An in-situ observation device and method for subcooled flow boiling under ultra-high heat flux

Abstract

The application discloses a kind of superhigh heat flow under supercooled flow boiling in situ observation device and method, belong to the technical field of partial filter heat exchange structure optimization, the device includes electron gun system, vacuum system, optical observation system and water circulation system, vacuum system is connected with electron gun system, optical observation system and water circulation system respectively.The device uses electron gun and water circulation system to simulate the real service condition of partial filter test piece in fusion reactor, by adjusting the cooling water condition inside partial filter test piece, adjusting optical observation light path, vacuumizing vacuum box and electron gun, high heat flow loading to partial filter and other steps, superhigh heat flow under supercooled flow boiling is observed in situ, and the optimization direction of heat exchange structure is determined.The application solves the problem that existing supercooled flow boiling in situ observation heat flux is low and difficult to simulate extreme conditions, realizes superhigh heat flow under supercooled flow boiling in situ observation, and provides basis for partial filter heat exchange structure optimization.

Description

Technical Field

[0001] This invention relates to the field of divertor heat exchange structure optimization technology, and in particular to an in-situ observation device and method for subcooled flow boiling under ultra-high heat flux. Background Technology

[0002] In the future Tokamak nuclear fusion reactor, the divertor needs to withstand high-energy particle bombardment and high heat flux density during stable operation to protect the rest of the reaction chamber from damage. However, the divertor is exposed to a high-temperature environment for extended periods, causing recrystallization of the tungsten material on its surface, resulting in surface cracking and interfacial debonding. To ensure the normal operation of the fusion device, the internal heat exchange structure of the divertor needs to be optimized, and it is necessary to develop in-situ observation techniques for supercooled flow boiling under ultra-high heat flux.

[0003] Currently, existing in-situ observation techniques for supercooled flow boiling mainly rely on induction heating to apply heat flux, using electromagnetic induction to generate current within the heated material and relying on the energy of eddy currents to achieve heating. However, this method has significant drawbacks and limitations. First, the heat flux density provided by induction heating is relatively low, generally below 2 MW / m², which is significantly different from the actual service conditions of divertors (10–20 MW / m²). Furthermore, induction heating requires a long time, making it difficult to simulate some rapidly heating scenarios, such as the extreme condition of plasma disruption. Therefore, to better understand the heat transfer mechanism of supercooled flow boiling and optimize the heat transfer structure of divertors, it is necessary to develop a supercooled flow boiling observation technique that simulates the actual service conditions of divertors. Summary of the Invention

[0004] The purpose of this invention is to provide an in-situ observation device and method for supercooled flow boiling under ultra-high heat flux, which can solve the problem that the existing in-situ observation of supercooled flow boiling has low heat flux density and is difficult to simulate the real service conditions of divertors. It enables in-situ observation of supercooled flow boiling of divertors under ultra-high heat flux, and lays the foundation for optimizing the heat exchange structure of divertors and improving the safety of nuclear fusion reaction devices.

[0005] To achieve the above objectives, the present invention provides an in-situ observation device for supercooled flow boiling under ultra-high heat flux, comprising a lead room and a water circulation system. The lead room is equipped with an electron gun system, a vacuum system and an optical observation system, and the vacuum system is connected to the electron gun system, the optical observation system and the water circulation system respectively.

[0006] Preferably, the vacuum system includes a vacuum chamber with an observation window on the front and a clamping platform inside the vacuum chamber, on which a divertor specimen is clamped and fixed.

[0007] Preferably, the vacuum chamber is sequentially connected to a vacuum chamber molecular pump and a vacuum chamber mechanical pump.

[0008] Preferably, the clamping platform includes a horizontal platform surface, a pulley is provided at the bottom of the horizontal platform surface, and a clamping arm is provided on the horizontal platform surface.

[0009] Preferably, the electron gun system includes an electron gun disposed outside the vacuum chamber and facing the divertor specimen, and an electron gun molecular pump and an electron gun mechanical pump are connected in sequence to the electron gun.

[0010] Preferably, the optical observation system includes a spotlight source, a right-angle mirror, a telephoto lens, and a camera. The spotlight source illuminates the right-angle mirror located at the bottom of the divertor specimen through the observation window. The right-angle mirror reflects the light to the heat exchange surface of the divertor specimen. The reflected light from the heat exchange surface returns through the right-angle mirror and is then transmitted to the camera via the telephoto lens.

[0011] Preferably, the camera is connected to a data acquisition system.

