CN117589649A - Method for measuring air permeability of porous sheet - Google Patents
Method for measuring air permeability of porous sheet Download PDFInfo
- Publication number
- CN117589649A CN117589649A CN202311550632.0A CN202311550632A CN117589649A CN 117589649 A CN117589649 A CN 117589649A CN 202311550632 A CN202311550632 A CN 202311550632A CN 117589649 A CN117589649 A CN 117589649A
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- China
- Prior art keywords
- sample
- air permeability
- porous sheet
- gas
- air
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- 230000035699 permeability Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000003068 static effect Effects 0.000 claims description 4
- 238000009423 ventilation Methods 0.000 claims description 2
- 238000012360 testing method Methods 0.000 abstract description 9
- 238000007789 sealing Methods 0.000 abstract description 7
- 238000013461 design Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 16
- 229910052799 carbon Inorganic materials 0.000 description 16
- 238000009792 diffusion process Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical group C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Fluid Mechanics (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measuring Volume Flow (AREA)
Abstract
The invention relates to a method for measuring the air permeability of a porous sheet, which comprises the following steps: cutting the porous sheet into a ring-shaped sample, and placing the ring-shaped sample between two flat plates, wherein one flat plate is provided with no hole, the other flat plate is provided with a hole, and the projection surface of the inner circle of the sample completely covers the hole; measuring the thickness of the sample while clamped; aerating the hole to measure the pressure drop or flow rate of the gas passing through the sample; the air permeability value of the porous sheet was calculated from the measured value. Compared with the prior art, the invention has the advantages that the sample is placed between two flat plates with one hole for air permeability test, so that the difficulty of sealing design of the clamp is reduced; the load is applied to the two flat plates, so that the air permeability of the porous sheet under different ballast force conditions can be effectively obtained; the method for controlling the variables is adopted to measure the air pressure drop or the air flow rate generated when the air passes through the sample, and the method can be selected according to the actual equipment condition, and has the advantages of wide application range and the like.
Description
Technical Field
The present invention relates to a method for measuring air permeability of a porous sheet, and more particularly, to a method for measuring air permeability of a porous sheet.
Background
Carbon paper is a carbon fiber product, is commonly used as a gas diffusion layer, has wide application in proton exchange membranes of fuel cells, is one of indispensable materials of hydrogen fuel cells, and has the main functions of mass transfer, electric conduction, heat transfer, support of catalytic layers and the like, and the air permeability of the carbon paper can greatly influence the performance of the product to which the carbon paper is applied. Currently, the air permeability of carbon paper is measured by mainly fixing the carbon paper by a specific clamp and measuring the air flowing from one side of the carbon paper to the other side; on the one hand, when a non-sealing type clamp is adopted, partial gas cannot be prevented from flowing out from the side surface of the carbon paper, so that the calculation of the air permeability is larger; on the other hand, if a sealing type jig is used, it is difficult to effectively measure the air permeability of the carbon paper under different ballast forces because part of the load is borne by the sealing structure.
Through retrieval, application publication number CN103852406A discloses a carbon paper/diffusion layer air permeability test device and a use method thereof, and specifically discloses: 1) Placing a sample to be tested between a pair of laminated flaky plates with through holes in the middle, pressing the flaky plates around the sample to form an assembly, clamping the assembly between two first clamps and two second clamps which are buckled oppositely, and assembling a test pool; 2) Installing the test pool on a test device; 3) And introducing tested gas into the gas inlet of the first clamp of the test tank, measuring the gas flow of the test tank at the outlet of the second clamp by using a gas flowmeter, testing the pressure difference by using a micro pressure difference meter, and further calculating to obtain the air permeability of the sample to be tested.
However, the conventional patent also fails to solve the problem that it is difficult to effectively measure the air permeability of the carbon paper under different ballast forces because a partial load is borne by the sealing structure. In summary, how to accurately measure the air permeability of the carbon paper is a technical problem to be solved.
Disclosure of Invention
The invention aims to overcome the defect of inaccurate measurement of the air permeability of the carbon paper in the prior art and provides an air permeability measuring method of a porous sheet.
