Machining method of 2K negative pressure aluminum plate-fin heat exchanger

Abstract

The invention provides a machining method of a 2K negative pressure aluminum plate-fin heat exchanger. The machining method comprises the steps that a core body is manufactured; manufacturing an end socket, wherein the process for manufacturing the end socket comprises the step of integrally forging the end socket; the core body is connected with the end socket to manufacture the heat exchanger; normal-temperature detection is conducted on the heat exchanger; performing low-temperature detection on the heat exchanger; the step of performing low-temperature detection on the heat exchanger comprises the substeps of vacuumizing each heat exchange channel in the heat exchanger and a sealing device where the heat exchanger is located; when the vacuum degree is smaller than a first preset pressure threshold value, the background leakage rate of the sealing device and the background leakage rate of each heat exchange channel in the heat exchanger are obtained; the heat exchanger is subjected to cold shock treatment, and the background leakage rate and the vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and the vacuum degree of the sealing device in the cooling process are obtained; and under the condition that the temperature is reduced to the preset temperature threshold value, low-temperature helium mass spectrum leak detection is conducted on the heat exchanger. The heat exchanger with the micro leakage rate, high mechanical strength, compact size and high cleanliness can be obtained, and the machining efficiency and the yield are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchangers, and in particular relates to a processing method of a 2K negative pressure aluminum plate-fin heat exchanger. Background Art

[0002] 2K negative pressure heat exchanger refers to a heat exchanger that works in the 4K liquid helium and 2K superfluid helium temperature range, which can be used to recover the cold of the cryogenic system and increase the production rate of superfluid helium. The 2K negative pressure heat exchanger operates in a deep low temperature and negative pressure environment. The heat exchange temperature difference on both sides is small, the physical properties of helium change dramatically, and there is a transition between 4K liquid helium and 2K superfluid helium. Therefore, the leakage rate, heat transfer performance, pressure drop performance and volume of the 2K negative pressure heat exchanger have a great impact on the performance of the deep cryogenic system, the construction and operation cost of the heat exchanger. The mechanical, thermal and electrical properties of metal materials change with temperature, especially between deep cold environment and normal temperature. These changes have important impacts in the fields of cryogenic engineering, aerospace, deep cold storage, superconducting materials, refrigeration and energy.

[0003] In the existing manufacturing of 2K negative pressure aluminum plate-fin heat exchangers, generally only the appearance inspection and room temperature helium mass spectrometry leak detection are carried out on the heat exchangers, and low temperature detection cannot be carried out, and its sealing performance in deep low temperature environment cannot be accurately evaluated and tested, and leak detection under design pressure cannot be carried out. At the same time, the lack of relatively standardized purging treatment and cleanliness detection processes has led to low efficiency and yield rate in the production of 2K negative pressure aluminum plate-fin heat exchangers, and there is a high risk of welding impurities contaminating the low temperature system. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a processing method for a 2K negative pressure aluminum plate-fin heat exchanger, which can perform various tests on the 2K negative pressure aluminum plate-fin heat exchanger including low-temperature helium mass spectrometry leak detection, thereby improving the processing efficiency and yield of the 2K negative pressure aluminum plate-fin heat exchanger.

[0005] In order to solve the above problems, the present invention provides a processing method of a 2K negative pressure aluminum plate-fin heat exchanger, comprising: Making the core; Making the head, the process of making the head includes one-piece forging the head; Connect the core and the head to form a heat exchanger; Conduct normal temperature testing on the heat exchanger, the temperature range of normal temperature testing is 20℃~30℃; Conduct low temperature testing on the heat exchanger, the temperature range of low temperature testing is below -150℃; The step of performing low temperature detection on the heat exchanger includes: Evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located; When the vacuum degree is less than the first preset pressure threshold, obtaining the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger; Perform cold shock treatment on the heat exchanger, and obtain the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device during the cooling process; When the temperature is cooled to a preset temperature threshold, the heat exchanger is tested for leaks using a cryogenic helium mass spectrometer.

[0006] Optionally, the step of evacuating each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located includes: Each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located are evacuated by a mechanical pump; When the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the first intermediate pressure threshold, the Roots pump is turned on to evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located; When the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the second intermediate pressure threshold, the molecular pump is turned on to evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located, so that the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the first preset pressure threshold; When the vacuum degree is less than the first preset pressure threshold, obtaining the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger includes: The leak detection device is connected to the closed device, and the leak detection device is blocked from each heat exchange channel in the heat exchanger to obtain the background leakage rate of the closed device; The leak detection device is sequentially connected to each heat exchange channel in the heat exchanger, and the leak detection device is blocked from the sealing device to obtain the background leakage rate of each heat exchange channel in the heat exchanger; The heat exchange channel of the heat exchanger includes a cold fluid channel and a hot fluid channel; The heat exchanger is subjected to cold shock treatment, and the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device are obtained during the cooling process, including: Selecting a cold fluid channel with the largest volume as a first cooling channel, introducing liquid nitrogen into a first end of the first cooling channel and discharging it from a second end of the first cooling channel, so that the second end of the first cooling channel becomes a discharge port; Control the cooling rate of the first cooling channel to be less than or equal to 4°C / min; When the temperature difference between the first end of the first cooling channel and the second end of the first cooling channel is greater than a preset temperature difference threshold, and the temperature drop rate is less than a preset rate threshold, liquid nitrogen is introduced into the second end of the first cooling channel and discharged from the first end of the first cooling channel, so that the first end of the first cooling channel becomes a discharge port; After the temperature of the first cooling channel is cooled to a preset temperature threshold, and when no nitrogen is discharged from the exhaust port of the first cooling channel, the hot fluid channel with the largest volume is selected as the second cooling channel, and liquid nitrogen is introduced into the first end of the second cooling channel and discharged from the second end of the second cooling channel, so that the second end of the second cooling channel becomes the exhaust port; Control the cooling rate of the second cooling channel to be less than or equal to 4°C / min; When the temperature difference between the first end of the second cooling channel and the second end of the second cooling channel is greater than a preset temperature difference threshold, and the temperature drop rate is less than a preset rate threshold, liquid nitrogen is introduced into the second end of the second cooling channel and discharged from the first end of the second cooling channel, so that the first end of the second cooling channel becomes a discharge port; After the temperature of the second cooling channel is cooled to a preset temperature threshold, and when no nitrogen is discharged from the exhaust port of the second cooling channel, performing the low-temperature helium mass spectrometry leak detection; or performing cold shock treatment on the heat exchanger, and obtaining the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device during the cooling process, including: Place the heat exchanger in the cooling medium and perform immersion cold shock treatment on the heat exchanger.

[0007] Optionally, the step of performing low-temperature helium mass spectrometry leak detection on the heat exchanger includes: Selecting a heat exchange channel as a charging channel, charging helium into the charging channel, and leaving it to stand for a first period of time; Obtaining external leakage data of the charging channel and internal leakage data between adjacent heat exchange channels; Switch other heat exchange channels as charging channels in turn, and repeat the steps of filling helium into the charging channels and letting them stand for the first period of time to obtaining external leakage data of the charging channels and internal leakage data between adjacent heat exchange channels, until the external leakage data and internal leakage data of all heat exchange channels are obtained.

[0008] Optionally, the manufacturing of the core includes: Processing fins, baffles and seals, wherein the fins, baffles and seals are accessories of the core; Cleaning accessories; Assembling the core; Welding the core, wherein the core is welded by a vacuum brazing process; Check the geometric dimensions of the core; When the geometric dimensions of the core meet the requirements, water is injected into the core to detect leaks; The method for making the head includes: One-piece forged head; Clean the head; Machining steel and aluminum joints; Cleaning steel and aluminum joints; Welding steel-aluminum joints to the header; Check the geometric dimensions of the whole formed by the head and the steel-aluminum joint; When the overall geometric dimensions of the head and the steel-aluminum joint meet the requirements, perform X-ray inspection on the butt weld; When the core body water injection leak detection and X-ray detection of the butt weld meet the requirements, the core body is connected to the head to make a heat exchanger; The core body and the head are connected to form a heat exchanger, comprising: Weld the head to the core.

[0009] Optionally, the step of performing normal temperature detection on the heat exchanger includes: Penetrant testing of fillet welds; When the fillet weld meets the requirements, the geometric dimensions of the heat exchanger are inspected; When the geometric dimensions of the heat exchanger meet the requirements, the heat exchanger is subjected to overall immersion leak detection.

[0010] Optionally, the step of performing normal temperature detection on the heat exchanger includes: When the overall immersion leak detection meets the requirements, perform pressure test on the heat exchanger; The stress test includes: Introduce pressure test gas into the heat exchange channel of the heat exchanger, increase the pressure to 10% of the specified test pressure, maintain it for a second period, and check for air leaks at all welds and joints; In the absence of leakage, increase the pressure to 50% of the specified test pressure and check for air leakage at all welds and joints; In the absence of leakage, increase the pressure step by step by 10% of the specified test pressure, and detect the leakage of all welds and joints until the pressure reaches the test pressure. Maintain the pressure for the third time and detect the leakage of all welds and joints. Optionally, the step of performing normal temperature detection on the heat exchanger includes: Conduct air tightness test on heat exchanger; The airtightness test includes: Introduce airtightness test gas into the heat exchange channel of the heat exchanger, increase the pressure to 10% of the specified test pressure, maintain it for the fourth time, and check all welds and joints for air leakage; In the absence of leakage, increase the pressure to 50% of the specified test pressure and check for air leakage at all welds and joints; In the absence of leakage, increase the pressure step by step by 10% of the specified test pressure and maintain it for the fifth time, and check all welds and joints for air leakage until the pressure reaches the test pressure.

[0011] Optionally, the step of performing normal temperature detection on the heat exchanger includes: When the pressure test meets the requirements, the heat exchanger is tested for leaks by helium mass spectrometry at room temperature; The room temperature helium mass spectrometer leak detection comprises: External leakage detection and internal leakage detection; The leakage detection comprises: A cover chamber is formed by a polyethylene plastic bag, a heat exchanger is placed in the cover chamber, and the air in the cover chamber is exhausted; Helium is introduced into the chamber to an atmospheric pressure; When the volume of the mask chamber is greater than the preset volume, standing for a sixth period of time; Sequentially evacuate each heat exchange channel of the heat exchanger to a pressure lower than a second preset pressure threshold, and detect leakage rate data; The internal leakage detection comprises: Select a heat exchange channel in the heat exchanger as the channel to be tested; Introduce helium gas to one atmosphere pressure into the heat exchange channel adjacent to the channel under test; The channel under test is evacuated to a pressure lower than a third preset pressure threshold, and the pressure is maintained for a seventh time period; Detect the leak rate data of the measured channel.

[0012] Optionally, after the low temperature detection of the heat exchanger, the method further comprises: Explosion and purge the heat exchanger; The blasting and purging of the heat exchanger comprises: Step 1: Select a heat exchange channel for blasting and purging; The second step: using blasting materials to block the outlet of the selected heat exchange channel; The third step: injecting high-pressure nitrogen through the inlet of the selected heat exchange channel; Step 4: performing high-pressure blasting on the selected heat exchange channel, and detecting the particle concentration at the outlet of the selected heat exchange channel after the blasting; Step 5: When the particle concentration at the outlet of the selected heat exchange channel is greater than the preset concentration value, repeat the blasting until the particle concentration at the outlet is less than or equal to the preset concentration value; Step 6: Use blasting materials to block the entrance of the selected heat exchange channel; Step 7: injecting high-pressure nitrogen through the outlet of the selected heat exchange channel; Step 8: Perform high-pressure blasting on the selected heat exchange channel, and detect the particle concentration at the entrance of the selected heat exchange channel after blasting; Step 9: When the particle concentration at the inlet of the selected heat exchange channel is greater than the preset concentration value, repeat the blasting until the particle concentration at the inlet is less than or equal to the preset concentration value; Step 10: sequentially switch other heat exchange channels for blasting and purging, and repeat the first step to the ninth step until all heat exchange channels have completed blasting and purging; After the heat exchanger is blasted and purged, the method further comprises: Conduct cleanliness test on heat exchanger; The cleanliness detection of the heat exchanger comprises: Use an endoscope to reach into each heat exchange channel of the heat exchanger for inspection.

[0013] Optionally, the method further includes: When the cleanliness test meets the requirements, the heat exchanger is tested for flow and heat transfer performance; When the flow and heat transfer performance test meets the requirements, clean the inner and outer surfaces of the heat exchanger; Welding nameplate; The flow heat transfer performance test of the heat exchanger includes: Measure the cold side fluid pressure drop of the heat exchanger; Perform efficiency tests on heat exchangers.

[0014] Beneficial effects: A processing method for a 2K negative pressure aluminum plate-fin heat exchanger provided in an embodiment of the present invention performs a variety of tests on the 2K negative pressure plate-fin heat exchanger, including cryogenic helium mass spectrometry leak detection. When performing cryogenic helium mass spectrometry leak detection, it can simulate a real low temperature environment to ensure the accuracy of leak detection. Through the processing method provided in the present invention, a heat exchanger with a micro-leakage rate, high mechanical strength, compact size, and high cleanliness can be obtained, greatly improving the processing efficiency and yield rate of the 2K negative pressure heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of a processing method according to embodiment 1 of the present invention; Figure 2 is a flow chart of a processing method according to Embodiment 3 of the present invention; Figure 3 This is a schematic structural diagram of a low-temperature helium mass spectrometer leak detection device according to Example 3 of the present invention; Figure 4 It is a structural schematic diagram of an external leakage detection device in room temperature helium mass spectrometry leak detection according to Example 3 of the present invention; Figure 5 It is a structural schematic diagram of the internal leakage detection equipment in the room temperature helium mass spectrometer leak detection in Example 3 of the present invention.

[0016] The reference numerals are as follows: 1. Liquid nitrogen container; 2. Third helium mass spectrometer leak detector; 3. Vacuum pump system; 4. Chiller; 5. First helium cylinder; 6. First pressure reducing gauge; 7. Polyethylene plastic bag; 8. Heat exchanger; 9. First vacuum gauge; 10. First vacuum valve; 11. First vacuum pump; 12. First standard leak; 13. Second vacuum valve; 14. First helium mass spectrometer leak detector; 15. Second helium cylinder; 16. Second pressure reducing gauge; 17. Second vacuum gauge; 18. Third vacuum valve; 19. Second vacuum pump; 20. Second standard leak; 21. Fourth vacuum valve; 22. Second helium mass spectrometer leak detector. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0018] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0019] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0021] See also Figure 1 As shown, according to Embodiment 1 of the present invention, a method for processing a 2K negative pressure aluminum plate-fin heat exchanger is provided, comprising: Step 101: Make the core.

[0022] In this step, the accessories in the core body are first assembled together and then welded and fixed by vacuum brazing to form the core body, thereby ensuring that the core body has good strength.

[0023] Specifically, the accessories of the core include guide vanes, partitions, heat transfer fins, seals, side panels, etc. The accessories are fixed together by assembly tools. Heat transfer fins and seals are placed between two adjacent partitions to form a sandwich, called a heat exchange channel. The sandwich is stacked and brazed into a whole according to different flow modes of the fluid to form a core.

[0024] Among them, the accessories that need to be brazed together are welded by a vacuum brazing process. During brazing, the core is placed in a high-temperature brazing furnace for brazing treatment.

[0025] Step 102: manufacturing a head, wherein the process for manufacturing the head includes integrally forging the head.

[0026] In this step, the head can be forged in one piece, which can reduce the number of welds, reduce the risk of leakage and increase the mechanical strength, so that the head has the advantages of low leakage rate and high strength.

[0027] Step 103: Connect the core body and the head to form a heat exchanger 8.

[0028] In this step, the core body and the head are welded together to ensure good connection strength between the core body and the head, thereby ensuring good stability of the heat exchanger 8 as a whole.

[0029] The core is assembled in a dust-free workshop equipped with a negative pressure and ventilation system to reduce dust pollution inside the core. The workshop is designed as a negative pressure environment to prevent dust from spreading to other areas. Before assembling the fins, the dust-free workshop is ventilated using a ventilation system. The ventilation system is reasonably planned to ensure that dust enters the dust removal equipment through directional airflow.

[0030] Step 104: Perform a normal temperature test on the heat exchanger 8, where the temperature range of the normal temperature test is 20°C to 30°C.

[0031] In this step, room temperature detection may include weld detection, appearance detection, liquid immersion leak detection, pressure testing, room temperature helium mass spectrometry leak detection, etc.

[0032] Step 105: Perform low temperature detection on the heat exchanger 8, wherein the temperature range of the low temperature detection is below -150°C.

[0033] In this step, by performing low-temperature testing on the heat exchanger 8, the sealing performance of the heat exchanger 8 in a simulated test of a deep low-temperature environment can be achieved, ensuring that the heat exchanger 8 meets the design specifications and requirements, ensuring that the quality of the heat exchanger 8 meets the standards, and ensuring the performance, stability and reliability of the heat exchanger 8 under actual use conditions.

[0034] Embodiment 2 of the present invention is a refinement and extension of the specific implementation of step 105 in the above-mentioned embodiment 1, and illustrates the implementation process of step 105 in embodiment 1.

[0035] Step 105 includes: Step 1051: evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located.

[0036] In this step, the heat exchanger 8 is placed in a closed device, and the internal space of the closed device and the heat exchange channels of the heat exchanger 8 are evacuated by the vacuum pump system 3, so that the pressure in the heat exchange channels in the heat exchanger 8 and the internal space of the closed device is less than or equal to 5Pa.

[0037] Step 1052: When the vacuum degree is less than the first preset pressure threshold, the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger 8 are obtained.

[0038] In this step, the first preset pressure threshold is a preset test pressure threshold, and the first preset pressure threshold can be adjusted and modified according to actual needs. When the vacuum degree is less than the first preset pressure threshold, the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger 8 are observed.

[0039] Step 1053: perform cold shock treatment on the heat exchanger 8, and obtain the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger 8 and the background leakage rate and vacuum degree of the closed device during the cooling process.

[0040] In this step, liquid nitrogen may be introduced into the heat exchanger 8 to perform cold shock treatment on the heat exchanger 8. During the cooling process, the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger 8 and the background leakage rate and vacuum degree of the sealed device are continuously or intermittently obtained and observed to obtain the changes in vacuum degree and background leakage rate.

[0041] Specifically, if the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger 8 and the background leakage rate and vacuum degree of the closed device are obtained and observed intermittently, the interval time may be the same or different and may be flexibly set according to actual conditions.

[0042] Specifically, liquid nitrogen may be introduced into the heat exchanger 8 through the liquid nitrogen container 1 , thereby performing a cold shock treatment on the heat exchanger 8 .

[0043] Step 1054: When the temperature is cooled to a preset temperature threshold, a low-temperature helium mass spectrometer leak test is performed on the heat exchanger 8 .

[0044] Performing low-temperature helium mass spectrometry leak detection on the heat exchanger 8 can simulate a real low-temperature environment and ensure the accuracy of leak detection. It can obtain a heat exchanger 8 with a very low leakage rate, high mechanical strength, compact size, and high cleanliness, greatly improving the processing efficiency and yield rate of the 2K negative pressure heat exchanger 8.

[0045] Embodiment 3 of the present invention is a refinement and extension of the specific implementation of the above-mentioned embodiment 1, and fully illustrates the specific implementation process of embodiment 1.

