Multi-channel supercritical water reactor thermal analysis method based on positioning grid correction

Abstract

The invention relates to the field of supercritical water reactor thermal analysis, in particular to a positioning grid correction-based multichannel supercritical water reactor thermal analysis method, which comprises the following steps of: acquiring real-time nuclear reactor working condition data under a target supercritical condition; the nuclear reactor working condition data are input into a multi-channel supercritical water reactor thermal model, a global calculation result is obtained, and the multi-channel supercritical water reactor thermal model is a multi-channel model established based on the influence of a positioning grid; and analyzing according to the global calculation result to obtain an evaluation result of the influence of the positioning grillwork on the performance of the reactor core under the supercritical condition. According to the method, local positioning grillwork simulation is not needed, the geometric dependence and the complexity of earlier-stage treatment are reduced, and the efficiency of analyzing the thermal performance of the supercritical water reactor influenced by the positioning grillwork is improved.

Description

Technical Field

[0001] The present invention relates to the field of supercritical water reactor thermal analysis, and in particular to a multi-channel supercritical water reactor thermal analysis method based on spacer grid correction. Background Art

[0002] As a type of advanced nuclear reactor, the supercritical water-cooled reactor (SCWR) has become a key development direction for next-generation nuclear energy technology due to its efficient thermal performance and high thermoelectric conversion efficiency. In a SCWR, the coolant (water) operates at supercritical pressure, possessing high specific heat capacity and thermal conductivity, enabling the reactor to operate at higher temperatures, thereby improving thermal efficiency.

[0003] For SCWRs, the primary goal of thermal analysis is to ensure reactor safety and stability under various operating conditions, particularly ensuring effective fuel rod cooling and preventing overheating and heat transfer degradation. Compared to conventional water reactors, SCWR thermal analysis presents a series of challenges, including dramatic changes in physical properties, degraded heat transfer, and unsuitable turbulence models. This is particularly true near the spacer grid area, where complex geometric characteristics dramatically impact flow and heat transfer. The resulting turbulence and the interaction between localized heat transfer enhancement and degradation further complicate analysis. Current simulations of local spacer grids involve building a geometric model of the grid, calculating correction factors, and then embedding them into the porous media model. Due to the high computational complexity and verification challenges of supercritical water reactors, empirical formulas and simplified models are commonly used in engineering practice to approximate the effects of the grid. While computationally efficient, this approach suffers from low accuracy and limited interpretability, making it of limited research value. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-channel supercritical water reactor thermal analysis method based on spacer grid correction to solve the current problem that the thermal performance of supercritical water reactors affected by spacer grids cannot be analyzed conveniently and efficiently.

[0005] An embodiment of the present invention provides a thermal analysis method for a multi-channel supercritical water reactor based on spacer grid correction, the method comprising the following steps: acquiring real-time nuclear reactor operating condition data under target supercritical conditions, the real-time nuclear reactor operating condition data including channel geometry parameters and coolant physical property parameters of the supercritical water reactor; inputting the nuclear reactor operating condition data into a multi-channel supercritical water reactor thermal model to obtain a global calculation result, the multi-channel supercritical water reactor thermal model being a multi-channel model established based on the influence of spacer grids; and performing analysis based on the global calculation result to obtain an evaluation result of the influence of the spacer grid on the core performance under the target supercritical conditions.

[0006] Optionally, the method further includes: obtaining local calculation results based on a three-dimensional geometric model of the spacer grid and computational fluid dynamics, the three-dimensional geometric model of the spacer grid including a spacer grid structure in each channel of the supercritical water reactor and a local coolant flow area structure near the spacer grid; obtaining a flow resistance correction factor and a heat transfer enhancement correction factor based on the local calculation results; correcting a momentum conservation equation and an energy conservation equation of a multi-channel model based on the flow resistance correction factor and the heat transfer enhancement correction factor to obtain a corrected multi-channel model, wherein position information of the momentum conservation equation and the energy conservation equation corresponds to position information of the flow resistance correction factor and the heat transfer enhancement correction factor; and obtaining a multi-channel supercritical water reactor thermal model based on the corrected multi-channel model and the local calculation results.

