Variable thermal resistance structure suitable for material irradiation temperature adjustment and design method

Abstract

The invention relates to the technical field of research reactor material irradiation, and provides a variable thermal resistance structure suitable for material irradiation temperature adjustment and a design method, the variable thermal resistance structure comprises a protection tube and a to-be-tested sample arranged in the protection tube, an elastic thermal resistor is arranged between the protection tube and the to-be-tested sample, and the elastic thermal resistor is in contact with the protection tube and the to-be-tested sample at the same time; the cross section of the elastic thermal resistor is of an annular structure formed by continuous bending, inert gas is further filled between the protection tube and the sample to be tested, the elastic thermal resistor is in contact with the outer wall of the sample to be tested and the inner wall of the protection tube at the same time, heat transfer of an original air gap layer is changed, and heat transfer performance is enhanced; meanwhile, the elastic thermal resistor formed by bending has certain ductility, so that the outward heat transfer capacity of the sample to be tested in the irradiation test is enhanced, the influence of thermal expansion on heat transfer is reduced, and the irradiation test requirements of various materials are met; parameter determination is carried out through an out-of-pile verification test, and in-pile condition tests are combined, so that the elastic thermal resistance meeting the requirements is rapidly screened out.

Description

Technical Field

[0001] The present invention relates to the technical field of research reactor material irradiation, and in particular to a variable thermal resistance structure and a design method suitable for material irradiation temperature regulation. Background Art

[0002] With the advancement of nuclear energy technology, the research and development of new fuels and cladding materials face diverse irradiation requirements, among which the temperature and neutron injection of irradiation tests are key indicators. With the increase in irradiation test tasks and the improvement of requirements, under certain specific conditions, the heat release parameters of the material may cause the air gap size to be too small or too large, making the traditional temperature control method unable to meet the needs of irradiation experiments.

[0003] Under the irradiation conditions of high heat release rate and low irradiation temperature, higher heat release rate requires higher gamma heat release and other conditions, which prompts the material irradiation to usually select the high neutron injection area of ​​the research reactor. However, this approach may lead to insufficient air gap size when using air gap structure design, and even make the irradiation temperature of the material significantly higher than the target temperature. In order to solve this problem, liquid sodium, liquid lead bismuth and other media have been used at home and abroad, taking advantage of the good filling and thermal conductivity of liquid metal to enhance the heat transfer capacity of the material during irradiation, thereby achieving the target temperature. However, this method is only applicable to specific irradiation requirements such as liquid metal environment, and its scope of application is relatively limited.

[0004] In certain high-temperature irradiation conditions, the air gap design for irradiation tests using pure helium is large, and when a small amount of low thermal conductivity gas such as argon is introduced, the temperature fluctuation may be very drastic, thus affecting the temperature adjustability.

[0005] Therefore, in order to adapt to the development of nuclear energy technology and meet the needs of various material irradiation tests, it is particularly necessary to design a variable thermal resistor suitable for material irradiation temperature regulation. Summary of the invention

[0006] The purpose of the present invention is to provide a variable thermal resistance structure and design method suitable for material irradiation temperature regulation, to solve the above technical problems, with high flexibility and wide application range, able to meet the needs of various material irradiation tests, and to enhance heat transfer performance.

[0007] The present invention is achieved through the following technical scheme: a variable thermal resistance structure suitable for adjusting the irradiation temperature of a material, comprising a protective tube and a sample to be tested arranged in the protective tube, an elastic thermal resistance is arranged between the protective tube and the sample to be tested, the elastic thermal resistance is in contact with the protective tube and the sample to be tested at the same time, the cross section of the elastic thermal resistance is a ring structure formed by continuous bending, and an inert gas is also filled between the protective tube and the sample to be tested.

[0008] Furthermore, the elastic thermal resistor is provided with an arch on the contact surface with the protection tube and the sample to be tested.

[0009] Furthermore, the cross section of the minimum bending unit of the elastic thermal resistor is trapezoidal, V-shaped, U-shaped or arc-shaped.

[0010] Furthermore, the thickness of the elastic thermal resistor is 0.05-0.1 mm.

[0011] Furthermore, the bending height of the elastic thermal resistor is 0.1-0.7 mm.

[0012] Furthermore, the elastic thermal resistor is made of heat-conducting metal material.

[0013] Furthermore, the sample to be tested is in a tubular or cylindrical shape.

