Pressure drop analysis method and system for pebble-bed high-temperature gas cooled reactor bypass flow evaluation

Abstract

The invention discloses a pressure drop analysis method and system for pebble-bed high-temperature gas cooled reactor bypass flow evaluation, and the method comprises the steps: obtaining pebble-bed high-temperature gas cooled reactor structure data, and building a pebble-bed high-temperature gas cooled reactor three-dimensional model according to the pebble-bed high-temperature gas cooled reactor structure data; carrying out grid division on the three-dimensional model of the pebble-bed high-temperature gas cooled reactor, and then carrying out numerical simulation analysis; post-processing a result obtained by simulation analysis to obtain a bypass flow pressure drop value of the three-dimensional model of the pebble-bed high-temperature gas cooled reactor; and acquiring a non-bypass-flow pressure drop value based on a theoretical calculation method, and acquiring a bypass flow value of the pebble-bed high-temperature gas cooled reactor according to the bypass-flow pressure drop value and the non-bypass-flow pressure drop value. According to the method, the three-dimensional model of the pebble-bed high-temperature gas cooled reactor is constructed, a fluid dynamics numerical simulation calculation technology is combined, the complex flow phenomenon in the reactor is effectively simulated, and the bypass flow proportion is accurately calculated by comparing the pressure drop values under the bypass flow condition and the pressure drop values under the bypass flow-free condition.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power numerical simulation, and in particular to a pressure drop analysis method and system for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor. Background Art

[0002] The internal components of a high-temperature gas-cooled reactor are divided into ceramic internal components and metal internal components. The ceramic internal components are composed of graphite bricks, carbon bricks, tenons, square keys and other structures stacked together to form the reflective layer and insulation layer structure of the core. However, since graphite bricks expand when heated and shrink when irradiated, it is necessary to reserve enough gaps between the turns when installing and stacking to prevent stress caused by structural changes that damage the brick structure. However, due to such characteristics, the helium gas used as the core coolant has more bypass flow channels, forming a bypass effect of the coolant in the reactor. The generation of the bypass effect seriously affects the increase of the core power and the safety of the core fuel balls. An effective method is needed for average calculation in order to better control the internal physical thermal conditions during the actual operation of the reactor. Therefore, establishing a method for bypass analysis of high-temperature gas-cooled reactors is of great significance for reactor operation.

[0003] At present, the bypass evaluation of high-temperature reactors can be calculated and analyzed using three-dimensional computational fluid dynamics calculation methods. However, since the gaps between the graphite bricks are interconnected with the core pebble bed, helium flows in the criss-crossing gaps, and it is difficult to determine its flow direction and share. This makes it very difficult to count the share of bypass data when conducting three-dimensional computational fluid dynamics calculations and analysis, which brings a huge workload to the bypass evaluation of pebble-bed high-temperature gas-cooled reactors. Therefore, establishing an efficient bypass evaluation method based on specific physical phenomena is of great significance to the operation and development of high-temperature reactors. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed. Therefore, the present invention provides a pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor to solve the problem that the coolant bypass flow effect caused by the gaps in the graphite bricks in the pebble bed high temperature gas-cooled reactor is difficult to accurately analyze and evaluate.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor, comprising:

[0008] Acquiring structural data of a pebble bed type high temperature gas-cooled reactor, and establishing a three-dimensional model of the pebble bed type high temperature gas-cooled reactor according to the structural data of the pebble bed type high temperature gas-cooled reactor;

[0009] After meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor, numerical simulation analysis is performed;

[0010] The simulation results are post-processed to obtain the bypass pressure drop value of the pebble bed high temperature gas-cooled reactor three-dimensional model;

[0011] The pressure drop value without bypass flow is obtained based on a theoretical calculation method, and the bypass flow value of the pebble bed type high temperature gas-cooled reactor is obtained according to the pressure drop value with bypass flow and the pressure drop value without bypass flow.

