Continuous air supply type micro throttling refrigeration system and refrigeration method thereof

Abstract

The invention relates to a continuous air supply type micro throttling refrigeration system and a refrigeration method thereof, and the refrigeration system comprises an inflation unit, a double-main-air-cylinder buffer unit and a refrigeration Dewar with a temperature control module, the double-main-gas-cylinder buffer unit comprises a main gas cylinder with a pressure release valve, a stop valve, a buffer cylinder, a pressure regulating valve with a pressure detection module, a purifier and a diaphragm valve which are sequentially connected in the gas supply direction, and an external flow channel port of the pressure release valve selectively communicates with the inflation unit and the stop valve; and the refrigeration dewar is detachably connected with the diaphragm valve. Through the buffering design of the double main gas cylinders, on the premise that the size of the refrigerating system is kept small, the main gas cylinders can be replaced in the working stage of the refrigerating system, zero-temperature-rise continuous refrigerating is achieved, and the beneficial effects that refrigerating interruption is avoided, and the pollution risk is reduced are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration systems, in particular to a continuous gas supply type micro-throttling refrigeration system and a refrigeration method thereof. BACKGROUND

[0002] In the field of modern science and technology, especially in the military, aerospace, medical imaging and scientific research, the application of liquid nitrogen temperature zone cryogenic detectors is increasingly widespread. These detectors, such as refrigeration type infrared detectors and high-performance CCDs, need to be in a low-temperature environment to maintain their performance stability and reliability. In order to achieve this goal, current methods mainly rely on liquid nitrogen refrigeration Dewar containers or Stirling refrigerators. Although the liquid nitrogen refrigeration Dewar container can provide a stable low-temperature environment, its use is limited by the tank volume (usually 1-5L) and the ice blocking effect of the pipeline, resulting in an effective working time of usually no more than 3h. While the Stirling refrigerator can achieve continuous operation for thousands of hours, its high cost (≥300,000 yuan) becomes an obstacle to its popularization and application.

[0003] Micro-throttling refrigeration technology (MJT) as an emerging technology, through micro-electromechanical manufacturing process, integrates micron-scale flow channels in multiple glass substrates, and uses the throttling effect of high-pressure gas working medium (such as nitrogen) to achieve single-stage refrigeration, with a working temperature range of 80-120K. This technology has the advantages of small size, low vibration and low gas consumption, but its open refrigeration system needs continuous gas supply, with a typical consumption rate of about 20mg / s. Relying on high-pressure main gas cylinder for gas supply, it can support continuous operation for more than a week, but its gas circuit refrigeration system contains more than 7 valves and supporting pressure regulating, purification, temperature control modules, resulting in the refrigeration system volume increasing several times compared to the core refrigeration element, which limits its application in space-limited scenarios. At present, the applicant has improved the small-sized low-temperature gas purification and pressure control device, reduced the number of valves to 5 by optimizing the purification gas path flow direction and pipeline layout, reduced the purification structure volume by more than 50%, and developed a micro-temperature control module based on single-chip microcomputer serial communication temperature control method, with a volume of 6x6x2cm 3 .

[0004] The continuous operation of the open refrigeration system still relies on the high-pressure main gas cylinder supply, and the maximum operation time is positively correlated with the volume of the main gas cylinder. For example, a 50L@20MPa main gas cylinder can support more than a week of operation time. However, in order to adapt to the narrow space scene, a 1.5L@20MPa small main gas cylinder is used, and the operation time will be reduced to about 3h, which forms a fundamental contradiction between portability and endurance. In addition, when the pressure of the main gas cylinder drops to a critical threshold (<8MPa), the existing refrigeration system needs to be shut down to replace the main gas cylinder, which will cause the refrigeration to be interrupted. The gas path separation makes the refrigeration flow instantaneous zero, and the refrigeration system experiences temperature rise (ΔT≥20K / min), and needs 30~60min of cooling time to reestablish the low-temperature environment after restarting. At the same time, the interface exposure introduces environmental air (local water vapor concentration >1000ppm), which brings pollution risk, which may exceed the instantaneous processing capacity of the purifier, causing the ice blocking probability of the micro channel to increase, thereby affecting the stability and reliability of the refrigeration system. SUMMARY

[0005] In view of the deficiencies of the prior art, the first object of the present application is to provide a continuous gas supply type micro-throttling refrigeration system, which realizes zero temperature rise continuous refrigeration and main gas cylinder replacement during the working stage of the refrigeration system by double main gas cylinder buffer design while keeping the refrigeration system small.

[0006] The second object of the present application is to provide a refrigeration method of a continuous gas supply type micro-throttling refrigeration system, which has the advantages of avoiding refrigeration interruption and reducing pollution risk.

[0007] To achieve the above-mentioned first object, the present application provides the following technical solutions: A continuous gas supply type micro-throttling refrigeration system, comprising a gas charging unit, a double main gas cylinder buffer unit, and a refrigeration dewar with a temperature control module, the double main gas cylinder buffer unit comprising a main gas cylinder with a pressure relief valve, a stop valve, a buffer bottle, a pressure regulating valve with a pressure detection module, a purifier, and a diaphragm valve connected in sequence along the gas supply direction, the pressure relief valve being selectively communicated with the gas charging unit and the stop valve through an external flow channel port, and the refrigeration dewar being detachably connected with the diaphragm valve.

[0008] Further, the gas charging unit comprises a nitrogen storage tank, an air compressor, and a booster pump, the low-pressure inlet of the booster pump being communicated with the outlet of the nitrogen storage tank, the drive gas inlet being communicated with the outlet of the air compressor, and the high-pressure outlet being communicated with the pressure relief valve.

