Marine fuel cell-oriented methanol reforming process modeling method and device

Abstract

The invention discloses a ship fuel cell-oriented methanol reforming process modeling method, which comprises the following steps of: 1, determining exhaust heat and temperature in an operation load range, and calculating fuel supply quantity and stoichiometric ratio according to a methanol reforming process mechanism; 2, determining a reaction kinetic model, determining a reactor structure and key model parameters, and establishing a methanol reforming process steady-state model; 3, analyzing parameters of the methanol reforming process of the SOFC under different operation load conditions, and determining a basic structure and input parameters of the methanol reforming reaction process; and 4, establishing a methanol reforming process dynamic mechanism model, determining a model interface in each physical field, and carrying out SOFC variable load methanol reforming process dynamic characteristic analysis. The invention further discloses a methanol reforming process modeling device for the ship fuel cell. The method solves the problem of poor coupling modeling matching performance of the current methanol reforming and ship platform SOFC system, and can be widely applied to the technical field of diesel-electric-fuel hybrid power.

Description

Technical Field

[0001] This invention relates to the field of diesel-electric-gasoline hybrid power technology, and in particular to a method and apparatus for modeling the methanol reforming process for marine fuel cells. Background Technology

[0002] Methanol, as a liquid fuel, possesses high energy density. Compared to gaseous fuels such as hydrogen, methane, and ammonia, it exhibits significant advantages in storage, transportation, and safety. Through steam reforming, methanol can be efficiently converted into hydrogen at relatively low temperatures of 150-300℃. This operating temperature is significantly lower than the reforming temperatures required for the aforementioned gaseous fuels (CH4, NH3), allowing for deep integration with solid oxide fuel cells (SOFCs). Furthermore, methanol has a wide range of feedstock sources, not only produced from traditional fossil fuels but also through green production using emerging technologies such as electro-methanol conversion. Therefore, methanol fuel is considered an effective solution for SOFC applications on marine platforms.

[0003] The coupling of methanol reforming with SOFC systems on ship platforms involves multiple fields such as thermodynamics, chemistry, and fluid mechanics. System design and modeling are complex, and current research on the steady-state or dynamic processes of methanol reforming lacks a complete description. Steady-state modeling focuses only on the inlet and outlet states and energy balance of the reforming process, leading to mathematical models that easily simplify process characteristics. Dynamic modeling, on the other hand, only considers internal constraints and equilibrium relationships, neglecting structural and parameter optimization of the reforming process. This results in poor compatibility with SOFCs in practical applications and an inability to accurately describe the coupling relationships and dynamic characteristics within the system. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a methanol reforming process modeling method and apparatus for ship fuel cells, which can effectively meet the fuel supply requirements of ship platform SOFC during variable load processes, while accurately reflecting the coupling relationship and dynamic characteristics within the methanol reforming process system. This helps to predict the dynamic changes of the system under different load conditions of ship platform SOFC, and solves the problem of poor matching between current methanol reforming and ship platform SOFC system coupling modeling.

[0005] This invention provides a modeling method for methanol reforming processes in marine fuel cells, comprising the following steps: S1, determining the exhaust heat and temperature within the operating load range of the solid oxide fuel cell (SOFC), and calculating the fuel supply and stoichiometry based on the methanol reforming mechanism; S2, determining the reaction kinetics model based on the methanol reforming mechanism model, designing the reactor structure, determining key model parameters, and establishing a steady-state model of the methanol reforming process; S3, analyzing the parameters of the methanol reforming process under different operating load conditions in the SOFC, and determining the basic structure and input parameters of the methanol reforming reaction process based on the steady-state operating results; S4, establishing a dynamic mechanism model of the methanol reforming process based on the basic structure and input parameters of the steady-state process, determining the model interfaces in various physical domains, optimizing the model structure and parameters, and conducting dynamic characteristic analysis of the SOFC variable-load methanol reforming process.

[0006] In the above technical solution, in step S1, the fuel supply quantity and stoichiometric ratio represent the flow rate and mixing molar ratio of methanol and water.

[0007] In the above technical solution, the specific process of calculating the fuel supply and stoichiometric ratio based on the methanol reforming process mechanism in step S1 is as follows: The methanol reforming reaction mechanism is as follows: Steam reforming reaction: (1) Methanol decomposition reaction: (2) Water vapor conversion reaction: (3) Among them, k i This represents the reaction rate constant for each reaction; that is, the reaction rate constant for each of the three reactions is calculated based on the three chemical reaction steps of the methanol reforming reaction.

