Supercooled liquid nitrogen circulating cooling device and using method

Abstract

The invention discloses a supercooled liquid nitrogen circulating cooling device and a using method. The device comprises a Dewar tank and a circulating pipeline assembly. Cold liquid nitrogen is stored in the Dewar tank, a part of the circulating pipeline assembly is located in the Dewar tank, a part of the circulating pipeline assembly protrudes out of the Dewar tank, and the cold liquid nitrogen circulates circularly for heat exchange; wherein a plurality of layers of radiation baffles are arranged in the Dewar tank and located between a cover plate of the Dewar tank and the liquid level of the cold liquid nitrogen; the circulating pipeline assembly comprises a heat exchanger, a liquid supply pipeline, a liquid return pipeline and a bypass pipeline; two ends of the heat exchanger are respectively communicated with the liquid supply pipeline and the liquid return pipeline, and the other ends of the liquid supply pipeline and the liquid return pipeline are communicated; and two ends of the bypass pipeline are respectively communicated with the liquid supply pipeline and the liquid return pipe. According to the supercooled liquid nitrogen circulating cooling device and the using method, the stability of pipeline pressure is improved.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration and cryogenic technology, and in particular to a supercooled liquid nitrogen circulation cooling device and a use method thereof. Background Art

[0002] As people's research on life sciences and physics experiments continues to deepen, such as in the fields of superconductivity and quantum computing, as well as the development of industries such as electronics, semiconductors and precision instruments, more liquid nitrogen supply equipment is needed to provide a continuous and stable low-temperature environment. As a liquid nitrogen supply equipment, the intelligent liquid nitrogen circulation unit can automatically control the supply flow of liquid nitrogen and set the temperature of the liquid nitrogen fluid according to user needs. Its main functions include: refrigeration, low-temperature storage and transportation, liquid nitrogen supply, safety control, etc. It can provide a stable and reliable low-temperature environment for various experiments and tests, and can also be used for cryopreservation and transportation in the fields of medicine and biotechnology.

[0003] For example, it can freeze biological samples at extremely low temperatures, thereby achieving long-term preservation and maintaining the original state of the samples, which is of great significance to biomedical research, germplasm preservation, and protection of animal and plant genetic resources. Intelligent liquid nitrogen circulation units have excellent performance and safety guarantees. They are not only widely used in scientific research, but also can bring practical benefits and application value to industries, medicine, and the environment. They can ensure the normal operation of experimental equipment and extend its service life. They are an indispensable part of modern research and experimental equipment. However, the liquid nitrogen circulation units in the prior art have the following disadvantages:

[0004] 1. The liquid nitrogen in the existing device will be vaporized during the heat exchange process, resulting in an increase in flow rate and flow resistance, and at the same time, the heat exchange effect will deteriorate.

[0005] 2. The temperature fluctuation of liquid nitrogen supply is large, which is not conducive to the stable operation of low-temperature demand equipment.

[0006] 3. The existing device has a single purge and evacuation function, a single pressure stabilization method and a single flow adjustment method, cannot adapt to various needs, and has a low degree of automation.

[0007] 4. The cover of the liquid nitrogen circulation machine will condense due to the low temperature and produce condensed water. The connected loads are all precision instruments and cannot come into contact with water, otherwise the instruments will be damaged. Summary of the invention

[0008] The technical problem to be solved by the present invention is to solve the problem that the existing liquid nitrogen circulation unit has a single flow rate adjustment method, the cover plate condenses, and the generated condensed water damages the tight instruments.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] A supercooled liquid nitrogen circulation cooling device comprises: a dewar tank 100 and a circulation pipeline assembly 200; the dewar tank 100 stores cold liquid nitrogen, the circulation pipeline assembly 200 is partially located in the dewar tank 100, and partially protrudes outside the dewar tank 100, and circulates the cold liquid nitrogen for heat exchange;

[0011] Wherein, a multi-layer radiation baffle is provided in the dewar tank 100, and is located between the cover plate 110 of the dewar tank 100 and the liquid surface of the cold liquid nitrogen;

[0012] The circulation pipeline assembly 200 includes a heat exchanger 210, a liquid supply pipeline, a liquid return pipeline and a bypass pipeline; the two ends of the heat exchanger 210 are respectively connected to the liquid supply pipeline and the liquid return pipeline, and the other ends of the liquid supply pipeline and the liquid return pipeline are respectively connected; the two ends of the bypass pipeline are respectively connected to the liquid supply pipeline and the liquid return pipeline;

[0013] According to the cooling direction of the cold liquid nitrogen circulation, a flow meter 221, a low temperature switch valve 222, and a temperature sensor 223 are sequentially arranged on the liquid supply pipeline; and a temperature sensor 231, a low temperature switch valve 232, a flow meter 233 and a variable frequency liquid nitrogen circulation pump 234 are sequentially arranged on the liquid return pipeline; and a low temperature regulating valve 241 and a temperature sensor 3 242 are arranged on the bypass pipeline.

[0014] Advantages: By adding a bypass line to the liquid nitrogen supply pipeline, the bypass line is connected to the liquid nitrogen circuit, and a regulating valve is installed on the bypass line. The liquid nitrogen temperature at the outlet of the low-temperature demand equipment is monitored and real-time feedback is used to adjust the bypass line flow, thereby controlling the liquid nitrogen flow entering the equipment. In addition, the liquid nitrogen circulation pump adopts a variable frequency design, and the liquid nitrogen flow can also be adjusted according to the equipment outlet temperature, realizing two flow regulation functions. Therefore, the equipment can obtain stable low-temperature operating conditions and avoid the impact of temperature fluctuations on the equipment.

