Simulation method of hydrogen absorption / desorption process of titanium-based hydrogen storage bulk bed

Abstract

The application discloses a kind of titanium-based hydrogen storage bulk accumulation bed's simulation method of hydrogen absorption / desorption process, it is related to hydrogen storage technical field, the present method includes the following steps: step 1, construct specified size bulk under the action of gravity Random accumulation three-dimensional model;Step 2, for the maximum accumulation bed volume hydrogen storage capacity, with bed porosity as target, set different bulk size and optimize;Step 3, for target titanium-based hydrogen storage bulk accumulation bed hydrogen absorption / desorption process, construct three-dimensional multi-physical field thermal mass coupling model for titanium-based hydrogen storage bulk accumulation bed.The present application considers the influence distribution model of hydrogen storage bulk random accumulation on heat and mass transfer, establishes heat and mass transfer coupling model method, improves the accuracy of heat and mass transfer model in hydrogen absorption / desorption process.In addition, the present method effectively improves the volume hydrogen storage density of titanium-based solid hydrogen storage device since optimizing bulk size is optimized.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage technology, and in particular to a method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed. Background Technology

[0002] Metal hydride hydrogen storage technology, due to its high volumetric hydrogen storage density and safety, is a crucial supporting technology for the commercialization of hydrogen storage and transportation. Among various solid-state hydrogen storage routes, titanium-based solid-state hydrogen storage devices, with titanium-based hydrogen storage materials as the core, have advantages such as abundant resource reserves, low cost, and the ability to achieve room temperature hydrogen absorption and desorption, making them the most promising technology for commercial application. However, existing titanium-based hydrogen storage devices suffer from poor operational performance, uneven temperature / pressure distribution, and high energy consumption, which severely impact device efficiency and operational flexibility in renewable energy consumption hydrogen storage and mobile hydrogen storage application scenarios. Currently, there is some research on hydrogen storage unit stacked beds and hydrogen storage blocks. Research on hydrogen storage units often uses homogenized thermo-mass coupling models for simulation. However, since these models assume that the hydrogen storage material is homogeneous, but the material in actual hydrogen storage devices is compressed into blocks, they cannot reflect the complex thermo-mass flow conditions of the block bed. Research on blocks often focuses on microscopic properties such as powder diameter, block porosity, and material defects, lacking simulation of the block stacking situation in the stacked bed and optimization of block size. Establishing a thermo-mass coupling model based on a bulk-stacking hydrogen storage unit by integrating and optimizing the block size, thereby accurately simulating various indicators of the hydrogen storage unit, remains a challenge.

[0003] Therefore, those skilled in the art are dedicated to developing a simulation method for the hydrogen absorption / desorption process of titanium-based hydrogen storage bulk beds. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problems to be solved by the present invention are that the existing bulk bed model of titanium-based hydrogen storage unit hydrogen absorption / desorption thermo-mass coupling model cannot be determined, the bulk stacking condition of hydrogen storage device cannot be simulated and determined, and the optimal geometric dimensions of hydrogen storage device bulk cannot be determined.

[0005] To achieve the above objectives, the present invention provides a method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed, the method comprising the following steps:

[0006] Step 1: Construct a 3D model of randomly stacked blocks of a specified size under the action of gravity;

[0007] Step 2: Targeting the maximum hydrogen storage capacity of the packed bed volume, set different block sizes and optimize them based on the bed porosity.

[0008] Step 3: Construct a three-dimensional multiphysics thermo-mass coupling model for the hydrogen absorption / desorption process of the target titanium-based hydrogen storage bulk bed.

[0009] Furthermore, step 1 specifically involves constructing a three-dimensional model of randomly stacked blocks of a specified size under the action of gravity based on the open-source discrete element software yade.

[0010] Furthermore, the random stacking 3D model in step 1 specifically includes a block contact model and a position update model.

[0011] Further, step 2 specifically involves: selecting different block diameters and thicknesses to simulate and obtain the corresponding porosity of the stacked bed, and selecting the block size corresponding to the minimum porosity of the bed as the optimal value.

[0012] Furthermore, the specific optimization method in step 2 is as follows: based on the random stacking three-dimensional model in step 1, a large number of blocks are simulated to randomly stack under the action of gravity in a cylindrical region. The optimization objective is to minimize the space not occupied by the blocks in the cylindrical region per unit volume. The block size is optimized by changing the block diameter and thickness.

[0013] Further, step 3 specifically involves: based on the three-dimensional block stacking model proposed in step 1 and the optimal block size in step 2, using finite element multiphysics simulation software to construct a multiphysics coupling model for titanium-based hydrogen storage block stacking beds.

[0014] Furthermore, step 3 specifically includes:

[0015] Step 3.1: Obtain the corresponding material, including bulk thermal conductivity and material hydrogen absorption / desorption thermodynamic model;

[0016] Step 3.2: Based on Step 2, obtain the optimal 3D model of the packing bed and construct a mesh;

[0017] Step 3.3: Construct a three-dimensional multiphysics thermo-mass coupling model of the block-type stacked bed;

[0018] Step 3.4: Calculate the model to obtain information on the hydrogen absorption / desorption process of the hydrogen storage unit.

