A long electric heating plate heat insulation structure and a heat transfer simulation experiment device with the same

Abstract

The application relates to the technical field of reactor thermal hydraulic and safety, in particular to a long electric heating plate heat insulation structure and a heat transfer simulation experiment device with the same. The long electric heating plate heat insulation structure comprises a heat insulation base, a heating plate and a glue layer; the heat insulation base is configured as a ceramicized resin plate, one plate surface of the heat insulation base is provided with a sink; the heating plate is arranged in the sink so that the plate surface of the heating plate is flush with the plate surface of the heat insulation base, the surface of the heating plate corresponding to the sink wall and the sink bottom is provided with a microporous alumina ceramic layer which is nano-treated by using an active coupling agent; and the glue layer is arranged between the heating plate and the heat insulation base under a high-temperature vacuum pressure environment. The application can ensure that the heating plate has good single-side heat dissipation performance under the temperature condition of bubble formation on the surface of a dispersed fuel element, can guarantee the test safety of the heat transfer simulation experiment device during operation, and can ensure the accuracy of the measurement result in the simulation test.

Description

Technical Field

[0001] This application relates to the fields of reactor thermal hydraulics and safety technology, specifically to a long electric heating plate insulation structure and a heat transfer simulation experimental device having the same. Background Technology

[0002] Rectangular slit channels, with their compact structure and large heat exchange area, have been widely used in heat exchangers and nuclear reactor fuel assemblies. However, due to factors such as the corner effect at the corners of the rectangular slit channel, its flow and heat transfer characteristics, including the critical heat flux density, differ significantly from those of a corresponding hydraulic diameter circular pipe channel. Therefore, specialized experiments on flow and heat transfer and critical heat flux density in rectangular channels are necessary. These experiments typically employ a long, electrically heated metal plate with a large aspect ratio for heating, and the insulation of this plate is crucial for experimental safety. Furthermore, these experiments often use single-sided heating simulations, requiring that all heat generated by the energized metal plate enters the coolant channel through a single heated surface; the other surfaces of the metal plate are non-heated and require insulation. Currently, experimental models often use ceramic or PTFE plates spliced ​​together to form partitions to achieve insulation and heat insulation for the electric heating plate. However, the splicing method is relatively complex, requiring high dimensional tolerances and installation precision. Furthermore, leaks at the joints can affect the insulation performance, jeopardizing experimental safety and impacting the accuracy of measurements such as the temperature of the heated wall surface. Summary of the Invention

[0003] This application provides a long-term electric heating plate insulation structure and a heat transfer simulation experimental device with it. The heating plate and the insulation base are sealed by gluing, which reduces the dimensional tolerance and installation accuracy requirements of the heating plate and the insulation base, and reduces the risk of water leakage at the joint. This solves the problems of existing splicing methods that endanger test safety and affect the accuracy of measurement results such as the temperature of the heated wall.

[0004] This application is achieved through the following technical solution:

[0005] In a first aspect, this application provides a long-electric heating plate insulation structure, comprising:

[0006] Insulating base, wherein the insulating base is configured as a ceramicized resin plate, and a groove is formed on one side of the insulating base.

[0007] A heating plate is disposed in the settling tank so that the surface of the heating plate is flush with the surface of the heat insulation base. A microporous alumina ceramic layer treated with an active coupling agent is disposed on the surface of the heating plate corresponding to the tank wall and the bottom of the settling tank.

[0008] An adhesive layer is provided between the heated plate and the heat-insulating base under high temperature and vacuum pressure.

[0009] In some optional embodiments, the thickness of the microporous alumina ceramic layer is configured to be 10–50 μm.

[0010] In some optional embodiments, the aspect ratio of the micropores in the microporous alumina ceramic layer is configured to be on the micrometer scale.

[0011] In some alternative embodiments, the walls and bottom of the settling tank are configured as laser-activated surfaces.

[0012] Secondly, this application provides a heat transfer simulation experimental apparatus for simulating the foaming condition on the surface of a dispersed fuel element, including:

[0013] As described in the first aspect, in any of the long electric heating plate insulation structures, the heating plate has a vacuum bubble-like portion on the surface facing away from the insulation base, the insulation base is provided with an elastic sealing cavity, the elastic sealing cavity is filled with heat-insulating powder, and the insulation base is also provided with a temperature measuring hole corresponding to the position of the vacuum bubble-like portion, so that the thermocouple can pierce the elastic sealing cavity through the temperature measuring hole and contact the heating plate.

[0014] The cover has a flow groove, and the cover is connected to the heat insulation base so that the heat insulation base seals the flow groove to form a narrow slit channel, and the heat receiving plate is located in the narrow slit channel;

[0015] A media inlet device, wherein the media inlet device is connected to one end of the narrow slit channel;

[0016] A media outlet component, which is connected to the other end of the narrow slit channel;

[0017] The conductive elements are respectively connected to the two ends of the heated plate, and the vacuum bubble section is located between the two conductive elements.

[0018] In some alternative embodiments, the cover is sealed to the heat-insulating base by a static sealing ring, wherein the static sealing ring is arranged around the flow groove.

[0019] In some optional embodiments, the light transmittance of the cover is configured to be not less than 98%.