[0015] In one embodiment of the present invention, in the multi-layer radiation baffles, between adjacent radiation baffles and between the radiation baffles and the cover plate 110 are filled with a foamed insulation material.

[0016] In one embodiment of the present invention, the circulation pipeline assembly 200 includes a liquid supply purge vacuum pipeline and a liquid return purge vacuum pipeline;

[0017] One end of the liquid supply purge vacuum pipeline is located in the Dewar tank 100 and is connected to the liquid supply pipeline, and is connected to the pipeline between the low-temperature switch valve 222 and the temperature sensor 223; the other end of the liquid supply purge vacuum pipeline protrudes out of the Dewar tank 100 and is connected to a pressure sensor 251, and a ball valve 252 is provided on the side branch of the liquid supply purge vacuum pipeline, and a purge and vacuum interface 253 is provided at the end;

[0018] One end of the return liquid purge vacuum pipeline is located in the Dewar tank 100 and is connected to the return liquid pipeline, and is connected to the pipeline between the temperature sensor 231 and the low-temperature switch valve 232; the other end of the return liquid purge vacuum pipeline protrudes out of the Dewar tank 100 and is provided with a ball valve 261, and a purge and vacuum interface 262 is provided at the end.

[0019] In one embodiment of the present invention, the supercooled liquid nitrogen circulation cooling device also includes a liquid supply state stabilization auxiliary component 3456; the liquid supply state stabilization auxiliary component 3456 includes a liquid replenishment and pressure stabilization component; wherein the liquid replenishment component and the pressure stabilization component share a buffer tank 300, the buffer tank 300 is used to store the cold liquid nitrogen to be replenished, and the bottom of the buffer tank 300 is connected to the return liquid pipeline, and is connected to the pipeline between the low-temperature switch valve 232 and the variable frequency liquid nitrogen circulation pump 234.

[0020] In one embodiment of the present invention, the liquid replenishment assembly includes a liquid nitrogen supply pipe 410, a liquid replenishment filter 420, a liquid replenishment temperature sensor 430, a liquid replenishment low temperature regulating valve 440, a liquid replenishment low temperature switch valve 1 450, a liquid replenishment pressure sensor 460, a buffer tank level gauge 470 and a liquid replenishment low temperature switch valve 2 480;

[0021] One end of the liquid nitrogen supply pipe 410 is located in the Dewar tank 100, and the other end is located outside the Dewar tank 100; the liquid replenishment filter 420 is arranged on the liquid nitrogen supply pipe 410 and is located on the pipe section located in the Dewar tank 100, and then the liquid nitrogen supply pipe 410 is branched through a tee pipe, and one branch pipe leads into the buffer tank 300, and the liquid replenishment low temperature switch valve 450 is arranged on the branch pipeline, and the liquid replenishment low temperature regulating valve 440 and the liquid replenishment temperature sensor 430 are arranged on another branch pipeline;

[0022] The liquid replenishment pressure sensor 460 and the buffer tank level gauge 470 respectively detect the pressure and liquid level of the cold liquid nitrogen in the buffer tank 300; and the liquid replenishment low-temperature switch valve 2 480 is arranged on the exhaust pipeline connected to the buffer tank 300.

[0023] In one embodiment of the present invention, the voltage stabilizing assembly includes a voltage stabilizing tube, a low temperature heating resistor 510, an inflating voltage stabilizing electric valve 520 and an exhaust voltage stabilizing electric valve 530;

[0024] The heating end of the low-temperature heating resistor 510 is located in the buffer tank 300; one end of the voltage regulator tube extends into the buffer tank 300, and the voltage regulator tube is provided with a first voltage regulator branch tube and a second voltage regulator branch tube in communication;

[0025] The inflation pressure-stabilizing electric valve 520 is arranged on the first pressure-stabilizing branch pipe, and a helium inlet 521 is arranged at the end of the first pressure-stabilizing branch pipe;

[0026] The exhaust pressure stabilizing electric valve 530 is arranged on the second pressure stabilizing branch pipe, and a helium exhaust port 531 is arranged at the end of the second pressure stabilizing branch pipe.

[0027] In one embodiment of the present invention, the liquid supply state stabilization auxiliary component 3456 includes a ball valve 3 610 , a safety bursting disk 2 620 , and a safety valve 3 630 ;

[0028] The voltage stabilizing tube is provided with a third voltage stabilizing branch tube and a fourth voltage stabilizing branch tube which are connected to each other;

[0029] The third ball valve 610 is arranged on the third voltage-stabilizing branch pipe, and a third purge and vacuuming interface 611 is arranged at the end of the third voltage-stabilizing branch pipe;

[0030] The third safety valve 630 is arranged on the fourth voltage-stabilizing branch pipe; and the second safety bursting membrane 620 is connected to the other end of the voltage-stabilizing pipe.

[0031] In one embodiment of the present invention, the subcooled liquid nitrogen circulation cooling device includes a vaporization exhaust assembly, which includes a nitrogen exhaust pipe, a nitrogen exhaust heater 710 and a vaporization thermometer 720;

[0032] The nitrogen exhaust pipe is in communication with the dewar 100 to exhaust the nitrogen in the dewar 100 , and the nitrogen exhaust heater 710 and the vaporization temperature meter 720 are disposed on the nitrogen exhaust pipe.

[0033] In one embodiment of the present invention, the circulation pipeline assembly 200 includes a temperature recovery assembly, which is arranged in the Dewar tank 100, including a liquid nitrogen internal discharge pipe and a liquid nitrogen discharge low-temperature switch valve 280; wherein the liquid nitrogen internal discharge pipe is connected to the liquid return pipeline, the connection position is on the pipeline between the temperature sensor 231 and the low-temperature switch valve 232, and the liquid nitrogen discharge low-temperature switch valve 280 is arranged on the liquid nitrogen internal discharge pipe.

