Analysis Method of Heat Transfer Process in Fin-Tube Sodium-Air Heat Exchanger

Abstract

A heat exchange process analysis method for a fin tube sodium-air heat exchanger, the method comprising: modeling the fin tube sodium-air heat exchanger to obtain a heat exchanger model; gridding the heat exchanger model to generate a grid model; selecting a calculation model and an algorithm adapted to the calculation model; and calculating the grid model using the algorithm to obtain a temperature field state and / or a flow field state of the heat exchanger; wherein modeling the fin tube sodium-air heat exchanger comprises: modeling a fin heat exchange tube bundle of the fin tube sodium-air heat exchanger, and modeling the fins of each heat exchange tube of the fin heat exchange tube bundle as an equivalent porous medium model. The heat exchange process analysis method of the heat exchanger according to the present invention simplifies the structure of the heat exchanger in the process of modeling the heat exchanger, and the modeling process can be simplified by simplifying the structure, thereby facilitating the calculation of the heat exchange process analysis.

Description

Technical Field

[0001] The invention relates to the field of nuclear technology, and in particular to a heat exchange analysis method for a cooling system of a fast reactor. Background Art

[0002] Compared with traditional pressurized water reactors, sodium-cooled fast reactors can maximize the utilization of uranium resources, so they have been more widely used. The safety and reliability of fast reactor systems are increasingly valued. Passive safety protection measures, as a key consideration of the fourth-generation nuclear technology, can effectively reduce the probability of core meltdown.

[0003] The basic principle of passive residual heat removal is natural circulation, that is, using the principles of fluid gravity, inertia, natural convection, diffusion, evaporation, condensation, etc. to remove the core residual heat in accident conditions. The setting of the passive residual heat removal system can simplify special safety facilities, reduce related equipment and components, and reduce possible malfunctions caused by human intervention, improve the human-machine relationship, and enhance the inherent safety of nuclear power plants.

[0004] In the event of power outage, damage to the three-circuit feedwater pump, earthquake or other accident conditions, the accident residual heat removal system will discharge the residual heat from the core into the atmosphere. The accident residual heat removal system is one of the most important special safety facilities for pool-type sodium-cooled fast reactors and is the main means to achieve the safety function of residual heat removal in reactors under accident conditions.

[0005] When the overall structural design of the sodium-air heat exchanger of the accident waste heat removal system has been preliminarily determined, it is necessary to further consider whether the performance of the equipment can meet the requirements, that is, it is necessary to evaluate the performance and related parameters of the sodium-air heat exchanger. Therefore, it is necessary to provide an effective method for evaluating the working performance of the sodium-air heat exchanger. Summary of the invention

[0006] In view of the above problems, the present invention is proposed to provide a heat exchange process analysis method for a fin-tube sodium-air heat exchanger that overcomes the above problems or at least partially solves the above problems.

[0007] According to one aspect of the present invention, a heat exchange process analysis method for a fin tube sodium-air heat exchanger is provided, the heat exchange process analysis method comprising the following steps:

[0008] Model the fin-tube sodium-air heat exchanger to obtain the heat exchanger model;

[0009] Meshing the heat exchanger model to generate a meshed model;

[0010] Selecting a computational model and an algorithm adapted to the computational model; and

[0011] Calculating the grid model using the algorithm to obtain the temperature field state and / or flow field state of the heat exchanger;

[0012] The modeling of the fin tube sodium-air heat exchanger includes: modeling the fin heat exchange tube bundle of the fin tube sodium-air heat exchanger, and modeling the fin of each heat exchange tube of the fin heat exchange tube bundle as an equivalent porous medium model.