[0046] like Figure 2 As shown, this embodiment 3 provides a processing method for a 2K negative pressure aluminum plate-fin heat exchanger, comprising: Step 2011: Processing fins, partitions and seals, wherein the fins, partitions and seals are accessories of the core.

[0047] In this step, the fins, partitions and seals are processed separately to obtain the accessories of the core.

[0048] Step 2012: Clean the accessories.

[0049] In this step, the accessories of the core are cleaned. The accessories include fins, partitions and seals, and may also include guide vanes and side panels. By cleaning the accessories, the cleanliness of the interior of the heat exchanger 8 is effectively improved, the impurity contamination of the heat exchanger 8 during operation is reduced, and the possibility of damaging the helium cryogenic system is reduced.

[0050] Step 2013: Assemble the core.

[0051] In this step, the fins, partitions, seals, guide vanes, side panels and other accessories are assembled and fixed together by tooling. The tooling used is prior art and will not be described in detail here.

[0052] Step 2014: welding the core body. The core body is welded by using a vacuum brazing process.

[0053] In this step, the core body may be placed in a high temperature brazing furnace for brazing treatment.

[0054] Perform step 2015: geometric dimension check on the core.

[0055] If the geometric dimensions of the core body meet the requirements, the step 2016 is performed: injecting water into the core body to detect leaks. If the geometric dimensions of the core body do not meet the requirements, the core body is remade.

[0056] In step 216, water is injected into the core body to detect leakage, thereby ensuring that the core body has good sealing performance to a certain extent. If the leakage detection of the core body after water injection does not meet the requirements, the core body is remade.

[0057] Step 2021: One-piece forging of the head.

[0058] In this step, by integrally forging the head, the number of welds can be reduced, the risk of leakage can be lowered, and the mechanical strength can be increased, so that the head has the advantages of low leakage rate and high strength.

[0059] The existing head is made of multiple parts spliced ​​and welded, which has the defects of high leakage risk, low mechanical strength and bulkiness. In this embodiment, the head is forged in one piece, which greatly reduces the leakage risk and increases the mechanical strength. Since the thickness of the head can be reduced by one piece forging, the volume and weight of the head are reduced, and the appearance is more beautiful.

[0060] Step 2022: Clean the head.

[0061] In this step, the head is cleaned to effectively improve cleanliness and reduce impurity contamination.

[0062] While processing the head, or before or after processing the head, step 2023: processing the steel-aluminum joint can be performed.

[0063] Among them, the steel-aluminum joint is one of the accessories of the heat exchanger 8. The steel-aluminum joint is fixedly connected to the head and connected to the core together with the head.

[0064] Step 2024: Clean the steel-aluminum joints.

[0065] In this step, the steel-aluminum joints are cleaned to effectively improve cleanliness and reduce impurity contamination.

[0066] Step 2025: Weld the steel-aluminum joint to the head.

[0067] In this step, the steel-aluminum joint is fixed to the head by welding to form a stable whole.

[0068] Step 2026: geometric dimension inspection is performed on the whole formed by the head and the steel-aluminum joint.

[0069] If the overall geometric dimensions of the end cap and the steel-aluminum joint meet the requirements, proceed to step 2027: X-ray inspection of the butt weld. If the overall geometric dimensions of the end cap and the steel-aluminum joint do not meet the requirements, remake the end cap and the steel-aluminum joint.

[0070] In step 2027, X-ray inspection of the butt weld formed by the head and the steel-aluminum joint can accurately detect defects such as pores, slag inclusions, and incomplete penetration inside the weld, thereby reducing the risk of leakage.

[0071] When the core body water injection leak detection and X-ray detection of the butt weld meet the requirements, step 2028 is performed: the core body is connected to the head to form a heat exchanger 8.

[0072] In the above steps, the core and head components are made separately, and the processing technology and quality standards can be formulated according to their respective characteristics. When the core is made, a series of processes from the processing of fins, partitions and seals to cleaning, assembly, welding, geometric dimension inspection and water injection leak detection can accurately control the internal structure and sealing performance of the core. When the head is made, the one-piece forged head reduces the number of welds and reduces the risk of leakage. The subsequent cleaning, processing, welding, geometric dimension inspection of the head and steel-aluminum joints, and X-ray inspection of the butt welds can ensure the strength and sealing of the head assembly, thereby accurately controlling the quality of the heat exchanger 8.

[0073] Specifically, step 2028: connecting the core body to the head, includes: welding the head to the core body.

[0074] Step 2031: Penetrant testing of fillet welds.

[0075] In this step, a penetrant containing a color dye or fluorescent agent is applied to the surface of the fillet weld. Due to capillary action, the penetrant will penetrate into the open defects on the weld surface. The excess penetrant on the surface is then removed, and a developer is applied. The developer will absorb the penetrant in the defect and expand it on the surface. By observing the displayed traces, the location, shape and size of the defect can be determined. By inspecting the fillet weld with a penetrant, open defects such as tiny cracks and looseness on the surface of the fillet weld can be accurately detected.

[0076] Specifically, in weld inspection, butt welds are inspected by X-rays, and fillet welds are inspected by penetrants.

[0077] More specifically, in the X-ray inspection, before the head and the steel-aluminum joint are welded to the core, the butt weld between the head and the steel-aluminum joint is X-ray inspected. After the head and the steel-aluminum joint are welded to the core, the fillet weld between the head and the core is penetrant inspected.

[0078] If the fillet weld meets the requirements, step 2032: geometric dimension inspection is performed on the heat exchanger 8. If the fillet weld does not meet the requirements, the head and the core are re-welded.

[0079] If the geometric dimensions of the heat exchanger 8 meet the requirements, the step 2033 is performed: the whole is immersed for leak detection. If the geometric dimensions of the heat exchanger 8 do not meet the requirements, the head and the core are re-welded.

[0080] In step 2033, the heat exchanger 8 is completely immersed in the leak detection liquid, and then a certain pressure of gas is filled into the heat exchanger 8. If there is a leak in the heat exchanger 8, the gas will escape from the leak and generate bubbles in the liquid. By observing the location and number of bubbles, the location of the leak and the severity of the leak can be determined. The sealing performance of the heat exchanger 8 is guaranteed by the overall immersion leak detection.

[0081] If the overall immersion leak detection meets the requirements, step 2034: pressure test is performed. If the overall immersion leak detection does not meet the requirements, the core body and the head are remade and re-welded.

[0082] Specifically, step 2034: stress testing includes: Step 20341: Introduce pressure test gas into the heat exchange channel of the heat exchanger 8, increase the pressure to 10% of the specified test pressure, maintain for the second time period, and check for air leaks in all welds and joints.

[0083] In this step, the pressure test gas may be dry and clean air, nitrogen or other inert gas. The second time length may be flexibly set according to actual needs. In this embodiment, the second time length is 5 to 10 minutes.

[0084] Specifically, when introducing the pressure test gas, first slowly increase the pressure to 10% of the specified test pressure, maintain it for 5 to 10 minutes, and check all welds and joints to see if there are any leaks.

[0085] Step 20342: In the absence of leakage, increase the pressure to 50% of the specified test pressure and check all welds and joints for leaks.

[0086] Specifically, after increasing the pressure to 50% of the specified test pressure, maintain it for 5 to 10 minutes and check all welds and joints to see if there are any leaks.

[0087] Step 20343: In the absence of leakage, increase the pressure step by step to 10% of the specified test pressure, and check all welds and joints for leaks until the pressure reaches the test pressure. Maintain the pressure for the third time and check all welds and joints for leaks.

[0088] In this step, the third duration can be flexibly set according to actual needs. In this embodiment, the third duration is 10 to 15 minutes.

[0089] Specifically, in the absence of leakage, each pressure increase is made by 10% of the specified test pressure, that is, each time the pressure is increased by 10% of the specified test pressure, it is maintained for 5 to 10 minutes, and all welds and joints are checked for leaks. After the pressure is increased to the test pressure, it is maintained for 10 to 15 minutes, and all welds and joints are checked for leaks. The pressure should remain unchanged during the inspection.

[0090] During step 2034, the pressure vessel is qualified only if there is no abnormal sound, and there is no leakage and visible deformation after leakage detection with leak detection fluid.

[0091] Optionally, as a feasible implementation, the heat exchanger 8 may also be subjected to an air tightness test.

[0092] Air tightness test, including: Introduce airtightness test gas into the heat exchange channel of the heat exchanger 8, increase the pressure to 10% of the specified test pressure, maintain it for the fourth time, and check all welds and joints for air leakage.

[0093] Specifically, the airtightness test gas may be dry and clean air, nitrogen or other inert gases. The fourth time period may be flexibly set according to actual needs. In this embodiment, the fourth time period is 5 to 10 minutes.

[0094] More specifically, when introducing the airtightness test gas, first slowly increase the pressure to 10% of the specified test pressure, maintain it for 5 to 10 minutes, and check all welds and joints to see if there are any leaks.

[0095] In the absence of leakage, increase the pressure to 50% of the specified test pressure and check for air leakage at all welds and joints.

[0096] Specifically, after increasing the pressure to 50% of the specified test pressure, maintain it for 5 to 10 minutes and inspect all welds and joints to check for leaks.

[0097] In the absence of leakage, increase the pressure step by step by 10% of the specified test pressure and maintain it for the fifth time, and check all welds and joints for air leakage until the pressure reaches the test pressure.

[0098] Specifically, the fifth duration can be flexibly set according to actual needs. In this embodiment, the fifth duration is 10 to 15 minutes.

[0099] More specifically, in the absence of leakage, each pressure increase is performed step by step by 10% of the specified test pressure, that is, each time the pressure is increased by 10% of the specified test pressure, it is maintained for 5 to 10 minutes, and all welds and joints are inspected to see if there is any leakage. After the pressure is increased to the test pressure, it is maintained for 10 to 15 minutes, and all welds and joints are inspected to see if there is any leakage. The pressure should remain unchanged during the inspection.