[0007] Optionally, the momentum conservation equation and the energy conservation equation of the multi-channel model are corrected according to the flow resistance correction factor and the heat transfer enhancement correction factor to obtain a corrected multi-channel model, including: establishing a momentum correction term and an energy correction term according to the flow resistance correction factor and the heat transfer enhancement correction factor, respectively; embedding the momentum correction term and the energy correction term into the momentum conservation equation and the energy conservation equation of the multi-channel model, respectively; and establishing a corrected multi-channel model according to the corrected momentum conservation equation and the energy conservation equation.

[0008] Optionally, the momentum correction term is -K spacer v, where K spacer is the flow resistance correction factor, and v is the fluid flow rate.

[0009] Optionally, the energy correction term is Among them, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor, L is the channel length, and D is the hydraulic diameter.

[0010] Optionally, the local calculation results are obtained based on the three-dimensional geometric model of the spacer grid and computational fluid dynamics, including: using computational fluid dynamics software to numerically solve the three-dimensional geometric model of the spacer grid to obtain the flow velocity field, pressure field and temperature field of the coolant in the spacer grid area; according to the flow velocity field, the pressure field and the temperature field, flow parameters and heat transfer parameters are obtained; wherein the flow parameters include total pressure drop, friction factor, fluid density and fluid flow rate, and the heat transfer parameters include a locally corrected Nusselt number, and the locally corrected Nusselt number characterizes the heat transfer efficiency enhancement effect under the influence of the spacer grid.

[0011] Optionally, obtaining the flow resistance correction factor and the heat transfer enhancement correction factor based on the local calculation results includes: calculating the flow resistance correction factor based on the flow parameters, the channel geometric parameters of the supercritical water reactor and the flow resistance correction factor calculation formula; calculating the heat transfer enhancement correction factor based on the heat transfer parameters, the channel geometric parameters of the supercritical water reactor and the heat transfer enhancement correction factor calculation formula; wherein the channel geometric parameters of the supercritical water reactor include channel length and hydraulic diameter.

[0012] Optionally, the flow resistance correction factor calculation formula is as follows:

[0013]

[0014] Where ΔP total is the total pressure drop, f is the friction factor, L is the channel length, D is the hydraulic diameter, K spacer is the flow resistance correction factor, ρ is the fluid density, and v is the fluid velocity.

[0015] The heat transfer enhancement correction factor is calculated as follows:

[0016]

[0017] Among them, Nu corrected is the locally corrected Nusselt number, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor, L is the channel length, and D is the hydraulic diameter.

[0018] Optionally, the multi-channel supercritical water reactor thermal model is obtained based on the corrected multi-channel model and the local calculation results, including: obtaining the calculation results of the corrected multi-channel model, the position information of the calculation results of the corrected multi-channel model corresponds to the position information of the local calculation results; calculating the absolute value of the difference between the local calculation results and the calculation results of the corrected multi-channel model; and obtaining the multi-channel supercritical water reactor thermal model through repeated iterations until the absolute value is less than a preset threshold.

[0019] Optionally, the method further includes: obtaining the number of channels and channel geometric parameters based on the supercritical water reactor geometry and coolant flow path; establishing the multi-channel model based on the number of channels and the channel geometric parameters, and initializing the multi-channel model; the initialization is to set the temperature, pressure, and flow rate distribution in each channel of the multi-channel model.

[0020] Compared with the prior art, the multi-channel supercritical water reactor thermal analysis method based on spacer grid correction provided by the present invention has the following beneficial effects:

[0021] An embodiment of the present invention provides a thermal analysis method for a multi-channel supercritical water reactor based on spacer grid correction. The method obtains real-time nuclear reactor operating data under target supercritical conditions, including channel geometry parameters and coolant physical properties of the supercritical water reactor; inputs the nuclear reactor operating data into a multi-channel supercritical water reactor thermal model to obtain a global calculation result. The multi-channel supercritical water reactor thermal model is a multi-channel model established based on the influence of the spacer grid; and analyzes the global calculation result to obtain an assessment result of the influence of the spacer grid on the core performance under supercritical conditions. The present invention does not require local spacer grid simulation, that is, it does not require the construction of a three-dimensional geometric model, which reduces geometric dependence and the complexity of pre-processing. Only real-time nuclear reactor operating data is required to analyze the thermal performance of the supercritical water reactor, thereby improving the efficiency of analyzing the thermal performance of the supercritical water reactor affected by the spacer grid. In addition, the multi-channel model has non-uniformity compared to the porous medium model, and can accurately simulate the influence of the spacer grid on the thermal performance of the supercritical water reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0023] Figure 1 A schematic flow chart of a thermal analysis method for a multi-channel supercritical water reactor based on spacer grid correction provided by an embodiment of the present invention;

