Grid mapping method and system for thermal calculation of pebble-bed high-temperature gas cooled reactor

Abstract

The invention discloses a grid mapping method and system for thermal calculation of a pebble-bed high-temperature gas cooled reactor, and relates to the field of nuclear reactor physics and thermal engineering, and the method comprises the following steps: solving a solid heat conduction equation of the pebble-bed high-temperature gas cooled reactor by using a solid temperature calculation method to obtain the average temperature of each grid and the average temperature of the grid boundary; assuming a two-dimensional distribution expression of the temperature in each grid, and calculating each coefficient of the expression according to an average value and a boundary value of the temperature; calculating a temperature angular point value of each grid by using a two-dimensional expression of temperature; and taking the four corner point values corresponding to the same grid point as the temperature value of the current point, and transmitting the temperature value to a fluid calculation program. Compared with a conventional mapping method, the method fully considers the characteristics of r-z geometry, and is suitable for models with large temperature change range and non-uniform grid size, so that reference is provided for thermal calculation of the pebble-bed high-temperature gas cooled reactor. By using the grid mapping method provided by the invention, the temperature values on the grid points are well consistent with the reference solution.

Description

Technical Field

[0001] The present invention relates to the field of nuclear reactor physical thermal calculation, and in particular to a grid mapping method and system for thermal calculation of a pebble bed high-temperature gas-cooled reactor. Background Art

[0002] The design and analysis of pebble bed high temperature gas-cooled reactors require the program to simulate the safety and operating characteristics of the reactor in detail.

[0003] Solving the temperature field of a pebble-bed high-temperature gas-cooled reactor primarily involves the solid heat conduction equation and the convection-diffusion equation. The convection-diffusion equation is typically solved using the finite difference method, while the solid heat conduction equation can be solved using the nodal expansion method. Calculating the fluid temperature requires the solid temperature value at each grid point, while the nodal expansion method yields the average temperature value for each grid. To transfer the solid temperature and couple the two temperature calculation modules, a suitable grid mapping method must be found to transfer the solid temperature from within the grid to the grid points while minimizing the deviation. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to transfer the solid temperature from the grid to the grid points while minimizing the deviation.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor, comprising the following steps:

[0007] The solid temperature calculation method is used to solve the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary.

[0008] Assuming a two-dimensional distribution expression of temperature in each grid, calculate the coefficients of the two-dimensional distribution expression based on the average value and boundary value of the temperature;

[0009] Using the two-dimensional expression of temperature, calculate the temperature corner value of each grid;

[0010] The four corner point values corresponding to the same grid point are used as the temperature value of the current point to complete the grid mapping.

[0011] As a preferred embodiment of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to the present invention, the method for solving the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor includes using a solid temperature calculation program to solve the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary: in a cylindrical coordinate system, the solid heat conduction expression is:

[0012]

[0013] Among them, λ e is the equivalent thermal conductivity, θ is the circumferential coordinate, T(r,θ,z) is the solid temperature, α(r,θ,z) is the solid-gas heat transfer coefficient, is the equivalent heat source density.

[0014] As a preferred embodiment of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to the present invention, the solution of the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor further comprises performing numerical calculations using a second-order nodal expansion method, meshing the cylindrical model with sector-shaped nodals, and obtaining the nodal coordinate value range, as expressed by:

[0015] r∈[r k -a k ,r k +a k ]

[0016] θ∈[θ k -b k ,θ k +b k ]

[0017] z∈[z k -c k ,z k +c k ]

[0018] Among them, r k a is the distance between the midpoint of node k in the r direction (radial direction) and the model axis; k is the size of node k in the r direction; b k is the size of node k in the θ direction; c k is the size of node k in the z direction;

[0019] To find the average temperature of grid k, the expression is:

[0020]

[0021] in, is the average solid temperature of node k, is the equivalent heat source density of node k; is the equivalent thermal conductivity of node k; is the average temperature at the right boundary of the kth node in the r direction; is the average temperature at the left boundary of the kth node in the r direction; is the average temperature at the right boundary of the kth node in the θ direction; is the average temperature at the left boundary of the kth node in the θ direction; is the average temperature at the right boundary of the kth node in the z direction; is the average temperature at the left boundary of the kth node in the z direction; α k is the solid-gas heat transfer coefficient of the kth node;

[0022] The average temperature is iteratively calculated until convergence, and the average value and boundary value of the solid temperature in each node are obtained.

