Proportional modeling method for liquid metal reactor steam generator

Abstract

The invention discloses a proportional modeling method for a liquid metal reactor steam generator. The proportional modeling method comprises the following steps: adopting a systematic bidirectional proportional modeling method; determining a modeling principle; systematic decomposition is conducted on the steam generator, the steam generator is divided into a metal side single-phase flow subsystem and a water side single-phase / two-phase flow subsystem, and geometric parameters and operation parameters of all the subsystems are defined; key thermal-hydraulic phenomena in each part and the phenomenon area are identified, the thermal-hydraulic phenomena are graded based on a PIRT table, and a priority modeling sequence is determined; the metal side and the water side are analyzed from top to bottom, a flow heat transfer conservation equation is established, a corresponding criterion number is obtained after dimensional analysis, and the proportional relation of the needed size, power, flow and time is obtained; analyzing the local process from bottom to top, and determining a feature modeling criterion therein; and calculating a characteristic time ratio and a distortion factor, and carrying out distortion degree evaluation on a modeling result.

Description

Technical Field

[0001] This invention relates to a method for scaling up a liquid metal reactor steam generator, belonging to the field of liquid metal reactor steam generator design technology. Background Technology

[0002] Liquid metal reactors, as one of the advanced nuclear reactor types, occupy an important position in energy strategy, and the steam generator, as a key component, directly affects the safety and economy of the reactor. Because the design of steam generators for liquid metal reactors differs significantly from that of traditional reactor steam generators, and their operating environment is characterized by high temperature, high pressure, and unique working fluid properties, it is necessary to conduct overall performance tests to study their parameter responses under normal operation and transient accident conditions, analyze their thermal-hydraulic performance, verify the calculation results of the design program, and assess the feasibility and rationality of the component structural design.

[0003] However, constructing a model test bench that is completely identical to an actual liquid metal reactor steam generator faces numerous limitations in terms of economy and engineering feasibility. Therefore, establishing a scaled-down experimental device using proportional modeling analysis methods to simulate the thermal-hydraulic processes of the prototype steam generator has become a necessary approach.

[0004] Currently used modeling methods have certain limitations: although the power-volume modeling method can simulate power distribution and coolant flow, due to differences in geometry, the simulation results deviate from the prototype in terms of fluid velocity, pressure drop, etc.; the Ishii-Kataoka modeling method is suitable for simulating natural circulation phenomena, but it is insufficient in simulating two-phase flow and cannot fully and accurately reflect the complex thermal-hydraulic behavior inside the steam generator. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by providing a proportional modeling method for a liquid metal reactor steam generator. This method can be used to determine the physical dimensions of a prototype steam generator, enabling accurate simulation of the thermal-hydraulic behavior and key physical phenomena of the prototype steam generator under normal and transient conditions. This provides a reliable basis for the design optimization, performance verification, and safety assessment of liquid metal reactor steam generators.

[0006] The technical solution adopted in this invention is as follows: A method for scaling up a steam generator for a liquid metal reactor includes the following steps: S1. A systematic two-way scaling method is adopted; S2. Determine the modeling principles; S3. Decompose the steam generator into a single-phase flow subsystem on the metal side and a single-phase / two-phase flow subsystem on the water side, and define the geometric parameters and operating parameters of each subsystem. S4. Identify key thermal-hydraulic phenomena in each component and phenomenon area, classify the thermal-hydraulic phenomena based on the PIRT table, and determine the priority modeling order. S5. Perform a top-down analysis on the metal and water sides, establish the flow and heat transfer conservation equations, perform dimensional analysis to obtain the corresponding criterion numbers, and obtain the required proportional relationships of size, power, flow rate, and time. S6. Conduct bottom-up analysis of local processes, focusing on key issues, and determine the characteristic modeling criteria. S7. Calculate the feature time ratio and distortion factor to evaluate the distortion of the modeling results.

