CN108870821B - Low-temperature cooling equipment using refrigerator as cold source - Google Patents
Low-temperature cooling equipment using refrigerator as cold source Download PDFInfo
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- CN108870821B CN108870821B CN201810679670.9A CN201810679670A CN108870821B CN 108870821 B CN108870821 B CN 108870821B CN 201810679670 A CN201810679670 A CN 201810679670A CN 108870821 B CN108870821 B CN 108870821B
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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
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
- F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
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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
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D29/00—Arrangement or mounting of control or safety devices
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Abstract
The invention discloses a low-temperature cooling device taking a refrigerating machine as a cold source, which comprises a cover body with a vacuum cavity, the refrigerating machine, a liquid helium pool, an overflow helium pool and a sample container, wherein the liquid helium pool, the overflow helium pool and the sample container are arranged in the vacuum cavity; a condenser is arranged on the secondary cold head; the super-flow helium tank is positioned below the liquid helium tank; the liquid helium pool accommodating cavity is communicated with the super-flow helium pool accommodating cavity through a throttling pipeline; the sample container is positioned below the super flow helium tank, and the sample container is fixedly attached to the bottom surface of the super flow helium tank; the equipment also comprises a main air inlet pipeline and a gas circulating pipeline; one end of the main air inlet pipeline is connected with helium supply equipment, and the other end of the main air inlet pipeline is communicated with the liquid helium tank accommodating cavity; one end of the gas circulation pipeline is communicated with the super-flow helium tank cavity, and the other end of the gas circulation pipeline is communicated and connected with the main gas inlet pipeline. The low-temperature cooling equipment provided by the invention can rapidly obtain 1.8K super-current helium by using normal-temperature high-purity helium, the precooling time of a cooled sample is short, and a device needing extremely low temperature can be rapidly cooled conveniently.
Description
Technical Field
The invention relates to the technical field of cryogenic cooling. And more particularly, to a cryogenic cooling apparatus using a refrigerator as a cold source.
Background
In high-precision instruments such as a photon detector, an infrared detector and the like, detection signals are weak after all, and are easily influenced by surrounding interference. With the development of high and new technologies such as aerospace, information and the like, the requirements of the technical field on the precision of the detector are increasingly improved, and higher requirements on the elimination of noise interference are provided. The lower the temperature, the less radiation the object emits, so the lower the ambient temperature the detector is at, the less ambient interference, and the higher the measurement accuracy. In cooling superconducting magnets, superconducting helium is widely used for system cooling in high magnetic field strength superconducting magnets and superconducting cavities because of its lower viscosity, higher specific heat and higher thermal conductivity compared to liquid helium. With the increasing demand of national large scientific engineering on low-temperature environment, users put higher requirements on the stability, repeatability and measurement accuracy of temperature control below 25K, and the lowest temperature fixed point specified in the international temperature scale up to now is the hydrogen triple point (13.8K). In order to meet the new requirement for high-accuracy temperature measurement in China and obtain long-term and stable liquid helium superflow fixed point experiment data support, the liquid helium superflow helium conversion fixed point measuring device needs to provide a stable and continuous cold source for experiments.
The existing devices for obtaining the temperature below 2K are divided into two types, one type is to reduce the pressure and the temperature of liquid helium in a sealed container, and the method has the defects that the consumption of helium is huge, the sealing is easy to fluctuate in temperature when the liquid helium is filled, meanwhile, the liquid helium needs to be filled artificially and continuously, and the danger is large. The other is to liquefy helium into liquid helium by a refrigerator and then generate 1.8K super-flow helium by throttling and cooling, and the device can overcome the defects of the former one, but also brings new problems. Due to the introduction of the refrigerating machine, vibration of the sample is inevitably brought, which brings great interference to the operation of the cooled precision instrument. Secondly, the refrigerator cools the helium gas at normal temperature to generate 4.2K liquid helium, and a helium circulating pipeline needs to be pre-cooled firstly, so that the process takes a long time. Finally, to eliminate the vibration from the refrigerator, the sample and refrigerator need to be in as little contact as possible, which presents difficulties in cooling the sample.
In order to obtain an experimental environment lower than 2K and overcome the defects of the existing equipment, a new improved equipment is urgently needed.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a cryogenic cooling apparatus using a refrigerator as a cold source. The cooling equipment can rapidly obtain 1.8K super-flow helium by precooling normal-temperature high-purity helium, the precooling time of a cooled sample is short, and a device needing extremely low temperature can be rapidly cooled conveniently; and through one-time gas supply, helium can be converted and circulated in the equipment gas-liquid, and can continuously obtain the super-flow helium, so that stable cold quantity is provided for the cooled sample, the helium consumption is saved, and the influence on the stability and the accuracy of the low-temperature experiment of the cooled sample due to the fluctuation of the temperature is avoided.
