High-flux Knudsen pump based on macro-micro multichannel coupling and design method thereof

Abstract

The invention provides a high-flux Knudsen pump based on macro-micro multi-channel coupling and a design method thereof, and relates to the technical field of micro-nano scale rarefied gas transportation and micro gas pump devices. According to the Knudsen pump, a plurality of parallel and identical micro-channels are connected to a macro-channel in series, a linearly-rising temperature gradient exists along the wall faces of the micro-channels, a linearly-falling temperature gradient exists along the wall faces of the macro-channels, the low-temperature ends of the micro-channels are gas input ends, and the high-temperature ends of the micro-channels are directly connected with the high-temperature ends of the macro-channels. And the low-temperature end of the macro channel is a gas output end. According to the method, the series-parallel hybrid topology of the macro channel and the multiple micro channels can be definitely limited, a geometric parameter design principle is given, and the critical scale ratio acrit is definitely defined, so that whether the resistance of the macro channel can be ignored or not is judged, whether parallel expansion can reach ideal linear expandability or not is judged, and the total mass flow rate is improved. And the capability of maintaining relatively high pressure difference is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-nano scale rarefied gas transport and micro gas pump device, and particularly relates to a high-throughput Knudsen pump based on macro-micro multi-channel coupling and a design method thereof. BACKGROUND

[0002] The existing micro gas pumps mostly adopt mechanical driving forms, for example, micro piston pumps, diaphragm pumps and the like. Such pumps have the following problems in micro-nano scale applications: reliability and service life problems caused by mechanical moving parts, including wear, fatigue, seal failure and the like; vibration and noise problems, which have adverse effects on high-precision sensors or micro analysis systems; power consumption and integration difficulties, which are not easy to realize monolithic integration in lab-on-chip and MEMS systems. The Knudsen pump is a solid gas pump that realizes gas transport by using thermal transpiration (also known as thermal creep). In the rarefied gas condition (for example, medium or large Kn number), a temperature gradient is applied along the wall surface of the channel, which can induce the transport of gas from the cold end to the hot end, and even a net mass flow can be generated under the condition of no external pressure difference. In the related art, the research on the Knudsen pump mainly focuses on: thermal transpiration flow in a single long straight micro channel; thermal driven flow in special geometric channels such as curved and zigzag channels; multi-stage cascade structure for improving compression ratio; porous / multi-capillary structure for improving volume flow. However, the existing research mostly regards each channel as independent, assumes that the inlet and outlet conditions of each channel do not affect each other in the multi-channel structure, and does not fully consider the following problems: when multiple micro channels are connected through a shared macro channel (or a flow collecting cavity), how the viscous pressure drop in the macro channel is fed back to each micro channel; when multiple channels are connected in parallel, the scaling relationship between the total mass flow and the mass flow of a single channel with the number of channels Y; the influence of the ratio a=R / r of the macro channel radius to the micro channel radius on the scalability of the multi-channel, so there are problems such as lack of design criteria for the macro-micro scale ratio a and the parallel number Y, lack of unified device design for the multi-micro channel-macro channel coupling structure, and lack of structure design that can improve the total mass flow while maintaining high pressure difference capability, which makes it difficult to select a reasonable combination of a and Y, to realize the linear parallel gain close to the ideal while ensuring the compactness of the device, and limits the development of the Knudsen pump to the direction of high-throughput and modular expansion.

[0003] The information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0004] The application provides a high-flux Knudsen pump based on macro-micro multi-channel coupling and a design method thereof, and can solve the technical problem that a reasonable combination of a and Y is difficult to select in the prior art, while ensuring compactness of the device, and realizing nearly ideal linear parallel gain.

[0005] According to a first aspect of the application, a high-flux Knudsen pump based on macro-micro multi-channel coupling is provided, comprising,

[0006] a plurality of micro-channels with the same geometric parameters arranged in parallel, the low-temperature end of the micro-channels being a gas input end, the high-temperature end of the micro-channels being a gas output end, and the high-temperature end of the micro-channels being connected to a macro-channel;

[0007] a macro-channel, the high-temperature end of the macro-channel being a gas input end, the low-temperature end of the macro-channel being a gas output end, and the high-temperature end of the macro-channel being connected to the micro-channels;

[0008] wherein the micro-channels and the macro-channel are integrally formed in the same micron-scale structure, the high-temperature end of the micro-channels directly transitions to the high-temperature end of the macro-channel in the axial direction, and the two constitute an integrated continuous flow channel structure. The gas entering the macro-channel from the micro-channels does not need to pass through an independent connecting member or a confluence cavity, thereby realizing continuous and uninterrupted fluid transport.

