Experimental apparatus for a nuclear reactor thermal fluid

Abstract

The application discloses an experimental device for simulating a nuclear reactor thermal fluid, comprising: a water supply system, which controls the water flow into the gas-liquid mixing cavity at a fixed flow rate; a gas supply system, which controls the air flow into the gas-liquid mixing cavity at a fixed flow rate; and an experimental system, which comprises an experimental pipeline and an electric current control system, wherein the air and water in the gas-liquid mixing cavity flow through the experimental pipeline, and the electric current control system heats different parts of the experimental pipeline according to a first heat distribution scheme, so as to simulate the nuclear heat coupling reaction of a single channel of a nuclear reactor. The experimental device disclosed in the application can effectively simulate the thermal fluid phenomenon in the nuclear reactor by heating the experimental section pipeline in different ways. Moreover, the data extracted from the experimental device is more accurate, and the heat distribution research of the nuclear reactor is more accurate. The experimental device is simple to operate, and can be adjusted in real time according to actual conditions, so as to simulate various phenomena in the actual nuclear reaction process.

Description

Technical Field

[0001] This invention relates to the field of thermal fluid experimental apparatus, specifically to an experimental apparatus for thermal fluids in a nuclear reactor simulation. Background Technology

[0002] Nuclear reactor thermal fluid phenomena refer to all phenomena involving fluid flow and heat transfer processes that are widely present in nuclear engineering, such as the flow and heat transfer of coolant in the reactor core, phase change flow in the steam generator, phase change heat release in the condenser, and evaporation and condensation in the pressurizer.

[0003] During nuclear reactor operation, the heat source is the enormous energy released during neutron fission, which accompanies the production of neutrons. Subchannels in the reactor core refer to the division of the reactor core into several small regions according to certain rules. Each small region has essentially the same characteristics and parameters, allowing for independent simulation and calculation. Generally, subchannels can be divided into three dimensions: radial, circumferential, and axial. Inside the reactor core, due to uneven heat generation and difficulty in controlling coolant flow, local reactor parameters are difficult to measure or calculate directly. However, by establishing core subchannels, the thermal-hydraulic parameters of each small region can be accurately calculated and evaluated, leading to better reactor design, optimized coolant flow, and improved reactor performance and safety. The cross-section of the subchannel varies depending on the arrangement of the fuel elements in the core, and the fluid flowing within the subchannel is the coolant.

[0004] When the core temperature changes, the neutron energy spectrum and microscopic cross-section also change accordingly. Therefore, when coolant flows through the subchannels, it carries away the heat generated by the core fuel elements. This causes a change in the core temperature, leading to changes in the neutron energy spectrum and microscopic cross-section, which in turn changes the heat generated by the core fuel elements. Consequently, the temperature of the subchannel walls also changes, altering the amount of heat carried away by the coolant flow, resulting in a new change in the core temperature. This is the nuclear-thermal coupling phenomenon, also known as a nuclear reactor thermal-fluid phenomenon. Thermal coupling occurs continuously within the reactor core.

[0005] Therefore, the distribution of neutron flux in the reactor core is not constant. Generally speaking, the radial distribution follows a Bessel function, and the axial distribution follows a cosine function, which also reflects the heat distribution within the reactor core.

[0006] In experimental setups studying thermal fluids, the heat source applied to the experimental tube section is typically uniformly distributed. This leads to significant differences between the experimental results of the fluid heating process and those obtained in the cooling tubes of a nuclear reactor. Consequently, it affects the study of coolant flow pressure drop and flow instability in nuclear reactors. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an experimental apparatus for simulating the thermal fluid of a nuclear reactor, comprising: a water supply system for controlling the flow of water at a fixed velocity into a gas-liquid mixing chamber; an air supply system for controlling the flow of air at a fixed velocity into the gas-liquid mixing chamber; and an experimental system comprising an experimental pipeline and a current control system, wherein the air and water in the gas-liquid mixing chamber flow through the experimental pipeline, and the current control system heats different parts of the experimental pipeline according to a first heat distribution scheme to simulate the nuclear thermal coupling reaction of a single channel of a nuclear reactor.