[0008] In the above technical solution, in step S2, the reaction kinetic model is based on the reaction mechanism model to calculate the chemical reaction rate; the key model parameters include reactor structural parameters and various physical parameters required for the methanol reforming reaction.

[0009] In the above technical solution, the specific process of step S2 is as follows: S21, Calculate the chemical reaction rate based on the reaction mechanism model, including the following process: The chemical reaction rate is obtained through the following methods: (4) (5) (6) Among them, r i The reaction rates of each reaction are represented separately. C i This indicates the volume concentration of each component. k iThe rate constants for each reaction are represented by the Arrhenius equation: (7) Among them, A i Pre-exponential factors; R The gas constant is T For temperature; E ai As activation energy, due to k -3 If the value is too small, the SR reaction can be considered an irreversible reaction; S22, determine the reactor structural parameters and various physical parameters required for the methanol reforming reaction, and establish a steady-state model of the methanol reforming process, including the following processes: the reactor structure is a tubular packed reactor, the internal packing is a porous catalyst, and the reactor structural parameters include setting the reactor diameter and reactor length to be adapted to the reaction; the catalyst is a metal oxide catalyst, the catalyst structure is a porous structure, and the reactor bed porosity and catalyst density are designed to be adapted to the reaction.

[0010] In the above technical solution, the input parameters in step S3 include the flow rates of methanol and water, the molar ratio of methanol to water, and the temperature and heat during the methanol reforming process.

[0011] In the above technical solution, the specific process of step S3 is as follows: In the methanol reforming process, the methanol reaction rate and the molar ratio of the products increase with increasing reaction temperature. That is, the methanol conversion rate, as well as the production of hydrogen, carbon dioxide, and carbon monoxide, all increase with increasing reaction temperature. The methanol conversion rate reaches 100% at the first temperature threshold, and the hydrogen molar ratio is at its highest at 67.77%. However, when the reaction temperature exceeds the second temperature threshold, further increasing the temperature reduces the increase in methanol conversion rate and hydrogen yield. Continuing to increase the reaction temperature further reduces the yield gain, and the methanol conversion rate of the reactants... and product molar ratio The calculation is as follows: (8) (9) Among them, n i,in , n i,out These are the molar flow rates of each component at the reactor inlet and outlet, respectively. n total,out This represents the total molar flow rate at the outlet.

[0012] In the above technical solution, the specific process of step S4 is as follows: Based on the physical structure and process of methanol reforming, a dynamic system model is established. According to the physical topology of the reactor, the process is divided into three parts: diffusion, reaction and heat transfer. Model interfaces for the above three processes are established respectively. After defining the model interfaces and encapsulating the model, a dynamic model is established.

