Simulation analysis method for hydrogen absorption and desorption of hydrogen storage tank based on JMAK model

Abstract

The invention relates to the technical field of hydrogen storage, in particular to a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model, and is mainly used for optimizing evaluation and improvement of performance of a hydrogen storage tank in the hydrogen adsorption and release process. Compared with a traditional simulation method, the method has the advantages that the physical model of the hydrogen storage tank is constructed, thermodynamic and dynamic characteristics in the hydrogen absorption and desorption process are combined, particularly, a PCT result curve obtained through a PCT performance test of a hydrogen storage material is utilized, a JMAK model is combined, and experimental data are subjected to fitting processing through origin drawing software; and on the basis of data measured by an experiment, a COMSOL simulation software is used for carrying out detailed modeling and analysis on the absorption and release process of the hydrogen, so that the simulation precision of the hydrogen storage and release process is optimized, and the dynamic behavior and thermodynamic behavior of the hydrogen in the hydrogen storage tank are captured. According to the invention, accurate simulation of key factors such as hydrogen absorption and release rate, temperature distribution, pressure change and the like in the hydrogen storage tank can be realized.

Description

Technical Field

[0001] The present application relates to the field of hydrogen storage technology, and in particular to a simulation analysis method for hydrogen absorption and desorption of a hydrogen storage tank based on a JMAK model. Background Art

[0002] Hydrogen storage technology is the core of hydrogen energy application, and the key lies in the efficient and safe storage and release of hydrogen. The hydrogen storage tank is the main component of the hydrogen storage system, and undertakes the important tasks of hydrogen storage, adsorption and release. With the widespread application of hydrogen energy, the performance requirements of hydrogen storage tanks are getting higher and higher, especially in the process of hydrogen adsorption and release. In order to ensure the safety and efficiency of hydrogen storage tanks in actual operation, in-depth simulation analysis of their performance is required.

[0003] The traditional design method of hydrogen storage tanks mainly relies on experiments and experience. This method is not only costly, but also has a long cycle and is difficult to fully reflect the actual behavior of hydrogen storage tanks under various working conditions. In recent years, with the development of computer technology, multi-physics simulation software such as COMSOL has been widely used in hydrogen storage technology research. COMSOL can simultaneously simulate the coupling effects of hydrogen flow, heat conduction and heat transfer, providing a powerful tool for the performance analysis of hydrogen storage tanks. However, current technology often faces problems such as high modeling complexity and unsystematic analysis framework when using COMSOL for simulation analysis of hydrogen storage tanks, which limits its effectiveness in practical applications.

[0004] Specifically, hydrogen storage tanks undergo complex thermodynamic and fluid dynamic processes during hydrogen adsorption and release. The flow of hydrogen in the tank is closely related to the expansion and contraction of the material. Traditional simulation methods are usually unable to fully integrate these factors, and cannot fully describe the thermodynamic and kinetic processes of hydrogen storage, resulting in deviations between simulation results and actual conditions. Therefore, a kinetic model analysis method is urgently needed to improve the design and performance prediction of hydrogen storage tanks.

[0005] The simulation analysis method of hydrogen absorption and desorption of hydrogen storage tanks based on the JMAK model of COMSOL can effectively integrate multi-physics field effects such as thermodynamics and fluid mechanics, providing a more accurate and comprehensive analysis method. This method can not only improve the design accuracy of hydrogen storage tanks, but also optimize their performance while ensuring safety, and improve the overall efficiency of hydrogen energy systems. Through the application of this method, more reliable theoretical support and practical guidance can be provided for the development of hydrogen storage technology. Summary of the invention

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] According to the first aspect of the present invention, the present invention claims a method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on a JMAK model, comprising:

[0008] Obtaining physical parameters of the hydrogen storage tank, and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model;

[0009] Configuring the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank;

[0010] Select a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material, and express the simulation result of the hydrogen storage material with a mathematical equation;

[0011] A grid division strategy is adopted to grid the hydrogen storage tank model, data is extracted from the simulation results, and an optimization scheme for designing the hydrogen storage tank is analyzed and output.

[0012] Furthermore, the method of obtaining the physical parameters of the hydrogen storage tank and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model also includes:

[0013] The physical parameters of the hydrogen storage tank include at least:

[0014] Internal structure, shell structure, hydrogen flow area, hydrogen storage material area, size, shape and related interfaces.

[0015] Further, configuring the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank, further includes:

[0016] Inputting the physical and chemical properties of the hydrogen storage material, including at least density, thermal conductivity, and specific heat capacity;

[0017] Inputting the physical and chemical properties of the filling hydrogen, including at least density, viscosity, thermal conductivity, specific heat capacity, and average molar mass of hydrogen;

[0018] Input material properties of the hydrogen storage tank, including at least specific heat capacity, thermal conductivity, porosity, hydrogen absorption enthalpy change, particle volume ratio, reaction fraction, and hydrogen atomic ratio.

[0019] Further, selecting a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material also includes:

[0020] The filling hydrogen flows in from the top of the hydrogen storage tank at a constant pressure, and the bottom and outer surface of the hydrogen storage tank perform convection heat exchange;

[0021] The hydrogen storage materials are all spherical particles evenly distributed in the hydrogen storage tank, and the filled hydrogen undergoes a hydrogen absorption / desorption reaction in the hydrogen storage material reaction bed, releasing heat and consuming hydrogen during the hydrogen absorption process, and absorbing heat and generating hydrogen during the hydrogen desorption process, thereby performing a local thermal balance process;

[0022] The heat transfer process, mass transfer process, thermodynamic process, kinetic process and distributed ordinary differential equation of the filled hydrogen in the hydrogen storage material are analyzed.

[0023] Furthermore, expressing the simulation results of the hydrogen storage material using mathematical equations also includes:

[0024] When analyzing the heat transfer process of the filled hydrogen in the hydrogen storage material, the heat transfer process includes two parts: heat conduction and convection. According to Fourier's law, the law of conservation of energy and the control equation under the non-steady-state process, the expression is as follows:

[0025]

[0026] Among them, ρ s C p is the product of the density and specific heat capacity of the hydrogen storage material; t is the time, in seconds; T is the temperature, in K;

[0027] ρ g C pg is the product of the density and specific heat capacity of hydrogen; is the hydrogen flow rate in m / s; S is the source term of the equation, which is related to the hydrogen absorption / desorption dynamics. In the hydrogen absorption process, S is the internal heat source term, and the expression is:

[0028]

[0029] Among them, M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; M H2 is the average molar mass of hydrogen, which is 0.0020159 kg / mol; ε is the porosity of the hydrogen storage material, in %; ρ s is the density of hydrogen storage material, in kg / m 3 ; H / M is the hydrogen atomic ratio, the unit is 1; t is the time, the unit is s; H / M is the hydrogen atomic ratio; ΔH is the enthalpy change of hydrogen absorption / desorption, the unit is J / (kg*K).

