Pressure Change for Single- and Two-Phase Non-Newtonian Flows through Sudden Contraction in Rectangular Microchannel

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 440
Author(s):  
Masaki Toshimitsu ◽  
Yukihiro Yonemoto ◽  
Akimaro Kawahara
Keyword(s):  
Pressure Distribution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Pressure Change ◽  
Two Phase ◽  
Rectangular Microchannel ◽  
Cross Sectional ◽  
Contraction Ratio ◽  
Cross Sectional Dimension ◽  
Sudden Contraction

The flow characteristics of the single-phase liquid and the gas–liquid two-phase flows including the Newtonian and non-Newtonian liquids were experimentally investigated in a horizontal rectangular micro-channel with a sudden contraction—specifically the pressure change across the contraction. The rectangular cross-sectional dimension has Wu × Hu (width × height) = 0.99 × 0.50 mm2 on the upstream side of the contraction and Wd × Hd = 0.49 × 0.50 mm2 on the downstream side. The resulting contraction ratio, σA (=Wd/Wu), was 0.5. Air was used as the test gas (in the case of the gas–liquid two-phase flow experiment), distilled water and three kinds of aqueous solution, i.e., glycerin 25 wt%, xanthangum 0.1 wt% and polyacrylamide 0.11 wt% were used as the test liquid. The pressure distribution in the flow direction upstream and downstream of the channel was measured. The pressure change and loss at the sudden contraction were determined from the pressure distribution. In addition, the pressure change data were compared with the calculation by several correlations proposed by various researchers as well as a newly developed correlation in this study. From the comparisons, it was found that calculations by the newly developed correlations agreed well with the measured values within the error of 30%.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

scholarly journals Cross-Sectional Dimension Dependence of Electroosmotic Flow in Fractal Treelike Rectangular Microchannel Network

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 266 ◽  
Author(s):  
Dalei Jing ◽  
Xuekuan Zhan
Keyword(s):  
Surface Area ◽  
Electroosmotic Flow ◽  
Scaling Laws ◽  
Channel Length ◽  
Channel Height ◽  
Rectangular Microchannel ◽  
Cross Sectional ◽  
Cross Sectional Dimension ◽  
Fluidic Resistance ◽  
Fractal Network

The present work theoretically and numerically studies the electroosmotic flow (EOF) within a fractal treelike rectangular microchannel network with uniform channel height. To obtain minimum EOF fluidic resistance, the microchannel cross-sectional dimensions of the fractal network are optimized. It is found that the cross-sectional dimension dependence of EOF fluidic resistance within a symmetric fractal network is only dependent on the channel width when the total channel volume is constant, and the optimal microchannel widths to reach the minimum EOF fluidic resistance satisfy the scaling law of κ = N−1 (where κ is the width ratio of the rectangular channels at two successive branching levels, N is the branching number); however, for the symmetric fractal network with constant total surface area, the optimal cross-sectional dimensions should simultaneously satisfy κ = N−1 and H = S 4 l 0 1 − γ N 1 − ( γ N ) m + 1 (where H is the channel height, S is the total channel surface area, l0 is the channel length at the original branching level, γ is the channel length ratio at two successive branching levels and m is the total branching level) to obtain the minimum EOF fluidic resistance. The optimal scaling laws established in present work can be used for the optimization design of the fractal rectangular microchannel network for EOF to reach maximum transport efficiency.

An Experimental Investigation of Gas-Liquid Heat Transfer in Rectangular Micro-Channels

2013 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises ◽  
Piyawat Kuaseng ◽  
Chompunut Nuibutr ◽  
Wattana Chanphan
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Camera System ◽  
Micro Channels ◽  
Flow Mechanisms

The investigations of heat transfer and fluid flow characteristics of non-boiling air-water flow in micro-channels are experimentally studied. The gas-liquid mixture from y-shape mixer is forced to flow in the 21 parallel rectangular microchannels with 40 mm long in the flow direction. Each channel has a width and a depth of 0.45 and 0.41 mm, respectively. Flow visualization is feasible by incorporating the stereozoom microscope into the camera system and different flow patterns are recorded. The experiments are performed under low superficial velocities. Two-phase heat transfer gives better results when compared with the single-phase flow. It is found from the experiment that heat transfer enhancement up to 53% is obtained over the single-phase flow. Also, the change in the configuration of the inlet plenum can result in the different two-phase flow mechanisms.