[0012] Preferably, the water circulation system includes a heat exchanger, and the cold end of the heat exchanger is circulatedly connected to an oil pump and an oil tank;

[0013] An inlet temperature sensor and an inlet pressure sensor are sequentially installed between the hot end outlet of the heat exchanger and the inlet of the divertor specimen. An outlet pressure sensor, an outlet temperature sensor, a pressure booster, a vortex flow meter, a magnetic pump, and a safety valve are sequentially installed between the outlet of the divertor specimen and the hot end inlet of the heat exchanger.

[0014] This invention also provides an in-situ observation method for supercooled flow boiling under ultra-high heat flux, comprising the following steps:

[0015] S1. Assemble the designed divertor specimen and cure it.

[0016] S2. Fix the divertor specimen on the clamping platform and adjust the position of the divertor specimen so that it is located within the scanning area of ​​the electron gun.

[0017] S3. Start the water circulation system to fill, pressurize, and check for leaks;

[0018] S4. Adjust the optical path to ensure that the camera's field of view clearly and completely captures the area to be observed;

[0019] S5. Start the heat exchanger, adjust the internal cooling water temperature of the divertor specimen to the given value, then start the magnetic pump, adjust the internal cooling water flow rate of the divertor specimen to the given value, and finally use the pressurizer to adjust the cooling water pressure to the given value.

[0020] S6. Close the vacuum chamber door, start the vacuum chamber mechanical pump to evacuate the vacuum chamber. When the internal pressure of the vacuum chamber drops to 20Pa, start the vacuum chamber molecular pump. When the internal pressure of the vacuum chamber drops below 0.1Pa, the vacuum evacuation is complete.

[0021] S7. Start the electron gun mechanical pump to evacuate the electron gun. When the instrument shows that the internal pressure is lower than 7Pa, start the electron gun molecular pump. When the internal pressure of the electron gun is lower than 0.001Pa, the evacuation of the electron gun is completed.

[0022] S8. Open the electron gun diaphragm valve to connect the electron gun to the vacuum chamber, adjust the scanning area of ​​the electron gun to match the size of the target area, and then adjust the electron gun point count and frequency to achieve uniform loading.

[0023] S9. Set the electron gun beam current to start loading from 10mA, and the camera starts acquiring images at the same time. Once the thermocouple temperature stabilizes, the heat transfer is considered to have reached a stable state, and loading and image acquisition are stopped.

[0024] S10. After applying 10mA of electron gun beam current, repeat step S9.

[0025] S11. Process the temperature data, obtain the boiling curve according to the heat transfer law, analyze it in conjunction with the image data, and analyze the merits of the heat exchange structure based on bubble generation and motion behavior to determine the optimization direction.

[0026] Preferably, an electron gun is used for heat loading, with a maximum heat flux of 30 MW / m2.

[0027] Therefore, the beneficial technical effects of the above-mentioned in-situ observation device and method for supercooled flow boiling under ultra-high heat flux are as follows:

[0028] (1) It solves the problem that the heat flux is insufficient to simulate the real service conditions of the divertor in traditional methods: Traditional heat loading methods usually have the problems of slow loading speed and low loading heat flux, making it difficult to simulate the real service conditions of the divertor. However, the electron gun heating system used in this invention can effectively avoid these problems and is closer to the real application scenario.

[0029] (2) Providing different camera options for observation needs: The optical path designed in this invention is compatible with different cameras and can be adjusted according to observation needs. For example, if the focus is on the distribution of bubbles under steady-state heat transfer, a high-resolution camera can be used for long-term shooting; if the focus is on the movement of bubbles, a high-speed camera can be used to continuously track the position of bubbles. This not only helps researchers to understand the subcooled flow boiling heat transfer process of the divertor more deeply, but also provides strong data support for the design and optimization of the divertor.

[0030] (3) Coupling of temperature data and in-situ observation of subcooled flow boiling: Traditional divertor heat transfer tests often only provide partial temperature data, which has limited guiding significance for the optimization of divertor heat transfer structure. However, this invention, by coupling temperature data and in-situ observation of subcooled flow boiling, can more effectively evaluate the heat transfer performance of the divertor and further clarify the direction of optimization.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of an embodiment of the in-situ observation device for supercooled flow boiling under ultra-high heat flux according to the present invention.

[0033] Figure 2 This is a schematic diagram of the optical path of the optical observation system of an embodiment of an in-situ observation device for supercooled flow boiling under ultra-high heat flux according to the present invention.

