Dépouillements

CO2 bubble absorption enhancement in methanol-based nanofluids / Jae Won Lee in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1727–1733 Titre : CO2 bubble absorption enhancement in methanol-based nanofluids Titre original : Amélioration de l'absorption des bulles de CO2 dans les nanofluides à base de méthanol Type de document : texte imprimé Auteurs : Jae Won Lee, Auteur ; Jung-Yeul Jung, Auteur ; Soon-Geul Lee, Auteur Année de publication : 2012 Article en page(s) : pp. 1727–1733 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Absorption  Enhancement  Bubble  Carbon  dioxide  Methanol  Particle Résumé : In this study, the nanoparticles (i.e. SiO2 and Al2O3 nanoparticles) and methanol are combined into SiO2/methanol and Al2O3/methanol nanofluids to enhance the CO2 absorption rate of the base fluid (methanol). The absorption experiments are performed in the bubble type absorber system equipped with mass flow controller (MFC), mass flow meter (MFM) and silica gel (which can remove the methanol vapor existing in the outlet gases). The parametric analysis on the effects of the particle species and concentrations on CO2 bubble absorption rate is carried out. The particle concentration ranges from 0.005 to 0.5 vol%. It is found that the CO2 absorption rate is enhanced up to 4.5% at 0.01 vol% of Al2O3/methanol nanofluids at 20 °C, and 5.6% at 0.01 vol% of SiO2/methanol nanofluids at −20 °C, respectively. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001915 [article] CO2 bubble absorption enhancement in methanol-based nanofluids = Amélioration de l'absorption des bulles de CO2 dans les nanofluides à base de méthanol [texte imprimé] / Jae Won Lee, Auteur ; Jung-Yeul Jung, Auteur ; Soon-Geul Lee, Auteur . - 2012 . - pp. 1727–1733. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1727–1733 Mots-clés : Absorption  Enhancement  Bubble  Carbon  dioxide  Methanol  Particle Résumé : In this study, the nanoparticles (i.e. SiO2 and Al2O3 nanoparticles) and methanol are combined into SiO2/methanol and Al2O3/methanol nanofluids to enhance the CO2 absorption rate of the base fluid (methanol). The absorption experiments are performed in the bubble type absorber system equipped with mass flow controller (MFC), mass flow meter (MFM) and silica gel (which can remove the methanol vapor existing in the outlet gases). The parametric analysis on the effects of the particle species and concentrations on CO2 bubble absorption rate is carried out. The particle concentration ranges from 0.005 to 0.5 vol%. It is found that the CO2 absorption rate is enhanced up to 4.5% at 0.01 vol% of Al2O3/methanol nanofluids at 20 °C, and 5.6% at 0.01 vol% of SiO2/methanol nanofluids at −20 °C, respectively. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001915

The effect of oil-droplet on bubble absorption performance in binary nanoemulsions / Young-Jin Kim in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1734–1740 Titre : The effect of oil-droplet on bubble absorption performance in binary nanoemulsions : Effet des gouttelettes d'huile sur la performance en terme d'absorption bullaire Titre original : Nanoémulsions binaires Type de document : texte imprimé Auteurs : Young-Jin Kim, Auteur ; Jin Ki Lee, Auteur ; Yong Tae Kang, Auteur Année de publication : 2012 Article en page(s) : pp. 1734–1740 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Binary  mixture  Ammonia–water  Absorption  system  Emulsion  Stability  Bubble Résumé : The objectives of this paper are to study the absorption characteristics of NH3 bubbles in binary nanoemulsions and to quantify the effect of oil-droplet on the bubble absorption performance. C12E4 and Tween20 are used as the surfactants and n-decane oil is added into NH3/H2O solution to make the binary nanoemulsion. The initial concentration of NH3/H2O solution and the concentration of oil are considered as the key parameters. The absorption rates are calculated by measuring the inlet and outlet mass flow rates per a given time period. In addition, the droplet size in the binary nanoemulsion is measured by the particle size analyzer (ELS-Z, OTSUKA ELECTRONICS). It is found that the effective absorption ratio for 2.0 vol% oil and 14.3 wt% NH3/H2O becomes 17% higher than that for the base fluid. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001824 [article] The effect of oil-droplet on bubble absorption performance in binary nanoemulsions = Nanoémulsions binaires : Effet des gouttelettes d'huile sur la performance en terme d'absorption bullaire [texte imprimé] / Young-Jin Kim, Auteur ; Jin Ki Lee, Auteur ; Yong Tae Kang, Auteur . - 2012 . - pp. 1734–1740. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1734–1740 Mots-clés : Binary  mixture  Ammonia–water  Absorption  system  Emulsion  Stability  Bubble Résumé : The objectives of this paper are to study the absorption characteristics of NH3 bubbles in binary nanoemulsions and to quantify the effect of oil-droplet on the bubble absorption performance. C12E4 and Tween20 are used as the surfactants and n-decane oil is added into NH3/H2O solution to make the binary nanoemulsion. The initial concentration of NH3/H2O solution and the concentration of oil are considered as the key parameters. The absorption rates are calculated by measuring the inlet and outlet mass flow rates per a given time period. In addition, the droplet size in the binary nanoemulsion is measured by the particle size analyzer (ELS-Z, OTSUKA ELECTRONICS). It is found that the effective absorption ratio for 2.0 vol% oil and 14.3 wt% NH3/H2O becomes 17% higher than that for the base fluid. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001824

An experimental and theoretical study of the influence of surfactant on the preparation and stability of ammonia-water nanofluids / Liu Yang in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1741–1748 Titre : An experimental and theoretical study of the influence of surfactant on the preparation and stability of ammonia-water nanofluids Titre original : Etude expérimentale et théorique sur l'influence d'agents tensio-actifs sur la préparation et la stabilité des nano-fluides à ammoniac / eau Type de document : texte imprimé Auteurs : Liu Yang, Auteur ; Kai Du, Auteur ; Xiaofeng Niu, Auteur Année de publication : 2012 Article en page(s) : pp. 1741–1748 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Absorption  Particle  Stability  Ammonia-water  Refrigerant Résumé : Two types of nanofluids are obtained by adding the mixture of carbon black nanoparticles with emulsifier OP-10, and Al2O3 nanoparticles with sodium dodecyl benzene sulfonate (SDBS) in the ammonia-water solution, respectively. The dispersion stability of the prepared nanofluids in different mass fractions of surfactants is investigated by the light absorbency ratio index methods. The results show that with the increase of mass fraction of surfactant, the stability of carbon black nanofluid is improved firstly and then is exacerbated, while the stability of Al2O3 nanofluid is exacerbated firstly, then is improved, and then is exacerbated again. The influences of surfactant on the stability of ammonia-water nanofluids abide by the monolayer adsorption theory or electric double layer adsorption theory. Finally, the theoretical surfactant mass fractions required in the preparation of ammonia-water nanofluids are calculated by simplifying the dispersion models and the results are in accordance with experimental results. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001526 [article] An experimental and theoretical study of the influence of surfactant on the preparation and stability of ammonia-water nanofluids = Etude expérimentale et théorique sur l'influence d'agents tensio-actifs sur la préparation et la stabilité des nano-fluides à ammoniac / eau [texte imprimé] / Liu Yang, Auteur ; Kai Du, Auteur ; Xiaofeng Niu, Auteur . - 2012 . - pp. 1741–1748. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1741–1748 Mots-clés : Absorption  Particle  Stability  Ammonia-water  Refrigerant Résumé : Two types of nanofluids are obtained by adding the mixture of carbon black nanoparticles with emulsifier OP-10, and Al2O3 nanoparticles with sodium dodecyl benzene sulfonate (SDBS) in the ammonia-water solution, respectively. The dispersion stability of the prepared nanofluids in different mass fractions of surfactants is investigated by the light absorbency ratio index methods. The results show that with the increase of mass fraction of surfactant, the stability of carbon black nanofluid is improved firstly and then is exacerbated, while the stability of Al2O3 nanofluid is exacerbated firstly, then is improved, and then is exacerbated again. The influences of surfactant on the stability of ammonia-water nanofluids abide by the monolayer adsorption theory or electric double layer adsorption theory. Finally, the theoretical surfactant mass fractions required in the preparation of ammonia-water nanofluids are calculated by simplifying the dispersion models and the results are in accordance with experimental results. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001526

Experimental performances of a LiBr-water absorption facility equipped with adiabatic absorber / G. Gutiérrez-Urueta in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1749–1759 Titre : Experimental performances of a LiBr-water absorption facility equipped with adiabatic absorber Titre original : Performance expérimentale d'une installation au LiBr /eau muni d'un absorbeur adiabatique Type de document : texte imprimé Auteurs : G. Gutiérrez-Urueta, Auteur ; P. Rodríguez, Auteur ; M. Venegas, Auteur Année de publication : 2012 Article en page(s) : pp. 1749–1759 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Absorption  system  Lithium  bromide  Chilled  water  Air  conditioning Résumé : A facility for experimental evaluation of innovative components forming part of a single effect LiBr–H2O adiabatic absorption chiller is described. Plate heat exchangers have been incorporated in the design. Two adiabatic absorber configurations, droplets and liquid sheets, were designed and tested and its performances parameters were experimentally determined. Evaporator limitations have been identified and included in the analysis. Liquid accumulation leads to overflow of refrigerant out of the evaporators. Some general observations, regarding particular operating conditions, are reported. The absorber performance has been characterized in terms of heat and mass transfer through the heat conductance and the effectiveness. The influence of the recirculation ratio is presented for both cases. The liquid sheet configuration has shown better evaluation parameters than droplets configuration. A significant reduction in the absorber size (up to 50%) as compared to using droplets is possible. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001885 [article] Experimental performances of a LiBr-water absorption facility equipped with adiabatic absorber = Performance expérimentale d'une installation au LiBr /eau muni d'un absorbeur adiabatique [texte imprimé] / G. Gutiérrez-Urueta, Auteur ; P. Rodríguez, Auteur ; M. Venegas, Auteur . - 2012 . - pp. 1749–1759. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1749–1759 Mots-clés : Absorption  system  Lithium  bromide  Chilled  water  Air  conditioning Résumé : A facility for experimental evaluation of innovative components forming part of a single effect LiBr–H2O adiabatic absorption chiller is described. Plate heat exchangers have been incorporated in the design. Two adiabatic absorber configurations, droplets and liquid sheets, were designed and tested and its performances parameters were experimentally determined. Evaporator limitations have been identified and included in the analysis. Liquid accumulation leads to overflow of refrigerant out of the evaporators. Some general observations, regarding particular operating conditions, are reported. The absorber performance has been characterized in terms of heat and mass transfer through the heat conductance and the effectiveness. The influence of the recirculation ratio is presented for both cases. The liquid sheet configuration has shown better evaluation parameters than droplets configuration. A significant reduction in the absorber size (up to 50%) as compared to using droplets is possible. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001885

