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Analysis of entropy generation due to natural convection in tilted square cavities / Abhishek Kumar Singh in Industrial & engineering chemistry research, Vol. 51 N° 40 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13300-13318 Titre : Analysis of entropy generation due to natural convection in tilted square cavities Type de document : texte imprimé Auteurs : Abhishek Kumar Singh, Auteur ; S. Roy, Auteur ; Tanmay Basak, Auteur Année de publication : 2012 Article en page(s) : pp. 13300-13318 Note générale : Industrial chemsitry Langues : Anglais (eng) Mots-clés : Thermodynamic  properties  Natural  convection  Entropy Résumé : In this article, the numerical investigation of entropy generation due to heat transfer irreversibility and fluid friction irreversibility during natural convection within tilted square cavity with hot wall AB, cold side walls (DA and BC), and top insulated wall (CD) has been performed. The numerical simulation has been carried out for various fluids of industrial importance (Pr = 0.015, 0.7, and 1000), Rayleigh numbers (103 ≤ Ra ≤ 105), and different inclination angles (ϕ =15°, 45°, and 75°). The results are presented in terms of isotherms (8), streamlines (ψ), entropy generation maps due to heat transfer (Sθ), and fluid friction (Sψ). The total entropy generation (Stotal), average Bejan number (Beav), and average heat transfer rate (NuAB) are plotted for Rayleigh number 103 ≤ Ra ≤ 105. The maximum values of Sθ occur near the comer regions of wall AB due to a junction of hot and cold walls. On the other hand, maximum values of Sψ are found near the walls of the cavity due to friction between the circulation cells and walls of the cavity. It is found that minimum entropy generation occurs for ϕ ≥ 45° at convection dominant mode (Ra = 105) for lower Pr (Pr = 0.015 and 0.7). The inclined cavity with ϕ = 45° may be an alternative optimal inclination angle in optimal thermal processing of high Pr (Pr = 1000). ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26451480 [article] Analysis of entropy generation due to natural convection in tilted square cavities [texte imprimé] / Abhishek Kumar Singh, Auteur ; S. Roy, Auteur ; Tanmay Basak, Auteur . - 2012 . - pp. 13300-13318. Industrial chemsitry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13300-13318 Mots-clés : Thermodynamic  properties  Natural  convection  Entropy Résumé : In this article, the numerical investigation of entropy generation due to heat transfer irreversibility and fluid friction irreversibility during natural convection within tilted square cavity with hot wall AB, cold side walls (DA and BC), and top insulated wall (CD) has been performed. The numerical simulation has been carried out for various fluids of industrial importance (Pr = 0.015, 0.7, and 1000), Rayleigh numbers (103 ≤ Ra ≤ 105), and different inclination angles (ϕ =15°, 45°, and 75°). The results are presented in terms of isotherms (8), streamlines (ψ), entropy generation maps due to heat transfer (Sθ), and fluid friction (Sψ). The total entropy generation (Stotal), average Bejan number (Beav), and average heat transfer rate (NuAB) are plotted for Rayleigh number 103 ≤ Ra ≤ 105. The maximum values of Sθ occur near the comer regions of wall AB due to a junction of hot and cold walls. On the other hand, maximum values of Sψ are found near the walls of the cavity due to friction between the circulation cells and walls of the cavity. It is found that minimum entropy generation occurs for ϕ ≥ 45° at convection dominant mode (Ra = 105) for lower Pr (Pr = 0.015 and 0.7). The inclined cavity with ϕ = 45° may be an alternative optimal inclination angle in optimal thermal processing of high Pr (Pr = 1000). ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26451480

Analysis of steady convective heating for molten materials processing within trapezoidal enclosures / Tanmay Basak ; S. Roy ; E. Natarajan in Industrial & engineering chemistry research, Vol. 47 n°22 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8652–8666 Titre : Analysis of steady convective heating for molten materials processing within trapezoidal enclosures Type de document : texte imprimé Auteurs : Tanmay Basak, Auteur ; S. Roy, Auteur ; E. Natarajan, Auteur Année de publication : 2008 Article en page(s) : p. 8652–8666 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Convective  Heating Résumé : Material processing involving natural convection within a trapezoidal enclosure for uniformly and nonuniformly heated bottom wall, insulated top wall, and isothermal