[0023] As a preferred solution of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to the present invention, the two-dimensional distribution expression of the temperature in each grid is assumed, and the coefficients of the two-dimensional distribution expression are calculated based on the average value and boundary value of the temperature. The expression is:

[0024] T k (r,z)=A 1,k +A 2,k r+A 3,k z++A 4,k r 2 +A 5,k z 2

[0025] Among them, T k (r, z) is the temperature distribution in the grid k on the two-dimensional rz plane, r is the radial coordinate, z is the axial coordinate, A 1,k , A 2,k , A 3,k , A 4,k , A 5,k are the coefficients of the temperature distribution expression within the grid k.

[0026] As a preferred solution of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to the present invention, the temperature corner value of each grid is calculated using a two-dimensional expression of temperature, and the expression is:

[0027] T(r k+ ,z k+ )=T k (r k +a k ,z k +c k )

[0028] T(r k+ ,z k- )=T k (r k +a k ,z k -c k )

[0029] T(r k- ,z k- )=T k (r k -a k ,z k -c k )

[0030] T(r k- ,z k+ )=T k (r k -a k ,z k +c k )

[0031] Among them, T(r k+ ,z k+ ) is the temperature of the upper right corner of the grid k with the lower left corner as the coordinate origin; T(r k+ ,z k- ) is the temperature of the lower right corner of grid k, with the lower left corner as the coordinate origin; T(r k- ,z k- ) is the temperature of the lower left corner of grid k, with the lower left corner as the coordinate origin; T(r k- ,z k+ ) is the temperature of the upper left corner of the grid k, with the lower left corner as the coordinate origin, r k is the radial coordinate of the center point of grid k, a k is the half width of the grid k in the radial direction, z k is the axial coordinate of the center point of grid k, c k is the half-width of the grid k in the axial direction, r k+ The coordinate origin is the lower left corner, z k+ The lower left corner is the coordinate origin, r k- The coordinate origin is the lower left corner, z k- The lower left corner is the coordinate origin.

[0032] As a preferred solution of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to the present invention, the temperature value of the current point is expressed as follows:

[0033] T i,j =(T(r k+ ,z k+ ) i-1,j-1 +T(r k+ ,z k- ) i-1,j +T(r k- ,z k- ) i,j +T(r k-,z k+ ) i,j-1 ) / 4

[0034] Among them, T i,j is the temperature value of the i-th radial and j-th axial grid point, T(r k+ ,z k+ ) i-1,j-1 is the temperature value of the upper right corner of the i-1th radial and j-1th axial grid, T(r k+ ,z k- ) i-1,j is the temperature value of the upper right corner of the i-1th grid in the radial direction and the jth grid in the axial direction, T(r k- ,z k- ) i,j is the temperature value of the lower left corner of the i-th radial and j-th axial grid, T(r k- ,z k+ ) i,j-1 is the temperature value of the upper left corner of the i-th grid in the radial direction and the j-1-th grid in the axial direction.

[0035] Another object of the present invention is to provide a grid mapping system for thermal calculations of pebble-bed high-temperature gas-cooled reactors, which can solve the problems in the prior art of low calculation efficiency due to small grid size, lack of consistency in corner temperature calculations, and the inability to directly apply solid temperatures calculated by the nodal method to fluid temperature calculations through the collaborative work of multiple modules.

[0036] To solve the above technical problems, the present invention provides the following technical solutions: a grid mapping system for thermal calculation of a pebble bed high temperature gas-cooled reactor, comprising: a temperature field solving module, a temperature distribution modeling module, a corner point temperature calculation module, and a grid data integration module;

[0037] The temperature field solving module uses the second-order block expansion method to perform numerical calculations on the solid heat conduction equation in the cylindrical coordinate system, and obtains the average temperature of each sector grid and the average temperature of the six boundary surfaces through iterative solution;

[0038] The temperature distribution modeling module constructs a temperature distribution polynomial on a two-dimensional rz plane based on the grid average temperature and boundary temperature, and calculates the coefficients by the least squares method or boundary condition matching;

[0039] The corner temperature calculation module calculates the temperature value of each grid corner based on the established two-dimensional temperature distribution expression and substitutes the radial coordinates and axial coordinates of the four grid corners;

[0040] The grid data integration module is used to fuse the four calculation results of the shared corner points of adjacent grids into the temperature value of the final grid node.

