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Partager le résultat de cette recherche Interroger des sources externesÉtude du comportement dynamique Du transfert de chaleur et de masse d'un réacteur de métal-hydrogène fermé / Ali Boukhari
Titre : Étude du comportement dynamique Du transfert de chaleur et de masse d'un réacteur de métal-hydrogène fermé Type de document : texte imprimé Auteurs : Ali Boukhari, Auteur ; Rachid Bessaih, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 115 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : Stockage d’hydrogène Réacteur à lit absorbant Hydrure de métal Simulation
numérique Transferts de chaleur et de masse couplés Hydrogen storage Packed bed reactor Metal hydride Numerical simulation Coupled
heat and mass transfer ????? ?????????? ????? ???? ??????-??????? ???????? ??????? ?????? ??????? ???????Index. décimale : 620 Génie Mécanique Résumé : The purpose of this work is to numerically study the dynamic behavior of heat and mass
transfer in an annulus-disc metal hydride reactor used for hydrogen solid storage. A twodimensional mathematical model of a simple geometry consisting of the equations governing the phenomenon of hydrogen storage has been proposed, in which the Navier-Stokes equations were used in addition of the source term with the Forchheimer’s modification, to adequately describe fluid flow in the packed bed considered as porous medium. The equations of continuity, momentum and energy were solved using the finite volume method; by accommodating the commercial code ANSYS FLUENT through user-defined functions (UDF), to numerically solve the equations governing the sorption processes studied.
The numerical model results were compared to experimental results reported in the literature for the case of a simple regular geometry. A good agreement was found between present calculations results and experimental data.
Numerical simulations have shown that the pressure drop in the metal hydride packed bed
caused by the fluid inertia can be considerable in this flow type. Moreover, the hydrogen sorption time depends on the configuration and geometrical dimensions of the heat exchange device. Thus, the minimization of absorption or desorption time is reduced to the reliability of the heat exchange process in the packed bed reactor. In addition, the conductivity is a key factor in the efficient design of the metal hydride reactors.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6817.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10086 Étude du comportement dynamique Du transfert de chaleur et de masse d'un réacteur de métal-hydrogène fermé [texte imprimé] / Ali Boukhari, Auteur ; Rachid Bessaih, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2015 . - 115 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : Stockage d’hydrogène Réacteur à lit absorbant Hydrure de métal Simulation
numérique Transferts de chaleur et de masse couplés Hydrogen storage Packed bed reactor Metal hydride Numerical simulation Coupled
heat and mass transfer ????? ?????????? ????? ???? ??????-??????? ???????? ??????? ?????? ??????? ???????Index. décimale : 620 Génie Mécanique Résumé : The purpose of this work is to numerically study the dynamic behavior of heat and mass
transfer in an annulus-disc metal hydride reactor used for hydrogen solid storage. A twodimensional mathematical model of a simple geometry consisting of the equations governing the phenomenon of hydrogen storage has been proposed, in which the Navier-Stokes equations were used in addition of the source term with the Forchheimer’s modification, to adequately describe fluid flow in the packed bed considered as porous medium. The equations of continuity, momentum and energy were solved using the finite volume method; by accommodating the commercial code ANSYS FLUENT through user-defined functions (UDF), to numerically solve the equations governing the sorption processes studied.
The numerical model results were compared to experimental results reported in the literature for the case of a simple regular geometry. A good agreement was found between present calculations results and experimental data.
