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Partager le résultat de cette recherche Interroger des sources externesEffet des propriétés thermophysiques variables sur la convection mixte dans l’espace annulaire entre deux cylindres elliptique horizontaux / Khalil Zerari
Titre : Effet des propriétés thermophysiques variables sur la convection mixte dans l’espace annulaire entre deux cylindres elliptique horizontaux Type de document : texte imprimé Auteurs : Khalil Zerari, Auteur ; M. Afrid, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 198 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : Mixed convection Temperature dependent properties Elliptic confocal cylinders Finite volume method Convection mixte Propriétés dépendent de la température cylindres elliptiques confocaux la méthode des volumes finis ????? ??????? ??????? ?????? ?????????? ?????? ????? ??????? ???????? ?????
????? ??????? ????? ????? ?????? ????????Index. décimale : 530 Physique Résumé :
This study presents a numerical simulation of the three dimensional laminar mixed convection between two elliptical horizontal cylinders using temperature dependent physical properties.
The inner cylinder is uniformly heated whereas the outer cylinder is adiabatic. The flow and thermal fields are modeled by the continuity, momentum and energy equations with appropriate initial and boundary conditions using an elliptical coordinate system. The model equations are numerically solved by a finite volume numerical method with second order accurate spatiotemporal discretizations. For the considered geometric, dynamic and thermal controlling parameters, it is found that the realistic consideration of the mixed convection with variable physical properties gives physically sound flows and thermal fields that are qualitatively and quantitatively different from those of forced convection with temperature dependent properties and those of mixed convection with constant properties; the obtained Nusselt number is also higher in this case. The heat transfer enhancement obtained by considering natural convection within mixed convection with temperature dependent physical properties increases with the increased Grashof number which is proportional to the heat flux imposed at the surface of the
inner cylinder.Diplôme : Doctorat en sciences En ligne : ../theses/physique/ZER6483.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9542 Effet des propriétés thermophysiques variables sur la convection mixte dans l’espace annulaire entre deux cylindres elliptique horizontaux [texte imprimé] / Khalil Zerari, Auteur ; M. Afrid, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 198 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Mixed convection Temperature dependent properties Elliptic confocal cylinders Finite volume method Convection mixte Propriétés dépendent de la température cylindres elliptiques confocaux la méthode des volumes finis ????? ??????? ??????? ?????? ?????????? ?????? ????? ??????? ???????? ?????
????? ??????? ????? ????? ?????? ????????Index. décimale : 530 Physique Résumé :
This study presents a numerical simulation of the three dimensional laminar mixed convection between two elliptical horizontal cylinders using temperature dependent physical properties.
The inner cylinder is uniformly heated whereas the outer cylinder is adiabatic. The flow and thermal fields are modeled by the continuity, momentum and energy equations with appropriate initial and boundary conditions using an elliptical coordinate system. The model equations are numerically solved by a finite volume numerical method with second order accurate spatiotemporal discretizations. For the considered geometric, dynamic and thermal controlling parameters, it is found that the realistic consideration of the mixed convection with variable physical properties gives physically sound flows and thermal fields that are qualitatively and quantitatively different from those of forced convection with temperature dependent properties and those of mixed convection with constant properties; the obtained Nusselt number is also higher in this case. The heat transfer enhancement obtained by considering natural convection within mixed convection with temperature dependent physical properties increases with the increased Grashof number which is proportional to the heat flux imposed at the surface of the
inner cylinder.Diplôme : Doctorat en sciences En ligne : ../theses/physique/ZER6483.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9542 Exemplaires
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Titre : Étude numérique de la convection mixte en milieu poreux dans un canal contenant des composants électroniques Type de document : texte imprimé Auteurs : Lyes Boutina, Auteur ; R. Bessaih, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 115 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : Convection mixte Canal Refroidissement à air Composants électroniques milieux poreux mixed convection channel air-cooling electronic components porous medium ????? ??????? ???? ???????? ???????? Index. décimale : 620 Génie Mécanique Résumé :
A numerical study of laminar mixed convection air-cooling of two identical heat sources enveloped by a porous matrix has been presented in this work. The flow field is governed by the Navier–Stokes equations in the fluid region, the Darcy–Brinkman–Forchheimer model in the porous region, and the thermal field by the energy equation. The numerical calculation was carried out using the software ""FLUENT"", based on the finite volume method.