[0100] During the air tightness test, the system is qualified if there is no leakage after checking with leak detection fluid.

[0101] When the pressure test meets the requirements, proceed to step 2035: room temperature helium mass spectrometer leak detection.

[0102] Specifically, step 2035: room temperature helium mass spectrometer leak detection includes: step 20351: external leak detection and step 20352: internal leak detection.

[0103] Figure 4 The figure shows the leakage detection equipment in the room temperature helium mass spectrometer leak detection, through which the heat exchanger 8 is leak tested.

[0104] Step 20351: Leakage detection, including: Step 203511: A cover chamber is formed by using a polyethylene plastic bag 7, a heat exchanger 8 is placed in the cover chamber, and the air in the cover chamber is exhausted.

[0105] In this step, the air in the hood chamber is evacuated by the first vacuum pump 11. After the vacuuming is completed, the flow path between the first vacuum pump 11 and the hood chamber is disconnected by the first vacuum valve 10. The first vacuum gauge 9 is provided and connected to the heat exchanger 8 and the hood chamber respectively, so as to detect the vacuum degree of the heat exchanger 8 and the hood chamber.

[0106] Step 203512: Introduce helium into the cover chamber to an atmospheric pressure.

[0107] In this step, after the first vacuum pump 11 is disconnected from the mask chamber through the first vacuum valve 10, helium is introduced into the mask chamber to an atmospheric pressure through the first helium bottle 5. The air pressure is adjusted by the first decompression gauge 6 disposed between the first helium bottle 5 and the mask chamber.

[0108] Step 203513: When the volume of the mask chamber is greater than the preset volume, let it stand for a sixth period of time.

[0109] In this step, the preset volume and the sixth duration can be flexibly set according to actual needs. In this embodiment, the preset volume is 100L and the sixth duration is 15 minutes.

[0110] Among them, when the volume of the mask chamber is less than or equal to the preset volume, the standing time can be appropriately shortened, for example, standing for 10 minutes.

[0111] Step 203514: evacuate each heat exchange channel of the heat exchanger 8 in turn to a pressure lower than a second preset pressure threshold, and detect the leakage rate data.

[0112] In this step, the second preset pressure threshold can be flexibly set according to actual needs. In this embodiment, the second preset pressure threshold is 50Pa, that is, when each heat exchange channel of the heat exchanger 8 is evacuated to less than 50Pa in turn, the leakage rate data is detected by the first helium mass spectrometer leak detector 14.

[0113] A branch is provided on the flow path between the first vacuum valve 10 and the first helium mass spectrometer leak detector 14 , and a second vacuum valve 13 and a first standard leak hole 12 are provided on the branch, which can be used to calibrate the leak detection equipment.

[0114] Figure 5 The internal leakage detection device in the room temperature helium mass spectrometer leak detection is shown, and the internal leakage detection device is used to perform the internal leakage detection on the heat exchanger 8.

[0115] Step 20352: Internal leakage detection, including: Step 203521: Select a heat exchange channel in the heat exchanger 8 as the channel to be tested.

[0116] In this step, the heat exchange channel with the largest volume in the heat exchanger 8 can be first selected as the channel to be tested. If there are multiple heat exchange channels with the largest volume, any heat exchange channel with the largest volume in the middle position can be selected as the channel to be tested.

[0117] Step 203522: Introduce helium gas to one atmosphere of pressure into the heat exchange channel adjacent to the channel under test.

[0118] In this step, after selecting the channel to be tested, helium is introduced into the heat exchange channel adjacent to the channel to be tested to an atmospheric pressure through the second helium cylinder 15. The air pressure is adjusted through the second pressure reducing gauge 16 between the second helium cylinder 15 and the heat exchanger 8.

[0119] Step 203523: Evacuate the channel under test to a pressure lower than the third preset pressure threshold, and maintain the pressure for the seventh time period.

[0120] In this step, the third preset pressure threshold and the seventh time length can be flexibly set according to actual needs. In this embodiment, the third preset pressure threshold is 50Pa, and the seventh time length is 15 minutes. That is, the channel to be tested is evacuated to less than 50Pa, and the pressure is maintained for 15 minutes.

[0121] The measured channel is evacuated to a pressure lower than the third preset pressure threshold by the second vacuum pump 19. After the evacuation is completed, the flow path between the second vacuum pump 19 and the measured channel is disconnected by the third vacuum valve 18. The vacuum degree of the measured channel is detected by setting a second vacuum gauge 17 and connecting the second vacuum gauge 17 to the measured channel.

[0122] Step 203524: Detect the leakage rate data of the measured channel.

[0123] In this step, the leak rate data is detected by the second helium mass spectrometer leak detector 22 .

[0124] If it is necessary to perform internal leakage detection on all heat exchange channels, each heat exchange channel in the heat exchanger 8 is taken as a channel to be tested, and the internal leakage detection is performed in sequence according to the above steps.

[0125] A branch is provided on the flow path between the third vacuum valve 18 and the second helium mass spectrometer leak detector 22 , and a fourth vacuum valve 21 and a second standard leak hole 20 are provided on the branch, which can be used to calibrate the leak detection equipment.

[0126] The heat exchanger 8 may include two groups of heat exchange channels, such as a cold fluid channel and a hot fluid channel. In step 20351 of the external leakage detection and step 20352 of the internal leakage detection, the external leakage data of the cold fluid channel and the external leakage data of the hot fluid channel of the heat exchanger 8, as well as the internal leakage data between the cold fluid channel and the hot fluid channel are obtained. The worst value of the three groups of leakage rate data is selected as the leakage rate of the heat exchanger 8.

[0127] If step 2035 does not meet the requirements, the core and the head are remade and re-welded. If step 2035 meets the requirements, the heat exchanger 8 is moved to the low-temperature helium mass spectrometer leak detection device, and then the heat exchanger 8 is tested at low temperature. The low-temperature helium mass spectrometer leak detection device includes the above-mentioned sealing device. That is, if step 2035 meets the requirements, the heat exchanger 8 is moved to the sealing device of the low-temperature helium mass spectrometer leak detection device.

[0128] Specifically, three platinum thermal resistors are arranged at the inlet of the heat exchange channel with the largest volume in the heat exchanger 8, the middle of the side plate, and the outlet of the heat exchange channel with the largest volume in the heat exchanger 8, and the digital display monitor is powered on for monitoring. Use dry nitrogen to replace the air in each heat exchange channel being tested, as well as the helium and moist air remaining in the normal temperature helium mass spectrometer leak detection process. Check again to confirm whether all joints are connected. After confirmation, push them into the closed device of the low-temperature helium mass spectrometer leak detection device. Check the sealing flange gasket of the low-temperature helium mass spectrometer leak detection device, and apply sealing silicone grease after confirming that there are no obvious impurities. The sealing silicone grease can be applied directly by hand until it is visually uniform. Apply sealing silicone grease as needed. Close the sealing flange and tighten the bolts and nuts at the flange.

[0129] like Figure 3 As shown, the pipeline where the V1 valve is located is connected to the closed device of the cryogenic helium mass spectrometer leak detection device. The cryogenic helium mass spectrometer leak detection device includes multiple pipelines, each of which is connected to a heat exchange channel in the heat exchanger 8, and each pipeline is provided with a valve. In this embodiment, Figure 3 As shown, there are three pipelines, one of which is provided with a V4 valve, one is provided with a V5 valve, and one is provided with a V6 valve. The V4 valve, the V5 valve, and the V6 valve are used to control the on-off of the pipelines. The V2 valve is provided on the air inlet pipeline of the third helium mass spectrometer leak detector 2, and is used to control the on-off of the air inlet pipeline. The air inlet pipeline is respectively connected to the pipeline where the V1 valve is located, the pipeline where the V4 valve is located, the pipeline where the V5 valve is located, and the pipeline where the V6 valve is located. The pipeline where the vacuum pump system 3 is located is respectively connected to the pipeline where the V1 valve is located, the pipeline where the V2 valve is located, the pipeline where the V4 valve is located, the pipeline where the V5 valve is located, and the pipeline where the V6 valve is located. The V3 valve is provided on the air inlet pipeline of the vacuum pump system 3, and is used to control the on-off of the air inlet pipeline of the vacuum pump system 3. The vacuum pump system 3 is connected to a matching chiller 4.

[0130] The vacuum pump system 3 includes a mechanical pump, a Roots pump and a molecular pump which are connected in sequence.

[0131] Step 2041: evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located by a mechanical pump.

[0132] In this step, see Figure 3 , close the V2 valve, open the V1 valve, V3 valve, V4 valve, V5 valve and V6 valve, and start the mechanical pump to evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located.

[0133] Step 2042: when the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than the first intermediate pressure threshold, start the Roots pump to evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located.

[0134] In this step, the first intermediate pressure threshold can be flexibly set according to actual needs. In this embodiment, the intermediate pressure threshold is 100 Pa. That is, when the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than 100 Pa, the Roots pump in the vacuum pump system 3 is turned on to evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located.

[0135] Step 2043: When the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than the second intermediate pressure threshold, start the molecular pump to evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located, so that the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than the first preset pressure threshold.

[0136] In this step, the second intermediate pressure threshold can be flexibly set according to actual needs. In this embodiment, the intermediate pressure threshold is 20 Pa. That is, when the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than 20 Pa, the molecular pump in the vacuum pump system 3 is turned on to evacuate each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located.

[0137] Specifically, while turning on the molecular pump, start the chiller 4. Each time the molecular pump is started, press the green "start" button on the molecular pump control panel to start the molecular pump. When the controller displays that the molecular pump speed reaches the rated speed, press the red "stop" button.