[0009] In the specification, 'connected' refers to a connection relationship in which the micro-channels and the macro-channel are directly communicated in structure and constitute a continuous fluid channel, unless otherwise specified. The connection relationship can be realized by integral molding or an equivalent integrated manner.

[0010] wherein the macro-channel radius R and the micro-channel radius r satisfy R=ar, a is a scale ratio, and the scale ratio a satisfies a≥20, so that the equivalent viscous resistance of the macro-channel is significantly reduced relative to the resistance of a single micro-channel, thereby making the flow state of each micro-channel in the parallel structure mainly determined by the respective geometric parameters and boundary conditions, the performance of a single micro-channel remains basically unchanged when the number of parallel channels changes, each micro-channel can be approximately regarded as working independently under the same boundary conditions, and the coupling effect between the micro-channels is effectively weakened or can be ignored in engineering.

[0011] In an embodiment of the application, the micro-channel length L1 and the macro-channel length L2 are equal, and in this embodiment, L1=L2=10r, for illustrating and calculating the channel structure characteristics. The length values do not constitute a limitation on the technical solutions of the application.

[0012] According to the application, the temperature at the input end of the micro-channel is Tc=300K; the temperature at the input end of the macro-channel is Th=400K; the micro-channel wall temperature linearly increases from Tc to Th along the axial direction; and the macro-channel wall temperature linearly decreases from Th to Tc along the axial direction.

[0013] According to the application, the scale ratio a belongs to a first optimal interval of [50, 200], the micro-channel number Y belongs to a second optimal interval of [5, 10], and the structure is compact.

[0014] According to the application, when working in an open system mode, the maximum pressure difference between the input end of the micro-channel and the output end of the macro-channel is 0, and the mass flow rate of the gas reaches a maximum value; when working in a closed system mode, the pressure difference between the input end of the micro-channel and the output end of the macro-channel reaches a maximum pressure difference, and the mass flow rate of the gas is 0; when working in an intermediate mode, the mass flow rate of the gas is in an interval between 0 and the maximum value of the mass flow rate, and the pressure difference between the input end of the micro-channel and the output end of the macro-channel is in an interval between 0 and the maximum pressure difference.

[0015] According to the application, the parallel efficiency η is determined according to the formula:

[0016] , wherein η is the parallel efficiency (%); Y is the micro-channel number; Q is the total mass flow rate of the device when the micro-channel number is Y; Qmax is the maximum mass flow rate of a single micro-channel of the device when the micro-channel number is Y; Qmax1 is the maximum mass flow rate of the device when the micro-channel number is 1; and a is the scale ratio.

[0017] The relationship between the parallel efficiency and the scale ratio a and the micro-channel number Y is determined.

[0018] According to the relationship between the parallel efficiency and the scale ratio a and the micro-channel number Y, the first optimal interval and the second optimal interval are determined.

[0019] According to the application, the gas is a rare gas, the rare gas is helium, and the inlet pressure of the input end of the micro-channel is in an interval of [0.1, 100] kPa.

[0020] According to a second aspect of the application, a high-throughput Knudsen pump design method based on macro-micro multi-channel coupling is provided, comprising,

[0021] The micro-channels are provided, the number of the micro-channels is multiple, the geometric parameters of the micro-channels are the same, the micro-channels are arranged in parallel, the low-temperature end of the micro-channel is a gas input end, the high-temperature end of the micro-channel is a gas output end, and the high-temperature end of the micro-channel is connected with a macro-channel;

[0022] The macro-channel is provided, the high-temperature end of the macro-channel is a gas input end, the low-temperature end of the macro-channel is a gas output end, and the high-temperature end of the macro-channel is connected with the micro-channel;

[0023] ​​​Wherein, the macro-channel radius R and the micro-channel radius r satisfy R=ar, a is a scale ratio, and the scale ratio a satisfies a>=20, so that the equivalent viscous resistance of the macro-channel is significantly reduced relative to the resistance of a single micro-channel, thereby making the flow state of each micro-channel in the parallel structure mainly determined by its own geometric parameters and boundary conditions, and the performance of a single micro-channel remains basically unchanged when the number of parallel channels changes, each micro-channel can work independently under the same boundary conditions, thereby effectively reducing or engineering-negligible the coupling effect between micro-channels.

