Control valve modeling method, system and equipment based on two fluids and six equations and medium

Abstract

The invention discloses a two-fluid six-equation-based control valve modeling method, system and equipment and a medium, and the method comprises the steps that a control valve is simplified into a pipeline model which is described by adopting a two-fluid six-equation and has variable local flow pressure loss, and the pipeline model is provided with two control body models and a connecting pipe model; in the vapor-phase momentum equation and the liquid-phase momentum equation of the connecting pipe model, a control valve vapor-phase variable local flow resistance item and a control valve liquid-phase variable local flow resistance item are added respectively; the control valve opening degree needed by variable local flow resistance item calculation is extracted to serve as a control interface parameter, and a control body and a connecting pipe are packaged into a control valve model with a control interface and a fluid interface; and connecting the control valve model with other thermal hydraulic assemblies and controller assemblies to construct a simulation system. Under the framework of a two-fluid six-equation system, modularization, reusability and expandability of the control valve model are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of control valve modeling and simulation, and specifically relates to a control valve modeling method, system, equipment and medium based on two-fluid six equations. Background Art

[0002] Steam-water two-phase thermal hydraulic systems are common process systems in pressurized water reactors (PWRs) and thermal power plants. These systems are typically mathematically modeled using a two-fluid six-equation system, which accurately simulates the mass and heat transfer behavior of the steam-liquid two-phase system under both normal operating conditions and emergency conditions. Control valves are the control components of thermal hydraulic systems, used to control the flow rate within the system's pipelines and regulate thermal hydraulic parameters such as flow rate, pressure, temperature, and vessel level, ensuring the system operates within a specified operating range. Within the framework of the two-fluid six-equation system, constructing a modular, reusable, and scalable control valve model applicable to single-phase liquid, steam-water two-phase, and single-phase steam is a key issue for high-precision simulation of the control valve's thermal hydraulic characteristics under different working fluid states and openings. This is also an urgent issue to demonstrate the control valve's effectiveness in regulating key parameters in steam-water two-phase thermal hydraulic systems. Summary of the Invention

[0003] In view of this, the present application is committed to providing a control valve modeling method, system, equipment and medium based on two-fluid six-equation system. Under the framework of the two-fluid six-equation system, the control valve model is modularized, reusable and extensible, and is suitable for different working fluid states from single-phase liquid, steam-water two-phase to single-phase steam, as well as different opening degrees from fully open to fully closed, providing reliable support for the modeling and simulation of steam-water two-phase thermal-hydraulic systems.

[0004] In a first aspect, the present application provides a control valve modeling method based on two-fluid six-equation modeling, the control valve modeling method based on two-fluid six-equation modeling comprises the following steps:

[0005] Step 1: Simplify the control valve into a pipe model with variable local flow resistance coefficient described by two-fluid six equations;

[0006] Step 2: Structurally, the control valve is simplified into a pipeline model consisting of two control body models and a pipe model. The control body model and the pipe model adopt a staggered grid form.

[0007] Step 3: In the vapor phase momentum equation of the takeover model, the closed equation of the source term expressing the local loss pressure drop of the vapor phase is modified, and the variable local flow resistance term of the vapor phase of the control valve is added; in the liquid phase momentum equation of the takeover model, the constitutive equation of the source term expressing the local loss pressure drop of the liquid phase is modified, and the variable local flow resistance term of the liquid phase of the control valve is added.

[0008] Step 4: Extract the control valve opening required for calculating the variable local flow resistance terms of the control valve vapor phase and liquid phase as the control interface parameter of the control valve model, and encapsulate the two control body models and one takeover model into a control valve model with a control interface and a fluid interface according to the staggered grid.

[0009] Step 5: Connect the constructed control valve model with other thermal-hydraulic component models based on the two-fluid six-equation method and the controller model for opening control to build a simulation system to simulate the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

[0010] In a specific embodiment of the present application, a simplified pipeline model uses Modelica as the modeling language, and includes a main equation model, a constitutive equation model, and a physical property equation model. The main equation model includes the mass equation, momentum equation, energy equation, and non-condensable gas equation for the vapor and liquid phases. The constitutive equation model includes the wall friction equation, the wall heat transfer equation, the phase interface friction equation, the phase interface heat transfer equation, and the phase interface mass exchange equation. The physical property equation model uses the standard formula IAPWS-97 for the physical properties of water and water vapor to obtain physical parameters such as density, thermal conductivity, viscosity coefficient, and constant pressure specific heat, which are used by the main equation model and the constitutive equation model.

