Passive Heat Transfer in Porous Enclosures Using a Two-Energy Equation Model

2012 ◽  
Author(s):  
Marcelo J. S. deLemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Heat Transfer ◽  
Energy Equation ◽  
Equation Model ◽  
Thermal Conductivity Ratio ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Energy Models ◽  
Different Temperatures ◽  
Volume Method ◽  
Generalized Coordinate

This paper presents computations for natural convection within a porous cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for two energy models and distinct solid-to-fluid thermal conductivity ratio.

Laminar Free Convection in Inclined Enclosures Filled With a Fluid Saturated Porous Medium

Volume 1 ◽  
2004 ◽  
Author(s):  
Edimilson J. Braga ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Medium ◽  
Saturated Porous Medium ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Temperatures ◽  
Laminar Natural Convection ◽  
Fluid Saturated Porous Medium ◽  
Volume Method ◽  
Generalized Coordinate ◽  
Good Agreement

Detailed numerical computations for steady-state laminar natural convection within in oblique cavities totally filled with a fluid saturated porous medium is numerically analyzed using the finite volume method in a generalized coordinate system. The inclined walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics, (streamlines, isotherms and average Nusselt number), are investigated for Rayleigh number ranging from 103 to 104 and inclined angles ranging from 0° to 45°. In general, present results show good agreement with previous works. Analyses of important environmental and engineering flows can benefit from the derivations herein and, ultimately, it is expected that additional research on this new subject be stimulated by the work here presented.

scholarly journals The Influence of Different Types of Nanofluid on Thermal and Fluid Flow Performance of Liquid Cold Plate

2018 ◽  
Vol 7 (4.35) ◽  
pp. 148 ◽  
Author(s):  
Nur Irmawati Om ◽  
Rozli Zulkifli ◽  
P. Gunnasegaran
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Cold Plate ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Types ◽  
Volume Method

The influence of utilizing different nanofluids types on the liquid cold plate (LCP) is numerically investigated. The thermal and fluid flow performance of LCP is examined by using pure ethylene glycol (EG), Al2O3-EG and CuO-EG. The volume fraction of the nanoparticle for both nanofluid is 2%. The finite volume method (FVM) has been used to solved 3-D steady state, laminar flow and heat transfer governing equations. The presented results indicate that Al2O3-EG able to provide the lowest surface temperature of the heater block followed by CuO-EG and EG, respectively. It is also found that the pressure drop and friction factor are higher for Al2O3-EG and CuO-EG compared to the pure EG.

Non-Uniform Heating Condition Effects in Microchannels of the MTPV Systems

2013 ◽  
Vol 437 ◽  
pp. 120-123
Author(s):  
Ge Ping Wu ◽  
Ping Lu ◽  
Jun Wang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heating Condition ◽  
Governing Equations ◽  
Uniform Heating ◽  
Simple Method ◽  
Flow And Heat Transfer ◽  
Microchannel Cooling ◽  
Cooling Passage ◽  
Volume Method

Heat transfer and fluid flow in the microchannel cooling passages of plane cell type MTPV systems are numerically investigated. The Finite Volume method is adopted for the governing equations discretization; The SIMPLE method is applied to deal with the linkage between pressure and velocities. The microscale effects, such as surface roughness and viscous dissipation are taken into account. Influence of non-uniform heating condition on the flow and heat transfer characteristics of the microchannel cooling passage was discussed. The computer simulations were validated by the experiment data. Numerical results confirm that the effects of non-uniform heating condition on fluid flow and heat transfer in microchannels could not be neglected.

Effects of Viscosity-Variation and Viscous Dissipation in Microchannels of the MTPV Systems

2013 ◽  
Vol 437 ◽  
pp. 110-113
Author(s):  
Ge Ping Wu ◽  
Ping Lu ◽  
Jun Wang
Keyword(s):  
Heat Transfer ◽  
Viscous Dissipation ◽  
Variable Viscosity ◽  
Governing Equations ◽  
Simple Method ◽  
Flow And Heat Transfer ◽  
Viscosity Variation ◽  
Microchannel Cooling ◽  
Cooling Passage ◽  
Volume Method

Heat transfer and fluid flow in the microchannel cooling passages of plane cell type MTPV systems are numerically investigated. The Finite Volume method is adopted for the governing equations discretization; The SIMPLE method is applied to deal with the linkage between pressure and velocities. Numerical results confirm that the effects of viscous dissipation and variable viscosity could not be neglected. Influence of viscosity-variation with temperature of water and viscous dissipation on the flow and heat transfer characteristics of the microchannel cooling passage was discussed. The computer simulations were validated by the analytical solution results.

Magnetohydrodynamics Flow and Heat Transfer Around a Solid Cylinder Wrapped With a Porous Ring

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Mohammad Sadegh Valipour ◽  
Saman Rashidi ◽  
Reza Masoodi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Critical Radius ◽  
Governing Equations ◽  
Heat Transfer Characteristics ◽  
Electrically Conductive ◽  
Flow And Heat Transfer ◽  
Volume Method ◽  
Physical Phenomena

The problem of the effect of an external magnetic field on fluid flow and heat transfer characteristics is relevant to several physical phenomena. In this paper, flow and heat transfer of an electrically-conductive fluid around a cylinder, wrapped with a porous ring and under the influence of a magnetic field, is studied numerically. The ranges of the Stuart (N), Reynolds (Re), and Darcy (Da) numbers are 0–7, 1–40, and 10−8–10−1, respectively. The Darcy–Brinkman–Forchheimer model was used for simulating flow in the porous layer. The governing equations provide a coupling between flow and magnetic fields. The governing equations, together with the relevant boundary conditions, are solved numerically using the finite-volume method (FVM). The effect of the Stuart, Reynolds, and Darcy numbers on the flow patterns and heat transfer rate are explored. Finally, two empirical equations for the average Nusselt number were suggested, in which the effect of a magnetic field and the Darcy numbers are taken into account. It was found that in the presence of a magnetic field, the drag coefficient and the critical radius of the insulation increases, while the wake length and Nusselt number decrease.

Effects of Inlet and Outlet Ports of Ventilated Square Cavity on Flow and Heat Transfer

2020 ◽  
Vol 26 ◽  
pp. 78-85
Author(s):  
Houssem Laidoudi ◽  
Mustapha Helmaoui ◽  
Belbachir Azeddine ◽  
Adel Ayad ◽  
Abedallah Ghenaim
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Average Nusselt Number ◽  
Governing Equations ◽  
Square Cavity ◽  
Outlet Port ◽  
Flow And Heat Transfer ◽  
The Mean ◽  
Drag And Lift ◽  
Volume Method

This paper deals with numerical simulations of forced convection from a pair of identical cylinders arranged in tandem manner inside a square cavity of single inlet and outlet ports. The gap distance between the cylinders is fixed with half of square length. The main purpose of this study is to see the effect of inlet and outlet port positions on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy have been solved using finite-volume method in laminar, steady and two dimensional directions. The work has been done in the range of these conditions: Re = 1 to 40, at fixed Pr = 7.01. Three positions of inlet and outlet port have been selected. The mean results of flow patterns and distribution temperature are illustrated under the contours of streamline and isotherm respectively. The drag and lift coefficients of each cylinder is computed and discussed. The average Nusselt number of both cylinders is also presented and discussed. It was found that the inlet and outlet ports have significant effects on heat transfer from the confined cylinders.

Computation of Turbulent Free Convection in Oblique Porous Enclosures Using a Macroscopic Two-Equation Model

2007 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Edimilson J. Braga
Keyword(s):  
Turbulence Model ◽  
Equation Model ◽  
Turbulent Natural Convection ◽  
Flow And Heat Transfer ◽  
Wide Range ◽  
Laminar And Turbulent Flow ◽  
Different Temperatures ◽  
Inclined Cavity ◽  
Volume Method ◽  
Range Of Values

This paper presents computations for turbulent natural convection within an inclined cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The inclined walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for a wide range of values of Rayleigh number and inclined angles. The turbulent model used is the macroscopic k-eps model with a wall function. In this work, the turbulence model is first switched off and the laminar branch of the solution is found. Subsequently, the turbulence model is included so that the solution merges to the laminar branch for a reducing Ram. This convergence of results as Ram decreases can be seen as an estimate of the well known laminarization phenomenon. Present solutions are compared with published results and the influence of the inclination angle on Racr is analyzed. For Ram greater than around 104, both laminar and turbulent flow solutions deviate, indicating that such critical value for Ram was reached.

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 Prediction of Combustor Heatshield Flow and Heat Transfer With Sub-Grid-Scale Modelling of Pedestals

2001 ◽  
Author(s):  
John K. Luff ◽  
James J. McGuirk
Keyword(s):  
Heat Transfer ◽  
Life Prediction ◽  
Conjugate Heat Transfer ◽  
Energy Equation ◽  
Flow And Heat Transfer ◽  
Extra Energy ◽  
Scale Modelling ◽  
Heat Transfer Calculation ◽  
Proper Account ◽  
Good Agreement

A goal for computational analysis of combustors is to produce a tool for life prediction. An important part of this will be the prediction of the temperature field in the combustor walls. The complex geometries of combustor components make this a formidable task. In this paper a 3D coupled numerical flow/conjugate heat transfer calculation procedure is presented for a combustor heatshield. Proper account must be taken of the blockage and heat transfer effects of pedestals. A scheme has been developed to account for these effects without resolving the pedestals in the computational grid. Extra sink terms are included in the momentum equations to account for pedestal pressure drop. An extra energy equation is solved to determine the local pedestal temperature and to account for heat transfer between pedestals and fluid. This treatment has been validated against empirical data for arrays of pedestals in ducts with good agreement for friction factor and Nusselt number. The methodology is then applied to a generic heatshield geometry to indicate that a viable computational route has been developed for combustor heatshield analysis.

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