[0030] Furthermore, the mass transfer process of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0031] When analyzing the mass transfer process of the filled hydrogen in the hydrogen storage material, the pressure-driven flow is defined by Darcy's law, and the expression is:

[0032]

[0033] in, is the flow rate of hydrogen in the porous medium, in m / s; K is the permeability of the powder bed, and assuming that the porous medium is isotropic, the K value is 1e -8 m 2 ;μ g is the dynamic viscosity of hydrogen, in kg / (m*s); is the pressure gradient, in pa, where the velocity field u depends on the permeability and the dynamic viscosity μ of the fluid has a pressure gradient drive;

[0034] Substituting into the continuity equation:

[0035]

[0036] Among them, ρ g is the density of hydrogen, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; u is the flow rate of hydrogen in the porous medium, in m / s; Q m is the source term of the continuity equation, is the consumption of hydrogen in the hydrogen storage material during the hydrogen absorption process or the generation of hydrogen in the hydrogen storage material during the hydrogen release process, and its expression is:

[0037]

[0038] Among them, ρ s is the density of hydrogen storage material, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; H / M is the hydrogen atomic ratio, in 1; t is the time, in s.

[0039] Furthermore, the thermodynamic process of the hydrogen storage material is expressed by mathematical equations, which also includes:

[0040] When analyzing the thermodynamic process of the hydrogen filling in the hydrogen storage material, the following relationship is obtained through the relationship between Gibbs free energy and other thermodynamic parameters:

[0041] ΔG = ΔH - TΔS;

[0042]

[0043] ΔG is Gibbs free energy, P H2 is the equilibrium hydrogen pressure; K p is the equilibrium constant, which indicates the partial pressure of each component under equilibrium conditions;

[0044] In the thermodynamic analysis of chemical reactions, K p It is an important parameter for describing the equilibrium state of gaseous reactants and products, and Gibbs free energy provides a thermodynamic basis for determining whether a reaction is spontaneous.

[0045] Among them, ΔH is the enthalpy change of hydrogen absorption and desorption; ΔS is the entropy variable; R is the gas constant. The above formula can be used to calculate lnp H2 The relationship between 1 / T is called the Hovantoff curve.

[0046] During the simulation, the equilibrium pressure of the hydrogen storage material is a function of the hydrogen atomic ratio and temperature, and the formula is:

[0047]

[0048] Wherein, f(H / M) is the polynomial fitting equation of the PCT curve at the reference temperature, representing the relationship between the equilibrium pressure and H / M at the reference temperature; T ref is the reference temperature, T is the temperature of the hydrogen storage material, in K;

[0049] For hydrogen storage materials, f(H / M) at the reference temperature is a 9th-order polynomial, with the formula:

[0050]

[0051] Among them, a i is the fitting coefficient, and its unit is 1.

[0052] Furthermore, the kinetic process of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0053] When analyzing the kinetic process of the hydrogen filling in the hydrogen storage material, the JMAK model is used;

[0054] The expression of the JMAK model is as follows:

[0055] [-ln(1-α)] 1 / n =kt;

[0056] After taking the logarithm of both sides, we can get the following result:

[0057] ln[-ln(1-α)]=nlnk+nlnt;

[0058] Wherein, k is the rate constant of hydrogenation or dehydrogenation reaction; α is the reaction fraction converted to hydride hydrogen storage material corresponding to time t; n is the dimension that determines the abstract model; the linear relationship between ln[-ln(1-α)] and lnt is established by the above formula; the value of n is obtained from the slope, and the value of the reaction rate constant k is calculated in combination with the intercept value;

[0059] In the process of hydrogenation or dehydrogenation, hydrogen storage materials must overcome energy barriers to undergo hydrogen absorption / desorption reactions. The energy barrier is the activation energy, expressed as E a It is expressed that the Arrhenius equation is used to obtain:

[0060]

[0061] R is the gas constant; T is the reaction temperature;

[0062] Taking the logarithm of both sides of the above formula gives:

[0063]

[0064] B is the parameter obtained after taking the logarithm, which is represented as the intercept on the linear fitting result graph;

[0065] It can be seen that lnk is linearly related to 1 / T, and its slope is -E a / R, and then calculate the absorption / desorption rate constant k at different temperatures, and then draw the relationship curve between lnk and 1 / T, and obtain the activation energy E by linear fitting the curve. a , and then explain the intrinsic mechanism of the change in hydrogen absorption / desorption kinetics from the perspective of activation energy.

[0066] Furthermore, the distributed ordinary differential equation of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0067] When analyzing the distributed ordinary differential equation of the hydrogen filling in the hydrogen storage material, the density of the hydrogen storage material is used as the dependent variable of the distributed ordinary differential equation, the source term of the equation is f, and the damping is d a , the quality coefficient is e a , the expression is

[0068]

[0069] Where f is the source term for the mass rate of hydrogen; d a Damping is 1-ε; quality coefficient e a is 0; to solve the ordinary differential equation, it is necessary to set the initial value of the dependent variable and the initial time derivative. Taking the hydrogen absorption process as an example, the initial value is ρ emp , that is, the density of the hydrogen storage material when there is no hydrogen;

[0070] Initial time derivative for:

[0071]

[0072] The outer surface of the hydrogen storage tank is exposed to natural convection under air, and the remaining surfaces are set to thermal insulation. Hydrogen flows in from the inlet at a constant pressure.

[0073] Furthermore, a grid division strategy is adopted to grid the hydrogen storage tank model, data is extracted from the simulation results, and an optimization scheme for designing the hydrogen storage tank is analyzed and output, which also includes:

[0074] A first fine-grained grid is used in the hydrogen flow region to capture flow details;

[0075] Applying a second fine-grained grid on the hydrogen storage tank wall and key locations, wherein the second fine-grained grid has a smaller size than the first fine-grained grid;

[0076] Ensure that the quality of meshing meets the convergence requirements of the numerical solution;

[0077] Performing data extraction on the simulation results to obtain the flow velocity, pressure field and temperature field distribution of hydrogen, the temperature field distribution and density change of the hydrogen storage material, and the reaction rate;

[0078] Compare simulation data under different operating conditions and analyze performance changes during hydrogen adsorption and release;

[0079] Generate visual charts and reports to display the simulation results, and output an optimization plan for designing the hydrogen storage tank based on the analysis results.

