Dépouillements

Analysis of bioheat transport through a dual layer biological media / Shadi Mahjoob in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031101-1/14] Titre : Analysis of bioheat transport through a dual layer biological media Type de document : texte imprimé Auteurs : Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur Article en page(s) : pp. [031101-1/14] Note générale : Physique Langues : Anglais (eng) Mots-clés : Bioheat  transfer  Biological  tissue/organ  Hyperthermia  Porous  media  Multilayer  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : A comprehensive analysis of bioheat transport through a double layer and multilayer biological media is presented in this work. Analytical solutions have been developed for blood and tissue phase temperatures and overall heat exchange correlations, incorporating thermal conduction in tissue and vascular system, blood-tissue convective heat exchange, metabolic heat generation, and imposed heat flux, utilizing both local thermal nonequilibrium and equilibrium models in porous media theory. Detailed solutions as well as Nusselt number distributions are given, for the first time, for two primary conditions, namely, isolated core region and uniform core temperature. The solutions incorporate the pertinent effective parameters for each layer, such as volume fraction of the vascular space, ratio of the blood, and the tissue matrix thermal conductivities, interfacial blood-tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties. Interface temperature profiles are also obtained based on the continuity of temperature and heat flux through the interface and the physics of the problem. Comparisons between these analytical solutions and limiting cases from previous works display an excellent agreement. These analytical solutions establish a comprehensive presentation of bioheat transport, which can be used to clarify various physical phenomena as well as establishing a detailed benchmark for future works in this area. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Analysis of bioheat transport through a dual layer biological media [texte imprimé] / Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur . - pp. [031101-1/14]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031101-1/14] Mots-clés : Bioheat  transfer  Biological  tissue/organ  Hyperthermia  Porous  media  Multilayer  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : A comprehensive analysis of bioheat transport through a double layer and multilayer biological media is presented in this work. Analytical solutions have been developed for blood and tissue phase temperatures and overall heat exchange correlations, incorporating thermal conduction in tissue and vascular system, blood-tissue convective heat exchange, metabolic heat generation, and imposed heat flux, utilizing both local thermal nonequilibrium and equilibrium models in porous media theory. Detailed solutions as well as Nusselt number distributions are given, for the first time, for two primary conditions, namely, isolated core region and uniform core temperature. The solutions incorporate the pertinent effective parameters for each layer, such as volume fraction of the vascular space, ratio of the blood, and the tissue matrix thermal conductivities, interfacial blood-tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties. Interface temperature profiles are also obtained based on the continuity of temperature and heat flux through the interface and the physics of the problem. Comparisons between these analytical solutions and limiting cases from previous works display an excellent agreement. These analytical solutions establish a comprehensive presentation of bioheat transport, which can be used to clarify various physical phenomena as well as establishing a detailed benchmark for future works in this area. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Pool boiling heat transfer of water on finned surfaces at near vacuum pressures / Mark Aaron Chan in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031501-1/6] Titre : Pool boiling heat transfer of water on finned surfaces at near vacuum pressures Type de document : texte imprimé Auteurs : Mark Aaron Chan, Auteur ; Christopher R. Yap, Auteur ; Kim Choon Ng, Auteur Article en page(s) : pp. [031501-1/6] Note générale : Physique Langues : Anglais (eng) Mots-clés : Boiling  Extended  surfaces  Subatmospheric  pressure  Boiling  enhancement  Thermosyphon  Electronic  cooling  Bubble  visualization Index. décimale : 536 Chaleur. Thermodynamique Résumé : This research paper presents a study of boiling heat transfer from longitudinal rectangular-finned surfaces immersed in saturated water at low vapor pressures. Finned surfaces with assorted fin spacing, fin thicknesses, and fin heights on a copper based surface have been investigated. All the finned surfaces were found to increase both boiling heat transfer coefficients and critical heat fluxes. An optimal fin thickness was found for a configuration, and heat transfer coefficients have been obtained at the pressures. Factors affecting the boiling characteristics have been identified and the optimal enhancement requires a balance of the active nucleation sites, bubble flow resistance, natural convection, thin film evaporation, liquid superheating, heat transfer area, bubble coalescence, and liquid reflux resistance. High speed visualization of vapor plug and vapor film generation on the boiling surfaces has revealed significant insights into the boiling mechanisms at low saturation pressures. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Pool boiling heat transfer of water on finned surfaces at near vacuum pressures [texte imprimé] / Mark Aaron Chan, Auteur ; Christopher R. Yap, Auteur ; Kim Choon Ng, Auteur . - pp. [031501-1/6]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031501-1/6] Mots-clés : Boiling  Extended  surfaces  Subatmospheric  pressure  Boiling  enhancement  Thermosyphon  Electronic  cooling  Bubble  visualization Index. décimale : 536 Chaleur. Thermodynamique Résumé : This research paper presents a study of boiling heat transfer from longitudinal rectangular-finned surfaces immersed in saturated water at low vapor pressures. Finned surfaces with assorted fin spacing, fin thicknesses, and fin heights on a copper based surface have been investigated. All the finned surfaces were found to increase both boiling heat transfer coefficients and critical heat fluxes. An optimal fin thickness was found for a configuration, and heat transfer coefficients have been obtained at the pressures. Factors affecting the boiling characteristics have been identified and the optimal enhancement requires a balance of the active nucleation sites, bubble flow resistance, natural convection, thin film evaporation, liquid superheating, heat transfer area, bubble coalescence, and liquid reflux resistance. High speed visualization of vapor plug and vapor film generation on the boiling surfaces has revealed significant insights into the boiling mechanisms at low saturation pressures. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Confocal microscopy for capillary film measurements in a flat plate heat pipe / Frédéric Lefèvre in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031502-1/6] Titre : Confocal microscopy for capillary film measurements in a flat plate heat pipe Type de document : texte imprimé Auteurs : Frédéric Lefèvre, Auteur ; Romuald Rullière, Auteur ; Stéphane Lips, Auteur Article en page(s) : pp. [031502-1/6] Note générale : Physique Langues : Anglais (eng) Mots-clés : Evaporation  Condensation  Flat  plate  heat  pipes  Thin  film  Capillarity Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper aims to show how confocal microscopy can be useful for characterizing menisci in a flat plate heat pipe made of silicon. The capillary structure is made of radial microgrooves whose width decreases from the periphery to the center of the system. A transparent plate is used to close the system and allow visualizations. The confocal method allows measuring both the liquid film shape inside the grooves and the condensate films on the fins. The film thickness is lower than 10 µm. The measurements show that the condensate film forms a drop connected to the meniscus in the grooves but their curvatures are reversed. As a result, a very thin region shall exist where the liquid formed by condensation is drained to the grooves. The drop curvature radius decreases from the condenser to the evaporator like the meniscus radius in the grooves. Therefore, a small part of the liquid is drained by the fins from the evaporator to the condenser. Furthermore, the condensate film covers a large part of the system and can also be in contact with the evaporator at high heat fluxes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Confocal microscopy for capillary film measurements in a flat plate heat pipe [texte imprimé] / Frédéric Lefèvre, Auteur ; Romuald Rullière, Auteur ; Stéphane Lips, Auteur . - pp. [031502-1/6]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031502-1/6] Mots-clés : Evaporation  Condensation  Flat  plate  heat  pipes  Thin  film  Capillarity Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper aims to show how confocal microscopy can be useful for characterizing menisci in a flat plate heat pipe made of silicon. The capillary structure is made of radial microgrooves whose width decreases from the periphery to the center of the system. A transparent plate is used to close the system and allow visualizations. The confocal method allows measuring both the liquid film shape inside the grooves and the condensate films on the fins. The film thickness is lower than 10 µm. The measurements show that the condensate film forms a drop connected to the meniscus in the grooves but their curvatures are reversed. As a result, a very thin region shall exist where the liquid formed by condensation is drained to the grooves. The drop curvature radius decreases from the condenser to the evaporator like the meniscus radius in the grooves. Therefore, a small part of the liquid is drained by the fins from the evaporator to the condenser. Furthermore, the condensate film covers a large part of the system and can also be in contact with the evaporator at high heat fluxes. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Flow boiling visualization of R-134a in a vertical channel of small diameter / Claudi Martín-Callizo in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031503-1/8] Titre : Flow boiling visualization of R-134a in a vertical channel of small diameter Type de document : texte imprimé Auteurs : Claudi Martín-Callizo, Auteur ; Björn Palm, Auteur ; Wahib Owhaib, Auteur Article en page(s) : pp. [031503-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Flow  boiling  Two-phase  Flow  patterns  Microchannel  Refrigerant  R-134a Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with an internal diameter of 1.33 mm and 235 mm in heated length. A quartz tube with a homogeneous Indium Tin Oxide coating is used to allow heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of high-speed complementary metal oxide semiconductor (CMOS) digital camera. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. The effects of the saturation temperature and the inlet subcooling degree on the two-phase flow pattern transitions are elucidated. Finally, the experimental flow pattern map is compared with models developed for conventional sizes as well as to a microscale map for air-water mixtures available in literature, showing a large discrepancy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Flow boiling visualization of R-134a in a vertical channel of small diameter [texte imprimé] / Claudi Martín-Callizo, Auteur ; Björn Palm, Auteur ; Wahib Owhaib, Auteur . - pp. [031503-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031503-1/8] Mots-clés : Flow  boiling  Two-phase  Flow  patterns  Microchannel  Refrigerant  R-134a Index. décimale : 536 Chaleur. Thermodynamique Résumé : The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with an internal diameter of 1.33 mm and 235 mm in heated length. A quartz tube with a homogeneous Indium Tin Oxide coating is used to allow heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of high-speed complementary metal oxide semiconductor (CMOS) digital camera. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. The effects of the saturation temperature and the inlet subcooling degree on the two-phase flow pattern transitions are elucidated. Finally, the experimental flow pattern map is compared with models developed for conventional sizes as well as to a microscale map for air-water mixtures available in literature, showing a large discrepancy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Convection calibration of schmidt–boelter heat flux gauges in stagnation and shear air flow / A. Gifford in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031601-1/9] Titre : Convection calibration of schmidt–boelter heat flux gauges in stagnation and shear air flow Type de document : texte imprimé Auteurs : A. Gifford, Auteur ; A. Hoffie, Auteur ; T. Diller, Auteur Article en page(s) : pp. [031601-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  flux  gauge  Sensor  calibration  Convection  effects Index. décimale : 536 Chaleur. Thermodynamique Résumé : Experiments were performed to characterize the performance of Schmidt–Boelter heat flux gauges in stagnation and shear convective air flows. The gauges were of a standard design (25.4 mm and 38 mm in diameter), using a copper heat sink with water cooling channels around the active sensing element. A simple model of the gauges using an internal thermal resistance between the sensor surface and the heat sink is used to interpret the results. The model predicts a nonlinear dependence of the gauge sensitivity as a function of the heat transfer coefficient. Experimental calibration systems were developed to simultaneously measure the heat flux gauge response relative to a secondary standard under the same flow and thermal conditions. The measured gauge sensitivities in the stagnation flow matched the model, and were used to estimate the value of the internal thermal resistance for each of the four gauges tested. For shear flow, the effect of the varying gauge surface temperature on the boundary layer was included. The results matched the model with a constant factor of 15–25% lower effective heat transfer coefficient. When the gauge was water cooled, the effect of the internal thermal resistance of the gauge was markedly different for the two flow conditions. In the stagnation flow, the internal resistance further decreased the apparent gauge sensitivity. Conversely, in shear flow, the resistance was effectively offset by the cooler heat sink of the gauge, and the resulting sensitivities were nearly the same as, or larger than, for radiation. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Convection calibration of schmidt–boelter heat flux gauges in stagnation and shear air flow [texte imprimé] / A. Gifford, Auteur ; A. Hoffie, Auteur ; T. Diller, Auteur . - pp. [031601-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031601-1/9] Mots-clés : Heat  flux  gauge  Sensor  calibration  Convection  effects Index. décimale : 536 Chaleur. Thermodynamique Résumé : Experiments were performed to characterize the performance of Schmidt–Boelter heat flux gauges in stagnation and shear convective air flows. The gauges were of a standard design (25.4 mm and 38 mm in diameter), using a copper heat sink with water cooling channels around the active sensing element. A simple model of the gauges using an internal thermal resistance between the sensor surface and the heat sink is used to interpret the results. The model predicts a nonlinear dependence of the gauge sensitivity as a function of the heat transfer coefficient. Experimental calibration systems were developed to simultaneously measure the heat flux gauge response relative to a secondary standard under the same flow and thermal conditions. The measured gauge sensitivities in the stagnation flow matched the model, and were used to estimate the value of the internal thermal resistance for each of the four gauges tested. For shear flow, the effect of the varying gauge surface temperature on the boundary layer was included. The results matched the model with a constant factor of 15–25% lower effective heat transfer coefficient. When the gauge was water cooled, the effect of the internal thermal resistance of the gauge was markedly different for the two flow conditions. In the stagnation flow, the internal resistance further decreased the apparent gauge sensitivity. Conversely, in shear flow, the resistance was effectively offset by the cooler heat sink of the gauge, and the resulting sensitivities were nearly the same as, or larger than, for radiation. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

A hybrid method for measuring heat flux / David O. Hubble in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031602 -1/8] Titre : A hybrid method for measuring heat flux Type de document : texte imprimé Auteurs : David O. Hubble, Auteur ; Tom E. Diller, Auteur Article en page(s) : pp. [031602 -1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  flux  gauge  Thermal  time  response  Slug  calorimeter Index. décimale : 536 Chaleur. Thermodynamique Résumé : The development and evaluation of a novel hybrid method for obtaining heat flux measurements is presented. By combining the spatial and temporal temperature measurements of a heat flux sensor, the time response, accuracy, and versatility of the sensor is improved. Sensors utilizing the hybrid method are able to make heat flux measurements on both high and low conductivity materials. It is shown that changing the thermal conductivity of the backing material four orders of magnitude causes only an 11% change in sensor response. The hybrid method also increases the time response of heat flux sensors. The temporal response is shown to increase by up to a factor of 28 compared with a standard spatial sensor. The hybrid method is tested both numerically and experimentally on both high and low conductivity materials and demonstrates significant improvement compared with operating the sensor as a spatial or temporal sensor alone. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] A hybrid method for measuring heat flux [texte imprimé] / David O. Hubble, Auteur ; Tom E. Diller, Auteur . - pp. [031602 -1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031602 -1/8] Mots-clés : Heat  flux  gauge  Thermal  time  response  Slug  calorimeter Index. décimale : 536 Chaleur. Thermodynamique Résumé : The development and evaluation of a novel hybrid method for obtaining heat flux measurements is presented. By combining the spatial and temporal temperature measurements of a heat flux sensor, the time response, accuracy, and versatility of the sensor is improved. Sensors utilizing the hybrid method are able to make heat flux measurements on both high and low conductivity materials. It is shown that changing the thermal conductivity of the backing material four orders of magnitude causes only an 11% change in sensor response. The hybrid method also increases the time response of heat flux sensors. The temporal response is shown to increase by up to a factor of 28 compared with a standard spatial sensor. The hybrid method is tested both numerically and experimentally on both high and low conductivity materials and demonstrates significant improvement compared with operating the sensor as a spatial or temporal sensor alone. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Fluorescence and fiber-optics based real-time thickness sensor for dynamic liquid films / T. W. Ng in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031603-1/12] Titre : Fluorescence and fiber-optics based real-time thickness sensor for dynamic liquid films Type de document : texte imprimé Auteurs : T. W. Ng, Auteur ; A. Narain, Auteur ; M. T. Kivisalu, Auteur Article en page(s) : pp. [031603-1/12] Note générale : Physique Langues : Anglais (eng) Mots-clés : Liquid  film  thickness  measurements  Real-time  liquid  thickness  sensor  Fiber-optic  sensor  Dynamic  liquid  film  Liquid-vapor  interface  Fluorescence  probe Index. décimale : 536 Chaleur. Thermodynamique Résumé : To overcome the limitations/disadvantages of many known liquid film thickness sensing devices (viz. conductivity probes, reflectance based fiber-optics probes, capacitance probes, etc.), a new liquid film thickness sensor that utilizes fluorescence phenomena and fiber-optic technology has been developed and reported here. Measurements from this sensor are expected to facilitate better understanding of liquid film dynamics in various adiabatic, evaporating, and condensing film flows. The sensor accurately measures the instantaneous thickness of a dynamically changing liquid film in such a way that the probe does not perturb the flow dynamics in the proximity of the probe's tip. This is achieved by having the probe's exposed surface embedded flush with the surface over which the liquid film flows, and by making arrangements for processing the signals associated with the emission and collection of light (in distinctly different wavelength windows) at the probe's flush surface. Instantaneous film thickness in the range of 0.5–3.0 mm can accurately (with a resolution that is within ±0.09 mm over 0.5–1.5 mm range and within ±0.18 mm over 1.5–3.0 mm range) be measured by the sensor described in this paper. Although this paper only demonstrates the sensor's ability for dynamic film thickness measurements carried out for a doped liquid called FC-72 (perfluorohexane or C6F14 from 3M Corporation, Minneapolis, MN), the approach and development/calibration procedure described here can be extended, under similar circumstances, to some other liquid films and other thickness ranges as well. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Fluorescence and fiber-optics based real-time thickness sensor for dynamic liquid films [texte imprimé] / T. W. Ng, Auteur ; A. Narain, Auteur ; M. T. Kivisalu, Auteur . - pp. [031603-1/12]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031603-1/12] Mots-clés : Liquid  film  thickness  measurements  Real-time  liquid  thickness  sensor  Fiber-optic  sensor  Dynamic  liquid  film  Liquid-vapor  interface  Fluorescence  probe Index. décimale : 536 Chaleur. Thermodynamique Résumé : To overcome the limitations/disadvantages of many known liquid film thickness sensing devices (viz. conductivity probes, reflectance based fiber-optics probes, capacitance probes, etc.), a new liquid film thickness sensor that utilizes fluorescence phenomena and fiber-optic technology has been developed and reported here. Measurements from this sensor are expected to facilitate better understanding of liquid film dynamics in various adiabatic, evaporating, and condensing film flows. The sensor accurately measures the instantaneous thickness of a dynamically changing liquid film in such a way that the probe does not perturb the flow dynamics in the proximity of the probe's tip. This is achieved by having the probe's exposed surface embedded flush with the surface over which the liquid film flows, and by making arrangements for processing the signals associated with the emission and collection of light (in distinctly different wavelength windows) at the probe's flush surface. Instantaneous film thickness in the range of 0.5–3.0 mm can accurately (with a resolution that is within ±0.09 mm over 0.5–1.5 mm range and within ±0.18 mm over 1.5–3.0 mm range) be measured by the sensor described in this paper. Although this paper only demonstrates the sensor's ability for dynamic film thickness measurements carried out for a doped liquid called FC-72 (perfluorohexane or C6F14 from 3M Corporation, Minneapolis, MN), the approach and development/calibration procedure described here can be extended, under similar circumstances, to some other liquid films and other thickness ranges as well. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

On the Mach number invariance of gas jets expanding into hot or cold environments / R. Sambasivam in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031701-1/8] Titre : On the Mach number invariance of gas jets expanding into hot or cold environments Type de document : texte imprimé Auteurs : R. Sambasivam, Auteur ; F. Durst, Auteur Article en page(s) : pp. [031701-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Jets  Mach  number  Supersonic  flow Index. décimale : 536 Chaleur. Thermodynamique Résumé : Gas jet flows expanding into a space containing the same medium but at a significant temperature difference are of concern in many fields of engineering. One such example is the expansion of supersonic oxygen jets in the basic oxygen furnace (BOF) steelmaking process. While studying the characteristics of such gas jets, an interesting invariance of the local Mach number with the change in the surrounding temperature was found. The velocity and temperature of the jet at any given location increased with the increasing ambient temperature. However, the local Mach number remained the same for all ambient temperatures. This interesting result was further studied since there is no mention of it in any published literature. The reasons for these characteristics of the jet are analyzed in this paper. It is stressed that this finding is of practical importance and can be used in experimental studies of submerged gas jets expanding into environments with different ambient temperatures. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] On the Mach number invariance of gas jets expanding into hot or cold environments [texte imprimé] / R. Sambasivam, Auteur ; F. Durst, Auteur . - pp. [031701-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031701-1/8] Mots-clés : Jets  Mach  number  Supersonic  flow Index. décimale : 536 Chaleur. Thermodynamique Résumé : Gas jet flows expanding into a space containing the same medium but at a significant temperature difference are of concern in many fields of engineering. One such example is the expansion of supersonic oxygen jets in the basic oxygen furnace (BOF) steelmaking process. While studying the characteristics of such gas jets, an interesting invariance of the local Mach number with the change in the surrounding temperature was found. The velocity and temperature of the jet at any given location increased with the increasing ambient temperature. However, the local Mach number remained the same for all ambient temperatures. This interesting result was further studied since there is no mention of it in any published literature. The reasons for these characteristics of the jet are analyzed in this paper. It is stressed that this finding is of practical importance and can be used in experimental studies of submerged gas jets expanding into environments with different ambient temperatures. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Flow visualization and local measurement of forced convection heat transfer in a microtube / Boris Schilder in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031702-1/9] Titre : Flow visualization and local measurement of forced convection heat transfer in a microtube Type de document : texte imprimé Auteurs : Boris Schilder, Auteur Article en page(s) : pp. [031702-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Boiling  Bubbles  Flow  visualisation  Forced  convection  Friction  Liquid  films  Microchannel  flow  Organic  compounds  Pattern  formation  Pipe  flow  Poiseuille  flow  Two-phase  flow  Water Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pressure drop and the convective heat transfer characteristics of ethanol and water in a circular tube with a diameter of 600 µm with and without phase change have been studied experimentally. The test section consists of a glass tube coated with a transparent indium tin oxide heater film. For single-phase liquid flow (including superheated liquid) it was found that the measured Nusselt numbers and friction factors are in good agreement with the theoretical values expected from Poiseuille flow. Subsequently, the boiling heat transfer of ethanol was studied. It was found that boiling with bubble growth in both upstream and downstream directions leaving behind a thin evaporating liquid film on the tube wall is the dominant phase change process. Wavy patterns on the film surface indicate shear forces between vapor and liquid phase during slug flow. Temporary dryout phenomena occur even at a low mean vapor quality due to film rupture as a result of film instabilities. Local Nusselt numbers are calculated for the two-phase flow at different heat fluxes and Reynolds numbers. Compared with single-phase flow the heat transfer is enhanced by a factor of 3–8. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Flow visualization and local measurement of forced convection heat transfer in a microtube [texte imprimé] / Boris Schilder, Auteur . - pp. [031702-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031702-1/9] Mots-clés : Boiling  Bubbles  Flow  visualisation  Forced  convection  Friction  Liquid  films  Microchannel  flow  Organic  compounds  Pattern  formation  Pipe  flow  Poiseuille  flow  Two-phase  flow  Water Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pressure drop and the convective heat transfer characteristics of ethanol and water in a circular tube with a diameter of 600 µm with and without phase change have been studied experimentally. The test section consists of a glass tube coated with a transparent indium tin oxide heater film. For single-phase liquid flow (including superheated liquid) it was found that the measured Nusselt numbers and friction factors are in good agreement with the theoretical values expected from Poiseuille flow. Subsequently, the boiling heat transfer of ethanol was studied. It was found that boiling with bubble growth in both upstream and downstream directions leaving behind a thin evaporating liquid film on the tube wall is the dominant phase change process. Wavy patterns on the film surface indicate shear forces between vapor and liquid phase during slug flow. Temporary dryout phenomena occur even at a low mean vapor quality due to film rupture as a result of film instabilities. Local Nusselt numbers are calculated for the two-phase flow at different heat fluxes and Reynolds numbers. Compared with single-phase flow the heat transfer is enhanced by a factor of 3–8. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Computational analysis of pin-fin arrays effects on internal heat transfer enhancement of a blade tip wall / Gongnan Xie in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031901-1/11] Titre : Computational analysis of pin-fin arrays effects on internal heat transfer enhancement of a blade tip wall Type de document : texte imprimé Auteurs : Gongnan Xie, Auteur ; Bengt Sundén, Auteur ; Esa Utriainen, Auteur Article en page(s) : pp. [031901-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Tip  wall  Pin  fins  Enhancement  Computation  Gas  turbine  cooling Index. décimale : 536 Chaleur. Thermodynamique Résumé : Cooling methods are strongly needed for the turbine blade tips to ensure a long durability and safe operation. Improving the internal convective cooling is therefore required to increase the blade tip life. A common way to cool the tip is to use serpentine passages with 180-deg turns under the blade tip cap. In this paper, enhanced heat transfer of a blade tip cap has been investigated numerically. The computational models consist of a two-pass channel with a 180-deg turn and various arrays of pin fins mounted on the tip cap, and a smooth two-pass channel. The inlet Reynolds number is ranging from 100,000 to 600,000. The computations are 3D, steady, incompressible, and nonrotating. Details of the 3D fluid flow and heat transfer over the tip walls are presented. The effects of pin-fin height, diameter, and pitches on the heat transfer enhancement on the blade tip walls are observed. The overall performances of ten models are compared and evaluated. It is found that due to the combination of turning, impingement, and pin-fin crossflow, the heat transfer coefficient of the pin-finned tip is a factor of 2.67 higher than that of a smooth tip. This augmentation is achieved at the expense of a penalty of pressure drop around 30%. Results show that the intensity of heat transfer enhancement depends upon pin-fin configuration and arrangement. It is suggested that pin fins could be used to enhance the blade tip heat transfer and cooling. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Computational analysis of pin-fin arrays effects on internal heat transfer enhancement of a blade tip wall [texte imprimé] / Gongnan Xie, Auteur ; Bengt Sundén, Auteur ; Esa Utriainen, Auteur . - pp. [031901-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031901-1/11] Mots-clés : Tip  wall  Pin  fins  Enhancement  Computation  Gas  turbine  cooling Index. décimale : 536 Chaleur. Thermodynamique Résumé : Cooling methods are strongly needed for the turbine blade tips to ensure a long durability and safe operation. Improving the internal convective cooling is therefore required to increase the blade tip life. A common way to cool the tip is to use serpentine passages with 180-deg turns under the blade tip cap. In this paper, enhanced heat transfer of a blade tip cap has been investigated numerically. The computational models consist of a two-pass channel with a 180-deg turn and various arrays of pin fins mounted on the tip cap, and a smooth two-pass channel. The inlet Reynolds number is ranging from 100,000 to 600,000. The computations are 3D, steady, incompressible, and nonrotating. Details of the 3D fluid flow and heat transfer over the tip walls are presented. The effects of pin-fin height, diameter, and pitches on the heat transfer enhancement on the blade tip walls are observed. The overall performances of ten models are compared and evaluated. It is found that due to the combination of turning, impingement, and pin-fin crossflow, the heat transfer coefficient of the pin-finned tip is a factor of 2.67 higher than that of a smooth tip. This augmentation is achieved at the expense of a penalty of pressure drop around 30%. Results show that the intensity of heat transfer enhancement depends upon pin-fin configuration and arrangement. It is suggested that pin fins could be used to enhance the blade tip heat transfer and cooling. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Equilibrium molecular dynamics study of lattice thermal conductivity/conductance of Au-SAM-Au junctions / Tengfei Luo in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032401-1/10] Titre : Equilibrium molecular dynamics study of lattice thermal conductivity/conductance of Au-SAM-Au junctions Type de document : texte imprimé Auteurs : Tengfei Luo, Auteur ; John R. Lloyd, Auteur Article en page(s) : pp. [032401-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Molecular  dynamics  Thermal  energy  transport  Interface Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, equilibrium molecular dynamics simulations were performed on Au-SAM (self-assembly monolayer)-Au junctions. The SAM consisted of alkanedithiol (–S–(CH2)n–S–) molecules. The out-of-plane (z-direction) thermal conductance and in-plane (x- and y-direction) thermal conductivities were calculated. The simulation finite size effect, gold substrate thickness effect, temperature effect, normal pressure effect, molecule chain length effect, and molecule coverage effect on thermal conductivity/conductance were studied. Vibration power spectra of gold atoms in the substrate and sulfur atoms in the SAM were calculated, and vibration coupling of these two parts was analyzed. The calculated thermal conductance values of Au-SAM-Au junctions are in the range of experimental data on metal-nonmetal junctions. The temperature dependence of thermal conductance has a similar trend to experimental observations. It is concluded that the Au-SAM interface resistance dominates thermal energy transport across the junction, while the substrate is the dominant media in which in-plane thermal energy transport happens. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Equilibrium molecular dynamics study of lattice thermal conductivity/conductance of Au-SAM-Au junctions [texte imprimé] / Tengfei Luo, Auteur ; John R. Lloyd, Auteur . - pp. [032401-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032401-1/10] Mots-clés : Molecular  dynamics  Thermal  energy  transport  Interface Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, equilibrium molecular dynamics simulations were performed on Au-SAM (self-assembly monolayer)-Au junctions. The SAM consisted of alkanedithiol (–S–(CH2)n–S–) molecules. The out-of-plane (z-direction) thermal conductance and in-plane (x- and y-direction) thermal conductivities were calculated. The simulation finite size effect, gold substrate thickness effect, temperature effect, normal pressure effect, molecule chain length effect, and molecule coverage effect on thermal conductivity/conductance were studied. Vibration power spectra of gold atoms in the substrate and sulfur atoms in the SAM were calculated, and vibration coupling of these two parts was analyzed. The calculated thermal conductance values of Au-SAM-Au junctions are in the range of experimental data on metal-nonmetal junctions. The temperature dependence of thermal conductance has a similar trend to experimental observations. It is concluded that the Au-SAM interface resistance dominates thermal energy transport across the junction, while the substrate is the dominant media in which in-plane thermal energy transport happens. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Ultra-low thermal conductivity in nanoscale layered oxides / J. Alvarez-Quintana in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032402-1/6] Titre : Ultra-low thermal conductivity in nanoscale layered oxides Type de document : texte imprimé Auteurs : J. Alvarez-Quintana, Auteur ; Ll. Peralba-Garcia, Auteur ; J. L. Lábár, Auteur Article en page(s) : pp. [032402-1/6] Note générale : Physique Langues : Anglais (eng) Mots-clés : Dielectric  oxides  Ultra-low  thermal  conductivity  Multilayers Index. décimale : 536 Chaleur. Thermodynamique Résumé : The cross-plane thermal conductivity of several nanoscale layered oxides SiO2/Y2O3, SiO2/Cr2O3, and SiO2/Al2O3, synthesized by e-beam evaporation was measured in the range from 30 K to 300 K by the 3omega method. Thermal conductivity attains values around 0.5 W/m K at room temperature in multilayer samples, formed by 20 bilayers of 10 nm SiO2/10 nm Y2O3, and as low as 0.16 W/m K for a single bilayer. The reduction in thermal conductivity is related to the high interface density, which produces a strong barrier to heat transfer rather than to the changes of the intrinsic thermal conductivity due to the nanometer thickness of the layers. We show that the influence of the first few interfaces on the overall thermal resistance is higher than the subsequent ones. Annealing the multilayered samples to 1100°C slightly increases the thermal conductivity due to changes in the microstructure. These results suggest a route to obtain suitable thermal barrier coatings for high temperature applications. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Ultra-low thermal conductivity in nanoscale layered oxides [texte imprimé] / J. Alvarez-Quintana, Auteur ; Ll. Peralba-Garcia, Auteur ; J. L. Lábár, Auteur . - pp. [032402-1/6]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032402-1/6] Mots-clés : Dielectric  oxides  Ultra-low  thermal  conductivity  Multilayers Index. décimale : 536 Chaleur. Thermodynamique Résumé : The cross-plane thermal conductivity of several nanoscale layered oxides SiO2/Y2O3, SiO2/Cr2O3, and SiO2/Al2O3, synthesized by e-beam evaporation was measured in the range from 30 K to 300 K by the 3omega method. Thermal conductivity attains values around 0.5 W/m K at room temperature in multilayer samples, formed by 20 bilayers of 10 nm SiO2/10 nm Y2O3, and as low as 0.16 W/m K for a single bilayer. The reduction in thermal conductivity is related to the high interface density, which produces a strong barrier to heat transfer rather than to the changes of the intrinsic thermal conductivity due to the nanometer thickness of the layers. We show that the influence of the first few interfaces on the overall thermal resistance is higher than the subsequent ones. Annealing the multilayered samples to 1100°C slightly increases the thermal conductivity due to changes in the microstructure. These results suggest a route to obtain suitable thermal barrier coatings for high temperature applications. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Investigations on multimode heat transfer from a heated vertical plate / R. Krishna Sabareesh in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032501-1/8] Titre : Investigations on multimode heat transfer from a heated vertical plate Type de document : texte imprimé Auteurs : R. Krishna Sabareesh, Auteur ; S. Prasanna, Auteur ; S. P. Venkateshan, Auteur Article en page(s) : pp. [032501-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Multimode  heat  transfer  Interfermeter  Thermal  conductivity  Emissivity  Asymptotic  limits Index. décimale : 536 Chaleur. Thermodynamique Résumé : The interaction of surface radiation and conduction with natural convection heat transfer from a vertical flat plate assembly, with an embedded heater, has been investigated, both experimentally (using differential interferometer) and numerically (using FLUENT), in the present work. In the absence of radiation, the asymptotic limits that can be attained by the heated plate are isothermal and isoflux conditions. High values of plate thermal conductivity tend to make the surface isothermal, where as, lower values of thermal conductivity tend to make it isoflux. Irrespective of the thermal conductivity of the plate, an increase in the emissivity reduces the average temperature of the plate and brings the plate toward isothermal condition. A new methodology has also been proposed to determine the thermophysical properties, emissivity and thermal conductivity, the consistency of which is tested by carrying out experiments for various heat inputs and comparing the estimated values with those available in literature. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Investigations on multimode heat transfer from a heated vertical plate [texte imprimé] / R. Krishna Sabareesh, Auteur ; S. Prasanna, Auteur ; S. P. Venkateshan, Auteur . - pp. [032501-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032501-1/8] Mots-clés : Multimode  heat  transfer  Interfermeter  Thermal  conductivity  Emissivity  Asymptotic  limits Index. décimale : 536 Chaleur. Thermodynamique Résumé : The interaction of surface radiation and conduction with natural convection heat transfer from a vertical flat plate assembly, with an embedded heater, has been investigated, both experimentally (using differential interferometer) and numerically (using FLUENT), in the present work. In the absence of radiation, the asymptotic limits that can be attained by the heated plate are isothermal and isoflux conditions. High values of plate thermal conductivity tend to make the surface isothermal, where as, lower values of thermal conductivity tend to make it isoflux. Irrespective of the thermal conductivity of the plate, an increase in the emissivity reduces the average temperature of the plate and brings the plate toward isothermal condition. A new methodology has also been proposed to determine the thermophysical properties, emissivity and thermal conductivity, the consistency of which is tested by carrying out experiments for various heat inputs and comparing the estimated values with those available in literature. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Transient methods of thermal properties measurement on fibrous materials / Zuo Lei in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032601-1/7] Titre : Transient methods of thermal properties measurement on fibrous materials Type de document : texte imprimé Auteurs : Zuo Lei, Auteur ; Sukang Zhu, Auteur ; Ning Pan, Auteur Article en page(s) : pp. [032601-1/7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Convection  Flow  instability  Flow  through  porous  media  Transient  analysis Index. décimale : 536 Chaleur. Thermodynamique Résumé : Fibrous material is a complex porous medium and steady test methods are the main test approaches we currently depend on to study the heat transfer properties. The application of unsteady test methods on fibrous material is still not mature. In this paper, some systematic studies are taken to investigate this problem. By analyzing the main factors impacting the test results, it is found that the local heat convection potentially excited by imposing test temperature can be avoided by limiting the internal temperature gradient and the so-called dual-phase lagging effects are negligible so that the feasibility of the unsteady test method is verified via both theoretical analysis and experimental data. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Transient methods of thermal properties measurement on fibrous materials [texte imprimé] / Zuo Lei, Auteur ; Sukang Zhu, Auteur ; Ning Pan, Auteur . - pp. [032601-1/7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032601-1/7] Mots-clés : Convection  Flow  instability  Flow  through  porous  media  Transient  analysis Index. décimale : 536 Chaleur. Thermodynamique Résumé : Fibrous material is a complex porous medium and steady test methods are the main test approaches we currently depend on to study the heat transfer properties. The application of unsteady test methods on fibrous material is still not mature. In this paper, some systematic studies are taken to investigate this problem. By analyzing the main factors impacting the test results, it is found that the local heat convection potentially excited by imposing test temperature can be avoided by limiting the internal temperature gradient and the so-called dual-phase lagging effects are negligible so that the feasibility of the unsteady test method is verified via both theoretical analysis and experimental data. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Natural convection from a porous cavity with sublayers of nonuniform thickness / R. L. III Marvel in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032602-1/6] Titre : Natural convection from a porous cavity with sublayers of nonuniform thickness : a lumped system analysis Type de document : texte imprimé Auteurs : R. L. III Marvel, Auteur ; F. C. Lai, Auteur Article en page(s) : pp. [032602-1/6] Note générale : Physique Langues : Anglais (eng) Mots-clés : Natural  convection  Heat  transfer  Porous  media  Numerical  method Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical study has been performed to further investigate the flow and temperature fields in layered porous cavity. The geometry considered is a two-dimensional square cavity comprising of three or four vertical sublayers with nonuniform thickness and distinct permeability. The cavity is subjected to differential heating from the vertical walls. The results obtained are used to further evaluate the capacity of the lumped-system analysis in the prediction of heat transfer results of layered porous cavities. It has been found that predictions by the lumped-system model are reasonably good for the range of Rayleigh numbers encountered in engineering applications. In addition, the predictions improve when the number of sublayers increases as well as the sublayer thickness becomes more uniform. Thus, it proves that the lumped-system analysis can offer a quick estimate of heat transfer result from a layered porous cavity with reasonable accuracy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Natural convection from a porous cavity with sublayers of nonuniform thickness : a lumped system analysis [texte imprimé] / R. L. III Marvel, Auteur ; F. C. Lai, Auteur . - pp. [032602-1/6]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [032602-1/6] Mots-clés : Natural  convection  Heat  transfer  Porous  media  Numerical  method Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical study has been performed to further investigate the flow and temperature fields in layered porous cavity. The geometry considered is a two-dimensional square cavity comprising of three or four vertical sublayers with nonuniform thickness and distinct permeability. The cavity is subjected to differential heating from the vertical walls. The results obtained are used to further evaluate the capacity of the lumped-system analysis in the prediction of heat transfer results of layered porous cavities. It has been found that predictions by the lumped-system model are reasonably good for the range of Rayleigh numbers encountered in engineering applications. In addition, the predictions improve when the number of sublayers increases as well as the sublayer thickness becomes more uniform. Thus, it proves that the lumped-system analysis can offer a quick estimate of heat transfer result from a layered porous cavity with reasonable accuracy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Optimization of a pin fin with variable base thickness / H. S. Kang in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034501-1/4] Titre : Optimization of a pin fin with variable base thickness Type de document : texte imprimé Auteurs : H. S. Kang, Auteur Article en page(s) : pp. [034501-1/4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Convection  characteristic  number  Fin  base  thickness  Heat  loss  Pin  fin  Optimization Index. décimale : 536 Chaleur. Thermodynamique Résumé : A pin fin with variable fin base thickness is optimized using a two-dimensional analytic method. The values of the inner wall temperature and fin volume are given as constants. The fin base temperature varies with variation in the fin base thickness, fin outer radius, fin length, and convection characteristic number. Under these conditions, the optimum heat loss, the corresponding optimum fin effectiveness, fin length, and fin outer radius are presented as functions of the fin base thickness, fin volume, and convection characteristic number. One of the results shows that both the optimum heat loss and optimum fin length decrease linearly with increase in the fin base thickness. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Optimization of a pin fin with variable base thickness [texte imprimé] / H. S. Kang, Auteur . - pp. [034501-1/4]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034501-1/4] Mots-clés : Convection  characteristic  number  Fin  base  thickness  Heat  loss  Pin  fin  Optimization Index. décimale : 536 Chaleur. Thermodynamique Résumé : A pin fin with variable fin base thickness is optimized using a two-dimensional analytic method. The values of the inner wall temperature and fin volume are given as constants. The fin base temperature varies with variation in the fin base thickness, fin outer radius, fin length, and convection characteristic number. Under these conditions, the optimum heat loss, the corresponding optimum fin effectiveness, fin length, and fin outer radius are presented as functions of the fin base thickness, fin volume, and convection characteristic number. One of the results shows that both the optimum heat loss and optimum fin length decrease linearly with increase in the fin base thickness. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Inverse heat conduction in a composite slab with pyrolysis effect and temperature-dependent thermophysical properties / Jianhua Zhou in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034502-1/3] Titre : Inverse heat conduction in a composite slab with pyrolysis effect and temperature-dependent thermophysical properties Type de document : texte imprimé Auteurs : Jianhua Zhou, Auteur ; Yuwen Zhang, Auteur ; J. K. Chen, Auteur Article en page(s) : pp. [034502-1/3] Note générale : Physique Langues : Anglais (eng) Mots-clés : Composite  Inverse  heat  conduction  Pyrolysis  Temperature-dependent  thermal  properties Index. décimale : 536 Chaleur. Thermodynamique Résumé : The inverse heat conduction problem (IHCP) in a one-dimensional composite slab with rate-dependent pyrolysis chemical reaction and outgassing flow effects is investigated using the iterative regularization approach. The thermal properties of the composites are considered to be temperature-dependent. A nonlinear conjugate gradient method formulation is developed and applied to solve the IHCP in an organic composite slab whose front-surface is subjected to high intensity periodic laser heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Inverse heat conduction in a composite slab with pyrolysis effect and temperature-dependent thermophysical properties [texte imprimé] / Jianhua Zhou, Auteur ; Yuwen Zhang, Auteur ; J. K. Chen, Auteur . - pp. [034502-1/3]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034502-1/3] Mots-clés : Composite  Inverse  heat  conduction  Pyrolysis  Temperature-dependent  thermal  properties Index. décimale : 536 Chaleur. Thermodynamique Résumé : The inverse heat conduction problem (IHCP) in a one-dimensional composite slab with rate-dependent pyrolysis chemical reaction and outgassing flow effects is investigated using the iterative regularization approach. The thermal properties of the composites are considered to be temperature-dependent. A nonlinear conjugate gradient method formulation is developed and applied to solve the IHCP in an organic composite slab whose front-surface is subjected to high intensity periodic laser heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Investigation of heat transfer enhancement through permeable fins / A.-R. A. Khaled in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034503-1/5] Titre : Investigation of heat transfer enhancement through permeable fins Type de document : texte imprimé Auteurs : A.-R. A. Khaled, Auteur Article en page(s) : pp. [034503-1/5] Note générale : Physique Langues : Anglais (eng) Mots-clés : Conduction  Heat  transfer  Enhancement  Permeable  fins  Convection Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer through rectangular permeable fins is modeled and analyzed theoretically in this work. The free stream fluid flow is considered to be normal to the upper surface of the permeable fin. The flow across the permeable fin is permitted in this work. The continuity, momentum, and energy equations are solved for the fluid flow using a similarity transformation and an iterative tridiagonal finite difference method. As such, a correlation for the Nusselt number is generated as functions of the Prandtl number (Pr) and dimensionless suction velocity (fo) for 0.7 DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Investigation of heat transfer enhancement through permeable fins [texte imprimé] / A.-R. A. Khaled, Auteur . - pp. [034503-1/5]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034503-1/5] Mots-clés : Conduction  Heat  transfer  Enhancement  Permeable  fins  Convection Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer through rectangular permeable fins is modeled and analyzed theoretically in this work. The free stream fluid flow is considered to be normal to the upper surface of the permeable fin. The flow across the permeable fin is permitted in this work. The continuity, momentum, and energy equations are solved for the fluid flow using a similarity transformation and an iterative tridiagonal finite difference method. As such, a correlation for the Nusselt number is generated as functions of the Prandtl number (Pr) and dimensionless suction velocity (fo) for 0.7 DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Heat transfer characterization of two isothermal circular cylinders in proximity / Taeheon Han in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034504-1/4] Titre : Heat transfer characterization of two isothermal circular cylinders in proximity Type de document : texte imprimé Auteurs : Taeheon Han, Auteur ; Kyung-Soo Yang, Auteur ; Kyongjun Lee, Auteur Article en page(s) : pp. [034504-1/4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Convective  heat  transfer  Immersed  boundary  method  Flow  pattern  Vortex  shedding  Wake  interaction Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer on two nearby isothermal circular cylinders of equal diameter immersed in a uniform crossflow at Re=120 and Pr=0.7 was numerically studied. We consider all possible arrangements of the two cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of heat transfer are noticed depending on how they are positioned, resulting in quantitative changes in heat transfer coefficients of both cylinders. Collecting all of the numerical results obtained, we propose a contour diagram for averaged Nusselt number for each of the two cylinders. The geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate heat transfer rates on two isothermal circular cylinders of equal diameter arbitrarily positioned in physical space with respect to the main flow direction. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Heat transfer characterization of two isothermal circular cylinders in proximity [texte imprimé] / Taeheon Han, Auteur ; Kyung-Soo Yang, Auteur ; Kyongjun Lee, Auteur . - pp. [034504-1/4]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [034504-1/4] Mots-clés : Convective  heat  transfer  Immersed  boundary  method  Flow  pattern  Vortex  shedding  Wake  interaction Index. décimale : 536 Chaleur. Thermodynamique Résumé : Heat transfer on two nearby isothermal circular cylinders of equal diameter immersed in a uniform crossflow at Re=120 and Pr=0.7 was numerically studied. We consider all possible arrangements of the two cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of heat transfer are noticed depending on how they are positioned, resulting in quantitative changes in heat transfer coefficients of both cylinders. Collecting all of the numerical results obtained, we propose a contour diagram for averaged Nusselt number for each of the two cylinders. The geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate heat transfer rates on two isothermal circular cylinders of equal diameter arbitrarily positioned in physical space with respect to the main flow direction. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse