A device for measuring the expansion rate of hydrogen storage alloy tablets

Abstract

The utility model relates to hydrogen storage alloy tabletting expansion rate measurement technical field, especially in kind of measure hydrogen storage alloy tabletting expansion rate's device, main including cylindrical jar body, the top of jar body is sealed with high borosilicate glass, the top of high borosilicate glass is arranged with high definition video recording equipment, and the lateral wall of jar body is connected with gas supply pipeline, and the inner chamber bottom of jar body places and places hydrogen storage alloy tabletting of transverse oxygen storage alloy tabletting, the utility model discloses double tabletting horizontal and vertical layout mode, improves hydrogen storage alloy volume expansion calculation precision, makes researcher obtain reliable volume expansion rate data, provides accurate quantitative index for material performance analysis, adopts adhesive fixing method, and hydrogen storage alloy's boundary restraint force action is reduced as far as possible, makes material in the experiment process can expand freely, and the natural state of its in hydrogen pressure environment is truly reflected, adopts dynamic image recording equipment whole process to capture the morphological change of material, and records hydrogen storage alloy expansion change details.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen storage alloy tablet expansion rate measurement technology, and in particular to a device for measuring the expansion rate of hydrogen storage alloy tablets. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, has always attracted much attention. At present, there are three main ways to store hydrogen in a physical form: gaseous hydrogen storage, liquid hydrogen storage, and solid hydrogen storage. Among them, solid hydrogen storage has advantages over gaseous and liquid hydrogen storage, such as high hydrogen storage density, low pressure, good safety, and high hydrogen purity, and is an important direction for the development of hydrogen storage.

[0003] Hydrogen storage alloys, as the core carriers of solid-state hydrogen storage materials, have their volume expansion rate during hydrogen absorption / desorption as a key parameter for evaluating cycle life and structural stability. Current measurement techniques in this field suffer from the following significant shortcomings:

[0004] 1. Defect of single measurement direction: The mainstream method only monitors radial expansion and ignores axial deformation, while hydrogen storage alloys actually expand anisotropically, and single-dimensional measurement leads to volume calculation errors;

[0005] 2. Sample fixation interference: Mechanical clamping introduces additional constraint forces, changing the free expansion boundary conditions;

[0006] 3. Limitations of the measurement method: Existing methods only measure volume after hydrogen absorption is complete, and cannot capture the dynamic expansion process.

[0007] In summary, addressing the aforementioned deficiencies and ensuring real-time observation of the alloy tablet expansion process under high pressure and real-time measurement of the hydrogen storage alloy tablet expansion rate are urgent problems to be solved in this field. Utility Model Content

[0008] Based on the above problems, the purpose of this utility model is to provide a device for measuring the expansion rate of hydrogen storage alloy tablets. This utility model adopts the following technical solution:

[0009] This utility model provides a device for measuring the expansion rate of hydrogen storage alloy blister packs, including a cylindrical tank, the top of which is sealed with high borosilicate glass, a high-definition video recording device is arranged above the high borosilicate glass, a gas supply pipe is connected to the side wall of the tank, and a horizontally placed oxygen storage alloy blister pack and a vertically placed hydrogen storage alloy blister pack are placed at the bottom of the inner cavity of the tank.

[0010] Preferably, a first flange and a second flange are respectively provided on the upper and lower sides of the high borosilicate glass. The first flange and the second flange are fixed by multiple sets of bolt assemblies. The second flange is fixed at the top of the tank. A polytetrafluoroethylene gasket is provided at the contact position between the first flange and the high borosilicate glass, and a fluororubber O-ring is provided at the contact position between the second flange and the high borosilicate glass.

[0011] Preferably, the roughness Ra of the sealing surfaces of the first and second flanges is ≤3.2µm; and the perpendicularity deviation between the high borosilicate glass and the tank axis is ≤0.1°.

[0012] Preferably, the number of bolt assemblies is six.

[0013] Preferably, the radius of the tank is 30-100mm and the height is 50-150mm;

[0014] The thickness of the high borosilicate glass is 20-40 mm, and its pressure resistance is ≤5 MPa.