[0080] The present application relates to the field of hydrogen storage technology, and in particular to a simulation analysis method for hydrogen absorption and desorption of hydrogen storage tanks based on the JMAK model, which is mainly used to optimize the evaluation and improvement of the performance of hydrogen storage tanks during hydrogen adsorption and release. Compared with the traditional simulation method, this method constructs a physical model of the hydrogen storage tank, and combines the thermodynamic and kinetic characteristics of the hydrogen absorption and desorption process, especially using the PCT result curve obtained by the PCT performance test of the hydrogen storage material, and combining the JMAK model, fitting the experimental data through the origin drawing software, and using the COMSOL simulation software based on the experimental measured data to perform detailed modeling and analysis of the hydrogen absorption and desorption process, which is used to optimize the simulation accuracy of the hydrogen storage and release process, so as to capture the kinetic behavior and thermodynamic behavior of hydrogen in the hydrogen storage tank. The present invention can realize the accurate simulation of key factors such as the hydrogen absorption and desorption rate, temperature distribution and pressure change in the hydrogen storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 A work flow chart of a method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on a JMAK model as claimed in an embodiment of the present invention;

[0082] Figure 2 A three-dimensional modeling diagram of a hydrogen storage tank for a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0083] Figure 3 A PCT curve diagram of a hydrogen storage material for a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0084] Figure 4 A fitted Hovantoff curve diagram of a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0085] Figure 5 A hydrogen storage material hydrogen absorption rate diagram of an experiment of a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0086] Figure 6 A Hovantoff activation energy fitting curve of a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0087] Figure 7 A phase transformation principle diagram of a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on the JMAK model claimed in an embodiment of the present invention;

[0088] Figure 8 A JMAK schematic diagram of a method for simulating the analysis of hydrogen absorption and desorption of hydrogen in a hydrogen storage tank based on a JMAK model as claimed in an embodiment of the present invention;

[0089] Fig. 9 A two-dimensional axisymmetric grid division diagram of a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0090] Fig.10 A graph showing the variation of reaction fraction over time of a simulation analysis method for hydrogen absorption and desorption of hydrogen in a hydrogen storage tank based on a JMAK model as claimed in an embodiment of the present invention;

[0091] Fig.11 A result diagram of temperature variation inside a hydrogen storage tank of a hydrogen storage tank simulation analysis method based on a JMAK model as claimed in an embodiment of the present invention;

[0092] Fig.12 A graph showing the result of the average pressure change inside a hydrogen storage tank according to a hydrogen storage tank hydrogen absorption and desorption simulation analysis method based on the JMAK model as claimed in an embodiment of the present invention. DETAILED DESCRIPTION

[0093] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0094] The terms "first", "second" and "third" in this application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second" and "third" can explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications in the embodiments of the present application (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0095] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0096] According to the first embodiment of the present invention, the present invention claims a method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model, referring to Figure 1 ,include:

[0097] Obtaining physical parameters of the hydrogen storage tank, and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model;

[0098] Configuring the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank;

[0099] Select a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material, and express the simulation result of the hydrogen storage material with a mathematical equation;

[0100] A grid division strategy is adopted to grid the hydrogen storage tank model, data is extracted from the simulation results, and an optimization scheme for designing the hydrogen storage tank is analyzed and output.

[0101] Furthermore, the method of obtaining the physical parameters of the hydrogen storage tank and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model also includes:

[0102] The physical parameters of the hydrogen storage tank include at least:

[0103] Internal structure, shell structure, hydrogen flow area, hydrogen storage material area, size, shape and related interfaces.

[0104] Among them, in this embodiment, the modeling step includes using COMSOL software to create a two-dimensional axisymmetric geometric model of the hydrogen storage tank. The model should reflect the internal structure, shell structure, hydrogen flow area and hydrogen storage material area of ​​the hydrogen storage tank in detail. The model construction needs to consider the specific size, shape and related interfaces of the hydrogen storage tank to ensure that the model can truly simulate the hydrogen storage tank under actual working conditions.

[0105] Further, configuring the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank, further includes:

[0106] Inputting the physical and chemical properties of the hydrogen storage material, including at least density, thermal conductivity, and specific heat capacity;

[0107] Inputting the physical and chemical properties of the filling hydrogen, including at least density, viscosity, thermal conductivity, specific heat capacity, and average molar mass of hydrogen;

[0108] Input material properties of the hydrogen storage tank, including at least specific heat capacity, thermal conductivity, porosity, hydrogen absorption enthalpy change, particle volume ratio, reaction fraction, and hydrogen atomic ratio.

[0109] In this embodiment, p g is the density of hydrogen, in kg / m 3 ;μ g is the dynamic viscosity of hydrogen, in kg / (m*s); g is the thermal conductivity of hydrogen, in W / (m*K); C pg is the specific heat capacity of hydrogen, in J / (kg*K); M g is the average molar mass of hydrogen, in kg / mol.

[0110] Hydrogen storage tank material properties: Input the thermodynamic properties of the hydrogen storage tank wall material, such as specific heat capacity, thermal conductivity, porosity, hydrogen absorption enthalpy change, particle volume ratio, reaction fraction, hydrogen atomic ratio, etc. s is the density of hydrogen storage material, in kg / m 3 ; s is the thermal conductivity of the hydrogen storage material, in W / (m*K); C ps is the specific heat capacity of hydrogen storage material, in J / (kg*K); the porosity is ε, in %; the enthalpy change of hydrogen absorption / desorption is ΔH, in J / mol; the particle volume ratio is β, in %; the reaction fraction is f, in %; the hydrogen atomic ratio is H / M, in 1; M s is the average molar mass of hydrogen, in kg / mol.

[0111] Basic assumptions of numerical simulation:

[0112] The diameter of the hydrogen storage tank is d; the height is L, in meters; hydrogen flows in at a constant pressure from the top, and the pressure is P ref , the unit is pa; the bottom and the outer surface conduct convection heat transfer, and the heat transfer coefficient is h e , the unit is W / (m 2 / K), modeling graphics see Figure 2 ,In COMSOL, in order to simplify the calculation, it is modeled as a two-dimensional axisymmetric structure.

[0113] Further, selecting a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material also includes:

[0114] The filling hydrogen flows in from the top of the hydrogen storage tank at a constant pressure, and the bottom and outer surface of the hydrogen storage tank perform convection heat exchange;

[0115] The hydrogen storage materials are all spherical particles evenly distributed in the hydrogen storage tank, and the filled hydrogen undergoes a hydrogen absorption / desorption reaction in the hydrogen storage material reaction bed, releasing heat and consuming hydrogen during the hydrogen absorption process, and absorbing heat and generating hydrogen during the hydrogen desorption process, thereby performing a local thermal balance process;

[0116] The heat transfer process, mass transfer process, thermodynamic process, kinetic process and distributed ordinary differential equation of the filled hydrogen in the hydrogen storage material are analyzed.

