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Titre : Effet de l’ondulation de la surface sur le transfert de chaleur par jet impactant. Type de document : texte imprimé Auteurs : Amina Derdouri, Auteur ; Zoubir Nemouchi, Auteur Mention d'édition : 22 / 03 / 2021 Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2021 Importance : 80 f. Format : 30 cm. Note générale : 1 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : G.Mécanique: Energétique jet impactant axisymétrique plan surface ondulée cavité carrée transfert de chaleur nombre de Nusselt modèle de turbulence SST k-ω approche LES axisymmetric impinging jet slot-jet grooved surface square grooves heat transfer Nusselt number SST k-ω turbulence model LES approach نقاث مصطدم ذو تناظر محوري مستو سطح متموج تجويف مربع الانتقال الحراري عدد نوسلت نموذج الاضطراب SST k-ω مقاربة LES Index. décimale : 620 Génie Mécanique Résumé :
The present work is a numerical simulation by the ANSYS Fluent code of a jet impinging on a surface fitted with square-shaped grooves. In the first part of this thesis, a parametric study on the flow dynamics and the heat transfer in an axisymmetric turbulent impinging jet is carried out using the SST k-ω turbulence model. Different parameters are varied: the groove size C, ranging from 0 to 1.5 (mm) (where C = 0 represents the smooth surface), the nozzleto-wall distance H/D ranging from 1 to 4, and the Reynolds number Re ranging from 5000 to 30000. The velocity, kinetic energy and temperature fields in the different regions of the domain and in particular inside the grooves are presented and discussed. The results show that an increase in the cavity size leads to an increase in friction and heat transfer. The comparison between the smooth wall and the corrugated walls shows that the latter improve the average Nusselt number by 80%, 82% and 85%, for the groove sizes 0.5, 1 and 1.5 mm respectively.
Concerning the effect of the nozzle-to-target-surface distance the best heat transfer performance is obtained by using the small distance H/D = 1. As for the effect of the Reynolds number, the highest value of the Nusselt number obtained corresponds to the value of Re = 30000. In the second part of the work, the unsteady turbulent isothermal flow of a plane-in-the-mean semi-confined jet impinging on a surface fitted with square grooves is simulated using the LES approach. The configuration considered is such that the nozzle-towall distance H/L = 2, the cavity size C = 5 (mm) and the Reynolds number Re = 5000.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/DER7742.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11575 Effet de l’ondulation de la surface sur le transfert de chaleur par jet impactant. [texte imprimé] / Amina Derdouri, Auteur ; Zoubir Nemouchi, Auteur . - 22 / 03 / 2021 . - جامعة الإخوة منتوري قسنطينة, 2021 . - 80 f. ; 30 cm.
1 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : G.Mécanique: Energétique jet impactant axisymétrique plan surface ondulée cavité carrée transfert de chaleur nombre de Nusselt modèle de turbulence SST k-ω approche LES axisymmetric impinging jet slot-jet grooved surface square grooves heat transfer Nusselt number SST k-ω turbulence model LES approach نقاث مصطدم ذو تناظر محوري مستو سطح متموج تجويف مربع الانتقال الحراري عدد نوسلت نموذج الاضطراب SST k-ω مقاربة LES Index. décimale : 620 Génie Mécanique Résumé :
The present work is a numerical simulation by the ANSYS Fluent code of a jet impinging on a surface fitted with square-shaped grooves. In the first part of this thesis, a parametric study on the flow dynamics and the heat transfer in an axisymmetric turbulent impinging jet is carried out using the SST k-ω turbulence model. Different parameters are varied: the groove size C, ranging from 0 to 1.5 (mm) (where C = 0 represents the smooth surface), the nozzleto-wall distance H/D ranging from 1 to 4, and the Reynolds number Re ranging from 5000 to 30000. The velocity, kinetic energy and temperature fields in the different regions of the domain and in particular inside the grooves are presented and discussed. The results show that an increase in the cavity size leads to an increase in friction and heat transfer. The comparison between the smooth wall and the corrugated walls shows that the latter improve the average Nusselt number by 80%, 82% and 85%, for the groove sizes 0.5, 1 and 1.5 mm respectively.