[0013] The heat exchange process analysis method according to the present invention can simulate and analyze the entire heat exchange process of the heat exchanger, obtain the heat exchange power, resistance, temperature field and flow field distribution of the heat exchanger, provide a basis for the design and / or improvement of the heat exchange area of ​​the heat exchanger, and verify the heat exchange effect of the heat exchanger. The heat exchange process analysis method of the heat exchanger according to the present invention simplifies the structure of the heat exchanger in the process of modeling the heat exchanger. The simplified structure can simplify the modeling process, which is beneficial to the calculation of the heat exchange process analysis. Furthermore, the heat exchange process analysis method can also be used to determine the temperature difference between different heat exchange tubes and whether a local cold spot appears at the outlet of each heat exchange tube, providing a basis for the structural optimization of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other objects and advantages of the present invention will become apparent from the following description of the present invention with reference to the accompanying drawings, which will help to provide a comprehensive understanding of the present invention.

[0015] Figure 1 is a schematic structural diagram of a fin tube sodium-air heat exchanger according to the present invention;

[0016] Figure 2 is a flow chart of a heat exchange process analysis method for a fin tube sodium-air heat exchanger according to the present invention;

[0017] Figure 3a is an original model diagram of a heat exchange tube according to the present invention;

[0018] Figure 3b is a simplified heat exchange tube model diagram according to the present invention;

[0019] Figure 4a It is the relationship between the velocity of air flow in the lateral direction and the pressure loss and the relationship diagram;

[0020] Figure 4b It is the relationship between the velocity of air flow in the vertical direction and the pressure loss and the relationship diagram;

[0021] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiment is one embodiment of the present invention, not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0024] First, the structure of the fin tube sodium-air heat exchanger used in the heat exchange process analysis method according to the present invention is briefly described below. Figure 1 As shown, the fin tube sodium-air heat exchanger 10 includes a shell 12 defining a heat exchange space of the heat exchanger, a first collector 14 disposed at the upper part of the shell 12, a second collector 16 disposed at the lower part of the shell 12, and a fin heat exchange tube bundle 18 disposed between the first collector 14 and the second collector 16. The fin heat exchange tube bundle 18 may include a plurality of heat exchange tubes, each of which is in fluid communication with the first collector 14 and the second collector 16. A liquid sodium inlet pipeline 142 in fluid communication with the first collector 14 is disposed on the first collector 14, which is used to introduce high-temperature liquid sodium in the sodium circuit into the heat exchanger 10, and a liquid sodium outlet pipeline 162 in fluid communication with the lower collector 16 is disposed on the lower collector 16, which is used to transport the cooled liquid sodium back to the sodium circuit. The shell 12 is generally configured to be cylindrical, the first collector 14 and the second collector 16 are configured to be annular, and a plurality of outlet pipe interfaces and a plurality of inlet pipe interfaces are respectively provided on the first collector 14 and the second collector 16, so that a fin heat exchange tube bundle 18 including a plurality of heat exchange tubes is provided between the first collector 14 and the second collector 16. Here, the number of heat exchange tubes of the fin heat exchange tube bundle 18 can be determined according to the processing capacity of the heat exchanger 10, for example, a fin heat exchange tube bundle 18 including 300-500 heat exchange tubes can be provided. The first collector 14 and the second collector 16 can be fixedly supported on the inner wall of the shell 12 by the first bracket 144 and the second bracket 164, respectively. An air inlet damper 20 is provided at the bottom of the shell 12, and an air outlet damper 22 is provided at the top of the shell 12, so as to control the flow rate and flow rate of the air entering the shell 12. Furthermore, an air flow distributor 24 is provided at the axial center position of the inner cavity of the shell 12 , and the air flow entering from the inlet damper 20 can be guided by the air flow distributor 24 so that the air flow can fully contact and exchange heat with each heat exchange tube of the fin heat exchange tube bundle 18 .