[0117] Among them, in this embodiment, it is assumed that hydrogen is an ideal gas during the hydrogen storage process; the particles of the hydrogen storage material are all spheres and are evenly distributed in the tank; the powder bed is treated as a porous medium, the flow of hydrogen in the porous medium conforms to Darcy's law, and hydrogen absorption / desorption reactions occur in the hydrogen storage material reaction bed, heat is released and hydrogen is consumed during the hydrogen absorption process, and heat is absorbed and hydrogen is generated during the hydrogen desorption process; local thermal equilibrium treatment is performed, that is, it is assumed that during the reaction process, the temperature of the hydrogen storage material and the hydrogen are the same; and radiation heat transfer during the reaction process is ignored.

[0118] Furthermore, expressing the simulation results of the hydrogen storage material using mathematical equations also includes:

[0119] When analyzing the heat transfer process of the filled hydrogen in the hydrogen storage material, the heat transfer process includes two parts: heat conduction and convection. According to Fourier's law, the law of conservation of energy and the control equation under the non-steady-state process, the expression is as follows:

[0120]

[0121] Among them, ρ s C p is the product of the density and specific heat capacity of the hydrogen storage material; t is the time, in seconds; T is the temperature, in K;

[0122] ρ g C pg is the product of the density and specific heat capacity of hydrogen; is the hydrogen flow rate in m / s; S is the source term of the equation, which is related to the hydrogen absorption / desorption dynamics. In the hydrogen absorption process, S is the internal heat source term, and the expression is:

[0123]

[0124] Among them, M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; M H2 is the average molar mass of hydrogen, which is 0.0020159 kg / mol; ε is the porosity of the hydrogen storage material, in %; ρ s is the density of hydrogen storage material, in kg / m 3 ; H / M is the hydrogen atomic ratio, the unit is 1; t is the time, the unit is s; H / M is the hydrogen atomic ratio; ΔH is the enthalpy change of hydrogen absorption / desorption, the unit is J / (kg*K).

[0125] Furthermore, the mass transfer process of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0126] When analyzing the mass transfer process of the filled hydrogen in the hydrogen storage material, the pressure-driven flow is defined by Darcy's law, and the expression is:

[0127]

[0128] in, is the flow rate of hydrogen in the porous medium, in m / s; K is the permeability of the powder bed, and assuming that the porous medium is isotropic, the K value is 1e -8 m 2 ;μ g is the dynamic viscosity of hydrogen, in kg / (m*s); is the pressure gradient, in pa, where the velocity field u depends on the permeability and the dynamic viscosity μ of the fluid has a pressure gradient drive;

[0129] Substituting into the continuity equation:

[0130]

[0131] Among them, ρ g is the density of hydrogen, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; u is the flow rate of hydrogen in the porous medium, in m / s; Q m is the source term of the continuity equation, is the consumption of hydrogen in the hydrogen storage material during the hydrogen absorption process or the generation of hydrogen in the hydrogen storage material during the hydrogen release process, and its expression is:

[0132]

[0133] Among them, ρ s is the density of hydrogen storage material, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; H / M is the hydrogen atomic ratio, in 1; t is the time, in s.

[0134] Furthermore, the thermodynamic process of the hydrogen storage material is expressed by mathematical equations, which also includes:

[0135] When analyzing the thermodynamic process of the hydrogen filling in the hydrogen storage material, the study of the thermodynamic properties of the hydrogen storage material mainly studies the enthalpy and entropy values ​​of the formation of hydrides during the hydrogen absorption (desorption) process of the material. It can be seen from the following formula that the hydrogen absorption (desorption) process of the hydrogen storage material is accompanied by the generation and absorption of heat, the forward reaction is an exothermic hydrogen absorption reaction, and the reverse process is an endothermic hydrogen release reaction.

[0136] The following relationship is obtained by the relationship between Gibbs free energy and other thermodynamic parameters:

[0137] ΔG = ΔH - TΔS;

[0138]

[0139]

[0140] ΔG is Gibbs free energy, P H2 is the equilibrium hydrogen pressure; K p is the equilibrium constant, which indicates the partial pressure of each component under equilibrium conditions;

[0141] In the thermodynamic analysis of chemical reactions, K p It is an important parameter for describing the equilibrium state of gaseous reactants and products, and Gibbs free energy provides a thermodynamic basis for determining whether a reaction is spontaneous.

[0142] Among them, ΔH is the enthalpy change of hydrogen absorption and desorption; ΔS is the entropy variable; R is the gas constant. The above formula can be used to calculate lnp H2 The relationship between 1 / T is called the Hovantoff curve.

[0143] During the simulation, the equilibrium pressure of the hydrogen storage material is a function of the hydrogen atomic ratio and temperature, and the formula is:

[0144]

[0145] Wherein, f(H / M) is the polynomial fitting equation of the PCT curve at the reference temperature, representing the relationship between the equilibrium pressure and H / M at the reference temperature; T ref is the reference temperature, T is the temperature of the hydrogen storage material, in K;

[0146] For hydrogen storage materials, f(H / M) at the reference temperature is a 9th-order polynomial, with the formula:

[0147]

[0148] Among them, a i is the fitting coefficient, and its unit is 1.

[0149] In this embodiment, the measured hydrogen storage material takes the intermetallic compound LaNi5 as a reference, and the PCT hydrogen absorption curves measured at four different temperatures by the volume method are experimental results, such as Figure 3 , and the experimental results were analyzed by thermodynamics and kinetics.

[0150] In the process of quantitatively studying the thermodynamic properties of hydrogen storage materials, the logarithmic relationship curve between equilibrium hydrogen pressure and temperature is established by combining the Hovantoff equation with the PCT curve at different temperatures. The Origin software is used for fitting, and the following should be obtained: Figure 4 The curve shown;

[0151] The absorption / desorption process of most hydrogen storage materials can be described by the kinetic mechanism of nucleation and growth (i.e., JMAK model). The specific analysis method is shown in the modeling steps. The fitting results of the experimental results are shown in Figure 5 As shown;

[0152] The thermodynamic parameters of hydrogen storage materials can explain the difficulty of hydrogen storage materials to absorb / desorb hydrogen. The larger the enthalpy change ΔH, the more stable the hydride formed by the hydrogen storage material, and the more difficult the dehydrogenation reaction. On the contrary, the smaller the enthalpy change ΔH, the worse the thermal stability of the hydride formed by the hydrogen storage material, and the better the hydrogen absorption / desorption performance of the material. The size of the reaction entropy ΔS reflects the stability of the hydride material system (usually measured by the number of microscopic states), and the Gibbs free energy can indirectly reflect the degree of spontaneity of the hydrogenation reaction and dehydrogenation reaction of the hydrogen storage material.