According to at least one aspect of the present invention, there is provided a cryogenic cooling apparatus using a refrigerator as a cold source, the apparatus comprising:
a housing having a vacuum chamber;
a refrigerator including a primary cold head and a secondary cold head; the first-stage cold head and the second-stage cold head are both positioned in the vacuum cavity; and
the liquid helium tank, the super-flow helium tank and the sample container are arranged in the vacuum cavity;
the liquid helium tank and the secondary cold head are fixed in a sealing mode, an accommodating cavity is formed, a condenser is arranged on the secondary cold head, and the condenser is located in the accommodating cavity;
the overflow helium tank comprises a sealed cavity and is positioned below the liquid helium tank; the liquid helium pool accommodating cavity is communicated with the super-flow helium pool accommodating cavity through a throttling pipeline;
the sample container comprises a sealed sample cavity, is positioned below the super-flow helium tank and is fixedly attached to the bottom surface of the super-flow helium tank;
the equipment also comprises a main air inlet pipeline and a gas circulating pipeline;
one end of the main air inlet pipeline is connected with helium supply equipment, and the other end of the main air inlet pipeline is communicated with the liquid helium tank accommodating cavity;
one end of the gas circulation pipeline is communicated with the super-flow helium tank cavity, and the other end of the gas circulation pipeline is communicated and connected with the main gas inlet pipeline.
In addition, it is preferable that the gas circulation line includes a vacuum pump, and an air bag provided on the gas circulation line between the main air intake line and the vacuum pump.
In addition, preferably, the main air inlet pipeline comprises heat exchanging parts wound on the primary cold head, the secondary cold head and the cylinder between the primary cold head and the secondary cold head;
the heat exchange part comprises:
the first heat exchanging part corresponds to the first-stage cold head;
the second heat exchanging part corresponds to the cylinder between the first-stage cold head and the second-stage cold head; and
and the third heat exchanging part corresponds to the second-stage cold head.
Preferably, the first heat exchanging portion and the third heat exchanging portion are both made of copper;
the second heat exchanging part is made of stainless steel.
In addition, it is preferable that a cold trap having an inner cavity and provided in communication with the primary air intake pipeline is further included in the primary air intake pipeline between the heat exchanging portion and the helium gas supply device.
In addition, preferably, a communication pipeline including a stop valve is further arranged between the liquid helium pool accommodating cavity and the overflow helium pool accommodating cavity.
In addition, preferably, the equipment also comprises a primary cold shield positioned in the vacuum cavity;
and the primary cold head, the cylinder between the primary cold head and the secondary cold head, the liquid helium tank, the super-current helium tank and the sample container are all positioned in the inner cavity of the primary cold screen.
In addition, preferably, the equipment also comprises a secondary cold shield positioned in the inner cavity of the primary cold shield;
and the secondary cold head, the liquid helium tank, the super-flow helium tank and the sample container are all positioned in the inner cavity of the secondary cold screen.
In addition, preferably, the equipment further comprises a liquid helium dewar which is in communication connection with the liquid helium pool accommodating cavity through an injection pipeline.
In addition, preferably, a storage space for containing liquid helium is reserved between the bottom of the condenser and the bottom of the liquid helium tank; and the communication connection position of the other end of the main air inlet pipeline and the liquid helium tank is positioned at the part of the liquid helium tank corresponding to the condenser.
The invention has the following beneficial effects:
1. according to the low-temperature cooling equipment with the refrigerating machine as the cold source, 1.8K super-flow helium can be quickly obtained by precooling normal-temperature high-purity helium, the precooling time of a cooled sample is short, and a device needing extremely low temperature can be quickly cooled conveniently; and through one-time gas supply, helium can be converted and circulated in the equipment gas-liquid, and can continuously obtain the super-flow helium, so that stable cold quantity is provided for the cooled sample, helium resources are saved, and the influence on the stability and accuracy of the low-temperature experiment of the cooled sample due to temperature fluctuation is avoided.
2. The cryogenic cooling equipment provided by the invention has the advantages of low requirement on manual operation, simplicity, convenience, safety and reliability in operation and low difficulty in liquid helium storage, and can be used for cooling devices such as a liquid helium super-current helium conversion fixed point measuring device, a superconducting magnet, a photon detector and the like.
