Effect of Size and Slip Coefficient of a Porous Manifold on Thermal Stratification in Storage Tanks

2009 ◽  
Author(s):  
N. M. Brown ◽  
F. C. Lai
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Simulations ◽  
Storage Tank ◽  
Richardson Number ◽  
Thermal Stratification ◽  
Temperature Fields ◽  
Storage Tanks ◽  
Slip Coefficient ◽  
Wide Range

Numerical simulations have been performed to study the effects of size and slip coefficient of a porous manifold on the thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 < Gr < 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 10−2 < Ri < 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.

Numerical Study of Thermal Stratification in a Liquid Storage Tank With a Porous Manifold

Solar Energy ◽  
2006 ◽  
Author(s):  
N. M. Brown ◽  
F. C. Lai
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Storage Tank ◽  
Richardson Number ◽  
Thermal Stratification ◽  
Numerical Study ◽  
Temperature Fields ◽  
Liquid Storage ◽  
Wide Range ◽  
Liquid Storage Tank

A numerical model has been developed to study the effects of a porous manifold on thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 < Gr < 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 0.1 < Ri < 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.

Measurement of Permeability and Slip Coefficient of Porous Tubes

Volume 1 ◽  
2004 ◽  
Author(s):  
N. M. Brown ◽  
F. C. Lai
Keyword(s):  
Reynolds Number ◽  
Wall Thickness ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Porous Wall ◽  
Interface Condition ◽  
Outer Diameter ◽  
Slip Coefficient ◽  
Liquid Storage ◽  
Liquid Storage Tank

Experiments have been conducted to measure the permeability and slip coefficient of seven porous tubes. These tubes are to be used in a liquid storage tank to enhance thermal stratification. They were made from fiberglass and nylon nettings with various wall thicknesses. Six tubes had an outer diameter of 1.9 cm and a thickness ranging from 0.158 cm to 0.635 cm, and the seventh tube had an outer diameter of 10 cm and a thickness of 0.635 cm. Tests show that these tubes have a distinct permeability in the longitudinal and radial directions. As such, both permeabilities of the tubes were measured. In addition, the slip coefficient which is an important parameter in the Beaver-Joseph interface condition was determined. From the results obtained, one can conclude that both permeabilities depend on the material, but the radial permeability also depends on the wall thickness. The slip coefficient depends not only on the material but also on the Reynolds number, permeabilities and porous wall thickness.

scholarly journals One-dimensional Droplet Model for Prediction of Jet-tip Height of Subcooling Mixing Jet for Cryogenic Propellant Storage Tank

2021 ◽  
Author(s):  
Osamu Kawanami ◽  
Kentaro Takeda ◽  
Ryoki Matsushima ◽  
Ryoji Imai ◽  
Yutaka Umemura ◽  
...  
Keyword(s):  
Experimental Data ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Droplet Model ◽  
Spherical Droplet ◽  
One Dimensional ◽  
Long Term Storage ◽  
Proposed Model ◽  
Term Storage

Abstract This study proposes a one-dimensional droplet model to predict the jet-tip height of a subcooling mixing jet issuing from the bottom of a cryogenic propellant storage tank. Cryogenic liquids, such as liquid hydrogen and liquid oxygen, are used as propellants and oxidants in spacecraft propulsion systems that require long-term storage in a closed tank. However, thermal stratification forms near the gas-liquid interface during long-term storage of cryogens due to heat flowing into the tank from the surrounding environment. In addition, boil-off gas (BOG) is generated from the interface, which causes increased pressure in the tank. To reduce the BOG, it is effective to destroy the thermal stratification by mixing in the cold jet issuing from the bottom of the tank. Ground experiments using FC-72 and water as test fluids are conducted to investigate the behavior of the jet using the proposed one-dimensional spherical droplet model as the tip of the jet. The jet behavior is visualized using the Shadowgraph system and the height of the jet-tip is investigated under various experimental conditions. The proposed model is also verified by comparison with experimental data available in the literature. The results show that the proposed model aligns well with the experimental data.

scholarly journals Numerical Simulations of Temperature and Velocity Fields in the Storage Tank with the Three-Coil Heat Exchanger

2020 ◽  
Vol 44 (3) ◽  
pp. 74-79
Author(s):  
Robert Smusz ◽  
Joanna Wilk ◽  
Paweł Bałon
Keyword(s):  
Numerical Simulations ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Waste Heat ◽  
Velocity Fields ◽  
Operating Conditions ◽  
Hot Water ◽  
Water Storage Tank ◽  
Coil Heat Exchanger ◽  
Temperature And Velocity Fields

AbstractThis article presents the results of the numerical investigation of the thermal stratification in the hot water storage tank. The exchanger consists of three tube coils that are immersed in the storage tank of hot water. Two coils—lower and upper—are designed to warm the water in the tank using the water as a heating medium. Another coil—uses the refrigerant for the waste heat transfer. The temperature stratification device is mounted in the thermal storage tank. The device’s task is to improve the thermal stratification level of heated water. The performed numerical simulations allowed us to obtain the temperature and velocity fields in the storage tank under the conditions of the work of coils filled with water. Calculations were made in the case of the use of the stratification device under the operating conditions of the upper and lower coils with water.

