A method and related equipment for simulating ammonia energy storage based on local non-thermal equilibrium.

Abstract

This invention discloses a simulation method and related equipment for ammonia energy storage based on the local non-thermal equilibrium method, belonging to the field of thermochemical energy storage in solar tower power plants. This method constructs a three-dimensional model of the ammonia decomposition reaction tube, which overcomes the shortcomings of the two-dimensional model, which can only show the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with the axial direction and radius. It can reflect the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with the circumferential angle. The invention proposes to use the local non-thermal equilibrium method to study the ammonia decomposition reaction tube on the heat-absorbing side of the solar thermal ammonia energy storage system, replacing the traditional continuous homogeneous medium model. Due to the different heat transfer characteristics, there is a temperature difference between the gas and the catalyst particles in practical applications. Studying the temperature change laws of the gas and catalyst particle sides separately can obtain more accurate results and reveal the energy transport characteristics of the thermal-chemical energy conversion of ammonia energy storage more profoundly.

Description

Technical Field

[0001] This invention belongs to the field of thermochemical energy storage in solar tower power plants, specifically involving an ammonia energy storage simulation method and related equipment based on the local non-thermal balance method. Background Technology

[0002] Currently, the energy landscape is changing, and energy transition is imminent. The energy sector is about to enter the era of clean and environmentally friendly new energy sources, and finding and developing efficient and sustainable new energy sources is an important future energy goal. Since the large-scale use of fossil fuels, the economy has developed rapidly. However, the greenhouse effect caused by burning fossil fuels has brought many problems to human production and life. To solve the greenhouse effect problem caused by fossil fuels, research on many new energy sources, including solar energy, has gradually begun. Solar energy has large reserves and is easily obtained, making it a very promising clean energy source. To better utilize solar energy, solar thermal power generation systems are usually paired with energy storage subsystems. Energy storage technologies are divided into three categories: sensible heat energy storage, latent heat energy storage, and thermochemical energy storage. Thermochemical energy storage is based on a reversible chemical reaction. The energy storage medium receives solar radiation and undergoes an endothermic reaction, converting the focused solar energy into chemical energy. The reverse reaction is an exothermic reaction, and the products release energy to heat the working fluid to generate electricity. Among thermochemical energy storage systems, ammonia is the system with the greatest energy storage potential. Its energy storage density is much higher than that of methane, metal hydrides, metal oxides, and metal hydroxide systems, and its reaction temperature is relatively low. Thermochemical energy storage systems based on ammonia synthesis / decomposition reactions have fewer side reactions and higher controllability. Operating at ambient temperature, pressurizing ammonia allows it to be stored in liquid form, facilitating automatic separation of ammonia from hydrogen / nitrogen (3:1) mixtures. This also allows for the storage of more ammonia in the same volume of storage tank.

[0003] Currently, simulation studies of ammonia decomposition reactions mainly employ one-dimensional or two-dimensional models, which can only investigate the variations in temperature and ammonia mass fraction with tube length, without detailed research on the cross-sectional parameter characteristics. For example, Wang et al. introduced a two-dimensional model to study the influence of reactor structure and different parameters on energy storage performance when studying thermochemical energy storage reactors; Chen et al. introduced a one-dimensional model to study the performance and feasibility of the exothermic side of ammonia energy storage. Furthermore, since catalyst particles are uniformly distributed in the ammonia decomposition reaction tube, most current studies use the local heat balance method to study the catalyst and flowing gas, simplifying the process by using a single equation to describe the heat transfer between them, or focusing only on gas heat transfer while ignoring catalyst heat transfer. For instance, Meng et al. studied the performance of thermochemical energy storage reactors based on the local heat balance method; HI et al. used this method to study the internal heat transfer process of traditional solar thermal absorbers; Hideo et al. studied the thermal responsiveness of catalyst reactors utilizing solar thermal energy, mainly focusing on gas heat transfer performance.