Visualization Study on Two-Phase Flow Behaviors in the Gas-Liquid-Solid Microreactor for Hydrogenation of Nitrobenzene

2016 ◽  
Author(s):  
Hao Feng ◽  
Xun Zhu ◽  
Rong Chen ◽  
Qiang Liao
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Microchannel Reactor ◽  
Two Phase ◽  
Modified Surface

In this study, visualization study on the gas-liquid two phase flow characteristics in a gas-liquid-solid microchannel reactor was carried out. Palladium nanocatalyst was coated onto the polydopamine functionalized surface of the microchannel through eletroless deposition. The materials characterization results indicated that palladium nanocatalyst were well dispersed on the modified surface. The effects of both the gas and liquid flow rates as well as inlet nitrobenzene concentration on the two-phase flow characteristics were studied. The experimental results revealed that owing to the chemical reaction inside the microreactor, the gas slug length gradually decreased along the flow direction. For a given inlet nitrobenzene concentration, increasing the liquid flow rate or decreasing the gas flow rate would make the variation of the gas slug length more obvious. High inlet nitrobenzene concentration would intensify both the nitrobenzene transfer efficiency and gas reactants consumption, and thereby the flow pattern in the microchannel was transferred from Taylor flow into bubble flow. Besides, the effect of both flow rate and original nitrobenzene concentration on the variation of nitrobenzene conversion and the desired product aniline yield were also discussed.

Two-phase flow characteristics across sudden contraction in small rectangular channels

2008 ◽  
Vol 32 (8) ◽  
pp. 1609-1619 ◽  
Author(s):  
Ing Youn Chen ◽  
Mon-Chern Chu ◽  
Jane-Sunn Liaw ◽  
Chi-Chuan Wang
Keyword(s):  
Two Phase Flow ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase ◽  
Rectangular Channels ◽  
Sudden Contraction

Heat Transfer in Triangular Microchannels

2003 ◽  
Author(s):  
J. Todd Dickey ◽  
Tung T. Lam
Keyword(s):  
Heat Transfer ◽  
Porous Material ◽  
Cross Sections ◽  
Flow Characteristics ◽  
Microchannel Flow ◽  
Geometric Aspect ◽  
Rectangular Microchannel ◽  
Cross Sectional ◽  
Numerical Heat Transfer ◽  
Fluid Flow Characteristics

A numerical heat transfer solution is compared with an analytical solution for a microchannel flow. The analytical derivation is based upon the porous material assumption as put forth by various investigators. While extensive work exists for the rectangular microchannel cross sectional area, other cross sections have not received the same attention. It is the intent of this paper to investigate the applicability of the porous material assumption to a triangular “saw tooth” cross section microchannel with respect to heat transfer and fluid flow characteristics. The results are presented in nondimensionalized form applicable to any fluid and geometric aspect ratio combination presented herein.

scholarly journals Flow Characteristics and Control of Vertical Upward Gas-Liquid Two-Phase Flow through a Sudden Contraction Pipe

2006 ◽  
Vol 49 (4) ◽  
pp. 1000-1007 ◽  
Author(s):  
Alexandros VOUTSINAS ◽  
Toshihiko SHAKOUCHI ◽  
Junichi TAKAMURA ◽  
Koichi TSUJIMOTO ◽  
Toshitake ANDO
Keyword(s):  
Two Phase Flow ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase ◽  
Sudden Contraction ◽  
Flow Through ◽  
And Control
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