[0020] In some alternative embodiments, the cover is configured as optical quartz glass.

[0021] In some alternative embodiments, the conductive element is connected to the heated plate by silver soldering.

[0022] In some optional embodiments, the number of temperature measuring holes is configured to be multiple, and the distance between the multiple temperature measuring holes and the vacuum bubble portion is no more than 10 mm from the normal viewing angle of the heated plate surface.

[0023] In some alternative embodiments, at least one temperature sensing hole corresponds to the center position of the vacuum bubble portion.

[0024] In some optional embodiments, the heat-insulating base has a detachable positioning plate, the positioning plate including a lower baffle and an upper baffle embedded in the lower baffle, the upper baffle and the lower baffle forming an installation cavity suitable for accommodating the elastic sealing cavity, and the temperature measuring hole is located on the positioning plate; wherein, the positioning plate corresponds to the position of the vacuum bubble portion.

[0025] In some alternative embodiments, a pressure testing connector is also included, which communicates with the narrow slit channel.

[0026] In some optional embodiments, the media inlet and / or media outlet are configured with a temperature sensing connector.

[0027] In some optional embodiments, a first pressure-bearing block and a second pressure-bearing block arranged at intervals are also included, the first pressure-bearing block being connected to the second pressure-bearing block, wherein the first pressure-bearing block abuts against the base and the second pressure-bearing block abuts against the cover.

[0028] In some alternative embodiments, the heating plate includes:

[0029] A foaming plate, wherein the foaming plate is formed with grooves by a casting process;

[0030] A heating plate, wherein the heating plate and the bubbling plate are arranged in parallel and spaced apart;

[0031] An insulating layer is located between the foaming plate and the heating plate. The insulating layer is connected to the heating plate and is connected to the foaming plate by vacuum diffusion welding to form a vacuum bubble-like part with the groove on the foaming plate.

[0032] Compared with the prior art, this application has the following advantages and beneficial effects:

[0033] 1. The thermal insulation structure of the electric heating plate provided in this application has a thermally sealed connection between the heating plate and the thermal insulation base by adhesive bonding, which greatly reduces the requirements for dimensional tolerances and installation accuracy of the heating plate and the thermal insulation base. The microporous alumina ceramic layer can be tightly connected with the heating plate. Under high temperature vacuum pressure environment, the adhesive layer can combine with the active coupling agent in the micropores, so that the adhesive layer can have a large connection strength with the heating plate. This ensures that the thermal insulation base can have a large connection strength with the heating plate to meet the temperature under the foaming condition of the dispersion type fuel element, and prevents the adhesive layer from detaching from the heating plate under high temperature conditions.

[0034] 2. The heat transfer simulation experimental device provided in this application can simulate the structural state of a diffuse fuel element under bubbling conditions by the vacuum bubble section on the heated plate. A narrow slit channel is formed by connecting the cover and the insulating base. The medium flows in the narrow slit channel using the medium inlet and outlet components, and the heated plate is heated by the conductive components. At the same time, the heated plate achieves unilateral heat diffusion into the narrow slit channel under the insulating effect of the insulating base. It can obtain the same heating and heat transfer conditions as when the diffuse fuel element is bubbling, and provide the same coolant thermal boundary as when the diffuse fuel element is bubbling. Thus, it can accurately simulate the heating boundary and flow channel geometric boundary of the diffuse fuel element. Finally, the temperature of the heated plate can be easily measured directly by the setting of the temperature measuring hole.

[0035] 3. The heat transfer simulation experimental device provided in this application has an external temperature measuring element, which does not need to be continuously in a high-temperature working environment, thus improving the accuracy of temperature measurement. After the measurement is completed, the elastic sealing cavity uses its own elasticity to compress the heat insulation powder inside to fill the hole formed by the puncture of the temperature measuring element, thereby preventing heat loss from the heated plate and ensuring that the thermal boundary of the coolant in the narrow channel is basically consistent with the actual working conditions. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the exemplary embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0037] Figure 1 This is a schematic cross-sectional view of the thermal insulation structure of the electric heating plate provided in the embodiments of this application.

[0038] Figure 2 for Figure 1 Enlarged structural diagram at point C;

[0039] Figure 3 This is a schematic diagram of the heat transfer simulation experimental device provided in the embodiments of this application;

[0040] Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure at point AA;

[0041] Figure 5 This is a partial structural diagram of the connection between the positioning plate and the first pressure-bearing block provided in an embodiment of this application;

[0042] Figure 6 This is a schematic diagram of the cross-sectional structure of the positioning plate provided in an embodiment of this application;

[0043] Figure 7 This is a schematic diagram of the heat-receiving plate structure provided in an embodiment of this application.

[0044] The attached diagram shows the markings and corresponding component names:

[0045] 1-Media inlet component, 2-Media outlet component, 3-Second pressure-bearing block, 4-Cover body, 5-Heating plate, 51-Bubble plate, 52-Heating plate, 53-Insulation layer, 6-Insulating base, 7-Narrow slit channel, 8-Conductive component, 9-First pressure-bearing block, 10-Temperature measuring hole, 11-Positioning plate, 111-Upper baffle, 112-Lower baffle, 113-Elastic sealing cavity, 114-Insulating powder, 12-Temperature measuring pipe, 13-Pressure measuring pipe, 14-Adhesive layer, 15-Microporous alumina ceramic layer. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0047] Firstly, you can refer to this as well. Figure 1 and Figure 2 This application provides a long-term electric heating plate insulation structure, including an insulation base 6, a heating plate 5 and an adhesive layer 14.