[0013] In the above technical solution, in step S4, the model interface is defined as follows: the total mass within the reactor volume can be expressed as: (10) Among them, ρ For the density of the reactants, V The volume of the reactants t For time, j The inlet and outlet nodes of each process are represented. The momentum balance equation, based on a quasi-steady-state model, is used to calculate the pressure drop inside the pipe; the Ergun equation is used to calculate the friction coefficient. (11) Among them, ε is the total gas pressure, ε is the packing porosity, and u is the gas velocity. To represent apparent air velocity, The diameter of the catalyst particles is [missing information]. The viscosity of the reacting gas; the energy balance of the methanol reforming reaction can be expressed as: (12) Among them, m For quality, h For enthalpy, W This is the work done by the gas expansion. Q To absorb heat during the reaction process, U For the internal energy of the system, P The gas pressure inside the reactor. V The volume of the reacting gas. t For time, j Indicates the inlet and outlet nodes of each process; the methanol reforming reaction is an endothermic reaction, and the heat required for the reaction comes from the waste heat of SOFC exhaust. The dynamic gas heat transfer between the methanol vapor phase and the catalyst phase can be expressed as: Gas phase: (13) Catalyst phase: (14) Among them, T g and T c These are the temperatures of the gas phase and the catalyst phase, respectively. D tube The diameter of the tubular reactor, A tube This refers to the heat exchange area on the tube wall side of the tubular reactor. T w The temperature of the reactor tube wall. a v The specific surface area of ​​the catalyst. r k Let k be the reaction rate. and These are the specific heat capacities of the gas phase and the catalyst phase, respectively. and These are the densities of the gas phase and the catalyst phase, respectively. The thermal conductivity of the catalyst phase, The heat transfer coefficient between the gas phase and the pipe wall. The heat transfer coefficient between the gas phase and the catalyst phase. For the reaction The heat of reaction; the gas heat transfer on the waste heat side of SOFC exhaust can be expressed as: (15) Among them, u The gas velocity is given; the diffusion flow rates of each component in the gas mixture are calculated using Fick's law. (16) Among them, J diff For the diffusion flux of different components, D eff Indicates the effective diffusion coefficient of the reactants. C Let be the volume concentration of each component in the diffusing material; the transport of reactants on the reactor catalyst surface and in the SOFC porous medium can be described by combining Knudsen diffusion and binary diffusion, and the effective diffusion coefficient can be expressed as: (17) Among them, D A eff For the effective diffusion coefficient, and Let A and B be the binary diffusion coefficients of components A and B respectively, and Knudsen's diffusion coefficient of component A. D AB and D AK The free molecular diffusion coefficients of components AB and component A, respectively. Porosity represents the porosity of porous media. τ Indicates curvature; the binary diffusion coefficient can be expressed as: (18) Among them, v i Indicates the molar diffusion volume of each component. P Indicates the pressure of the reaction system. M A and M B Let A and B be the molar masses of components A and B, respectively; the Knudsen diffusion coefficient can be expressed as: (19) Among them, r This indicates the pore size of the porous medium. R The gas constant is 8.314 J / (mol·K). T For temperature, D AK Let Knudsen be the diffusion coefficient of component A; the permeability of the porous medium can be calculated using the Kozeny-Carman correlation: (20) Among them, k p For porous media permeability, h k It is the Kozeny-Carman constant. A g Specific surface area of ​​porous media particles m -1 ; (21) Among them, m For quality flow, ρ For density, A The cross-sectional area of ​​the flow path. μ For fluid dynamic viscosity, L The length of the tubular reactor, ΔP The pressure difference across the reactor; the energy balance of the methanol steam reforming reaction can be expressed as: (22) Among them, V j for j The volume of the process node. T Represents temperature. J i Indicates the diffusion flow rate of each component in the gas mixture. i Indicates different components, H g Indicates the enthalpy value of the mixed gas. h i For the specific enthalpy of each component, Indicates the effective thermal conductivity of a porous medium; (23) Among them, Let be the thermal conductivity of the gas mixture. It is the thermal conductivity of porous media; (24) Among them, Q R，MSR This represents the heat of reaction during the entire methanol reforming process. ΔH SR This indicates the enthalpy change during the steam reforming reaction. ΔH MD This indicates the enthalpy change during the methanol decomposition reaction. ΔH WGS This indicates the enthalpy change during the water vapor conversion reaction process. r SR This indicates the reaction rate of the steam reforming reaction. r MD This indicates the reaction rate of the methanol decomposition reaction. r WGS This indicates the reaction rate of the water-vapor conversion reaction.

[0014] The present invention also provides a methanol reforming process modeling apparatus for marine fuel cells, which has a computer program that can execute a methanol reforming process modeling method for marine fuel cells.

[0015] The present invention provides a method and apparatus for modeling the methanol reforming process in marine fuel cells, which has the following advantages: This invention provides a method and apparatus for modeling the methanol reforming process in marine fuel cells. Based on the SOFC operating load and waste heat, the fuel demand for the reforming process is determined. A steady-state model of the reactor is established based on the methanol reforming reaction mechanism, defining the basic structure and input parameters of the methanol reforming reaction process. Based on these parameters, a dynamic mechanism model of the methanol reforming process is established. This method can meet the fuel demand of solid oxide fuel cells on marine platforms under varying loads, accurately reflect the dynamic characteristics of the methanol reforming process, and effectively improve modeling efficiency and simulation reliability. It also promotes the progress of engineering design and optimization, and helps predict the dynamic changes of the methanol reforming process under different load conditions in marine platform SOFCs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall process of Embodiments 1-2 of the methanol reforming process modeling method for marine fuel cells of the present invention; Figure 2 This is a schematic diagram of the tubular methanol steam reforming reactor structure in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 3 This is a schematic diagram showing the changes in the methanol reaction rate and product molar ratio as a function of reaction temperature in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 4 This is a schematic diagram showing the changes in the methanol reaction rate and product molar ratio along the methanol reforming process from the inlet to the outlet in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 5 This is a schematic diagram of the dynamic modeling of a tubular methanol steam reforming reactor in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 6 This is a schematic diagram illustrating the dynamic response of the molar flow rates of methanol and water vapor at the inlet and outlet of the methanol reforming process as a function of the step change in the inlet molar flow rate in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 7 This is a schematic diagram illustrating the dynamic response of the molar flow rates of hydrogen, carbon monoxide, and carbon dioxide products in the methanol reforming process as a function of the step change in inlet molar flow rate in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 8 This is a schematic diagram illustrating the dynamic response of the temperature of the reactor outlet product in the methanol reforming process as a function of the inlet molar flow rate step change in Example 2 of the methanol reforming process modeling method for marine fuel cells of the present invention. Figure 9 This is a schematic diagram of the architecture of the methanol reforming process modeling device for marine fuel cells according to the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0018] Example 1 See Figure 1 The present invention provides a modeling method for methanol reforming processes in marine fuel cells, comprising the following steps: S1. Determine the exhaust heat and temperature within the operating load range of the solid oxide fuel cell, and calculate the fuel supply and stoichiometry based on the methanol reforming process mechanism; S2. Based on the mechanism model of methanol reforming, determine the reaction kinetic model, design the reactor structure, determine the key model parameters, and establish a steady-state model of methanol reforming. S3. Conduct parameter analysis of methanol reforming process under different SOFC operating loads, and determine the basic structure and input parameters of methanol reforming reaction process based on steady-state operation results; S4. Based on the basic structure and input parameters of the steady-state process, establish a dynamic mechanism model of the methanol reforming process, determine the model interface under each physical domain, optimize the model structure and parameters, and conduct dynamic characteristic analysis of the SOFC variable load methanol reforming process. The exhaust gas is the gas emitted after SOFC waste heat utilization; The fuel supply quantity and stoichiometric ratio represent the flow rate and mixing molar ratio of methanol and water; The reaction kinetics model is based on the reaction mechanism model and calculates the chemical reaction rate; The key model parameters include reactor structural parameters, reaction model parameters, etc. The input parameters include the flow rates of methanol and water, the mixing molar ratio, and the temperature and heat of the reforming process.

[0019] Example 2 This embodiment is basically the same as Embodiment 1, except that: See Figure 1 This embodiment provides a modeling method for a SOFC methanol reforming reactor with a rated power of 50kW, where the SOFC operating range is 25-65kW.

[0020] S1. The mechanism of the methanol reforming reaction process is as follows: Steam reforming reaction (SR): (1) Methanol decomposition reaction (MD): (2) Water vapor reforming reaction (WGS): (3) In the formula, k i This represents the reaction rate constant for each reaction.

[0021] S2, The chemical reaction rate is as follows: (4) (5) (6) in, r i The reaction rates of each reaction are represented separately. C i This indicates the volume concentration (mol / m3) of each component. k i The rate constants for each reaction are represented by the Arrhenius equation: (7) In the formula: A i Pre-exponential factors; R This is the gas constant, with a value of 8.314 J / (mol·K); T For temperature; E ai The activation energy is given. The model parameters are shown in Table 1. Since... k -3 If the value is too small, the SR reaction can be considered an irreversible reaction.

[0022] Table 1. Parameters of the Methanol Steam Reforming Model

[0023] The reactor structure is a tubular packed reactor, as shown in the attached figure. Figure 2 As shown, the internal packing material is a porous catalyst. The reactor structural parameters are set with a diameter of 0.025 m and a length of 6 m.

[0024] The catalyst used is a CuO / ZnO / Al₂O₃ metal oxide catalyst, which exhibits good thermal stability and catalytic activity. The catalyst has a porous structure to ensure that methanol molecules can effectively contact the catalyst and react. (See attached image.) Figure 2 The reactor shown uses CuO / ZnO / Al2O3 as the catalyst material, which exhibits good catalytic efficiency in common methanol reforming processes. The reactor bed porosity is 0.5, and the catalyst density is 1480 kg / m³. 3 .

[0025] S3, Appendix Figure 3 This study examines the changes in methanol conversion rate and product molar ratio in the methanol reforming process with increasing reaction temperature, assuming a water-to-methanol ratio of 1.3:1. Methanol conversion rate, as well as the production of hydrogen, carbon dioxide, and carbon monoxide, all increase with increasing reaction temperature. The methanol conversion rate reaches 100% at 325℃, while the hydrogen molar ratio is highest at 67.77%. However, above 295℃, further increases in temperature reduce the improvement in methanol conversion rate and hydrogen yield. Continuing to increase the reaction temperature further decreases the yield gain. (Methanol conversion rate of reactants) and product molar ratio The calculations are as follows: (8) (9) In the formula, n i,in , n i,out These are the molar flow rates of each component at the reactor inlet and outlet, respectively. n total,out This represents the total molar flow rate at the outlet.

[0026] Appendix Figure 4 The reaction temperature of the methanol reforming reactor is 300℃. The reaction rate of methanol and the molar ratio of products along the reactor inlet to outlet are shown. The methanol conversion rate and the molar ratios of hydrogen, carbon dioxide and carbon monoxide all increase along the reactor. However, the molar ratios of products such as carbon dioxide and carbon monoxide increase slowly after 3m. The molar ratio of hydrogen is the highest at the outlet, which is 60%. The methanol conversion rate is 77%.

[0027] S4. The mechanism model includes physical process mechanism and chemical process mechanism. The physical process mechanism includes mass balance and energy balance, and the chemical process mechanism is the above-mentioned chemical reaction mechanism.

[0028] The physical process mechanism model is as follows: Based on the physical structure and process of methanol reforming, a dynamic system model is established. According to the physical topology of the reactor, the process is divided into three parts: diffusion, reaction, and heat transfer. These three processes are established separately. After defining model interfaces and encapsulating the models, the software's built-in models are combined with user-defined model packages to create a dynamic model. (Appendix) Figure 5 This is a schematic diagram of dynamic modeling. The diffusion and heat transfer models in the diagram are built-in models in the software. The reaction model is established based on the reaction kinetic mechanism model and the equations are calculated using a signal library.

[0029] The total mass within the reactor volume can be expressed as: (10) In the formula, ρ For the density of the reactants, V The volume of the reactants t For time, j The inlet and outlet nodes of each process are represented. The momentum balance equation, based on a quasi-steady-state model, is used to calculate the pressure drop within the pipe. Considering the dynamic momentum balance, even neglecting gravity effects, kinetic energy, and viscosity deviations, will lead to numerical stiffness. The Ergun equation is used to calculate the friction coefficient.

[0030] (11) in ε is the total gas pressure, ε is the packing porosity, and u is the gas velocity. For apparent air velocity ( ), The diameter of the catalyst particles is [missing information]. The viscosity is the viscosity of the reacting gas.

[0031] The energy balance of the methanol reforming reaction can be expressed as: (12) In the formula, m For quality, h For enthalpy, W This is the work done by the gas expansion. Q To absorb heat during the reaction process, U For the internal energy of the system, P The gas pressure inside the reactor. V The volume of the reacting gas. t For time, j This indicates the entry and exit points for each process.

[0032] The methanol reforming reaction is an endothermic reaction, and the heat required for the reaction comes from the waste heat of SOFC exhaust gas. The dynamic gas heat transfer between the methanol vapor phase and the catalyst phase can be expressed as: Gas phase: (13) Catalyst phase: (14) in, T g and T c These are the temperatures of the gas phase and the catalyst phase, respectively. D tube The diameter of the tubular reactor, A tube This refers to the heat exchange area on the tube wall side of the tubular reactor. T w The temperature of the reactor tube wall. a v The specific surface area of ​​the catalyst. r k Let k be the reaction rate. and These are the specific heat capacities of the gas phase and the catalyst phase, respectively. and These are the densities of the gas phase and the catalyst phase, respectively. The thermal conductivity of the catalyst phase, The heat transfer coefficient between the gas phase and the pipe wall. is the heat transfer coefficient between the gas phase and the catalyst phase. For the reaction The heat of reaction.

[0033] The gas heat transfer on the waste heat side of SOFC exhaust can be expressed as: where u is the gas flow velocity: (15) The diffusion flow rates of each component in the gas mixture can be calculated using Fick's law: (16) In the formula, J diff For the diffusion flux of different components, D eff Indicates the effective diffusion coefficient of the reactants. C This represents the volume concentration of the diffusing substances (each component); The transport of reactants on the reactor catalyst surface and in the porous medium of SOFC can be described by combining Knudsen diffusion and binary diffusion, and the effective diffusion coefficient can be expressed as: (17) in, D A eff For the effective diffusion coefficient, and Let A and B be the binary diffusion coefficients of components A and B respectively, and Knudsen's diffusion coefficient of component A. D AB and D AK The free molecular diffusion coefficients of components AB and component A, respectively. Porosity represents the porosity of porous media. τ Indicates the degree of curvature.

[0034] The binary diffusion coefficient can be expressed as: (18) in, v i Indicates the molar diffusion volume of each component. P Indicates the pressure of the reaction system. M A and M B These are the molar masses of components A and B, respectively. The Knudsen diffusion coefficient can be expressed as: (19) in, r This indicates the pore size of the porous medium. R This is the gas constant, with a value of 8.314 J / (mol·K); T For temperature, D AK Let Knudsen be the diffusion coefficient of component A.

[0035] The permeability of porous media can be calculated using the Kozeny-Carman correlation: (20) In the formula, k p For porous media permeability, h k It is the Kozeny-Carman constant. A g Specific surface area of ​​porous media particles m -1 The mass flow rate can be calculated using the Darcy formula (Darcy-Weisbach formula).