[0009] Specifically, in the gas charging unit of the present application, The specific meaning of the nitrogen storage tank is a container for storing 5N grade low-pressure nitrogen gas source and providing gas source for the whole refrigeration system. The specific meaning of the air compressor is a device that compresses external air through an internal compression mechanical structure to increase the pressure of the gas, and its outlet is connected to the driving gas inlet of the booster pump to provide sufficient pressure gas for the booster pump to work; The specific meaning of the booster pump is a pump body device that can increase the pressure of low-pressure nitrogen to the required working pressure. It can increase the pressure of low-pressure nitrogen in the nitrogen storage tank to the required working pressure under the action of high-pressure driving gas provided by the air compressor, and stably deliver it to the main cylinder, thereby providing a stable gas source for the subsequent refrigeration process.

[0010] Specifically, in the double-main-cylinder buffer unit of the present application, The specific meaning of the pressure relief valve is a three-position three-way pressure relief valve (K32200B of Kaimay gas source) with three valve positions, which can be manually controlled and / or electromagnetically driven. The first valve position is the closed state, at which the pressure relief valve blocks the bottle body of the main cylinder, connects the external flow channel to the atmosphere, and realizes the pipeline gas emptying; the second valve position is the intermediate state, at which the pressure relief valve blocks the bottle body of the main cylinder and the external flow channel at the same time; the third valve position is the open state, at which the pressure relief valve connects the bottle body of the main cylinder to the external flow channel, so that the gas in the main cylinder is output to the external flow channel. During the refrigeration or inflation stage, the pressure relief valve is switched from the first valve position to the third valve position in sequence to complete the opening operation. After the refrigeration or inflation is completed, the pressure relief valve can be switched from the third valve position to the first valve position in sequence to realize the closing operation. The external flow channel is automatically depressurized, which facilitates the safe disassembly of the main cylinder. The specific meaning of the main cylinder is a high-pressure gas storage container that contains high-pressure nitrogen as the working gas of the refrigeration system. The bottle body, pressure gauge, and pressure relief valve of the main cylinder are integrated, which facilitates quick replacement and state monitoring of the main cylinder. The specific meaning of the stop valve is a valve used to open or close the gas path, which can be manually controlled and / or electromagnetically driven. It can block the gas path connection between the main cylinder and the buffer bottle when needed, to facilitate the safe disassembly of the main cylinder. The specific meaning of the buffer bottle is a container for storing and buffering high-pressure nitrogen to stabilize the gas flow. It is used to temporarily store gas during the replacement of the main cylinder, to ensure stable gas path pressure and avoid interruption of refrigeration. The volume design can meet the demand for continuous gas supply during the replacement of the main cylinder. The specific meaning of the pressure detection module is a device for real-time monitoring of the pressure change of the gas in the buffer bottle and / or the main cylinder. It can be a pressure gauge that directly displays the gas pressure, or a pressure sensor that converts the pressure signal into an electrical signal output, to facilitate accurate control of the pressure regulating valve by the refrigeration system, ensuring stable pressure of the refrigeration system. The specific meaning of the pressure regulating valve is a valve for regulating the pressure of the output gas, which can be manually controlled and / or electromagnetically driven, and is equipped with a pressure detection module that can monitor the pressure value of the output gas in real time to ensure the stability of the pressure of the output gas. The specific meaning of the purifier is a device for purifying high-pressure nitrogen gas to remove impurities and moisture to ensure the refrigeration effect. The specific meaning of the diaphragm valve is a valve for high-purity fluid isolation and conduction control, which can be manually controlled and / or electromagnetically driven, and is designed to meet the needs of isolating and conducting the gas entering the refrigeration dewar.

[0011] Specifically, in the refrigeration dewar of the present application, The specific meaning of the temperature control module is a device for real-time monitoring and control of the internal temperature of the refrigeration dewar, which can be realized based on the temperature control method of single-chip microcomputer serial communication, and can intelligently regulate the refrigeration process through a pre-set temperature threshold to ensure the refrigeration effect and the stability of the refrigeration system. The temperature control module cooperates with the refrigeration element (such as the throttling device) of the refrigeration dewar to adjust the refrigeration power according to the actual demand, achieving the purpose of energy saving and consumption reduction. The specific meaning of the refrigeration dewar is a low-temperature container provided with a throttling refrigeration element, a temperature sensor and a heating element, which receives high-pressure nitrogen gas after purification treatment, realizes refrigeration by using the throttling effect, and provides a low-temperature environment for external loads such as low-temperature detectors.

[0012] To achieve the above-mentioned second object, the present application provides the following technical solutions: A refrigeration method of a continuous gas supply type micro-throttling refrigeration system, comprising the following steps, S1 Assemble the gas charging unit and the main gas cylinder, the low-pressure nitrogen gas is compressed by the gas charging unit and charged into the main gas cylinder, the pressure relief valve is closed, and the standby main gas cylinder is obtained; S2 Assemble the main gas cylinder, the stop valve, the buffer bottle and the pressure regulating valve, open the pressure relief valve and the stop valve, slightly open the pressure regulating valve, complete the first low-pressure nitrogen gas purge, assemble the diaphragm valve and the refrigeration dewar, open the outlet end of the refrigeration dewar, open the diaphragm valve, install the purifier, and complete the second low-pressure nitrogen gas purge; S3 Open the outlet end of the refrigeration dewar, open the stop valve, the pressure regulating valve and the diaphragm valve, and adjust the opening degree of the pressure regulating valve based on the working pressure of the refrigeration dewar, and the refrigeration dewar is lowered to the target working temperature; S4 The refrigeration dewar is stabilized at the target working temperature and works at low temperature, and the gas pressure of the main gas cylinder gradually decreases, if the gas pressure of the main gas cylinder is lower than the critical pressure, the stop valve and the pressure relief valve are closed in sequence for pressure relief, the new main gas cylinder is disassembled and replaced, the pressure relief valve and the stop valve are opened, and the opening degree of the pressure regulating valve is adjusted based on the working pressure of the refrigeration dewar. S5 low temperature work is over, the refrigeration dewar is raised to room temperature, and is depressurized through the pressure regulating valve, the outlet end of the refrigeration dewar is blocked, and the diaphragm valve, the pressure regulating valve and the stop valve are closed in sequence.