Attempt of integration of a small commercial ammonia-water absorption refrigerator with a solar concentrator / A. Busso in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1760–1775 Titre : Attempt of integration of a small commercial ammonia-water absorption refrigerator with a solar concentrator : Experience and results Titre original : Tentative d'intégration d'un réfrigérateur commercial à absorption à ammoniac / eau de petite taille et d'un capteur solaire: expérience acquise et résultats Type de document : texte imprimé Auteurs : A. Busso, Auteur ; J. Franco, Auteur ; N. Sogari, Auteur Année de publication : 2012 Article en page(s) : pp. 1760–1775 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Ammonia  Absorption  system  Solar  refrigeration  Solar  concentration  Thermodynamic  property Résumé : The integration of a small commercial ammonia-water absorption refrigerator with a solar concentrator as heat source was analyzed theoretically and experimentally. Operation parameters of the fridge were determined by parametric fitting experimental data using a thermodynamic model of the cycle leading to a working pressure of 25 bar, weak and strong solution concentrations of 15% and 30% respectively and a COP of ∼0.18. As sold, the fridge can operate with a reduction in the electric power supply of up to 40%. Results showed that the Parabolic Concentrator (PC) used can deliver temperatures above 200 °C for almost 6 h with an average useful power delivery and efficiency of 530 W and 26% respectively. During laboratory test runs it was possible to hold the refrigeration cycle running in a very unstable regime despite the inappropriate heat distribution in the generator unit due to the lower temperature heat source used (220 °C). However, outdoor testing with the sun as energy source proved unsuccessful due to the higher heat losses that occur at the pipes connecting the PC with the fridge. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001770 [article] Attempt of integration of a small commercial ammonia-water absorption refrigerator with a solar concentrator = Tentative d'intégration d'un réfrigérateur commercial à absorption à ammoniac / eau de petite taille et d'un capteur solaire: expérience acquise et résultats : Experience and results [texte imprimé] / A. Busso, Auteur ; J. Franco, Auteur ; N. Sogari, Auteur . - 2012 . - pp. 1760–1775. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1760–1775 Mots-clés : Ammonia  Absorption  system  Solar  refrigeration  Solar  concentration  Thermodynamic  property Résumé : The integration of a small commercial ammonia-water absorption refrigerator with a solar concentrator as heat source was analyzed theoretically and experimentally. Operation parameters of the fridge were determined by parametric fitting experimental data using a thermodynamic model of the cycle leading to a working pressure of 25 bar, weak and strong solution concentrations of 15% and 30% respectively and a COP of ∼0.18. As sold, the fridge can operate with a reduction in the electric power supply of up to 40%. Results showed that the Parabolic Concentrator (PC) used can deliver temperatures above 200 °C for almost 6 h with an average useful power delivery and efficiency of 530 W and 26% respectively. During laboratory test runs it was possible to hold the refrigeration cycle running in a very unstable regime despite the inappropriate heat distribution in the generator unit due to the lower temperature heat source used (220 °C). However, outdoor testing with the sun as energy source proved unsuccessful due to the higher heat losses that occur at the pipes connecting the PC with the fridge. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001770

Waste heat driven absorption/vapor-compression cascade refrigeration system for megawatt scale, high-flux, low-temperature cooling / Srinivas Garimella in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1776–1785 Titre : Waste heat driven absorption/vapor-compression cascade refrigeration system for megawatt scale, high-flux, low-temperature cooling Titre original : Système frigorifique à absorption à compression de vapeur entraîné par la chaleur récupérée pour le refroidissement basse température à haut flux à l'échelle des mégawatts Type de document : texte imprimé Auteurs : Srinivas Garimella, Auteur ; Ashlie M. Brown, Auteur ; Ananda Krishna Nagavarapu, Auteur Année de publication : 2012 Article en page(s) : pp. 1776–1785 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Absorption  Mechanical  vapour  compression  Cascade  system  Refrigeration  Water  Lithium  bromide  Carbon  dioxide Résumé : A novel cascaded absorption/vapor-compression cycle with a high temperature lift for a naval ship application was conceptualized and analyzed. A single-effect LiBr–H2O absorption cycle and a subcritical CO2 vapor-compression cycle were coupled together to provide low-temperature refrigerant (−40 °C) for high heat flux electronics applications, medium-temperature refrigerant (5 °C) for space conditioning and other low heat flux applications, and as an auxiliary benefit, provide medium-temperature heat rejection (∼48 °C) for water heating applications. A thermodynamic model was developed to analyze the performance of the cascaded system, and parametric analyses were conducted to estimate the performance of the system over a range of operating conditions. The performance of the cascaded system was also compared with an equivalent two-stage vapor-compression cycle. This cycle was found to exhibit very high COPs over a wide range of operating conditions and when compared to an equivalent vapor-compression system, was found to avoid up to 31% electricity demand. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100123X [article] Waste heat driven absorption/vapor-compression cascade refrigeration system for megawatt scale, high-flux, low-temperature cooling = Système frigorifique à absorption à compression de vapeur entraîné par la chaleur récupérée pour le refroidissement basse température à haut flux à l'échelle des mégawatts [texte imprimé] / Srinivas Garimella, Auteur ; Ashlie M. Brown, Auteur ; Ananda Krishna Nagavarapu, Auteur . - 2012 . - pp. 1776–1785. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1776–1785 Mots-clés : Absorption  Mechanical  vapour  compression  Cascade  system  Refrigeration  Water  Lithium  bromide  Carbon  dioxide Résumé : A novel cascaded absorption/vapor-compression cycle with a high temperature lift for a naval ship application was conceptualized and analyzed. A single-effect LiBr–H2O absorption cycle and a subcritical CO2 vapor-compression cycle were coupled together to provide low-temperature refrigerant (−40 °C) for high heat flux electronics applications, medium-temperature refrigerant (5 °C) for space conditioning and other low heat flux applications, and as an auxiliary benefit, provide medium-temperature heat rejection (∼48 °C) for water heating applications. A thermodynamic model was developed to analyze the performance of the cascaded system, and parametric analyses were conducted to estimate the performance of the system over a range of operating conditions. The performance of the cascaded system was also compared with an equivalent two-stage vapor-compression cycle. This cycle was found to exhibit very high COPs over a wide range of operating conditions and when compared to an equivalent vapor-compression system, was found to avoid up to 31% electricity demand. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100123X

Characterization of desiccant wheels with alternative materials at low regeneration temperatures / Stephen D. White in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1786–1791 Titre : Characterization of desiccant wheels with alternative materials at low regeneration temperatures Titre original : Caractérisation des roues déshydratantes utilisant des matériaux innovants à des basses températures de régénération Type de document : texte imprimé Auteurs : Stephen D. White, Auteur ; Mark Goldsworthy, Auteur ; Roger Reece, Auteur Année de publication : 2012 Article en page(s) : pp. 1786–1791 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Desiccant  wheel  Dehumidification  Silica  gel  Polymer  Zeolite Résumé : A number of new desiccant materials have been proposed which have the potential to improve the performance of desiccant wheels being regenerated at low temperature. Desiccant wheels containing two such desiccant materials (zeolite and superadsorbent polymer) were compared with a conventional silica gel desiccant wheel. The superadsorbent polymer desiccant wheel achieved greater dehumidification than the silica gel wheel when dehumidifying high relative humidity air with low temperature (50 °C) regeneration air. The temperature of dehumidified air exiting the polymer wheel was also lower. The zeolite desiccant wheel was generally less effective at dehumidifying air and had a higher pressure drop. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001575 [article] Characterization of desiccant wheels with alternative materials at low regeneration temperatures = Caractérisation des roues déshydratantes utilisant des matériaux innovants à des basses températures de régénération [texte imprimé] / Stephen D. White, Auteur ; Mark Goldsworthy, Auteur ; Roger Reece, Auteur . - 2012 . - pp. 1786–1791. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1786–1791 Mots-clés : Desiccant  wheel  Dehumidification  Silica  gel  Polymer  Zeolite Résumé : A number of new desiccant materials have been proposed which have the potential to improve the performance of desiccant wheels being regenerated at low temperature. Desiccant wheels containing two such desiccant materials (zeolite and superadsorbent polymer) were compared with a conventional silica gel desiccant wheel. The superadsorbent polymer desiccant wheel achieved greater dehumidification than the silica gel wheel when dehumidifying high relative humidity air with low temperature (50 °C) regeneration air. The temperature of dehumidified air exiting the polymer wheel was also lower. The zeolite desiccant wheel was generally less effective at dehumidifying air and had a higher pressure drop. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001575

Design concepts for a continuously rotating active magnetic regenerator / C. R. H. Bahl in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1792–1796 Titre : Design concepts for a continuously rotating active magnetic regenerator Titre original : Concepts appliqués dans la conception d'un régénérateur actif magnétique en rotation continue Type de document : texte imprimé Auteurs : C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; R. Bjørk, Auteur Année de publication : 2012 Article en page(s) : pp. 1792–1796 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Magnet  Design  Optimization  Model Résumé : Design considerations for a prototype magnetic refrigeration device with a continuously rotating AMR are presented. Building the active magnetic regenerator (AMR) from stacks of elongated plates of the perovskite oxide material La0.67Ca0.33−xSrxMn1.05O3, gives both a low pressure drop and allows grading of the Curie temperature along the plates. This may be accomplished by a novel technique where a compositionally-graded material is tape cast in one piece. The magnet assembly is based on a novel design strategy, to create alternating high- and low magnetic field regions within a magnet assembly. Focus is on maximising the magnetic field in the high field regions but also, importantly, minimising the flux in the low field regions. The design is iteratively optimised through 3D finite element magnetostatic modelling. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001873 [article] Design concepts for a continuously rotating active magnetic regenerator = Concepts appliqués dans la conception d'un régénérateur actif magnétique en rotation continue [texte imprimé] / C. R. H. Bahl, Auteur ; K. Engelbrecht, Auteur ; R. Bjørk, Auteur . - 2012 . - pp. 1792–1796. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1792–1796 Mots-clés : Magnetic  refrigerator  Magnet  Design  Optimization  Model Résumé : Design considerations for a prototype magnetic refrigeration device with a continuously rotating AMR are presented. Building the active magnetic regenerator (AMR) from stacks of elongated plates of the perovskite oxide material La0.67Ca0.33−xSrxMn1.05O3, gives both a low pressure drop and allows grading of the Curie temperature along the plates. This may be accomplished by a novel technique where a compositionally-graded material is tape cast in one piece. The magnet assembly is based on a novel design strategy, to create alternating high- and low magnetic field regions within a magnet assembly. Focus is on maximising the magnetic field in the high field regions but also, importantly, minimising the flux in the low field regions. The design is iteratively optimised through 3D finite element magnetostatic modelling. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001873

