Gas flow measurement system and method based on atomic-scale smooth wall surface nano channel

Abstract

The invention discloses a gas flow measurement system and method based on an atomic-scale smooth wall surface nanometer channel. The system mainly comprises a high-purity gas source, the nanometer channel, a valve, a pipeline and the like. Neutral gas molecules or charged ions are introduced into the system inlet, and the inlet pressure is adjusted, thereby providing precise neutral gas flow or ion flow. The technique is based on the latest frontier theoretical outcome of the current traffic measurement. The invention discloses a gas flow system based on an atomic-scale smooth wall surface nano channel. The gas flow system mainly comprises a high-purity gas source, the nano channel, a valve, a pipeline and the like. The method is characterized in that gas flow measurement based on the atomic-scale smooth wall surface nano channel is carried out. Based on a new gas transportation theory of an atomic-scale smooth wall surface nano channel, a new means of gas flow is established.

Description

Technical Field

[0001] The invention relates to a gas flow measurement system and method based on an atomic-level smooth-wall nanochannel, belonging to the frontier technical field of flow measurement. Background Art

[0002] In the field of vacuum technology, Knudsen theory is based on a key assumption: gas molecules are diffusely reflected on the channel wall. However, with the emergence of new materials and the advancement of observation technology, studies have found that on certain specific walls, especially on the surfaces of atomically smooth materials, gas molecules are more inclined to undergo specular reflection. This specular reflection phenomenon causes the gas flow through nanochannels to be significantly higher than the value predicted by Knudsen theory. In recent years, a series of innovative results have been achieved in the theory of gas transport on atomically smooth walls such as graphene. In particular, an innovative research idea has been proposed to reduce gas dissipation flow by specular reflection, and a universal theory has been established to apply to a wider range of channel walls, especially to accurately quantify the gas flow in channels with atomically smooth walls such as graphene.

[0003] In gas flow calibration technology, small holes or small aperture channels are usually used as flow limiting elements for standard flow. Due to the limitation of processing and manufacturing capabilities, the aperture scale is mostly above the micron level, and the gas molecules and the inner wall of the channel undergo non-specular scattering. At this time, the Knudsen theory is applicable. However, with the emergence of new materials and the advancement of observation technology, the aperture scale and wall roughness have shown nanometer and mirror levels respectively, and the Knudsen theoretical value deviates seriously from the actual measured value. In recent years, a new theory of gas transport with atomically smooth walls has been developed, which provides theoretical guidance for solving the problem of accurate measurement of gas flow in this area.

[0004] Based on the above objective conditions, a gas flow system based on atomically smooth-walled nanochannels was established, which promoted the innovative development of gas flow measurement technology. Summary of the invention

[0005] The present invention provides a gas flow measurement system and method based on an atomic-level smooth-wall nanochannel.

[0006] The technical solution of the present invention is:

[0007] The present invention is mainly based on the gas flow rate of atomic-level smooth-walled nanochannels to achieve accurate measurement of gas flow rate. The specific technical solution to achieve the purpose of the present invention is:

[0008] A gas flow measurement system based on an atomic-level smooth-wall nanochannel, the measurement system comprising a high-purity gas source, a first valve, a pressure gauge, a nanochannel, a second valve, a vacuum gauge, a vacuum chamber, a third valve and a vacuum pump;

[0009] The high-purity gas source is connected to the vacuum chamber through a first pipeline, a first valve, a pressure gauge, a nanochannel and a second valve are sequentially arranged on the first pipeline, and a vacuum gauge is provided on the vacuum chamber;

[0010] The vacuum chamber is communicated with the vacuum pump through a second pipeline, and a third valve is arranged on the second pipeline.

[0011] The structure of the nanochannel is a single channel.

[0012] The structure of the nanochannel is a channel combination structure composed of multiple single channels.

[0013] The left end of the nanochannel is a vacuum-sealed air inlet end, and the right end of the nanochannel is a vacuum-sealed air outlet end.

[0014] When a high-purity gas source is introduced, the high-purity gas source enters the nanochannel through the vacuum-sealed gas inlet end, then leaves the nanochannel through the vacuum-sealed gas outlet end, and finally enters the vacuum chamber.

[0015] The cross section of a single channel of the nanochannel is rectangular, triangular or circular.