3. The low-temperature cooling equipment provided by the invention comprises a liquid helium filling port, and after the temperature of the secondary cold head of the refrigerating machine reaches a preset temperature, liquid helium can be directly input for reducing pressure and cooling, so that a sample container and a cooled sample in a sample cavity can be quickly precooled. Meanwhile, when the equipment has a fault of a refrigerating machine or runs out of liquid helium caused by improper operation, the liquid helium can be directly introduced to obtain the super-flow helium, so that the temperature fluctuation of a cooled sample can be prevented.
4. In the low-temperature cooling equipment provided by the invention, the evaporation capacity of the over-flow helium is equal to the liquefaction capacity of the helium through the control of the throttling pipeline, so that the equipment can continuously provide a 1.8K cold source for a cooled sample.
5. In the low-temperature cooling equipment provided by the invention, high-purity helium can be quickly pre-cooled through the heat exchange part wound on the main air inlet pipeline on the cylinder and the cold head of the refrigerator, the pre-cooled helium enters the condenser below the secondary cold head for liquefaction, the pre-cooling speed of the helium is improved, meanwhile, the heat exchange part can fully utilize the cylinder for heat regeneration, and the liquefaction amount of the helium is obviously improved.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Fig. 1 shows a schematic diagram of the overall structure of the device provided by the present invention.
Fig. 2 shows an enlarged schematic view of a portion a in fig. 1.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.
In order to more clearly illustrate the present invention, the following further description of the invention is given in conjunction with the preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
In order to solve the defects of the prior art, the invention provides a low-temperature cooling device using a refrigerator as a cold source. The cooling equipment can rapidly obtain 1.8K super-flow helium by precooling normal-temperature high-purity helium, the precooling time of a cooled sample is short, and a device needing extremely low temperature can be rapidly cooled conveniently; and through one-time gas supply, helium can be converted and circulated in the equipment, and can continuously obtain the super-current helium so as to provide stable cold quantity for a cooled sample. Referring to fig. 1 and 2, in particular, the cryocooling apparatus using a refrigerator as a cold source provided by the present invention includes: a housing 1 having a vacuum chamber 11; a refrigerator 2 including a primary cold head 21 and a secondary cold head 22; the primary cold head 21 and the secondary cold head 22 are both positioned in the vacuum cavity 11; and a liquid helium bath 3, an overflow helium bath 4 and a sample container 5 which are arranged in the vacuum chamber 11;
the liquid helium tank 3 and the secondary cold head 22 are fixed in a sealing manner, an accommodating cavity 31 is formed, a condenser 221 is arranged on the secondary cold head 22, and the condenser 221 is located in the accommodating cavity 31; the overflow helium tank 4 comprises a sealed containing cavity 41, and the overflow helium tank 4 is positioned below the liquid helium tank 3; the containing cavity 31 of the liquid helium pool 3 is communicated with the containing cavity 41 of the super-flow helium pool 4 through a throttling pipeline 100, and a throttling valve is arranged on the throttling pipeline 100;
the sample container 5 comprises a sealed sample cavity 51, the sample container 5 is positioned below the super flow helium tank 4, and the sample container 5 is fixedly attached to the bottom surface of the super flow helium tank 4; further, the apparatus further comprises a primary air intake pipeline 200 and a gas circulation pipeline 300; one end of the primary air inlet pipeline 200 is connected with a helium gas supply device 6, and the other end of the primary air inlet pipeline is communicated with the accommodating cavity 31 of the liquid helium tank 3; one end of the gas circulation pipeline 300 is communicated with the cavity 41 of the super flow helium tank 4, and the other end is communicated with the main gas inlet pipeline 200, and in addition, the gas circulation pipeline 300 comprises a vacuum pump 301 and an air bag 302 arranged on the gas circulation pipeline 300 between the main gas inlet pipeline 200 and the vacuum pump 301.
As specific embodiments, the following detailed description will be made for each composition of the cooling apparatus provided by the present invention:
the cover body 1 is made of stainless steel, and the vacuum cavity 11 of the cover body 1 provides a vacuum environment for the whole cooling device.
The refrigerator 2 adopts a GM refrigerator, a first-stage cold head 21 and a second-stage cold head 22 of the refrigerator 2 provide cold for the equipment, and thermometers are respectively arranged on the first-stage cold head 21 and the second-stage cold head 22 to detect the temperature of each cold head.
