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Titre : Investigation des échanges convectifs dans diverses configurations Type de document : texte imprimé Auteurs : Issam Rezaiguia, Auteur ; Mahfoud Kadja, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 142 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : convection naturelle nanofluides cavité triangulaire angle d'inclinaison simulation numérique microcanaux chute de pression transfert thermique conjugué fraction solide comportement non-Newtonien natural convection nanofluids triangular cavity inclination angle numerical simulation microchannels pressure drop conjugate heat transfer solid fraction non-Newtonian behavior ????? ??????? ??????? ???? ????? ????? ????? ????? ????? ????? ?????? ??????? ????? ??????? ??? ??????? ??? ?????? ?????? ?????? ???? ??? ??????? Index. décimale : 620 Génie Mécanique Résumé : This thesis reports the results of two studies: the first one concerns natural convection in isosceles triangular cavities with a partially active base while the second one concerns heat transfer in microchannels.
The first study considers natural convection cooling of a heat source located on the bottom wall of an inclined isosceles triangular enclosure filled with a Cu water-nanofluid. The right and left walls of the enclosure are both maintained cold at constant equal temperatures, while the remaining parts of the bottom wall are insulated. The study has been carried out for a Rayleigh number in the range 104 ≤ Ra ≤ 106, for a heat source length in the range 0.2 ≤ ε ≤ 0.8, for a solid volume fraction in the range 0.0 ≤ � ≤ 06 and for an inclination angle in the range 00 ≤ δ ≤ 450. Results are presented in the form of streamline contours, isotherms, maximum temperature at the heat source surface and average Nusselt number. It is noticed that the addition of Cu nanoparticles enhances the heat transfer rate and therefore cooling effectiveness for all values of Rayleigh number, especially at low values of Ra. The effect of the inclination angle becomes more noticeable as one increases the value of Ra. For high Rayleigh numbers, a critical value for the inclination angle of δ = 150 is found for which the heat source maximum temperature is highest.
The second study investigates heat transfer in microchannels machined in heat dissipating sinks. The fluid used is a nanofluid whose properties are temperature dependent. The energy dissipation is evaluated for various solid fraction contents along with the cooling effectiveness of this modern type of heat exchangers. The shape of the channels is also investigated. The evaluation parameter used for thermal energy dissipation is the Nusselt number while that used for cooling effectiveness is the static pressure drop between the inlet and the outlet of the microchannel. Conjugate convection-conduction energy conservation equations have been solved along with mass and momentum conservation equations in order to determine these parameters.
The results obtained showed important heat transfer augmentation with solid fraction at the expense of an increased pressure drop, i.e high pumping cost (therefore low cooling effectiveness). The microchannel inlet section geometry was also found to contribute to the values of the Nusselt number and pressure drop. Among the tested geometries (elliptical, rectangular, trapezoidal) the rectangular section provided the best compromise between heat transfer augmentation and pumping cost. At the end of the study, a comparison was made between the results obtained by assuming Newtonian rheology and those obtained with non-Newtonian rheological behavior of the same nanofluid sample. It was found that the assumption of non-Newtonian rheological behavior of nanofluids gives higher Nusselt number values and much lower pressure drops.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/REZ6773.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9837 Investigation des échanges convectifs dans diverses configurations [texte imprimé] / Issam Rezaiguia, Auteur ; Mahfoud Kadja, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 142 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : convection naturelle nanofluides cavité triangulaire angle d'inclinaison simulation numérique microcanaux chute de pression transfert thermique conjugué fraction solide comportement non-Newtonien natural convection nanofluids triangular cavity inclination angle numerical simulation microchannels pressure drop conjugate heat transfer solid fraction non-Newtonian behavior ????? ??????? ??????? ???? ????? ????? ????? ????? ????? ????? ?????? ??????? ????? ??????? ??? ??????? ??? ?????? ?????? ?????? ???? ??? ??????? Index. décimale : 620 Génie Mécanique Résumé : This thesis reports the results of two studies: the first one concerns natural convection in isosceles triangular cavities with a partially active base while the second one concerns heat transfer in microchannels.