The aim of the invention can be achieved by the following technical scheme:
according to an aspect of the present invention, there is provided a method for measuring air permeability of a porous sheet, the method specifically comprising the steps of:
step S1, cutting a porous sheet into a ring-disk-shaped sample;
s2, placing a sample between two flat plates, wherein one flat plate is provided with no hole, the other flat plate is provided with a hole, and the projection surface of the inner circle of the sample completely covers the hole;
s3, measuring the thickness of the sample clamped by the two flat plates;
s4, ventilation is carried out to the holes of the flat plate, and the air pressure drop generated when the air passes through the sample or the air flow of the air passing through the sample is measured;
and S5, calculating the air permeability value of the porous sheet according to the thickness, the air pressure drop and the air flow of the sample.
In a preferred embodiment, in the step S3, a static load is applied to the two plates when the two plates clamp the sample.
In a preferred embodiment, in the step S3, when the two plates clamp the sample, a dynamic load is applied to the two plates.
As a preferable technical scheme, in the step S4, the flow rate of the gas is fixed when the gas pressure drop generated when the gas passes through the sample is measured; the gas flow rate of the gas through the sample is measured while maintaining the pressure drop of the gas as it passes through the sample.
As a preferable technical scheme, the inner radius of the annular disk-shaped sample is defined as r i An outer radius r o The thickness in the unstressed state is h.
As a preferable technical scheme, the relation between the inner radius and the outer radius is r o >r i The method comprises the steps of carrying out a first treatment on the surface of the The relation between the inner radius and the thickness is thatr i >h, performing H; the relation between the outer radius and the thickness is r o >h。
As a preferable technical scheme, the air permeability in the step S5Where Q is the gas flow, μ is the gas viscosity coefficient, ΔP is the gas pressure drop, and δ is the thickness of the sample when clamped by the two plates.
As a preferable technical scheme, the two flat plates have the same shape.
As a preferred technical solution, the hole is located at the center of the plate.
As a preferable technical scheme, the holes are concentric with the inner circle of the sample.
Compared with the prior art, the invention has the following beneficial effects:
1) According to the invention, the sample is placed between two flat plates with one hole, and the air permeability test is carried out, so that the problem of inaccurate air permeability measurement value caused by air leakage of the side surface of the sheet can be effectively avoided;
2) The gas flows in from the inner circle of the sample, flows out after flowing through the sample, has no special sealing requirement on the clamp, and can effectively reduce the difficulty of sealing design on the clamp;
3) When the two flat plates clamp the sample, static load or dynamic load is applied to the two flat plates, so that the air permeability of the porous sheet under different ballast force conditions can be effectively obtained;
4) The invention adopts a variable control method to measure the flow of the gas which is fixedly introduced when the gas passes through the pressure drop generated by the sample; when the gas flow of the gas passing through the sample is measured, the gas pressure drop generated when the gas passes through the sample is kept unchanged, the gas pressure drop can be selected according to the actual equipment condition, and the application range is wide.
Drawings
FIG. 1 is a flow chart of a method for measuring air permeability of a porous sheet according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
As shown in fig. 1, the present invention provides a method for measuring air permeability of a porous sheet, comprising the steps of:
1) Cutting the porous sheet into a disk-shaped sample, wherein the disk-shaped sample has an inner radius r i An outer radius r o The thickness in the unstressed state is h, and satisfies r o >r i ，r i >h，r o >h；
2) Selecting two flat plates with smooth surfaces, wherein one flat plate is provided with no holes, and the other flat plate is provided with holes with the diameter of r p The method comprises the steps of carrying out a first treatment on the surface of the The flat plates can be identical in shape, the holes can be arranged in the center, so that the paths through which the gas flows are identical, and the variables can be controlled conveniently;
3) Placing the annular disk-shaped sample between two flat plates to satisfy r p <r i When the device is placed, the projection surface of the middle hole of the sample is ensured to completely cover the hole area of the flat plate, the holes and the inner circle of the annular disk-shaped sample are preferably concentric, so that the paths through which the gas flows are completely the same, and the variables are convenient to control;
4) Under the condition that the two flat plates clamp the sample, static load or dynamic load is uniformly loaded on the two flat plates;
5) Measuring the thickness delta of the sample under the condition that the two flat plates clamp the sample;
6) Aerating the holes of the flat plate, and measuring the air pressure drop delta P generated when the air passes through the sample under the condition of fixing the flow rate of the aerated air; measuring the gas flow Q of the gas passing through the sample under the condition that the gas pressure drop generated when the gas passes through the sample is kept unchanged;
7) The air permeability value eta of the porous sheet is calculated according to the thickness delta, the air pressure drop delta P and the air flow Q of the sample, and the calculation formula is as follows:
where μ is the gas viscosity coefficient, and changes with temperature and is an inherent property of the gas introduced.
