Brayton cycle system construction method based on compressor characteristic curve and gas turbine theoretical model

Abstract

A method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model solves the problems of large computational amount and high complexity existing in the building process of the existing Brayton system. According to the physical and chemical properties of the helium-xenon mixed gas, the present invention constructs a coolant physical property calculation model; according to the flow and heat transfer characteristics of the helium-xenon mixed gas, constructs a flow and heat transfer calculation model; constructs a mathematical and physical model of the sub-devices of the Brayton cycle system based on the three major conservation laws, separately stabilizes the mathematical and physical models of each sub-device of the Brayton cycle system, and obtains the temperature, pressure and flow parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system is separately stabilized; sets the boundary conditions of the Brayton cycle system model; uses the boundary conditions as the initial input of the Brayton cycle system model, and globally stabilizes the model parameters to complete the building of the Brayton cycle system model. The present invention is applicable to the construction of the Brayton cycle system.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power simulation system program development. Background Art

[0002] A small nuclear reactor system refers to a nuclear reactor unit with a power generation capacity of less than 300 MWe. It has the advantages of flexible layout, wide application, high energy density, long service life, high power, long endurance time, etc., meeting the demand for diversified energy sources and having a wide application prospect. It can be used in icebreakers, marine reactors, offshore floating reactors, deep-sea space stations, etc. There are many energy conversion methods for available nuclear power supply technologies. For small reactor systems, regardless of the reactor type adopted, such as gas-cooled reactors, metal-cooled reactors or heat pipe reactors, when the power reaches the megawatt or sub-megawatt level, in order to improve the energy conversion efficiency and economy of the system, a closed Brayton thermodynamic cycle is preferably adopted.

[0003] The Brayton cycle system mainly consists of key equipment such as a reactor core, a steam turbine, a compressor, a generator, a cooler and a recuperator. Its working process is as follows: High-pressure and low-temperature working fluid enters the reactor core and is heated, and then enters the turbine through a pipeline to expand and do work. The turbine, compressor and generator are coaxial. While the turbine drives the generator to generate electricity, it also drives the operation of the compressor. The high-temperature working fluid that has completed work at the turbine outlet enters the low-pressure and high-temperature side of the recuperator through a pipeline to heat the high-pressure and low-temperature side working fluid of the recuperator. The temperature of the working fluid flowing through the low-pressure side of the recuperator decreases, and then it enters the cooler for cooling. After meeting the requirements at the compressor inlet, it enters the compressor through a pipeline. After the compressor compresses the working fluid, the pressure of the working fluid increases, and the temperature also rises accordingly. When the pressure increase meets the requirements, it flows into the high-pressure side of the recuperator for preheating, and then flows out from the high-pressure side outlet of the recuperator and enters the reactor core through a pipeline, thus completing the entire Brayton cycle device process.

[0004] Key equipment such as the Brayton cycle core, steam turbine, compressor, recuperator and cooler are connected through pipelines to form a closed cycle system. The parameters between each key equipment are mutually transmitted, having strong correlation. The calculation of the inlet and outlet parameters of each key equipment will affect the calculation accuracy and calculation efficiency of the entire system analysis program. The steam turbine, compressor and generator in the Brayton cycle adopt coaxial rotation, which are collectively called rotating mechanical equipment. Specifically as Figure 1 shown, as the key equipment in the Brayton cycle, its calculation accuracy and calculation efficiency have a significant impact on the entire Brayton cycle system analysis program. The model of rotating mechanical equipment is complex, and the matching process has a large amount of calculation. How to match the characteristic curves of the steam turbine and the compressor is the key difficulty in the construction of the Brayton cycle system. Figure 1 It is the schematic diagram of the Brayton cycle system. Summary of the Invention

[0005] The object of the present invention is to solve the problems of large computational amount and high complexity existing in the construction process of the existing Brayton system, and a method for constructing a Brayton cycle system based on the compressor characteristic curve and the gas turbine theoretical model is proposed.

[0006] A method for constructing a Brayton cycle system based on the compressor characteristic curve and the gas turbine theoretical model includes:

[0007] Step 1: Construct a coolant physical property calculation model according to the physical and chemical properties of the helium-xenon mixed gas;

[0008] Construct a flow heat transfer calculation model according to the flow heat transfer characteristics of the helium-xenon mixed gas;

[0009] Step 2: Based on the three major conservation laws, construct the mathematical and physical models of the sub-devices of the Brayton cycle system, and use the coolant physical property calculation model and the flow heat transfer calculation model to calculate the temperature, pressure and flow rate parameters of the inlet and outlet gases when the sub-devices of the Brayton cycle system operate independently; the mathematical and physical models of the sub-devices of the Brayton cycle system include: rotating mechanical equipment model, core equipment model, recuperator equipment model, cooler equipment model;

[0010] Step 3: According to the operating characteristics of the Brayton cycle system and the temperature, pressure and flow rate parameters of the inlet and outlet gases when the sub-devices of the Brayton cycle system operate independently, respectively adjust and stabilize the temperature, pressure and flow rate parameters of the inlet and outlet gases of each sub-device model of the Brayton cycle system to obtain the temperature, pressure and flow rate parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system is adjusted and stabilized independently;

[0011] Step 4: Set the boundary conditions of the Brayton cycle system model according to the temperature, pressure and flow rate parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system is adjusted and stabilized independently;

[0012] Step 5: Initialize the parameters of the mathematical and physical model of the Brayton cycle system, use the boundary conditions as the initial input of the Brayton cycle system model, and adjust and stabilize the model parameters as a whole until the temperature, pressure and flow rate parameters of the inlet and outlet of the sub-devices of the mathematical and physical model of the Brayton cycle system are stable and meet the set values of the system operating parameters, and complete the construction of the Brayton cycle system model.

[0013] Further, in the present invention, in Step 1, the coolant physical property calculation model includes: helium-xenon mixed gas density model, helium-xenon mixed gas specific heat at constant pressure model, helium-xenon mixed gas viscosity model, helium-xenon mixed gas thermal conductivity model;

[0014] Helium-xenon mixed gas density model:

[0015]

[0016] Where ρ is the density of the helium-xenon mixed gas, R g is the gas constant of the helium-xenon mixture, Z is the actual gas compressibility factor, T is the temperature of the helium-xenon mixture, and P is the pressure of the helium-xenon mixture.

