scholarly journals Numerical parametric study of a cooling system for an LNG storage tank

2019 ◽  
Vol 74 ◽  
pp. 21 ◽  
Author(s):  
Mohamed Haddar ◽  
Moez Hammami ◽  
Mounir Baccar
Keyword(s):  
Heat Transfer ◽  
Lateral Surface ◽  
Storage Tank ◽  
Cooling System ◽  
Liquefied Natural Gas ◽  
Cylindrical Tank ◽  
Heat Gain ◽  
Nusselt Numbers ◽  
Numerical Parametric Study ◽  
Volume Method

The study of the cooling system of a Liquefied Natural Gas (LNG) storage tank is vital for the safety of the installation. The objective of this paper is to develop cooling baffles capable of reducing the heat gain from the environment leading to a loss of LNG quantity, keeping the Boil-Off Gas (BOG) under control. For this purpose, a specific code based on the finite volume method was developed to improve our knowledge of the hydrodynamic and thermal behaviors of LNG in the cylindrical tank. In addition, the effect of the number, position and dimension of the baffles on the flow structure of LNG were determined. The obtained results indicated that the location of the baffles at the top of the tank nearby the vicinity of the wall would yield a better cooling of the LNG. Moreover, we emphasized that a number of six baffles would give rise to a better heat transfer. For a design purpose, the Nusselt numbers on the lateral surface and on the baffles have been correlated as functions of Rayleigh and baffle numbers.

Numerical study of steady natural convection in a liquefied natural gas cylindrical storage tank equipped with baffles

2019 ◽  
Vol 234 (5) ◽  
pp. 709-721 ◽  
Author(s):  
Mohamed Haddar ◽  
Moez Hammami ◽  
Mounir Baccar
Keyword(s):  
Rayleigh Number ◽  
Natural Gas ◽  
Lateral Surface ◽  
Storage Tank ◽  
Cooling System ◽  
Numerical Study ◽  
Gas Storage ◽  
Liquefied Natural Gas ◽  
Natural Gas Storage ◽  
Average Temperature

In this paper, a study of cooling system for a liquefied natural gas storage tank is conducted. Our objective is to remedy the heat ingress to the liquefied natural gas from the environment using baffles toward limiting temperature elevation in the tank, and then the Boil-off Gas (BOG) formation. A specific code based on the finite volume method is developed to supply a fine knowledge of the hydrodynamic and thermal liquefied natural gas characteristics in the cylindrical tank heated from bottom and lateral surfaces. The effect of the number, position and dimension of baffles, on the flow structure and thermal behavior, has been analyzed. According to our simulation results, the baffles should be placed at the top of tank nearby the lateral wall as the liquefied natural gas dimensionless average temperature can be reduced by 36%. The installation of four rectangular baffles, equally spaced around the perimeter of the tank, gives better homogenization of the temperature field and decreases the average temperature by about 44% in order to limit BOG formation. Finally, two correlations of the Nusselt number are established for the flat rectangular baffle plates and the lateral surface of the cylindrical liquefied natural gas storage tank as a function of the Rayleigh number, as well as the baffle number. Scaling of these correlations with the Rayleigh number gives exponents of 0.25 and 0.18 for lateral surface and baffle, respectively, which are in good agreement with literature.

A Numerical Parametric Study of the Growth of Ice Formation Around a Vertical Tube, During the Full Charging Process of an Indirect, Area-Constrained, Ice-on-Pipe Storage Tank

2003 ◽  
Author(s):  
Cleyton S. Stampa ◽  
Angela O. Nieckele ◽  
Sergio L. Braga
Keyword(s):  
Heat Transfer ◽  
Storage Tank ◽  
Vertical Wall ◽  
Vertical Tube ◽  
Layer Growth ◽  
Ice Storage ◽  
Vertical Annulus ◽  
Numerical Parametric Study ◽  
Volume Method ◽  
The Mathematical Model