[0011] In a specific embodiment of the present application, both the control body model and the takeover model adopt a modeling method based on one-dimensional simplification, and the thermal hydraulic parameters such as pressure, flow rate, temperature, specific internal energy, specific enthalpy of the vapor phase and liquid phase, as well as physical parameters such as density, thermal conductivity, viscosity coefficient, constant pressure specific heat, etc. are averaged on their respective flow sections, and it is assumed that the pressure is uniformly distributed on the same flow channel section.

[0012] In a specific embodiment of the present application, the upstream chamber of the control valve throttle hole is mapped to a first control body model, the area of the first control body is equal to the control valve inlet flow area, and the volume of the first control valve is equal to the volume of the upstream chamber of the control valve throttle hole; the downstream chamber of the control valve throttle hole is mapped to a second control body, the area of the second control body is equal to the control valve outlet flow area, and the volume of the second control body is the volume of the downstream chamber of the control valve throttle hole; the control valve throttle hole, i.e., the valve core, is mapped to a takeover model, the channel area of the takeover model is equal to the average value of the control valve inlet and outlet flow areas, and the length of the takeover model is equal to the average value of the lengths of the first control body model and the second control body model.

[0013] In a specific embodiment of the present application, the control body model performs modeling and calculation of the mass equation and energy equation of the vapor phase and liquid phase, the takeover model performs modeling and calculation of the momentum equation of the vapor phase and liquid phase, and the control body model and the takeover model perform coupled iteration to complete the six-equation calculation of the two fluids.

[0014] In one embodiment of the present application, the variable local flow resistance term of the vapor phase of the control valve is:

[0015]

[0016] In formula 1, F′ Lg is the variable local flow resistance term of the control valve vapor phase in the vapor phase momentum equation of the takeover model, α g is the cavitation fraction of the fluid flowing through the valve, ρ g is the vapor density flowing through the valve, V g is the vapor phase flow rate through the valve, HLOSG is the local flow resistance coefficient of the control valve vapor phase, and ΔL is the length of the pipe.

[0017] The variable local flow resistance term of the control valve liquid phase is:

[0018]

[0019] In formula 2, F′ Lf is the variable local flow resistance term of the control valve liquid phase in the liquid phase momentum equation of the takeover model, α f is the liquid fraction flowing through the valve, ρ f is the density of the liquid phase flowing through the valve, V f is the liquid phase flow rate flowing through the valve, and HLOSSF is the local flow resistance coefficient of the vapor phase of the control valve.

[0020] In a specific embodiment of the present application, on the control valve take-over model, the expression of the vapor phase momentum equation of the control valve vapor phase variable local flow resistance term after discretization is:

[0021]

[0022] The expression of the liquid phase momentum equation after discretization of the variable local flow resistance term of the control valve vapor phase is:

[0023] ΔP Lf =ΔL*F′ Lf =α k ρ f *HLOSSF*V f Formula 4

[0024] In Formula 3 and Formula 4, ΔP Lg is the expression of the variable local flow resistance term of the control valve vapor phase in the discretized vapor phase momentum equation, ΔP Lf is the expression of the variable local flow resistance term of the vapor phase of the control valve in the discretized liquid phase momentum equation.

[0025] In a specific embodiment of the present application, the control valve vapor phase local flow resistance coefficient HLOSG is:

[0026]

[0027] The local flow resistance coefficient HLOSSF of the control valve liquid phase is:

[0028]

[0029] In Formula 5 and Formula 6, ε is the variable local resistance coefficient of the control valve.

[0030] In a specific embodiment of the present application, the variable local resistance coefficient ε of the control valve is related to the flow rate of the control valve K V A monotonic relationship is formed, specifically:

[0031]

[0032] In formula 7, A is the flow area of the control valve takeover model, in m 2 K is the count; V The flow rate of the control valve is the flow rate of the valve when the pressure difference across the valve is 100kPa, expressed in m 3 / h is counted.

[0033] In a specific embodiment of the present application, the control valve flow rate K V It is monotonically related to the control valve opening x, specifically:

[0034] K V =K V,max f(x) Formula 8

[0035] In formula 8, x is the control valve opening, K V,max is the flow rate when the control valve is fully open, which is the characteristic parameter of the control valve; f(x) is the flow characteristic curve of the control valve, which expresses the change curve of the ratio of the flow rate corresponding to the current opening of the control valve to the flow rate when the control valve is fully open as the current opening of the control valve changes. It mainly includes three forms: equal percentage, equal proportion, and array-based customization.