[0048] The heat insulation base 6 is configured as a ceramicized resin plate, which means that the overall shape of the heat insulation base 6 is plate-shaped. The ceramicized resin plate has good heat resistance, wear resistance, impact resistance and machinability, and is suitable for processing long plates. One of the plate surfaces of the heat insulation base 6 has a groove.

[0049] The heating plate 5 can be configured as an electrically conductive metal plate. The heating plate 5 is placed in the settling tank so that the plate surface of the heating plate 5 is flush with the plate surface of the heat insulation base 6. A microporous alumina ceramic layer 15, which is nano-treated by an active coupling agent, is provided on the surface of the heating plate 5 corresponding to the tank wall and the bottom of the tank.

[0050] The adhesive layer 14 is placed between the heated plate 5 and the heat-insulating base 6 under high temperature vacuum pressure environment.

[0051] In this embodiment, the heating plate 5 is a conductive metal plate with a relatively smooth surface. Therefore, directly bonding the adhesive to the heating plate 5 would result in low connection strength and insufficient adhesion at the bonding surfaces. Specifically, after the adhesive cures, tiny gaps exist between it and the surface of the heating plate 5, leading to a larger actual heat dissipation area. Furthermore, under prolonged high-temperature conditions, the adhesive may delaminate at the bonding point, causing the gaps to widen and further increasing the heat dissipation area. This would significantly affect the unilateral heat dissipation effect of the heating plate 5. However, by first bonding the microporous alumina ceramic layer 15 to the heating plate 5, the microporous alumina ceramic layer 15 exhibits greater bonding strength with the heating plate 5, and the bonding... The microporous alumina ceramic layer 15 is nano-sized using an active coupling agent, allowing the adhesive to penetrate the micropores of the layer under high temperature and vacuum pressure and combine with the active coupling agent. This results in a stronger bond between the adhesive and the microporous alumina ceramic layer 15, with a very high degree of tightness. Consequently, there are fewer or no micro-gaps between the adhesive and the heating plate 5. After the adhesive combines with the active coupling agent in the micropores, the adhesive and the microporous alumina ceramic layer 15 will not easily detach at high temperatures (i.e., the operating temperature of the dispersed fuel element foaming), thus ensuring that the heating plate 5 has a good unilateral heat dissipation effect, guaranteeing experimental safety and the accuracy of measurement results.

[0052] In this embodiment of the application, the heated plate 5 may also be configured as a non-metallic conductive plate such as silicon, germanium, silicon carbide, gallium arsenide, carbon fiber, graphite, carbon nanotubes, ceramic fiber, carbon-based composite plate, etc.

[0053] In this embodiment, the heat insulation base 6 is configured as a plate to facilitate processing and reduce the overall space occupied by the heat insulation structure. In other embodiments, the shape of the heat insulation base 6 is not limited, and the shape of the heat insulation base 6 does not affect its heat insulation performance on the heat-receiving plate 5. That is to say, in this application, in order to achieve the heat insulation effect on the heat-receiving plate 5, heat insulation bases 6 of other shapes can be equivalent to plate-shaped heat insulation bases 6.

[0054] In some optional embodiments, the thickness of the microporous alumina ceramic layer 15 can be configured to be 10-50 μm to ensure the connection strength between the microporous alumina ceramic layer 15 and the heat-receiving plate 5, as well as the connection strength between the microporous alumina ceramic layer 15 and the adhesive. At the same time, a smaller microporous alumina ceramic layer 15 can reduce heat loss and ensure the heat dissipation effect of the heat-receiving plate 5 on one side.

[0055] In some optional embodiments, the aspect ratio of the micropores in the microporous alumina ceramic layer 15 can be configured to be on the micrometer level. This ensures that the microporous alumina ceramic layer 15 and the adhesive layer 14 have a large bonding surface area, while also ensuring that the adhesive layer 14 and the microporous alumina ceramic layer 15 have a good mechanical locking effect, thereby ensuring the connection strength between the adhesive layer 14 and the microporous alumina ceramic layer 15.

[0056] In some alternative embodiments, the walls and bottom of the settling tank are configured as laser-activated surfaces, which can further enhance the connection strength between the adhesive layer 14 and the thermal insulation base 6.

[0057] Secondly, please refer to the following: Figures 1-4 This application provides a heat transfer simulation experimental device for simulating the foaming condition on the surface of a diffuse fuel element. The heat transfer simulation experimental device includes a cover 4, a medium inlet 1, a medium outlet 2, a conductive element 8, and any of the long electric heating plate insulation structures described in the first aspect.

[0058] In the thermal insulation structure of the electric heating plate, one surface of the heating plate 5 has a vacuum bubble-like section, which is manifested as a hollow protrusion on one surface of the heating plate 5. The vacuum bubble-like section can be formed by casting or by connecting two components together. The hollow protrusion contains a vacuum cavity. Preferably, the heating plate 5 is formed by welding two plates, one of which serves as a connector, and the other plate can be formed by casting a protrusion and then welding it to the first plate.