Numerical analysis of an active magnetic regenerator / J. Roudaut in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1797–1804 Titre : Numerical analysis of an active magnetic regenerator Titre original : Analyse numérique d'un un régénérateur actif magnétique Type de document : texte imprimé Auteurs : J. Roudaut, Auteur ; A. Kedous-Lebouc, Auteur ; J.-P. Yonnet, Auteur Année de publication : 2012 Article en page(s) : pp. 1797–1804 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Gadolinium  Plate  exchanger  Modelling  Performance Résumé : A one-dimensional transient model of an active magnetic regenerator has been developed. The magnetocaloric properties are calculated using the Mean field theory and the model is used to study the transient and steady state response of a parallel plate regenerator. A parametric study is performed and highlights the influence of the Number of Transfer Units, the Utilization, and the solid axial conductivity. Finally the magnetic field inhomogeneity and the fluid axial conductivity are found to have no significant influence on the regenerator performance. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001861 [article] Numerical analysis of an active magnetic regenerator = Analyse numérique d'un un régénérateur actif magnétique [texte imprimé] / J. Roudaut, Auteur ; A. Kedous-Lebouc, Auteur ; J.-P. Yonnet, Auteur . - 2012 . - pp. 1797–1804. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1797–1804 Mots-clés : Magnetic  refrigerator  Gadolinium  Plate  exchanger  Modelling  Performance Résumé : A one-dimensional transient model of an active magnetic regenerator has been developed. The magnetocaloric properties are calculated using the Mean field theory and the model is used to study the transient and steady state response of a parallel plate regenerator. A parametric study is performed and highlights the influence of the Number of Transfer Units, the Utilization, and the solid axial conductivity. Finally the magnetic field inhomogeneity and the fluid axial conductivity are found to have no significant influence on the regenerator performance. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001861

Determining the minimum mass and cost of a magnetic refrigerator / R. Bjørk in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1805–1816 Titre : Determining the minimum mass and cost of a magnetic refrigerator Titre original : Détermination de la masse minimale et du coût d'un réfrigérateur magnétique Type de document : texte imprimé Auteurs : R. Bjørk, Auteur ; A. Smith, Auteur ; C. R. H. Bahl, Auteur Année de publication : 2012 Article en page(s) : pp. 1805–1816 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Regenerator  Magnetic  fieldModeling Résumé : An expression is determined for the mass of the magnet and magnetocaloric material needed for a magnetic refrigerator and these are determined using numerical modeling for both parallel plate and packed sphere bed regenerators as function of temperature span and cooling power. As magnetocaloric material Gd or a model material with a constant adiabatic temperature change, representing an infinitely linearly graded refrigeration device, is used. For the magnet a maximum figure of merit magnet or a Halbach cylinder is used. For a cost of $40 and $20 per kg for the magnet and magnetocaloric material, respectively, the cheapest 100 W parallel plate refrigerator with a temperature span of 20 K using Gd and a Halbach magnet has 0.8 kg of magnet, 0.3 kg of Gd and a cost of $35. Using the constant material reduces this cost to $25. A packed sphere bed refrigerator with the constant material costs $7. It is also shown that increasing the operation frequency reduces the cost. Finally, the lowest cost is also found as a function of the cost of the magnet and magnetocaloric material. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100140X [article] Determining the minimum mass and cost of a magnetic refrigerator = Détermination de la masse minimale et du coût d'un réfrigérateur magnétique [texte imprimé] / R. Bjørk, Auteur ; A. Smith, Auteur ; C. R. H. Bahl, Auteur . - 2012 . - pp. 1805–1816. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1805–1816 Mots-clés : Magnetic  refrigerator  Regenerator  Magnetic  fieldModeling Résumé : An expression is determined for the mass of the magnet and magnetocaloric material needed for a magnetic refrigerator and these are determined using numerical modeling for both parallel plate and packed sphere bed regenerators as function of temperature span and cooling power. As magnetocaloric material Gd or a model material with a constant adiabatic temperature change, representing an infinitely linearly graded refrigeration device, is used. For the magnet a maximum figure of merit magnet or a Halbach cylinder is used. For a cost of $40 and $20 per kg for the magnet and magnetocaloric material, respectively, the cheapest 100 W parallel plate refrigerator with a temperature span of 20 K using Gd and a Halbach magnet has 0.8 kg of magnet, 0.3 kg of Gd and a cost of $35. Using the constant material reduces this cost to $25. A packed sphere bed refrigerator with the constant material costs $7. It is also shown that increasing the operation frequency reduces the cost. Finally, the lowest cost is also found as a function of the cost of the magnet and magnetocaloric material. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100140X

An experimental study of passive regenerator geometries / K. Engelbrecht in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1817–1822 Titre : An experimental study of passive regenerator geometries Titre original : Etude expérimentale sur les géométries des régénérateurs passifs Type de document : texte imprimé Auteurs : K. Engelbrecht, Auteur ; K.K. Nielsen, Auteur ; N. Pryds, Auteur Année de publication : 2012 Article en page(s) : pp. 1817–1822 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Regenerator  Experimentation Résumé : Active magnetic regenerative (AMR) systems are being investigated because they represent a potentially attractive alternative to vapor compression technology. The performance of these systems is dependent on the heat transfer and pressure drop performance of the regenerator geometry. Therefore this article studies the effects of regenerator geometry on performance for flat plate regenerators. This paper investigates methods of improving the performance of flat plate regenerators for use in AMR systems and studies how manufacturing variation affects regenerator performance. In order to eliminate experimental uncertainty associated with magnetocaloric material properties, all regenerators are made of aluminum. The performance of corrugated plates and dimpled plates are compared to traditional flat plate regenerators for a range of cycle times and utilizations. Each regenerator is built using 18 aluminum plates with a 0.4 mm thickness, which allows their performance to be compared directly. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001897 [article] An experimental study of passive regenerator geometries = Etude expérimentale sur les géométries des régénérateurs passifs [texte imprimé] / K. Engelbrecht, Auteur ; K.K. Nielsen, Auteur ; N. Pryds, Auteur . - 2012 . - pp. 1817–1822. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1817–1822 Mots-clés : Magnetic  refrigerator  Regenerator  Experimentation Résumé : Active magnetic regenerative (AMR) systems are being investigated because they represent a potentially attractive alternative to vapor compression technology. The performance of these systems is dependent on the heat transfer and pressure drop performance of the regenerator geometry. Therefore this article studies the effects of regenerator geometry on performance for flat plate regenerators. This paper investigates methods of improving the performance of flat plate regenerators for use in AMR systems and studies how manufacturing variation affects regenerator performance. In order to eliminate experimental uncertainty associated with magnetocaloric material properties, all regenerators are made of aluminum. The performance of corrugated plates and dimpled plates are compared to traditional flat plate regenerators for a range of cycle times and utilizations. Each regenerator is built using 18 aluminum plates with a 0.4 mm thickness, which allows their performance to be compared directly. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001897

Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. / Peng, Hao in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1823–1832 Titre : Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. : Part I: Experimental measurement Titre original : Influences de la composition et le chauffage d'un nanofluide sur la migration des nanoparticules lors de l'ébullition libre. Partie I : mesures expérimentales Type de document : texte imprimé Auteurs : Peng, Hao, Auteur ; Guoliang Ding, Auteur ; Haitao Hu, Auteur Année de publication : 2012 Article en page(s) : pp. 1823–1832 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Heat  flux  Oil  Particle  Pool  boiling  Refrigerant Résumé : Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling were investigated experimentally. The nanoparticles include Cu (average diameters of 20, 50 and 80 nm), Al and Al2O3 (average diameters of 20 nm), and CuO (average diameter of 40 nm). The refrigerants include R113, R141b and n-pentane. The mass fraction of lubricating oil RB68EP is from 0 to 10 wt%, the heat flux is from 10 to 100 kW m−2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results show that the migration ratio of nanoparticles during the pool boiling of refrigerant-based nanofluid increases with the decrease of nanoparticle density, nanoparticle size, dynamic viscosity of refrigerant, mass fraction of lubricating oil or heat flux; while increases with the increase of liquid-phase density of refrigerant or initial liquid-level height. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001848 [article] Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. = Influences de la composition et le chauffage d'un nanofluide sur la migration des nanoparticules lors de l'ébullition libre. Partie I : mesures expérimentales : Part I: Experimental measurement [texte imprimé] / Peng, Hao, Auteur ; Guoliang Ding, Auteur ; Haitao Hu, Auteur . - 2012 . - pp. 1823–1832. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1823–1832 Mots-clés : Heat  flux  Oil  Particle  Pool  boiling  Refrigerant Résumé : Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling were investigated experimentally. The nanoparticles include Cu (average diameters of 20, 50 and 80 nm), Al and Al2O3 (average diameters of 20 nm), and CuO (average diameter of 40 nm). The refrigerants include R113, R141b and n-pentane. The mass fraction of lubricating oil RB68EP is from 0 to 10 wt%, the heat flux is from 10 to 100 kW m−2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results show that the migration ratio of nanoparticles during the pool boiling of refrigerant-based nanofluid increases with the decrease of nanoparticle density, nanoparticle size, dynamic viscosity of refrigerant, mass fraction of lubricating oil or heat flux; while increases with the increase of liquid-phase density of refrigerant or initial liquid-level height. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001848

Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. / Peng, Hao in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1833–1845 Titre : Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. : Part II: Model development and validation Titre original : Influences de la composition et le chauffage d'un nanofluide sur la migration des nanoparticules lors de l'ébullition libre. Partie II : développement et validation du modèle Type de document : texte imprimé Auteurs : Peng, Hao, Auteur ; Guoliang Ding, Auteur ; Haitao Hu, Auteur Année de publication : 2012 Article en page(s) : pp. 1833–1845 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Bubble  Liquid  Model  Particle  CFD  Vapor Résumé : The objective of this study is to propose a model for predicting the migration characteristics of nanoparticles during the refrigerant-based nanofluid pool boiling. In establishing the present model, the departure and rising processes of bubble, as well as the movement of nanoparticles in the liquid-phase are firstly simulated; then the capture of nanoparticles by bubble and the escape of nanoparticles from the liquid–vapor interface are simulated; finally, the migration ratio of nanoparticles is obtained by flotation theory combining the analysis on the boiling process. The proposed model can predict the influences of nanoparticle type, nanoparticle size, refrigerant type, mass fraction of lubricating oil, heat flux and initial liquid-level height on the migration of nanoparticles. The migration ratio of nanoparticles predicted by the model can agree with 90% of the experimental data of within a deviation of ±20%, and the mean deviation is 12.1%. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001836 [article] Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. = Influences de la composition et le chauffage d'un nanofluide sur la migration des nanoparticules lors de l'ébullition libre. Partie II : développement et validation du modèle : Part II: Model development and validation [texte imprimé] / Peng, Hao, Auteur ; Guoliang Ding, Auteur ; Haitao Hu, Auteur . - 2012 . - pp. 1833–1845. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1833–1845 Mots-clés : Bubble  Liquid  Model  Particle  CFD  Vapor Résumé : The objective of this study is to propose a model for predicting the migration characteristics of nanoparticles during the refrigerant-based nanofluid pool boiling. In establishing the present model, the departure and rising processes of bubble, as well as the movement of nanoparticles in the liquid-phase are firstly simulated; then the capture of nanoparticles by bubble and the escape of nanoparticles from the liquid–vapor interface are simulated; finally, the migration ratio of nanoparticles is obtained by flotation theory combining the analysis on the boiling process. The proposed model can predict the influences of nanoparticle type, nanoparticle size, refrigerant type, mass fraction of lubricating oil, heat flux and initial liquid-level height on the migration of nanoparticles. The migration ratio of nanoparticles predicted by the model can agree with 90% of the experimental data of within a deviation of ±20%, and the mean deviation is 12.1%. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001836