The first study considers natural convection cooling of a heat source located on the bottom wall of an inclined isosceles triangular enclosure filled with a Cu water-nanofluid. The right and left walls of the enclosure are both maintained cold at constant equal temperatures, while the remaining parts of the bottom wall are insulated. The study has been carried out for a Rayleigh number in the range 104 ≤ Ra ≤ 106, for a heat source length in the range 0.2 ≤ ε ≤ 0.8, for a solid volume fraction in the range 0.0 ≤ � ≤ 06 and for an inclination angle in the range 00 ≤ δ ≤ 450. Results are presented in the form of streamline contours, isotherms, maximum temperature at the heat source surface and average Nusselt number. It is noticed that the addition of Cu nanoparticles enhances the heat transfer rate and therefore cooling effectiveness for all values of Rayleigh number, especially at low values of Ra. The effect of the inclination angle becomes more noticeable as one increases the value of Ra. For high Rayleigh numbers, a critical value for the inclination angle of δ = 150 is found for which the heat source maximum temperature is highest.
The second study investigates heat transfer in microchannels machined in heat dissipating sinks. The fluid used is a nanofluid whose properties are temperature dependent. The energy dissipation is evaluated for various solid fraction contents along with the cooling effectiveness of this modern type of heat exchangers. The shape of the channels is also investigated. The evaluation parameter used for thermal energy dissipation is the Nusselt number while that used for cooling effectiveness is the static pressure drop between the inlet and the outlet of the microchannel. Conjugate convection-conduction energy conservation equations have been solved along with mass and momentum conservation equations in order to determine these parameters.
The results obtained showed important heat transfer augmentation with solid fraction at the expense of an increased pressure drop, i.e high pumping cost (therefore low cooling effectiveness). The microchannel inlet section geometry was also found to contribute to the values of the Nusselt number and pressure drop. Among the tested geometries (elliptical, rectangular, trapezoidal) the rectangular section provided the best compromise between heat transfer augmentation and pumping cost. At the end of the study, a comparison was made between the results obtained by assuming Newtonian rheology and those obtained with non-Newtonian rheological behavior of the same nanofluid sample. It was found that the assumption of non-Newtonian rheological behavior of nanofluids gives higher Nusselt number values and much lower pressure drops.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/REZ6773.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9837 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité REZ/6773 REZ/6773 Thèse Bibliothèque principale Thèses Disponible Transfert convectif dans une cavité totalement ou partiellement occupée par une matrice poreuse en ETL ou HETL / Abderrahim Bourouis
Titre : Transfert convectif dans une cavité totalement ou partiellement occupée par une matrice poreuse en ETL ou HETL Type de document : texte imprimé Auteurs : Abderrahim Bourouis, Auteur ; Abdeslam Omara, Auteur Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2016 Importance : 131 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : Convection Mixte Conjuguée Convection Naturelle Milieu Poreux Hors Équilibre Thermique Local Phase Solide Phase Fluide Volumes Finis Conjugate Mixed Convection Natural Convection Porous Medium Local Thermal non Equilibrium Solid Phase Fluid Phase Finite-Volume Method ??? ????? ????? ??? ????? ??? ??????? ??????? ??????? ??? ???? ??? ??? ?????? ???????? Index. décimale : 530 Physique Résumé : In this work, a numerical study of convective heat transfer in confined fluid and porous media was considered. The fluid flow is governed by the Navier–Stokes equations in the fluid region whereas the Darcy–Brinkman–Forchheimer model in the porous region. The finite volume method is used in order to discrete the governing equations, and the SIMPLE algorithm is used to treat the coupling pressure-velocity.
