Experimental system for testing petal-shaped fuel element

Abstract

The invention relates to the field of fuel element thermal hydraulic experiments, and discloses an experimental system for testing a petal-shaped fuel element, the experimental system comprises a petal-shaped fuel element, an element container, a liquid supply unit, an electric heating device and a temperature detection device, a spiral arc-shaped convex surface and a spiral arc-shaped concave surface are formed on the peripheral wall of the petal-shaped fuel element; the element container is used for accommodating petal-shaped fuel elements; the liquid supply unit is used for conveying test liquid to the element container; the electric heating device is electrically connected with the petal-shaped fuel element and is used for heating the petal-shaped fuel element, so that the test liquid can reach a boiling critical point; the temperature detection device comprises a first temperature measurement element and a second temperature measurement element, the first temperature measurement element is used for detecting the convex surface temperature of the arc-shaped convex surface, and the second temperature measurement element is used for detecting the concave surface temperature of the arc-shaped concave surface. The experiment system can accurately detect the critical heat flux density of the petal-shaped fuel element, and can accurately obtain the circumferential position of the boiling critical point at the same time.

Description

Technical Field

[0001] The present application belongs to the technical field of thermal hydraulic experiments on fuel elements, and in particular relates to an experimental system for testing petal-shaped fuel elements. Background Art

[0002] Petal-shaped fuel elements are a new type of fuel element that can be used in commercial pressurized water reactors, such as Figure 1 As shown in the figure, it has a unique twisted structure and has a higher heat transfer efficiency than traditional round rod-shaped fuel elements, which can greatly improve the output power of pressurized water reactors. Therefore, petal-shaped fuel elements have great development potential. As we all know, critical heat flux density is the core parameter of reactor thermal hydraulic analysis and safety design. Therefore, mastering the boiling critical characteristics of petal-shaped fuel elements is of great significance for their engineering applications.

[0003] Considering that the petal-shaped fuel element is a twisted structure, its circumferential heat flux and wall temperature are unevenly distributed. If the traditional single-phase flow heat exchange device is used to test its critical heat flux, the bubbles generated on the wall of the petal-shaped fuel element will continue to gather toward the concave surface of the wall (i.e., the leeward side) under the influence of the swirl flow field, resulting in the inability to accurately determine the circumferential position of the boiling critical point. Therefore, it is necessary to develop an experimental system suitable for petal-shaped fuel elements to provide reliable technical support for the study of the critical boiling mechanism and model development of petal-shaped fuel elements. Summary of the invention

[0004] In response to at least one of the above-mentioned defects or shortcomings of the prior art, the present application provides an experimental system for testing petal-shaped fuel elements, which can accurately detect the critical heat flux density of the petal-shaped fuel elements and determine the circumferential position of the boiling critical point, providing technical support for the research on the critical boiling mechanism and model development of petal-shaped fuel elements.

[0005] In order to achieve the above object, the present application provides an experimental system for testing petal-shaped fuel elements, comprising:

[0006] A petal-shaped fuel element, wherein the peripheral wall of the petal-shaped fuel element is formed with a spiral arc-shaped convex surface and an arc-shaped concave surface;

[0007] An element container, used for accommodating the petal-shaped fuel element;

[0008] A liquid supply unit, used for delivering a test liquid to the component container;

[0009] an electric heating device, electrically connected to the petal-shaped fuel element and used to heat the petal-shaped fuel element so that the test liquid can reach a boiling critical point; and

[0010] The temperature detection device comprises a first temperature measuring element and a second temperature measuring element, wherein the first temperature measuring element is used to detect the convex surface temperature of the arc-shaped convex surface, and the second temperature measuring element is used to detect the concave surface temperature of the arc-shaped concave surface.

[0011] In some embodiments, the electric heating device includes a power supply and two electrode rods connected to the power supply, both ends of the petal-shaped fuel element are formed with element grooves extending in the axial direction, the two electrode rods are respectively inserted into the two element grooves, the peripheral wall of the electrode rod is provided with a first electrode through hole and a second electrode through hole, the inner peripheral wall of the element groove is provided with a convex through hole penetrating to the arc-shaped convex surface and a concave through hole penetrating to the arc-shaped concave surface, the first electrode through hole is aligned and connected to the convex through hole, and the second electrode through hole is aligned and connected to the concave through hole;

[0012] The first temperature measuring element and the second temperature measuring element are respectively a first thermocouple and a second thermocouple. The first thermocouple passes through the first electrode through hole and the convex surface through hole in sequence, so that the measuring end of the first thermocouple is flush with the arc-shaped convex surface; the second thermocouple passes through the second electrode through hole and the concave surface through hole in sequence, so that the measuring end of the second thermocouple is flush with the arc-shaped concave surface.