[0034] Figure 3 This is a diagram showing the boiling curve and heat transfer coefficient curve of an embodiment of the subcooled flow boiling in-situ observation device under ultra-high heat flux according to the present invention.

[0035] Figure 4 These are observation images captured by the camera.

[0036] Figure Labels

[0037] 1. Vacuum chamber; 2. Electron gun; 3. Electron gun mechanical pump; 4. Electron gun molecular pump; 5. Vacuum chamber molecular pump; 6. Vacuum chamber mechanical pump; 7. Clamping platform; 8. Inlet pressure sensor; 9. Inlet temperature sensor; 10. Outlet pressure sensor; 11. Outlet temperature sensor; 12. Vortex flow meter; 13. Magnetic pump; 14. Safety valve; 15. Heat exchanger; 16. Oil pump; 17. Oil tank; 18. Observation window; 19. Spotlight source; 20. Camera; 21. Data acquisition system; 22. Lead room; 23. Divertor specimen; 24. Pressure booster; 25. Right-angle reflector; 26. Telephoto lens. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0040] Example 1

[0041] like Figure 1 As shown, the present invention provides an in-situ observation device for supercooled flow boiling under ultra-high heat flux, including a lead room 22 and a water circulation system. The lead room 22 is equipped with an electron gun system, a vacuum system and an optical observation system. The vacuum system works in coordination with the electron gun system, the optical observation system and the water circulation system through precise connections.

[0042] The vacuum system includes a vacuum chamber 1 with two observation windows 18 on the front, providing necessary access for optical observation. Inside the vacuum chamber 1 is a clamping platform 7, which includes a horizontal platform surface. The bottom of the horizontal platform surface is equipped with pulleys for easy movement and adjustment. Two clamping arms are mounted on the horizontal platform surface, and a divertor specimen 23 is placed on it. The horizontal platform surface and the two clamping arms stably support the divertor specimen 23, ensuring stability and accuracy during the testing process.

[0043] Vacuum chamber 1 is sequentially connected to a vacuum chamber molecular pump 5 and a vacuum chamber mechanical pump 6, enabling efficient vacuuming to ensure extremely low atmospheric pressure conditions in the testing environment. The electron gun system includes an electron gun 2 located outside the vacuum chamber 1 and facing the divertor specimen 23. Electron gun 2 is sequentially connected to an electron gun molecular pump 4 and an electron gun mechanical pump 3, enabling vacuuming of the electron gun 2.

[0044] The optical observation system is the core component of the entire device, such as Figure 2As shown, the system includes a spotlight source 19, a right-angle reflector 25, a telephoto lens 26, and a camera 20. The spotlight source 19 illuminates the right-angle reflector 25 located at the bottom of the divertor specimen 23 through the observation window 18. The right-angle reflector 25 precisely reflects the light onto the heat exchange surface of the divertor specimen 23. The reflected light from the heat exchange surface then returns through the right-angle reflector 25 and is transmitted to the camera 20 via the telephoto lens 26. The camera 20 is a high-pixel industrial camera, characterized by high speed and high resolution, which is beneficial for the precise capture of reflected light. A data acquisition system 21 is also connected to the camera 20 to achieve real-time data transmission and observation.

[0045] The water circulation system is responsible for regulating the cooling water flow inside the divertor specimen 23 to ensure the hydraulic conditions during the test. This includes the heat exchanger 15. In this embodiment, the heat exchanger 15 is an oil-water heat exchanger. The cold end of the heat exchanger 15 is circulatedly connected to the oil pump 16 and the oil tank 17 for heat exchange with the cooling water at the hot end. During the test, tap water is used to cool the heat exchange oil in the oil tank 17.

[0046] An inlet temperature sensor 9 and an inlet pressure sensor 8 (for acquiring inlet water temperature and pressure data) are sequentially installed between the hot end outlet of the heat exchanger 15 and the inlet of the divertor specimen 23. An outlet pressure sensor 10 and an outlet temperature sensor 11 (for acquiring outlet water temperature and pressure data), a pressure booster 24 (for adjusting cooling water pressure), a vortex flow meter 12 (for measuring cooling water flow rate), a magnetic pump 13 (for driving the cooling water circulation in the loop), and a safety valve 14 (for releasing pressure when the loop water pressure is too high) are sequentially installed between the outlet of the divertor specimen 23 and the hot end inlet of the heat exchanger 15.

[0047] The method for conducting observations using the above-mentioned observation device includes the following steps:

[0048] S1. Assemble the specially designed divertor specimen 23 and cure it.