Initially, the first application is to examine the effects of the Richardson number (Ri = 0.1, 1, 10) and thermal conductivity ratio (Rk = 0.1, 1, 10, 100) on the heat transfer by conjugate mixed convection and conduction in a lid-driven enclosure with thick vertical porous layer. The left vertical moving wall of enclosure takes two different directions, (upward or downward moving wall). In this study, the compression of isotherms in the porous layer is observed at low conductivity ratio, while at large conductivity ratio, isotherms span the fluid filled part of the enclosure. It is also observed that average Nusselt numbers along the right hot wall and along the fluid-porous layer interface tend to zero at large and low thermal conductivity ratio, respectively.
For the second application, we have considered a thermal non-equilibrium approach on
natural convection in a square porous cavity with partial active vertical walls. Depending on the location of hot part and cold part, respectively on the left and right side walls, two cases are considered: Upper-Lower and Lower-Upper active walls. The two equations model is used to take into account separately local temperatures of the fluid and the solid. The effect of the Rayleigh number, Darcy number, inter-phase heat transfer coefficient and modified conductivity ratio is examined. The obtained results reveal that the location of the hot and cold parts on the vertical side walls has a significant influence on the flow structure and the rate of heat transfer within the enclosure.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/BOU6987.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10407 Transfert convectif dans une cavité totalement ou partiellement occupée par une matrice poreuse en ETL ou HETL [texte imprimé] / Abderrahim Bourouis, Auteur ; Abdeslam Omara, Auteur . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2016 . - 131 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : Convection Mixte Conjuguée Convection Naturelle Milieu Poreux Hors Équilibre Thermique Local Phase Solide Phase Fluide Volumes Finis Conjugate Mixed Convection Natural Convection Porous Medium Local Thermal non Equilibrium Solid Phase Fluid Phase Finite-Volume Method ??? ????? ????? ??? ????? ??? ??????? ??????? ??????? ??? ???? ??? ??? ?????? ???????? Index. décimale : 530 Physique Résumé : In this work, a numerical study of convective heat transfer in confined fluid and porous media was considered. The fluid flow is governed by the Navier–Stokes equations in the fluid region whereas the Darcy–Brinkman–Forchheimer model in the porous region. The finite volume method is used in order to discrete the governing equations, and the SIMPLE algorithm is used to treat the coupling pressure-velocity.
Initially, the first application is to examine the effects of the Richardson number (Ri = 0.1, 1, 10) and thermal conductivity ratio (Rk = 0.1, 1, 10, 100) on the heat transfer by conjugate mixed convection and conduction in a lid-driven enclosure with thick vertical porous layer. The left vertical moving wall of enclosure takes two different directions, (upward or downward moving wall). In this study, the compression of isotherms in the porous layer is observed at low conductivity ratio, while at large conductivity ratio, isotherms span the fluid filled part of the enclosure. It is also observed that average Nusselt numbers along the right hot wall and along the fluid-porous layer interface tend to zero at large and low thermal conductivity ratio, respectively.
For the second application, we have considered a thermal non-equilibrium approach on
natural convection in a square porous cavity with partial active vertical walls. Depending on the location of hot part and cold part, respectively on the left and right side walls, two cases are considered: Upper-Lower and Lower-Upper active walls. The two equations model is used to take into account separately local temperatures of the fluid and the solid. The effect of the Rayleigh number, Darcy number, inter-phase heat transfer coefficient and modified conductivity ratio is examined. The obtained results reveal that the location of the hot and cold parts on the vertical side walls has a significant influence on the flow structure and the rate of heat transfer within the enclosure.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/BOU6987.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10407 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BOU/6987 BOU/6987 Thèse Bibliothèque principale Thèses Disponible 