[0015] Preferably, both the horizontally placed oxygen storage alloy sheet and the vertically placed hydrogen storage alloy sheet are adhered to the bottom of the inner cavity using an adhesive.

[0016] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0017] 1. High-pressure environment observation technology: Combined with a high borosilicate glass observation window, dynamic observation of the material expansion process can be achieved under hydrogen pressure environments below 5 MPa; the high borosilicate glass observation window has excellent chemical stability and mechanical strength, which can withstand high pressure and provide a clear and transparent observation view, ensuring that researchers can capture the subtle changes of materials under hydrogen pressure in real time, providing intuitive evidence for material performance research.

[0018] The polytetrafluoroethylene gasket, borosilicate glass, and fluororubber O-ring constitute a three-layer sealing structure design, which effectively prevents hydrogen leakage and ensures experimental safety.

[0019] 2. High-precision measurement technology: An innovative in-situ measurement method using simultaneous transverse / vertical dual-pressing significantly improves the accuracy of volumetric expansion rate measurement. This technology, through the coordinated work of transverse and longitudinal pressing, collects material deformation data in real time from multiple dimensions, avoiding errors caused by single-direction measurement. Simultaneous in-situ measurement ensures the timeliness and accuracy of data acquisition, enabling researchers to obtain reliable volumetric expansion rate data and providing precise quantitative indicators for material performance analysis.

[0020] 3. Unconstrained Fixing Technology: Breaking away from traditional fixing methods, this technique employs an adhesive-based, clamp-free fixing method to minimize the effect of boundary constraint forces. This fixing method reduces the additional constraints imposed by clamps on the material boundaries, allowing the material to expand freely during the experiment and truly reflecting its natural state under hydrogen pressure. Eliminating boundary constraint interference results in experimental results that more closely resemble actual working conditions, providing more reliable data support for material performance research.

[0021] 4. Full-process dynamic monitoring and analysis technology: From the beginning to the end of the experiment, the dynamic image recording equipment captures the morphological changes of the material throughout the entire process, recording the details of every moment; the minute-level computing power ensures rapid data processing and analysis, and timely converts image information into visualized continuous curves, intuitively showing the changing trend of the material expansion process, which facilitates researchers to deeply analyze the evolution law of material properties and provides strong data support for scientific research and engineering applications. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 The diagram shown is a schematic representation of the overall structure of the device for measuring the expansion rate of hydrogen storage alloy tablets according to this invention.

[0024] Figure 2 The image shown is a high-definition video recorder view of the measurement of the expansion rate of the hydrogen storage alloy sheet according to this invention.

[0025] Figure 3 The image shows a horizontally placed hydrogen storage alloy press and an oxygen storage alloy press of the present invention, with a thickness H of 10a. t Graph showing changes over time;

[0026] Figure 4 The figure shows the diameter D of the longitudinally arranged hydrogen storage alloy press 10b of this utility model. t Graph showing changes over time;

[0027] Figure 5 The figure shows the expansion coefficient δ of the hydrogen storage alloy tablet of this invention. V Graph showing changes over time.

[0028] Explanation of reference numerals in the attached drawings: 1. Tank body; 2a. Second flange; 2b. First flange; 3. Bolt assembly; 4. High-definition video recording equipment; 5. Polytetrafluoroethylene gasket; 6. High borosilicate glass; 7. Fluororubber O-ring; 8. Gas supply pipeline; 9. Bottom of inner cavity; 10a. Horizontal oxygen storage alloy pressure plate; 10b. Vertical hydrogen storage alloy pressure plate. Detailed Implementation

[0029] To make the technical problems, technical solutions and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, this embodiment discloses a device for measuring the expansion rate of hydrogen storage alloy pellets, including a cylindrical tank 1. A high-borosilicate glass 6 is sealed at the top of the tank 1, and a high-definition video recording device 4 is arranged above the high-borosilicate glass 6 to record the expansion process of the hydrogen storage alloy pellets. A gas supply pipe 8 is connected to the side wall of the tank 1, and a horizontally placed oxygen storage alloy pellet 10a and a vertically placed hydrogen storage alloy pellet 10b are placed at the bottom 9 of the inner cavity of the tank 1.