[0036] (twenty one) In the formula, m For quality flow, ρ For density, A The cross-sectional area of ​​the flow path. μ For fluid dynamic viscosity, L The length of the tubular reactor, ΔP The pressure difference across the reactor and the molar diffusion volumes of each component are shown in Table 2.

[0037] Table 2 Molar diffusion volumes of each component

[0038] The energy balance of the methanol steam reforming reaction can be expressed as: (twenty two) in, V j for j The volume of the process node. T Represents temperature. J i Indicates the diffusion flow rate of each component in the gas mixture. i Indicates different components, H g Indicates the enthalpy value of the mixed gas. h i For the specific enthalpy of each component, This represents the effective thermal conductivity of a porous medium.

[0039] (twenty three) Mode, Let be the thermal conductivity of the gas mixture. It is the thermal conductivity of porous media. Q R The heat source represents the heat of methanol reforming reaction.

[0040] (twenty four) in, Q R，MSR This represents the heat of reaction during the entire methanol reforming process. ΔH SR This indicates the enthalpy change during the steam reforming reaction. ΔH MD This indicates the enthalpy change during the methanol decomposition reaction. ΔH WGS This indicates the enthalpy change during the water vapor conversion reaction process. r SR This indicates the reaction rate of the steam reforming reaction. r MD This indicates the reaction rate of the methanol decomposition reaction. r WGS This indicates the reaction rate of the water-vapor conversion reaction.

[0041] According to the appendix Figure 2Based on the reactor structure and steady-state results, the above models were integrated into a methanol reforming reactor model using a modular integration method. The performance of the methanol reforming process under SOFC variable load conditions was analyzed to provide data support for optimization decisions.

[0042] Appendix Figure 6 The changes in the molar flow rates of methanol and water vapor at the reactor inlet and outlet during a flow step in the methanol reforming process are shown. The changes in the molar flow rates of methanol and water at the outlet lag behind those at the inlet by 5-10 seconds.

[0043] Appendix Figure 7 This paper presents the dynamic response of the molar flow rates of hydrogen, carbon monoxide, and carbon dioxide products in the methanol reforming process to step changes in the inlet molar flow rate. The product yield increases with increasing reactant flow rate. However, there is overshoot during the step increase and decrease of hydrogen flow rate, and the dynamic response time of the hydrogen molar flow rate is 10 s.

[0044] Appendix Figure 8 This describes the dynamic response of the reactor outlet product temperature to changes in reactant flow rate during a methanol reforming process. The product temperature decreases with increasing reactant flow rate and increases with decreasing flow rate. The dynamic response time for the product outlet temperature is 25 s.

[0045] Example 3 See Figure 9 This invention relates to a methanol reforming process modeling device for marine fuel cells, comprising the following components: Mechanism calculation module: Determines the exhaust heat and temperature within the operating load range of the solid oxide fuel cell, and calculates the fuel supply and stoichiometry based on the methanol reforming process mechanism; Steady-state model building module: Based on the mechanism model of methanol reforming process, determine the reaction kinetic model, design the reactor structure, determine the key model parameters, and establish a steady-state model of methanol reforming process; Basic Structure and Input Parameters Module: Analyzes the parameters of the methanol reforming process in SOFC under different operating load conditions, and determines the basic structure and input parameters of the methanol reforming reaction process based on steady-state operation results; Dynamic Mechanism Model Module: Based on the basic structure and input parameters of the steady-state process, a dynamic mechanism model of the methanol reforming process is established, the model interface under each physical domain is determined, the model structure and parameters are optimized, and dynamic characteristic analysis of the SOFC variable load methanol reforming process is carried out.

[0046] The main technical points are as follows: (1) The present invention can determine the fuel demand of the reforming process based on the SOFC operating load and waste heat, establish a steady-state model of the reactor based on the reaction mechanism of the methanol reforming process, determine the basic structure and input parameters of the methanol reforming reaction process, and establish a dynamic mechanism model of the methanol reforming process based on the above parameters. (2) Combining the fuel demand of the solid oxide fuel cell on the ship platform under varying loads, it can accurately reflect the dynamic characteristics of the methanol reforming process, and can effectively improve the modeling efficiency and simulation reliability, promote the progress of engineering design and optimization, and help predict the dynamic changes of the methanol reforming process under different load conditions of SOFC on the ship platform.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0048] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A modeling method for methanol reforming processes in marine fuel cells, characterized in that: Includes the following steps: S1. Determine the exhaust heat and temperature within the operating load range of the solid oxide fuel cell, and calculate the fuel supply and stoichiometry based on the methanol reforming process mechanism; S2. Based on the mechanism model of methanol reforming, determine the reaction kinetic model, design the reactor structure, determine the key model parameters, and establish a steady-state model of methanol reforming. S3. Analyze the parameters of the methanol reforming process in SOFC under different operating load conditions, and determine the basic structure and input parameters of the methanol reforming reaction process based on the steady-state operation results. S4. Based on the basic structure and input parameters of the steady-state process, establish a dynamic mechanism model of the methanol reforming process, determine the model interface under each physical domain, optimize the model structure and parameters, and conduct dynamic characteristic analysis of the SOFC variable load methanol reforming process.