[0013] In some embodiments, the element container includes a glass tube and two sealing sleeves, the two ends of the sealing sleeves are respectively formed as a sleeve open end and a sleeve sealed end, the two ends of the glass tube are respectively sleeved in the two sleeve open ends of the two sealing sleeves, and the two sealing sleeves and the glass tube jointly define a accommodating space for accommodating the petal-shaped fuel element; the end face of the sleeve sealing end is formed with a sleeve end face through-hole which is aligned and connected with the element groove, and the electrode rod is sequentially connected with the sleeve end face through-hole and the element groove.

[0014] In some embodiments, the inner circumferential wall of the open end of the sleeve forms a first annular groove, the inner circumferential wall of the perforated end face of the sleeve forms a second annular groove, and the element container also includes a first sealing ring arranged in the first annular groove and a second sealing ring arranged in the second annular groove.

[0015] In some embodiments, a sleeve circumferential wall perforation communicating with the accommodating space is formed through the circumferential wall of the open end of the sleeve, wherein the sleeve circumferential wall perforation of one of the sealing sleeves is formed as a liquid inlet channel, and the sleeve circumferential wall perforation of the other sealing sleeve is formed as a liquid outlet channel; the liquid supply unit includes a liquid supply output port and a liquid supply return port, the liquid supply output port is flange-connected with the liquid inlet channel, and the liquid supply return port is flange-connected with the liquid outlet channel, and the experimental system includes a first asbestos gasket and a second asbestos gasket, the first asbestos gasket is arranged between the liquid supply output port and the liquid inlet channel, and the second asbestos gasket is arranged between the liquid supply return port and the liquid outlet channel.

[0016] In some embodiments, the experimental system includes a high-speed camera disposed on one side of the glass tube, and the high-speed camera is used to photograph the end peripheral wall of the petal-shaped fuel element (1) to obtain a transient bubble image of the petal-shaped fuel element.

[0017] In some embodiments, the liquid supply unit includes a liquid pump, a frequency converter and a mass flow meter, the liquid pump is used to pump the test liquid into the element container, the frequency converter is used to control the output flow of the liquid pump, and the mass flow meter is arranged between the liquid pump and the container liquid inlet of the element container to detect the mass flow rate of the test liquid.

[0018] In some embodiments, the liquid supply unit also includes a liquid storage tank, a first preheating device and a second preheating device, the liquid storage tank is used to store the test liquid, the liquid pump is connected to the liquid outlet of the liquid storage tank by a pipeline, the first preheating device is used to heat the test liquid in the liquid storage tank, and the second preheating device is arranged between the liquid pump and the liquid inlet of the container to heat the test liquid output from the liquid storage tank.

[0019] In some embodiments, the element container includes the container liquid inlet and the container liquid outlet, the liquid supply unit also includes a cooling device for cooling the test liquid, the liquid inlet of the cooling device is connected to the container liquid outlet by a pipeline, and the liquid outlet of the cooling device is connected to the liquid inlet of the liquid storage tank by a pipeline.

[0020] In some embodiments, the electric heating device can communicate with the temperature detection device and is configured to be able to cut off power when the convex surface temperature and / or the concave surface temperature is greater than a preset critical temperature, so that the petal-shaped fuel element stops heating.

[0021] Through the above technical scheme, when the critical heat flux density of the petal-shaped fuel element is detected by using the experimental system of the present application, the petal-shaped fuel element can be set in an element container, and the test liquid is input into the element container by using the liquid supply unit so that the test liquid flows through the petal-shaped fuel element. At this time, the petal-shaped fuel element is heated by using the electric heating device so that the test liquid flowing through the petal-shaped fuel element reaches a boiling state. The key is that the convex surface temperature and the concave surface temperature of the petal-shaped fuel element can be detected in real time by using the first temperature measuring element and the second temperature measuring element. When the convex surface temperature or the concave surface temperature reaches the preset boiling critical temperature, the circumferential position (arc convex surface or arc concave surface) of the boiling critical point can be determined, and combined with the structural size of the petal-shaped fuel element and the real-time power of the electric heating device, the critical heat flux density of the petal-shaped fuel element can be accurately calculated, thereby providing technical data support for the critical boiling mechanism research and model development of the petal-shaped fuel element.