[0024] Figure 2 This is a schematic flow chart of a specific method for thermal analysis of a multi-channel supercritical water reactor based on local spacer grid correction in an embodiment of the present invention;

[0025] Figure 3 is a schematic flow chart of a correction factor extraction method in an embodiment of the present invention;

[0026] Figure 4 4 is a schematic flow chart of a correction factor embedding method in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] The embodiment of the present invention provides a multi-channel supercritical water reactor thermal analysis method based on spacer grid correction, Figure 1 A schematic flow chart of a multi-channel supercritical water reactor thermal analysis method based on spacer grid correction is shown, the method comprising the following steps:

[0029] S110, acquiring real-time nuclear reactor operating condition data under target supercritical conditions.

[0030] The above-mentioned real-time nuclear reactor operating condition data includes channel geometry parameters and coolant physical property parameters of the supercritical water reactor;

[0031] S120: Input the above-mentioned nuclear reactor operating condition data into a multi-channel supercritical water reactor thermal model to obtain a global calculation result. The multi-channel supercritical water reactor thermal model is a multi-channel model established based on the influence of the spacer grid.

[0032] S130 , analyzing the global calculation results to obtain an evaluation result of the effect of the spacer grid on the core performance under the target supercritical condition.

[0033] Optionally, the above global calculation results are compared with the calculation results of the multi-channel model without the influence of the spacer grid to obtain the evaluation results of the influence of the spacer grid on the core performance under the above target supercritical conditions.

[0034] Optionally, the method further includes: obtaining local calculation results based on a three-dimensional geometric model of a spacer grid and computational fluid dynamics (CFD), wherein the three-dimensional geometric model of the spacer grid includes a spacer grid structure in each channel of the supercritical water reactor and a local coolant flow area structure near the spacer grid; obtaining a flow resistance correction factor and a heat transfer enhancement correction factor based on the local calculation results; correcting a momentum conservation equation and an energy conservation equation of a multi-channel model based on the flow resistance correction factor and the heat transfer enhancement correction factor to obtain a corrected multi-channel model, wherein position information of the momentum conservation equation and the energy conservation equation corresponds to position information of the flow resistance correction factor and the heat transfer enhancement correction factor; and obtaining a multi-channel supercritical water reactor thermal model based on the corrected multi-channel model and the local calculation results.

[0035] It should be noted that the three-dimensional geometric model of the spacer grid can accurately reflect the local phenomena of flow and heat transfer in and around the spacer grid structure.

[0036] Optionally, the step of obtaining local calculation results based on the three-dimensional geometric model of the spacer grid and computational fluid dynamics includes: using computational fluid dynamics software to numerically solve the three-dimensional geometric model of the spacer grid to obtain the flow velocity field, pressure field and temperature field of the coolant in the spacer grid area; obtaining flow parameters and heat transfer parameters based on the flow velocity field, the pressure field and the temperature field; wherein the flow parameters include total pressure drop, friction factor, fluid density and fluid flow rate, and the heat transfer parameters include a locally corrected Nusselt number, and the locally corrected Nusselt number characterizes the heat transfer efficiency enhancement effect under the influence of the spacer grid.

[0037] Optionally, the step of obtaining the flow resistance correction factor and the heat transfer enhancement correction factor based on the above-mentioned local calculation results includes: calculating the above-mentioned flow resistance correction factor based on the above-mentioned flow parameters, the channel geometric parameters of the above-mentioned supercritical water reactor and the flow resistance correction factor calculation formula; calculating the heat transfer enhancement correction factor based on the above-mentioned heat transfer parameters, the channel geometric parameters of the above-mentioned supercritical water reactor and the heat transfer enhancement correction factor calculation formula; wherein, the channel geometric parameters of the above-mentioned supercritical water reactor include channel length and hydraulic diameter.

