A continuous gas supply type micro throttling refrigeration system and a refrigeration method thereof

Abstract

This invention relates to a continuous gas supply micro-throttling refrigeration system and its refrigeration method. The refrigeration system includes a gas charging unit, a dual main gas cylinder buffer unit, and a refrigeration Dewar with a temperature control module. The dual main gas cylinder buffer unit includes a main gas cylinder with a pressure relief valve, a shut-off valve, a buffer bottle, a pressure regulating valve with a pressure detection module, a purifier, and a diaphragm valve, sequentially connected along the gas supply direction. The external flow port of the pressure relief valve is selectively connected to the gas charging unit and the shut-off valve. The refrigeration Dewar is detachably connected to the diaphragm valve. This invention, through its dual main gas cylinder buffer design, achieves continuous refrigeration with zero temperature rise while maintaining a small system size, allowing the main gas cylinder to be replaced during system operation. This avoids refrigeration interruptions and reduces the risk of contamination.

Description

Technical Field

[0001] This invention relates to the technical field of refrigeration systems, and in particular to a continuous gas supply micro throttling refrigeration system and its refrigeration method. Background Technology

[0002] In modern science and technology, particularly in military, aerospace, medical imaging, and scientific research, the application of liquid nitrogen cryogenic detectors is becoming increasingly widespread. These detectors, such as cooled infrared detectors and high-performance CCDs, require cryogenic environments to maintain their performance stability and reliability. To achieve this, current technologies primarily rely on liquid nitrogen-cooled Dewar containers or Stirling refrigerators. While liquid nitrogen-cooled Dewar containers can provide a stable cryogenic environment, their use is limited by tank volume (typically 1-5L) and pipe ice blockage effects, resulting in an effective operating time typically not exceeding 3 hours. While Stirling refrigerators can achieve thousands of hours of continuous operation, their high cost (≥300,000 RMB) hinders their widespread adoption.

[0003] Miniature throttling cooling technology (MJT), as an emerging technology, integrates micron-level flow channels within a multilayer glass substrate using microelectromechanical manufacturing processes. It utilizes the throttling effect of a high-pressure gas (such as nitrogen) to achieve single-stage cooling, operating in the temperature range of 80–120 K. This technology offers advantages such as small size, low vibration, and low gas consumption. However, its open-loop cooling system requires a continuous gas supply, with a typical consumption rate of approximately 20 mg / s. While it can support continuous operation for over a week due to reliance on a high-pressure main gas cylinder, its gas-based cooling system includes more than seven valves and associated pressure regulating, purification, and temperature control modules, resulting in a system size several times larger than the core cooling components. This limits its application in space-constrained scenarios. Currently, the applicant has improved the small-scale cryogenic gas purification and pressure control device. By optimizing the purification gas flow direction and pipeline layout, the number of valves has been reduced to five, and the purification structure volume has been reduced by more than 50%. Furthermore, a miniature temperature control module based on a microcontroller serial communication temperature control method has been developed, reducing the size to 6 × 6 × 2 cm. 3 .

[0004] The continuous operation of open-loop refrigeration systems still relies on high-pressure main gas cylinders, and their maximum operating time is directly proportional to the cylinder volume. For example, a 50L@20MPa main gas cylinder can support more than a week of operation. However, the operating time of smaller 1.5L@20MPa main gas cylinders, used to adapt to confined spaces, drops drastically to about 3 hours, creating a fundamental contradiction between portability and endurance. Furthermore, when the main gas cylinder pressure drops to a critical threshold (<8MPa), the existing refrigeration system needs to be shut down for cylinder replacement, resulting in refrigeration interruption. Gas path separation causes the refrigeration flow rate to instantly drop to zero, and the refrigeration system experiences a temperature rebound (ΔT≥20K / min). After restarting, it requires 30-60 minutes of cooling time to re-establish the low-temperature environment. Simultaneously, the exposed interface introduces ambient air (local water vapor concentration >1000ppm), posing a risk of contamination that may exceed the purifier's instantaneous processing capacity, increasing the probability of microchannel ice blockage and thus affecting the stability and reliability of the refrigeration system. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a continuous gas supply micro throttling refrigeration system. Through a dual main gas cylinder buffer design, this system achieves continuous refrigeration with zero temperature rise while maintaining a small system size, allowing the main gas cylinders to be replaced during the refrigeration system's operation.

[0006] The second objective of this invention is to provide a refrigeration method for a continuously supplied micro throttling refrigeration system, which has the advantages of avoiding refrigeration interruption and reducing the risk of pollution.

[0007] To achieve the first objective mentioned above, the present invention provides the following technical solution:

[0008] A continuous gas supply micro throttling refrigeration system includes a gas charging unit, a dual main gas cylinder buffer unit, and a refrigeration Dewar with a temperature control module. The dual main gas cylinder buffer unit includes a main gas cylinder with a pressure relief valve, a shut-off valve, a buffer bottle, a pressure regulating valve with a pressure detection module, a purifier, and a diaphragm valve, which are connected sequentially along the gas supply direction. The external flow channel port of the pressure relief valve is selectively connected to the gas charging unit and the shut-off valve. The refrigeration Dewar is detachably connected to the diaphragm valve.

[0009] Furthermore, the inflation unit includes a nitrogen storage tank, an air compressor, and a booster pump. The low-pressure inlet of the booster pump is connected to the outlet of the nitrogen storage tank, the driving gas inlet is connected to the outlet of the air compressor, and the high-pressure outlet is connected to the pressure relief valve.

[0010] Specifically, in the inflation unit of the present invention,

[0011] The nitrogen storage tank specifically refers to a container used to store 5N-level low-pressure nitrogen gas and provide a gas source for the entire refrigeration system.