Boiling heat transfer of HFO-1234yf flowing in a smooth small-diameter horizontal tube / Shizuo Saitoh in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1846–1853 Titre : Boiling heat transfer of HFO-1234yf flowing in a smooth small-diameter horizontal tube Titre original : Transfert de chaleur lors de l’ébullition de HFO-1234yf à l’intérieur d’un tube horizontal lisse de faible diamètre Type de document : texte imprimé Auteurs : Shizuo Saitoh, Auteur ; Chaobin Dang, Auteur ; Yoshitaka Nakamura, Auteur Année de publication : 2012 Article en page(s) : pp. 1846–1853 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Boiling  Heat  transfer  Pressure  drop  HFO-1234yf  Tube  Small  diameter Résumé : The flow boiling heat transfer coefficient of the low-GWP (global warming potential) refrigerant HFO-1234yf inside a smooth small-diameter horizontal tube (inner diameter: 2 mm) was experimentally investigated. The local heat transfer coefficient was measured at heat fluxes of 6–24 kW m−2, mass fluxes of 100–400 kg m−2 s−1, an evaporating temperature of 288.15 K, and an inlet vapor quality of 0–0.25. The results show that the effect of heat flux on the heat transfer was large at low vapor quality, while the effect of mass flux was large at high vapor quality. The heat transfer coefficient of HFO-1234yf was almost the same as that of R-134a. The heat transfer coefficients calculated based on correlations with Saitoh et al. agreed well with the measured values compared to other correlations. The measured pressure drop agreed well with that predicted by the Lockhart–Martinelli correlation. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001241# [article] Boiling heat transfer of HFO-1234yf flowing in a smooth small-diameter horizontal tube = Transfert de chaleur lors de l’ébullition de HFO-1234yf à l’intérieur d’un tube horizontal lisse de faible diamètre [texte imprimé] / Shizuo Saitoh, Auteur ; Chaobin Dang, Auteur ; Yoshitaka Nakamura, Auteur . - 2012 . - pp. 1846–1853. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1846–1853 Mots-clés : Boiling  Heat  transfer  Pressure  drop  HFO-1234yf  Tube  Small  diameter Résumé : The flow boiling heat transfer coefficient of the low-GWP (global warming potential) refrigerant HFO-1234yf inside a smooth small-diameter horizontal tube (inner diameter: 2 mm) was experimentally investigated. The local heat transfer coefficient was measured at heat fluxes of 6–24 kW m−2, mass fluxes of 100–400 kg m−2 s−1, an evaporating temperature of 288.15 K, and an inlet vapor quality of 0–0.25. The results show that the effect of heat flux on the heat transfer was large at low vapor quality, while the effect of mass flux was large at high vapor quality. The heat transfer coefficient of HFO-1234yf was almost the same as that of R-134a. The heat transfer coefficients calculated based on correlations with Saitoh et al. agreed well with the measured values compared to other correlations. The measured pressure drop agreed well with that predicted by the Lockhart–Martinelli correlation. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001241#

Two-phase pressure drop in return bends / Miguel Padilla in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1854–1865 Titre : Two-phase pressure drop in return bends : Experimental results for R-410A Titre original : Chute de pression diphasique dans les coudes de retour : résultats expérimentaux obtenus avec le R-410A Type de document : texte imprimé Auteurs : Miguel Padilla, Auteur ; Rémi Revellin, Auteur ; Philippe Haberschill, Auteur Année de publication : 2012 Article en page(s) : pp. 1854–1865 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Two-phase  flow  Pressure  drop  Refrigerant  Experimentation Résumé : This study presents 238 pressure drop data points measured for two-phase flow of R-410A in horizontal return bends. The tube diameter (D) varies from 7.90 to 10.85 mm and the curvature ratio (2R/D) from 3.68 to 4.05. The mass velocity ranges from 179 to 1695 kg m−2 s−1 and the saturation temperatures from 4.6 °C to 20.7 °C. Preliminary tests show that the recovery length necessary for a correct pressure drop measurement downstream of the return bend is less than 20D, for the experimental conditions covered in this study. The singular pressure drop is determined by subtracting the regular pressure drop in straight tube from the total pressure drop. The experimental data are compared against four available correlations found in the literature. The present experimental database for the return bend pressure drop is presented in the Appendix A. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000727 [article] Two-phase pressure drop in return bends = Chute de pression diphasique dans les coudes de retour : résultats expérimentaux obtenus avec le R-410A : Experimental results for R-410A [texte imprimé] / Miguel Padilla, Auteur ; Rémi Revellin, Auteur ; Philippe Haberschill, Auteur . - 2012 . - pp. 1854–1865. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1854–1865 Mots-clés : Two-phase  flow  Pressure  drop  Refrigerant  Experimentation Résumé : This study presents 238 pressure drop data points measured for two-phase flow of R-410A in horizontal return bends. The tube diameter (D) varies from 7.90 to 10.85 mm and the curvature ratio (2R/D) from 3.68 to 4.05. The mass velocity ranges from 179 to 1695 kg m−2 s−1 and the saturation temperatures from 4.6 °C to 20.7 °C. Preliminary tests show that the recovery length necessary for a correct pressure drop measurement downstream of the return bend is less than 20D, for the experimental conditions covered in this study. The singular pressure drop is determined by subtracting the regular pressure drop in straight tube from the total pressure drop. The experimental data are compared against four available correlations found in the literature. The present experimental database for the return bend pressure drop is presented in the Appendix A. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000727

A unified approach to predict evaporation losses in evaporative heat exchangers / Bilal Ahmed Qureshi in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1866–1876 Titre : A unified approach to predict evaporation losses in evaporative heat exchangers Titre original : Approche unifiée de la prévision des pertes par évaporation dans les échangeurs de chaleur évaporatifs Type de document : texte imprimé Auteurs : Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur Année de publication : 2012 Article en page(s) : pp. 1866–1876 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Evaporative  heat  exchanger  Evaporation  Correlation  Prediction Résumé : In this paper, the rules of thumb used to predict evaporation losses in different evaporative heat exchangers are unified. The accurate prediction of all aspects of evaporative heat exchanger behavior is very important. Accurately predicting evaporation losses is significant since water, in this class of heat exchangers, is cooled primarily by evaporation of a portion of the circulating water that causes the concentration of impurities to increase. Furthermore, the design of hybrid cooling towers requires that the amount of evaporation be known. A single correlation is, therefore, developed for this class of heat exchangers that is simple and accurate with a wide range of applicability. The predicted values are in good agreement with experimental values as well as predictions made by reliable mathematical models. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001538# [article] A unified approach to predict evaporation losses in evaporative heat exchangers = Approche unifiée de la prévision des pertes par évaporation dans les échangeurs de chaleur évaporatifs [texte imprimé] / Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur . - 2012 . - pp. 1866–1876. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1866–1876 Mots-clés : Evaporative  heat  exchanger  Evaporation  Correlation  Prediction Résumé : In this paper, the rules of thumb used to predict evaporation losses in different evaporative heat exchangers are unified. The accurate prediction of all aspects of evaporative heat exchanger behavior is very important. Accurately predicting evaporation losses is significant since water, in this class of heat exchangers, is cooled primarily by evaporation of a portion of the circulating water that causes the concentration of impurities to increase. Furthermore, the design of hybrid cooling towers requires that the amount of evaporation be known. A single correlation is, therefore, developed for this class of heat exchangers that is simple and accurate with a wide range of applicability. The predicted values are in good agreement with experimental values as well as predictions made by reliable mathematical models. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001538#

Mathematical analysis for the efficiency of a semi-spherical fin with simultaneous heat and mass transfer / S. Sabbaghi in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1877–1882 Titre : Mathematical analysis for the efficiency of a semi-spherical fin with simultaneous heat and mass transfer Titre original : Analyse mathématique de l'efficacité d'une ailette semi-sphérique avec transfert de chaleur et de masse simultanés Type de document : texte imprimé Auteurs : S. Sabbaghi, Auteur ; A. Rezaii, Auteur ; Gh.R. Shahri, Auteur Année de publication : 2012 Article en page(s) : pp. 1877–1882 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Fin  Semi-spherical  Efficiency  Heat  transfer  Mass  transfer  Simulation Résumé : In this paper an analytical solution for the efficiency of a semi-spherical fin when subjected to simultaneous heat and mass transfer mechanisms is studied. For the mathematical analysis of a wet fin equation, a relationship between humidity ratio and temperature of the saturation air is needed. The driving forces for the heat and mass transfer are the temperature and humidity ratio differences, respectively. Analytical solutions are obtained for the temperature distribution over the fin surface when the fin is fully wet. It is observed that in humid conditions the fin has high efficiency to be used in industry. The variation effects of these parameters have been considered. Finally linear relation has been proposed for humidity and temperature on the fin surface. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001599 [article] Mathematical analysis for the efficiency of a semi-spherical fin with simultaneous heat and mass transfer = Analyse mathématique de l'efficacité d'une ailette semi-sphérique avec transfert de chaleur et de masse simultanés [texte imprimé] / S. Sabbaghi, Auteur ; A. Rezaii, Auteur ; Gh.R. Shahri, Auteur . - 2012 . - pp. 1877–1882. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1877–1882 Mots-clés : Fin  Semi-spherical  Efficiency  Heat  transfer  Mass  transfer  Simulation Résumé : In this paper an analytical solution for the efficiency of a semi-spherical fin when subjected to simultaneous heat and mass transfer mechanisms is studied. For the mathematical analysis of a wet fin equation, a relationship between humidity ratio and temperature of the saturation air is needed. The driving forces for the heat and mass transfer are the temperature and humidity ratio differences, respectively. Analytical solutions are obtained for the temperature distribution over the fin surface when the fin is fully wet. It is observed that in humid conditions the fin has high efficiency to be used in industry. The variation effects of these parameters have been considered. Finally linear relation has been proposed for humidity and temperature on the fin surface. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001599

Simulation of air-to-refrigerant fin-and-tube heat exchanger with CFD-based air propagation / Varun Singh in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1883–1897 Titre : Simulation of air-to-refrigerant fin-and-tube heat exchanger with CFD-based air propagation Titre original : Simulation d'un échangeur de chaleur air-frigorigène à tubes ailetés à l'aide de la propagation d'air et de la mécanique numérique des fluides Type de document : texte imprimé Auteurs : Varun Singh, Auteur ; Omar Abdelaziz, Auteur ; Vikrant Aute, Auteur Année de publication : 2012 Article en page(s) : pp. 1883–1897 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Condenser  Modeling  Finned  tube  CFD  Hybrid  Simulation Résumé : A new model for simulating air-to-refrigerant fin-and-tube heat exchangers with computational fluid dynamics (CFD)-based air propagation is introduced. This model is based on a segment-by-segment approach and is developed to be a general purpose and flexible simulation tool. The model superimposes a CFD mesh on the heat exchanger model’s geometric grid, interprets the CFD results, and processes them to generate the air propagation path through the heat exchanger. The model is capable of accounting for air flow maldistribution and other complex flow patterns including recirculation zones within the heat exchanger, as well as, entrainment of exit flow into the heat exchanger, using both two-dimensional (2D) and three-dimensional (3D) CFD results. The modeling results show that the overall predicted heat load using 3D-CFD simulation results agrees within ±4% of the experimental data, without employing any multipliers on air side correlations. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001812 [article] Simulation of air-to-refrigerant fin-and-tube heat exchanger with CFD-based air propagation = Simulation d'un échangeur de chaleur air-frigorigène à tubes ailetés à l'aide de la propagation d'air et de la mécanique numérique des fluides [texte imprimé] / Varun Singh, Auteur ; Omar Abdelaziz, Auteur ; Vikrant Aute, Auteur . - 2012 . - pp. 1883–1897. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1883–1897 Mots-clés : Heat  exchanger  Condenser  Modeling  Finned  tube  CFD  Hybrid  Simulation Résumé : A new model for simulating air-to-refrigerant fin-and-tube heat exchangers with computational fluid dynamics (CFD)-based air propagation is introduced. This model is based on a segment-by-segment approach and is developed to be a general purpose and flexible simulation tool. The model superimposes a CFD mesh on the heat exchanger model’s geometric grid, interprets the CFD results, and processes them to generate the air propagation path through the heat exchanger. The model is capable of accounting for air flow maldistribution and other complex flow patterns including recirculation zones within the heat exchanger, as well as, entrainment of exit flow into the heat exchanger, using both two-dimensional (2D) and three-dimensional (3D) CFD results. The modeling results show that the overall predicted heat load using 3D-CFD simulation results agrees within ±4% of the experimental data, without employing any multipliers on air side correlations. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001812

Impact of classical assumptions in modelling a microchannel gas cooler / Santiago Martínez-Ballester in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1898–1910 Titre : Impact of classical assumptions in modelling a microchannel gas cooler Titre original : Impact des hypothèses classiques sur la modélisation d'un refroidisseur de gaz à microcanaux Type de document : texte imprimé Auteurs : Santiago Martínez-Ballester, Auteur ; José-M. Corberán, Auteur ; José Gonzálvez-Maciá, Auteur Année de publication : 2012 Article en page(s) : pp. 1898–1910 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Modelling  Simulation  Microchannel  Fin  Gas  cooler Résumé : Most of the current air-to-refrigerant heat exchanger models use the classic ɛ-NTU approach, or some of its assumptions. These models do not account for longitudinal heat conduction in the tube and the fin, and the heat conduction between different tubes. This paper presents a more fundamental numerical approach to heat exchanger modelling which takes into account the 2D longitudinal heat conduction in any element, does not apply the fin theory, and captures a more detailed representation of air properties. Using the fundamental numerical approach, the paper assesses the impact of the traditional heat exchanger model assumptions when modelling a microchannel gas cooler working with CO2. The study revealed significant differences in capacity predictions depending on the ɛ-NTU relationship adopted. Large errors in capacity prediction of individual tubes occurred due to the adiabatic-fin-tip assumption when the neighbouring tubes were of different temperature. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001782# [article] Impact of classical assumptions in modelling a microchannel gas cooler = Impact des hypothèses classiques sur la modélisation d'un refroidisseur de gaz à microcanaux [texte imprimé] / Santiago Martínez-Ballester, Auteur ; José-M. Corberán, Auteur ; José Gonzálvez-Maciá, Auteur . - 2012 . - pp. 1898–1910. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1898–1910 Mots-clés : Heat  exchanger  Modelling  Simulation  Microchannel  Fin  Gas  cooler Résumé : Most of the current air-to-refrigerant heat exchanger models use the classic ɛ-NTU approach, or some of its assumptions. These models do not account for longitudinal heat conduction in the tube and the fin, and the heat conduction between different tubes. This paper presents a more fundamental numerical approach to heat exchanger modelling which takes into account the 2D longitudinal heat conduction in any element, does not apply the fin theory, and captures a more detailed representation of air properties. Using the fundamental numerical approach, the paper assesses the impact of the traditional heat exchanger model assumptions when modelling a microchannel gas cooler working with CO2. The study revealed significant differences in capacity predictions depending on the ɛ-NTU relationship adopted. Large errors in capacity prediction of individual tubes occurred due to the adiabatic-fin-tip assumption when the neighbouring tubes were of different temperature. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001782#

Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique / Chul Woo Roh in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1911–1921 Titre : Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique Titre original : Effets de la pression intermédiaire sur la performance en mode chauffage d'un système à pompe à chaleur utilisant une technologie à injection de vapeur de R410A Type de document : texte imprimé Auteurs : Chul Woo Roh, Auteur ; Min Soo Kim, Auteur Année de publication : 2012 Article en page(s) : pp. 1911–1921 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : COP  Experimentation  Heat  pump  Injection  Performance  R410A Résumé : Recent heat pumps are actively equipped with a refrigerant vapor-injection technique to acquire better performance in severe operating conditions. In this study, the target system which has an additional expansion valve at the outlet of condenser was presented. The concept of intermediate pressure was generated in the target system. Effects of the intermediate pressure on the heating performance with various injection ratios were measured and analyzed according to the compressor frequencies ranging from 60 to 100 Hz. Unlike conventional vapor-injection cycle, the maximum injection ratio was highly affected by the intermediate pressure. The high intermediate pressure provided high initial heating capacity and COP; but it restricted the available range of vapor-injection within narrow limits. The result indicates that a proper operating strategy is needed for the vapor-injection cycle. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100185X# [article] Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique = Effets de la pression intermédiaire sur la performance en mode chauffage d'un système à pompe à chaleur utilisant une technologie à injection de vapeur de R410A [texte imprimé] / Chul Woo Roh, Auteur ; Min Soo Kim, Auteur . - 2012 . - pp. 1911–1921. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1911–1921 Mots-clés : COP  Experimentation  Heat  pump  Injection  Performance  R410A Résumé : Recent heat pumps are actively equipped with a refrigerant vapor-injection technique to acquire better performance in severe operating conditions. In this study, the target system which has an additional expansion valve at the outlet of condenser was presented. The concept of intermediate pressure was generated in the target system. Effects of the intermediate pressure on the heating performance with various injection ratios were measured and analyzed according to the compressor frequencies ranging from 60 to 100 Hz. Unlike conventional vapor-injection cycle, the maximum injection ratio was highly affected by the intermediate pressure. The high intermediate pressure provided high initial heating capacity and COP; but it restricted the available range of vapor-injection within narrow limits. The result indicates that a proper operating strategy is needed for the vapor-injection cycle. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100185X#

Transient and steady-state experimental investigation of flash tank vapor injection heat pump cycle control strategy / Xing Xu in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1922–1933 Titre : Transient and steady-state experimental investigation of flash tank vapor injection heat pump cycle control strategy Titre original : Etude expérimentale en régime transitoire et permanent de la stratégie de régulation appliquée à un cycle à pompe à chaleur avec injection de vapeur du réservoir intermédiaire Type de document : texte imprimé Auteurs : Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2012 Article en page(s) : pp. 1922–1933 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Tank  Injection  Transient  state  Steady  state  Control Résumé : Recent research on vapor injection technique has been mostly focused on performance improvement using different system configurations. The flash tank cycle typically shows better performance than the internal heat exchanger cycle. However, the flash tank cycle control strategy is not yet clearly defined. In this study, a novel cycle control strategy is proposed for an R-410A vapor injection flash tank heat pump system and its feasibility was experimentally investigated. The proposed novel cycle control strategy utilized an electronic expansion valve (EEV) for the upper-stage expansion and a thermostatic expansion valve for the lower-stage expansion, and applied an electric heater in the vapor injection line to introduce superheat to the injected vapor by providing a control signal to the upper-stage EEV. Both transient and steady-state system behaviors were studied. The proposed cycle control strategy was found to be able to provide reliable control to the system. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001927# [article] Transient and steady-state experimental investigation of flash tank vapor injection heat pump cycle control strategy = Etude expérimentale en régime transitoire et permanent de la stratégie de régulation appliquée à un cycle à pompe à chaleur avec injection de vapeur du réservoir intermédiaire [texte imprimé] / Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2012 . - pp. 1922–1933. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1922–1933 Mots-clés : Tank  Injection  Transient  state  Steady  state  Control Résumé : Recent research on vapor injection technique has been mostly focused on performance improvement using different system configurations. The flash tank cycle typically shows better performance than the internal heat exchanger cycle. However, the flash tank cycle control strategy is not yet clearly defined. In this study, a novel cycle control strategy is proposed for an R-410A vapor injection flash tank heat pump system and its feasibility was experimentally investigated. The proposed novel cycle control strategy utilized an electronic expansion valve (EEV) for the upper-stage expansion and a thermostatic expansion valve for the lower-stage expansion, and applied an electric heater in the vapor injection line to introduce superheat to the injected vapor by providing a control signal to the upper-stage EEV. Both transient and steady-state system behaviors were studied. The proposed cycle control strategy was found to be able to provide reliable control to the system. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001927#

Capacity control in ground source heat pump systems part II: / Hatef Madani in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1934–1942 Titre : Capacity control in ground source heat pump systems part II: : Comparative analysis between on/off controlled and variable capacity systems Titre original : Régulation de la puissance des pompes à chaleur sol-eau. Partie II : analyse comparative des systèmes régulés de façon tout ou rien et des systèmes à puissance variable Type de document : texte imprimé Auteurs : Hatef Madani, Auteur ; Joachim Claesson, Auteur ; Per Lundqvist, Auteur Année de publication : 2012 Article en page(s) : pp. 1934–1942 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Control  Modelling  Simulation  Variable  speed Résumé : In the present paper, as the second part of two, modeling and simulation was carried out for a Ground Source Heat Pump (GSHP) system in the presence of all the most important interacting sub-systems such as building, ground heat source, electrical auxiliary heater, and the heat pump unit in order to make a fair and comprehensive comparison between the annual performance of on/off controlled and variable capacity systems. The annual modeling showed that dimensioning of the on/off controlled GSHP based on the peak heat demand of the building plays a significant role when the two control strategies are compared: if the on/off controlled GSHP is dimensioned to cover only 55% of the peak heat demand of the building, the electrical auxiliary, which then covers about 10% of the annual heating demand of the building, makes the SPF of the on/off controlled GSHP to be lower than the one of the variable speed system. On the contrary, when the on/off controlled system is dimensioned to cover more than 65% of the building’s peak heat demand, i.e. more than 95% of the annual heat demand of the building, there is no considerable difference between the SPFs of the on/off controlled and variable capacity systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001186 [article] Capacity control in ground source heat pump systems part II: = Régulation de la puissance des pompes à chaleur sol-eau. Partie II : analyse comparative des systèmes régulés de façon tout ou rien et des systèmes à puissance variable : Comparative analysis between on/off controlled and variable capacity systems [texte imprimé] / Hatef Madani, Auteur ; Joachim Claesson, Auteur ; Per Lundqvist, Auteur . - 2012 . - pp. 1934–1942. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1934–1942 Mots-clés : Heat  pump  Control  Modelling  Simulation  Variable  speed Résumé : In the present paper, as the second part of two, modeling and simulation was carried out for a Ground Source Heat Pump (GSHP) system in the presence of all the most important interacting sub-systems such as building, ground heat source, electrical auxiliary heater, and the heat pump unit in order to make a fair and comprehensive comparison between the annual performance of on/off controlled and variable capacity systems. The annual modeling showed that dimensioning of the on/off controlled GSHP based on the peak heat demand of the building plays a significant role when the two control strategies are compared: if the on/off controlled GSHP is dimensioned to cover only 55% of the peak heat demand of the building, the electrical auxiliary, which then covers about 10% of the annual heating demand of the building, makes the SPF of the on/off controlled GSHP to be lower than the one of the variable speed system. On the contrary, when the on/off controlled system is dimensioned to cover more than 65% of the building’s peak heat demand, i.e. more than 95% of the annual heat demand of the building, there is no considerable difference between the SPFs of the on/off controlled and variable capacity systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001186