[0025] During operation, the high-temperature liquid sodium in the sodium circuit enters the first collector 14 of the heat exchanger 10 through the liquid sodium inlet pipeline 142, and the high-temperature liquid sodium is distributed to each heat exchange tube of the fin heat exchange tube bundle 18 through the first collector 14, and the high-temperature liquid sodium flows along the heat exchange tube to the second collector 16. In the process of the high-temperature liquid sodium flowing along the heat exchange tube of the fin heat exchange tube bundle 18, the low-temperature air enters the interior of the shell 12 from the inlet damper 20, and flows in the direction from the inlet damper 20 to the outlet damper 22. The low-temperature air is guided by the air flow distributor 24 during the flow process to better contact with the fins of each heat exchange tube of the fin heat exchange tube bundle 18, so as to exchange heat. As a result, in the process of the high-temperature liquid sodium flowing in the heat exchange tube of the fin heat exchange tube bundle 18, the heat is transferred to the air moving in a direction substantially opposite to the flow direction of the high-temperature liquid sodium through the fins, thereby achieving the cooling of the high-temperature liquid sodium, and after being collected by the second collector 16, it flows back to the sodium circuit from the liquid sodium outlet pipeline 162. At the same time, the air after the heat exchange is discharged from the outlet damper 22 to the outside of the housing 12 in a state of high-temperature gas.

[0026] In the early stage of the design of the sodium-air heat exchanger 10, the basic structural parameters such as the pipe diameter of the fin heat exchange tube bundle 18, the number of heat exchange tubes, and the length of the heat exchange tubes have been basically determined. However, whether the equipment performance of the heat exchanger can meet the requirements, for example, whether the heat exchange power of the equipment can meet the requirements after considering the three-dimensional effect of the fluid, whether there will be local cold spots at the outlet of the heat exchange tube at the inlet damper, and whether the temperature difference between the heat exchange tube bundles will be too large, these problems will affect the heat exchange efficiency of the heat exchanger, so temperature field analysis needs to be carried out for further verification.

[0027] The present invention provides a heat exchange process analysis method for a fin tube sodium-air heat exchanger. The heat exchange process analysis method can be used to simulate and analyze the entire heat exchange process of the heat exchanger, obtain the heat exchange power, resistance, temperature field and flow field distribution of the heat exchanger, provide a basis for the design and / or improvement of the heat exchange area of ​​the heat exchanger, and verify the heat exchange effect of the heat exchanger. In addition, the heat exchange process analysis method can also be used to determine the temperature difference between different heat exchange tubes and whether a local cold spot appears at the outlet of each heat exchange tube, providing a basis for the structural optimization of the heat exchanger. Furthermore, the heat exchange process analysis method of the heat exchanger according to the present invention simplifies the structure of the heat exchanger in the process of modeling the heat exchanger. By simplifying the structure, the modeling process can be simplified, which is beneficial to the calculation of the heat exchange process analysis.

[0028] like Figure 2 FIG. 1 is a flow chart showing a heat exchange process analysis method for a fin tube sodium-air heat exchanger according to the present invention. The heat exchange process analysis method comprises the following steps:

[0029] S1. Modeling a fin-tube sodium-air heat exchanger to obtain a heat exchanger model; S2. Meshing the heat exchanger model to generate a meshed model; S3. Selecting a calculation model and an algorithm suitable for the calculation model; and, S4. Using the algorithm to calculate the meshed model to obtain a temperature field state and / or a flow field state of the heat exchanger.

[0030] Here, modeling the fin tube sodium-air heat exchanger includes: modeling the fin heat exchange tube bundle of the fin tube sodium-air heat exchanger, and modeling the fin of each heat exchange tube of the fin heat exchange tube bundle as an equivalent porous medium model.

[0031] Before performing the three-dimensional temperature field and flow field analysis calculation of the fin tube sodium-air heat exchanger, it is necessary to first define and create the geometric shape of the flow area. Creating a geometric model is the basis for computational fluid simulation analysis. Establishing a good geometric model can not only accurately reflect the physical object to be studied, but also facilitate the next step of meshing.

[0032] Therefore, the heat exchange process analysis method for the fin tube sodium-air heat exchanger according to the present invention first includes a modeling step, that is, modeling the fin tube sodium-air heat exchanger 10 to obtain a heat exchanger model, that is, a geometric model of the heat exchanger 10.

