Method and device for constructing dynamic model of thermodynamic system

Abstract

The invention provides a method and device for constructing a dynamic model of a thermodynamic system, and the method comprises the steps: determining a process frequency domain topology linear constraint and a frequency response function characteristic of a part based on the heat transfer, transportation and conversion process of a heat exchanger and related parts, and constructing a frequency domain heat flow model; constructing a frequency domain equivalent heat flow model based on the frequency domain heat flow model and the topological connection relationship between the components, and establishing an overall heat flow model control equation set by using the Kirchhoff's law; based on the working medium flowing process of the heat exchanger and related parts, the function relation between the pressure change and the mass flow of the working medium after the working medium flows through all power and / or resistance parts is determined, and a power resistance balance equation set of the working medium flowing process is established; the coupling relation between the working medium flow process and the heat transfer, transportation and conversion process is analyzed, a constraint equation set between the working medium pressure and the temperature is established, and a frequency domain overall model for dynamic analysis of the thermodynamic system provides powerful support for performance analysis and regulation and control of the dynamic process of the complex thermodynamic system.

Description

Technical Field

[0001] The present invention relates to the technical field of system modeling, and in particular to a method and device for constructing a dynamic model of a thermal system. Background Art

[0002] With the rapid development of renewable energy, how to efficiently absorb renewable energy and improve energy utilization has become a common focus in academia and industry. To achieve high-proportion and large-scale application of renewable energy, improve the flexibility of thermal systems, and develop electrical energy storage technologies, it is necessary to accurately characterize the dynamic characteristics of thermal systems and propose new, accurate modeling and efficient solution methods.

[0003] As an important component in the thermal system, the analysis method of the dynamic characteristics of the heat exchanger has an important impact on the modeling and solution of the overall dynamic characteristics of the thermal system. For the study of the dynamic characteristics of heat transfer and transport processes in the heat exchanger, the heat exchanger is generally divided into three parts: hot fluid, cold fluid and heat exchanger wall. The heat transfer equation between the three is introduced to solve the energy conservation differential equation of each part under non-steady-state conditions. However, considering the nonlinear characteristics of the convective heat transfer process itself and the mutual coupling between the energy equations, it is difficult to directly obtain the time domain analytical solution under arbitrary initial conditions and boundary conditions. Existing research can be divided into two categories. One is to make certain assumptions on the equations under specific initial conditions, simplify the equations, and then use analytical solution methods to obtain the dynamic response of the heat exchanger wall temperature and the fluid outlet temperature, such as the lumped parameter method, distributed parameter method, transient method, etc. -NTU, integration method, Laplace transform method; the other is based on numerical methods, using analytical combined with numerical solution or applying finite difference methods to solve the discretization of partial differential equations. However, there are often some problems when using these methods to analyze the dynamics of heat exchangers. The analytical solution requires the introduction of simplifications to the equations, which makes the characterization of dynamic characteristics inaccurate; and methods such as Laplace transform can only analyze dynamic responses under specific boundaries, and the application scenarios are limited. Although the numerical solution can analyze the dynamic heat transfer process more accurately, it requires the introduction of a large number of space and time nodes, which increases the complexity of solving the problem; in addition, the convergence of the solution format also has certain requirements on the space and time steps.

[0004] In summary, the nonlinearity of the dynamic model of the thermal system is the reason why it is difficult to apply it in the scheduling and optimization of integrated energy systems, and the use of limited simplified methods cannot fully reflect the heat transfer characteristics. To quickly analyze the dynamic characteristics of the thermal system, it is necessary to establish a system-wide model based on an efficient and accurate dynamic model of the heat transfer process. To this end, existing studies have developed a heat flow modeling method based on the heat exchanger thermal resistance method based on the linearization of the heat transfer process to establish an equivalent circuit model. However, the modeling process of this method is based on the time domain, and the heat exchanger needs to be divided into small sections to ensure the accuracy of the solution, which limits the application of this method in long-term, large-scale, and complex systems. Therefore, a system-wide model construction method that can accurately and efficiently solve the corresponding control equations of each component of the system is needed to achieve rapid analysis of the dynamic response of complex thermal systems. Summary of the Invention

[0005] The present invention provides a method and apparatus for constructing a dynamic model of a thermal system, addressing existing shortcomings in the physical modeling of thermal systems, such as the difficulty in handling the nonlinearity of heat exchange processes, which leads to low computational efficiency in dynamic simulations. This invention provides powerful support for the performance analysis and control of complex thermal system dynamic processes.

[0006] The present invention provides a method for constructing a dynamic model of a thermal system, comprising: determining the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, so as to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; constructing a frequency domain equivalent heat flow model of the entire thermal system based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, and establishing a group of control equations of the overall heat flow model using Kirchhoff's law; and constructing a frequency domain heat flow model of the entire thermal system based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components. and the working fluid flow process of related components, determine the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid, so as to establish the power resistance balance equation group of the working fluid flow process of the thermal system; by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, establish the constraint equation group between the working fluid pressure and temperature; jointly establish the control equation group of the heat flow model, the power resistance balance equation group and the constraint equation group between the working fluid pressure and temperature, so as to construct a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0007] According to a method for constructing a dynamic model of a thermal system provided by the present invention, the frequency domain topological linear constraints during the heat exchange process are determined, including: establishing a time domain partial differential equation group of the heat exchanger based on the energy conservation law of the hot fluid, the cold fluid and the wall; performing Fourier transform on the time domain partial differential equation group of the heat exchanger, eliminating the time partial differential terms, and decomposing the convolution terms of the coefficients and variables respectively, thereby determining the frequency response function matrix constraints of the heat exchanger, and establishing the frequency domain linear constraints of the heat exchanger inlet and outlet based on the frequency response characteristics.

