ON HEAT TRANSFER BETWEEN A POROUS MATRIX AND A TRAVERSING FLUID

1990 ◽  
Author(s):  
Jean P. Du Plessis ◽  
Jacob H. Masliyah
Keyword(s):  
Heat Transfer ◽  
Porous Matrix

Free convection in a square porous cavity filled with a nanofluid using thermal non equilibrium and Buongiorno models

2016 ◽  
Vol 26 (3/4) ◽  
pp. 671-693 ◽  
Author(s):  
Ioan Pop ◽  
Mohammad Ghalambaz ◽  
Mikhail Sheremet
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Brownian Motion ◽  
Base Fluid ◽  
Average Nusselt Number ◽  
Solid Phase ◽  
Porous Matrix ◽  
Governing Equations ◽  
Content Type ◽  
Brownian Motion And Thermophoresis

Purpose – The purpose of this paper is to theoretically analysis the steady-state natural convection flow and heat transfer of nanofluids in a square enclosure filled with a porous medium saturated with a nanofluid considering local thermal non-equilibrium (LTNE) effects. Different local temperatures for the solid phase of the nanoparticles, the solid phase of porous matrix and the liquid phase of the base fluid are taken into account. Design/methodology/approach – The Buongiorno’s model, incorporating the Brownian motion and thermophoresis effects, is utilized to take into account the migration of nanoparticles. Using appropriate non-dimensional variables, the governing equations are transformed into the non-dimensional form, and the finite element method is utilized to solve the governing equations. Findings – The results show that the increase of buoyancy ratio parameter (Nr) decreases the magnitude of average Nusselt number. The increase of the nanoparticles-fluid interface heat transfer parameter (Nhp) increases the average Nusselt number for nanoparticles and decreases the average Nusselt number for the base fluid. The nanofluid and porous matrix with large values of modified thermal capacity ratios (γ p and γ s ) are of interest for heat transfer applications. Originality/value – The three phases of nanoparticles, base fluid and the porous matrix are in the LTNE. The effect of mass transfer of nanoparticles due to the Brownian motion and thermophoresis effects are also taken into account.

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.

Mixed Convection in a Horizontal Porous Duct With a Sudden Expansion and Local Heating From Below

1999 ◽  
Vol 121 (3) ◽  
pp. 653-661 ◽  
Author(s):  
Y. Yokoyama ◽  
F. A. Kulacki ◽  
R. L. Mahajan
Keyword(s):  
Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Local Heating ◽  
Lower Surface ◽  
Porous Matrix ◽  
Sudden Expansion ◽  
Nusselt Numbers ◽  
Matrix Heat ◽  
Heating From Below

Results are reported for an experimental and numerical study of forced and mixed convective heat transfer in a liquid-saturated horizontal porous duct. The cross section of the duct has a sudden expansion with a heated region on the lower surface downstream and adjacent to the expansion. Within the framework of Darcy’s formulation, the calculated and measured Nusselt numbers for 0.1 < Pe < 100 and 50 < Ra < 500 are in excellent agreement. Further, the calculated Nusselt numbers are very close to those for the bottom-heated flat duct. This finding has important implications for convective heat and mass transfer in geophysical systems and porous matrix heat exchangers. The calculations were also carried out for glass bead-packed beds saturated with water using non-Darcy’s formula. The streamlines in the forced convection indicate that, even with non-Darcy effects included, recirculation is not observed downstream of an expansion and the heat transfer rate is decreased but only marginally.

scholarly journals The NANOFLUID FLOW BETWEEN PARALLEL PLATES AND HEAT TRANSFER IN PRESENCE OF CHEMICAL REACTION AND POROUS MATRIX

2020 ◽  
Vol 50 (4) ◽  
pp. 283-289
Author(s):  
S. Jena ◽  
S. R. Mishra ◽  
P.K. Pattnaik ◽  
Ram Prakash Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Chemical Reaction ◽  
Numerical Solutions ◽  
Porous Matrix ◽  
Parallel Plates ◽  
Nanofluid Flow ◽  
Similarity Transformations ◽  
Fourth Order Method ◽  
Source Sink

This paper deals with nanofluid flow between parallel plates and heat transfer through porous media with heat source /sink. The governing equations are transformed into self-similar ordinary differential equations by adopting similarity transformations and then the converted equations are solved numerically by Runge-Kutta fourth order method. Special emphasis has been given to the parameters of physical interest which include Prandtl number, magnetic parameter, porous matrix, chemical reaction parameter and heat source parameter. The results obtained for velocity, temperature and concentration are shown in graphs. The comparison of the special case of this present results with the existing numerical solutions in the literature shows excellent agreement.

