Measuring device and testing method for transport performance of working medium in porous material
A non-destructive testing method for porous materials using real-time mass monitoring and linear regression addresses the limitations of existing methods, providing precise fluid transport property measurements.
Patent Information
- Application Number
- CN202510470513.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2025-07-08
AI Technical Summary
Existing methods for measuring the transport properties of fluids in porous materials are cumbersome, prone to human error, and often require destructive testing, failing to accurately capture the fluid dynamics due to neglecting inertial and gravitational forces, and are limited in applicability.
A non-destructive testing method using a setup comprising a sample fixation system, a liquid reservoir, and a weighing system to monitor fluid mass changes in real-time, allowing for precise determination of transport properties by linear regression analysis, incorporating inertial forces if needed.
Enables high-precision, cost-effective, and non-destructive measurement of fluid transport properties in porous materials, reducing human error and enabling accurate determination of key parameters like permeability and effective pore radius.
Smart Images
Figure CN120275233A_ABST
Abstract
Description
Technical field:
[0001] The invention belongs to the technical field of thermal management, and in particular relates to a measuring device and a testing method for the working medium transport performance in a porous material. Background technology:
[0002] With the continuous development of electronic components and equipment and the continuous improvement of their performance, the overheating problem caused by the increase in heat flux density during use has become more and more prominent, and the demand for heat dissipation has continued to increase. As a highly efficient and widely used heat dissipation component, the driving force of heat pipes mainly comes from capillary core porous materials. The effective capillary radius R of the porous material eff The smaller it is, the greater the capillary driving force. eff If it is too small, the permeability K of the working fluid flowing inside will be too small. Therefore, K / R is often used to eff Characterize the comprehensive transport performance of the working fluid. Measuring the transport performance of the working fluid in the capillary wick porous material is an important means to evaluate the performance of the capillary wick.
[0003] The existing method for testing the internal transport performance of porous materials is to use a high-speed camera or an infrared thermal imager to shoot the relationship between the rising height h of the working fluid and the time t during the porous material absorption process, and ignore the influence of forces such as inertia and gravity, and obtain the following Lucas-Washburn formula (Washburn E W. The Dynamics of Capillary Flow [J]. Physical Review, 1921, 17 (3): 273-283):
[0004]
[0005] Where ρ and μ are the liquid density and viscosity, θ is the contact angle, and ε is the porosity of the porous material.
[0006] From formula 1, we can see that the square of the liquid rising height h 2 It is linearly related to time t, and K / R can be obtained by linear fitting eff .
[0007] This method has several disadvantages: (1) The rising front of the liquid working medium during the aspiration process is not an ideal straight line, and data extraction is complex and subject to large human errors; (2) Since the effects of forces such as inertia and gravity are ignored, it is generally only applicable to 10% of the maximum aspiration height; (3) For devices with porous materials inside, such as heat pipes, non-destructive measurements cannot be performed and they must be cut open for testing. In addition, the porous materials will be damaged to a certain extent during the cutting process, resulting in measurement errors.
[0008] The test device and method for the working fluid transport performance inside this porous material provide a method capable of accurately and efficiently measuring the flow performance of the porous material, and can achieve non-destructive measurement of devices inside porous materials such as heat pipes. This method can also be extended to the measurement of the working fluid transport performance inside other porous materials besides the capillary core of the heat pipe. Summary of the Invention:
[0009] Aiming at the disadvantages of the existing test methods for the working fluid transport performance inside porous materials, such as being cumbersome, complex, and having poor versatility. The present invention designs a measurement device and test method for the working fluid transport performance inside porous materials, which can efficiently perform the flow performance test of the working fluid transport performance inside porous materials and non-destructively test devices inside porous materials such as heat pipes, and extract key performance parameters therefrom to accurately characterize the working fluid transport performance of the porous material.
[0010] To achieve the above object, the present invention adopts the following technical solutions:
[0011] In this patent, the test device for the working fluid transport performance inside the porous material consists of a fixed subsystem for the sample to be tested, a liquid working fluid container, and a weighing subsystem. The working fluid transport performance inside the porous material is extracted by real-time monitoring of the mass change of the liquid working fluid in the porous material.