The liquid helium tank 3 is made of oxygen-free copper, is hermetically connected with the secondary cold head 22 of the refrigerator 2 and is used for storing liquid helium generated by helium, a thermometer is arranged at the bottom of the liquid helium tank 3 and is used for detecting the temperature in the liquid helium tank 3, and meanwhile, the liquid helium tank 3 is also provided with a liquid level transmitter which is used for detecting the liquid helium level in the liquid helium tank 3. It should be noted that the liquid helium tank 3 should be further provided with a pressure sensor to monitor the pressure in the liquid helium tank 3, and a thin tube is arranged above the liquid helium tank 3 and connected to a safety valve arranged outside the vacuum chamber 11 of the cover body 1 to prevent explosion caused by vaporization of liquid helium due to sudden heat leakage of the equipment.
The super-flow helium tank 4 is used for storing liquid helium, and the liquid helium flows from the liquid helium tank 3 to the super-flow helium formed in the super-flow helium tank 4 through decompression and temperature reduction. The bottom of the super flow helium tank 4 is directly contacted with the sample container 5, and is indirectly contacted with the cooled sample 7 in the sample cavity 51 of the sample container 5 through the body of the sample container 5, so that the super flow helium in the super flow helium tank 4 directly provides cold for the cooled sample 7, and preferably, the bottom of the super flow helium tank 4 is provided with a thermometer for measuring the temperature in the super flow helium tank 4.
The sample container 5 comprises a sample cavity 51, the sample cavity 51 is used for placing a cooled sample 7, and the cooled sample 7 can be a device which has high requirements on ultralow temperature stability, such as a liquid helium superflow helium conversion fixed point measuring device, and can also be a device which is sensitive to vibration, such as a photon detector. Furthermore, the body of the sample container 5, preferably made of oxygen-free copper, acts as a radiation screen for the cooled sample 7, preventing ambient radiation from affecting the cooled sample.
The throttling pipeline 100 is used for communicating the containing cavity 31 of the liquid helium tank 3 with the containing cavity 41 of the overflowing helium tank 4, a throttling valve arranged on the throttling pipeline 100 can throttle and cool the liquid helium passing through the throttling pipeline 100, meanwhile, the flow rate of the liquid helium entering the overflowing helium tank 4 can be controlled, the stable operation of the whole equipment is kept, and a thermometer is arranged on a pipeline behind the throttling valve and used for measuring the temperature of the throttled liquid helium.
The condenser 221 is preferably a plate-fin heat exchanger made of oxygen-free copper, and is directly connected and fixed with the secondary cold head 22 of the refrigerator 2, and the temperature of the condenser 221 is consistent with that of the secondary cold head 22 and is used for liquefying high-purity helium gas entering the accommodating cavity 31 of the liquid helium tank 3. A storage space for containing liquid helium is reserved between the bottom of the condenser 221 and the bottom of the liquid helium tank 3; and the other end of the primary gas inlet pipeline 200 is connected with the liquid helium tank 3 at a position corresponding to the condenser 221 of the liquid helium tank 3.
The main gas inlet pipeline 200 is used for conveying high-purity helium gas in the helium gas supply device 6 into the accommodating cavity 31 of the liquid helium tank 3, the helium gas supply device 6 is used for storing raw material high-purity helium gas (99.999%) for obtaining super-flow helium, and the raw material high-purity helium gas can be a helium bottle with high-purity helium gas, and a pressure gauge is arranged on an outlet of the helium bottle and used for monitoring the internal pressure of the helium bottle and the pressure of a gas inlet; and a flow controller is further arranged on the main air inlet pipeline 200 and used for accurately controlling the flow rate of the helium gas entering the equipment, so that the gas flow of the helium gas is ensured to be equal to the evaporation capacity of the over-flow helium, the stability of the equipment is maintained, the helium gas can be converted and circulated in the equipment, and the over-flow helium can be continuously obtained. And a thermometer is arranged at the outlet of the main gas inlet pipeline (namely a port communicated with the liquid helium tank) and used for detecting the temperature of the outlet helium gas.
The gas circulation pipeline 300 is used for communicating the over-flow helium tank 4 with the primary air inlet pipeline 200; the gas circulation line 300 includes a vacuum pump 301 and an air bag 302. The vacuum pump 301 is used for performing vacuum-pumping processing on the equipment on one hand, and is used for cooling the liquid helium in the super-flow helium tank 4 through pumping on the other hand, so as to obtain the super-flow helium. The air bag 302 is used for storing helium so that after the helium supply device 6 provides helium for the device, the helium can be converted and circulated in the device, and can continuously obtain the super-flow helium, so that stable cold energy is provided for the cooled sample 7, and helium resources are greatly saved.