[0017] Helium-xenon mixed gas constant pressure specific heat model:

[0018]

[0019] Where x1 is the mass fraction of helium in the helium-xenon mixture

[0020] The viscosity model of helium-xenon mixed gas is:

[0021]

[0022] Among them, μ 混 is the viscosity of the helium-xenon mixed gas, μ 0 is the weighted average value of viscosity, μ * is the fitted viscosity, v * is the average critical specific volume, ψ μ (·) is the fitting function of the experimental data, M is the average molar mass of the helium-xenon mixed gas;

[0023] The thermal conductivity model of helium-xenon mixed gas is:

[0024]

[0025] Among them, λ 混 is the thermal conductivity of the helium-xenon gas mixture, λ o is the weighted average value of thermal conductivity, Ψ λ (·) is the test data fitting function, λ * is the fitted thermal conductivity.

[0026] The Planck number model of a helium-xenon gas mixture is:

[0027]

[0028] Among them, Pr 混 is the Prandtl number of the helium-xenon gas mixture.

[0029] Furthermore, in the present invention, in step 1, the flow heat transfer calculation model of the helium-xenon mixed gas is:

[0030] Nu b =0.023Re b 0.8 Pr 0.65 (T w / T b ) -n

[0031] n = [0.57 - 1.59 / (x / D)]

[0032] In the formula, Nu b is the Nusselt number of the helium-xenon mixture gas, Re b is the Reynolds number with variable physical properties; Pr is the Prandtl number; T w is the wall temperature, in K; T b is the average temperature of the helium-xenon mixture gas, in K; n is the correction factor for variable physical properties; x is the axial distance between the uniformly heated section and the starting point of the heated section, in m; D is the overall length of the heated section, in m. Using the flow and heat transfer calculation model, the calculation of the Nusselt number of the helium-xenon mixture gas with different proportions is realized within the range of Reynolds number from 1.8×10 4 to 6×10 4 .

[0033] Furthermore, in the present invention, in step two, the mathematical and physical model of the rotating machinery includes: the total torque model of the compressor and the energy conversion model of the steam turbine;

[0034] The total torque model of the compressor is:

[0035]

[0036] Among them, the torque τ s corresponding to the isentropic work is:

[0037]

[0038] The irreversible or dissipative torque τ d is:

[0039]

[0040] Among them, represents the mass flow rate of the mixed working fluid, in kg / s; ω is the rotational angular velocity, in r / rad; η ad is the adiabatic efficiency of the compressor, obtained by calculating the compressor characteristic curve; is the total enthalpy of the isentropic process at the compressor outlet; is the actual total enthalpy at the compressor inlet, P1 T is the inlet total pressure; R p is the compressor pressure ratio; ρ m is the average density.

[0041] The energy conversion model of the steam turbine:

[0042]

[0043]

[0044] Among them, represents the mass flow rate of the mixed working fluid, kg / s; U represents the specific internal energy, J / kg; j represents the pipe connection number; represents the source term due to the turbine model correction, J; P1 represents the inlet pressure, Pa; P2 represents the outlet pressure, Pa; ρ represents the fluid density, kg / m 3 ; ρ1 represents the inlet density, kg / m 3 ; ρ2 represents the outlet density, kg / m 3 ; v1 represents the specific volume at the inlet, m 3 / kg; v2 represents the specific volume at the outlet, m 3 / kg; h1 represents the actual enthalpy value at the inlet of the steam turbine, J / kg; h2 represents the actual enthalpy value at the outlet of the steam turbine, J / kg; h2′ represents the enthalpy value of the working fluid at the outlet of the steam turbine in an isentropic process, J / kg.

[0045] Furthermore, in the present invention, in step two, the mathematical and physical model of the core equipment includes: a reactor power calculation model and a reactor core heat transfer model;

[0046] Reactor power calculation model:

[0047]

[0048]

[0049]

[0050] ρ′ = ρ in -α1(T f -T f0 )

[0051] where, N 堆 is the reactor thermal power; ρ′ is the total reactivity; β is the total delayed neutron fraction (0.0065); β i is the delayed neutron fraction of the i-th group; Λ is the neutron generation time per generation (10 -3 s); λ i is the decay constant of the i-th generation of delayed neutrons; C i is the concentration of delayed neutron precursors; ρ in is the reactivity introduced by the control rod; α1 is the temperature negative feedback coefficient; T f is the fuel temperature; T f0 is the fuel temperature at rated power;

[0052] Reactor core heat transfer model:

[0053]

[0054]

[0055]

[0056] Among them, P r Reactor thermal power; T f Average fuel temperature; ρ f Fuel element density; C vf Fuel element heat capacity; V c Total reactor volume, α2 Heat transfer coefficient of fuel element; A Heat transfer area of fuel element; ρ 冷 Coolant density; C p冷 Coolant heat capacity; T 堆冷a Average coolant temperature in the core; T 堆冷o Core outlet temperature; T 堆冷i Core inlet temperature; ε Reactor porosity; G 堆 Core mass flow rate.

[0057] Furthermore, in the present invention, in step two, the mathematical and physical model of the regenerator device is:

[0058] G 低i = G 低o = G 压

[0059] G 高i = G 高o = G 气

[0060]

[0061] T 高a = (T 高o + T 高i ) / 2

[0062]

[0063] T 低a = (T 低o + T 低i ) / 2

[0064]

[0065]

[0066] Among them, G 高i Inlet flow rate on the high-temperature side of the regenerator; G 高o Outlet mass flow rate on the high-temperature side of the regenerator; T 高i Inlet temperature on the high-temperature side of the regenerator; T 高o Outlet temperature on the high-temperature side of the regenerator; G 低i Inlet mass flow rate on the low-temperature side of the regenerator; G 低o Outlet mass flow rate at the low temperature of the regenerator; T低i Low - temperature side inlet temperature of the regenerator; T 低o Low - temperature side outlet temperature of the regenerator; Q 高 Heat transfer quantity on the high - temperature side of the regenerator; Q 低 Heat transfer quantity on the low - temperature side of the regenerator; M 高 Total mass of the fluid on the high - temperature side of the regenerator; M 低 Total mass of the fluid on the low - temperature side of the regenerator; j heat transfer factor; Pr Prandtl number; G 压 Flow rate of the compressor; G 气 Flow rate of the turbine; C p Specific heat capacity of the helium - xenon mixed gas; G flow rate; a 高 Heat transfer coefficient on the high - temperature side of the regenerator; A 高 Heat transfer area on the high - temperature side of the regenerator; e 高 Finned wall efficiency on the high - temperature side of the regenerator; a 低 Heat transfer coefficient on the low - temperature side of the regenerator; A 低 Heat transfer area on the low - temperature side of the regenerator; e 低 Finned wall efficiency on the low - temperature side of the regenerator.

[0067] Furthermore, in the present invention, in step two, the mathematical - physical model of the cooler equipment is:

[0068]

[0069] T 冷as =(T 冷o +T 冷i ) / 2

[0070] Wherein, G 冷i Inlet flow rate of the cooler working medium; G 冷o Outlet flow rate of the cooler working medium; T 冷i Inlet temperature of the cooler working medium; T 冷o Outlet temperature of the cooler working medium; T 冷a Average temperature of the cooler working medium; M 冷 Total mass of the fluid on the high - temperature side of the cooler; Q 冷 Cooling power of the cooler.