[0014] A design method comprises the following steps:

[0015] Step S1, determining the size of the elastic thermal resistor according to the size, heat release and irradiation temperature requirements of the sample to be tested, and preliminarily selecting the material and bending form of the elastic thermal resistor;

[0016] Step S2: Based on the screening result of step S1, an off-pile verification test is performed to screen elastic thermal resistance that preliminarily meets the requirements;

[0017] Step S3, based on the screening result of step S2, using the in-pile condition test to obtain the change law of elastic thermal resistance under the in-pile irradiation condition;

[0018] Step S4: After optimizing and improving according to the above-mentioned change rules, carry out subsequent formal tests.

[0019] Furthermore, in the off-pile verification test, the elastic thermal resistor is clamped and flattened to maintain continuous bending. One side of the plate is provided with a pressure measuring device for detecting the pressure on the elastic thermal resistor and a cooling system for simulating the cooling environment temperature, and the other side of the plate is provided with a heating system for simulating the irradiation power conditions. The temperature change laws of the elastic thermal resistor with pressure, power and cooling temperature factors are obtained respectively, and the elastic thermal resistor that meets the test requirements is screened out.

[0020] Furthermore, in the in-pile condition test, based on the elastic thermal resistance selected by the out-pile verification test, an analog size simulation method is adopted to carry out a magnified test in the pile according to the actual size of the target sample, and the temperature change law of the elastic thermal resistance in the magnified test is obtained.

[0021] The present invention has at least the following advantages and beneficial effects:

[0022] (1) The elastic thermal resistor is used to contact the outer wall of the sample to be tested and the inner wall of the protective tube at the same time, which increases the metal heat conduction form, changes the heat transfer of the original air gap layer, and enhances the heat transfer performance; at the same time, the bent elastic thermal resistor has a certain ductility, which not only enhances the heat transfer capacity of the sample to be tested during the irradiation test, but also reduces the influence of thermal expansion on heat transfer, thus meeting the needs of various material irradiation tests.

[0023] (2) By adjusting the material, thickness, bending height and bending form of the elastic thermal resistor, the thermal conductivity, contact area and ductility of the elastic thermal resistor are changed, thereby achieving the adjustability of the thermal resistor layer within a certain range.

[0024] (3) By setting an arch on the contact surface of the elastic thermal resistor, the contact change between the elastic thermal resistor structure and the sample to be tested and the protective tube caused by thermal expansion can be further reduced, forming a stable thermal resistance layer and increasing the stability of the irradiation temperature.

[0025] (4) Determine the parameters through off-pile verification tests, and combine them with in-pile condition tests to quickly screen out the elastic thermal resistance that meets the requirements.

[0026] (5) By filling inert gas between the test sample and the protective tube and adjusting the inert gas composition, the thermal resistance layer can be further adjusted, which has a wide range of applications and meets the temperature control requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the installation of a variable thermal resistance structure suitable for regulating the irradiation temperature of a material provided by the present invention.

[0028] Figure 2 For the present invention Figure 1 A partial enlarged view of point A in the middle.

[0029] Figure 3 It is a schematic diagram of a structural form of a bending unit with minimum elastic thermal resistance in the present invention.

[0030] Figure 4 It is a schematic diagram of another structural form of the bending unit with minimum elastic thermal resistance in the present invention.

[0031] Figure 5 It is a schematic diagram of another structural form of the bending unit with minimum elastic thermal resistance in the present invention.

[0032] Reference numerals: 1-protection tube, 2-sample to be tested, 3-elastic thermal resistance, 30-bend. DETAILED DESCRIPTION

[0033] The following is a specific implementation method in conjunction with the accompanying drawings.

[0034] Example

[0035] like Figure 1 , 2 As shown, in this embodiment, a variable thermal resistance structure suitable for adjusting the irradiation temperature of a material is disclosed, comprising a protection tube 1 and a sample 2 to be tested arranged in the protection tube 1, an elastic thermal resistor 3 is arranged between the protection tube 1 and the sample 2 to be tested, the elastic thermal resistor 3 is in contact with the protection tube 1 and the sample 2 to be tested at the same time, the cross section of the elastic thermal resistor 3 is a ring structure formed by continuous bending, and an inert gas is also filled between the protection tube 1 and the sample 2 to be tested; it should be noted that there is an air gap between the protection tube 1 and the sample 2 to be tested, forming a thermal resistance layer, and the present invention pre-fills the thermal resistance layer with an inert gas, and the inert gas can be helium, argon or neon. In addition, the inert gas is not limited to the use of a single gas, and a plurality of inert gases can also be used. The gas mixture can be used as the filling gas. According to the temperature requirement of the irradiation test, the temperature can be adjusted and controlled by filling or changing the inert gas composition, so that the thermal resistance layer between the sample to be tested 2 and the protective tube 1 has a certain variability. Specifically, the elastic thermal resistor 3 is made of a heat-conducting metal material. The elastic thermal resistor 3 is rolled into a ring shape after continuous bending and placed between the sample to be tested 2 and the protective tube 1, which increases the metal thermal conductivity, changes the heat transfer of the original air gap layer, and enhances the heat transfer performance. At the same time, the bent elastic thermal resistor 3 has a certain ductility, which not only enhances the outward heat transfer capacity of the sample to be tested 2 in the irradiation test, but also reduces the influence of thermal expansion on heat transfer, thereby meeting the requirements of various material irradiation tests.

[0036] Furthermore, in a specific implementation, the elastic thermal resistor 3 provided in the embodiment of the present invention is provided with an arch 30 on the contact surface with the protection tube 1 and the sample to be tested 2; the influence of the contact between the elastic thermal resistor 3 structure and the sample to be tested 2 and the protection tube 1 caused by structural changes such as thermal expansion caused by irradiating the test sample can be further reduced, thereby forming a stable thermal resistance layer and increasing the stability of the irradiation temperature.

[0037] Furthermore, in a specific implementation, the cross-section of the minimum bending unit of the elastic thermal resistor 3 provided in the embodiment of the present invention is trapezoidal, V-shaped, U-shaped or arc-shaped; during the irradiation test, the sample 2 to be tested generates thermal expansion due to the increase in temperature, and squeezes the elastic thermal resistor 3. The elastic thermal resistor 3 has a certain elasticity through the above-mentioned structural form, which can reduce the change of the thermal resistance layer due to the change of the contact area of ​​the elastic thermal resistor 3 caused by thermal expansion during the irradiation test. To a certain extent, it has the robustness of structural changes. In the application of pre-filling inert gas, the influence of structural changes on the irradiation temperature is reduced.

[0038] Furthermore, in a specific implementation, the thickness of the elastic thermal resistor 3 provided in the embodiment of the present invention is 0.05-0.1 mm, and the bending height of the elastic thermal resistor 3 is 0.1-0.7 m; the parameters are determined according to the heat release and diameter of the sample to be tested. For example, when the diameter of the sample to be tested is small, the thickness and bending height of the elastic thermal resistor 3 are both smaller values. By appropriately adjusting the thickness and bending height of the elastic thermal resistor 3, the heat transfer performance of the irradiated test sample is changed to meet the irradiation test requirements.

[0039] Furthermore, in the specific implementation, the above-mentioned

[0040] Furthermore, in a specific implementation, the above-mentioned sample 2 to be tested provided in the embodiment of the present invention is in a tubular or cylindrical shape.

[0041] In this embodiment, a design method based on a variable thermal resistance structure suitable for material irradiation temperature regulation is also disclosed. The overall idea is to preliminarily select the elastic thermal resistor 3 material and bending form according to the target air gap structure and irradiation index, wherein different bending forms mainly correspond to different contact areas, and then the selected multiple materials and elastic thermal resistors 3 with different bending forms are subjected to reduction simulation outside the pile to further select the elastic thermal resistor 3 materials and bending forms that meet the requirements, and then the enlargement test is carried out in the pile according to the actual size of the target sample with the further selected materials and bending forms, and finally the temperature change law of the elastic thermal resistor 3 measured inside and outside the pile is fitted, and after appropriate adjustment (for example, the temperature change of the elastic thermal resistor 3 in the in-pile test is greater than that in the out-pile test, which can be achieved by changing the filling inert gas composition or reducing the contact area between the elastic thermal resistor 3 and the sample 2 to be tested and the protective tube 1), the subsequent formal test can be carried out, which mainly includes the following steps:

[0042] Step S1, according to the size, heat release and irradiation temperature requirements of the sample 2 to be tested, determine the size of the elastic thermal resistor 3, and preliminarily select the material and bending form of the elastic thermal resistor 3; specifically, two groups of test pieces are respectively set outside the pile and inside the pile, and the sample 2 to be tested here actually refers to the final target sample inside the pile;

[0043] Step S2: Based on the screening results of step S1, an out-of-pile verification test is used to screen elastic thermal resistors 3 that preliminarily meet the requirements; that is, according to the selected materials and bending forms, a reduction simulation is first performed outside the pile for further screening;

[0044] Step S3, based on the screening result of step S2, using the in-pile condition test to obtain the change law of the elastic thermal resistance 3 under the in-pile irradiation condition;

[0045] Step S4: After optimizing and improving according to the above-mentioned change rules, carry out subsequent formal tests.

