Supercooled flow boiling in-situ observation device and method under ultrahigh heat flow

Abstract

The invention discloses a supercooled flow boiling in-situ observation device and method under ultrahigh heat flow, and belongs to the technical field of divertor heat exchange structure optimization, the device comprises an electron gun system, a vacuum system, an optical observation system and a water circulation system, and the vacuum system is connected with the electron gun system, the optical observation system and the water circulation system. According to the device, an electronic gun and a water circulation system are used for simulating the real service condition of a divertor test piece in a fusion reactor, and the divertor test piece can be tested by adjusting the cooling water condition in the divertor test piece, adjusting an optical observation light path, vacuumizing a vacuum box and the electronic gun, carrying out high heat flow loading on the divertor and the like. In-situ observation is carried out on supercooled flow boiling under ultrahigh heat flow, and the optimization direction of a heat exchange structure is determined. According to the invention, the problems of low heat flux density and difficulty in simulation of extreme conditions in existing supercooled flow boiling in-situ observation are solved, supercooled flow boiling in-situ observation under ultrahigh heat flow is realized, and a basis is provided for optimization of a divertor heat exchange structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of divertor heat transfer structure optimization, in particular to a super-high heat flow subcooled flow boiling in-situ observation device and method. BACKGROUND

[0002] In the future Tokamak nuclear fusion reactor, the divertor needs to withstand high-energy particle bombardment and high heat flux density to protect the rest of the reaction chamber from damage when the device is running smoothly. However, the surface tungsten material of the divertor will recrystallize in a high-temperature environment, causing surface cracking and interface debonding. In order to ensure the normal operation of the fusion device during operation, it is necessary to optimize the design of the heat transfer structure inside the divertor, and it is necessary to develop a subcooled flow boiling in-situ observation technology under super-high heat flow.

[0003] At present, the existing subcooled flow boiling in-situ observation technology mainly uses induction heating to load heat flow, uses electromagnetic induction to generate current inside the heated material, and relies on the energy of eddy current to achieve heating effect. However, this method has significant defects and deficiencies. First, the heat flux density provided by induction heating is low, generally less than 2MW / m2, which is significantly different from the real service conditions of the divertor (10-20MW / m2). In addition, induction heating takes a long time and is difficult to simulate some rapid heating scenarios, such as extreme conditions of plasma disruption. Therefore, in order to better understand the subcooled flow boiling heat transfer mechanism and optimize the heat transfer structure of the divertor, it is necessary to develop a subcooled flow boiling observation technology that simulates the real service conditions of the divertor. SUMMARY

[0004] The purpose of the present application is to provide a subcooled flow boiling in-situ observation device and method under super-high heat flow, which can solve the problem of low heat flux density in existing subcooled flow boiling in-situ observation, and simulate the real service conditions of the divertor. The purpose is to realize the in-situ observation of the subcooled flow boiling of the divertor under super-high heat flow, and to establish a foundation for optimizing the heat transfer structure of the divertor and improving the safety of the nuclear fusion reactor.

[0005] To achieve the above purpose, the present application provides a subcooled flow boiling in-situ observation device under super-high heat flow, which comprises a lead house and a water circulation system, and the lead house is provided with an electron gun system, a vacuum system and an optical observation system. The vacuum system is connected with the electron gun system, the optical observation system and the water circulation system respectively.

[0006] Preferably, the vacuum system comprises a vacuum box, the front surface of the vacuum box is provided with an observation window, and a clamping platform is arranged in the vacuum box. The divertor test piece is clamped and fixed on the clamping platform.

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

[0008] Preferably, the clamping platform comprises a water platform, the bottom of the water platform is provided with a pulley, and the water platform is provided with a clamping arm.

[0009] Preferably, the electron gun system comprises an electron gun arranged outside the vacuum box and facing the bias filter sample, and the electron gun is sequentially connected with an electron gun molecular pump and an electron gun mechanical pump.

[0010] Preferably, the optical observation system comprises a spotlight light source, a right-angle reflector, a long-focus lens and a camera, the spotlight light source irradiates the right-angle reflector located at the bottom of the bias filter sample through the observation window, the right-angle reflector reflects light to the heat exchange surface of the bias filter sample, the reflected light of the heat exchange surface returns to the original path through the right-angle reflector, and is conducted to the camera through the long-focus lens.

[0011] Preferably, the camera is connected with a collection system.