[0036] In a specific embodiment of the present application, the equal percentage flow characteristic curve is:

[0037] f(x)=τ x-1 Formula 9

[0038] In Formula 9, τ is a constant of equal percentage.

[0039] The proportional flow characteristic curve is:

[0040] f(x)=xFormula 10

[0041] The array-based flow characteristic custom curve adopts the form of a binary array, which is composed of several units. Each unit consists of two numbers, the first number is the opening x, between 0 and 1; the second number is the flow number K corresponding to the opening x of the first number. V Flow rate K when the control valve is fully open V,max The flow characteristic custom curve based on the array is generated by linear interpolation, spline interpolation, polynomial fitting, etc. The horizontal axis is the control valve opening 0 to 1 and the vertical axis is the corresponding K V With K V,max A continuous curve of the ratio.

[0042] In a specific embodiment of the present application, the control interface of the control valve model is connected to the external controller model, the parameter transmitted is the control valve opening, and the data transmitted is in the form of an analog value from 0 to 1. The control valve opening transmitted through the control interface is then transmitted to the control valve variable resistance local resistance coefficient calculation module, and then the calculation result of the control valve variable resistance local resistance coefficient is transmitted to the control valve vapor phase and liquid phase variable local flow resistance items to carry out related momentum equation calculations.

[0043] In a specific embodiment of the present application, the fluid interface of the control valve model is connected to other thermal-hydraulic component models based on two-fluid six equations, and the transmitted parameters include pressure, cavitation fraction, vapor-liquid flow rate, vapor-liquid internal energy ratio, non-condensable gas fraction, etc., to realize the combination of the main equations of the control valve model and the main equations of other thermal-hydraulic component models.

[0044] A second aspect of the present application provides a control valve modeling system based on two-fluid six-equation modeling, the control valve modeling system based on two-fluid six-equation modeling includes:

[0045] The control valve node division module is used to structurally divide the control valve into two control bodies and a connecting pipe. The control bodies and connecting pipes adopt a staggered grid form;

[0046] Control valve local flow resistance modeling module, used to add control valve variable local resistance terms to the control valve vapor and liquid phase momentum equations;

[0047] The control valve variable local resistance coefficient calculation module is used to configure the control valve flow characteristic curve and the flow number when the control valve is fully open, and then calculate the current flow number of the control valve according to the current opening of the control valve, and then calculate the variable local resistance coefficient of the control valve.

[0048] The control valve control interface modeling module is used to build the control interface of the control valve model and pass the control interface parameters as the valve opening to the variable local flow resistance items of the vapor phase and liquid phase of the control valve;

[0049] The control valve model encapsulation module is used to construct the fluid interface of the control valve model and encapsulate the two control bodies and one connecting pipe of the control valve in the form of a staggered grid to form a control valve component model with a fluid interface and a control interface.

[0050] The control valve model application module is used to connect the constructed control valve model with other thermal-hydraulic component models such as pipeline models, container models, pipeline accessory models based on two-fluid six equations, and controller models for opening control, to build a simulation system and realize the simulation of the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

[0051] A third aspect of the present application provides a computer device comprising at least a processor, such as a CPU, a readable storage medium, and a display screen. The readable storage medium stores a computer program that, when executed by the processor, implements the aforementioned control valve modeling method based on two fluids and six equations.

[0052] A fourth aspect of the present application provides a computer-readable storage medium storing computer executable instructions, which, when executed by a processor, implement a control valve modeling method based on two fluids and six equations provided in the first aspect of the present application.

[0053] The fifth aspect of the present application provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements a control valve modeling method based on two-fluid six equations provided in the first aspect of the present application.

[0054] The beneficial effects of the technical solution of the present application are: within the framework of the two-fluid six-equation system, the control valve model is modularized, reusable, and extensible, and is applicable to different working fluid states from single-phase liquid, steam-water two-phase to single-phase steam, as well as different opening degrees from fully open to fully closed, providing reliable support for the modeling and simulation of steam-water two-phase thermal-hydraulic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Shown is a schematic diagram of a control valve modeling process based on two fluids and six equations according to an embodiment of the present application.

[0056] Figure 2 Shown is a schematic diagram of the control valve modeling topology structure of an embodiment of the present application.

[0057] Figure 3 Shown is a control valve model parameter transfer logic diagram of an embodiment of the present application.

[0058] Figure 4 Shown is a schematic diagram of the model icon after the control valve model of an embodiment of the present application is packaged.