[0041] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor are implemented.

[0042] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the grid mapping method for thermal calculation of a pebble-bed high-temperature gas-cooled reactor.

[0043] The present invention's beneficial effects: Compared to conventional mapping methods, the method fully considers the characteristics of RZ geometry and is applicable to models with large temperature variations and non-uniform grid sizes, thus providing a reference for thermal calculations of pebble-bed high-temperature gas-cooled reactors. Using the present grid mapping method, the temperature values at the grid points agree well with the reference solution, whereas conventional mapping methods result in significant deviations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 This is an overall flow chart of a grid mapping method for thermal calculations of a pebble bed high temperature gas-cooled reactor provided by the first embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor provided by the first embodiment of the present invention;

[0047] Figure 3 A schematic diagram of node division in a cylindrical coordinate system in a grid mapping method for thermal calculation of a pebble-bed high-temperature gas-cooled reactor provided by the first embodiment of the present invention;

[0048] Figure 4 A schematic diagram of a calculation model in a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor provided in a third embodiment of the present invention;

[0049] Figure 5 This is a diagram showing the absolute error distribution of solid temperature calculation results using a grid mapping method for thermal calculation of a pebble bed high-temperature gas-cooled reactor provided in a third embodiment of the present invention.

[0050] Figure 6This is a diagram showing the absolute error distribution of solid temperature calculation results using the volume weighted average method in a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor provided in a third embodiment of the present invention.

[0051] Figure 7 This is a diagram showing the absolute error distribution of solid temperature calculation results using a linear interpolation method in a grid mapping method for thermal calculations of a pebble-bed high-temperature gas-cooled reactor provided in a third embodiment of the present invention. DETAILED DESCRIPTION

[0052] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0053] Example 1, with reference to Figures 1 to 3 According to one embodiment of the present invention, a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor is provided, comprising:

[0054] The present invention first uses a solid temperature calculation program to solve the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary; then assumes a two-dimensional distribution expression of the temperature in each grid, and calculates the coefficients of the expression based on the average temperature and boundary value; then uses the two-dimensional expression of temperature to calculate the temperature corner point value of each grid; finally, the four corner point values corresponding to the same grid point are used as the temperature value of the point and are passed to the fluid calculation program. The temperature mapping process is as follows Figure 2 shown.

[0055] Step 1: Use the solid temperature calculation program to solve the solid heat conduction equation of the pebble bed high-temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary: In the cylindrical coordinate system, the solid heat conduction equation can be written as follows:

[0056]

[0057] Where: e is the equivalent thermal conductivity, unit is w / (m·k); θ is the circumferential coordinate, unit is rad; T(r,θ,z) is the solid temperature, unit is K; α(r,θ,z) is the solid-gas heat transfer coefficient, unit is w / (m 3 k); is the equivalent heat source density, in w / m 3 .

[0058] In order to efficiently solve the solid temperature, the second-order node expansion method is used for numerical calculation. The cylindrical model is meshed with sector nodes. The sector nodes are as follows: Figure 3 As shown. The coordinate value range of node k is:

[0059] r∈[r k -a k ,r k +a k ],θ∈[θ k -b k ,θ k +b k ],z∈[z k -c k ,z k +c k ] (2)

[0060] Where: r k a is the distance between the midpoint of node k in the r direction (radial direction) and the model axis; k is the size of node k in the r direction; b k is the size of segment k in the θ direction (circumferential direction); c k is the size of the segment k in the z direction (axial direction).

[0061] Solve for the average temperature of grid k:

[0062]

[0063] in, is the average solid temperature of node k; is the equivalent heat source density of node k; is the equivalent thermal conductivity of node k; is the average temperature at the right boundary of the kth node in the r direction; is the average temperature at the left boundary of the kth node in the r direction; is the average temperature at the right boundary of the kth node in the θ direction; is the average temperature at the left boundary of the kth node in the θ direction; is the average temperature at the right boundary of the kth node in the z direction; is the average temperature at the left boundary of the kth node in the z direction; α k is the solid-gas heat transfer coefficient of the kth node.