Concerning the effect of the nozzle-to-target-surface distance the best heat transfer performance is obtained by using the small distance H/D = 1. As for the effect of the Reynolds number, the highest value of the Nusselt number obtained corresponds to the value of Re = 30000. In the second part of the work, the unsteady turbulent isothermal flow of a plane-in-the-mean semi-confined jet impinging on a surface fitted with square grooves is simulated using the LES approach. The configuration considered is such that the nozzle-towall distance H/L = 2, the cavity size C = 5 (mm) and the Reynolds number Re = 5000.
Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/DER7742.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11575 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité DER/7742 DER/7742 Thèse Bibliothèque principale Thèses Disponible Instabilité et interaction des macrostructures tourbillonnaires avec la couche limite dans une cavité différentiellement chauffée / Djedid Taloub
Titre : Instabilité et interaction des macrostructures tourbillonnaires avec la couche limite dans une cavité différentiellement chauffée Type de document : texte imprimé Auteurs : Djedid Taloub, Auteur ; Abdelhadi Beghidja, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 117 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie MécaniqueTags : Cavité fermée modèle de turbulence simulation des grandes échelles stratification thermique transfert de chaleur, RANS
closed cavity turbulence model large eddy simulation thermal stratification heat transfer تجويف مغلق نموذج التمثيل الرقمي للدوامات المضطربة الكبيرة التحول الحراري نموذج الاضطراب التوازن
الحراريIndex. décimale : 620 Génie Mécanique Résumé : In the recent years, the study of the boundary layer interaction with the flow and the influence of cavity heat transfer for strong Rayleigh numbers (2.5×109 ≤ RaH ≤ 1.4x1011) is use of various numerical simulations. The resulting velocity field can be divided into two domains: the flow of the average field in the cavity, and the fluctuating velocity field of this flow in the cavity. The cavity is the site of instabilities causing or modulating the vortex structures. In this work, a general the prospect of fluid dynamics turbulence and thermal transfer is provided based on previous experimental studies in order to develop new methods allowing the comparison between numerical simulations and experimental results in the case of turbulent
flows with unsteady macrostructures. The turbulence modeling is performed by a LES approach with a sub grid diffusivity model adapted to the natural convection. Therefore, our goal is to compare our numerical results with those obtained experimentally literature on the one hand and those established by other
numerical studies on the other hand.Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/TAL6882.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10202 Instabilité et interaction des macrostructures tourbillonnaires avec la couche limite dans une cavité différentiellement chauffée [texte imprimé] / Djedid Taloub, Auteur ; Abdelhadi Beghidja, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2015 . - 117 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie MécaniqueTags : Cavité fermée modèle de turbulence simulation des grandes échelles stratification thermique transfert de chaleur, RANS
closed cavity turbulence model large eddy simulation thermal stratification heat transfer تجويف مغلق نموذج التمثيل الرقمي للدوامات المضطربة الكبيرة التحول الحراري نموذج الاضطراب التوازن
الحراريIndex. décimale : 620 Génie Mécanique Résumé : In the recent years, the study of the boundary layer interaction with the flow and the influence of cavity heat transfer for strong Rayleigh numbers (2.5×109 ≤ RaH ≤ 1.4x1011) is use of various numerical simulations. The resulting velocity field can be divided into two domains: the flow of the average field in the cavity, and the fluctuating velocity field of this flow in the cavity. The cavity is the site of instabilities causing or modulating the vortex structures. In this work, a general the prospect of fluid dynamics turbulence and thermal transfer is provided based on previous experimental studies in order to develop new methods allowing the comparison between numerical simulations and experimental results in the case of turbulent
flows with unsteady macrostructures. The turbulence modeling is performed by a LES approach with a sub grid diffusivity model adapted to the natural convection. Therefore, our goal is to compare our numerical results with those obtained experimentally literature on the one hand and those established by other
numerical studies on the other hand.Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/TAL6882.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10202 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité TAL/6882 TAL/6882 Thèse Bibliothèque principale Thèses Disponible
Titre : Modélisation numérique tridimensionnelle des processus physico-chimiques dans une pile à combustible à membrane échangeuse de protons. Type de document : texte imprimé Auteurs : Razika Hadjadj ép. Assabaa, Auteur ; Wahiba Kaabar, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2019 Importance : 176 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