Titre : Contribution a l’etude de la convection naturelle au sein d’un tube elliptique rempli d’un milieu poreux sature de fluide Type de document : texte imprimé Auteurs : Amel Labed, Auteur ; Mahfoud Djezzar, Directeur de thèse Editeur : Constantine : Université Mentouri Constantine Année de publication : 2012 Importance : 84 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : convection naturelle équations de Boussinesq milieu poreux espace annulaire elliptique Formulation vorticité-fonction de courant natural convection Boussinesq equations porous medium elliptical annulus Darcy flow model velocity-function formulation ????? ???????-?????????????-??? ?????-???? ???? ????????-????? ?????? ???????? Index. décimale : 530 Physique Résumé : The purpose of the present paper is to analyze numerically the flow and heat transfer by steady laminar natural convection in a elliptical horizontal annulus filled with a Newtonian incompressible fluid saturated porous medium, with an isothermal inner and outer boundary. This study is carried out using the Darcy flow model, Boussinesq’s approximation and the vorticity-stream function formulation, the continuity and the momentum equations are expressed in a frame of reference known as "elliptic ", to facilitate the writing of the boundary conditions and to transform the curvilinear field into a rectangular field. A computer code was developed, using finite volume method. The stream lines and temperature distributions are presented and analyzed, examining the slope, geometric parameters and Rayleigh-Darcy effect. Diplôme : Magistère En ligne : ../theses/physique/LAB6321.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=6288 Contribution a l’etude de la convection naturelle au sein d’un tube elliptique rempli d’un milieu poreux sature de fluide [texte imprimé] / Amel Labed, Auteur ; Mahfoud Djezzar, Directeur de thèse . - Constantine : Université Mentouri Constantine, 2012 . - 84 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : convection naturelle équations de Boussinesq milieu poreux espace annulaire elliptique Formulation vorticité-fonction de courant natural convection Boussinesq equations porous medium elliptical annulus Darcy flow model velocity-function formulation ????? ???????-?????????????-??? ?????-???? ???? ????????-????? ?????? ???????? Index. décimale : 530 Physique Résumé : The purpose of the present paper is to analyze numerically the flow and heat transfer by steady laminar natural convection in a elliptical horizontal annulus filled with a Newtonian incompressible fluid saturated porous medium, with an isothermal inner and outer boundary. This study is carried out using the Darcy flow model, Boussinesq’s approximation and the vorticity-stream function formulation, the continuity and the momentum equations are expressed in a frame of reference known as "elliptic ", to facilitate the writing of the boundary conditions and to transform the curvilinear field into a rectangular field. A computer code was developed, using finite volume method. The stream lines and temperature distributions are presented and analyzed, examining the slope, geometric parameters and Rayleigh-Darcy effect. Diplôme : Magistère En ligne : ../theses/physique/LAB6321.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=6288 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité LAB/6321 LAB/6321 Thèse Bibliothèque principale Thèses Disponible Documents numériques
texte intégraleAdobe Acrobat PDF
Titre : Contribution a l’etude numerique de la convection naturelle laminaire d’un systeme radial de chauffage solaire Type de document : texte imprimé Auteurs : Tahar Tayebi, Auteur ; Mahfoud Djezzar, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 124 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
PhysiqueTags : Enrgies renouvelables Système Radial de Chauffage Solaire Energie Solaire Appliquée Convection Naturelle Etude Numérique 2D et 3D Radial Solar heater System Applied Solar Energy Natural Convection 2D and 3D Numerical Study ???? ??????? ?????? ??????? ??????? ??????? ?????? ??????? ????? ??????? ??????? ?????? ????? ??????
??????? ???????Index. décimale : 530 Physique Résumé : The author proposes in this thesis, a numerical study of laminar natural convection in a Solar Heater Radial System. Two different simulations were performed. First, the two-dimensional governing equations have been solved numerically using a validate computer code. The Transported fluid is the air (Pr =0.702), it is considered as a Newtonian and incompressible fluid based on the Boussinesq approximations, the governing equations are taken to be in the vorticitystream function formulation in hyperbolic coordinates. For heating conditions we suppose an
isothermal walls of the collector (Tc for the ground and Tf for the roof, with Tc > Tf). Solution of
the defined equations has been done with numerical control volume method. We examined the effect of the system geometry on the natural convection phenomenon in the solar chimney.
Finally, the simulation results have been given as airflows and temperature patterns.
Then, a 3D numerical simulation was performed using the FLUENT software to simulate a three-dimensional model of a solar chimney power plant. The simulation was performed for the geometry of the Manzanares prototype, in Spain. The distribution of temperature, velocity and pressure in the system are shown for three different solar radiations. Good quantitative agreement was obtained between the experimental and numerical data and our numerical results.
