the high-pressure cavity, and the low-pressure gas of suction side stores in the low-pressure cavity; the high-low pressure cavity is connected with the rotary valve through the oil filter, the rotary valve moves periodically, the high-pressure gas and the low-pressure gas are switched in a channel to generate compression and expansion effects, the regenerative low-temperature refrigerator is driven, and the operation period of the regenerative low-temperature refrigerator is about 1 Hz. In the regenerative low-temperature refrigerator, the effect of the refrigerator is generated by the compression expansion and the phase modulation of an ejector (or a phase modulation mechanism in a pulse tube refrigerator), and the lowest temperature can reach 2K. In particular, the method has low cost and relatively high efficiency and is widely applied to a liquid helium temperature zone.
For the GM refrigerator, because the rotary valve structure is adopted for switching high pressure and low pressure, great pressure drop loss can be generated when gas flows through, irreversible loss which is difficult to avoid is caused, and the energy conversion efficiency is difficult to further improve; the oil compressor is used for generating high-pressure and low-pressure gas, equipment such as an oil separator and the like needs to be arranged, the system is large in size, regular maintenance is needed, and the service life is difficult to guarantee; the phase of the ejector is adjusted, so that large vibration is caused at a cold head part, and the application occasions of the cold head part are limited. The GM type pulse tube refrigerator adopts a pulse tube plus phase modulation mechanism to replace an ejector at the side of a refrigerator, a cold end has no moving part, and cold end vibration can be effectively reduced.
The multi-stage Stirling refrigerator or the multi-stage pulse tube refrigerator driven by the linear compressor compresses and expands helium in a system by utilizing the reciprocating motion of an oil-free linear piston to form periodic pressure fluctuation, and meanwhile, the ejector running at low temperature is utilized to adjust the sound field distribution of the whole refrigerator to generate a refrigeration effect in the heat regenerator, so that the refrigerator or the multi-stage pulse tube refrigerator is essentially reversible Stirling cycle and has higher theoretical efficiency. However, because of its high operating frequency, the heat exchange and flow losses in the regenerator are large at low temperatures, and although higher efficiency can be obtained in the temperature region above the liquid hydrogen, the operating temperature region is difficult to further decrease. The Stirling type pulse tube refrigerator has the advantages that the operation principle and the basic framework are similar to those of the Stirling refrigerator, compared with the Stirling refrigerator, the ejector structure is removed, the pulse tube structure is adopted to isolate the cold end from the room temperature environment, the resistance element is utilized at the hot end of the pulse tube to adjust the acoustic impedance distribution in the heat regenerator, so that the refrigerator has no moving part at the cold end, and the Stirling type pulse tube refrigerator has the advantages of simple structure, small vibration, high reliability, long service life, low cost and the like.
The coke soup throttling refrigerator (JT refrigerator) utilizes the throttling effect of fluid to generate a refrigeration effect, utilizes a compressor to compress gas, dissipates heat in a condenser, throttles and reduces the pressure to a low temperature after cooling, absorbs heat in an evaporator, generates refrigerating capacity, evaporates and then enters the compressor to form a closed cycle. Its advantage lies in utilizing the latent heat transfer, and the refrigerating output is big, and heat exchange efficiency is high to the cold junction does not have moving part, and cooling rate is fast. But has the disadvantages of being limited by the physical properties of the working medium and limited working temperature zone. In the vicinity of the liquid helium temperature, the gas is in a liquid or even solid state, except for helium. However, the transition temperature of the throttling effect of helium is below 30K, and the refrigeration effect can be obtained only by precooling the temperature below the temperature zone.
Disclosure of Invention
Technical problem to be solved
The invention aims to provide a mixed circulation low-temperature refrigerating machine, and aims to solve the problems of large volume, complex structure, low reliability and low refrigerating efficiency of a refrigerating system in the prior art.
(II) technical scheme
In order to solve the technical problem, the invention provides a mixed cycle cryogenic refrigerator, which comprises a gas compression unit and a first refrigeration unit connected with the gas compression unit, wherein a second refrigeration unit is arranged on the first refrigeration unit in parallel; the first refrigeration unit comprises a multi-stage cold head, the second refrigeration unit comprises a multi-stage heat exchanger, and the cold head and the heat exchanger are arranged at intervals.
