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Partager le résultat de cette recherche Interroger des sources externesContribution à l’étude théorique des transferts thermiques convectifs dans un nanofluide / Asma Lamri Zeggar
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) الحمل القسري الحمل المختلط الإنسياب الرقائقي أسطوانتين متمركزتين نانوفلويد)ماء/ 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) الحمل القسري الحمل المختلط الإنسياب الرقائقي أسطوانتين متمركزتين نانوفلويد)ماء/ 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 : Convection forcée et mixte dans un espace annulaire elliptique horizontal et incliné rempli par une mousse métallique Type de document : texte imprimé Auteurs : Meriem Benmerkhi, Auteur ; M. Afrid, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2016 Importance : 196 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : Convection forcée convection mixte mousse métallique espace annulaire section elliptique horizontal incliné propriétés variables modèle analytique étude numérique transfert thermique حمل قسري حمل مختلط رغوة معدنية خصائص متغيرة تجويف حلقي بيضاوي المقطع أفقي مائل نموذج تحليلي دراسة عددية نقل الحرارة Index. décimale : 530 Physique Résumé : The three-dimensional laminar convection of water in aluminum metal foam annulus between two confocal elliptic cylinders is presented. The 20 PPI aluminum foam is considered a homogeneous and isotropic porous medium. The flow field is considered axial,uniform and isothermal at the annulus entrance. The inner cylinder is uniformly heated and the outer cylinder is adiabatic. In this study, we present two parts: the first one is an analytic and a numerical solution of the thermally developing forced convection flow, with constant physical properties; the results will be compared with those of the empty annulus to assess the thermal performance of the used aluminum foam. The detailed mathematical and physical aspects of the convection are presented and discussed. The heat transfer enhancement by the use of the metal foam is demonstrated. For the considered controlling parameters of the problem, it is found that the numerical thermal field reproduces the analytic one. This reproduction is a validation of the numerical result and a demonstration of the adequacy of the spatial resolution of the used numerical grid. The validation of the numerical results of the considered forced convection is a prelude to the numerical simulation of the mixed convection in an inclined annulus with fluid variable physical properties that is presented in the second Part of this work. The results of the forced convection are considered a reference state for those of the mixed convection. In the second part of this work, the slow flow and the heat transfer through the porous annulus are modeled by the continuity equation, the Darcy-Forchheimer-Brinkman flow model, accounting for the important buoyancy, and the energy equation. In the temperature variation domain of this study, the thermophysical properties of the water are functions of temperature while those of the aluminum are constants. The model equations are numerically solved by a finite volume numerical method with a second order accurate spatiotemporal discretization. From the results obtained with the considered geometric, dynamic and thermal parameters, a small negative annulus inclination is recommended to obtain an enhanced heat transfer close to that of the horizontal annulus mounting while overcoming the total pressure drop. The qualitative aspects of the results of this study are not limited to the specific used system; they apply to any strong mixed convection system (with fluid variable physical properties), in along enough and inclined conduit, filled with any porous medium that has an effective thermal conductivity higher than that of the used liquid. Diplôme : Doctorat en sciences En ligne : ../theses/physique/BEN6902.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10233 Convection forcée et mixte dans un espace annulaire elliptique horizontal et incliné rempli par une mousse métallique [texte imprimé] / Meriem Benmerkhi, Auteur ; M. Afrid, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2016 . - 196 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : Convection forcée convection mixte mousse métallique espace annulaire section elliptique horizontal incliné propriétés variables modèle analytique étude numérique transfert thermique حمل قسري حمل مختلط رغوة معدنية خصائص متغيرة تجويف حلقي بيضاوي المقطع أفقي مائل نموذج تحليلي دراسة عددية نقل الحرارة Index. décimale : 530 Physique Résumé : The three-dimensional laminar convection of water in aluminum metal foam annulus between two confocal elliptic cylinders is presented. The 20 PPI aluminum foam is considered a homogeneous and isotropic porous medium. The flow field is considered axial,uniform and isothermal at the annulus entrance. The inner cylinder is uniformly heated and the outer cylinder is adiabatic. In this study, we present two parts: the first one is an analytic and a numerical solution of the thermally developing forced convection flow, with constant physical properties; the results will be compared with those of the empty annulus to assess the thermal performance of the used aluminum foam. The detailed mathematical and physical aspects of the convection are presented and discussed. The heat transfer enhancement by the use of the metal foam is demonstrated. For the considered controlling parameters of the problem, it is found that the numerical thermal field reproduces the analytic one. This reproduction is a validation of the numerical result and a demonstration of the adequacy of the spatial resolution of the used numerical grid. The validation of the numerical results of the considered forced convection is a prelude to the numerical simulation of the mixed convection in an inclined annulus with fluid variable physical properties that is presented in the second Part of this work. The results of the forced convection are considered a reference state for those of the mixed convection. In the second part of this work, the slow flow and the heat transfer through the porous annulus are modeled by the continuity equation, the Darcy-Forchheimer-Brinkman flow model, accounting for the important buoyancy, and the energy equation. In the temperature variation domain of this study, the thermophysical properties of the water are functions of temperature while those of the aluminum are constants. The model equations are numerically solved by a finite volume numerical method with a second order accurate spatiotemporal discretization. From the results obtained with the considered geometric, dynamic and thermal parameters, a small negative annulus inclination is recommended to obtain an enhanced heat transfer close to that of the horizontal annulus mounting while overcoming the total pressure drop. The qualitative aspects of the results of this study are not limited to the specific used system; they apply to any strong mixed convection system (with fluid variable physical properties), in along enough and inclined conduit, filled with any porous medium that has an effective thermal conductivity higher than that of the used liquid. Diplôme : Doctorat en sciences En ligne : ../theses/physique/BEN6902.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10233 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BEN/6902 BEN/6902 Thèse Bibliothèque principale Thèses Disponible
Titre : Étude de l’amplification de l’instabilité hydrodynamique et de la résonance thermique lors du refroidissement des blocs chauffés Type de document : texte imprimé Auteurs : Abdelouahab Bouttout, Auteur ; Smail Benissaad, Directeur de thèse Editeur : Constantine : Université Mentouri Constantine Année de publication : 2015 Importance : 137 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : convection forcée résonance thermique composants électronique forced convection thermal resonance electronic components حمل قوي تناغم حراري عناصر الكترونية Index. décimale : 620 Génie Mécanique Résumé : This thesis presents a numerical simulation of the forced convection in a horizontal channel contained identical heated blocks with uniform and pulsation flow in the entrance of the channel. We examined two applications: horizontal channel contains heated blocks with and without deflectors. Theses configurations simulate the cooling applications of the electronic components generating heat by the Joule effect during the electrical current flow.
The principal objective of the thesis is the amplification of instabilities to produce the thermal resonance phenomenon in order to improve the convective heat transfer of the heated blocks mounted in the package and printed circuit board. The flow field is governed by the Navier–Stokes equations in the fluid region, and the thermal field by the energy equation. The finite volume method and the SIMPLER algorithm have been used to solve these equations.
The first part of the thesis has been focused on the heat transfer in the channel contained nine identical heated blocks mounted on the bottom wall. The air pulsation is introduced in the channel inlet. The natural frequencies of the flow are obtained for various Reynolds numbers. The bands of thermal resonance which ensure a better heat transfer of the heated blocks are obtained. The analysis of the flow with pulsation and its effect on the heat transfer gain of each block are discussed in detail. The results show that the enhanced heat transfer coefficient achieve 25 to 55% compared with uniform flow without pulsation. Good agreement between numerical simulations and experimental results available from the literature is obtained.