[0012] The air compressor specifically refers to a device that compresses external air through an internal compression mechanical structure to increase the gas pressure. Its outlet is connected to the driving gas inlet of a booster pump, providing the booster pump with gas of sufficient pressure to drive its operation.

[0013] The booster pump is a pump device that can boost low-pressure nitrogen to the required working pressure. Under the action of high-pressure driving gas provided by an air compressor, it can boost low-pressure nitrogen in a nitrogen storage tank to the required working pressure and stably deliver it to the main gas cylinder, thereby providing a stable gas source for the subsequent refrigeration process.

[0014] Specifically, in the dual main gas cylinder buffer unit of the present invention,

[0015] The pressure relief valve specifically refers to a three-position three-way pressure relief valve (Kaimai Gas Source K32200B) with three working positions, which can be manually operated and / or electromagnetically driven. The first valve position is the closed state, in which the pressure relief valve blocks the main gas cylinder body and connects the external flow channel to the atmosphere, realizing the gas venting of the pipeline. The second valve position is the intermediate state, in which the pressure relief valve simultaneously blocks the main gas cylinder body and the external flow channel. The third valve position is the open state, in which the pressure relief valve connects the main gas cylinder body and the external flow channel, allowing the gas in the main gas cylinder to be output to the external flow channel. During the refrigeration or filling stage, the pressure relief valve switches from the first valve position to the third valve position to complete the opening operation. After the refrigeration or filling is completed, the pressure relief valve can switch from the third valve position to the first valve position to complete the closing operation, and the external flow channel is automatically depressurized, which facilitates the safe disassembly of the main gas cylinder.

[0016] The main gas cylinder specifically refers to a high-pressure gas storage container that contains high-pressure nitrogen as the working gas of the refrigeration system. The main gas cylinder body, pressure gauge and pressure relief valve are integrated into one unit, and its design facilitates quick replacement and status monitoring of the main gas cylinder.

[0017] The term "shut-off valve" specifically refers to a valve used to open or close the gas path. It can be manually operated and / or electromagnetically driven. When needed, it can block the gas path connection between the main gas cylinder and the buffer cylinder to facilitate the safe disassembly of the main gas cylinder.

[0018] The buffer bottle is a container used to store and buffer high-pressure nitrogen to smooth out airflow fluctuations. It is used to temporarily store gas during the replacement of the main gas cylinder, ensure stable gas pressure, and avoid refrigeration interruption. Its volume design can meet the needs of continuous gas supply during the replacement of the main gas cylinder.

[0019] The pressure detection module is specifically used to monitor the changes in gas pressure in the buffer bottle and / or main gas cylinder in real time. It can be a pressure machine that directly displays the gas pressure, or a pressure sensor that converts the pressure signal into an electrical signal output, so that the refrigeration system can accurately control the pressure regulating valve according to the pressure value and ensure the stability of the refrigeration system pressure.

[0020] The pressure regulating valve is a valve used to regulate the pressure of the output gas. It can be manually operated and / or electromagnetically driven. Its pressure detection module can monitor the pressure value of the output gas in real time to ensure the stability of the output gas pressure.

[0021] The purifier specifically refers to a device used to purify high-pressure nitrogen gas to remove impurities and moisture, thereby ensuring the refrigeration effect.

[0022] The diaphragm valve specifically refers to a valve used for the isolation and conduction control of high-purity fluids. It can be manually operated and / or electromagnetically driven, and its design can meet the requirements for isolating and conducting gas entering the refrigeration Dewar.

[0023] Specifically, in the cooling Dewar of the present invention,

[0024] The temperature control module specifically refers to a device used to monitor and control the internal temperature of the cooling Dewar in real time. It can be implemented using a microcontroller serial communication method to intelligently regulate the cooling process through a preset temperature threshold, ensuring the cooling effect and the stability of the cooling system. The temperature control module works in conjunction with the cooling elements (such as a throttle) of the cooling Dewar to adjust the cooling power according to actual needs, thereby achieving the purpose of energy saving and consumption reduction.

[0025] The specific meaning of the cooling Dewar refers to a cryogenic container with a throttling cooling element, a temperature sensor and a heating element inside. It receives purified high-pressure nitrogen gas, uses the throttling effect to achieve cooling, and provides the low-temperature environment generated by the cooling to an external load, such as a cryogenic detector.

[0026] To achieve the second objective mentioned above, the present invention provides the following technical solution:

[0027] A refrigeration method for a continuous gas supply micro-throttling refrigeration system includes the following steps.

[0028] S1 assembles the inflation unit and the main gas cylinder. The inflation unit compresses low-pressure nitrogen and fills the main gas cylinder. After closing the pressure relief valve, a spare main gas cylinder is obtained.

[0029] S2 assembles the main gas cylinder, shut-off valve, buffer bottle and pressure regulating valve, opens the pressure relief valve and shut-off valve, slightly opens the pressure regulating valve to complete the first low-pressure nitrogen purging, assembles the diaphragm valve and cooling Dewar, opens the outlet end of the cooling Dewar, opens the diaphragm valve, installs the purifier, and completes the second low-pressure nitrogen purging.

[0030] S3 opens the outlet end of the cooling Dewar, opens the shut-off valve, pressure regulating valve and diaphragm valve, and adjusts the opening of the pressure regulating valve based on the working pressure of the cooling Dewar, so that the cooling Dewar is reduced to the target working temperature;

[0031] The S4 cooling Dewar stabilizes at the target operating temperature and operates at low temperature. The main gas cylinder pressure gradually decreases. If the main gas cylinder pressure is lower than the critical pressure, the shut-off valve and pressure relief valve are closed in sequence to release the pressure. The main gas cylinder is then disassembled and replaced with a new one. The pressure relief valve and shut-off valve are then opened, and the opening of the pressure regulating valve is adjusted based on the working pressure of the cooling Dewar.