[0012] As a preferred solution of the pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor according to the present invention, the numerical simulation analysis of the three-dimensional model of the pebble bed type high temperature gas-cooled reactor includes:

[0013] Determine relevant parameters of the pebble bed high temperature gas-cooled reactor three-dimensional model by using a porous medium model, and simulate the physical properties of the porous medium and the interference to the fluid flow;

[0014] The RNG k-ε two-equation turbulence model is used to simulate the turbulent flow characteristics of the fluid passing through the porous medium in the pebble bed high temperature gas-cooled reactor three-dimensional model;

[0015] A momentum equation is established according to the porous medium model and the RNG k-ε two-equation turbulence model, and the momentum equation is solved to obtain the flow characteristics of the fluid in the pebble bed high temperature gas-cooled reactor three-dimensional model.

[0016] As a preferred embodiment of the pressure drop analysis method for the bypass flow evaluation of the pebble bed high temperature gas-cooled reactor of the present invention, wherein: the RNG k-ε two-equation turbulence model includes:

[0017] The RNG k-ε two-equation turbulence model includes a turbulent kinetic energy equation and a dissipation rate equation;

[0018] The energy distribution and conversion in the fluid turbulent motion of the three-dimensional model of the pebble bed high temperature gas-cooled reactor are obtained by using the turbulent kinetic energy equation, which is expressed as:

[0019]

[0020] Where k is the turbulent kinetic energy equation, μ e is the effective viscosity, G k is the average velocity gradient, g b is the term for the turbulent kinetic energy generated by buoyancy, α kis the effective Prandtl number corresponding to the turbulent kinetic energy equation, ρ is the fluid density, x i and x j is the spatial position, μ i is the fluid dynamic viscosity, S k For custom source items;

[0021] The energy dissipation in the fluid turbulence motion of the pebble bed high temperature gas-cooled reactor three-dimensional model is obtained by using the dissipation rate equation, which is expressed as:

[0022]

[0023] Among them, ε is the dissipation rate equation, μ e is the effective viscosity, G k is the average velocity gradient, G b is the term for the turbulent kinetic energy generated by buoyancy, ε k is the effective Prandtl number corresponding to the dissipation rate equation, C 1ε , C 2ε , C 3ε is the RNG k-ε two-equation turbulence model constant, S ε For custom source items.

[0024] As a preferred embodiment of the pressure drop analysis method for the side flow evaluation of the pebble bed high temperature gas-cooled reactor of the present invention, the momentum equation is established according to the porous medium model and the RNG k-ε two-equation turbulence model, including:

[0025] The solid structure in the porous medium flow region is taken as a distributed resistance added to the fluid, and the momentum equation is established by adding a momentum equation source term to the standard momentum equation;

[0026] The source term of the momentum equation includes a viscosity loss term and an inertia loss term, and the source term of the momentum equation is expressed as:

[0027]

[0028] Among them, S i is the source term of the momentum equation, D ij is the viscous loss term, C ij is the inertia loss term, α is the permeability, and v is the volume of the porous medium.

[0029] As a preferred solution of the pressure drop analysis method for the bypass flow evaluation of the pebble bed high temperature gas-cooled reactor of the present invention, the post-processing of the results obtained by the simulation analysis includes:

[0030] By establishing a section for the pebble bed inlet and outlet of the pebble bed type high temperature gas-cooled reactor three-dimensional model and counting the pebble bed inlet and outlet pressure values, the pebble bed inlet and outlet pressure values ​​are used as the bypass pressure drop values ​​of the pebble bed type high temperature gas-cooled reactor three-dimensional model.

[0031] As a preferred embodiment of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to the present invention, obtaining the bypass flow value of the pebble bed high temperature gas-cooled reactor includes:

[0032] According to the bypass pressure drop value and the pressure drop value without bypass flow, the bypass value of the pebble bed high temperature gas-cooled reactor is calculated, and the calculation expression is:

[0033]

[0034] Among them, Δp 无旁流 is the pressure drop value without bypass flow, Δp 有旁流 It is the pressure drop value with bypass flow.

[0035] As a preferred embodiment of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to the present invention, wherein:

[0036] Meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor includes:

[0037] When dividing the grid, local encryption settings are performed and the encryption method is slit encryption.