[0016] A method for measuring gas flow based on atomically smooth wall nanochannels, the method comprising the following steps:

[0017] The first step is to start the vacuum pump, open the second valve, the third valve, the pressure gauge, and the vacuum gauge to evacuate the vacuum chamber;

[0018] The second step is to close the third valve and open the first valve, so that the high-purity gas source enters the vacuum chamber through the nanochannel;

[0019] The third step is to record the pressure gauge reading p in ;

[0020] The fourth step is to measure the tangential momentum adaptation coefficient f and Knudsen transmission probability α of the nanochannel K ;

[0021] Step 5: According to the indication p obtained in step 3 in And the tangential momentum adaptation coefficient f and Knudsen transmission probability α obtained in the fourth step K The nanochannel outlet flow rate Q is calculated by the following formula out :

[0022]

[0023] Among them, Q in is the flow rate injected into the nanochannel inlet; f is the tangential momentum adaptation coefficient; α Krepresents the Knudsen transmission probability; A is the cross-sectional area of ​​the nanochannel entrance; R is the molar gas constant; T is the gas temperature; M is the molar mass of the gas molecule; p in is the nanochannel inlet pressure, D is the nanochannel cross-sectional diameter, and L is the nanochannel length.

[0024] The invention discloses a gas flow measurement system and method based on an atomic-level smooth-wall nanochannel. The system mainly includes a high-purity gas source, a nanochannel, a valve, a pipeline, etc. Neutral gas molecules or charged ions are introduced into the system inlet, and the inlet pressure is adjusted to provide an accurate neutral gas flow or ion flow. The technology is based on the latest cutting-edge theoretical achievements of current flow measurement. A gas flow system based on an atomic-level smooth-wall nanochannel mainly includes a high-purity gas source, a nanochannel, a valve, a pipeline, etc. It is characterized in that the gas flow measurement based on the atomic-level smooth-wall nanochannel. A new means of gas flow is established based on the new theory of gas transport of atomic-level smooth-wall nanochannels. When introducing a high-purity gas source, a flow channel structure with an atomic-level smooth-wall nanochannel as a key component is designed. The structure of the nanochannel can be a single channel or a channel combination structure composed of multiple single channels. The two ends of the nanochannel are respectively a vacuum-sealed air inlet end and an air outlet end structure. The cross-sectional size of a single channel is nanometer-level or angstrom-level.

[0025] The beneficial effects of the present invention compared with the prior art are:

[0026] (1) This invention is a new technology based on the latest theory of gas transport in atomically smooth-walled nanochannels, which overcomes the application limitations of traditional theories in the fields of membrane separation, nanocatalysis, shale gas development, etc.

[0027] (2) This invention is the latest innovative achievement of the cross-integration of vacuum technology and new materials science.

[0028] (3) This invention expands the cognitive boundaries of vacuum science and solves the problem that the actual measured value of the flow in a smooth-walled nanochannel dominated by mirror reflection deviates greatly from the Knudsen theoretical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the system structure of the present invention, wherein 1-high purity gas source; 2, 5, 8-valves; 3-pressure gauge; 4-nanochannel; 6-vacuum gauge; 7-vacuum chamber; 9-vacuum pump. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.

[0031] Example

[0032] like Figure 1 As shown, a gas flow measurement system based on atomically smooth-walled nanochannels comprises a high-purity gas source 1, a first valve 2, a pressure gauge 3, a nanochannel 4, a second valve 5, a vacuum gauge 6, a vacuum chamber 7, a third valve 8 and a vacuum pump 9;

[0033] The high-purity gas source 1 is connected to the vacuum chamber 7 through a first pipeline, on which a first valve 2, a pressure gauge 3, a nanochannel 4 and a second valve 5 are sequentially arranged, and the vacuum chamber 7 is provided with a vacuum gauge 6;

[0034] The vacuum chamber 7 is connected to the vacuum pump 9 through a second pipeline, and a third valve 8 is provided on the second pipeline;

[0035] The nanochannel 4 has a single-channel circular cross section;

[0036] A method for measuring gas flow based on atomically smooth wall nanochannels, the method comprising the following steps:

[0037] The first step is to start the vacuum pump, open the second valve, the third valve, the pressure gauge, and the vacuum gauge to evacuate the vacuum chamber;

[0038] The second step is to close the third valve and open the first valve, so that the high-purity gas source enters the vacuum chamber through the nanochannel;

[0039] The third step is to record the pressure gauge reading p in ;