[0008] According to a method for constructing a dynamic model of a thermal system provided by the present invention, considering the conditions of variable flow and variable physical properties, the frequency domain linear constraints of the inlet and outlet temperatures of the cold and hot fluids of the heat exchanger in the frequency domain and the frequency response function matrix are as follows: , , in, is the frequency domain representation of the hot fluid outlet temperature, is the frequency domain representation of the cold fluid outlet temperature, is the frequency domain representation of the hot fluid inlet temperature, is the frequency domain representation of the cold fluid inlet temperature, is the frequency domain representation of the hot fluid outlet temperature disturbance term, is the frequency domain representation of the cold fluid outlet temperature disturbance term, is the frequency response function matrix of the heat exchanger, 、 、 、 are parameters related to the heat exchanger and the cold and hot fluids, is the length of the heat exchanger.

[0009] According to a method for constructing a dynamic model of a thermal system provided by the present invention, the frequency domain linear constraints of the heat exchange amount of the cold and hot fluids of the heat exchanger and the inlet temperature in the frequency domain, and the frequency response function are: , , in, is the frequency domain representation of the heat transfer of the thermal fluid, is the frequency domain representation of the heat transfer of the cold fluid, is the frequency domain representation of the heat transfer disturbance term of the thermal fluid, is the frequency domain representation of the cold fluid heat transfer disturbance term, is the heat capacity flow of the thermal fluid, is the heat capacity flow of the cold fluid, is the frequency response function matrix between heat transfer and inlet temperature.

[0010] According to a method for constructing a dynamic model of a thermal system provided by the present invention, the frequency domain linear constraints of the heat exchanger components are: , in, 、 、 、 、 and is the frequency domain representation of the heat transfer of different components, are the elements of the frequency response function matrix of different components, is the frequency domain representation of the temperature of different components, Frequency domain representation of the disturbance term for the heat transfer of different components.

[0011] According to a method for constructing a dynamic model of a thermal system provided by the present invention, the method for establishing a group of dynamic resistance balance equations for the working fluid flow process of the thermal system includes: determining the pressure loss of the working fluid flow during the heat transfer process of the thermal system using the Darcy-Weisbach formula based on the flow rate and friction coefficient of the fluid in the heat exchanger; and establishing the relationship between the mass flow and speed of the compressor and turbine and the efficiency and the inlet and outlet enthalpy difference based on the characteristic parameters and component parameters of the working fluid flow, so as to establish the group of dynamic resistance balance equations for the working fluid flow process of the thermal system.

[0012] According to a method for constructing a dynamic model of a thermal system provided by the present invention, the establishment of a set of constraint equations between the working fluid pressure and the temperature includes: determining a thermodynamic dual-state variable based on the constraint relationship between the characteristic parameters of the working fluid flow and the temperature and pressure; determining the heat transfer coefficient between the working fluid flow and the wall surface based on the characteristic parameters of the working fluid flow and the heat transfer coefficient correlation formula; and establishing the set of constraint equations between the working fluid pressure and the temperature based on the thermodynamic dual-state variables and the heat transfer coefficient.

[0013] The present invention also provides a device for constructing a dynamic model of a thermal system, comprising: a frequency domain heat flow model construction unit, for determining the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, so as to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; a heat flow model control equation group establishment unit, for constructing a frequency domain equivalent heat flow model of the entire thermal system based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, and establishing the overall heat flow model control equation group using Kirchhoff's law; a dynamic resistance balance ... and a dynamic resistance balance equation group establishment unit, for constructing a frequency domain equivalent heat flow model of the entire thermal system based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components. The invention relates to a method for analyzing the working fluid flow process of the heat exchanger and related components in the thermal system, determining the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid, so as to establish the power resistance balance equation group of the working fluid flow process of the thermal system; a constraint equation group establishment unit between the working fluid pressure and temperature, used to establish the constraint equation group between the working fluid pressure and temperature by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process; a frequency domain overall model construction unit, used to jointly establish the heat flow model control equation group, the power resistance balance equation group and the constraint equation group between the working fluid pressure and temperature, so as to construct a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0014] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, any one of the above-described methods for constructing a dynamic model of a thermal system is implemented.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for constructing a dynamic model of a thermal system.

[0016] The present invention provides a method and device for constructing a dynamic model of a thermal system. Based on the heat transfer, transport and conversion processes of a heat exchanger and related components, the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components are determined to construct a frequency domain heat flow model; based on the frequency domain heat flow model and the topological connection relationship between the components, a frequency domain equivalent heat flow model is constructed, and Kirchhoff's law is used to establish a group of control equations for the overall heat flow model; based on the working fluid flow process of the heat exchanger and related components, the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid is determined, and a group of dynamic resistance balance equations for the working fluid flow process is established; the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process is analyzed, and a group of constraint equations between the working fluid pressure and temperature is established. The frequency domain overall model for dynamic analysis of thermal systems provides strong support for performance analysis and regulation of the dynamic processes of complex thermal systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a flow chart of a method for constructing a dynamic model of a thermal system provided by the present invention.

[0019] Figure 2 Schematic diagram of the countercurrent heat exchanger provided by the present invention.

[0020] Figure 3 It is a schematic diagram of the frequency domain heat flow model of the countercurrent heat exchanger provided by the present invention.

[0021] Figure 4 It is a schematic diagram of the flow mixing process provided by the present invention.

[0022] Figure 5 It is a schematic diagram of the heat-to-work conversion process provided by the present invention.

[0023] Figure 6 It is a schematic diagram of the thermal system provided by the present invention.

[0024] Figure 7 It is a schematic diagram of the frequency domain analysis model of the thermal system provided by the present invention.

[0025] Figure 8 It is a structural schematic diagram of a thermal system dynamic model building device provided by the present invention.