2. The methanol reforming process modeling method for marine fuel cells according to claim 1, characterized in that: In step S1, the fuel supply quantity and stoichiometric ratio represent the flow rate and mixing molar ratio of methanol and water.

3. The methanol reforming process modeling method for marine fuel cells according to claim 2, characterized in that: In step S1, the specific process of calculating the fuel supply and stoichiometric ratio based on the methanol reforming mechanism is as follows: The mechanism of the methanol reforming reaction process is as follows: Steam reforming reaction: （1） Methanol decomposition reaction: （2） Water vapor conversion reaction: （3） in, k i This represents the reaction rate constant for each reaction; That is, calculate the rate constants of the three reactions based on the three chemical reaction steps of the methanol reforming reaction.

4. The methanol reforming process modeling method for marine fuel cells according to claim 3, characterized in that: In step S2, the reaction kinetic model is based on the reaction mechanism model to calculate the chemical reaction rate; the key model parameters include reactor structural parameters and various physical parameters required for the methanol reforming reaction.

5. The methanol reforming process modeling method for marine fuel cells according to claim 4, characterized in that: The specific process of step S2 is as follows: S21. Calculate the chemical reaction rate based on the reaction mechanism model, including the following process: The chemical reaction rate is obtained through the following methods: （4） （5） （6） in, r i The reaction rates of each reaction are represented separately. C i This indicates the volume concentration of each component. k i The rate constants for each reaction are represented by the Arrhenius equation: （7） in, A i Pre-exponential factors; R The gas constant is... T For temperature; E ai As activation energy, due to k -3 If the value is too small, the SR reaction can be considered an irreversible reaction; S22. Determine the reactor structural parameters and various physical parameters required for the methanol reforming reaction, and establish a steady-state model of the methanol reforming process, including the following steps: The reactor structure is a tubular packed reactor, with porous catalyst as the internal packing. The reactor structural parameters include the reactor diameter and reactor length, which are adapted to the reaction. The catalyst used is a metal oxide catalyst with a porous structure, and the reactor bed porosity and catalyst density are designed to be compatible with the reaction.

6. The methanol reforming process modeling method for marine fuel cells according to claim 5, characterized in that: In step S3, the input parameters include the flow rates of methanol and water, the molar ratio of methanol to water, and the temperature and heat during the methanol reforming process.

7. The methanol reforming process modeling method for marine fuel cells according to claim 6, characterized in that: The specific process of step S3 is as follows: In the methanol reforming process, the methanol conversion rate and the molar ratio of products increase with increasing reaction temperature. This means that the methanol conversion rate, as well as the production of hydrogen, carbon dioxide, and carbon monoxide, all increase with increasing reaction temperature. The methanol conversion rate reaches 100% at the first temperature threshold, and the highest hydrogen molar ratio is 67.77%. However, when the reaction temperature exceeds the second temperature threshold, further increases in temperature reduce the improvement in methanol conversion rate and hydrogen yield. Continuing to increase the reaction temperature further decreases the yield gain. and product molar ratio The calculation is as follows: （8） （9） in, n i,in , n i,out These are the molar flow rates of each component at the reactor inlet and outlet, respectively. n total,out This represents the total molar flow rate at the outlet.

8. The methanol reforming process modeling method for marine fuel cells according to claim 7, characterized in that: The specific process of step S4 is as follows: Based on the physical structure and process of methanol reforming, a dynamic system model is established. According to the physical topology of the reactor, the process is divided into three parts: diffusion, reaction and heat transfer. Model interfaces for the above three processes are established respectively. After defining the model interfaces and encapsulating the model, a dynamic model is established.