[0033] In actual production, the fin tube sodium-air heat exchanger 10 mainly includes the following components: a shell 12, a first collector 14, a second collector 16, a fin heat exchange tube bundle 18, a liquid sodium inlet pipeline 142, a liquid sodium outlet pipeline 162, an air flow distributor 24, a first bracket 144 supporting the first collector 14, a second bracket 164 supporting the second collector 16, a tube bundle bracket supporting the fin heat exchange tube bundle 18 (not shown in the drawings), an inlet damper 20, an outlet damper 22, and a sodium leakage receiving plate (not shown in the drawings). If all the above components of the heat exchanger 10 are geometrically modeled in 1:1, the workload of subsequent mesh division will be greatly increased, and the number of meshes will also increase, which will increase the difficulty of temperature field calculation. The purpose of geometric modeling of the heat exchanger here is to analyze the temperature field and flow field inside the heat exchanger. Therefore, when geometric modeling of the heat exchanger is performed, its structure can be simplified accordingly according to the flow and heat exchange characteristics of the fin tube sodium-air heat exchanger 10. Here, the geometric model of the fin tube sodium-air heat exchanger 10 can be simplified to include: a shell 12, a first collector 14 disposed at the upper part of the shell 12, a liquid sodium inlet pipeline 142 disposed on the first collector 14 and in fluid communication with the first collector 14, a second collector 16 disposed at the lower part of the shell 14, a liquid sodium outlet pipeline 162 disposed on the second collector 16 and in fluid communication with the second collector 16, a fin heat exchange tube bundle 18 disposed in fluid communication between the first collector 14 and the second collector 16, an inlet damper 20 disposed at the bottom of the shell 12, an outlet damper 22 disposed at the top of the shell 12, and an air flow distributor 24 disposed between the inlet damper 20 and the outlet damper 22 for guiding the air flow, and other components can be ignored in the modeling process. By simplifying the geometric model of the fin tube sodium-air heat exchanger 10, the modeling process can be simplified and the amount of data to be processed later can be reduced.

[0034] Further, in the heat exchange process analysis method for the fin tube sodium-air heat exchanger 10 according to the present invention, the geometric model of the heat dissipation fin of each heat exchange tube in the fin heat exchange tube bundle 18 is equivalently replaced by the geometric model of the porous medium. That is, modeling the fin tube sodium-air heat exchanger 10 may include: modeling the fin heat exchange tube bundle 18 of the fin tube sodium-air heat exchanger 10, and modeling the fin of each heat exchange tube of the fin heat exchange tube bundle 18 as an equivalent porous medium model. The volume of the fin tube sodium-air heat exchanger 10 of the sodium cold and hot reactor is usually large, with a height of about 13m and a diameter of about 6m. The size of its fin heat exchange tube is relatively small relative to the size of the entire device, the thickness of the fin is about 1mm, and the spacing between adjacent fins is about 5mm. If the fine modeling and meshing method are used, the number of grids of the fin heat exchange tube alone will be in the billions. Too many grids will seriously affect the calculation time and the calculation accuracy.

[0035] In order to solve this problem, the multi-layer spiral zigzag fins and / or annular fins of the heat exchange tube are treated as porous media, and the heat exchange tube and its surrounding parts are divided into four equivalent areas. Figure 3a As shown, the original model diagram of the heat exchange tube is shown. The heat exchange tube model 182 includes a tube wall area 1822, a liquid sodium area 1824 located inside the tube wall area 1822, a fin area 1826 located outside the tube wall area 1822, and an air area 1828 located outside the fin area 1826. Since each heat exchange tube includes multiple layers of spiral zigzag fins and / or multiple annular fins, the fin area 1826 of the heat exchange tube model 182 will include several fin models. In order to reduce the number of grids and simplify the model, the model of the heat exchange tube is simplified as follows: Figure 3b The simplified heat exchange tube model 184 shown includes, from the inside to the outside, a liquid sodium region 1844, a tube wall region 1842 of the heat exchange tube, a porous medium region 1846, and an air region 1848. Here, the fins are mainly simplified into porous media, thereby reducing the number of meshes during mesh division.

