4 recherche sur le tag 'نقل الحرارة'   

Contribution à l’intensification des transferts thermiques par un nanofluide dans un échangeur thermique à tube elliptique coaxial. / Abdeslem Bouzerzour  

Public ISBD Titre : Contribution à l’intensification des transferts thermiques par un nanofluide dans un échangeur thermique à tube elliptique coaxial. Type de document : texte imprimé Auteurs : Abdeslem Bouzerzour, Auteur ; Mahfoud Djezzar, Directeur de thèse Mention d'édition : 20/10/2020 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2020 Importance : 79 f. Format : 30 cm. Note générale : Doctorat 3éme CYCLE LMD. 1 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais Physique Tags : physique: Energies Renouvelables  Transferts de chaleur  Convection naturelle  Espace annulaire elliptique  Formulation vorticité-fonction de courant  nanofluide  chauffage partiel  Heat transfers  Natural convection  Elliptical annular space  Vorticity-Stream function formulation  nanofluid  partial heating  نقل الحرارة  الحمل الحراري الطبيعي  الحيز الحلقي الإهليليجي  صياغة التدويم-دالة التيار  مائع نانومتري  التسخين الجزئي Index. décimale : 530 Physique Résumé : The author presents here, a contribution to the study of two-dimensional laminar natural convection of Newtonian incompressible nanofluids confined in coaxial elliptical tubes heat exchanger. The external wall is maintained cold while the internal wall is subjected to different parietal thermal conditions. The effects of inclination angle and the injected nanoparticles type are examined for considered, Rayleigh number and volume fraction, values. A numerical code with finite volumes method based on Vorticity-Stream function formulation is developed to resolve the continuity, momentum, and energy equations written in elliptic coordinates considering Boussinesq approximation. The study consists of three parts, for different Rayleigh numbers (103 Diplôme : Doctorat En ligne : ../theses/physique/BOU7655.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11489 Contribution à l’intensification des transferts thermiques par un nanofluide dans un échangeur thermique à tube elliptique coaxial. [texte imprimé] / Abdeslem Bouzerzour, Auteur ; Mahfoud Djezzar, Directeur de thèse  . -  20/10/2020 . - جامعة الإخوة منتوري قسنطينة, 2020 . - 79 f. ; 30 cm. Doctorat 3éme CYCLE LMD. 1 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais Physique Tags : physique: Energies Renouvelables  Transferts de chaleur  Convection naturelle  Espace annulaire elliptique  Formulation vorticité-fonction de courant  nanofluide  chauffage partiel  Heat transfers  Natural convection  Elliptical annular space  Vorticity-Stream function formulation  nanofluid  partial heating  نقل الحرارة  الحمل الحراري الطبيعي  الحيز الحلقي الإهليليجي  صياغة التدويم-دالة التيار  مائع نانومتري  التسخين الجزئي Index. décimale : 530 Physique Résumé : The author presents here, a contribution to the study of two-dimensional laminar natural convection of Newtonian incompressible nanofluids confined in coaxial elliptical tubes heat exchanger. The external wall is maintained cold while the internal wall is subjected to different parietal thermal conditions. The effects of inclination angle and the injected nanoparticles type are examined for considered, Rayleigh number and volume fraction, values. A numerical code with finite volumes method based on Vorticity-Stream function formulation is developed to resolve the continuity, momentum, and energy equations written in elliptic coordinates considering Boussinesq approximation. The study consists of three parts, for different Rayleigh numbers (103 Diplôme : Doctorat En ligne : ../theses/physique/BOU7655.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11489

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
BOU/7655	BOU/7655	Thèse	Bibliothèque principale	Thèses	Disponible

Convection forcée et mixte dans un espace annulaire elliptique horizontal et incliné rempli par une mousse métallique / Meriem Benmerkhi  

Public ISBD 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 Physique Tags : 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 : pdf 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 Physique Tags : 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 : pdf 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

Investigation des échanges convectifs dans diverses configurations / Issam Rezaiguia  

Public ISBD 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 Mécanique Tags : 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  الحمل الحراري الطبيعي  مائع نانوي  تجويف ثلاثي الشكل  زاوية الميل  محاكاة العددية  قنوات ميكروية  هبوط الضغط  نقل الحرارة  نسب الحيود للذرات الصلبة  سلوك غير نيوتوني 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 : pdf 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 [Algérie] : Université Constantine 1, 2014 . - 142 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais Génie Mécanique Tags : 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  الحمل الحراري الطبيعي  مائع نانوي  تجويف ثلاثي الشكل  زاوية الميل  محاكاة العددية  قنوات ميكروية  هبوط الضغط  نقل الحرارة  نسب الحيود للذرات الصلبة  سلوك غير نيوتوني 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 : pdf 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