[0034] The present invention also provides a method for using a supercooled liquid nitrogen circulating cooling device, comprising: connecting the liquid inlet and the liquid outlet of the load device A to the other ends of the liquid supply pipeline and the liquid return pipeline respectively;

[0035] After the subcooled liquid nitrogen in the liquid supply pipeline and the liquid return pipeline is cooled by the heat exchanger 210, it is sent to the load device A by means of the variable frequency liquid nitrogen circulation pump 234. After the subcooled liquid nitrogen absorbs the heat of the load device A, it returns to the heat exchanger 210, and the subcooled liquid nitrogen is basically circulated;

[0036] When the heat load of the load device A changes, the flow rates of the liquid supply pipeline and the liquid return pipeline are adjusted according to the temperature signal fed back by the temperature sensor 231, including:

[0037] Traffic adjustment method 1:

[0038] When it is necessary to reduce the liquid supply flow rate, the opening of the low temperature regulating valve 241 is increased to allow a portion of the subcooled liquid nitrogen in the liquid supply pipeline to flow directly into the liquid return pipeline, thereby reducing the flow rate of the liquid supply pipeline; conversely, when the liquid supply flow rate is increased, the opening of the low temperature regulating valve 241 is reduced;

[0039] Traffic adjustment method 2:

[0040] Control the output frequency of the variable frequency liquid nitrogen circulation pump 234 to control the rotation speed of the variable frequency liquid nitrogen circulation pump 234, and further control the flow rates of the liquid supply pipeline and the liquid return pipeline;

[0041] During adjustment, the data of flow meter 1 221, temperature sensor 1 223, temperature sensor 2 231, flow meter 2 233, temperature sensor 3 242, the opening of cryogenic switch valve 1 222, cryogenic switch valve 2 232, cryogenic regulating valve 1 241 and the frequency data of variable frequency liquid nitrogen circulation pump 234 are recorded for analyzing the system status.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] In order to ensure that the liquid nitrogen always maintains a liquid state during heat exchange in the pipeline, the pipeline pressure is increased to above 2 bar, and the liquid nitrogen always maintains a supercooled state in the circulation pipeline. After the liquid nitrogen in the circulation pipeline absorbs heat, it exchanges heat with the normal-pressure liquid nitrogen in the tank through the heat exchanger. The heat exchanger is immersed in liquid nitrogen, and the heat is taken away by the vaporization of the normal-pressure liquid nitrogen in the tank. The low-temperature nitrogen generated is discharged into the environment after heating. The liquid nitrogen pressure of the circulation system can be controlled by the buffer tank. There are two ways to adjust the pressure. One is to heat the liquid in the buffer tank by a low-temperature heating wire to vaporize and pressurize it, and the other is to pressurize it by introducing helium.

[0044] The liquid level information is collected through the liquid level sensor and uploaded to the control system to control the opening and closing of the valve of the liquid filling pipe. The liquid level gauge in the atmospheric pressure tank ensures that the heat exchanger is completely immersed in the atmospheric pressure liquid nitrogen, thereby achieving a good heat exchange effect; the liquid level gauge in the high-pressure buffer tank ensures that the liquid is replenished in time when the liquid level in the buffer tank is insufficient. When the unit starts to add liquid nitrogen, it is necessary to purge the pipeline with 99.999% high-purity nitrogen to discharge the air and moisture in the pipeline, and then use a vacuum pump to evacuate the pipeline to ensure that no air enters the pipeline.

[0045] Different purge and vacuum modes can be realized. When the system does not return to temperature, the load equipment can be returned to temperature separately and replaced, which effectively reduces liquid nitrogen consumption and time costs.

[0046] You can run a self-test before each work, and then connect it to the load device after it is reliable to prevent damage to the load equipment.

[0047] Multiple flow regulation methods, efficient flow regulation, small fluctuation of supercooled liquid nitrogen, ensure the operation stability of load equipment. Multiple pressure stabilization methods, efficient pressure regulation, small fluctuation of supercooled liquid nitrogen pressure, ensure the operation stability of load equipment.

[0048] The heat insulation design is adopted inside the tank, which can effectively ensure that no condensation water is generated on the cover during operation, and can reduce the loss of liquid nitrogen in the device. The U-shaped elbow design can reduce the loss of liquid nitrogen and ensure that the sensor can work within the normal temperature range.

[0049] It has a high degree of automation, efficient and stable operation, high reliability, high safety factor, strong feasibility and strong practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of a supercooled liquid nitrogen circulating cooling device according to an embodiment of the present invention.

[0051] Figure 2 Schematic diagram of a multi-layer radiation shield according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0053] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0054] See also Figure 1 As shown, the present invention provides a supercooled liquid nitrogen circulation cooling device, including a dewar tank 100 and a circulation pipeline assembly 200; the dewar tank 100 stores cold liquid nitrogen, and the circulation pipeline assembly 200 is partially located in the dewar tank 100 and partially protrudes outside the dewar tank 100, and circulates the cold liquid nitrogen for heat exchange.

[0055] The dewar 100 is provided with a multi-layer radiation baffle, which is located between the cover plate 110 of the dewar 100 and the liquid surface of the cold liquid nitrogen. The circulation pipeline assembly 200 includes a heat exchanger 210, a liquid supply pipeline, a liquid return pipeline and a bypass pipeline. The two ends of the heat exchanger 210 are respectively connected to the liquid supply pipeline and the liquid return pipeline, and the other ends of the liquid supply pipeline and the liquid return pipeline are connected; the two ends of the bypass pipeline are respectively connected to the liquid supply pipeline and the liquid return pipe.