The gas compression unit is a gas compressor, the gas compressor comprises a compressor shell and a compressor cylinder arranged in the compressor shell, and the inner wall of the compressor cylinder is in a step shape.
Wherein the inner diameter of the middle part of the compressor cylinder is larger than the inner diameter of the two end parts of the compressor cylinder.
The gas compressor further comprises a first compressor rotor piston and a second compressor rotor piston, the first compressor rotor piston and the second compressor rotor piston are step-shaped pistons matched with the inner wall of the compressor cylinder in shape, and the first compressor rotor piston and the second compressor rotor piston are respectively matched with two ends of the compressor cylinder.
The compressor comprises a compressor cylinder, a compressor shell, a rotor magnet, a coil and a rotor magnet, wherein the coil and the rotor magnet are arranged between the compressor shell and the compressor cylinder, the coil is arranged on the inner side of the compressor shell, the rotor magnet is arranged on the outer side of the compressor cylinder, and the coil and the rotor magnet are arranged oppositely.
The first refrigeration unit comprises a room temperature end heat exchanger, a first-stage cold head and a second-stage cold head which are sequentially connected, and the room temperature end heat exchanger is communicated with a compression cavity formed by the first compressor rotor piston, the second compressor rotor piston and the compressor cylinder.
The phase modulation component is connected to one end, far away from the first-stage cold head and the second-stage cold head, of the room-temperature-end heat exchanger.
The second refrigeration unit comprises a throttling valve, a cold end heat exchanger and a multi-stage regenerative heat exchanger which are sequentially connected, the regenerative heat exchanger is communicated with a first direct-current cavity formed by the second compressor rotor piston and the compressor cylinder, and the throttling valve is communicated with a second direct-current cavity formed by the first compressor rotor piston and the compressor cylinder; and valve bodies are arranged in the first direct current cavity and the second direct current cavity.
The valve body comprises a first air suction valve, a first exhaust valve, a second air suction valve and a second exhaust valve, the first air suction valve and the first exhaust valve are located in the first direct-current cavity, and the second air suction valve and the second exhaust valve are located in the second direct-current cavity; the first direct current cavity and the second direct current cavity are communicated through a direct current pipeline.
The valve body comprises a valve plate and a supporting spring, and the valve plate is fixed on the compressor cylinder through the supporting spring.
(III) advantageous effects
compared with the prior art, the technical scheme of the invention has the following beneficial effects: according to the mixed circulation low-temperature refrigerating machine provided by the invention, the first refrigerating unit and the second refrigerating unit are integrated, so that the refrigerating system is reduced in size, high in reliability and greatly improved in refrigerating efficiency.
The invention utilizes a Stirling refrigerator or a Stirling type pulse tube refrigerator to pre-cool a JT throttling refrigerator, adopts a single oil-free linear compressor to generate periodic reciprocating pressure fluctuation, and is combined with a one-way valve to generate high-pressure and low-pressure gas. The working temperature region of the periodic reciprocating pressure fluctuation is positioned in the liquid hydrogen temperature region to pre-cool the high-pressure helium, and the high-pressure and low-pressure gas is used for driving the JT throttling refrigerating machine to generate refrigerating capacity in the helium temperature region; the low-temperature refrigerating machine has the advantages that the single compressor is adopted to simultaneously generate periodic alternating flow and high-low pressure driven one-way flow, the advantages of high efficiency and high power density of the Stirling cycle in a temperature region above liquid hydrogen are fully utilized, and the advantages of high efficiency, large cooling capacity, high reliability and no moving part of the helium throttling refrigerating machine in the liquid helium temperature region are simultaneously exerted, so that the high-efficiency compact low-temperature refrigerating machine without the moving part, which runs in the liquid helium temperature region, is formed.