[0004] Therefore, to promote the development of solar ammonia thermochemical energy storage technology, it is essential to possess comprehensive energy and mass transport characteristics of the ammonia decomposition process. Ammonia energy storage systems operate at high temperatures and pressures; a lack of clarity regarding their internal energy and mass transport processes poses significant safety risks. Most studies simulate ammonia decomposition reaction tubes using Fluent simulation software. This software primarily focuses on physical properties and lacks models for chemical reactions, compromising calculation accuracy. Consequently, it fails to effectively reflect energy and mass transport characteristics, severely limiting the comprehensive study of reactor performance parameters and hindering optimal design. Summary of the Invention

[0005] To overcome the shortcomings of the above-mentioned technologies, the present invention provides an ammonia energy storage simulation method and related equipment based on the local non-thermal equilibrium method, which can solve the technical problem that existing simulation methods cannot accurately simulate the parameter characteristics on the cross-section of the ammonia decomposition reaction tube.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for simulating ammonia energy storage based on a local non-thermal equilibrium approach, comprising:

[0008] A three-dimensional model of the ammonia decomposition reaction tube was obtained based on the local non-thermal equilibrium method.

[0009] The ammonia decomposition reaction tube model was spatially discretized using the finite volume method to obtain a discrete model.

[0010] The discrete model was solved using an iterative method to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube.

[0011] Furthermore, a porous media framework was used to simulate the state of catalyst particles in the ammonia decomposition reaction tube; based on the local non-thermal equilibrium method, the mixed gas mass control equation, the mixed gas side energy control equation, and the porous media side energy control equation were constructed to obtain the ammonia decomposition reaction tube model.

[0012] Furthermore, before discretizing the ammonia decomposition reaction tube model, the ammonia decomposition reaction tube model is subjected to mesh generation.

[0013] Furthermore, the Gauss-Seidel iterative method is used to solve the discrete model.

[0014] Furthermore, the discrete model was solved using an iterative method to obtain the energy and mass parameters inside the ammonia decomposition reaction tube. Data simulation analysis was then performed on the energy and mass parameters to obtain the simulation results of ammonia energy storage inside the ammonia decomposition reaction tube.

[0015] Furthermore, the energy and quality parameters include the gas temperature at any location within the ammonia decomposition reaction tube, the catalyst particle temperature, the tube wall temperature, and the mass fraction of ammonia.

[0016] Furthermore, the boundary condition values ​​and initial conditions are input into the discrete model, and the energy and mass parameters inside the ammonia decomposition reaction tube are obtained by iterative calculation.

[0017] An ammonia energy storage simulation system based on the local non-thermal equilibrium method, comprising the steps of implementing the aforementioned ammonia energy storage simulation method based on the local non-thermal equilibrium method, including:

[0018] The 3D modeling module is used to create a 3D model of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method, thus obtaining the ammonia decomposition reaction tube model.

[0019] The model discretization module is used to spatially discretize the ammonia decomposition reaction tube model using the finite volume method to obtain a discrete model.

[0020] The calculation module is used to solve the discrete model using an iterative method to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube.

[0021] An apparatus comprising:

[0022] Memory, used to store computer programs;

[0023] A processor is used to implement the steps of the above-described ammonia energy storage simulation method based on the local non-thermal equilibrium method when executing the computer program.

[0024] A computer-readable storage medium storing a computer program, which, when executed by a processor, is used to implement the steps of the above-described ammonia energy storage simulation method based on the local non-thermal equilibrium method.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a simulation method for ammonia energy storage based on the local non-thermal equilibrium method. This method uses the local non-thermal equilibrium method to create a three-dimensional model of the ammonia decomposition reaction tube, and employs the finite volume method to spatially discretize the model. Finally, an iterative method is used to solve the model, achieving accurate simulation of ammonia energy storage within the ammonia decomposition reaction tube. This method constructs a three-dimensional model of the ammonia decomposition reaction tube, overcoming the limitations of two-dimensional models which can only represent the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to axial and radial directions. This method can reflect the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to the circumferential angle. It proposes using the local non-thermal equilibrium method to study the ammonia decomposition reaction tube on the endothermic side of a photothermal ammonia energy storage system, replacing the traditional continuous homogeneous medium model. Due to differences in heat transfer characteristics, the temperatures of the gas and catalyst particles differ in practical applications. Studying the temperature change patterns on the gas and catalyst particle sides separately yields more accurate results and more profoundly reveals the energy transport characteristics of the thermal-chemical energy conversion in ammonia energy storage.