sidewalls with inclination angle φ have been investigated. The penalty finite element method is used to obtain isotherm and streamline profiles for model liquids e.g. molten metal, salt water and olive oil. Parametric study for the wide range of Rayleigh number (Ra), 103 ≤ Ra ≤ 105 and Prandtl number (Pr) for model fluids with various tilt angles φ = 45°, 30°, and 0° have been obtained. Secondary circulations were observed during molten metal processing. Streamlines show that the strength of convection is larger for φ = 45° and flow intensities are also found to be larger for olive oil compared to molten metal and salt water. Heat transfer rates are shown via local and average Nusselt number plots. Local heat transfer rates are found to be relatively more for φ = 0° than those with φ = 45° and φ = 30°. Average Nusselt number plots show higher heat transfer rates for φ = 0° except for the nonuniform heating of the bottom wall with Pr = 0.015 (molten metal). Overall, less heat transfer rates are observed for molten metal processing. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800263c [article] Analysis of steady convective heating for molten materials processing within trapezoidal enclosures [texte imprimé] / Tanmay Basak, Auteur ; S. Roy, Auteur ; E. Natarajan, Auteur . - 2008 . - p. 8652–8666. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8652–8666 Mots-clés : Convective  Heating Résumé : Material processing involving natural convection within a trapezoidal enclosure for uniformly and nonuniformly heated bottom wall, insulated top wall, and isothermal sidewalls with inclination angle φ have been investigated. The penalty finite element method is used to obtain isotherm and streamline profiles for model liquids e.g. molten metal, salt water and olive oil. Parametric study for the wide range of Rayleigh number (Ra), 103 ≤ Ra ≤ 105 and Prandtl number (Pr) for model fluids with various tilt angles φ = 45°, 30°, and 0° have been obtained. Secondary circulations were observed during molten metal processing. Streamlines show that the strength of convection is larger for φ = 45° and flow intensities are also found to be larger for olive oil compared to molten metal and salt water. Heat transfer rates are shown via local and average Nusselt number plots. Local heat transfer rates are found to be relatively more for φ = 0° than those with φ = 45° and φ = 30°. Average Nusselt number plots show higher heat transfer rates for φ = 0° except for the nonuniform heating of the bottom wall with Pr = 0.015 (molten metal). Overall, less heat transfer rates are observed for molten metal processing. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800263c

A Complete heatline analysis on visualization of heat flow and thermal mixing during mixed convection in a square cavity with various wall heating / Tanmay Basak in Industrial & engineering chemistry research, Vol. 50 N° 12 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7608-7630 Titre : A Complete heatline analysis on visualization of heat flow and thermal mixing during mixed convection in a square cavity with various wall heating Type de document : texte imprimé Auteurs : Tanmay Basak, Auteur ; P. V. Krishna Pradeep, Auteur ; S. Roy, Auteur Année de publication : 2011 Article en page(s) : pp. 7608-7630 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Heat  transfer  Heating  Convection  Mixing  Heat  flow Résumé : A wide range of applications involving mixed-convection studies can be found in various engineering processes such as thermal discharge of water bodies, float glass production, heat exchangers, nuclear reactors, and crystallization process. The present study focuses on understanding the thermal mixing scenarios for mixed-convection lid-driven flow in a square cavity using heatlines. Thermal mixing is analyzed for four different thermal boundary conditions, and heat flow patterns in mixed convection are analyzed using Bejan's heatlines concept for wide ranges of parameters (Pr = 0.015―7.2, Re = 1―100, and Gr = 103―105, where Pr, Re, and Gr denote the Prandtl, Reynolds, and Grashof numbers, respectively). The results indicate that, at low Prvalues (Pr = 0.015), the transport is conduction-dominant irrespective of the values of Gr and Re. The trends of heatlines and streamlines are identical near the core for high-Re cases. A single circulation cell was observed in the streamlines for any Pr ≥ 0.7 at high Re and low Gr values for uniform heating of the bottom surface with cold side walls. It was observed that thermal mixing increased significantly with subsequent rises in Gr for high-Pr