[0007] The two-way proportional modeling method employed in S1 provides a framework for overall analysis, taking into account the interaction between the system level and the process level. The modeling principles defined in S2 establish fundamental constraints from core dimensions such as geometry, thermal engineering, and hydraulics, ensuring the essential similarity between the prototype and the model. The system decomposition in S3 clarifies the boundaries and parameters of the modeling object, laying a targeted foundation for subsequent analysis. S4 uses a PIRT table to hierarchically focus on key phenomena, prioritizing modeling resources for processes with significant performance impacts. The top-down analysis in S5 starts from macroscopic conservation laws, deriving criterion numbers that provide a theoretical basis for parameter proportional relationships. The bottom-up analysis in S6 refines the analysis to details such as local resistance and flow patterns, supplementing the microscopic modeling criteria. The distortion evaluation in S7 quantifies the modeling effect through characteristic time ratio and distortion factor, ensuring the reliability of the results. Compared to the power-volume modeling method, it reduces biases caused by geometric differences through system decomposition and two-way analysis. Addressing the shortcomings of the Ishii-Kataoka method in two-phase flow simulation, it specifically incorporates flow pattern transformation criteria and drift velocity analysis, enabling a more comprehensive reflection of complex thermal-hydraulic behavior. Furthermore, the combination of hierarchical focus on key phenomena and quantitative distortion assessment ensures both the accuracy of the modeling and its engineering applicability, ultimately achieving accurate simulation of the thermal-hydraulic characteristics of a prototype steam generator, providing reliable support for design optimization, performance verification, and safety assessment.

[0008] Alternatively, the two-way proportional modeling method in step S1 is the H2TS multi-level two-way modeling analysis method. This method decomposes the reactor system into multiple interdependent subsystems and modules, analyzes the mass, momentum, and energy conservation equations to derive dimensionless criterion numbers characterizing specific phenomena and physical processes, and determines the proportional relationship of the main parameters between the prototype and the final prototype. By decomposing the complex reactor system into interdependent subsystems and modules, a refined decomposition of the system can be achieved, making complex structures and processes that were originally difficult to analyze as a whole readily identifiable. Based on this, the analysis of the mass, momentum, and energy conservation equations provides a rigorous theoretical basis for deriving the dimensionless criterion numbers. These criterion numbers accurately capture the essential characteristics of specific phenomena and physical processes, ensuring that the proportional relationship of parameters between the prototype and the final prototype is based on a deep understanding of physical laws. Compared to traditional modeling methods, the H2TS method more comprehensively considers various thermal-hydraulic phenomena and their interactions. It can simulate not only important physical phenomena in the steam generator but also mutually constraining factors such as the coupling characteristics of the primary and secondary loop systems, avoiding the one-sidedness caused by single-perspective analysis. This allows for a more accurate reflection of the thermal-hydraulic behavior of the prototype steam generator. By comprehensively considering various thermal-hydraulic phenomena and their interrelationships within the system, the derived criterion numbers and parameter ratios more closely resemble actual operating conditions. This ensures that the modeling results more accurately reflect the real behavior of the prototype steam generator, effectively overcoming the limitations of traditional methods in simulating complex thermal-hydraulic phenomena. This provides a scientifically reliable foundation for subsequent modeling steps and improves the systematicity and accuracy of the entire modeling process.

[0009] Alternatively, the modeling principles in step S2 include maintaining a constant volume ratio, consistent volumetric heat generation rate per unit time, consistent relative height, consistent thermal properties, and consistent hydraulic resistance of the flow channels. Specifically, maintaining a constant volume ratio ensures that the volume ratio of the prototype steam generator to the actual liquid metal reactor steam generator is constant, thus ensuring similarity in geometry and overall dimensions, laying the foundation for the modeling process. Consistent volumetric heat generation rate per unit time means maintaining the prototype's heat generation rate per unit time and volume consistent with the actual liquid metal reactor steam generator; that is, the ratio of the prototype's power to the actual steam generator's power is equal to the scaling factor. This helps simulate the heat transfer process within the steam generator, ensuring the similarity of thermal-hydraulic phenomena. Maintaining consistent relative height means maintaining the relative height of each component of the prototype consistent with the actual liquid metal reactor steam generator to reproduce the effect of gravity on fluid flow and heat transfer, ensuring the accuracy of fluid flow direction and thermal stratification. Maintaining consistent thermal properties: Ensuring the thermal properties of the prototype are consistent with those of the actual liquid metal reactor steam generator, including fluid density, specific heat capacity, thermal conductivity, and other thermophysical properties, to accurately reflect the fluid's thermodynamic behavior and heat transfer characteristics during modeling. Consistent hydraulic resistance in flow channels: The outer diameter and pitch of the simulated steam generator's pipes are consistent with those of the actual liquid metal reactor steam generator to ensure similar hydraulic resistance characteristics in the flow channels, thereby accurately simulating the fluid flow state and pressure drop distribution within the pipes. The synergistic effect of these principles forms a comprehensive constraint system covering geometry, energy, gravity effects, working fluid characteristics, and hydraulic characteristics. This system fundamentally reduces modeling distortion caused by mismatches in key parameters. Compared to the potential limitations of single-dimensional considerations in traditional modeling methods, it more systematically ensures the similarity between the prototype and the actual prototype in core physical processes, laying a solid foundation for subsequent system decomposition, criterion derivation, and distortion evaluation. This ensures that the entire modeling process revolves around accurately reflecting the prototype's characteristics, improving the reliability and effectiveness of the modeling results.