The basic working principle of the cooling device provided by the invention is that the flow of high-purity helium in the helium supply device 6 is controlled by a flow controller, the helium enters the condenser 221 below the secondary cold head 22 through the main air inlet pipeline 200 and precooled by the cold head of the refrigerating machine 2 to be liquefied, the high-purity helium is liquefied into 4.2K liquid helium, and the generated 4.2K liquid helium is stored in the liquid helium tank 3. And then 4.2K liquid helium in the liquid helium pool 3 enters the super-flow helium pool 4 through throttling and cooling of a throttle valve, at the moment, the vacuum pump 301 is started to reduce the pressure and cool, and under the combined action of the throttle valve and the vacuum pump 301, the 4.2K liquid helium is cooled to become the super-flow helium with the temperature of 1.8K. After the 1.8K overflowing helium amount in the overflowing helium tank 4 reaches a preset value, the throttle valve is opened to a proper opening degree, the evaporation amount of the 1.8K overflowing helium is controlled to be equal to the helium liquefaction amount, and therefore the device can continuously provide a 1.8K cold source for the cooled sample. The helium gas evaporated is collected in the gas bag 302 and then enters the next gas-liquid conversion cycle by the action of the vacuum pump 301. It should be noted that, the primary air intake pipeline 200 and the gas circulation pipeline 300 of the cooling device further include a plurality of valves for delivering, circulating or regulating the delivery amount of the helium gas, which are known to those skilled in the art, and this embodiment will not be described in detail herein.
In a preferred embodiment, since the sample container 5 and the cooled sample 7 in the sample cavity 51 of the sample container 5 are only fixed in contact with the super-flow helium pool 4, and 1.8K of super-flow helium in the super-flow helium pool 4 is not generated yet in the pre-cooling stage, the super-flow helium pool 4, the sample container 5 and the cooled sample 7 are extremely difficult to cool. Therefore, in the present invention, a communication pipeline 400 including a stop valve is further disposed between the receiving cavity 31 of the liquid helium tank 3 and the receiving cavity 41 of the overflow helium tank 4. The stop valve is opened in the precooling stage, so that 4.2K liquid helium generated in the liquid helium tank 3 can be completely put into the super-current helium tank 4 in advance, and the vacuum pump 301 is opened to pump out evaporated helium. When the experimental phase is performed, the stop valve is closed, and 4.2K liquid helium in the liquid helium tank 3 enters the super-flow helium tank 4 through the throttling pipeline 100.
Specifically, after 4.2K liquid helium formed in the liquid helium tank 3 reaches a set amount, the stop valve arranged on the communication pipeline 400 is opened, 4.2K liquid helium all flows into the super flow helium tank 4, at this time, the vacuum pump 301 is started to pump out evaporated helium to the air bag 302, the pressure is reduced and the temperature is reduced, so that the sample container 5 and the cooled sample 7 in the sample cavity 51 of the sample container 5 are precooled quickly, when the temperature of the sample container 5 and the cooled sample 7 is reduced to about 4.2K, the stop valve on the communication pipeline 400 is closed, after the 4.2K liquid helium amount in the liquid helium tank 3 reaches a preset value, the throttle valve on the throttle pipeline 100 is opened to a proper opening degree, and the combined action of the throttle valve arranged on the throttle pipeline 100 and the vacuum pump 301 is utilized to reduce the temperature of the 4.2K liquid helium in the super flow helium tank 4 to be 1.8K super flow helium.
In addition, in the embodiment of the present invention, preferably, the cooling apparatus further includes a liquid helium dewar 8, and the liquid helium dewar 8 is connected to the accommodating chamber of the liquid helium tank 3 through an injection pipe 81. The purpose of arranging the liquid helium dewar 8 is to directly input 4.2K liquid helium through the liquid helium dewar 8 after the temperature of the secondary cold head 22 of the refrigerator 2 reaches a preset temperature, open a stop valve on the communicating pipeline 400, then open the vacuum pump 301 to pump the evaporated helium to the air bag 302, reduce the pressure and reduce the temperature, and quickly pre-cool the sample container 5 and the cooled sample 7 in the sample cavity 51 of the sample container 5. In addition, when the equipment has a fault of a refrigerating machine or runs out of liquid helium caused by improper operation, 4.2K liquid helium can be directly introduced into the liquid helium tank 3 by using the liquid helium Dewar 8, and 1.8K super-current helium is obtained, so that the temperature of the cooled sample 7 can be effectively prevented from fluctuating, and the stability and the accuracy of an experiment are influenced.