[0013] Further, in the S1, an inflation unit is assembled in advance by the nitrogen storage tank, the air compressor and the booster pump, the low-pressure inlet of the booster pump is communicated with the outlet of the nitrogen storage tank, the driving gas inlet is communicated with the outlet of the air compressor, the inflation unit and the main gas cylinder are assembled again, the high-pressure outlet of the booster pump is communicated with the pressure relief valve, the pressure relief valve is opened, the air compressor and the booster pump are started, the booster pump compresses the low-pressure nitrogen to 25-35 MPa and then fills the main gas cylinder, when the pressure of the main gas cylinder reaches 25-35 MPa, the pressure relief valve is closed, and the main gas cylinder and the booster pump are disconnected, thereby obtaining a standby main gas cylinder.

[0014] Further, in the S2, the main gas cylinder obtained in the S1, the stop valve, the buffer bottle and the pressure regulating valve are assembled, the pressure relief valve and the stop valve are opened, and the pressure regulating valve is slightly opened, so that the low-pressure nitrogen slowly flows into the main gas circuit, after the first low-pressure nitrogen purging for 5-10 min, the diaphragm valve and the refrigeration dewar are assembled, the outlet end of the refrigeration dewar is opened, the diaphragm valve is opened, the two ends of the purifier are connected with the pressure regulating valve and the diaphragm valve respectively, and after the MJT throttling effect integrated in the refrigeration dewar, the second low-pressure nitrogen purging is performed for 1 h.

[0015] Further, in the S2, after the purging is completed, the outlet end of the refrigeration dewar is blocked, and the diaphragm valve, the pressure regulating valve and the stop valve are closed in sequence.

[0016] Further, in the S3, based on the double main gas cylinder buffer unit and the refrigeration dewar obtained in the S2, the outlet end of the refrigeration dewar is opened, the stop valve, the pressure regulating valve and the diaphragm valve are opened, and the opening degree of the pressure regulating valve is adjusted based on the working pressure of the refrigeration dewar of 7.0-10.0 MPa, after the MJT throtting effect integrated in the refrigeration dewar, the refrigeration dewar is reduced to the target working temperature, and during the period, the temperature of the refrigeration dewar is collected and stabilized by the temperature control module.

[0017] Further, in the S3, the refrigeration dewar is cooled for the first time, the residual water vapor in the refrigeration dewar is gradually purged, if the cooling is blocked due to ice blocking, the cooling can be paused, the temperature is raised and maintained for 10-30 min for gas circuit purging, after the purging is completed, the cooling is continued until the target working temperature of 80-100 K is reached, and the temperature control module is started to stabilize the temperature of the refrigeration dewar.

[0018] Further, in the S4, the refrigeration Dewar is stabilized at the target working temperature and performs low-temperature work, and the main gas cylinder pressure gradually decreases, if the main gas cylinder pressure is lower than the critical pressure 7.0~10.0MPa, the stop valve and the pressure relief valve are closed in turn, the pressure relief valve is automatically relieved to normal pressure before the pressure relief valve, the new main gas cylinder is disassembled and replaced, the buffer cylinder maintains gas supply during replacement, and the refrigeration Dewar can continue to work for more than 5min at low temperature, after replacement, the pressure relief valve and the stop valve are opened, and the opening degree of the pressure regulating valve is adjusted based on the working pressure of the refrigeration Dewar, although the initial gas pressure fluctuates, but by setting the temperature of the refrigeration Dewar in the working medium two-phase region, based on the two-phase flow characteristics, the temperature fluctuation is less than 1K.

[0019] Further, in the S5, the low-temperature work is completed, the refrigeration Dewar is raised to room temperature, and is relieved to 2MPa through the pressure regulating valve, the outlet end of the refrigeration Dewar is blocked, and the diaphragm valve, the pressure regulating valve and the stop valve are closed in turn to avoid carrying high-pressure gas in the refrigeration system in the non-working state.

[0020] Further, the following steps are further included, S6, the pressure relief valve, the stop valve, the pressure regulating valve and the diaphragm valve are closed, the double main gas cylinder buffer unit and the refrigeration Dewar are disconnected, the two ends of the refrigeration Dewar are blocked, the new refrigeration Dewar is disassembled and replaced, and S3~S5 are repeated.