[0027] Preferably, in this invention, the governing equations for the gas side and the porous medium side of the mixed gas are constructed based on the local non-thermal equilibrium method, replacing the traditional continuous homogeneous medium model. Due to the different heat transfer characteristics, there is a temperature difference between the gas and the catalyst particles in practical applications. Studying the gas and catalyst particle temperatures separately can yield more accurate results.

[0028] Preferably, in this invention, the Gauss-Seidel iterative method is used to solve the discrete model. Since the Gauss-Seidel method incorporates the values ​​obtained in the current iteration during the calculation process, it converges faster. Therefore, using the Gauss-Seidel iterative method is more beneficial to the solution process and improves the calculation speed and processing efficiency.

[0029] Preferably, in this invention, data simulation analysis is performed on the energy quality parameters, that is, the energy quality parameters are post-processed to generate three-dimensional graphs and temperature change curves, thereby obtaining the simulation results of ammonia energy storage in the ammonia decomposition reaction tube, making the simulation results more intuitive. Attached Figure Description

[0030] Figure 1 A flowchart of an amino energy storage simulation method based on the local non-thermal equilibrium method provided in this embodiment of the invention;

[0031] Figure 2 This is a schematic diagram of the cross-sectional mesh division and node setting of the ammonia decomposition reaction tube provided in an embodiment of the present invention;

[0032] Figure 3 The following diagrams are provided for the present invention to solve the distribution of gas temperature and ammonia mass fraction using an ammonia energy storage simulation method based on local non-thermal equilibrium; wherein, (a) is the temperature distribution of gas temperature at different cross sections; and (b) is the temperature distribution of ammonia mass fraction at different cross sections.

[0033] Figure 4 The graphs showing the variation of average temperature and average ammonia mass fraction with pipe length are provided for embodiments of the present invention.

[0034] Figure 5 A flowchart of an amino energy storage simulation method based on the local non-thermal equilibrium method provided by the present invention;

[0035] Figure 6 This invention provides a schematic diagram of an amino energy storage simulation system based on the local non-thermal equilibrium method. Detailed Implementation

[0036] This invention provides a method for simulating amino energy storage based on the local non-thermal equilibrium method, such as... Figure 5 As shown, it includes the following steps:

[0037] S1: Three-dimensional modeling of the ammonia decomposition reaction tube was performed based on the local non-thermal equilibrium method to obtain the ammonia decomposition reaction tube model. The specific steps are as follows:

[0038] A porous media framework was used to simulate the state of catalyst particles in the ammonia decomposition reaction tube. Based on the local non-thermal equilibrium method, the mass control equation of the mixed gas, the energy control equation of the mixed gas side, and the energy control equation of the porous media side were constructed to obtain the ammonia decomposition reaction tube model.

[0039] S2: The ammonia decomposition reaction tube model is meshed and spatially discretized using the finite volume method to obtain a discrete model.

[0040] S3: The discrete model is solved by iterative method to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube.

[0041] Specifically, the Gauss-Seidel iterative method is used to solve the discrete model. The boundary conditions and initial conditions are input into the discrete model, and the energy and mass parameters in the ammonia decomposition reaction tube are obtained through iterative calculation. Data simulation analysis is performed on the energy and mass parameters to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube.

[0042] Among them, the above-mentioned energy and quality parameters include the gas temperature at any location inside the ammonia decomposition reaction tube, the catalyst particle temperature, the tube wall temperature, and the mass fraction of ammonia.