[0012] Preferably, the water circulation system comprises a heat exchanger, and the cold end of the heat exchanger is connected with an oil pump and an oil tank in circulation; The outlet of the hot end of the heat exchanger and the inlet of the bias filter sample are sequentially provided with an inlet temperature sensor and an inlet pressure sensor, and the outlet of the bias filter sample and the hot end flow inlet of the heat exchanger are sequentially provided with an outlet pressure sensor, an outlet temperature sensor, a pressure booster, a vortex flowmeter, a magnetic pump and a safety valve.

[0013] The application also provides an in-situ observation method for subcooled flow boiling under super-high heat flow, comprising the following steps: S1, assembling and curing the designed bias filter sample; S2, fixing the bias filter sample on the clamping platform and adjusting the position of the bias filter sample to be located in the scanning area of the electron gun; S3, starting the water circulation system to charge water, pressurize and detect leakage; S4, adjusting the optical path to ensure that the camera field of view clearly and completely captures the picture of the observed area; S5, starting the heat exchanger, adjusting the water temperature of the cooling water in the bias filter sample to a given value, then starting the magnetic pump, adjusting the flow rate of the cooling water in the bias filter sample to a given value, and finally using the pressure booster to adjust the cooling water pressure to a given value; S6, closing the cabin door of the vacuum box, starting the mechanical pump of the vacuum box to perform vacuumization, when the internal air pressure of the vacuum box is reduced to 20 Pa, starting the molecular pump of the vacuum box, and when the internal air pressure of the vacuum box is lower than 0.1 Pa, completing the vacuumization work of the vacuum box; S7, start the electron gun mechanical pump to vacuumize the inside of the electron gun, open the electron gun molecular pump when the internal pressure of the electron gun is lower than 7Pa, and complete the vacuumization of the electron gun when the internal pressure of the electron gun is lower than 0.001Pa; S8, open the electron gun isolation valve to connect the electron gun with the vacuum box, adjust the scanning area of the electron gun to be the size of the target area, and then realize uniform loading by adjusting the electron gun point number and frequency; S9, set the electron gun beam current to start loading from 10mA, and the camera starts collecting images, and after the thermocouple temperature stabilizes, it is considered that the heat transfer reaches a stable state, and the loading and image collection are stopped; S9 is repeated after the electron gun beam current is loaded to 10mA. S11, process the temperature data, obtain the boiling curve according to the heat transfer law, analyze the image data, and analyze the advantages and disadvantages of the heat exchange structure according to the bubble generation and motion behavior to determine the optimization direction.

[0014] Preferably, the electron gun is used for heat loading, and the maximum heat flow is 30MW / m2.

[0015] Therefore, the superheat flow boiling in-situ observation device and method under the above high heat flow have the following beneficial technical effects: (1) The problem that the heat flow in the traditional method is insufficient to simulate the real service condition of the divertor is solved: the traditional heat loading method usually has the problems of slow loading speed and low loading heat flow, and it is difficult to simulate the real service condition of the divertor. The electron gun heating system adopted by the present application can effectively avoid these problems and be closer to the real application scene.

[0016] (2) Different camera selection is provided according to the observation requirement: the light path designed in the present application is adapted to different cameras, which can be adjusted according to the observation requirement, such as focusing on the bubble distribution under the steady-state heat transfer state, and a high-pixel camera can be used for long-time shooting, or focusing on the motion of the bubble, and a high-speed camera can be used for continuous tracking of the bubble position. This not only helps researchers to better understand the subcooling flow boiling heat transfer process of the divertor, but also provides strong data support for the design and optimization of the divertor.

[0017] (3) Temperature data and subcooling flow boiling in-situ observation are coupled: the traditional divertor heat transfer test can only provide part of the temperature data, and the guiding significance for the optimization of the divertor heat exchange structure is limited. By coupling the temperature data and the subcooling flow boiling in-situ observation, the heat transfer performance of the divertor can be more effectively evaluated, and the optimization direction is further clarified.

[0018] The technical solutions of the present application will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of an embodiment of a super-high heat flow subcooled flow boiling in-situ observation device of the present application; Figure 2 is a light path schematic diagram of an optical observation system of an embodiment of a super-high heat flow subcooled flow boiling in-situ observation device of the present application; Figure 3 is a boiling curve and heat exchange coefficient curve diagram of an embodiment of a super-high heat flow subcooled flow boiling in-situ observation device of the present application; Figure 4 is an observation image collected by a camera.