[0036] Based on the above description, according to the heat exchange process analysis method for the fin tube sodium-air heat exchanger 10 of the present invention, the model of the heat exchange tube of the fin heat exchange tube bundle 18 is set to include the tube wall model of the heat exchange tube, the liquid sodium model located inside the tube wall model, the porous medium model located outside the tube wall model, and the air model located outside the porous medium model. By simplifying the model of the heat exchange fins of the heat exchange tubes of the fin heat exchange tube bundle 18 to a porous medium model, the number of grids of the heat exchange fins can be greatly reduced, which is convenient for subsequent simulation and analysis of the heat exchange tube model.

[0037] The simplified heat exchanger model is then meshed to generate a meshed model. The geometric model of the fin tube sodium-air heat exchanger 10 is divided into small meshes by meshing, which is convenient for subsequent computer processing of the geometric model. Meshing the heat exchanger model may include using polyhedral meshes to divide the heat exchanger model to obtain a plurality of polyhedral models, and merging the plurality of polyhedral models according to the computational domain. Merging the plurality of polyhedral models according to the computational domain may include: performing Boolean operations on a plurality of polyhedral models belonging to the same computational domain; and merging the plurality of polyhedral models into a composite polyhedral model according to the Boolean operations.

[0038] Considering that the geometric model of the heat exchanger 10 has a complex internal structure, the model of the heat exchanger 10 is meshed by polyhedral meshes according to the computational domain, and multiple polyhedral meshes belonging to the same computational domain are subjected to Boolean operations to merge them into a polyhedral mesh model, thereby facilitating the selection and setting of boundary conditions. After all the polyhedral meshes that can be merged are merged, the merged polyhedral mesh geometry can be named according to the computational domain. For example, in the process of polyhedral meshing of a heat exchange tube, since the heat exchange tube has a long length, it is possible to divide the same heat exchange tube into multiple meshes. At this time, multiple meshes of the same heat exchange tube can be merged into the same polyhedral mesh through Boolean operations, thereby facilitating subsequent processing or calculation of the model.

[0039] Using a polyhedral mesh to divide a heat exchanger model may include the following steps: first, performing surface mesh processing on the heat exchanger model to obtain a surface mesh of the heat exchanger model; then, reconstructing the surface mesh of the heat exchanger model to obtain a high-quality reconstructed surface mesh; setting a unit size for generating the polyhedral mesh; and reading in the high-quality reconstructed surface mesh to generate a polyhedral mesh model.

[0040] Since the generation of polyhedral meshes is usually affected by surface meshes, the efficient and convenient surface mesh generation capability of the Star-CCM+ simulation software can be used to reconstruct the surface mesh of the geometric model imported into Star-CCM+ to generate a high-quality reconstructed surface mesh. The generated high-quality reconstructed surface mesh is read into the Fluent Meshing software, and the unit size required to generate the polyhedral mesh is set to generate a polyhedral mesh model of the heat exchanger 10.

[0041] Next, after the heat exchanger 10 is modeled, the calculation model is selected. In Fluent software, the Standard k-ε model is the most widely used turbulence model, which has a moderate amount of calculation, more data accumulation and relatively high accuracy. Therefore, the Standard k-ε model is considered to be used in the heat exchange process analysis method for the fin tube sodium-air heat exchanger according to the present invention.

[0042] After determining the selected calculation model, the boundary conditions of the calculation model are determined. Here, the flow velocity of the air at the inlet damper 20 is used as the inlet boundary condition, and the pressure of the air at the outlet damper 22 is used as the outlet boundary condition to perform the temperature field analysis of the fin tube sodium-air heat exchanger 10.

[0043] Furthermore, an algorithm adapted to the above-mentioned calculation model is selected to calculate the gridded geometric model using the above-mentioned calculation model to obtain the temperature field and / or flow field state of the heat exchanger. Here, the SIMPLE algorithm is used to solve the three-dimensional temperature field of the fin tube sodium-air heat exchanger. In addition, the heat exchange power and flow resistance of the heat exchanger can also be calculated by the above-mentioned algorithm.