Modeling of Thermomagnetic Phenomena in Active Magnetocaloric Regenerators

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Paulo V. Trevizoli ◽  
Jader R. Barbosa ◽  
Armando Tura ◽  
Daniel Arnold ◽  
Andrew Rowe
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Experimental Data ◽  
Solid Phase ◽  
Entropy Change ◽  
Porous Matrix ◽  
Cooling Capacity ◽  
Heat Transfer Fluid ◽  
Fluid Displacement ◽  
Matrix Heat Exchanger

The active magnetic regenerator (AMR) consists of a porous matrix heat exchanger whose solid phase is a magnetocaloric material (solid refrigerant) that undergoes a reversible magnetic entropy change when subjected to a changing magnetic field. The cooling capacity of the cycle is proportional to the mass of solid refrigerant, operating frequency, volumetric displacement of the heat transfer fluid and regenerator effectiveness. AMRs can be modeled via a porous media approach and a model has been developed in this work to simulate the time-dependent fluid flow and heat transfer processes in the regenerator matrix. Gadolinium (Gd) is usually adopted as a reference material for magnetic cooling at near room temperature and its magnetic temperature change and physical properties were accounted for through a combination of experimental data and the Weiss-Debye-Sommerfeld (WDS) theory. In this paper, the interaction of the applied magnetic field waveform with the heat transfer fluid displacement profile and the influence of demagnetizing effects on the AMR performance are investigated numerically. The numerical model is evaluated against experimental data for a regenerator containing spherical Gd particles.

A Numerical Investigation of Premixed Combustion Within Porous Inert Media

1993 ◽  
Vol 115 (3) ◽  
pp. 744-750 ◽  
Author(s):  
P.-F. Hsu ◽  
J. R. Howell ◽  
R. D. Matthews
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Numerical Investigation ◽  
Convective Heat ◽  
Unit Length ◽  
Flame Temperature ◽  
Porous Matrix ◽  
Premixed Combustion ◽  
Detailed Chemical Kinetics ◽  
Porous Inert Media

A numerical investigation of premixed combustion within a highly porous inert medium is reported. Specifically, results of a numerical model using detailed chemical kinetics and energy exchange between the flowing gas and the porous solid are presented. The current formulation differs from prior models of this type of combustion in that multistep kinetics is used and a better description of the thermophysical properties of the solid is applied in the present model. It was found that the preheating effect increases strongly with increasing convective heat transfer and with increasing effective thermal conductivity of the solid. The convective heat transfer is expected to increase with increasing number of cells per unit length of porous matrix but the absorption coefficient decreases with increasing cell size and decreasing cell density. Numerical simulations using baseline properties indicate that the lean limit can be extended to an equivalence ratio of about 0.36 for a methane–air flame and that the peak flame temperature is generally higher than the adiabatic flame temperature. The latter effect is predicted to be more pronounced at lower equivalence ratios.

Nusselt Number and Temperature Distribution in an Horizontal Cavity Containing a Layer of Porous Material at the Bottom

2003 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Viviani T. Magro
Keyword(s):  
Heat Transfer ◽  
Porous Material ◽  
Numerical Solutions ◽  
Control Volume ◽  
Simple Algorithm ◽  
Flow Region ◽  
Porous Matrix ◽  
Layered Porous Media ◽  
Energy Equations ◽  
Volume Method

Horizontally-layered porous media in enclosures represents an important configuration with many technological applications in mechanical and aerospace engineering. This work presents numerical solutions for flow and heat transfer in square cavities partially obstructed with porous material. The microscopic flow and energy equations are integrated in a representative elementary volume in order to obtain a set of equations valid in both the clear flow region and in the porous matrix. A unique set of equations is discretized with the control volume method and solved with SIMPLE algorithm. Heat transfer enhancement across the porous cavity is calculated as the permeability or the porosity of the porous substrate increase.

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