Experimental Study of Pressure Loss Due to Abrupt Expansion and Contraction in Mini-Channels

Yu, Jin-Won; Li, Z.; F., C.

doi:10.1615/ihtc13.p14.190

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…The contraction loss coefficient for air in turbulent flow and water in laminar flow had a minor increase with the Reynolds number increasing. Yu et al [7] and Li et al [8,9] conducted experiments with nitrogen and water, and investigated single-phase and gas-liquid two-phase pressure drops caused by a sudden contraction in microtubes at room temperature and atmospheric pressure. The diameter of the smaller tube was 330 μm.…”

Section: Introductionmentioning

confidence: 99%

Local resistance of fluid flow across sudden contraction in small channels

Guo

et al. 2009

Front. Energy Power Eng. China

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The pressure drop caused by flow area contraction in microchannels has been experimentally studied in this paper using the tiny gap pressure measurement method. The working fluid was deionized water at room temperature at near-atmospheric pressure. Three test sections with area ratios of 0.284 and 0.274 and at different tube diameter sizes were used. The experimental results show that the abrupt contraction coefficient K c decreases with the Reynolds number increasing, and it is much higher than that of conventional tubes in laminar flow. The widely-applied correlation K c = 0.5(1 -σ) 0.75 could not predict the contraction coefficient of turbulent flow in the micro tubes. The K c decreases as the tube diameter increases. The transition from laminar to turbulent flow is not obvious when the diameter of the small tube is 0.32 mm.

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Section: Introductionmentioning

confidence: 99%

Local resistance of fluid flow across sudden contraction in small channels

Guo

et al. 2009

Front. Energy Power Eng. China

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“…Moreover, the supporting experiments have been performed for circular and triangular tube geometries only, while the theoretical expressions vary considerably with the shape of the channels and between single and multiple channel configurations. Some experimental work has been performed more recently on mini-and micro-channels, but results of these are also inconclusive ( [46], [47], [48]). Therefore, it appears that no reliable, validated data exists for laminar contraction losses in square ducts and duct arrays.…”

Section: )mentioning

confidence: 99%

Turbulent Flow Pressure Losses in Gasoline Particulate Filters

Aleksandrova

Saul

Prantoni

et al. 2019

SAE Int. J. Engines

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Contraction/Expansion Effects in 90° Miter Bends in Rectangular Xurographic Microchannels

Nguyen

Elsnab

Ameel

2011

ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, Volume 1

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Xurography is an inexpensive rapid prototyping technology for the development of microfluidic systems. Imprecision in the xurographic tape cutting process can result in undesired changes in channel dimensions near features that require a change in cutting direction, such as 90° miter bends. An experimental study of water flow in rectangular xurographic microchannels incorporating 90° miter bends with different channel widths in each leg is reported. A set of twelve microchannels, with channel depth approximately 105 micrometers and aspect ratio ranging from 0.071 to 0.435, were fabricated from double-sided adhesive Kapton® polyimide tape and two rectangular glass plates. The channels were reinforced with a mechanical clamping system, enabling high Reynolds number, Re, flows (up to Re = 3200) where Re was based upon hydraulic diameter and average velocity. Reported data include friction factor and critical Reynolds number for straight microchannels and loss coefficients for flow through 90° miter bends that contain either a contraction or expansion with cross-sectional area ratios of 0.5, 0.333 and 0.2. The critical Reynolds number, Recr, ranged from 1750 to 2300 and was found to be dependent on channel defects such as sidewall roughness, adhesive droplets, and corner imperfections. Loss coefficients through 90° miter bends with expansion decrease rapidly for Re < Recr. At the transition, the loss coefficient suddenly drops and approaches an asymptotic value for Re > Recr. For 90° miter bends with contractions, loss coefficients gradually decrease with increasing Re for 150 < Re < 1400. In addition, the loss coefficient decreases with decreasing area ratio through the contraction or expansion. The minor loss coefficient data were found to be dependent on Reynolds numbers and area ratio of contraction/expansion at the bend. The results suggest that the effect of the contraction/expansion was the dominant mechanism for minor losses in the 90° miter bend.

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Experimental Study of Pressure Loss Due to Abrupt Expansion and Contraction in Mini-Channels

Cited by 3 publications

References 6 publications

Local resistance of fluid flow across sudden contraction in small channels

Local resistance of fluid flow across sudden contraction in small channels

Turbulent Flow Pressure Losses in Gasoline Particulate Filters

Contraction/Expansion Effects in 90° Miter Bends in Rectangular Xurographic Microchannels

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