This result (2D and 3D) will let the solar chimney designer locate correctly the turbine in the solar chimney power plant and estimate the power that could be exploited.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/TAY6709.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9914 Contribution a l’etude numerique de la convection naturelle laminaire d’un systeme radial de chauffage solaire [texte imprimé] / Tahar Tayebi, Auteur ; Mahfoud Djezzar, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 124 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
PhysiqueTags : Enrgies renouvelables Système Radial de Chauffage Solaire Energie Solaire Appliquée Convection Naturelle Etude Numérique 2D et 3D Radial Solar heater System Applied Solar Energy Natural Convection 2D and 3D Numerical Study ???? ??????? ?????? ??????? ??????? ??????? ?????? ??????? ????? ??????? ??????? ?????? ????? ??????
??????? ???????Index. décimale : 530 Physique Résumé : The author proposes in this thesis, a numerical study of laminar natural convection in a Solar Heater Radial System. Two different simulations were performed. First, the two-dimensional governing equations have been solved numerically using a validate computer code. The Transported fluid is the air (Pr =0.702), it is considered as a Newtonian and incompressible fluid based on the Boussinesq approximations, the governing equations are taken to be in the vorticitystream function formulation in hyperbolic coordinates. For heating conditions we suppose an
isothermal walls of the collector (Tc for the ground and Tf for the roof, with Tc > Tf). Solution of
the defined equations has been done with numerical control volume method. We examined the effect of the system geometry on the natural convection phenomenon in the solar chimney.
Finally, the simulation results have been given as airflows and temperature patterns.
Then, a 3D numerical simulation was performed using the FLUENT software to simulate a three-dimensional model of a solar chimney power plant. The simulation was performed for the geometry of the Manzanares prototype, in Spain. The distribution of temperature, velocity and pressure in the system are shown for three different solar radiations. Good quantitative agreement was obtained between the experimental and numerical data and our numerical results.
This result (2D and 3D) will let the solar chimney designer locate correctly the turbine in the solar chimney power plant and estimate the power that could be exploited.
Diplôme : Doctorat en sciences En ligne : ../theses/physique/TAY6709.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9914 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité TAY/6709 TAY/6709 Thèse Bibliothèque principale Thèses Disponible
Titre : Génération d’entropie due au refroidissement par convection naturelle d’un nanofluide Type de document : texte imprimé Auteurs : Abd el malik Bouchoucha, Auteur ; Rachid Bessaih, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 159 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : Nanofluide Génération d’entropie Convection naturelle Cavité Nanofluid Entropy generation Natural convection Cavity ????? ?????? ????? ? ???????? ????? ??????? ??????? ???? Index. décimale : 620 Génie Mécanique Résumé : Venous thromboembolism (VTE) is a multifactorial disease in which the genetic
component is important.Many genetic risk factors have been identified for causing VTE.
Most of them affect the function of natural anticoagulant pathways, particularly the prote
Diplôme : Doctorat En ligne : ../theses/gmecanique/BOU7046.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10553 Génération d’entropie due au refroidissement par convection naturelle d’un nanofluide [texte imprimé] / Abd el malik Bouchoucha, Auteur ; Rachid Bessaih, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 159 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : Nanofluide Génération d’entropie Convection naturelle Cavité Nanofluid Entropy generation Natural convection Cavity ????? ?????? ????? ? ???????? ????? ??????? ??????? ???? Index. décimale : 620 Génie Mécanique Résumé : Venous thromboembolism (VTE) is a multifactorial disease in which the genetic
component is important.Many genetic risk factors have been identified for causing VTE.
Most of them affect the function of natural anticoagulant pathways, particularly the prote
Diplôme : Doctorat En ligne : ../theses/gmecanique/BOU7046.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10553 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité BOU/7046 BOU/7046 Thèse Bibliothèque principale Thèses Disponible Permalink
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