[0043] like Figure 6 As shown, the present invention also provides an ammonia energy storage simulation system based on the local non-thermal equilibrium method, comprising: a three-dimensional modeling module for three-dimensional modeling of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method to obtain an ammonia decomposition reaction tube model; a model discretization module for spatially discretizing the ammonia decomposition reaction tube model using the finite volume method to obtain a discrete model; and a calculation module for solving the discrete model using an iterative method to obtain the ammonia energy storage simulation results within the ammonia decomposition reaction tube.

[0044] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the amino energy storage simulation method based on the local non-thermal equilibrium method.

[0045] When the processor executes the computer program, it implements the above-mentioned steps for simulating ammonia energy storage based on the local non-thermal equilibrium method. For example, it performs three-dimensional modeling of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method to obtain the ammonia decomposition reaction tube model; it discretizes the ammonia decomposition reaction tube model in space using the finite volume method to obtain the discrete model; and it solves the discrete model using the iterative method to obtain the ammonia energy storage simulation results in the ammonia decomposition reaction tube.

[0046] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system, such as: a three-dimensional modeling module for three-dimensional modeling of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method to obtain the ammonia decomposition reaction tube model; a model discretization module for spatially discretizing the ammonia decomposition reaction tube model using the finite volume method to obtain a discrete model; and a calculation module for solving the discrete model using an iterative method to obtain the ammonia energy storage simulation results in the ammonia decomposition reaction tube.

[0047] For example, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing preset functions, wherein the instruction segments describe the execution process of the computer program in the ammonia energy storage simulation device based on the local non-thermal equilibrium method. For example, the computer program can be divided into a three-dimensional modeling module, a model discretization module, and a calculation module; the specific functions of each module are as follows: the three-dimensional modeling module is used to perform three-dimensional modeling of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method to obtain the ammonia decomposition reaction tube model; the model discretization module is used to spatially discretize the ammonia decomposition reaction tube model using the finite volume method to obtain a discrete model; the calculation module is used to solve the discrete model using an iterative method to obtain the ammonia energy storage simulation results within the ammonia decomposition reaction tube.

[0048] The ammonia energy storage simulation device based on the local non-thermal equilibrium method can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The ammonia energy storage simulation device based on the local non-thermal equilibrium method may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the above examples of ammonia energy storage simulation devices based on the local non-thermal equilibrium method do not constitute a limitation on ammonia energy storage simulation devices based on the local non-thermal equilibrium method. It may include more components than described above, or combine certain components, or different components. For example, the ammonia energy storage simulation device based on the local non-thermal equilibrium method may also include input / output devices, network access devices, buses, etc.

[0049] The processor referred to can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor. The processor is the control center of the ammonia energy storage simulation based on the local non-thermal equilibrium method, connecting various parts of the ammonia energy storage simulation device using various interfaces and lines.

[0050] The memory can be used to store the computer program and / or modules. The processor realizes various functions of the ammonia energy storage simulation device based on the local non-thermal balance method by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory.

[0051] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a given function (such as sound playback or image playback). The data storage area may store data created based on the use of the mobile phone (such as audio data and phonebook entries). Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0052] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the aforementioned amino energy storage simulation method based on a local non-thermal equilibrium method.

[0053] If the modules / units integrated in the ammonia energy storage simulation system based on the local non-thermal balance method are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0054] Based on this understanding, the present invention can implement all or part of the processes in the above-mentioned ammonia energy storage simulation method based on the local non-thermal equilibrium method. This can also be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the above-mentioned ammonia energy storage simulation method based on the local non-thermal equilibrium method. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or a preset intermediate form, etc.