[0010] Alternatively, S3 decomposes the steam generator system, dividing the liquid metal reactor steam generator system into a metal-side primary loop system and a water-side secondary loop system, further subdividing it into individual components and various thermal-hydraulic phenomenon regions. First, dividing the whole into the metal-side primary loop system and the water-side secondary loop system clarifies the two core objects of modeling, providing a clear primary and secondary framework for the analysis of complex systems. Further subdivision into individual components and various thermal-hydraulic phenomenon regions allows for precise identification of specific objects requiring focus during modeling, such as heat transfer pipes, pressure shells, and phenomenon regions like single-phase flow and two-phase flow, making subsequent parameter definitions and phenomenon identification more targeted. This approach grasps both the overall system structure and delves into local details, avoiding omissions that might result from a general analysis of complex systems.

[0011] The optional geometric parameters in S3 include pipe diameter, pitch, and length, while the operating parameters include pressure, temperature, and flow rate. Pipe diameter, pitch, and length directly determine the spatial structure and dimensional relationships of the various components of the steam generator, serving as core indicators for ensuring geometric similarity. Their precise definition ensures that the prototype and the actual device maintain consistency in the physical morphology of the flow channels. Pressure, temperature, and flow rate reflect the key operating conditions of the system, directly affecting the fluid flow state and heat transfer characteristics. Their explicit setting provides fundamental data for subsequent analysis of thermal-hydraulic phenomena. This allows the system decomposition to move beyond the structural level and delve into the quantifiable physical properties.

[0012] Optional key thermo-hydraulic phenomena in step S4 include single-phase heat transfer on the metal side, metal-side metal circulation, metal-side pressure, tube wall heat conduction, tube wall heat storage, pressure drop, primary loop main pump head, flow field inhomogeneity, flow pattern, water-side single-phase heat transfer, water-side two-phase heat transfer, and water-side flow rate. The key thermo-hydraulic phenomena explicitly defined in S4 cover the core physical processes on both the metal and water sides during steam generator operation. Single-phase heat transfer, metal circulation, and pressure on the metal side are directly related to primary loop energy transfer and flow stability; tube wall heat conduction and heat storage are crucial for energy transfer across interfaces, affecting the overall thermal response rate; pressure drop, primary loop main pump head, and flow field inhomogeneity determine the dynamic characteristics and distribution of fluid flow; and flow pattern, as well as water-side single-phase heat transfer, two-phase heat transfer, and flow rate, reflect changes in the working fluid state and energy absorption efficiency in the secondary loop. This allows the modeling process to focus on the physical processes that play a decisive role in system performance. By using a hierarchical sorting method based on the PIRT table, the accurate simulation of key phenomena can be prioritized, avoiding the waste of resources on secondary factors. Compared with the generalized treatment of complex phenomena by traditional methods, this method can reduce modeling distortion caused by the neglect of key processes, ensuring that the experimental prototype is consistent with the prototype in core thermo-hydraulic behavior. This provides a clear target orientation for subsequent criterion derivation and parameter matching, improving the reliability and effectiveness of the modeling results.