[0040] The fourth step is to measure the tangential momentum adaptation coefficient f and Knudsen transmission probability α of the nanochannel K ;

[0041] Step 5: According to the indication p obtained in step 3 in And the tangential momentum adaptation coefficient f and Knudsen transmission probability α obtained in the fourth step K The nanochannel outlet flow rate Q is calculated by the following formula out :

[0042]

[0043]

[0044] Among them, Q in is the flow rate injected into the nanochannel inlet; f is the tangential momentum adaptation coefficient; α K represents the Knudsen transmission probability; A is the cross-sectional area of ​​the nanochannel entrance; R is the molar gas constant; T is the gas temperature; M is the molar mass of the gas molecule; p in is the nanochannel inlet pressure, D is the nanochannel cross-sectional diameter, and L is the nanochannel length.

[0045] The specific measurement process is:

[0046] 1. Turn on the vacuum pump 9, open valve 5, valve 8, pressure gauge 3, and vacuum gauge 6, and evacuate the vacuum chamber 7 to 10 Pa.

[0047] 2. Close valve 8, open valve 2, and introduce high-purity argon gas source 1.

[0048] 3. Record the value p of the pressure gauge 3 in =1.5×10 5 Pa.

[0049] 4. According to the graphene nanochannel property data, f=0.01 was measured.

[0050] 5. Set the cross-sectional diameter D = 6nm and the channel length L = 100nm to obtain α K =0.0712.

[0051] 6. Based on the above data, the nanochannel outlet flow rate Q is measured out =5.34×10 3 mol / s.

[0052] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A gas flow measurement system based on atomically smooth wall nanochannels, characterized in that: The measuring system includes a high-purity gas source, a first valve, a pressure gauge, a nanochannel, a second valve, a vacuum gauge, a vacuum chamber, a third valve and a vacuum pump; The high-purity gas source is connected to the vacuum chamber through a first pipeline, a first valve, a pressure gauge, a nanochannel and a second valve are sequentially arranged on the first pipeline, and a vacuum gauge is provided on the vacuum chamber; The vacuum chamber is communicated with the vacuum pump through a second pipeline, and a third valve is arranged on the second pipeline.

2. A gas flow measurement system based on atomically smooth wall nanochannel according to claim 1, characterized in that: The structure of the nanochannel is a single channel.

3. The gas flow measurement system based on atomically smooth wall nanochannel according to claim 1, characterized in that: The structure of the nanochannel is a channel combination structure composed of multiple single channels.

4. The gas flow measurement system based on atomically smooth wall nanochannel according to claim 1, characterized in that: The left end of the nanochannel is a vacuum-sealed air inlet end, and the right end of the nanochannel is a vacuum-sealed air outlet end.

5. A gas flow measurement system based on atomically smooth wall nanochannel according to claim 4, characterized in that: When a high-purity gas source is introduced, the high-purity gas source enters the nanochannel through the vacuum-sealed gas inlet end, then leaves the nanochannel through the vacuum-sealed gas outlet end, and finally enters the vacuum chamber.

6. The gas flow measurement system based on atomically smooth wall nanochannel according to claim 1, characterized in that: The cross section of a single channel of the nanochannel is rectangular, triangular or circular.

7. A method for measuring gas flow based on atomically smooth wall nanochannels, characterized in that The steps of the method include: The first step is to start the vacuum pump, open the second valve, the third valve, the pressure gauge, and the vacuum gauge to evacuate the vacuum chamber; The second step is to close the third valve and open the first valve, so that the high-purity gas source enters the vacuum chamber through the nanochannel; The third step is to record the pressure gauge reading p in ; The fourth step is to measure the tangential momentum adaptation coefficient f and Knudsen transmission probability α of the nanochannel K ; Step 5: According to the indication p obtained in step 3 in And the tangential momentum adaptation coefficient f and Knudsen transmission probability α obtained in the fourth step K The nanochannel outlet flow rate Q is calculated by the following formula out : Among them, Q in is the flow rate injected into the nanochannel inlet; f is the tangential momentum adaptation coefficient; α K represents the Knudsen transmission probability; A is the cross-sectional area of ​​the nanochannel entrance; R is the molar gas constant; T is the gas temperature; M is the molar mass of the gas molecule; p in is the nanochannel inlet pressure, D is the nanochannel cross-sectional diameter, and L is the nanochannel length.

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