[0038] In a second aspect, the present invention provides a system for pressure drop analysis for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor, comprising:

[0039] A three-dimensional model building module is used to obtain the structural data of the pebble bed type high temperature gas-cooled reactor and build a three-dimensional model of the pebble bed type high temperature gas-cooled reactor according to the structural data of the pebble bed type high temperature gas-cooled reactor;

[0040] A meshing and numerical simulation module, used for meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor and then performing numerical simulation analysis;

[0041] The bypass value acquisition module is used to post-process the results obtained from the simulation analysis to obtain the bypass pressure drop value of the pebble bed type high temperature gas-cooled reactor three-dimensional model; obtain the non-bypass pressure drop value based on the theoretical calculation method, and obtain the bypass value of the pebble bed type high temperature gas-cooled reactor according to the bypass pressure drop value and the non-bypass pressure drop value.

[0042] In a third aspect, the present invention provides a computing device, comprising:

[0043] Memory and processor;

[0044] The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor are implemented.

[0045] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor.

[0046] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an accurate and systematic pressure drop analysis method, which effectively simulates the complex flow phenomena in the reactor, including the fluid flow and turbulence characteristics in porous media, by constructing a three-dimensional model of a pebble bed high temperature gas-cooled reactor and combining it with computational fluid dynamics numerical simulation technology. By comparing the pressure drop values ​​with and without bypass flow, the bypass flow ratio is accurately calculated, providing a reliable numerical reference for the safe and stable operation of the pebble bed high temperature gas-cooled reactor, and optimizing the fluid distribution and cooling efficiency in the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing 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 creative labor. Among them:

[0048] Figure 1 It is a schematic diagram of the overall process of a pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor according to an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of a pebble bed type high temperature gas-cooled reactor model for a pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor according to an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of the division and naming of a pebble bed type high temperature gas-cooled reactor model for a pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor according to an embodiment of the present invention;

[0051] Figure 4 A schematic diagram of mesh division of a pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0054] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0055] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0056] At the same time, in the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Example 1

[0059] Before introducing this embodiment, for the convenience of understanding, the relevant terms are explained first;

[0060] Pebble bed type: refers to the fuel elements in the reactor in the form of spherical particles, usually graphite balls wrapped around fuel particles, and these spherical particles can flow freely or remain stationary in the core of the reactor to form a bed-like structure;

[0061] High Temperature Gas Cooled Reactor: A reactor that uses high temperature gas as a coolant. This reactor design is able to operate at higher temperatures, typically over 800°C, which improves thermal efficiency and allows direct use of high temperature process heat.

[0062] Bypass: In a pebble bed high temperature gas-cooled reactor, bypass refers to the phenomenon that the coolant does not flow along the designed main flow path during the flow process, but partially or completely flows through unexpected paths in the core, such as gaps between graphite bricks, leakage at the edge of the core, etc. Bypass may affect the thermal efficiency, safety and stability of the reactor;

[0063] Pressure drop: refers to the pressure lost by a fluid during its flow due to resistance, such as friction, gravity, acceleration, etc. In a reactor, pressure drop is an important parameter for evaluating the flow state of the coolant, calculating flow resistance, and optimizing the flow path.

[0064] Reference Figure 1 , which is an embodiment of the present invention, provides a pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor, comprising:

[0065] S100: Acquire structural data of a pebble bed type high temperature gas-cooled reactor, and establish a three-dimensional model of the pebble bed type high temperature gas-cooled reactor according to the structural data of the pebble bed type high temperature gas-cooled reactor;

[0066] The structural data of the pebble bed high temperature gas-cooled reactor include the overall geometric dimensions of the core, the width and shape of the gaps between the graphite bricks and various materials, the distribution of the channels inside the graphite bricks, the detailed specifications of the core cylinder area and the primary circuit outlet casing pipe, and the physical and thermal properties of the materials, such as thermal conductivity and density.

[0067] The structural data of the pebble bed high temperature gas-cooled reactor are preprocessed. The preprocessing process covers data cleaning, that is, eliminating errors or outliers; data integration, unifying data from different sources or formats; data simplification, reducing the complexity of the model through reasonable assumptions and approximations without significantly affecting the simulation accuracy; and data conversion, converting the original data into a format and coordinate system suitable for use by 3D modeling software. This series of preprocessing steps ensures the accuracy, consistency and availability of the data.

[0068] S102: Performing numerical simulation analysis after meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor;

[0069] Preferably, when dividing the grid, local encryption setting is performed, and the encryption method is slit encryption;

[0070] Specifically, before meshing, the 3D model of the pebble bed high temperature gas-cooled reactor was preprocessed, including naming the inlet, outlet, symmetry surface and specific interface surface, and creating the corresponding Part and Body. Subsequently, a local encryption strategy was implemented for key areas such as slits to ensure mesh fineness, and the minimum mesh size was set to capture model details. Finally, a mesh model containing the encrypted area was generated, providing a high-quality mesh foundation for subsequent simulation analysis. The gap structure between the square key and the graphite brick is characterized by the chamfered structure of the square key.

[0071] Preferably, the numerical simulation analysis of the pebble bed type high temperature gas-cooled reactor three-dimensional model includes using a porous medium model to determine relevant parameters of the pebble bed type high temperature gas-cooled reactor three-dimensional model, and simulating the physical properties of the porous medium and the interference to the fluid flow; using the RNG k-ε two-equation turbulence model to simulate the turbulent flow characteristics of the fluid in the pebble bed type high temperature gas-cooled reactor three-dimensional model when passing through the porous medium; establishing a momentum equation based on the porous medium model and the RNG k-ε two-equation turbulence model, and solving the momentum equation to obtain the flow characteristics of the fluid in the pebble bed type high temperature gas-cooled reactor three-dimensional model;

[0072] Preferably, the RNG k-ε two-equation turbulence model includes a turbulent kinetic energy equation and a dissipation rate equation;

[0073] Preferably, the turbulent kinetic energy equation is used to obtain the energy distribution and conversion in the turbulent motion of the fluid in the three-dimensional model of the pebble bed high temperature gas-cooled reactor. The turbulent kinetic energy equation is expressed as:

[0074]

[0075] Where k is the turbulent kinetic energy equation, μ e is the effective viscosity, G k is the average velocity gradient, G b is the term for the turbulent kinetic energy generated by buoyancy, α k is the effective Prandtl number corresponding to the turbulent kinetic energy equation, ρ is the fluid density, x i and x j is the spatial position, μ i is the fluid dynamic viscosity, S k For custom source items;

[0076] Preferably, the energy dissipation in the fluid turbulence motion of the three-dimensional model of the pebble bed high temperature gas-cooled reactor is obtained by using the dissipation rate equation, and the dissipation rate equation is expressed as:

[0077]

[0078] Among them, ε is the dissipation rate equation, μe is the effective viscosity, G k is the average velocity gradient, G b is the term for the turbulent kinetic energy generated by buoyancy, ε k is the effective Prandtl number corresponding to the dissipation rate equation, C 1ε , C 2ε , C 3ε is the RNG k-ε two-equation turbulence model constant, S ε For custom source items;

[0079] In the embodiment of the present application, the core adopts a porous medium model, and the porous medium model is affected by the porosity The influence of porosity The expression is:

[0080]

[0081] Among them, V s is the volume of the solid in the porous medium, V t is the total volume of the porous medium, where

[0082] In the embodiment of the present application, the characteristic dimension of the ball-stacked porous medium is the hydraulic diameter d h , which is the fuel ball diameter d p and porosity The hydraulic diameter is expressed as:

[0083]

[0084] Where, the fuel ball diameter d is taken p =60mm=0.06m;

[0085] In the embodiment of the present application, the interstitial flow velocity in the porous medium, i.e., the physical flow velocity u p The relationship between the average flow velocity u is expressed as:

[0086]

[0087] Based on the above, the Reynolds number and Nusselt number in porous media are expressed as:

[0088]

[0089] Preferably, the solid structure in the porous medium flow region is used as a distributed resistance added to the fluid, and the momentum equation is established by adding a momentum equation source term to the standard momentum equation;

