Dépouillements

Enhanced convective heat transfer in nongas generating nanoparticle thermites / S. W. Dean in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp.[111201-1/7] Titre : Enhanced convective heat transfer in nongas generating nanoparticle thermites Type de document : texte imprimé Auteurs : S. W. Dean, Auteur ; M. L. Pantoya, Auteur ; A. E. Gash, Auteur Année de publication : 2010 Article en page(s) : pp.[111201-1/7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nanocomposites  Enhanced  convection  reaction  mechanisms  Nano-alumium  Thermites  CuO  NiO  Peak  pressures  Flame  speeds  Flame  speeds  DSC  TGA  XRD  Gas  generation  Flame  propagation Index. décimale : 536 Chaleur. Thermodynamique Résumé : Flame propagation and peak pressure measurements were taken of two nanoscaled thermites using aluminum (Al) fuel and copper oxide (CuO) or nickel oxide (NiO) oxidizers in a confined flame tube apparatus. Thermal equilibrium simulations predict that the Al+CuO reaction exhibits high gas generation and, thus, high convective flame propagation rates while the Al+NiO reaction produces little to no gas and, therefore, should exhibit much lower flame propagation rates. Results show flame propagation rates ranged between 200 m/s and 600 m/s and peak pressures ranged between 1.7 MPa and 3.7 MPa for both composites. These results were significantly higher than expected for the Al+NiO, which generates virtually no gas. For nanometric Al particles, oxidation has recently been described by a melt-dispersion oxidation mechanism that involves a dispersion of high velocity alumina shell fragments and molten Al droplets that promote a pressure build-up by inducing a bulk movement of fluid. This mechanism unique to nanoparticle reaction may promote convection without the need for additional gas generation. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Enhanced convective heat transfer in nongas generating nanoparticle thermites [texte imprimé] / S. W. Dean, Auteur ; M. L. Pantoya, Auteur ; A. E. Gash, Auteur . - 2010 . - pp.[111201-1/7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp.[111201-1/7] Mots-clés : Nanocomposites  Enhanced  convection  reaction  mechanisms  Nano-alumium  Thermites  CuO  NiO  Peak  pressures  Flame  speeds  Flame  speeds  DSC  TGA  XRD  Gas  generation  Flame  propagation Index. décimale : 536 Chaleur. Thermodynamique Résumé : Flame propagation and peak pressure measurements were taken of two nanoscaled thermites using aluminum (Al) fuel and copper oxide (CuO) or nickel oxide (NiO) oxidizers in a confined flame tube apparatus. Thermal equilibrium simulations predict that the Al+CuO reaction exhibits high gas generation and, thus, high convective flame propagation rates while the Al+NiO reaction produces little to no gas and, therefore, should exhibit much lower flame propagation rates. Results show flame propagation rates ranged between 200 m/s and 600 m/s and peak pressures ranged between 1.7 MPa and 3.7 MPa for both composites. These results were significantly higher than expected for the Al+NiO, which generates virtually no gas. For nanometric Al particles, oxidation has recently been described by a melt-dispersion oxidation mechanism that involves a dispersion of high velocity alumina shell fragments and molten Al droplets that promote a pressure build-up by inducing a bulk movement of fluid. This mechanism unique to nanoparticle reaction may promote convection without the need for additional gas generation. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Numerical simulations of the dynamics and heat transfer associated with a single bubble in subcooled pool boiling / Jinfeng Wu in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111501-1/15] Titre : Numerical simulations of the dynamics and heat transfer associated with a single bubble in subcooled pool boiling Type de document : texte imprimé Auteurs : Jinfeng Wu, Auteur ; Vijay K. Dhir, Auteur Année de publication : 2010 Article en page(s) : pp. [111501-1/15] Note générale : Physique Langues : Anglais (eng) Mots-clés : Subcooled  nucleate  boiling  Level-set  method  Moving  mesh  method  Numerical  simulation  Condensation Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this study, numerical simulations of a vapor bubble in subcooled pool boiling have been performed. The applied numerical procedure coupling level-set function with moving mesh method has been validated by comparing the results of bubble-growth history including bubble departure diameter with data from experiments. The predictions of bubble dynamics and heat transfer for various subcoolings as well as different gravity levels are presented. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Numerical simulations of the dynamics and heat transfer associated with a single bubble in subcooled pool boiling [texte imprimé] / Jinfeng Wu, Auteur ; Vijay K. Dhir, Auteur . - 2010 . - pp. [111501-1/15]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111501-1/15] Mots-clés : Subcooled  nucleate  boiling  Level-set  method  Moving  mesh  method  Numerical  simulation  Condensation Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this study, numerical simulations of a vapor bubble in subcooled pool boiling have been performed. The applied numerical procedure coupling level-set function with moving mesh method has been validated by comparing the results of bubble-growth history including bubble departure diameter with data from experiments. The predictions of bubble dynamics and heat transfer for various subcoolings as well as different gravity levels are presented. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Nucleate pool boiling heat transfer of R134a and R134a-PVE lubricant mixtures on smooth and five enhanced tubes / Wen-Tao Ji in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111502-1/8] Titre : Nucleate pool boiling heat transfer of R134a and R134a-PVE lubricant mixtures on smooth and five enhanced tubes Type de document : texte imprimé Auteurs : Wen-Tao Ji, Auteur ; Ding-Cai Zhang, Auteur ; Nan Feng, Auteur Année de publication : 2010 Article en page(s) : pp. [111502-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nucleate  pool  boiling  Enhancement  heat  transfer  Lubricant Index. décimale : 536 Chaleur. Thermodynamique Résumé : Pool boiling heat transfer coefficients of R134a with different lubricant mass fractions for one smooth tube and five enhanced tubes were tested at a saturation temperature of 6°C. The lubricant used was polyvinyl ether. The lubrication mass fractions were 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively. Within the tested heat flux range, from 9000 W/m2 to 90,000 W/m2, the lubricant generally has a different influence on pool boiling heat transfer of these six tubes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Nucleate pool boiling heat transfer of R134a and R134a-PVE lubricant mixtures on smooth and five enhanced tubes [texte imprimé] / Wen-Tao Ji, Auteur ; Ding-Cai Zhang, Auteur ; Nan Feng, Auteur . - 2010 . - pp. [111502-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111502-1/8] Mots-clés : Nucleate  pool  boiling  Enhancement  heat  transfer  Lubricant Index. décimale : 536 Chaleur. Thermodynamique Résumé : Pool boiling heat transfer coefficients of R134a with different lubricant mass fractions for one smooth tube and five enhanced tubes were tested at a saturation temperature of 6°C. The lubricant used was polyvinyl ether. The lubrication mass fractions were 0.25%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 7.0%, and 10.0%, respectively. Within the tested heat flux range, from 9000 W/m2 to 90,000 W/m2, the lubricant generally has a different influence on pool boiling heat transfer of these six tubes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Poiseuille flow of reactive phan–thien–tanner liquids in 1D channel flow / T. Chinyoka in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111701-1/7] Titre : Poiseuille flow of reactive phan–thien–tanner liquids in 1D channel flow Type de document : texte imprimé Auteurs : T. Chinyoka, Auteur Année de publication : 2010 Article en page(s) : pp. [111701-1/7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Channel  flow  Finite  difference  methods  Flow  simulation  Non-Newtonian  flow  Non-Newtonian  fluids  Poiseuille  flow Index. décimale : 536 Chaleur. Thermodynamique Résumé : We investigate, using direct numerical simulations, the effects of viscoelasticity on pressure driven flows of thermally decomposable liquids in channels. A numerical algorithm based on the finite difference method is implemented in time and space with the Phan–Thien–Tanner as the model for the viscoelastic liquids. The strong dependence of fluid temperature on the Frank–Kamenetskii parameter is shown for various fluid types and the phenomenon of thermal runaway is demonstrated. It is shown that viscoelastic fluids have in general delayed susceptibility to thermal runaway as compared with corresponding inelastic fluids. This paper demonstrates the efficiency of using semi-implicit finite difference schemes in solving transient problems of coupled nonlinear systems. It also provides an understanding of nonisothermal flows of viscoelastic fluids. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Poiseuille flow of reactive phan–thien–tanner liquids in 1D channel flow [texte imprimé] / T. Chinyoka, Auteur . - 2010 . - pp. [111701-1/7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111701-1/7] Mots-clés : Channel  flow  Finite  difference  methods  Flow  simulation  Non-Newtonian  flow  Non-Newtonian  fluids  Poiseuille  flow Index. décimale : 536 Chaleur. Thermodynamique Résumé : We investigate, using direct numerical simulations, the effects of viscoelasticity on pressure driven flows of thermally decomposable liquids in channels. A numerical algorithm based on the finite difference method is implemented in time and space with the Phan–Thien–Tanner as the model for the viscoelastic liquids. The strong dependence of fluid temperature on the Frank–Kamenetskii parameter is shown for various fluid types and the phenomenon of thermal runaway is demonstrated. It is shown that viscoelastic fluids have in general delayed susceptibility to thermal runaway as compared with corresponding inelastic fluids. This paper demonstrates the efficiency of using semi-implicit finite difference schemes in solving transient problems of coupled nonlinear systems. It also provides an understanding of nonisothermal flows of viscoelastic fluids. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Simple models for laminar thermally developing slug flow in noncircular ducts and channels / Y. S. Muzychka in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111702-1/10] Titre : Simple models for laminar thermally developing slug flow in noncircular ducts and channels Type de document : texte imprimé Auteurs : Y. S. Muzychka, Auteur ; Edmond Walsh, Auteur ; Pat Walsh, Auteur Année de publication : 2010 Article en page(s) : pp. [111702-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Graetz  flow  Pulg  flow  Slug  flow  Heat  transfer  coefficient  Laminar  flow  Heat  exchangers  Heat  sinks  Porous  media  Modeling Index. décimale : 536 Chaleur. Thermodynamique Résumé : Solutions to the classical Graetz slug flow problem (uniform velocity distribution) in noncircular ducts are examined. These solutions have applications where a constant uniform velocity distribution exists across a channel or duct. These are most often realized in the laminar flow of low Prandtl number liquids, such as liquid metals, and low Reynolds number flows through porous media. Expressions are developed for a number of applications using the asymptotic correlation method of Churchill and Usagi. These expressions vary depending on the definition used for the dimensionless heat transfer coefficient, in the case of constant wall temperature boundary condition (T), and the dimensionless wall temperature for the constant flux boundary conditions (H) and (H1). Finally, simple expressions are developed for predicting the thermal entrance length and fully developed flow Nu values for noncircular ducts. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Simple models for laminar thermally developing slug flow in noncircular ducts and channels [texte imprimé] / Y. S. Muzychka, Auteur ; Edmond Walsh, Auteur ; Pat Walsh, Auteur . - 2010 . - pp. [111702-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111702-1/10] Mots-clés : Graetz  flow  Pulg  flow  Slug  flow  Heat  transfer  coefficient  Laminar  flow  Heat  exchangers  Heat  sinks  Porous  media  Modeling Index. décimale : 536 Chaleur. Thermodynamique Résumé : Solutions to the classical Graetz slug flow problem (uniform velocity distribution) in noncircular ducts are examined. These solutions have applications where a constant uniform velocity distribution exists across a channel or duct. These are most often realized in the laminar flow of low Prandtl number liquids, such as liquid metals, and low Reynolds number flows through porous media. Expressions are developed for a number of applications using the asymptotic correlation method of Churchill and Usagi. These expressions vary depending on the definition used for the dimensionless heat transfer coefficient, in the case of constant wall temperature boundary condition (T), and the dimensionless wall temperature for the constant flux boundary conditions (H) and (H1). Finally, simple expressions are developed for predicting the thermal entrance length and fully developed flow Nu values for noncircular ducts. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Combined effects of temperature and velocity jump on the heat transfer, fluid flow, and entropy rotating disk / A. Arikoglu in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111703-1/10] Titre : Combined effects of temperature and velocity jump on the heat transfer, fluid flow, and entropy rotating disk Type de document : texte imprimé Auteurs : A. Arikoglu, Auteur ; G. Komurgoz, Auteur ; I. Ozkol, Auteur Année de publication : 2010 Article en page(s) : pp. [111703-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Rotating  disk  flow  Temperature  jump  Velocity  slip  Entropy  generation Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present work examines the effects of temperature and velocity jump conditions on heat transfer, fluid flow, and entropy generation. As the physical model, the axially symmetrical steady flow of a Newtonian ambient fluid over a single rotating disk is chosen. The related nonlinear governing equations for flow and thermal fields are reduced to ordinary differential equations by applying so-called classical approach, which was first introduced by von Karman. Instead of a numerical method, a recently developed popular semi numerical-analytical technique; differential transform method is employed to solve the reduced governing equations under the assumptions of velocity and thermal jump conditions on the disk surface. The combined effects of the velocity slip and temperature jump on the thermal and flow fields are investigated in great detail for different values of the nondimensional field parameters. In order to evaluate the efficiency of such rotating fluidic system, the entropy generation equation is derived and nondimensionalized. Additionally, special attention has been given to entropy generation, its characteristic and dependency on various parameters, i.e., group parameter, Kn and Re numbers, etc. It is observed that thermal and velocity jump strongly reduce the magnitude of entropy generation throughout the flow domain. As a result, the efficiency of the related physical system increases. A noticeable objective of this study is to give an open form solution of nonlinear field equations. The reduced recurative form of the governing equations presented gives the reader an opportunity to see the solution in open series form. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Combined effects of temperature and velocity jump on the heat transfer, fluid flow, and entropy rotating disk [texte imprimé] / A. Arikoglu, Auteur ; G. Komurgoz, Auteur ; I. Ozkol, Auteur . - 2010 . - pp. [111703-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111703-1/10] Mots-clés : Rotating  disk  flow  Temperature  jump  Velocity  slip  Entropy  generation Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present work examines the effects of temperature and velocity jump conditions on heat transfer, fluid flow, and entropy generation. As the physical model, the axially symmetrical steady flow of a Newtonian ambient fluid over a single rotating disk is chosen. The related nonlinear governing equations for flow and thermal fields are reduced to ordinary differential equations by applying so-called classical approach, which was first introduced by von Karman. Instead of a numerical method, a recently developed popular semi numerical-analytical technique; differential transform method is employed to solve the reduced governing equations under the assumptions of velocity and thermal jump conditions on the disk surface. The combined effects of the velocity slip and temperature jump on the thermal and flow fields are investigated in great detail for different values of the nondimensional field parameters. In order to evaluate the efficiency of such rotating fluidic system, the entropy generation equation is derived and nondimensionalized. Additionally, special attention has been given to entropy generation, its characteristic and dependency on various parameters, i.e., group parameter, Kn and Re numbers, etc. It is observed that thermal and velocity jump strongly reduce the magnitude of entropy generation throughout the flow domain. As a result, the efficiency of the related physical system increases. A noticeable objective of this study is to give an open form solution of nonlinear field equations. The reduced recurative form of the governing equations presented gives the reader an opportunity to see the solution in open series form. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

AneExperimental study on heat transfer around two side-by-side closely arranged circular cylinders / Takayuki Tsutsui in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111704-1/8] Titre : AneExperimental study on heat transfer around two side-by-side closely arranged circular cylinders Type de document : texte imprimé Auteurs : Takayuki Tsutsui, Auteur Année de publication : 2010 Article en page(s) : pp. [111704-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Two  circular  cylinders  Side-by-side  arrangement  Heat  transfer  Flow  visualization Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present paper describes heat transfer around two side-by-side closely arranged circular cylinders. The flows around two circular cylinders in a side-by-side arrangement can be classified into three flow patterns according to the gap between the two cylinders. The heat transfer characteristics of the cylinders in each flow regime were experimentally investigated. The diameter of the circular cylinders was 40 mm and the gap between the two cylinders varied from 4 mm to 40 mm. The free stream velocity ranged from 4 m/s to 24 m/s, resulting in Reynolds nos. ranging from 1.1×104 to 6.2×104. The local heat transfer coefficient of both cylinders was measured. The overall Nusselt no. of the two cylinders was found to be minimum at G/D(=gap/diameter)=0.4, which is the minimum drag coefficient condition of the two cylinders, too. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] AneExperimental study on heat transfer around two side-by-side closely arranged circular cylinders [texte imprimé] / Takayuki Tsutsui, Auteur . - 2010 . - pp. [111704-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111704-1/8] Mots-clés : Two  circular  cylinders  Side-by-side  arrangement  Heat  transfer  Flow  visualization Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present paper describes heat transfer around two side-by-side closely arranged circular cylinders. The flows around two circular cylinders in a side-by-side arrangement can be classified into three flow patterns according to the gap between the two cylinders. The heat transfer characteristics of the cylinders in each flow regime were experimentally investigated. The diameter of the circular cylinders was 40 mm and the gap between the two cylinders varied from 4 mm to 40 mm. The free stream velocity ranged from 4 m/s to 24 m/s, resulting in Reynolds nos. ranging from 1.1×104 to 6.2×104. The local heat transfer coefficient of both cylinders was measured. The overall Nusselt no. of the two cylinders was found to be minimum at G/D(=gap/diameter)=0.4, which is the minimum drag coefficient condition of the two cylinders, too. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