[0038] Optionally, the calculation formula of the flow resistance correction factor is as follows:

[0039]

[0040] Where ΔP total is the total pressure drop, f is the friction factor, L is the channel length, D is the hydraulic diameter, K spacer is the flow resistance correction factor, ρ is the fluid density, and v is the fluid velocity.

[0041] The calculation formula of the above heat transfer enhancement correction factor is as follows:

[0042]

[0043] Among them, Nu corrected is the above locally corrected Nusselt number, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor, L is the channel length, and D is the hydraulic diameter.

[0044] Optionally, the above-mentioned step of correcting the momentum conservation equation and the energy conservation equation of the multi-channel model according to the above-mentioned flow resistance correction factor and the above-mentioned heat transfer enhancement correction factor to obtain a corrected multi-channel model includes: establishing a momentum correction term and an energy correction term respectively according to the above-mentioned flow resistance correction factor and the above-mentioned heat transfer enhancement correction factor; embedding the above-mentioned momentum correction term and the above-mentioned energy correction term into the momentum conservation equation and the energy conservation equation of the multi-channel model respectively; and establishing a corrected multi-channel model according to the corrected momentum conservation equation and the above-mentioned energy conservation equation.

[0045] Optionally, the momentum correction term is -K spacer v, where K spacer is the flow resistance correction factor mentioned above, and v is the fluid flow rate.

[0046] Optionally, the energy correction term is Among them, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor mentioned above, L is the channel length, and D is the hydraulic diameter.

[0047] Optionally, the step of obtaining a multi-channel supercritical water reactor thermal model based on the modified multi-channel model and the local calculation results includes: obtaining the calculation results of the modified multi-channel model, wherein the position information of the calculation results of the modified multi-channel model corresponds to the position information of the local calculation results; calculating the absolute value of the difference between the calculation results of the local calculation results and the calculation results of the modified multi-channel model; and repeatedly iterating until the absolute value is less than a preset threshold, thereby obtaining the multi-channel supercritical water reactor thermal model. It should be noted that multi-channel simulation does not rely on global correction factors; local correction factors can directly simulate the influence of the spacer grid on the flow and heat transfer behavior in each channel.

[0048] Optionally, the above method also includes: obtaining the number of channels and channel geometric parameters based on the above supercritical water reactor geometric structure and coolant flow path; establishing the above multi-channel model based on the above number of channels and the above channel geometric parameters, and initializing the above multi-channel model; the above initialization is to set the temperature, pressure, and flow rate distribution in each channel of the above multi-channel model.

[0049] The thermal analysis method for a multi-channel supercritical water reactor based on spacer grid correction provided by an embodiment of the present invention has the following beneficial effects:

[0050] 1. Multi-channel calculations enable detailed simulation of flow and heat transfer behavior within each channel, particularly in the spacer grid region, capturing complex local phenomena such as enhanced turbulence and localized heat transfer variations. Multi-channel calculations avoid the simplification issues of homogenization and provide higher local accuracy.

[0051] 2. Multi-channel simulation methods are less dependent on geometric properties because they directly simulate the flow and heat transfer behavior within each channel without relying heavily on domain partitioning and correction factors. Multi-channel methods are more adaptable and flexible, better able to handle geometric complexity, and maintain high accuracy and computational efficiency as model complexity increases.

[0052] 3. The multi-channel calculation and structural fusion method achieves tight coupling between the global and local aspects. Through multi-channel simulation, the influence of the spacer grid can be directly reflected in the calculation of each channel without relying on global correction factors, thus avoiding the limitations of global and local coupling and providing more consistent and realistic simulation results.

[0053] 4. Multi-channel simulations dynamically reflect the physical changes within each channel, including the nonlinear effects induced by the spacer grid. By embedding detailed simulation results of the local structure into multi-channel calculations, the dynamic response and complex behavior of the spacer grid region can be more accurately predicted.

[0054] 5. Multi-channel calculation methods can directly analyze the physical phenomena of global and local processes, including heat transfer and flow, as well as changes in boundary conditions at complex structures. Through detailed physical equations and dynamic solutions, multi-channel calculations can intuitively display and explain complex flow and heat transfer phenomena. This detailed process analysis can help engineers identify and understand potential problems and provide a clear physical basis for design optimization. In addition, multi-channel models can also perform parameter sensitivity analysis to clarify the impact of positioning grid parameters (such as size, position, and shape) on flow and heat transfer, thereby providing higher interpretability and design optimization guidance.

