A method for modeling isomorphic energy flow of a photo-thermal methanol cracking hydrogen production reactor

Abstract

The application provides a photo-thermal methanol cracking hydrogen production reactor isomorphism energy flow modeling method, and belongs to the technical field of solar thermo-chemical hydrogen production. The method comprises the following steps: a one-dimensional methanol cracking reaction kinetics and mass transfer model and a one-dimensional steady-state heat transfer and energy balance model are established by dividing a segmented control body; based on an isomorphism modeling theory, a local isomorphism energy flow network and a local mass transfer-reaction network are mapped to obtain a one-dimensional steady-state whole isomorphism energy flow and mass transfer-reaction network model which is coupled; and a layered solving algorithm combining outer main variable iteration and inner block matrix solving is used for solving to obtain reactor isomorphism energy flow data and complete isomorphism energy flow modeling. The application can reflect the along-path distribution characteristics of the internal thermo-chemical parameters of the reactor while reducing the calculation amount of the three-dimensional numerical model, and provides a modeling tool for the structural design, working condition analysis and performance evaluation of the solar thermo-chemical reactor.

Description

Technical Field

[0001] This invention belongs to the field of solar thermochemical hydrogen production technology, and particularly relates to a method for isomorphic energy flow modeling of a photothermal methanol cracking hydrogen production reactor. Background Technology

[0002] Thermochemical hydrogen production technology driven by solar thermal collectors can convert solar energy into fuel chemical energy, and is one of the important technical routes for the conversion, storage and utilization of renewable energy. Among them, the methanol thermocatalytic cracking hydrogen production reaction has the characteristics of relatively low reaction temperature, relatively mild reaction conditions and easy coupling of the hydrogen production process with medium and low temperature solar thermal collectors. After integrating the methanol cracking reactor with the trough solar collector, the solar radiation is concentrated and absorbed by the selective absorption coating, and the heat is transferred to the catalytic bed and reaction fluid through the metal absorption tube, thereby driving the methanol cracking reaction to generate hydrogen-rich gas.

[0003] The solar-thermal methanol cracking hydrogen production reactor simultaneously involves multiple coupled processes, including concentrated solar heat collection, heat conduction through metal tube walls, radiative heat transfer between tubes, convective and radiative heat dissipation from the glass tubes to the environment, convective heat transfer within the catalytic bed, changes in the sensible heat of the reaction mixture, the endothermic reaction of methanol cracking, and changes in composition along the flow path. These processes influence each other: local temperature affects the reaction rate and equilibrium state, while the endothermic reaction, in turn, alters the fluid temperature and wall thermal equilibrium; component distribution affects local partial pressure and reaction propulsion, and changes in fluid properties and thermal capacity flow rate affect the heat transfer process. Therefore, accurately describing the temperature, component, and conversion rate distribution along the flow direction of the reactor is fundamental for structural design, operational analysis, and performance evaluation.

[0004] Existing modeling methods for solar thermochemical reactors mainly include zero-dimensional lumped parameter models, one-dimensional distributed parameter models, and three-dimensional computational fluid dynamics models. Zero-dimensional lumped parameter models typically treat the reactor as a uniformly parameterized whole, making the calculation process relatively simple. However, they are difficult to reflect the flow path distribution characteristics of temperature, composition, reaction rate, and conversion rate within the reactor, and also difficult to analyze the impact of local heat transfer and reaction coupling on overall performance. Three-dimensional computational fluid dynamics models can describe the flow field, temperature field, and concentration field in more detail, but their modeling and mesh generation processes are complex, and the computational load required to solve the nonlinear partial differential equation system is large, resulting in high costs for use in system-level simulation, multi-condition analysis, parameter scanning, and engineering optimization.

[0005] Traditional one-dimensional distributed parameter models can balance computational efficiency and spatial resolution to a certain extent, but they usually directly establish energy conservation equations and mass conservation equations along the process, and couple heat transfer, heat dissipation, reaction endothermics, composition changes and reaction kinetics into the same set of nonlinear equations for solution. When dealing with reactor problems involving multi-stage discrete components, strong thermal reaction coupling, and local parameters that are updated with temperature and composition changes, this type of method is prone to problems such as unclear model structure, complex equation coupling relationships, and reliance on iterative experience in the solution process, which is not conducive to forming a unified and scalable modeling and solution framework. Summary of the Invention

[0006] To address the aforementioned shortcomings in existing technologies, this invention provides a isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor. This method solves the problems that existing zero-dimensional lumped parameter models cannot reflect the reactor's flow distribution characteristics, three-dimensional computational fluid dynamics models have high computational costs, and traditional one-dimensional models do not clearly express the coupling relationship between heat transfer, mass transfer, and chemical reaction.

[0007] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for isomorphic energy flow modeling of a photothermal methanol cracking hydrogen production reactor, comprising the following steps: S1. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters and operating boundary conditions, and divide the reactor along the preset axis according to the main flow direction of the fluid to obtain a preset number of segmented control bodies and main temperature nodes. S2. Based on structural parameters, operating boundary conditions, and segmented control volumes, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established by describing the methanol cracking reaction propulsion process, and a one-dimensional steady-state heat transfer and energy balance model is established by describing the basic thermal equilibrium process. S3. Based on the isomorphic modeling theory and key temperature nodes, the one-dimensional steady-state heat transfer and energy balance model is mapped to a local isomorphic energy flow network, and the one-dimensional methanol cracking reaction kinetics and mass transfer model is mapped to a local mass transfer-reaction network. The local isomorphic energy flow network and local mass transfer-reaction network of each segment control volume are coupled and assembled to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model. S4. Based on structural parameters and operational boundary conditions, a hierarchical solution algorithm combining outer-layer principal variable iteration and inner-layer block matrix solution is used to solve the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model, thereby obtaining reactor isomorphic energy flow data and completing the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

[0008] The beneficial effects of this invention are as follows: By dividing the control volume into segments, this invention establishes a one-dimensional methanol cracking reaction kinetics and mass transfer model and a one-dimensional steady-state heat transfer and energy balance model. Based on isomorphic modeling theory, it maps to obtain a local isomorphic energy flow network and a local mass transfer-reaction network, which are coupled to obtain a one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model. The model is solved using a hierarchical solution algorithm that combines outer-layer principal variable iteration with inner-layer block matrix solution to obtain reactor isomorphic energy flow data. This reduces the computational load of the three-dimensional numerical model while retaining the temperature, composition, and conversion rate distribution information along the reactor path. It also describes the coupling relationship between heat transfer, mass transfer, and chemical reaction through a clear networked expression, thus providing an efficient modeling tool for the structural design, operation analysis, and performance evaluation of solar thermochemical reactors.

[0009] Further, S1 includes the following steps: S101. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters including the total length of the reactor and the operating boundary conditions including the direct normal irradiance, methanol inlet temperature and total molar flow rate of methanol inlet. S102. Based on the solar thermal methanol cracking hydrogen production reactor, establish the coordinates along the reactor axis and define the main fluid flow direction as the positive direction of the reactor axis. S103. Divide the total length of the reactor along the axial direction to obtain a preset number of segmented control bodies; S104. Based on the segmented control body, obtain the main temperature nodes including the representative temperature of the reaction mixture gas, the representative temperature of the inner wall of the metal absorption tube, the representative temperature of the outer wall of the metal absorption tube, the representative temperature of the inner wall of the glass tube, and the representative temperature of the outer wall of the glass tube.

[0010] Furthermore, S2 includes the following steps: S201. Based on structural parameters, operating boundary conditions, and segmented control volumes, the component molar flow rate at the reactor inlet is defined according to the total molar flow rate at the methanol inlet by describing the methanol cracking reaction propulsion process. S202. Define the molar flow rate of components within the segmented control volume, calculate the local component concentration, and define the reaction advance rate within the segmented control volume based on the main methanol cracking reaction, and obtain the mass conservation relationship of the molar flow rate of components at the outlet of the segmented control volume. S203. By integrating the component molar flow rates at the outlet of the segmented control volume, the total molar flow rate at the outlet of the segmented control volume is obtained, and the component molar fraction is obtained. S204. Based on the mole fraction of the components and the mixed gas pressure in the segmented control body, the local partial pressure of the components in the segmented control body is obtained. S205. Based on the component molar flow rate at the reactor inlet, the component molar flow rate in the segmented control body, the local component concentration, the reaction propulsion rate in the segmented control body, the mass conservation relationship of the component molar flow rate at the segmented control body outlet, the component molar fraction, and the local partial pressure of the component in the segmented control body, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established. S206. Based on structural parameters, operating boundary conditions, and segmented control volume, the solar radiation heat input within the segmented control volume is defined by describing the basic thermal equilibrium process, according to the direct normal irradiance, the effective light-collecting area of ​​the segmented control volume, and the optical efficiency of the segmented control volume. S207. Based on the endothermic enthalpy of the methanol cracking reaction and the reaction propulsion rate in the segmented control body, the endothermic heat of the methanol cracking reaction is defined. S208. Based on the mass flow rate of the reaction mixture in the segmented control body and the equivalent isobaric specific heat capacity of the reaction mixture in the segmented control body, obtain the heat capacity flow rate of the reaction mixture in the segmented control body, and obtain the net sensible heat relationship and the change in sensible heat of the reaction mixture by defining the thermodynamic potential. S209. By defining the heat flow of the fluid endothermic branch, the heat flow of the radiation heat dissipation branch from the glass tube to the sky, and the heat flow of the convection heat dissipation branch from the glass tube to the environment, and combining the solar radiation heat input in the segmented control body, the heat endothermic reaction of methanol cracking, and the change in the sensible heat of the reaction mixture, a one-dimensional steady-state heat transfer and energy balance model is established.

[0011] Furthermore, the expression for the change in sensible heat of the reaction mixture is as follows: ; ; ; in, This represents the change in sensible heat of the reacting gas mixture. This represents the heat flow in the heat-absorbing branch of the fluid. This indicates that the methanol cracking reaction is endothermic. Indicates the first i The heat capacity flow rate of the reacting gas mixture within the body is controlled in segments. Indicates the first i Each segment controls the outlet temperature. Indicates the first i -1 segmented control body outlet temperature, Indicates the first i The mass flow rate of the reacting gas mixture within the body is controlled in segments. Indicates the first i The equivalent isobaric specific heat capacity of the reacting gas mixture in the body is controlled in segments; Definition of the first iThe thermodynamic potential corresponding to each segmented control volume is given, and the net sensible heat relationship is obtained as follows: ; in, It represents thermal kinetic potential.

[0012] The beneficial effects of the above-mentioned further scheme are as follows: This invention divides the solar thermal methanol cracking hydrogen production reactor into multiple segmented control volumes along the main fluid flow direction, and describes the heat transfer, mass transfer and chemical reaction processes within each segmented control volume in a one-dimensional steady-state framework. By describing the methanol cracking reaction propulsion process, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established. By describing the basic thermal equilibrium process, a one-dimensional steady-state heat transfer and energy balance model is jointly established. Under conditions where the computational load is lower than that of a three-dimensional computational fluid dynamics model, information on the temperature, composition and conversion rate distribution along the reactor can be obtained.