[0026] Figure 9 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] In order to solve the problem of the difficulty in handling the nonlinearity of heat exchange processes in the construction of thermal system physical models in the prior art, which leads to low efficiency in model dynamic simulation calculations, the present invention provides a method for constructing a dynamic model of a thermal system. For the common heat transfer, transport and conversion processes in thermal systems, such as heat exchanger heat transfer processes, separation processes, mixing processes and heat-to-work conversion processes, the method first classifies them through characteristic time analysis, and then focuses on modeling the dynamic processes of the heat exchanger. Starting from the partial differential control equation, the frequency domain topological linear constraints and frequency response function characteristics of the components are established for different processes, and the frequency domain heat flow model of the component-level heat transfer, transport and conversion processes is obtained. Combined with the topological connection relationship between components, from the perspective of heat transport and heat transfer, the perspective of working fluid flow, and the perspective of coupling with physical properties, a complete overall dynamic analysis model of the thermal system under physical property change conditions is constructed. Based on the frequency domain equivalent heat flow model of the entire thermal system, Kirchhoff's law is used to establish the overall heat flow model control equation group, thereby clarifying the overall law of heat transfer, transport and conversion in the system. From the perspective of working fluid flow, the functional relationship between the pressure change after the working fluid passes through each power and resistance component and its mass flow rate is analyzed. Combining these functional relationships, a set of dynamic and resistance balance equations can be constructed in each branch of the system, thereby quantitatively describing the pressure distribution of the working fluid. Furthermore, in thermal systems, physical properties constrain temperature and pressure, forming a system constraint from the perspective of physical property coupling with temperature and pressure. Therefore, this coupling relationship manifests itself in the constraint relationship between working fluid pressure and temperature. By analyzing the coupling relationship between the working fluid flow process and the heat transfer and conversion process, a set of constraint equations for working fluid pressure and temperature is established. By combining the aforementioned heat flow model control equations, dynamic and resistance balance equations, constraint equations for physical properties and working fluid temperature and pressure, and constraint equations for working fluid pressure and temperature, a complete overall dynamic analysis model of the thermal system is constructed. The present invention uses Fourier transforms and matrix operations to determine the overall laws of heat transfer, transport, and conversion in the system, thereby obtaining a complete overall dynamic analysis model of the thermal system. This method provides powerful support for performance analysis and effective control of the dynamic processes of complex thermal systems.

[0029] Please refer to Figure 1 , Figure 1 A schematic flow chart of a method for constructing a dynamic model of a thermal system provided by the present invention.

[0030] The present invention provides a method for constructing a dynamic model of a thermal system, comprising: 101: Based on the heat transfer, transport and conversion processes of heat exchangers and related components in thermal systems, determine the process frequency domain topology linear constraints and the frequency response function characteristics of the components to construct a frequency domain heat flow model for component-level heat transfer, transport and conversion processes.

[0031] As a preferred embodiment, the frequency domain topological linear constraints during the heat exchange process are determined, including: establishing a time domain partial differential equation group of the heat exchanger based on the energy conservation law of the hot fluid, cold fluid and wall surface; performing Fourier transform on the time domain partial differential equation group of the heat exchanger, eliminating the time partial differential terms, and decomposing the convolution terms of the coefficients and variables respectively, thereby determining the frequency response function matrix constraints of the heat exchanger, and establishing the frequency domain linear constraints of the heat exchanger inlet and outlet based on the frequency response characteristics.

[0032] In this embodiment, the frequency response constraints for the heat exchanger are established based on the Fourier transform and perturbation decomposition method of a system of partial differential equations. Frequency-domain linear constraints are established at the heat exchanger inlet and outlet based on the frequency response characteristics, thereby obtaining a frequency-domain heat flow model. This facilitates the establishment of a frequency-domain analysis model for the entire system. A steady-state model is used for the mixing process and the heat-to-work conversion process, as their characteristic times are shorter than those of the heat exchanger. Energy conservation constraints and process constraints are used to determine the temperature changes at the working fluid inlet and outlet, as well as the work exchanged with the external environment, to generate a frequency-domain heat flow model.

[0033] Please refer to Figure 2 , Figure 2 Schematic diagram of the countercurrent heat exchanger provided by the present invention.

[0034] The countercurrent flat plate heat exchanger is used as an example to illustrate this. The same method can be used for other types of heat exchangers.

[0035] According to the energy conservation law of hot fluid, cold fluid and wall, the control equation of the heat exchanger can be established: , in, C c and C h are the products of the local fluid mass and the specific heat capacity at constant pressure of the cold and hot fluids respectively; G c and G h are the heat capacity flows of cold and hot fluids respectively; ( kA ) h and( kA ) c are the thermal conductivities on the hot and cold fluid sides of the heat exchanger, respectively; Mc p is the product of the heat exchanger wall mass and its specific heat capacity, k is the heat transfer coefficient, A is the heat exchange area, T c is the temperature of the cold fluid, T w is the temperature of the heat exchanger wall, t For time,L is the pipe length.

[0036] Regarding equations (1)-(3) t Performing Fourier transform and eliminating the time partial differential term, we can obtain the following ordinary differential boundary value problem: Where j is the imaginary unit, is the frequency component, and the variable with the wavy line “~” on it represents the Fourier transform of the original variable. ” indicates convolution.

[0037] The convolution terms of coefficients and variables in equations (4)-(6) make the equations highly nonlinear and difficult to solve analytically. The present invention selects time 0 as the benchmark, decomposes any variable into the benchmark value and its disturbance term, and converts the variable to be solved into T h , T c , T w and parameters G c , G h , , , , break down. It is defined as the hot and cold fluid and wall temperatures that satisfy the constant flow constant property heat exchanger control equation, that is, the solution of the basic equation. That is, the difference between the actual temperature and the defined temperature, the solution of the perturbation equation.