[0055] The following example details a specific method for thermal analysis of a multi-channel supercritical water reactor based on local spacer grid correction. Figure 2 A schematic flow chart of a specific method for thermal analysis of a multi-channel supercritical water reactor based on local positioning grid correction is shown. Figure 3 The schematic flow chart of the correction factor extraction method shown in FIG. Figure 4 The schematic flow chart of the correction factor embedding method shown is as follows:

[0056] Step 1: Create an accurate 3D geometric model based on the specific structure of the spacer grids in a supercritical water reactor. This model must include the detailed structure of the spacer grids and the surrounding coolant flow region. Ensure that the model details are clear enough, especially at key locations on the spacer grids, to accurately capture the local flow and heat transfer phenomena.

[0057] Step 2: Refine the mesh of the geometry. The mesh needs to be dense enough, especially in the spacer grid area, to accurately capture subtle phenomena such as turbulence and flow separation. Set appropriate boundary conditions for the CFD calculation, such as inlet velocity, outlet pressure, wall temperature, or adiabatic conditions.

[0058] Step 3: Use CFD software to numerically solve the constructed geometric model and grid to calculate the flow velocity field, pressure field, temperature field, etc. of the coolant in the spacer grid area.

[0059] Step 4: After obtaining the CFD calculation results, analyze them to determine the changes in flow resistance and heat transfer coefficient, that is, the effect of the spacer grid on local flow and heat transfer. Calculate the flow resistance correction factor using the flow resistance correction factor calculation formula; calculate the heat transfer enhancement correction factor using the heat transfer enhancement correction factor calculation formula.

[0060] The calculation formula of the above flow resistance correction factor is as follows:

[0061]

[0062] Where ΔP total is the total pressure drop, which represents the pressure loss caused by friction and local resistance during the flow of the fluid; f is the friction factor, which describes the friction effect between the fluid and the pipe wall, and is usually related to the Reynolds number (Re) and the pipe roughness; L is the channel length; D is the hydraulic diameter; K spacer is the flow resistance correction factor; ρ is the fluid density; v is the fluid velocity; It is the ratio of the length of the channel to the hydraulic diameter, reflecting the influence of the geometric characteristics of the channel on the pressure drop.

[0063] The calculation formula of the above heat transfer enhancement correction factor is as follows:

[0064]

[0065] Among them, Nu corrected is the locally corrected Nusselt number, which represents the enhanced effect of heat transfer efficiency; Nu base is the basic Nusselt number; C spacer is the heat transfer enhancement correction factor; L is the channel length; D is the hydraulic diameter.

[0066] Step 5: Based on the core geometry and coolant flow paths, the core is divided into multiple independent coolant channels. Each channel corresponds to a coolant flow path within the core. Initial conditions are set, including the temperature, pressure, and flow rate distributions. This step initializes the multi-channel calculation.

[0067] Step 6: Based on the correction factors extracted from the local CFD calculations, they are embedded into the momentum conservation equation and energy conservation equation of the multi-channel model. This step ensures that the local effects of the spacer grid are reflected in the global calculation.

[0068] The embedding of the flow resistance correction factor reflects the influence of the spacer grid on the coolant flow resistance, which is mainly reflected in the additional pressure drop when the coolant flows through the spacer grid. By constructing a momentum correction term and embedding it into the momentum conservation equation, the corrected momentum conservation equation is obtained.

[0069] The conservation equation of prime momentum is as follows:

[0070]

[0071] The revised momentum conservation equation is as follows:

[0072]

[0073] Where, ρ is the fluid density; v is the fluid flow velocity; is the acceleration term of fluid flow; is the pressure gradient, which indicates the change of pressure in spatial position; μ is the dynamic viscosity of the fluid; is the Laplace operator of fluid flow velocity; F is the external body force; -K spacer v is the momentum correction term, which is used to add additional flow resistance, which reduces the flow velocity in the channel and increases the pressure drop; the fluid mentioned above is the coolant.