[0064] The average temperature in equation (3) is iteratively calculated until convergence, and the average value and boundary value of the solid temperature in each node are obtained.

[0065] Most existing thermal analysis programs use differential methods to solve the solid heat conduction equation, which requires a relatively fine meshing of the model, affecting computational efficiency. The nodal expansion method allows for the use of larger mesh sizes while maintaining accuracy, thereby improving computational efficiency.

[0066] Step 2: Assume a two-dimensional distribution expression for the temperature within each grid. Calculate the coefficients of the expression based on the average and boundary values of the temperature:

[0067] For circumferentially uniform problems, the three-dimensional model can be simplified to two dimensions:

[0068] T(r,θ,z)=T(r,z) (4)

[0069] Assume that on the two-dimensional rz plane, the solid temperature satisfies the following distribution in each grid:

[0070] T k (r,z)=A 1,k +A 2,k r+A 3,k z++A 4,k r 2 +A 5,k z 2 (5)

[0071] Define the one-dimensional temperature distribution in the r and z directions and the average temperature of the grid:

[0072]

[0073] In order to solve the five coefficients in formula (4), five corresponding equations are obtained according to the average value and boundary value of temperature:

[0074]

[0075] Combine equations (8)-(10), and use coefficient A i,k As the variable to be solved, establish the following linear equations:

[0076]

[0077] Solve equation (11) to obtain the expression of the two-dimensional temperature distribution in each grid.

[0078] Using the temperature distribution assumption shown in equation (6), we can maintain mapping accuracy even when the temperature gradient within the nodule is large. Common mesh mapping methods typically only assume a linear temperature distribution, but this method uses a larger mesh size when dividing the model, and the temperature gradient in the core region is large. Therefore, common mapping methods are not suitable for temperature calculations using the nodule expansion method.

[0079] Step 3: Use the two-dimensional expression of temperature to calculate the temperature corner value of each grid:

[0080] T(r k+ ,z k+ )=T k (r k +a k ,z k +c k ) (13)

[0081] T(r k+ ,z k- )=T k (r k +a k ,z k -c k ) (14)

[0082] T(r k- ,z k- )=T k (r k -a k ,z k -c k ) (15)

[0083] T(r k- ,z k+ )=T k (r k -a k ,z k +c k ) (16)

[0084] In order to verify the comparison between the grid mapping method of the present invention and other mapping methods, the volume weighted average method and the linear interpolation method are used for calculation. The calculation process is described by formula (23) and formula (24) respectively:

[0085]

[0086] Among them, T node and Represents the corner temperature and the average temperature of the four surrounding nodes, V i Represents the volume of the node around the corner point, d i is the distance from the center of the node to the corner point.

[0087] The corner temperature calculation method shown in equations (13-16) draws on the concept of fine power reconstruction in reactor physics analysis, which has been widely verified and applied, and has good calculation results. Therefore, the grid mapping method selected in this invention has a reliable theoretical basis.

[0088] Step 4: Take the four corner point values corresponding to the same grid point as the temperature value of the point and pass it to the fluid calculation program:

[0089] T i,j =(T(r k+ ,z k+ ) i-1,j-1 +T(r k+ ,z k- ) i-1,j +T(r k- ,z k- ) i,j +T(r k- ,z k+ ) i,j-1 ) / 4(19)

[0090] In the fluid calculation program, the solid temperature value obtained by this method is used to solve the three-dimensional steady-state energy conservation equation of helium flow:

[0091]

[0092] Among them, c p is the heat capacity of helium, is the mass flow rate of helium, T gas is the helium temperature, λ gas is the thermal conductivity of helium, h is the heat transfer coefficient between helium and solid, S is the heat transfer area between helium and solid, T solid is the temperature of the solid.

[0093] In the process of solving the fluid temperature, the solid temperature value at a given node is required. Therefore, through the grid mapping method of the present invention, the solid temperature calculation module and the fluid temperature calculation module can be coupled to perform a complete thermal analysis of the pebble bed high temperature gas-cooled reactor.