Drawings
FIG. 1 is a side sectional view of a hybrid cycle cryocooler according to an embodiment of the present invention;
FIG. 2 is a schematic view of a second inhalation valve shown in FIG. 1;
FIG. 3 is a schematic structural view of a second exhaust valve shown in FIG. 1;
Wherein, 1-compressor shell; 2-compressor cylinder; 3-a first compressor mover piston; 4-a second compressor mover piston; 5-a first air suction valve; 6-a first exhaust valve; 7-a second suction valve; 8-a second exhaust valve; 9-a compression chamber; 10-a first direct current cavity; 11-a second direct current cavity; 12-a direct flow line; 13-a first mover magnet; 14-a second mover magnet; 15-a first coil; 16-a second coil; 17-an air suction pipe; 18-an exhaust pipe; 19-a connecting tube; 20-a phase modulation component; 21-room temperature end heat exchanger; 22-first stage cold head; 23-second stage cold head; 24-a first stage regenerative heat exchanger; 25-a second-stage regenerative heat exchanger; 26-a third-stage regenerative heat exchanger; 27-a throttle valve; 28-cold side heat exchanger; 29-valve plate; 30-a support spring; 31-valve body cavity.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the present invention, "a plurality" means two or more unless otherwise specified; "notched" means, unless otherwise stated, a shape other than a flat cross-section. The terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present invention can be understood as appropriate by those of ordinary skill in the art.
Referring to fig. 1 to 3, the present invention provides a mixed cycle cryocooler, which includes a gas compression unit and a first refrigeration unit connected to the gas compression unit, wherein the first refrigeration unit is provided with a second refrigeration unit in parallel; the first refrigeration unit comprises a multistage cold head, the second refrigeration unit comprises a multistage heat exchanger, and the cold head and the heat exchanger are arranged at intervals.
According to the mixed circulation low-temperature refrigerating machine provided by the invention, the first refrigerating unit and the second refrigerating unit are integrated, so that the refrigerating system is reduced in size, high in reliability and greatly improved in refrigerating efficiency.
Further, the gas compression unit is a gas compressor, the gas compressor comprises a compressor shell 1 and a compressor cylinder 2 arranged inside the compressor shell 1, and the inner wall of the compressor cylinder 2 is in a step shape.
Further, the inner diameter of the middle portion of the compressor cylinder 2 is larger than the inner diameter of the end portions of the compressor cylinder 2.
Further, the gas compressor further comprises a first compressor rotor piston 3 and a second compressor rotor piston 4, the first compressor rotor piston 3 and the second compressor rotor piston 4 are both stepped pistons matched with the inner wall of the compressor cylinder 2 in shape, and the first compressor rotor piston 3 and the second compressor rotor piston 4 are respectively matched with two ends of the compressor cylinder 2.
Further, a coil and a mover magnet are arranged between the compressor housing 1 and the compressor cylinder 2, the coil is arranged inside the compressor housing 1, the mover magnet is arranged outside the compressor cylinder 2, and the coil and the mover magnet are arranged opposite to each other.
Further, the first refrigeration unit comprises a room temperature end heat exchanger 21, a first stage cold head 22 and a second stage cold head 23 which are connected in sequence, and the room temperature end heat exchanger 21 is communicated with a compression cavity 9 formed by the first compressor rotor piston 3, the second compressor rotor piston 4 and the compressor cylinder 2.
Further, a phase modulation component 20 is arranged between the room temperature end heat exchanger 21 and the gas compression unit, and the phase modulation component 20 is connected to one end of the room temperature end heat exchanger 21, which is far away from the first stage cold head 22 and the second stage cold head 23.
Further, the second refrigeration unit comprises a throttle valve 27, a cold end heat exchanger 28 and a multi-stage regenerative heat exchanger which are sequentially connected, the regenerative heat exchanger is communicated with a first direct-current cavity 10 formed by the second compressor rotor piston 4 and the compressor cylinder 2, and the throttle valve 27 is communicated with a second direct-current cavity 11 formed by the first compressor rotor piston 3 and the compressor cylinder 2; valve bodies are arranged in the first direct current cavity 10 and the second direct current cavity 11. The valve body mainly functions to convert alternating reciprocating motion into unidirectional direct current motion, and is composed of a valve plate 29 and a supporting spring 30, wherein one end of the supporting spring 30 is connected to the inner wall of the compressor cylinder 2, and the other end of the supporting spring is connected with the valve plate 29, as shown in the structural schematic diagrams of figures 2 and 3; when the valve is used as an air suction valve, the valve plate 29 is positioned on the inner side of the valve cavity 31 and is tightly attached to the inner wall of the valve cavity 31 under the action of the spring force; when the valve is used as an exhaust valve, the valve sheet 29 is positioned outside the valve chamber 31 and is brought into close contact with the outer wall surface of the valve chamber 31 by the spring force.