[0038] Defined as the hot and cold fluid and wall temperatures satisfying the following partial differential equations with constant coefficients: because is the solution of the system of partial differential equations with constant coefficients, which is easy to obtain. Substitute (6) into (4) and (5), and put the remaining convolution terms into the inhomogeneous terms. For the temperature equations of cold and hot fluids, they can be unified as: in, f h and f c is a nonhomogeneous term: (11) in, and is a parameter related to thermal conductivity, bw and b w is a parameter related to the wall thermal conductivity and fluid temperature.

[0039] (12) The expressions of the cold and hot fluid temperatures of the heat exchanger in the frequency domain can be obtained by formula (10), that is, (13) in, C 1, C 2 is the unknown coefficient, which can be determined by the boundary conditions, Q is the eigenvector matrix of the coefficient matrix, K h , K c is the temperature response of the particular solution to the nonhomogeneous terms of the equation.

[0040] When the flow rates of hot and cold fluids in the heat exchanger remain unchanged, the nonhomogeneous terms in equation (10) are 0. K h and K c is also 0, and the formula (30) gives The frequency domain analytical solution is the temperature of the hot and cold fluids. When considering the flow rate or physical property changes, f h and f c There are convolution terms in , which makes it difficult to obtain K h and K c The analytical form of , needs to be solved numerically.

[0041] Substitution x =0 and x = L After calculating the temperatures of the cold and hot fluids, they can be organized into a matrix form.

[0042] As a preferred embodiment, considering the case of variable flow and variable physical properties, the frequency domain linear constraints of the inlet and outlet temperatures of the cold and hot fluids of the heat exchanger in the frequency domain and the frequency response function matrix are: (14) (15) in, is the frequency domain representation of the hot fluid outlet temperature, is the frequency domain representation of the cold fluid outlet temperature, is the frequency domain representation of the hot fluid inlet temperature, is the frequency domain representation of the cold fluid inlet temperature, is the frequency domain representation of the hot fluid outlet temperature disturbance term, is the frequency domain representation of the cold fluid outlet temperature disturbance term, is the frequency response function matrix between the inlet and outlet temperatures of the heat exchanger, 、 、 、 are parameters related to the heat exchanger and the cold and hot fluids, is the length of the heat exchanger. The influence of variable physical properties and variable flow on frequency domain temperature is included in the disturbance term of outlet temperature.

[0043] For the sake of simplicity, the parameters are defined as follows: (16) Combined with the relationship between the heat transfer of hot and cold fluids, Q h and Q c The heat exchange between the hot and cold fluids and the wall is obtained. The constraint relationship between the inlet temperature and the heat exchange is obtained in the frequency domain.

[0044] As a preferred embodiment, the frequency domain linear constraints of the heat exchange amount of the cold and hot fluids of the heat exchanger and the inlet temperature in the frequency domain, as well as the frequency response function are: (17) (18) in, is the frequency domain representation of the heat transfer between the hot fluid and the wall, is the frequency domain representation of the heat transfer between the cold fluid and the wall, is the frequency domain representation of the heat transfer disturbance term of the thermal fluid, is the frequency domain representation of the cold fluid heat transfer disturbance term, is the frequency response function matrix between heat transfer and inlet temperature. Similarly, the influence of variable physical properties and flow on frequency domain heat transfer is included in the disturbance term of heat transfer.

[0045] Please refer to Figure 3 , Figure 3 Schematic diagram of the frequency domain heat flow model of the countercurrent heat exchanger provided by the present invention.

[0046] In the frequency domain dynamic heat flow model of the heat exchanger, the difference in the inlet temperature of the hot and cold fluids and the heat transfer amount in the frequency domain are analogized to the voltage and current in the circuit, respectively. Equation (17) can be represented as a linear two-port network in the circuit, using Type equivalent circuit representation.

[0047] Frequency domain and is a flow-controlled voltage source, i.e., the temperature change of hot and cold fluids under constant flow and constant physical properties; its value is determined by the heat transfer Q h 0 and Q c 0 OK. Likewise, and is the flow-controlled voltage source, that is, the temperature change of hot and cold fluids under variable flow and variable physical properties. Among the equivalent parameters, admittance Y 1~ Y 3 and current source They respectively characterize the dynamic heat transfer resistance, hot fluid heat storage, cold fluid heat storage and wall heat storage, and are lumped expressions in the frequency domain.

[0048] (19) Please refer to Figure 4 , Figure 4 Schematic diagram of the flow mixing process provided by the present invention.

[0049] For the working fluid mixing process, the working fluid at mixing point 1 and the working fluid at mixing point 2 are mixed as the outlet. It is assumed that the pressure before and after mixing is consistent and the total enthalpy value is equal. According to the law of conservation of energy in the mixing process and physical property constraints, it can be obtained: (20) in, h is the enthalpy of the working fluid, T 、 p are the temperature and pressure of the working fluid, respectively. The subscripts mix1, mix2, and out represent the mixing points 1, 2, and the outlet, respectively.

[0050] Analogous to the electromotive force in the circuit, use two additional thermal motive forces and The temperature changes before and after the two working fluids are mixed are represented respectively, and the frequency domain heat flow model of the mixing process can be obtained.

[0051] (twenty one) in, is the difference between the outlet temperature of the hot fluid and the temperature of mixing point 1 in the frequency domain, is the difference between the outlet temperature of the cold fluid and the temperature of mixing point 2 in the frequency domain. Since the flow separation process does not change the temperature and pressure, the temperature and pressure before and after are the same, so the coefficient matrix corresponding to the heat transfer constraint equation is one, and the temperature difference before and after separation is 0.

[0052] Please refer to Figure 5 , Figure 5 Schematic diagram of the heat-to-work conversion process provided by the present invention.

