Churn and Wispy Annular Flow Regimes in Vertical Gas–Liquid Flows

2012 ◽  
Vol 26 (7) ◽  
pp. 4067-4077 ◽  
Author(s):  
Geoffrey F. Hewitt
Keyword(s):  
Annular Flow ◽  
Flow Regimes ◽  
Liquid Flows

Shifting Chemical Equilibria in Flow-Efficient Decarbonylation Driven by Annular Flow Regimes

2014 ◽  
Vol 126 (43) ◽  
pp. 11741-11745 ◽  
Author(s):  
Bernhard Gutmann ◽  
Petteri Elsner ◽  
Toma Glasnov ◽  
Dominique M. Roberge ◽  
C. Oliver Kappe
Keyword(s):  
Annular Flow ◽  
Flow Regimes ◽  
Chemical Equilibria

Shifting Chemical Equilibria in Flow-Efficient Decarbonylation Driven by Annular Flow Regimes

2014 ◽  
Vol 53 (43) ◽  
pp. 11557-11561 ◽  
Author(s):  
Bernhard Gutmann ◽  
Petteri Elsner ◽  
Toma Glasnov ◽  
Dominique M. Roberge ◽  
C. Oliver Kappe
Keyword(s):  
Annular Flow ◽  
Flow Regimes ◽  
Chemical Equilibria

scholarly journals COMPARISON ANALYSIS OF CORRELATIONS FOR INTERFACIAL FRICTION FACTOR APPLIED IN GAS-LIQUID ANNULAR FLOW IN VERTICAL PIPES

2017 ◽  
Vol 16 (2) ◽  
pp. 54 ◽  
Author(s):  
C. F. de Paula Jr. ◽  
L. E. M. Lima
Keyword(s):  
Experimental Data ◽  
Friction Factor ◽  
Annular Flow ◽  
Interfacial Shear Stress ◽  
Interfacial Friction ◽  
Gas Flows ◽  
Steam Generation ◽  
Definition Of ◽  
Liquid Flows ◽  
Different Characteristics

Gas-liquid flows in pipes can occur in the form of an annular pattern in which the liquid flows as a thin film at pipe wall and the gas flows as a core in pipe center. This flow pattern is often encountered at boiling and condensation processes, for example, in industries of steam generation, cooling or petroleum. In annular flow, the interfacial friction factor is one of the important closing parameters for the definition of the interfacial shear stress and consequently the pressure gradient. In the literature, several correlations are found to estimate the interfacial friction factor. The main objective of this work is to carry out a comparative analysis of some these correlations against experimental data also obtained from the literature. The features and limitations of each correlation were observed, as well as the accuracy of each in relation to experimental data. The results obtained demonstrate that correlations analyzed, present relatively satisfactory results, despite the different characteristics of the correlations, however, it is necessary to carry out more extensive analyses involving others correlations and sets of experimental data.

Effect of Drag-Reducing Agents in Multiphase Flow Pipelines

1998 ◽  
Vol 120 (1) ◽  
pp. 15-19 ◽  
Author(s):  
C. Kang ◽  
R. M. Vancko ◽  
A. S. Green ◽  
H. Kerr ◽  
W. P. Jepson
Keyword(s):  
Multiphase Flow ◽  
Pressure Gradient ◽  
Slug Flow ◽  
Annular Flow ◽  
Flow Regimes ◽  
Reducing Agents ◽  
Pressure Gradients ◽  
Horizontal Pipes ◽  
Flow Pressure ◽  
Inclined Pipes

The effect of drag-reducing agents (DRA) on pressure gradient and flow regime has been studied in horizontal and 2-deg upward inclined pipes. Experiments were conducted for different flow regimes in a 10-cm i.d., 18-m long plexiglass system. The effectiveness of DRA was examined for concentrations ranging from 0 to 75 ppm. Studies were done for superficial liquid velocities between 0.03 and 1.5 m/s and superficial gas velocities between 1 and 14 m/s. The results indicate that DRA was effective in reducing the pressure gradients in single and multiphase flow. The DRA was more effective for lower superficial liquid and gas velocities for both single and multiphase flow. Pressure gradient reductions of up to 42 percent for full pipe flow, 81 percent for stratified flow, and 35 percent for annular flow were achieved in horizontal pipes. In 2 deg upward inclination, the pressure gradient reduction for slug flow, with a concentration of 50 ppm DRA, was found to be 28 and 38 percent at superficial gas velocities of 2 and 6 m/s, respectively. Flow regimes maps with DRA were constructed in horizontal pipes. Transition to slug flow with addition of DRA was observed to occur at higher superficial liquid velocities.