[0022] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work. In the drawings:

[0024] Figure 1 Schematic diagram of a petal-shaped fuel element in a specific embodiment of the present application, wherein FIG a is a front view of the petal-shaped fuel element, and FIG b is a cross-sectional schematic diagram of the petal-shaped fuel element;

[0025] Figure 2 A schematic diagram of an experimental system for testing petal-shaped fuel elements in a specific embodiment of the present application;

[0026] Figure 3 for Figure 2 Schematic diagram of the sealing sleeve in the experimental system;

[0027] Figure 4 for Figure 2 Schematic diagram of the experimental system in which the first thermocouple and the second thermocouple sequentially pass through the electrode rod and the petal-shaped fuel element.

[0028] Description of Reference Numerals

[0029] 1 Petal-shaped fuel element 2 Element container

[0030] 3 First temperature measuring element 4 Second temperature measuring element

[0031] 5 Power supply 6 Electrode rod

[0032] 7 First asbestos gasket 8 Second asbestos gasket

[0033] 9 High-speed camera 10 Liquid pump

[0034] 11 Frequency converter 12 Mass flow meter

[0035] 13 Liquid storage tank 14 First preheating device

[0036] 15 Second preheating device 16 Cooling device

[0037] 101 arc convex surface 102 arc concave surface

[0038] 103 Component groove 104 Convex through hole

[0039] 105 concave through hole 201 glass tube

[0040] 202 sealing sleeve 203 first sealing ring

[0041] 204 second sealing ring 301 first thermocouple

[0042] 401 Second thermocouple 2021 Sleeve open end

[0043] 2022 Sleeve sealing end 2023 Sleeve end face perforation

[0044] 2024 First annular groove 2025 Second annular groove

[0045] 2026 Liquid inlet channel 2027 Liquid outlet channel DETAILED DESCRIPTION

[0046] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0047] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0048] like Figures 1 to 4As shown, an exemplary embodiment of the present application provides an experimental system for testing a petal-shaped fuel element, the experimental system comprising a petal-shaped fuel element 1, an element container 2, a liquid supply unit, an electric heating device and a temperature detection device. The peripheral wall of the petal-shaped fuel element 1 is formed with a spiral arc convex surface 101 and an arc concave surface 102, the element container 2 is used to accommodate the petal-shaped fuel element 1, and the liquid supply unit is used to transport the test liquid to the element container 2. Since the petal-shaped fuel element 1 is a conductive element, the electric heating device is electrically connected to the petal-shaped fuel element 1, so that the petal-shaped fuel element 1 can be heated, so that the test liquid flowing through the petal-shaped fuel element 1 can reach the boiling critical point. The temperature detection device comprises a first temperature measuring element 3 and a second temperature measuring element 4, wherein the first temperature measuring element 3 is used to detect the convex surface temperature of the arc convex surface 101, and the second temperature measuring element 4 is used to detect the concave surface temperature of the arc concave surface 102.

[0049] Therefore, when the critical heat flux density of the petal-shaped fuel element 1 is detected by using the experimental system of the exemplary embodiment, the petal-shaped fuel element 1 can be set in the element container 2, and the test liquid can be input into the element container 2 by using the liquid supply unit, so that the test liquid flows through the petal-shaped fuel element 1. At this time, the petal-shaped fuel element 1 is heated by the electric heating device, so that the test liquid flowing through the petal-shaped fuel element 1 reaches a boiling state. The key is that the convex surface temperature and the concave surface temperature of the petal-shaped fuel element 1 can be detected in real time by using the first temperature measuring element 3 and the second temperature measuring element 4. When the convex surface temperature or the concave surface temperature reaches the preset boiling critical temperature, it can be determined that the boiling critical point of the petal-shaped fuel element 1 is at this point, so that the circumferential position of the boiling critical point in the petal-shaped fuel element 1 (i.e., the position of the arc convex surface or arc concave surface) can be accurately determined. In addition, combined with the structural size of the petal-shaped fuel element 1 and the real-time power of the electric heating device, the critical heat flux density of the petal-shaped fuel element 1 can be accurately calculated, so as to provide technical data support for the critical boiling mechanism research and model development of the petal-shaped fuel element.

[0050] It should be noted that, in this embodiment, the electric power of the electric heating device can be adjusted, for example, by adjusting the power supply voltage or adjusting the output current, so that the heat flux density of the petal-shaped fuel element 1 can be adjusted so that the wall temperature of the petal-shaped fuel element 1 can reach the preset boiling critical temperature.