Numerical simulations have shown that the pressure drop in the metal hydride packed bed
caused by the fluid inertia can be considerable in this flow type. Moreover, the hydrogen sorption time depends on the configuration and geometrical dimensions of the heat exchange device. Thus, the minimization of absorption or desorption time is reduced to the reliability of the heat exchange process in the packed bed reactor. In addition, the conductivity is a key factor in the efficient design of the metal hydride reactors.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6817.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10086 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BOU/6817 BOU/6817 Thèse Bibliothèque principale Thèses Disponible
Titre : Modélisation thermique du stockage d'hydrogéne par absorption dans un réservoir d'hydrures Type de document : texte imprimé Auteurs : Karim Lahmer, Auteur ; Rachid Bessaih, Auteur Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 120 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : " Stockage de l’Hydrogène réservoir à hydrures de Magnésium simulation
numérique FLUENT - ANSYS 13.0 modélisation thermique mécanismes de réaction "Hydrogen storage Magnesium hydride tank Numerical simulation Thermal modeling Reaction mechanisms ????? ?????????? ???? ?????? ?????????? ???????? ??????? ??????? ???????? ????? ???????Index. décimale : 620 Génie Mécanique Résumé : Magnesium hydride is the best candidate for the reversible hydrogen storage in atomic form. Indeed, thanks to its high specific storage capacity, abundance and lower prices compared with other metal hydrides, it will be used on a large scale at near future to allow a quick development of fuel cells. The laws that govern the chemical and thermal phenomena of the hydrogen storage have been determined experimentally.
Numerical simulation, allows predicting and understanding the spatial and temporal
evolution of the hydrogen storage reaction. In addition, the computational tool saves important time for the design and the optimization of hydrogen tanks. In this work, we describe a developed model of charging / discharging a specific magnesium hydride tank for better control of the phenomenon. Also, we particularly interested about the thermal description of the reactions generated by the process of hydrogen absorption and desorption.
FLUENT software of ANSYS 13.0 was used to realize numerical simulations. One of its specific advantages consists of the important part that it attaches to the modeling of thermodynamics and kinetics of reactions between a gas and a porous medium (Metal Hydride). A subroutine written in C, called UDF for (User Defined Function) was developed by us and included in FLUENT. The results were validated by those available in the literature and have been the subject of many publications and international meetings. These results are the fruits of simulations on 2D and 3D geometries tanks initially heated to 300°C and at a
storage pressure of 1 MPa.
The equations that govern hydriding reaction are solved with a numerical scheme for fully implicit finite volume. The effect of different kinetic equations of absorption reaction was examined in order to determine which one would produce similar results compared to experimental ones. The profiles of temperature and concentration with space and time values
were plotted. Finally, the contours describing the gradients of temperature depending time were performed with the CFD-POST software.
The results show that the mechanism of reaction, based on the method of bidimensional volume contraction with a constant velocity interface provides the best results in the minimum of calculation time and becomes more appropriate for the 2D simulations.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/LAH6815.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10084 Modélisation thermique du stockage d'hydrogéne par absorption dans un réservoir d'hydrures [texte imprimé] / Karim Lahmer, Auteur ; Rachid Bessaih, Auteur . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2015 . - 120 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : " Stockage de l’Hydrogène réservoir à hydrures de Magnésium simulation
numérique FLUENT - ANSYS 13.0 modélisation thermique mécanismes de réaction "Hydrogen storage Magnesium hydride tank Numerical simulation Thermal modeling Reaction mechanisms ????? ?????????? ???? ?????? ?????????? ???????? ??????? ??????? ???????? ????? ???????Index. décimale : 620 Génie Mécanique Résumé : Magnesium hydride is the best candidate for the reversible hydrogen storage in atomic form. Indeed, thanks to its high specific storage capacity, abundance and lower prices compared with other metal hydrides, it will be used on a large scale at near future to allow a quick development of fuel cells. The laws that govern the chemical and thermal phenomena of the hydrogen storage have been determined experimentally.
Numerical simulation, allows predicting and understanding the spatial and temporal
evolution of the hydrogen storage reaction. In addition, the computational tool saves important time for the design and the optimization of hydrogen tanks. In this work, we describe a developed model of charging / discharging a specific magnesium hydride tank for better control of the phenomenon. Also, we particularly interested about the thermal description of the reactions generated by the process of hydrogen absorption and desorption.
FLUENT software of ANSYS 13.0 was used to realize numerical simulations. One of its specific advantages consists of the important part that it attaches to the modeling of thermodynamics and kinetics of reactions between a gas and a porous medium (Metal Hydride). A subroutine written in C, called UDF for (User Defined Function) was developed by us and included in FLUENT. The results were validated by those available in the literature and have been the subject of many publications and international meetings. These results are the fruits of simulations on 2D and 3D geometries tanks initially heated to 300°C and at a
storage pressure of 1 MPa.
The equations that govern hydriding reaction are solved with a numerical scheme for fully implicit finite volume. The effect of different kinetic equations of absorption reaction was examined in order to determine which one would produce similar results compared to experimental ones. The profiles of temperature and concentration with space and time values
were plotted. Finally, the contours describing the gradients of temperature depending time were performed with the CFD-POST software.
The results show that the mechanism of reaction, based on the method of bidimensional volume contraction with a constant velocity interface provides the best results in the minimum of calculation time and becomes more appropriate for the 2D simulations.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/LAH6815.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10084 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité LAH/6815 LAH/6815 Thèse Bibliothèque principale Thèses Disponible 
Titre : Contribution a l’etude des profils de tuyeres en ecoulements supersoniques visqueux par la methode des volumes finis Type de document : texte imprimé Auteurs : El-Ahcene Mahfoudi, Auteur ; Abderrahmane Gahmousse, Directeur de thèse ; Kamel Talbi, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 133 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : Tuyères convergentes-divergentes Jet supersonique Ondes de choc Décollement
de la couche limite Turbulence Simulation numérique Méthode des volumes finis Schémas de capture des ondes de choc Overexpanded nozzles Supersonic jet Shock waves Boundary layer separation Numerical simulation Finite volumes method Shock capturing schemes ??????? ?????????-????????? ??????? ????? ???? ??????? ?????????? ?????? ?????? ?????? ??????? ??????? ???????? ??????? ????? ?????? ????????? ?????? ?????? ?????? ??????????Index. décimale : 620 Génie Mécanique Résumé : Experimental studies of supersonic compressible flows in Overexpanded nozzles have
proved the existence and interaction of several physical phenomena: Supersonic jet, shock waves, boundary layer separation, reversed flow, viscous and turbulent mixing layer. These complex phenomena can significantly affect the performance and reliability of propulsive nozzles. This work focuses on the physical analysis and numerical simulation of turbulent separated flow in supersonic nozzles, operating in under-overexpanded conditions. The turbulence is modelled using a statistical approach (URANS) on a generalized coordinates, using the two-equation model of transport (SST Menter). The system of equations governing the flow is solved using the finite volume method in structured grid. The time integration is performed by the fully implicit numerical scheme of predictor-corrector type of Mac-Cormack. While the convective flows are discretized with shock capturing schemes (Roe, Steger-Warming). Viscous terms are discretized with a second order centred scheme. The Obtained numerical results have detected the various phenomena observed experimentally.Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MAH6475.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9519 Contribution a l’etude des profils de tuyeres en ecoulements supersoniques visqueux par la methode des volumes finis [texte imprimé] / El-Ahcene Mahfoudi, Auteur ; Abderrahmane Gahmousse, Directeur de thèse ; Kamel Talbi, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 133 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : Tuyères convergentes-divergentes Jet supersonique Ondes de choc Décollement
de la couche limite Turbulence Simulation numérique Méthode des volumes finis Schémas de capture des ondes de choc Overexpanded nozzles Supersonic jet Shock waves Boundary layer separation Numerical simulation Finite volumes method Shock capturing schemes ??????? ?????????-????????? ??????? ????? ???? ??????? ?????????? ?????? ?????? ?????? ??????? ??????? ???????? ??????? ????? ?????? ????????? ?????? ?????? ?????? ??????????Index. décimale : 620 Génie Mécanique Résumé : Experimental studies of supersonic compressible flows in Overexpanded nozzles have
proved the existence and interaction of several physical phenomena: Supersonic jet, shock waves, boundary layer separation, reversed flow, viscous and turbulent mixing layer. These complex phenomena can significantly affect the performance and reliability of propulsive nozzles. This work focuses on the physical analysis and numerical simulation of turbulent separated flow in supersonic nozzles, operating in under-overexpanded conditions. The turbulence is modelled using a statistical approach (URANS) on a generalized coordinates, using the two-equation model of transport (SST Menter). The system of equations governing the flow is solved using the finite volume method in structured grid. The time integration is performed by the fully implicit numerical scheme of predictor-corrector type of Mac-Cormack. While the convective flows are discretized with shock capturing schemes (Roe, Steger-Warming). Viscous terms are discretized with a second order centred scheme. The Obtained numerical results have detected the various phenomena observed experimentally.Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MAH6475.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9519 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité MAH/6475 MAH/6475 Thèse Bibliothèque principale Thèses Disponible Documents numériques
texte intégraleAdobe Acrobat PDF
Titre : Contribution à l’étude théorique des transferts thermiques convectifs dans un nanofluide : Application aux modèles monophasique et diphasique Type de document : texte imprimé Auteurs : Asma Lamri Zeggar, Auteur ; T. Boufendi, Directeur de thèse Editeur : Constantine : Université Mentouri Constantine Année de publication : 2014 Importance : 137 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : Photothermique Simulation numérique Convection forcée Convection mixte Conduit annulaire nanofluide (eau / Al2O3) Numerical simulation forced convection Mixed Convection annulus duct nanofluid (water/Al2O3) ????? ?????? ????? ??????? ???????? ???????? ????????? ????????? ?????????)???/ Al2O3) Index. décimale : 530 Physique Résumé : This research is a 3D computer simulation of fluid flows, combined to heat transfer in a forced and mixed convection mode, for a permanent and steady laminar flow through an annular duct made up of two horizontal and concentric cylinders. While the inner cylinder is adiabatic, the outer cylinder is subjected to a constant parietal heating. The annulus duct is traversed by a nanofluid laminar flow composed of a fluid base (water) and nanoparticles of aluminum oxide Al2O3 with constant physical properties regarded as incompressible and
Newtonian. This physical problem is modeled by mass conservation equations, by movement and energy amounts in a cylindrical coordinate system accompanied by appropriate boundary conditions. Different approaches were developed, such as the monophasic and the biphasic approaches, to which belong the fluid volume models, the mixing model and the Eulerian model.
These equation systems were solved as to the single-phase model by means of the finite volume method with a second-order spatial and temporal precision and the SIMPLER algorithm for the sequential solution of equations. The dynamic and thermal fields are obtained for various Reynolds number values, ranging from 500 to 2000, reaching (1%, 4%,8%) for different concentrations of nanoparticles, and between (0, 104 and 105) for different numbers of Grashof. The results show that the nanofluid behavior, whether in a forced convection mode or in mixed convection mode are, from both a hydrodynamic and a thermal points of view, characteristics of a trend similar to the behavior of a conventional fluid. In a forced convection, dynamic and thermal fields reflect radial velocity and temperature
gradients, as well as a Nusselt number with asymptotic behavior at the output. In a mixed convection, the cell structure and the lamination temperatures through a straight section appear with an increasing number of Grashof, giving rise therefore to an increase in the Nusselt number, and thus to a better heat transfer.
Diplôme : Magistère En ligne : ../theses/physique/LAM6729.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9894 Contribution à l’étude théorique des transferts thermiques convectifs dans un nanofluide : Application aux modèles monophasique et diphasique [texte imprimé] / Asma Lamri Zeggar, Auteur ; T. Boufendi, Directeur de thèse . - Constantine : Université Mentouri Constantine, 2014 . - 137 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : Photothermique Simulation numérique Convection forcée Convection mixte Conduit annulaire nanofluide (eau / Al2O3) Numerical simulation forced convection Mixed Convection annulus duct nanofluid (water/Al2O3) ????? ?????? ????? ??????? ???????? ???????? ????????? ????????? ?????????)???/ Al2O3) Index. décimale : 530 Physique Résumé : This research is a 3D computer simulation of fluid flows, combined to heat transfer in a forced and mixed convection mode, for a permanent and steady laminar flow through an annular duct made up of two horizontal and concentric cylinders. While the inner cylinder is adiabatic, the outer cylinder is subjected to a constant parietal heating. The annulus duct is traversed by a nanofluid laminar flow composed of a fluid base (water) and nanoparticles of aluminum oxide Al2O3 with constant physical properties regarded as incompressible and
Newtonian. This physical problem is modeled by mass conservation equations, by movement and energy amounts in a cylindrical coordinate system accompanied by appropriate boundary conditions. Different approaches were developed, such as the monophasic and the biphasic approaches, to which belong the fluid volume models, the mixing model and the Eulerian model.