[0074] The embedding of the heat transfer enhancement correction factor reflects the enhancement effect of the spacer grid on the coolant heat transfer coefficient, which is mainly due to the turbulence enhancement caused by the spacer grid, which improves the heat transfer efficiency. In the energy conservation equation of multi-channel calculation, an energy correction term is established based on the heat transfer enhancement correction factor, and the heat transfer energy correction term is embedded in the original heat transfer coefficient. Corrected heat transfer coefficient: in The revised energy conservation equation is obtained.

[0075] The original energy conservation equation is as follows:

[0076]

[0077] The revised energy conservation equation is as follows:

[0078]

[0079] Where ρ is the fluid density; c p is the specific heat capacity of the fluid; T is the temperature; k is the thermal conductivity of the fluid; Q is the heat, which represents the heat generation inside the system; is the partial derivative of temperature with respect to time; is the temperature gradient, which indicates the change in temperature in spatial position; the above-mentioned fluid is the coolant.

[0080] Step 7: Calculate the calculation results (temperature, pressure, flow rate, etc.) in each channel through repeated iterations. When the relative change rate of the above calculation results compared to the local calculation results is less than a preset threshold, the iteration converges.

[0081] Step 8: Integrate the final results of the multi-channel calculation to generate global calculation results (temperature field, pressure field, velocity field, etc.). The calculation results are compared with the calculation results without the spacer grid to evaluate the impact of the spacer grid on the overall performance of the core.

[0082] This embodiment of the present invention proposes a specific method for thermal analysis of multi-channel supercritical water reactors based on local spacer grid correction, specifically designed for accurate thermal calculations of supercritical water reactors. This method effectively couples the global and local levels, accurately capturing the effects of the spacer grid on coolant flow and heat transfer through multiple iterations, thereby achieving high-precision simulation of complex flow and heat transfer phenomena within supercritical water reactors. The method boasts high accuracy, excellent dynamic responsiveness, strong interpretability, and high computational efficiency.

[0083] The existing methods have the following defects: (1) The porous media model adopts homogenization processing, which cannot accurately capture the local influence of the spacer grid on flow and heat transfer, especially under complex phenomena such as turbulence enhancement and flow separation, and the simulation accuracy is low. The inaccurate simulation of the flow channel by the porous media method makes it difficult to analyze phenomena such as deterioration of rod bundle heat transfer and flow-induced vibration. (2) When using the regional porous media method, the calculation method is highly dependent on the geometric characteristics of the model, there is a relatively complex pre-processing stage, and it is not scalable. As the complexity of the model increases, the limitations of the porous media method become more obvious, and it is difficult to meet the needs of high-precision thermal analysis. (3) The simulation accuracy of the local area of ​​the spacer grid depends on the accuracy of the correction factor. However, these correction factors are usually based on local spacer grid simulation or empirical formulas, and cannot fully reflect the dynamic influence of the spacer grid on the entire flow and heat transfer distribution under different working conditions. Especially under supercritical conditions, the nonlinear enhancement of flow and heat transfer makes the global and local coupling more complicated, and a simple correction factor cannot accurately reflect the actual situation. (4) Due to its homogenization and simplification, the porous media method makes the nonlinear behavior of the positioning grid area (such as heat transfer deterioration and flow separation) more significant under supercritical conditions. This method is difficult to accurately predict these dynamic changes, especially in the case of rapid changes in operating conditions or accidents, and the dynamic response capability of the model is insufficient. (5) The porous media method reduces complex geometric structures and physical phenomena to averaged parameters (such as permeability, heat transfer coefficient, etc.) through simplification and homogenization, which makes it difficult to intuitively understand and explain the specific details of fluid flow and heat transfer processes; since these parameters are often obtained through empirical formulas or correction factors, they do not directly reflect specific physical phenomena and mechanisms. Therefore, when analyzing and diagnosing thermal problems, it is difficult to draw clear physical explanations or identify potential design improvements.

