A Discussion on the Relation Between the Intermittent Flow Sub-Regimes and the Frictional Pressure Drop

2021 ◽  
Vol 181 ◽  
pp. 121895
Author(s):  
Abderraouf Arabi ◽  
Yacine Salhi ◽  
Youcef Zenati ◽  
El-Khider Si-Ahmed ◽  
Jack Legrand
Keyword(s):  
Pressure Drop ◽  
Intermittent Flow ◽  
Frictional Pressure Drop

Evaluation Analysis of Prediction Methods for Two-Phase Flow Pressure Drop in Mini-Channels

2008 ◽  
Author(s):  
Licheng Sun ◽  
Kaichiro Mishima
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulent Region ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Mini Channels ◽  
Flow Pressure ◽  
Better Than

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.

Laminar Fully-Developed Flow in a Microchannel With Patterned Ultrahydrophobic Walls

2005 ◽  
Author(s):  
B. Woolford ◽  
K. Jeffs ◽  
D. Maynes ◽  
B. W. Webb
Keyword(s):  
Pressure Drop ◽  
Solid Wall ◽  
Relative Size ◽  
Frictional Resistance ◽  
Hydraulic Diameter ◽  
Fourth Power ◽  
Fully Developed Flow ◽  
Flowing Liquid ◽  
Frictional Pressure Drop ◽  
Liquid Vapor

Microfluidic transport is finding increasing application in a number of emerging technologies. At these scales, classical analysis shows that the required fluid driving pressure is inversely proportional to the hydraulic diameter to the fourth power. Consequently, generating fluid motion at these physical scales is a challenge. There is thus considerable incentive for developing strategies to reduce the frictional resistance to fluid flow. A novel approach recently proposed is fabrication of micro-ribs and cavities in the channel walls which are treated with a hydrophobic coating. This reduces the surface contact area between the flowing liquid and the solid wall, yielding walls with no-slip and shear-free regions at the microscale. The shear-free regions consist of a liquid-vapor meniscus above the cavities between micro-ribs. Reductions in the flow resistance are thus possible. This paper reports results of an analytical and experimental investigation of the laminar, fully-developed flow in a parallel plate microchannel whose walls are microengineered in this fashion. The micro-ribs and cavities are oriented parallel to the flow direction. The channel walls are modeled in an idealized fashion, with the shape of liquid-vapor meniscus approximated as flat and characterized by vanishing shear stress. Predictions are presented for the friction factor-Reynolds number product as a function of relevant governing dimensionless parameters. Comparisons are made between the smooth-wall classical channel flow results and predictions for the microengineered channel walls. Results show that significant reductions in the frictional pressure drop are possible. Reductions in frictional resistance increase as the channel hydraulic diameter and/or micro-rib width are reduced. The frictional pressure drop predictions are in good agreement with experimental measurements made at dynamically similar conditions, with greater deviation observed with increasing relative size of the shear-free regions.

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 Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

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