These equation systems were solved as to the single-phase model by means of the finite volume method with a second-order spatial and temporal precision and the SIMPLER algorithm for the sequential solution of equations. The dynamic and thermal fields are obtained for various Reynolds number values, ranging from 500 to 2000, reaching (1%, 4%,8%) for different concentrations of nanoparticles, and between (0, 104 and 105) for different numbers of Grashof. The results show that the nanofluid behavior, whether in a forced convection mode or in mixed convection mode are, from both a hydrodynamic and a thermal points of view, characteristics of a trend similar to the behavior of a conventional fluid. In a forced convection, dynamic and thermal fields reflect radial velocity and temperature
gradients, as well as a Nusselt number with asymptotic behavior at the output. In a mixed convection, the cell structure and the lamination temperatures through a straight section appear with an increasing number of Grashof, giving rise therefore to an increase in the Nusselt number, and thus to a better heat transfer.
Diplôme : Magistère En ligne : ../theses/physique/LAM6729.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9894 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité LAM/6729 LAM/6729 Thèse Bibliothèque principale Thèses Disponible
Titre : Etude paramétrique des échanges convectifs turbulents dans les configurations d’intérêt pratique Type de document : texte imprimé Auteurs : Ridha Mebrouk, Auteur ; Abderrahim Boudenne, Directeur de thèse ; Yassine Kabar, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 139 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : Convection turbulente Simulation numérique Nanofluide Enceinte chauffée par le bas,
Convection forcée Echanges turbulents Echangeur de chaleur Transfert thermique conjugué Turbulent convection Numerical simulation Nanofluid Enclosure heated from below Forced
convection Turbulent exchanges Heat exchanger Conjugate heat transfer ????? ???????? ???????? ???????? ????????? ??????? ????? ?? ??????? ????? ??????? ??????? ???????? ?????????
???????????? ??????? ?????????Index. décimale : 620 Génie Mécanique Résumé : This thesis presents the results of two studies: the first concerns natural turbulent convection in a
rectangular cavity heated from the bottom wall and filled with a nanofluid and the second relates to the
investigation of conjugate heat transfer in a fin-and-tube heat exchanger.
The cavity of the first study is tall and has a heat source embedded on its bottom wall, while its left, right
and top walls are maintained at a relatively low temperature. The working fluid is a water based nanofluid
having three nanoparticle types: alumina, copper and copper oxide. The influence of pertinent parameters
such as the Rayleigh number, the type of nanofluid and solid volume fraction of nanoparticles on the cooling
performance is studied. Steady forms of two dimensional Reynolds-Averaged-Navier-Stokes equations and
conservation equations of mass and energy, coupled with the Boussinesq approximation, are solved by the
control volume based discretisation method employing the SIMPLE algorithm for pressure-velocity
coupling. Turbulence is modeled using the standard k-ε model. The Rayleigh number, Ra, is varied from
2.49x1009 to 2.49x1011. The volume fractions of nanoparticles were varied in the interval 0≤φ≤ 6% . Stream
lines, isotherms, velocity profiles and Temperature profiles are presented for various combinations of Ra,
the type of nanofluid and solid volume fraction of nanoparticles. The results are reported in the form of
average Nusselt number on the heated wall. It is shown that for all values of Ra, the average heat transfer
rate from the heat source increases almost linearly and monotonically as the solid volume fraction increases.
Finally the average heat transfer rate takes on values that decrease according to the ordering Cu, CuO and
Al2O3.