[0032] After the S5 low-temperature operation ends, the cooling Dewar is brought to room temperature and depressurized through the pressure regulating valve. The outlet end of the cooling Dewar is then sealed, and the diaphragm valve, pressure regulating valve, and shut-off valve are closed in sequence.

[0033] Further, in step S1, a filling unit is pre-assembled from a nitrogen storage tank, an air compressor, and a booster pump. The low-pressure inlet of the booster pump is connected to the outlet of the nitrogen storage tank, and the driving gas inlet is connected to the outlet of the air compressor. Then, the filling unit and the main gas cylinder are assembled. The high-pressure outlet of the booster pump is connected to a pressure relief valve. The pressure relief valve is opened, and the air compressor and booster pump are started. The booster pump compresses the low-pressure nitrogen to 25~35MPa and fills the main gas cylinder. When the pressure in the main gas cylinder reaches 25~35MPa, the pressure relief valve is closed, and the main gas cylinder and booster pump are disconnected to obtain a spare main gas cylinder.

[0034] Further, in S2, the main gas cylinder, shut-off valve, buffer bottle and pressure regulating valve obtained in S1 are assembled first. The pressure relief valve and shut-off valve are opened, and the pressure regulating valve is slightly opened so that low-pressure nitrogen slowly flows into the main gas path. After the first low-pressure nitrogen purging for 5-10 minutes, the diaphragm valve and cooling Dewar are assembled. The outlet end of the cooling Dewar is opened, the diaphragm valve is opened, and the two ends of the purifier are connected to the pressure regulating valve and the diaphragm valve respectively. After the throttling effect of the MJT integrated in the cooling Dewar, the second low-pressure nitrogen purging is carried out for 1 hour.

[0035] Furthermore, in S2, after the purging is completed, the outlet end of the cooling Dewar is sealed, and the diaphragm valve, pressure regulating valve and shut-off valve are closed in sequence.

[0036] Furthermore, in S3, based on the dual main gas cylinder buffer unit and cooling Dewar obtained in S2, the outlet end of the cooling Dewar is opened, and the shut-off valve, pressure regulating valve and diaphragm valve are opened. The opening of the pressure regulating valve is adjusted based on the working pressure of the cooling Dewar (7.0~10.0MPa). After the throttling effect of the MJT integrated in the cooling Dewar, the cooling Dewar is reduced to the target working temperature. During this period, the temperature of the cooling Dewar is collected and stabilized by the temperature control module.

[0037] Furthermore, in S3, the cooling Dewar is cooled for the first time, and the residual water vapor inside the cooling Dewar is gradually blown away. If the cooling is hindered due to ice blockage, the cooling can be paused, the temperature is raised and the air path is maintained for 10 to 30 minutes. After the blowing is completed, the cooling continues until the target working temperature of 80 to 100K is reached, and the temperature control module is turned on to stabilize the temperature of the cooling Dewar.

[0038] Furthermore, in step S4, the cooling Dewar stabilizes at the target operating temperature and operates at low temperature. The main gas cylinder pressure gradually decreases. If the main gas cylinder pressure is lower than the critical pressure of 7.0~10.0 MPa, the shut-off valve and the pressure relief valve are closed in sequence. The pressure relief valve automatically releases pressure to atmospheric pressure. The main gas cylinder is then disassembled and replaced. During the replacement, the buffer bottle maintains gas supply, and the cooling Dewar can continue to operate at low temperature for more than 5 minutes. After the replacement is completed, the pressure relief valve and the shut-off valve are opened, and the opening of the pressure regulating valve is adjusted based on the operating pressure of the cooling Dewar. Although there is initial pressure fluctuation, by setting the temperature of the cooling Dewar in the two-phase region of the working fluid, the temperature fluctuation is <1K based on the two-phase flow characteristics.

[0039] Furthermore, in S5, the low-temperature operation ends, the refrigeration Dewar is raised to room temperature, and the pressure is released to 2MPa through the pressure regulating valve. The outlet end of the refrigeration Dewar is sealed, and the diaphragm valve, pressure regulating valve and shut-off valve are closed in sequence to prevent the refrigeration system from carrying high-pressure gas when it is not in operation.

[0040] Furthermore, the procedure also includes the following steps: S6 closes the pressure relief valve, shut-off valve, pressure regulating valve and diaphragm valve, disconnects the dual main gas cylinder buffer unit and the cooling Dewar, seals both ends of the cooling Dewar, disassembles and replaces the cooling Dewar with a new one, and repeats S3~S5.

[0041] In summary, the beneficial technical effects of the present invention are as follows: Through innovative structural design, the present invention solves the contradiction between long-term operation and miniaturization of low-temperature refrigeration systems in the field of microelectronics, and significantly improves the practicality and ease of use of the refrigeration system;

[0042] 1. Dual Main Gas Cylinder Structure for Long-Term Operation: To achieve the design goals of miniaturization and long-term operation of the refrigeration system, this invention adopts a dual main gas cylinder structure. A buffer cylinder is integrated after the main gas cylinder, and gas path isolation control is achieved by using the cylinder valve at the outlet of the main gas cylinder and the shut-off valve at the front end of the buffer cylinder. When the gas pressure in the main gas cylinder drops to a preset critical value, the refrigeration system completes gas path isolation by closing the shut-off valve and the cylinder valve. At this time, the buffer cylinder continues to supply gas to the downstream equipment. During the gas supply from the buffer cylinder, the main gas cylinder can be replaced with a fully filled main gas cylinder module, and then the cylinder valve and shut-off valve can be reopened to restore the main gas cylinder gas supply mode. This design ensures the continuity of the refrigeration system's gas supply during the replacement of the main gas cylinder. Only the main gas cylinder needs to be replaced to adapt to different working time requirements, without expanding the size of the refrigeration system. The operation is as simple as "changing a battery."