ChimieTags : Chimie: Chimie analytique et physique PEMFC CFD écoulement de fluide transfert de masse transfert de chaleur forme
des canaux humidité relative mass transfer heat transfer channels shape relative humidity خلیة وقود ذات غشاء نفوذ للبروتونات أشكال قنوات الغاز دینامیكیة الموائع الحسابیة نقل الكتلة نقل
الحرارة الرطوبة النسبیةIndex. décimale : 540 Chimie et sciences connexes Résumé :
In the current situation of global warming and depletion of oil reserves, the use of proton exchange membrane fuel cells (PEMFC) needs further improvements. In this work, two numerical 3D models have been developed; single-phasic and two-phase water transport coupled with heat transfer and electrochemical kinetics in a PEMFC with parallel, straight channels, characterized by three different shapes: rectangular, triangular and elliptical. The single-phase model describes the coupled transport of gaseous species in the electrodes of the cell and the transport of water in the membrane. The two-phase model considers liquid water in porous diffusers. The equations governing fluid and transfer phenomena vary between the continuous
medium in the gas channels and the porous medium in the diffusion and catalytic layers. The models are implemented into the commercial computational fluid dynamics (CFD) software package Fluent®6.3, with its user-defined functions (UDFs). The use of the models makes it possible to study the influence of the geometrical parameters and the impact of the cell potentiel and the humidification of the reactants on the performance of the cell. It is shown, on the basis of the monophasic model, that the geometry of the gas channels and the dimensions of the channel have a great influence on mass and heat transfer phenomena. The best performance is obtained for a triangular channel with 0.1 mm width. The performance of the cell can be greatly improved at low voltage and high relative humidity. The two-phase model indicates good hydration of the membrane at high current density. The liquid water saturation in the porous layer is the highest in the rectangular channel which generates a low current density. The simulations reveal that oxygen consumption at the catalytic surface is much lower in the two-phase model due to the accumulation of liquid water that blocks O2 access to the catalytic layer active sites. The consideration of the liquid water generates a lower limit current than in the monophasic case. In view of the results obtained, taking into account liquid water in the modelling of a PEMFC is essential. The geometrical and operating parameters in the different parts of an elementary cell affect greatly the performance of the fuel cell.Diplôme : Doctorat en sciences En ligne : ../theses/chimie/HAD7522.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11362 Modélisation numérique tridimensionnelle des processus physico-chimiques dans une pile à combustible à membrane échangeuse de protons. [texte imprimé] / Razika Hadjadj ép. Assabaa, Auteur ; Wahiba Kaabar, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2019 . - 176 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
ChimieTags : Chimie: Chimie analytique et physique PEMFC CFD écoulement de fluide transfert de masse transfert de chaleur forme
des canaux humidité relative mass transfer heat transfer channels shape relative humidity خلیة وقود ذات غشاء نفوذ للبروتونات أشكال قنوات الغاز دینامیكیة الموائع الحسابیة نقل الكتلة نقل
الحرارة الرطوبة النسبیةIndex. décimale : 540 Chimie et sciences connexes Résumé :
In the current situation of global warming and depletion of oil reserves, the use of proton exchange membrane fuel cells (PEMFC) needs further improvements. In this work, two numerical 3D models have been developed; single-phasic and two-phase water transport coupled with heat transfer and electrochemical kinetics in a PEMFC with parallel, straight channels, characterized by three different shapes: rectangular, triangular and elliptical. The single-phase model describes the coupled transport of gaseous species in the electrodes of the cell and the transport of water in the membrane. The two-phase model considers liquid water in porous diffusers. The equations governing fluid and transfer phenomena vary between the continuous
medium in the gas channels and the porous medium in the diffusion and catalytic layers. The models are implemented into the commercial computational fluid dynamics (CFD) software package Fluent®6.3, with its user-defined functions (UDFs). The use of the models makes it possible to study the influence of the geometrical parameters and the impact of the cell potentiel and the humidification of the reactants on the performance of the cell. It is shown, on the basis of the monophasic model, that the geometry of the gas channels and the dimensions of the channel have a great influence on mass and heat transfer phenomena. The best performance is obtained for a triangular channel with 0.1 mm width. The performance of the cell can be greatly improved at low voltage and high relative humidity. The two-phase model indicates good hydration of the membrane at high current density. The liquid water saturation in the porous layer is the highest in the rectangular channel which generates a low current density. The simulations reveal that oxygen consumption at the catalytic surface is much lower in the two-phase model due to the accumulation of liquid water that blocks O2 access to the catalytic layer active sites. The consideration of the liquid water generates a lower limit current than in the monophasic case. In view of the results obtained, taking into account liquid water in the modelling of a PEMFC is essential. The geometrical and operating parameters in the different parts of an elementary cell affect greatly the performance of the fuel cell.Diplôme : Doctorat en sciences En ligne : ../theses/chimie/HAD7522.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=11362 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité HAD/7522 HAD/7522 Thèse Bibliothèque principale Thèses Disponible