[0059] See also Figure 6The insulating base 6 has a grooved plate surface as its working surface. An elastic sealing cavity 113 is provided inside the insulating base 6. The elastic sealing cavity 113 can be made of rubber or silicone material and is filled with insulating powder 114. In practice, the insulating powder 114 can be configured as glass fiber powder. The insulating base 6 also has a temperature measuring hole 10 corresponding to the position of the vacuum bubble section. The thermocouple can pierce the elastic sealing cavity 113 through the temperature measuring hole 10 and then contact the heated plate 5. In practice, a piercing hole with a diameter much smaller than the thermocouple can be made on the elastic sealing cavity 113. Due to the material properties of the elastic sealing cavity 113 itself, the thermocouple piercing projectile... After the elastic sealing cavity 113 is sealed, the wall of the puncture hole can adhere tightly to the thermocouple due to its own elastic deformation. At the same time, the heat-insulating powder 114 inside the elastic sealing cavity 113 becomes more compact under the pressure of the thermocouple, meaning that the heat-insulating powder 114 can also adhere tightly to the thermocouple. Of course, due to the compression of the heat-insulating powder 114, the cavity wall of the elastic sealing cavity 113 will also undergo a certain elastic deformation. After the temperature measurement is completed, the thermocouple is removed. The puncture hole of the elastic sealing cavity 113 returns to its original shape under the action of elastic deformation, while the heat-insulating powder 114 inside is compressed under the elastic action of the cavity wall of the elastic sealing cavity 113, causing the heat-insulating powder 114 to flow to the thermocouple. The formed holes indicate that, under the elastic action of the elastic sealing cavity 113, the heat-insulating powder 114 can self-fill, thereby providing better heat insulation for the heated plate 5, preventing heat loss from the heated plate 5, and ensuring that the thermal boundary of the coolant in the narrow slit channel 7 is basically consistent with the actual working conditions. A ceramic tube can be inserted into the temperature measuring hole 10 to achieve insulation. The extension direction of the temperature measuring hole 10 is not limited, such as a straight line, a broken line, a curve, or any combination of two or three of the above. In order to reduce the length of the temperature measuring hole 10 in its extension direction, the extension direction of the temperature measuring hole 10 can be a straight line. The extension direction of the temperature measuring hole 10 can be perpendicular to the plate surface of the heated plate 5 or form an angle. In actual implementation... Preferably, the extension direction of the temperature measuring hole 10 is set to be perpendicular to the surface of the heated plate 5, so as to ensure that the length of the temperature measuring hole 10 in the extension direction is short enough to facilitate the temperature measurement of the heated plate 5 through the temperature measuring hole 10. When the temperature measuring hole 10 is not working, it can be isolated. The shorter temperature measuring hole 10 can ensure that there is less heat exchange medium inside, such as air, in the isolated state, thereby reducing its influence on the local temperature of the heated plate 5 during the test. The cross-sectional shape of the temperature measuring hole 10 is not limited, such as triangle, rectangle, square, circle, heart, star or other irregular shape. In actual implementation, the temperature measuring hole 10 can be set as a circular straight hole.

[0060] The cover 4 has a flow groove, and the cover 4 is connected to the heat insulation base 6 so that the heat insulation base 6 seals the flow groove to form a narrow slit channel 7. The heating plate 5 is located in the narrow slit channel 7, that is, for the cover 4 and the heating plate 5, the heating plate 5 can be placed in the flow groove. The specific form of the flow groove is not limited. It can be a closed groove on the cover 4, that is, a groove with only one opening, or an open groove, that is, the flow groove can penetrate the cover 4 to form two or three openings. In actual implementation, the flow groove can be set as a closed groove. In this way, after the cover 4 is connected to the heat insulation base 6, the heat insulation base 6 can easily seal the flow groove through the working surface to form a narrow slit channel 7. Of course, in other embodiments, if the flow groove is set as an open groove, after the cover 4 is connected to the heat insulation base 6, other openings can be sealed individually or other openings can be connected to it. The components are sealed together; the specific shape of the flow channel is not limited, such as triangle, rectangle, square, circle or other irregular shapes; since a narrow channel 7 for medium flow is formed between the flow channel and the heat insulation base 6, it is preferred to set the flow channel as a channel shape with a certain length, such as a rectangular channel, a square channel, or a prism-shaped channel. Preferably, the flow channel is set as a rectangular channel or a square channel, that is, from the perspective of the length direction of the flow channel, the outline shape of the flow channel is a square or a rectangle. When the flow channel is set as a rectangular channel or a square channel, its extension direction can be a straight line or a curve. In actual implementation, the extension direction of the flow channel can be set as a straight line to ensure that the medium has a stable flow state in the narrow channel 7. In other embodiments, as needed, the extension direction of the flow channel can also be set as a curve or a combination of curve and straight line. When the flow channel is set as a rectangular or square channel, the heating plate 5 can be set as a rectangular plate. That is to say, the thickness of the heating plate 5 is uniform except for the vacuum bubble part. At this time, the overall shape of the narrow channel 7 formed by the flow channel and the insulating base 6 is a cuboid. This is conducive to the centering of the heating plate 5 in the narrow channel 7, ensuring that the heat can be evenly diffused in the narrow channel 7, and ensuring that the medium is heated evenly in the flow direction.