[0043] 2. Pressure relief valve and integrated design reduce impurity introduction: Because the dual main gas cylinder structure introduces air impurities at the gas circuit connection, it affects the purity of the working gas and may cause the MJT microchannel to freeze and become blocked, resulting in cooling failure. In order to reduce the introduction of impurities, this invention optimizes the selection of pipe valves and the integrated design.

[0044] First, a pressure relief valve is selected as the main gas cylinder valve. This valve has only a single gas inlet and outlet, reducing its volume by more than 50% compared to traditional double-port cylinder valves. Since the pressure relief valve needs to be frequently disassembled and reassembled, conventional solutions add an adapter to prevent the adapter from wearing out and failing. To reduce air residue at the gas connection, this invention omits the adapter and directly uses a high-hardness 17-4PH material to manufacture the connector. While ensuring that it maintains its seal after more than 1,000 repeated disassemblies and reassemblies, it significantly reduces air residue by more than 50%.

[0045] Secondly, the outlet of the pressure relief valve and the inlet of the shut-off valve are connected by a threaded direct connection, and the interface diameter is 1 / 8 inch (much larger than the equivalent diameter of the throttling channel). The residual air volume at the connection is <1mL, which greatly reduces the risk of introducing external impurities. The connection structure adopts a ball head outer nut design, which takes into account high purity, sealing performance and easy disassembly and assembly.

[0046] Furthermore, the gate valve adopts an "L"-shaped bend structure, which results in a more compact pipeline layout and reduces the overall footprint by approximately 20% compared to a straight-through design.

[0047] Finally, all pipes and valves are made of stainless steel with a surface roughness of BA grade or higher, and the leakage rate of the refrigeration system is controlled to ≤1×10. -8 Pa·m³ / s, thereby reducing the degradation of refrigeration performance caused by the accumulation of water vapor impurities in the refrigeration system;

[0048] 3. Improving Temperature Stability through Control Strategies Based on Two-Phase Flow Characteristics: During main gas cylinder replacement, air introduction, pressure fluctuations, and flow rate changes may occur, affecting the operating temperature of the micro-throttling refrigeration chip. This invention proposes setting the operating temperature in the two-phase region of the working fluid (two-phase region temperature calculation reference 10.2139 / ssrn.4259978) to achieve higher temperature stability. The specific strategies, based on the refrigeration system's operating phases, are as follows:

[0049] Phase 1 (Buffer Bottle Gas Supply): With the shut-off valve closed, the refrigeration system is supplied with gas from the buffer bottle. The gas pressure inside the buffer bottle gradually decreases within a preset range (e.g., from 8MPa to 6MPa). Since the operating temperature is in the gas-liquid two-phase region, its temperature-pressure relationship follows the saturated vapor pressure curve. The temperature decreases slowly as the gas pressure decreases, but it can still be maintained within the required operating range. Because the MJT flow rate is as low as <25mg / s, this process can be maintained for several minutes (e.g., for a 100mL buffer bottle volume, it can be maintained for more than 5 minutes), providing sufficient time for replacing the main gas cylinder.

[0050] Phase Two (New Main Gas Cylinder Connection): After the main gas cylinder is replaced, the shut-off valve opens, and the refrigeration system resumes supplying gas from the main gas cylinder. The gas pressure before the pressure regulating valve rises rapidly (e.g., from less than 8 MPa to approximately 26 MPa). According to the derivative of the saturated vapor pressure curve, the sensitivity of temperature to pressure changes is approximately 3 MPa / K. Therefore, this invention uses a high-precision pilot-operated pressure regulating valve, which can control the output gas pressure fluctuation within ±1% to ±0.1%. For a 30 MPa main gas cylinder, the fluctuation does not exceed 0.3 MPa. In the event of a sudden increase in flow before the pressure regulating valve, the valve automatically reduces its opening, causing a brief drop in the gas pressure after the valve accompanied by slight oscillations, which eventually stabilizes. This keeps the refrigeration unit temperature within the required operating range, with fluctuations less than 1 K, ensuring the stability of low-temperature operation.

[0051] 4. Miniaturization of the main gas cylinder volume design based on gas consumption calculation and verification: Due to the varying degrees of water vapor impurities generated by the dual main gas cylinder structure under different operating conditions, the refrigeration system may need to purge the MJT before cooling. To ensure that the capacity of the dual main gas cylinders is sufficient to support the entire process of purging and cooling the MJT, this invention accurately measures the gas consumption under different operating conditions through experiments. The experimental test items include: the amount of gas required for the first purging after the refrigeration system has been sealed for a long time (>30 days), the purging gas consumption of water vapor introduced after the refrigeration system has been sealed for 5 days, the purging gas consumption of air introduced when the main gas cylinder is replaced, and the purging gas consumption of air introduced when the refrigeration Dewar is replaced.