[0020] REFERENCE NUMERALS 1, vacuum box; 2, electron gun; 3, electron gun mechanical pump; 4, electron gun molecular pump; 5, vacuum box molecular pump; 6, vacuum box mechanical pump; 7, clamping platform; 8, inlet pressure sensor; 9, inlet temperature sensor; 10, outlet pressure sensor; 11, outlet temperature sensor; 12, vortex flowmeter; 13, magnetic pump; 14, safety valve; 15, heat exchanger; 16, oil pump; 17, oil tank; 18, observation window; 19, spotlight source; 20, camera; 21, acquisition system; 22, lead house; 23, bias filter test piece; 24, pressurizer; 25, right-angle mirror; 26, long-focus lens. DETAILED DESCRIPTION

[0021] The technical solutions of the present application are further described below by means of the accompanying drawings and embodiments.

[0022] Unless otherwise defined, technical or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Unless otherwise defined, the terms "first", "second", and the like, used in the present application do not necessarily have any order or sequence, and are used to distinguish different components. The terms "comprise", "comprising", "include", "including", and the like, mean including but not limited to, and the like, and the terms "connected", "coupled", and the like, do not necessarily mean physically or mechanically connected, but can include electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like, are only used to indicate relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0023] Embodiment One As Figure 1As shown, the application provides a super-high heat flow undercooling flow boiling in-situ observation device, which comprises a lead house 22 and a water circulation system, the lead house 22 is provided with an electron gun system, a vacuum system and an optical observation system, the vacuum system cooperates with the electron gun system, the optical observation system and the water circulation system through precise connection.

[0024] The vacuum system comprises a vacuum box 1, the front of the vacuum box 1 is provided with two observation windows 18, which provides a necessary channel for optical observation. The vacuum box 1 is provided with a clamping platform 7 inside, the clamping platform 7 comprises a water platform surface, the bottom of the water platform surface is provided with a pulley to facilitate the movement and adjustment of the water platform surface, the water platform surface is provided with two clamping arms, and the water platform surface is provided with a deflector test piece 23, the deflector test piece 23 is stably carried by the water platform surface and the two clamping arms, and the stability and accuracy during the test are ensured.

[0025] The vacuum box 1 is sequentially connected with a vacuum box molecular pump 5 and a vacuum box mechanical pump 6, which can perform efficient vacuumizing work to ensure the extremely low pressure condition of the test environment. The electron gun system comprises an electron gun 2 arranged outside the vacuum box 1 and facing the deflector test piece 23, the electron gun 2 is sequentially connected with an electron gun molecular pump 4 and an electron gun mechanical pump 3, which can realize the vacuumizing work of the electron gun 2.

[0026] The optical observation system is the core part of the whole device, as shown in the figure, Figure 2 The optical observation system comprises a spotlight 19, a right-angle reflector 25, a long-focus lens 26 and a camera 20. The spotlight 19 irradiates the right-angle reflector 25 at the bottom of the deflector test piece 23 through the observation window 18, the right-angle reflector 25 accurately reflects the light to the heat exchange surface of the deflector test piece 23, the reflected light of the heat exchange surface returns to the right-angle reflector 25 by the original route, and is conducted to the camera 20 through the long-focus lens 26. The camera 20 adopts a high-pixel industrial camera, which has the characteristics of high speed and high resolution, and is conducive to accurate capture of reflected light. The camera 20 is also connected with a collection system 21 to realize real-time transmission and observation of data.

[0027] The water circulation system is responsible for adjusting the cooling water flow in the deflector test piece 23 to ensure the hydraulic conditions during the test, which comprises a heat exchanger 15, in this embodiment, the heat exchanger 15 adopts an oil-water heat exchanger, the cold end of the heat exchanger 15 is circularly connected with an oil pump 16 and an oil tank 17, which is used for heat exchange with the cooling water of the hot end, and tap water is used to cool the heat exchange oil in the oil tank 17 during the test.

[0028] The heat exchange 15 hot end flow outlet and the filter test piece 23 inlet are sequentially provided with an inlet temperature sensor 9 and an inlet pressure sensor 8 (for obtaining inlet water temperature and pressure data), the filter test piece 23 outlet and the heat exchange 15 hot end flow inlet are sequentially provided with an outlet pressure sensor 10 and an outlet temperature sensor 11 (for obtaining outlet water temperature and pressure data), a pressure regulator 24 (for adjusting cooling water pressure), a vortex flowmeter 12 (for measuring cooling water flow rate), a magnetic pump 13 (for driving the loop cooling water circulation), and a safety valve 14 (for pressure relief when the loop water pressure is too high).