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
PhysiqueTags : 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 : Permalink : 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
PhysiqueTags : 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 : Permalink : 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
Titre : Performances des systèmes frigorifiques trans-critiques utilisant le CO2 comme fluide frigorigène Type de document : texte imprimé Auteurs : Nabil Khellaf, Auteur ; Rabah Gomri, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 161 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Catégories : Français - Anglais
Génie ClimatiqueTags : Réfrigération Cycles Trans-critiques Dioxyde de Carbone Transfert de Chaleur Évaporation Simulation Optimisation Performance Refrigeration transcritical cycles Carbon Dioxide Heat Transfer Evaporation Optimization التبريد دورات عبر حرجة ثاني أكسيد الكربون انتقال الحرارة التبخر محاكاة التحسين الأداء Index. décimale : 626 Génie Climatique Résumé : The negative impact of synthetic fluids on the environment has led researchers to
natural refrigerants, although these fluids are not harmful on the environment, some of them are dangerous because of their flammability and toxicity. Therefore, carbon dioxide goes into very good position among the other natural fluids. The thermodynamic properties of CO2 require a trans-critical cycle. Unfortunately, this cycle has low performance compared to conventional cycles. The main objective of this work is to improve the performance of the refrigeration systems using CO2 as refrigerant and study the heat transfer of carbon dioxide in evaporation.
Based on the first law of thermodynamics and the optimization analysis several trans-critical cycles were studied, in addition, new proposed cycles have been proposed and studied.
As regards the study of heat transfer during evaporation of CO2, literature review has shown that there are several correlations used to predict the coefficient of heat transfer. In order to evaluate these correlations and select the best correlation allowing the optimal design of evaporator, which ensures the required cooling capacity, an experimental database was extracted from different papers available in the literature and compared with these correlations.
Diplôme : Doctorat En ligne : ../theses/gclim/KHE6996.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10398 Performances des systèmes frigorifiques trans-critiques utilisant le CO2 comme fluide frigorigène [texte imprimé] / Nabil Khellaf, Auteur ; Rabah Gomri, Directeur de thèse . - جامعة الإخوة منتوري قسنطينة, 2017 . - 161 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Catégories : Français - Anglais
Génie ClimatiqueTags : Réfrigération Cycles Trans-critiques Dioxyde de Carbone Transfert de Chaleur Évaporation Simulation Optimisation Performance Refrigeration transcritical cycles Carbon Dioxide Heat Transfer Evaporation Optimization التبريد دورات عبر حرجة ثاني أكسيد الكربون انتقال الحرارة التبخر محاكاة التحسين الأداء Index. décimale : 626 Génie Climatique Résumé : The negative impact of synthetic fluids on the environment has led researchers to
natural refrigerants, although these fluids are not harmful on the environment, some of them are dangerous because of their flammability and toxicity. Therefore, carbon dioxide goes into very good position among the other natural fluids. The thermodynamic properties of CO2 require a trans-critical cycle. Unfortunately, this cycle has low performance compared to conventional cycles. The main objective of this work is to improve the performance of the refrigeration systems using CO2 as refrigerant and study the heat transfer of carbon dioxide in evaporation.
Based on the first law of thermodynamics and the optimization analysis several trans-critical cycles were studied, in addition, new proposed cycles have been proposed and studied.
As regards the study of heat transfer during evaporation of CO2, literature review has shown that there are several correlations used to predict the coefficient of heat transfer. In order to evaluate these correlations and select the best correlation allowing the optimal design of evaporator, which ensures the required cooling capacity, an experimental database was extracted from different papers available in the literature and compared with these correlations.
Diplôme : Doctorat En ligne : ../theses/gclim/KHE6996.pdf Format de la ressource électronique : Permalink : index.php?lvl=notice_display&id=10398 Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité KHE/6996 KHE/6996 Thèse Bibliothèque principale Thèses Disponible
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