Further, the valve body comprises a first air suction valve 5, a first exhaust valve 6, a second air suction valve 7 and a second exhaust valve 8, the first air suction valve 5 and the first exhaust valve 6 are located in a first direct-current cavity 10, and the second air suction valve 7 and the second exhaust valve 8 are located in a second direct-current cavity 11; the first direct current cavity 10 and the second direct current cavity 11 are communicated through a direct current pipeline 12.
Further, the valve body comprises a valve plate 29 and a supporting spring 30, and the valve plate 29 is fixed on the compressor cylinder 2 through the supporting spring 30.
the invention provides a mixed circulation low-temperature refrigerating machine, when working, the system is filled with helium gas with certain pressure, two ends of a first coil 15 and a second coil 16 are driven by alternating current with certain frequency to generate an alternating magnetic field, a first rotor magnet 13 and a second rotor magnet 14 respectively drive a first compressor rotor piston 3 and a second compressor rotor piston 4 to do linear reciprocating motion under the action of the alternating magnetic field, and periodic pressure fluctuation, namely periodic compression-expansion, is formed in a compression cavity 9 under the action of the end surface of the center side of the piston; pressure fluctuation enters the Stirling or pulse tube refrigerator assembly from the compression cavity 9 through the connecting pipe 19, and refrigeration capacity is generated at the first-stage cold head 22 and the second-stage cold head 23 under the action of the phase modulation assembly 20, wherein the working temperature area of the first-stage cold head 22 is about 100-50K, and the second-stage cold head 23 is located in the 20-10K temperature area.
In fig. 1, a first direct current cavity 10 is formed by a right compressor cylinder 2 and a step side of a second compressor rotor piston 4, when the second compressor rotor piston 4 is at a balance position, a first air suction valve 5 and a valve plate 29 of a first exhaust valve 6 are both in a closed state, the second compressor rotor piston 4 gradually moves rightwards, the volume of the first direct current cavity 10 expands, when the second compressor rotor piston 4 approaches to reach the rightmost end, the pressure reaches the lowest value, the valve plate 29 of the first air suction valve 5 is opened under the action of pressure difference at two sides by overcoming the spring force, and the gas sucked into the throttling refrigerator enters a first-stage direct current cavity 8; when the second compressor rotor piston 4 reaches the rightmost end, the piston further moves leftwards to start compressing gas, at the moment, the pressure gradually rises, and a valve plate of the first air suction valve 5 is closed under the action of the pressure and the spring force; the valve plates 29 of the first air suction valve 5 and the first air exhaust valve 6 are in a closed state, when the second compressor rotor piston 4 is close to the leftmost end, the pressure is compressed to be close to the maximum value, at the moment, the valve plate 29 of the first air exhaust valve 6 is opened under the action of pressure difference, and the compressed high-pressure air enters the connecting pipe 12; when the second compressor rotor piston 4 reaches the leftmost end, the second compressor rotor piston continues moving rightwards, the valve plate 29 of the second compressor rotor piston 6 is closed, the pressure after gas expansion is reduced, and the cycle of expansion, suction, compression, exhaust and expansion is repeated.
The working principle of the second direct current cavity 11 is similar to that of the first direct current cavity, and the pressure is further increased on the basis of the first direct current cavity 10. In fig. 1, a second direct-current cavity 11 is formed by the left-side compressor cylinder 2 and the stepped side of the first compressor rotor piston 3, when the first compressor rotor piston 3 is in a balanced position, the second suction valve 7 and the valve plate 29 of the second exhaust valve 8 are both in a closed state, the rotor piston gradually moves leftward, the volume of the second direct-current cavity 11 expands, when the first compressor rotor piston 3 approaches to the leftmost end, the pressure reaches the lowest value, the valve plate 29 of the second suction valve 7 is opened against the spring force under the action of the pressure difference between the two sides, and the gas compressed at one stage is sucked through the connecting pipe 9 and enters the second direct-current cavity 11; when the first compressor rotor piston 3 reaches the leftmost end, the piston further moves rightwards to start compressing gas, the pressure is gradually increased at the moment, and the valve plate 29 of the second-stage suction valve 13 is closed under the action of the pressure and the spring force; the second suction valve 7 and the valve plate 29 of the second exhaust valve 8 are in a closed state, when the first compressor rotor piston 3 is close to the rightmost end, the pressure is compressed to be close to the maximum value, at the moment, the valve plate 29 of the second exhaust valve 8 is opened under the action of pressure difference, and the compressed high-pressure gas enters the first refrigeration unit through the exhaust pipe 18; when the first compressor rotor piston 3 reaches the rightmost end, the expansion is continued leftwards, the valve plate 29 of the first exhaust valve 6 is closed, the pressure is further reduced, and the cycle of expansion-suction-compression-exhaust-expansion is repeated.