[0138] When evacuating, first start the mechanical pump in the atmospheric state to obtain a low vacuum in the closed device. Roots pumps usually have a large pumping rate in the pressure range of 100 to 20Pa, and can quickly remove the suddenly released gas. This pressure range is between the mechanical pump and the molecular pump. The molecular pump can use the high-speed rotating rotor to transfer momentum to the gas molecules, so that they can obtain a directional speed, so that they are compressed and driven to the exhaust port to be pumped away by the front stage. When evacuating the closed device, these three vacuum pumps are arranged in the order of starting and in a complementary manner, and can jointly complete the conversion process from the atmospheric state to the high vacuum state inside the closed device.

[0139] When the vacuum degree of each heat exchange channel in the heat exchanger 8 and the closed device where the heat exchanger 8 is located is less than the first preset pressure threshold, step 2044 is performed: the leak detection device is connected to the closed device, and the leak detection device is blocked from each heat exchange channel in the heat exchanger 8 to obtain the background leakage rate of the closed device.

[0140] In this step, the first preset pressure threshold can be flexibly set according to actual needs. For example, it can be 10 -4 Specifically, after the molecular pump is turned on, the ionized silicon shows 10 -4 Pa or less, that is, 10 -4 Pa, the third helium mass spectrometer leak detector 2 is turned on, at this time the V4 valve, the V5 valve and the V6 valve are in the closed state, the V1 valve and the V2 valve are slowly opened, and then the background leakage rate of the accommodation space is obtained through the third helium mass spectrometer leak detector 2.

[0141] Step 2045: connect the leak detection device to each heat exchange channel in the heat exchanger 8 in sequence, and block the leak detection device from the sealing device to obtain the background leakage rate of each heat exchange channel in the heat exchanger 8.

[0142] In this step, the V4 valve, the V5 valve and the V6 valve are opened in sequence, and the V1 valve is closed, so that the background leakage rates of the heat exchange channel of the heat exchanger 8 corresponding to the V4 valve, the heat exchange channel of the heat exchanger 8 corresponding to the V5 valve, and the heat exchange channel of the heat exchanger 8 corresponding to the V6 valve can be obtained through the third helium mass spectrometer leak detector 2.

[0143] The heat exchange passages of the heat exchanger 8 include cold fluid passages and hot fluid passages.

[0144] Step 2046: perform cold shock treatment on the heat exchanger 8, and obtain the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger 8 and the background leakage rate and vacuum degree of the closed device during the cooling process.

[0145] In one embodiment, the heat exchanger 8 is subjected to a cold shock treatment, comprising: Step 20461: Select the cold fluid channel with the largest volume as the first cooling channel, introduce liquid nitrogen into the first end of the first cooling channel, and discharge it from the second end of the first cooling channel, so that the second end of the first cooling channel becomes the discharge port.

[0146] In this step, the liquid outlet valve of the liquid nitrogen container 1 is opened, and liquid nitrogen is introduced into the first end of the cold fluid channel with the largest volume in the heat exchanger 8 to reduce the temperature.

[0147] Step 20462: Control the cooling rate of the first cooling channel to be less than or equal to 4°C / min.

[0148] In this step, the temperature change can be detected by a digital display monitor or other detection equipment, and the cooling rate of the first cooling channel can be controlled to be less than or equal to 4°C / min. When the temperature is first cooled, the temperature data can be recorded every 10 minutes. After the cooling rate stabilizes, the temperature data can be recorded every 1 hour. If the cooling rate is too fast, the opening of the liquid outlet valve of the liquid nitrogen container 1 can be adjusted to adjust the flow rate.

[0149] When the temperature difference between the first end of the first cooling channel and the second end of the first cooling channel is greater than the preset temperature difference threshold, and the cooling rate is less than the preset rate threshold, step 20463 is performed: liquid nitrogen is introduced into the second end of the first cooling channel and discharged from the first end of the first cooling channel, so that the first end of the first cooling channel becomes the discharge outlet.

[0150] In this step, the preset temperature difference threshold may be 10° C. The preset rate threshold may be 1° C. / min.

[0151] Specifically, during the cooling process, when the temperature of one end where liquid nitrogen is introduced drops to a preset temperature difference threshold, the discharge port may still be in a relatively high temperature state, and the cooling rate is very small, that is, when the temperature difference between the first end and the second end of the first cooling channel is greater than the preset temperature difference threshold, and the cooling rate is less than the preset rate threshold, liquid nitrogen is introduced into the second end of the first cooling channel and discharged from the first end of the first cooling channel, thereby further uniformly cooling the temperature.

[0152] After the temperature of the first cooling channel is cooled to a preset temperature threshold and when no nitrogen is discharged from the exhaust port of the first cooling channel, perform step 20464: select the hot fluid channel with the largest volume as the second cooling channel, introduce liquid nitrogen into the first end of the second cooling channel, and discharge it from the second end of the second cooling channel, so that the second end of the second cooling channel becomes the exhaust port.

[0153] In this step, the liquid outlet valve of the liquid nitrogen container 1 is opened, and liquid nitrogen is introduced into the first end of the hot fluid channel with the largest volume in the heat exchanger 8 for cooling. The preset temperature threshold may be -173.15°C.

[0154] Step 20465: Control the cooling rate of the second cooling channel to be less than or equal to 4°C / min.

[0155] In this step, the temperature change can be detected by a digital display monitor or other detection equipment, and the cooling rate of the second cooling channel can be controlled to be less than or equal to 4°C / min. When the temperature is first cooled, the temperature data can be recorded every 10 minutes. After the cooling rate stabilizes, the temperature data can be recorded every 1 hour. If the cooling rate is too fast, the opening of the liquid outlet valve of the liquid nitrogen container 1 can be adjusted to adjust the flow rate.

[0156] When the temperature difference between the first end of the second cooling channel and the second end of the second cooling channel is greater than the preset temperature difference threshold, and the cooling rate is less than the preset rate threshold, perform step 20466: introduce liquid nitrogen into the second end of the second cooling channel and discharge it from the first end of the second cooling channel, so that the first end of the second cooling channel becomes the discharge outlet.

[0157] In this step, the preset temperature difference threshold may be 10° C. The preset rate threshold may be 1° C. / min.

[0158] Specifically, during the cooling process, when the temperature of the end where liquid nitrogen is introduced drops to the preset temperature difference threshold, the outlet may still be at a relatively high temperature, and the cooling rate is very small, that is, when the temperature difference between the first end and the second end of the second cooling channel is greater than the preset temperature difference threshold, and the cooling rate is less than the preset rate threshold, liquid nitrogen is introduced into the second end of the second cooling channel and discharged from the first end of the second cooling channel, further uniformly cooling the temperature. The formula is as follows:

[0159] In order to provide operators with more accurate flow values ​​and avoid blind adjustments by operators, the cooling rate of the heat exchanger can be effectively controlled by controlling the liquid nitrogen flow rate u The functional relationship is dominated by the 0.8 power of the flow velocity u, and is driven by the heat transfer area, the thermal properties of the working fluid and the temperature difference.

[0160] Where dT is the temperature change, dt is the time change, C The geometric dimensions of the heat exchanger flow channel (such as hydraulic diameter D h ) related dimensionless coefficients; A 0 is the reference heat transfer area; α is the surface strengthening coefficient; η is the contact efficiency of the heat transfer surface, that is, the ratio of the actual effective heat transfer area to the theoretical area ( 0≤η≤1 ), affected by surface roughness and wettability; V is the volume of the working fluid; ρ is the working fluid density; c p is the specific heat capacity of the working fluid; T m is the ambient temperature; T is the working fluid temperature; TT m is the working fluid-medium temperature difference.

[0161] According to the target cooling rate r target Back-propagation to desired flow rate u set The formula is:

[0162] in, C The geometric dimensions of the heat exchanger flow channel (such as hydraulic diameter D h ) related dimensionless coefficients; A 0 is the reference heat transfer area; α is the surface strengthening coefficient; η is the contact efficiency of the heat transfer surface, that is, the ratio of the actual effective heat transfer area to the theoretical area ( 0≤η≤1 ), affected by surface roughness and wettability; V is the volume of the working fluid; ρ is the working fluid density; c p is the specific heat capacity of the working fluid; T m is the ambient temperature; T is the working fluid temperature; TT m is the working fluid-medium temperature difference.

[0163] Specifically, the minimum flow rate u min ≥0.1m / s (avoid laminar flow causing a sudden drop in heat transfer efficiency), maximum flow rate u max ≤5m / s (limited by pump power and pressure drop).

[0164] The specific calculation example is as follows: the known parameters are set as shown in Table 1:

[0165] Calculate the effective heat transfer area A( η ):

[0166] Calculate the comprehensive constant k:

[0167] Reverse flow rate u set :

[0168]

[0169] Due to the superfluid helium effect, if the system temperature is lower than 2.17K (λ point), the liquid helium enters the superfluid state, the heat transfer coefficient is significantly improved, and the actual required flow rate can be further reduced.

[0170] In some possible embodiments, the flow rate is obtained by the above formula u set , the actual initial flow rate is set to A1 u set， Where A1 is a coefficient between 0 and 1.

[0171] Specifically, the actual initial flow rate is set to 0.3 u set、 0.4 u set、 0.5 u set、 0.6 u set . Measure the actual cooling rate, compare it with the target cooling rate, and make fine adjustments to the flow rate.

[0172] In another embodiment, the heat exchanger 8 is subjected to a cold shock treatment, including: placing the heat exchanger in a cooling medium, and subjecting the heat exchanger to an immersion cold shock treatment.

[0173] According to the size of the heat exchanger 8, an immersion cold shock device with a suitable size and shape is selected, and an appropriate amount of cooling medium is added to the immersion cold shock device. The heat exchanger 8 is immersed in the low-temperature cooling medium. The temperature and immersion time of the cooling medium are controlled. After the immersion cold shock is completed, the heat exchanger 8 is taken out of the cooling medium to complete the immersion cold shock process.