[0056] According to the cooling direction of the cold liquid nitrogen circulation, the liquid supply pipeline is provided with a flow meter 221, a low temperature switch valve 222, and a temperature sensor 223 in sequence; and the return liquid pipeline is provided with a temperature sensor 231, a low temperature switch valve 232, a flow meter 233 and a variable frequency liquid nitrogen circulation pump 234 in sequence, and the bypass pipeline is provided with a low temperature regulating valve 241 and a temperature sensor 3 242. In addition, a return liquid filter 235 is also provided on the return liquid pipeline, and the return liquid filter 235 is located on the pipeline before the supercooled liquid nitrogen returns to the variable frequency liquid nitrogen circulation pump 234.

[0057] See also Figure 1 and Figure 2 As shown, in one embodiment of the present invention, a safety valve 111 is provided on the cover plate 110. Also, the multi-layer radiation baffle includes a first layer radiation baffle 121, a second layer radiation baffle 122 and a third layer radiation baffle 123. In the multi-layer radiation baffle, foamed insulation material is filled between adjacent radiation baffles and between the radiation baffle and the cover plate 110. The multi-layer radiation baffle design can effectively reduce the radiation heat exchange between the low-temperature liquid nitrogen and the cover plate 110, avoid condensation and dew on the cover plate 110 due to the low temperature, generate condensed water, affect the normal operation of the experiment, and reduce the loss of liquid nitrogen.

[0058] In this embodiment, the filling of the foam insulation material can limit the flow of low-temperature nitrogen, and the nitrogen that has exchanged heat with the cover plate 110 will also be limited near the cover plate 110, and the low-temperature gas is not easy to flow in, thereby hindering the heat exchange between the low-temperature nitrogen and the cover plate 110. The above two methods can effectively ensure that the cover plate 110 will not have condensed water during operation, and also reduce the loss of liquid nitrogen.

[0059] See also Figure 1 As shown, in one embodiment of the present invention, the circulation pipeline assembly 200 further includes a liquid supply purge vacuum pipeline, a liquid return purge vacuum pipeline, a circulation pipeline safety assembly and a temperature return assembly.

[0060] In this embodiment, one end of the liquid supply purge vacuum pipeline is located in the dewar tank 100 and is connected to the liquid supply pipeline, and is connected to the pipeline between the low temperature switch valve 222 and the temperature sensor 223. The other end of the liquid supply purge vacuum pipeline protrudes out of the dewar tank 100 and is connected to a pressure sensor 251, and a ball valve 252 is provided on the side branch of the liquid supply purge vacuum pipeline, and a purge and vacuum interface 253 is provided at the end.

[0061] In this embodiment, one end of the liquid return purge vacuum pipeline is located in the dewar tank 100 and is connected to the liquid return pipeline, and is connected to the pipeline between the second temperature sensor 231 and the second low-temperature switch valve 232. The other end of the liquid return purge vacuum pipeline protrudes out of the dewar tank 100 and is provided with a second ball valve 261, and a second purge and vacuum interface 262 is provided at the end.

[0062] In this embodiment, the circulation pipeline safety component includes a safety bursting membrane 1 271 and a safety valve 272. The safety bursting membrane 1 271 and the safety valve 2 272 are located outside the dewar tank 100 and are arranged on the liquid return purge vacuum pipeline.

[0063] In this embodiment, the temperature recovery component is arranged in the dewar tank 100, and includes a liquid nitrogen inner discharge pipe and a liquid nitrogen discharge low temperature switch valve 280. The liquid nitrogen inner discharge pipe is connected with the liquid return pipeline, and the connection position is on the pipeline between the temperature sensor 231 and the low temperature switch valve 232, and the liquid nitrogen discharge low temperature switch valve 280 is arranged on the liquid nitrogen inner discharge pipe.

[0064] See also Figure 1 As shown, in one embodiment of the present invention, the supercooled liquid nitrogen circulation cooling device further includes a liquid supply state stabilization auxiliary component 3456. The liquid supply state stabilization auxiliary component 3456 includes a liquid replenishment and a pressure stabilization component. Among them, the liquid replenishment component and the pressure stabilization component share a buffer tank 300, and the buffer tank 300 is used to store the cold liquid nitrogen to be replenished, and the bottom of the buffer tank 300 is connected to the liquid return pipeline, and is connected to the pipeline between the low temperature switch valve 232 and the variable frequency liquid nitrogen circulation pump 234.

[0065] In this embodiment, the liquid replenishment component includes a liquid nitrogen supply pipe 410, a liquid replenishment filter 420, a liquid replenishment temperature sensor 430, a liquid replenishment low-temperature regulating valve 440, a liquid replenishment low-temperature switch valve 1 450, a liquid replenishment pressure sensor 460, a buffer tank level gauge 470 and a liquid replenishment low-temperature switch valve 2 480.

[0066] One end of the liquid nitrogen supply pipe 410 is located in the dewar tank 100, and the other end is located outside the dewar tank 100; the liquid replenishment filter 420 is arranged on the liquid nitrogen supply pipe 410 and is located on the pipe section located in the dewar tank 100, and then the liquid nitrogen supply pipe 410 is branched through a tee pipe, and one branch pipe is connected to the buffer tank 300, and the liquid replenishment cryogenic switch valve 1 450 is arranged on the branch pipeline, and the liquid replenishment cryogenic regulating valve 440 and the liquid replenishment temperature sensor 430 are arranged on another branch pipeline. The liquid replenishment pressure sensor 460 and the buffer tank liquid level gauge 470 respectively detect the pressure and liquid level of the cold liquid nitrogen in the buffer tank 300, and the liquid replenishment cryogenic switch valve 2 480 is arranged on the exhaust pipeline connected to the buffer tank 300.