[0094] Example 2 is an embodiment of the present invention, which provides a system for a grid mapping method for thermal calculation of a pebble bed high-temperature gas-cooled reactor, including: a temperature field solving module, a temperature distribution modeling module, a corner point temperature calculation module, and a grid data integration module.

[0095] The temperature field solving module uses the second-order block expansion method to perform numerical calculations on the solid heat conduction equation in the cylindrical coordinate system, and obtains the average temperature of each sector grid and the average temperature of the six boundary surfaces through iterative solution.

[0096] The temperature distribution modeling module constructs a temperature distribution polynomial on a two-dimensional rz plane based on the grid average temperature and boundary temperature, and calculates coefficients through the least squares method or boundary condition matching.

[0097] The corner point temperature calculation module calculates the temperature value of each grid corner based on the established two-dimensional temperature distribution expression and substitutes the radial coordinates and axial coordinates of the four grid corners.

[0098] The grid data integration module is used to fuse the four calculation results of the shared corner points of adjacent grids into the temperature value of the final grid node.

[0099] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0100] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0101] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0102] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0103] Example 3, reference Figures 4 to 7 In this embodiment, in order to verify the beneficial effects of the present invention, economic benefit calculation and simulation experiments are conducted to scientifically demonstrate the effectiveness of the present invention.

[0104] In order to verify the feasibility of the method of the present invention, the HTR-PM model of the high temperature gas-cooled reactor nuclear power plant demonstration project was used for calculation verification. The actual size and material layout of the HTR-PM were used, and its outer boundary was set as a constant temperature boundary of 0°C. The calculation model is as follows Figure 4 shown.

[0105] The grid mapping method of the present invention and two common grid mapping methods are used to compare the temperature values of the grid points with the reference solutions. The absolute error distribution of the temperature is shown in the following figure: Figure 5-Figure 7 As shown, Figure 5 Using the method of the present invention, Figure 6 Using the volume-weighted average method, Figure 7 The linear interpolation method was used. Results showed that the temperature values at the grid points using the proposed grid mapping method agreed well with the reference solution, with the maximum deviation of the corner temperature being 6.5 K. In this example, the nodes at the bottom of the model have a larger axial dimension, and in this area, the two conventional mapping methods could result in an error of more than 50 K.

[0106] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor, characterized in that: include: The solid temperature calculation method is used to solve the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary. Assuming a two-dimensional distribution expression of temperature in each grid, calculate the coefficients of the two-dimensional distribution expression based on the average value and boundary value of the temperature; Using the two-dimensional expression of temperature, calculate the temperature corner value of each grid; The four corner point values corresponding to the same grid point are used as the temperature value of the current point to complete the grid mapping.

2. The grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to claim 1, characterized in that: The method for solving the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor includes using a solid temperature calculation program to solve the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor to obtain the average temperature of each grid and the average temperature of the grid boundary: in a cylindrical coordinate system, the solid heat conduction expression is: Among them, λ e is the equivalent thermal conductivity, θ is the circumferential coordinate, T(r,θ,z) is the solid temperature, α(r,θ,z) is the solid-gas heat transfer coefficient, is the equivalent heat source density.

3. The grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to claim 2, characterized in that: The solution to the solid heat conduction equation of the pebble bed high temperature gas-cooled reactor also includes performing numerical calculations using a second-order nodal expansion method, dividing the cylindrical model into grids with sector-shaped nodals, and obtaining the coordinate value range of the nodal blocks, which is expressed as follows: r∈[r k -a k ,r k +a k ] θ∈[θ k -b k ,i k +b k ] z∈[z k -c k ,z k +c k ] Among them, r k a is the distance between the midpoint of node k in the r direction (radial direction) and the model axis; k is the size of node k in the r direction; b k is the size of node k in the θ direction; c k is the size of node k in the z direction; To find the average temperature of grid k, the expression is: in, is the average solid temperature of node k, is the equivalent heat source density of node k; is the equivalent thermal conductivity of node k; is the average temperature at the right boundary of the kth node in the r direction; is the average temperature at the left boundary of the kth node in the r direction; is the average temperature at the right boundary of the kth node in the θ direction; is the average temperature at the left boundary of the kth node in the θ direction; is the average temperature at the right boundary of the kth node in the z direction; is the average temperature at the left boundary of the kth node in the z direction; α k is the solid-gas heat transfer coefficient of the kth node; The average temperature is iteratively calculated until convergence, and the average value and boundary value of the solid temperature in each node are obtained.