[0013] Furthermore, step S3 includes the following steps: S301. Based on the isomorphic modeling theory and key temperature nodes, a one-dimensional steady-state heat transfer and energy balance model is mapped. By setting the convection heat transfer resistance inside the tube, the thermal conductivity resistance of the metal absorption tube, the radiation heat transfer resistance between tubes, the thermal conductivity resistance of the glass tube, the environmental convection heat dissipation resistance, and the sky radiation heat dissipation resistance, a locally isomorphic energy flow network including controlled heat sources, thermal resistance, heat sinks, and thermodynamic potential is constructed. S302. The one-dimensional methanol cracking reaction kinetics and mass transfer model are mapped. The inlet component state and the outlet component state are taken as the two ends of the local mass transfer-reaction network. The extent of the methanol cracking reaction in the segmented control volume is characterized by using the reaction propulsion branch containing mass kinetic potential, reaction resistance and equilibrium concentration terms, and a local mass transfer-reaction network is constructed. S303. Connect the local isomorphic energy flow network and the local mass transfer-reaction network of each segmented control volume in series along the fluid flow direction to obtain the overall isomorphic energy flow network and the overall mass transfer-reaction network, respectively. Then, using the temperature field, component distribution and reaction propulsion, couple and assemble the overall isomorphic energy flow network and the overall mass transfer-reaction network to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model.

[0014] Furthermore, step S301 includes the following steps: S3011. Based on the isomorphic modeling theory and the main temperature nodes, the representative temperatures of the reaction mixture gas, the inner wall of the metal absorption tube, the outer wall of the metal absorption tube, the inner wall of the glass tube, and the outer wall of the glass tube are mapped to the reaction mixture gas node, the inner wall of the metal absorption tube node, the outer wall of the metal absorption tube node, the inner wall of the glass tube node, and the outer wall of the glass tube node in the main temperature nodes, respectively. An environment node and an equivalent sky node are set to obtain the equivalent network nodes. S3012, Map the effective solar radiation heat input as a controlled heat source connected to the node on the outer wall of the metal absorption tube, map the heat endothermic reaction of methanol cracking as a controlled heat sink at the node of the reaction mixture gas, and map the temperature rise effect of the reaction mixture gas flowing axially through the segmented control body as a thermodynamic potential. S3013. The branch between the inner wall node of the metal absorption tube and the reaction mixed gas node is set as the in-tube convective heat transfer resistance, the branch between the inner wall node of the metal absorption tube and the outer wall node of the metal absorption tube is set as the metal absorption tube thermal conductivity resistance, the branch between the outer wall node of the metal absorption tube and the inner wall node of the glass tube is set as the inter-tube radiative heat transfer resistance, the branch between the inner wall node of the glass tube and the outer wall node of the glass tube is set as the glass tube thermal conductivity resistance, the branch between the outer wall node of the glass tube and the environmental node is set as the environmental convective heat dissipation resistance, and the branch between the outer wall node of the glass tube and the equivalent sky node is set as the sky radiative heat dissipation resistance. S3013. Based on the operating boundary conditions and the structural parameters of each segment control body, the heat transfer resistance branch is obtained by determining the convection heat transfer resistance inside the pipe, the thermal conductivity resistance of the metal absorption tube, the radiation heat transfer resistance between the pipes, the thermal conductivity resistance of the glass tube, the environmental convection heat dissipation resistance, and the sky radiation heat dissipation resistance. S3014. Based on the net sensible heat relationship and heat transfer path, connect the controlled heat source, heat transfer thermal resistance branch, controlled heat sink and thermodynamic potential to form a locally isomorphic energy flow network topology. S3015. Based on the relationship between the thermal potential of each node and the heat flow of each heat transfer thermal resistance branch, establish a local energy conservation equation that satisfies Kirchhoff's laws, and combine it with the local isomorphic energy flow network topology to construct a local isomorphic energy flow network containing controlled heat sources, thermal resistance, heat sinks and thermal kinetic potential.

[0015] Furthermore, step S302 includes the following steps: S3021. Map the one-dimensional methanol cracking reaction kinetics and mass transfer model, and take the inlet component state and outlet component state as the port states of the local mass transfer-reaction network, respectively. S3022. The mass conservation relationship between the inlet component state and the outlet component state is used as the basic port constraint of the local mass transfer-reaction network. S3023. The mass kinetic potential of the reaction propulsion branch is characterized by the deviation of the local methanol concentration from the methanol equilibrium concentration. S3024. Based on the local component concentration, partial pressure, catalyst parameters, and equilibrium correction terms, the kinetic equivalence factor is determined, and the reaction resistance is obtained based on the methanol cracking kinetic rate constant and the kinetic equivalence factor at the local temperature. S3025. Based on the chemical reaction equilibrium constraints under local temperature and local component conditions, determine the methanol equilibrium concentration and use it as the equilibrium concentration term. S3026. By using mass kinetic potential as the driving force for reaction propulsion, reaction resistance as the limiting term for reaction propulsion, and equilibrium concentration as the equilibrium benchmark for reaction direction, a reaction propulsion branch is formed. S3027. Represent the reaction propulsion branch as the equivalent driving-resistance relationship in the mass transfer-reaction network, and calculate the reaction propulsion amount based on the local reaction rate and equivalent reaction scale parameters, and use it as the output of the mass transfer-reaction network to construct the local mass transfer-reaction network.

[0016] Furthermore, the expression for the mass-kinetic potential is as follows: ; ; in, It represents the kinetic potential. Indicates the first i The methanol concentration is controlled in a segmented manner at a local level. Indicates the equilibrium concentration of methanol. Indicates the first i Each segment controls the local concentration of carbon monoxide. Indicates the first i Each segment controls the local hydrogen concentration. Indicates local temperature The concentration equilibrium constant at this point; The expression for the reaction resistance is as follows: ; in, Indicates reaction resistance, Indicates local temperature The methanol cracking kinetic rate constant is given below. This represents the kinetic equivalence factor.

[0017] The beneficial effects of the above-mentioned further solutions are as follows: By mapping solar radiation input, wall heat transfer, environmental heat dissipation, reaction endothermic and sensible heat changes into a local energy flow network, and mapping the methanol cracking reaction propulsion process into a local mass transfer-reaction network, the present invention realizes that the coupling relationship between heat transfer, mass transfer and chemical reaction inside the reactor can be expressed in the form of network topology, which improves the clarity of the model structure and facilitates its extension to multi-segment, multi-condition and parametric analysis.

[0018] Furthermore, step S4 includes the following steps: S4 includes the following steps: S401. Based on structural parameters and operational boundary conditions, initialize the fluid temperature field and reaction propulsion field to obtain the current fluid temperature field and current reaction propulsion field. S402. Based on the current reaction propulsion field, the molar flow rate distributions of methanol, carbon monoxide, and hydrogen along the path are reconstructed to calculate the molar fractions of the components and the local partial pressures. S403. Based on the current fluid temperature field and the molar flow rate distribution along the flow path of methanol, carbon monoxide and hydrogen, update the fluid physical properties, heat capacity flow rate, local convective heat transfer coefficient, various heat transfer resistances, solar radiation heat input and heat absorption of methanol cracking reaction to obtain known energy flow data. S404. Based on known energy flow data, the thermal network equation is transformed into a linear block matrix equation and solved using a one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model to obtain the inner layer unknown vector. S405. Extract the inner layer unknown vector to obtain the reactor outlet temperature, thermodynamic potential of each segment control volume, heat flow of the fluid endothermic branch, heat flow of the sky radiation heat dissipation branch and heat flow of the environmental convection heat dissipation branch for the next outer layer iteration. S406. Using the thermodynamic potential of each segment of the control volume in the next outer layer iteration, update the current temperature field to obtain the temperature field of the next outer layer iteration. Combined with the local component distribution and local partial pressure, calculate the methanol cracking reaction rate using the methanol decomposition reaction kinetic model to obtain the original reaction propulsion. Then, relax and update the current reaction propulsion field to obtain the reaction propulsion field of the next outer layer iteration. S407. Calculate the maximum deviation of the temperature field and the maximum deviation of the reaction propulsion field between two adjacent outer layer iterations, and determine whether the maximum deviation of the temperature field is less than the preset temperature tolerance and whether the maximum deviation of the reaction propulsion field is less than the preset propulsion tolerance. If so, the outer layer iteration is determined to be converged, and the converged temperature field and the converged reaction propulsion field are obtained. If not, return to step S402 to continue reconstructing the component distribution, updating the parameters, solving the inner block matrix, and updating the reaction propulsion until the convergence condition is met; S408. By using the converged temperature field and the converged reaction propulsion field, the reactor isomorphic energy flow data, including the reactor friction fluid temperature, wall temperature, component molar flow rate, component molar fraction, local partial pressure, reaction propulsion, outlet temperature, outlet methanol conversion rate, and thermochemical efficiency, is obtained by reconstructing and solving the component distribution and thermal network equations. This completes the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

[0019] Furthermore, the expression for the linear block matrix equation is as follows: ; ; in, The coefficient matrix of the block matrix equation is represented. Let represent the right-hand vector of the block matrix equation. Represents the vector of unknowns in the inner layer. This represents the segmented outlet temperature vector. Represents the thermal force vector. This represents the heat flux vector of the heat-absorbing branch of the fluid. This represents the heat flow vector of the radiation cooling branch from the glass tube to the sky. This represents the heat flow vector of the convection cooling branch from the glass tube to the environment.

[0020] The beneficial effects of the above-mentioned further scheme are as follows: This invention adopts a hierarchical solution algorithm that combines outer-layer principal variable iteration with inner-layer block matrix solution. The temperature field, component distribution, and reaction propulsion rate are updated in the outer layer, and the thermal network equation with fixed parameters is transformed into a linear block matrix equation for solution in the inner layer, thereby reducing the complexity of directly solving strongly coupled nonlinear equations. Furthermore, by being able to output the reactor's temperature field along the flow path, component distribution, reaction propulsion rate, methanol conversion rate, outlet temperature, and thermochemical efficiency, it can be used for the structural design, operating condition analysis, performance evaluation, and system-level simulation of solar thermal methanol cracking hydrogen production reactors. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention.

[0022] Figure 2 This is a schematic diagram of a one-dimensional segmented model of the solar thermal methanol cracking hydrogen production reactor in this embodiment.

[0023] Figure 3 This is a schematic diagram of the thermal balance of a single segmented control body in this embodiment.

[0024] Figure 4 This is a schematic diagram of the local isomorphic energy flow network model of a single segmented control volume in this embodiment.

[0025] Figure 5 This is a schematic diagram of the local mass transfer-reaction network model of a single segmented control volume in this embodiment.

[0026] Figure 6 This is a schematic diagram of the overall isomorphic energy flow network model of the solar thermal methanol cracking hydrogen production reactor in this embodiment.