[0012] In this device, the fixed subsystem for the sample to be tested is a system for fixing and adjusting the distance between the sample to be tested and the weighing device. The fixed subsystem for the sample to be tested can be composed of one or more devices. For example, in the laboratory, a combination device of a lifting platform and an iron stand can be used, and in industry, it can be designed as a specific fixing device. The adjustment of the distance can be manual or through automatic control.
[0013] The working fluid container of this device is a container that can hold the liquid working fluid. As long as one end of the sample to be tested can touch the liquid level of the working fluid in the container, there are no restrictions on its shape, size, and material.
[0014] One of the core components of this device, the weighing subsystem, is a device for real-time monitoring of the mass change of the working fluid in the porous material, with a real-time response function, so as to accurately measure the mass of the working fluid in the porous material at the current moment. The weighing devices of the weighing subsystem include but are not limited to mass measurement devices such as balances and scales, mechanical property measurement devices such as pressure sensors, or optical weighing devices based on optical reflection and deformation. Preferably, an analytical balance is used. Preferably, the weighing subsystem also needs to be equipped with a printing function to print out the data; or preferably, the weighing subsystem has a communication port connected to the data acquisition module to transmit the acquired mass data to devices or modules such as a data acquisition computer or a single-chip microcomputer.
[0015] The fixed subsystem for the sample to be tested of this device can also be included in the weighing subsystem.
[0016] The specific process of the test method for the working fluid transport performance in porous materials is as follows:
[0017] Step 1: Fix the sample to be tested in the fixed sub-system for the sample to be tested. Add an appropriate amount of working fluid to the liquid working fluid container, adjust the distance between the sample and the liquid level of the working fluid, and allow the liquid working fluid to climb in the sample to be tested. Record the mass during this process.
[0018] Step 2: According to Equation 2, perform a linear fit of dm / dt and 1 / m.
[0019]
[0020] where: m is the mass of the liquid absorbed by the porous material, t is time, R eff and K are the effective capillary radius and permeability of the porous material respectively, and C1 and C2 are two coefficients related to the porous structure and the physical properties of the working fluid.
[0021] Then the intercept is C2·K, and the slope is C1·K / R eff , obtain K. Then substitute the values of C1 and C2 into the intercept and slope to obtain K, K / R eff and R eff and other key flow performance parameters. If higher precision is required, an inertial force term can be added to Equation 2.
[0022] Step 3: Optionally, according to Equation 3, obtain another set of commonly used arrays representing the flow performance, Δp c ·K, and further obtain Δp from the value of K c .
[0023]
[0024] where: Δp c is the capillary force of the capillary structure.
[0025] Compared with the existing methods for testing the flow performance of porous materials using high-speed cameras or infrared cameras, the present invention has the following beneficial effects:
[0026] (1) This device realizes high-precision measurement of the flow performance of porous materials at a lower cost.
[0027] (2) This device can quickly obtain an accurate curve of the liquid absorption mass changing with time after the measurement is completed, avoiding errors caused by complex manual operations such as reading the liquid level in the picture, and improving the test efficiency of the flow performance of porous materials.
[0028] (3) In addition to obtaining K / R eff , this method can also obtain K and R simultaneously effThe specific value. Another set of arrays commonly used to characterize the flow performance, Δp, can also be obtained. c ·K, and Δp c and the specific values of K.
[0029] (4) This device can accurately and nondestructively test the flow performance of the porous material inside the closed device. Description of the Drawings:
[0030] Figure 1 This is one of the overall structural schematic diagrams used for the flow performance testing device and method of a porous material of the present invention. It includes a weighing subsystem (including an analytical balance 101A, a computer 101B, and a connecting cable 101C), a fixed subsystem for the sample to be tested (including a lifting table 201A and an iron stand 201B), a liquid working medium container 301, and a sample 401 to be tested.
[0031] Figure 2 This is another overall structural schematic diagram used for the flow performance testing device and method of a porous material of the present invention. It includes a weighing subsystem (including an analytical balance 101A, a computer 101B, and a connecting cable 101C), a fixed subsystem for the sample to be tested (including a lifting table 201A, a weight 201B, a cable 201C, and a pulley 201D), a liquid working medium container 301, and a sample 401 to be tested.