[0153] In the process of quantitatively studying the thermodynamic properties of hydrogen storage materials, the logarithmic relationship curve between equilibrium hydrogen pressure and temperature (i.e., lnp H2 and 1 / T), a straight line should be obtained. H2 The relationship curve with 1 / T can obtain the slope and intercept of the straight line, the thermodynamic parameters ΔG, ΔH, ΔS in the process of hydrogen storage material absorbing / desorbing hydrogen, and can intuitively reflect the performance of hydrogen storage material in forming hydrides. The size of the formation enthalpy is directly related to the platform pressure of the PCT curve of alloy absorbing / desorbing hydrogen: the larger the formation enthalpy, the higher the platform pressure, which is conducive to the desorption of hydrogen but not conducive to the absorption of hydrogen; conversely, the smaller the formation enthalpy, the lower the platform pressure, which is conducive to the absorption of hydrogen but not conducive to the desorption of hydrogen.

[0154] P eqis the equilibrium pressure of the hydrogen storage material, in units of pa. The equilibrium pressure of the hydrogen storage material refers to the hydrogen pressure when the hydrogen reaches a dynamic equilibrium between the hydrogen storage material and the gas phase at a specific temperature. This pressure is critical to the design and simulation of the hydrogen storage system because it directly affects the hydrogen adsorption and release capacity of the material. During the simulation process, the equilibrium pressure helps to determine the performance indicators of the hydrogen storage material, such as hydrogen storage capacity and hydrogen release rate. In the hydrogen storage performance test PCT curve, that is, the pressure value in the area where the pressure in the corresponding curve remains constant, corresponds to the equilibrium pressure of the material in stable hydrogenation or dehydrogenation, and the magnitude of the hydrogen absorption / desorption enthalpy change is directly related to the equilibrium pressure of the alloy hydrogen absorption / desorption PCT curve; the larger the hydrogen absorption / desorption enthalpy change, the higher the platform pressure, which is conducive to the hydrogen release of the gas storage material but not conducive to hydrogen absorption; conversely, the smaller the hydrogen absorption / desorption enthalpy change, the lower the equilibrium pressure, which is conducive to hydrogen absorption of the hydrogen storage material but not conducive to hydrogen release.

[0155] Test the PCT curve of hydrogen absorption / desorption of hydrogen storage materials at different temperatures; secondly, select appropriate platform pressures corresponding to different temperatures to draw the relationship curve between equilibrium hydrogen pressure and temperature (i.e. lnp H2 The relationship curve with 1 / T), Figure 6 It is the Hovantoff activation energy fitting curve when absorbing hydrogen; the slope of the straight line is calculated after linear fitting of the curve, and then the reaction heat of the hydrogen storage material when absorbing hydrogen is obtained, and the change of entropy value during the hydrogen storage material absorbing hydrogen is calculated by the intercept of the straight line, and the fitting process of the hydrogen release process is the same.

[0156] Furthermore, the kinetic process of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0157] When analyzing the kinetic process of the hydrogen filling in the hydrogen storage material, the JMAK model is used;

[0158] The expression of the JMAK model is as follows:

[0159] [-ln(1-α)] 1 / n =kt;

[0160] After taking the logarithm of both sides, we can get the following result:

[0161] ln[-ln(1-α)]=nlnk+nlnt;

[0162] Wherein, k is the rate constant of hydrogenation or dehydrogenation reaction; α is the reaction fraction converted to hydride hydrogen storage material corresponding to time t; n is the dimension that determines the abstract model; the linear relationship between ln[-ln(1-α)] and lnt is established by the above formula; the value of n is obtained from the slope, and the value of the reaction rate constant k is calculated in combination with the intercept value;

[0163] In the process of hydrogenation or dehydrogenation, hydrogen storage materials must overcome energy barriers to undergo hydrogen absorption / desorption reactions. The energy barrier is the activation energy, expressed as E a It is expressed that the Arrhenius equation is used to obtain:

[0164]

[0165] R is the gas constant; T is the reaction temperature;

[0166] Taking the logarithm of both sides of the above formula gives:

[0167]

[0168] B is the parameter obtained after taking the logarithm, which is represented as the intercept on the linear fitting result graph;

[0169] It can be seen that lnk is linearly related to 1 / T, and its slope is -E a / R, and then calculate the absorption / desorption rate constant k at different temperatures, and then draw the relationship curve between lnk and 1 / T, and obtain the activation energy E by linear fitting the curve. a , and then explain the intrinsic mechanism of the change in hydrogen absorption / desorption kinetics from the perspective of activation energy.

[0170] Among them, in this embodiment, the hydrogen storage material's hydrogen absorption / desorption kinetics is a physical quantity that studies the speed of the material's hydrogen absorption / desorption, and is an important indicator for measuring its practical application. The hydrogen absorption reaction is actually a chemical reaction between the solid phase and the gas phase, and the reaction process can be divided into three stages: ① surface activation; ② nucleation and growth of the initial hydride, accompanied by lattice expansion; ③ generation of a large amount of hydride until hydrogen absorption is saturated. For the hydrogen desorption reaction, the reaction process can be divided into two stages: ① decomposition of surface hydrides and formation and growth of alloy phase nuclei: ② continuous decomposition of hydrides, and gradual formation of alloy phases until complete hydrogen desorption. Figure 7 (1) is a two-phase region with α+β and Figure 7 (2) No α+β (continuous moving interface), where 1 represents chemical adsorption; 2 represents surface penetration; 3 represents the diffusion of hydrogen in the α phase; 4 represents the diffusion of hydrogen in the β phase; 5 represents nucleation and growth; 6 represents chemical reaction. When the hydrogen pressure is higher than the equilibrium pressure of the hydrogen storage material, a β layer is generated on the surface of the particle. Then, the β layer will grow along the radial direction of the particle. Therefore, hydrogen must diffuse through the β layer to the front of the α→β phase transition (that is, the diffusion of hydrogen atoms in the β phase). If the nucleation and growth rate of β is slow, there will be an α+β two-phase region between α and β (such as Figure 7 (1)). If the nucleation and growth rate of β is fast, the α+β two-phase region will decrease until it is almost unobservable. Therefore, the phase transition from α to β can be simplified by chemical reaction (e.g. Figure 7(2)). The interface of α and β can be simplified as a continuously moving interface, an assumption that has been adopted by many kinetic models, such as the Jander and Chou models. The main methods for measuring hydrogen absorption and desorption are the Sievert and flowing volume methods. The Sievert method is the most commonly used measurement technique and can be easily implemented using a system of known volume when temperature and pressure are accurately measured. Using the pressure change, the amount of hydrogen absorbed and desorbed can be calculated using the modified ideal gas state equation. In most cases, the initial pressure of the hydrogen volume is higher than the plateau pressure of the α-β equilibrium. The β layer will be generated rapidly, so in most cases, kinetic models such as the Jander, JMAK and Chou models can be applied.