[0067] In this embodiment, the voltage stabilizing assembly includes a voltage stabilizing tube, a low-temperature heating resistor 510 , an inflation voltage stabilizing electric valve 520 , and an exhaust voltage stabilizing electric valve 530 .

[0068] The heating end of the low-temperature heating resistor 510 is located in the buffer tank 300, one end of the voltage regulator tube extends into the buffer tank 300, and the voltage regulator tube is provided with a first voltage regulator branch pipe and a second voltage regulator branch pipe that are connected. The charging voltage regulator electric valve 520 is provided on the first voltage regulator branch pipe, and a helium inlet 521 is provided at the end of the first voltage regulator branch pipe. The exhaust voltage regulator electric valve 530 is provided on the second voltage regulator branch pipe, and a helium exhaust port 531 is provided at the end of the second voltage regulator branch pipe.

[0069] In this embodiment, the liquid supply state stabilization auxiliary component 3456 includes a ball valve 3 610, a safety bursting membrane 2 620 and a safety valve 3 630. The voltage regulator tube is provided with a third voltage stabilization branch pipe and a fourth voltage stabilization branch pipe connected to each other, the ball valve 3 610 is provided on the third voltage stabilization branch pipe, and a purge and vacuum interface 3 611 is provided at the end of the third voltage stabilization branch pipe, and the safety valve 3 630 is provided on the fourth voltage stabilization branch pipe. And, the safety bursting membrane 2 620 is connected to the other end of the voltage regulator tube. Among them, the third voltage stabilization branch pipe, the ball valve 3 610 and the purge and vacuum interface 3 611 are used to realize the purge and vacuum functions of the liquid supply state stabilization auxiliary component 3456, and the fourth voltage stabilization branch pipe, the safety bursting membrane 2 620 and the safety valve 3 630 constitute the safety monitoring function of the liquid supply state stabilization auxiliary component 3456.

[0070] See also Figure 1 As shown, in one embodiment of the present invention, the subcooled liquid nitrogen circulation cooling device further includes a vaporization exhaust assembly, which includes a nitrogen exhaust pipe, a nitrogen exhaust heater 710 and a vaporization thermometer 720. The nitrogen exhaust pipe is connected to the dewar 100 to exhaust the nitrogen in the dewar 100, and the nitrogen exhaust heater 710 and the vaporization thermometer 720 are arranged on the nitrogen exhaust pipe.

[0071] See also Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the supercooled liquid nitrogen circulation cooling device further includes a dewar tank level gauge 800 and a controller 900. The dewar tank level gauge 800 measures the liquid level of the supercooled liquid nitrogen in the dewar tank 100. The controller 900 is connected to all valves, such as a cryogenic switch valve, a cryogenic regulating valve, a safety valve, a safety bursting disk, etc., and sensors such as a temperature sensor, a pressure sensor, a flow meter, etc. in communication.

[0072] In this embodiment, the low-temperature switch valve is connected to the pipeline by welding, the heat exchanger 210 is connected to the pipeline by welding, the variable frequency liquid nitrogen circulation pump 234 is connected to the pipeline by welding, the safety valve and the liquid level sensor are fixed to the cover plate by external threads, and the safety bursting membrane and the purge interface are connected to the pipeline by threads.

[0073] In this embodiment, the supercooled liquid nitrogen cooled by the heat exchanger 210 is sent to the load device A through the variable frequency liquid nitrogen circulation pump 234. The supercooled liquid nitrogen absorbs the heat of the load device A and then returns to the heat exchanger 210. The atmospheric pressure liquid nitrogen in the Dewar tank 100 absorbs the heat in the heat exchanger by evaporation. The vaporized liquid nitrogen is heated by the nitrogen exhaust heater 710 and then discharged. The nitrogen exhaust heater 710 automatically adjusts the heating power according to the temperature collected by the vaporization thermometer 720 at the outlet.

[0074] See also Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the connecting pipe of the sensor in the circulation pipeline assembly 200 and the liquid supply state stabilization auxiliary assembly 3456 and protruding outside the Dewar tank 100 adopts a U-shaped design, and the U-shaped elbow is located below the cover plate 110 and between the multi-layer radiation baffles, such as Figure 2 The connecting pipe 46 of the replenishment pressure sensor 460, the connecting pipe of the buffer tank level gauge 470, the connecting pipe of the pressure sensor 251, and the connecting pipe of the Dewar tank level gauge 800. The U-shaped design can effectively increase the length of the pipeline. Increasing the length can not only ensure that the cold energy remains in the tank body as much as possible, but also use the nitrogen in the pipeline to isolate the external heat from being transferred to the internal circulating liquid nitrogen, reduce the loss of liquid nitrogen, and ensure that the sensor works within the working temperature range.

[0075] See also Figure 1 and Figure 2 As shown, the present invention also provides a method for using a supercooled liquid nitrogen circulating cooling device, comprising: connecting the liquid inlet and outlet of the load device A to the other ends of the liquid supply pipeline and the liquid return pipeline respectively.

[0076] System operation modes include flow control, voltage stabilization control, fluid replenishment control, and vaporization control.

[0077] After being cooled by the heat exchanger 210, the supercooled liquid nitrogen in the liquid supply pipeline and the liquid return pipeline is sent to the load device A by means of the variable frequency liquid nitrogen circulation pump 234. After the supercooled liquid nitrogen absorbs the heat of the load device A, it returns to the heat exchanger 210, and the circulation of the supercooled liquid nitrogen is basically completed.