[0071] The calculation method for the characteristics of the Brayton cycle system coupling the theoretical design equation of the turbine and the characteristic curve of the compressor mentioned in the present invention is applicable to the Brayton cycle of gas working media (such as helium, helium - xenon mixed gas, supercritical carbon dioxide, etc.). For the calculation error of the physical properties of the helium - xenon mixed working medium, it is less than 5%. For the closed - cycle Brayton cycle system with the working medium being helium - xenon mixed gas, the steady - state calculation error is less than 5%, and the transient calculation error is less than 10%. Description of the Drawings

[0072] Figure 1 It is a schematic diagram of the Brayton cycle system;

[0073] Figure 2 is the flowchart of the method of the present invention;

[0074] Figure 3 is a schematic diagram of the temperature on the high-temperature side of the reactor core changing with time;

[0075] Figure 4 Schematic diagram of the temperature on the low-temperature side changing with time;

[0076] Figure 5 Schematic diagram of the temperature inside the reactor core changing with time;

[0077] Figure 6 is a schematic diagram of the pressure changing with time;

[0078] Figure 7 is a schematic diagram of the mass flow rate changing with time. Detailed implementation manners

[0079] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0080] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0081] Detailed implementation manner 1: Next, in conjunction with Figure 1 and Figure 2 this implementation manner will be described. The method for building a Brayton cycle system based on the compressor characteristic curve and the gas turbine theoretical model described in this implementation manner includes:

[0082] Step 1: Construct a coolant physical property calculation model according to the physical and chemical properties of the helium-xenon mixed gas;

[0083] Construct a flow heat transfer calculation model according to the flow heat transfer characteristics of the helium-xenon mixed gas;

[0084] Step 2: Based on the three major conservation laws, construct the mathematical and physical models of the sub-devices of the Brayton cycle system, and use the coolant physical property calculation model and the flow heat transfer calculation model to calculate the temperature, pressure and flow parameters of the inlet and outlet gases when the sub-devices of the Brayton cycle system operate independently; the mathematical and physical models of the sub-devices of the Brayton cycle system include: rotating mechanical equipment model, reactor core equipment model, regenerator equipment model, cooler equipment model;

[0085] Step 3: According to the operating characteristics of the Brayton cycle system and the temperature, pressure, and flow rate parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system operates independently, separately adjust and stabilize the temperature, pressure, and flow rate parameters of the inlet and outlet gases of each sub-device model of the Brayton cycle system to obtain the temperature, pressure, and flow rate parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system is separately adjusted and stabilized.

[0086] Step 4: Set the boundary conditions of the Brayton cycle system model according to the temperature, pressure, and flow rate parameters of the inlet and outlet gases when each sub-device of the Brayton cycle system is separately adjusted and stabilized.

[0087] Step 5: Initialize the parameters of the mathematical and physical model of the Brayton cycle system. Use the boundary conditions as the initial input of the Brayton cycle system model, and globally adjust and stabilize the model parameters until the temperature, pressure, and flow rate parameters of the inlet and outlet of the sub-devices of the mathematical and physical model of the Brayton cycle system are stable and meet the set values of the system operating parameters (the set values are the preset values set by technicians according to the system), and complete the construction of the Brayton cycle system model.

[0088] Further, in the present invention, in Step 1, the coolant physical property calculation model includes:

[0089] Helium-xenon mixed gas density model, helium-xenon mixed gas constant pressure specific heat model, helium-xenon mixed gas viscosity model, helium-xenon mixed gas thermal conductivity model;

[0090] Physical and chemical properties of helium-xenon mixed gas: The molar mass of helium M = 4.003×10 -3 kg / mol; the boiling point under standard atmospheric pressure is f b = -268.94°C; the melting point t m = -267.96°C; the gas constant is approximately R = 2077.1 J / (kg·K); the critical pressure P cr = 0.229 MPa; the critical density ρ cr = 69.3 kg / m 3 .

[0091] The molar mass of xenon M = 131.293×10 -3 kg / mol; the boiling point under standard atmospheric pressure is f b = -108.10°C; the melting point t m = -111.79°C; the gas constant is approximately R = 2077.1 J / (kg·K); the critical pressure P cr = 5.764 MPa; the critical density ρ cr = 1100.0 kg / m 3 .

[0092] Considering the working environment of the working fluid, the physical property calculation temperature range of the helium-xenon mixed gas is 300K - 1400K, and the pressure range is 0.1MPa - 20MPa;

[0093] The density of the helium-xenon mixed gas is calculated by the following formula:

[0094]

[0095] where p is the pressure of the helium-xenon mixed gas, T is the temperature of the helium-xenon mixed gas, and R g is the gas constant of the helium-xenon mixed gas, and the expression is

[0096]

[0097] where M is the average molar mass of the helium-xenon mixed gas, and the expression is:

[0098] M = xM1 + (1 - x)M2

[0099] where M1 is the molar mass of helium; M2 is the molar mass of xenon; x is the molar mass fraction of helium.

[0100] where Z is the compressibility factor of the real gas, which is solved by the real gas state equation, and the expression is:

[0101]

[0102] where v is the specific volume of the gas; the real gas state equation is expanded as a power series:

[0103]

[0104] where B, C, D... represent the second-order, third-order, and fourth-order virial coefficients respectively; the second-order virial coefficient represents the interaction between two molecules, and the third-order virial coefficient characterizes the interaction between three molecules; the second-order and third-order virial coefficients are used to analyze the helium-xenon mixed gas. For real gases other than helium, the second-order virial coefficient is:

[0105]

[0106] where is the reduced temperature, T cr is the critical temperature of the gas; v * is the critical specific volume of the gas;

[0107] Since helium tends to be an ideal gas, the second-order virial coefficient of helium:

[0108]

[0109] The second-order virial coefficient of the mixed gas is:

[0110]

[0111]

[0112]

[0113]

[0114] Among them, B 11 is the second virial coefficient of helium, B 22 is the second virial coefficient of xenon, B 12 is the average second virial coefficient of the helium-xenon mixed gas, v12* is the average critical specific volume of the helium-xenon mixed gas, is the critical specific volume of helium, is the critical specific volume of xenon, T cr,1 is the critical temperature of helium, T cr,2 is the critical temperature of xenon, T cr,12 is the average critical temperature of the helium-xenon mixed gas, and the subscripts 1 and 2 represent helium and xenon respectively;

[0115]

[0116] T 11 = T cr,1 T 22 = T cr,2

[0117] The third virial coefficient of the gas is:

[0118]

[0119] The third virial coefficient of the mixed gas is:

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] Among them, C1 is the third virial coefficient of helium, and C2 is the third virial coefficient of xenon;

[0126] The specific heat capacity at constant pressure of the helium-xenon mixed gas is calculated by the following formula:

[0127] C p = 2.6276 × x5 -5.3238×x 4 +4.1073×x 3 -1.4134×x 2 +0.2345×x + 0.0071

[0128] The viscosity μ of the helium-xenon mixture gas 混 The expression is:

[0129]

[0130] Among them, μ 0 is the viscosity weighted average value, and the latter part is the correction of the real gas; μ * is the fitted viscosity, v * is the average critical specific volume, ψ μ (·) is the fitting function of the experimental data.

[0131] ψ μ (·) is expressed as ψ μ (ρ r ) Its expression is:

[0132] ψ μ (ρ r ) = 0.221ρ r +1.062ρ r 2 -0.509ρ r 3 +0.225ρ r 4

[0133] μ * is the fitted viscosity, and the expression is:

[0134]

[0135] v * is the average critical specific volume, and the expression is:

[0136] v * = xv 11 +(1 - x)v 22

[0137] T * is the average critical temperature, and the expression is:

[0138]

[0139] Among them, v 11 is the critical specific volume of helium, v 12 is the critical specific volume of the helium-xenon mixture gas, v 22is the critical specific volume of xenon,

[0140]

[0141] T 11 = T cr,1 T 22 = T cr,2

[0142] The expression for the viscosity weighted average value of the helium-xenon mixed gas is:

[0143]

[0144] where the weighting coefficient φ 12 , φ 21 The expression is:

[0145]

[0146]

[0147] where M1 is the molar mass of helium and M2 is the molar mass of xenon, is the viscosity of helium, is the viscosity of xenon, and the related viscosity μ of the helium-xenon mixed gas 12 The expression is:

[0148] μ 12 = 3.40998×10 -7 (T - 45.89) 0.66

[0149] A 12 = Ω (2,2) / Ω (1,1) Ω (1,1) is the dimensionless collision integral of helium, and Ω (2,2) is the dimensionless collision integral of xenon. A12 represents the ratio of the dimensionless collision integrals of the two gases. For helium and xenon, its value range is 1.094 - 1.119.

[0150] The thermal conductivity of the helium-xenon mixed gas is expressed by the formula:

[0151]

[0152] where λ o is the weighted average value of the thermal conductivity, and the latter part is the correction for real gases; Ψ λ (·) is the fitting function of experimental data. Ψ λ (·) is expressed as Ψ λ (ρ r ), The expression is:

[0153] Ψ λ (ρ r ) = 0.645ρ r + 0.33ρ r 2 + 0.0368ρ r 3 - 0.0128ρ r 4

[0154] λ * is the fitting thermal conductivity, and the expression is:

[0155]

[0156] The weighted average of the thermal conductivity λ o The expression is:

[0157]

[0158] Among them, the weighting coefficient L 11 、L 12 、L 22 The expression is:

[0159]

[0160]

[0161]

[0162] is the thermal conductivity of helium, is the thermal conductivity of xenon, and the related thermal conductivity λ of the helium-xenon mixed gas 12 The expression is:

[0163]

[0164] Among them, k * is the Boltzmann constant (1.38 * 10-23 J / K), and the constant f 12 is determined by experiments, and for the helium-xenon mixed gas, its value is 1.06. m 12 is the average molecular mass of the mixed gas.

[0165] The Prandtl number model of the helium-xenon mixed gas is:

[0166]

[0167] Among them, Pr 混 is the Prandtl number of the helium-xenon mixed gas.

[0168] In this embodiment, during the calculation process, different terms on the right side of the power series expansion of the actual gas state equation are intercepted, and different precisions can be obtained. In the low-pressure range, the third-order virial coefficient and higher-order virial coefficients are omitted, and a quite high precision can be obtained. By combining mathematical analysis and experimental data, an empirical formula for the virial coefficient of the actual gas can be derived. The empirical formula of the virial coefficient of the ideal gas and the actual gas has a large difference, and they need to be calculated separately. In the present invention, the second-order and third-order virial coefficients are used to analyze the helium-xenon mixed gas.

[0169] Furthermore, in the present invention, in step one, the flow and heat transfer calculation model of the helium-xenon mixed gas is as follows:

[0170] Nu b = 0.023Re b 0.8 Pr 0.65 (T w / T b ) -n

[0171] n = [0.57 - 1.59 / (x / D)]

[0172] In the formula, Re b is the variable-property Reynolds number; Pr is the Prandtl number; T w is the wall temperature, with the unit of K; T b is the average temperature of the helium-xenon mixed gas, with the unit of K; n is the variable-property correction factor; x is the axial distance between the uniformly heated section and the starting point of the heated section, with the unit of m; D is the overall length of the heated section, with the unit of m; the flow and heat transfer calculation model is used to calculate the Nusselt number of the helium-xenon mixed gas with different proportions in the range of Reynolds number from 1.8×10^4 to 6×10^4.

[0173] Furthermore, in the present invention, in step two, the mathematical and physical model of the rotating machinery includes: the total torque model of the compressor and the energy conversion model (energy equation) of the steam turbine;

[0174] The focus of constructing the mathematical and physical system analysis program of the rotating machinery, the core equipment, the recuperator equipment, and the cooler equipment based on the three major conservation laws lies in the response of the system equipment to parameter changes and the coupling mechanism between the main equipment. If too complex compressor and turbine models are selected, the calculation time and stable convergence will be reduced, and it is difficult to achieve real-time simulation. If only the model accuracy of a certain equipment is pursued while ignoring the matching degree of the accuracy of each model, the calculation accuracy of the entire system will not be significantly improved.

[0175] Turbines and compressors are both fluid machinery components. The turbine unit in this model features a single-shaft, integrated layout, meaning the turbine, compressor, and generator are coaxially mounted. A turbine is a rotary power machine that converts the internal energy of a working fluid into mechanical energy, thereby driving the entire mechanical shaft system. A compressor is a rotary power machine that converts mechanical energy into the internal energy of the working fluid. Its primary purpose is to compress the working fluid, raising its pressure to the designed value and providing the pressure head required to drive the system's circulation.

[0176] For a stable single-phase fluid, the energy equation can be written as:

[0177]

[0178] in, represents the mass flow rate of the mixed working fluid, kg / s; U represents the specific internal energy, J / kg; j represents the pipe number; represents the source term due to turbine model correction, J; P represents pressure, Pa.

[0179] Therefore, the inlet and outlet pipe interfaces with the same pressure can be rewritten in the form of specific enthalpy as follows:

[0180]

[0181] Where h1 represents the actual enthalpy at the inlet of the turbine, J / kg; h2 represents the actual enthalpy at the outlet of the turbine, J / kg; P1 represents the inlet pressure, Pa; P2 represents the outlet pressure, Pa; ρ1 represents the inlet density, kg / m 3 .

[0182] At the same time, the total turbine energy equation can be written as:

[0183]

[0184] Where v1 represents the inlet specific volume, m 3 / kg; v2 represents the outlet specific volume, m 3 / kg; It represents the total energy of the gas turbine, J; W is the total power of the gas turbine, J / kg.

[0185] Therefore, the source term can be obtained from the above equation:

[0186]

[0187] The power of the shaft in the turbine equipment can be approximately written as:

[0188]

[0189] Where ρ2 represents the inlet density, kg / m 3 .

[0190] Among them, the efficiency η is consistent with the calculation method of the compressor adiabatic efficiency, that is, the ratio of actual power to isentropic power, that is:

[0191]

[0192] Wherein, h1 represents the actual enthalpy at the inlet of the turbine, in J / kg; h2 represents the actual enthalpy at the outlet of the turbine, in J / kg; and h2′ represents the isentropic process enthalpy of the working fluid at the outlet of the turbine, in J / kg.

[0193] Finally, combining the above equations, we can get the source term that needs to be added to the turbine energy equation:

[0194]

[0195] In a compressor, forces acting tangentially only cause a change in the angular momentum of the compressor's working fluid. Radial and axial forces are subject to physical design limits. Therefore, the total torque applied to the compressor can be considered to consist of two components: one that changes the fluid's angular momentum and the other that generates reaction forces in the journal and thrust bearings. In principle, the isentropic torque can be calculated by considering the isentropic compression of the fluid and then applying an efficiency factor to obtain the total torque.

[0196] The torque corresponding to isentropic work is:

[0197]

[0198] Adiabatic efficiency is defined as:

[0199]

[0200] The irreversible or dissipative torque is:

[0201]

[0202] Compressor losses are the energy associated with the work produced by friction:

[0203]

[0204] in, represents the energy lost by the compressor,

[0205] The momentum equation for the compressor can be written as:

[0206]

[0207] Where P is the total pressure of the fluid, ρ is the density of the fluid, and H is the pressure head added to the fluid by the compressor. The total pressure P is determined by the pressure ratio relative to the speed and flow rate table, the pressure ratio R p Defined as:

[0208]

[0209] Among them, P1 T is the total pressure at the compressor inlet, and P2 T is the total pressure at the compressor outlet.

[0210] If it is assumed that the average density ρ m is independent of pressure ( ), then the compressor head ΔP added to the momentum equation is:

[0211]

[0212] Assuming that the heat entering the system is zero, the total work of the input liquid is given by the following formula:

[0213]

[0214]

[0215]

[0216] Among them, is the total work of the compressor, is the isentropic work of the compressor, is the work lost by the compressor.

[0217] Using the symbol convention, the work on the fluid is positive. The isentropic work is calculated based on the increase in potential energy in the control volume

[0218]

[0219] The torque corresponding to the isentropic work is obtained by combining the above formula:

[0220]

[0221] And the irreversible or dissipative torque is obtained by the above formula:

[0222]

[0223] The total torque is the sum of the isentropic torque and the dissipative torque:

[0224]

[0225] And it can be input into the shaft rotational speed equation.

[0226] The surge line and throttling line in the compressor characteristic curve determine the normal operating range of the compressor. The data in the normal operating area of the compressor are written into the input card in tabular form and read through linear interpolation. At the same time, transient parameters beyond the normal operating range are calculated through simple linear extrapolation. With the rated stagnation speed, speed, and mass flow rate as input parameters, the compressor characteristic curve is called to obtain the compressor pressure ratio and efficiency under the corresponding operating conditions.

[0227] Furthermore, in the present invention, in step two, the mathematical and physical model of the core equipment is as follows: including a reactor power calculation model and a reactor core heat transfer model;

[0228] The reactor is the energy source of the Brayton cycle. The coolant flows through the reactor core to take away the heat of the reactor. Then, the coolant enters the turbine to do work, thereby driving the turbine and compressor to do work, and converting thermal energy into mechanical energy, electrical energy, or other types of energy. The core of the reactor module is the point reactor neutron kinetics equation and the core heat transfer equation that describe the generation of fission energy in the reactor.

[0229] Since in the system dynamic process, what is mainly concerned about is the change of reactor power and the change of neutron flux, and the spatial distribution of power and neutron flux is not the main concern, the point reactor neutron kinetics equation is selected. As shown in the following formula, this equation is a coupled system of first-order differential equations. The point reactor model is widely applicable in many cases due to its simplicity, especially when the local perturbation is small or the spatial effect is not important, and it is widely used in many nuclear energy systems in engineering.

[0230] Reactor power calculation model:

[0231]

[0232]

[0233]

[0234] ρ′ = ρ in -α1(T f -T f0 )

[0235] where N 堆 reactor thermal power; ρ′ is the total reactivity; β is the total delayed neutron fraction (0.0065); β i the delayed neutron fraction of the i-th group; Λ is the neutron generation time per generation (10 -3 s); λ i the decay constant of the i-th generation of delayed neutrons; C i the concentration of delayed neutron precursors; ρ in the reactivity introduced by the control rod; α1 is the temperature negative feedback coefficient; T fFuel temperature; T f0 Fuel temperature at rated power.

[0236] The reactor core heat transfer model is a heat transfer model based on the lumped parameter method. Since the core heat transfer model is concerned with the relationship between the outlet temperature of the reactor and the core power, it can be considered that all the fuel elements in the entire core are at the same temperature at the same instant. This simplified analysis using the lumped parameter method is commonly used in the heat transfer analysis of reactor cores.

[0237] Reactor core heat transfer model:

[0238]

[0239]

[0240]

[0241] Where, P r Reactor thermal power; T f Average fuel temperature; ρ f Fuel element density; C vf Fuel element heat capacity; V C Total reactor volume, α2 fuel element heat transfer coefficient; A fuel element heat transfer area; ρ 冷 Coolant density; C p冷 Coolant heat capacity; T 堆冷a Average core coolant temperature; T 堆冷o Core outlet temperature; T 堆冷i Core inlet temperature; ε reactor porosity; G 堆 Core mass flow rate.

[0242] Furthermore, in the present invention, in step two, the mathematical and physical model of the recuperator device is:

[0243] G 低i = G 低o = G 压

[0244] G 高i = G 高o = G 气

[0245]

[0246] T 高a =(T 高o + T 高i ) / 2

[0247]

[0248]

[0248]

[0248] T 低a =(T低o +T 低i ) / 2

[0249]

[0250]

[0251] Wherein, G 高i Inlet flow rate of the high-temperature side of the regenerator; G 高o Outlet mass flow rate of the high-temperature side of the regenerator; T 高i Inlet temperature of the high-temperature side of the regenerator; T 高o Outlet temperature of the high-temperature side of the regenerator; G 低i Inlet mass flow rate of the low-temperature side of the regenerator; G 低o Outlet mass flow rate of the low-temperature side of the regenerator; T 低i Inlet temperature of the low-temperature side of the regenerator; T 低o Outlet temperature of the low-temperature side of the regenerator; Q 高 Heat transfer amount of the high-temperature side of the regenerator; Q 低 Heat transfer amount of the low-temperature side of the regenerator; M 高 Total mass of the fluid on the high-temperature side of the regenerator; M 低 Total mass of the fluid on the low-temperature side of the regenerator; a 回 Heat transfer coefficient of the regenerator; A 回 Heat transfer area of the regenerator; e 回 Finned wall efficiency of the regenerator; j heat transfer factor; Pr Prandtl number.

[0252] In the Brayton cycle system, the main function of the regenerator is to use the high-temperature working fluid at the turbine outlet to heat the working fluid entering the reactor inlet to ensure that its temperature meets the design value of the reactor, improve the thermal efficiency of the cycle, and ensure the stable operation of the Brayton cycle device under full power and variable operating conditions such as starting and stopping the reactor.

[0253] The heat transfer capacity of the regenerator module depends on its specific structural parameters, so a model is established based on its structure and principle. During modeling, based on a certain degree of assumption, the heat transfer between the regenerator and the outside is ignored, and it is considered that the temperature, velocity, and pressure parameters of the working fluid are the same within the same cross-section, and the fluid flows one-dimensionally along the axis, thus establishing a mathematical and physical model of the regenerator.

[0254] The reactor core heat transfer model is based on the heat transfer model of the lumped parameter method. Since the reactor core heat transfer model is concerned with the relationship between the outlet temperature of the reactor and the core power, it can be considered that all the fuel elements in the entire reactor core are at the same temperature at the same instant. This simplified analysis method of the lumped parameter method is commonly used for the heat transfer analysis of the reactor core.

[0255] Furthermore, in the present invention, in step two, the mathematical and physical model of the cooler device is as follows:

[0256]

[0257] T 冷as =(T 冷o +T 冷i ) / 2

[0258] where G 冷i is the inlet flow rate of the working fluid of the cooler; G 冷o is the outlet flow rate of the working fluid of the cooler; T 冷i is the inlet temperature of the working fluid of the cooler; T 冷o is the outlet temperature of the working fluid of the cooler; T 冷a is the average temperature of the working fluid of the cooler; M 冷 is the total mass of the fluid on the high-temperature side of the cooler; Q 冷 is the cooling power of the cooler.

[0259] In the Brayton cycle, the main function of the cooler is to cool the working fluid at the outlet of the low-pressure heating side of the regenerator so that its temperature can be effectively reduced and reach the design value at the compressor inlet, thereby improving the efficiency of the Brayton cycle.

[0260] The cooler model is similar to the regenerator module and is based on the principle of energy conservation. The cooling capacity of the cooler module depends on its specific structural parameters, the external ambient temperature, the flow rate of the external cooling fluid, etc. When modeling, based on certain assumptions, it is considered that the temperature, velocity, and pressure parameters of the working fluid are consistent within the same cross-section, and the fluid flows one-dimensionally along the axis, thereby establishing a lumped parameter model of the cooler.

[0261] The specific method for separately regulating and stabilizing the temperature, pressure, and flow rate parameters of the inlet and outlet gases of rotating machinery, core equipment, regenerator equipment, and cooler equipment according to the structure and operating characteristics of the Brayton cycle system is as follows:

[0262] Refer to the design values of the Brayton cycle system as shown in the following table, and separately regulate and stabilize each key equipment.

[0263] Table 1 Design values of key node parameters of the Brayton cycle system

[0264]

[0265] In rotating machinery, gas turbines and compressors are both fluid mechanical components. In a Brayton cycle system, the gas turbine unit has a single-shaft integral layout, that is, the gas turbine, compressor and generator are coaxially installed. Therefore, the compressor and the gas turbine have the same rotational speed. For gas turbine equipment, the main input parameters are: inlet temperature, mass flow rate, outlet pressure, rotor speed, gas turbine efficiency, and gas turbine power. Among them, the inlet temperature, mass flow rate and outlet pressure take design values and are constant during the individual tuning and stabilization process. By adjusting the gas turbine rotor speed, gas turbine efficiency and gas turbine power, the gas turbine outlet temperature and gas turbine inlet pressure are made to match the design values, thus completing the individual tuning and stabilization of the gas turbine equipment. For compressor equipment, the main input parameters are: inlet temperature, outlet pressure, mass flow rate, rotor speed, compressor efficiency and compressor power. Among them, the compressor rotor speed value is set to the output value of the gas turbine rotor speed, the inlet temperature, outlet pressure and mass flow rate take design values and are constant during the individual tuning and stabilization process. The compressor rotor speed and compressor efficiency are provided by the compressor characteristic curve. By adjusting the compressor characteristic curve, the compressor outlet temperature, inlet pressure and compressor power are made to match the design values, thus completing the individual tuning and stabilization of the compressor equipment. Specifically, as shown in Figures 3 - 7 shown. [[ID=�]]

[0266] For reactor equipment, the basic input parameters are: reactor inlet temperature, reactor outlet pressure, coolant mass flow rate, reactor power, equivalent diameter of the coolant flow channel, coolant temperature feedback coefficient, fuel rod temperature feedback coefficient, etc. The basic output parameters are coolant outlet temperature and fuel rod temperature distribution. Among them, the reactor inlet temperature, reactor outlet pressure, coolant mass flow rate and reactor power take design values and are constant during the individual tuning and stabilization process. By adjusting the equivalent diameter of the coolant flow channel, coolant temperature feedback coefficient and fuel rod temperature feedback coefficient, the reactor outlet temperature and pressure are made to match the design values, thus completing the individual tuning and stabilization of the reactor module.

[0267] The high-temperature side module of the regenerator is similar to the low-temperature side module, except that the heat transfer power values on the high-temperature side and the low-temperature side are different, and the values depend on the intermediate heat transfer loss and the heat transfer efficiency; and the energy transfer methods are different, that is, the high-temperature side of the regenerator releases heat to the low-temperature side. For the regenerator equipment, the basic input parameters are: the inlet temperature of the hot side of the regenerator, the outlet pressure of the hot side of the regenerator, the inlet temperature of the cold side of the regenerator, the outlet pressure of the cold side of the regenerator, the mass flow rate of the regenerator, the heat transfer efficiency of the regenerator, the equivalent thermal conductivity of the regenerator, the equivalent heat transfer area of the hot side of the regenerator, the equivalent heat transfer area of the cold side of the regenerator, etc. Among them, the inlet temperature of the hot side of the regenerator, the outlet pressure of the hot side of the regenerator, the inlet temperature of the cold side of the regenerator, the outlet pressure of the cold side of the regenerator, and the mass flow rate of the regenerator take the design values and are fixed values during the individual regulation and stabilization process. By adjusting the heat transfer efficiency of the regenerator, the equivalent thermal conductivity of the regenerator, the equivalent heat transfer area of the hot side of the regenerator, and the equivalent heat transfer area of the cold side of the regenerator, the outlet temperatures and inlet pressures of the cold and hot sides of the regenerator are made to conform to the design values, and the individual regulation and stabilization of the regenerator module are completed.

[0268] The models of the cooler and the regenerator are very close. The main difference is that the regenerator uses a high-temperature working fluid to heat a low-temperature working fluid, and the working fluids on both sides of its cooling are the same, both being a helium-xenon mixed gas, while the cooler uses cooling water to cool the working fluid at the outlet of the high-temperature side of the regenerator, and the working fluids on the hot and cold sides are different, with the cold side being water and the hot side being a helium-xenon mixed gas. For the cooler equipment, the basic input parameters are: the inlet temperature of the hot side of the cooler, the outlet pressure of the hot side of the cooler, the inlet temperature of the cold side of the cooler, the outlet pressure of the cold side of the cooler, the mass flow rate of the hot side of the cooler, the mass flow rate of the cold side of the cooler, the equivalent thermal conductivity of the cooler, the equivalent heat transfer area of the cooler, etc. Among them, the inlet temperature of the hot side of the cooler, the outlet pressure of the hot side of the cooler, the inlet temperature of the cold side of the cooler, the outlet pressure of the cold side of the cooler, the mass flow rate of the hot side of the cooler, and the mass flow rate of the cold side of the cooler take the design values and are fixed values during the individual regulation and stabilization process. By adjusting the equivalent thermal conductivity of the cooler and the equivalent heat transfer area of the cooler, the outlet temperatures and inlet pressures of the cold and hot sides of the cooler are made to conform to the design values, and the individual regulation and stabilization of the cooler equipment are completed.

[0269] Take the following obtained after the individual regulation and stabilization in Step 3: the rotational speeds of the compressor and the turbine rotor, the turbine efficiency, the turbine power, the compressor characteristic curve, the equivalent diameter of the reactor coolant flow channel, the coolant temperature feedback coefficient, the fuel rod temperature feedback coefficient, the equivalent thermal conductivity of the regenerator, the equivalent heat transfer area of the regenerator, the inlet and outlet temperatures of the cold side of the cooler, the mass flow rate of the cold side of the cooler, the equivalent thermal conductivity of the cooler, and the equivalent heat transfer area of the cooler as the boundary conditions of the Brayton cycle system and input them into the Brayton cycle system model.

[0270] Subsequently, the model parameters of the Brayton cycle system are initialized. Using the boundary conditions as the initial input of the Brayton cycle system model, the model parameters are adjusted as a whole until the parameters such as the inlet and outlet temperatures, pressures, and flows of the rotating machinery equipment, core equipment, recuperator equipment, and cooler equipment in the system model are stable and meet the set values of the system operating parameters.

[0271] Since there are small errors between the calculated values and the design values during the separate adjustment process, after inputting the boundary conditions into the Brayton cycle system, the Brayton cycle system will amplify the small errors, resulting in the calculated values output deviating significantly from the design values. Compare the calculated values and the design values of the inlet and outlet temperatures and pressures of each key equipment, and by finely adjusting the compressor characteristic curve, reduce the errors between the calculated values and the design values of the inlet and outlet temperatures and pressures of the key equipment of the Brayton cycle, making the error less than 5%, as shown in the following table, to meet the system development requirements.

[0272] Table 2 Verification of Operating Parameters of Brayton Cycle System

[0273]

[0274]

[0275] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model, characterized in that including: Step 1: Construct a coolant physical property calculation model according to the physical and chemical properties of the helium-xenon mixed gas; Construct a flow heat transfer calculation model according to the flow and heat transfer characteristics of the helium-xenon mixed gas; Step 2: Based on the three major conservation laws, construct a mathematical and physical model of the sub-equipment of the Brayton cycle system. Using the coolant physical property calculation model and the flow heat transfer calculation model, calculate the temperature, pressure and flow rate parameters of the inlet and outlet gases when the sub-equipment of the Brayton cycle system operates alone; The mathematical and physical model of the sub-equipment of the Brayton cycle system includes: a rotating machinery model, a core equipment model, a recuperator equipment model, and a cooler equipment model; Step 3: According to the operating characteristics of the Brayton cycle system and the temperature, pressure and flow rate parameters of the inlet and outlet gases when the sub-equipment of the Brayton cycle system operates alone, separately adjust and stabilize the temperature, pressure and flow rate parameters of the inlet and outlet gases of each sub-equipment model of the Brayton cycle system to obtain the temperature, pressure and flow rate parameters of the inlet and outlet gases when each sub-equipment of the Brayton cycle system is separately adjusted and stabilized; Step 4: Set the boundary conditions of the Brayton cycle system model according to the temperature, pressure and flow rate parameters of the inlet and outlet gases when each sub-equipment of the Brayton cycle system is separately adjusted and stabilized; Step 5: Initialize the parameters of the mathematical and physical model of the Brayton cycle system. Using the boundary conditions as the initial input of the Brayton cycle system model, globally adjust and stabilize the model parameters until the temperature, pressure and flow rate parameters of the inlet and outlet of the sub-equipment of the mathematical and physical model of the Brayton cycle system are stable and meet the set values of the system operating parameters, and complete the construction of the Brayton cycle system model.