[0031] The high borosilicate glass 6 is provided with a first flange 2b and a second flange 2a on its upper and lower sides respectively. The first flange 2b and the second flange 2a are fixed by a six-bolt assembly 3. The second flange 2a is fixed at the top of the tank body 1. A polytetrafluoroethylene gasket 5 is provided at the contact position between the first flange 2b and the high borosilicate glass 6, and a fluororubber O-ring 7 is provided at the contact position between the second flange 2a and the high borosilicate glass 6.

[0032] Specifically, the preload of bolt assembly 3 is 15–30 N·m. The surface roughness Ra of the sealing surfaces of the first flange 2b and the second flange 2a is ≤3.2 μm; the perpendicularity deviation between the high borosilicate glass 6 and the axis of the tank body 1 is ≤0.1°; the radius of the tank body 1 is 30–100 mm, and the height is 50–150 mm; the thickness of the high borosilicate glass 6 is 20–40 mm, and the pressure resistance is ≤5 MPa. The horizontally placed oxygen storage alloy plate 10a and the vertically placed hydrogen storage alloy plate 10b are both adhered to the bottom of the inner cavity 9 by adhesive.

[0033] like Figure 1 As shown, in this embodiment, the hydrogen alloy sheet is circular. The axis of the horizontally placed oxygen storage alloy sheet 10a is parallel to the horizontal plane, and the axis of the vertically placed hydrogen storage alloy sheet 10b is perpendicular to the horizontal plane. Therefore, as... Figure 2 As shown, for the thickness measurement of the transverse oxygen storage alloy pellet 10a, the straight line measurement tool in the software is used to draw the thickness line on the image to obtain H. t Numerical value. For the diameter measurement of the longitudinally placed hydrogen storage alloy pellet 10b, the linear measurement tool in the software is used to draw a diameter line through the center of the pellet on the image, obtaining D. t Numerical value.

[0034] like Figures 2 to 5 As shown, the specific method of using this utility model includes the following steps:

[0035] (S1) Before operation, the surfaces of the horizontal oxygen storage alloy pellet 10a, the vertical hydrogen storage alloy pellet 10b, and the bottom of the inner cavity 9 must be cleaned. Use a lint-free cloth dampened with anhydrous ethanol to wipe away surface oil, dust, and other impurities to ensure the bonding surfaces are clean. Apply a layer of a special adhesive with high strength and low shrinkage evenly to the bottom surface of the pellets. Place the horizontal oxygen storage alloy pellet 10a and the vertical hydrogen storage alloy pellet 10b at the pre-marked center positions on the bottom of the inner cavity 9. After placement, allow them to stand at room temperature for 4 hours to allow the adhesive to fully cure. During this period, avoid any vibration or external interference to ensure a firm bond between the pellets and the bottom of the inner cavity 9, providing a stable and reliable foundation for subsequent experiments.

[0036] (S2) Before assembly, check the sealing surfaces of the first flange 2b and the second flange 2a for scratches, dents, or other defects. If any are found, repair or replace them promptly. First, place the PTFE gasket 5 flat in the sealing groove of the first flange 2b. The PTFE gasket 5 has good chemical stability and can effectively resist hydrogen corrosion. At the same time, its low coefficient of friction can reduce stress concentration during installation. Next, carefully place the borosilicate glass 6, taking care to avoid scratching the glass surface. The borosilicate glass 6, with its excellent mechanical strength and light transmittance, can provide a clear observation window under high pressure. Then, embed the fluororubber O-ring 7 into the corresponding groove of the second flange 2a. The excellent elasticity of fluororubber allows it to fit tightly against the flange sealing surface under pressure, forming an efficient sealing barrier. Use a torque wrench to tighten the 6 bolt assemblies 3 in a diagonal, crisscrossing order, gradually applying the torque to 25 N·m in 3-4 steps to ensure that the bolts are evenly stressed and to prevent flange deformation that could lead to sealing failure.