[0024] According to a third aspect of the present application, a high-throughput Knudsen pump device based on macro-micro multi-channel coupling is provided, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to execute the high-throughput Knudsen pump design method based on macro-micro multi-channel coupling.

[0025] According to a fourth aspect of the present application, a computer-readable storage medium is provided, which stores computer program instructions, and the computer program instructions are executed by a processor to implement the high-throughput Knudsen pump design method based on macro-micro multi-channel coupling.

[0026] The high-throughput Knudsen pump based on macro-micro multi-channel coupling and its design method according to the embodiments of the present application can clearly define the series-parallel mixed topology of the macro-channel and the plurality of micro-channels, give the geometric parameter design principle, and clearly define the critical scale ratio a crit , so as to determine whether the macro-channel resistance can be ignored, and further determine whether the parallel expansion can achieve ideal linear scalability, improve the total mass flow, and improve the ability to maintain a high pressure difference, thereby providing a basic structural unit for high-throughput and parallel expandable micro gas pumps. And by clearly defining the macro-channel radius, the micro-channel radius, and the scale ratio of the two, a single-stage mixed structure Knudsen pump device with predictable performance can be constructed, and when a belongs to [20, 50], the total mass flow increases approximately linearly with the number of parallel channels, which is suitable for application scenarios that require to increase the flux by parallel connection. When the input pressure is 1kPa, the maximum pressure difference can be close to the upper limit value of about 120Pa when a belongs to [50, 200], and increasing the number of micro-channels does not significantly affect the maximum pressure difference, thereby achieving the design goal of "linear increase in total flow + pressure difference maintenance". And the two-dimensional parameter space of the scale ratio and the number of micro-channels can be visualized, and the combination of a=[50, 200] and Y=[5, 10] can be selected to obtain a comprehensive optimal design window with high flux, high pressure difference, and compact structure. Further, the series-parallel mixed topology of the macro-channel and the plurality of micro-channels can be clearly defined, the geometric parameter design principle can be given, and the critical scale ratio a critThis is used to determine whether the macro channel resistance can be ignored, and then to determine whether the parallel expansion can achieve ideal linear scalability, increase the total mass flow rate, and enhance the ability to maintain a high differential pressure.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Other features and aspects of the invention will become clearer from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of a high-throughput Knudsen pump based on macro-micro multichannel coupling according to an embodiment of the present invention is shown as an example;

[0030] Figure 2 A cross-sectional schematic diagram of a high-throughput Knudsen pump based on macro-micro multichannel coupling according to an embodiment of the present invention is shown as an example;

[0031] Figure 3 An exemplary schematic diagram of the axial temperature and radius distribution of a device according to an embodiment of the present invention is shown;

[0032] Figure 4 An exemplary schematic diagram of axial pressure and temperature distribution under a typical operating mode according to an embodiment of the present invention is shown (input pressure Pi = 1 kPa).

[0033] Figure 5 An exemplary schematic diagram illustrating the variation of maximum mass flow rate and maximum pressure difference under different macro-micro scale ratios a according to an embodiment of the present invention is shown; wherein, (a) is the maximum mass flow rate calculated when Y=1, changing a=R / r(4–1000) under multiple inlet pressures Pi (0.1, 1, 10, 100 kPa). max (b) shows the calculated maximum mass flow rate at Pi = 0.1 kPa. max (c) is the maximum pressure difference ΔPmax calculated when Y=1, changing a=R / r(4–1000) under multiple inlet pressures Pi (0.1, 1, 10, 100kPa); (d) is the maximum pressure difference ΔPmax calculated when Pi=0.1kPa.