[0061] The medium inlet 1 is connected to one end of the narrow slit channel 7. When the flow channel is a closed channel, the medium inlet 1 can penetrate the insulating base 6 to communicate with the narrow slit channel 7, and the medium inlet 1 is sealed to the insulating base 6. When the flow channel is an open channel, the medium inlet 1 can be directly sealed to the unsealed opening in the flow channel. The medium inlet 1 is typically used for injecting coolant.

[0062] The medium outlet 2 is connected to the other end of the narrow slit channel 7; when the flow channel is set as a closed channel, the medium outlet 2 can pass through the heat insulation base 6 to communicate with the narrow slit channel 7, and the medium outlet 2 is sealed to the heat insulation base 6; when the flow channel is set as an open channel, the medium outlet 2 can be directly sealed to the unclosed opening in the flow channel.

[0063] The two conductive elements 8 are respectively connected to the two ends of the heating plate 5. The conductive elements 8 can be configured as copper busbars, aluminum busbars, stainless steel busbars, zinc alloy busbars, copper alloy busbars, plastic conductive busbars, etc. In actual implementation, the two conductive elements 8 can be the same or different. Preferably, the two conductive elements 8 can be configured as copper busbars. Copper busbars have excellent conductivity, can reduce heat loss, and have good mechanical strength, corrosion resistance, high flexibility, and good welding performance. The vacuum bubble section is located between the two conductive elements 8. That is, when the heating plate 5 is set as a rectangular plate, the two conductive elements 8 can be connected to the two ends of the length direction of the heating plate 5, and the vacuum bubble section can be located in the middle position of the two conductive elements 8 in the length direction of the heating plate 5. Of course, in other embodiments, the vacuum bubble section can also be located at other positions between the two conductive elements 8.

[0064] The heat transfer simulation experimental device provided in this application embodiment can simulate the structural state of a dispersed fuel element under bubbling conditions by using a vacuum bubble section on the heated plate 5. After connecting the two conductive parts 8 to the power supply and connecting the medium inlet 1 and the medium outlet 2 to the medium circulation system, the heated plate 5 can be electrically conductive to generate heat, thereby increasing the temperature. Due to the insulation effect of the insulating base 6, most of the heat from the heated plate 5 is dissipated to the narrow slit channel 7 on one side to heat the medium in the narrow slit channel 7, thereby simulating the working state of the fluid in the dispersed fuel element. The experimenter can measure the temperature field of the medium near the vacuum bubble section and directly measure the temperature of the heated plate 5 at the corresponding position of the vacuum bubble section through the temperature measuring hole 10. Combined with parameters such as the medium pressure and medium flow rate in the medium circulation system, the flow heat transfer characteristics near the vacuum bubble section can be obtained. These flow heat transfer characteristics can provide technical support for the precise formulation of thermal-hydraulic design and safety criteria for dispersed fuel elements.

[0065] Compared with existing three-dimensional numerical simulation methods, the heat transfer simulation experimental device provided in this application embodiment can perform direct measurement, requires less computation, is more convenient to implement, provides more intuitive and easier-to-obtain data, and has considerable reliability in measurement results.

[0066] There are various sealing connection methods between the cover 4 and the heat insulation base 6, such as adhesive sealing, welding sealing, magnetic sealing, and threaded sealing. Considering the overall maintainability of the device, in some optional embodiments, the cover 4 is sealed to the heat insulation base 6 by a static sealing ring. The static sealing ring can be configured as a rubber sealing ring, a metal sealing ring, a polytetrafluoroethylene sealing ring, a graphite sealing ring, etc. In actual implementation, a suitable static sealing ring can be selected according to the thermal conductivity of the cover 4. For example, if the thermal conductivity of the cover 4 is low, a static sealing ring with general heat resistance, such as a rubber sealing ring, can be selected. If the thermal conductivity of the cover 4 is high, a static sealing ring with higher heat resistance, such as a graphite sealing ring, can be selected. In actual implementation, it is generally desirable for the thermal conductivity of the cover 4 to be low. To prevent excessive heat loss from the narrow slit channel 7, ensuring that the temperature of the cover 4 does not become too high during operation, the static sealing ring can be configured as a low-cost static sealing ring such as a rubber sealing ring. The static sealing ring is arranged around the flow groove, and its shape is not limited. For example, it can be rectangular, circular, triangular, or rhomboid, etc. The design can be adapted to the opening of the flow groove to avoid creating a large narrow slit space after the cover 4 is connected to the heat-insulating base 6. For example, when the flow groove is rectangular, its opening is rectangular, and the static sealing ring can be configured as rectangular. Of course, in other embodiments, depending on the needs, such as different installation conditions or different processing precision, the shape of the static sealing ring can also be other irregular shapes.