The gas after two-stage compression enters a throttling refrigerating machine, and the following circulation processes are carried out in sequence: firstly, the gas enters the side of a room temperature end heat exchanger 21 to radiate heat to room temperature, and then enters a first-stage regenerative heat exchanger 24 to perform regenerative exchange with returned low-pressure gas; then the gas enters a first-stage cold head 22 of a Stirling or pulse tube refrigerator and is cooled to a temperature range of 100-50K; then enters a second-stage regenerative heat exchanger 25 to further exchange heat with the returned low-pressure gas; the gas is further reduced to a 20-10K temperature zone at the second stage cold head 23 of the Stirling or pulse tube refrigerator; exchanging heat with the returned low pressure, low temperature gas in the third stage recuperative heat exchanger 26; after the cooled high-pressure gas enters the throttle valve 27, an isenthalpic pressure reduction process is carried out, and the temperature is reduced to generate a refrigeration effect to reach or approach a liquid helium temperature zone; the throttled low-temperature low-pressure gas or liquid enters the cold-end heat exchanger 28 to absorb the heat of the cooled device, and the gas generated after the throttled liquid is heated enters the third-stage regenerative heat exchanger 26 to perform regenerative heat with the high-pressure gas; and then passes through the second stage recuperator 25 and the first stage recuperator 24 in sequence until the aspirated air duct 17 is connected to the first aspiration valve 5, forming a complete thermodynamic cycle.
The mixed circulation low-temperature refrigerating machine provided by the invention has the following advantages: 1. the stepped piston structure of the compressor piston is adopted, and alternating flow and high-low pressure gas are generated by a single compressor at the same time, so that the volume and weight of the system can be effectively reduced; 2. the Stirling refrigerator or Stirling type pulse tube refrigerator is used for precooling the JT throttling refrigerator, the advantages of high efficiency and high power density of a Stirling cycle in a temperature region above liquid hydrogen are fully utilized, and the advantages of high efficiency, large cold quantity, high reliability and no moving part of the helium throttling refrigerator in the liquid helium temperature region are simultaneously exerted, so that the efficient compact low-temperature refrigerator without the moving part, which operates in the liquid helium temperature region, is formed; 3. a Stirling or pulse tube refrigerator is adopted for refrigerating in a temperature region above liquid hydrogen, and the advantages of high efficiency and high power density of Stirling cycle in the temperature region above liquid hydrogen are fully utilized; 4. the single compressor is combined with the one-way valve to simultaneously generate alternating flow and high-low pressure gas; 5. the system employs two stages of compression.
The embodiments of the present invention have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (9)
1. A mixed cycle low-temperature refrigerator is characterized by comprising a gas compression unit and a first refrigeration unit connected with the gas compression unit, wherein a second refrigeration unit is arranged on the first refrigeration unit in series; the first refrigeration unit comprises a multi-stage cold head, the second refrigeration unit comprises a multi-stage heat exchanger, and the cold head and the heat exchanger are arranged at intervals; the gas compression unit is a gas compressor, the gas compressor comprises a compressor shell (1) and a compressor cylinder (2) arranged in the compressor shell (1), and the inner wall of the compressor cylinder (2) is in a step shape.
2. A mixed cycle cryocooler according to claim 1, characterized in that the inner diameter dimension of the middle part of the compressor cylinder (2) is larger than the inner diameter dimension of the two end parts of the compressor cylinder (2).
