DYNAMICS OF TWO-PHASE FLOW ACROSS HORIZONTAL TUBE BUNDLES - A REVIEW

This paper presents a state-of-the-art review of the hydrodynamic aspects of two-phase flow across horizontal tube bundles. The review covers studies related to the evaluation of void fraction, two-phase flow behaviors and pressure drops on the shell side of staggered and in-line tube bundles for upward, downward and side-to-side flows. This study of the literature critically describes the proposed flow pattern maps and semi-empirical correlations for predicting void fraction and frictional pressure drop. These predicting methods are generally based on experimental results for adiabatic air-water flows. A limited number of experimental studies with R-11 and R-113 were also carried out in the past. The review shows noticeable discrepancies among the available prediction methods. Finally, this study suggests that further research focusing on the development of representative databanks and new prediction methods is still necessary.

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Numerical Prediction of Two-Phase Flow in Tube Bundles with a CFD Porous Media Approach Based on Mixture Model and a Void Fraction Correlation

E3S Web of Conferences ◽

10.1051/e3sconf/202132101002 ◽

2021 ◽

Vol 321 ◽

pp. 01002

Author(s):

Claire Dubot ◽

Vincent Melot ◽

Claudine Béghein ◽

Cyrille Allery ◽

Clément Bonneau

Keyword(s):

Porous Media ◽

Mixture Model ◽

Void Fraction ◽

Two Phase Flow ◽

Numerical Prediction ◽

Phase Flow ◽

Two Phase ◽

Mixture Density ◽

Tube Bundles ◽

Phase Mixture

Being able to predict the void fraction is essential for a numerical prediction of the thermohydraulic behaviour in steam generators. Indeed, it determines two-phase mixture density and affects two-phase mixture velocity which enable to evaluate the pressure drop of heat exchanger, the mass transfer and heat transfer coefficients. In this study, the flow is modelled by coupling Ansys Fluent with an in-house code library where a CFD porous media approach is implemented. In this code, the two-phase flow has been modelled so far using the Eulerian model. However, this two-phase model requires interaction laws between phases which are not known and/or reliable for a flow within a tube bundle. The aim of this paper is to use the mixture model, for which it is easier to implement suitable correlations for tube bundles. By expressing the relative velocity, as a function of slip, the void fraction model of Feenstra et al. developed for upward cross-flow through horizontal tube bundles is introduced. With this method, physical phenomena that occur in tube bundles are taken into consideration in the mixture model. The developed approach is validated based on the experimental results obtained by Dowlati et al.

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Two-Phase Flow Through Square and Circular Microchannels—Effects of Channel Geometry

Journal of Fluids Engineering ◽

10.1115/1.1777227 ◽

2004 ◽

Vol 126 (4) ◽

pp. 546-552 ◽

Cited By ~ 59

Author(s):

Peter M.-Y. Chung ◽

Masahiro Kawaji ◽

Akimaro Kawahara ◽

Yuichi Shibata

Keyword(s):

Pressure Drop ◽

Void Fraction ◽

Two Phase Flow ◽

Flow Characteristics ◽

Separated Flow ◽

Phase Flow ◽

Two Phase ◽

Channel Geometry ◽

Frictional Pressure Drop ◽

Channel Shape

An adiabatic experiment was conducted to investigate the effect of channel geometry on gas-liquid two-phase flow characteristics in horizontal microchannels. A water-nitrogen gas mixture was pumped through a 96 μm square microchannel and the resulting flow pattern, void fraction and frictional pressure drop data were compared with those previously reported by the authors for a 100 μm circular microchannel. The pressure drop data were best estimated using a separated-flow model and the void fraction increased non-linearly with volumetric quality, regardless of the channel shape. However, the flow maps exhibited transition boundaries that were shifted depending on the channel shape.

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INVESTIGATION ON VOID FRACTION FOR TWO-PHASE FLOW PRESSURE DROP OF EVAPORATIVE R-290 IN HORIZONTAL TUBE

Jurnal Teknologi ◽

10.11113/jt.v78.9590 ◽

2016 ◽

Vol 78 (8-4) ◽

Cited By ~ 1

Author(s):

Agus Sunjarianto Pamitran ◽

Sentot Novianto ◽

Normah Mohd-Ghazali ◽

Nasruddin Nasruddin ◽

Raldi Koestoer

Keyword(s):

Pressure Drop ◽

Void Fraction ◽

Two Phase Flow ◽

Flow Boiling ◽

Homogeneous Model ◽

Saturation Temperature ◽

Horizontal Tube ◽

Phase Flow ◽

Two Phase ◽

Experimental Conditions

Two-phase flow boiling pressure drop experiment was conducted to observe its characteristics and to develop a new correlation of void fraction based on the separated model. Investigation is completed on the natural refrigerant R-290 (propane) in a horizontal circular tube with a 7.6 mm inner diameter under experimental conditions of 3.7 to 9.6 °C saturation temperature, 10 to 25 kW/m2 heat flux, and 185 to 445 kg/m2s mass flux. The present experimental data was used to obtain the calculated void fraction which then was compared to the predicted void fraction with 31 existing correlations. A new void fraction correlation for predicting two-phase flow boiling pressure drop, as a function of Reynolds numbers, was proposed. The measured pressure drop was compared to the predicted pressure drop with some existing pressure drop models that use the newly developed void fraction model. The homogeneous model of void fraction showed the best prediction with 2% deviation

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A New Capacitance Sensor for Measuring the Void Fraction of Two-Phase Flow Through Tube Bundles

Sensors ◽

10.3390/s20072088 ◽

2020 ◽

Vol 20 (7) ◽

pp. 2088

Author(s):

Wael Ahmed ◽

Adib Fatayerji ◽

Ahmed Elsaftawy ◽

Marwan Hassan ◽

David Weaver ◽

...

Keyword(s):

Void Fraction ◽

Two Phase Flow ◽

Tube Bundle ◽

Local Variation ◽

Phase Flow ◽

Capacitance Sensor ◽

Two Phase ◽

Element Analysis ◽

Tube Bundles ◽

The Stability

Evaluating the two-phase flow parameters across tube bundles is crucial to the analysis of vibration excitation mechanisms. These parameters include the temporal and local variation of void fraction and phase redistribution. Understanding these two-phase parameters is essential to evaluating the stability threshold of tube bundle configurations. In this work, capacitance sensor probes were designed using finite element analysis to ensure high sensor sensitivity and optimum response. A simulation-based approach was used to calibrate and increase the accuracy of the void fraction measurement. The simulation results were used to scale the normalized capacitance and minimize the sensor uncertainty to ±5%. The sensor and required conditioning circuits were fabricated and tested for measuring the instantaneous void fraction in a horizontal triangular tube bundle array under both static and dynamic two-phase flow conditions. The static calibration of the sensor was able to reduce the uncertainty to ±3% while the sensor conditioning circuit was able to capture instantaneous void fraction signals with frequencies up to 2.5 kHz.

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