Energetic and exergetic performance analysis of Bethe-Zeldovich-Thompson (BZT) fluids in geothermal heat pumps / Oznur Ozcan in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1943–1952 Titre : Energetic and exergetic performance analysis of Bethe-Zeldovich-Thompson (BZT) fluids in geothermal heat pumps Titre original : Performance énergétique et exergétique des fluides de Bethe-Zeldovich-Thompson (BZT) utilisés pour les pompes à chaleur géothermiques Type de document : texte imprimé Auteurs : Oznur Ozcan, Auteur ; Onder Ozgener, Auteur Année de publication : 2012 Article en page(s) : pp. 1943–1952 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : COP  Energy  Exergy  Heat  pump  Refrigerant Résumé : This study highlights theoretical energetic and exergetic performance evaluation results of Bethe-Zeldovich-Thompson (BZT) fluids in geothermal heat pumps. In this study, hexafluoroethane (R116), octafluoropropane (R218), and octafluorocyclobutane (RC318) were selected as possible alternative replacements to the traditional refrigerants in geothermal heat pumps. According to the calculations, coefficient of performance of 101 kW geothermal heat pumps (COPHP) changes with range between 3.84, 3.08, and 2.92 for octafluorocyclobutane (RC318), hexafluoroethane (R116), and octafluoropropane (R218), respectively. Moreover, R116 shows the maximum exergy efficiency 68% among the selected BZT fluids. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001381 [article] Energetic and exergetic performance analysis of Bethe-Zeldovich-Thompson (BZT) fluids in geothermal heat pumps = Performance énergétique et exergétique des fluides de Bethe-Zeldovich-Thompson (BZT) utilisés pour les pompes à chaleur géothermiques [texte imprimé] / Oznur Ozcan, Auteur ; Onder Ozgener, Auteur . - 2012 . - pp. 1943–1952. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1943–1952 Mots-clés : COP  Energy  Exergy  Heat  pump  Refrigerant Résumé : This study highlights theoretical energetic and exergetic performance evaluation results of Bethe-Zeldovich-Thompson (BZT) fluids in geothermal heat pumps. In this study, hexafluoroethane (R116), octafluoropropane (R218), and octafluorocyclobutane (RC318) were selected as possible alternative replacements to the traditional refrigerants in geothermal heat pumps. According to the calculations, coefficient of performance of 101 kW geothermal heat pumps (COPHP) changes with range between 3.84, 3.08, and 2.92 for octafluorocyclobutane (RC318), hexafluoroethane (R116), and octafluoropropane (R218), respectively. Moreover, R116 shows the maximum exergy efficiency 68% among the selected BZT fluids. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001381

Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (first report: Flow characteristics) / Hiroyuki Kumano in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1953–1962 Titre : Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (first report: Flow characteristics) Titre original : Etude expérimentale sur les caractéristiques d’écoulement et de transfert de chaleur d’un coulis de hydrate de bromure de tétra-n-butylammonium Type de document : texte imprimé Auteurs : Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Tomoya Kudoh, Auteur Année de publication : 2012 Article en page(s) : pp. 1953–1962 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Hydrate  Two-phase  flow  Pressure  drop  Non-Newtonian  fluid Résumé : The flow characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated experimentally. Reynolds number, tube diameter and solid fraction were varied as the experimental parameters. For laminar flow, it was found that the ratio of the coefficients of pipe friction increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of pipe friction was approximately 1 for all tube diameters at low solids fraction. It then decreased slightly at a particular solid fraction and increased again at high solid fraction. Theoretical analysis was carried out using the experimental results, and it was found that the flow characteristics of the hydrate slurry can be treated as those of a pseudoplastic fluid and clarified using the apparent Reynolds number. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001423 [article] Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (first report: Flow characteristics) = Etude expérimentale sur les caractéristiques d’écoulement et de transfert de chaleur d’un coulis de hydrate de bromure de tétra-n-butylammonium [texte imprimé] / Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Tomoya Kudoh, Auteur . - 2012 . - pp. 1953–1962. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1953–1962 Mots-clés : Hydrate  Two-phase  flow  Pressure  drop  Non-Newtonian  fluid Résumé : The flow characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated experimentally. Reynolds number, tube diameter and solid fraction were varied as the experimental parameters. For laminar flow, it was found that the ratio of the coefficients of pipe friction increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of pipe friction was approximately 1 for all tube diameters at low solids fraction. It then decreased slightly at a particular solid fraction and increased again at high solid fraction. Theoretical analysis was carried out using the experimental results, and it was found that the flow characteristics of the hydrate slurry can be treated as those of a pseudoplastic fluid and clarified using the apparent Reynolds number. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001423

Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (second report: Heat transfer characteristics) / Hiroyuki Kumano in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1963–1971 Titre : Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (second report: Heat transfer characteristics) Titre original : Etude expérimentale sur les caractéristiques d'écoulement et de transfert de chaleur d'un coulis de hydrate de bromure de tétra-n-butylammonium (deuxième partie : caractéristiques du transfert de chaleur) Type de document : texte imprimé Auteurs : Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Tomoya Kudoh, Auteur Année de publication : 2012 Article en page(s) : pp. 1963–1971 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Hydrate  Two-phase  flow  Heat  transfer  Non-newtonian  fluid Résumé : The heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated where the Reynolds number, tube diameters and solid fraction were varied as experimental parameters. For laminar flow, it was found that the ratio of Nusselt numbers increased with solid fraction. An approximation of Nusselt number could be derived using the Graetz number on the basis of the apparent Reynolds number, the solid fraction and the ratio of the average diameter of the hydrate particles to the test tube diameter. For turbulent flow conditions, the ratio of Nusselt numbers had a value of one for each condition at low solid fractions. The ratio of Nusselt numbers increased with solid fraction in the high solid fraction region. Moreover, the apparent Reynolds number, which can be derived by treating the hydrate slurry as a pseudoplastic fluid, can be used to determine the condition under which hydrate slurry heat transfer characteristics vary under turbulent flow. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001435 [article] Experimental study on the flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry (second report: Heat transfer characteristics) = Etude expérimentale sur les caractéristiques d'écoulement et de transfert de chaleur d'un coulis de hydrate de bromure de tétra-n-butylammonium (deuxième partie : caractéristiques du transfert de chaleur) [texte imprimé] / Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Tomoya Kudoh, Auteur . - 2012 . - pp. 1963–1971. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1963–1971 Mots-clés : Hydrate  Two-phase  flow  Heat  transfer  Non-newtonian  fluid Résumé : The heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated where the Reynolds number, tube diameters and solid fraction were varied as experimental parameters. For laminar flow, it was found that the ratio of Nusselt numbers increased with solid fraction. An approximation of Nusselt number could be derived using the Graetz number on the basis of the apparent Reynolds number, the solid fraction and the ratio of the average diameter of the hydrate particles to the test tube diameter. For turbulent flow conditions, the ratio of Nusselt numbers had a value of one for each condition at low solid fractions. The ratio of Nusselt numbers increased with solid fraction in the high solid fraction region. Moreover, the apparent Reynolds number, which can be derived by treating the hydrate slurry as a pseudoplastic fluid, can be used to determine the condition under which hydrate slurry heat transfer characteristics vary under turbulent flow. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001435

Ultrasonic determination of the particle concentration in model suspensions and ice slurry / V. Langlois in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1972–1979 Titre : Ultrasonic determination of the particle concentration in model suspensions and ice slurry Titre original : Détermination à l’aide d’ultrasons de la concentration des particules dans les suspensions et les coulis de glace modélisés Type de document : texte imprimé Auteurs : V. Langlois, Auteur ; W. Gautherin, Auteur ; J. Laurent, Auteur Année de publication : 2012 Article en page(s) : pp. 1972–1979 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Ultrasound  Sound  velocity  Concentration  Ice  slurry Résumé : The development of ice slurry for refrigeration systems and the enhancement of its efficiency depend on an accurate control of the ice concentration. We present here an ultrasonic method capable to measure precisely the particle concentration in ice slurry. To calibrate the ultrasonic measurement, we first determine the sound velocity and attenuation in two model suspensions (glass beads/polyethylene glycol and polyethylene beads/vaseline oil) for different particle volume fractions. The experimental results show a good agreement with the predictions of the two-component models in the long-wavelength limit. Additionally, the sound attenuation reveals a clear signature of the aggregate formation in the nearly iso-dense suspension. We next conduct the measurement of the sound velocity in the polypropylene glycol ice slurry where the ice concentration changes with temperature. The ice concentrations extracted from our sound velocity measurements are well consistent with the values determined from the binary phase diagram. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100154X [article] Ultrasonic determination of the particle concentration in model suspensions and ice slurry = Détermination à l’aide d’ultrasons de la concentration des particules dans les suspensions et les coulis de glace modélisés [texte imprimé] / V. Langlois, Auteur ; W. Gautherin, Auteur ; J. Laurent, Auteur . - 2012 . - pp. 1972–1979. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1972–1979 Mots-clés : Ultrasound  Sound  velocity  Concentration  Ice  slurry Résumé : The development of ice slurry for refrigeration systems and the enhancement of its efficiency depend on an accurate control of the ice concentration. We present here an ultrasonic method capable to measure precisely the particle concentration in ice slurry. To calibrate the ultrasonic measurement, we first determine the sound velocity and attenuation in two model suspensions (glass beads/polyethylene glycol and polyethylene beads/vaseline oil) for different particle volume fractions. The experimental results show a good agreement with the predictions of the two-component models in the long-wavelength limit. Additionally, the sound attenuation reveals a clear signature of the aggregate formation in the nearly iso-dense suspension. We next conduct the measurement of the sound velocity in the polypropylene glycol ice slurry where the ice concentration changes with temperature. The ice concentrations extracted from our sound velocity measurements are well consistent with the values determined from the binary phase diagram. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100154X