[0013] Alternatively, the dimensionless numbers obtained in step S5 include the Richardson number, drag coefficient, number of heat sources, and heat capacity number, and these dimensionless parameters are equal to 1. These four dimensionless numbers characterize the key physical relationships within the steam generator from different perspectives. The Richardson number relates to buoyancy and inertia; its equality of 1 ensures similarity between the prototype and the model in buoyancy-driven flow characteristics. The drag coefficient reflects the influence of loop friction and form drag; equality ensures consistent energy loss characteristics during fluid flow. The number of heat sources reflects the effect of heat release on loop enthalpy rise; equality keeps the influence of heat input on the system's energy state synchronized. The heat capacity number characterizes the relationship between structural heat capacity and loop enthalpy rise; equality allows them to match in thermal response speed. Setting all four dimensionless parameters to be equal to 1 is the core condition for achieving similarity in the flow and heat transfer conservation equations between the prototype and the model. Compared to the lack of or laxity of criteria in traditional modeling methods, this comprehensive and rigorous dimensionless control provides a solid theoretical foundation for the derivation of parameter proportional relationships.

[0014] Optional feature modeling criteria in step S6 include drag coefficient, flow pattern transition criteria, and two-phase flow drift velocity. Controlling the drag coefficient ensures consistency between the prototype and the model in terms of friction and local drag characteristics. By adjusting the flow cross-section, length, or adding orifice plates, the local energy loss pattern can be matched to the prototype. The flow pattern transition criteria accurately capture the differences in physical properties under different flow patterns, addressing the transition from bubbly to flocculent, flocculent to emulsified, and flocculent or emulsified to annular flow, avoiding heat transfer and flow deviations caused by flow pattern simulation distortion. Modeling the two-phase flow drift velocity ensures the similarity of the relative motion characteristics between phases in the two-phase flow, ensuring accurate reproduction of complex two-phase flow fields. This allows the modeling analysis to delve from the macroscopic system to local details, compensating for the potential shortcomings of relying solely on macroscopic conservation equations. By focusing on key local processes such as friction drag, flow pattern transition, and two-phase drift, the simulation not only maintains consistency with the prototype in overall parameters but also maintains similarity in microscopic physical mechanisms.

[0015] Alternatively, the characteristic time ratio in step S7 can be composed of a specific frequency of the process attribute and the residence time constant of the control volume. The characteristic time ratio should be the same for each process in both the prototype and the steam generator. For the modeling analysis of the liquid metal reactor steam generator, a characteristic time ratio of 0.5 is required. This modeling analysis focuses on the dynamic characteristics of the process, accurately capturing the time-scale characteristics of different thermal-hydraulic processes by correlating frequency and residence time. Requiring the same characteristic time ratio for each process in both the prototype and the steam generator ensures consistency in their dynamic response rhythm, avoiding distortion in transient behavior simulation due to time-scale mismatch. The explicit requirement of a characteristic time ratio of 0.5 in the modeling analysis of the liquid metal reactor steam generator provides a specific quantitative standard for the time dimension modeling, giving a clear basis for setting the time parameters of the experimental prototype. This complements the completeness of the modeling from a dynamic perspective, echoing the modeling of static parameters such as geometry, thermal, and hydraulics, and together constructing a comprehensive similarity covering the spatiotemporal dimensions.

[0016] Alternatively, the distortion factor in step S7 can be defined to satisfy that the distortion factor of each dominant process in the effective modeling is less than 5%. The distortion factor, by comparing the characteristic differences between the prototype and the model in key processes, intuitively reflects the degree of deviation that may exist in the modeling process. Controlling the distortion factor within 5% can effectively constrain the accumulation of errors in each stage of the modeling process, ensuring that the simulation of the thermal-hydraulic characteristics of the prototype steam generator by the test prototype is within an acceptable range of accuracy.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The proportional modeling method for a liquid metal reactor steam generator provided by this invention deeply integrates system-level and process-level analysis: on the one hand, it decomposes the sodium-side and water-side subsystems at the overall level, deriving dimensionless criterion numbers through mass, momentum, and energy conservation equations to ensure the consistency of overall flow and heat transfer laws; on the other hand, it conducts bottom-up refined analysis of local processes, capturing microscopic physical mechanisms through flow pattern transformation criteria and drag coefficient control. This comprehensively covers the entire dimension of thermal-hydraulic processes, from macroscopic system coupling to the evolution of local phenomena, avoiding the omission of key phenomena due to the limited perspective of traditional methods.