[0032] Figure 3 This is yet another overall structural schematic diagram used for the flow performance testing device and method of a porous material of the present invention. It includes a weighing subsystem (including a tension sensor 101A, a computer 101B, and a connecting cable 101C), a fixed subsystem for the sample to be tested (a fixed block 201A and a cable 201B), a liquid working medium container 301, and a sample 401 to be tested.
[0033] Figure 4 This is still another overall structural schematic diagram used for the flow performance testing device and method of a porous material of the present invention. It includes a weighing subsystem (including a tension sensor 101A, a computer 101B, and a connecting cable 101C), a fixed subsystem for the sample to be tested (a fixed block 201A and a cable 201B), a liquid working medium container 301, and a sample 401 to be tested.
[0034] Figure 5 This is still another overall structural schematic diagram used for the flow performance testing device and method of a porous material of the present invention. It includes a weighing subsystem (including an analytical balance 101A, a computer 101B, and a connecting cable 101C), a fixed subsystem for the sample to be tested (including a lifting table 201A and an iron stand 201B), a liquid working medium container 301, and a sample 401 to be tested.
[0035] Figure 6 Schematic diagram of the results obtained from the tests of Example 1, Example 2 and the theoretical model.
[0036] Figure 7 Schematic diagram of the results obtained from the test of Example 3 and its theoretical model. Specific implementation method:
[0037] Example 1: Use Figures 1-5 the device shown to measure the working fluid transport performance (flow performance) of a certain porous material.
[0038] First step: Fix the sample to be measured 401 on the iron stand 201B of the sample fixing subsystem shown. Add an appropriate amount of working fluid to the liquid working fluid container 301. Adjust the distance between the sample 401 and the liquid level of the working fluid through the lifting table 201A to make the liquid working fluid climb in the sample 401 to be measured. Record the mass during this process through the analytical balance 101A and transmit it to the computer 101B. Figure 1
[0039] Second step: Through the analysis and processing of the stored data, obtain the accurate curve of the working fluid mass change in the porous medium during the flow performance test of the porous material in Example 1 (as Figure 6 shown). Through Equation 2, obtain the intercept as C2·K and the slope as C1·K / R eff eff , and calculate K. Then substitute the values of C1 and C2 into the intercept and slope to calculate K, K / R eff and R eff and other key flow performance parameters.
[0040] As a reliability verification, in software with the ability to perform mathematical equation calculations, according to the extracted key flow performance parameters, calculate its theoretical flow performance parameter curve and compare it with the curve obtained from the test to verify the accuracy of the measurement results in Example 1 (as Figure 6 shown).
[0041] Example 2: Use Figures 1-5 the device shown to measure the working fluid transport performance (flow performance) of the same sample as in Example 1.
[0042] First step: Place a weight 201B on the analytical balance 101 of the weighing subsystem, and fix the sample 401 to be measured through the cable 201C and the pulley 201D. Add an appropriate amount of working fluid to the liquid working fluid container 301. Adjust the distance between the sample 401 and the liquid level of the working fluid through the lifting table 201A to make the liquid working fluid climb in the sample 401 to be measured. Record the mass during this process through the analytical balance 101A and transmit it to the computer 101B.
[0043] Step 2: By analyzing and processing the stored data, obtain the accurate curve of the working fluid mass change in the porous medium during the flow performance test of the porous material in Example 2. (As Figure 6 shown). Through Equation 2, the intercept is obtained as C2·K, and the slope is C1·K / R eff , and K is obtained. Then, substitute the values of C1 and C2 into the intercept and slope to obtain K, K / R eff and R eff and other key flow performance parameters.
[0044] As a reliability verification, in software with the ability to calculate mathematical equations, according to the extracted key flow performance parameters, calculate the theoretical curve of the flow performance parameters and compare it with the measured curve to verify the accuracy of the measurement results in Example 2 (as Figure 6 shown). In addition, the data of Example 1 and Example 2 basically coincide, which also shows that the device with different overall structures has the same effect.
[0045] Example 3: Use the Figures 1-5 shown device to measure the working fluid transport performance and flow performance of the heat pipe wick.