[0027] Figure 7 This is a schematic diagram of the overall mass transfer-reaction network model of the solar thermal methanol cracking hydrogen production reactor in this embodiment.

[0028] Figure 8 This is a comparison chart of the calculation results along the path between the one-dimensional steady-state isomorphic energy flow model and the three-dimensional finite element model for conditions 1 and 2 in this embodiment.

[0029] Figure 9 This is a comparison chart of the calculation results along the path between the one-dimensional steady-state isomorphic energy flow model and the three-dimensional finite element model for conditions 3 and 4 in this embodiment. Detailed Implementation

[0030] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0031] Before describing this embodiment, the following terms will be explained: Arrhenius: Arrhenius formula.

[0032] Example In this embodiment, isomorphic energy flow refers to the equivalent expression of the heat transfer, mass transfer, and chemical reaction propulsion processes in the solar thermal methanol cracking hydrogen production reactor according to a topological structure that is the same as or similar to that of a circuit network. Specifically, thermal potential or temperature difference characterizes the driving force of energy transfer, thermal resistance characterizes the resistance to heat transfer, controlled heat source characterizes solar radiation input, controlled heat sink characterizes the endothermic reaction of chemical reactions, and thermodynamic potential characterizes the sensible heat change of the reaction mixture along the process. Simultaneously, mass potential characterizes the driving force of reaction propulsion, reaction resistance characterizes the kinetic constraint, and equilibrium concentration term characterizes the local chemical equilibrium constraint. This isomorphic expression does not mean that the reactor is driven by electrical energy, but rather that the coupling relationship between energy, matter, and reaction within the reactor is described using a circuit network-like form.

[0033] like Figure 1 As shown, this invention provides a method for isomorphic energy flow modeling in a photothermal methanol cracking hydrogen production reactor, the implementation of which is as follows: S1. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters and operating boundary conditions, and divide the reactor along the preset axis according to the main fluid flow direction to obtain a preset number of segmented control volumes and main temperature nodes. The specific steps are as follows: S101. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters including the total length of the reactor and the operating boundary conditions including the direct normal irradiance, methanol inlet temperature and total molar flow rate of methanol inlet. S102. Based on the solar thermal methanol cracking hydrogen production reactor, establish the coordinates along the reactor axis and define the main fluid flow direction as the positive direction of the reactor axis. S103. Divide the total length of the reactor along the axial direction to obtain a preset number of segmented control bodies; S104. Based on the segmented control body, obtain the main temperature nodes including the representative temperature of the reaction mixture gas, the representative temperature of the inner wall of the metal absorption tube, the representative temperature of the outer wall of the metal absorption tube, the representative temperature of the inner wall of the glass tube, and the representative temperature of the outer wall of the glass tube.

[0034] In this embodiment, a typical solar thermal methanol cracking hydrogen production reactor includes a glass outer tube, a vacuum jacket, a metal absorption tube, and a catalyst bed disposed inside the metal absorption tube; the glass outer tube is located outside the metal absorption tube and forms an annular vacuum jacket with the metal absorption tube to reduce the convection and heat conduction losses from the metal absorption tube to the external environment. The outer surface of the metal absorption tube is provided with a selective absorption coating, which has a high absorption rate for the solar spectrum and a low emissivity for the infrared band; the interior of the metal absorption tube is filled with Cu / ZnO / Al2O3 catalyst particles to form a catalytic bed for methanol cracking reaction. Solar radiation is reflected by the trough-type concentrator and passes through the outer glass tube, then irradiates the selective absorption surface of the metal absorber tube. After absorbing solar radiation energy, the metal absorber tube transfers the heat to the catalytic bed and methanol vapor fluid through heat conduction through the tube wall and heat exchange inside the tube. During operation, methanol vapor enters the metal absorption tube through the reactor inlet and flows axially through the catalyst bed. During the flow, the methanol vapor absorbs heat and undergoes a cracking reaction to generate a reaction mixture containing hydrogen and carbon monoxide.

[0035] In this embodiment, the structural parameters and operating boundary conditions of a typical solar thermal methanol cracking hydrogen production reactor are obtained based on a typical solar thermal methanol cracking hydrogen production reactor. The structural parameters include the total length of the reactor, the size of the metal absorber tube, the size of the glass tube, the parameters of the catalytic bed, the heat transfer area, the thermal conductivity of the material, and the surface radiation parameters. The operating boundary conditions include at least one of the following: direct normal irradiance (DNI), methanol inlet temperature, methanol inlet mass flow rate, ambient temperature, and sky equivalent temperature. The heat collection or reaction components in the reactor are divided into preset sections along the main fluid flow direction. N Each segmented control unit, specifically: like Figure 2 As shown, establish coordinates along the axial direction of the reactor's heat collection or reaction components. z And define the main flow direction of the fluid as z In the positive direction of the axis, the total length of the reactor is L The total length of the reactor is divided along the axial direction into N One control entity, among which... N The total number of control entities is represented by an integer greater than 1, denoted as the [number of]th [control entity]. i The entry position of each segmented control body is The export location is The segment lengths are as follows: ; in, Indicates the segment length; when using equal-length discretization, the segment length is... as follows: ; in, This indicates the first segment control unit at the entry end. This indicates the last segment control unit at the export end; For the i Each segmented control unit defines the outlet temperature of the reaction mixture as... The inlet temperature is The reactor inlet temperature is ,in, This indicates the inlet temperature when methanol enters the reactor; No. i The main temperature nodes within the segmented control body include: the representative temperature of the reaction mixture gas. The inner wall of the metal absorption tube represents the temperature. The outer wall of the metal absorption tube represents the temperature. The inner wall of the glass tube represents the temperature. And the temperature represented by the outer wall of the glass tube Wherein, the representative temperature refers to the temperature at the first... i The equivalent node temperature is used to construct a one-dimensional piecewise model within each segmented control body; the radial heat transfer process is characterized by the equivalent node temperature and thermal resistance branch without solving the radial continuous temperature field.

[0036] S2. Based on structural parameters, operating boundary conditions, and segmented control volumes, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established by describing the methanol cracking reaction propagation process. Furthermore, a one-dimensional steady-state heat transfer and energy balance model is established by describing the basic thermal equilibrium process. The specific steps are as follows: S201. Based on structural parameters, operating boundary conditions, and segmented control volumes, the component molar flow rate at the reactor inlet is defined according to the total molar flow rate at the methanol inlet by describing the methanol cracking reaction propulsion process. S202. Define the molar flow rate of components within the segmented control volume, calculate the local component concentration, and define the reaction advance rate within the segmented control volume based on the main methanol cracking reaction, and obtain the mass conservation relationship of the molar flow rate of components at the outlet of the segmented control volume. S203. By integrating the component molar flow rates at the outlet of the segmented control volume, the total molar flow rate at the outlet of the segmented control volume is obtained, and the component molar fraction is obtained. S204. Based on the mole fraction of the components and the mixed gas pressure in the segmented control body, the local partial pressure of the components in the segmented control body is obtained. S205. Based on the molar flow rate of the component at the reactor inlet, the molar flow rate of the component in the segmented control body, the local component concentration, the reaction advance rate in the segmented control body, the mass conservation relationship of the molar flow rate of the component at the outlet of the segmented control body, the component molar fraction, and the local partial pressure of the component in the segmented control body, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established.

[0037] In this embodiment, a one-dimensional methanol cracking reaction kinetics and mass transport model is established based on structural parameters, operating boundary conditions, and segmented control volumes. Specifically: No. i The molar flow rates of the components within each segmented control volume are defined as follows: ; in, Indicates the first i The molar flow rate of methanol at the outlet of each segmented control volume Indicates the first i The molar flow rate of carbon monoxide at the outlet of each segmented control volume Indicates the first i The molar flow rate of hydrogen at the outlet of each segmented control volume; the molar flow rate of the components at the reactor inlet is defined as follows: ; For the methanol single-component inlet condition, take , , ,in, This indicates the total molar flow rate of methanol at the inlet. This indicates the molar flow rate of methanol at the reactor inlet. This indicates the molar flow rate of carbon monoxide at the reactor inlet. This indicates the molar flow rate of hydrogen at the reactor inlet; Total molar flow rate of methanol inlet The methanol inlet mass flow rate molar mass of methanol The converted expression is as follows: ; in, This indicates the methanol inlet mass flow. Indicates the molar mass of methanol; The main reaction of methanol cracking is: ; Definition of the first i The reaction propulsion amount within each segmented control body is According to stoichiometry, the first i The molar flow rates of the components at the outlet of each segmented control volume satisfy the following mass conservation relationship: ; ; ; in, Indicates the first i -1 molar flow rate of methanol at the outlet of the segmented control volume, Indicates the first i -1 molar flow rate of carbon monoxide at the outlet of the segmented control volume, Indicates the first i -1 molar flow rate of hydrogen at the outlet of a segmented control volume; To ensure that the reaction propulsion satisfies the constraints of mass conservation and nonnegativity, the following constraints are established: ; No. i The total molar flow rates at the outlet of each segmented control volume are as follows: ; in, Indicates the first i Total molar flow rate at the outlet of each segmented control body; The mole fraction of the components is defined as follows: ; in, Indicates the first i Each segmented control body component s mole fraction; Under the ideal gas assumption, the first iEach segment controls the components within the body s The localized pressure is as follows: ; in, Indicates the first i Each segment controls the components within the body s Localized pressure, Indicates the first i The pressure of the mixed gas within the segmented control body, the pressure It can be determined by a given pressure boundary, a preset pressure drop model, or an approximate constant pressure condition.

[0038] S206. Based on structural parameters, operating boundary conditions, and segmented control volume, the solar radiation heat input within the segmented control volume is defined by describing the basic thermal equilibrium process, according to the direct normal irradiance, the effective light-collecting area of ​​the segmented control volume, and the optical efficiency of the segmented control volume. S207. Based on the endothermic enthalpy of the methanol cracking reaction and the reaction propulsion rate in the segmented control body, the endothermic heat of the methanol cracking reaction is defined. S208. Based on the mass flow rate of the reaction mixture in the segmented control body and the equivalent isobaric specific heat capacity of the reaction mixture in the segmented control body, obtain the heat capacity flow rate of the reaction mixture in the segmented control body, and obtain the net sensible heat relationship and the change in sensible heat of the reaction mixture by defining the thermodynamic potential. S209. By defining the heat flow of the fluid endothermic branch, the heat flow of the radiation heat dissipation branch from the glass tube to the sky, and the heat flow of the convection heat dissipation branch from the glass tube to the environment, and combining the solar radiation heat input in the segmented control body, the heat endothermic reaction of methanol cracking, and the change in the sensible heat of the reaction mixture, a one-dimensional steady-state heat transfer and energy balance model is established.