Furthermore, preferably, the primary air intake pipe 200 includes heat exchanging portions wound around the primary cold head 21, the secondary cold head 22 and the cylinder 23 between the primary and secondary cold heads;
the heat exchange part comprises a first heat exchange part 201 corresponding to the first-stage cold head 21; a second heat exchanging part 202 corresponding to the cylinder 23 between the first-stage cold head 21 and the second-stage cold head 22; and a third heat exchanging part 203 corresponding to the secondary cold head 22. Preferably, the first heat exchanging portion 201 and the third heat exchanging portion 203 are both made of red copper or oxygen-free copper; the second heat exchanging portion 202 is made of stainless steel. The material of first heat transfer portion 201 and the material of third heat transfer portion 203 are red copper and are anaerobic copper, because red copper or anaerobic copper's coefficient of heat conductivity is high, can heat transfer portion fully with the one-level cold head, the heat transfer of second grade cold head for the cooling to the helium, the material of second heat transfer portion 202 is stainless steel, the coefficient of heat conductivity of stainless steel is lower relatively, when with the cylinder heat transfer, can effectively keep apart a cold head, the heat transfer between the second grade cold head, avoid the cold volume loss of refrigerator. In the invention, the helium gas is rapidly pre-cooled through the heat exchanging part wound on the main air inlet pipeline 200 on the cylinder and the cold head of the refrigerator 2, the pre-cooled helium gas enters the condenser 221 below the secondary cold head 22 for liquefaction, the pre-cooling speed and efficiency of the helium gas are improved, and the design of the heat exchanging part can fully utilize the back heating of the cylinder 23, thereby obviously improving the liquefaction capacity of the helium gas.
Furthermore, the equipment also comprises a primary cold shield 12 positioned in the vacuum cavity 11 and a secondary cold shield 13 positioned in the inner cavity of the primary cold shield 12; and the cylinder 23, the secondary cold head 22, the liquid helium tank 3, the super-flow helium tank 4 and the sample container 5 among the primary cold head 21, the primary cold head 21 and the secondary cold head 22 are all positioned in the inner cavity of the primary cold screen 12. The secondary cold head 22, the liquid helium tank 3, the super-current helium tank 4 and the sample container 5 are all positioned in the inner cavity of the secondary cold screen 13. It will be understood by those skilled in the art that the primary and secondary cold shield chambers should be in a vacuum state.
The primary cold shield 12 is made of oxygen-free copper, is directly connected and fixed with the primary cold head 21, and has the temperature consistent with that of the primary cold head 21; the primary cold screen 12 is coated with a plurality of layers of heat insulating materials, and the primary cold screen 12 serves as a radiation screen to prevent the influence of heat radiation on the temperature of the inner cavity of the primary cold screen; and a thermometer is also arranged on the primary cold shield 12 and used for monitoring the temperature of the primary cold shield 12.
The secondary cold screen 13 is made of oxygen-free copper and is directly connected and fixed with the secondary cold head 22, the temperature of the secondary cold screen is consistent with that of the secondary cold head 22, a plurality of layers of heat insulating materials are coated on the secondary cold screen 13, and the secondary cold screen 13 serves as a radiation screen to prevent the influence of heat radiation on the temperature of an inner cavity of the secondary cold screen; and a thermometer is also arranged on the second-stage cold shield 13 and used for monitoring the temperature of the second-stage cold shield 13.
In order to remove impurity gases such as oxygen and nitrogen from the helium gas and prevent the solidification of the impurity gases from blocking the primary air intake pipe 200, it is preferable that a cold trap 9 having an inner cavity, which is arranged to communicate with the primary air intake pipe 200, is included in the primary air intake pipe 200 between the heat exchanging part and the helium gas supply device 6. The cold trap 9 is located in the vacuum chamber 11 between the primary cold screen 12 and the cover body 1, preferably, the cold trap 9 is arranged on a flange of the primary cold screen 12 fixedly connected with the primary cold head 21, the primary cold head 21 supplies cold energy to the cold trap 9 through the primary cold screen 12, helium supplied by the helium supply device 6 is firstly precooled in the cold trap 9, and the helium is precooled by the cold trap 9 and then enters the heat exchange part of the main air inlet pipeline 200 for further precooling.