[0053] The heat-to-work conversion process is exemplified by the compressor, and the turbine is similar. The internal working process of the compressor is a variable process, but due to the large flow rate and high flow rate of the working medium during the working process, the heat transfer process cannot be completed in a short time, so it can generally be regarded as an adiabatic process. The process constraints are (twenty two) in, s is the entropy of the working fluid flow, is the adiabatic compression efficiency of the compressor. The subscripts in and out represent the inlet and outlet of the component, respectively. s and enthalpy h About temperature T and pressure p The implicit constraint relationship also needs to be determined based on the physical property database.

[0054] The outlet temperature can be further determined from the outlet enthalpy and pressure: (twenty three) According to the energy conservation constraint, the compressor power consumption W C for (twenty four) in m is the mass flow rate.

[0055] Analogous to the electromotive force in the circuit, use the additional thermal motive force Indicates the temperature change of the working fluid inlet and outlet in the compressor, and the temperature control heat flow source W C The heat of the working fluid injected into the system by adiabatic compression is expressed, and the frequency domain heat flow model of the heat-to-work conversion process is obtained.

[0056] (25) Where F represents the Fourier transform of the variable.

[0057] Please refer to Figure 6 , Figure 6 Schematic diagram of the thermal system provided by the present invention.

[0058] The thermal system primarily consists of two heat storage tanks (HT1 and HT2), two cold storage tanks (LT1 and LT2), a compressor, an expander (turbine), a heat absorber, a cooler, a regenerator, and an electric motor / generator. During discharge, the system operates in heat engine mode based on the positive Brayton cycle. A high-temperature, high-pressure working fluid enters the expander, performs work, and drives the generator to generate electricity. During this process, the working fluid absorbs heat from the high-temperature heat source and releases it to the low-temperature heat source, transferring heat from the heat storage tank to the cold storage tank. During charging, the system operates in heat pump mode based on the reverse Brayton cycle. The compressor, driven by the electric motor, uses off-peak electricity or waste wind / photovoltaic power to drive the working fluid to absorb heat from the low-temperature heat source and release it to the high-temperature heat source. Heat is transferred from the cold storage tank to the hot storage tank, converting electrical energy into thermal energy that is stored in the energy storage medium.

[0059] Please refer to Figure 7 , Figure 7 This is a schematic diagram of the frequency domain analysis model of the thermal system provided by the present invention.

[0060] In the frequency-domain heat flow model of the thermal system, each node is represented by serial numbers 1 to 7 and h and c, and the lines between components are connected by solid arrows, which indicate the flow direction of the fluid (taking the heat engine model as an example). T hin and T cin are the inlet temperatures of the high temperature heater and cooler, respectively.

[0061] Based on the frequency domain heat flow model, an overall equivalent heat flow model of the thermal system regarding heat transfer, transport and conversion is constructed.

[0062] The frequency domain response characteristic expressions of the three heat exchangers, namely the absorber, regenerator and cooler, are: As a preferred embodiment, the frequency response function characteristics of the heat exchanger component are: (26) in, 、 、 、 、 and is the frequency domain representation of the heat transfer at different nodes, are the elements of the frequency response function matrix of different components, is the frequency domain representation of the temperature of different nodes, It is the frequency domain representation of the heat transfer disturbance term at different nodes.

[0063] 102: Based on the frequency domain heat flow model of component-level heat transfer, transport and conversion processes and the topological connection relationship between components, a frequency domain equivalent heat flow model of the entire thermal system is constructed, and Kirchhoff's law is used to establish the control equation group of the overall heat flow model.

[0064] In this embodiment, based on the overall equivalent heat flow model, Kirchhoff's law is used to establish the overall heat flow model control equations, thereby explaining the overall laws of heat transfer, transportation and conversion in the system.

[0065] The equivalent heat flow models of each independent component are connected through the corresponding isothermal points to construct the overall equivalent heat flow model of the thermal system; the relationship between the temperatures of each node can be written according to Kirchhoff's voltage law: (27) in, , , , , , is the frequency domain representation of the temperature of different nodes, is the thermokinetic potential, which represents the change in temperature. The expressions of the thermokinetic potential of different nodes (2, 3, 5, 6) are: (28) , (29) in and is the thermodynamic force of the compressor and turbine, which represents the difference in frequency domain temperature between the inlet and outlet of the heat-to-work conversion component.

[0066] According to the above analysis, the transfer, transport and conversion of heat in the system are described by introducing equivalent elements such as admittance, thermodynamic potential and energy source. The equivalent heat flow models of each component are connected according to the corresponding isothermal points to construct the overall equivalent heat flow model of the thermal system.

[0067] As can be seen, the frequency response function matrix of the heat exchanger's dynamic heat transfer process transforms and separates the time-domain partial differential equations into linear topological constraints and nonlinear element constraints representing the outlet and inlet temperatures of the cold and hot fluids. Mathematically, both linear and explicit nonlinear equations are easily solved. Therefore, the introduction of the heat flow model improves the nonlinear nature of the system's mathematical model, facilitating subsequent model solutions.

[0068] In practical applications, it is also necessary to convert the time domain initial and boundary conditions (inlet temperature) to the frequency domain and the frequency domain solution results to the time domain. In numerical calculations, the time domain series of the inlet cold and hot fluid temperatures can be converted into the sum of a set of sine / cosine signals with known frequencies through discrete Fourier transform: (30) The left sides of the equation are and No. k frequency domain components, t i is the sampling moment, the angular frequency ω 0=2π / τ , is the sampling period. n t is the total number of sampling moments, which includes a period of historical data of boundary conditions to reflect the influence of the initial state of each variable in the system at time 0. In numerical calculations, the fast Fourier transform (FFT) algorithm is usually used to calculate Equation (30).

[0069] Combined with the frequency domain model, the outlet temperatures of the cold and hot fluids are solved at the angular frequency kω 0 frequency domain components and According to the superposition theorem of linear systems, the sampling time t i The output is (31) in, n f is the number of frequency components, and Re is the operation of taking the real part of a complex number. This yields the time-domain values ​​of the outlet temperatures of the cold and hot fluids at each discrete sampling moment. In this calculation, Equation (31) is often calculated using an inverse fast Fourier transform (IFFT).