[0052] Test Results: During the initial purging of the refrigeration system, low-pressure purging (2MPa, continuous for 25 hours, flow rate approximately 0.2mg / s) allowed the MJT to cool down normally, consuming only about 18g of nitrogen. The main gas cylinder pressure dropped by less than 1%, indicating high activation efficiency of the refrigeration system. After 5 days of sealing, the refrigeration system cooled down normally without additional purging, indicating no significant accumulation of internal moisture. Since the moisture concentration increases with sealing time and tends to stabilize (reaching atmospheric concentration), to improve purging efficiency, it is recommended to reactivate using low-pressure purging after more than one month of sealing. For cases where the main gas cylinder is disassembled and reinstalled (introducing air volume <1mL), test results show that the purifier can effectively remove moisture without additional purging. For cases where the refrigeration Dewar is disassembled and reinstalled, only an additional 20 minutes of purging time is required, extending the cooling time by approximately 2 minutes, while the cooling temperature remains unchanged or slightly decreases, indicating that the refrigeration system has good scalability and maintainability.

[0053] Based on experimental data, and considering the miniaturization and operating time requirements of the refrigeration system, as well as the difficulty of adapting high-pressure pipe valves, this invention sets the initial high pressure of the main gas cylinder and buffer cylinder at 30MPa. The main gas cylinder is replaced after the gas pressure drops to a preset critical value of 8MPa. Within the effective gas pressure range, the required gas supply of the refrigeration system is (purge gas consumption + gas consumption from room temperature to low temperature + gas consumption for maintaining low temperature for 1 hour), and the total gas volume is designed to be 0.6L. Among them, the buffer cylinder capacity is 0.1L and the main gas cylinder capacity is 0.5L, equivalent to the size of a bottle of mineral water. The refrigeration system uses 1 / 8-inch stainless steel pipes for connection, which is convenient for welding and bending, further compressing the volume. The overall dimensions are 195×219×300mm³, with the height mainly limited by the main gas cylinder, and the width and depth limited by the layout of the main gas cylinder, shut-off valve, and pressure regulating valve, resulting in a compact structure. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the structure of the continuous gas supply micro throttling refrigeration system of Embodiment 1 of the present invention.

[0055] Figure 2 This is a schematic diagram of the structure of the dual main gas cylinder buffer unit in Embodiment 1 of the present invention.

[0056] Figure 3 This is a graph showing the flow rate and temperature changes of the refrigeration system in Embodiment 1 of the present invention;

[0057] Figure 3 (a) is a flow rate change diagram of the refrigeration system of Embodiment 1 of the present invention during the initial purging and cooling period after a long period of sealing;

[0058] Figure 3 (b) is a temperature change diagram during the cooling period of the refrigeration system of Embodiment 1 of the present invention.

[0059] Figure 4This is a temperature change graph of the refrigeration method of Embodiment 3 of the present invention, after the initial cooling and sealing for 5 days, without purging and direct cooling.

[0060] Figure 5 This is a graph showing the temperature, flow rate, and pressure changes during the replacement of the main gas cylinder in the refrigeration method of Embodiment 3 of the present invention.

[0061] Figure 6 This is a temperature change graph of the refrigeration system of Embodiment 1 of the present invention during the initial cooling and after purging and cooling following the replacement of the refrigeration Dewar.

[0062] In the diagram, 1 is the inflation unit; 11 is the nitrogen storage tank; 12 is the air compressor; 13 is the booster pump; 2 is the dual main cylinder buffer unit; 21 is the main cylinder; 211 is the pressure relief valve; 22 is the shut-off valve; 23 is the buffer bottle; 24 is the pressure regulating valve; 241 is the pressure detection module; 25 is the purifier; 26 is the diaphragm valve; 3 is the cooling Dewar; and 31 is the temperature control module. Detailed Implementation

[0063] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0064] Example 1: Refer to Figure 1 The present invention discloses a continuous gas supply micro throttling refrigeration system, which includes a gas charging unit 1, a dual main gas cylinder buffer unit 2, and a refrigeration Dewar 3 with a temperature control module 31.

[0065] The dual main gas cylinder buffer unit 2 includes a main gas cylinder 21 with a pressure relief valve 211, a shut-off valve 22, a buffer bottle 23, a pressure regulating valve 24 with a pressure detection module 241, a purifier 25, and a diaphragm valve 26, which are connected sequentially along the gas supply direction. When the main gas cylinder 21 is in the filling state, the external flow port of the pressure relief valve 211 is detachably connected to the filling unit 1; when the main gas cylinder 21 is in the working state, the external flow port of the pressure relief valve 211 is detachably connected to the shut-off valve 22, and the cooling Dewar 3 is detachably connected to the diaphragm valve 26.

[0066] In addition, the inflation unit 1 includes a nitrogen storage tank 11, an air compressor 12, and a booster pump 13. The low-pressure inlet of the booster pump 13 is connected to the outlet of the nitrogen storage tank 11, the driving gas inlet is connected to the outlet of the air compressor 12, and the high-pressure outlet is connected to the pressure relief valve 211.

[0067] Example 2: A refrigeration method for a continuous gas supply micro throttling refrigeration system disclosed in this invention, which differs from Example 1 in that it includes the following steps:

[0068] S1 assembles the inflation unit 1 and the main gas cylinder 21. The inflation unit 1 compresses low-pressure nitrogen and fills it into the main gas cylinder 21. The pressure relief valve 211 is closed to obtain the spare main gas cylinder 21.

[0069] S2 assembles the main gas cylinder 21, shut-off valve 22, buffer bottle 23 and pressure regulating valve 24, opens the pressure relief valve 211 and shut-off valve 22, slightly opens the pressure regulating valve 24 to complete the first low-pressure nitrogen purging, assembles the diaphragm valve 26 and the cooling Dewar 3, opens the outlet end of the cooling Dewar 3, opens the diaphragm valve 26, installs the purifier 25, and completes the second low-pressure nitrogen purging;

[0070] S3 opens the outlet end of the cooling Dewar 3, opens the shut-off valve 22, the pressure regulating valve 24 and the diaphragm valve 26, and adjusts the opening of the pressure regulating valve 24 based on the working pressure of the cooling Dewar 3, so that the cooling Dewar 3 is reduced to the target working temperature.