An experimentally validated numerical modeling technique for perforated plate heat exchangers / M. J. White in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111801-1/9] Titre : An experimentally validated numerical modeling technique for perforated plate heat exchangers Type de document : texte imprimé Auteurs : M. J. White, Auteur ; G. F. Nellis, Auteur ; S. A. Klein, Auteur Année de publication : 2010 Article en page(s) : pp. [111801-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Perforated  plate  Heat  exchanger  Axizl  conduction  Cryogenic  MEMS Index. décimale : 536 Chaleur. Thermodynamique Résumé : Cryogenic and high-temperature systems often require compact heat exchangers with a high resistance to axial conduction in order to control the heat transfer induced by axial temperature differences. One attractive design for such applications is a perforated plate heat exchanger that utilizes high conductivity perforated plates to provide the stream-to-stream heat transfer and low conductivity spacers to prevent axial conduction between the perforated plates. This paper presents a numerical model of a perforated plate heat exchanger that accounts for axial conduction, external parasitic heat loads, variable fluid and material properties, and conduction to and from the ends of the heat exchanger. The numerical model is validated by experimentally testing several perforated plate heat exchangers that are fabricated using microelectromechanical systems based manufacturing methods. This type of heat exchanger was investigated for potential use in a cryosurgical probe. One of these heat exchangers included perforated plates with integrated platinum resistance thermometers. These plates provided in situ measurements of the internal temperature distribution in addition to the temperature, pressure, and flow rate measured at the inlet and exit ports of the device. The platinum wires were deposited between the fluid passages on the perforated plate and are used to measure the temperature at the interface between the wall material and the flowing fluid. The experimental testing demonstrates the ability of the numerical model to accurately predict both the overall performance and the internal temperature distribution of perforated plate heat exchangers over a range of geometry and operating conditions. The parameters that were varied include the axial length, temperature range, mass flow rate, and working fluid. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] An experimentally validated numerical modeling technique for perforated plate heat exchangers [texte imprimé] / M. J. White, Auteur ; G. F. Nellis, Auteur ; S. A. Klein, Auteur . - 2010 . - pp. [111801-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111801-1/9] Mots-clés : Perforated  plate  Heat  exchanger  Axizl  conduction  Cryogenic  MEMS Index. décimale : 536 Chaleur. Thermodynamique Résumé : Cryogenic and high-temperature systems often require compact heat exchangers with a high resistance to axial conduction in order to control the heat transfer induced by axial temperature differences. One attractive design for such applications is a perforated plate heat exchanger that utilizes high conductivity perforated plates to provide the stream-to-stream heat transfer and low conductivity spacers to prevent axial conduction between the perforated plates. This paper presents a numerical model of a perforated plate heat exchanger that accounts for axial conduction, external parasitic heat loads, variable fluid and material properties, and conduction to and from the ends of the heat exchanger. The numerical model is validated by experimentally testing several perforated plate heat exchangers that are fabricated using microelectromechanical systems based manufacturing methods. This type of heat exchanger was investigated for potential use in a cryosurgical probe. One of these heat exchangers included perforated plates with integrated platinum resistance thermometers. These plates provided in situ measurements of the internal temperature distribution in addition to the temperature, pressure, and flow rate measured at the inlet and exit ports of the device. The platinum wires were deposited between the fluid passages on the perforated plate and are used to measure the temperature at the interface between the wall material and the flowing fluid. The experimental testing demonstrates the ability of the numerical model to accurately predict both the overall performance and the internal temperature distribution of perforated plate heat exchangers over a range of geometry and operating conditions. The parameters that were varied include the axial length, temperature range, mass flow rate, and working fluid. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Second law analysis of heat exchangers / Ahmad Fakheri in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111802-1/7] Titre : Second law analysis of heat exchangers Type de document : texte imprimé Auteurs : Ahmad Fakheri, Auteur Année de publication : 2010 Article en page(s) : pp. [111802-1/7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  exchangers  Efficiency  Heat  exchanger  efficiency  Entropy  minimization  Exergy  Exergy  maximization Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper further explores the topic of an ideal heat exchanger, which is still an open question. It is shown that the minimization of entropy production or exergy destruction should not be an objective in heat exchanger design. It is further proven that heat exchanger effectiveness does not correlate with irreversibility. A new performance measure, entropy flux, is introduced and a general expression for its evaluation is presented. It is shown that entropy flux captures many desirable attributes of heat exchangers. For a given effectiveness, a single stream heat exchanger has the absolute maximum entropy flux, and for capacity ratios greater than zero, counterflow has the highest entropy flux, parallel flow the lowest, and the shell and tube heat exchangers are somewhere in between. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Second law analysis of heat exchangers [texte imprimé] / Ahmad Fakheri, Auteur . - 2010 . - pp. [111802-1/7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [111802-1/7] Mots-clés : Heat  exchangers  Efficiency  Heat  exchanger  efficiency  Entropy  minimization  Exergy  Exergy  maximization Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper further explores the topic of an ideal heat exchanger, which is still an open question. It is shown that the minimization of entropy production or exergy destruction should not be an objective in heat exchanger design. It is further proven that heat exchanger effectiveness does not correlate with irreversibility. A new performance measure, entropy flux, is introduced and a general expression for its evaluation is presented. It is shown that entropy flux captures many desirable attributes of heat exchangers. For a given effectiveness, a single stream heat exchanger has the absolute maximum entropy flux, and for capacity ratios greater than zero, counterflow has the highest entropy flux, parallel flow the lowest, and the shell and tube heat exchangers are somewhere in between. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