The basic flow of the cooling equipment provided by the invention is as follows:
(1) firstly, the whole equipment is vacuumized to ensure that the vacuum degree in the equipment reaches 10-4Pa；
(2) Introducing high-purity helium gas into the liquid helium tank and the super-flow helium tank by using a main gas inlet pipeline and a gas circulating pipeline for purging and replacement; the process is repeated for five times, so that the residual air in the pipeline can be prevented from freezing and blocking the main air inlet pipeline and the gas circulation pipeline. And after the replacement process is finished, filling helium to 100 Pa.
(3) And starting the refrigerator, simultaneously regulating helium to enter, maintaining the pressure in the pipeline at 100Pa, and generating liquid helium when the temperature of the secondary cold head reaches 4.2K. And when the liquid level of the liquid helium tank reaches a preset liquid level, the low-temperature stop valve is opened, so that the liquid helium flows into the super-flow helium tank, and the super-flow helium tank and the sample cavity are cooled.
(4) And when the temperature of the sample reaches about 5K, closing the low-temperature stop valve, opening the throttle valve and the vacuum pump, and cooling the liquid helium until the temperature of the overflowing helium in the overflowing helium tank is stabilized near 1.8K.
(5) Monitoring the liquid helium amount in the liquid helium tank, and adjusting the opening of the throttle valve to ensure that the liquefaction amount of the high-purity helium gas is equal to the liquid helium amount passing through the throttle valve and equal to the evaporation amount of the over-flow helium in the over-flow helium tank, so that the helium gas can be converted and circulated in the equipment, and the over-flow helium can be continuously obtained.
(6) The temperature, level and pressure of the liquid helium bath are monitored, as well as the temperature of the overflow helium in the overflow helium bath and the temperature of the sample being cooled.
By combining the above contents, the cryogenic cooling equipment using the refrigerator as the cold source provided by the invention can rapidly obtain 1.8K super-flow helium by precooling with normal-temperature high-purity helium gas, the precooling time of a cooled sample is short, and the device needing extremely low temperature can be rapidly cooled conveniently; and through one-time gas supply, helium can be converted and circulated in the equipment gas-liquid, and can continuously obtain the super-flow helium, so that stable cold quantity is provided for the cooled sample, helium resources are saved, and the influence on the stability and accuracy of the low-temperature experiment of the cooled sample due to temperature fluctuation is avoided. The cryogenic cooling equipment provided by the invention also has the advantages of low requirement on manual operation, simplicity, convenience, safety and reliability in operation, small difficulty in storing liquid helium and the like.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (10)
1. A cryogenic cooling apparatus using a refrigerator as a cooling source, the apparatus comprising:
a housing having a vacuum chamber;
a refrigerator including a primary cold head and a secondary cold head; the first-stage cold head and the second-stage cold head are both positioned in the vacuum cavity; and
the liquid helium tank, the super-flow helium tank and the sample container are arranged in the vacuum cavity;
the liquid helium tank and the secondary cold head are fixed in a sealing mode, an accommodating cavity is formed, a condenser is arranged on the secondary cold head, and the condenser is located in the accommodating cavity;
the overflow helium tank comprises a sealed cavity and is positioned below the liquid helium tank; the liquid helium pool accommodating cavity is communicated with the super-flow helium pool accommodating cavity through a throttling pipeline;
the sample container comprises a sealed sample cavity, is positioned below the super-flow helium tank and is fixedly attached to the bottom surface of the super-flow helium tank;
the equipment also comprises a main air inlet pipeline and a gas circulating pipeline;
one end of the main air inlet pipeline is connected with helium supply equipment, and the other end of the main air inlet pipeline is communicated with the liquid helium tank accommodating cavity;
one end of the gas circulation pipeline is communicated with the super-flow helium tank cavity, and the other end of the gas circulation pipeline is communicated and connected with the main gas inlet pipeline.
2. The cryocooling apparatus of claim 1, wherein the gas circulation line includes a vacuum pump and a bladder disposed in the gas circulation line between the primary gas inlet line and the vacuum pump.
3. The cryogenic cooling apparatus of claim 1, wherein the primary air inlet line includes heat exchanging portions wound around the primary coldhead, the secondary coldhead, and the cylinder between the primary and secondary coldheads;
the heat exchange part comprises:
the first heat exchanging part corresponds to the first-stage cold head;
the second heat exchanging part corresponds to the cylinder between the first-stage cold head and the second-stage cold head; and
and the third heat exchanging part corresponds to the second-stage cold head.
