Single- and two-phase pressure losses in a horizontal mini-size impacting tee junction with a rectangular cross-section

2012 ◽  
Vol 41 ◽  
pp. 67-76 ◽  
Author(s):  
A.M. Elazhary ◽  
H.M. Soliman
Keyword(s):  
Cross Section ◽  
Rectangular Cross Section ◽  
Two Phase ◽  
Pressure Losses ◽  
Tee Junction ◽  
Phase Pressure

An Experimentally Validated Model for Two-Phase Sudden Contraction Pressure Drop in Microchannel Tube Headers

2003 ◽  
Author(s):  
John Wesley Coleman
Keyword(s):  
Pressure Loss ◽  
Accurate Determination ◽  
Time Data ◽  
Two Phase ◽  
Pressure Transducers ◽  
Pressure Losses ◽  
Mass Fluxes ◽  
Data Points ◽  
Minor Losses ◽  
Phase Pressure

This paper presents the results of an experimental investigation of two-phase pressure loss of R134a in microchannel headers using various end-cut techniques. Novel experimental techniques and test sections were developed to enable the accurate determination of the minor losses without obfuscating the problem with a lengthwise pressure gradient. This technique represents a departure from approaches used by other investigators that have extrapolated minor losses from air-water experiments and the combined effects of expansion, contraction, deceleration, and lengthwise pressure gradients. Pressure losses were recorded over the entire range of qualities from 100% vapor to 100% liquid. In addition, the tests were conducted for five different refrigerant mass fluxes between 185 kg/m2-s and 785 kg/m2-s using two differnt end-cut techniques. More than 790 data points were recorded to obtain a comprehensive understanding of the effects of mass flux and quality on minor pressure losses. High accuracy instrumentation such as coriolis mass flowmeters, RTDs, pressure transducers, and real-time data analyses were used to ensure accuracy in the results. The results show that many of the commonly used correlations for estimating two-phase pressure losses significantly underpredict the pressure losses found in compact microchannel tube headers. Furthermore, the results show that the end-cut technique can substantially affect the pressure losses in microchannel headers. A new model for estimating the pressure loss in microchannel headers is presented and a comparison of the end-cut techniques on the minor losses is reported.

The Investigation of the Kinetic Energy of Slug in a Horizontal Channel Using VOF Method

2018 ◽  
Author(s):  
Nariman Ashrafi ◽  
Mohammad Reza Ansari ◽  
Armin Chegini ◽  
Ali Sadeghi
Keyword(s):  
Kinetic Energy ◽  
Pressure Gradient ◽  
Cross Section ◽  
Volume Fraction ◽  
Rectangular Cross Section ◽  
Vof Method ◽  
Experimental Results ◽  
Two Phase ◽  
Trapped Air ◽  
Helmholtz Condition

In this article, two-phase slug regime in a duct with rectangular cross-section is investigated numerically, using the volume of fluid (VOF) method. Equations of mass, momentum and advection of volume fraction are solved accompanying k-∈ realizable turbulence equations. To ensure the creditability, numerical results have been compared with experimental results using same geometry. With occurrence of instability in the entrance of duct, Kelvin-Helmholtz condition satisfies and with increasing instability, slug phenomenon occurs. With closing the cross-section of duct, slug causes pressure gradient in it. Trapped air behind a slug transfers the momentum and increases the kinetic energy of slug. In this research the kinetic energy of a slug is investigated.

The motion of large bubbles in horizontal channels

1970 ◽  
Vol 43 (2) ◽  
pp. 247-255 ◽  
Author(s):  
G. C. Gardner ◽  
I. G. Crow
Keyword(s):  
Surface Tension ◽  
Experimental Investigation ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Phase Interface ◽  
Bubble Velocity ◽  
Radius Of Curvature ◽  
Channel Depth ◽  
Two Phase ◽  
Air Bubble

An experimental investigation of a large long air bubble moving into stationary water in a horizontal channel of rectangular cross-section is presented and three well-defined flow régimes for the water discharged beneath the bubble are described. The influence of surface tension on the bubble velocity is explained using the hypothesis that the radius of curvature of the two-phase interface close to the upper wall does not vary greatly with channel depth and is close to the theoretical value for a channel of such depth that the bubble is just motionless.

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