[0174] In the process from step 20461 to step 20466, the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger 8 and the background leakage rate and vacuum degree of the sealing device are obtained.

[0175] Specifically, the V4 valve, the V5 valve, and the V6 valve can be opened in sequence, and the V1 valve and the V3 valve can be closed, and the V2 valve can be opened, so that the background leakage rate and vacuum degree of the heat exchange channel of the heat exchanger 8 corresponding to the V4 valve, the heat exchange channel of the heat exchanger 8 corresponding to the V5 valve, and the heat exchange channel of the heat exchanger 8 corresponding to the V6 valve can be obtained through the third helium mass spectrometer leak detector 2. The V1 valve and the V2 valve are opened, and the V3 valve, the V4 valve, the V5 valve, and the V6 valve are closed, and the background leakage rate of the closed device can be obtained through the third helium mass spectrometer leak detector 2.

[0176] After the temperature of the second cooling channel is cooled to a preset temperature threshold, and when no nitrogen is discharged from the exhaust port of the second cooling channel, a low temperature helium mass spectrometer leak detection is performed, wherein the preset temperature threshold may be -173.15°C.

[0177] Step 2047: Perform low-temperature helium mass spectrometry leak detection on the heat exchanger 8, including: Step 20471: Select a heat exchange channel as a charging channel, fill the charging channel with helium, and let it stand for a first period of time.

[0178] In this step, keep Figure 3 The V3 valve, V4 valve, V5 valve and V6 valve in the apparatus are closed, and helium is filled into the filling channel.

[0179] Step 20472: Obtain external leakage data of the charging channel and internal leakage data between adjacent heat exchange channels.

[0180] In this step, the third helium mass spectrometer leak detector 2 is connected to the sealing device, and then the external leakage data of the charging channel is obtained through the value change of the third helium mass spectrometer leak detector 2. The third helium mass spectrometer leak detector 2 is connected to the adjacent heat exchange channel of the charging channel, and then the internal leakage data between the adjacent heat exchange channels is obtained through the value change of the third helium mass spectrometer leak detector 2.

[0181] Step 20473: sequentially switch other heat exchange channels as charging channels, repeatedly fill the charging channels with helium, and let them stand for a first period of time; obtain external leakage data of the charging channels, and internal leakage data between adjacent heat exchange channels; until the external leakage data and internal leakage data of all heat exchange channels are obtained.

[0182] In this step, other heat exchange channels can be switched in sequence to serve as charging channels for leak detection in the order of the V4 valve, the V5 valve, and the V6 valve.

[0183] Among them, before switching the V4 valve, the V5 valve and the V6 valve, the V2 valve must be closed to prevent the third helium mass spectrometer leak detector 2 from entering the atmosphere and damaging the third helium mass spectrometer leak detector 2 .

[0184] The pressure of the heat exchange channel filled with helium is maintained at the working pressure of the heat exchange channel and the maximum pressure difference between adjacent heat exchange channels. For example, the heat exchanger 8 has four groups of heat exchange channels, the design pressure is 2.5MPa, and the operating pressures are 1.0MPa, 0.5MPa, 0.2MPa, and 0.1MPa, respectively. The pressure is maintained at the highest working pressure of 1.0MPa.

[0185] The heat exchanger 8 may include two groups of heat exchange channels, such as a cold fluid channel and a hot fluid channel. In step 20472, external leakage data of the cold fluid channel and the hot fluid channel of the heat exchanger 8, as well as internal leakage data between the cold fluid channel and the hot fluid channel are obtained. The worst value of the three groups of leakage rate data is selected as the cryogenic helium mass spectrometry leak detection data of the heat exchanger 8.

[0186] Step 2047: After the heat exchanger 8 is leak tested by cryogenic helium mass spectrometry, the method further includes: Step 2048: Perform vacuuming twice, then perform vacuuming three times, and repeat the process until the i-th vacuuming is performed to calculate the total leakage rate, where i is an integer greater than 3.

[0187] Specifically, in a possible embodiment, based on the principle of mass conservation, the multi-stage pumping process can be modeled as a dynamic leakage system of a series of cavities. Assuming that the pumping speed in each stage is constant and the leakage source is in a steady-state flow state, the total leakage rate can be decomposed into the linear superposition of the leakage rates in each independent pressure interval. By introducing the effective pumping speed correction coefficient and the pressure decay function, the total leakage rate formula of the system is derived:

[0188] In the formula, is the effective pumping speed of the i-th stage, is the i-th stage equilibrium pressure, is the weight factor of the i-th level leakage path. The above formula quantifies the contribution of different vacuum stages to the total leakage rate and provides a theoretical basis for determining leakage.

[0189] In another possible embodiment, vacuuming is performed twice, the equivalent leakage rate of the second stage is calculated, and vacuuming is performed three times to calculate the equivalent leakage rate of the third stage. The cycle is repeated until the i-th vacuuming is performed, the equivalent leakage rate of the i-th stage is calculated, and the total leakage rate is calculated, where i is an integer greater than 3. When the system reaches a steady state at the i-th vacuum stage, the leakage gas flow rate is balanced with the pumping rate, satisfying:

[0190] In the formula, is the equivalent leakage rate of the i-th level (Pa·m 3 / s), is the effective pumping speed of the i-th stage (m 3 / s), is the equilibrium pressure of the i-th stage (Pa), is the ultimate vacuum of the i-th stage vacuum pump (Pa).

[0191] For an n-stage vacuum system, the total leakage rate is the cumulative effect of the leakage rates of each stage. Considering the independence of the leakage paths and the nonlinear characteristics of the pressure difference, the total leakage rate can be expressed as:

[0192] In the formula, is the i-th stage pumping time (s); =V / ; is the characteristic time constant of the i-th level (s); V is the system volume (m 3 ); It is an exponential term, which reflects the effect of pressure decay on leakage rate during non-steady-state pumping.

[0193] This embodiment adopts progressive pressure gradient control, which can isolate the interference of tiny leaks and macro leaks at different vacuum levels, thereby improving the sensitivity of leak rate detection; secondly, the graded operation can effectively shorten the equilibrium time required for the system to reach a steady-state vacuum, and avoid the nonlinear response problem caused by the sudden drop in pressure during the traditional single-stage vacuum pumping process; in addition, this method can reduce the continuous load of the vacuum pump by releasing the residual stress in stages, thereby extending the service life of key equipment.

[0194] After step 2048, the following steps are also included: Step 20491, closing the vacuum system to break the vacuum inside the sealed device; Step 20492, after the heat exchanger 8 is reheated, the reheating rate of the heat exchanger 8 is controlled; Specifically, the reheating rate of the heat exchanger 8 must be strictly controlled within 4°C / min, and it is prohibited to open the sealing device before the heat exchanger 8 is reheated to room temperature.

[0195] Step 20493: When the heat exchanger 8 returns to normal temperature, take the heat exchanger 8 out of the sealed device.

[0196] After the heat exchanger 8 is taken out of the sealed device, step 205 is performed: the heat exchanger 8 is subjected to explosive blowing. Specifically, the step 205 includes: Step 1: Select a heat exchange channel for blasting and purging.

[0197] In this step, one heat exchange channel is selected from all heat exchange channels, and the selected heat exchange channel is firstly subjected to explosion and purge.

[0198] The second step: using blasting materials to block the outlet of the selected heat exchange channel.

[0199] In this step, blasting materials are used to block the outlet of the selected heat exchange channel, which can accumulate the pressure of high-pressure nitrogen in the selected heat exchange channel. When the pressure reaches a certain level, it triggers an explosion, which can generate a strong impact force, effectively remove impurities in the heat exchange channel, and improve the cleaning effect.

[0200] The third step: injecting high-pressure nitrogen through the inlet of the selected heat exchange channel.

[0201] In this step, high-pressure nitrogen can be used as a power source for blasting and purging. During blasting, high-pressure nitrogen can push particles, impurities, etc. in the heat exchange channel out with the airflow, thereby achieving a cleaning effect on the heat exchange channel.

[0202] The fourth step: performing high-pressure blasting on the selected heat exchange channel, and detecting the particle concentration at the outlet of the selected heat exchange channel after the blasting.

[0203] Step 5: When the particle concentration at the outlet of the selected heat exchange channel is greater than the preset concentration value, the blasting is repeated until the particle concentration at the outlet is less than or equal to the preset concentration value.

[0204] In this step, through multiple high-pressure blasting, the impurities that are difficult to clean in the heat exchange channel are gradually removed to ensure that the selected heat exchange channel meets a high cleanliness standard. By comparing the particle concentration at the outlet with the preset concentration value, a basis is provided for judging whether the heat exchange channel is clean and the cleaning quality is guaranteed.

[0205] Among them, the particle concentration at the outlet of the selected heat exchange channel is detected by a particle counter. The detection standard is that the number of particles with a diameter greater than 5µm is less than 10 / cm², and the detection standard is also the preset concentration value. If the standard is not met, repeated blasting, dismantling and transformation, or even scrapping and re-production are carried out.

[0206] Step 6: Use blasting materials to block the entrance of the selected heat exchange channel.

[0207] In this step, the inlet of the selected heat exchange channel is blocked with explosive materials, which can change the direction of the airflow during the explosive purge and further improve the comprehensiveness of the cleaning.

[0208] Step 7: Inject high-pressure nitrogen through the outlet of the selected heat exchange channel.

[0209] In this step, high-pressure nitrogen can be used as a power source for blasting and purging. During blasting, high-pressure nitrogen can push particles, impurities, etc. in the heat exchange channel out with the airflow, thereby achieving a cleaning effect on the heat exchange channel.