The first application is to examine the effects of the Reynolds number, the inclination angle, the size of electronic components and the space between them on the heat transfer inside a two-dimensional (2D) vertical channel. The results show that increasing of the Reynolds number and the separation distance can enhance the cooling of electronic components. For an inclinaison angle (α = 45 °), the maximum heat transfer was obtained. For the second application, we have considered a two-dimensional (2D) vertical channel, containing two electronic components wrapped by a porous matrix. The effects of the Reynolds number, the inclination angle, the Darcy number, the thickness of the porous layer and their conductivity have been examined. The results show that the thickness of the porous matrix improves the cooling of electronic components inside the channel, about 60% higher compared to the case without integration of the porous matrix. The increase of the Darcy number (10-3 ≤ Da ≤ 10-6) causes a decrease of the maximum temperature in the channel, which contributes to the cooling of electronic components. The insertion of the porous matrix with a thermal conductivity in the range ke/kf ≤ 50 improves the cooling of heat sources. For the third application, we have considered a three-dimensional (3D) vertical channel, containing two electronic components wrapped by a porous matrix. The effects of the Reynolds number, the Darcy number and the thickness of the porous layer have been examined. The results show that proper cooling of electronic components is obtained for a channel completely filled with a porous matrix with high thermal conductivity (ke / kf = 100), with Re = 200 and Gr = 104 ( Ri = Gr/Re2=0.25) and for all values of the Darcy number (10-3 ≤ Da ≤ 10-6).Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6604.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9717 Étude numérique de la convection mixte en milieu poreux dans un canal contenant des composants électroniques [texte imprimé] / Lyes Boutina, Auteur ; R. Bessaih, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 115 f. ; 30 cm.
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Langues : Français (fre)
Tags : Convection mixte Canal Refroidissement à air Composants électroniques milieux poreux mixed convection channel air-cooling electronic components porous medium ????? ??????? ???? ???????? ???????? Index. décimale : 620 Génie Mécanique Résumé :
A numerical study of laminar mixed convection air-cooling of two identical heat sources enveloped by a porous matrix has been presented in this work. The flow field is governed by the Navier–Stokes equations in the fluid region, the Darcy–Brinkman–Forchheimer model in the porous region, and the thermal field by the energy equation. The numerical calculation was carried out using the software ""FLUENT"", based on the finite volume method.
The first application is to examine the effects of the Reynolds number, the inclination angle, the size of electronic components and the space between them on the heat transfer inside a two-dimensional (2D) vertical channel. The results show that increasing of the Reynolds number and the separation distance can enhance the cooling of electronic components. For an inclinaison angle (α = 45 °), the maximum heat transfer was obtained. For the second application, we have considered a two-dimensional (2D) vertical channel, containing two electronic components wrapped by a porous matrix. The effects of the Reynolds number, the inclination angle, the Darcy number, the thickness of the porous layer and their conductivity have been examined. The results show that the thickness of the porous matrix improves the cooling of electronic components inside the channel, about 60% higher compared to the case without integration of the porous matrix. The increase of the Darcy number (10-3 ≤ Da ≤ 10-6) causes a decrease of the maximum temperature in the channel, which contributes to the cooling of electronic components. The insertion of the porous matrix with a thermal conductivity in the range ke/kf ≤ 50 improves the cooling of heat sources. For the third application, we have considered a three-dimensional (3D) vertical channel, containing two electronic components wrapped by a porous matrix. The effects of the Reynolds number, the Darcy number and the thickness of the porous layer have been examined. The results show that proper cooling of electronic components is obtained for a channel completely filled with a porous matrix with high thermal conductivity (ke / kf = 100), with Re = 200 and Gr = 104 ( Ri = Gr/Re2=0.25) and for all values of the Darcy number (10-3 ≤ Da ≤ 10-6).Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/BOU6604.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9717 Exemplaires
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Titre : Étude Numérique de la Convection Mixte dans un Canal Horizontal Contenant des Ailettes Type de document : texte imprimé Auteurs : Moussa Khentoul, Auteur ; R. Bessaih, 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) Tags : Convection mixte Canal horizontal Refroidissement nanofluide Ailettes Mixed convection horizontal channel Cooling nanofluid fins ????? ??????? ???? ????? ????? ???? ??????? ???????? Index. décimale : 620 Génie Mécanique Résumé : Heat transfer is very important for good design and reliable operation of a system.
Reliability and system performance are highly dependent on the operating temperature,
in particular, in electronic equipment. Several cooling methods have been proposed in
order to improve the heat transfer. These techniques include two: which consists in
grafting blades offering a greater contact surface with the environment; and which
consists of using nanofluids comprising metallic particles or carbon nanotubes. The
latter is currently present the best solution.
In the first part of the thesis, a numerical study of 2D laminar mixed convection in
a horizontal channel with three fins nanofluid has been carried out made. The influence
of Reynolds and Richardson numbers and concentration of nanoparticles (Al2O3, Cu, Ag
and TiO2) dispersed in a base fluid (water), on the flow and thermal fields is presented.
A computer code in Fortran, based on finite volume method was used to simulate 2D
flow with heat transfer. The results indicate that the addition of nanoparticles in pure
water can improve the cooling performance, in particular, low Richardson number. The
influence of the solid volume fraction on increasing the heat transfer is more sensitive to
higher values of Reynolds number. Although, the addition of nanofluids (TiO2 and
Al
2O3) also increases heat transfer, their influence is not important for Cu-Ag-water and
water.
The second part is to find an optimal geometry for good cooling. Numerical
calculations were carried out using the software ""FLUENT 6.3"" to simulate 3D laminar
mixed convection flow in a channel containing fins with nanofluid. The effects of
Reynolds number, height, and distance between the fins are presented and discussed.