[0055] The computer-readable storage medium may include any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0056] It should be noted that the content contained in the computer-readable storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0057] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0058] Example

[0059] To address the issues mentioned in the background section: in the simulation study of ammonia decomposition reaction, the use of one-dimensional or two-dimensional models cannot provide detailed research on the parameter characteristics of the cross section; the use of the local heat balance method to study it and the flowing gas ignores the heat transfer process of the catalyst, resulting in poor simulation accuracy; and the use of Fluent simulation software, due to the lack of models for chemical reactions, cannot guarantee the accuracy of calculations.

[0060] Therefore, this embodiment provides an ammonia energy storage simulation method based on the local non-thermal equilibrium method. This method can effectively reflect the energy and mass transport process of the ammonia decomposition reaction tube on the endothermic side of the solar thermal power generation ammonia energy storage subsystem in three dimensions, and obtain higher accuracy simulation results.

[0061] like Figure 1 As shown in the figure, the specific steps of the ammonia energy storage simulation method based on the local non-thermal equilibrium method provided in this embodiment are as follows:

[0062] Step 1: The state of catalyst particles in the ammonia decomposition reaction tube is simulated using a porous media framework. The mass control equation and the energy control equations for the porous media side and the mixed gas side are constructed based on the local non-thermal equilibrium method.

[0063] In step 1, the following assumptions are made when establishing the ammonia decomposition reaction tube model: (1) Radiative heat transfer between the tube wall and the gas and solid is ignored; (2) The length-to-diameter ratio of the reaction tube is large, and the heat transfer in the axial direction of the tube wall is ignored, and only the radial and axial directions are considered; (3) The flow rate of the mixed gas composed of ammonia, nitrogen and hydrogen is slow and is regarded as laminar flow; (4) The diameter of the solar spot after focusing is relatively large compared with the size of a single ammonia decomposition endothermic reaction tube, and the solar energy flux density is uniformly distributed in the circumferential direction of the reaction tube and only varies with the tube length.

[0064] The governing equations constructed in step 1 include:

[0065] (1) Quality control equation:

[0066]

[0067] Where: f—mass fraction of ammonia in the mixed gas; D f —Diffusion coefficient of the mixed gas; ρ m —Density of the gas mixture; M —Molar mass; u m — Mixed gas flow rate; R' — Ammonia decomposition reaction rate; z — Ammonia decomposition reaction tube length parameter; ε — Ammonia decomposition reaction tube catalyst porosity; r — Ammonia decomposition reaction tube radius; θ — Ammonia decomposition reaction tube circumferential angle.

[0068] (2) Energy control equations on the mixed gas side:

[0069]

[0070] In the formula: E f —Gas energy; t —Time parameter; p —Gas pressure; T f —Gas temperature; τ —Shear force vector; h i —Intermediate quantity 1; J i —Intermediate quantity 2; v —Velocity vector T s —Catalyst particle temperature; S f —Source term; h sf —Heat transfer coefficient between catalyst particles and gas

[0071] Under steady-state conditions, according to the above assumption (2), it can be simplified to:

[0072]

[0073] In the formula: C p,m—Specific heat capacity of the mixed gas; λ f — Thermal conductivity of the mixed gas; ΔH — Enthalpy change of the ammonia decomposition reaction; A fs —Specific surface area of ​​catalyst particles.

[0074] (3) The energy control equation for the porous media side (i.e., catalyst particles) can be simplified based on the above assumptions as follows:

[0075]

[0076] In the formula: λ s — Thermal conductivity of porous media.

[0077] (4) The heat conduction between the inner and outer surfaces of the tube is determined according to Fourier's law of heat conduction for circular tubes:

[0078]

[0079] Where: q—total heat transferred through the tube wall in the ammonia decomposition reaction; T—temperature at various points within the tube wall in the ammonia decomposition reaction; T wo —Temperature of the outer wall of the ammonia decomposition reaction tube; T wi —Temperature of the inner wall of the ammonia decomposition reaction tube; r o —Outer diameter (radius) of the ammonia decomposition reaction tube; r i —Inner diameter (radius) of the ammonia decomposition reaction tube; λ —thermal conductivity of the ammonia decomposition reaction tube wall.