[0071] The S4 cooling Dewar 3 stabilizes at the target operating temperature and operates at low temperature. The pressure of the main gas cylinder 21 gradually decreases. If the pressure of the main gas cylinder 21 is lower than the critical pressure, the shut-off valve 22 and the pressure relief valve 211 are closed in sequence to relieve pressure. The main gas cylinder 21 is disassembled and replaced with a new one. The pressure relief valve 211 and the shut-off valve 22 are opened, and the opening of the pressure regulating valve 24 is adjusted based on the operating pressure of the cooling Dewar 3.

[0072] After the S5 low-temperature operation ends, the cooling Dewar 3 is brought up to room temperature and depressurized through the pressure regulating valve 24. The outlet end of the cooling Dewar 3 is then sealed, and the diaphragm valve 26, pressure regulating valve 24, and shut-off valve 22 are closed in sequence.

[0073] Example 3: A refrigeration method for a continuous gas supply micro throttling refrigeration system disclosed in this invention, which differs from Example 1 in that it includes the following steps:

[0074] S1 is pre-assembled with a nitrogen storage tank 11, an air compressor 12, and a booster pump 13 to form an inflation unit 1. The low-pressure inlet of the booster pump 13 is connected to the outlet of the nitrogen storage tank 11, and the driving gas inlet is connected to the outlet of the air compressor 12. Then, the inflation unit 1 and the main gas cylinder 21 are assembled. The high-pressure outlet of the booster pump 13 is connected to the pressure relief valve 211. The pressure relief valve 211 is opened, and the air compressor 12 and the booster pump 13 are started. The booster pump 13 compresses the low-pressure nitrogen to 25~35MPa and then fills the main gas cylinder 21. When the pressure in the main gas cylinder 21 reaches 25~35MPa, the pressure relief valve 211 is closed, and the main gas cylinder 21 and the booster pump 13 are disconnected to obtain a spare main gas cylinder 21.

[0075] S2 first assembles the main gas cylinder 21, shut-off valve 22, buffer bottle 23 and pressure regulating valve 24 obtained from S1. Open the pressure relief valve 211 and shut-off valve 22, and slightly open the pressure regulating valve 24 to allow low-pressure nitrogen to slowly flow into the main gas path. After the first low-pressure nitrogen purging for 5-10 minutes, assemble the diaphragm valve 26 and the cooling Dewar 3. Open the outlet end of the cooling Dewar 3 and open the diaphragm valve 26. Connect the two ends of the purifier 25 to the pressure regulating valve 24 and the diaphragm valve 26 respectively. After the throttling effect of the MJT integrated in the cooling Dewar 3, the second low-pressure nitrogen purging is carried out for 1 hour.

[0076] After purging, seal the outlet end of the cooling Dewar 3, and close the diaphragm valve 26, pressure regulating valve 24 and shut-off valve 22 in sequence;

[0077] Based on the dual main gas cylinder buffer unit 2 and the cooling Dewar 3 obtained from S2, S3 opens the outlet end of the cooling Dewar 3, opens the shut-off valve 22, the pressure regulating valve 24 and the diaphragm valve 26, and adjusts the opening of the pressure regulating valve 24 based on the working pressure of the cooling Dewar 3 of 8.0MPa. After the throttling effect of the MJT integrated in the cooling Dewar 3, the cooling Dewar 3 is reduced to the target working temperature. During this period, the temperature of the cooling Dewar 3 is collected and stabilized by the temperature control module 31.

[0078] The cooling Dewar 3 is the first cooling process. The residual water vapor inside the cooling Dewar 3 is gradually blown away. If the cooling is blocked due to ice blockage, the cooling can be paused, the temperature can be increased and the air path can be blown away for 20 minutes. After the blowing is completed, the cooling can continue until the target working temperature of 100K is reached, and the temperature control module can be turned on to stabilize the temperature of the cooling Dewar 3.

[0079] The S4 cooling Dewar 3 stabilizes at the target operating temperature and operates at low temperature. The pressure in the main gas cylinder 21 gradually decreases. If the pressure in the main gas cylinder 21 is lower than the critical pressure of 8.0 MPa, the shut-off valve 22 and the pressure relief valve 211 are closed in sequence. The pressure relief valve 211 automatically releases pressure to atmospheric pressure. The main gas cylinder 21 is then disassembled and replaced. During the replacement, the buffer bottle 23 maintains the gas supply, and the cooling Dewar 3 can continue to operate at low temperature for more than 5 minutes. After the replacement is completed, the pressure relief valve 211 and the shut-off valve 22 are opened, and the opening of the pressure regulating valve 24 is adjusted based on the operating pressure of the cooling Dewar 3. Although there is initial pressure fluctuation, by setting the temperature of the cooling Dewar 3 in the two-phase region of the working fluid, the temperature fluctuation is <1K based on the two-phase flow characteristics.

[0080] After the S5 low-temperature operation ends, the refrigeration Dewar 3 is brought up to room temperature and depressurized to 2MPa through the pressure regulating valve 24. The outlet end of the refrigeration Dewar 3 is sealed, and the diaphragm valve 26, pressure regulating valve 24 and shut-off valve 22 are closed in sequence to prevent the refrigeration system from carrying high-pressure gas when it is not in operation.

[0081] S6 disconnect the dual main gas cylinder buffer unit 2 and the cooling Dewar 3, seal both ends of the cooling Dewar 3, disassemble and replace the cooling Dewar 3 with a new one, and repeat S3~S5.