[0039] In this embodiment, as Figure 3 As shown, the first i The basic thermal balance processes within the segmented control body include: effective solar radiation heat input, heat flow in the fluid endothermic branch, heat flow in the radiative heat dissipation branch from the glass tube to the sky, heat flow in the convective heat dissipation branch from the glass tube to the environment, heat endothermic reaction of methanol, and change in sensible heat of the reaction mixture. Definition of the first i The effective solar radiation heat input within each segmented control unit is The heat flux of the fluid endothermic branch is The heat flow in the radiative cooling branch from the glass tube to the sky is The heat flow in the convective heat dissipation branch from the glass tube to the environment is The heat absorbed by the methanol cracking reaction is The change in sensible heat of the reacting gas mixture is A one-dimensional steady-state heat transfer and energy balance model was established. No. i The solar radiation heat input within each segmented control body is represented as follows: ; in, Indicates direct normal irradiance, Indicates the first i The effective light-receiving area corresponding to each segmented control unit. Indicates the first i The optical efficiency or equivalent photothermal input coefficient corresponding to each segmented control body; Without considering axial heat conduction and axial back mixing, the first i The overall heat flow distribution relationship within each segmented control body can be written as: ; The reaction mixture gas in the first i The sensible heat changes within each segmented control volume satisfy the following: ; in, Indicates the first i Each segment controls the outlet temperature. Indicates the first i -1 segmented control body outlet temperature, Indicates the first i The heat capacity flow rate of the gas mixture reacting in the body is controlled in segments, and the expression is as follows: ; in, Indicates the first i The mass flow rate of the reacting gas mixture within the body is controlled in segments. Indicates the first i The equivalent isobaric specific heat capacity of the reacting gas mixture in the body is controlled in segments; The endothermic reaction of methanol cracking is expressed as follows: ; in, This represents the endothermic enthalpy of the methanol cracking reaction, and ; In a one-dimensional steady-state isomorphic energy flow model, the methanol cracking reaction is endothermic. As a controlled heat sink for extracting heat from the reactive gas mixture node; Therefore, the first i The net sensible heat obtained by the reacting gas mixture in each segmented control unit is expressed as follows: ; ; Definition of the first i The thermodynamic potential corresponding to each segmented control body is: The net sensible heat relationship is obtained as follows: ; The sensible heat change of the reaction mixture is used to describe the reaction mixture flowing axially through the first... i The temperature rise caused by the sensible heat change after each segmented control volume provides a basis for the subsequent construction of the local isomorphic energy flow network and the global block matrix equation.

[0040] In this embodiment, the following modeling assumptions are adopted: Quasi-homogeneous assumption: The catalyst bed is regarded as a uniform porous medium, and the reaction mixture and catalyst particles are in a local thermal equilibrium state. The local non-equilibrium temperature difference between the gas phase and the solid phase is not solved separately. Ideal gas assumption: The reaction mixture of methanol, hydrogen and carbon monoxide is regarded as an ideal gas mixture, and the partial pressure of each component is determined by the mole fraction and the pressure of the mixed gas. One-dimensional steady-state assumption: The reactor reaches steady state under given solar radiation input, inlet temperature and inlet flow rate, and the temperature, composition, partial pressure and reaction propulsion vary along the main flow direction of the fluid; Axial transport simplification assumption: Ignore axial heat conduction and axial backmixing of the fluid, and take the outlet temperature and outlet composition of the previous segment control volume as the inlet state of the next segment control volume; Radial equivalence assumption: Instead of solving for the radial continuous temperature distribution in the reactor, the radial heat transfer, heat dissipation and heat absorption processes are described by using equivalent nodes such as metal absorber tube, glass tube, reaction mixture gas, environment and sky and the heat transfer resistance between them. Based on the above segmentation method, variable definition and basic conservation relationship, each segmented control volume can be further mapped as a local isomorphic energy flow network and a local mass transfer-reaction network, and all segmented control volumes can be assembled into an overall one-dimensional steady-state isomorphic energy flow network model according to the fluid flow direction.

[0041] S3. Based on isomorphic modeling theory and key temperature nodes, the one-dimensional steady-state heat transfer and energy balance model is mapped to a locally isomorphic energy flow network, and the one-dimensional methanol cracking reaction kinetics and mass transfer model is mapped to a locally mass transfer-reaction network. The locally isomorphic energy flow networks and locally mass transfer-reaction networks of each segment control volume are coupled and assembled to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model. The specific steps are as follows: S301. Based on isomorphic modeling theory and key temperature nodes, a one-dimensional steady-state heat transfer and energy balance model is mapped. A locally isomorphic energy flow network is constructed by setting the convective heat transfer resistance inside the tube, the conductive heat transfer resistance of the metal absorption tube, the radiative heat transfer resistance between tubes, the conductive heat transfer resistance of the glass tube, the convective heat dissipation resistance of the environment, and the radiative heat dissipation resistance from the sky. The specific steps are as follows: S3011. Based on the isomorphic modeling theory and the main temperature nodes, the representative temperatures of the reaction mixture gas, the inner wall of the metal absorption tube, the outer wall of the metal absorption tube, the inner wall of the glass tube, and the outer wall of the glass tube are mapped to the reaction mixture gas node, the inner wall of the metal absorption tube node, the outer wall of the metal absorption tube node, the inner wall of the glass tube node, and the outer wall of the glass tube node in the main temperature nodes, respectively. An environment node and an equivalent sky node are set to obtain the equivalent network nodes. S3012: Map the effective solar radiation heat input as a controlled heat source connected to the node on the outer wall of the metal absorption tube, map the heat endothermic reaction of methanol cracking as a controlled heat sink at the node of the reaction mixture gas, and map the temperature rise effect of the reaction mixture gas flowing axially through the segmented control body as a thermodynamic potential.

[0042] In this embodiment, based on the segmented control body, for the first... i A local isomorphic network model is established for each segmented control volume to describe the energy coupling relationship between solar radiation input, pipe wall heat transfer, ambient heat dissipation, reaction endothermics, and changes in the sensible heat of the reaction mixture. The local isomorphism network includes a local isomorphic energy flow network and a local mass transfer-reaction network; such as Figure 3 As shown, the first i Each segment controls the physical and thermal balance within the body. Figure 4 for Figure 3 The locally isomorphic energy flow network obtained based on this, Figure 5 for Figure 4 A local mass transfer-reaction network coupled with the heat sink phase in the mid-reaction endothermic phase; Local isomorphic energy flow networks are used to describe the coupling relationships between solar radiation input, radial heat transfer, environmental heat dissipation, reaction endothermics, and fluid sensible heat changes. Local mass transfer-reaction networks are used to describe the coupling relationships between methanol cracking reaction propulsion, component variations along the path, kinetic constraints, and equilibrium constraints. The locally isomorphic energy flow network, such as Figure 4 As shown, for the first i Each segmented control body maps its internal heat transfer and energy balance process as a locally isomorphic energy flow network; the locally isomorphic energy flow network includes a controlled heat source, a heat transfer resistance, a controlled heat sink, and a thermodynamic potential; Figure 4In the diagram, the nodes representing the reaction mixture, the inner wall of the metal absorber tube, the outer wall of the metal absorber tube, the inner wall of the glass tube, and the outer wall of the glass tube are respectively defined as representing the temperature of the reaction mixture. The inner wall of the metal absorption tube represents the temperature. The outer wall of the metal absorption tube represents the temperature. The inner wall of the glass tube represents the temperature. And the temperature represented by the outer wall of the glass tube And set environment nodes. Equivalent node to the sky ; Among them, controlled heat source The node connected to the outer wall of the metal absorber tube represents the solar radiation input; the branch between the node on the inner wall of the metal absorber tube and the node for the reaction mixture represents the convective heat transfer resistance inside the tube. The branch between the inner wall node and the outer wall node of the metal absorption tube represents the thermal resistance of the metal absorption tube. The branch between the outer wall node of the metal absorption tube and the inner wall node of the glass tube represents the inter-tube radiative heat transfer thermal resistance. The branch between the inner wall node and the outer wall node of the glass tube represents the thermal resistance of the glass tube. The branch between the glass tube outer wall node and the environmental node represents the environmental convection heat dissipation thermal resistance. The branch between the glass tube outer wall node and the equivalent sky node represents the thermal resistance of sky radiation heat dissipation. A controlled heat sink is installed at the node of the reaction mixture, specifically to collect the heat absorbed by the methanol cracking reaction. The reaction mixture flows axially through the first... i The temperature rise generated by each segmented control unit is due to the thermodynamic potential. Characterization.

[0043] S3013. The branch between the inner wall node of the metal absorption tube and the reaction mixed gas node is set as the in-tube convective heat transfer resistance, the branch between the inner wall node of the metal absorption tube and the outer wall node of the metal absorption tube is set as the metal absorption tube thermal conductivity resistance, the branch between the outer wall node of the metal absorption tube and the inner wall node of the glass tube is set as the inter-tube radiative heat transfer resistance, the branch between the inner wall node of the glass tube and the outer wall node of the glass tube is set as the glass tube thermal conductivity resistance, the branch between the outer wall node of the glass tube and the environmental node is set as the environmental convective heat dissipation resistance, and the branch between the outer wall node of the glass tube and the equivalent sky node is set as the sky radiative heat dissipation resistance. S3013. Based on the operating boundary conditions and the structural parameters of each segment control body, the heat transfer resistance branch is obtained by determining the convection heat transfer resistance inside the pipe, the thermal conductivity resistance of the metal absorption tube, the radiation heat transfer resistance between the pipes, the thermal conductivity resistance of the glass tube, the environmental convection heat dissipation resistance, and the sky radiation heat dissipation resistance. S3014. Based on the net sensible heat relationship and heat transfer path, connect the controlled heat source, heat transfer thermal resistance branch, controlled heat sink and thermodynamic potential to form a locally isomorphic energy flow network topology. S3015. Based on the relationship between the thermal potential of each node and the heat flow of each heat transfer thermal resistance branch, establish a local energy conservation equation that satisfies Kirchhoff's laws, and combine it with the local isomorphic energy flow network topology to construct a local isomorphic energy flow network containing controlled heat sources, thermal resistance, heat sinks and thermal kinetic potential.