[0019] Furthermore, the three-dimensional multiphysics thermo-mass coupling model of the bulk bed in step 3.3 is established based on the porous medium mass transfer equation, porous medium heat transfer equation, thermal conductivity equation, and material thermo / kinetic equation.

[0020] Furthermore, the three-dimensional multiphysics thermo-mass coupling model in step 3.3 is constructed and calculated using the finite element multiphysics software COMSOL.

[0021] Furthermore, the hydrogen absorption / desorption process information of the hydrogen storage unit in step 3.4 includes the bed temperature, pressure, hydrogen content, and heat flux.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] 1. To address the problem that the hydrogen absorption / desorption thermo-mass coupling model of titanium-based hydrogen storage units based on bulk bed models cannot be determined, this paper proposes a method for simulating hydrogen absorption / desorption thermo-mass coupling based on a three-dimensional bed model with optimized bulk size. Compared with the traditional homogenization assumption model, this method can effectively improve the model accuracy and simulate flow field changes.

[0024] 2. To address the problem that the bulk accumulation of hydrogen storage devices cannot be simulated and determined, this invention establishes a bulk bed model based on discrete element method software, which simulates the random accumulation of bulk materials under gravity. This model accurately simulates the bulk accumulation in the bed and provides a three-dimensional model foundation for subsequent modeling work.

[0025] 3. To address the problem of not being able to determine the optimal geometric dimensions of the hydrogen storage device block, this invention optimizes the size of the hydrogen storage block with the goal of minimizing the porosity of the stacked bed, which significantly reduces the porosity of the stacked bed and increases the volumetric hydrogen storage capacity of the block stacked bed, thereby improving the capacity of the corresponding hydrogen storage device.

[0026] Compared to existing methods, this invention improves the accuracy of the heat and mass transport model for the hydrogen absorption / desorption process by proposing a simulation method that considers the influence of random stacking of hydrogen storage blocks on the distribution of heat and mass transport, and establishing a coupled heat and mass transport model. Furthermore, this method effectively increases the volumetric hydrogen storage density of titanium-based solid-state hydrogen storage devices by optimizing the block size.

[0027] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0028] Figure 1 This is a schematic flowchart illustrating the simulation method for the hydrogen absorption / desorption process of the titanium-based hydrogen storage bulk bed of the present invention.

[0029] Figure 2 This is an embodiment of the invention showing the correspondence between the porosity of the bulk bed and the size of the bulk blocks;

[0030] Figure 3 This describes the block stacking situation when the block size is optimal in the embodiments of the present invention;

[0031] Figure 4 This is the mesh partitioning result corresponding to the optimal stacking situation in the embodiments of the present invention;

[0032] Figure 5 This is a comparison of external heat flux at different virtual startup times in embodiments of the present invention;

[0033] Figure 6 This is a comparison of the highest, average, and lowest hydrogen contents under different virtual start-up times in the embodiments of the present invention;

[0034] Figure 7 This is a comparison of the highest, average, and lowest pressure under different virtual startup times in the embodiments of the present invention;

[0035] Figure 8 This is a comparison of the highest, average, and lowest temperatures under different virtual startup times in the embodiments of the present invention. Detailed Implementation

[0036] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0037] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0038] like Figure 1 As shown, a simulation method for the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed is provided, the method specifically including the following steps:

[0039] Step 1: Construct a 3D model of randomly stacked blocks of a specified size under the action of gravity;

[0040] Step 2: Targeting the maximum hydrogen storage capacity of the packed bed volume, set different block sizes and optimize them based on the bed porosity.

[0041] Step 3: Construct a three-dimensional multiphysics thermo-mass coupling model for the hydrogen absorption / desorption process of the target titanium-based hydrogen storage bulk bed.

[0042] This embodiment describes the hydrogen release process of a hydrogen storage unit formed by stacking titanium-based hydrogen storage material blocks. The main parameters of the material and the block are shown in Table 1.

[0043] Table 1. Main operating parameters of titanium-based materials and bulk materials in this example.

[0044]

[0045] The block diameter and thickness are the results of simulation optimization using Yade software. The optimization method involves simulating different block diameters and thicknesses to obtain the corresponding porosity of the packing bed, and selecting the block size corresponding to the minimum bed porosity as the optimal value. In this embodiment, after defining parameters such as block density, Young's modulus, and friction angle, the PotentialBlock command is used to define the blocks, the cylindrical regions are constructed using the cylindricalPlates and inCylinder commands, and 1000 blocks are randomly generated within the cylindrical region using the makeCloud command. A random packing simulation is then performed under gravity, with a time step of 0.00001 seconds and a total simulation time of 10 seconds. The optimization objective is to minimize the space not occupied by blocks within the cylindrical region per unit volume. The optimization results are as follows: Figure 2 As shown, the minimum porosity of the packing bed is achieved when the block diameter is 10mm, the thickness is 8mm, and the porosity is 40%. Therefore, the optimal 3D model of the packing bed is obtained, and the packing configuration is as follows. Figure 3 As shown. Subsequently, the position information of each block at the last moment is saved as a VTK format file using VTKExporter.