[0051] In some embodiments, Figure 2As shown, the electric heating device includes a power supply 5 and two electrode rods 6 connected to the power supply 5. Both ends of the petal-shaped fuel element 1 are formed with element grooves 103 extending in the axial direction, and the two electrode rods 6 are respectively inserted into the two element grooves 103. In this embodiment, the power supply 5 can be a DC power supply, and accordingly, the two electrode rods 6 are respectively a positive electrode rod and a negative electrode rod, and can be copper electrodes. The two electrode rods 6 are inserted into the two element grooves 103 to form a tight connection with the petal-shaped fuel element 1, thereby ensuring stable power supply.

[0052] Furthermore, if Figure 4 As shown, thermocouples can be selected as the temperature measuring elements of the temperature detection device, specifically, the first temperature measuring element 3 and the second temperature measuring element 4 are respectively the first thermocouple 301 and the second thermocouple 401. In order to ensure that the temperature measuring end of the thermocouple can accurately detect different temperature values ​​of the peripheral wall surface of the petal-shaped fuel element 1, the first temperature measuring element 3 and the second temperature measuring element 4 are installed in an interlaced manner in this embodiment.

[0053] Specifically, Figure 4 As shown, the peripheral wall of the electrode rod 6 is provided with a first electrode through hole and a second electrode through hole (not shown in the drawings), and the inner peripheral wall of the element groove 103 is provided with a convex through hole 104 penetrating to the arc-shaped convex surface 101 and a concave through hole 105 penetrating to the arc-shaped concave surface 102, and the first electrode through hole is aligned and connected to the convex through hole 104, and the second electrode through hole is aligned and connected to the concave through hole 105. Therefore, when the first thermocouple 301 is installed, the first thermocouple 301 can pass through the first electrode through hole and the convex through hole 104 in sequence until the measuring end of the first thermocouple 301 is flush with the arc-shaped convex surface 101, so that the temperature of the arc-shaped convex surface 101 can be accurately detected. Similarly, when the second thermocouple 401 is installed, the second thermocouple 401 can pass through the second electrode through hole and the concave through hole 105 in sequence until the measuring end of the second thermocouple 401 is flush with the arc-shaped concave surface 102, so that the temperature of the arc-shaped concave surface 102 can be accurately detected.

[0054] It should be noted that the measuring ends of the first thermocouple 301 and the second thermocouple 401 can be respectively welded in the convex through hole 104 and the concave through hole 105 by low-temperature cold welding, and then polished and polished to make the measuring ends of the first thermocouple 301 and the second thermocouple 401 flush with the wall surface of the petal-shaped fuel element 1.

[0055] In some embodiments, Figure 2 and Figure 3As shown, the element container 2 includes a glass tube 201 and two sealing sleeves 202, wherein the two ends of the sealing sleeve 202 are respectively formed as a sleeve open end 2021 and a sleeve sealed end 2022, and the two ends of the glass tube 201 are respectively sleeved in the two sleeve open ends 2021 of the two sealing sleeves 202, so that the two sealing sleeves 202 and the glass tube 201 can jointly define a containing space for containing the petal-shaped fuel element 1. Through the glass tube 201, the experimenter can directly observe the bubble generation of the petal-shaped fuel element 1, so as to roughly judge the boiling state of the test liquid, which is convenient for the orderly development of the process, for example, when the bubbles are not obvious, the power of the power supply 5 can be increased in time to increase the temperature of the petal-shaped fuel element 1.

[0056] Under the above structure, in order to enable the two ends of the petal-shaped fuel element 1 to be smoothly connected to the electrode rod 6, the end face of the sleeve sealing end 2022 is formed with a sleeve end face through-hole 2023 that is aligned and connected to the element groove 103, so that the electrode rod 6 can first pass through the sleeve end face through-hole 2023 and then be inserted into the element groove 103. It is worth noting that it is necessary to ensure that the electrode rod 6 and the sleeve end face through-hole 2023 can achieve interference fit, so as to ensure that the sealing sleeve 202 has good sealing performance and prevent leakage of the test liquid. Since the two electrode rods 6 are in contact with the two sealing sleeves 202 respectively, the sealing sleeves 202 should be made of good insulating materials. At the same time, thanks to the good insulation of the glass tube 201, the two sealing sleeves 202 are also insulated, thereby improving the safety level of the element container 2.

[0057] On this basis, in order to further improve the sealing performance of the component container 2, the inner circumferential wall of the sleeve open end 2021 is formed with a first annular groove 2024, and the inner circumferential wall of the sleeve end surface perforation 2023 is formed with a second annular groove 2025. The component container 2 also includes a first sealing ring 203 arranged in the first annular groove 2024 and a second sealing ring 204 arranged in the second annular groove 2025. When the sealing sleeve 202 is sleeved on the end of the glass tube 201 through the sleeve open end 2021, the circumferential wall of the first sealing ring 203 can be tightly fitted with the circumferential wall of the end of the glass tube 201, thereby ensuring that the sleeve open end 2021 is sealed and connected with the glass tube 201 to prevent leakage of the test liquid. Similarly, when the electrode rod 6 is inserted into the sleeve end surface perforation 2023, the circumferential wall of the second sealing ring 204 can be tightly fitted with the circumferential wall of the electrode rod 6, thereby ensuring that the electrode rod 6 is tightly connected with the sealing sleeve 202 to prevent leakage of the test liquid.

[0058] Considering that the internal pressure of the element container 2 increases with the temperature of the test liquid, in order to prevent the sealing sleeve 202 from being separated from the glass tube 201 under high pressure conditions, in some embodiments, such as Figure 3As shown, a plurality of first annular grooves 2024 spaced in sequence may be provided along the axial direction of the sealing sleeve 202. Accordingly, a plurality of first sealing rings 203 are provided and filled in the plurality of first annular grooves 2024, respectively, so that the friction coefficient between the sealing sleeve 202 and the first sealing rings 203 is increased, and the plurality of first sealing rings 203 play a role of multi-layer protection, which can further improve the sealing performance of the sealing sleeve 202. Similarly, the sleeve end surface through hole 2023 may be provided with a plurality of second annular grooves 2025 to provide a plurality of second sealing rings 204, thereby increasing the total friction between the electrode rod 6 and the second sealing ring 204, and improving the sealing performance of the sealing sleeve 202.

[0059] In some embodiments, a sleeve peripheral wall perforation communicating with the above-mentioned accommodating space is formed through the peripheral wall of the sleeve open end 2021. Among the two sealing sleeves 202, the sleeve peripheral wall perforation of one sealing sleeve 202 is formed as a liquid inlet channel 2026 for inputting the test liquid, and the sleeve peripheral wall perforation of the other sealing sleeve 202 is formed as a liquid outlet channel 2027 for outputting the test liquid.

[0060] Furthermore, the liquid supply unit includes a liquid supply outlet and a liquid supply return outlet, the liquid supply outlet forms a flange connection with the liquid inlet channel 2026, and the liquid supply return outlet forms a flange connection with the liquid outlet channel 2027, thereby ensuring that the liquid supply unit is stably connected to the component container 2. In addition, the experimental system of this embodiment also includes a first asbestos gasket 7 and a second asbestos gasket 8, the first asbestos gasket 7 is arranged between the liquid supply outlet and the liquid inlet channel 2026, and the second asbestos gasket 8 is arranged between the liquid supply return outlet and the liquid outlet channel 2027. Since the first asbestos gasket 7 and the second asbestos gasket 8 are both good insulating materials, the liquid supply unit and the component container 2 are kept insulated, thereby improving the safety of the system.

[0061] In some embodiments, Figure 1 As shown, the experimental system includes a high-speed camera 9, which is used to photograph the peripheral wall of the petal-shaped fuel element 1, so as to obtain a transient bubble image of the petal-shaped fuel element 1. Preferably, considering that the temperature of the test liquid is the highest when it flows to the downstream position in the glass tube 201, and theoretically reaches the boiling critical point the fastest, for this reason, observing the bubble generation situation of the peripheral wall of the petal-shaped fuel element 1 located at the downstream position of the glass tube 201 is of the greatest reference value. Therefore, the high-speed camera 9 can be set outside the downstream position of the glass tube 201, so as to photograph the peripheral wall of the end of the petal-shaped fuel element 1 close to the liquid outlet flow channel 2027, and at the moment when the petal-shaped fuel element 1 is heated to reach the critical heat flux density, the transient bubble image at that moment can be accurately obtained, which is helpful to provide a clear phase field distribution image for the study of boiling critical mechanism.

[0062] In some embodiments, Figure 1As shown, the liquid supply unit includes a liquid pump 10, a frequency converter 11 and a mass flow meter 12. The liquid pump 10 is used to pump the test liquid into the component container 2. The frequency converter 11 is used to control the output flow of the liquid pump 10, thereby being able to control the mass flow rate of the test liquid flowing through the component container 2. The mass flow meter 12 is arranged between the liquid pump 10 and the container liquid inlet of the component container 2, thereby being able to detect the mass flow rate of the test liquid in real time.