[0008] Furthermore, the current control system includes: multiple thermocouples, one end of which is connected to the experimental pipe and the other end of which is connected to a data processor, for measuring the wall temperature at different locations of the experimental pipe; the data processor for recording and processing the temperature electrical signals at multiple wall temperatures to form a temperature electrical signal distribution; and a current controller for receiving the temperature electrical signal distribution, calculating the corresponding current value, and heating the experimental pipe by controlling the current flowing through it, thereby realizing the nuclear thermal coupling reaction of a single channel in a simulated nuclear reactor.

[0009] Furthermore, the first heat distribution scheme is as follows: a metal wire is wound around the experimental pipe, and the current control system is connected to both ends of the metal wire. The experimental pipe is heated by the resistance heat generated by the energization of the metal wire.

[0010] Furthermore, the metal wires wound in the middle section of the experimental pipe are more densely packed than those wound at both ends.

[0011] Furthermore, the calculation method for the density of the metal wires in the experimental pipe is as follows: the formula for the heat release rate y of the axial metal wire and the axial height t is y(t)=cos(t), where t∈[-n, n]; taking the height t values ​​with equal intervals, the corresponding heat release rate y values ​​are calculated respectively; according to the formula...

[0012] Y = (y max -y i ) / (y max -y min ), calculate the density value of the above metal wires, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different parts.

[0013] Furthermore, the first heat distribution scheme is as follows: the experimental pipe includes a pipe wall and a cavity, the pipe wall encloses the cavity, the pipe wall material is metal, and the current control system is connected to both ends of the pipe wall. The air and water in the cavity are heated by the resistance heat generated by the energization of the pipe wall.

[0014] Furthermore, the thickness of the middle section of the pipe wall is greater than that of the two ends of the pipe wall.

[0015] Furthermore, the calculation method for the thickness of the experimental pipe is as follows: the formula for the heat release rate y of the axial metal wire and the axial height t is y(t)=cos(t), where t∈[-m, m]; taking the height t values ​​at equal intervals, calculate the corresponding heat release rate y values ​​respectively; according to the formula Y=(y max -y i ) / (y max -y min ), calculate the thickness of the experimental pipe mentioned above, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different parts.

[0016] Furthermore, the aforementioned current control system also includes an adjustable resistor connected between the aforementioned current controller and the aforementioned experimental pipeline, used to assist the aforementioned current controller in adjusting the current value in the control loop.

[0017] Furthermore, the experimental system also includes: a high-speed camera to capture visual images of the experimental pipe; an electrical probe to detect the cavitation fraction or voltage signal at different locations within the experimental pipe; a pressure sensor to measure the pressure within the experimental pipe; and a differential pressure transmitter to measure the differential pressure within the experimental pipe. Based on the visual images, the cavitation fraction or voltage signal, the internal pressure, and the differential pressure, the system records and plots the flow distribution within the experimental pipe to assist in simulating the state of nuclear thermal coupling reactions within a single channel.

[0018] The experimental apparatus disclosed in this application can effectively simulate the thermal fluid phenomena in a nuclear reactor by heating the test section of the pipeline in different ways. Furthermore, because the data extracted by the experimental apparatus is more accurate, the study of the heat distribution in the nuclear reactor is more precise. This experimental apparatus is simple to operate and can be adjusted in real time according to actual conditions to simulate various phenomena in the actual nuclear reaction process.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] Figure 1 A schematic diagram of the experimental apparatus for the thermal fluid of a nuclear reactor as provided in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a current control system provided in an embodiment of the present invention;

[0022] Figure 3A cross-sectional view and a perspective view of the metal wire winding experimental pipe provided in an embodiment of the present invention;

[0023] Figure 4 The graph showing the relationship between the wire density Y and the axial height t, and the corresponding three-dimensional view of the experimental pipe provided in the embodiments of the present invention;

[0024] Figure 5 Cross-sectional and perspective views of the outer walls of experimental pipes of different thicknesses provided in embodiments of the present invention;

[0025] Figure 6 The diagram showing the relationship between the metal wall thickness Y' and the axial height t' provided in the embodiments of the present invention, and the corresponding three-dimensional view of the experimental pipeline. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and examples, so as to better understand the solution of the present invention and its advantages in various aspects. However, the specific embodiments and examples described below are for illustrative purposes only and are not intended to limit the present invention.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention 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 of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0030] This application provides an experimental apparatus for a nuclear reactor-like thermal fluid, which includes a water supply system, a gas supply system, and an experimental system.