[0210] Step 8: Perform high-pressure blasting on the selected heat exchange channel, and detect the particle concentration at the inlet of the selected heat exchange channel after the blasting.

[0211] Step 9: When the particle concentration at the inlet of the selected heat exchange channel is greater than the preset concentration value, the blasting is repeated until the particle concentration at the inlet is less than or equal to the preset concentration value.

[0212] Among them, the particle concentration at the outlet of the selected heat exchange channel is detected by a particle counter. The detection standard is that the number of particles with a diameter greater than 5µm is less than 10 / cm², and the detection standard is also the preset concentration value. If the standard is not met, repeated blasting, dismantling and modification, or even scrapping and re-production are carried out.

[0213] In this step, through multiple high-pressure blasting, the impurities that are difficult to clean in the heat exchange channel are gradually removed to ensure that the selected heat exchange channel meets a high cleanliness standard. By comparing the particle concentration at the entrance with the preset concentration value, it provides a basis for judging whether the heat exchange channel is clean and ensures the cleaning quality.

[0214] Step 10: Switch other heat exchange channels in turn for blasting and blowing, and repeat steps 1 to 9 until all heat exchange channels have completed blasting and blowing.

[0215] All heat exchange channels are blasted and purged one by one to ensure that each heat exchange channel of the heat exchanger 8 meets high cleanliness standards to avoid affecting the overall performance and operating stability of the heat exchanger 8 due to incomplete cleaning of some heat exchange channels.

[0216] Specifically, in one embodiment, during the blasting and purging process, an air compressor or a nitrogen cylinder injects high-pressure nitrogen, generally at a pressure of 0.6 to 1.0 MPa. Highland barley paper blasting discs are used as blasting materials, with a thickness of 0.3 to 0.5 mm, and the compressive strength needs to be designed according to the purging pressure. A pressure gauge can be provided to monitor the purging pressure in real time, and the pressure gauge range is 0 to 1.5 MPa. A safety valve or a pressure relief valve can be provided on the flow path to prevent overpressure.

[0217] In this embodiment, preparations are made before blasting and purging. Close the inlet and outlet valves of the heat exchanger to ensure isolation from other systems. Open the drain valve to drain the internal medium and confirm that the pressure returns to zero. Remove the original inlet and outlet flanges of the heat exchanger and install a temporary flange with a bursting disc interface. After the preparations are completed, install the bursting disc and select the thickness of the highland barley paper according to the purge pressure. For example, 0.4mm can withstand a bursting pressure of about 0.8MPa. During installation, clean the flange sealing surface to ensure that there are no burrs. Cut the highland barley paper into flange size and place it in the center. Apply high-temperature sealant, tighten the bolts evenly, and tighten them diagonally to avoid bias. Then connect the gas source system and connect the air compressor or nitrogen bottle to the inlet flange of the heat exchanger with a rubber hose. Install a pressure gauge on the inlet pipeline and calibrate the range. Install a safety valve at the outlet of the gas source and set the pressure to 1.1 times the purge pressure. During blasting and purging, perform low-pressure pre-purging first. Open the gas source and slowly pressurize it to 0.2MPa, maintain it for 10 minutes, loosen the impurities initially, and observe whether there are obvious foreign objects discharged from the outlet. Then perform high-pressure blasting and purge, gradually increase the pressure to the design pressure, such as 0.8MPa, until the highland barley paper bursting piece breaks. At the moment of blasting, the airflow rushes out at high speed, carrying the impurities out, and achieving blasting and purge.

[0218] After step 205, the method further includes: Step 206: Perform cleanliness inspection on the heat exchanger 8, which specifically includes: using an endoscope to extend into each heat exchange channel of the heat exchanger 8 for inspection.

[0219] In this step, an endoscope is used to extend into each heat exchange channel of the heat exchanger 8 for inspection, and whether there are impurities, foreign matter, etc. in the heat exchange channel can be directly observed. If there are impurities, the heat exchange channel may be blocked in a low temperature environment, affecting the flow of fluids and even damaging the equipment. Through cleanliness inspection, impurities can be discovered and cleaned in time, which can effectively avoid these problems and ensure the safe and stable operation of the equipment.

[0220] If the cleanliness test meets the requirements, step 207 is performed: flow heat transfer performance test. Specifically, it includes: Step 2071: Measure the cold side fluid pressure drop of the heat exchanger 8.

[0221] The cold side fluid pressure drop is an important indicator for measuring the performance of the heat exchanger 8. In this step, the resistance of the superfluid helium flowing in the heat exchanger 8 is evaluated by measuring the cold side fluid pressure drop.

[0222] Before measurement, prepare a stable cold fluid source, such as a common 2K negative pressure heat exchanger test device, to ensure that it can provide a cold fluid with a superfluid helium temperature zone and a stable flow rate. Install a high-precision pressure sensor on the cold fluid inlet and outlet pipes of the heat exchanger 8 to measure the pressure difference before and after the cold side fluid enters the heat exchanger 8. At the same time, install a flow measurement device, such as a turbine flowmeter, on the cold side inlet and hot side inlet pipes to analyze the cold side pressure drop at different flow rates. Start the cold fluid source and allow the cold fluid to flow stably in the pipe and heat exchanger 8 for a period of time so that the system reaches a thermally stable state to avoid the measurement accuracy being affected by temperature fluctuations. According to the design parameters of the heat exchanger 8 and the actual operating conditions, adjust the cold fluid flow rate to the design conditions to keep the flow rate stable. After the system is stable, read and record the readings measured by the cold side inlet and cold side outlet pressure sensors and the pressure value measured by the outlet pressure sensor. The cold side fluid pressure drop value is the difference between the pressure value measured by the inlet pressure sensor and the pressure value measured by the outlet pressure sensor.

[0223] Step 2072: Perform a heat exchange efficiency test on the heat exchanger 8.

[0224] In this step, the heat exchange amount is obtained by measuring the relevant parameters of the cold side fluid and the hot side fluid using a heat calculation formula, and then the efficiency of the heat exchanger 8 is calculated.

[0225] Specifically, high-precision temperature sensors are installed on the cold fluid and hot fluid inlet and outlet pipes of the heat exchanger 8 to measure the inlet and outlet temperatures of the cold and hot fluids in real time. At the same time, a flow measurement device, such as a mass flow meter, is installed on the pipe to accurately measure the mass flow of the cold and hot fluids. According to the principles of thermodynamics, the heat exchange of the cold fluid and the hot fluid is calculated respectively. According to the design parameters of the heat exchanger 8, the maximum possible heat exchange is calculated, and the heat exchange efficiency of the heat exchanger 8 is calculated based on the actual heat exchange of the heat exchanger 8 and the maximum possible heat exchange.

[0226] Specifically, according to the law of conservation of energy, the heat exchange amounts of the cold and hot fluids should be equal.

[0227] The calculation formula for the heat transfer on the cold side is:

[0228] In the formula, , : Cold fluid inlet / outlet temperature (measured by high-precision temperature sensor); : Mass flow rate of cold fluid (measured by turbine flowmeter or mass flowmeter); : Constant-pressure specific heat capacity of cold fluid (known physical parameters); The calculation formula for the cold side pressure drop is:

[0229] is the cold fluid inlet pressure, is the outlet pressure of the cold fluid, and Can be measured by a pressure sensor.

[0230] The calculation formula for the heat transfer on the hot side is:

[0231] In the formula, , : Thermal fluid inlet / outlet temperature (measured by high-precision temperature sensor); : Thermal fluid mass flow rate (measured by mass flow meter); : Constant pressure specific heat capacity of thermal fluid (known physical parameters); Determine the minimum heat capacity ratio, the formula is:

[0232] In the formula, is the minimum heat capacity rate; : Mass flow rate of cold fluid (measured by turbine flowmeter or mass flowmeter); : Constant-pressure specific heat capacity of cold fluid (known physical parameters); : Thermal fluid mass flow rate (measured by mass flow meter); : Specific heat capacity of thermal fluid at constant pressure (known physical parameters).

[0233] Determine the maximum heat capacity rate using the formula:

[0234] In the formula, is the maximum heat capacity rate; : Mass flow rate of cold fluid (measured by turbine flowmeter or mass flowmeter); : Constant-pressure specific heat capacity of cold fluid (known physical parameters); : Thermal fluid mass flow rate (measured by mass flow meter); : Specific heat capacity of thermal fluid at constant pressure (known physical parameters).

[0235] The maximum heat transfer formula is:

[0236] Heat transfer efficiency Defined as the ratio of actual heat transfer to the maximum possible heat transfer, based on the number of heat transfer units (NTU) method, assuming an overall heat transfer coefficient Cold side pressure drop P c Related: Heat transfer coefficient correlation: ,in

[0237] The NTU expression is:

[0238] Assumptions ,and is a constant, incorporated into the coefficient middle.

[0239] When the heat exchanger is a countercurrent heat exchanger, and Ratio Satisfy the formula:

[0240] The efficiency formula is:

[0241] Specifically, the formula is:

[0242] in, In order to fit the constant, factors such as heat transfer area and fluid properties are considered.

[0243] In some possible embodiments =0.023, then the formula is:

[0244] When the flow heat transfer performance test meets the requirements, proceed to step 208: cleaning the inner and outer surfaces of the heat exchanger 8.

[0245] In this step, the cleanliness of the heat exchanger 8 is further improved by cleaning the inner and outer surfaces of the heat exchanger 8 again.

[0246] Step 209: Welding the nameplate. After welding the nameplate, the processing of the 2K negative pressure aluminum plate-fin heat exchanger is completed.