[0046] Furthermore, in a specific implementation, in the above-mentioned off-pile verification test provided in an embodiment of the present invention, the elastic thermal resistor 3 is clamped and flattened to maintain continuous bending, and one side of the plate is provided with a pressure measuring device for detecting the pressure on the elastic thermal resistor 3 and a cooling system for simulating the cooling environment temperature, and the other side of the plate is provided with a heating system for simulating the irradiation power conditions, so as to obtain the temperature variation law of the elastic thermal resistor 3 with the pressure, power and cooling temperature factors, and screen out the elastic thermal resistor 3 that meets the test requirements.

[0047] Furthermore, in the specific implementation, in the above-mentioned in-pile condition test provided in the embodiment of the present invention, the elastic thermal resistor 3 selected according to the off-pile verification test is subjected to an enlarged test in the pile according to the actual size of the target sample by adopting an analog size simulation method, and the temperature change law of the elastic thermal resistor 3 in the enlarged test is obtained.

Claims

1. A variable thermal resistance structure suitable for adjusting the irradiation temperature of a material, comprising a protection tube (1) and a sample to be tested (2) arranged in the protection tube (1), characterized in that: An elastic thermal resistor (3) is provided between the protection tube (1) and the sample to be tested (2); the elastic thermal resistor (3) is in contact with both the protection tube (1) and the sample to be tested (2); the cross section of the elastic thermal resistor (3) is a ring structure formed by continuous bending; and an inert gas is also filled between the protection tube (1) and the sample to be tested (2).

2. A variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The elastic thermal resistor (3) is provided with an arch (30) on the contact surface with the protection tube (1) and the sample to be tested (2).

3. A variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The cross section of the smallest bending unit of the elastic thermal resistor (3) is trapezoidal, V-shaped, U-shaped or arc-shaped.

4. A variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The thickness of the elastic thermal resistor (3) is 0.05-0.1 mm.

5. The variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The bending height of the elastic thermal resistor (3) is 0.1-0.7 mm.

6. A variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The elastic thermal resistor (3) is made of a heat-conducting metal material.

7. The variable thermal resistance structure suitable for adjusting the irradiation temperature of a material according to claim 1, characterized in that: The sample to be tested (2) is in the shape of a tube or a cylinder.

8. A design method for a variable thermal resistance structure suitable for adjusting the irradiation temperature of a material based on any one of claims 1 to 7, characterized in that: The following steps are involved: Step S1, determining the size of the elastic thermal resistor (3) according to the size, heat release and irradiation temperature requirements of the sample (2) to be tested, and preliminarily screening the material and bending form of the elastic thermal resistor (3); Step S2, based on the screening result of step S1, using an off-pile verification test to screen the elastic thermal resistor (3) that preliminarily meets the requirements; Step S3, based on the screening result of step S2, using an in-pile condition test to obtain a variation law of the elastic thermal resistance (3) under in-pile irradiation conditions; Step S4: After optimizing and improving according to the above-mentioned change rules, carry out subsequent formal tests.

9. The design method according to claim 8, characterized in that: In the off-pile verification test, the elastic thermal resistor (3) is clamped and flattened to maintain continuous bending. On one side of the plate, a pressure measuring device for detecting the pressure on the elastic thermal resistor (3) and a cooling system for simulating the cooling environment temperature are provided. On the other side of the plate, a heating system for simulating the irradiation power condition is provided. The temperature variation law of the elastic thermal resistor (3) with the change of pressure, power and cooling temperature factors is obtained respectively, and the elastic thermal resistor (3) that meets the test requirements is screened out.

10. The design method according to claim 8, characterized in that: In the in-pile condition test, based on the elastic thermal resistor (3) selected in the out-pile verification test, an analog size simulation method is adopted to carry out an enlarged test in the pile according to the actual size of the target sample, and the temperature change law of the elastic thermal resistor (3) in the enlarged test is obtained.

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