[0171] For some alloy hydrogen storage materials, for example, LaNi5 in the present invention, that is, the equation when the abstract model dimension n=1, the partial derivative of the hydrogen atomic ratio H / M with respect to time is:

[0172]

[0173] Among them, H / M max is the maximum hydrogen absorption capacity under the condition of k, the value of k is related to the hydrogen absorption temperature and pressure, and the expression of k is:

[0174]

[0175] Where k0 is an independent temperature coefficient, i.e., the standard rate constant; R is the gas constant; in particular, for the hydrogen release process, the corresponding expression of k is:

[0176]

[0177] The variables in the formula are different from those in the hydrogen absorption process in that the corresponding E a , T, P e All parameters are under hydrogen desorption.

[0178] In general, the JMAK model is used to analyze the kinetics of the hydrogen storage process, which is divided into the following steps:

[0179] First, draw the hydrogen absorption / desorption kinetic curves at different temperatures. Here, only the curve of the time portion from 0 to t end (corresponding to the hydrogen storage amount being approximately equal to the maximum value) is needed; the reaction fraction α of the hydrogen storage material converted into hydride is calculated by dividing the hydrogen absorption / desorption amount at each time point t by the maximum hydrogen absorption / desorption amount corresponding to t end; the ln[-ln(1-α)]=nlnk+nlnt relationship curve is drawn using the α corresponding to each time point t, and the slope and intercept of the straight line are calculated by linear fitting of the curve, thereby obtaining the value of lnk at different temperatures;

[0180] According to the Arrhenius equation, the relationship curve between lnk and 1 / R is plotted, and then the activation energy of hydrogen absorption / desorption of hydrogen storage materials is calculated.

[0181] From the mass transfer equation:

[0182]

[0183] And the partial derivative equation of the hydrogen atom ratio H / M with respect to time:

[0184]

[0185] The mass rate equation for hydrogen can be obtained as follows:

[0186] For the hydrogen absorption process:

[0187]

[0188] For the hydrogen desorption process:

[0189]

[0190] Among them, m a With m d Represent the rates of hydrogen absorption and desorption respectively; E a and E d are the activation energies of hydrogen absorption and desorption (reaction enthalpy change). Note that the equilibrium pressures of hydrogen absorption and desorption are P eq They are not the same. It can be seen from the PCT curve that there is a difference between the two platforms. This phenomenon is called the hysteresis effect (it is generally believed that this is related to the lattice stress caused by the expansion of the metal lattice during the hydrogenation of the alloy). Generally speaking, the smaller the pressure hysteresis, the better.

[0191] In the process of hydrogen storage, volume expansion is inevitable. Taking the hydrogen absorption process as an example, the volume change of the hydrogen storage material as a porous medium must be considered. In the COMSOL software simulation process, the volume change of the hydrogen storage material is combined with the JMAK model principle, such as Figure 8 As shown in the figure, the change in volume is caused by the volume expansion of the hydrogen storage material particles when they absorb hydrogen. Assuming that the volume of the hydrogen storage material filling bed remains unchanged, the change in the bed porosity and the change in the material particles during the hydrogen storage process cannot be ignored and must be calculated using the following formula:

[0192] ε=1-(1-ε0)[β-1)f+1]

[0193] Among them, ε is the porosity of the hydrogen storage material reaction bed; ε0 is the initial porosity; β is the volume expansion ratio before and after hydrogen absorption; f is the reaction fraction. In particular, the reaction fraction f and the hydrogen atomic ratio (H / M) and the hydrogen mass ratio are not the same concept, but they can all reflect the degree of the process. The expressions of these three physical quantities are as follows:

[0194] Hydrogen atom ratio H / M: indicates the number of hydrogen atoms bound to each metal atom

[0195]

[0196] Among them, n H and n s represent the atomic numbers of hydrogen and hydrogen storage material, respectively;

[0197] Hydrogen metal ratio: indicates the percentage of hydrogen mass in the hydrogen storage material to the total mass

[0198]

[0199] Among them, ρ s is the density of the hydrogen storage material at time t; ρ m is the density of the initial hydrogen storage material;

[0200] Reaction fraction f: represents the percentage of the hydrogen atom ratio of the hydrogen storage material at time t to the maximum hydrogen atom ratio

[0201]

[0202] In the formula, (H / M)max is the hydrogen atomic ratio corresponding to the maximum hydrogen absorption amount.

[0203] The conversion relationship between the three physical quantities is as follows:

[0204]

[0205] Right now:

[0206]

[0207] Due to the change in the porosity of the hydrogen storage material, the thermal properties of the material itself will change (thermal conductivity, specific heat, density) and the permeability of hydrogen in the porous medium will change. The calculation formula is as follows:

[0208] λ e =ελ g +(1-ε)λ g

[0209] ρC p =ερ g C pg +(1-ε)ρ s C ps

[0210] Among them, λ g and λ s are the thermal conductivities of hydrogen and alloy, C pg and C psare the specific heat capacities of hydrogen and alloy respectively. The viscosity of hydrogen is a function of temperature and is expressed as

[0211]

[0212] As a porous medium, the permeability of hydrogen storage materials is related to porosity and particle size.

[0213]

[0214] T ref is the reference temperature; d p is the particle diameter.

[0215] Furthermore, the distributed ordinary differential equation of the hydrogen storage material is expressed by a mathematical equation, which also includes:

[0216] When analyzing the distributed ordinary differential equation of the hydrogen filling in the hydrogen storage material, the density of the hydrogen storage material is used as the dependent variable of the distributed ordinary differential equation, the source term of the equation is f, and the damping is d a , the quality coefficient is e a , the expression is

[0217]

[0218] Where f is the source term for the mass rate of hydrogen; d a Damping is 1-ε; quality coefficient e a is 0; to solve the ordinary differential equation, it is necessary to set the initial value of the dependent variable and the initial time derivative. Taking the hydrogen absorption process as an example, the initial value is ρ emp , that is, the density of the hydrogen storage material when there is no hydrogen;

[0219] Initial time derivative for:

[0220]

[0221] The outer surface of the hydrogen storage tank is exposed to natural convection under air, and the remaining surfaces are set to thermal insulation. Hydrogen flows in from the inlet at a constant pressure.

[0222] Among them, in this embodiment, the traditional simulation method may ignore or simplify the processing of density changes, resulting in the inability to accurately describe the complex phenomena in the hydrogen adsorption and release process. Distributed ordinary differential equations can provide more accurate density change simulations, improve the accuracy of predictions of hydrogen storage material performance, and allow real-time simulation of dynamic changes in the hydrogen storage process, providing more comprehensive material performance predictions.