[0044] In this embodiment, the controlled heat source is used to characterize the first... i Effective solar radiation heat input received by each segmented control unit ; The first i The heat transfer process inside the tube within each segmented control body is equivalent to a heat transfer process with an approximately constant wall temperature, yielding the heat flow of the fluid endothermic branch. The expression is as follows: ; in, The thermal resistance for convective heat transfer is expressed as follows: ; in, This represents the equivalent convective heat transfer coefficient inside the pipe. Indicates the first i Each segment controls the heat exchange area inside the tube; For a catalytic bed filled with catalyst particles, the equivalent convective heat transfer coefficient inside the tube is... The Nusselt number correlation for porous media beds is determined by the following expression: ; in, Indicates the thermal conductivity of the reacting gas mixture. Indicates the characteristic diameter of the catalyst particles. The Nusselt number of the bed layer is expressed as follows: ; ; ; in, Represents the particle Reynolds number. Representing Prandtl numbers, This indicates the density of the reacting gas mixture. Indicates apparent flow velocity, Indicates dynamic viscosity; Thermoconductivity and thermal resistance of metal absorption tube The expression is as follows: ; in, Indicates the outer diameter of the metal absorption tube. Indicates the inner diameter of the metal absorption tube. This indicates the thermal conductivity of the metal absorption tube. Indicates the first i Length of each segmented control body; inter-tube radiative heat transfer thermal resistance The expression is as follows: ; in, Indicates the outer wall of the metal absorption tube in the first... i Each segment controls the radiative heat transfer area within the body. The equivalent radiative heat transfer coefficient between the outer wall of the metal absorption tube and the inner wall of the glass tube is expressed as follows: ; in, This represents the Stefan-Boltzmann constant. The equivalent radiation factor, determined by the emissivity and geometry of the absorber tube and glass tube surfaces, is given for a coaxial cylindrical structure. The expression is as follows: ; in, This indicates the emissivity of the outer surface of the metal absorber tube. Indicates the emissivity of the inner surface of the glass tube. Indicates the inner diameter of the glass tube; Thermal resistance of glass tube The expression is as follows: ; in, Indicates the outer diameter of the glass tube. Indicates the thermal conductivity of the glass tube; Convection heat dissipation thermal resistance The expression is as follows: ; in, This represents the convective heat transfer coefficient between the outer wall of the glass tube and the ambient air. Indicates the first i Each segment controls the outer surface area of ​​the glass tube inside the body; Thermal resistance of heat dissipation by sky radiation The expression is as follows: ; in, The equivalent radiative heat transfer coefficient between the outer wall of the glass tube and the equivalent environment of the sky is expressed as follows: ; in, Indicates the emissivity of the outer surface of the glass tube. This indicates that the temperature is represented by the outer wall of the glass tube. Indicates the equivalent temperature of the sky; No. i The sensible heat change of the gas mixture reacting in the body is controlled by thermodynamic potential in each segment. Characterization; The net sensible heat relationship is as follows: This indicates the first i The heat flow from the pipe wall to the reaction mixture within the segmented control body is partly used to compensate for the endothermic reaction of methanol cracking, and partly used to increase the sensible heat of the reaction mixture; thus, the controlled heat source, heat transfer resistance, controlled heat sink, and thermodynamic potential together constitute the first... i Local isomorphic energy flow network of segmented control volumes; like Figure 4 Each heat transfer branch in the locally isomorphic energy flow network corresponds to a physical heat transfer process, and each controlled source or controlled sink corresponds to an energy input or energy consumption process. The heat flow of each branch and the thermal potential of each node satisfy the energy conservation relationship similar to Kirchhoff's law, and provide local network units for the subsequent matrix assembly of the overall isomorphic energy flow network.

[0045] S302. Mapping the one-dimensional methanol cracking reaction kinetics to the mass transport model, by taking the inlet component state and the outlet component state as the two ends of the local mass transfer-reaction network, and by using the reaction propulsion branch containing mass kinetic potential, reaction resistance, and equilibrium concentration terms, the extent of the methanol cracking reaction within the segmented control volume is characterized, and the local mass transfer-reaction network is constructed. The specific steps are as follows: S3021. Map the one-dimensional methanol cracking reaction kinetics and mass transfer model, and take the inlet component state and outlet component state as the port states of the local mass transfer-reaction network, respectively. S3022. The mass conservation relationship between the inlet component state and the outlet component state is used as the basic port constraint of the local mass transfer-reaction network. S3023. The mass kinetic potential of the reaction propulsion branch is characterized by the deviation of the local methanol concentration from the methanol equilibrium concentration. S3024. Based on the local component concentration, partial pressure, catalyst parameters, and equilibrium correction terms, the kinetic equivalence factor is determined, and the reaction resistance is obtained based on the methanol cracking kinetic rate constant and the kinetic equivalence factor at the local temperature. S3025. Based on the chemical reaction equilibrium constraints under local temperature and local component conditions, determine the methanol equilibrium concentration and use it as the equilibrium concentration term. S3026. By using mass kinetic potential as the driving force for reaction propulsion, reaction resistance as the limiting term for reaction propulsion, and equilibrium concentration as the equilibrium benchmark for reaction direction, a reaction propulsion branch is formed. S3027. Represent the reaction propulsion branch as the equivalent driving-resistance relationship in the mass transfer-reaction network, and calculate the reaction propulsion amount based on the local reaction rate and equivalent reaction scale parameters, and use it as the output of the mass transfer-reaction network to construct the local mass transfer-reaction network.

[0046] In this embodiment, the local mass transfer-reaction network, such as Figure 5 As shown, for the first i Each segmented control unit maps the methanol cracking reaction process as a local mass transfer-reaction network. The local mass transfer-reaction network abandons the step-by-step expansion of the molar flow rate branches of each component, and uses the inlet component state and the outlet component state as the two ends of the network. The reaction propulsion branch is used to characterize the extent of the methanol cracking reaction within the segmented control unit. The reaction propulsion pathway includes mass kinetic potential, reaction resistance, and equilibrium concentration term, wherein the mass kinetic potential... The reaction resistance term is used to characterize the driving force of local reaction propulsion, the reaction resistance term is used to characterize the limiting effect of reaction kinetics on reaction propulsion, and the equilibrium concentration term is used to characterize the reaction equilibrium constraint under local temperature and local component conditions. Specifically, based on the main methanol cracking reaction, the first i The reaction propulsion of each segmented control unit The mass conservation relationship between the inlet component state and the outlet component state, the first i Total molar flow rate at the outlet of each segmented control body mole fraction of components Localized pressure of components ; like Figure 5 The local mass transfer-reaction network shown uses the deviation of the local methanol concentration from the equilibrium concentration to represent the mass kinetic potential. The expression is as follows: ; in, Indicates the first i The methanol concentration is controlled in a segmented manner at a local level. This represents the equilibrium concentration of methanol under local temperature and product concentration conditions. In the methanol cracking reaction, the equilibrium concentration term is set as follows: ; in, Indicates the first i Each segment controls the local concentration of carbon monoxide. Indicates the first iEach segment controls the local hydrogen concentration. Indicates local temperature The concentration equilibrium constant at this point; Utilizing reaction resistance The expression characterizing the local reaction kinetics constraint is as follows: ; in, Indicates local temperature The methanol cracking kinetic rate constant is given below. The kinetic equivalence factor is specifically determined by local component concentration, partial pressure, catalyst parameters, and equilibrium correction terms. Get the first i The reaction propulsion of each segmented control unit The expression is as follows: ; Based on the mass-kinetic potential, reaction resistance, and equilibrium concentration term, a reaction propulsion branch is constructed, representing the equivalent driving-resistance relationship in the mass transfer-reaction network; in specific numerical calculations, the reaction propulsion amount... It can be further determined by the local reaction rate and the equivalent reaction scale parameter, as shown in the following expression: ; in, Indicates the first i The methanol cracking reaction rate within the body is controlled in stages. This represents an equivalent reaction scale parameter related to catalyst mass, bed volume, or residence time, when the reaction rate is expressed per unit catalyst mass. Can be taken as the first i The mass of the catalyst in vivo is controlled in stages; when the reaction rate is measured per unit bed volume... Can be taken as the first i The volume of the in vivo catalytic bed is controlled in segments.

[0047] In this embodiment, the preferred local methanol cracking reaction rate is... The kinetic model of methanol decomposition reaction based on Cu / ZnO / Al2O3 catalyst was used to determine the following expression: ; in, and Both represent the surface adsorption coefficient. Indicates the first i Each segment controls the local partial pressure of methanol within the body. Indicates the first i Each segment controls the local partial pressure of hydrogen gas in the body. Indicates the first iEach segment controls the localized partial pressure of carbon monoxide in the body. This represents the reaction equilibrium constant at the local temperature. Represents the reaction rate constant; Reaction rate constant The Arrhenius form is as follows: ; in, Indicates pre-exponential factor, Indicates the apparent activation energy. Represents the universal gas constant and surface adsorption coefficient. and The expression is as follows: ; ; in, The entropy change parameter represents the adsorption process on the methoxy surface. The enthalpy change parameter represents the adsorption process on the methoxy surface. The entropy change parameter represents the adsorption process on hydrogen-based surfaces. Enthalpy change parameters representing the adsorption process on hydrogen-based surfaces; Equilibrium correction terms in the dynamic expression This term describes the deviation of a local reaction state from the chemical equilibrium state. When this term is positive, the methanol cracking reaction proceeds in the forward direction; when this term approaches zero, the local reaction is close to equilibrium.

[0048] S303. Connect the local isomorphic energy flow network and the local mass transfer-reaction network of each segmented control volume in series along the fluid flow direction to obtain the overall isomorphic energy flow network and the overall mass transfer-reaction network, respectively. Then, using the temperature field, component distribution and reaction propulsion, couple and assemble the overall isomorphic energy flow network and the overall mass transfer-reaction network to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model.

[0049] In this embodiment, as Figure 5 The inlet component state, mass kinetic potential, reaction resistance, equilibrium concentration term, and outlet component state shown together constitute the first... i The local mass transfer-reaction network of the segmented control volume; the molar flow rate branches of each component are not drawn individually in the figure, but are generally represented by the inlet component state and the outlet component state; the recursive relationship between the molar flow rates of each component is determined by the above-mentioned mass conservation equation; Local mass transfer-reaction networks and locally isomorphic energy flow networks are driven by reaction propulsion. Mutually coupled; specifically, the amount of reaction propulsion determines the first... i The methanol cracking reaction within the body is controlled in stages, absorbing heat in each stage. ; The reaction is endothermic As Figure 4 The controlled heat sink in the locally isomorphic energy flow network shown; simultaneously... Figure 4 The temperature obtained It also affects Figure 5 The reaction rate constant, equilibrium constant, adsorption coefficient, and local partial pressure are calculated; therefore, the heat transfer, mass transfer, and chemical reaction processes within a single segmented control volume are determined through... Figure 4 and Figure 5 The two local networks shown are coupled to represent the model, and the local isomorphic energy flow network and the local mass transfer-reaction network are integrated to obtain the local isomorphic network model.

[0050] In this embodiment, based on the local isomorphic network model, the network obtained by dividing along the axis... N The segmented control units are assembled in series to form a one-dimensional steady-state isomorphic energy flow network model of the solar thermal methanol cracking hydrogen production reactor. like Figure 6 As shown, the overall isomorphic energy flow network consists of N A network of locally isomorphic energy flows is formed in series along the direction of fluid flow. Figure 6 Each local energy flow network unit corresponds to Figure 4 The first one shown i Each segment of the control body is a locally isomorphic energy flow network. Adjacent local energy flow networks are connected by fluid temperature and thermodynamic potential. The outlet temperature of the previous segment of the control body serves as the inlet temperature of the next segment. The effective solar radiation heat input, internal heat transfer resistance, thermal conductivity resistance of the metal absorption tube, inter-tube radiation heat transfer resistance, thermal conductivity resistance of the glass tube, environmental heat dissipation resistance, endothermic heat sink, and thermodynamic potential within each segment of the control body together constitute the overall thermal network constraint equation. like Figure 7 As shown, the overall mass transfer-reaction network consists of N A series of local mass transfer-reaction networks are formed along the direction of fluid flow; Figure 7 Each local mass transfer-reaction network unit corresponds to Figure 5 The first one shown i The local mass transfer-reaction network of each segmented control volume; the outlet component state of the previous segmented control volume serves as the inlet component state of the next segmented control volume; the reaction propulsion rate within each segmented control volume collectively determines the molar flow rate, mole fraction, local partial pressure, and endothermic reaction of methanol, hydrogen, and carbon monoxide; thus, Figure 6 The overall isomorphic energy flow network shown is Figure 7 The overall mass transfer-reaction network shown is coupled through temperature field, component distribution and reaction propulsion.