[0080] (5) Relationship between pressure drop of mixed gas and length of reaction tube:

[0081]

[0082] In the formula: d p —Average diameter of catalyst particles; μ —Viscosity of mixed gas; α' —Correction factor 1; C2 —Correction factor 2; Δp —Total pressure drop in ammonia decomposition reaction tube; L —Total tube length.

[0083] Preferably, the Temkin-Pyzhev equation is used to describe the ammonia decomposition reaction rate:

[0084]

[0085] In the formula: k0—pre-exponential factor of reaction rate, with units consistent with the reaction rate; E a —Activation energy of reaction; k —Gas constant; K p —Chemical reaction equilibrium constant; p H2 p NH3 — Partial pressure of gases; different subscripts represent the partial pressure of different gases.

[0086] The heat transfer coefficient h between catalyst particles and gas sf Using the Wakao formula:

[0087]

[0088] After the construction in step 1, the ammonia decomposition reaction tube model is obtained.

[0089] Step 2: The model is meshed, and the ammonia decomposition reaction tube model is spatially discretized using the finite volume method to obtain a discrete model. Specifically, based on the characteristics of a circular tube, a cylindrical coordinate system is established, where coordinate points (i, j, k) represent the radius r, circumferential angle θ, and axial length z of the ammonia decomposition reaction tube, respectively. Figure 2 As shown, in the spatial domain, r is divided into g Δr, θ into m Δθ, and z into q Δz. The intermediate point is point P, the boundary is e, w, n, s, the adjacent nodes are points E, W, N, S, and the upper layer node is point P0. Here, the set of nodes with the same z coordinate is called a layer of infinitesimal element, which is defined from the smallest to the largest as the first layer of infinitesimal element to the last layer of infinitesimal element. The FVM method (finite volume method) is used to discretize equations (1), (2), and (3). The computational domain is divided into a series of non-repeating control volumes. A node represents the entire infinitesimal element. The differential equation in the conservation form is integrated within the determined control volume infinitesimal element. Taking the quality control equation (1) as an example, the integral form can be obtained:

[0090]

[0091] In the formula: r P r w r e r n r s — The distance from different boundaries or nodes to the origin of the cross-section coordinate system; θ w θ e —The circumferential angle formed by the lines connecting the center of different boundaries to the origin; f z0+dz f z0 —Ammonia mass fraction at different nodes.

[0092] The partial derivatives with respect to spatial coordinates that exist after integration are handled using linear differences, i.e.:

[0093]

[0094] In the formula: fW, fP, fN, fS, fE — ammonia mass fraction at different nodes.

[0095] Following the discretization steps described above, all formulas can be processed into the same format, as shown in formula (11):

[0096]

[0097] In the formula: φ represents the energy quality parameters, which include the temperature of the mixed gas, the temperature of the porous medium, and the mass fraction of ammonia in the mixed gas; a and b represent coefficients, and different equations and nodes at different positions have different coefficient expressions.

[0098] After step 2 is executed, a discrete model is obtained.

[0099] Step 3: The Gauss-Seidel iterative method is used to solve the discrete model. The boundary condition values ​​and initial conditions are input into the discrete model, and the energy and mass parameters in the ammonia decomposition reaction tube are obtained by iterative calculation. The energy and mass parameters are simulated and analyzed to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube. Specifically: In the ammonia decomposition reaction tube of the solar thermal power generation ammonia energy storage system, one side receives solar irradiation, and the other side can be insulated compared with the heat of solar irradiation. In practical applications, the types of different nodes are determined according to the reaction tube conditions. The nodes on the outer wall of the tube are divided into boundary points on the side receiving solar irradiation and boundary points on the side of insulation. The heat conduction of the nodes between the inner and outer walls of the tube is calculated using Equation (5). In Equation (5), q is taken according to the actual situation of different boundary points. The boundary point on the side of insulation is regarded as the second type of boundary condition with a heat flux density of 0. The side receiving solar irradiation is regarded as the second type, and the vector sum of solar irradiation heat and heat dissipation is considered as the total heat flux. When receiving solar irradiation, the emissivity and absorptivity are determined according to the actual material of the ammonia decomposition reaction tube. For gases and solids inside the pipe, nodes can be classified into heat exchange nodes with the inner wall, inlet nodes, outlet nodes, and inner nodes. Nodes with different locations, types, and equations have different expressions.