[0223] Detailed description: It can provide a detailed description of the spatial distribution within the material, taking into account the local effects in different areas and providing a more comprehensive analysis result.

[0224] When there are spatial derivatives of dependent variables in the equation, according to the COMSOL simulation design principles, the "Partial Differential Equation Interface" is used; when there are no spatial derivatives of dependent variables in the equation, the ODE and DAE interface is used to add global equations that are independent of space and can represent additional states. Use the "ODE and DAE Module"

[0225] Distributed ODEs usually refer to the extension of ODEs to a distributed parameter system. This means that the equations depend not only on time, but may also depend on multiple dimensions such as space. Unlike ordinary ODEs, distributed ODEs are often used to describe dynamic systems with spatial or other distributed characteristics. For example, the heat conduction equation is a typical distributed ODE because it describes the process of how the distribution of heat in space changes over time.

[0226] Furthermore, a grid division strategy is adopted to grid the hydrogen storage tank model, data is extracted from the simulation results, and an optimization scheme for designing the hydrogen storage tank is analyzed and output, which also includes:

[0227] A first fine-grained grid is used in the hydrogen flow region to capture flow details;

[0228] Applying a second fine-grained grid on the hydrogen storage tank wall and key locations, wherein the second fine-grained grid has a smaller size than the first fine-grained grid;

[0229] Ensure that the quality of meshing meets the convergence requirements of the numerical solution;

[0230] Performing data extraction on the simulation results to obtain the flow velocity, pressure field and temperature field distribution of hydrogen, the temperature field distribution and density change of the hydrogen storage material, and the reaction rate;

[0231] Compare simulation data under different operating conditions and analyze performance changes during hydrogen adsorption and release;

[0232] Generate visual charts and reports to display the simulation results, and output an optimization plan for designing the hydrogen storage tank based on the analysis results.

[0233] Among them, in this embodiment, the grid type: select a finer grid type, such as Fig. 9 The time step is set to 1s, the total duration is 10000s, and the tolerance is controlled by the physical field.

[0234] Post-processing analysis: The post-processing function of COMSOL is used to generate visualization images of hydrogen flow field, temperature field, stress field, etc., to intuitively display the behavior of the hydrogen storage tank during the hydrogen absorption and desorption process, and to extract key data from the simulation results, including hydrogen absorption rate, temperature change, pressure field change, etc. Fig.10 , 11 、12.

[0235] Performance analysis: Conduct sensitivity analysis and trend analysis to evaluate the performance of hydrogen storage tanks, including hydrogen storage efficiency, thermal management effect, structural strength, etc.

[0236] like Fig.10 As shown, the obtained relationship between the hydrogen absorption amount of the hydrogen storage tank and time can provide a reference for the hydrogen storage tank experiment; by analyzing the influence of different factors on the hydrogen absorption and desorption rate of the hydrogen storage tank under different boundary conditions, the test cycle is short and is not affected by changes in external environmental factors.

[0237] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0238] In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of software functional units. The above is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of this application, or directly or indirectly used in other related technical fields, is also included in the patent protection scope of the present application.

[0239] The specific implementation methods of the invention are described in detail above, but they are only examples, and the present application is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the present application, and therefore, the equalization, modification, and improvement made without departing from the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. A simulation analysis method for hydrogen absorption and desorption of a hydrogen storage tank based on the JMAK model, characterized in that: include: Obtaining physical parameters of the hydrogen storage tank, and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model; Configuring the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank; Select a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material, and express the simulation result of the hydrogen storage material with a mathematical equation; A grid division strategy is adopted to grid the hydrogen storage tank model, data is extracted from the simulation results, and an optimization scheme for designing the hydrogen storage tank is analyzed and output.

2. The method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model according to claim 1, characterized in that: The method of obtaining the physical parameters of the hydrogen storage tank and using COMSOL software to create a two-dimensional axisymmetric hydrogen storage tank geometric model also includes: The physical parameters of the hydrogen storage tank include at least: Internal structure, shell structure, hydrogen flow area, hydrogen storage material area, size, shape and related interfaces.

3. The method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model according to claim 1, characterized in that: The configuring of the hydrogen storage material and the filling hydrogen of the geometric model of the hydrogen storage tank, and obtaining the physical properties of the filling hydrogen and the material properties of the hydrogen storage tank, further includes: Inputting the physical and chemical properties of the hydrogen storage material, including at least density, thermal conductivity, and specific heat capacity; Inputting the physical and chemical properties of the filling hydrogen, including at least density, viscosity, thermal conductivity, specific heat capacity, and average molar mass of hydrogen; Input material properties of the hydrogen storage tank, including at least specific heat capacity, thermal conductivity, porosity, hydrogen absorption enthalpy change, particle volume ratio, reaction fraction, and hydrogen atomic ratio.

4. The method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model according to claim 1, characterized in that: Selecting a physical field module to describe the physical process of filling hydrogen in the hydrogen storage material also includes: The filling hydrogen flows in from the top of the hydrogen storage tank at a constant pressure, and the bottom and outer surface of the hydrogen storage tank perform convection heat exchange; The hydrogen storage materials are all spherical particles evenly distributed in the hydrogen storage tank, and the filled hydrogen undergoes a hydrogen absorption / desorption reaction in the hydrogen storage material reaction bed, releasing heat and consuming hydrogen during the hydrogen absorption process, and absorbing heat and generating hydrogen during the hydrogen desorption process, thereby performing a local thermal balance process; The heat transfer process, mass transfer process, thermodynamic process, kinetic process and distributed ordinary differential equation of the filled hydrogen in the hydrogen storage material are analyzed.

5. The method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model according to claim 4 is characterized in that: The simulation results of the hydrogen storage material are expressed by mathematical equations, and also include: When analyzing the heat transfer process of the filled hydrogen in the hydrogen storage material, the heat transfer process includes two parts: heat conduction and convection. According to Fourier's law, the law of conservation of energy and the control equation under the non-steady-state process, the expression is as follows: Among them, ρ s C p is the product of the density and specific heat capacity of the hydrogen storage material; t is the time, in seconds; T is the temperature, in K; ρ g C pg is the product of the density and specific heat capacity of hydrogen; is the hydrogen flow rate in m / s; S is the source term of the equation, which is related to the hydrogen absorption / desorption dynamics. In the hydrogen absorption process, S is the internal heat source term, and the expression is: Among them, M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; M H2 is the average molar mass of hydrogen, which is 0.0020159 kg / mol; ε is the porosity of the hydrogen storage material, in %; ρ s is the density of hydrogen storage material, in kg / m 3 ; H / M is the hydrogen atomic ratio, unit is 1; t is the time, unit is s; H / M is the hydrogen atomic ratio; ΔH is the enthalpy change of hydrogen absorption / desorption, unit is J / (kg*K).