A simplified model for churn and annular flow regimes in small- and large-diameter pipes

2017 ◽  
Vol 162 ◽  
pp. 309-321 ◽  
Author(s):  
E. Pagan ◽  
W.C. Williams ◽  
S. Kam ◽  
P.J. Waltrich
Keyword(s):  
Annular Flow ◽  
Large Diameter ◽  
Flow Regimes ◽  
Simplified Model ◽  
Large Diameter Pipes

Modeling Transient Churn-Annular Flows in a Long Vertical Pipe

2013 ◽  
Author(s):  
M. V. C. Alves ◽  
J. R. Barbosa ◽  
P. J. Waltrich ◽  
G. Falcone
Keyword(s):  
Annular Flow ◽  
Large Scale ◽  
Coefficient Matrix ◽  
Vertical Tube ◽  
Flow Conditions ◽  
Vertical Pipe ◽  
One Dimensional ◽  
The One ◽  
Energy Equations ◽  
Liquid Flows

A mathematical model is presented to describe the behavior of transient gas-liquid flows involving the churn and annular flow patterns in a long vertical tube. The HyTAF (Hyperbolic Transient Annular Flow) code, developed specifically for this study, is based on the one-dimensional multi-fluid formulation and takes account of hydrodynamic non-equilibrium flow conditions by means of relationships for the rates of droplet entrainment and deposition. A finite difference algorithm is employed to solve the hyperbolic system of mass, momentum and energy equations via the Split Coefficient Matrix Method. The modeling results are compared with experimental data for steady-state annular and churn flows obtained from the literature and with pressure and flow rate induced transient churn-annular flow data generated in a large scale facility (48-mm ID, 42-m long test section).

Detailed Characterization of Two-Phase Annular Flow in a Horizontal Tube

Volume 3 ◽  
2004 ◽  
Author(s):  
DuWayne Schubring ◽  
Timothy A. Shedd
Keyword(s):  
Pressure Drop ◽  
Film Thickness ◽  
Wave Velocity ◽  
Liquid Flow ◽  
Annular Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Dependence ◽  
Annular Regime

In this study, non-intrusive pressure drop, liquid film thickness distribution and wave behavior measurements have been obtained for 140 and 220 two-phase flow conditions in horizontal 8.8 mm I.D and 15.1 mm I.D. tubes, respectively. Horizontal flow regimes ranging from stratified-wavy to annular were studied in long clear test sections. Pressure drop data appeared to show different trends for the wavy, wavy-annular and annular flow regimes, suggesting that a unique model may be required for each. In addition, wave frequency showed clearly different behavior for these regimes, with only minor liquid flow dependence in the wavy and wavy-annular flows and strong liquid flow dependence in annular flow. Interestingly, disturbance wave velocity could be correlated to within 10% by the gas friction velocity in the annular regime and within 20% in the wavy-annular regime, leading to a simple correlation between pressure drop and wave velocity. Base film thickness data (between waves) show that the film is relatively insensitive to gas flow at the side and top of the tube and that the film thickness around the tube becomes nearly independent of liquid flow rate at high gas flows. Empirical correlations of the various data sets are presented with the goal of aiding general horizontal two-phase flow modeling efforts.

Condensation Flow Mechanisms in Microchannels: Basis for Pressure Drop and Heat Transfer Models

2003 ◽  
Author(s):  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Visualization ◽  
Flow Regime ◽  
Annular Flow ◽  
Flow Regimes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Mechanisms ◽  
Transfer Models

This paper presents an overview of the use of flow visualization in micro- and mini-channel geometries for the development of pressure drop and heat transfer models during condensation of refrigerants. Condensation flow mechanisms for round, square and rectangular tubes with hydraulic diameters in the range 1–5 mm for 0 < x < 1 and 150 kg/m2-s and 750 kg/m2-s were recorded using unique experimental techniques that permit flow visualization during the condensation process. The effect of channel shape and miniaturization on the flow regime transitions was documented. The flow mechanisms were categorized into four different flow regimes: intermittent flow, wavy flow, annular flow, and dispersed flow. These flow regimes were further subdivided into several flow patterns within each regime. It was observed that the intermittent and annular flow regimes become larger as the tube hydraulic diameter is decreased, at the expense of the wavy flow regime. These maps and transition lines can be used to predict the flow regime or pattern that will be established for a given mass flux, quality and tube geometry. These observed flow mechanisms, together with pressure drop measurements, are being used to develop experimentally validated models for pressure drop during condensation in each of these flow regimes for a variety of circular and noncircular channels with 0.4 < Dh < 5 mm. These flow regime-based models yield substantially better pressure drop predictions than the traditionally used correlations that are primarily based on air-water flows for large diameter tubes. Condensation heat transfer coefficients were also measured using a unique thermal amplification technique that simultaneously allows for accurate measurement of the low heat transfer rates over small increments of refrigerant quality and high heat transfer coefficients characteristic of microchannels. Models for these measured heat transfer coefficients are being developed using the documented flow mechanisms and the corresponding pressure drop models as the basis.

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