[0049] S2. Fix the divertor specimen 23 on the clamping platform 7 and adjust the position of the divertor specimen 23 so that it is located within the scanning area of ​​the electron gun 2.

[0050] S3. Start the water circulation system, fill it with water, pressurize it, and check for leaks to ensure that the water circulation system can operate normally.

[0051] S4. Adjust the optical path to ensure that the camera 20 can capture the area to be observed clearly and completely.

[0052] S5. Start the heat exchanger 15, adjust the internal cooling water temperature of the divertor specimen 23 to the given value, then start the magnetic pump 13, adjust the internal cooling water flow rate of the divertor specimen 23 to the given value, and finally use the pressure booster 24 to adjust the cooling water pressure to the given value.

[0053] S6. Close the door of vacuum chamber 1, start the vacuum chamber mechanical pump 6 to evacuate the vacuum chamber. When the internal pressure of vacuum chamber 1 drops to 20Pa, start the vacuum chamber molecular pump 5. When the internal pressure of vacuum chamber 1 is lower than 0.1Pa, the evacuation of vacuum chamber 1 is completed.

[0054] S7. Start the electron gun mechanical pump 3 to evacuate the electron gun 2. When the instrument shows that the internal pressure is lower than 7Pa, start the electron gun molecular pump 4. When the internal pressure of the electron gun 2 is lower than 0.001Pa, the evacuation of the electron gun 2 is completed.

[0055] S8. Open the diaphragm valve of electron gun 2 to connect electron gun 2 to vacuum chamber 1. Adjust the scanning area of ​​electron gun 2 to match the size of the target area. Then, adjust the number of electron gun points and frequency to achieve uniform loading.

[0056] S9. Set the electron gun beam current to 10mA and simultaneously start image acquisition at camera 20. Once the thermocouple temperature stabilizes, the heat transfer is considered to have reached a steady state, at which point loading and image acquisition cease. When using the electron gun for heat loading, the maximum heat flux reaches 30 MW / m².

[0057] S10. After applying 10mA of electron gun beam current, repeat step S9.

[0058] S11. Process the temperature data, obtain the boiling curve according to the heat transfer law, analyze it in conjunction with the image data, and analyze the merits of the heat exchange structure based on bubble generation and motion behavior to determine the optimization direction.

[0059] To link the visualization with heat transfer, the heat transfer of the divertor specimen 23 needs to be analyzed. This is evaluated by drilling thermocouple holes, with a pair of thermocouple holes drilled vertically between the heat flow loading surface and the heat transfer surface. The depth of the thermocouple holes is half the width of the specimen. According to Fourier's one-dimensional heat transfer law, the actual internal heat flow can be calculated from the temperature measured by the thermocouples, using the following formula:

[0060] ;

[0061] in, T 1. T 2 represents the temperatures measured by the upper and lower thermocouples, respectively. This refers to the thermocouple aperture spacing. For the thermal conductivity of the material, This represents the actual internal heat flow. Furthermore, by considering the inlet and outlet water temperatures of the water circulation system, the heat transfer coefficient of the specimen can be calculated using the following formula:

[0062] ;

[0063] in, The calculated heat transfer coefficient of the specimen, , These are the wall surface temperature and the mainstream cooling water temperature of the test section, respectively, and their calculation formulas are as follows:

[0064] ;

[0065] ;

[0066] in, This is the distance from the lower thermocouple to the heat exchange surface. T in , T out These are the inlet and outlet water temperatures, respectively.

[0067] In this embodiment, a rectangular cross-section specimen is used as an example. The thermal conductivity of chromium-zirconium-copper is 320 kW / (m·℃). The experimental temperature, calculated heat flow, and calculated heat transfer coefficient are shown in Table 1.

[0068] ;

[0069] The boiling curves and heat transfer coefficient curves obtained based on the data in Table 1 are as follows: Figure 3 As shown, the observation image taken using a high-resolution camera 20 at the boiling initiation point of the supercooled flow (heat flux approximately 4.73 MW / m2) is as follows. Figure 4 As shown, a small number of bubbles were found distributed in the upper left part, indicating that the observed results of the boiling point are consistent with the experimental data.