Diplôme : Doctorat En ligne : ../theses/gmecanique/KHE6947.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10324 Étude Numérique de la Convection Mixte dans un Canal Horizontal Contenant des Ailettes [texte imprimé] / Moussa Khentoul, Auteur ; R. Bessaih, Auteur . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2016 . - 131 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Convection mixte Canal horizontal Refroidissement nanofluide Ailettes Mixed convection horizontal channel Cooling nanofluid fins ????? ??????? ???? ????? ????? ???? ??????? ???????? Index. décimale : 620 Génie Mécanique Résumé : Heat transfer is very important for good design and reliable operation of a system.
Reliability and system performance are highly dependent on the operating temperature,
in particular, in electronic equipment. Several cooling methods have been proposed in
order to improve the heat transfer. These techniques include two: which consists in
grafting blades offering a greater contact surface with the environment; and which
consists of using nanofluids comprising metallic particles or carbon nanotubes. The
latter is currently present the best solution.
In the first part of the thesis, a numerical study of 2D laminar mixed convection in
a horizontal channel with three fins nanofluid has been carried out made. The influence
of Reynolds and Richardson numbers and concentration of nanoparticles (Al2O3, Cu, Ag
and TiO2) dispersed in a base fluid (water), on the flow and thermal fields is presented.
A computer code in Fortran, based on finite volume method was used to simulate 2D
flow with heat transfer. The results indicate that the addition of nanoparticles in pure
water can improve the cooling performance, in particular, low Richardson number. The
influence of the solid volume fraction on increasing the heat transfer is more sensitive to
higher values of Reynolds number. Although, the addition of nanofluids (TiO2 and
Al
2O3) also increases heat transfer, their influence is not important for Cu-Ag-water and
water.
The second part is to find an optimal geometry for good cooling. Numerical
calculations were carried out using the software ""FLUENT 6.3"" to simulate 3D laminar
mixed convection flow in a channel containing fins with nanofluid. The effects of
Reynolds number, height, and distance between the fins are presented and discussed.
Diplôme : Doctorat En ligne : ../theses/gmecanique/KHE6947.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10324 Exemplaires
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Titre : Etude de la convection mixte dans des cavités. Type de document : texte imprimé Auteurs : Ilhem Zeghbid, Auteur ; R. Bessaih, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 172 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : Mixed convection Cavities Entropy generation Nanofluid Convection mixte Cavités Génération d’entropie Nanofluide ???? ????? ????? ??????? ????? ?????? Index. décimale : 620 Génie Mécanique Résumé : The aim of this work is to study numerically the laminar mixed convection and
entropy generation in cavities. The calculations were performed for water (Cu, Ag)
metallic nanofluids and water-(AlO3, TiO2) metal oxides. The fluids are supposed
incompressible and Newtonian. The equations governing the flow and heat transfer have
been solved using the finite volume method. A house code in FORTRAN has been
developed to calculate the flow and temperature fields, the Nusselt number, and the
entropy generation. The effects of Rayleigh and Reynolds numbers , the volume fraction
of the nanofluid, the nanofluid type, and the position of the heat sources on the flow and
thermal fields, the average Nusselt number, entropy generation, and the Bejan number
are studied in detail. The results show that the use of nanofluids improves heat transfer
and reduces the entropy generation. Finally, a three-dimensional numerical study of
laminar forced convection in a cubic cavity filled with different nanofluids is presented.
In this study, the Ansys-Fluent 14 software was used to solve the equations of the
problem in questionDiplôme : Doctorat en sciences En ligne : ../theses/gmecanique/ZEG7096.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10508 Etude de la convection mixte dans des cavités. [texte imprimé] / Ilhem Zeghbid, Auteur ; R. Bessaih, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 172 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Mixed convection Cavities Entropy generation Nanofluid Convection mixte Cavités Génération d’entropie Nanofluide ???? ????? ????? ??????? ????? ?????? Index. décimale : 620 Génie Mécanique Résumé : The aim of this work is to study numerically the laminar mixed convection and
entropy generation in cavities. The calculations were performed for water (Cu, Ag)
metallic nanofluids and water-(AlO3, TiO2) metal oxides. The fluids are supposed
incompressible and Newtonian. The equations governing the flow and heat transfer have
been solved using the finite volume method. A house code in FORTRAN has been
developed to calculate the flow and temperature fields, the Nusselt number, and the
entropy generation. The effects of Rayleigh and Reynolds numbers , the volume fraction
of the nanofluid, the nanofluid type, and the position of the heat sources on the flow and
thermal fields, the average Nusselt number, entropy generation, and the Bejan number
are studied in detail. The results show that the use of nanofluids improves heat transfer
and reduces the entropy generation. Finally, a three-dimensional numerical study of
laminar forced convection in a cubic cavity filled with different nanofluids is presented.
In this study, the Ansys-Fluent 14 software was used to solve the equations of the
problem in questionDiplôme : Doctorat en sciences En ligne : ../theses/gmecanique/ZEG7096.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10508 Exemplaires
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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) Tags : 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)
Tags : 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
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