[0018] 2. The proportional simulation method for a liquid metal reactor steam generator provided by this invention directly uses the same materials as the prototype at the working fluid and material level, ensuring complete matching of thermal properties with the prototype. At the pressure and geometry level, isobaric simulation and scaled-down design are employed to accurately reproduce the influence of gravity on flow and flow field distribution characteristics. At the criterion number level, strict control of key parameters such as the Richardson number and drag coefficient ensures that core physical relationships such as buoyancy, inertial force, and heat capacity are consistent with the prototype. This results in a high degree of consistency between the thermal-hydraulic response of the prototype and the prototype, significantly improving simulation accuracy.

[0019] 3. The proportional simulation method for a liquid metal reactor steam generator provided by this invention, in the parameter design stage, clarifies the calculation methods for the number of heat transfer tubes, support plate structure, and operating parameters based on simulation principles such as volume ratio and heat generation rate per unit volume, providing a direct and referable quantitative basis for prototype design. In the effect evaluation stage, the simulation effect is quantitatively evaluated through the calculation of characteristic time ratio and distortion factor, ensuring the effectiveness and traceability of the design scheme. This reduces the resource consumption for prototype construction and operation, significantly shortens the test cycle while ensuring simulation accuracy, and provides an efficient and feasible technical solution for engineering applications. Attached Figure Description

[0020] Figure 1 This is a scaled-down overall flow chart of a liquid metal reactor steam generator.

[0021] Figure 2 This is a schematic diagram of system decomposition.

[0022] Figure 3 PIRT represents intent. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example A method for proportional modeling of a liquid metal reactor steam generator, wherein the metal is sodium, such as... Figure 1 As shown, it includes the following steps: S1. Determine the modeling method: Select the H2TS multi-level bidirectional modeling analysis method. By decomposing the reactor system into multiple mutually influential subsystems and modules, analyze the mass, momentum and energy conservation equations to derive dimensionless criterion numbers characterizing specific phenomena and physical processes, and determine the main parameter ratios between the test prototype and the prototype.

[0026] S2. Determine the modeling principles: maintain a constant volume ratio, consistent volumetric heat generation rate per unit time, consistent relative height, consistent thermal properties, and consistent hydraulic resistance of the flow channel.

[0027] Based on the above modeling principles, the specific design requirements for the steam generator prototype are as follows: (1) The outer diameter, wall thickness and pitch of the heat transfer tubes of the prototype are consistent with those of the steam generator. The average effective length of the heat transfer tubes is consistent with that of the steam generator. The number of heat transfer tube bundles is matched with the heat exhaust power of the steam generator and the power of the core simulation body, that is, the size is reduced according to the volume ratio of the prototype to the steam generator.

[0028] (2) In order to reproduce the phenomena that occur in the steam generator, the number of heat transfer tubes in the steam generator cannot be too small; due to the power limit of the core simulator, the number of heat transfer tubes in the steam generator cannot be too large. (3) The prototype should also have the same support plate as the steam generator. The main structure of the support plate should be consistent with that of the steam generator, and the spacing of the support plate should be consistent with that of the steam generator. (4) The operating conditions of the prototype, namely, the operating parameters on both the sodium and water sides are kept consistent with those of the steam generator, including the sodium side inlet pressure and inlet temperature, and the water side inlet pressure and water supply temperature; (5) The prototype steam generator should have a water supply system on the water side, with adjustable water flow and temperature.

[0029] (6) The preliminary prototype parameters are as follows:

[0030] S3. The steam generator is considered as a complex system. It is decomposed according to its structure and function into a primary loop system (sodium side) and a secondary loop system (water side). It is further subdivided into components such as heat transfer tubes, pressure shell, and support baffles, as well as thermal-hydraulic phenomenon regions such as single-phase flow region and two-phase flow region. The geometric parameters (pipe diameter, pitch, length) and operating parameters (pressure, temperature, flow rate) of each module are defined.

[0031] S4. For each component and phenomenon area after decomposition, identify the key thermal-hydraulic phenomena, such as sodium-side single-phase heat transfer, sodium-side sodium circulation, sodium-side pressure, pipe wall heat conduction, pipe wall heat storage, pressure drop, primary loop main pump head, flow field non-uniformity, flow pattern, water-side single-phase heat transfer, water-side two-phase heat transfer, water-side flow rate, etc.