[0034] Figure 6An exemplary diagram illustrating the single-channel / total mass flow rate and parallel efficiency under different parallel numbers Y according to an embodiment of the present invention (input pressure Pi = 1 kPa); wherein, (a) is the calculation of the single-channel mass flow rate by changing the number of microchannels Y = 1–10 under the condition that a takes multiple typical values ​​(e.g., 4, 5, 20, 50, 100, 200) and the inlet pressure Pi = 1 kPa. (b) Calculate the total mass flow rate by changing the number of microchannels Y = 1–10 under the condition that a takes multiple typical values ​​(e.g., 4, 5, 20, 50, 100, 200) and the inlet pressure Pi = 1 kPa. =Y· (c) Calculate the parallel efficiency by changing the number of microchannels Y = 1–10 under the condition that a takes multiple typical values ​​(e.g., 4, 5, 20, 50, 100, 200) and the inlet pressure Pi = 1 kPa;

[0035] Figure 7 An illustrative isograph showing the combined effects of a and Y on total mass flow rate and maximum pressure difference according to an embodiment of the present invention (input pressure Pi = 1 kPa); wherein, (a) is the total mass flow rate. (b) represents the maximum pressure difference ΔP max . Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0038] Figure 1 A schematic diagram of a high-throughput Knudsen pump based on macro-micro multichannel coupling according to an embodiment of the present invention is shown, the Knudsen pump comprising:

[0039] The microchannels are multiple and have the same geometric parameters, arranged in parallel. The low-temperature end of the microchannel is the gas input end, and the high-temperature end of the microchannel is the gas output end. The high-temperature end of the microchannel is connected to the macrochannel.

[0040] A macrochannel, wherein the high-temperature end of the macrochannel is the gas input end, the low-temperature end of the macrochannel is the gas output end, and the high-temperature end of the macrochannel is connected to a microchannel;

[0041] Wherein, the radius R of the macrochannel and the radius r of the microchannel satisfy R=ar, a is the scale ratio, and the scale ratio a satisfies a≥20, so that the equivalent viscous resistance of the macrochannel is significantly reduced relative to the resistance of a single microchannel, so that the flow state of each microchannel in the parallel structure is mainly determined by its own geometric parameters and boundary conditions. When the number of parallel channels changes, the performance of a single microchannel remains basically unchanged. Each microchannel can be approximated as working independently under the same boundary conditions, thereby effectively reducing or negligible the coupling effect between microchannels in engineering.

[0042] The high-throughput Knudsen pump and its design method based on macro-micro multi-channel coupling according to embodiments of the present invention can clearly define the series-parallel hybrid topology of macro channels and multiple micro channels, provide geometric parameter design principles, and clarify the critical scale ratio α. crit This allows us to determine whether the macrochannel resistance can be ignored, and further determine whether parallel expansion can achieve ideal linear scalability, increase total mass flow rate, and enhance the ability to maintain a high differential pressure. This provides a basic structural unit for high-throughput, parallel-expandable micro gas pumps.

[0043] Example 1:

[0044] According to an embodiment of the present invention, multiple microchannels with identical geometric parameters are arranged in parallel, with the low-temperature end of the microchannel serving as the gas input end, the high-temperature end of the microchannel being connected to the high-temperature end of the macrochannel, and each microchannel having a radius of r and an axial length of L1.

[0045] Example 2:

[0046] According to an embodiment of the present invention, the high-temperature end of the macrochannel is connected to the high-temperature end of the microchannel, the low-temperature end of the macrochannel is the gas output end, and the low-temperature end of the microchannel is the gas input end. The macrochannel has a radius R = ar and a length L2.

[0047] This device has a micrometer-scale structure, and the integrated continuous flow channel can be realized through micro-nano fabrication processes. For example, photolithography combined with bonding and encapsulation can be used to form continuous hollow channels of different scales in the same substrate; or two-photon polymerization three-dimensional micro-nano printing technology can be used to directly construct an integrated continuous flow channel structure of microchannels and macrochannels. For closed or semi-closed channel structures formed by two-photon polymerization, uncured material can be removed during development and rinsing by setting channel ports and / or drainage holes, thereby obtaining a hollow and interconnected channel structure. The above processing methods are only used to illustrate the feasibility of the structure of the present invention and do not constitute a limitation on specific manufacturing processes.

[0048] Example 3:

[0049] According to an embodiment of the present invention, the macrochannel radius R and the microchannel radius r satisfy R=ar, where a is the scale ratio, and the scale ratio a satisfies a≥20. This significantly reduces the equivalent viscous drag of the macrochannel relative to the drag of a single microchannel, thereby ensuring that the flow state of each microchannel in the parallel structure is mainly determined by its respective geometric parameters and boundary conditions. The performance of a single microchannel remains essentially unchanged when the number of parallel channels changes, and each microchannel can be approximated as operating independently under the same boundary conditions. This effectively weakens or negligibly reduces the coupling effect between microchannels. For example, the microchannel radius r=5μm, the macrochannel radius R=ar, a can be between 4 and 1000, the microchannel length L1=10r, and the macrochannel length L2=10r. Furthermore, when a belongs to [20,50], the influence of the macrochannel viscous drag on the performance of a single microchannel is negligible, and the coupling effect between channels is significantly weakened or disappears.

[0050] In this way, a single-stage hybrid Knudsen pump device with predictable performance can be constructed by defining the macro-channel radius, micro-channel radius, and their scale ratio. Furthermore, when a belongs to [20,50], the total mass flow rate increases approximately linearly with the number of parallel channels, making it suitable for applications that require increasing throughput through parallel connections.

[0051] Example 4:

[0052] According to an embodiment of the present invention, the microchannel length L1 is equal to the macrochannel length L2 to form microchannel segments and macrochannel segments of equal length; and L1=L2=10r to balance the heat-driven region and the current collection region.

[0053] Example 5:

[0054] According to an embodiment of the present invention, the temperature at the input end of the microchannel is Tc = 300K; the temperature at the input end of the macrochannel is Th = 400K; the microchannel wall temperature linearly increases from Tc to Th along the axial direction, that is, there is a linearly increasing temperature gradient along the microchannel wall; the macrochannel wall temperature linearly decreases from Th to Tc along the axial direction, that is, there is a linearly decreasing temperature gradient along the macrochannel wall. For example, the temperature at the input end of the microchannel is Tc = 300K, and the temperature at the input end of the macrochannel is Th = 400K; the microchannel wall temperature linearly increases from z = 0 to z = L1 (that is, linearly increases from 300K to 400K), and the macrochannel wall temperature linearly decreases from z = L1 to z = L1 + L2 (that is, linearly decreases from 400K to 300K).

[0055] Example 6:

[0056] According to an embodiment of the present invention, the scale ratio a belongs to a first optimal range of [50, 200], the number of microchannels Y belongs to a second optimal range of [5, 10], and the structure is compact. When the scale ratio a belongs to the first optimal range of [50, 200] and the number of microchannels Y belongs to the second optimal range of [5, 10], the total mass flow rate exhibits an ideal linear growth with respect to Y, while the maximum pressure difference ΔPmax approaches the upper limit value, and the structure is compact.

[0057] In this way, when the input pressure Pi = 1 kPa, the maximum pressure difference can be close to the upper limit of about 120 Pa when a belongs to [50,200]. Increasing the number of microchannels does not significantly affect the maximum pressure difference, thus achieving the design goal of "linear increase in total flow rate + pressure difference maintenance".

[0058] Example 7:

[0059] According to an embodiment of the present invention, when operating in open system mode (i.e., maximum mass flow rate mode), the maximum pressure difference between the input end of the microchannel and the output end of the macrochannel is 0 (i.e., the inlet and outlet pressures are equal), and the gas mass flow rate reaches its maximum value, which can be obtained by solving for the maximum mass flow rate. When operating in closed system mode (i.e., maximum pressure difference mode), the gas mass flow rate is zero, and the pressure difference between the input end of the microchannel and the output end of the macrochannel reaches its maximum pressure difference, which can be obtained by solving for the maximum pressure difference. When operating in intermediate mode (i.e., intermediate operating condition), the gas mass flow rate is within the range between 0 and the maximum mass flow rate, and the pressure difference between the input end of the microchannel and the output end of the macrochannel is within the range between 0 and the maximum pressure difference, thus obtaining the complete characteristic curves of mass flow rate and pressure difference between the input end of the microchannel and the output end of the macrochannel. Based on the relationship between parallel efficiency, scale ratio a, and the number of microchannels Y, a first optimal interval and a second optimal interval are determined.

[0060] Example 8:

[0061] According to an embodiment of the present invention, the parallel efficiency η is determined according to formula (1).

[0062] (1)

[0063] Where η is the parallel efficiency (%); Y is the number of microchannels; Y represents the total mass flow rate of the device when the number of microchannels is Y. Y represents the maximum mass flow rate of a single microchannel in the device when the number of microchannels is Y. The maximum mass flow rate of the device when the number of microchannels is 1 is determined; the relationship between parallel efficiency and scale ratio a and number of microchannels Y is determined; based on the relationship between parallel efficiency and scale ratio a and number of microchannels Y, the first optimal interval and the second optimal interval are determined.