[0029] The method for observing using the observation device described above comprises the following steps: S1, assemble and cure the specially designed filter test piece 23.

[0030] S2, fix the filter test piece 23 on the clamping platform 7, and adjust the position of the filter test piece 23 to be within the scanning area of the electron gun 2.

[0031] S3, start the water circulation system, and perform water filling, pressurization, and leak detection to ensure that the water circulation system can operate normally.

[0032] S4, adjust the optical path to ensure that the camera 20 can clearly and completely capture the picture of the area to be observed.

[0033] S5, start the heat exchanger 15, adjust the cooling water temperature in the filter test piece 23 to a given value, then start the magnetic pump 13, adjust the cooling water flow rate in the filter test piece 23 to a given value, and finally use the pressure regulator 24 to adjust the cooling water pressure to a given value.

[0034] S6, close the door of the vacuum box 1, start the vacuum box mechanical pump 6 to perform vacuum pumping, when the internal pressure of the vacuum box 1 is reduced to 20 Pa, start the vacuum box molecular pump 5, and when the internal pressure of the vacuum box 1 is lower than 0.1 Pa, complete the vacuum pumping of the vacuum box 1.

[0035] S7, start the electron gun mechanical pump 3 to perform vacuum pumping on the electron gun 2, when the internal pressure is lower than 7 Pa, start the electron gun molecular pump 4, and when the internal pressure of the electron gun 2 is lower than 0.001 Pa, complete the vacuum pumping of the electron gun 2.

[0036] S8, open the electron gun 2 valve to connect the electron gun 2 with the vacuum box 1, adjust the scanning area of the electron gun 2 to be the size of the target area, and then adjust the electron gun point number and frequency to achieve uniform loading.

[0037] S9, set the electron gun beam current from 10 mA loading, while the camera 20 starts to collect images, after the thermocouple temperature stabilizes, it is considered that the heat transfer reaches a steady state, stop loading, stop collecting images. When using the electron gun for thermal loading, the highest heat flow is 30 MW / m2.

[0038] S10, repeat step S9 after the electron gun beam current is loaded to 10 mA.

[0039] S11, process the temperature data, obtain the boiling curve according to the heat transfer law, and analyze the image data, and analyze the advantages and disadvantages of the heat exchange structure according to the bubble generation and motion behavior, and determine the optimization direction.

[0040] In order to associate the visual image with the heat transfer, the heat transfer of the deflector test piece 23 needs to be analyzed, and the heat transfer is evaluated by the thermocouple hole. A pair of thermocouple holes are punched vertically between the heat flow loading surface and the heat exchange surface, and the depth of the thermocouple hole is half the width of the test piece. According to the one-dimensional Fourier heat transfer law, the real heat flow inside can be calculated by the temperature measured by the thermocouple. The formula is: ; Among them, T 1, T 2 are the temperatures measured by the upper and lower thermocouples, is the distance between the thermocouple holes, is the thermal conductivity of the material, is the real heat flow inside. Further, combined with the inlet and outlet water temperatures of the water circulation system, the heat exchange coefficient of the test piece can be calculated, and the corresponding formula is: ; Among them, is the calculated heat exchange coefficient of the test piece, , are the wall temperature and the main stream cooling water temperature of the test section respectively, and the calculation formula is as follows: ; ; Among them, is the distance from the lower thermocouple to the heat exchange surface, T in , T out are the inlet and outlet water temperatures.

[0041] In this embodiment, taking a rectangular cross-section test piece as an example, the thermal conductivity of chromium-zirconium-copper is taken as 320 kW / (m·℃), and the temperature, calculated heat flow and calculated heat exchange coefficient obtained by experiment are shown in Table 1: ; The boiling curve and heat transfer coefficient curve obtained based on the data in Table 1 are shown in Figure 3 As shown in the observed image of the supercooled flow boiling starting point (heat flow about 4.73 MW / m2) using the high-pixel camera 20, Figure 4 It is found that a small amount of bubbles are distributed in the upper left part, indicating that the observation result of the boiling starting point is consistent with the experimental data.

[0042] It is worth noting that the contents not elaborated in the present application are all prior art and are well known to those skilled in the art.

[0043] Therefore, the present application adopts the above-mentioned super-high heat flow undercooling flow boiling in-situ observation device and method, solves the problems of low power, slow response and difficulty in simulating the real service conditions of the partial filter of the existing heating equipment, realizes the in-situ observation of the super-high heat flow undercooling flow boiling, and provides experimental observation basis for the optimization of the partial filter structure through the technology, and improves the safety and efficiency of the nuclear fusion reaction device.