4. The cryogenic cooling apparatus of claim 3,
the first heat exchanging part and the third heat exchanging part are both made of copper;
the second heat exchanging part is made of stainless steel.
5. The cryogenic cooling apparatus of claim 1, wherein the primary gas inlet conduit between the heat exchanging portion and the helium gas supply apparatus further comprises a cold trap having an inner cavity and disposed in communication with the primary gas inlet conduit.
6. The cryogenic cooling apparatus of claim 1, wherein a communication line including a stop valve is further disposed between the liquid helium bath receiving chamber and the super flow helium bath receiving chamber.
7. The cryogenic cooling apparatus of claim 1, further comprising a primary cold shield positioned within the vacuum chamber;
and the primary cold head, the cylinder between the primary cold head and the secondary cold head, the liquid helium tank, the super-current helium tank and the sample container are all positioned in the inner cavity of the primary cold screen.
8. The cryogenic cooling apparatus of claim 7, further comprising a secondary cold shield positioned within the primary cold shield interior chamber of the primary cold shield;
and the secondary cold head, the liquid helium tank, the super-flow helium tank and the sample container are all positioned in the inner cavity of the secondary cold screen.
9. The cryogenic cooling apparatus of claim 1, further comprising a liquid helium dewar in fluid communication with the liquid helium bath receiving chamber through an injection line.
10. The cryogenic cooling apparatus of claim 1, wherein a storage space is left between a bottom of the condenser and a bottom of the liquid helium bath to contain liquid helium; and the communication connection position of the other end of the main air inlet pipeline and the liquid helium tank is positioned at the part of the liquid helium tank corresponding to the condenser.
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| CN109442798B (en) * | 2018-12-05 | 2024-04-09 | 湖南迈太科医疗科技有限公司 | Refrigeration system, closed-loop refrigeration cycle and method for injecting refrigerant |
| CN110749115B (en) * | 2019-11-11 | 2023-12-26 | 中国科学院上海技术物理研究所 | Multifunctional low-temperature vortex coil precooling heat exchanger |
| CN114279167B (en) * | 2020-09-28 | 2023-06-27 | 中国科学院理化技术研究所 | Precooling device of superfluid helium system |
| CN113280572B (en) * | 2021-06-02 | 2022-12-20 | 中国科学院理化技术研究所 | System and method for purifying helium 3 on lunar surface |
| CN113654382B (en) * | 2021-07-20 | 2022-04-15 | 中国科学院高能物理研究所 | Superconducting cooling circulation system driven by no-motion part |
| CN114405572B (en) * | 2021-12-10 | 2023-04-14 | 核工业西南物理研究院 | Helium low-temperature experiment test platform and method under multi-working-condition operation mode |
| CN114754511B (en) * | 2022-03-25 | 2023-05-26 | 中国科学院上海高等研究院 | Refrigerating system and method for cold screen of superconducting undulator |
| CN115388615B (en) * | 2022-04-19 | 2023-11-24 | 北京师范大学 | Argon liquefaction system |
| CN114739115A (en) * | 2022-05-17 | 2022-07-12 | 中船重工鹏力（南京）超低温技术有限公司 | Low-temperature gas liquefying device |
| CN114931840B (en) * | 2022-06-02 | 2024-02-13 | 散裂中子源科学中心 | Helium three-gas purifying system |
| CN117299242B (en) * | 2023-11-27 | 2024-03-12 | 北京飞斯科科技有限公司 | Ultra-low temperature system of inferior K ultra-low vibration |
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| US3221509A (en) * | 1964-01-16 | 1965-12-07 | Ibm | Refrigeration method and apparatus |
| CN101144657A (en) * | 2007-09-30 | 2008-03-19 | 中国科学院合肥物质科学研究院 | Method and device of G-M refrigerating machine for producing liquid helium |
| CN105571190B (en) * | 2016-01-06 | 2019-05-31 | 复旦大学 | A kind of mechanical oscillation isolation consumes extremely low temp, refrigerating system without liquid helium |
| CN106524554B (en) * | 2016-12-14 | 2022-10-11 | 费勉仪器科技（上海）有限公司 | Compact liquid-free helium 1K low-temperature refrigerating device suitable for ultrahigh vacuum environment |
| CN108036538B (en) * | 2017-11-27 | 2020-05-19 | 中国科学院理化技术研究所 | Superfluid helium low-temperature circulating system |
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