The second part of this thesis is focused to study the effect of the air pulsation in the entrance of the channel contains heated blocks with various kinds of deflectors (rectangular and triangular shapes).The results show that the integration of the deflectors improves the heat transfer of the heated blocks significantly, up to 34% in the uniform flow case. The exploiting natural instabilities require: the creation of the system with flow separation through the deflectors and the tandem blocks, the determination of the resonance frequency and then the excitation with appropriate modulation. This part showed that the combination of the passive and active techniques of the cooling ensures an enhancement of heat transfer of the electronic components in the channel.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6738.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9885 Étude de l’amplification de l’instabilité hydrodynamique et de la résonance thermique lors du refroidissement des blocs chauffés [texte imprimé] / Abdelouahab Bouttout, Auteur ; Smail Benissaad, Directeur de thèse . - Constantine : Université Mentouri Constantine, 2015 . - 137 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : convection forcée résonance thermique composants électronique forced convection thermal resonance electronic components حمل قوي تناغم حراري عناصر الكترونية Index. décimale : 620 Génie Mécanique Résumé : This thesis presents a numerical simulation of the forced convection in a horizontal channel contained identical heated blocks with uniform and pulsation flow in the entrance of the channel. We examined two applications: horizontal channel contains heated blocks with and without deflectors. Theses configurations simulate the cooling applications of the electronic components generating heat by the Joule effect during the electrical current flow.
The principal objective of the thesis is the amplification of instabilities to produce the thermal resonance phenomenon in order to improve the convective heat transfer of the heated blocks mounted in the package and printed circuit board. The flow field is governed by the Navier–Stokes equations in the fluid region, and the thermal field by the energy equation. The finite volume method and the SIMPLER algorithm have been used to solve these equations.
The first part of the thesis has been focused on the heat transfer in the channel contained nine identical heated blocks mounted on the bottom wall. The air pulsation is introduced in the channel inlet. The natural frequencies of the flow are obtained for various Reynolds numbers. The bands of thermal resonance which ensure a better heat transfer of the heated blocks are obtained. The analysis of the flow with pulsation and its effect on the heat transfer gain of each block are discussed in detail. The results show that the enhanced heat transfer coefficient achieve 25 to 55% compared with uniform flow without pulsation. Good agreement between numerical simulations and experimental results available from the literature is obtained.
The second part of this thesis is focused to study the effect of the air pulsation in the entrance of the channel contains heated blocks with various kinds of deflectors (rectangular and triangular shapes).The results show that the integration of the deflectors improves the heat transfer of the heated blocks significantly, up to 34% in the uniform flow case. The exploiting natural instabilities require: the creation of the system with flow separation through the deflectors and the tandem blocks, the determination of the resonance frequency and then the excitation with appropriate modulation. This part showed that the combination of the passive and active techniques of the cooling ensures an enhancement of heat transfer of the electronic components in the channel.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6738.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9885 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BOU/6738 BOU/6738 Thèse Bibliothèque principale Thèses Disponible
Titre : La Convection mixte dans un éspace annulaire entre deux cylindres cocentriques Type de document : texte imprimé Auteurs : Abdelkader Khaled Hariz ; Univ. de Constantine, Éditeur scientifique ; T. Boufendi, Directeur de thèse Année de publication : 2008 Importance : 128 f. Note générale : 01 Disponible à la salle de recherche 02 Disponibles au magazin de la B.U.C. 01 CD Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : Ecoulement laminaire Convection mixte Convection forcée Espace annulaire Cylindres cocentriques Ailettes Simulation numérique 3D Index. décimale : 530 Physique En ligne : ../theses/physique/HAR5058.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=3463 La Convection mixte dans un éspace annulaire entre deux cylindres cocentriques [texte imprimé] / Abdelkader Khaled Hariz ; Univ. de Constantine, Éditeur scientifique ; T. Boufendi, Directeur de thèse . - 2008 . - 128 f.