[0084] In summary, the method of using porous media to fuse the positioning grid structure has the disadvantages of inaccurate local simulation, strong geometric dependence, complex pre-processing, global and local calculation limitations of critical points, and poor dynamic response. The method of using multi-channel calculation to fuse local simulation can better solve the above problems. The method provided by the embodiment of the present invention has the following advantages compared with the existing method of fusing local simulation of porous media: (1) The embodiment of the present invention can more accurately capture the local influence of the positioning grid on flow and heat transfer through the combination of multi-channel calculation and local CFD simulation. This method avoids the homogenization treatment in the porous media method and can better reflect the actual physical phenomena, such as local turbulence enhancement and flow separation. (2) The embodiment of the present invention reduces the dependence on the geometric structure, especially in the pre-processing of complex geometric structures, without the need for excessive simplification. This makes the model more flexible when facing designs of different complexities, and also reduces the workload of the pre-processing stage. (3) Multi-channel calculation can update the physical properties of the coolant (such as density, viscosity, etc.) in real time and dynamically reflect nonlinear changes, especially under supercritical conditions. This capability makes the method of the present invention have higher accuracy and stability when dealing with complex working conditions and rapidly changing working conditions. (4) By directly embedding correction factors in the momentum conservation equation and the energy conservation equation, the embodiment of the present invention provides stronger physical interpretability. Engineers can clearly understand and analyze the impact of the positioning grid on the flow resistance and heat transfer coefficient, thereby making more reasonable design optimization. (5) Compared with pure CFD simulation, the embodiment of the present invention combines the global computing power of the multi-channel model and the refined processing of the local simulation, which significantly improves the computing efficiency while ensuring the calculation accuracy. This is particularly important in large-scale core thermal analysis. (6) The embodiment of the present invention can flexibly adjust the precision of the local simulation and the scope of the global calculation according to demand, making it not only suitable for complex thermal analysis of supercritical water reactors, but also can be extended to other types of reactor systems.

[0085] These advantages give the method of the present invention significant advantages in performing complex thermal analysis, especially in the design and optimization of supercritical water reactors.

[0086] The functions and effects achieved by the method provided by the embodiment of the present invention are:

[0087] The method provided by the embodiments of the present invention enables multiscale thermal analysis of supercritical water reactors. First, it successfully implements multiscale coupled analysis from the microscopic (detailed flow and heat transfer characteristics of local spacer grids) to the macroscopic (flow and temperature distribution of the coolant throughout the core). This method accurately captures physical phenomena at different scales in supercritical water reactors, thereby providing more accurate and detailed thermal analysis results. Second, by embedding correction factors, the method can reflect the impact of local structures on global flow and heat transfer, and continuously adjust model parameters based on iterative results to achieve dynamic response analysis for different operating conditions. Third, by embedding explicit mathematical physics formulas (such as correction factors in the momentum and energy conservation equations), the method significantly enhances the physical interpretability of heat transfer and flow processes. Researchers can better understand and explain the impact of local structures such as spacer grids on the overall reactor thermal performance, providing more powerful design guidance. Finally, the method significantly improves computational efficiency while maintaining accuracy, reducing geometric dependence and pre-processing complexity. This makes the method more operational and flexible in practical engineering applications.

[0088] In addition, since the method provided by the embodiment of the present invention realizes multi-scale coupling analysis, researchers can further optimize the core design in future studies and explore the impact of new positioning grid structures or other local designs on the overall system performance. It will also help promote the development of efficient, stable and safe supercritical water reactor systems. Through precise thermal analysis, it is possible to better understand and optimize the heat transfer and flow processes in the core, providing support for the design of more efficient nuclear energy systems. This method provides an extensible computational framework that is applicable to different types of reactor systems. On this basis, future research can further expand this method and apply it to the analysis of other complex thermal systems to explore new local-global coupling strategies.

[0089] Of course, those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the control device through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it may include the processes of the above-mentioned method embodiments, wherein the storage medium may be a memory, a disk, an optical disk, etc.

[0090] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0091] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0092] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A thermal analysis method for a multi-channel supercritical water reactor based on spacer grid correction, characterized in that: The method comprises the following steps: Acquiring real-time nuclear reactor operating condition data under target supercritical conditions, wherein the real-time nuclear reactor operating condition data includes channel geometry parameters and coolant physical property parameters of a supercritical water reactor; Inputting the nuclear reactor operating condition data into a multi-channel supercritical water reactor thermal model to obtain a global calculation result, wherein the multi-channel supercritical water reactor thermal model is a multi-channel model established based on the influence of a spacer grid; An analysis is performed based on the global calculation results to obtain an evaluation result of the effect of the spacer grid on the core performance under the target supercritical condition.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining local calculation results based on a three-dimensional geometric model of a spacer grid and computational fluid dynamics, wherein the three-dimensional geometric model of the spacer grid includes a spacer grid structure in each channel of a supercritical water reactor and a local coolant flow region structure near the spacer grid; Obtaining a flow resistance correction factor and a heat transfer enhancement correction factor based on the local calculation results; Correcting the momentum conservation equation and the energy conservation equation of the multi-channel model according to the flow resistance correction factor and the heat transfer enhancement correction factor to obtain a corrected multi-channel model, wherein position information of the momentum conservation equation and the energy conservation equation corresponds to position information of the flow resistance correction factor and the heat transfer enhancement correction factor; A multi-channel supercritical water reactor thermal model is obtained based on the modified multi-channel model and the local calculation results.