[0031] The water supply system controls the flow of water from the storage tank into the gas-liquid mixing chamber at a fixed flow rate through the water pipe. The air supply system controls the flow of air into the gas-liquid mixing chamber at a fixed flow rate.

[0032] The experimental system includes an experimental pipeline and a current control system. Air and water in the gas-liquid mixing chamber flow through the experimental pipeline. The current control system heats different parts of the experimental pipeline according to a first heat distribution scheme to simulate the nuclear thermal coupling reaction of a single channel of a nuclear reactor.

[0033] Figure 1 This is a schematic diagram of an experimental setup for a simulated nuclear reactor thermal fluid disclosed in this application. Figure 1 As shown, the water supply system in this application includes a water storage tank 1, a circulation pump 5, water flow pipes 2, multiple water valves 4, and a gas-liquid mixing chamber 3. One end of the water flow pipe is connected to the water storage tank 1, and the other end is connected to the gas-liquid mixing chamber 3. The circulation pump 5 and water valves 4 are installed between the water flow pipes 2. The circulation pump 5 and water valves 4 control the water in the water storage tank 1 to enter the water flow pipes 2 at a fixed flow rate and then flow into the gas-liquid mixing chamber 3. After entering the experimental system, the water finally circulates back to the water storage tank 1. Multiple water valves 4 and circulation pumps 5 are also provided between the water flow pipes 2 to control the water flow rate. This embodiment also includes a water flow filter 6 to remove impurities from the water flow. It is worth noting that, at the end of the water flow pipe before entering the gas-liquid mixing chamber 3, a dual-channel water flow is provided, with a water valve 4 and a liquid flow meter 7 installed on each channel. This arrangement allows for water flow diversion. By observing the flow rate on the liquid flow meter 4, the water valves on each channel can be controlled to further refine the flow rate, ensuring that water from the storage tank enters the water flow pipe at the required fixed flow rate. The liquid flow meter used in this application is an electromagnetic flow meter; there are no restrictions on the type or application of the flow meter.

[0034] The air supply system in this embodiment includes an air compressor a, an air pressure tank c, an airflow duct b, and multiple air valves g. One end of the airflow duct b is connected to the air compressor a, and the other end is connected to the gas-liquid mixing chamber 3. The air pressure tank c and the air valves g are installed between the airflow duct b. The air generated by the air compressor a, after being controlled by the air pressure tank c and the air valves g, enters the gas-liquid mixing chamber 3 at a fixed flow rate. An air pressure tank c, a drying chamber d, and an air filter e are also sequentially installed on the airflow duct b. The air generated by the air compressor a is pressurized by the air pressure tank c and then further dried and filtered. Before entering the gas-liquid mixing chamber 3, this embodiment divides the airflow duct b into three channels b1, b2, and b3. Each airflow channel is equipped with an air flow meter f and an air valve g. By observing the flow rate on the air flow meter f, the air valves on each channel are controlled to further control the airflow rate, ensuring that the air enters the airflow channel at a fixed flow rate. The air flow meter used in this application is a Coriolis flow meter, and this is not a limitation.

[0035] It should be noted that before entering the experimental pipeline, this application also provides a gas-liquid mixing chamber 3 to ensure that air and water are fully mixed.

[0036] The current control system in this application is as follows: Figure 2 The system includes multiple thermocouples ①, a data processor ②, and a current controller ④. The current controller ④ forms a loop with the experimental pipeline ⑤. One end of each thermocouple ① is connected to the experimental pipeline, and the other end is connected to the data processor ②, used to measure the wall temperature at different locations on the experimental pipeline. The data processor ② records and processes the temperature signals from the multiple wall temperatures to form a temperature signal distribution. The current controller ④ receives the temperature signal distribution, calculates the corresponding current value, and heats the experimental pipeline by controlling the current flowing through it, thereby realizing a nuclear thermal coupling reaction in a single channel of a simulated nuclear reactor.

[0037] The current control system in this embodiment may also include a variable resistor ③ to facilitate adjustment of the heating temperature of the experimental pipe.