[0090] Preferably, the source term of the momentum equation includes a viscosity loss term and an inertia loss term, and the source term of the momentum equation is expressed as:

[0091]

[0092] Among them, S i is the source term of the momentum equation, D ij is the viscous loss term, C ij is the inertia loss term, α is the permeability, and v is the volume of the porous medium;

[0093] In the embodiments of the present application, It is expressed as:

[0094]

[0095] It should be noted that the present invention ensures the high quality of the grid and effectively captures the model details, including the gap structure characteristics between the square keys and the graphite bricks, by finely meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor, especially implementing a local encryption strategy for key areas such as slits; numerical simulation analysis is performed using a porous medium model and an RNG k-ε two-equation turbulence model, which not only accurately simulates the physical properties and flow disturbance of the fluid in the porous medium, but also deeply studies the energy distribution, conversion and dissipation mechanism in the turbulent motion of the fluid; by introducing the source term of the momentum equation, the additional resistance of the porous medium to the fluid flow is taken into account, which further improves the accuracy and reliability of the simulation. This series of processing and technical applications has significantly improved the understanding and prediction capabilities of the internal fluid flow characteristics of the pebble bed high temperature gas-cooled reactor.

[0096] S104: Post-processing the results obtained from the simulation analysis to obtain the bypass flow pressure drop value of the pebble bed high temperature gas-cooled reactor three-dimensional model;

[0097] Preferably, a section is established for the inlet and outlet of the pebble bed of the pebble bed type high temperature gas-cooled reactor three-dimensional model, and the inlet and outlet pressure values ​​of the pebble bed are counted, and the inlet and outlet pressure values ​​of the pebble bed are used as the bypass pressure drop value of the pebble bed type high temperature gas-cooled reactor three-dimensional model;

[0098] In a possible embodiment, the post-processing method can use streamline visualization technology to intuitively display the flow path and velocity distribution of the fluid inside the ball bed, and then analyze the bypass phenomenon and its impact on the pressure drop; identify the area of ​​pressure gradient change through isobaric surface or pressure cloud map analysis to assist in understanding the mechanism of pressure drop formation; use the integration tool in the CFD post-processing software to integrate the pressure in a specific area to obtain more accurate pressure loss data; combine experimental data to verify and correct the simulation results to improve the accuracy of pressure drop value prediction.

[0099] S106: Obtaining a pressure drop value without bypass flow based on a theoretical calculation method, and obtaining a bypass value of a pebble bed type high temperature gas-cooled reactor according to the pressure drop value with bypass flow and the pressure drop value without bypass flow;

[0100] Preferably, the bypass value of the pebble bed high temperature gas-cooled reactor is calculated based on the bypass pressure drop value and the non-bypass pressure drop value, and the calculation expression is:

[0101]

[0102] Among them, Δp 无旁流 is the pressure drop value without bypass flow, Δp 有旁流 is the pressure drop value with bypass flow;

[0103] It should be noted that, in traditional schemes, the calculation of the bypass value of the pebble bed high temperature gas-cooled reactor often relies on complex experimental measurements or simplified theoretical estimates. These methods are not only costly and time-consuming, but also difficult to accurately capture the complex flow phenomena inside the pebble bed and its subtle influence on the pressure drop. In addition, traditional schemes are often unable to directly separate the contribution of the bypass effect to the total pressure drop, resulting in large uncertainty and error in the determination of the bypass value. Therefore, the present invention proposes an innovative calculation method, which first obtains the pressure drop value of the pebble bed in the non-bypass state through theoretical calculation, and then combines the bypass pressure drop value obtained by numerical simulation analysis to directly calculate the bypass ratio of the pebble bed high temperature gas-cooled reactor using a concise and clear calculation expression. This method not only simplifies the calculation process and reduces the calculation cost, but more importantly, it can accurately reflect the actual influence of the bypass phenomenon on the pressure drop, thereby improving the accuracy and reliability of the bypass value calculation.