[0247] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0248] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A processing method for a 2K negative pressure aluminum plate-fin heat exchanger, characterized in that: include: Making the core; Making the head, the process of making the head includes one-piece forging the head; Connect the core and the head to form a heat exchanger; Conduct normal temperature testing on the heat exchanger, the temperature range of normal temperature testing is 20℃~30℃; Conduct low temperature testing on the heat exchanger, the temperature range of low temperature testing is below -150℃; The step of performing low temperature detection on the heat exchanger includes: Evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located; When the vacuum degree is less than the first preset pressure threshold, obtaining the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger; Perform cold shock treatment on the heat exchanger, and obtain the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device during the cooling process; When the temperature is cooled to a preset temperature threshold, the heat exchanger is tested for leaks using a cryogenic helium mass spectrometer.

2. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 1 is characterized in that: The step of evacuating each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located comprises: Each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located are evacuated by a mechanical pump; When the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the first intermediate pressure threshold, the Roots pump is turned on to evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located; When the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the second intermediate pressure threshold, the molecular pump is turned on to evacuate each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located, so that the vacuum degree of each heat exchange channel in the heat exchanger and the closed device where the heat exchanger is located is less than the first preset pressure threshold; When the vacuum degree is less than the first preset pressure threshold, obtaining the background leakage rate of the closed device and the background leakage rate of each heat exchange channel in the heat exchanger includes: The leak detection device is connected to the closed device, and the leak detection device is blocked from each heat exchange channel in the heat exchanger to obtain the background leakage rate of the closed device; The leak detection device is sequentially connected to each heat exchange channel in the heat exchanger, and the leak detection device is blocked from the sealing device to obtain the background leakage rate of each heat exchange channel in the heat exchanger; The heat exchange channel of the heat exchanger includes a cold fluid channel and a hot fluid channel; The heat exchanger is subjected to cold shock treatment, and the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device are obtained during the cooling process, including: Selecting a cold fluid channel with the largest volume as a first cooling channel, introducing liquid nitrogen into a first end of the first cooling channel and discharging it from a second end of the first cooling channel, so that the second end of the first cooling channel becomes a discharge port; Control the cooling rate of the first cooling channel to be less than or equal to 4°C / min; When the temperature difference between the first end of the first cooling channel and the second end of the first cooling channel is greater than a preset temperature difference threshold, and the temperature drop rate is less than a preset rate threshold, liquid nitrogen is introduced into the second end of the first cooling channel and discharged from the first end of the first cooling channel, so that the first end of the first cooling channel becomes a discharge port; After the temperature of the first cooling channel is cooled to a preset temperature threshold, and when no nitrogen is discharged from the exhaust port of the first cooling channel, the hot fluid channel with the largest volume is selected as the second cooling channel, and liquid nitrogen is introduced into the first end of the second cooling channel and discharged from the second end of the second cooling channel, so that the second end of the second cooling channel becomes the exhaust port; Control the cooling rate of the second cooling channel to be less than or equal to 4°C / min; When the temperature difference between the first end of the second cooling channel and the second end of the second cooling channel is greater than a preset temperature difference threshold, and the temperature drop rate is less than a preset rate threshold, liquid nitrogen is introduced into the second end of the second cooling channel and discharged from the first end of the second cooling channel, so that the first end of the second cooling channel becomes a discharge port; After the temperature of the second cooling channel is cooled to a preset temperature threshold, and when no nitrogen is discharged from the exhaust port of the second cooling channel, performing the low-temperature helium mass spectrometry leak detection; or performing cold shock treatment on the heat exchanger, and obtaining the background leakage rate and vacuum degree of each heat exchange channel in the heat exchanger and the background leakage rate and vacuum degree of the closed device during the cooling process, including: Place the heat exchanger in the cooling medium and perform immersion cold shock treatment on the heat exchanger.

3. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 2 is characterized in that: The method of performing low temperature helium mass spectrometry leak detection on the heat exchanger comprises: Selecting a heat exchange channel as a charging channel, charging helium into the charging channel, and leaving it to stand for a first period of time; Obtaining external leakage data of the charging channel and internal leakage data between adjacent heat exchange channels; Switch other heat exchange channels as charging channels in turn, and repeat the steps of filling helium into the charging channels and letting them stand for the first period of time to obtaining external leakage data of the charging channels and internal leakage data between adjacent heat exchange channels, until the external leakage data and internal leakage data of all heat exchange channels are obtained.

4. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 1 is characterized in that: The core manufacturing method comprises: Processing fins, baffles and seals, wherein the fins, baffles and seals are accessories of the core; Cleaning accessories; Assembling the core; Welding the core, wherein the core is welded by a vacuum brazing process; Check the geometric dimensions of the core; When the geometric dimensions of the core meet the requirements, water is injected into the core to detect leaks; The method for making the head includes: One-piece forged head; Clean the head; Machining steel and aluminum joints; Cleaning steel and aluminum joints; Welding steel-aluminum joints to the headers; Check the geometric dimensions of the whole formed by the head and the steel-aluminum joint; When the overall geometric dimensions of the head and the steel-aluminum joint meet the requirements, perform X-ray inspection on the butt weld; When the core body water injection leak detection and X-ray detection of the butt weld meet the requirements, the core body is connected to the head to make a heat exchanger; The core body and the head are connected to form a heat exchanger, comprising: Weld the head to the core.

5. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 1 is characterized in that: The step of performing normal temperature detection on the heat exchanger comprises: Penetrant testing of fillet welds; When the fillet weld meets the requirements, the geometric dimensions of the heat exchanger are inspected; When the geometric dimensions of the heat exchanger meet the requirements, the heat exchanger is subjected to overall immersion leak detection.

6. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 5 is characterized in that: The step of performing normal temperature detection on the heat exchanger comprises: When the overall immersion leak detection meets the requirements, perform pressure test on the heat exchanger; The stress test includes: Introduce pressure test gas into the heat exchange channel of the heat exchanger, increase the pressure to 10% of the specified test pressure, maintain it for the second time, and check all welds and joints for air leakage; In the absence of leakage, increase the pressure to 50% of the specified test pressure and detect air leakage at all welds and joints; In the case of no leakage, increase the pressure step by step to 10% of the specified test pressure, and check all welds and joints for leaks, until the pressure reaches the test pressure. Maintain it for the third time, and check all welds and joints for leaks.

7. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 1 is characterized in that: The step of performing normal temperature detection on the heat exchanger comprises: Conduct air tightness test on heat exchanger; The airtightness test includes: Introduce airtightness test gas into the heat exchange channel of the heat exchanger, increase the pressure to 10% of the specified test pressure, maintain it for the fourth time, and check all welds and joints for air leakage; In the absence of leakage, increase the pressure to 50% of the specified test pressure and detect air leakage at all welds and joints; In the absence of leakage, increase the pressure step by step by 10% of the specified test pressure and maintain it for the fifth time, and check all welds and joints for air leakage until the pressure reaches the test pressure.

8. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 6 is characterized in that: The step of performing normal temperature detection on the heat exchanger comprises: When the pressure test meets the requirements, the heat exchanger is tested for leaks by helium mass spectrometry at room temperature; The room temperature helium mass spectrometer leak detection comprises: External leakage detection and internal leakage detection; The leakage detection comprises: A cover chamber is formed by a polyethylene plastic bag, a heat exchanger is placed in the cover chamber, and the air in the cover chamber is exhausted; Helium is introduced into the chamber to an atmospheric pressure; When the volume of the mask chamber is greater than the preset volume, standing for a sixth period of time; Sequentially evacuate each heat exchange channel of the heat exchanger to a pressure lower than a second preset pressure threshold, and detect leakage rate data; The internal leakage detection comprises: Select a heat exchange channel in the heat exchanger as the channel to be tested; Introduce helium gas to one atmosphere pressure into the heat exchange channel adjacent to the channel under test; The channel under test is evacuated to a pressure lower than a third preset pressure threshold, and the pressure is maintained for a seventh time period; Detect the leak rate data of the measured channel.

9. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 1, characterized in that: After the low temperature detection of the heat exchanger, the method further includes: Explosion and purge the heat exchanger; The blasting and purging of the heat exchanger comprises: Step 1: Select a heat exchange channel for blasting and purging; The second step: using blasting materials to block the outlet of the selected heat exchange channel; The third step: injecting high-pressure nitrogen through the inlet of the selected heat exchange channel; Step 4: performing high-pressure blasting on the selected heat exchange channel, and detecting the particle concentration at the outlet of the selected heat exchange channel after the blasting; Step 5: When the particle concentration at the outlet of the selected heat exchange channel is greater than the preset concentration value, repeat the blasting until the particle concentration at the outlet is less than or equal to the preset concentration value; Step 6: Use blasting materials to block the entrance of the selected heat exchange channel; Step 7: injecting high-pressure nitrogen through the outlet of the selected heat exchange channel; Step 8: Perform high-pressure blasting on the selected heat exchange channel, and detect the particle concentration at the entrance of the selected heat exchange channel after blasting; Step 9: When the particle concentration at the inlet of the selected heat exchange channel is greater than the preset concentration value, repeat the blasting until the particle concentration at the inlet is less than or equal to the preset concentration value; Step 10: sequentially switch other heat exchange channels for blasting and purging, and repeat the first step to the ninth step until all heat exchange channels have completed blasting and purging; After the heat exchanger is blasted and purged, the method further comprises: Conduct cleanliness test on heat exchanger; The cleanliness detection of the heat exchanger comprises: Use an endoscope to reach into each heat exchange channel of the heat exchanger for inspection.

10. The processing method of the 2K negative pressure aluminum plate-fin heat exchanger according to claim 9, characterized in that: The method further comprises: When the cleanliness test meets the requirements, the heat exchanger is tested for flow and heat transfer performance; When the flow and heat transfer performance test meets the requirements, clean the inner and outer surfaces of the heat exchanger; Welding nameplate; The flow heat transfer performance test of the heat exchanger includes: Measure the cold side fluid pressure drop of the heat exchanger; Perform efficiency tests on heat exchangers.

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