[0059] Figure 5 Shown is a control valve modeling system architecture diagram based on two-fluid six equations according to an embodiment of the present application.

[0060] Figure 6 Shown is an example diagram of a control valve test model according to an embodiment of the present application. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0062] 1. Control valve modeling method based on two-fluid six equations

[0063] like Figure 1 As shown, at least one embodiment of the present application provides a control valve modeling method based on two-fluid six-equation modeling. The control valve modeling method based on two-fluid six-equation modeling method can be applied to the Modelica language. The control valve modeling method based on two-fluid six-equation modeling method includes the following steps:

[0064] Step 1: Simplify the control valve into a pipe model with variable local flow resistance coefficient described by two-fluid six equations;

[0065] The variable local flow resistance coefficient can reflect the variable local flow pressure loss.

[0066] Step 2: Structurally, Figure 2 As shown in FIG, the pipeline model of the control valve is simplified to include two control body models and a take-over model, and the control body model and the take-over model adopt a staggered grid form;

[0067] Two control body models and one takeover model respectively describe the upstream chamber of the control valve throttle orifice, the downstream chamber of the control valve throttle orifice and the control valve throttle orifice.

[0068] Step 3: In the vapor phase momentum equation of the takeover model, the closed equation of the source term expressing the local loss pressure drop of the vapor phase is modified, and the variable local flow resistance term of the vapor phase of the control valve is added; in the liquid phase momentum equation of the takeover model, the constitutive equation of the source term expressing the local loss pressure drop of the liquid phase is modified, and the variable local flow resistance term of the liquid phase of the control valve is added.

[0069] Step 4: Extract the control valve opening required for calculating the variable local flow resistance of the control valve vapor phase and liquid phase as the control interface parameter of the control valve model, and encapsulate the two control body models and one takeover model into a control valve model with control interface and fluid interface according to the staggered grid, as shown in the following example: Figure 4 shown.

[0070] Step 5: Connect the constructed control valve model with other thermal-hydraulic component models based on the two-fluid six-equation method and the controller model for opening control to build a simulation system to simulate the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

[0071] Other thermal hydraulic component models based on the two-fluid six-equation method include pipeline models, container models, and pipeline accessory models.

[0072] 1. Pipeline model based on two-fluid six-equation

[0073] The embodiment of the present application is based on the Modelica language, and the control valve model is simplified into a pipeline model including two control bodies and a connecting pipe described by two fluid six equations. Its topological structure is as follows: Figure 2 As shown. The two-fluid six-equation model takes into account the different physical properties, flow rates, temperatures of the two-phase fluids and the mass, energy and momentum exchange between the two phases during the actual two-phase fluid flow process. That is, the mass, momentum and energy conservation equations are established for the vapor phase and liquid phase respectively. In order to make the control equation group closed, it is necessary to add closed constitutive equations such as phase interface friction, phase interface heat transfer, phase interface mass exchange, wall friction, and wall heat transfer. The basic form of the two-fluid six-equation is as follows:

[0074] The gas-liquid mass conservation equation is:

[0075]

[0076] The gas-liquid energy conservation equation is:

[0077]

[0078] The gas-liquid momentum conservation equation is:

[0079]

[0080] Non-condensable gas equation:

[0081]

[0082] Wherein, subscript k represents gas or liquid (subscript g for gas and f for liquid); i represents gas-liquid interface; w represents wall; α k is the volume percentage; ρ k is the density; V k is the flow rate, U k is the internal energy; A is the flow area; P is the pressure; Γ k is the amount of material exchange at the phase interface; Γ ik is the amount of material exchange at the interface in the mainstream area; Γwk is the amount of material exchange at the interface of the wall thermal boundary layer; Q wk is the heat transfer from the wall; Q ik is the heat transfer at the phase interface; is the interface enthalpy in the mainstream area; h′ k is the enthalpy of the thermal boundary layer interface on the wall; DISS is the energy dissipation term; B x is the volume force; V ik is the interfacial flow velocity; F wk is the wall friction; F ik is the interfacial friction; F Lk is the local flow pressure loss; F Nk is the virtual mass force.

[0083] like Figure 2 As shown, the pipeline model based on two-fluid six-equation adopts a staggered grid form, the mass equation and energy equation are discretized and calculated on the control volume, and the momentum equation is discretized and calculated on the connecting pipe.