[0067] The cover 4 can be made of either transparent or opaque material, both of which enable the measurement of parameters such as the temperature of the medium within the narrow slit channel 7. Of course, if the cover 4 has a certain degree of transparency, it can achieve visual measurement of the velocity field and two-phase flow within the medium of the narrow slit channel 7. Therefore, in some optional embodiments, the transmittance of the cover 4 is configured to be not less than 98%. Preferably, the cover 4 can be configured as optical quartz glass. Optical quartz glass has good transmittance and low thermal conductivity, which can reduce heat loss from the medium in the narrow slit channel 7.

[0068] The conductive component 8 is typically connected to other devices requiring conductivity by welding. In this embodiment, the heating plate 5 operates at a relatively high temperature; therefore, the weld between the conductive component 8 and the heating plate 5 must possess certain heat resistance. In some optional embodiments, the conductive component 8 is connected to the heating plate 5 via silver brazing. Silver has a lower coefficient of thermal expansion than copper, meaning that the thermal stress generated at the silver brazing connection point is relatively small during temperature changes, helping to reduce the risk of loosening. Furthermore, silver has good corrosion resistance, especially at high temperatures, which helps extend the service life of the welded area and ensures the conductivity of the conductive component 8 and the heating plate 5.

[0069] In order to facilitate obtaining the temperature field characteristics of the vacuum bubble section and its surroundings, in some optional embodiments, the number of temperature measuring holes 10 is configured to be multiple. From the normal viewing angle of the heated plate 5, the distance between the multiple temperature measuring holes 10 and the vacuum bubble section is no more than 10 mm. This includes temperature measuring holes 10 corresponding to the edge of the vacuum bubble section, and at least one temperature measuring hole 10 corresponding to the center position of the vacuum bubble section at a distance of 10 mm from the vacuum bubble section in the medium flow direction.

[0070] For different heating plates 5, the position and size of the vacuum bubble-like portions vary. In some optional embodiments, the insulation base 6 has a detachable positioning plate 11. The positioning plate 11 can be configured as a polytetrafluoroethylene (PTFE) plate. Specifically, the positioning plate 11 may include a lower baffle 112 and an upper baffle 111. The upper baffle 111 is embedded in the lower baffle 112. The lower baffle 112 is generally a multi-diameter shaft, with a mating groove in its small-diameter section. The upper baffle 111 is similar in shape to a circular cover, and its shape is adapted to fit the mating groove so that it can be embedded within it. The open end of the upper baffle 111 is located inside the mating groove, while the closed end is located outside. The space within the upper baffle 111 serves as an installation cavity. This installation cavity is adapted to the shape of the elastic sealing cavity 113 so that the outer wall of the elastic sealing cavity 113 can fit against the cavity wall of the installation cavity. The positioning plate 11 has... The presence of temperature measuring holes 10 indicates that some of the multiple temperature measuring holes 10 are distributed on the positioning plate 11. Specifically, coaxial holes are formed on the upper baffle 111 and the lower baffle 112, with each pair of coaxial holes on the upper baffle 111 and the lower baffle 112 serving as temperature measuring holes 10. The distribution of temperature measuring holes 10 on different positioning plates 11 varies. Depending on the position and size of the vacuum bubble, the size and position of the temperature measuring holes 10 on the positioning plate 11 are different. This means that by replacing different positioning plates 11 according to the position and size of the vacuum bubble, it is convenient for the thermocouple to measure the heated plate 5. The positioning plate 11 corresponds to the position of the vacuum bubble. In actual implementation, the specific shape of the positioning plate 11 is not limited. It can be constructed as a cylinder to accommodate the detection range around the vacuum bubble. In other embodiments, the positioning plate 11 can also be constructed as a prism, a hemisphere, or other irregular shapes. The positioning plate 11 can also be removed, at which point the bubbling position on the heated plate 5 is exposed, making it easier to measure the wall temperature field using an infrared thermometer.

[0071] See also Figure 5It is understandable that the projected area of ​​the positioning plate 11 in the normal direction of the heated plate 5 may be much larger than that of the vacuum bubble part. At this time, temperature measuring holes 10 can also be provided on the positioning plate 11 at the corresponding positions around the vacuum bubble part. These temperature measuring holes 10 correspond one-to-one with the temperature measuring holes 10 on the heat insulation base 6 and are arranged coaxially.

[0072] In some optional embodiments, the heat transfer simulation experimental device further includes a pressure measuring pipe 13, which is connected to the narrow slit channel 7. In actual implementation, the pressure measuring pipe 13 passes through the insulating base 6 and connects to the narrow slit channel 7. The number of pressure measuring pipes 13 can be configured to be two. In the direction of medium flow, the two pressure measuring pipes 13 are respectively located on both sides of the vacuum bubble section. Preferably, the two pressure measuring pipes 13 are arranged close to the medium inlet 1 and the medium outlet 2, respectively. By setting the pressure measuring pipes 13, the medium pressure in the narrow slit channel 7 can be measured, and the pressure change characteristics of the medium on both sides of the vacuum bubble section can be obtained, which is beneficial for carrying out research on the influence of the vacuum bubble section on the medium pressure under heat generation conditions.

[0073] In some optional embodiments, the medium inlet 1 and / or the medium outlet 2 are equipped with temperature measuring pipes 12. In actual implementation, temperature measuring pipes 12 can be configured on both the medium inlet 1 and the medium outlet 2. The temperature measuring pipes 12 facilitate the measurement / monitoring of the medium temperature before it enters the narrow slit channel 7 and after it flows out of the narrow slit channel 7, which can bring convenience to the measurement process and make it easier to obtain the dynamic change characteristics of the medium temperature under long-term operation.