[0063] Furthermore, the liquid supply unit further comprises a liquid storage tank 13, a first preheating device 14 and a second preheating device 15. The liquid storage tank 13 is used to store the test liquid. Preferably, deionized water can be used as the test liquid, and the liquid storage tank 13 is a deionized water tank. The liquid pump 10 is connected to the liquid outlet of the liquid storage tank 13 by a pipeline, so that the test liquid can be pumped to the component container 2 continuously. The first preheating device 14 is used to heat the test liquid in the liquid storage tank 13, and the second preheating device 15 is arranged between the liquid pump 10 and the liquid inlet of the container to heat the test liquid output from the liquid storage tank 13. For example, an electric heater can be used as the first preheating device 14 and arranged at the bottom of the liquid storage tank 13, so that the temperature of the test liquid in the liquid storage tank 13 can be adjusted. The second preheating device 15 may include an infusion tube and an electric heating device, and the test liquid flowing through the infusion tube is heated by the electric heating device, so that the enthalpy value of the test liquid flowing into the component container 2 can be adjusted.

[0064] The enthalpy of the test liquid flowing into the element container 2 can be calculated by the following relationship:

[0065]

[0066] Among them, h exp,in h is the enthalpy of the test liquid at the outlet of the second preheating device 15; in is the enthalpy value of the test liquid in the liquid storage tank 13 , which can be obtained by looking up a table; W is the mass flow rate of the test liquid; and P is the power of the second preheating device 15 .

[0067] In some embodiments, the liquid supply unit further includes a cooling device 16 for cooling the test liquid, the liquid inlet of the cooling device 16 is connected to the liquid outlet of the component container by a pipeline, and the liquid outlet of the cooling device 16 is connected to the liquid inlet of the liquid storage tank 13 by a pipeline, so that the test liquid flowing out of the component container 2 can be cooled and then flow back into the liquid storage tank 13. Specifically, the cooling device 16 may include a cooling water tank and a cooling disc, and the test liquid flowing into the cooling water tank is cooled by the cooling disc, so that the enthalpy value of the test liquid flowing back to the liquid storage tank 13 can be adjusted.

[0068] In some embodiments, the electric heating device can communicate with the temperature detection device, and is configured to be able to cut off the power when the convex surface temperature and / or the concave surface temperature is greater than a preset critical temperature, so that the petal-shaped fuel element 1 stops heating. Specifically, the electric heating device can be provided with a controller that communicates with the temperature detection device, and the controller is preset with a preset critical temperature. When the convex surface temperature and / or the concave surface temperature received by the controller is greater than the preset critical temperature, the power supply of the electric heating device can be controlled to stop supplying power to the petal-shaped fuel element 1, so that the petal-shaped fuel element 1 stops heating to prevent the temperature from being too high.

[0069] It should be noted that when the preset critical temperature is reached, the wall of the petal-shaped fuel element 1 will appear to be in a burnt state. At this time, it can be determined that the position is the boiling critical point of the petal-shaped fuel element 1. In order to do this, by maintaining communication between the electric heating device and the temperature detection device, the electric heating device can be powered off in time before the petal-shaped fuel element 1 burns, thereby protecting the petal-shaped fuel element 1, making it safer, and making it reusable.

[0070] It can be understood that the experimental system of the present application may include a computer, which can communicate with the detection devices in the above-mentioned embodiments, for example, communicate with the first temperature measuring element and the second temperature measuring element, so as to obtain and analyze the convex surface temperature and the concave surface temperature; communicate with the electric heating device, so as to obtain the power of the electric heating device and automatically adjust the power; communicate with the high-speed camera 9, so as to obtain the transient bubble image, and analyze the transient bubble image to obtain information such as the bubble density, size and distribution position; communicate with the mass flow meter 12, so as to obtain the mass flow rate of the test liquid.

[0071] In summary of the above-mentioned multiple embodiments, the experimental system of the present application innovatively designs an element container 2 for accommodating a petal-shaped fuel element 1 as a test section for the experiment. A multi-channel sealing structure and an insulating structure are used between the element container 2 and the liquid supply device, so that the experimental system of the present application has a high safety, and the temperature detection device can provide real-time feedback of the wall temperature of the petal-shaped fuel element 1 to the electric heating device. When the wall temperature reaches a temperature greater than the preset critical temperature, the electric heating device can be powered off in time, effectively protecting the petal-shaped fuel element 1 from damage. Most importantly, the experimental system of the present application can measure the wall temperature of the petal-shaped fuel element 1 at different circumferential positions by embedding multiple thermocouples inside the petal-shaped fuel element 1, so as to accurately determine the circumferential position of the boiling critical point of the petal-shaped fuel element 1.