[0038] like Figure 1 As shown, the experimental system can also be equipped with a high-speed camera A, an electrical probe B, a pressure sensor, and a differential pressure sensor. The high-speed camera captures visual images of the experimental pipe, the electrical probe detects the cavitation fraction or voltage signal at different locations within the experimental pipe, the pressure sensor measures the pressure within the experimental pipe, and the differential pressure transmitter measures the differential pressure within the experimental pipe.

[0039] Based on the visualization images, cavitation fraction, voltage signal, internal pressure and internal pressure difference of the pipe, the flow distribution inside the experimental pipe is recorded and plotted to help simulate the state of nuclear thermal coupling reaction in a single channel.

[0040] In this embodiment, the high-speed camera A and the circuit probe B of the experimental system are installed on the side of the experimental pipe C, and the pressure sensor and the differential pressure transmitter (not shown in the figure) are directly installed on the experimental pipe.

[0041] Figure 3 The cross-sectional view and perspective view of the metal wire winding experimental pipe provided in the embodiments of the present invention are as follows: Figure 3 As shown, the first heat distribution scheme adopted in this application involves winding a metal wire F around the experimental pipe C and energizing both ends of the wire. The resistive heat generated when the metal wire F is energized heats the experimental pipe C. Furthermore, the metal wire wound in the middle section of the experimental pipe is denser than that wound at both ends. This is because in a nuclear reactor, the heat source comes from the large energy released during nuclear fission. In the reactor core, the neutron flux distribution along the axial direction is a cosine function distribution, meaning the heat release rate along the z-axis of the reactor core follows a cosine function distribution, as shown in the formula:

[0042]

[0043] Where r is the radial position of the fuel element, and H e It is the extrapolated height. Therefore, when the extrapolated height H... e The larger the diameter, the smaller the neutron flux. Therefore, in simulating nuclear thermal coupling in a nuclear reactor, the metal wires in the middle section are more densely wound, while those at both ends are sparser. From an axial perspective, the heat release rate of the tube wall exhibits a cosine function distribution.

[0044] The heat release rate formula can then be simplified to a function y(t) = cos(t) in the axial direction, where the axial height t ∈ [-n, n] is set; and the corresponding heat release rate y is calculated by taking equally spaced height t values.

[0045] Then according to the formula Y = (y max -y i ) / (y max -y min ), calculate the density value of the metal wire, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different locations. For example, the heat release rate at the midpoint 0 is set to 1, where H ∈ [-2z, 2z], corresponding to... First, take one point at equal intervals (t) and calculate the corresponding heat release rate y values: y = 0.2, 0.4, 0.56, 0.7, 0.83, 0.92, 0.98, 1, 0.98, 0.92, 0.83, 0.7, 0.56, 0.4, 0.2. The following function calculates the importance of each y value, and the density of the wire winding at different locations is determined based on the magnitude of the y value:

[0046] Y = (y max -y i ) / (y max -y min )

[0047] The calculated values ​​are Y = 1, 0.78, 0.61, 0.44, 0.22, 0.11, 0.02, 0, 0.02, 0.11, 0.22, 0.44, 0.61, 0.77, 1. The wire density curve is obtained by plotting the wire density Y against the extrapolated function t, as shown below. Figure 3 As shown, the metal wire forms a cosine function from the center of the axis outwards to both sides.

[0048] Figure 5 Cross-sectional views and perspective views of the outer walls of experimental pipes of different thicknesses provided for embodiments of the present invention. Figure 5 As shown. The first heat distribution scheme of this application can also be achieved by using different metal pipe wall thicknesses. The experimental pipe C includes a pipe wall C1 and a cavity C2. The pipe wall C1 encloses the cavity C2, which contains a uniformly mixed air and water. By passing electricity through both ends of the metal pipe wall, the pipe wall generates resistance heat to heat the air and water in the cavity. Similarly, depending on the actual situation, the pipe wall can be thicker at higher temperature locations and thinner at lower heat source locations. Therefore, in this application, the thickness of the middle section of the pipe wall is set to be thicker than that of the two ends of the pipe wall.

[0049] The calculation method for the thickness of the experimental pipe is similar to that for the density of the metal wires: the formula for the heat release rate y of the axial metal pipe and the axial height t is y(t)=cos(t), where t∈[-m,m]; taking the height t values ​​at equal intervals, calculate the corresponding heat release rate y values ​​respectively; according to the formula...