[0100] Then, based on different operating conditions, specific boundary condition values ​​are input, and initial conditions are set. Based on the initial pressure and equation (6), the pressure drop from the inlet to the outlet of the ammonia decomposition reaction tube can be calculated, and the pressure value corresponding to each node is determined according to the assumption of a linear distribution.

[0101] The Gauss-Seidel iterative method is used for calculation. In each loop, the calculated value of the next step is substituted into the subsequent formulas. The loop ends when the error between the calculated value and the assumed value is less than the set error. During the calculation, the steady-state value of each layer is calculated first. After the result of the layer converges, the calculation of the next layer begins, until the calculation of the last infinitesimal element is completed, and the operation ends.

[0102] Step 4: Obtain the gas temperature, catalyst particle temperature, tube wall temperature, and ammonia mass fraction distribution at various points inside the tube. Analyze and simulate based on the gas temperature, catalyst particle temperature, tube wall temperature, and ammonia mass fraction distribution, for example, generating a 3D graph and temperature change curve to obtain more intuitive simulation results of ammonia energy storage inside the ammonia decomposition reaction tube.

[0103] To further illustrate the specific implementation process of the method of the present invention, this embodiment takes a superheated ammonia decomposition reaction tube on the endothermic side of an ammonia energy storage as an example for specific calculation analysis.

[0104] 1. Example parameters

[0105] Table 1 Parameters of the ammonia decomposition reaction tube

[0106]

[0107] One side of the tube wall is considered to receive solar radiation, while the other side is insulated. The formula for the energy flux density of solar irradiance is as follows:

[0108]

[0109] In the formula: P h —The energy remaining after reflection by a one-way mirror; σ HF —Effective deviation: the larger the value, the more uniform the distribution of solar flux density; the smaller the value, the denser the distribution of solar flux density; x, y —the absolute position of a single ammonia decomposition reaction tube in the entire receiver.

[0110] After actual optimization, equation (13) is adopted:

[0111]

[0112] 2. Calculation Results and Analysis

[0113] The main program of this method runs in MATLAB, and the obtained data is processed as follows: Figure 3 and Figure 4 As shown.

[0114] Figure 3 This describes the distribution of gas temperature and ammonia mass fraction at different cross-sections within the ammonia decomposition reaction tube, as shown in the following figures. Figure 3 (a) and Figure 3 As shown in (b), the temperature inside the tube is not uniform or varies with the radius, and the tube wall temperature can differ by up to 300K.

[0115] Figure 4The curves show the variation of average gas temperature, average catalyst particle temperature, average inner wall temperature, average outer wall temperature, and average ammonia mass fraction as a function of tube length within the ammonia decomposition reaction tube. The average ammonia mass fraction gradually decreases with tube length, exhibiting a trend of initially slow, then fast, and then slowing down again. The inlet temperature is lower, resulting in a slower ammonia decomposition reaction. As the temperature rises with solar radiation, the ammonia decomposition reaction accelerates, and the ammonia mass fraction decreases. When the ammonia mass fraction decreases to a certain level, the reactant concentration decreases, and the reaction slows down again, thus causing peaks in the average gas temperature, average catalyst particle temperature, average inner wall temperature, and average outer wall temperature. Simultaneously, from... Figure 4 It can be seen that there is a temperature difference of about 3K between the catalyst particles and the gas. This temperature difference still exists after the flow rate is increased and solar radiation is focused, and it even shows a greater trend.

