Interaction Between Water or Air-Water Bubble Flow and Tube Bundle—Effects of Arrangement of Tube Bundle and Void Fraction

2018 ◽  
pp. 111-116
Author(s):  
Toshihiko Shakouchi ◽  
Takeshi Kitamura ◽  
Koichi Tsujimoto ◽  
Toshitake Ando
Keyword(s):  
Void Fraction ◽  
Tube Bundle ◽  
Bubble Flow

scholarly journals On Damping and Fluidelastic Instability in a Tube Bundle Subjected to Two-Phase Cross-Flow

2007 ◽  
Author(s):  
Joaquin E. Moran ◽  
David S. Weaver
Keyword(s):  
Flow Regime ◽  
Void Fraction ◽  
Tube Bundle ◽  
Damping Ratio ◽  
Pressure Fluctuations ◽  
Cross Flow ◽  
Phase Changes ◽  
Working Fluid ◽  
Two Phase ◽  
Fluidelastic Instability

An experimental study was conducted to investigate damping and fluidelastic instability in tube arrays subjected to two-phase cross-flow. The purpose of this research was to improve our understanding of these phenomena and how they are affected by void fraction and flow regime. The working fluid used was Freon 11, which better models steam-water than air-water mixtures in terms of vapour-liquid mass ratio as well as permitting phase changes due to pressure fluctuations. The damping measurements were obtained by “plucking” the monitored tube from outside the test section using electromagnets. An exponential function was fitted to the tube decay trace, producing consistent damping measurements and minimizing the effect of frequency shifting due to fluid added mass fluctuations. The void fraction was measured using a gamma densitometer, introducing an improvement over the Homogeneous Equilibrium Model (HEM) in terms of density and velocity predictions. It was found that the Capillary number, when combined with the two-phase damping ratio (interfacial damping), shows a well defined behaviour depending on the flow regime. This observation can be used to develop a better methodology to normalize damping results. The fluidelastic results agree with previously presented data when analyzed using the HEM and the half-power bandwidth method. The interfacial velocity is suggested for fluidelastic studies due to its capability for collapsing the fluidelastic data. The interfacial damping was introduced as a tool to include the effects of flow regime into the stability maps.

Drag Coefficient and Two-Phase Friction Multiplier on Tube Bundles Subjected to Two-Phase Cross-Flow

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
W. G. Sim ◽  
Njuki W. Mureithi
Keyword(s):  
Drag Coefficient ◽  
Void Fraction ◽  
Euler Number ◽  
Tube Bundle ◽  
Cross Flow ◽  
Water Mixture ◽  
Duct Flow ◽  
Two Phase ◽  
Mass Fluxes ◽  
Wide Range

An approximate analytical model, to predict the drag coefficient on a cylinder and the two-phase Euler number for upward two-phase cross-flow through horizontal bundles, has been developed. To verify the model, two sets of experiments were performed with an air–water mixture for a range of pitch mass fluxes and void fractions. The experiments were undertaken using a rotated triangular (RT) array of cylinders having a pitch-to-diameter ratio of 1.5 and cylinder diameter 38 mm. The void fraction model proposed by Feenstra et al. was used to estimate the void fraction of the flow within the tube bundle. An important variable for drag coefficient estimation is the two-phase friction multiplier. A new drag coefficient model has been developed, based on the single-phase flow Euler number formulation proposed by Zukauskas et al. and the two-phase friction multiplier in duct flow formulated by various researchers. The present model is developed considering the Euler number formulation by Zukauskas et al. as well as existing two-phase friction multiplier models. It is found that Marchaterre's model for two-phase friction multiplier is applicable to air–water mixtures. The analytical results agree reasonably well with experimental drag coefficients and Euler numbers in air–water mixtures for a sufficiently wide range of pitch mass fluxes and qualities. This model will allow researchers to provide analytical estimates of the drag coefficient, which is related to two-phase damping.

Two-Phase Void Fraction and Pressure Drop in Horizontal Crossflow Across a Tube Bundle

1998 ◽  
Vol 120 (1) ◽  
pp. 140-145 ◽  
Author(s):  
G. P. Xu ◽  
K. W. Tou ◽  
C. P. Tso
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Mass Velocity ◽  
Flow Model ◽  
Tube Bundle ◽  
Diameter Ratio ◽  
Two Phase ◽  
Friction Pressure ◽  
Oil Flow ◽  
Friction Pressure Drop

Void fraction and friction pressure drop measurements were made for an adiabatic, horizontal two-phase flow of air-water, air-oil across a horizontal in-line, 5 × 20 tube bundle with pitch-to-diameter ratio, P/D, of 1.28. For both air-water and air-oil flow, the experimental results showed that the average void fraction were less than the values predicted by a homogenous flow model, but were well correlated with the Martinelli parameter Xtt and liquid-only Froude number FrLO. The two-phase friction multiplier data exhibited an effect of flow pattern and mass velocity, and they could be well-correlated with the Martinelli parameter.