[0072] Reference Figure 2 The functions of the experimental system for testing petal-shaped fuel elements of the present application can be realized by the following steps:

[0073] Step S1: Preparation and inspection before boiling critical test. First, clean the liquid supply unit and check whether there is leakage in the pipeline of the liquid supply unit. Turn on the computer and check whether the data acquisition system and the high-speed camera 9 are working normally.

[0074] Step S2: exhaust all the non-condensable gases in the liquid storage tank 13 and the pipeline of the liquid supply unit through the degasser; turn on the liquid pump 10, and adjust the mass flow rate of the test liquid in the pipeline through the frequency converter 11; adjust the power of the first preheating device 14 to keep the temperature of the test liquid in the liquid storage tank 13 within a certain range; adjust the power of the second preheating device 15 to adjust the enthalpy value of the test liquid flowing into the component container 2 to a specified range; turn on the power supply 5 to heat the test liquid in the component container 2; adjust the mass flow rate of the test liquid flowing into the cooling device to ensure that the test liquid flowing out of the component container 2 is fully cooled.

[0075] Step S3: adjusting the output power of the power supply 5, thereby adjusting the heat flux density of the petal-shaped fuel element 1 to a certain range, recording the mass flow rate of the test liquid in the pipeline, the fluid temperature of the liquid outlet flow channel 2027, the fluid pressure at the inlet and outlet of the element container 2 and the wall temperature of the petal-shaped fuel element 1 through the data acquisition system, and photographing the transient bubble distribution image at the end of the heating section of the petal-shaped fuel element 1 through the high-speed camera 9; increasing the heat flux density of the petal-shaped fuel element 1, recording the test data and photographing the bubble image; repeating the test until the wall temperature of the petal-shaped fuel element 1 exceeds 400 degrees Celsius, the power supply 5 is automatically disconnected, and the heat flux density of the petal-shaped fuel element 1 before the power supply 5 is disconnected is used as the critical heat flux density of the petal-shaped fuel element 1; comparing the wall temperatures of the petal-shaped fuel element 1 at different circumferential positions to determine the circumferential position of the boiling critical point of the petal-shaped fuel element 1;

[0076] Step S4: Repeat test steps S2 and S3 to obtain the critical heat flux density, circumferential position of the boiling critical point and corresponding transient bubble distribution image of the petal-shaped fuel element 1 under different mass flow rates and inlet enthalpy values.

[0077] Step S5: Correct the optical distortion of the captured image. Since there is a certain difference in the refractive index between the glass tube 201 and the test liquid, the actual distance L between the image point corresponding to the high-speed camera and the center point of the quartz glass tube can be corrected by the following relationship:

[0078]

[0079] n0=arcsin(L' / R o );

[0080] n1=arcsin((L' / R o )×u0 / u1);

[0081] Ω=π / 2-n1+n0;

[0082]

[0083] In the formula, R i is the inner diameter of the glass tube, R o is the outer diameter of the quartz glass tube, u o and u1 are the refractive indices of air and glass respectively.

[0084] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0085] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An experimental system for testing petal-shaped fuel elements, characterized in that: include: A petal-shaped fuel element (1), wherein a peripheral wall of the petal-shaped fuel element (1) is formed with a spiral arc-shaped convex surface (101) and an arc-shaped concave surface (102); An element container (2) for accommodating the petal-shaped fuel element (1); A liquid supply unit, used for delivering a test liquid to the component container (2); An electric heating device, electrically connected to the petal-shaped fuel element (1) and used to heat the petal-shaped fuel element (1) so that the test liquid reaches a critical point capable of boiling; and The temperature detection device comprises a first temperature measuring element (3) and a second temperature measuring element (4), wherein the first temperature measuring element (3) is used to detect the convex surface temperature of the arc-shaped convex surface (101), and the second temperature measuring element (4) is used to detect the concave surface temperature of the arc-shaped concave surface (102).

2. The experimental system for testing petal-shaped fuel elements according to claim 1, characterized in that: The electric heating device comprises a power source (5) and two electrode rods (6) connected to the power source (5); both ends of the petal-shaped fuel element (1) are formed with an element groove (103) extending in the axial direction; the two electrode rods (6) are respectively inserted into the two element grooves (103); the peripheral wall of the electrode rod (6) is provided with a first electrode through hole and a second electrode through hole; the inner peripheral wall of the element groove (103) is provided with a convex through hole (104) penetrating to the arc-shaped convex surface (101) and a concave through hole (105) penetrating to the arc-shaped concave surface (102); the first electrode through hole is aligned and connected to the convex through hole (104); and the second electrode through hole is aligned and connected to the concave through hole (105); The first temperature measuring element (3) and the second temperature measuring element (4) are respectively a first thermocouple (301) and a second thermocouple (401); the first thermocouple (301) sequentially passes through the first electrode through-hole and the convex surface through-hole (104), so that a measuring end of the first thermocouple (301) is flush with the arc-shaped convex surface (101); and the second thermocouple (401) sequentially passes through the second electrode through-hole and the concave surface through-hole (105), so that a measuring end of the second thermocouple (401) is flush with the arc-shaped concave surface (102).