In the step 6), the gas flows from the middle to the outer ring of the sample in a sample mode, which is different from the mode that a specific clamp is adopted to fix the carbon paper and the gas flows from one surface to the other surface of the carbon paper to measure, so that the problem of inaccurate calculation of the gas permeability caused by the outflow of the gas from the side surface of the carbon paper can be avoided; in the step 4), the load is uniformly applied to the two flat plates, so that the air permeability of the carbon paper under different ballasts can be effectively tested.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. A method for measuring the air permeability of a porous sheet, comprising the steps of:
step S1, cutting a porous sheet into a ring-disk-shaped sample;
s2, placing a sample between two flat plates, wherein one flat plate is provided with no hole, the other flat plate is provided with a hole, and the projection surface of the inner circle of the sample completely covers the hole;
s3, measuring the thickness of the sample clamped by the two flat plates;
s4, ventilation is carried out to the holes of the flat plate, and the air pressure drop generated when the air passes through the sample or the air flow of the air passing through the sample is measured;
and S5, calculating the air permeability value of the porous sheet according to the thickness, the air pressure drop and the air flow of the sample.
2. The method according to claim 1, wherein in the step S3, a static load is applied to the two flat plates when the two flat plates clamp the sample.
3. The method according to claim 1, wherein in the step S3, a dynamic load is applied to the two flat plates when the two flat plates clamp the sample.
4. The method according to claim 1, wherein in the step S4, the flow rate of the introduced gas is fixed when the gas pressure drop generated when the gas passes through the sample is measured; the gas flow rate of the gas through the sample is measured while maintaining the pressure drop of the gas as it passes through the sample.
5. The method for measuring air permeability of a porous sheet according to claim 1, wherein an inner radius of the annular disk-like sample is defined as r i An outer radius r o The thickness in the unstressed state is h.
6. The method for measuring air permeability of a porous sheet according to claim 5, wherein the relationship between the inner radius and the outer radius is r o >r i The method comprises the steps of carrying out a first treatment on the surface of the The relation between the inner radius and the thickness is r i >h, performing H; the relation between the outer radius and the thickness is r o >h。
7. The method for measuring air permeability of a porous sheet according to claim 5, wherein the air permeability in step S5Where Q is the gas flow, μ is the gas viscosity coefficient, ΔP is the gas pressure drop, and δ is the thickness of the sample when clamped by the two plates.
8. The method for measuring air permeability of a porous sheet according to claim 1, wherein the two flat plates are identical in shape.
9. The method of claim 1, wherein the hole is located at the center of the plate.
10. The method of claim 1, wherein the holes are concentric with the inner circle of the sample.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311550632.0A CN117589649A (en) | 2023-11-20 | 2023-11-20 | Method for measuring air permeability of porous sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311550632.0A CN117589649A (en) | 2023-11-20 | 2023-11-20 | Method for measuring air permeability of porous sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117589649A true CN117589649A (en) | 2024-02-23 |
Family
ID=89909318
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311550632.0A Pending CN117589649A (en) | 2023-11-20 | 2023-11-20 | Method for measuring air permeability of porous sheet |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117589649A (en) |
-
2023
- 2023-11-20 CN CN202311550632.0A patent/CN117589649A/en active Pending
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