[0074] In some optional embodiments, the heat transfer simulation experimental device further includes a first pressure block 9 and a second pressure block 3 arranged at intervals, the first pressure block 9 being connected to the second pressure block 3, wherein the first pressure block 9 abuts against the base and the second pressure block 3 abuts against the cover 4.

[0075] In this embodiment, the first pressure block 9 and the second pressure block 3 can press the cover 4 and the heat insulation base 6 together, thereby ensuring the stability of the sealing performance between the cover 4 and the heat insulation base 6. Both the first pressure block 9 and the second pressure block 3 can be constructed as cuboids. The first pressure block 9 can cover the heat insulation base 6, and the second pressure block 3 can cover the cover 4. The first pressure block 9 and the second pressure block 3 can be fastened together with bolts. The temperature measuring pipe 12, the conductive component 8, the pressure measuring pipe 13, the medium inlet component 1, the medium outlet component 2, and the positioning plate 11 can all sequentially pass through the first pressure block 9 and the heat insulation base 6 to communicate with the narrow slit channel 7 or connect with the heat-receiving plate 5. When the cover 4 has a light transmittance of not less than 98%, an observation window can be opened on the second pressure block 3. In the normal direction of the surface of the heat-receiving plate 5, the vacuum bubble portion is located within the area encompassed by the observation window.

[0076] Among them, such as Figure 5 As shown, when the first pressure block 9 and the second pressure block 3 are set, the positioning plate 11 can be connected to the first pressure block 9 by bolts. Therefore, it is not necessary to set a connection structure corresponding to the positioning plate 11 on the heat insulation base 6. When installing the positioning plate 11, it is only necessary to perform relative positioning of the temperature measuring hole 10 and the vacuum bubble part. The heat insulation base 6 does not participate in connecting the positioning plate, and the risk of structural damage to the heat insulation base 6 is greatly reduced, thereby ensuring that it has long-term stable heat insulation performance and / or insulation performance.

[0077] In some alternative embodiments, see [reference]. Figure 7 The heated plate includes a bubbling plate 51, a heating plate 52, and an insulating layer 53. The bubbling plate 51 is formed with grooves by a casting process. The heating plate 52 is arranged in parallel with the bubbling plate 51 at intervals. The insulating layer 53 is located between the bubbling plate 51 and the heating plate 52. The insulating layer 53 is connected to the heating plate 52. The insulating layer 53 is connected to the bubbling plate 51 by vacuum diffusion welding to form a vacuum bubble-like part with the bubbling plate 51.

[0078] When the heating plate provided in this application is used in an experimental apparatus for simulating the heat transfer characteristics under bubbling conditions on the surface of a dispersed fuel element, since the heating plate 52 relies on electricity to generate heat to simulate the heating of the dispersed fuel element, the current only passes through the heating plate 52 and not through the bubbling plate 51 through the setting of the insulating layer 53, thus truly simulating the heat source distribution in the prototype fuel element. This avoids the situation where the self-heating of the bubbling plate 51 affects the temperature field near the vacuum bubbling part, that is, it reduces the influencing factors of the temperature field near the vacuum bubbling part, which is beneficial to subsequent theoretical analysis and ensures the accuracy and reliability of the experimental results. Furthermore, the insulating layer 53 is connected to the bubbling plate 51 by vacuum diffusion welding, and the connection part has high temperature resistance, which is suitable for the bubbling temperature environment on the surface of a dispersed fuel element.

[0079] In actual implementation, the bubbling plate 51 is configured as an Inconel 625 plate, so that the thermal conductivity of the bubbling plate 51 is similar to that of the zirconium alloy cladding in the dispersed fuel element, and the thickness of the bubbling plate 51 is configured to be no more than 1 / 10 of the thickness of the heating plate 52; the conductive portion of the heating plate 52 is configured as an S32168 plate to ensure good resistance to intergranular corrosion and high-temperature strength, wherein the entire heating plate 52 can be configured as an S32168 plate; the insulating layer 53 can be formed by applying an aluminum nitride ceramic coating to the surface of the heating plate 52 using a PVD process, providing insulation. The thickness of layer 53 is 30-50 μm to ensure that it does not exceed 1 / 10 of the thickness of the blister plate 51, thereby achieving effective insulation under the operating condition of a maximum voltage of 50V in the experiment. The resistivity of the blister plate is much higher than that of the heating plate. With this setting, if the insulation layer 53 cracks during the diffusion welding process or during use, the heat generated by the blister plate 51 will not exceed 5% of the total heat generated by electrical conduction. The heat generated by the blister plate 51 has an acceptable impact on the temperature field of the vacuum bubble section, giving the experimental device a certain ability to resist abnormalities, thereby ensuring the success rate of the experiment.