fluids. Patterns of heatlines and multiple circulation cells of heatlines were found to lead to enhanced thermal mixing, with the thermal boundary layer much compressed toward the walls for linearly heated side walls. The heat-transfer rates along the walls are illustrated by the local Nusselt number distribution based on gradients of heatfunctions for the first time in this work. Nusselt numbers with infinitely large magnitudes were observed at hot―old junctions, illustrating high heat-transfer rates. An oscillatory distribution in the local heatfunction rate was observed as a result of sinusoidal heating of the bottom surface for high-Pr fluids. Negative heat-transfer rates or local Nusselt numbers were observed along the side walls when side wall(s) was/were linearly heated, as explained based on negative heatfunction gradients. Also, the effect of Gr on the local and average Nusselt numbers in different cases can be adequately explained based on heatlines. Dense heatlines signifying higher overall heat-transfer rates along the bottom surface and side walls were observed for uniform bottom surface heating, whereas lower heat-transfer rates were observed for sinusoidal heating. Nonmonotonic distributions in overall heat-transfer rates along the bottom surface and left wall were observed when both walls were linearly heated, whereas a smooth and exponential increase was observed when the right wall was isothermally cooled. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239078 [article] A Complete heatline analysis on visualization of heat flow and thermal mixing during mixed convection in a square cavity with various wall heating [texte imprimé] / Tanmay Basak, Auteur ; P. V. Krishna Pradeep, Auteur ; S. Roy, Auteur . - 2011 . - pp. 7608-7630. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7608-7630 Mots-clés : Heat  transfer  Heating  Convection  Mixing  Heat  flow Résumé : A wide range of applications involving mixed-convection studies can be found in various engineering processes such as thermal discharge of water bodies, float glass production, heat exchangers, nuclear reactors, and crystallization process. The present study focuses on understanding the thermal mixing scenarios for mixed-convection lid-driven flow in a square cavity using heatlines. Thermal mixing is analyzed for four different thermal boundary conditions, and heat flow patterns in mixed convection are analyzed using Bejan's heatlines concept for wide ranges of parameters (Pr = 0.015―7.2, Re = 1―100, and Gr = 103―105, where Pr, Re, and Gr denote the Prandtl, Reynolds, and Grashof numbers, respectively). The results indicate that, at low Prvalues (Pr = 0.015), the transport is conduction-dominant irrespective of the values of Gr and Re. The trends of heatlines and streamlines are identical near the core for high-Re cases. A single circulation cell was observed in the streamlines for any Pr ≥ 0.7 at high Re and low Gr values for uniform heating of the bottom surface with cold side walls. It was observed that thermal mixing increased significantly with subsequent rises in Gr for high-Pr fluids. Patterns of heatlines and multiple circulation cells of heatlines were found to lead to enhanced thermal mixing, with the thermal boundary layer much compressed toward the walls for linearly heated side walls. The heat-transfer rates along the walls are illustrated by the local Nusselt number distribution based on gradients of heatfunctions for the first time in this work. Nusselt numbers with infinitely large magnitudes were observed at hot―old junctions, illustrating high heat-transfer rates. An oscillatory distribution in the local heatfunction rate was observed as a result of sinusoidal heating of the bottom surface for high-Pr fluids. Negative heat-transfer rates or local Nusselt numbers were observed along the side walls when side wall(s) was/were linearly heated, as explained based on negative heatfunction gradients. Also, the effect of Gr on the local and average Nusselt numbers in different cases can be adequately explained based on heatlines. Dense heatlines signifying higher overall heat-transfer rates along the bottom surface and side walls were observed for uniform bottom surface heating, whereas lower heat-transfer rates were observed for sinusoidal heating. Nonmonotonic distributions in overall heat-transfer rates along the bottom surface and left wall were observed when both walls were linearly heated, whereas a smooth and exponential increase was observed when the right wall was isothermally cooled. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239078