A novel revolving vane compressor with a fixed-vane / K.M. Tan in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1980–1988 Titre : A novel revolving vane compressor with a fixed-vane Titre original : Nouveau compresseur rotatif à palettes muni d'une palette fixe Type de document : texte imprimé Auteurs : K.M. Tan, Auteur ; K.T. Ooi, Auteur Année de publication : 2012 Article en page(s) : pp. 1980–1988 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Design  Rotary  compressor  Efficiency  Friction Résumé : This paper presents design improvements of a Revolving Vane (RV) compressor which significantly reduce the frictional losses. The original RV compressor has a vane that swivels during the operation. Though in general, the frictional losses of the RV compressor are significantly lower than most currently available rotary compressors, this swivel vane design has a disadvantage of relatively high vane side friction loss. The latter is caused by a high vane-side and slot contact force due to a high gas pressure differential force across the vane. In this paper, a new design concept has been introduced to totally eliminate the vane side friction loss caused by the gas pressure differential force across the vane. This is achieved by rigidly fixes the vane onto the rotor or the cylinder. This new design yielded two possible variants, each reduces the frictional losses by 18% and 41% and improves the mechanical efficiency from 93% to 94% and 96% respectively. In this paper, details analysis on the new design that leads to the improvement in performance are presented and shown. The analysis also reveals that the design with the highest mechanical efficiency comes with a small price of a higher instantaneous peak torque requirement. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001551 [article] A novel revolving vane compressor with a fixed-vane = Nouveau compresseur rotatif à palettes muni d'une palette fixe [texte imprimé] / K.M. Tan, Auteur ; K.T. Ooi, Auteur . - 2012 . - pp. 1980–1988. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1980–1988 Mots-clés : Design  Rotary  compressor  Efficiency  Friction Résumé : This paper presents design improvements of a Revolving Vane (RV) compressor which significantly reduce the frictional losses. The original RV compressor has a vane that swivels during the operation. Though in general, the frictional losses of the RV compressor are significantly lower than most currently available rotary compressors, this swivel vane design has a disadvantage of relatively high vane side friction loss. The latter is caused by a high vane-side and slot contact force due to a high gas pressure differential force across the vane. In this paper, a new design concept has been introduced to totally eliminate the vane side friction loss caused by the gas pressure differential force across the vane. This is achieved by rigidly fixes the vane onto the rotor or the cylinder. This new design yielded two possible variants, each reduces the frictional losses by 18% and 41% and improves the mechanical efficiency from 93% to 94% and 96% respectively. In this paper, details analysis on the new design that leads to the improvement in performance are presented and shown. The analysis also reveals that the design with the highest mechanical efficiency comes with a small price of a higher instantaneous peak torque requirement. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001551

Object-oriented simulation of reciprocating compressors / R. Damle in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1989–1998 Titre : Object-oriented simulation of reciprocating compressors : Numerical verification and experimental comparison Titre original : Simulation des compresseurs à piston fondée sur les objets: vérification numérique et comparaison expérimentale Type de document : texte imprimé Auteurs : R. Damle, Auteur ; J. Rigola, Auteur ; C.D. Pérez-Segarra, Auteur Année de publication : 2012 Article en page(s) : pp. 1989–1998 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Reciprocating  compressor  Simulation  Experimentation  Refrigeration Résumé : Numerical simulation of reciprocating compressors is important for the design, development, improvement and optimization of the elements constituting the compressor circuit. In this work, an object-oriented unstructured modular numerical simulation of reciprocating compressors is presented. Pressure correction approach is applied for the resolution of tubes, chambers and compression chambers, while valve dynamics are modelled assuming a spring-mass system having single degree of freedom. The modular approach offers advantages of handling complex circuitry (e.g. parallel paths, multiple compressor chambers, etc.), coupling different simulation models for each element and adaptability to different configurations without changing the program. The code has been verified with some basic tests for assuring asymptotic behaviour to guarantee error free code and physically realistic results. Cases with different compressor configurations and working fluids (R134a, R600a and R744) have also been worked out. Numerical results are compared with experimental data and illustrative cases of multi-stage compression are also presented. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000508 [article] Object-oriented simulation of reciprocating compressors = Simulation des compresseurs à piston fondée sur les objets: vérification numérique et comparaison expérimentale : Numerical verification and experimental comparison [texte imprimé] / R. Damle, Auteur ; J. Rigola, Auteur ; C.D. Pérez-Segarra, Auteur . - 2012 . - pp. 1989–1998. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1989–1998 Mots-clés : Reciprocating  compressor  Simulation  Experimentation  Refrigeration Résumé : Numerical simulation of reciprocating compressors is important for the design, development, improvement and optimization of the elements constituting the compressor circuit. In this work, an object-oriented unstructured modular numerical simulation of reciprocating compressors is presented. Pressure correction approach is applied for the resolution of tubes, chambers and compression chambers, while valve dynamics are modelled assuming a spring-mass system having single degree of freedom. The modular approach offers advantages of handling complex circuitry (e.g. parallel paths, multiple compressor chambers, etc.), coupling different simulation models for each element and adaptability to different configurations without changing the program. The code has been verified with some basic tests for assuring asymptotic behaviour to guarantee error free code and physically realistic results. Cases with different compressor configurations and working fluids (R134a, R600a and R744) have also been worked out. Numerical results are compared with experimental data and illustrative cases of multi-stage compression are also presented. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000508

Quantitative evaluation of the effects of poly-vinyl alcohol on supercooling phenomena of water / Hiroyuki Kumano in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1999–2006 Titre : Quantitative evaluation of the effects of poly-vinyl alcohol on supercooling phenomena of water Titre original : Evaluation quantitative des effets de l'alcool polyvinylique sur les phénomènes de surrefroidissement de l'eau Type de document : texte imprimé Auteurs : Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Shutaro Takeda, Auteur Année de publication : 2012 Article en page(s) : pp. 1999–2006 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Freezing  Nucleation  Solutions  Polymers  Water  Supercooling Résumé : The effect of poly-vinyl alcohols (PVAs) on the supercooling of water was investigated experimentally for varying sample volumes and degrees of polymerization and saponification. A statistical analysis was carried out on the experimental results and a quantitative evaluation of the inhibition effect of PVA on release of the supercooled state was attempted by introducing a coefficient representing the inhibition effect of PVA. Experimental results and the values calculated from the statistical analysis agreed well and it was found the statistical analysis could be applied to the freezing of supercooled water containing PVA. Moreover, the effects of the PVA on the release of the supercooled state were evaluated quantitatively, using the statistical analysis. The effect of the degree of polymerization is insignificant but it was found that the inhibition effect of PVA increased with increasing degrees of saponification. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001617 [article] Quantitative evaluation of the effects of poly-vinyl alcohol on supercooling phenomena of water = Evaluation quantitative des effets de l'alcool polyvinylique sur les phénomènes de surrefroidissement de l'eau [texte imprimé] / Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Shutaro Takeda, Auteur . - 2012 . - pp. 1999–2006. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1999–2006 Mots-clés : Freezing  Nucleation  Solutions  Polymers  Water  Supercooling Résumé : The effect of poly-vinyl alcohols (PVAs) on the supercooling of water was investigated experimentally for varying sample volumes and degrees of polymerization and saponification. A statistical analysis was carried out on the experimental results and a quantitative evaluation of the inhibition effect of PVA on release of the supercooled state was attempted by introducing a coefficient representing the inhibition effect of PVA. Experimental results and the values calculated from the statistical analysis agreed well and it was found the statistical analysis could be applied to the freezing of supercooled water containing PVA. Moreover, the effects of the PVA on the release of the supercooled state were evaluated quantitatively, using the statistical analysis. The effect of the degree of polymerization is insignificant but it was found that the inhibition effect of PVA increased with increasing degrees of saponification. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001617

Freezing mechanism of supercooled water droplet impinging on metal surfaces / Guomin Yang in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2007–2017 Titre : Freezing mechanism of supercooled water droplet impinging on metal surfaces Titre original : Mécanisme de congélation des gouttelettes d'eau surrefroidies impactant sur des surfaces métalliques Type de document : texte imprimé Auteurs : Guomin Yang, Auteur ; Kaihua Guo, Auteur ; Ning Li, Auteur Année de publication : 2012 Article en page(s) : pp. 2007–2017 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Supercooling  Water  Droplet  Freezing  Ice  Morphology Résumé : Ice accretion on power lines is a random natural phenomenon and may seriously harm to the safety of power network. However, the mechanism of the freezing process of supercooled water droplet impacting on wires is still not fully understood. In this study, an experimental investigation on the freezing mechanism of the supercooled water droplet impinging on cold metal surfaces was performed. The morphological characters and the dynamics of a single supercooled droplet collide on the cylindrical metal surfaces had been revealed with high-speed photographing. The experimental data for the surfaces of stainless steel, copper and aluminum, on which the supercooled droplets impinging with speeds of 2.3 m s−1 and 4.3 m s−1 had been plotted. The phenomena of instantaneous and non-instantaneous freezing of the supercooled impinging droplet were identified and the conditional boundaries for these two kinds of freezing were found statistically. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001629 [article] Freezing mechanism of supercooled water droplet impinging on metal surfaces = Mécanisme de congélation des gouttelettes d'eau surrefroidies impactant sur des surfaces métalliques [texte imprimé] / Guomin Yang, Auteur ; Kaihua Guo, Auteur ; Ning Li, Auteur . - 2012 . - pp. 2007–2017. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2007–2017 Mots-clés : Supercooling  Water  Droplet  Freezing  Ice  Morphology Résumé : Ice accretion on power lines is a random natural phenomenon and may seriously harm to the safety of power network. However, the mechanism of the freezing process of supercooled water droplet impacting on wires is still not fully understood. In this study, an experimental investigation on the freezing mechanism of the supercooled water droplet impinging on cold metal surfaces was performed. The morphological characters and the dynamics of a single supercooled droplet collide on the cylindrical metal surfaces had been revealed with high-speed photographing. The experimental data for the surfaces of stainless steel, copper and aluminum, on which the supercooled droplets impinging with speeds of 2.3 m s−1 and 4.3 m s−1 had been plotted. The phenomena of instantaneous and non-instantaneous freezing of the supercooled impinging droplet were identified and the conditional boundaries for these two kinds of freezing were found statistically. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001629

Modeling non-uniform frost growth on a fin-and-tube heat exchanger / S.K. Padhmanabhan in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2018–2030 Titre : Modeling non-uniform frost growth on a fin-and-tube heat exchanger Titre original : Modélisation de la formation de givre non uniforme sur un échangeur de chaleur à tubes ailetés Type de document : texte imprimé Auteurs : S.K. Padhmanabhan, Auteur ; D.E. Fisher, Auteur ; L. Cremaschi, Auteur Année de publication : 2012 Article en page(s) : pp. 2018–2030 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Frost  Modeling  Finned  tube  Air  distribution Résumé : A semi-empirical model that predicts non-uniform frost growth on heat exchangers is developed and experimentally validated. The model is based on a scaling approach that uses the average frost layer properties to predict growth in a quasi-steady state, heat and mass balance based segment-by-segment coil simulation. The air redistribution algorithm in the model improved frost thickness predictions by 20%–50% and coil capacity predictions by 42% compared to the same model without air redistribution. The model along with an empirical frost delay predicted the frost thickness for different inlet refrigerant temperatures, air relative humidities and air velocities under non-uniform frosting with a root mean square error of 3.7%, 9.8% and 5.2% respectively. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001459 [article] Modeling non-uniform frost growth on a fin-and-tube heat exchanger = Modélisation de la formation de givre non uniforme sur un échangeur de chaleur à tubes ailetés [texte imprimé] / S.K. Padhmanabhan, Auteur ; D.E. Fisher, Auteur ; L. Cremaschi, Auteur . - 2012 . - pp. 2018–2030. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2018–2030 Mots-clés : Frost  Modeling  Finned  tube  Air  distribution Résumé : A semi-empirical model that predicts non-uniform frost growth on heat exchangers is developed and experimentally validated. The model is based on a scaling approach that uses the average frost layer properties to predict growth in a quasi-steady state, heat and mass balance based segment-by-segment coil simulation. The air redistribution algorithm in the model improved frost thickness predictions by 20%–50% and coil capacity predictions by 42% compared to the same model without air redistribution. The model along with an empirical frost delay predicted the frost thickness for different inlet refrigerant temperatures, air relative humidities and air velocities under non-uniform frosting with a root mean square error of 3.7%, 9.8% and 5.2% respectively. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001459