[0032] like Figure 3 As shown, based on the importance of these phenomena in the operation of the steam generator and their impact on the overall performance, the PIRT table is used to classify and rank them, identify key phenomena and processes, and clarify the focus for subsequent modeling analysis.

[0033] S5. Perform a top-down analysis on both the metal and water sides, establish the flow and heat transfer conservation equations, perform dimensional analysis to derive the corresponding criterion numbers, and obtain the required proportional relationships between size, power, flow rate, and time: The governing equations for heat transfer on the sodium and water sides are established as follows: Continuity equation:

[0034] Momentum equation:

[0035] Energy equation:

[0036] Heat transfer equation:

[0037] In the above formula —Fluid density , —Fluid flow rate , --pressure , --perimeter , Enthalpy , ——Cross-sectional area , --temperature , —wall temperature , —Sodium fluid inlet temperature , —Radial travel coordinates / m Heat flux density .

[0038] The conservation equations are made dimensionless, and their dimensionless parameters are: velocity ,length ,density density difference circulation area ,time ,temperature The subscript 0 represents the initial value of the parameter.

[0039] Dimensionless transformation of continuity equations:

[0040] Dimensionless transformation of the momentum equation:

[0041] Dimensionless energy equation:

[0042] The dimensions of the dimensionless parameters in the momentum and energy equations are defined as follows: Richardson number This characterizes the relationship between buoyancy and inertial force. drag coefficient Characterizes the friction and form resistance of the circuit; The heat source number is also called the phase transition number. This characterizes the effect of heat release from the heat source on the enthalpy rise of the loop; heat capacity This characterizes the relationship between the thermal capacity of the structure and the enthalpy rise of the loop.

[0043] To ensure similarity between the steam generator and the prototype, the three major equations must be similar, meaning that the four dimensionless parameters must be equal to 1.

[0044] The steam generator and the prototype have similar flow cross-sectional areas:

[0045] Thus, we have:

[0046] This criterion represents a constant pressure ratio between the steam generator and the prototype:

[0047] To avoid a series of errors introduced by pressure reduction simulation, isobaric simulation is used, that is:

[0048] Based on the above density similarity, we can conclude that:

[0049] In summary:

[0050] Similarly, drag coefficient It can also be simplified to:

[0051] Isobaric simulation was used, with a consistent initial temperature, taking into account... The relationship between the fluid velocity ratio and the height ratio obtained from the calculation is as follows:

[0052] For heat capacity Then we have:

[0053] S6. Conduct a bottom-up analysis of the local processes, focusing on issues such as friction and local resistance systems, heat transfer mechanisms, etc., and determine the characteristic modeling criteria: For single-phase flow on both the sodium and water sides, the friction, local resistance coefficients, and heat transfer mechanisms will be analyzed from bottom to top, based on the proportional modeling flow diagram of the sodium-side single-phase flow in the steam generator. The expressions for friction and local resistance coefficients will be consistent with the total friction and local resistance coefficients in the steam generator in the prototype by adjusting the flow cross-section size and length, local resistance, and adding orifice plates.

[0054] For two-phase flow pattern transition, it is necessary to determine the specific influencing factors of the two-phase flow pattern transition in each component. The two-phase flow pattern transition criteria used in this invention include: Transition from bubbly flow to flocculent flow:

[0055] Transition from flocculent to foamy flow:

[0056] Transition from flocculent / foamy flow to annular flow:

[0057] For the velocity of two-phase drift flow:

[0058] To maintain the model's simulation of drift flow, the following should be satisfied:

[0059] The above criteria are all based on the similarity of fluid properties. Since the prototype and the steam generator have the same medium and the same pressure, the above similarity criteria are satisfied.

[0060] S7. Calculate the feature time ratio and distortion factor to evaluate the distortion of the modeling results: By analyzing characteristic frequencies and residence times, the dominant processes in the entire steam generator operation are determined, and the characteristic time ratios of each dominant process are obtained. Each characteristic time ratio... By a specific frequency as a property of a specific process and control volume residence time constant Composition, that is .