[0078] In order to ensure the stable operation of load device A, it is necessary to ensure that the cooling capacity is balanced with the demand, so the cooling capacity needs to be adjusted in real time. When the heat load of load device A changes, the flow of the liquid supply pipeline and the liquid return pipeline is adjusted according to the temperature signal fed back by the temperature sensor 231, including:

[0079] Traffic adjustment method 1:

[0080] When it is necessary to reduce the liquid supply flow rate, the opening of the low temperature regulating valve 241 is increased to allow a portion of the subcooled liquid nitrogen in the liquid supply pipeline to flow directly into the liquid return pipeline, thereby reducing the flow rate of the liquid supply pipeline; conversely, when the liquid supply flow rate is increased, the opening of the low temperature regulating valve 241 is reduced;

[0081] Traffic adjustment method 2:

[0082] The output frequency of the variable frequency liquid nitrogen circulation pump 234 is controlled to control the rotation speed of the variable frequency liquid nitrogen circulation pump 234, thereby controlling the flow rates of the liquid supply pipeline and the liquid return pipeline.

[0083] During adjustment, the data of flow meter 1 221, temperature sensor 1 223, temperature sensor 2 231, flow meter 2 233, temperature sensor 3 242, and the opening of low temperature switch valve 1 222, low temperature switch valve 2 232, low temperature regulating valve 1 241 and the frequency data of variable frequency liquid nitrogen circulation pump 234 are recorded for analyzing the system status. These collected data can be used to judge the operating status and be kept as a data set for follow-up to find the dynamic relationship between the heat load of load device A and the valve opening, the frequency of variable frequency liquid nitrogen circulation pump 234, etc., to achieve precise control. Combined with the above system functions, it can effectively reduce the temperature fluctuation of the working environment of load device A and ensure its normal operation.

[0084] Voltage regulation:

[0085] The pressure of the supercooled liquid nitrogen circulation pipeline is maintained above 2 bar, and the pressure is stabilized and liquid is replenished through the buffer tank 300 to ensure that the pipeline is always full of supercooled liquid nitrogen. There are two ways to design the pressure stabilization of the buffer tank 300.

[0086] Voltage stabilization control method 1:

[0087] The low temperature heating resistor 510 heats the liquid nitrogen, causing the liquid nitrogen to vaporize and increase the pressure of the buffer tank 300 .

[0088] Voltage stabilization control method 2:

[0089] Helium is introduced into the helium inlet 521, and the gas charging and pressure-stabilizing electric valve 520 is opened to pressurize the supercooled liquid nitrogen circulating cooling system. If the pipeline pressure condition in the supercooled liquid nitrogen circulating cooling system is met, the gas charging and pressure-stabilizing electric valve 520 is opened to discharge the excess helium in the pipeline through the helium exhaust port 531.

[0090] When the buffer tank liquid level gauge 470 detects that the liquid level is lower than the set value, the liquid replenishment cryogenic switch valve 1 450 is opened to replenish the liquid until the liquid level is higher than the safety value; if the liquid replenishment pressure sensor 460 detects that the pressure value of the supercooled liquid nitrogen circulation cooling system is higher than the set value, the liquid replenishment cryogenic switch valve 2 480 is opened to discharge nitrogen into the Dewar tank 100.

[0091] Combining the above methods, the pressure of the liquid in the closed subcooled liquid nitrogen circulation pipeline can be quickly controlled to maintain a stable pressure in the pipeline.

[0092] Fluid regulation:

[0093] In this embodiment, when the Dewar tank liquid level meter 800 detects that the liquid level in the Dewar tank 100 is lower than the set value, the liquid replenishment low temperature regulating valve 440 is opened to replenish the liquid, and the liquid replenishment temperature is measured by the liquid replenishment temperature sensor 430. The heat exchanger 210 is completely immersed in the liquid nitrogen in the Dewar tank 100, ensuring a good heat exchange effect.

[0094] Vaporization control:

[0095] In this embodiment, the vaporized liquid nitrogen is heated by the nitrogen discharge heater 710 and then discharged. The nitrogen discharge heater 710 automatically adjusts the heating power according to the temperature collected by the vaporization thermometer 720 at the outlet. When the outlet temperature is lower than the set value, the controller controls the nitrogen discharge heater 710 to increase the heating power to increase the discharge nitrogen temperature, and vice versa.

[0096] System purging and vacuuming:

[0097] In this embodiment, before the system is filled with liquid nitrogen, the entire closed subcooled liquid nitrogen circulation cooling system needs to be purged and evacuated to avoid the influence of impurities, air and moisture on the pipeline.

[0098] Purge and vacuum mode 1:

[0099] Connect 99.999% nitrogen to the purge and vacuum interface three 611, open the ball valve three 610, the low-temperature switch valve one 222, the low-temperature switch valve two 232, and the ball valve two 261; close the liquid replenishment low-temperature switch valve one 450, the liquid replenishment low-temperature switch valve two 480, the low-temperature regulating valve one 241, the liquid nitrogen discharge low-temperature switch valve 280, the charging pressure-stabilizing electric valve 520, the exhaust pressure-stabilizing electric valve 530 and the ball valve one 252, and carry out purging.

[0100] After purging for a period of time, close ball valve three 610 and ball valve two 261, connect the purging and vacuuming interface two 262 to the vacuum pump, open ball valve two 261 to vacuum the system, then close ball valve two 261 and disconnect from the vacuum pump to complete the purging and evacuation of the entire system.

[0101] Purge and vacuum mode 2:

[0102] In this embodiment, if the load device A needs to be replaced during system operation, it is only necessary to evacuate and purge the new load device A and part of the connecting pipelines. The details are as follows:

[0103] The purge and vacuum interface 1 253 is connected to 99.999% nitrogen, the low-temperature switch valve 232 and the low-temperature switch valve 1 222 are closed, and the ball valve 261 and the ball valve 1 252 are opened to achieve the purge of the new load device A.