6. A method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on the JMAK model according to claim 5, characterized in that: The mass transfer process of the hydrogen storage material is expressed by mathematical equations, and also includes: When analyzing the mass transfer process of the filled hydrogen in the hydrogen storage material, the pressure-driven flow is defined by Darcy's law, and the expression is: in, is the flow rate of hydrogen in the porous medium, in m / s; K is the permeability of the powder bed, and assuming that the porous medium is isotropic, the K value is 1e -8 m 2 ;μ g is the dynamic viscosity of hydrogen, in kg / (m*s); is the pressure gradient, in pa, where the velocity field u depends on the permeability and the dynamic viscosity μ of the fluid has a pressure gradient drive; Substituting into the continuity equation: Among them, ρ g is the density of hydrogen, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; u is the flow rate of hydrogen in the porous medium, in m / s; Q m is the source term of the continuity equation, is the consumption of hydrogen in the hydrogen storage material during the hydrogen absorption process or the generation of hydrogen in the hydrogen storage material during the hydrogen release process, and its expression is: Among them, ρ s is the density of hydrogen storage material, in kg / m 3 ; ε is the porosity of the porous medium, i.e. the hydrogen storage material, in %; M H is the average molar mass of hydrogen, which is 0.0010079 kg / mol; M s is the average molar mass of hydrogen storage material, in kg / mol; H / M is the hydrogen atomic ratio, in 1; t is the time, in s.

7. A method for simulating the absorption and desorption of hydrogen in a hydrogen storage tank based on the JMAK model according to claim 6, characterized in that: The thermodynamic process of the hydrogen storage material is expressed by mathematical equations, and also includes: When analyzing the thermodynamic process of the hydrogen filling in the hydrogen storage material, the following relationship is obtained through the relationship between Gibbs free energy and other thermodynamic parameters: ΔG = ΔH - TΔS; ΔG is Gibbs free energy, P H2 is the equilibrium hydrogen pressure; K p is the equilibrium constant, which indicates the partial pressure of each component under equilibrium conditions; In the thermodynamic analysis of chemical reactions, K p It is an important parameter for describing the equilibrium state of gaseous reactants and products, and Gibbs free energy provides a thermodynamic basis for determining whether a reaction is spontaneous. Among them, ΔH is the enthalpy change of hydrogen absorption and desorption; ΔS is the entropy variable; R is the gas constant. The above formula can be used to calculate Inp H2 The relationship between 1 / T is called the Hovantoff curve. During the simulation, the equilibrium pressure of the hydrogen storage material is a function of the hydrogen atomic ratio and temperature, and the formula is: Wherein, f(H / M) is the polynomial fitting equation of the PCT curve at the reference temperature, representing the relationship between the equilibrium pressure and H / M at the reference temperature; T ref is the reference temperature, T is the temperature of the hydrogen storage material, in K; For hydrogen storage materials, f(H / M) at the reference temperature is a 9th-order polynomial, with the formula: Among them, a i is the fitting coefficient, and its unit is 1.

8. The method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on the JMAK model according to claim 7 is characterized in that: The kinetic process of the hydrogen storage material is expressed by mathematical equations, and also includes: When analyzing the kinetic process of the hydrogen filling in the hydrogen storage material, the JMAK model is used; The expression of the JMAK model is as follows: [-ln(1-α)] 1 / n =kt; After taking the logarithm of both sides, we can get the following result: ln[-ln(1-α)]=nlnk+nlnt; Wherein, k is the rate constant of hydrogenation or dehydrogenation reaction; α is the reaction fraction converted to hydride hydrogen storage material corresponding to time t; n is the dimension that determines the abstract model; the linear relationship between ln[-ln(1-α)] and lnt is established by the above formula; the value of n is obtained from the slope, and the value of the reaction rate constant k is calculated in combination with the intercept value; In the process of hydrogenation or dehydrogenation, hydrogen storage materials must overcome energy barriers to undergo hydrogen absorption / desorption reactions. The energy barrier is the activation energy, expressed as E a It is expressed that the Arrhenius equation is used to obtain: R is the gas constant; T is the reaction temperature; Taking the logarithm of both sides of the above formula gives: B is the parameter obtained after taking the logarithm, which is represented as the intercept on the linear fitting result graph; It can be seen that lnk is linearly related to 1 / T, and its slope is -E a / R, and then calculate the absorption / desorption rate constant k at different temperatures, and then draw the relationship curve between lnk and 1 / T, and obtain the activation energy E by linear fitting the curve. a , and then explain the intrinsic mechanism of the change in hydrogen absorption / desorption kinetics from the perspective of activation energy.

9. The method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on the JMAK model according to claim 7, characterized in that: The distributed ordinary differential equation of the hydrogen storage material is expressed by a mathematical equation, and also includes: When analyzing the distributed ordinary differential equation of the hydrogen filling in the hydrogen storage material, the density of the hydrogen storage material is used as the dependent variable of the distributed ordinary differential equation, the source term of the equation is f, and the damping is d a , the quality coefficient is e a , the expression is Where f is the source term for the mass rate of hydrogen; d a Damping is 1-ε; quality coefficient e a is 0; to solve the ordinary differential equation, it is necessary to set the initial value of the dependent variable and the initial time derivative. Taking the hydrogen absorption process as an example, the initial value is ρ emp , that is, the density of the hydrogen storage material when there is no hydrogen; Initial time derivative for: The outer surface of the hydrogen storage tank is exposed to natural convection under air, and the remaining surfaces are set to thermal insulation. Hydrogen flows in from the inlet at a constant pressure.

10. The method for simulating and analyzing hydrogen absorption and desorption of a hydrogen storage tank based on the JMAK model according to claim 7, characterized in that: The method further comprises: adopting a meshing strategy to mesh the hydrogen storage tank model, extracting data from the simulation results, analyzing and outputting an optimization scheme for designing the hydrogen storage tank, and further comprising: A first fine-grained grid is used in the hydrogen flow region to capture flow details; Applying a second fine-grained grid on the hydrogen storage tank wall and key locations, wherein the second fine-grained grid has a smaller size than the first fine-grained grid; Ensure that the quality of meshing meets the convergence requirements of the numerical solution; Performing data extraction on the simulation results to obtain the flow velocity, pressure field and temperature field distribution of hydrogen, the temperature field distribution and density change of the hydrogen storage material, and the reaction rate; Compare simulation data under different operating conditions and analyze performance changes during hydrogen adsorption and release; Generate visual charts and reports to display the simulation results, and output an optimization plan for designing the hydrogen storage tank based on the analysis results.

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