On variance-reduced simulations of the boltzmann transport equation for small-scale heat transfer applications / Nicolas G. Hadjiconstantinou in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112401-1/8] Titre : On variance-reduced simulations of the boltzmann transport equation for small-scale heat transfer applications Type de document : texte imprimé Auteurs : Nicolas G. Hadjiconstantinou, Auteur ; Gregg A. Radtke, Auteur ; Lowell L. Baker, Auteur Année de publication : 2010 Article en page(s) : pp. [112401-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Boltzmann  equation  Flow  simulation  Heat  transfer Index. décimale : 536 Chaleur. Thermodynamique Résumé : We present and discuss a variance-reduced stochastic particle simulation method for solving the relaxation-time model of the Boltzmann transport equation. The variance reduction, achieved by simulating only the deviation from equilibrium, results in a significant computational efficiency advantage compared with traditional stochastic particle methods in the limit of small deviation from equilibrium. More specifically, the proposed method can efficiently simulate arbitrarily small deviations from equilibrium at a computational cost that is independent of the deviation from equilibrium, which is in sharp contrast to traditional particle methods. The proposed method is developed and validated in the context of dilute gases; despite this, it is expected to directly extend to all fields (carriers) for which the relaxation-time approximation is applicable. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] On variance-reduced simulations of the boltzmann transport equation for small-scale heat transfer applications [texte imprimé] / Nicolas G. Hadjiconstantinou, Auteur ; Gregg A. Radtke, Auteur ; Lowell L. Baker, Auteur . - 2010 . - pp. [112401-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112401-1/8] Mots-clés : Boltzmann  equation  Flow  simulation  Heat  transfer Index. décimale : 536 Chaleur. Thermodynamique Résumé : We present and discuss a variance-reduced stochastic particle simulation method for solving the relaxation-time model of the Boltzmann transport equation. The variance reduction, achieved by simulating only the deviation from equilibrium, results in a significant computational efficiency advantage compared with traditional stochastic particle methods in the limit of small deviation from equilibrium. More specifically, the proposed method can efficiently simulate arbitrarily small deviations from equilibrium at a computational cost that is independent of the deviation from equilibrium, which is in sharp contrast to traditional particle methods. The proposed method is developed and validated in the context of dilute gases; despite this, it is expected to directly extend to all fields (carriers) for which the relaxation-time approximation is applicable. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Large convective heat transfer enhancement in microchannels with a train of coflowing immiscible or colloidal droplets / Magnus Fischer in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112402-1/10] Titre : Large convective heat transfer enhancement in microchannels with a train of coflowing immiscible or colloidal droplets Type de document : texte imprimé Auteurs : Magnus Fischer, Auteur ; Damir Juric, Auteur ; Dimos Poulikakos, Auteur Année de publication : 2010 Article en page(s) : pp. [112402-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nanofluid  Colloidal  suspensions  Thermal  transport  Marangoni  effect  Droplet-laden  flow  Segmented  flow  Immiscible  fluids Index. décimale : 536 Chaleur. Thermodynamique Résumé : We show that heat transfer in microchannels can be considerably augmented by introducing droplets or slugs of an immiscible liquid into the main fluid flow. We numerically investigate the influence of differently shaped colloidal or simply pure immiscible droplets to the main liquid flow on the thermal transport in microchannels. Results of parametric studies on the influence of all major factors connected to microchannel heat transfer are presented. The effect of induced Marangoni flow at the liquid interfaces is also taken into account and quantified. The calculation of the multiphase, multispecies flow problem is performed, applying a front tracking method, extended to account for nanoparticle transport in the suspended phase when relevant. This study reveals that the use of a second suspended liquid (with or without nanoparticles) is an efficient way to significantly increase the thermal performance without unacceptably large pressure losses. In the case of slug-train coflow, the Nusselt number can be increased by as much as 400% compared with single liquid flow. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Large convective heat transfer enhancement in microchannels with a train of coflowing immiscible or colloidal droplets [texte imprimé] / Magnus Fischer, Auteur ; Damir Juric, Auteur ; Dimos Poulikakos, Auteur . - 2010 . - pp. [112402-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112402-1/10] Mots-clés : Nanofluid  Colloidal  suspensions  Thermal  transport  Marangoni  effect  Droplet-laden  flow  Segmented  flow  Immiscible  fluids Index. décimale : 536 Chaleur. Thermodynamique Résumé : We show that heat transfer in microchannels can be considerably augmented by introducing droplets or slugs of an immiscible liquid into the main fluid flow. We numerically investigate the influence of differently shaped colloidal or simply pure immiscible droplets to the main liquid flow on the thermal transport in microchannels. Results of parametric studies on the influence of all major factors connected to microchannel heat transfer are presented. The effect of induced Marangoni flow at the liquid interfaces is also taken into account and quantified. The calculation of the multiphase, multispecies flow problem is performed, applying a front tracking method, extended to account for nanoparticle transport in the suspended phase when relevant. This study reveals that the use of a second suspended liquid (with or without nanoparticles) is an efficient way to significantly increase the thermal performance without unacceptably large pressure losses. In the case of slug-train coflow, the Nusselt number can be increased by as much as 400% compared with single liquid flow. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Numerical analysis of interaction between inertial and thermosolutal buoyancy forces on convective heat transfer in a lid-driven cavity / D. Senthil kumar in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112501-1/11] Titre : Numerical analysis of interaction between inertial and thermosolutal buoyancy forces on convective heat transfer in a lid-driven cavity Type de document : texte imprimé Auteurs : D. Senthil kumar, Auteur ; K. Murugesan, Auteur ; Akhilesh Gupta, Auteur Année de publication : 2010 Article en page(s) : pp. [112501-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Thermosolutal  buoyancy  forces  Lid-driven  cavity  Velocity-vorticity  equations  Mixed  convection Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, results on double diffusive mixed convection in a lid-driven cavity are discussed in detail with a focus on the effect of interaction between fluid inertial force and thermosolutal buoyancy forces on convective heat and mass transfer. The governing equations for the mathematical model