Pressure Drop and Void Fraction in Steam-Water Two-Phase Flow at High Pressure

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Wei Liu ◽  
Hidesada Tamai ◽  
Kazuyuki Takase
Keyword(s):  
High Pressure ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Water Pressure ◽  
Homogeneous Model ◽  
Test Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model

For a steam generator (SG) in a commercialized sodium-cooled fast breeder reactor (FBR), flow instability in the water side is one of the most important items needing research. As the first step of this research, thermal-hydraulic experiments using water as the test fluid were performed under high pressure conditions at the Japan Atomic Energy Agency (JAEA) by using a circular tube. Void fraction, pressure drop, and heat transfer coefficient data were obtained under 15, 17, and 18 MPa. This paper discusses the steam-water pressure drop and void fraction. Using the obtained data, we evaluated existing correlations for void fraction and two-phase flow multipliers under high pressure. As a result, the drift flux model implemented in the TRAC-BF1 code was confirmed to suitably predict the void fraction well under the present high pressure conditions. For the two-phase flow multiplier, the Chisholm correlation and the homogeneous model were confirmed to be the best under the present high-pressure conditions.

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

2016 ◽  
Vol 78 (8-4) ◽  
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

scholarly journals Pressure drop and average void fraction measurements for two-phase flow through highly permeable porous media

2016 ◽  
Vol 94 ◽  
pp. 422-432 ◽  
Author(s):  
N. Chikhi ◽  
R. Clavier ◽  
J.-P. Laurent ◽  
F. Fichot ◽  
M. Quintard
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through

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

2004 ◽  
Vol 126 (4) ◽  
pp. 546-552 ◽  
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.

Axial Development of Vertical Upward Bubbly Flow in a Minipipe

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Naohisa Tamura ◽  
Norihiro Fukamachi ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Constitutive Relations ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using a 1.02 mm-diameter pipe. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 1.02 m/s to 4.89 m/s and from 0.980% to 24.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channel.

Comparison of Drift-Flux Models for Void Fraction Prediction in Sub-Channel of Vertical Rod Bundles

2018 ◽  
Author(s):  
Quanyao Ren ◽  
Liangming Pan ◽  
Wenxiong Zhou ◽  
Tingpu Ye ◽  
Hang Liu ◽  
...  
Keyword(s):  
Void Fraction ◽  
Drift Velocity ◽  
Nuclear Reactor ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Phase Flow ◽  
Rod Bundles ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux

In order to simulate the transfer of mass, momentum and energy in the gas-liquid two-phase flow system, tremendous work focused on the phenomenon, mechanisms and models for two-phase flow in different channels, such as circular pipe, rectangular channel, rod bundle and annulus. Drift-flux model is one of the widely used models for its simplicity and good accuracy, especially for the reactor safety analysis codes (RELAP5 and TRAC et al.) and sub-channel analysis code (COBRA, SILFEED and NASCA et al.). Most of the adopted drift-flux models in these codes were developed based on the void fraction measured in pipe and annulus, which were different with the actual nuclear reactor. Although some drift-flux models were developed for rod bundles, they were based on the void fraction on the whole cross-section not in subchannel in rod bundles due to the lack of effective measuring methods. A novel sub-channel impedance void meter (SCIVM) has been developed to measure the void fraction in sub-channel of 5 × 5 rod bundles, which is adopted to evaluate these existing drift-flux models for rod bundles. By comparison, the values of drift-flux parameters have large differences among different correlations, which are suggested to be reconsidered. Based on the experimental data and physical laws, Lellouche-Zolotar and Chexal-Lellouche correlations show a better performance for drift velocity. If the predicting error of void fraction is the only concerned parameter, Chen-Liu, Ishizuka-Inoue and Chexal-Lellouche correlations are recommended for averaged relative error less than 30%. More experiments are suggested to focus on the distribution parameter and drift velocity through their definition.

Measurement of Void Fraction in Magnetic Fluid Using Electromagnetic Induction

2003 ◽  
Vol 125 (3) ◽  
pp. 479-485 ◽  
Author(s):  
S. Shuchi ◽  
H. Yamaguchi ◽  
M. Takemura
Keyword(s):  
Numerical Analysis ◽  
Linear Relationship ◽  
Void Fraction ◽  
Magnetic Fluid ◽  
Electromagnetic Induction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Actual Measurement ◽  
Drift Flux Model

A new technique of measuring void fraction in magnetic fluid using electromagnetic induction was proposed. In order to establish the measuring method, a feasibility study was conducted experimentally with an aid of numerical analysis. From the results of static experiment and numerical analysis, it was obtained that there exists a linear relationship between the void fraction and the measured electromotive force, when induction coils were connected in series for Helmholtz excitation coils, regardless of distribution of air bubbles in magnetic fluid. By applying the calibrated linear relationship to actual two-phase situations, it was revealed that the proposed method yielded quite reasonable account for measuring the void fraction, showing excellent agreement with the mechanical measured data in the two-phase flow apparatus, and with the published correlation of the drift flux model. From the results of the present investigation, it was proved that the proposed technique is feasible for the actual measurement of void fraction in two-phase flow of magnetic fluid.

Experimental Investigation of Two Phase Flow in Micro-Sized Circular Tubes

2012 ◽  
Author(s):  
Y. S. Lim ◽  
Simon C. M. Yu
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Transitional Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Slip Ratio ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Glass Tubes ◽  
Flux Model

Single phase and two phase flow characteristics in micro-sized glass tubes with i.d. (inner diameter) of 300 and 500 μm have been examined experimentally. Single phase pressure drop measurements are found generally in good agreement with Poiseulle flow theory. Transitional flow is found to start earlier at Reynolds number about 1600 as compared to the onset of transitional flow at Reynolds number of 2300 for macro-scale tubes. In addition, these glass tubes are employed for the investigation of adiabatic two phase flow characteristic by introducing gas phase via a stainless steel tube inserted at the center of the glass tube. Real time flow visualization obtained under the same flow condition are analyzed by both cross sectional void fraction (one dimensional drift flux model) and volumetric void fraction (image processing method). The analysis shows that the void fraction estimated by drift flux model (DFM) agrees with homogeneous correlation (α = β) and Armand correlation (α = 0.833β). However image processing method seems to reveal that the slip ratio for the two phase flow is more significant and that the void fraction results are clustering between slip ratio of 3 and 7. Additionally, two phase frictional pressure losses are compared with the convention correlation for macro-sized tube (Lockhart-Martinelli model). It is found that measurements of the two phase frictional pressure drop can serve as a flow map to predict the flow patterns when the flow in the channel is not transparent.

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