A parametric numerical investigation regarding the ice layer growth outside a vertical tube is investigated. It encompasses heat transfer and removal of energy, applicable to indirect, area-constrained, ice-on-pipe storage tanks. The study is carried out in a vertical annulus, with the inner vertical wall representing one of the tubes packed into a typical storage tank. Further, the outer vertical wall determines the maximum border for the ice layer growth under the conditions established in the present study, corresponding to a full charging process in such devices. Our task is to provide helpful qualitative results for the investigation of ice storage tank heat transfer performance, considering changes in the following parameters: aspect ratio, radius ratio, Grashof and Stefan numbers. For the mathematical model adopted to simulate transient natural convection of water with phase-change (solidification), it was utilized a model based on the finite volume method to solve the set of coupled conservation equations of mass, momentum and energy.

scholarly journals Effect of Rayleigh Number on Internal Eccentricity in a Heated Horizontal Elliptical Cylinder to its Coaxial Square Enclosure

2020 ◽  
Vol 25 (3) ◽  
pp. 17-29
Author(s):  
Abdelkrim Bouras ◽  
Djedid Taloub ◽  
Zied Driss
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Outer Cylinder ◽  
Boussinesq Approximation ◽  
Square Enclosure ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Commercial Code ◽  
Volume Method ◽  
Rayleigh Numbers

AbstractThis paper deals with numerical investigation of a natural convective flow in a horizontal annular space between a heated square inner cylinder and a cold elliptical outer cylinder with a Newtonian fluid. Uniform temperatures are imposed along walls of the enclosure. The governing equations of the problem were solved numerically by the commercial code Fluent, based on the finite volume method and the Boussinesq approximation. The effects of Geometry Ratio GR and Rayleigh numbers on fluid flow and heat transfer performance are investigated. The Rayleigh number is varied from 103 to 106. Throughout the study the relevant results are presented in terms of isotherms, and streamlines. From the results, we found that the increase in the Geometry Ratio B leads to an increase of the heat transfer coefficient. The heat transfer rate in the annulus is translated in terms of the average Nusselt numbers along the enclosure’s sides. Tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. The results for the streamlines, isotherms, local and average Nusselt numbers average Nusselt numbers are compared with previous works and show good agreement.

Numerical Analysis of Heat Transfer and Flow Stability in an Open Rotating Cavity Using the Maximum Entropy Production Principle

2010 ◽  
Author(s):  
D. Bohn ◽  
R. Krewinkel ◽  
A. Wolff
Keyword(s):  
Heat Transfer ◽  
Entropy Production ◽  
Maximum Entropy ◽  
Gas Turbines ◽  
Cooling System ◽  
Numerical Study ◽  
Internal Cooling ◽  
Maximum Entropy Production ◽  
Nusselt Numbers ◽  
Rotating Cavity

The flow field and heat transfer in the internal cooling system of gas turbines can be modelled using rotating-disc systems with axial throughflow. Because of the complexity of these flows, in which buoyancy-induced phenomena are of the utmost importance, numerical studies are notoriously difficult to perform and need extensive experimental validation. J.M. Owen proposed using the Maximum Entropy Production (MEP) Principle as a possible means of simplifying numerical computations for these complex flows. This theory is based on the heat flux out of the cavity. In this numerical study, the Nusselt numbers on the disc walls inside an open rotating cavity with a Rayleigh number of approximately 4.97×108 are evaluated with regard to the computed Nusselt numbers on the disc walls. These can be considered to be representative of the flow inside the cavity. It is shown that, as predicted by Owen, the flow is stable when the heat transfer out of the cavity is maximised, or, conversely, the system is unstable when the heat transfer is minimised. Furthermore, it is proven that the level of the Nusselt number plays an important role for the change between the number of vortex pairs in the flow as well.