01 Disponible à la salle de recherche 02 Disponibles au magazin de la B.U.C. 01 CD
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : Ecoulement laminaire Convection mixte Convection forcée Espace annulaire Cylindres cocentriques Ailettes Simulation numérique 3D Index. décimale : 530 Physique En ligne : ../theses/physique/HAR5058.pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=3463 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité HAR/5058 HAR/5058 Thèse Bibliothèque principale Thèses Disponible
Titre : Etude hydrodynamique et thermique d’un écoulement en régime laminaire dans une conduite remplie par un milieu poreux. Type de document : texte imprimé Auteurs : Abdelkrim Bouaffane, Auteur ; Kamel Talbi, Directeur de thèse Mention d'édition : 21/12/2020 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2020 Importance : 108 f. Format : 30 cm. Note générale : 1 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : milieu poreux convection forcée déséquilibre thermique local performance thermique modèle de Darcy- Brinkman- Forchheimer Porous medium forced convection local thermal non-equilibrium Thermal performance Darcy- Brinkman- Forchheimer model الحمل الحراري القسري المادة المسامية الأداء الحراري دارسي برينكمان فورشايمر Index. décimale : 620 Génie Mécanique Résumé :
The present work involves the thermal numerical simulation of laminar forced convection inside an annular pipe completely filled porous material. The DarcyBrinkman-Forcheimer- model is considered to describe the fluid transport in the porous media. The energy transport is simulated using the LTNE model: Local Thermal Non-Equilibrium between the fluid and the solid phases. The final form of the governing equations with their boundary conditions are transformed in dimensionless form and discretized by the finite volume method. SIMPLE algorithm was adopted to solve the set of algebraic discretized coupled equations. This work is divided in two parts: In the first part, the effect of the pertinent dimensionless parameters which govern the study such as Biot number (Bi), Reynolds number (Re), solid-fluid thermal conductivity ratio (Rc) and porosity ( ) on the LTNE intensity are analyzed by calculating the local difference of temperature (LDT) and the average difference of temperature DMT. The results show that the increase of Biot number and the solid-fluid thermal conductivity ratio, porosity and the decrease of Re reduces the LTNE intensity. The intensity of the LDT in the developing region is greater than that of the fully developed region. It is difficult to achieve a thermal equilibrium between the solid and fluid phases except in the case of high values of the Bio number. Therefore, the use of the thermal equilibrium model is not suitable in most cases. In the second part, the thermal performance is studied, the results illustrate that the increase of Bi, and Rc, and the decrease of porosity, Rr and Re represent good factors to improve the thermal performance.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU7703.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11537 Etude hydrodynamique et thermique d’un écoulement en régime laminaire dans une conduite remplie par un milieu poreux. [texte imprimé] / Abdelkrim Bouaffane, Auteur ; Kamel Talbi, Directeur de thèse . - 21/12/2020 . - جامعة الإخوة منتوري قسنطينة, 2020 . - 108 f. ; 30 cm.
1 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : milieu poreux convection forcée déséquilibre thermique local performance thermique modèle de Darcy- Brinkman- Forchheimer Porous medium forced convection local thermal non-equilibrium Thermal performance Darcy- Brinkman- Forchheimer model الحمل الحراري القسري المادة المسامية الأداء الحراري دارسي برينكمان فورشايمر Index. décimale : 620 Génie Mécanique Résumé :
The present work involves the thermal numerical simulation of laminar forced convection inside an annular pipe completely filled porous material. The DarcyBrinkman-Forcheimer- model is considered to describe the fluid transport in the porous media. The energy transport is simulated using the LTNE model: Local Thermal Non-Equilibrium between the fluid and the solid phases. The final form of the governing equations with their boundary conditions are transformed in dimensionless form and discretized by the finite volume method. SIMPLE algorithm was adopted to solve the set of algebraic discretized coupled equations. This work is divided in two parts: In the first part, the effect of the pertinent dimensionless parameters which govern the study such as Biot number (Bi), Reynolds number (Re), solid-fluid thermal conductivity ratio (Rc) and porosity ( ) on the LTNE intensity are analyzed by calculating the local difference of temperature (LDT) and the average difference of temperature DMT. The results show that the increase of Biot number and the solid-fluid thermal conductivity ratio, porosity and the decrease of Re reduces the LTNE intensity. The intensity of the LDT in the developing region is greater than that of the fully developed region. It is difficult to achieve a thermal equilibrium between the solid and fluid phases except in the case of high values of the Bio number. Therefore, the use of the thermal equilibrium model is not suitable in most cases. In the second part, the thermal performance is studied, the results illustrate that the increase of Bi, and Rc, and the decrease of porosity, Rr and Re represent good factors to improve the thermal performance.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU7703.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11537 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BOU/7703 BOU/7703 Thèse Bibliothèque principale Thèses Disponible
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