[0080] In summary, the heat transfer simulation experimental apparatus provided in this application embodiment can simulate the gap thermal resistance of the bubbling region of the dispersed fuel element, the cooling boundary shape of the narrow slit channel 7, and its heat transfer conditions. It is beneficial for measuring experimental data such as the wall temperature near the vacuum bubble section, the fluid temperature field and velocity field in the narrow slit channel 7, and the visualization measurement of the boiling two-phase flow pattern in the narrow slit channel 7, thereby obtaining the flow heat transfer characteristics near the vacuum bubble section, and thus providing a reference for the study of the heat transfer characteristics of the actual dispersed fuel element in the bubble state.

[0081] The specific embodiments described above illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Although the description of this application is presented in conjunction with some embodiments, this does not mean that the features of this application are limited to this embodiment. On the contrary, the purpose of describing the application in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of this application. To provide a thorough understanding of this application, many specific details are included in the above description. This application may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this application, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0082] It should be noted that in this specification, similar reference numerals and letters in the above figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this application, it should be noted that unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0083] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A heat transfer simulation experimental apparatus for simulating the bubbling condition on the surface of a dispersed fuel element, characterized in that, include: The thermal insulation structure of the electric heating plate includes an insulation base (6), a heating plate (5), and an adhesive layer (14). The insulation base (6) is configured as a ceramicized resin plate, and a groove is formed on one surface of the insulation base (6). The heating plate (5) is placed in the groove so that the surface of the heating plate (5) is flush with the surface of the insulation base (6). A microporous alumina ceramic layer (15) treated with an active coupling agent is provided on the surface of the heating plate (5) corresponding to the groove wall and the bottom of the groove. The adhesive layer (14) is... The device is positioned between the heating plate (5) and the insulating base (6) under high temperature vacuum pressure. The heating plate (5) has a vacuum bubble-like part on the side facing away from the insulating base (6). The insulating base (6) is provided with an elastic sealing cavity (113) and is filled with heat-insulating powder (114). The insulating base (6) is also provided with a temperature measuring hole (10) corresponding to the position of the vacuum bubble-like part, so that the thermocouple can pierce the elastic sealing cavity (113) through the temperature measuring hole (10) and contact the heating plate (5). Cover (4), the cover (4) has a flow groove, the cover (4) is connected to the heat insulation base (6) so that the heat insulation base (6) seals the flow groove to form a narrow slit channel (7), and the heat receiving plate (5) is located in the narrow slit channel (7); Medium inlet (1), the medium inlet (1) is connected to one end of the narrow slit channel (7); Medium outlet (2), which is connected to the other end of the narrow slit channel (7); The conductive element (8) is connected to both ends of the heated plate (5), and the vacuum bubble is located between the two conductive elements (8).

2. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The thickness of the microporous alumina ceramic layer (15) is configured to be 10~50 μm.

3. The heat transfer simulation experimental apparatus according to claim 1 or 2, characterized in that, The aspect ratio of the micropores in the microporous alumina ceramic layer (15) is configured to be on the micrometer scale.

4. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The walls and bottom of the settling tank are configured as laser-activated surfaces.

5. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The cover (4) is sealed to the heat insulation base (6) by a static sealing ring, wherein the static sealing ring is arranged around the flow groove.

6. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The light transmittance of the cover (4) is configured to be not less than 98%.

7. The heat transfer simulation experimental apparatus according to claim 6, characterized in that, The cover (4) is configured as optical quartz glass.

8. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The conductive element (8) is connected to the heated plate (5) by silver brazing.

9. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The number of temperature measuring holes (10) is configured to be multiple, and the distance between the multiple temperature measuring holes (10) and the vacuum bubble part is no more than 10 mm from the normal viewing angle of the surface of the heated plate (5).

10. The heat transfer simulation experimental apparatus according to claim 9, characterized in that, At least one temperature measuring hole (10) corresponds to the center position of the vacuum bubble section.

11. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The heat insulation base (6) has a detachable positioning plate (11), the positioning plate (11) includes a lower baffle (112) and an upper baffle (111) embedded in the lower baffle (112), and an installation cavity suitable for accommodating the elastic sealing cavity (113) is formed between the upper baffle (111) and the lower baffle (112), and the temperature measuring hole (10) is located on the positioning plate (11); wherein, the positioning plate (11) corresponds to the position of the vacuum bubble part.

12. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, It also includes a pressure testing connector (13), which is connected to the narrow slit channel (7).

13. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The medium inlet (1) and / or medium outlet (2) are equipped with a temperature measuring tube (12).

14. The heat transfer simulation experimental apparatus according to claim 1 or 11, characterized in that, It also includes a first pressure block (9) and a second pressure block (3) arranged at intervals. The first pressure block (9) is connected to the second pressure block (3). The first pressure block (9) abuts against the base, and the second pressure block (3) abuts against the cover (4).

15. The heat transfer simulation experimental apparatus according to claim 1, characterized in that, The heat-receiving plate (5) includes: Bubble plate (51), the bubble plate (51) having grooves formed by a casting process; Heating plate (52), the heating plate (52) and the bubbling plate (51) are arranged in parallel and spaced apart; An insulating layer (53) is located between the bubbling plate (51) and the heating plate (52). The insulating layer (53) is connected to the heating plate (52). The insulating layer (53) and the bubbling plate (51) are connected by vacuum diffusion welding to form a vacuum bubble with the groove on the bubbling plate (51).

Images