[0044] In the heat exchange process analysis method for the fin tube sodium-air heat exchanger 10 according to the present invention, it also includes calculating the pressure loss of the air flow passing through the porous medium model. The pressure loss of the air flow passing through the porous medium model is calculated by the following formula (1):

[0045]

[0046] Among them, s i is the pressure loss of air flowing through the porous medium model; μ is the viscosity of the porous medium model; α is the viscous resistance coefficient of the porous medium model; v i is the velocity of the air flow flowing through the porous medium model; C2 is the inertial resistance coefficient of the porous medium model; ρ is the density of the porous medium model.

[0047] Obtain the viscous resistance coefficient α of the porous media model and the inertial resistance coefficient C2 of the porous media model by following the steps below:

[0048] First, a local three-dimensional model of the heat exchange tube is established. For example, a linear three-dimensional model of the heat exchange tube can be established, that is, the model is established with the straight section of the heat exchange tube as a sample. Then, the local three-dimensional model of the heat exchange tube is simulated to be flushed transversely and downstream by air with different flow rates, that is, the air flow flushes the local three-dimensional model in the transverse direction and the vertical direction to obtain different pressure loss results, that is, the velocity and pressure loss of air flow with different flow rates in the transverse direction and the vertical direction. It should be noted here that transverse flushing refers to the air flow flowing in a direction perpendicular to the flow direction of the liquid sodium model in the heat exchange tube model, that is, the transverse direction is perpendicular to the flow direction of the liquid sodium model; correspondingly, downstream flushing refers to the air flow flowing in a direction parallel to the flow direction of the liquid sodium model in the heat exchange tube model, that is, the vertical direction is roughly parallel to the flow direction of the liquid sodium model. Next, the pressure loss result is fitted to the relationship between velocity and pressure drop, that is, the velocity and pressure loss obtained in the transverse direction and the vertical direction are fitted to a quadratic polynomial of velocity and pressure loss, such as Figure 4a and 4b As shown, Figure 4a The relationship between the velocity of the air flow in the transverse direction and the pressure loss and the relationship diagram are shown, that is, the relationship between the velocity and the pressure drop when the air flow sweeps across the local three-dimensional model of the heat exchange tube and the relationship diagram; Figure 4b The relationship between the velocity and pressure loss of the air flow in the vertical direction and the relationship between the velocity and pressure drop are shown, that is, the relationship between the velocity and pressure drop when the air flow flushes the local three-dimensional model of the heat exchange tube. Finally, the viscous resistance coefficient α and the inertial resistance coefficient C2 of the porous medium are obtained based on the obtained quadratic polynomial and the expression (1) of the flow pressure loss.

[0049] By obtaining the viscous resistance coefficient α and the inertial resistance coefficient C2 of the porous medium, the air flow velocity can be input through formula (1), thereby calculating the fluid pressure loss of the air flowing through the porous medium model, that is, the pressure drop, and the temperature field of the heat exchanger model can be obtained to know whether the temperature of the liquid sodium in the liquid sodium outlet pipeline of the heat exchanger model meets the requirements. At the same time, the temperature of the air at the inlet damper and the outlet damper can be known. The temperature values ​​at various locations can provide data support for the design and improvement of the fin tube sodium-air heat exchanger 10. The heat transfer process analysis method for the fin tube sodium-air heat exchanger according to the present invention can obtain the thermal performance of a large fin tube sodium-air heat exchanger, reduce the necessity of thermal tests, and thus reduce the design and test costs of the heat exchanger. The temperature field results obtained by the heat transfer process analysis method can accurately evaluate the heat transfer area of ​​the heat exchanger, for example, accurately evaluate the margin of the heat transfer area, thereby improving the economy of the heat exchanger.

[0050] The heat exchange process analysis method for the fin tube sodium-air heat exchanger according to the present invention can also determine the temperature difference between different heat exchange tubes and whether a local cold spot appears at the outlet of each heat exchange tube through an analysis model, thereby providing a basis for the structural optimization of the heat exchanger.