A Method of Determining Unified Viscoplastic Constitutive Equations for Hot Forging Simulations

2016 ◽  
Vol 716 ◽  
pp. 251-261 ◽  
Author(s):  
Nicholas J. Politis ◽  
Denis J. Politis ◽  
Catrin Mair Davies ◽  
Jian Guo Lin
Keyword(s):  
Experimental Data ◽  
Genetic Algorithm ◽  
Numerical Simulations ◽  
Material Properties ◽  
Constitutive Equations ◽  
Hot Forging ◽  
Strain Rates ◽  
Algorithmic Method ◽  
Wide Range ◽  
Algorithm Implementation

Constitutive equations have been used extensively to accurately describe material properties over a wide range of temperatures and strain rates in numerical simulations. In this paper, an algorithmic method of determining the constants of such constitutive equations is presented. The Genetic Algorithm implementation utilising MATLAB is described, and example fits to experimental data are presented.

The Effect of Obstacle Geometry and Position on Thermal Stratification in Solar Hot Water Storage Tanks

2008 ◽  
Author(s):  
Necdet Altuntop ◽  
Veysel Ozceyhan ◽  
Yusuf Tekin ◽  
Sibel Gunes
Keyword(s):  
Storage Tank ◽  
Thermal Stratification ◽  
Water Storage ◽  
Hot Water ◽  
Storage Tanks ◽  
Domestic Hot Water ◽  
Water Storage Tank ◽  
Temperature Distributions ◽  
Solar Powered ◽  
Obstacle Geometry

In this study the effect of obstacle geometry and its position on thermal stratification in solar powered domestic hot water storage tanks are numerically investigated. The goal of this study is to obtain higher thermal stratification and supply hot water for usage as long as possible. The temperature distributions are presented for three different obstacle geometries (1, 2 and 3) and six different distances (f = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 mm) from the bottom of the hot water storage tank. The numerical method is validated using both experimental and numerical results available in the literature. It is observed from the results that the thermal stratification increases with the increasing obstacle distance from the bottom of the hot water storage tank for obstacle 1 and 3. The obstacle 2 provides less thermal stratification than the obstacles 1 and 3. As a result, in a duration of 30 minutes, the obstacle 3 provides the best thermal stratification for the distance of f = 0.8 mm from the bottom of the hot water storage tank.

scholarly journals Spectral analysis of the transition to turbulence from a dipole in stratified fluid

2012 ◽  
Vol 713 ◽  
pp. 86-108 ◽  
Author(s):  
Pierre Augier ◽  
Jean-Marc Chomaz ◽  
Paul Billant
Keyword(s):  
Reynolds Number ◽  
Spectral Analysis ◽  
Kinetic Energy ◽  
Numerical Simulations ◽  
Scaling Laws ◽  
Stratified Fluid ◽  
Shear Instability ◽  
Transition To Turbulence ◽  
Small Scale ◽  
Wide Range