Turbulent Heat Transfer in an Enclosure With a Horizontal Permeable Plate in the Middle

2006 ◽  
Vol 128 (11) ◽  
pp. 1122-1129 ◽  
Author(s):  
Edimilson J. Braga ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Porous Plate ◽  
Porous Matrix ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Turbulent Natural Convection ◽  
Nusselt Numbers ◽  
Model Solutions ◽  
Volume Method ◽  
Rayleigh Numbers

Turbulent natural convection in a vertical two-dimensional square cavity, isothermally heated from below and cooled at the upper surface, is numerically analyzed using the finite volume method. The enclosure has a thin horizontal porous obstruction, made of a highly porous material and extremely permeable, located at the cavity midheight. Governing equations are written in terms of primitive variables and are recast into a general form. For empty cavities, no discrepancies result for the Nusselt number when laminar and turbulent model solutions are compared for Rayleigh numbers up to 107. Also, in general the porous obstruction decreases the heat transfer across the heated walls showing overall lower Nusselt numbers when compared with those without the porous obstruction. However, the presence of a porous plate in the cavity seems to force an earlier separation from laminar to turbulence model solutions due to higher generation rates of turbulent kinetic energy into the porous matrix.

Use of a Shroud and Baffle to Improve Natural Convection to Immersed Heat Exchangers

2010 ◽  
Author(s):  
S. K. S. Boetcher ◽  
F. A. Kulacki ◽  
Jane H. Davidson
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
High Performance ◽  
Discharge Process ◽  
Thermal Systems ◽  
Water Storage Tank ◽  
Nusselt Numbers ◽  
Commercial Applications ◽  
Thermal Stores

Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which charge and discharge are accomplished using a heat exchanger immersed in the storage fluid. The objective is to investigate the use of a baffle and shroud as a means to improve convective heat transfer and thermal stratification. The immersed heat exchanger is modeled as a two-dimensional isothermal cylinder which is situated near the top of a storage tank with adiabatic walls. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient Nusselt numbers are calculated for different baffle-shroud geometries and Rayleigh numbers. Results indicate that a long baffle with a high shroud height is optimal.

Effects of Vortex Generators on the Impingement Jet Arrays Heat Transfer

2021 ◽  
Author(s):  
Yue Yang ◽  
Junkui Mao ◽  
Feilong Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
Pressure Loss ◽  
Cooling System ◽  
Jet Impingement ◽  
Vortex Generators ◽  
Maximum Enhancement ◽  
Impingement Jet ◽  
Nusselt Numbers ◽  
Impingement Heat Transfer

Abstract In the jets array cooling system of the gas turbine, the downstream jets will be deflected by the crossflow and the heat transfer in the downstream will be suppressed. In this paper, the rectangular vortex generators are arranged in the jet arrays to enhance the jet impingement heat transfer. Through the numerical simulations, the configuration of rectangular vortex generators (Common-flow-down CFD and Common-flow-up CFU) and the relative position (l2) between the impingements and the rectangular vortex generators are studied. The results show that both of configurations are beneficial to the suppression of the crossflow and enhance the heat transfer in the downstream. The maximum enhancement of the whole regional average Nusselt numbers in CFD-VGs configuration can reach up to 9.09% with lower than 5% increase of the pressure loss and that in CFU-VGs configuration can reach up to 10.8% with lower than 4.8% increase of the pressure loss. From the perspective of the whole regional average Nusselt numbers and the overall thermal efficiency, the CFD-VGs with l2 = 0 has the best performance. However, from the perspective of the whole regional average Nusselt numbers, the CFU-VGs with l2 = 0 has the best performance, while from the perspective of the overall thermal efficiency, the CFU-VGs with l2 = 3 has the best performance.