[0021] In summary, the beneficial technical effects of the present application are: through the structural innovation design, the contradiction between long-time operation and miniaturization of the low-temperature refrigeration system in the microelectronic field is solved, and the practicability and use convenience of the refrigeration system are significantly improved; 1. The double main gas cylinder structure design realizes long-time operation: in order to realize the design goal of miniaturization and long-time operation of the refrigeration system, the double main gas cylinder structure is adopted, the buffer cylinder is integrated after the main gas cylinder, and the gas path isolation control is realized by using the bottle valve at the outlet of the main gas cylinder and the stop valve at the front end of the buffer cylinder; when the main gas cylinder pressure decreases to the preset critical value, the refrigeration system completes the gas path isolation by closing the stop valve and the bottle valve, at this time the buffer cylinder continues to supply gas to the rear-end equipment; during the buffer cylinder gas supply, the main gas cylinder can be replaced with a full main gas cylinder module, and then the bottle valve and the stop valve are reopened to restore the main gas cylinder gas supply mode; this design realizes the continuity of the refrigeration system gas supply during the replacement of the main gas cylinder, and only the main gas cylinder needs to be replaced to adapt to different working time requirements, without the need to expand the refrigeration system volume, and the operation is simple like "replacing the battery"; 2. The pressure relief valve and integrated design reduce the introduction of impurities: due to the introduction of air impurities at the gas path connection of the double main gas cylinder structure, the purity of the working gas is affected, which may cause the MJT microchannel to freeze and block, resulting in temperature drop failure, in order to reduce the introduction of impurities, the pipe valve selection and integrated design are optimized; First, the pressure relief valve is selected as the bottle valve of the main gas cylinder. The valve has only a single gas inlet and outlet, and the volume is reduced by more than 50% compared to the traditional double-port bottle valve. Because the pressure relief valve needs to be frequently disassembled and assembled, the conventional scheme adds a connector to prevent the connector from wearing out and failing. To reduce air residue at the air connection, the application omits the connector and directly uses high-hardness 17-4PH material to manufacture the connector. This ensures that the seal remains intact after more than 1000 repeated disassembly and assembly, and significantly reduces air residue by more than 50%. Second, the outlet of the pressure relief valve is directly connected to the inlet of the stop valve using a threaded connection. The interface diameter is 1 / 8 inch (much larger than the equivalent diameter of the throttling channel), and the air residue volume at the connection is less than 1 mL, significantly reducing the risk of introducing external impurities. The connection structure uses a ball head with a nut design, which takes into account high purity, sealing, and ease of disassembly and assembly. Third, the stop valve uses an "L" shaped bend-through structure. Compared to the straight-through scheme, the pipeline layout is more compact, and the overall footprint is reduced by about 20%. Finally, all pipe and valve components are made of stainless steel with a surface roughness of BA grade or higher. The refrigeration system leakage rate is controlled to be ≤1×10 -8 Pa·m³ / s, thereby reducing the deterioration of refrigeration performance caused by the accumulation of water vapor impurities in the refrigeration system. 3. Control strategy based on two-phase flow characteristics to improve temperature stability: During the replacement of the main gas cylinder, air may be introduced, pressure fluctuations may occur, and flow changes may occur, which may affect the operating temperature of the micro-throttling refrigeration chip. The application proposes setting the operating temperature in the two-phase region of the working fluid (two-phase region temperature calculation reference cited document 10.2139 / ssrn.4259978) to achieve high temperature stability. According to the operating stage of the refrigeration system, the specific strategies are as follows: First stage (buffer bottle gas supply): The stop valve is closed, the refrigeration system is supplied by the buffer bottle, and the gas pressure in the buffer bottle gradually decreases within the preset range (e.g., from 8 MPa to 6 MPa). Since the operating temperature is in the gas-liquid two-phase region, the temperature-pressure relationship follows the saturation vapor pressure curve, and the temperature decreases slowly as the pressure decreases, remaining within the required operating range. Because the MJT flow is as low as <25 mg / s, this process can be maintained for several minutes (e.g., for a 100 mL buffer bottle volume, for more than 5 minutes), providing sufficient time for replacing the main gas cylinder. The second stage (new main gas cylinder access): after the main gas cylinder replacement is completed, the stop valve is opened, the refrigeration system is restored to be supplied with gas by the main gas cylinder, and the gas pressure before the pressure regulating valve rapidly rises (for example, from less than 8 MPa to about 26 MPa); according to the derivative calculation of the saturated steam pressure curve, the sensitivity of temperature to gas pressure change is about 3 MPa / K; therefore, the high-precision pilot-operated pressure regulating valve is selected in the application, and the output gas pressure fluctuation can be controlled within ±1% to ±0.1%, and for a 30 MPa main gas cylinder, the fluctuation is not more than 0.3 MPa; in the case of sudden increase of flow before the pressure regulating valve, the pressure regulating valve automatically reduces the opening degree, so that the gas pressure after the valve temporarily decreases and is accompanied by slight oscillation, and finally tends to be stable, so that the temperature of the refrigerator is maintained within the required working range, and the fluctuation amplitude is less than 1K, which ensures the stability of the low-temperature work; 4. Small size is realized based on the verification of main gas cylinder volume design according to gas consumption: due to different degrees of water vapor impurities generated by the double main gas cylinder structure under different working conditions, the MJT may need to be purged before cooling, in order to ensure that the double main gas cylinder capacity is sufficient to support the whole process of MJT purging and cooling, the application accurately determines the gas consumption under different working conditions through experiments; the experimental test items include: the amount of gas required for the first time purging after the refrigeration system is sealed for a long time (> 30 days), the purging gas consumption of water vapor introduced into the refrigeration system after being sealed for 5 days, the purging gas consumption of air introduced into the refrigeration system under the condition of main gas cylinder replacement, and the purging gas consumption of air introduced into the refrigeration system under the condition of refrigeration dewar replacement; Test results: low-pressure purging (2 MPa, 25 h, flow rate about 0.2 mg / s) can make the MJT normally cool down when the refrigeration system is purged for the first time, and only about 18g of nitrogen is consumed, and the main gas cylinder pressure drops by less than 1%, which indicates that the refrigeration system has high activation efficiency; the refrigeration system can normally cool down without additional purging after being sealed for 5 days, which shows that the internal water vapor has not accumulated significantly; as the water vapor concentration increases with the sealing time and tends to be stable (reaches the atmospheric concentration), in order to improve the purging efficiency, it is recommended to activate by low-pressure purging when sealed for more than one month; for the case of main gas cylinder disassembly and reinstallation (introduced air volume <1 mL), the test results show that the purifier can effectively remove water, and no additional purging is required; for the case of refrigeration dewar disassembly and reinstallation, only 20 min of purging time is required, the cooling time is prolonged by about 2 min, the refrigeration temperature does not change or slightly decreases, which shows that the refrigeration system has good expandability and maintainability; Based on experimental data, considering the miniaturization and long operation time of the refrigeration system, and combining the difficulty of adapting high-pressure pipe valves, the application sets the initial high pressure of the main gas cylinder and the buffer bottle to 30 MPa, and the main gas cylinder is replaced after the gas pressure drops to the preset critical value of 8 MPa; within the effective gas pressure range, the required gas supply of the refrigeration system is (sweeping gas consumption + gas consumption from normal temperature to low temperature section + low temperature maintenance for 1 hour), and the total gas volume is designed to be 0.6L; wherein the buffer bottle capacity is 0.1L, the main gas cylinder capacity is 0.5L, which is equivalent to the size of a bottle of mineral water; the refrigeration system adopts 1 / 8 inch stainless steel pipe connection, which is convenient for welding and bending, and further compresses the volume; the overall size is 195*219*300mm3, the height is mainly limited by the main gas cylinder, and the width and depth are limited by the layout of the main gas cylinder, stop valve and pressure regulating valve, and the structure is compact. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structure schematic diagram of the continuous gas supply type miniature throttling refrigeration system of embodiment 1 of the application.