[0050] Y = (y max -y i ) / (y max -y min ), calculate the thickness value of the experimental pipe, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different parts.

[0051] For example, let the heat release rate be distributed as a function y(t) = 0.02·cos(0.02·π·t) along the z-axis, where t∈[-25, 25]. When setting the thickness of the metal tube wall at different locations, the function curve (with t=0 as half a period of the central axis) is compared with... x The area enclosed by the axis is set as the metal wall thickness of the sub-channel, and Y = (y max -y i ) / (ymax -y min ), calculate the thickness value of the experimental pipe. From the front view, the function curve is the outline of the outermost wall of the metal, such as Figure 6 As shown.

[0052] Obviously, the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An experimental apparatus for simulating the thermal fluid of a nuclear reactor, comprising: The water supply system controls the flow of water at a fixed velocity into the air-liquid mixing chamber; An air supply system controls the flow of air at a fixed velocity into the gas-liquid mixing chamber; The experimental system includes an experimental pipeline and a current control system. Air and water in the gas-liquid mixing chamber flow through the experimental pipeline. The current control system heats different parts of the experimental pipeline according to a first heat distribution scheme to simulate the nuclear thermal coupling reaction of a single channel of a nuclear reactor. The first heat distribution scheme is as follows: a metal wire is wound around the experimental pipe, and the current control system is connected to both ends of the metal wire. The experimental pipe is heated by the resistance heat generated by the energization of the metal wire. The metal wires wound in the middle section of the experimental pipe are denser than those wound at both ends, and the method for calculating the density of the metal wires in the experimental pipe is as follows: The formula for the heat release rate y of the axial metal wire and its axial height t is as follows: , where settings ; Take equal-interval height t values ​​and calculate the corresponding heat release rate y values ​​respectively; According to the formula Calculate the density value of the metal wire, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different parts.

2. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 1, characterized in that, The current control system includes: Multiple thermocouples, one end of which is connected to the experimental pipe and the other end of which is connected to a data processor, are used to measure the wall temperature at different locations in the experimental pipe. A data processor is used to record and process temperature electrical signals at multiple wall surface temperatures to form a temperature electrical signal distribution; The current controller receives the temperature electrical signal distribution, calculates the corresponding current value, and heats the experimental pipe by controlling the current flowing through it, thereby realizing the nuclear thermal coupling reaction in a single channel of a simulated nuclear reactor.

3. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 2, characterized in that, The first heat distribution scheme is as follows: the experimental pipe includes a pipe wall and a cavity, the pipe wall surrounds the cavity, the pipe wall material is metal, and the current control system is connected to both ends of the pipe wall. The air and water in the cavity are heated by the resistance heat generated by the energization of the pipe wall.

4. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 3, characterized in that, The thickness of the middle section of the pipe wall is greater than that of the two ends of the pipe wall.

5. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 4, characterized in that, The method for calculating the thickness of the experimental pipe is as follows: The formula for the heat release rate y of the axial metal wire and its axial height t is as follows: Among the settings ; Take equal-interval height t values ​​and calculate the corresponding heat release rate y values ​​respectively; According to the formula Calculate the thickness value of the experimental pipe, where y max y represents the maximum heat release rate. min For the minimum heat release rate, y i These represent the heat release rate values ​​for different parts.

6. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 2, characterized in that, The current control system also includes an adjustable resistor connected between the current controller and the experimental pipeline to assist the current controller in adjusting the current value in the control loop.

7. The experimental apparatus for the thermal fluid of a simulated nuclear reactor as described in claim 1, characterized in that, The experimental system also includes: A high-speed camera was used to capture visual images of the experimental pipe. An electrical probe is used to detect the cavitation fraction or voltage signal at different locations within the experimental pipe. A pressure sensor measures the pressure inside the experimental pipe. A differential pressure transmitter is used to measure the differential pressure inside the experimental pipeline; Based on the visualization image, the cavitation fraction or the voltage signal, the internal pressure and the internal pressure difference, the flow distribution in the experimental pipeline is recorded and plotted to help simulate the state of nuclear thermal coupling reaction in a single channel.

Images