A Study on the Heat Transfer Enhancement in Magnetron Sputtering System

2007 ◽  
Author(s):  
Jae-Sang Baik ◽  
Youn-Jea Kim
Keyword(s):  
Heat Transfer ◽  
Magnetron Sputtering ◽  
Flow Rate ◽  
Cooling System ◽  
Current Trend ◽  
Cooling Water ◽  
Simple Algorithm ◽  
Commercial Code ◽  
Volume Method ◽  
Sputtering System

Magnetron sputtering systems have been widely used in the field of thin film technologies, such as making ultra-thin semiconductors, metal films, etc. The feature of magnetron sputtering system is used high voltage and electric current as the power of system. The energy is converted to heat which must be removed by the appropriate cooling system. Otherwise, it may damage the target, the magnets, and the substrate as well. Also, the current trend of magnetron sputtering is towards that with larger size of target, which can improve the efficiency. Consequently, heat transfer of magnetron sputtering system becomes complex and needs to develop more efficient cooling system. The main parameters affecting the cooling performance are the flow path of cooling water and flow rate. In this study, we investigated the characteristics of cooling effect with various flow paths of cooling water and flow rates. Using a commercial code, FLUENT, which uses FVM (Finite Volume Method) and SIMPLE algorithm, the governing equations have been solved for the pressure, mass flow rate, and temperature distributions in the magnetron sputtering system.

scholarly journals Heat Transfer Potentiality and Flow Behavior in a Square Duct Fitted with Double-Inclined Baffles: A Numerical Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Numerical Models ◽  
Flow Behavior ◽  
Square Duct ◽  
Square Channel ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Commercial Code ◽  
Volume Method

Numerical analysis of heat transfer mechanisms and flow topologies for the heat exchanger square channel (HESC) installed with the double-inclined baffles (DIB) is reported. The main objective of the present research is to study the influences of DIB height to duct height ( b / H = 0.05 – 0.30 ), DIB distance to duct height ( P / H = 1 – 1.5 ), and flow attack angle ( α = 30 °   and   45 ° ) on the flow topologies, heat transfer features, and thermal performances. The Reynolds numbers (based on the entry HESC around 100–2000) are analyzed for the present problem. The numerical models of the HESC installed with the DIB are solved with finite volume method (commercial code). The simulated results of the HESC installed with the DIB are reported in forms of flow topologies and heat transfer characteristics. The Nusselt numbers (Nu), friction factors ( f ), and thermal enhancement factors (TEF) of the HESC placed with the DIB are offered. As the numerical results, it is seen that the DIB produces the vortex streams and impinging streams in all cases. The vortex streams and impinging streams disturb the thermal boundary layer on the HESC walls that is a key motive for the growth of heat transfer rate. The best TEF of the HESC installed with the DIB is about 3.87 at P / H = 1 , α = 30 ° , Re = 2000 , and b / H = 0.15 . Additionally, the TEF contours, which help to design the HESC inserted with the DIB, are performed.

scholarly journals Numerical investigation of fluid flow and heat transfer around a circular cylinder utilizing nanofluid for different thermal boundary condition in the steady regime

10.30544/292 ◽  
2017 ◽  
Vol 23 (2) ◽  
pp. 131-141
Author(s):  
Rafik Bouakkaz ◽  
F. Salhi ◽  
Y. Khelili ◽  
M. Ouazzazi ◽  
K. Talbi
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Reynolds Numbers ◽  
Uniform Heat Flux ◽  
Constant Wall Temperature ◽  
Steady Regime ◽  
Volume Fractions ◽  
Thermal Boundary Conditions ◽  
Nusselt Numbers ◽  
Volume Method

In this work, steady flow-field and heat transfer through a copper–water nanofluid around a circular cylinder, under the influence of both the standard thermal boundary conditions i.e. uniform heat flux (UHF) and constant wall temperature (CWT) was investigated numerically by using a finite-volume method for Reynolds numbers of 10 to 40. Furthermore, the range of nanoparticle volume fractions (φ) considered is 0 ≤ φ ≤ 5%. The variation of the local and the average Nusselt numbers with Reynolds number, and volume fractions are presented for the range of conditions. The average Nusselt number is found to increase with increasing the nanoparticle volume fractions.

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