[0023] Figure 2 is a structure schematic diagram of the double-main-gas-cylinder buffer unit of embodiment 1 of the application.

[0024] Figure 3 is a flow and temperature change diagram of the refrigeration system of embodiment 1 of the application. Figure 3 (a) in is a flow change diagram of the refrigeration system of embodiment 1 of the application during the first time of sealing and cooling down; Figure 3 (b) in is a temperature change diagram of the refrigeration system of embodiment 1 of the application during cooling down.

[0025] Figure 4 is a temperature change diagram of the refrigeration method of embodiment 3 of the application during the first time of cooling down and sealing for 5 days without sweeping.

[0026] Figure 5 is a temperature, flow and pressure change diagram of the refrigeration method of embodiment 3 of the application during the replacement of the main gas cylinder.

[0027] Figure 6 is a temperature change diagram of the refrigeration system of embodiment 1 of the application during the first time of cooling down and replacing the refrigeration dewar and sweeping and cooling down.

[0028] In the figure, 1, charging unit; 11, nitrogen storage tank; 12, air compressor; 13, booster pump; 2, double-main-gas-cylinder buffer unit; 21, main gas cylinder; 211, pressure relief valve; 22, stop valve; 23, buffer bottle; 24, pressure regulating valve; 241, pressure detection module; 25, purifier; 26, diaphragm valve; 3, refrigeration dewar; 31, temperature control module. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, purposes and effects of the present application more clear and easy to understand, the present application is further described below in conjunction with the drawings and specific embodiments.

[0030] Embodiment 1: Reference Figure 1 The present application discloses a continuous gas supply type micro-throttling refrigeration system, which comprises a gas charging unit 1, a double-main-gas cylinder buffer unit 2, and a refrigeration Dewar 3 with a temperature control module 31.

[0031] The double-main-gas cylinder buffer unit 2 comprises, in sequence along the gas supply direction, a main gas cylinder 21 with a pressure relief valve 211, a stop valve 22, a buffer cylinder 23, a pressure regulating valve 24 with a pressure detection module 241, a purifier 25, and a diaphragm valve 26. In the main gas cylinder 21 charging state, the external flow port of the pressure relief valve 211 is detachably connected with the gas charging unit 1; in the main gas cylinder 21 working state, the external flow port of the pressure relief valve 211 is detachably connected with the stop valve 22, and the refrigeration Dewar 3 is detachably connected with the diaphragm valve 26.

[0032] In addition, the gas charging unit 1 comprises a nitrogen storage tank 11, an air compressor 12, and a booster pump 13, the low-pressure inlet of the booster pump 13 is communicated with the outlet of the nitrogen storage tank 11, the driving gas inlet is communicated with the outlet of the air compressor 12, and the high-pressure outlet is communicated with the pressure relief valve 211.

[0033] Embodiment 2: The present application discloses a refrigeration method of a continuous gas supply type micro-throttling refrigeration system, which is different from the embodiment 1 in that it comprises the following steps, S1 Assemble the gas charging unit 1 and the main gas cylinder 21, compress the low-pressure nitrogen gas in the gas charging unit 1 and charge it into the main gas cylinder 21, close the pressure relief valve 211, and obtain a standby main gas cylinder 21; S2 Assemble the main gas cylinder 21, the stop valve 22, the buffer cylinder 23, and the pressure regulating valve 24, open the pressure relief valve 211 and the stop valve 22, slightly open the pressure regulating valve 24, complete the first low-pressure nitrogen gas purge, assemble the diaphragm valve 26 and the refrigeration Dewar 3, open the outlet end of the refrigeration Dewar 3, open the diaphragm valve 26, install the purifier 25, and complete the second low-pressure nitrogen gas purge; S3 Open the outlet end of the refrigeration Dewar 3, open the stop valve 22, the pressure regulating valve 24, and the diaphragm valve 26, adjust the opening degree of the pressure regulating valve 24 based on the working pressure of the refrigeration Dewar 3, and reduce the refrigeration Dewar 3 to the target working temperature; S4 The refrigeration Dewar 3 is stabilized at the target working temperature and works at low temperature, and the gas pressure of the main gas cylinder 21 gradually decreases. If the gas pressure of the main gas cylinder 21 is lower than the critical pressure, the relief valve 211 and the stop valve 22 are closed in turn to release pressure, the new main gas cylinder 21 is disassembled and replaced, the relief valve 211 and the stop valve 22 are opened, and the opening degree of the pressure regulating valve 24 is adjusted based on the working pressure of the refrigeration Dewar 3; S5 The low-temperature work is completed, the refrigeration Dewar 3 is raised to room temperature, and the pressure is released through the pressure regulating valve 24. The outlet end of the refrigeration Dewar 3 is blocked, and the diaphragm valve 26, the pressure regulating valve 24 and the stop valve 22 are closed in turn.