[0104] After purging for a period of time, close the second ball valve 261 and the first ball valve 252, connect the second purging and vacuuming interface 262 to the vacuum pump, open the second ball valve 261 to vacuum the system, and then close the second ball valve 261 to disconnect the vacuum pump to complete the purging and vacuuming of the new load device A. When the experiment is over, the load device can also be quickly warmed up in this way.

[0105] System self-check mode:

[0106] In this embodiment, when the system is filled with liquid nitrogen and starts to circulate, the low-temperature switch valve 222 and the low-temperature switch valve 232 are closed first, and the low-temperature regulating valve 241 is opened to realize self-circulation of the system in the unit, cool itself first to ensure the stable self-circulation operation of the system, and when the temperature collected by the temperature sensor 3 242 meets the requirements, the low-temperature switch valve 222 and the low-temperature switch valve 232 will be opened at this time, and the opening of the low-temperature regulating valve 241 will be reduced to supply cooling capacity to the load equipment A.

[0107] System reheating mode:

[0108] In this embodiment, when the system needs to be warmed up, the liquid nitrogen in the circulation pipeline needs to be discharged. By opening the liquid nitrogen discharge low temperature switch valve 280, closing the low temperature regulating valve 1 241 and the low temperature switch valve 2 232, the liquid nitrogen is transported to the Dewar tank 100 by the variable frequency liquid nitrogen circulation pump 234, and then vaporized and discharged. Then open the ball valve 3 610, the ball valve 2 261 and the ball valve 1 252, and the nitrogen gas vaporized from the residual liquid nitrogen in the pipeline can be discharged faster.

[0109] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0110] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A supercooled liquid nitrogen circulating cooling device, characterized in that: include: A dewar tank (100) and a circulation pipeline assembly (200); cold liquid nitrogen is stored in the dewar tank (100); the circulation pipeline assembly (200) is partially located in the dewar tank (100) and partially protrudes outside the dewar tank (100), and circulates the cold liquid nitrogen for heat exchange; A multi-layer radiation baffle is provided in the dewar tank (100), and is located between the cover plate (110) of the dewar tank (100) and the liquid surface of the cold liquid nitrogen; The circulation pipeline assembly (200) comprises a heat exchanger (210), a liquid supply pipeline, a liquid return pipeline and a bypass pipeline; two ends of the heat exchanger (210) are respectively connected to the liquid supply pipeline and the liquid return pipeline, and the other ends of the liquid supply pipeline and the liquid return pipeline are respectively connected; two ends of the bypass pipeline are respectively connected to the liquid supply pipeline and the liquid return pipeline; According to the cooling direction of the cold liquid nitrogen circulation, a flow meter 1 (221), a low temperature switch valve 1 (222), and a temperature sensor 1 (223) are sequentially arranged on the liquid supply pipeline; and a temperature sensor 2 (231), a low temperature switch valve 2 (232), a flow meter 2 (233) and a variable frequency liquid nitrogen circulation pump (234) are sequentially arranged on the liquid return pipeline; and a low temperature regulating valve 1 (241) and a temperature sensor 3 (242) are arranged on the bypass pipeline.

2. The subcooled liquid nitrogen circulating cooling device according to claim 1, characterized in that: In the multi-layer radiation shielding plate, the spaces between adjacent radiation shielding plates and between the radiation shielding plates and the cover plate (110) are filled with foamed heat insulating materials.

3. The subcooled liquid nitrogen circulating cooling device according to claim 1, characterized in that: The circulation pipeline assembly (200) comprises a liquid supply purge vacuum pipeline and a liquid return purge vacuum pipeline; One end of the liquid supply purge vacuum pipeline is located in the Dewar tank (100) and is connected to the liquid supply pipeline, and is connected to the pipeline between the low-temperature switch valve (222) and the temperature sensor (223); the other end of the liquid supply purge vacuum pipeline protrudes out of the Dewar tank (100) and is connected to a pressure sensor (251); a ball valve (252) is provided on the side branch of the liquid supply purge vacuum pipeline, and a purge and vacuum interface (253) is provided at the end; One end of the liquid return purge vacuum pipeline is located in the Dewar tank (100) and is connected to the liquid return pipeline, and is connected to the pipeline between the second temperature sensor (231) and the second low-temperature switch valve (232); the other end of the liquid return purge vacuum pipeline protrudes out of the Dewar tank (100) and is provided with a second ball valve (261), and the end is provided with a second purge and vacuum interface (262).

4. The subcooled liquid nitrogen circulation cooling device according to claim 1, characterized in that: The supercooled liquid nitrogen circulation cooling device also includes a liquid supply state stabilization auxiliary component (3456); the liquid supply state stabilization auxiliary component (3456) includes a liquid replenishment and pressure stabilization component; wherein the liquid replenishment component and the pressure stabilization component share a buffer tank (300), the buffer tank (300) is used to store cold liquid nitrogen to be replenished, and the bottom of the buffer tank (300) is connected to the liquid return pipeline and is connected to the pipeline between the second low-temperature switch valve (232) and the variable frequency liquid nitrogen circulation pump (234).