3. The mixed cycle cryogenic refrigerator according to claim 2, wherein the gas compressor further comprises a first compressor mover piston (3) and a second compressor mover piston (4), the first compressor mover piston (3) and the second compressor mover piston (4) are both stepped pistons adapted to the shape of the inner wall of the compressor cylinder (2), and the first compressor mover piston (3) and the second compressor mover piston (4) are respectively fitted to two ends of the compressor cylinder (2).
4. A mixed cycle cryocooler according to claim 1, characterized in that a coil and a mover magnet are arranged between the compressor housing (1) and the compressor cylinder (2), the coil being arranged inside the compressor housing (1), the mover magnet being arranged outside the compressor cylinder (2), the coil and the mover magnet being arranged opposite each other.
5. The mixed cycle cryocooler according to claim 3, wherein the first refrigeration unit comprises a room temperature end heat exchanger (21), a first stage cold head (22) and a second stage cold head (23) connected in series, the room temperature end heat exchanger (21) being in communication with a compression chamber (9) formed by the first compressor mover piston (3), the second compressor mover piston (4) and the compressor cylinder (2).
6. The mixed cycle cryocooler according to claim 5, wherein a phase modulation assembly (20) is arranged between the room temperature side heat exchanger (21) and the gas compression unit, the phase modulation assembly (20) being connected to the room temperature side heat exchanger (21) at an end remote from the first stage cold head (22) and the second stage cold head (23).
7. The mixed cycle cryocooler according to claim 5, wherein the second refrigeration unit comprises a throttle valve (27), a cold end heat exchanger (28) and a multi-stage recuperative heat exchanger connected in series, the recuperative heat exchanger being in communication with the second compressor mover piston (4) and the first flow through cavity (10) formed by the compressor cylinder (2), the throttle valve (27) being in communication with the first compressor mover piston (3) and the second flow through cavity (11) formed by the compressor cylinder (2); and valve bodies are arranged in the first direct current cavity (10) and the second direct current cavity (11).
8. A mixed cycle cryocooler according to claim 7, wherein the valve body comprises a first suction valve (5), a first exhaust valve (6), a second suction valve (7) and a second exhaust valve (8), the first suction valve (5) and the first exhaust valve (6) being located in the first DC chamber (10), the second suction valve (7) and the second exhaust valve (8) being located in the second DC chamber (11); the first direct current cavity (10) is communicated with the second direct current cavity (11) through a direct current pipeline (12).
9. A mixed cycle cryocooler according to claim 7, wherein the valve body comprises a valve plate (29) and a support spring (30), the valve plate (29) being fixed to the compressor cylinder (2) by the support spring (30).
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| CN110425768A (en) * | 2019-07-30 | 2019-11-08 | 中国电子科技集团公司第十一研究所 | Taper throttling refrigerator |
| CN110486979B (en) * | 2019-08-29 | 2021-08-24 | 上海理工大学 | Multi-stage single-side precooling laminated staggered micro-channel throttling heat exchange refrigerator |
| CN110486978B (en) * | 2019-08-29 | 2021-08-24 | 上海理工大学 | Array cylindrical group type multistage laminated microchannel throttling heat exchange refrigerator |
| CN110553416A (en) * | 2019-09-11 | 2019-12-10 | 中国科学院上海技术物理研究所 | Active control alternating current-direct current composite deep low-temperature mechanical refrigeration system |
| CN114046611B (en) * | 2021-12-21 | 2024-10-08 | 上海超立安科技有限责任公司 | Integrated Stirling refrigerator for low-temperature refrigerator |
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| US6425250B1 (en) * | 2001-02-08 | 2002-07-30 | Praxair Technology, Inc. | System for providing cryogenic refrigeration using an upstream pulse tube refrigerator |
| JP2004301367A (en) * | 2003-03-28 | 2004-10-28 | Aisin Seiki Co Ltd | Extremely low temperature generator |
| CN103062951B (en) * | 2013-01-25 | 2015-03-25 | 浙江大学 | Low-temperature J-T (Joule-Thomson) throttling cooler precooled by Stirling/pulse tube composite type cooler |
| CN104457009B (en) * | 2014-11-27 | 2016-08-24 | 中科力函（深圳）低温技术有限公司 | Low-temperature pulse tube refrigerator adopting mixed structure |
| CN106885390B (en) * | 2017-01-19 | 2019-03-05 | 中国科学院理化技术研究所 | Cryogenic refrigeration system with pulse tube expander |
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