[0070] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0071] Therefore, the present invention adopts the above-mentioned in-situ observation device and method for supercooled flow boiling under ultra-high heat flux, which solves the problems of low power, slow response and difficulty in simulating the real service conditions of divertor in existing heating equipment, and realizes in-situ observation of supercooled flow boiling under ultra-high heat flux. Through this technology, experimental observation basis can be provided for the optimization of divertor structure, and the safety and efficiency of nuclear fusion reaction device can be improved.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An in-situ observation device for supercooled flow boiling under ultra-high heat flux, characterized in that: It includes a lead room and a water circulation system. The lead room is equipped with an electron gun system, a vacuum system and an optical observation system. The vacuum system is connected to the electron gun system, the optical observation system and the water circulation system respectively. The vacuum system includes a vacuum chamber with an observation window on the front and a clamping platform inside the vacuum chamber, on which a divertor specimen is clamped and fixed. The optical observation system includes a spotlight source, a right-angle mirror, a telephoto lens, and a camera. The spotlight source illuminates the right-angle mirror located at the bottom of the divertor specimen through the observation window. The right-angle mirror reflects the light to the heat exchange surface of the divertor specimen. The reflected light from the heat exchange surface returns through the right-angle mirror and is then transmitted to the camera via the telephoto lens.

2. The in-situ observation device for supercooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The vacuum chamber is sequentially connected to a vacuum chamber molecular pump and a vacuum chamber mechanical pump.

3. The in-situ observation device for supercooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The clamping platform includes a horizontal platform surface, a pulley is provided at the bottom of the horizontal platform surface, and a clamping arm is provided on the horizontal platform surface.

4. The in-situ observation device for supercooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The electron gun system includes an electron gun located outside the vacuum chamber and facing the divertor specimen, and an electron gun molecular pump and an electron gun mechanical pump are connected in sequence to the electron gun.

5. The in-situ observation device for supercooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The camera is connected to a data acquisition system.

6. The in-situ observation device for supercooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The water circulation system includes a heat exchanger, and the cold end of the heat exchanger is circulatedly connected to an oil pump and an oil tank. An inlet temperature sensor and an inlet pressure sensor are sequentially installed between the hot end outlet of the heat exchanger and the inlet of the divertor specimen. An outlet pressure sensor, an outlet temperature sensor, a pressure booster, a vortex flow meter, a magnetic pump, and a safety valve are sequentially installed between the outlet of the divertor specimen and the hot end inlet of the heat exchanger.

7. A method for in-situ observation of subcooled flow boiling under ultra-high heat flux, characterized in that: The in-situ observation device for supercooled flow boiling under ultra-high heat flux as described in any one of claims 1-6 includes the following steps: S1. Assemble the designed divertor specimen and cure it. S2. Fix the divertor specimen on the clamping platform and adjust the position of the divertor specimen so that it is located within the scanning area of ​​the electron gun. S3. Start the water circulation system to fill, pressurize, and check for leaks; S4. Adjust the optical path to ensure that the camera's field of view clearly and completely captures the area to be observed; S5. Start the heat exchanger, adjust the internal cooling water temperature of the divertor specimen to the given value, then start the magnetic pump, adjust the internal cooling water flow rate of the divertor specimen to the given value, and finally use the pressurizer to adjust the cooling water pressure to the given value. S6. Close the vacuum chamber door, start the vacuum chamber mechanical pump to evacuate the vacuum chamber. When the internal pressure of the vacuum chamber drops to 20Pa, start the vacuum chamber molecular pump. When the internal pressure of the vacuum chamber drops below 0.1Pa, the vacuum evacuation is complete. S7. Start the electron gun mechanical pump to evacuate the electron gun. When the instrument shows that the internal pressure is lower than 7Pa, start the electron gun molecular pump. When the internal pressure of the electron gun is lower than 0.001Pa, the evacuation of the electron gun is completed. S8. Open the electron gun diaphragm valve to connect the electron gun to the vacuum chamber, adjust the scanning area of ​​the electron gun to match the size of the target area, and then adjust the electron gun point count and frequency to achieve uniform loading. S9. Set the electron gun beam current to start loading from 10mA, and the camera starts acquiring images at the same time. Once the thermocouple temperature stabilizes, the heat transfer is considered to have reached a stable state, and loading and image acquisition are stopped. S10. After applying 10mA of electron gun beam current, repeat step S9. S11. Process the temperature data, obtain the boiling curve according to the heat transfer law, analyze it in conjunction with the image data, and analyze the merits of the heat exchange structure based on bubble generation and motion behavior to determine the optimization direction.

8. The method for in-situ observation of subcooled flow boiling under ultra-high heat flux according to claim 7, characterized in that: Heat loading is achieved using an electron gun, with a maximum heat flux of 30 MW / m2.

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