[0046] First, the thermal conductivity of the corresponding materials and the thermodynamic model of hydrogen absorption / desorption were obtained. Then, the model was built and calculated using the finite element multiphysics software COMSOL. Based on the aforementioned VTK file, a Python script was written to obtain the angle normal vectors and center point positions of each block, and converted into a CSV file. COMSOL with Matlab was used to read the block position information file and a script was written to build the corresponding cylinders for each block, constructing a multiphysics coupled model for a titanium-based hydrogen storage bulk bed. The parameters of the constructed model are shown in Table 1. The mesh results after importing the geometry module are as follows: Figure 4 As shown in the figure. Finally, the model is calculated to obtain information on the hydrogen absorption / desorption process of the hydrogen storage unit. The virtual hydrogen desorption time t' is set to 15000s and 1500s respectively, and the model is solved to obtain the heat flux, hydrogen content, pressure and temperature results at t', as shown in the figure. Figures 5-8 As shown in the figure, the results indicate that at t' = 1500s, the bed rapidly releases hydrogen for a period of time; at this time, the external heat flux is negative and its absolute value continuously increases, indicating that the outermost temperature is continuously decreasing; pressure, temperature, and hydrogen content all decrease. Subsequently, it enters a bottleneck. Due to the relatively uniform pressure distribution, it can be inferred that temperature is the limiting factor at this point. Because the bed rapidly releases hydrogen and absorbs heat, the temperature decreases too quickly. Although the outer wall is at a constant temperature, it is restricted by the porous medium and hydrogen gas and cannot effectively heat the unit. The device cannot completely release the hydrogen gas, thus entering a bottleneck. When t' = 15000s, the hydrogen release rate decreases, the hydrogen release time is prolonged, but the amount of hydrogen released is greater.

[0047] In summary, this embodiment simulates the hydrogen release process of a bulk hydrogen storage material bed, optimizes the bulk size, and simulates processes with different hydrogen release rates. The results show that the proposed method for optimizing the bulk size and simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bed can significantly improve the volumetric hydrogen storage capacity of the bed and accurately reflect the changes in various physical quantities during the hydrogen absorption / desorption process.

[0048] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed, characterized in that, The method includes the following steps: Step 1: Construct a 3D model of randomly stacked blocks of a specified size under the action of gravity; Step 2: Targeting the maximum hydrogen storage capacity of the packed bed volume, set different block sizes and optimize them based on the bed porosity. Step 3: Construct a three-dimensional multiphysics thermo-mass coupling model for the hydrogen absorption / desorption process of the target titanium-based hydrogen storage bulk bed; Step 3 specifically includes: Step 3.1: Obtain the bulk thermal conductivity and the material's hydrogen absorption / desorption thermodynamic model; Step 3.2: Based on Step 2, obtain the optimal 3D model of the packing bed and construct a mesh; Step 3.3: Construct a three-dimensional multiphysics thermo-mass coupling model of the bulk bed; the three-dimensional multiphysics thermo-mass coupling model of the bulk bed is based on the mass transfer equation of porous media, the heat transfer equation of porous media, the thermal conductivity equation, and the material thermo / kinetic equation; Step 3.4: Calculate the model to obtain information on the hydrogen absorption / desorption process of the hydrogen storage unit.

2. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, Step 1 specifically involves constructing a three-dimensional model of randomly stacked blocks of a specified size under the action of gravity, based on the open-source discrete element software yade.

3. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, The random stacking 3D model in step 1 specifically includes a block contact model and a position update model.

4. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, Step 2 specifically involves: selecting different block diameters and thicknesses to simulate and obtain the corresponding porosity of the stacked bed, and selecting the block size corresponding to the minimum porosity of the bed as the optimal value.

5. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, The specific optimization method in step 2 is as follows: based on the random stacking three-dimensional model in step 1, a large number of blocks are simulated to randomly stack under the action of gravity in a cylindrical region. The optimization objective is to minimize the space not occupied by the blocks in the cylindrical region per unit volume. The block size is optimized by changing the block diameter and thickness.

6. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, The three-dimensional multiphysics thermo-mass coupling model in step 3.3 is constructed and calculated using the finite element multiphysics software COMSOL.

7. The method for simulating the hydrogen absorption / desorption process of a titanium-based hydrogen storage bulk bed as described in claim 1, characterized in that, The hydrogen absorption / desorption process information of the hydrogen storage unit in step 3.4 includes bed temperature, pressure, hydrogen content, and heat flux.

Images