[0037] (S3) During leak detection, first seal all interfaces of the device, then fill the tank 1 with nitrogen through the gas supply pipe 8, slowly increasing the pressure to 4 MPa (target pressure 1.3 times the safety factor) at a rate of 0.2 MPa / min, and maintain the pressure for 1 hour. During the pressure maintenance period, use foam water to check the sealing parts such as flange connections and sensor interfaces point by point. If bubbles are continuously generated, immediately mark the leak point. After the pressure maintenance is completed, if the pressure drops by more than 0.03 MPa, leak detection and repair are required again. Place the tank 1 in a water bath heating pot and heat it to 90℃ at a rate of 2℃ / min, while simultaneously evacuating the vacuum until the pressure is below 1×10⁻⁶. -3 Pa, under these conditions for 2 hours, remove the surface oxide layer and impurities, so that the tablet reaches the optimal hydrogen storage activity state, laying the foundation for subsequent experiments.

[0038] (S4) After confirming that the hydrogen storage alloy tablet activation is complete and the airtightness test of the device is qualified, connect the gas supply pipeline 8 to the calibrated high-purity hydrogen supply system. A two-stage pressure reduction device is used: first, the output pressure of the hydrogen cylinder is adjusted to 1.5 MPa, and then the pressure is stabilized at 0.5 MPa through a high-precision proportional valve. Using a mass flow controller, hydrogen is introduced into the tank 1 at an initial rate of 40 sccm, and the pressure sensor data is monitored in real time. When the pressure inside the tank reaches 2.8 MPa, the introducing rate is reduced to 10 sccm. After reaching the target pressure of 3 MPa, this pressure is maintained continuously. The gas intake is dynamically adjusted through a closed-loop control system to ensure that the pressure fluctuation range is controlled within ±0.02 MPa, providing reliable conditions for the study of the expansion process of the hydrogen storage alloy tablet under stable hydrogen pressure.

[0039] (S5) Select a camera with high resolution and high frame rate, and mount it on a fixed bracket perpendicular to the bottom 9 of the inner cavity. Ensure that the center of the lens of the high-definition recording device 4 is aligned with the center of the bottom 9 of the inner cavity, with the lens approximately 9.5cm away from the bottom 9 of the inner cavity, to obtain a clear and complete field of view. Adjust the camera parameters, set automatic white balance and automatic exposure modes to ensure uniform and stable image brightness and color. Use professional image acquisition software, set the recording time to the expected total experimental time, and enable continuous recording. For the recorded video, manually extract one frame every minute and save it as a high-resolution PNG file.

[0040] (S6) Import the captured image into professional image analysis software. First, perform image calibration. Using a standard reference of known size, take images under the same experimental conditions to obtain the conversion coefficient between pixels and actual size. For the thickness measurement of the 10a transverse oxygen storage alloy pellet, use the linear measurement tool in the software to draw a thickness line on the image to obtain H. t Numerical values; for the diameter measurement of the vertically placed hydrogen storage alloy pellet 10b, the linear measurement tool in the software is used to draw a diameter line through the center of the pellet on the image to obtain D. t Numerical values. Before each measurement, the image calibration parameters must be checked for accuracy to ensure the reliability of the measurement data.

[0041] (S7) The thickness H of the transverse oxygen storage alloy press 10a is measured. t And the longitudinally placed hydrogen storage alloy press with a diameter D of 10b tThe data was organized into a CSV file and imported into a Python program. The NumPy library was used to read the data, and the Akima interpolation function from the SciPy library was used to process the diameter data. Akima interpolation can better preserve the local features of the data while ensuring the smoothness of the curve, making it suitable for handling data with sharp variations. For diameter and thickness data, a cubic spline interpolation function was used. This method constructs a piecewise cubic polynomial, giving the curve continuous first and second derivatives at the nodes, generating a smooth curve. To simulate random errors in actual experiments, the `random.normal()` function from the NumPy library was used to generate noise data conforming to a normal distribution. The noise standard deviation was set to 0.01 mm based on the experimental measurement accuracy, and the noise was superimposed on the interpolated data. Finally, the `gaussian_filter1d()` function from the SciPy library was used for Gaussian convolution smoothing. An appropriate standard deviation was selected to smooth the data, eliminating high-frequency fluctuations caused by noise and measurement errors, making the data curve smoother and more stable.