[0104] The above is a schematic scheme of a pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor in this embodiment. It should be noted that the technical scheme of the system for pressure drop analysis of bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor and the technical scheme of the pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor described above belong to the same concept. The details not described in detail in the technical scheme of the pressure drop analysis system for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor in this embodiment can be found in the description of the technical scheme of the pressure drop analysis method for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor described above.

[0105] The pressure drop analysis system for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor in this embodiment includes:

[0106] A three-dimensional model building module is used to obtain the structural data of the pebble bed type high temperature gas-cooled reactor and build a three-dimensional model of the pebble bed type high temperature gas-cooled reactor based on the structural data of the pebble bed type high temperature gas-cooled reactor;

[0107] The meshing and numerical simulation module is used to mesh the three-dimensional model of the pebble bed high temperature gas-cooled reactor and then conduct numerical simulation analysis;

[0108] The bypass value acquisition module is used to post-process the results obtained from the simulation analysis to obtain the bypass pressure drop value of the pebble bed type high temperature gas-cooled reactor three-dimensional model; obtain the non-bypass pressure drop value based on the theoretical calculation method, and obtain the bypass value of the pebble bed type high temperature gas-cooled reactor based on the bypass pressure drop value and the non-bypass pressure drop value.

[0109] This embodiment further provides a computing device, which is applicable to the case of pressure drop analysis for bypass flow evaluation of a pebble bed type high temperature gas-cooled reactor, and includes:

[0110] A memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor as proposed in the above embodiment.

[0111] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor as proposed in the above embodiment is implemented.

[0112] The storage medium proposed in this embodiment and the pressure drop analysis method for implementing bypass flow evaluation of a pebble bed high temperature gas-cooled reactor proposed in the above embodiment belong to the same inventive concept. Technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0113] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0114] Example 2

[0115] Reference Figure 2-4 , which is an embodiment of the present invention, provides a pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor and provides experimental simulation results.

[0116] According to the structural data of the pebble bed high temperature gas-cooled reactor, a 3D model of the pebble bed high temperature gas-cooled reactor is established using the 3D modeling software solidworks; the 3D model of the pebble bed high temperature gas-cooled reactor is as follows Figure 2 As shown, it includes the gaps between graphite bricks, the gaps between graphite bricks and carbon bricks, the gaps between graphite bricks and square keys, the channels inside graphite bricks, the cylindrical area of ​​the core, the casing pipe at the outlet of the primary circuit, etc.

[0117] The established pebble bed high temperature gas-cooled reactor 3D model was meshed based on ANSYS Fluent Meshing.

[0118] Use FLUENT Meshing for meshing. Before meshing, name the model in SpaceClaim (SCDM), mainly as inlet, outlet, symmetry, and interface surfaces (83 pairs) of the 23 parts, such as Figure 3 As shown in the figure, Plane1 is the inlet, Plane2 is the outlet, Plane3 is the symmetry plane, and Plane4 is the interface plane. At the same time, on this basis, the parts and bodies of each part are named and created.

[0119] When the surface mesh is generated, local encryption is set according to the actual situation; in the surface mesh generation stage, key areas such as slits and intersections of fluid channels are locally encrypted according to the actual situation of the model and simulation requirements, so that the mesh density in these areas is significantly increased, so that subtle changes in the fluid in these complex flow paths can be more accurately captured, such as rapid changes in velocity, pressure and temperature gradients; through local encryption, the simulation results can more realistically reflect the flow characteristics inside the pebble bed high-temperature gas-cooled reactor, improving the accuracy and reliability of the simulation analysis.

[0120] The number of cells per gap in each gap is set to 3 using the proximity encryption method. The number of cells in the gap can be controlled to 3-4 layers. The minimum size setting captures the smallest structure in the model. The final mesh division results and some details are shown in the figure. Figure 4 shown.

[0121] After meshing, the established pebble bed high temperature gas-cooled reactor 3D model was simulated and analyzed based on ANSYS Fluent;

[0122] As a turbulence model, the RNG k-ε model takes into account the nonlinear effects in turbulent flows more accurately by introducing the renormalization group theory, thereby improving the ability to predict complex turbulent structures. This feature makes the turbulent flow simulation in the high-temperature reactor model more accurate, especially when dealing with strong turbulence areas or areas where the flow state changes rapidly, it can capture more details and improve the authenticity and reliability of the simulation.

