Investigation of a Two-Phase Siphon: Pressure Drop Characteristics, Flow Prediction, and Flow Regime Change Prediction

Volume 3 ◽  
2004 ◽  
Author(s):  
J. Howard Arthur ◽  
Charles D. Morgan ◽  
Cory D. Engelhard ◽  
Berton Austin
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Distribution Parameter ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Rates ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Regime Transition ◽  
Flux Model

In some nuclear power plants, a passive siphon breaking system is used to prevent the spent fuel tank from draining in the event of a break in the vertical leg of the heat exchanger piping. A hole is drilled in the horizontal leg of the piping. When the water level in the tank drops below the pipe level air is sucked into the system. When sufficient air is entrained in the pipe the siphon will break. A model to predict the flow rate in a vertical siphon was developed in reference 1 using the homogeneous flow model. The predicted flow rates were greater than measured flow rates. In order to improve the predictive capability, pressure drop measurements were obtained from ten foot vertical test sections with nominal diameters of 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 inches. Values of the distribution parameter, Co, for the drift flux model were determined from the pressure drop data. When the model of reference 1 is changed from homogeneous flow to drift flux model with the distribution parameter determined from the pressure drop data, good agreement with measured liquid flow rates is obtained. The improved model, along with the correlation for the siphon break condition obtained provides a good method for determining the hole size required to break the siphon. There is a paucity of data for two-phase flow regime transition where the flow is in the downward direction that is typical in a siphon. Flow regime transition data were obtained using the test sections listed above. The flow map of Oshinowo2 et al. gave a reasonable prediction of the transition from bubbly to slug flow. None of the references investigated gave an adequate prediction of the point where the siphon would break. A correlation for the siphon break point was developed.

Flow Pattern and Pipe Orientation Independent Semi-Empirical Void Fraction Correlation for a Gas-Liquid Two Phase Flow Based on the Concept of Drift Flux Model

2012 ◽  
Author(s):  
Swanand M. Bhagwat ◽  
Afshin J. Ghajar
Keyword(s):  
Flow Pattern ◽  
Void Fraction ◽  
Drift Velocity ◽  
Distribution Parameter ◽  
Two Phase ◽  
Data Set ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model ◽  
Inclined Pipe

A flow pattern and pipe orientation independent void fraction correlation is proposed in the present study. The correlation is based on the concept of drift flux model and proposes two separate expressions to model distribution parameter and drift velocity. The distribution parameter is expressed as a function of pipe orientation, phase superficial velocities and the void fraction in implicit form, while the drift velocity parameter is modeled as a function of fluid thermo physical properties, pipe orientation and void fraction. The drift velocity equation proposed by Zukoski [1] is extended for downward inclined pipe orientations. The performance of the proposed void fraction correlation is verified against void fraction data set of 5928 data points including the data for fifteen pipe diameters and eight different fluid combinations. The superiority of the proposed correlation is also illustrated by comparing it against the top performing correlations in horizontal, vertical upward and vertical downward pipe orientations and the predictions of the Woldesemayat and Ghajar [2] and Chexal et al. [3] correlations for incline pipe orientations.

A Drift-Flux Model Flow-Regime Map of Two-Phase Flows for Thermal-Hydraulic Calculations

1983 ◽  
Vol 84 (2) ◽  
pp. 166-168 ◽  
Author(s):  
S. Kaizerman ◽  
E. Wacholder ◽  
E. Elias
Keyword(s):  
Flow Regime ◽  
Two Phase Flows ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Model Flow ◽  
Flux Model ◽  
Regime Map ◽  
Flow Regime Map

Local Liquid Velocity in Vertical Air-Water Downward Flow

2004 ◽  
Vol 126 (4) ◽  
pp. 539-545 ◽  
Author(s):  
Xiaodong Sun ◽  
Sidharth Paranjape ◽  
Seungjin Kim ◽  
Hiroshi Goda ◽  
Mamoru Ishii ◽  
...  
Keyword(s):  
Liquid Flow ◽  
Liquid Velocity ◽  
Laser Doppler Anemometry ◽  
Two Phase ◽  
Downward Flow ◽  
Flow Rates ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Local Measurements ◽  
Flux Model

This paper presents an experimental study of local liquid velocity measurement in downward air-water bubbly and slug flows in a 50.8 mm inner-diameter round pipe. The axial liquid velocity and its fluctuations were measured by a laser Doppler anemometry (LDA) system. It was found that the maximum liquid velocity in a downward two-phase flow could occur off the pipe centerline at relatively low liquid flow rates and this observation is consistent with other researchers’ results. The comparisons between the liquid flow rates measured by a magnetic flow meter and those obtained from the local LDA and multi-sensor conductivity probe measurements showed good agreement. In addition, based on the local measurements the distribution parameter and the drift velocity in the drift-flux model were obtained for the current downward flow tests.

APPLICATION OF THE DRIFT FLUX MODEL IN A TWO-PHASE REFRIGERANT FLOW THROUGH CAPILLARY TUBE

2016 ◽  
Author(s):  
Mariana Barbosa ◽  
Ricardo Augusto Mazza
Keyword(s):  
Capillary Tube ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model ◽  
Flow Through

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

Low Bond Number Two-Phase Flow Regime Transition from Slug to Annular Wavy Flow in a Microchannel

2003 ◽  
Vol 125 (4) ◽  
pp. 544-544 ◽  
Author(s):  
Sang Young Son ◽  
Jeffrey S. Allen ◽  
Kenneth O. Kihm
Keyword(s):  
Flow Regime ◽  
Two Phase Flow ◽  
Bond Number ◽  
Phase Flow ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Regime Transition

Interfacial Structures and Regime Transition in Co-Current Downward Bubbly Flow

2004 ◽  
Vol 126 (4) ◽  
pp. 528-538 ◽  
Author(s):  
S. Kim ◽  
S. S. Paranjape ◽  
M. Ishii ◽  
J. Kelly
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Parameters ◽  
Interfacial Structures ◽  
Flux Model

The vertical co-current downward air-water two-phase flow was studied under adiabatic condition in round tube test sections of 25.4-mm and 50.8-mm ID. In flow regime identification, a new approach was employed to minimize the subjective judgment. It was found that the flow regimes in the co-current downward flow strongly depend on the channel size. In addition, various local two-phase flow parameters were acquired by the multi-sensor miniaturized conductivity probe in bubbly flow. Furthermore, the area-averaged data acquired by the impedance void meter were analyzed using the drift flux model. Three different distributions parameters were developed for different ranges of non-dimensional superficial velocity, defined by the ration of total superficial velocity to the drift velocity.

Interaction of weak shocks in drift-flux model of compressible two-phase flows

2018 ◽  
Vol 107 ◽  
pp. 222-227 ◽  
Author(s):  
S. Kuila ◽  
T. Raja Sekhar
Keyword(s):  
Two Phase Flows ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model ◽  
Weak Shocks

Numerical simulation of two phase refrigerant flow through non-adiabatic capillary tubes using drift flux model

2018 ◽  
Vol 32 (1) ◽  
pp. 381-389
Author(s):  
Masoud Zareh ◽  
Morteza Khayat ◽  
Hamed Fouladi
Keyword(s):  
Numerical Simulation ◽  
Capillary Tubes ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model ◽  
Flow Through
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