of the problem consist of vorticity transport equation, velocity Poisson equations, energy equation and solutal concentration equation. Numerical solution for the field variables are obtained by solving the governing equations using Galerkin's weighted residual finite element method. The interaction effects on convective heat and mass transfer are analyzed by simultaneously varying the characteristic parameters, 0.1 DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Numerical analysis of interaction between inertial and thermosolutal buoyancy forces on convective heat transfer in a lid-driven cavity [texte imprimé] / D. Senthil kumar, Auteur ; K. Murugesan, Auteur ; Akhilesh Gupta, Auteur . - 2010 . - pp. [112501-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112501-1/11] Mots-clés : Thermosolutal  buoyancy  forces  Lid-driven  cavity  Velocity-vorticity  equations  Mixed  convection Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, results on double diffusive mixed convection in a lid-driven cavity are discussed in detail with a focus on the effect of interaction between fluid inertial force and thermosolutal buoyancy forces on convective heat and mass transfer. The governing equations for the mathematical model of the problem consist of vorticity transport equation, velocity Poisson equations, energy equation and solutal concentration equation. Numerical solution for the field variables are obtained by solving the governing equations using Galerkin's weighted residual finite element method. The interaction effects on convective heat and mass transfer are analyzed by simultaneously varying the characteristic parameters, 0.1 DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Scale-up and generalization of horizontal-base pin-fin heat sinks in natural convection and radiation / D. Sahray in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112502-1/10] Titre : Scale-up and generalization of horizontal-base pin-fin heat sinks in natural convection and radiation Type de document : texte imprimé Auteurs : D. Sahray, Auteur ; G. Ziskind, Auteur ; R. Letan, Auteur Année de publication : 2010 Article en page(s) : pp. [112502-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Pin  fin  Natural  convection  Scale-up  Correlation Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper provides further insight in heat transfer from horizontal-base pin fin heat-sinks in free convection of air. The main objective is to assess the effect of base size, and this with regard to the effects of fin height and fin population density studied in a previous work (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13). To this end, experimental and numerical investigations are performed with sinks of different base sizes. The sinks are made of aluminum, with no contact resistance between the base and the fins, and are heated using foil electrical heaters. In the corresponding numerical study, the sinks and their environment are modeled using the FLUENT 6.3 software. In the experiments, sink bases of 100×100 mm2 and 200×200 mm2 are used, while in the numerical study sinks of 50×50 mm2 are investigated, too. In addition to the sinks with exposed, free edges (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13), the same sinks are explored also with their edges blocked. This is done in order to exclude the edge effect, thus making it possible to estimate heat transfer from a sink of an “infinite” base size. Heat-transfer enhancement due to the fins is assessed quantitatively and analyzed for various base sizes and fin heights. The effect of fin location in the array on its contribution to the heat-transfer rate from the sink is analyzed. By decoupling convection from radiation, a dimensional analysis of the results for natural convection is attempted. Interdependence of the base size and fin height effects on the heat transfer is demonstrated. A correlation that encompasses all the cases studied herein is obtained, in which the Nusselt number depends on the Rayleigh number, which uses the “clear” spacing between fins as the characteristic length, and on the dimensions of the fins and the base. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Scale-up and generalization of horizontal-base pin-fin heat sinks in natural convection and radiation [texte imprimé] / D. Sahray, Auteur ; G. Ziskind, Auteur ; R. Letan, Auteur . - 2010 . - pp. [112502-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112502-1/10] Mots-clés : Pin  fin  Natural  convection  Scale-up  Correlation Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper provides further insight in heat transfer from horizontal-base pin fin heat-sinks in free convection of air. The main objective is to assess the effect of base size, and this with regard to the effects of fin height and fin population density studied in a previous work (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13). To this end, experimental and numerical investigations are performed with sinks of different base sizes. The sinks are made of aluminum, with no contact resistance between the base and the fins, and are heated using foil electrical heaters. In the corresponding numerical study, the sinks and their environment are modeled using the FLUENT 6.3 software. In the experiments, sink bases of 100×100 mm2 and 200×200 mm2 are used, while in the numerical study sinks of 50×50 mm2 are investigated, too. In addition to the sinks with exposed, free edges (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13), the same sinks are explored also with their edges blocked. This is done in order to exclude the edge effect, thus making it possible to estimate heat transfer from a sink of an “infinite” base size. Heat-transfer enhancement due to the fins is assessed quantitatively and analyzed for various base sizes and fin heights. The effect of fin location in the array on its contribution to the heat-transfer rate from the sink is analyzed. By decoupling convection from radiation, a dimensional analysis of the results for natural convection is attempted. Interdependence of the base size and fin height effects on the heat transfer is demonstrated. A correlation that encompasses all the cases studied herein is obtained, in which the Nusselt number depends on the Rayleigh number, which uses the “clear” spacing between fins as the characteristic length, and on the dimensions of the fins and the base. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Vadasz number influence on vibration in a rotating porous layer placed far away from the axis of rotation / S. Govender in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112601-1/5] Titre : Vadasz number influence on vibration in a rotating porous layer placed far away from the axis of rotation Type de document : texte imprimé Auteurs : S. Govender, Auteur Année de publication : 2010 Article en page(s) : pp. [112601-1/5] Note générale : Physique Langues : Anglais (eng) Mots-clés : Gravity  modulation  Porous  media  Natural  convection  Rayleigh  number  Froude  number Index. décimale : 536 Chaleur. Thermodynamique Résumé : We consider vibration effects on the classical Rayleigh–Be'nard problem and the classical Vadasz (1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) problem, which includes rotation of a vertical porous layer about the z-axis. In particular, we focus on the influence of the Vadasz number on vibration for small to moderate and large Vadasz numbers. For small to moderate Vadasz numbers, we develop an analogy between the Vadasz problem (Vadasz, 1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) placed far away from the axis of rotation and classical Rayleigh–Be'nard problem, both of which include the effects of vibration. It is shown here that the stability criteria are identical to the Rayleigh–Be'nard problem with vibration when g*=omega*2X0*. The analysis for the large Vadasz number scaling indicates that a frozen time approximation is appropriate where the effect of vibration is modeled as small variations in the Rayleigh number definition. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Vadasz number influence on vibration in a rotating porous layer placed far away from the axis of rotation [texte imprimé] / S. Govender, Auteur . - 2010 . - pp. [112601-1/5]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112601-1/5] Mots-clés : Gravity  modulation  Porous  media  Natural  convection  Rayleigh  number  Froude  number Index. décimale : 536 Chaleur. Thermodynamique Résumé : We consider vibration effects on the classical Rayleigh–Be'nard problem and the classical Vadasz (1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) problem, which includes rotation of a vertical porous layer about the z-axis. In particular, we focus on the influence of the Vadasz number on vibration for small to moderate and large Vadasz numbers. For small to moderate Vadasz numbers, we develop an analogy between the Vadasz problem (Vadasz, 1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) placed far away from the axis of rotation and classical Rayleigh–Be'nard problem, both of which include the effects of vibration. It is shown here that the stability criteria are identical to the Rayleigh–Be'nard problem with vibration when g*=omega*2X0*. The analysis for the large Vadasz number scaling indicates that a frozen time approximation is appropriate where the effect of vibration is modeled as small variations in the Rayleigh number definition. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Radiation and conduction in an isotropic scattering rectangular medium with one semitransparent and diffusely reflecting boundary / Jian-Feng Luo in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112701-1/11] Titre : Radiation and conduction in an isotropic scattering rectangular medium with one semitransparent and diffusely reflecting boundary Type de document : texte imprimé Auteurs : Jian-Feng Luo, Auteur ; Hong-Liang Yi, Auteur ; Sheng-Li Chang, Auteur Année de publication : 2010 Article en page(s) : pp. [112701-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Ray  tracing-node  analyzing  method  2D  rectangular  semitransparent  medium  Diffuse  reflectivity  Transient  Radiation Index. décimale : 536 Chaleur. Thermodynamique Résumé : Using the ray tracing-node analyzing method, the 2D transient coupled radiative and conductive heat transfer in a rectangular semitransparent medium is investigated. The rectangular medium has one semitransparent and diffuse boundary (the other three boundaries are black) and is isotropically scattering. The transient differential energy equation is discretized by the fully implicit finite difference method, and the radiative source term of the energy equation is expressed by the radiative transfer coefficients (RTCs). The integrality and reciprocity relationships of the RTCs without considering scattering for the 2D physical model are discovered, which are much different from those for the 1D case. When solving the isotropic scattering RTCs, the RTCs without considering scattering are normalized at first, and then the normalized RTCs are used to trace the energy scattered by control volumes. Finally, the isotropic scattering RTCs are solved by reverse calculation. The Patankar's linearization method is used to linearize the radiative source term and the opaque boundary conditions, and the boundary conditions are dealt with an additional source term method. The alternating direction implicit method is applied to solve the nominal linearized equations. The effects of scattering albedo, extinction coefficient, refractive index, etc., on transient coupled heat transfer are studied. The study shows that when the extinction coefficient is so small, the increase in scattering albedo can intensify the cooling of the three black surfaces of the rectangular medium. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Radiation and conduction in an isotropic scattering rectangular medium with one semitransparent and diffusely reflecting boundary [texte imprimé] / Jian-Feng Luo, Auteur ; Hong-Liang Yi, Auteur ; Sheng-Li Chang, Auteur . - 2010 . - pp. [112701-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112701-1/11] Mots-clés : Ray  tracing-node  analyzing  method  2D  rectangular  semitransparent  medium  Diffuse  reflectivity  Transient  Radiation Index. décimale : 536 Chaleur. Thermodynamique Résumé : Using the ray tracing-node analyzing method, the 2D transient coupled radiative and conductive heat transfer in a rectangular semitransparent medium is investigated. The rectangular medium has one semitransparent and diffuse boundary (the other three boundaries are black) and is isotropically scattering. The transient differential energy equation is discretized by the fully implicit finite difference method, and the radiative source term of the energy equation is expressed by the radiative transfer coefficients (RTCs). The integrality and reciprocity relationships of the RTCs without considering scattering for the 2D physical model are discovered, which are much different from those for the 1D case. When solving the isotropic scattering RTCs, the RTCs without considering scattering are normalized at first, and then the normalized RTCs are used to trace the energy scattered by control volumes. Finally, the isotropic scattering RTCs are solved by reverse calculation. The Patankar's linearization method is used to linearize the radiative source term and the opaque boundary conditions, and the boundary conditions are dealt with an additional source term method. The alternating direction implicit method is applied to solve the nominal linearized equations. The effects of scattering albedo, extinction coefficient, refractive index, etc., on transient coupled heat transfer are studied. The study shows that when the extinction coefficient is so small, the increase in scattering albedo can intensify the cooling of the three black surfaces of the rectangular medium. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Thermohydraulic study of a flat plate heat pipe by means of confocal microscopy / Stéphane Lips in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112901-1/9] Titre : Thermohydraulic study of a flat plate heat pipe by means of confocal microscopy : application to a 2D capillary structure Type de document : texte imprimé Auteurs : Stéphane Lips, Auteur ; Frédéric Lefèvre, Auteur ; Bonjour, Jocelyn, Auteur Année de publication : 2010 Article en page(s) : pp. [112901-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Flat  plate  heat  pipe  Crossed  grooves  2D  capillary  structure  Confocal  microscopy  Meniscus Index. décimale : 536 Chaleur. Thermodynamique Résumé : Thermal and hydrodynamic experimental results of a flat plate heat pipe (FPHP) are presented. The capillary structure is made of crossed grooves machined in a copper plate. The shape of the liquid-vapor interface in this type of capillary structure—that can also be viewed as an array of posts—is studied theoretically and experimentally. A confocal microscope is used to visualize the liquid-vapor interface and thus the capillary pressure field in the system. These hydrodynamic measurements, coupled to temperature measurements on the FPHP wall, are used to estimate the permeability and the equivalent thermal conductivity of the capillary structure filled with methanol or FC72. These parameters are obtained from a comparison between the experimental data and an analytical model. Finally, the model is used to compare the draining capability of crossed grooves with that of longitudinal grooves. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Thermohydraulic study of a flat plate heat pipe by means of confocal microscopy : application to a 2D capillary structure [texte imprimé] / Stéphane Lips, Auteur ; Frédéric Lefèvre, Auteur ; Bonjour, Jocelyn, Auteur . - 2010 . - pp. [112901-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [112901-1/9] Mots-clés : Flat  plate  heat  pipe  Crossed  grooves  2D  capillary  structure  Confocal  microscopy  Meniscus Index. décimale : 536 Chaleur. Thermodynamique Résumé : Thermal and hydrodynamic experimental results of a flat plate heat pipe (FPHP) are presented. The capillary structure is made of crossed grooves machined in a copper plate. The shape of the liquid-vapor interface in this type of capillary structure—that can also be viewed as an array of posts—is studied theoretically and experimentally. A confocal microscope is used to visualize the liquid-vapor interface and thus the capillary pressure field in the system. These hydrodynamic measurements, coupled to temperature measurements on the FPHP wall, are used to estimate the permeability and the equivalent thermal conductivity of the capillary structure filled with methanol or FC72. These parameters are obtained from a comparison between the experimental data and an analytical model. Finally, the model is used to compare the draining capability of crossed grooves with that of longitudinal grooves. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Effect of rotation on heat/mass transfer for an impingement/effusion cooling system / Sung Kook Hong in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [114501-1/3] Titre : Effect of rotation on heat/mass transfer for an impingement/effusion cooling system Type de document : texte imprimé Auteurs : Sung Kook Hong, Auteur ; Dong Hyun Lee, Auteur ; Hyung Hee Cho, Auteur Année de publication : 2010 Article en page(s) : pp. [114501-1/3] Note générale : Physique Langues : Anglais (eng) Mots-clés : Impingement/effusion  cooling  Gas  turbine  Heat  transfer  Coriolis  force  Rotation Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present study, the effects of the rotating direction on heat/mass transfer in an impingement/effusion cooling system were investigated. The experiments were carried out with three different jet orientations relative to the axis of rotation and two plate spacing. For high H/d with an orthogonal jet orientation, low and nonuniform heat/mass transfer occurred between the effusion holes since the impinging jet was deflected by the Coriolis force. For a small H/d, the jet deflection effect was diminished, and rotation enhanced the heat/mass transfer in the stagnation region. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Effect of rotation on heat/mass transfer for an impingement/effusion cooling system [texte imprimé] / Sung Kook Hong, Auteur ; Dong Hyun Lee, Auteur ; Hyung Hee Cho, Auteur . - 2010 . - pp. [114501-1/3]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp. [114501-1/3] Mots-clés : Impingement/effusion  cooling  Gas  turbine  Heat  transfer  Coriolis  force  Rotation Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present study, the effects of the rotating direction on heat/mass transfer in an impingement/effusion cooling system were investigated. The experiments were carried out with three different jet orientations relative to the axis of rotation and two plate spacing. For high H/d with an orthogonal jet orientation, low and nonuniform heat/mass transfer occurred between the effusion holes since the impinging jet was deflected by the Coriolis force. For a small H/d, the jet deflection effect was diminished, and rotation enhanced the heat/mass transfer in the stagnation region. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

A Four-step fixed-grid method for 1D stefan problems / M. Tadi in Journal of heat transfer, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp.[114502-1/4] Titre : A Four-step fixed-grid method for 1D stefan problems Type de document : texte imprimé Auteurs : M. Tadi, Auteur Année de publication : 2010 Article en page(s) : pp.[114502-1/4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Stefan  problems  Parabolic  systems Index. décimale : 536 Chaleur. Thermodynamique Résumé : This note is concerned with a fixed-grid finite difference method for the solution of one-dimensional free boundary problems. The method solves for the field variables and the location of the boundary in separate steps. As a result of this decoupling, the nonlinear part of the algorithm involves only a scalar unknown, which is the location of the moving boundary. A number of examples are used to study the applicability of the method. The method is particularly useful for moving boundary problems with various conditions at the front. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] A Four-step fixed-grid method for 1D stefan problems [texte imprimé] / M. Tadi, Auteur . - 2010 . - pp.[114502-1/4]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 11 (Novembre 2010) . - pp.[114502-1/4] Mots-clés : Stefan  problems  Parabolic  systems Index. décimale : 536 Chaleur. Thermodynamique Résumé : This note is concerned with a fixed-grid finite difference method for the solution of one-dimensional free boundary problems. The method solves for the field variables and the location of the boundary in separate steps. As a result of this decoupling, the nonlinear part of the algorithm involves only a scalar unknown, which is the location of the moving boundary. A number of examples are used to study the applicability of the method. The method is particularly useful for moving boundary problems with various conditions at the front. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

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