2. The method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model according to claim 1, wherein In Step 1, the coolant physical property calculation model includes: a helium-xenon mixed gas density model, a helium-xenon mixed gas constant pressure specific heat model, a helium-xenon mixed gas viscosity model, and a helium-xenon mixed gas thermal conductivity model. According to the method for constructing a Brayton cycle system based on the compressor characteristic curve and the gas turbine theory model as described in claim 2, wherein Helium-xenon mixed gas density model: where ρ is the density of the helium-xenon mixture gas, R g is the gas constant of the helium-xenon mixture gas, Z is the real gas compression factor, T is the temperature of the helium-xenon mixture gas, and P is the pressure of the helium-xenon mixture gas; Helium-xenon mixed gas constant pressure specific heat model: where x1 is the mass fraction of helium in the helium-xenon mixed gas; C p is the specific heat capacity of the helium-xenon mixed gas; The viscosity model of the helium-xenon mixed gas is: Among them, μ 混 is the viscosity of the helium-xenon mixed gas, μ 0 is the viscosity weighted average value, μ * is the fitted viscosity, v * is the average critical specific volume, ψ μ (·) is the viscosity test data fitting function, and M is the average molar mass of the helium-xenon mixed gas; The thermal conductivity model of the helium-xenon mixed gas is: Among them, λ 混 is the thermal conductivity of the helium-xenon mixed gas, and λ o is the weighted average of the thermal conductivity, and Ψ λ (·) is the fitting function of the thermal conductivity test data, and λ * is the fitted thermal conductivity; The Prandtl number model of the helium-xenon mixed gas is: Among them, Pr 混 is the Prandtl number of the helium-xenon mixture gas.

4. The method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model according to claim 1 or 2, characterized in that In Step 1, the helium-xenon mixed gas flow heat transfer calculation model is: Nu b = 0.023Re b 0.8 Pr 0.65 (T w / T b ) -n n = [0.57 - 1.59 / (x / D)] In the formula, Nu b is the Nusselt number of the helium-xenon mixture gas, Re b is the variable-property Reynolds number; Pr is the Prandtl number; T w is the wall temperature, with the unit of K; T b is the average temperature of the helium-xenon mixture gas; n is the variable-property correction factor; x is the axial distance between the uniformly heated section and the starting point of the heated section; D is the overall length of the heated section.

5. The method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model according to claim 1, wherein In Step 2, the rotating machinery mathematical and physical model includes: a total torque model of the compressor and an energy conversion model of the steam turbine; The total torque model of the compressor is: Among them, the torque τ corresponding to the isentropic work s is as follows: The irreversible or dissipative torque τ d is given by: Among them, represents the mass flow rate of the mixed working fluid; ω is the rotational angular velocity; η ad is the adiabatic efficiency of the compressor, which is obtained by calculating the compressor characteristic curve; is the total enthalpy of the isentropic process at the compressor outlet; is the actual total enthalpy at the compressor inlet, P1 T is the total inlet pressure; is the total outlet pressure, R p is the compressor pressure ratio; ρ m is the average density; Steam turbine energy conversion model: Wherein, U represents specific internal energy; j represents the pipe number; represents the source term due to turbine model correction; P1 represents the inlet pressure; P2 represents the outlet pressure; ρ represents the fluid density; ρ1 represents the inlet density; ρ2 represents the outlet density; v1 represents the inlet specific volume; v2 represents the outlet specific volume; h1 represents the actual enthalpy of the turbine inlet; h2 represents the actual enthalpy of the turbine outlet; h2′ represents the isentropic process enthalpy of the working fluid at the turbine outlet.

6. The method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model according to claim 1 or 2, characterized in that In Step 2, the core equipment mathematical and physical model includes: a reactor power calculation model and a reactor core heat transfer model. According to the method for constructing a Brayton cycle system based on the compressor characteristic curve and the gas turbine theory model as described in claim 6, wherein Reactor power calculation model: ρ′ = ρ in -α1(T f -T f0 ) Among them, N 堆 is the reactor thermal power; ρ′ is the total reactivity; β is the total delayed neutron fraction; β i is the delayed neutron fraction of the i-th group; Λ is the neutron generation time; λ i is the decay constant of the i-th generation of delayed neutrons; C i is the concentration of delayed neutron precursors; ρ in is the reactivity introduced by the control rod; α1 is the temperature negative feedback coefficient; T f is the average fuel temperature; T f0 is the fuel temperature at rated power. According to the method for constructing a Brayton cycle system based on the compressor characteristic curve and the gas turbine theory model as described in claim 6, wherein Reactor core heat transfer model: Among them, P r Reactor thermal power; T f Average fuel temperature; ρ f Fuel element density; C vf Heat capacity of fuel element; V c Total volume of reactor, α2 heat transfer coefficient of fuel element; A heat transfer area of fuel element; ρ 冷 Coolant density; C p冷 Heat capacity of coolant; T 堆冷a Average temperature of coolant in reactor core; T 堆冷o Outlet temperature of reactor core; T 堆冷i Inlet temperature of reactor core; ε porosity of reactor core; G 堆 Mass flow rate of reactor core.

9. The method for building a Brayton cycle system based on a compressor characteristic curve and a gas turbine theoretical model according to claim 1, wherein In Step 2, the recuperator equipment mathematical and physical model is: G 低i = G 低o = G 压 G 高i = G 高o = G 气 T 高a = (T 高o + T 高i ) / 2 T 低a = (T 低o + T 低i ) / 2 Among them, The inlet flow rate on the high-temperature side of the regenerator; The outlet mass flow rate on the high-temperature side of the regenerator; The inlet temperature on the high-temperature side of the regenerator; The outlet temperature on the high-temperature side of the regenerator; The inlet mass flow rate on the low-temperature side of the regenerator; The outlet mass flow rate on the low-temperature side of the regenerator; The inlet temperature on the low-temperature side of the regenerator; The outlet temperature on the low-temperature side of the regenerator; Q 高 The heat transfer amount on the high-temperature side of the regenerator; Q 低 The heat transfer amount on the low-temperature side of the regenerator; M 高 The total mass of the fluid on the high-temperature side of the regenerator; M 低 The total mass of the fluid on the low-temperature side of the regenerator; j heat transfer factor; Pr Prandtl number; G 压 The flow rate of the compressor; G 气 The flow rate of the gas turbine; C p The specific heat capacity of the helium-xenon mixed gas; G flow rate; a 高 The heat transfer coefficient on the high-temperature side of the regenerator; A 高 The heat transfer area on the high-temperature side of the regenerator; e 高 The fin wall efficiency on the high-temperature side of the regenerator; a 低 The heat transfer coefficient on the low-temperature side of the regenerator; A 低 The heat transfer area on the low-temperature side of the regenerator; e 低 The fin wall efficiency on the low-temperature side of the regenerator.

10. The method for building a Brayton cycle system based on the compressor characteristic curve and the gas turbine theoretical model according to claim 1, wherein In Step 2, the cooler equipment mathematical and physical model is: T 冷as = (T 冷o + T 冷i ) / 2 Among them, G 冷i is the inlet flow rate of the cooler working medium; G 冷o is the outlet flow rate of the cooler working medium; T 冷i is the inlet temperature of the cooler working medium; T 冷o is the outlet temperature of the cooler working medium; T 冷a is the average temperature of the cooler working medium; M 冷 is the total mass of the high-temperature side fluid of the cooler; Q 冷 is the cooling power of the cooler.

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