9. The methanol reforming process modeling method for marine fuel cells according to claim 8, characterized in that: In step S4, the model interface is defined as follows: The total mass within the reactor volume can be expressed as: （10） in, ρ For the density of the reactants, V The volume of the reactants t For time, j The inlet and outlet nodes of each process are represented, and the momentum balance equation is used to calculate the pressure drop inside the pipe based on the quasi-steady-state model. The friction coefficient was calculated using the Ergun equation: （11） in, ε is the total gas pressure, ε is the packing porosity, and u is the gas velocity. To represent apparent air velocity, The diameter of the catalyst particles is [missing information]. The viscosity of the reacting gas; The energy balance of the methanol reforming reaction can be expressed as: （12） in, m For quality, h For enthalpy, W This is the work done by the gas expansion. Q To absorb heat during the reaction process, U For the internal energy of the system, P The gas pressure inside the reactor. V The volume of the reacting gas. t For time, j Indicates the import and export nodes of each process; Methanol reforming is an endothermic reaction, and the heat required for the reaction comes from the waste heat of SOFC exhaust. The dynamic gas heat transfer between the methanol vapor phase and the catalyst phase can be expressed as: Gas phase: （13） Catalyst phase: （14） in, T g and T c These are the temperatures of the gas phase and the catalyst phase, respectively. D tube The diameter of the tubular reactor, A tube This refers to the heat exchange area on the tube wall side of the tubular reactor. T w The temperature of the reactor tube wall. a v The specific surface area of ​​the catalyst. r k Let k be the reaction rate. and These are the specific heat capacities of the gas phase and the catalyst phase, respectively. and These are the densities of the gas phase and the catalyst phase, respectively. The thermal conductivity of the catalyst phase, The heat transfer coefficient between the gas phase and the pipe wall. The heat transfer coefficient between the gas phase and the catalyst phase. For the reaction The heat of reaction; The gas heat transfer on the waste heat side of SOFC exhaust can be expressed as: （15） in, u This refers to the gas flow rate; The diffusion flow rates of each component in the gas mixture are calculated using Fick's law: （16） in, J diff For the diffusion flux of different components, D eff Indicates the effective diffusion coefficient of the reactants. C This represents the volume concentration of each component in the diffusing substance; The transport of reactants on the reactor catalyst surface and in the porous medium of SOFC can be described by combining Knudsen diffusion and binary diffusion, and the effective diffusion coefficient can be expressed as: （17） in, D A eff For the effective diffusion coefficient, and Let A and B be the binary diffusion coefficients of components A and B respectively, and Knudsen's diffusion coefficient of component A. D AB and D AK The free molecular diffusion coefficients of components AB and component A, respectively. Porosity represents the porosity of porous media. τ Indicates curvature; The binary diffusion coefficient can be expressed as: （18） in, v i Indicates the molar diffusion volume of each component. P Indicates the pressure of the reaction system. M A and M B These are the molar masses of components A and B, respectively. The Knudsen diffusion coefficient can be expressed as: （19） in, r This indicates the pore size of the porous medium. R The gas constant is 8.314 J / (mol·K). T For temperature, D AK Let Knudsen's diffusion coefficient be the coefficient of component A. The permeability of porous media can be calculated using the Kozeny-Carman correlation: （20） in, k p For porous media permeability, h k It is the Kozeny-Carman constant. A g Specific surface area of ​​porous media particles m -1 ; （21） in, m For quality flow, ρ For density, A The cross-sectional area of ​​the flow path. μ For fluid dynamic viscosity, L The length of the tubular reactor, ΔP The pressure difference across the reactor; The energy balance of the methanol steam reforming reaction can be expressed as: （22） in, V j for j The volume of the process node. T Represents temperature. J i Indicates the diffusion flow rate of each component in the gas mixture. i Indicates different components, H g Indicates the enthalpy value of the mixed gas. h i For the specific enthalpy of each component, Indicates the effective thermal conductivity of a porous medium; （23） in, Let be the thermal conductivity of the gas mixture. It is the thermal conductivity of porous media; （24） in, Q R，MSR This represents the heat of reaction during the entire methanol reforming process. ΔH SR This indicates the enthalpy change during the steam reforming reaction. ΔH MD This indicates the enthalpy change during the methanol decomposition reaction. ΔH WGS This indicates the enthalpy change during the water vapor conversion reaction process. r SR This indicates the reaction rate of the steam reforming reaction. r MD This indicates the reaction rate of the methanol decomposition reaction. r WGS This indicates the reaction rate of the water-vapor conversion reaction.

10. A methanol reforming process modeling device for marine fuel cells, comprising a computer program, characterized in that: The computer program is capable of executing the methanol reforming process modeling method for marine fuel cells as described in any one of claims 1 to 9.

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