AbstractWe investigate the spectral properties of the turbulence generated during the nonlinear evolution of a Lamb–Chaplygin dipole in a stratified fluid for a high Reynolds number $Re= 28\hspace{0.167em} 000$ and a wide range of horizontal Froude number ${F}_{h} \in [0. 0225~0. 135] $ and buoyancy Reynolds number $\mathscr{R}= Re{{F}_{h} }^{2} \in [14~510] $. The numerical simulations use a weak hyperviscosity and are therefore almost direct numerical simulations (DNS). After the nonlinear development of the zigzag instability, both shear and gravitational instabilities develop and lead to a transition to small scales. A spectral analysis shows that this transition is dominated by two kinds of transfer: first, the shear instability induces a direct non-local transfer toward horizontal wavelengths of the order of the buoyancy scale ${L}_{b} = U/ N$, where $U$ is the characteristic horizontal velocity of the dipole and $N$ the Brunt–Väisälä frequency; second, the destabilization of the Kelvin–Helmholtz billows and the gravitational instability lead to small-scale weakly stratified turbulence. The horizontal spectrum of kinetic energy exhibits a ${{\varepsilon }_{K} }^{2/ 3} { k}_{h}^{\ensuremath{-} 5/ 3} $ power law (where ${k}_{h} $ is the horizontal wavenumber and ${\varepsilon }_{K} $ is the dissipation rate of kinetic energy) from ${k}_{b} = 2\lrm{\pi} / {L}_{b} $ to the dissipative scales, with an energy deficit between the integral scale and ${k}_{b} $ and an excess around ${k}_{b} $. The vertical spectrum of kinetic energy can be expressed as $E({k}_{z} )= {C}_{N} {N}^{2} { k}_{z}^{\ensuremath{-} 3} + C{{\varepsilon }_{K} }^{2/ 3} { k}_{z}^{\ensuremath{-} 5/ 3} $ where ${C}_{N} $ and $C$ are two constants of order unity and ${k}_{z} $ is the vertical wavenumber. It is therefore very steep near the buoyancy scale with an ${N}^{2} { k}_{z}^{\ensuremath{-} 3} $ shape and approaches the ${{\varepsilon }_{K} }^{2/ 3} { k}_{z}^{\ensuremath{-} 5/ 3} $ spectrum for ${k}_{z} \gt {k}_{o} $, ${k}_{o} $ being the Ozmidov wavenumber, which is the cross-over between the two scaling laws. A decomposition of the vertical spectra depending on the horizontal wavenumber value shows that the ${N}^{2} { k}_{z}^{\ensuremath{-} 3} $ spectrum is associated with large horizontal scales $\vert {\mathbi{k}}_{h} \vert \lt {k}_{b} $ and the ${{\varepsilon }_{K} }^{2/ 3} { k}_{z}^{\ensuremath{-} 5/ 3} $ spectrum with the scales $\vert {\mathbi{k}}_{h} \vert \gt {k}_{b} $.

Numerical Simulations of Laminar Backward-Facing Step Flow With FEMLAB 3.1

2005 ◽  
Author(s):  
Carlo Gualtieri
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Simulations ◽  
Close Agreement ◽  
Velocity Profiles ◽  
Channel Height ◽  
Backward Facing Step ◽  
Step Flow ◽  
Dimensionless Velocity

The paper presents 2-D numerical simulations of laminar backward-facing step flow using the FemLab 3.1 modeling package. Results demonstrated that primary reattachment lengths predicted by FemLab were in close agreement with experimental data up to step Reynolds number Reh = 300. Also, dimensionless velocity profiles along the channel height calculated by FemLab were successfully compared with the experimental data.

scholarly journals New Perspective for Heat Transfer Evaluation During Film Condensation Inside Tubes

2021 ◽  
Vol 39 (2) ◽  
pp. 390-402
Author(s):  
Yanán Camaraza-Medina
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Single Phase ◽  
Film Condensation ◽  
Mean Deviation ◽  
Two Phase ◽  
Wide Range ◽  
The Mean ◽  
Vertical Tubes

This paper presents the main results of the research developed by the author in his postdoctoral investigations on heat transfer calculations during film condensation inside tubes. The elements studied are combined in an analysis expression that provides a reasonable fit with the available experimental data, which includes a total of 22 fluids, including water, refrigerants and a wide range of organic substances, which condense inside horizontal, inclined and vertical tubes. These experimental data were obtained from the reports of 33 sources. Available data covers tube diameters from 2 to 50 mm, mass flow rates from 3 to 850 kg/(m2s), reduced pressures ranging from 0.0008 to 0.91, values for single-phase from 1 to , Reynolds number for two-phase from 900 to 594390, Reynolds number for single-phase from 65 to 84950 and vapor quality from 0.01 to 0.99. The mean deviation found for the analyzed data for horizontal tubes was 13.4%, while for the inclined and vertical tubes data the mean deviation was 14.9%. In all cases, the agreement of the proposed model is good enough to be considered satisfactory for practical design.

Investigation Of The Air Flow In Heated Highly Porous Cellular Materials

2017 ◽  
Vol 12 (2) ◽  
pp. 66-74
Author(s):  
Sergey Mironov ◽  
Tatyana Poplavskaya ◽  
Stanislav Kirilovskiy
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Porous Material ◽  
Filtration Rate ◽  
Cellular Materials ◽  
Air Filtration ◽  
Wide Range ◽  
Highly Porous Cellular Materials ◽  
Skeletal Model ◽  
Highly Porous

Measurements of air filtration rate through the highly porous cellular materials in the presence of heating a porous material were carried out. A new measurement technique was developed and data of the dependence of the filtration rate of the temperature of air passing through the porous material were obtained with different pore size and in wide range Reynolds number. The experimental data were compared with the results of numerical modeling of the airflow in the porous samples, based on skeletal model of the cellular-porous material.

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