[0051] Regarding the embodiments of the present invention, it should also be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0052] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A heat exchange process analysis method for a fin tube sodium-air heat exchanger, characterized in that: The method comprises: Modeling the fin-tube sodium-air heat exchanger to obtain a heat exchanger model; Meshing the heat exchanger model to generate a meshed model; Selecting a computational model and an algorithm adapted to the computational model; and Calculating the grid model using the algorithm to obtain the temperature field state and / or flow field state of the heat exchanger; Wherein, modeling the fin tube sodium-air heat exchanger includes: modeling the fin heat exchange tube bundle of the fin tube sodium-air heat exchanger, and modeling the fin of each heat exchange tube of the fin heat exchange tube bundle as an equivalent porous medium model; The fin tube sodium-air heat exchanger is modeled to obtain a heat exchanger model including: Simplifying the modeling of the fin tube sodium-air heat exchanger, so that the heat exchanger model includes: a shell, a first collector disposed at an upper portion of the shell, a liquid sodium inlet pipeline disposed on the first collector and in fluid communication with the first collector, a second collector disposed at a lower portion of the shell, a liquid sodium outlet pipeline disposed on the second collector and in fluid communication with the second collector, the fin heat exchange tube bundle disposed in fluid communication between the first collector and the second collector, an inlet damper disposed at a bottom portion of the shell, an outlet damper disposed at a top portion of the shell, and an air flow distributor disposed between the inlet damper and the outlet damper for guiding an air flow; The model of each heat exchange tube is set to include a tube wall model of the heat exchange tube, a liquid sodium model located inside the tube wall model, a porous medium model located outside the tube wall model, and an air model located outside the porous medium model; Meshing the heat exchanger model to generate a meshed model includes: Using polyhedral meshes to divide the heat exchanger model to obtain a plurality of polyhedral models; and The plurality of polyhedral models are merged according to the computational domain to generate a merged mesh model; the use of polyhedral meshes to divide the heat exchanger model includes: Performing surface mesh processing on the heat exchanger model to obtain a surface mesh of the heat exchanger model; Reconstructing the surface mesh of the heat exchanger model to obtain a high-quality reconstructed surface mesh; Setting a cell size for generating the polyhedral mesh; and Reading in the high-quality reconstructed surface mesh to generate a polyhedral mesh; The merging process of the plurality of polyhedral models according to the calculation domain comprises: Perform Boolean operations on multiple polyhedral models belonging to the same computational domain; and merging the plurality of polyhedral models into a composite polyhedral model according to a Boolean operation; After selecting the calculation model, the step further includes determining boundary conditions of the calculation model; The selecting of the calculation model includes selecting the Standard k-ε model in the Fluent software, and the boundary conditions include the velocity of the air flow at the inlet damper and the pressure of the air flow at the outlet damper; Algorithms that are compatible with the calculation model include the SIMPLE algorithm.

2. The method according to claim 1, characterized in that The fins include multi-layer spiral serrated fins and / or annular fins.

3. The method according to claim 1, characterized in that The pressure loss of air flowing through the porous medium model is calculated by the following formula (1): （1） Among them, s i is the pressure loss of air flow through the porous medium model fluid; μ is the viscosity of the porous medium model; α is the viscous resistance coefficient of the porous medium model; v i is the velocity of air flowing through the porous medium model; C2 is the inertial resistance coefficient of the porous medium model; ρ is the density of the porous medium model.

4. The method according to claim 3, characterized in that The viscous resistance coefficient and inertial resistance coefficient of the porous medium model are obtained by: Establishing a local three-dimensional model of the heat exchange tube; Simulating air flows with different flow rates to flush the local three-dimensional model in the lateral direction and the vertical direction respectively, and obtaining the speed and pressure loss of the air flows with different flow rates in the lateral direction and the vertical direction; Fitting the acquired velocities and pressure losses in the lateral and vertical directions to quadratic polynomials of velocity and pressure loss; as well as The viscous drag coefficient and the inertial drag coefficient are obtained based on the quadratic polynomial and equation (1) for calculating the pressure loss.

5. The method according to claim 1, characterized in that The calculating the gridded model by using the algorithm comprises: The algorithm is used to calculate the heat transfer power and flow resistance of the heat exchanger model.

6. The method according to claim 1, characterized in that The temperature field state includes a three-dimensional temperature field state.

Images