[0084] 2. Increase of variable local flow resistance of vapor and liquid phases in control valve

[0085] Compared to the existing pipeline model based on two fluids and six equations, the control valve model requires adding a source term to the pipeline model's vapor and liquid phase momentum equations to express the local pressure loss caused by changes in control valve opening, namely, the variable local flow resistance term for the control valve vapor and liquid phases. This embodiment of the present application utilizes the modular modeling concept of the Modelica language, treating the variable local flow resistance term for the control valve vapor and liquid phases as independent modules. The module output is used as one of the source terms in the vapor or liquid phase momentum equations of the pipe.

[0086] In formula (3), i.e. the gas-liquid momentum equation, F Lk is the local flow pressure loss, and the subscript k represents gas or liquid (the subscript for gas is g, and the subscript for liquid is f). Lk Add the variable local flow resistance of the control valve vapor and liquid phases to the equation, that is:

[0087] F Lg =F Lg0 +F′ Lg (5)

[0088] F Lf =F Lf0 +F′ Lf (6)

[0089] Among them, F Lg0 and F Lf0 To modify the local flow pressure loss of the vapor and liquid phase momentum equations before the control valve, F Lg and F Lfare the local flow pressure losses of the modified control valve vapor and liquid phase momentum equations, F′ Lg and F′ Lf are the variable local flow resistance terms of the vapor phase and liquid phase of the control valve, specifically:

[0090]

[0091]

[0092] In formulas (7) and (8) (corresponding to formulas 1 and 2, respectively), α g is the cavitation fraction of the fluid flowing through the valve, α f is the liquid fraction flowing through the valve, ρ g is the vapor density flowing through the valve, ρ f is the density of the liquid phase flowing through the valve, V g is the vapor phase flow rate through the valve, V f is the liquid phase flow rate flowing through the valve, HLOSG is the local flow resistance coefficient of the vapor phase of the control valve, HLOSF is the local flow resistance coefficient of the vapor phase of the control valve, and ΔL is the length of the connecting pipe.

[0093] In the control valve takeover model, the expression of the vapor phase momentum equation of the control valve vapor phase variable local flow resistance term after discretization is:

[0094]

[0095] The expression of the liquid phase momentum equation after discretization of the variable local flow resistance term of the control valve vapor phase is:

[0096] ΔP Lf =ΔL*F′ Lf =α k ρ f *HLOSSF*V f (10)

[0097] In formulas (9) and (10) (corresponding to formulas 3 and 4, respectively), ΔP Lg is the expression of the variable local flow resistance term of the control valve vapor phase in the discretized vapor phase momentum equation, ΔP Lf It is the expression of the variable local flow resistance term of the vapor phase of the control valve in the discretized liquid phase momentum equation.

[0098] HLOSSG is the local flow resistance coefficient of the control valve vapor phase, and HLOSSF is the local flow resistance coefficient of the control valve liquid phase, specifically:

[0099]

[0100]

[0101] In formulas (11) and (12) (corresponding to formulas 5 and 6, respectively), ε is the variable local resistance coefficient of the control valve.

[0102] 3. Calculation of variable local resistance coefficient of control valve

[0103] This application adopts the Modelica modular modeling concept and calculates the variable local resistance coefficient ε of the control valve as an independent module. The input of the module is the current opening of the control valve, and the output of the module is the variable local resistance coefficient corresponding to the current opening of the control valve. The variable local resistance coefficient is called by the variable local flow resistance items of the vapor phase and liquid phase of the control valve.

[0104] Control valve variable local resistance coefficient ε and control valve flow rate K V A monotonic relationship is formed, specifically:

[0105]

[0106] In formula (13) (corresponding to formula 7), A is the flow area of the control valve takeover model, expressed in m 2 K is the count; V The flow rate of the control valve is the flow rate of the valve when the pressure difference across the valve is 100kPa, expressed in m 3 / h is counted.

[0107] Control valve flow rate K V It is monotonically related to the current opening x of the control valve, specifically:

[0108] K V =K V,max f(x) (14)

[0109] In formula (14) (corresponding to formula 8), x is the control valve opening, K V,max is the flow rate when the control valve is fully open, which is the characteristic parameter of the control valve; f(x) is the flow characteristic curve of the control valve, which expresses the change curve of the ratio of the flow rate corresponding to the current opening of the control valve to the flow rate when the control valve is fully open as the current opening of the control valve changes. It mainly includes three forms: equal percentage, equal proportion, and array-based customization.

[0110] The equal percentage flow characteristic curve is:

[0111] f(x)=τ x-1 (15)

[0112] In formula (15) (corresponding to formula 9), τ is a constant of equal percentage.