[0046] Step 1: Cut off the encapsulation heads at both ends of the sample to be tested 401 (here it is a heat pipe).
[0047] Step 2: Fix the sample to be tested 401 on the iron stand 201B of the fixed sub-system for the sample to be tested shown in Figure 1 . Add an appropriate amount of working fluid to the liquid working fluid container 301, and adjust the distance between the sample 401 and the liquid level of the working fluid through the lifting platform 201A to make the liquid working fluid climb in the sample 401 to be tested. Record the mass during this process with the analytical balance 101A and transmit it to the computer 101B.
[0048] Step 3: By analyzing and processing the stored data, obtain the accurate curve of the working fluid mass change in the porous medium during the flow performance test of the porous material in Example 3 (as Figure 7 shown). Through Equation 2, the intercept is obtained as C2·K, and the slope is C1·K / R eff , and K is obtained. Then, substitute the values of C1 and C2 into the intercept and slope to obtain K, K / R eff and R eff and other key flow performance parameters.
[0049] As a reliability verification, in software with the ability to calculate mathematical equations, according to the extracted key flow performance parameters, calculate the theoretical curve of the flow performance parameters and compare it with the measured curve to verify the accuracy of the measurement results in Example 3 (as Figure 7 shown).
[0050] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0051] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.
Claims
1. A test device for the working fluid transport performance inside a porous material, characterized in that, It consists of a fixed subsystem, a liquid working medium container, and a weighing subsystem. The transport performance of the working medium in the porous material is extracted by real-time monitoring of the mass change of the liquid working medium in the porous material.
2. The testing device for the working medium transport performance inside a porous material according to claim 1, wherein, The weighing subsystem has a real-time response function, so as to accurately measure the mass of the working medium in the porous material at the current moment.
3. The weighing device according to claim 2, wherein The weighing device of the weighing subsystem includes, but is not limited to, mass measurement devices such as balances and scales, mechanical property measurement devices such as pressure sensors, or optical weighing devices based on optical reflection and deformation, preferably an analytical balance. Preferably, the weighing subsystem is also equipped with a printing function to print out the data; or preferably, the weighing subsystem has a communication port connected to the data acquisition module to transmit the acquired mass data to devices or modules such as a data acquisition computer or a single-chip microcomputer.
4. A testing device for the working medium transport performance inside a porous material according to claim 1, characterized in that The fixed subsystem for the sample to be measured is a system for fixing and adjusting the distance between the sample to be measured and the weighing device.
5. The fixed subsystem for the sample to be measured according to claim 4 can be composed of one or more devices. For example, a combined device of a lifting table and an iron stand can be used in the laboratory, and a specific fixing device can be designed in industry. The adjustment of the distance can be manual or by automatic control.
6. The testing device for the working fluid transport performance inside a porous material according to claim 1, wherein, The working medium container is a container that can hold the liquid working medium. As long as one end of the sample to be measured can touch the liquid level of the working medium in the container, its shape, size, and material are not limited.
7. A method for measuring the transport performance of the working medium in the porous material is carried out on the device for measuring the transport performance of the working medium in the porous material according to claim 1. The specific process is as follows: S1: Fix the sample to be measured in the fixed subsystem for the sample to be measured, add an appropriate amount of working medium to the liquid working medium container, adjust the distance between the sample and the liquid level of the working medium, so that the liquid working medium climbs in the sample to be measured. Record the mass during this process. S2: According to Equation 2, perform a linear fit on dm / dt and 1 / m. In the formula: m is the mass of the liquid inhaled by the porous material, t is the time, Reff and K are the effective capillary radius and permeability of the porous material respectively, and C1 and C2 are two coefficients related to the porous structure and the physical properties of the working medium. The intercept is C2·K and the slope is C1·K / R eff , and K is obtained. Then, substitute the values of C1 and C2 into the intercept and slope to obtain K and K / R eff and R eff and other key flow performance parameters. If higher precision is required, an inertial force term can be added to Equation 2 S3: Optionally, according to Equation 3, obtain another set of arrays Δp that are commonly used to characterize flow performance c ·K, and further obtain Δp from the value of K c . where: Δp c is the capillary force of the capillary structure.