[0061] The characteristic time ratios of each process in the prototype and the steam generator should be the same:

[0062] Furthermore, all dwell time constants are required to meet the following requirements:

[0063] Define the distortion factor DF:

[0064] The distortion factor of the prototype designed according to the present invention is shown in the table below.

[0065]

[0066] It can be seen that the distortion factors of each dominant process are all less than 5%, which meets the requirements of modeling analysis.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. The invention extends to any new features or combinations disclosed in this specification, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention. It is obvious to those skilled in the art that the invention is not limited to the details of the above exemplary embodiments, and that any detailed technical features not disclosed in this embodiment are prior art, which can be obtained by those skilled in the art from the prior art. Those skilled in the art can understand the specific methods in the embodiments of the invention according to the specific circumstances, and this disclosure does not specifically limit the embodiments in this regard.

Claims

1. A method for proportional modeling of a steam generator for a liquid metal reactor, characterized in that: Includes the following steps: S1. A systematic two-way scaling method is adopted; S2. Determine the modeling principles; S3. Decompose the steam generator into a single-phase flow subsystem on the metal side and a single-phase / two-phase flow subsystem on the water side, and define the geometric parameters and operating parameters of each subsystem. S4. Identify key thermal-hydraulic phenomena in each component and phenomenon area, classify the thermal-hydraulic phenomena based on the PIRT table, and determine the priority modeling order. S5. Perform a top-down analysis on the metal and water sides, establish the flow and heat transfer conservation equations, perform dimensional analysis to obtain the corresponding criterion numbers, and obtain the required proportional relationships of size, power, flow rate, and time. S6. Conduct bottom-up analysis of local processes, focusing on key issues, and determine the characteristic modeling criteria. S7. Calculate the feature time ratio and distortion factor to evaluate the distortion of the modeling results.

2. The modeling method according to claim 1, characterized in that, The bidirectional scaling method in step S1 is the H2TS multi-level bidirectional scaling analysis method. By decomposing the reactor system into multiple mutually influential subsystems and modules, the mass, momentum and energy conservation equations are analyzed to derive dimensionless criterion numbers characterizing specific phenomena and physical processes, and the main parameter ratios between the test prototype and the prototype are determined.

3. The modeling method according to claim 1, characterized in that, The modeling principles in step S2 include maintaining a constant volume ratio, consistent volumetric heat generation rate per unit time, consistent relative height, consistent thermal properties, and consistent hydraulic resistance of the flow channel.

4. The modeling method according to claim 1, characterized in that, In S3, the steam generator system is decomposed into a liquid metal reactor steam generator system, which is divided into a primary loop system on the metal side and a secondary loop system on the water side, and further subdivided into various components and various thermal-hydraulic phenomenon regions.

5. The modeling method according to claim 1, characterized in that, The geometric parameters in S3 include pipe diameter, pitch, and length, while the operating parameters include pressure, temperature, and flow rate.

6. The modeling method according to claim 1, characterized in that, Key thermal-hydraulic phenomena in step S4 include single-phase heat transfer on the metal side, metal-metal circulation on the metal side, metal-side pressure, pipe wall heat conduction, pipe wall heat storage, pressure drop, primary loop main pump head, flow field non-uniformity, flow pattern, single-phase heat transfer on the water side, two-phase heat transfer on the water side, and water side flow rate.

7. The modeling method according to claim 1, characterized in that, The dimensionless numbers obtained in step S5 include the Richardson number, drag coefficient, number of heat sources, and heat capacity number, and these dimensionless parameters are equal to 1.

8. The modeling method according to claim 1, characterized in that, The characteristic modeling criteria in step S6 include drag coefficient, flow pattern transformation criterion, and two-phase flow drift velocity.

9. The modeling method according to claim 1, characterized in that, The characteristic time ratio in step S7 consists of the specific frequency of the specific process attribute and the residence time constant of the control volume. The characteristic time ratio of each process in the prototype and the steam generator should be the same. The modeling analysis of the liquid metal reactor steam generator requires a characteristic time ratio of 0.

5.

10. The modeling method according to claim 1, characterized in that, In step S7, the distortion factor is defined to satisfy that the distortion factor of each dominant process in the effective modeling is less than 5%.

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