[0034] Embodiment 3: A continuous gas supply type micro-throttling refrigeration system disclosed in the present application, which is different from embodiment 1, comprises the following steps, S1 The gas charging unit 1 is assembled in advance by the nitrogen gas storage tank 11, the air compressor 12 and the booster pump 13. The low-pressure inlet of the booster pump 13 is communicated with the outlet of the nitrogen gas storage tank 11, and the driving gas inlet is communicated with the outlet of the air compressor 12. Then the gas charging unit 1 and the main gas cylinder 21 are assembled. The high-pressure outlet of the booster pump 13 is communicated with the relief valve 211. The relief valve 211 is opened, the air compressor 12 and the booster pump 13 are started, the booster pump 13 compresses the low-pressure nitrogen gas to 25-35 MPa and then charges it into the main gas cylinder 21. When the gas pressure of the main gas cylinder 21 reaches 25-35 MPa, the relief valve 211 is closed, and the main gas cylinder 21 and the booster pump 13 are disconnected, thereby obtaining a standby main gas cylinder 21; S2 The main gas cylinder 21, the stop valve 22, the buffer bottle 23 and the pressure regulating valve 24 obtained in S1 are assembled first. The relief valve 211 and the stop valve 22 are opened, and the pressure regulating valve 24 is slightly opened to make the low-pressure nitrogen gas flow slowly into the main gas path. After the first low-pressure nitrogen gas purge for 5-10 min, the diaphragm valve 26 and the refrigeration Dewar 3 are assembled. The outlet end of the refrigeration Dewar 3 is opened, the diaphragm valve 26 is opened, and the two ends of the purifier 25 are connected with the pressure regulating valve 24 and the diaphragm valve 26 respectively. After the MJT throttling effect integrated in the refrigeration Dewar 3, the second low-pressure nitrogen gas purge is performed for 1 h; After the purge is completed, the outlet end of the refrigeration Dewar 3 is blocked, and the diaphragm valve 26, the pressure regulating valve 24 and the stop valve 22 are closed in turn; S3 Based on the double-main-gas-buffer unit 2 and the refrigeration Dewar 3 obtained in S2, the outlet end of the refrigeration Dewar 3 is opened, the stop valve 22, the pressure regulating valve 24 and the diaphragm valve 26 are opened, and the opening degree of the pressure regulating valve 24 is adjusted based on the working pressure 8.0 MPa of the refrigeration Dewar 3. After the MJT throttling effect integrated in the refrigeration Dewar 3, the refrigeration Dewar 3 is lowered to the target working temperature. During this period, the temperature of the refrigeration Dewar 3 is collected and stabilized by the temperature control module 31; The first cooling is carried out on the cryogenic Dewar 3, and the residual water vapor inside the cryogenic Dewar 3 is gradually purged. If the cooling is blocked due to ice blocking, the cooling can be temporarily paused, the temperature is raised, and the gas path is purged for 20 min. After the purging is completed, the cooling is continued until the target working temperature 100 K is reached, and the temperature control module is started to stabilize the temperature of the cryogenic Dewar 3. S4 The cryogenic Dewar 3 is stabilized at the target working temperature, and low-temperature work is carried out. The gas pressure of the main gas cylinder 21 gradually decreases. If the gas pressure of the main gas cylinder 21 is lower than the critical pressure 8.0 MPa, the stop valve 22 and the pressure relief valve 211 are closed in turn. The pressure relief valve 211 is automatically relieved to normal pressure. The new main gas cylinder 21 is removed and replaced. The buffer cylinder 23 maintains the gas supply during the replacement. The cryogenic Dewar 3 can continue to work at low temperature for more than 5 min. After the replacement is completed, the pressure relief valve 211 and the stop valve 22 are opened, and the opening degree of the pressure regulating valve 24 is adjusted based on the working pressure of the cryogenic Dewar 3. Although there is an initial pressure fluctuation, the temperature fluctuation is less than 1 K based on the two-phase flow characteristics by setting the temperature of the cryogenic Dewar 3 in the working medium two-phase region. S5 The low-temperature work is completed, the cryogenic Dewar 3 is raised to room temperature, and the pressure is relieved to 2 MPa through the pressure regulating valve 24. The outlet end of the cryogenic Dewar 3 is blocked. The diaphragm valve 26, the pressure regulating valve 24, and the stop valve 22 are closed in turn to avoid carrying high-pressure gas in the non-working state of the refrigeration system. S6 The double-main-gas-cylinder buffer unit 2 and the cryogenic Dewar 3 are disconnected, and the two ends of the cryogenic Dewar 3 are blocked. The new cryogenic Dewar 3 is removed and replaced. Steps S3 to S5 are repeated.

[0035] Test Example 1: The refrigeration system obtained in Example 1 is refrigerated according to the refrigeration method of Example 3, and the purging requirement and the main gas cylinder 21 volume design under different refrigeration conditions are tested. The results are as follows.