[0113] The proportional flow characteristic curve is:

[0114] f(x)=x (16)

[0115] Formula (16) corresponds to Formula 10. The array-based flow characteristic custom curve adopts the form of a binary array, which is composed of several units. Each unit consists of two numbers, the first number is the opening x, between 0 and 1; the second number is the flow number K corresponding to the opening x of the first number. V Flow rate K when the control valve is fully open V,max The flow characteristic custom curve based on the array is generated by linear interpolation, spline interpolation, polynomial fitting, etc. The horizontal axis is the control valve opening 0 to 1 and the vertical axis is the corresponding K V With K V,max A continuous curve of the ratio.

[0116] The control valve opening is transmitted by the external controller model to the control valve variable local resistance coefficient calculation module through the control valve model control interface. The data form of the transmitted control valve opening is an analog value from 0 to 1. The control valve opening transmitted through the control interface is then transmitted to the control valve variable resistance local resistance coefficient calculation module, and then the calculation result of the control valve variable resistance local resistance coefficient is transmitted to the control valve vapor phase and liquid phase variable local flow resistance items to carry out related momentum equation calculations.

[0117] The control valve model also has a fluid interface, which is used to connect to other thermal-hydraulic component models based on the two-fluid six-equation system. The transmitted parameters include pressure, cavitation fraction, vapor-liquid flow rate, vapor-liquid internal energy ratio, non-condensable gas fraction, etc., thereby realizing the simultaneous establishment of the main equations of the control valve model and the main equations of other thermal-hydraulic component models.

[0118] The above content details the control valve modeling process and method based on two-fluid six-equation systems. Within the framework of the two-fluid six-equation system, the present embodiment of the application, through the control valve modeling process and method described above, achieves modularization, reusability, and scalability of the control valve model. It is applicable to different working fluid states, from single-phase liquid to steam-water two-phase to single-phase steam, and to different opening degrees, from fully open to fully closed, providing reliable support for the modeling and simulation of steam-water two-phase thermal hydraulic systems.

[0119] 2. Control valve modeling system based on two-fluid six equations

[0120] like Figure 5 As shown, at least one embodiment of the present application further provides a control valve modeling system based on two-fluid six-equation method, including:

[0121] The control valve node division module is used to structurally divide the control valve into two control bodies and a connecting pipe. The control bodies and connecting pipes adopt a staggered grid form.

[0122] Control valve local flow resistance modeling module, used to add control valve variable local resistance terms to the control valve vapor and liquid phase momentum equations;

[0123] The control valve variable local resistance coefficient calculation module is used to configure the control valve flow characteristic curve and the flow number when the control valve is fully open, and then calculate the current flow number of the control valve according to the current opening of the control valve, and then calculate the variable local resistance coefficient of the control valve.

[0124] The control valve control interface modeling module is used to build the control interface of the control valve model and pass the control interface parameters as the valve opening to the variable local flow resistance items of the vapor phase and liquid phase of the control valve;

[0125] The control valve model encapsulation module is used to construct the fluid interface of the control valve model and encapsulate the two control bodies and one connecting pipe of the control valve in the form of a staggered grid to form a control valve component model with a fluid interface and a control interface.

[0126] The control valve model application module is used to connect the constructed control valve model with other thermal-hydraulic component models such as pipeline models, container models, pipeline accessory models based on two-fluid six equations, and controller models for opening control, to build a simulation system and realize the simulation of the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

[0127] 3. Control Valve Model Instantiation Application

[0128] After completing the control valve model, you can instantiate the model and connect it with other pipeline models, flow boundary models, and controller models to form a simulation system. The following describes the process of building a simple system simulation model using the control valve model instantiation method.

[0129] 1. Use NUMAP or other Modelica modeling and simulation platforms to build a control valve test model. The test model is as follows: Figure 6 As shown in the figure, it includes pressure inlet component model, pipeline model, control valve model, controller model, and pressure outlet component model.

[0130] 2. Set the boundary conditions: inlet pressure of 10 MPa, inlet temperature of 20°C, outlet pressure of 9.9 MPa, inner diameter of the pipes before and after the control valve of 20 mm, length of 0.1 m, inlet and outlet flow areas of the control valve identical to those of the pipes before and after, Kv of the control valve of 50, and use an equal percentage curve. The control valve opening is 1 from 0 to 40 s, 0.8 from 50 to 100 s, 0.6 from 110 to 150 s, 0.4 from 160 to 200 s, 0.2 from 210 to 250 s, and 0 from 260 to 300 s.