[0070] 103: Based on the working fluid flow process of the heat exchanger and related components in the thermal system, determine the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid, so as to establish the dynamic resistance balance equation group of the working fluid flow process of the thermal system.

[0071] As a preferred embodiment, a group of dynamic resistance balance equations for the working fluid flow process of the thermal system is established, including: determining the pressure loss of the working fluid flow during the heat transfer process of the thermal system using the Darcy-Weisbach formula based on parameters such as the flow rate and friction coefficient of the fluid in the heat exchanger; establishing the relationship between the mass flow and speed of the compressor and turbine and the efficiency and the inlet and outlet enthalpy difference based on the characteristic parameters of the working fluid flow and component parameters, so as to establish a group of dynamic resistance balance equations for the working fluid flow process of the thermal system.

[0072] In this embodiment, during the actual operation of a thermal system, heat transfer, transport, and conversion are dependent on the flow of the fluid. Therefore, it is necessary to establish working fluid flow constraints within the thermal cycle, as well as heat-to-work conversion constraints, from the perspective of the working fluid flow. From this perspective, the functional relationship between the pressure change of the working fluid after passing through each power and resistance component and its mass flow rate is analyzed. Combining these functional relationships, a system of dynamic and resistance balance equations can be constructed for each branch of the system, thereby quantitatively describing the pressure distribution of the working fluid.

[0073] The above analysis explains the overall heat transfer, transport, and conversion laws in the system from the perspective of heat flow. However, during system operation, the heat transfer, transport, and conversion depend on the flow process of the fluid. Therefore, to construct a complete mathematical model of the system, it is necessary to analyze the power / resistance balance relationship within the closed loop from the perspective of the working fluid flow.

[0074] Preferably, when obtaining the characteristics of the fluid during the heat transfer process, the pressure distribution in the heat exchanger should be considered. For convenience, an approximate estimate is made here based on engineering experience, namely the Darcy-Weisbach formula: the pressure loss of the fluid through the entire heat exchanger is proportional to the square of the flow rate, expressed as (32) in, f is the friction coefficient; D is the hydraulic diameter of the flow channel; is the fluid density, u f is the flow rate of the fluid; Preferably, the relationship between the mass flow rate of the circulating working fluid and its pressure before and after the heat-work conversion component can be described by a functional relationship. Due to the implicit iterative relationship between physical properties and temperature and pressure, it is necessary to establish momentum and energy equations for the turbine and solve them simultaneously. However, in order to facilitate the simulation of non-designed thermodynamic cycle models, the compressor model is often simplified to a functional relationship between the dimensionless flow rate of the radial compressor and the ideal pressure head coefficient. The dimensionless flow expression is (33) in, is the fluid density at the compressor inlet, D is the diameter of the rotor in the compressor (also called the "compressor diameter"), U is the rotor tip speed.

[0075] (34) in, π is pi ，N represents the shaft speed in radians per second. The ideal head coefficient is the dimensionless pressure rise across the compressor and is defined as follows: (35) in, is the isentropic specific enthalpy rise through the compressor. The flow coefficient and head coefficient are derived by applying Buckingham's Pi theorem and are commonly used to describe compressor performance.

[0076] The experimentally measured compressor performance graph is folded into two curves. Generally, a fourth-order polynomial is used to fit the relationship between efficiency and head coefficient, flow coefficient and speed respectively. The efficiency relationship is: (36) The lift coefficient relationship can be written as: (37) Preferably, similar to compressors, radial turbines in thermal systems are often simplified models. However, since the mass flow rate through a radial turbine strongly depends on the inlet conditions and outlet pressure, and weakly depends on the shaft speed depending on the blade and nozzle design, the turbine is modeled as a constant area unobstructed nozzle, and the relationship is: (38) in, A nozzle is the effective nozzle area, which results in the mass flow rate ( m ) and injection velocity ( C s ) and is based on the turbine geometry.

[0077] The ejection velocity is the velocity that the fluid would reach if it were to isentropically expand to the outlet pressure in an ideal nozzle, and is calculated using the following formula: (39) The turbine is modeled as a constant area unobstructed nozzle, assuming that most of the isentropic enthalpy change in radial inflow into the turbine occurs through the nozzle of the turbine rather than along the blades.

[0078] An important characteristic of radial turbine performance is the blade tip speed ( U ) and the jet velocity ( C s ), also known as the speed ratio v : (40) The meaning of each parameter is similar to that of the compressor. Ideal efficiency of radial turbine η ideal and the speed ratio, which takes into account blade geometry and loading. For a well-designed turbine with a low load factor, the relationship simplifies to: (41) It is easy to see that the maximum efficiency occurs at a speed ratio of 0.707. However, the ideal efficiency does not take into account other losses associated with the turbine (e.g., flow losses, etc.). To account for these losses in the semi-empirical model, the efficiency of the turbine is calculated by multiplying the ideal efficiency by the turbine design point efficiency (design). ): (42) 104: By analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, a set of constraint equations between the working fluid pressure and temperature is established.

[0079] As a preferred embodiment, a set of constraint equations between the working fluid pressure and temperature is established, including: determining the thermodynamic dual-state variables based on the constraint relationship between the characteristic parameters of the working fluid flow and the temperature and pressure; determining the heat transfer coefficient between the working fluid flow and the wall surface based on the characteristic parameters of the working fluid flow and the heat transfer coefficient correlation formula; and establishing a set of constraint equations between the working fluid pressure and temperature based on the thermodynamic dual-state variables and the heat transfer coefficient.

[0080] In this embodiment, the constraints between physical properties and temperature and pressure in a thermal system constitute system constraints from the perspective of physical properties coupling temperature and pressure. Therefore, this coupling relationship manifests itself in the constraints between working fluid pressure and temperature. By analyzing the coupling relationship between the working fluid flow process and the heat transfer and conversion process, a set of constraint equations for working fluid pressure and temperature is established.