In the second study we determined the heat transfer and friction characteristics of a realistic fin-andtube heat exchanger . The computations assume steady-state heat transfer and fluid flow. Nusselt number
and friction factor characteristics of the heat exchanger are presented for various values of Reynolds
numbers. The energy conservation and the heat conduction equations in 3 dimensions have been solved
in the fluid and the solid respectivelyalong with the mass and momentum conservation equations in order
to determine these characteristics. Both laminar and turbulent flow regimes are considered. The effect of
turbulence modeling was investigated using three different models (the one equation Spalart-Allmaras
turbulence model, the standard k-ε model and the RSM model). The computations allowed the
determination of the dynamic and thermal fields. Model validation was carried out by comparing the
calculated friction factor f and Colburn j-factor to experimental results found in the literature. The
plotted results showed a qualitatively good agreement between numerical results and experimental data. The
results obtained also showed that the simplest of the three turbulence models tested(i.e. SpalartAllmaras) gives the closest values to the experimental data
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MEB7154.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10428 Etude paramétrique des échanges convectifs turbulents dans les configurations d’intérêt pratique [texte imprimé] / Ridha Mebrouk, Auteur ; Abderrahim Boudenne, Directeur de thèse ; Yassine Kabar, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 139 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : Convection turbulente Simulation numérique Nanofluide Enceinte chauffée par le bas,
Convection forcée Echanges turbulents Echangeur de chaleur Transfert thermique conjugué Turbulent convection Numerical simulation Nanofluid Enclosure heated from below Forced
convection Turbulent exchanges Heat exchanger Conjugate heat transfer ????? ???????? ???????? ???????? ????????? ??????? ????? ?? ??????? ????? ??????? ??????? ???????? ?????????
???????????? ??????? ?????????Index. décimale : 620 Génie Mécanique Résumé : This thesis presents the results of two studies: the first concerns natural turbulent convection in a
rectangular cavity heated from the bottom wall and filled with a nanofluid and the second relates to the
investigation of conjugate heat transfer in a fin-and-tube heat exchanger.
The cavity of the first study is tall and has a heat source embedded on its bottom wall, while its left, right
and top walls are maintained at a relatively low temperature. The working fluid is a water based nanofluid
having three nanoparticle types: alumina, copper and copper oxide. The influence of pertinent parameters
such as the Rayleigh number, the type of nanofluid and solid volume fraction of nanoparticles on the cooling
performance is studied. Steady forms of two dimensional Reynolds-Averaged-Navier-Stokes equations and
conservation equations of mass and energy, coupled with the Boussinesq approximation, are solved by the
control volume based discretisation method employing the SIMPLE algorithm for pressure-velocity
coupling. Turbulence is modeled using the standard k-ε model. The Rayleigh number, Ra, is varied from
2.49x1009 to 2.49x1011. The volume fractions of nanoparticles were varied in the interval 0≤φ≤ 6% . Stream
lines, isotherms, velocity profiles and Temperature profiles are presented for various combinations of Ra,
the type of nanofluid and solid volume fraction of nanoparticles. The results are reported in the form of
average Nusselt number on the heated wall. It is shown that for all values of Ra, the average heat transfer
rate from the heat source increases almost linearly and monotonically as the solid volume fraction increases.
Finally the average heat transfer rate takes on values that decrease according to the ordering Cu, CuO and
Al2O3.
In the second study we determined the heat transfer and friction characteristics of a realistic fin-andtube heat exchanger . The computations assume steady-state heat transfer and fluid flow. Nusselt number
and friction factor characteristics of the heat exchanger are presented for various values of Reynolds
numbers. The energy conservation and the heat conduction equations in 3 dimensions have been solved
in the fluid and the solid respectivelyalong with the mass and momentum conservation equations in order
to determine these characteristics. Both laminar and turbulent flow regimes are considered. The effect of
turbulence modeling was investigated using three different models (the one equation Spalart-Allmaras
turbulence model, the standard k-ε model and the RSM model). The computations allowed the
determination of the dynamic and thermal fields. Model validation was carried out by comparing the
calculated friction factor f and Colburn j-factor to experimental results found in the literature. The
plotted results showed a qualitatively good agreement between numerical results and experimental data. The
results obtained also showed that the simplest of the three turbulence models tested(i.e. SpalartAllmaras) gives the closest values to the experimental data
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MEB7154.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10428 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité MEB/7154 MEB/7154 Thèse Bibliothèque principale Thèses Disponible PermalinkPermalink