[0051] S4. Based on structural parameters and operational boundary conditions, a hierarchical solution algorithm combining outer-layer principal variable iteration and inner-layer block matrix solution is used to solve the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model, thereby obtaining reactor isomorphic energy flow data and completing the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

[0052] In this embodiment, a hierarchical solution algorithm combining outer-layer principal variable iteration and inner-layer block matrix solution is used to solve the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model. Specifically: Based on the overall isomorphic energy flow network and overall mass transfer-reaction network in the one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model, the one-dimensional steady-state overall control equations of the reactor include: thermal network constraint equations, mass conservation recursive equations, and reaction kinetic constraint equations. According to the i Thermodynamic potential corresponding to each segmented control body , ,in, N Indicates the total number of control bodies; and according to the first i The outlet temperature of each segmented control unit is Inlet temperature is and reactor inlet temperature is , obtained the i Each segment control unit outlet temperature The expression is as follows: ; in, Indicates the first j Thermodynamic potential corresponding to each segmented control volume; The expression for the reactor outlet temperature is as follows: ; in, Indicates the reactor outlet temperature; For the i For each segmented control volume, the sensible heat change of the reaction mixture, the heat flux of the fluid endothermic branch, and the heat endothermic reaction satisfy the net sensible heat relationship: ; For the i The solar radiation heat input within the segmented control system satisfies the heat flow distribution relationship among the fluid heat absorption branch, the sky radiation heat dissipation branch, and the environmental convection heat dissipation branch: ; Along the main heat transfer path and the ambient heat dissipation branch, it can be based on Figure 6A thermal potential balance relationship is established for each thermal resistance branch, and the fluid temperature field is initialized. The main heat transfer path includes the convective heat transfer resistance inside the tube, the conductive heat transfer resistance of the metal absorption tube wall, the radiative heat transfer resistance between the metal absorption tube and the glass tube, and the conductive heat transfer resistance of the glass tube. The heat dissipation path includes the radiative heat dissipation resistance from the glass tube to the sky and the convective heat dissipation resistance from the glass tube to the environment. Through each thermal resistance branch, the relationship between the thermal potential of each node and the heat flow of each branch can be expressed as a linear topological constraint.

[0053] In this embodiment, the reaction propulsion field is defined for the overall mass transfer-reaction network as follows: ; and define Lower triangular accumulation matrix L The matrix elements are as follows: ; in, Represents a lower triangular accumulation matrix L The Middle a Line number b Column matrix elements; The molar flow rate vectors of methanol, carbon monoxide, and hydrogen at the outlet of each segment control volume are rewritten as follows: ; ; ; in, express N A column vector of all 1s. This indicates the molar flow rate of methanol at the reactor inlet. This indicates the molar flow rate of carbon monoxide at the reactor inlet. This indicates the molar flow rate of hydrogen at the reactor inlet. Represents the reaction propulsion field; Based on the molar flow rates of each component, the total molar flow rate, component molar fraction, and local partial pressure within each control segment can be obtained, and used to calculate the reaction rate and reaction propulsion rate, based on the reaction kinetic constraints of the reaction propulsion rate: Calculate the reaction propulsion amount; The overall control equations of the reactor consist of Figure 6 Corresponding thermal network constraints, Figure 7 The corresponding material conservation recursive constraints and reaction kinetic constraints are combined; since the radiation heat transfer coefficient, fluid properties, heat capacity flow rate, heat transfer coefficient and reaction kinetic rate all change with temperature and composition, if all the constraint equations are solved simultaneously, a strongly coupled nonlinear equation system will be formed. The above problem is addressed by combining outer-layer principal variable iteration with inner-layer block matrix solving: In the outer layer, given the temperature field and reaction propulsion field, the component distribution, physical property parameters, thermal resistance parameters, and reaction endothermic heat are updated; in the inner layer, the thermal network constraints with fixed parameters are transformed into linear block matrix equations for solving, and then the reaction propulsion is updated according to the reaction kinetic constraints. Specifically: Define segmented outlet temperature vector The expression is as follows: ; Define the thermal force vector The expression is as follows: ; Define the vectors in the overall capability network as follows: ; ; ; ; ; in, This represents the solar radiation heat input vector. Represents the endothermic vector of the reaction. This represents the heat flux vector of the heat-absorbing branch of the fluid. This represents the heat flow vector of the radiation cooling branch from the glass tube to the sky. This represents the heat flow vector of the convection cooling branch from the glass tube to the environment.

[0054] In this embodiment, given the outer main variable, i.e., the current temperature field is known. and the current reaction propulsion field The component distribution, local partial pressure, fluid properties, heat capacity flow rate, heat transfer resistance, solar radiation input, and reaction endothermic heat within each segment control body can all be updated to known parameters. At this point, the thermal network constraints in the overall isomorphic energy flow network can be transformed into linear block matrix equations, as shown below: ; in, The coefficient matrix of the block matrix equation is represented. Let represent the right-hand vector of the block matrix equation. The vector representing the inner unknowns is defined as follows: ; Inner layer unknown vector The dimension is ; Compared to the overall governing equations that directly retain all branch heat flow variables, this block matrix equations merge or eliminate intermediate variables such as heat flow from the metal absorber heat transfer branch, heat flow from the inter-tube radiation heat transfer branch, heat flow from the glass tube heat transfer branch, and sensible heat flow from the fluid. Only the reactor outlet temperature, the thermodynamic potential of each segment, the heat flow from the fluid endothermic branch, the heat flow from the sky radiation heat dissipation branch, and the heat flow from the environmental convection heat dissipation branch are retained as inner-layer unknowns. Thus, the overall thermal network is expressed as a compact linear block matrix form under the current fixed outer-layer parameters. coefficient matrix of block matrix equation The right-hand vector of the sum block matrix equation The expression is as follows: ; ; in, express identity matrix Represents the zero vector of the corresponding dimension. This represents the accumulation matrix used to deduce the outlet temperatures of each segment from the reactor outlet temperature. This represents the thermal resistance matrix of the main heat transfer path. Indicates path correction terms; The accumulation matrix The definition is as follows: ; It can be seen that the first i Each segment control unit outlet temperature With reactor outlet temperature The relationship with thermal kinetic potential is as follows: ; ; And each diagonal matrix is ​​defined as follows: ; ; ; ; ; ; ; in, This represents the thermal resistance matrix for convective heat transfer inside the pipe. This represents the thermal resistance matrix of the metal absorber wall. This represents the thermal resistance matrix for radiative heat transfer between the metal absorber tube and the glass tube. This represents the thermal resistance matrix of the glass tube. This represents the thermal resistance matrix for heat dissipation from sky radiation. This represents the thermal resistance matrix for environmental convection heat dissipation. Represents the heat capacity flux matrix; The thermal resistance matrix and path correction terms of the main heat transfer path are defined and obtained as follows: ; ; in, This represents the thermal resistance matrix of the main heat transfer path. Indicates path correction terms; The above block matrix equation In the diagram, the first row represents the cumulative relationship between the reactor inlet temperature, the thermodynamic potential of each segment, and the reactor outlet temperature; the second row represents the thermal potential balance between the glass tube to the sky radiation heat dissipation branch and the main heat transfer path; the third row represents the thermal potential balance between the glass tube to the environment convection heat dissipation branch and the main heat transfer path; the fourth row represents the energy conservation relationship between the sensible heat change of the reaction mixture, environmental heat dissipation, and reaction endothermic heat; and the fifth row represents the heat flow distribution relationship of solar radiation heat input among the fluid endothermic branch, the sky radiation heat dissipation branch, and the environment convection heat dissipation branch. Therefore, the overall isomorphic energy flow network can be uniformly solved using block matrix equations.

[0055] S401. Based on structural parameters and operational boundary conditions, initialize the fluid temperature field and reaction propulsion field to obtain the current fluid temperature field and current reaction propulsion field. S402. Based on the current reaction propulsion field, the molar flow rate distributions of methanol, carbon monoxide, and hydrogen along the path are reconstructed to calculate the molar fractions of the components and the local partial pressures. S403. Based on the current fluid temperature field and the molar flow rate distribution along the flow path of methanol, carbon monoxide and hydrogen, update the fluid physical parameters, heat capacity flow rate, local convective heat transfer coefficient, various heat transfer resistances, solar radiation heat input and heat endothermic reaction of methanol to obtain known energy flow data.

[0056] In this embodiment, the iteration of the outer main variable is combined with the solution of the inner block matrix, and a hierarchical solution algorithm is used to obtain the steady-state temperature field, component distribution, reaction advance rate, methanol conversion rate, outlet temperature, and thermochemical efficiency of the photothermal methanol cracking hydrogen production reactor on a one-dimensional spatial scale. Specifically: To initialize the main variables, given the operating conditions and reactor structural parameters, first calculate the total molar flow rate of methanol inlet based on the inlet mass flow rate. The fluid temperature field and reaction propulsion field are initialized as follows: ; The reaction propulsion field is initialized as a non-negative vector that satisfies the mass conservation constraint, as shown in the following expression: ; and satisfy ,in, This represents the initial fluid temperature field. Indicates the initial reaction propulsion field; Perform component distribution reconstruction and parameter updates based on the first k The outermost iteration propels the flow field based on the current reaction. ,according to Figure 7 The overall mass transfer-reaction network shown is used to reconstruct the molar flow rate distribution of methanol, carbon monoxide, and hydrogen along the flow path, and further calculate the molar fraction of components and local partial pressure within each control segment. Based on the current fluid temperature field Based on the component distribution, update the fluid physical parameters, heat capacity flow rate, local convective heat transfer coefficient, various heat transfer resistances, solar radiation heat input, and methanol cracking reaction endothermic heat, and obtain known energy flow data.