5. The subcooled liquid nitrogen circulation cooling device according to claim 4, characterized in that: The liquid replenishment component comprises a liquid nitrogen supply pipe (410), a liquid replenishment filter (420), a liquid replenishment temperature sensor (430), a liquid replenishment low temperature regulating valve (440), a liquid replenishment low temperature switch valve 1 (450), a liquid replenishment pressure sensor (460), a buffer tank liquid level gauge (470) and a liquid replenishment low temperature switch valve 2 (480); One end of the liquid nitrogen supply pipe (410) is located in the dewar tank (100), and the other end is located outside the dewar tank (100); the liquid replenishment filter (420) is arranged on the liquid nitrogen supply pipe (410) and is located on the pipe section located in the dewar tank (100); the liquid nitrogen supply pipe (410) is branched through a tee pipe, and one branch pipe leads into the buffer tank (300); a liquid replenishment low temperature switch valve (450) is arranged on the branch pipe, and a liquid replenishment low temperature regulating valve (440) and a liquid replenishment temperature sensor (430) are arranged on another branch pipe; The liquid replenishment pressure sensor (460) and the buffer tank liquid level meter (470) respectively detect the pressure and liquid level of the cold liquid nitrogen in the buffer tank (300); and the second liquid replenishment low-temperature switch valve (480) is arranged on the exhaust pipeline connected to the buffer tank (300).

6. The subcooled liquid nitrogen circulating cooling device according to claim 4, characterized in that: The voltage stabilizing component comprises a voltage stabilizing tube, a low-temperature heating resistor (510), an air charging voltage stabilizing electric valve (520) and an exhaust voltage stabilizing electric valve (530); The heating end of the low-temperature heating resistor (510) is located in the buffer tank (300); one end of the voltage-stabilizing tube extends into the buffer tank (300), and the voltage-stabilizing tube is provided with a first voltage-stabilizing branch tube and a second voltage-stabilizing branch tube that are connected to each other; The inflation pressure-stabilizing electric valve (520) is arranged on the first pressure-stabilizing branch pipe, and a helium inlet (521) is arranged at the end of the first pressure-stabilizing branch pipe; The exhaust pressure stabilizing electric valve (530) is arranged on the second pressure stabilizing branch pipe, and a helium exhaust port (531) is arranged at the end of the second pressure stabilizing branch pipe.

7. The subcooled liquid nitrogen circulation cooling device according to claim 6, characterized in that: The liquid supply state stabilization auxiliary component (3456) includes a ball valve three (610), a safety bursting membrane two (620) and a safety valve three (630); The voltage stabilizing tube is provided with a third voltage stabilizing branch tube and a fourth voltage stabilizing branch tube which are connected to each other; The ball valve three (610) is arranged on the third pressure-stabilizing branch pipe, and a purge and vacuuming interface three (611) is arranged at the end of the third pressure-stabilizing branch pipe; The third safety valve (630) is arranged on the fourth voltage-stabilizing branch pipe; and the second safety bursting membrane (620) is connected to the other end of the voltage-stabilizing pipe.

8. The subcooled liquid nitrogen circulating cooling device according to claim 1, characterized in that: The supercooled liquid nitrogen circulation cooling device comprises a vaporization exhaust component, and the vaporization exhaust component comprises a nitrogen exhaust pipe, a nitrogen exhaust heater (710) and a vaporization thermometer (720); The nitrogen discharge pipe is in communication with the Dewar (100) for discharging the nitrogen in the Dewar (100), and the nitrogen discharge heater (710) and the vaporization temperature meter (720) are arranged on the nitrogen discharge pipe.

9. The subcooled liquid nitrogen circulating cooling device according to claim 3, characterized in that: The circulation pipeline assembly (200) comprises a temperature recovery assembly, which is arranged in the Dewar tank (100) and comprises a liquid nitrogen internal discharge pipe and a liquid nitrogen discharge low temperature switch valve (280); wherein the liquid nitrogen internal discharge pipe is connected to the liquid return pipeline, the connection position is located on the pipeline between the second temperature sensor (231) and the second low temperature switch valve (232), and the liquid nitrogen discharge low temperature switch valve (280) is arranged on the liquid nitrogen internal discharge pipe.

10. A method for using the supercooled liquid nitrogen circulating cooling device according to any one of claims 1 to 9, characterized in that: include: Connect the liquid inlet and outlet of the load device (A) to the other end of the liquid supply pipeline and the liquid return pipeline respectively; After the subcooled liquid nitrogen in the liquid supply pipeline and the liquid return pipeline is cooled by the heat exchanger (210), it is sent to the load device (A) by means of a variable frequency liquid nitrogen circulation pump (234). After the subcooled liquid nitrogen absorbs the heat of the load device (A), it returns to the heat exchanger (210), and the subcooled liquid nitrogen is basically circulated; When the heat load of the load device (A) changes, the flow rates of the liquid supply pipeline and the liquid return pipeline are adjusted according to the temperature signal fed back by the temperature sensor 2 (231), including: Traffic adjustment method 1: When it is necessary to reduce the liquid supply flow rate, the opening of the low temperature regulating valve 1 (241) is increased to allow a portion of the subcooled liquid nitrogen in the liquid supply pipeline to flow directly into the liquid return pipeline, thereby reducing the flow rate of the liquid supply pipeline; conversely, when increasing the liquid supply flow rate, the opening of the low temperature regulating valve 1 (241) is reduced; Traffic adjustment method 2: Controlling the output frequency of the variable frequency liquid nitrogen circulation pump (234) to control the rotation speed of the variable frequency liquid nitrogen circulation pump (234), thereby controlling the flow rates of the liquid supply pipeline and the liquid return pipeline; During adjustment, data of flow meter 1 (221), temperature sensor 1 (223), temperature sensor 2 (231), flow meter 2 (233), temperature sensor 3 (242), openings of cryogenic switch valve 1 (222), cryogenic switch valve 2 (232), cryogenic regulating valve 1 (241), and frequency data of variable frequency liquid nitrogen circulation pump (234) are recorded for use in analyzing system status.

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