[0081] Preferably, as an influencing factor of the heat transfer performance of the heat exchanger, the fluid properties (i.e., constant pressure specific heat c p ,density , viscosity , Convective thermal conductivity and Prandtl number Pr) with temperature and pressure, and the coupling relationship can be derived as a dual-state variable in thermodynamics.

[0082] (43) In addition, based on the relationship between the heat transfer coefficient and other properties, the heat transfer coefficient between the fluid and the wall k f for (44) Equations (43) and (44) are both nonlinear implicit system-level constraints that characterize the coupling relationship between fluid properties and temperature and pressure.

[0083] 105: Combine the heat flow model control equations, the dynamic resistance balance equations, and the constraint equations between the working fluid pressure and temperature to construct a frequency domain overall model for dynamic analysis of a variable property and variable flow thermal system.

[0084] In this embodiment, the heat flow model control equations, the dynamic resistance balance equations, and the constraint equations between the working fluid pressure and temperature are combined to construct a complete overall dynamic analysis model of the thermal system.

[0085] The embodiment of the present invention provides a clear and standardized method for constructing a dynamic model of a thermal system based on frequency domain analysis. Starting from the perspectives of heat transfer, transport and conversion and working fluid flow, coupled with physical property constraint analysis, a frequency domain overall model for dynamic analysis of a thermal system with variable physical properties and variable flow is obtained, which is conducive to accurate and rapid solution and regulation of complex thermal systems.

[0086] The following describes the thermal system dynamic model construction device provided by the present invention. The thermal system dynamic model construction device described below and the thermal system dynamic model construction method described above can be referenced to each other.

[0087] Please refer to Figure 8 , Figure 8 This is a structural schematic diagram of a thermal system dynamic model building device provided by the present invention.

[0088] The present invention also provides a device for constructing a dynamic model of a thermal system, comprising: a frequency domain heat flow model construction unit 801, for determining the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, so as to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; a heat flow model control equation group establishment unit 802, for constructing a frequency domain equivalent heat flow model of the entire thermal system based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, and establishing the heat flow model control equation group using Kirchhoff's law; a dynamic resistance balance equation group establishment unit 803, using Based on the working fluid flow process of the heat exchanger and related components in the thermal system, the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid is determined to establish the power resistance balance equation group of the working fluid flow process of the thermal system; the constraint equation group establishment unit 804 between the working fluid pressure and temperature is used to establish the constraint equation group between the working fluid pressure and temperature by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process; the frequency domain overall model construction unit 805 is used to jointly establish the heat flow model control equation group, the power resistance balance equation group and the constraint equation group between the working fluid pressure and temperature, so as to construct a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0089] Figure 9 The following is a schematic diagram of the structure of an electronic device, such as Figure 9As shown, the electronic device may include: a processor 901, a communications interface 902, a memory 903 and a communication bus 904, wherein the processor 901, the communications interface 902 and the memory 903 communicate with each other via the communication bus 904. The processor 901 may call the logic instructions in the memory 903 to execute a method for constructing a dynamic model of a thermal system, the method comprising: based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, determining the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, constructing a frequency domain equivalent heat flow model of the entire thermal system, and using Kirchhoff's law to establish the overall heat flow model control. Establish a group of equations; based on the working fluid flow process of the heat exchanger and related components in the thermal system, determine the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid, so as to establish the dynamic resistance balance equations of the working fluid flow process of the thermal system; by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, establish a group of constraint equations between the working fluid pressure and temperature; jointly establish the heat flow model control equations, the dynamic resistance balance equations and the constraint equations between the working fluid pressure and temperature, so as to construct a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0090] Furthermore, the logic instructions in the aforementioned memory 903 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product, stored in a storage medium, includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0091] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the method for constructing a dynamic model of a thermal system provided by the above methods. The method includes: based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, determining the process frequency domain topological linear constraints and the frequency response function characteristics of the components to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, constructing a whole thermal system dynamic model. The frequency domain equivalent heat flow model of the body is constructed, and the control equations of the overall heat flow model are established using Kirchhoff's law; based on the working fluid flow process of the heat exchanger and related components in the thermal system, the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid is determined to establish the power resistance balance equations of the working fluid flow process of the thermal system; by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, the constraint equations between the working fluid pressure and temperature are established; the heat flow model control equations, the power resistance balance equations and the constraint equations between the working fluid pressure and temperature are combined to construct the frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0092] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the method for constructing a dynamic model of a thermal system provided by the above methods, the method comprising: based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, determining the process frequency domain topological linear constraints and the frequency response function characteristics of the components to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; based on the frequency domain heat flow model of the component-level heat transfer, transport and conversion process and the topological connection relationship between components, constructing a frequency domain equivalent heat flow model of the entire thermal system, and Kirchhoff's law is used to establish the control equations of the overall heat flow model; based on the working fluid flow process of the heat exchanger and related components in the thermal system, the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid is determined to establish the power resistance balance equations of the working fluid flow process of the thermal system; by analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, the constraint equations between the working fluid pressure and temperature are established; the heat flow model control equations, the power resistance balance equations and the constraint equations between the working fluid pressure and temperature are combined to construct a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

[0093] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0094] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for constructing a dynamic model of a thermal system, characterized in that: include: Based on the heat transfer, transport, and conversion processes of heat exchangers and related components in thermal systems, determine the process frequency domain topology linear constraints and the frequency response function characteristics of the components to construct a frequency domain heat flow model for component-level heat transfer, transport, and conversion processes; Based on the frequency-domain heat flow model of the component-level heat transfer, transport, and conversion process and the topological connection relationship between components, a frequency-domain equivalent heat flow model of the entire thermal system is constructed, and Kirchhoff's law is used to establish the control equations of the overall heat flow model; Based on the working fluid flow process of the heat exchanger and related components in the thermal system, the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid is determined to establish the dynamic resistance balance equations of the working fluid flow process in the thermal system; By analyzing the coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process, a set of constraint equations between the working fluid pressure and temperature is established; The heat flow model control equations, the power resistance balance equations and the constraint equations between the working fluid pressure and temperature are combined to construct a frequency domain overall model for dynamic analysis of a variable property and variable flow thermodynamic system.