[0042] (S8) To ensure that the volume expansion rate data conforms to physical laws, a Python function was written to enhance monotonicity. The processed data sequence is iterated; if the data at a certain moment is less than the data at the previous moment, cubic spline interpolation is used to correct the data, making it greater than or equal to the previous moment's data, ensuring that the data increases monotonically with time. For key inflection points, a smooth transition function is used to smoothly connect the data before and after the inflection point, avoiding abrupt changes in the data. In specific implementation, the function parameters are adjusted according to the location of the inflection point and the magnitude of data change to make the curve transition natural and smooth, ensuring that the processed data not only reflects the true expansion characteristics of the material but also conforms to physical laws.

[0043] (S9) Based on the thickness H of the processed transverse oxygen storage alloy press 10a t And the longitudinally placed hydrogen storage alloy press with a diameter D of 10b t The data, combined with the initial thickness H0 and initial diameter D0 of the tablet, are used according to the formula for the volume of a cylinder. Calculate the volume V of the tablet at different times. t And the initial volume V0. The formula for calculating the real-time volume expansion rate is: Use Python loop statements to iterate through each group of D. t and H t The data is substituted into the formula to calculate the corresponding real-time volume expansion rate, and the calculation results are saved as a new CSV file. Simultaneously, the Matplotlib library is used to plot the curve of volume expansion rate over time, visually demonstrating the expansion process of the material under hydrogen pressure, providing visualized data support for analyzing material properties.

[0044] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A device for measuring the expansion rate of hydrogen storage alloy tablets, characterized in that: The tank includes a cylindrical tank (1), the top of which is sealed with borosilicate glass (6), a high-definition video recording device (4) is arranged above the borosilicate glass (6), a gas supply pipe (8) is connected to the side wall of the tank (1), and a horizontal oxygen storage alloy plate (10a) and a vertical hydrogen storage alloy plate (10b) are placed at the bottom (9) of the inner cavity of the tank (1).

2. The apparatus for measuring the expansion rate of hydrogen storage alloy tablets according to claim 1, characterized in that: The high borosilicate glass (6) is provided with a first flange (2b) and a second flange (2a) on its upper and lower sides respectively. The first flange (2b) and the second flange (2a) are fixed by multiple sets of bolt assemblies (3). The second flange (2a) is fixed at the top of the tank body (1). A polytetrafluoroethylene gasket (5) is provided at the contact position between the first flange (2b) and the high borosilicate glass (6). A fluororubber O-ring (7) is provided at the contact position between the second flange (2a) and the high borosilicate glass (6).

3. The apparatus for measuring the expansion rate of hydrogen storage alloy tablets according to claim 2, characterized in that: The roughness Ra of the sealing surfaces of the first flange (2b) and the second flange (2a) is ≤3.2um; the perpendicularity deviation between the high borosilicate glass (6) and the tank body (1) is ≤0.1°.

4. The apparatus for measuring the expansion rate of hydrogen storage alloy pellets according to claim 2, characterized in that: The number of bolt assemblies (3) is six.

5. The apparatus for measuring the expansion rate of hydrogen storage alloy pellets according to claim 1, characterized in that: The radius of the tank (1) is 30-100mm and the height is 50-150mm; The thickness of the high borosilicate glass (6) is 20-40 mm, and the pressure resistance is ≤5 MPa.

6. The apparatus for measuring the expansion rate of hydrogen storage alloy tablets according to claim 1, characterized in that: Both the horizontally placed oxygen storage alloy sheet (10a) and the vertically placed hydrogen storage alloy sheet (10b) are adhered to the bottom of the inner cavity (9) by an adhesive.

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