[0064] According to an embodiment of the present invention, under the condition that 'a' takes multiple typical values ​​(such as 4, 5, 20, 50, 100, 200) and the inlet pressure is equal to 1 kPa, the number of microchannels Y is changed from 1 to 10, and the mass flow rate of a single channel is calculated. With total mass flow rate =Y· Therefore, the parallel efficiency can be determined. .

[0065] Furthermore, the relationship between parallel efficiency and scale ratio *a* and the number of microchannels *Y* can be determined. Specifically, when *a* is small (e.g., 4, 5), the flow rate of a single microchannel decreases slightly with increasing *Y*, while the parallel efficiency *η* decreases significantly with *Y*. When *a* ≥ 20, the flow rate of a single microchannel remains essentially unchanged with *Y*. When *a* ≥ 50, the parallel efficiency *η* ≈ 1, and the total flow rate exhibits almost ideal linear growth with respect to *Y*. In other words, the mass flow rate of a single channel... The total mass flow rate remains essentially constant as Y increases (when a≥20). =Y· It exhibits linear growth, with the maximum pressure difference remaining largely unchanged with Y, only increasing with the increase of a and eventually tending towards saturation.

[0066] According to an embodiment of the present invention, a first optimal interval and a second optimal interval are determined based on the relationship between parallel efficiency, scale ratio *a*, and the number of microchannels *Y*. When *a* < 20, the macrochannel resistance is large, the parallel gain is significantly lower than ideal linearity, and significant coupling exists. When *a* > 50, the parallel gain is close to linear, and ΔP... max Approaching the saturation value of approximately 120 Pa, within the range of a=[50,200] and Y=[5,10], both a high total flow rate and a high ΔP can be obtained simultaneously. max And maintain a compact structure. Therefore, the first optimal interval is a belonging to [50, 200], and the second optimal interval is Y belonging to [5, 10].

[0067] In this way, the two-dimensional parameter space of scale ratio and number of microchannels can be visualized, and the combination of a=[50,200] and Y=[5,10] can be selected to obtain the comprehensive optimal design window with high throughput, high pressure difference and compact structure.

[0068] Example 9:

[0069] According to an embodiment of the present invention, the gas is a rarefied gas, specifically helium, and the inlet pressure at the cold end of the pipe is within the range of [0.1, 100], measured in kPa. Helium, as a monatomic rarefied gas, has a specific gas constant Rg = 2077 J·kg⁻¹. -1 ·K -1 Reference viscosity μ ref=1.864×10 -5 Pa·s(T) ref =273.15K), viscosity index ω=0.66.

[0070] In this way, the hybrid topology of macrochannels and multiple microchannels in series and parallel can be clearly defined, the design principles of geometric parameters can be given, and the critical scale ratio α can be clearly defined. crit This is used to determine whether the macro channel resistance can be ignored, and then to determine whether the parallel expansion can achieve ideal linear scalability, increase the total mass flow rate, and enhance the ability to maintain a high differential pressure.

[0071] The high-throughput Knudsen pump and its design method based on macro-micro multi-channel coupling according to embodiments of the present invention can clearly define the series-parallel hybrid topology of macro channels and multiple micro channels, provide geometric parameter design principles, and clarify the critical scale ratio α. crit This allows for the determination of whether macrochannel resistance can be ignored, and thus whether parallel expansion can achieve ideal linear scalability, increasing total mass flow rate and enhancing the ability to maintain a high differential pressure. This provides a basic structural unit for high-throughput, parallel-expandable micro gas pumps. A single-stage hybrid Knudsen pump device with predictable performance can be constructed by defining the macrochannel radius, microchannel radius, and their scale ratio. When a is within [20, 50], the total mass flow rate increases approximately linearly with the number of parallel channels, suitable for applications requiring increased throughput through parallel connections. When determining the first and second optimal intervals, the maximum differential pressure can approach the upper limit of approximately 120 Pa when a is within [50, 200], while increasing the number of microchannels does not significantly affect the maximum differential pressure, thus achieving the design goal of "linear increase in total flow rate + maintained differential pressure." Furthermore, the two-dimensional parameter space of the scale ratio and the number of microchannels can be visualized. A combination of a = [50, 200] and Y = [5, 10] can be selected to obtain a comprehensive optimal design window for high throughput, high differential pressure, and compact structure. Furthermore, the topology of a hybrid series-parallel structure of macrochannels and multiple microchannels can be clearly defined, and the design principles for geometric parameters can be given, as well as the critical scale ratio α can be clearly defined. crit This is used to determine whether the macro channel resistance can be ignored, and then to determine whether the parallel expansion can achieve ideal linear scalability, increase the total mass flow rate, and enhance the ability to maintain a high differential pressure.