2. The method for constructing a dynamic model of a thermal system according to claim 1, wherein: Determine frequency-domain topological linear constraints between heat transfer processes, including: According to the energy conservation law of hot fluid, cold fluid and wall, considering the variable flow rate and variable physical properties, the time domain partial differential equations of the heat exchanger are established; By performing Fourier transform on the time-domain partial differential equations of the heat exchanger, the time partial differential terms are eliminated, and the convolution terms of the coefficients and variables are decomposed separately, the frequency response function matrix constraints of the heat exchanger are determined, and the frequency-domain linear constraints of the heat exchanger inlet and outlet are established based on the frequency response characteristics.

3. The method for constructing a dynamic model of a thermal system according to claim 2, characterized in that Considering the case of variable flow and variable physical properties, the frequency domain linear constraints of the inlet and outlet temperatures of the cold and hot fluids of the heat exchanger in the frequency domain, as well as the frequency response function matrix are: ， ， in, is the frequency domain representation of the hot fluid outlet temperature, is the frequency domain representation of the cold fluid outlet temperature, is the frequency domain representation of the hot fluid inlet temperature, is the frequency domain representation of the cold fluid inlet temperature, is the frequency domain representation of the hot fluid outlet temperature disturbance term, is the frequency domain representation of the cold fluid outlet temperature disturbance term, is the frequency response function matrix between the inlet and outlet temperatures of the heat exchanger, 、 、 、 are parameters related to the heat exchanger and the cold and hot fluids, is the length of the heat exchanger.

4. The method for constructing a dynamic model of a thermal system according to claim 3, characterized in that: The frequency domain linear constraints of the heat exchanger's cold and hot fluid heat transfer and inlet temperature in the frequency domain, as well as the frequency response function are: ， ， in, is the frequency domain representation of the heat transfer of the thermal fluid, is the frequency domain representation of the heat transfer of the cold fluid, is the frequency domain representation of the heat transfer disturbance term of the thermal fluid, is the frequency domain representation of the cold fluid heat transfer disturbance term, is the heat capacity flow of the thermal fluid, is the heat capacity flow of the cold fluid, is the frequency response function matrix between heat transfer and inlet temperature.

5. The method for constructing a dynamic model of a thermal system according to claim 2, wherein: The frequency domain linear constraints of the heat exchanger components are: ， in, 、 、 、 、 and is the frequency domain representation of the heat transfer of different components, are the elements of the frequency response function matrix of different components, is the frequency domain representation of the temperature of different components, Frequency domain representation of the disturbance term for the heat transfer of different components.

6. The method for constructing a dynamic model of a thermal system according to claim 1, wherein: The dynamic resistance balance equations for establishing the working medium flow process of the thermodynamic system include: According to the flow rate and friction coefficient of the fluid in the heat exchanger, the Darcy-Weisbach formula is used to determine the pressure loss of the working fluid during the heat transfer process of the thermodynamic system; According to the characteristic parameters of the working fluid flow and the component parameters, the relationship between the mass flow and speed of the compressor and turbine and the efficiency and the inlet and outlet enthalpy difference is established to establish the dynamic resistance balance equation group of the working fluid flow process of the thermodynamic system.

7. The method for constructing a dynamic model of a thermal system according to any one of claims 1 to 6, characterized in that: The establishment of the constraint equations between the working fluid pressure and temperature includes: Determine the thermodynamic dual-state variables based on the constraints between the characteristic parameters of the working fluid flow and the temperature and pressure; Determine the heat transfer coefficient between the working fluid and the wall surface based on the characteristic parameters of the working fluid and the heat transfer coefficient correlation formula; A set of constraint equations between the working fluid pressure and temperature is established based on the thermodynamic dual-state variables and the heat transfer coefficient.

8. A device for constructing a dynamic model of a thermal system, characterized in that: include: The frequency domain heat flow model construction unit is used to determine the frequency domain topological linear constraints of the process and the frequency response function characteristics of the components based on the heat transfer, transport and conversion process of the heat exchanger and related components in the thermal system, so as to construct a frequency domain heat flow model of the component-level heat transfer, transport and conversion process; a heat flow model control equations establishing unit, configured to construct a frequency-domain equivalent heat flow model of the entire thermal system based on the frequency-domain heat flow model of the component-level heat transfer, transport, and conversion process and the topological connection relationship between components, and to establish the overall heat flow model control equations using Kirchhoff's law; A power and resistance balance equations establishment unit is used to determine the functional relationship between the pressure change of the working fluid after flowing through each power and / or resistance component and the mass flow rate of the working fluid based on the working fluid flow process of the heat exchanger and related components in the thermal system, so as to establish the power and resistance balance equations of the working fluid flow process of the thermal system; a unit for establishing a set of constraint equations between working fluid pressure and temperature, configured to establish a set of constraint equations between working fluid pressure and temperature by analyzing a coupling relationship between the working fluid flow process and the heat transfer, transport and conversion process; The frequency domain overall model construction unit is used to jointly establish the heat flow model control equations, the dynamic resistance balance equations and the constraint equations between the working fluid pressure and temperature, thereby constructing a frequency domain overall model for dynamic analysis of the variable physical property and variable flow thermal system.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the method for constructing a dynamic model of a thermal system according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for constructing a dynamic model of a thermal system according to any one of claims 1 to 7 is implemented.

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