Effect of Void Fraction on Vibrational Behavior of Tubes in Tube Bundle Under Two-Phase Cross Flow

1997 ◽  
Vol 119 (3) ◽  
pp. 457-463 ◽  
Author(s):  
H. Y. Lian ◽  
G. Noghrehkar ◽  
A. M. C. Chan ◽  
M. Kawaji
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Tube Bundle ◽  
Dynamic Pressure ◽  
Damping Ratio ◽  
Cross Flow ◽  
Vibration Measurement ◽  
Phase Flow ◽  
Two Phase ◽  
Vibrational Behavior

The effects of local two-phase flow parameters on the vibrational behavior of tubes have been studied in an in-line 5 × 20 tube bundle subjected to air-water cross-flow. One of the tubes was flexibly mounted and instrumented for vibration measurement and the others were rigid. Parameters obtained include local void fraction fluctuations, RMS amplitude of void fraction fluctuations, void fraction distributions across the tube bundle, flow regimes based on probability density function of void fraction signals, damping ratio, and tube vibration response as a function of mass flux, void fraction and dynamic pressure. Damping and tube vibration amplitude in two-phase flow have been found to be closely related to the RMS amplitudes of the local void fraction fluctuations and dynamic pressure fluctuations, respectively.

Numerical Investigation of Air/Water and Hydrogen/Diesel Flow Across Tube Bundles With Baffles

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Diego N. Venturi ◽  
Waldir P. Martignoni ◽  
Dirceu Noriler ◽  
Henry F. Meier
Keyword(s):  
Void Fraction ◽  
Volume Fraction ◽  
Tube Bundle ◽  
Superficial Velocity ◽  
Intermittent Flow ◽  
Two Phase ◽  
Operational Conditions ◽  
Horizontal Flows ◽  
Tube Bundles ◽  
Experimental Approaches

Two-phase flows across tube bundles are very commonly found in industrial heat exchange equipment such as shell and tube heat exchangers. However, recent studies published in the literature are generally performed on devices where the flow crosses the tube bundle in only a vertical or horizontal direction, lacking geometrical fidelity with industrial models, and the majority of them use air and water as the working fluids. Also, currently, experimental approaches and simulations are based on very simplified models. This paper reports the simulation of a laboratory full-scale tube bundle with a combination of vertical and horizontal flows and with two different baffle configurations. Also, it presents a similarity analysis to evaluate the influence of changing the fluids to hydrogen and diesel in the operational conditions of the hydrotreating. The volume of fluid (VOF) approach is used as the interface phenomena are very important. The air/water simulations show good agreement with classical correlations and are able to show the stratified behavior of the flow in the horizontal regions and the intermittent flow in the vertical regions. Also, the two baffle configurations are compared in terms of volume fraction and streamlines. When dealing with hydrogen/diesel flow using correlations and maps made for air/water, superficial velocity is recommended as similarity variable when a better prediction of the pressure drop is needed, and the modified superficial velocity is recommended for prediction of the volume-average void fraction and the outlet superficial void fraction.

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

Sensors ◽  
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.

0206 Measurement of void fraction distribution around tube in two-phase flow across a horizontal tube bundle

2013 ◽  
Vol 2013 (0) ◽  
pp. _0206-01_-_0206-02_
Author(s):  
Kota MIKAMI ◽  
Hideki MURAKAWA ◽  
Katsumi SUGIMOTO ◽  
Nobuyuki TAKENAKA
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Tube Bundle ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fraction Distribution ◽  
Fraction Distribution

Different Type Tube Bundle Heat Transfer to Vertical Foam Flow

2007 ◽  
Author(s):  
Jonas Gylys ◽  
Stasys Sinkunas ◽  
Tadas Zdankus ◽  
Vidmantas Giedraitis
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Flow Velocity ◽  
Void Fraction ◽  
Tube Bundle ◽  
Auxiliary Equipment ◽  
Foam Flow ◽  
Flow Parameters ◽  
Tube Bundles ◽  
Foam Generator

Gas-liquid foam due to especially large inter-phase contact surface can be used as a coolant. An experimental investigation of the staggered and in-line tube bundles’ heat transfer to the vertically upward and downward laminar foam flow was performed. The experimental setup consisted of the foam generator, vertical experimental channel, tube bundles, measurement instrumentation and auxiliary equipment. It was determined dependency of heat transfer intensity on flow parameters: flow velocity, direction of flow, volumetric void fraction of foam and liquid drainage from foam. Apart of this, influence of tube position in the bundle to heat transfer was investigated. Foam flow structure, distribution of the foam’s local void fraction and flow velocity in cross-section of the channel were the main factors which influenced on heat transfer intensity of the different tubes. Experimental investigation showed that the heat transfer intensity of the frontal and further tubes of the bundles to vertical foam flow is different in comparison with one-phase fluid flow. The results of the experimental investigation are presented in this paper.

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