[0072] Example 10:

[0073] Figure 3 An exemplary schematic diagram of the axial temperature and radius distribution of a device according to an embodiment of the present invention is shown.

[0074] like Figure 3As shown, the device operates under the following temperature boundary conditions: Tc = 300 K at the input of the microchannel; Th = 400 K at the input of the macrochannel; the microchannel wall temperature linearly increases from z = 0 to z = L1 (300 K → 400 K); the macrochannel wall temperature linearly decreases from z = L1 to z = L1 + L2 (400 K → 300 K). The working gas is helium, a monatomic rarefied gas with a specific gas constant Rg = 2077 J·kg⁻¹. -1 ·K -1 Reference viscosity μ ref =1.864×10 -5 Pa·s(T) ref =273.15K), viscosity index ω=0.66.

[0075] Example 11:

[0076] Figure 4 A schematic diagram illustrating the axial pressure and temperature distribution under a typical operating mode according to an embodiment of the present invention is shown.

[0077] like Figure 4 As shown, this device can operate in three modes: Open system (maximum mass flow mode): Inlet and outlet pressures are equal (Pi=Po), and the maximum mass flow rate is obtained by solving for ṁ max Closed system (maximum pressure difference mode): The mass flow rate is zero (ṁ=0), and the maximum pressure difference ΔP is obtained by solving. max =Po−Pi; Intermediate operating condition: mass flow rate between 0 and ṁ max Between 0 and ΔP max Between these points, the complete ṁ–ΔP characteristic curve is obtained. (Input pressure Pi = 1 kPa)

[0078] Example 12:

[0079] Figure 5 An exemplary schematic diagram illustrating the variation of maximum mass flow rate and maximum pressure difference under different macro-micro scale ratios α according to embodiments of the present invention is shown.

[0080] like Figure 5 As shown, when Y=1, the maximum mass flow rate is calculated under multiple inlet pressures Pi (0.1, 1, 10, 100 kPa) by changing a=R / r (4–1000). max and maximum pressure difference ΔP max The result is as follows Figure 5 As shown: ṁ max It rises rapidly as a increases, then plateaus after a ≈ 20–50; ΔP maxSimilarly, the resistance increases with increasing a and tends to plateau, indicating that the macro-channel resistance can be considered negligible after a ≥ 20–50. Therefore, a critical scale ratio a can be defined for the negligible macro-channel resistance in macro-micro hybrid structures. crit ≈20–50.

[0081] Example 13:

[0082] Figure 6 An exemplary diagram illustrating the single-channel / total mass flow rate and parallel efficiency under different parallel connection numbers Y according to embodiments of the present invention is shown. (Input pressure Pi = 1 kPa)

[0083] like Figure 6 As shown, under the condition that 'a' takes multiple typical values ​​(e.g., 4, 5, 20, 50, 100, 200) and the inlet pressure Pi = 1 kPa, the number of microchannels Y = 1–10 is changed, and the mass flow rate of a single channel ṁsingle(Y) max and the total mass flow rate ṁtotal max = Y·ṁsingle(Y) max are calculated. The parallel efficiency is defined as follows: Figure 6 As shown: when a is small (e.g., 4, 5), as Y increases, the flow rate of a single microchannel decreases slightly, and the parallel efficiency η decreases significantly with Y; when a≥20, the flow rate of a single microchannel basically does not change with Y; when a≥50, the parallel efficiency η≈1, and the total flow rate almost shows an ideal linear growth with respect to Y.

[0084] Example 14:

[0085] like Figure 7 As shown, Figure 7 An illustrative isograph showing the combined effects of a and Y on total mass flow rate and maximum pressure difference according to an embodiment of the present invention. (Input pressure Pi = 1 kPa)

[0086] like Figure 7 As shown, when a < 20, the macrochannel resistance is large, and the parallel gain is significantly lower than the ideal linearity, indicating significant coupling; when a > 50, the parallel gain is close to linear, and ΔP max The saturation value is approximately 120 Pa; within the range of a = 50–200 and Y = 5–10, both high total flow rate and high ΔP can be obtained simultaneously. max And maintain a compact structure.