[0082] Experimental Example 1: The refrigeration system obtained in Example 1 was refrigerated according to the refrigeration method in Example 3. The purging requirements and the volume design of the main gas cylinder 21 under different refrigeration conditions were tested, and the results are shown below.

[0083] 1. After the refrigeration system has been sealed for a long period (>30 days), it is purged with low-pressure nitrogen at 2 MPa, with an average flow rate of approximately 0.2 mg / s, for about 25 hours. The results are as follows: Figure 3 As shown in (a), approximately 18g of nitrogen is consumed to restore the cooling capacity, as shown in the results. Figure 3 As shown in (b) of the diagram. From Figure 3 It can be seen that the refrigeration system, after being sealed for a long time, can cool down normally after being purged with low pressure for about 25 hours; among them, Figure 3 (a) shows the flow rate change from the start of purging to cooling. The first sharp increase in flow rate is due to the high-pressure gas rushing out when the refrigeration system is unsealed, and the second sharp increase in flow rate corresponds to the start of cooling. Figure 3 (b) in the figure represents the temperature change during the cooling period.

[0084] 2. After the refrigeration system was sealed for 5 days, it could directly cool down without purging, verifying that the water vapor generated during the 5-day sealing period had no impact on the cooling performance. From Figure 4 As can be seen, the cooling time and minimum temperature are not affected when comparing the initial cooling of the refrigeration system (black line) with the direct cooling without purging after 5 days of sealing (red line).

[0085] 3. During the low-temperature phase, when the main gas cylinder 21 has insufficient pressure, the refrigeration system switches to supply gas from the buffer cylinder 23. After quickly replacing the main gas cylinder 21, the gas supply from the main gas cylinder 21 is restored. During this period, the temperature can be maintained stably. Figure 5 As shown. This is because the working fluid is in the gas-liquid two-phase region, and its temperature decreases with decreasing gas pressure, but the change is small. Therefore, when switching to buffer bottle 23 for gas supply, the refrigeration system can remain stable within the operating temperature range. Furthermore, the small amount of air (approximately 5 mL) introduced when replacing the main gas cylinder 21 has no impact on the refrigeration system's operation; no heating purging is required, and therefore, it will not cause operational interruption. From Figure 5 It can be seen that when the refrigeration system switches between "main gas cylinder 21 - buffer cylinder 23 - main gas cylinder 21" during the low-temperature stage, the temperature, flow rate, and gas pressure change (when switching to buffer cylinder 23 for gas supply, the flow rate and gas pressure drop rapidly, and when resuming main gas cylinder 21 for gas supply, the flow rate and gas pressure rise rapidly).

[0086] 4. After replacing the cooling Dewar 3, the cooling system only requires a purging process of approximately 20 minutes to restore its cooling capacity. This verifies that air introduced during the replacement of the cooling Dewar 3 can be removed through a short, high-temperature, high-pressure purging process. Figure 6It can be seen that the cooling system cooled down normally after the first cooling and after replacing the cooling Dewar 3. After replacing the cooling Dewar 3, the cooling system cooled down normally after heating and blowing at 250K or above for about 20 minutes.