[0036] 1. After the refrigeration system is sealed for a long time (> 30 d), low-pressure nitrogen gas purging at 2 MPa is carried out, the average flow rate is about 0.2 mg / s, and the purging time is about 25 h. The results are shown in (a) of Figure 3 , the nitrogen consumption is about 18 g, the cooling capacity can be restored, and the results are shown in (b) of Figure 3 . It can be seen from Figure 3 that the refrigeration system can be cooled normally after low-pressure purging for about 25 h after being sealed for a long time. Among them, Figure 3 (a) in is the flow rate change during the start of purging to the cooling period. The first steep increase in flow rate is due to the high-pressure gas rushing out when the refrigeration system is unsealed. The second steep increase in flow rate occurs when the cooling starts. Figure 3 (b) in is the temperature change during the cooling period.

[0037] 2. After the refrigeration system is sealed for 5 d, it can be directly cooled without purging, and it is verified that the water vapor generated by sealing the refrigeration system for 5 d has no effect on the cooling performance. From Figure 4It can be seen that the first cooling of the refrigeration system (black line) and the direct cooling after sealing 5d without purging (red line) are compared, and the cooling time and the minimum temperature are not affected.

[0038] 3. In the low-temperature stage of the refrigeration system, when the main gas cylinder 21 is insufficient, the buffer cylinder 23 is switched to supply gas, and after quickly replacing the main gas cylinder 21, the main gas cylinder 21 is restored to supply gas, and the temperature can be maintained stable, as shown in Figure 5 . This is because the working medium is in the gas-liquid two-phase region, and the temperature decreases with the decrease of gas pressure, and the change range is small, so when the buffer cylinder 23 is switched to supply gas, the refrigeration system can be stabilized in the working temperature range. In addition, a small amount of air (about 5ml) introduced during the replacement of the main gas cylinder 21 has no effect on the working state of the refrigeration system, and does not need to be heated and purged, so it will not cause the work to be interrupted. From Figure 5 It can be seen that when the refrigeration system switches the supply of the main gas cylinder 21 to the buffer cylinder 23 to the main gas cylinder 21 in the low-temperature stage, the temperature, flow rate and gas pressure change (when the buffer cylinder 23 is switched to supply gas, the flow rate and gas pressure decrease rapidly, and when the main gas cylinder 21 is restored to supply gas, the flow rate and gas pressure increase rapidly).

[0039] 4. After replacing the refrigeration dewar 3, the refrigeration system only needs to be purged for a total time of about 20 minutes to restore the cooling capacity. It is verified that the air introduced during the replacement of the refrigeration dewar 3 can be removed by short-time high-temperature and high-pressure purging. From Figure 6 It can be seen that the first cooling of the refrigeration system (black line) and the direct cooling after sealing 5d without purging (red line) are compared, and the cooling time and the minimum temperature are not affected.

[0040] 5. Main gas cylinder 21 volume design value verification: with the working time of 1h before replacing the main gas cylinder 21 as the target, the maximum gas supply required by the refrigeration system = the maximum purging gas consumption + the gas consumption from room temperature to low temperature + the gas consumption for maintaining 1h low temperature = 18g + 10g + 90g = 118g. For the volume design of 0.5L main gas cylinder 21 and 0.1L buffer cylinder 23, considering the room temperature 8MPa nitrogen density is 89.8g / L, the room temperature 29.5MPa nitrogen density is 291.1g / L, and the effective gas supply is 120.8g>118g, therefore the design is feasible.

[0041] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A continuous-gas-supply miniature throttling refrigeration system, characterized by: The application relates to a nitrogen gas filling device, which comprises a filling unit (1), a double-main-gas cylinder buffer unit (2) and a refrigeration Dewar (3) with a temperature control module (31), wherein the double-main-gas cylinder buffer unit (2) comprises, sequentially connected along a gas conveying direction, a main gas cylinder (21) with a pressure relief valve (211), a stop valve (22), a buffer cylinder (23), a pressure regulating valve (24) with a pressure detection module (241), a purifier (25) and a diaphragm valve (26), an external flow channel port of the pressure relief valve (211) is selectively communicated with the filling unit (1) and the stop valve (22), and the refrigeration Dewar (3) is detachably connected with the diaphragm valve (26).

2. The method of claim 1, wherein: The application further relates to a nitrogen gas filling method, which comprises the following steps, S1, assembling the filling unit (1) and the main gas cylinder (21), filling low-pressure nitrogen gas into the main gas cylinder (21) after compression, closing the pressure relief valve (211) and obtaining a standby main gas cylinder (21); S2, assembling the main gas cylinder (21), the stop valve (22), the buffer cylinder (23) and the pressure regulating valve (24), opening the pressure relief valve (211) and the stop valve (22), slightly opening the pressure regulating valve (24), completing the first low-pressure nitrogen gas purging, assembling the diaphragm valve (26) and the refrigeration Dewar (3), opening the outlet end of the refrigeration Dewar (3), opening the diaphragm valve (26), installing the purifier (25) and completing the second low-pressure nitrogen gas purging; S3, opening the outlet end of the refrigeration Dewar (3), opening the stop valve (22), the pressure regulating valve (24) and the diaphragm valve (26), adjusting the opening degree of the pressure regulating valve (24) based on the working pressure of the refrigeration Dewar (3), and lowering the refrigeration Dewar (3) to a target working temperature; S4, stabilizing the refrigeration Dewar (3) at the target working temperature and carrying out low-temperature work, gradually reducing the gas pressure of the main gas cylinder (21), closing the stop valve (22) and the pressure relief valve (211) in sequence for pressure relief when the gas pressure of the main gas cylinder (21) is lower than a critical pressure, disassembling and replacing a new main gas cylinder (21), opening the pressure relief valve (211) and the stop valve (22), and adjusting the opening degree of the pressure regulating valve (24) based on the working pressure of the refrigeration Dewar (3); S5, ending the low-temperature work, raising the refrigeration Dewar (3) to room temperature, releasing pressure through the pressure regulating valve (24), plugging the outlet end of the refrigeration Dewar (3), and closing the diaphragm valve (26), the pressure regulating valve (24) and the stop valve (22) in sequence.