[0044] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the technical solutions of the present application can still be modified or replaced by the equivalent, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. An in-situ observation device for subcooled flow boiling under ultra-high heat flux, characterized by: It includes a lead room and a water circulation system. The lead room is provided with an electron gun system, a vacuum system and an optical observation system. The vacuum system is connected with the electron gun system, the optical observation system and the water circulation system respectively.

2. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 1, characterized in that: The vacuum system comprises a vacuum box, an observation window is provided on the front of the vacuum box, a clamping platform is provided inside the vacuum box, and a divertor specimen is clamped and fixed on the clamping platform.

3. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 2, characterized in that: The vacuum box is connected in sequence with a vacuum box molecular pump and a vacuum box mechanical pump.

4. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 2, characterized in that: The clamping platform comprises a horizontal surface, a pulley is provided at the bottom of the horizontal surface, and a clamping arm is provided on the horizontal surface.

5. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 2, characterized in that: The electron gun system comprises an electron gun which is arranged outside the vacuum box and faces the divertor specimen. The electron gun is sequentially connected to an electron gun molecular pump and an electron gun mechanical pump.

6. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 2, characterized in that: The optical observation system includes a spotlight light source, a right-angle reflector, a telephoto lens, and a camera. The spotlight light source illuminates the right-angle reflector located at the bottom of the divertor specimen through the observation window. The right-angle reflector reflects light onto the heat exchange surface of the divertor specimen. The reflected light from the heat exchange surface then returns along the original path through the right-angle reflector and is transmitted to the camera through the telephoto lens.

7. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 6, characterized in that: The camera is connected to a collection system.

8. The in-situ observation device for subcooled flow boiling under ultra-high heat flux according to claim 2, characterized in that: The water circulation system includes a heat exchanger, and the cold end of the heat exchanger is cyclically connected to an oil pump and an oil tank; An inlet temperature sensor and an inlet pressure sensor are sequentially arranged between the hot end flow outlet of the heat exchanger and the inlet of the divertor specimen, and an outlet pressure sensor, an outlet temperature sensor, a pressurizer, a vortex flowmeter, a magnetic pump and a safety valve are sequentially arranged between the outlet of the divertor specimen and the hot end flow inlet of the heat exchanger.

9. A method for in-situ observation of subcooled flow boiling under ultra-high heat flux, characterized by: The following steps are involved: S1. Assemble and solidify the designed divertor specimen; 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, fill it with water, pressurize it, and check for leaks; S4. Adjust the optical path to ensure that the camera field of view clearly and completely captures the image of the area to be observed; S5. Start the heat exchanger to adjust the cooling water temperature inside the divertor specimen to a given value, then start the magnetic pump to adjust the cooling water flow rate inside the divertor specimen to a given value, and finally use the pressurizer to adjust the cooling water pressure to a given value; S6. Close the door of the vacuum box and start the mechanical pump of the vacuum box to evacuate the vacuum box. When the internal pressure of the vacuum box drops to 20 Pa, start the molecular pump of the vacuum box. When the internal pressure of the vacuum box is lower than 0.1 Pa, the vacuuming of the vacuum box is completed. S7, start the electron gun mechanical pump to evacuate the inside of the electron gun. When the instrument shows that the internal air pressure is lower than 7 Pa, start the electron gun molecular pump. When the internal air pressure of the electron gun is lower than 0.001 Pa, the electron gun vacuuming work is completed. S8. Open the electron gun valve to connect the electron gun to the vacuum box, adjust the electron gun scanning area to the target area size, and then adjust the number of electron gun points and frequency to achieve uniform loading; S9, set the electron gun beam current to load from 10mA, and at the same time, the camera starts to collect images. After the thermocouple temperature stabilizes, it is considered that the heat transfer has reached a stable state, and the loading and image collection are stopped; S10, after the electron gun beam current is loaded to 10 mA, repeat step S9; S11. Process the temperature data, obtain the boiling curve according to the heat transfer law, analyze it in combination with the image data, and analyze the advantages and disadvantages of the heat exchange structure according to the bubble generation and movement behavior to determine the optimization direction.

10. The in-situ observation method for subcooled flow boiling under ultra-high heat flux according to claim 9, characterized in that: Thermal loading is performed using an electron gun with a maximum heat flux of 30 MW / m2.

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