[0087] Example 15:

[0088] According to one embodiment of the present invention, a high-throughput Knudsen pump device based on macro-micro multi-channel coupling is provided, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to execute the high-throughput Knudsen pump design method based on macro-micro multi-channel coupling.

[0089] According to one embodiment of the present invention, a computer-readable storage medium is provided having computer program instructions stored thereon, which, when executed by a processor, implement the high-throughput Knudsen pump design method based on macro-micro multichannel coupling.

[0090] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0091] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and any modifications or variations of the embodiments of the present invention may be made without departing from the stated principles.

Claims

1. A high-throughput Knudsen pump based on macro-micro multi-channel coupling, characterized in that, include: The microchannels are multiple and have the same geometric parameters, arranged in parallel. The low-temperature end of the microchannel is the gas input end, and the high-temperature end of the microchannel is the gas output end. The high-temperature end of the microchannel is connected to the macrochannel. A macrochannel, wherein the high-temperature end of the macrochannel is the gas input end, the low-temperature end of the macrochannel is the gas output end, and the high-temperature end of the macrochannel is connected to a microchannel; Wherein, the macrochannel radius R and the microchannel radius r satisfy R=ar, a is the scale ratio, and the scale ratio a satisfies a≥20.

2. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 1, characterized in that, The microchannel length L1 is equal to the macrochannel length L2.

3. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 1, characterized in that, The temperature at the input end of the microchannel is Tc = 300K; the temperature at the input end of the macrochannel is Th = 400K; the wall temperature of the microchannel increases linearly from Tc to Th along the axial direction; the wall temperature of the macrochannel decreases linearly from Th to Tc along the axial direction.

4. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 1, characterized in that, The scale ratio a belongs to the first optimal range of [50, 200], and the number of microchannels Y belongs to the second optimal range of [5, 10], making the structure compact.

5. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 4, characterized in that, When operating in open system mode, the maximum pressure difference between the input end of the microchannel and the output end of the macrochannel is 0, and the gas mass flow rate reaches its maximum value; when operating in closed system mode, the pressure difference between the input end of the microchannel and the output end of the macrochannel reaches its maximum pressure difference, and the gas mass flow rate is 0; when operating in intermediate mode, the gas mass flow rate is in the range between 0 and the maximum mass flow rate, and the pressure difference between the input end of the microchannel and the output end of the macrochannel is in the range between 0 and the maximum pressure difference.

6. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 4, characterized in that, According to the formula: Determine the parallel efficiency η. Where η is the parallel efficiency (%); Y is the number of microchannels; Y represents the total mass flow rate of the device when the number of microchannels is Y. Y represents the maximum mass flow rate of a single microchannel in the device when the number of microchannels is Y. This represents the maximum mass flow rate of the device when the number of microchannels is 1. Determine the relationship between parallel efficiency and scale ratio a and the number of microchannels Y; Based on the relationship between parallel efficiency, scale ratio a, and number of microchannels Y, the first and second optimal intervals are determined.

7. The high-throughput Knudsen pump based on macro-micro multi-channel coupling according to claim 1, characterized in that, The gas is a rarefied gas, specifically helium. The inlet pressure at the input end of the microchannel is within the range of [0.1, 100], measured in kPa.

8. A design method for a high-throughput Knudsen pump based on macro-micro multi-channel coupling, characterized in that, include: A number of microchannels are provided, all with identical geometric parameters, and arranged in parallel. The low-temperature end of each microchannel is the gas input end, and the high-temperature end is the gas output end. The high-temperature end of each microchannel is connected to a macrochannel. A macro channel is configured, wherein the high-temperature end of the macro channel is the gas input end, the low-temperature end of the macro channel is the gas output end, and the high-temperature end of the macro channel is connected to a micro channel. Wherein, the macrochannel radius R and the microchannel radius r satisfy R=ar, a is the scale ratio, and the scale ratio a satisfies a≥20, so that the viscous resistance of the macrochannel is reduced relative to the resistance of the microchannel, thereby weakening or eliminating the coupling effect between the microchannels.

9. A high-throughput Knudsen pump device based on macro-micro multi-channel coupling, characterized in that, include: processor; A memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to perform the method as described in claim 8.

10. A computer-readable storage medium, characterized in that, It stores computer program instructions, which, when executed by a processor, implement the method of claim 8.

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