Optimisation des echangeurs compacts application du logiciel fluent / Nada Benayad  

Public ISBD Titre : Optimisation des echangeurs compacts application du logiciel fluent Type de document : texte imprimé Auteurs : Nada Benayad, Auteur ; N. Bellel, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 150 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais Physique Tags : échangeur coaxial  Fluent  modèles de turbulences  écoulement tridimensionnel  turbulence  transfert thermique  coaxial exchanger  turbulence models  three-dimensional flow  heat transfer  مبادل المحوري  نماذج الاضطراب  تدفق ثلاثي الأبعاد  الاضطراب  نقل الحرارة Index. décimale : 530 Physique Résumé : Experimental and numerical simulation studies of a three-dimensional turbulent flow of water in a coaxial exchanger are presented. The heat exchanger was divided into three equal sections to allow examination of the intermediate stream temperatures using thermocouples that capture the current temperatures of the four stations and the wall temperatures in the inlet and Release. Exchanger water / water heat turbulent flow. H 951 was designed to obtain quantitative results on the coefficients of heat transfer surface and global exchanger concentric tubes in turbulent flow. This compact unit designed to be installed on a table establishes, inter alia, the relationship between the Nusselt number, Reynolds and Prandtl, and the comparison of results in parallel flow or against the current. The second part of the study was done by numerical simulation; we tested the mathematical model k − ε using finite volume in healthy fluent software. This work contributes greatly to the understanding of turbulent flows in a coaxial heat exchanger, and also shows the effect of physical parameters (temperature, diameter, flow rate) on the establishment of the turbulent flow in a coaxial heat exchanger. The results obtained in this dynamics study of water in turbulent flow by the experimental and numerical study components are in good agreement and correspond to the results given in the literature (J.castaing-Lasvignottes). It has been found that the turbulent compact coaxial exchanger has a good configuration as it gives significant power exchange for surfaces too small. Flow phenomena of interest were observed. One can quote for example: The effect of various parameters (temperature, speed, and diameter) on the establishment of turbulent flow, the effect of the turbulence in the flow and in particular the behavior of the axial and tangential velocity fluctuations in this configuration exchanger has been shown numerically Diplôme : Doctorat en sciences En ligne : ../theses/physique/BEN6818.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10088 Optimisation des echangeurs compacts application du logiciel fluent [texte imprimé] / Nada Benayad, Auteur ; N. Bellel, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2015 . - 150 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Catégories : Français - Anglais Physique Tags : échangeur coaxial  Fluent  modèles de turbulences  écoulement tridimensionnel  turbulence  transfert thermique  coaxial exchanger  turbulence models  three-dimensional flow  heat transfer  مبادل المحوري  نماذج الاضطراب  تدفق ثلاثي الأبعاد  الاضطراب  نقل الحرارة Index. décimale : 530 Physique Résumé : Experimental and numerical simulation studies of a three-dimensional turbulent flow of water in a coaxial exchanger are presented. The heat exchanger was divided into three equal sections to allow examination of the intermediate stream temperatures using thermocouples that capture the current temperatures of the four stations and the wall temperatures in the inlet and Release. Exchanger water / water heat turbulent flow. H 951 was designed to obtain quantitative results on the coefficients of heat transfer surface and global exchanger concentric tubes in turbulent flow. This compact unit designed to be installed on a table establishes, inter alia, the relationship between the Nusselt number, Reynolds and Prandtl, and the comparison of results in parallel flow or against the current. The second part of the study was done by numerical simulation; we tested the mathematical model k − ε using finite volume in healthy fluent software. This work contributes greatly to the understanding of turbulent flows in a coaxial heat exchanger, and also shows the effect of physical parameters (temperature, diameter, flow rate) on the establishment of the turbulent flow in a coaxial heat exchanger. The results obtained in this dynamics study of water in turbulent flow by the experimental and numerical study components are in good agreement and correspond to the results given in the literature (J.castaing-Lasvignottes). It has been found that the turbulent compact coaxial exchanger has a good configuration as it gives significant power exchange for surfaces too small. Flow phenomena of interest were observed. One can quote for example: The effect of various parameters (temperature, speed, and diameter) on the establishment of turbulent flow, the effect of the turbulence in the flow and in particular the behavior of the axial and tangential velocity fluctuations in this configuration exchanger has been shown numerically Diplôme : Doctorat en sciences En ligne : ../theses/physique/BEN6818.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10088

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
BEN/6818	BEN/6818	Thèse	Bibliothèque principale	Thèses	Disponible