3. The method according to claim 2, characterized in that The step of correcting the momentum conservation equation and the energy conservation equation of the multi-channel model according to the flow resistance correction factor and the heat transfer enhancement correction factor to obtain a corrected multi-channel model includes: establishing a momentum correction term and an energy correction term according to the flow resistance correction factor and the heat transfer enhancement correction factor, respectively; embedding the momentum correction term and the energy correction term into the momentum conservation equation and the energy conservation equation of the multi-channel model respectively; A revised multi-channel model is established based on the revised momentum conservation equation and the energy conservation equation.

4. The method according to claim 3, characterized in that The momentum correction term is -K spacer v, where K spacer is the flow resistance correction factor, and v is the fluid flow rate.

5. The method according to claim 3, characterized in that The energy correction term is Among them, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor, L is the channel length, and D is the hydraulic diameter.

6. The method according to claim 2, characterized in that The local calculation results obtained based on the three-dimensional geometric model of the spacer grid and computational fluid dynamics include: Numerical solution is performed on the three-dimensional geometric model of the spacer grid using computational fluid dynamics software to obtain the flow velocity field, pressure field and temperature field of the coolant in the spacer grid region; Flow parameters and heat transfer parameters are obtained based on the flow velocity field, the pressure field, and the temperature field; wherein the flow parameters include a total pressure drop, a friction factor, a fluid density, and a fluid flow rate; and the heat transfer parameters include a locally corrected Nusselt number, wherein the locally corrected Nusselt number characterizes the heat transfer efficiency enhancement effect under the influence of the spacer grid.

7. The method according to claim 6, characterized in that The flow resistance correction factor and the heat transfer enhancement correction factor are obtained according to the local calculation results, including: Calculating a flow resistance correction factor according to the flow parameters, the channel geometric parameters of the supercritical water reactor, and a flow resistance correction factor calculation formula; Calculating a heat transfer enhancement correction factor based on the heat transfer parameters, the channel geometric parameters of the supercritical water reactor, and a heat transfer enhancement correction factor calculation formula; The channel geometric parameters of the supercritical water reactor include channel length and hydraulic diameter.

8. The method according to claim 7, characterized in that The flow resistance correction factor calculation formula is as follows: Where ΔP total is the total pressure drop, f is the friction factor, L is the channel length, D is the hydraulic diameter, K spacer is the flow resistance correction factor, ρ is the fluid density, and v is the fluid velocity. The heat transfer enhancement correction factor is calculated as follows: Among them, Nu corrected is the locally corrected Nusselt number, Nu base is the basic Nusselt number, C spacer is the heat transfer enhancement correction factor, L is the channel length, and D is the hydraulic diameter.

9. The method according to claim 2, characterized in that The multi-channel supercritical water reactor thermal model is obtained based on the modified multi-channel model and the local calculation results, including: Acquire a calculation result of the modified multi-channel model, wherein position information of the calculation result of the modified multi-channel model corresponds to position information of the local calculation result; Calculating the absolute value of the difference between the local calculation result and the calculation result of the modified multi-channel model; By repeated iterations until the absolute value is less than a preset threshold, a multi-channel supercritical water reactor thermal model is obtained.

10. The method according to claim 2, characterized in that The method further comprises: Obtaining the number of channels and channel geometric parameters according to the supercritical water reactor geometry and coolant flow path; The multi-channel model is established according to the number of channels and the channel geometric parameters, and the multi-channel model is initialized; the initialization is to set the temperature, pressure and flow rate distribution in each channel of the multi-channel model.

Images