[0123] By considering the core as a porous medium model and taking into account the influence of porosity, the present invention can more realistically reflect the complex geometric structure and flow characteristics inside the high-temperature reactor. The porous medium model not only simplifies the processing of the calculation domain, but also accurately describes the flow behavior of the fluid in the porous medium by defining the characteristic scale and the relationship between the gap velocity and the average velocity. This processing method avoids the high computational cost caused by directly modeling the complex geometric structure, while ensuring the accuracy of the simulation results.

[0124] The present invention introduces viscous loss terms and inertial loss terms into the source terms of the momentum equation in the porous medium model. These two terms represent the resistance caused by viscous friction and inertial effect when the fluid passes through the porous medium, respectively. This processing method enables Fluent to accurately simulate the pressure drop and velocity distribution of the fluid in the porous medium, further improving the accuracy of the simulation results.

[0125] Post-process the numerical simulation results based on ANSYS CFD-POST, and obtain the model pebble bed inlet and outlet pressure drop and the maximum core temperature;

[0126] After using ANSYS Fluent to perform numerical simulation analysis on the high-temperature reactor model, a wealth of data on flow field, temperature field, and turbulence characteristics were obtained. In order to further evaluate the performance of the model, these numerical simulation results were post-processed based on ANSYS CFD-POST.

[0127] Through the CFD-POST data extraction and visualization function, the pressure drop value at the inlet and outlet of the model pebble bed is obtained, and the difference between the two is calculated by setting monitoring points at the inlet and outlet of the model or extracting the average pressure value of a specific section;

[0128] In CFD-POST, a visual analysis of the temperature field is set up. By viewing the temperature cloud map, the area with the highest temperature in the core can be intuitively identified and the maximum temperature value of the area can be obtained. By combining the comprehensive analysis of the velocity field, pressure field and temperature field, the performance of the high-temperature reactor model can be comprehensively evaluated.

[0129] Combining theoretical calculation methods and THERMIX software, the core pebble bed area is modeled and calculated to obtain the pressure drop characteristics of the pebble bed when there is no bypass flow.

[0130] According to the actual pressure drop value including the bypass flow effect obtained through numerical simulation, the specific calculation formula in the bypass flow analysis method is used to compare and analyze this actual pressure drop value with the previously calculated pressure drop value without bypass flow;

[0131] Through this comparison process, the bypass value can be accurately calculated, that is, the degree of deviation caused by the fluid not flowing according to the designed path in the pebble bed area. The calculation of this bypass value not only reveals the complexity of the flow inside the core, but also provides important data support for optimizing flow design and improving system efficiency and safety.

[0132] 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 pressure drop analysis method for side flow evaluation of a pebble bed high temperature gas-cooled reactor, characterized in that: include: Acquiring structural data of a pebble bed type high temperature gas-cooled reactor, and establishing a three-dimensional model of the pebble bed type high temperature gas-cooled reactor according to the structural data of the pebble bed type high temperature gas-cooled reactor; After meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor, numerical simulation analysis is performed; The simulation results are post-processed to obtain the bypass pressure drop value of the pebble bed high temperature gas-cooled reactor three-dimensional model; The pressure drop value without bypass flow is obtained based on a theoretical calculation method, and the bypass flow value of the pebble bed type high temperature gas-cooled reactor is obtained according to the pressure drop value with bypass flow and the pressure drop value without bypass flow.

2. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 1, characterized in that: The numerical simulation analysis of the three-dimensional model of the pebble bed high temperature gas-cooled reactor includes: Determine relevant parameters of the pebble bed high temperature gas-cooled reactor three-dimensional model by using a porous medium model, and simulate the physical properties of the porous medium and the interference to the fluid flow; The RNG ks two-equation turbulence model is used to simulate the turbulent flow characteristics of the fluid passing through the porous medium in the pebble bed high temperature gas-cooled reactor three-dimensional model; A momentum equation is established according to the porous medium model and the RNG ks two-equation turbulence model, and the momentum equation is solved to obtain the flow characteristics of the fluid in the pebble bed high temperature gas-cooled reactor three-dimensional model.

3. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 2, characterized in that: The RNG ks two-equation turbulence model includes: The RNG k-ε two-equation turbulence model includes a turbulent kinetic energy equation and a dissipation rate equation; The energy distribution and conversion in the fluid turbulent motion of the three-dimensional model of the pebble bed high temperature gas-cooled reactor are obtained by using the turbulent kinetic energy equation, which is expressed as: Where k is the turbulent kinetic energy equation, μ e is the effective viscosity, G k is the average velocity gradient, G b is the term for the turbulent kinetic energy generated by buoyancy, α k is the effective Prandtl number corresponding to the turbulent kinetic energy equation, ρ is the fluid density, x i and x j is the spatial position, μ i is the fluid dynamic viscosity, S k For custom source items; The energy dissipation in the fluid turbulence motion of the pebble bed high temperature gas-cooled reactor three-dimensional model is obtained by using the dissipation rate equation, which is expressed as: Among them, ε is the dissipation rate equation, μ e is the effective viscosity, G k is the average velocity gradient, G b is the term for the turbulent kinetic energy generated by buoyancy, ε k is the effective Prandtl number corresponding to the dissipation rate equation, C 1ε , C 2ε , C 3ε is the RNG k-ε two-equation turbulence model constant, S ε For custom source items.

4. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 2, characterized in that: The momentum equation established according to the porous medium model and the RNG k-ε two-equation turbulence model includes: The solid structure in the porous medium flow region is taken as a distributed resistance added to the fluid, and the momentum equation is established by adding a momentum equation source term to the standard momentum equation; The source term of the momentum equation includes a viscosity loss term and an inertia loss term, and the source term of the momentum equation is expressed as: Among them, S i is the source term of the momentum equation, D ij is the viscous loss term, C ij is the inertia loss term, α is the permeability, and v is the volume of the porous medium.

5. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 1, characterized in that: Post-processing of the simulation results includes: By establishing a section for the pebble bed inlet and outlet of the pebble bed type high temperature gas-cooled reactor three-dimensional model and counting the pebble bed inlet and outlet pressure values, the pebble bed inlet and outlet pressure values ​​are used as the bypass pressure drop values ​​of the pebble bed type high temperature gas-cooled reactor three-dimensional model.

6. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 1, characterized in that: Obtaining the bypass value of the pebble bed high temperature gas cooled reactor includes: According to the bypass pressure drop value and the pressure drop value without bypass flow, the bypass value of the pebble bed high temperature gas-cooled reactor is calculated, and the calculation expression is: Among them, Δp 无旁流 is the pressure drop value without bypass flow, Δp 有旁流 It is the pressure drop value with bypass flow.

7. The pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor according to claim 1, characterized in that: Meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor includes: When dividing the grid, local encryption settings are performed and the encryption method is slit encryption.

8. A system for pressure drop analysis of bypass flow evaluation of a pebble bed high temperature gas-cooled reactor, characterized in that: include, A three-dimensional model building module is used to obtain the structural data of the pebble bed type high temperature gas-cooled reactor and build a three-dimensional model of the pebble bed type high temperature gas-cooled reactor according to the structural data of the pebble bed type high temperature gas-cooled reactor; A meshing and numerical simulation module, used for meshing the three-dimensional model of the pebble bed high temperature gas-cooled reactor and then performing numerical simulation analysis; The bypass value acquisition module is used to post-process the results obtained from the simulation analysis to obtain the bypass pressure drop value of the pebble bed type high temperature gas-cooled reactor three-dimensional model; obtain the non-bypass pressure drop value based on the theoretical calculation method, and obtain the bypass value of the pebble bed type high temperature gas-cooled reactor according to the bypass pressure drop value and the non-bypass pressure drop value.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the pressure drop analysis method for bypass flow evaluation of a pebble bed high temperature gas-cooled reactor as described in any one of claims 1 to 7.

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