[0057] S404. Based on known energy flow data, the thermal network equation is transformed into a linear block matrix equation and solved using a one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model to obtain the inner layer unknown vector. S405. Extract the inner layer unknown vector to obtain the reactor outlet temperature, thermodynamic potential of each segment control volume, heat flow of the fluid endothermic branch, heat flow of the sky radiation heat dissipation branch and heat flow of the environmental convection heat dissipation branch for the next outer layer iteration. S406. Using the thermodynamic potential of each segment of the control volume in the next outer layer iteration, update the current temperature field to obtain the temperature field of the next outer layer iteration. Combined with the local component distribution and local partial pressure, calculate the methanol cracking reaction rate using the methanol decomposition reaction kinetic model to obtain the original reaction propulsion. Then, relax and update the current reaction propulsion field to obtain the reaction propulsion field of the next outer layer iteration. S407. Calculate the maximum deviation of the temperature field and the maximum deviation of the reaction propulsion field between two adjacent outer layer iterations, and determine whether the maximum deviation of the temperature field is less than the preset temperature tolerance and whether the maximum deviation of the reaction propulsion field is less than the preset propulsion tolerance. If so, the outer layer iteration is determined to be converged, and the converged temperature field and the converged reaction propulsion field are obtained. If not, return to step S402 to continue reconstructing the component distribution, updating parameters, solving the inner block matrix, and updating the reaction propulsion until the convergence condition is met.

[0058] In this embodiment, the inner block matrix is ​​solved. In the current iteration step, in response to the updated parameters of component distribution, local partial pressure, fluid properties, heat capacity flow rate, thermal resistance, solar radiation input, and reaction endothermic heat, which are considered as known energy flow data, the following method is used: Figure 6 The overall isomorphic energy flow network assembly coefficient matrix shown is and the right-hand vector The linear block matrix equation is solved as follows: ; Based on the calculated inner layer unknown vector Extract the first k Reactor outlet temperature after +1 outer layer iteration Thermodynamic potential of each segment control body Heat flow in the fluid endothermic branch , Heat flow of the sky radiation heat dissipation branch and the heat flow of the environmental convection cooling branch ; And utilize the first k Thermodynamic potential of each segment of the control volume in the +1 outer iteration The fluid temperature field is updated using the following expression: ; in, Indicates the first k Fluid temperature field of +1 outer layer iteration; Update the reaction propulsion amount according to the first k The fluid temperature field of the +1 outer layer iteration, combined with local component distribution and local partial pressure, is used to calculate the th... k The methanol cracking reaction rate for the +1st outer layer iteration is expressed as follows: ; in, Indicates the first k +1 outer layer iteration methanol cracking reaction rate; This indicates the current outer iteration's... i Each segment controls the local partial pressure of methanol within the body. This indicates the current outer iteration's... i Each segment controls the local partial pressure of hydrogen gas in the body. This indicates the current outer iteration's... i Each segment controls the local partial pressure of carbon monoxide in the body; And calculate the first k The initial reaction propulsion for +1 outer iterations is expressed as follows: ; in, Indicates the first k +1 outer layer iterations of the original reaction propulsion; The remaining methanol quantity is used as a constraint, and a relaxation update method is employed to update the original... k The reaction propulsion amount of the +1 outer iteration is updated to obtain the first... k The reaction propulsion field of the +1st outer iteration is expressed as follows: ; ; ; in, Indicates the first k +1 outer iteration reaction propulsion field Represents the relaxation factor, when At that time, the reaction propulsion field update degenerates into a direct update; Convergence is determined by calculating the maximum deviation of the temperature field and the maximum deviation of the reaction propulsion field between two adjacent outer layer iterations, as shown in the following expressions: ; ; in, This represents the maximum deviation of the temperature field between two adjacent outer layer iterations. This represents the maximum deviation of the reaction propulsion field between two adjacent outer iterations; when the following condition is met... and If the outer iteration has reached the convergence condition, it is considered that the outer iteration has reached the convergence condition; otherwise, it returns to the component distribution reconstruction and parameter update step to continue component distribution reconstruction, parameter update, inner block matrix solution and reaction propulsion update.

[0059] S408. By using the converged temperature field and the converged reaction propulsion field, the reactor isomorphic energy flow data, including the reactor friction fluid temperature, wall temperature, component molar flow rate, component molar fraction, local partial pressure, reaction propulsion, outlet temperature, outlet methanol conversion rate, and thermochemical efficiency, is obtained by reconstructing and solving the component distribution and thermal network equations. This completes the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

[0060] In this embodiment, after the outer layer iteration satisfies the convergence condition, the converged temperature field is used as the basis for... and convergent reaction propulsion field The component distribution in the overall mass transfer-reaction network and the thermal network equation in the overall isomorphic energy flow network are reconstructed and finally solved to obtain the reactor flow temperature, wall temperature, component molar flow rate, component molar fraction, local partial pressure, reaction propulsion rate, outlet temperature, outlet methanol conversion rate and thermochemical efficiency. The methanol conversion rate at the export port can be expressed as: ; in, Indicates the methanol conversion rate at the export site; Thermochemical efficiency can be calculated based on the ratio between the increased chemical energy from methanol cracking products and the solar radiation input, for example: ; in, Indicates thermochemical efficiency; Thermochemical efficiency can also be defined using an equivalent definition that includes the increase in the lower heating value of the product, depending on the specific performance evaluation requirements; Therefore, by coupling and assembling the overall isomorphic energy flow network and the overall mass transfer-reaction network, the one-dimensional steady-state analysis problem of the solar thermal methanol cracking hydrogen production reactor is transformed into an outer layer principal variable iteration and an inner layer block matrix solution problem, realizing the unified calculation of the temperature field, component distribution and reaction conversion characteristics along the process. The above-mentioned block matrix form, variable arrangement and relaxation update method can be equivalently adjusted according to the specific discretization method and variable selection, without affecting the essence of the steady-state modeling analysis based on the overall isomorphic network and hierarchical solution algorithm of this invention.

[0061] In this embodiment, the effectiveness of the one-dimensional steady-state isomorphic energy flow model is verified, and a set of trough-type solar thermal methanol cracking hydrogen production reactors are selected as the verification objects; the reactor structural parameters, catalyst bed parameters and operating boundary conditions are shown in Table 1. Table 1 is a table of key geometric parameters of the solar reactor experimental system. Table 1

[0062] The model inputs include direct normal irradiance (DNI), methanol inlet temperature, methanol inlet mass flow rate, ambient temperature, and reactor structural parameters. Under different operating conditions, the methanol conversion rate at the reactor outlet was calculated using the one-dimensional steady-state isomorphic energy flow modeling and analysis method described in this invention, and compared with the experimental results. The results are shown in Table 2. Table 2 is a comparison table of methanol conversion rates at the outlet of the solar thermochemical reactor. Table 2

[0063] As shown in Table 2, the method of the present invention can predict the methanol conversion rate at the outlet under different operating conditions, indicating that the established one-dimensional steady-state isomorphic energy flow model can reflect the main thermochemical coupling characteristics of the solar thermal methanol cracking hydrogen production reactor.

[0064] To further verify the predictive ability of the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model for the reactor's flow distribution characteristics, a three-dimensional multiphysics model of the reactor was established as a benchmark; such as Figure 8 and Figure 9 As shown, a comparison is presented between the friction-through temperature and conversion rate calculated by the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model and the results of the three-dimensional finite element model under different operating conditions; Figure 8 and Figure 9 It can be seen that, in the main flow direction of the reactor, the model of the present invention can better reflect the trend of temperature and conversion rate along the flow path; Table 3 further shows the comparison of the outlet temperature and outlet conversion rate results of the one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model and the three-dimensional finite element model at the outlet section under different operating conditions. Table 3 is a comparison table of outlet results of solar thermochemical reactor. Table 3

[0065] As shown in Table 3, the absolute error of the export conversion rate is <0.6%, indicating that the method of the present invention can obtain good export prediction results while maintaining low computational complexity. The above embodiments are only used to illustrate the feasibility and effectiveness of the method of the present invention. The experimental parameters, number of grids, number of working conditions and comparison models used do not constitute a limitation on the scope of protection of the present invention.

Claims

1. A method for isomorphic energy flow modeling of a photothermal methanol cracking hydrogen production reactor, characterized in that, Includes the following steps: S1. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters and operating boundary conditions, and divide the reactor along the preset axis according to the main flow direction of the fluid to obtain a preset number of segmented control bodies and main temperature nodes. S2. Based on structural parameters, operating boundary conditions, and segmented control volumes, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established by describing the methanol cracking reaction propulsion process, and a one-dimensional steady-state heat transfer and energy balance model is established by describing the basic thermal equilibrium process. S3. Based on the isomorphic modeling theory and key temperature nodes, the one-dimensional steady-state heat transfer and energy balance model is mapped to a local isomorphic energy flow network, and the one-dimensional methanol cracking reaction kinetics and mass transfer model is mapped to a local mass transfer-reaction network. The local isomorphic energy flow network and local mass transfer-reaction network of each segment control volume are coupled and assembled to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model. S4. Based on structural parameters and operational boundary conditions, a hierarchical solution algorithm combining outer-layer principal variable iteration and inner-layer block matrix solution is used to solve the one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model, thereby obtaining reactor isomorphic energy flow data and completing the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

2. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 1, characterized in that, S1 includes the following steps: S101. Based on the solar thermal methanol cracking hydrogen production reactor, obtain the structural parameters including the total length of the reactor and the operating boundary conditions including the direct normal irradiance, methanol inlet temperature and total molar flow rate of methanol inlet. S102. Based on the solar thermal methanol cracking hydrogen production reactor, establish the coordinates along the reactor axis and define the main fluid flow direction as the positive direction of the reactor axis. S103. Divide the total length of the reactor along the axial direction to obtain a preset number of segmented control bodies; S104. Based on the segmented control body, obtain the main temperature nodes including the representative temperature of the reaction mixture gas, the representative temperature of the inner wall of the metal absorption tube, the representative temperature of the outer wall of the metal absorption tube, the representative temperature of the inner wall of the glass tube, and the representative temperature of the outer wall of the glass tube.

3. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 1, characterized in that, S2 includes the following steps: S201. Based on structural parameters, operating boundary conditions, and segmented control volumes, the component molar flow rate at the reactor inlet is defined according to the total molar flow rate at the methanol inlet by describing the methanol cracking reaction propulsion process. S202. Define the molar flow rate of components within the segmented control volume, calculate the local component concentration, and define the reaction advance rate within the segmented control volume based on the main methanol cracking reaction, and obtain the mass conservation relationship of the molar flow rate of components at the outlet of the segmented control volume. S203. By integrating the component molar flow rates at the outlet of the segmented control volume, the total molar flow rate at the outlet of the segmented control volume is obtained, and the component molar fraction is obtained. S204. Based on the mole fraction of the components and the mixed gas pressure in the segmented control body, the local partial pressure of the components in the segmented control body is obtained. S205. Based on the component molar flow rate at the reactor inlet, the component molar flow rate in the segmented control body, the local component concentration, the reaction propulsion rate in the segmented control body, the mass conservation relationship of the component molar flow rate at the segmented control body outlet, the component molar fraction, and the local partial pressure of the component in the segmented control body, a one-dimensional methanol cracking reaction kinetics and mass transfer model is established. S206. Based on structural parameters, operating boundary conditions, and segmented control volume, the solar radiation heat input within the segmented control volume is defined by describing the basic thermal equilibrium process, according to the direct normal irradiance, the effective light-collecting area of ​​the segmented control volume, and the optical efficiency of the segmented control volume. S207. Based on the endothermic enthalpy of the methanol cracking reaction and the reaction propulsion rate in the segmented control body, the endothermic heat of the methanol cracking reaction is defined. S208. Based on the mass flow rate of the reaction mixture in the segmented control body and the equivalent isobaric specific heat capacity of the reaction mixture in the segmented control body, obtain the heat capacity flow rate of the reaction mixture in the segmented control body, and obtain the net sensible heat relationship and the change in sensible heat of the reaction mixture by defining the thermodynamic potential. S209. By defining the heat flow of the fluid endothermic branch, the heat flow of the radiation heat dissipation branch from the glass tube to the sky, and the heat flow of the convection heat dissipation branch from the glass tube to the environment, and combining the solar radiation heat input in the segmented control body, the heat endothermic reaction of methanol cracking, and the change in the sensible heat of the reaction mixture, a one-dimensional steady-state heat transfer and energy balance model is established.

4. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 3, characterized in that, The expression for the change in sensible heat of the reaction mixture is as follows: in, This represents the change in sensible heat of the reacting gas mixture. This represents the heat flow in the heat-absorbing branch of the fluid. This indicates that the methanol cracking reaction is endothermic. Indicates the first i The heat capacity flow rate of the reacting gas mixture within the body is controlled in segments. Indicates the first i Each segment controls the outlet temperature. Indicates the first i -1 segmented control body outlet temperature, Indicates the first i The mass flow rate of the reacting gas mixture within the body is controlled in segments. Indicates the first i The equivalent isobaric specific heat capacity of the reacting gas mixture in the body is controlled in segments; Definition of the first i The thermodynamic potential corresponding to each segmented control volume is given, and the net sensible heat relationship is obtained as follows: in, It represents thermal kinetic potential.

5. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 3, characterized in that, S3 includes the following steps: S301. Based on the isomorphic modeling theory and key temperature nodes, a one-dimensional steady-state heat transfer and energy balance model is mapped. By setting the convection heat transfer resistance inside the tube, the thermal conductivity resistance of the metal absorption tube, the radiation heat transfer resistance between tubes, the thermal conductivity resistance of the glass tube, the environmental convection heat dissipation resistance, and the sky radiation heat dissipation resistance, a locally isomorphic energy flow network including controlled heat sources, thermal resistance, heat sinks, and thermodynamic potential is constructed. S302. The one-dimensional methanol cracking reaction kinetics and mass transfer model are mapped. The inlet component state and the outlet component state are taken as the two ends of the local mass transfer-reaction network. The extent of the methanol cracking reaction in the segmented control volume is characterized by using the reaction propulsion branch containing mass kinetic potential, reaction resistance and equilibrium concentration terms, and a local mass transfer-reaction network is constructed. S303. Connect the local isomorphic energy flow network and the local mass transfer-reaction network of each segmented control volume in series along the fluid flow direction to obtain the overall isomorphic energy flow network and the overall mass transfer-reaction network, respectively. Then, using the temperature field, component distribution and reaction propulsion, couple and assemble the overall isomorphic energy flow network and the overall mass transfer-reaction network to obtain a one-dimensional steady-state overall isomorphic energy flow and mass transfer-reaction network model.

6. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 5, characterized in that, S301 includes the following steps: S3011. Based on the isomorphic modeling theory and the main temperature nodes, the representative temperatures of the reaction mixture gas, the inner wall of the metal absorption tube, the outer wall of the metal absorption tube, the inner wall of the glass tube, and the outer wall of the glass tube are mapped to the reaction mixture gas node, the inner wall of the metal absorption tube node, the outer wall of the metal absorption tube node, the inner wall of the glass tube node, and the outer wall of the glass tube node in the main temperature nodes, respectively. An environment node and an equivalent sky node are set to obtain the equivalent network nodes. S3012, Map the effective solar radiation heat input as a controlled heat source connected to the node on the outer wall of the metal absorption tube, map the heat endothermic reaction of methanol cracking as a controlled heat sink at the node of the reaction mixture gas, and map the temperature rise effect of the reaction mixture gas flowing axially through the segmented control body as a thermodynamic potential. S3013. The branch between the inner wall node of the metal absorption tube and the reaction mixed gas node is set as the in-tube convective heat transfer resistance, the branch between the inner wall node of the metal absorption tube and the outer wall node of the metal absorption tube is set as the metal absorption tube thermal conductivity resistance, the branch between the outer wall node of the metal absorption tube and the inner wall node of the glass tube is set as the inter-tube radiative heat transfer resistance, the branch between the inner wall node of the glass tube and the outer wall node of the glass tube is set as the glass tube thermal conductivity resistance, the branch between the outer wall node of the glass tube and the environmental node is set as the environmental convective heat dissipation resistance, and the branch between the outer wall node of the glass tube and the equivalent sky node is set as the sky radiative heat dissipation resistance. S3013. Based on the operating boundary conditions and the structural parameters of each segment control body, the heat transfer resistance branch is obtained by determining the convection heat transfer resistance inside the pipe, the thermal conductivity resistance of the metal absorption tube, the radiation heat transfer resistance between the pipes, the thermal conductivity resistance of the glass tube, the environmental convection heat dissipation resistance, and the sky radiation heat dissipation resistance. S3014. Based on the net sensible heat relationship and heat transfer path, connect the controlled heat source, heat transfer thermal resistance branch, controlled heat sink and thermodynamic potential to form a locally isomorphic energy flow network topology. S3015. Based on the relationship between the thermal potential of each node and the heat flow of each heat transfer thermal resistance branch, establish a local energy conservation equation that satisfies Kirchhoff's laws, and combine it with the local isomorphic energy flow network topology to construct a local isomorphic energy flow network containing controlled heat sources, thermal resistance, heat sinks and thermal kinetic potential.

7. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 5, characterized in that, S302 includes the following steps: S3021. Map the one-dimensional methanol cracking reaction kinetics and mass transfer model, and take the inlet component state and outlet component state as the port states of the local mass transfer-reaction network, respectively. S3022. The mass conservation relationship between the inlet component state and the outlet component state is used as the basic port constraint of the local mass transfer-reaction network. S3023. The mass kinetic potential of the reaction propulsion branch is characterized by the deviation of the local methanol concentration from the methanol equilibrium concentration. S3024. Based on the local component concentration, partial pressure, catalyst parameters, and equilibrium correction terms, the kinetic equivalence factor is determined, and the reaction resistance is obtained based on the methanol cracking kinetic rate constant and the kinetic equivalence factor at the local temperature. S3025. Based on the chemical reaction equilibrium constraints under local temperature and local component conditions, determine the methanol equilibrium concentration and use it as the equilibrium concentration term. S3026. By using mass kinetic potential as the driving force for reaction propulsion, reaction resistance as the limiting term for reaction propulsion, and equilibrium concentration as the equilibrium benchmark for reaction direction, a reaction propulsion branch is formed. S3027. Represent the reaction propulsion branch as the equivalent driving-resistance relationship in the mass transfer-reaction network, and calculate the reaction propulsion amount based on the local reaction rate and equivalent reaction scale parameters, and use it as the output of the mass transfer-reaction network to construct the local mass transfer-reaction network.

8. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 7, characterized in that, The expression for the mass kinetic potential is as follows: in, It represents the kinetic potential. Indicates the first i The methanol concentration is controlled in a segmented manner at a local level. Indicates the equilibrium concentration of methanol. Indicates the first i Each segment controls the local concentration of carbon monoxide. Indicates the first i Each segment controls the local hydrogen concentration. Indicates local temperature The concentration equilibrium constant at this point; The expression for the reaction resistance is as follows: in, Indicates reaction resistance, Indicates local temperature The methanol cracking kinetic rate constant is given below. This represents the kinetic equivalence factor.

9. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 1, characterized in that, S4 includes the following steps: S401. Based on structural parameters and operational boundary conditions, initialize the fluid temperature field and reaction propulsion field to obtain the current fluid temperature field and current reaction propulsion field. S402. Based on the current reaction propulsion field, the molar flow rate distributions of methanol, carbon monoxide, and hydrogen along the path are reconstructed to calculate the molar fractions of the components and the local partial pressures. S403. Based on the current fluid temperature field and the molar flow rate distribution along the flow path of methanol, carbon monoxide and hydrogen, update the fluid physical properties, heat capacity flow rate, local convective heat transfer coefficient, various heat transfer resistances, solar radiation heat input and heat absorption of methanol cracking reaction to obtain known energy flow data. S404. Based on known energy flow data, the thermal network equation is transformed into a linear block matrix equation and solved using a one-dimensional steady-state global isomorphic energy flow and mass transfer-reaction network model to obtain the inner layer unknown vector. S405. Extract the inner layer unknown vector to obtain the reactor outlet temperature, thermodynamic potential of each segment control volume, heat flow of the fluid endothermic branch, heat flow of the sky radiation heat dissipation branch and heat flow of the environmental convection heat dissipation branch for the next outer layer iteration. S406. Using the thermodynamic potential of each segment of the control volume in the next outer layer iteration, update the current temperature field to obtain the temperature field of the next outer layer iteration. Combined with the local component distribution and local partial pressure, calculate the methanol cracking reaction rate using the methanol decomposition reaction kinetic model to obtain the original reaction propulsion. Then, relax and update the current reaction propulsion field to obtain the reaction propulsion field of the next outer layer iteration. S407. Calculate the maximum deviation of the temperature field and the maximum deviation of the reaction propulsion field between two adjacent outer layer iterations, and determine whether the maximum deviation of the temperature field is less than the preset temperature tolerance and whether the maximum deviation of the reaction propulsion field is less than the preset propulsion tolerance. If so, the outer layer iteration is determined to be converged, and the converged temperature field and the converged reaction propulsion field are obtained. If not, return to step S402 to continue reconstructing the component distribution, updating the parameters, solving the inner block matrix, and updating the reaction propulsion until the convergence condition is met; S408. By using the converged temperature field and the converged reaction propulsion field, the reactor isomorphic energy flow data, including the reactor friction fluid temperature, wall temperature, component molar flow rate, component molar fraction, local partial pressure, reaction propulsion, outlet temperature, outlet methanol conversion rate, and thermochemical efficiency, is obtained by reconstructing and solving the component distribution and thermal network equations. This completes the isomorphic energy flow modeling of the photothermal methanol cracking hydrogen production reactor.

10. The isomorphic energy flow modeling method for a photothermal methanol cracking hydrogen production reactor according to claim 9, characterized in that, The expression for the linear block matrix equation is as follows: in, The coefficient matrix of the block matrix equation is represented. Let represent the right-hand vector of the block matrix equation. Represents the vector of unknowns in the inner layer. This represents the segmented outlet temperature vector. Represents the thermal force vector. This represents the heat flux vector of the heat-absorbing branch of the fluid. This represents the heat flow vector of the radiation cooling branch from the glass tube to the sky. This represents the heat flow vector of the convection cooling branch from the glass tube to the environment.

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