[0116] In summary, this method overcomes the limitation of the field, which is limited to two-dimensional models that can only represent the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to axial direction and radius. It can reflect the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to circumferential angle.

[0117] This embodiment provides an ammonia energy storage simulation method based on the local non-thermal equilibrium method, which has the following advantages compared with existing simulation methods:

[0118] This method uses a local non-thermal equilibrium method to model the ammonia decomposition reaction tube in three dimensions, and employs the finite volume method to spatially discretize the model. Finally, an iterative method is used to solve the model, achieving accurate simulation of ammonia energy storage within the ammonia decomposition reaction tube. This method constructs a three-dimensional model of the ammonia decomposition reaction tube, overcoming the limitations of two-dimensional models that can only represent the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to axial and radial directions. This method can reflect the temperature and ammonia mass fraction at the cross-section of the ammonia decomposition reaction tube with respect to the circumferential angle. It proposes using the local non-thermal equilibrium method to study the ammonia decomposition reaction tube on the endothermic side of a photothermal ammonia energy storage system, replacing the traditional continuous homogeneous medium model. Due to differences in heat transfer characteristics, there are temperature differences between the gas and catalyst particles in practical applications. Studying the temperature change patterns on the gas and catalyst particle sides separately yields more accurate results and more profoundly reveals the energy transport characteristics of the thermal-chemical energy conversion in ammonia energy storage.

[0119] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. An aminosilicon energy storage simulation method based on local nonthermal equilibrium method, characterized in that, include: A three-dimensional model of the ammonia decomposition reaction tube was obtained based on the local non-thermal equilibrium method. The ammonia decomposition reaction tube model was spatially discretized using the finite volume method to obtain a discrete model. The discrete model was solved using an iterative method to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube. A porous media framework was used to simulate the state of catalyst particles inside the ammonia decomposition reaction tube. Based on the local non-thermal equilibrium method, the mixed gas mass control equation, the mixed gas side energy control equation, and the porous medium side energy control equation are constructed to obtain the ammonia decomposition reaction tube model. The discrete model was solved by iterative method to obtain the energy and mass parameters in the ammonia decomposition reaction tube. Data simulation analysis was performed on the energy and mass parameters to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube. Among them, the energy and quality parameters include the gas temperature at any location inside the ammonia decomposition reaction tube, the catalyst particle temperature, the tube wall temperature, and the mass fraction of ammonia.

2. The ammonia energy storage simulation method based on the local non-thermal equilibrium method according to claim 1, characterized in that, Before discretizing the ammonia decomposition reaction tube model, the ammonia decomposition reaction tube model is meshed.

3. The ammonia energy storage simulation method based on the local non-thermal equilibrium method according to claim 1, characterized in that, The Gauss-Seidel iterative method is used to solve the discrete model.

4. The ammonia energy storage simulation method based on the local non-thermal equilibrium method according to claim 1, characterized in that, The boundary conditions and initial conditions are input into the discrete model, and the energy and mass parameters inside the ammonia decomposition reaction tube are obtained by iterative calculation.

5. An ammonia energy storage simulation system based on a local non-thermal equilibrium method, used to implement the steps of the ammonia energy storage simulation method based on a local non-thermal equilibrium method as described in any one of claims 1-4, characterized in that, include: The 3D modeling module is used to create a 3D model of the ammonia decomposition reaction tube based on the local non-thermal equilibrium method, thus obtaining the ammonia decomposition reaction tube model. The model discretization module is used to spatially discretize the ammonia decomposition reaction tube model using the finite volume method to obtain a discrete model. The calculation module is used to solve the discrete model using an iterative method to obtain the simulation results of ammonia energy storage in the ammonia decomposition reaction tube.

6. A device, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the amino energy storage simulation method based on the local non-thermal equilibrium method as described in any one of claims 1-4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it is used to implement the steps of the amino energy storage simulation method based on the local non-thermal equilibrium method as described in any one of claims 1-4.

Images