[0131] 3. Simulation settings: simulation time 350s, output time step 0.01s, Euler algorithm, calculation accuracy 0.0001.

[0132] 4. Calculation results were derived to analyze the change in control valve flow rate over time and compared with theoretical calculations from the flow resistance manual. The results showed that the change trend in control valve flow rate was consistent with the control valve opening curve, and the deviation between the simulated control valve inlet and outlet pressure drops and the flow pressure drops calculated using the flow resistance manual was less than ±5.

[0133] This illustrates that the embodiments of the present application can be well applied to industrial simulation modeling projects, and can achieve model reuse and expansion by leveraging the modular modeling advantages of the Modelica language.

[0134] At least one embodiment of the present application further provides a computer device comprising at least a processor and a readable storage medium. The readable storage medium stores a computer program that, when executed by the processor, implements the aforementioned control valve modeling method based on two fluids and six equations.

[0135] It should be noted that the processor is, for example, a CPU. The computer device may also include a display screen.

[0136] At least one embodiment of the present application provides a computer-readable storage medium having computer executable instructions stored thereon. When the executable instructions are executed by a processor, the above-mentioned control valve modeling method based on two fluids and six equations is implemented.

[0137] At least one embodiment of the present application provides a computer program product, including a computer program / instruction, which implements the above-mentioned control valve modeling method based on two fluids and six equations when the computer program / instruction is executed by a processor.

[0138] It should be noted that the combination of the various technical features in the embodiments of the present application is not limited to the combination described in the embodiments of the present application or the combination described in the specific embodiments. All technical features described in the present application can be freely combined or combined in any way unless there is a contradiction between them.

[0139] As used in this application and the claims, unless the context clearly indicates an exception, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular and may include the plural, unless the context clearly indicates otherwise. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements. The phrase "comprises a..." does not preclude the presence of additional identical elements in the process, method, product, or apparatus that includes the elements.

[0140] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A control valve modeling method based on two-fluid six-equation method, characterized in that: The following steps are involved: Step 1: Simplify the control valve into a pipe model with variable local flow pressure loss described by two-fluid six equations; Step 2: Structurally, the control valve is simplified into a pipeline model consisting of two control body models and a take-over model. The control body model and the take-over model adopt a staggered grid form. Step 3: In the vapor phase momentum equation of the nozzle model, the closed equation of the source term expressing the local loss pressure drop of the vapor phase is modified, and a variable local flow resistance term of the vapor phase of the control valve is added; in the liquid phase momentum equation of the nozzle model, the constitutive equation of the source term expressing the local loss pressure drop of the liquid phase is modified, and a variable local flow resistance term of the liquid phase of the control valve is added; Step 4: Extract the control valve opening required for calculating the variable local flow resistance terms of the control valve vapor phase and liquid phase as the control interface parameter of the control valve model, and encapsulate the two control body models and one pipe model into a control valve model with a control interface and a fluid interface according to a staggered grid; Step 5: Connect the constructed control valve model with other thermal-hydraulic component models based on the two-fluid six-equation method and the controller model for opening control to build a simulation system to simulate the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

2. The control valve modeling method according to claim 1, characterized in that: The simplified pipeline model uses Modelica as the modeling language, and includes a main equation model, a constitutive equation model and a physical property equation model. The main equation model includes the mass equation, momentum equation, energy equation and non-condensable gas equation of the vapor phase and liquid phase. The constitutive equation model includes the wall friction equation, wall heat transfer equation, phase interface friction equation, phase interface heat transfer equation and phase interface mass exchange equation. The physical property equation model uses the standard formula IAPWS-97 for physical property parameters of water and water vapor to obtain multiple physical property parameters for calling by the main equation model and the constitutive equation model.

3. The control valve modeling method according to claim 1, characterized in that: The upstream chamber of the control valve throttle hole is mapped to the first control body model, the downstream chamber of the control valve throttle hole is mapped to the second control body, and the control valve throttle hole, that is, the valve core, is mapped to the takeover model.

4. The control valve modeling method according to claim 1, characterized in that: The variable local flow resistance term of the control valve vapor phase is: In formula 1, F′ Lg is the variable local flow resistance term of the control valve vapor phase in the vapor phase momentum equation of the takeover model, α g is the cavitation fraction of the fluid flowing through the valve, ρ g is the vapor density flowing through the valve, V g is the vapor phase flow rate flowing through the valve, HLOSG is the local flow resistance coefficient of the vapor phase of the control valve, and ΔL is the length of the pipe; The variable local flow resistance term of the control valve liquid phase is: In formula 2, F′ Lf is the variable local flow resistance term of the control valve liquid phase in the liquid phase momentum equation of the takeover model, α f is the liquid fraction flowing through the valve, ρ f is the density of the liquid phase flowing through the valve, V f is the liquid phase flow rate flowing through the valve, and HLOSSE is the local flow resistance coefficient of the vapor phase of the control valve.