[0087] 5. Verification of the design value of the main gas cylinder 21 volume: Taking the working time of 1 hour before replacing the main gas cylinder 21 as the target, the maximum gas supply required by the refrigeration system = maximum purging gas consumption + gas consumption from room temperature to low temperature + gas consumption for maintaining low temperature for 1 hour = 18g + 10g + 90g = 118g. For the volume design of the 0.5L main gas cylinder 21 and the 0.1L buffer bottle 23, considering that the nitrogen density at room temperature of 8MPa is 89.8g / L and the nitrogen density at room temperature of 29.5MPa is 291.1g / L, the effective gas supply is 120.8g > 118g, therefore the design is feasible.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A refrigeration method for a continuously supplied gas micro-throttling refrigeration system, characterized in that: The refrigeration system includes a gas filling unit (1), a dual main gas cylinder buffer unit (2), and a refrigeration Dewar (3) with a temperature control module (31). The dual main gas cylinder buffer unit (2) includes a main gas cylinder (21) with a pressure relief valve (211), a shut-off valve (22), a buffer bottle (23), a pressure regulating valve (24) with a pressure detection module (241), a purifier (25), and a diaphragm valve (26) connected sequentially along the gas delivery direction. The external flow channel port of the pressure relief valve (211) is selectively connected to the gas filling unit (1) and the shut-off valve (22). The refrigeration Dewar (3) is detachably connected to the diaphragm valve (26). The cooling method Includes the following steps, S1. Assemble the inflation unit (1) and the main gas cylinder (21). The inflation unit (1) compresses the low-pressure nitrogen and fills it into the main gas cylinder (21). Close the pressure relief valve (211) to obtain the spare main gas cylinder (21). S2. Assemble the main gas cylinder (21), shut-off valve (22), buffer bottle (23) and pressure regulating valve (24), open the pressure relief valve (211) and shut-off valve (22), slightly open the pressure regulating valve (24) to complete the first low-pressure nitrogen purging, assemble the diaphragm valve (26) and cooling Dewar (3), open the outlet end of the cooling Dewar (3), open the diaphragm valve (26), install the purifier (25) to complete the second low-pressure nitrogen purging; S3. Open the outlet end of the cooling Dewar (3), open the shut-off valve (22), the pressure regulating valve (24) and the diaphragm valve (26), and adjust the opening of the pressure regulating valve (24) based on the working pressure of the cooling Dewar (3) to reduce the cooling Dewar (3) to the target working temperature; S4. The cooling Dewar (3) stabilizes at the target working temperature and operates at low temperature. The pressure of the main gas cylinder (21) gradually decreases. If the pressure of the main gas cylinder (21) is lower than the critical pressure, the shut-off valve (22) and the pressure relief valve (211) are closed in sequence to relieve pressure. The main gas cylinder (21) is disassembled and replaced with a new one. The pressure relief valve (211) and the shut-off valve (22) are opened. The opening of the pressure regulating valve (24) is adjusted based on the working pressure of the cooling Dewar (3). S5. When the low temperature operation ends, the cooling Dewar (3) is raised to room temperature and depressurized through the pressure regulating valve (24). The outlet end of the cooling Dewar (3) is sealed, and the diaphragm valve (26), pressure regulating valve (24) and shut-off valve (22) are closed in sequence. In S1, a filling unit (1) is assembled in advance from a nitrogen storage tank (11), an air compressor (12) and a booster pump (13). The low-pressure inlet of the booster pump (13) is connected to the outlet of the nitrogen storage tank (11), and the driving gas inlet of the booster pump (13) is connected to the outlet of the air compressor (12). The filling unit (1) and the main gas cylinder (21) are then assembled. The high-pressure outlet of the booster pump (13) is connected to the pressure relief valve (211). The pressure relief valve (211) is opened, and the air compressor (12) and the booster pump (13) are started. The booster pump (13) compresses the low-pressure nitrogen to 25~35MPa and fills the main gas cylinder (21). When the pressure of the main gas cylinder (21) reaches 25~35MPa, the pressure relief valve (211) is closed, and the main gas cylinder (21) and the booster pump (13) are disconnected to obtain a spare main gas cylinder (21). In S2, first assemble the main gas cylinder (21), shut-off valve (22), buffer bottle (23) and pressure regulating valve (24) obtained in S1, open the pressure relief valve (211) and shut-off valve (22), and slightly open the pressure regulating valve (24) so ​​that low-pressure nitrogen slowly flows into the main gas path. After the first low-pressure nitrogen purging for 5~10 minutes, assemble the diaphragm valve (26) and the cooling Dewar (3), open the outlet end of the cooling Dewar (3), open the diaphragm valve (26), connect the two ends of the purifier (25) to the pressure regulating valve (24) and the diaphragm valve (26) respectively, and after the MJT throttling effect integrated in the cooling Dewar (3), the second low-pressure nitrogen purging for 1 hour is performed. In S2, after the purging is completed, the outlet end of the cooling Dewar (3) is sealed, and the diaphragm valve (26), pressure regulating valve (24) and shut-off valve (22) are closed in sequence; In S4, the cooling Dewar (3) stabilizes at the target operating temperature and operates at low temperature. The pressure of the main gas cylinder (21) gradually decreases. If the pressure of the main gas cylinder (21) is lower than the critical pressure, the shut-off valve (22) and the pressure relief valve (211) are closed in sequence. The pressure relief valve (211) automatically releases pressure to normal pressure. The main gas cylinder (21) is disassembled and replaced. During the replacement, the buffer bottle (23) maintains gas supply, and the cooling Dewar (3) continues to operate at low temperature for more than 5 minutes. After the replacement is completed, the pressure relief valve (211) and the shut-off valve (22) are opened, and the opening of the pressure regulating valve (24) is adjusted based on the operating pressure of the cooling Dewar (3). Although there is initial pressure fluctuation, by setting the temperature of the cooling Dewar (3) in the two-phase region of the working fluid, the temperature fluctuation is <1K based on the two-phase flow characteristics.

2. The refrigeration method of a continuous gas supply micro throttling refrigeration system according to claim 1, characterized in that: In S3, based on the dual main gas cylinder buffer unit (2) and the cooling Dewar (3) obtained in S2, the outlet end of the cooling Dewar (3) is opened, and the shut-off valve (22), pressure regulating valve (24) and diaphragm valve (26) are opened. The opening of the pressure regulating valve (24) is adjusted based on the working pressure of the cooling Dewar (3) of 7.0~10.0MPa. After the throttling effect of the MJT integrated in the cooling Dewar (3), the cooling Dewar (3) is reduced to the target working temperature. During this period, the temperature of the cooling Dewar (3) is collected and stabilized by the temperature control module (31).

3. The refrigeration method of a continuous gas supply micro throttling refrigeration system according to claim 1, characterized in that: In S3, the cooling Dewar (3) is cooled for the first time. The residual water vapor inside the cooling Dewar (3) is gradually blown away. If the cooling is blocked due to ice blockage, the cooling can be paused, the temperature is raised and the air path is maintained for 10 to 30 minutes. After the blowing is completed, the cooling continues until the target working temperature of 80 to 100K is reached, and the temperature control module is turned on to stabilize the temperature of the cooling Dewar (3).

4. The refrigeration method of a continuous gas supply micro throttling refrigeration system according to claim 1, characterized in that: In S5, the low-temperature operation ends, the refrigeration dewar (3) is raised to room temperature, and the pressure is released to 2MPa through the pressure regulating valve (24). The outlet end of the refrigeration dewar (3) is blocked, and the diaphragm valve (26), pressure regulating valve (24) and shut-off valve (22) are closed in sequence to prevent the refrigeration system from carrying high-pressure gas in the non-operating state.

5. The refrigeration method of a continuous gas supply micro throttling refrigeration system according to claim 1, characterized in that: The procedure also includes the following steps: S6 closes the pressure relief valve (211), shut-off valve (22), pressure regulating valve (24) and diaphragm valve (26), disconnects the dual main gas cylinder buffer unit (2) and cooling Dewar (3), seals both ends of the cooling Dewar (3), disassembles and replaces the cooling Dewar (3), and repeats S3~S5.

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