4. The grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to claim 3, characterized in that: The two-dimensional distribution expression of the temperature in each grid is assumed. According to the average value and boundary value of the temperature, the coefficients of the two-dimensional distribution expression are calculated. The expression is: T k (r,z)=A 1,k +A 2,k r+A 3,k z++A 4,k r 2 +A 5,k z 2 Among them, T k (r, z) is the temperature distribution in the grid k on the two-dimensional rz plane, r is the radial coordinate, z is the axial coordinate, A 1,k , A 2,k , A 3,k , A 4,k , A 5,k are the coefficients of the temperature distribution expression within the grid k.

5. The grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to claim 4, characterized in that: The two-dimensional expression of temperature is used to calculate the temperature corner value of each grid. The expression is: T(r k+ ,z k+ )=T k (r k +a k ,z k +c k ) T(r k+ ,z k- )=T k (r k +a k ,z k -c k ) T(r k- ,z k- )=T k (r k -a k ,z k -c k ) T(r k- ,z k+ )=T k (r k -a k ,z k +c k ) Among them, T(r k+ ,z k+ ) is the temperature of the upper right corner of the grid k with the lower left corner as the coordinate origin; T(r k+ ,z k- ) is the temperature of the lower right corner of grid k, with the lower left corner as the coordinate origin; T(r k- ,z k- ) is the temperature of the lower left corner of grid k, with the lower left corner as the coordinate origin; T(r k- ,z k+ ) is the temperature of the upper left corner of the grid k, with the lower left corner as the coordinate origin, r k is the radial coordinate of the center point of grid k, a k is the half width of the grid k in the radial direction, z k is the axial coordinate of the center point of grid k, c k is the half-width of the grid k in the axial direction, r k+ The coordinate origin is the lower left corner, z k+ The lower left corner is the coordinate origin, r k- The coordinate origin is the lower left corner, z k- The lower left corner is the coordinate origin.

6. The grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to claim 5, characterized in that: The four corner point values corresponding to the same grid point are used as the temperature value of the current point. The expression is: T i,j =(T(r k+ ,z k+ ) i-1,j-1 +T(r k+ ,z k- ) i-1,j +T(r k- ,z k- ) i,j +T(r k- ,z k+ ) i,j-1 ) / 4 Among them, T i,j is the temperature value of the i-th radial and j-th axial grid point, T(r k+ ,z k+ ) i-1,j-1 is the temperature value of the upper right corner of the i-1th radial and j-1th axial grid, T(r k+ ,z k- ) i-1,j is the temperature value of the upper right corner of the i-1th radial grid and the jth axial grid, T(r k- ,z k- ) i,j is the temperature value of the lower left corner of the i-th radial and j-th axial grid, T(r k- ,z k+ ) i,j-1 is the temperature value of the upper left corner of the i-th grid in the radial direction and the j-1-th grid in the axial direction.

7. A system using the grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to any one of claims 1 to 6, characterized in that: Including temperature field solving module, temperature distribution modeling module, corner temperature calculation module, grid data integration module; The temperature field solving module uses the second-order block expansion method to perform numerical calculations on the solid heat conduction equation in the cylindrical coordinate system, and obtains the average temperature of each sector grid and the average temperature of the six boundary surfaces through iterative solution; The temperature distribution modeling module constructs a temperature distribution polynomial on a two-dimensional rz plane based on the grid average temperature and boundary temperature, and calculates the coefficients by the least squares method or boundary condition matching; The corner temperature calculation module calculates the temperature value of each grid corner based on the established two-dimensional temperature distribution expression and substitutes the radial coordinates and axial coordinates of the four grid corners; The grid data integration module is used to fuse the four calculation results of the shared corner points of adjacent grids into the temperature value of the final grid node.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a grid mapping method for thermal calculation of a pebble bed high temperature gas-cooled reactor according to any one of claims 1 to 6 are implemented.

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