3. The experimental system for testing petal-shaped fuel elements according to claim 2, characterized in that: The element container (2) comprises a glass tube (201) and two sealing sleeves (202); the two ends of the sealing sleeve (202) are respectively formed as a sleeve open end (2021) and a sleeve sealed end (2022); the two ends of the glass tube (201) are respectively sleeved in the two sleeve open ends (2021) of the two sealing sleeves (202); the two sealing sleeves (202) and the glass tube (201) jointly define a storage space for storing the petal-shaped fuel element (1); the end surface of the sleeve sealed end (2022) is formed with a sleeve end surface through hole (2023) which is aligned and communicated with the element groove (103); the electrode rod (6) is sequentially inserted through the sleeve end surface through hole (2023) and the element groove (103).

4. The experimental system for testing petal-shaped fuel elements according to claim 3, characterized in that: The inner circumferential wall of the open end (2021) of the sleeve is formed with a first annular groove (2024), and the inner circumferential wall of the sleeve end face through hole (2023) is formed with a second annular groove (2025), and the element container (2) also includes a first sealing ring (203) arranged in the first annular groove (2024) and a second sealing ring (204) arranged in the second annular groove (2025).

5. The experimental system for testing petal-shaped fuel elements according to claim 3, characterized in that: The peripheral wall of the open end (2021) of the sleeve is penetrated by a sleeve peripheral wall perforation connected to the accommodating space, wherein the sleeve peripheral wall perforation of one of the sealing sleeves (202) is formed as a liquid inlet channel (2026), and the sleeve peripheral wall perforation of the other sealing sleeve (202) is formed as a liquid outlet channel (2027); the liquid supply unit comprises a liquid supply output port and a liquid supply return port, the liquid supply output port is flange-connected with the liquid inlet channel (2026), and the liquid supply return port is flange-connected with the liquid outlet channel (2027); the experimental system comprises a first asbestos gasket (7) and a second asbestos gasket (8), the first asbestos gasket (7) is arranged between the liquid supply output port and the liquid inlet channel (2026), and the second asbestos gasket (8) is arranged between the liquid supply return port and the liquid outlet channel (2027).

6. The experimental system for testing petal-shaped fuel elements according to claim 3, characterized in that: The experimental system comprises a high-speed camera (9) arranged on one side of the glass tube (201), and the high-speed camera (9) is used to photograph the end peripheral wall of the petal-shaped fuel element (1) to obtain a transient bubble image of the petal-shaped fuel element (1).

7. The experimental system for testing petal-shaped fuel elements according to claim 1, characterized in that: The liquid supply unit comprises a liquid pump (10), a frequency converter (11) and a mass flow meter (12); the liquid pump (10) is used to pump the test liquid into the element container (2); the frequency converter (11) is used to control the output flow of the liquid pump (10); and the mass flow meter (12) is arranged between the liquid pump (10) and the container liquid inlet of the element container (2) to detect the mass flow of the test liquid.

8. The experimental system for testing petal-shaped fuel elements according to claim 7, characterized in that: The liquid supply unit further comprises a liquid storage tank (13), a first preheating device (14) and a second preheating device (15); the liquid storage tank (13) is used for storing the test liquid; the liquid pump (10) is connected to the liquid outlet of the liquid storage tank (13) by a pipeline; the first preheating device (14) is used for heating the test liquid in the liquid storage tank (13); and the second preheating device (15) is arranged between the liquid pump (10) and the liquid inlet of the container to heat the test liquid output from the liquid storage tank (13).

9. The experimental system for testing petal-shaped fuel elements according to claim 8, characterized in that: The liquid supply unit also includes a cooling device (16) for cooling the test liquid, wherein the liquid inlet of the cooling device (16) is connected to the liquid outlet of the element container by a pipeline, and the liquid outlet of the cooling device (16) is connected to the liquid inlet of the liquid storage tank (13) by a pipeline.

10. The experimental system for testing petal-shaped fuel elements according to any one of claims 1 to 9, characterized in that: The electric heating device is capable of communicating with the temperature detection device and is configured to be able to cut off power when the convex surface temperature and / or the concave surface temperature is greater than a preset critical temperature, so that the petal-shaped fuel element (1) stops heating.

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