3. The method of claim 2, wherein the method further comprises: In the S1, the filling unit (1) is assembled in advance by a nitrogen gas storage tank (11), an air compressor (12) and a booster pump (13), the low-pressure inlet of the booster pump (13) is communicated with the outlet of the nitrogen gas storage tank (11), the driving gas inlet is communicated with the outlet of the air compressor (12), the high-pressure outlet of the booster pump (13) is communicated with the pressure relief valve (211), the pressure relief valve (211) is opened, the air compressor (12) and the booster pump (13) are started, the booster pump (13) compresses low-pressure nitrogen gas to 25-35 MPa and fills the main gas cylinder (21), when the gas pressure of the main gas cylinder (21) reaches 25-35 MPa, the pressure relief valve (211) is closed, the main gas cylinder (21) and the booster pump (13) are disconnected, and a standby main gas cylinder (21) is obtained.

4. The method of claim 2, wherein the continuous gas supply micro-grolier system is a micro-grolier system. In the S2, the main cylinder (21), the stop valve (22), the buffer cylinder (23) and the pressure regulating valve (24) obtained in the S1 are assembled first, the pressure relief valve (211) and the stop valve (22) are opened, the pressure regulating valve (24) is slightly opened, so that the low-pressure nitrogen gas slowly flows into the main gas path, after the first low-pressure nitrogen gas purging for 5-10 minutes, the diaphragm valve (26) and the refrigeration dewar (3) are assembled, the outlet end of the refrigeration dewar (3) is opened, the diaphragm valve (26) is opened, the two ends of the purifier (25) are connected with the pressure regulating valve (24) and the diaphragm valve (26) respectively, after the MJT throttling effect integrated in the refrigeration dewar (3), the second low-pressure nitrogen gas purging is performed for 1 hour.

5. The method of claim 2, wherein: In the S2, after the purging is completed, the outlet end of the refrigeration dewar (3) is blocked, the diaphragm valve (26), the pressure regulating valve (24) and the stop valve (22) are closed in sequence.

6. The method of claim 2, wherein: In the S3, based on the double main cylinder buffer unit (2) and the refrigeration dewar (3) obtained in the S2, the outlet end of the refrigeration dewar (3) is opened, the stop valve (22), the pressure regulating valve (24) and the diaphragm valve (26) are opened, and the opening degree of the pressure regulating valve (24) is adjusted based on the working pressure of the refrigeration dewar (3) of 7.0-10.0 MPa, after the MJT throtting effect integrated in the refrigeration dewar (3), the refrigeration dewar (3) is reduced to the target working temperature, during which the temperature of the refrigeration dewar (3) is collected and stabilized by the temperature control module (31).

7. The method of claim 2, wherein the method further comprises: In the S3, the refrigeration dewar (3) is cooled for the first time, the residual water vapor in the refrigeration dewar (3) is gradually purged, if the cooling is blocked due to ice blocking, the cooling can be paused, the temperature is increased and maintained for 10-30 minutes for gas path purging, after the purging is completed, the cooling is continued until the target working temperature of 80-100 K is reached, and the temperature control module is opened to stabilize the temperature of the refrigeration dewar (3).

8. The method of claim 2, wherein the continuous gas supply micro-grolier system is a micro-grolier system. In the S4, the refrigeration dewar (3) is stabilized at the target working temperature and works at low temperature, the pressure of the main cylinder (21) gradually decreases, if the pressure of the main cylinder (21) is lower than the critical pressure of 7.0-10.0 MPa, the stop valve (22) and the pressure relief valve (211) are closed in sequence, the pressure relief valve (211) is automatically relieved to normal pressure, the new main cylinder (21) is disassembled and replaced, the buffer cylinder (23) maintains gas supply during the replacement, and the refrigeration dewar (3) can continue to work at low temperature for more than 5 minutes, after the replacement is completed, the pressure relief valve (211) and the stop valve (22) are opened, and the opening degree of the pressure regulating valve (24) is adjusted based on the working pressure of the refrigeration dewar (3), although the initial gas pressure fluctuates, by setting the temperature of the refrigeration dewar (3) in the two-phase region of the working medium, based on the two-phase flow characteristics, the temperature fluctuation is less than 1 K.

9. The method of claim 2, wherein the continuous gas supply micro-grolier system is a micro-grolier system. In the S5, the low-temperature work is completed, the refrigeration dewar (3) is raised to room temperature, and is relieved to 2 MPa through the pressure regulating valve (24), the outlet end of the refrigeration dewar (3) is blocked, the diaphragm valve (26), the pressure regulating valve (24) and the stop valve (22) are closed in sequence, so as to avoid that the refrigeration system carries high-pressure gas in the non-working state.

10. The method of claim 2, wherein: Further comprising the following steps, S6, closing the pressure relief valve (211), the stop valve (22), the pressure regulating valve (24) and the diaphragm valve (26), disconnecting the double main cylinder buffer unit (2) and the refrigeration dewar (3), blocking both ends of the refrigeration dewar (3), disassembling and replacing a new refrigeration dewar (3), repeating S3~S5.

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