Wide range flow sensor—Vacuum through viscous flow conditions

Sagi, Hemi; Zhao, Yabin; Wereley, Steven T.

doi:10.1116/1.1776181

Cited by 10 publications

(3 citation statements)

References 7 publications

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“…Micro gas flow measurement technology is widely used in industries such as semiconductor processing [1], aerospace [2], automotive electronics [3], the chemical industry [4], and medical equipment [5]. These industries require high accuracy and short response times for micro gas flow measurement.…”

Section: Introductionmentioning

confidence: 99%

Development of a Measurement Device for Micro Gas Flowrate Based on Laminar Flow Element with Micro-Curved Surface

Wang,

Xu,

Liu

et al. 2024

Micromachines

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The laminar flow meter (LFM) boasts several advantages such as no moving parts, a wide range ratio, high measurement accuracy, quick dynamic response, etc., and is a promising technology for micro gas flow measurement. In order to explore the influence of different curvature radii on curved surface gap LFM, three curved structures with different curvature radii were designed. The computational fluid dynamics method is applied to simulate the flow feature of three structures. The simulated velocity cloud and pressure distribution show that the larger the curvature radius, the more stable the flow of gas medium. The relationship between differential pressure and volume flow was obtained through the test within a flow range of 0~540 sccm. Regression analysis revealed that the volume flow measured by the curved surface LFM had a high linear relationship with the differential pressure. Experimental findings indicate that differential pressure of the structure with a curvature radius of 2 mm was greater than that of other two structures (curvature radius of 6 mm and 3 mm) at the same point. This indicates that adding the number of surfaces can effectively increase the pressure loss, so as to obtain a larger range ratio, but will increase the measurement error.

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Section: Introductionmentioning

confidence: 99%

Development of a Measurement Device for Micro Gas Flowrate Based on Laminar Flow Element with Micro-Curved Surface

Wang,

Xu,

Liu

et al. 2024

Micromachines

View full text Add to dashboard Cite

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“…Studies of very small gas flow in microchannels have been essential in a large number of applications such as ultra sensitive gas flow sensors, gas chromatography, microchemical gas reactors, low-pressure semiconductor manufacturing machines, microscale heat exchangers, and micro gas regulators (Sagi et al 2004;Jang and Wereley 2007;Gross et al 2004;Shin and Besser 2006;Cho et al 1992;Debray et al 2005). The characteristic length scale of the gas flow in a microchannel is usually in the range of microns or tens of microns, and the mean free path of most common gases is approximately 60 nm at atmospheric conditions (Karniadakis et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Gaseous slip flow of a rectangular microchannel with non-uniform slip boundary conditions

Jang

Kim

2010

Microfluid Nanofluid

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This article presents analytical expressions of velocity and mass flow rate in terms of Fourier series for gaseous slip flows in long, straight, and uniform rectangular microchannels in the case of different first-order slip boundary conditions on each wall of the microchannels. The derived velocity expressions were in good agreement with those presented by Ebert and Sparrow (J Basic Eng 87:1018, 1965, when the slip boundary conditions on each wall of the microchannels were identical. The computed first-order dimensionless mass flow rate was also in very good agreement with the dimensionless mass flow rate for the planar channel reported by Arkilic et al. (J Microelectromec Syst 6:167, 1997) as the channel aspect ratio approached zero. Using the derived first-order dimensionless mass flow expression and the previously reported mass flow data, we found the unknown tangential momentum accommodation coefficient (TMAC) of nitrogen on a glass surface in a rectangular microchannel made by anodic bonding. The effects of the channel aspect ratio and Knudsen number on the velocity fields were discussed. The uncertainty level of the estimation of TMAC from mass flow rate measurements was also discussed, along with the effects of the channel aspect ratio and Knudsen number on the uncertainty level. List of symbols aChannel aspect ratio, a = h/w = H/W H Channel height (m) h Channel half height (m) Kn Knudsen number, Kn = k/H L Channel length between inlet and outlet (m) _ m Mass flow rate (kg/s) m* Dimensionless mass flow rate, m Ã ¼ lRTL _ m 16wh 3 p 2 o

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“…Most of them can be classified as either thermal-based or pressurebased. Thermal-based flow sensors, which correlate gas flow velocity with cooling of a heated element, can operate as low as 0.1 sccm (1 sccm = 2.083 × 10 −8 kg s −1 for nitrogen) in the semiconductor industry [7], but mostly they are impractical at sub-sccm flow rates because the gas velocity is too low to generate any significant convective cooling [2,8]. In fact, most of the micromachined thermal flow sensors measure a flow velocity range of zero to several meters per second [1].…”

Section: Introductionmentioning

confidence: 99%

Gaseous slip flow analysis of a micromachined flow sensor for ultra small flow applications

Jang

Wereley

2006

J. Micromech. Microeng.

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The velocity slip of a fluid at a wall is one of the most typical phenomena in microscale gas flows. This paper presents a flow analysis considering the velocity slip in a capacitive micro gas flow sensor based on pressure difference measurements along a microchannel. The tangential momentum accommodation coefficient (TMAC) measurements of a particular channel wall in planar microchannels will be presented while the previous micro gas flow studies have been based on the same TMACs on both walls. The sensors consist of a pair of capacitive pressure sensors, inlet/outlet and a microchannel. The main microchannel is 128.0 µm wide, 4.64 µm deep and 5680 µm long, and operated under nearly atmospheric conditions where the outlet Knudsen number is 0.0137. The sensor was fabricated using silicon wet etching, ultrasonic drilling, deep reactive ion etching (DRIE) and anodic bonding. The capacitance change of the sensor and the mass flow rate of nitrogen were measured as the inlet-to-outlet pressure ratio was varied from 1.00 to 1.24. The measured maximum mass flow rate was 3.86 × 10 −10 kg s −1 (0.019 sccm) at the highest pressure ratio tested. As the pressure difference increased, both the capacitance of the differential pressure sensor and the flow rate through the main microchannel increased. The laminar friction constant f · Re, an important consideration in sensor design, varied from the incompressible no-slip case and the mass sensitivity and resolution of this sensor were discussed. Using the current slip flow formulae, a microchannel with much smaller mass flow rates can be designed at the same pressure ratios.

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Wide range flow sensor—Vacuum through viscous flow conditions

Cited by 10 publications

References 7 publications

Development of a Measurement Device for Micro Gas Flowrate Based on Laminar Flow Element with Micro-Curved Surface

Development of a Measurement Device for Micro Gas Flowrate Based on Laminar Flow Element with Micro-Curved Surface

Gaseous slip flow of a rectangular microchannel with non-uniform slip boundary conditions

Gaseous slip flow analysis of a micromachined flow sensor for ultra small flow applications

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