5. The control valve modeling method according to claim 4, characterized in that: On the control valve takeover model, the expression of the vapor phase momentum equation of the control valve vapor phase variable local flow resistance term after discretization is ΔP Lg for: ΔP Lg = ΔL * F' Lg = α k ρ f * HLOSSF * V g Formula 3 The expression of the liquid phase momentum equation after discretization of the variable local flow resistance term of the vapor phase of the control valve is ΔP Lf for: ΔP Lf = ΔL * F' Lf = α k ρ f * HLOSSF * V f Formula Four.

6. The control valve modeling method according to claim 4, characterized in that: The control valve vapor phase local flow resistance coefficient HLOSG is: The control valve liquid phase local flow resistance coefficient HLOSSF is: In Formula 5 and Formula 6, ε is the variable local resistance coefficient of the control valve.

7. The control valve modeling method according to claim 6, characterized in that: The variable local resistance coefficient ε of the control valve is related to the flow rate of the control valve K V A monotonic relationship is formed, specifically: In the formula, A is the flow area of the control valve takeover model, in m 2 K is the count; V The flow rate of the control valve is the flow rate of the valve when the pressure difference across the valve is 100kPa, expressed in m 3 / h is counted.

8. The control valve modeling method according to claim 7, characterized in that: The control valve flow rate K V It is monotonically related to the control valve opening x, specifically: K V =K V,max f(x) Formula 8 In formula 8, x is the control valve opening, K V,max is the flow rate when the control valve is fully open, which is the characteristic parameter of the control valve; f(x) is the flow characteristic curve of the control valve, which expresses the change curve of the ratio of the flow rate corresponding to the current opening of the control valve to the flow rate when the control valve is fully open as the current opening of the control valve changes.

9. The control valve modeling method according to any one of claims 1 to 8, characterized in that: The control interface of the control valve model is connected to the external controller model. The parameter transmitted is the control valve opening, and the data transmitted is in the form of an analog value from 0 to 1. The control valve opening transmitted through the control interface is then transmitted to the control valve variable resistance local resistance coefficient calculation module, and then the calculation result of the control valve variable resistance local resistance coefficient is transmitted to the control valve vapor phase and liquid phase variable local flow resistance items to carry out related momentum equation calculations.

10. A control valve modeling system based on two-fluid six-equation method, characterized in that: include: The control valve node division module is used to structurally divide the control valve into two control bodies and a connecting pipe. The control bodies and connecting pipes adopt a staggered grid form. Control valve local flow resistance modeling module, used to add control valve variable local resistance terms to the control valve vapor and liquid phase momentum equations; The control valve variable local resistance coefficient calculation module is used to configure the control valve flow characteristic curve and the flow rate when the control valve is fully open, and then calculate the current flow rate of the control valve according to the current opening of the control valve, and then calculate the variable local resistance coefficient of the control valve; The control valve control interface modeling module is used to build the control interface of the control valve model and pass the control interface parameters as the valve opening to the variable local flow resistance items of the vapor phase and liquid phase of the control valve; The control valve model encapsulation module is used to construct the fluid interface of the control valve model and encapsulate the two control bodies and one connecting pipe of the control valve in the form of a staggered grid to form a control valve component model with a fluid interface and a control interface; The control valve model application module is used to connect the constructed control valve model with other thermal-hydraulic component models based on two-fluid six-equation and the controller model for opening control, build a simulation system, and realize the simulation of the thermal-hydraulic characteristics of the control valve under different working fluid states and different openings.

11. A computer device, characterized in that: The computer device includes at least a processor and a readable storage medium, wherein the readable storage medium stores a computer program, and when the computer program is executed by the processor, the control valve modeling method based on two-fluid six equations as described in any one of claims 1 to 9 is implemented.

12. A computer-readable storage medium having computer-executable instructions stored thereon, characterized in that: When the executable instructions are executed by the processor, the control valve modeling method based on two-fluid six equations as described in any one of claims 1 to 9 is implemented.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the control valve modeling method based on two-fluid six equations as described in any one of claims 1 to 9 is implemented.

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