In-situ study of frosting and defrosting processes in tube-fin evaporators of household refrigerating appliances / Fernando T. Knabben in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2031–2041 Titre : In-situ study of frosting and defrosting processes in tube-fin evaporators of household refrigerating appliances Titre original : Etude sur les processus de givrage et de dégivrage des évaporateurs à tubes ailetés des appareils frigorifiques domestiques Type de document : texte imprimé Auteurs : Fernando T. Knabben, Auteur ; Christian J.L. Hermes, Auteur ; Cláudio Melo, Auteur Année de publication : 2012 Article en page(s) : pp. 2031–2041 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Frosting  Defrosting  Evaporator  Refrigerator Résumé : The present paper advances an in-situ study of frosting and defrosting processes in tube-fin evaporators of household refrigerators and freezers. Frost growth experiments were carried out using a purpose-built test facility comprised of a refrigerated cabinet placed inside a climatized chamber, and a vapor compression refrigeration loop that controls both the evaporating temperature and the evaporator superheating. A first-principles two-dimensional simulation model was put forward to predict the evaporator blocking over time, and also the heat and mass transfer rates. The model validation exercise has shown that the model follows well the experimental trends of pressure drop, frost mass, cooling capacity and air flow rate, with all predictions falling inside ±10% error bounds. The model was then used to assess the impact of several design parameters on both the evaporator blockage and defrost efficiency. It was found that a nearly ideal defrost efficiency is achieved when the defrosting process is performed by two simultaneous heaters. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001800 [article] In-situ study of frosting and defrosting processes in tube-fin evaporators of household refrigerating appliances = Etude sur les processus de givrage et de dégivrage des évaporateurs à tubes ailetés des appareils frigorifiques domestiques [texte imprimé] / Fernando T. Knabben, Auteur ; Christian J.L. Hermes, Auteur ; Cláudio Melo, Auteur . - 2012 . - pp. 2031–2041. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2031–2041 Mots-clés : Frosting  Defrosting  Evaporator  Refrigerator Résumé : The present paper advances an in-situ study of frosting and defrosting processes in tube-fin evaporators of household refrigerators and freezers. Frost growth experiments were carried out using a purpose-built test facility comprised of a refrigerated cabinet placed inside a climatized chamber, and a vapor compression refrigeration loop that controls both the evaporating temperature and the evaporator superheating. A first-principles two-dimensional simulation model was put forward to predict the evaporator blocking over time, and also the heat and mass transfer rates. The model validation exercise has shown that the model follows well the experimental trends of pressure drop, frost mass, cooling capacity and air flow rate, with all predictions falling inside ±10% error bounds. The model was then used to assess the impact of several design parameters on both the evaporator blockage and defrost efficiency. It was found that a nearly ideal defrost efficiency is achieved when the defrosting process is performed by two simultaneous heaters. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001800

Application of groundwater cooling scheme for London Underground network / F. Ampofo in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2042–2049 Titre : Application of groundwater cooling scheme for London Underground network Titre original : Application d'un système de refroidissement faisant appel à l'eau souterraine au métro de Londres Type de document : texte imprimé Auteurs : F. Ampofo, Auteur ; G.G. Maidment, Auteur ; J.F. Missenden, Auteur Année de publication : 2012 Article en page(s) : pp. 2042–2049 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Groundwater  Low  energy  Cooling  system  London  Underground Résumé : The demand for acceptable thermal comfort conditions within the London Underground network has grown over the years. The operation of the network generates a large heat load, with high temperatures recorded in summer in train and on platforms. Different cooling methods and new sources of cooling have been proposed for cooling the network. Of the new sources of cooling proposed, groundwater cooling is the first to be tried. London Underground Limited unique characteristics of being close to the aquifer of the central London basin, rivers and also because they pump over 30 million litres of water from the network every day make it an ideal site for this technology. This paper investigates thermal issues within London Underground network and presents an overview of groundwater cooling schemes for the network. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001228 [article] Application of groundwater cooling scheme for London Underground network = Application d'un système de refroidissement faisant appel à l'eau souterraine au métro de Londres [texte imprimé] / F. Ampofo, Auteur ; G.G. Maidment, Auteur ; J.F. Missenden, Auteur . - 2012 . - pp. 2042–2049. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2042–2049 Mots-clés : Groundwater  Low  energy  Cooling  system  London  Underground Résumé : The demand for acceptable thermal comfort conditions within the London Underground network has grown over the years. The operation of the network generates a large heat load, with high temperatures recorded in summer in train and on platforms. Different cooling methods and new sources of cooling have been proposed for cooling the network. Of the new sources of cooling proposed, groundwater cooling is the first to be tried. London Underground Limited unique characteristics of being close to the aquifer of the central London basin, rivers and also because they pump over 30 million litres of water from the network every day make it an ideal site for this technology. This paper investigates thermal issues within London Underground network and presents an overview of groundwater cooling schemes for the network. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001228

Using cooling load forecast as the optimal operation scheme for a large multi-chiller system / Yan-Yue Lu in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2050–2062 Titre : Using cooling load forecast as the optimal operation scheme for a large multi-chiller system Titre original : Utilisation de la charge thermique pour prévoir le fonctionnement optimal d'un grand système à plusieurs refroidisseurs Type de document : texte imprimé Auteurs : Yan-Yue Lu, Auteur ; Junghui Chen, Auteur ; Tzu-Chi Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 2050–2062 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : System  Chiller  Energy  savings  Modelling  Optimal  design Résumé : Energy saving is one of the most important issues in high-tech manufacturing industries, such as semiconductor and electronics, because large chilled water systems are used to satisfy big cooling load requirements. In this paper, a new optimal integrity scheme based on a two-stage strategy, including a scheduling stage and an operating stage, is proposed to minimize the system energy consumption within a future time period. Instead of a lag scheme used in the general method, a forecasting scheme consisting of a series of optimal schemes at each sub-time period is also proposed for the two-stage design. The performance of the proposed method is examined through an industrial case. The cost of the proposed method is much less than that of the conventional method, so the proposed method is cost-efficient in applications of large air-conditioning systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001204 [article] Using cooling load forecast as the optimal operation scheme for a large multi-chiller system = Utilisation de la charge thermique pour prévoir le fonctionnement optimal d'un grand système à plusieurs refroidisseurs [texte imprimé] / Yan-Yue Lu, Auteur ; Junghui Chen, Auteur ; Tzu-Chi Liu, Auteur . - 2012 . - pp. 2050–2062. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2050–2062 Mots-clés : System  Chiller  Energy  savings  Modelling  Optimal  design Résumé : Energy saving is one of the most important issues in high-tech manufacturing industries, such as semiconductor and electronics, because large chilled water systems are used to satisfy big cooling load requirements. In this paper, a new optimal integrity scheme based on a two-stage strategy, including a scheduling stage and an operating stage, is proposed to minimize the system energy consumption within a future time period. Instead of a lag scheme used in the general method, a forecasting scheme consisting of a series of optimal schemes at each sub-time period is also proposed for the two-stage design. The performance of the proposed method is examined through an industrial case. The cost of the proposed method is much less than that of the conventional method, so the proposed method is cost-efficient in applications of large air-conditioning systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001204

A neuro-fuzzy identification of non-linear transient systems / I.C. Franco in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2063–2075 Titre : A neuro-fuzzy identification of non-linear transient systems : Application to a pilot refrigeration plant Titre original : Identification neuronale / par logique floue des systèmes en régime transitoire non linéaires: Application à une installation frigorifique pilote Type de document : texte imprimé Auteurs : I.C. Franco, Auteur ; M. Dall’Agnol, Auteur ; T.V. Costa, Auteur Année de publication : 2012 Article en page(s) : pp. 2063–2075 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Compression  system  Modeling  Cooling  Propylene  glycol  Neural  network  Fuzzy  logic Résumé : This study proposes to determine empirical models that represent the non-linear dynamics of a pilot refrigeration system (chiller), by using identification techniques of neuro-fuzzy systems (ANFIS). A detailed experimental study of a pilot refrigeration process using compression was conducted. Non-linearities were detected in the experimental data obtained from the system. Neuro-fuzzy models were developed for the prediction of the following process temperatures: condensation; evaporation; and refrigerated fluid (propylene glycol aqueous solution). The validation of the models was successfully conducted offline and online. The values obtained for VAF (“variance accounted for”) performance index and the dispersion plots showed the high performance of the models. These empirical models will be especially useful in the development of different non-linear control strategies, such as: fuzzy, neuro-fuzzy and model predictive control. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001046# [article] A neuro-fuzzy identification of non-linear transient systems = Identification neuronale / par logique floue des systèmes en régime transitoire non linéaires: Application à une installation frigorifique pilote : Application to a pilot refrigeration plant [texte imprimé] / I.C. Franco, Auteur ; M. Dall’Agnol, Auteur ; T.V. Costa, Auteur . - 2012 . - pp. 2063–2075. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2063–2075 Mots-clés : Compression  system  Modeling  Cooling  Propylene  glycol  Neural  network  Fuzzy  logic Résumé : This study proposes to determine empirical models that represent the non-linear dynamics of a pilot refrigeration system (chiller), by using identification techniques of neuro-fuzzy systems (ANFIS). A detailed experimental study of a pilot refrigeration process using compression was conducted. Non-linearities were detected in the experimental data obtained from the system. Neuro-fuzzy models were developed for the prediction of the following process temperatures: condensation; evaporation; and refrigerated fluid (propylene glycol aqueous solution). The validation of the models was successfully conducted offline and online. The values obtained for VAF (“variance accounted for”) performance index and the dispersion plots showed the high performance of the models. These empirical models will be especially useful in the development of different non-linear control strategies, such as: fuzzy, neuro-fuzzy and model predictive control. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001046#

Development of low-noise centrifugal fans for a refrigerator using inclined S-shaped trailing edge / Seung Heo in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2076–2091 Titre : Development of low-noise centrifugal fans for a refrigerator using inclined S-shaped trailing edge Titre original : Développement de ventilateurs centrifuges peu sonores pour un réfrigérateur à l’aide de la bordure de traînée inclinée en forme de S Type de document : texte imprimé Auteurs : Seung Heo, Auteur ; Cheolung Cheong, Auteur ; Tae-Hoon Kim, Auteur Année de publication : 2012 Article en page(s) : pp. 2076–2091 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Household  refrigerator  Centrifugal  fan  Noise  Acoustics Résumé : Low-noise centrifugal fans are developed by modifying the linear trailing edge lines of the fan blades into inclined S-shaped lines. The noise reductions achieved by using the inclined S-shaped trailing edges in the existing fans are confirmed by comparing the predicted BPF noise components of the developed fans with those of the existing fan. In addition, the turbulent kinetic energy of the fluid for the inclined S-shaped fans is predicted to be less than that for the existing fan. Finally, experiments using four prototype fans show that the levels of broadband noise from the newly developed fans are less than those of noise from existing fans. An additional experiment performed by using a selected low-noise fan installed in a household refrigerator show that the overall noise from the new fan is reduced by approximately 2.2 dB in comparison with that from the existing fan in the refrigerator. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001733 [article] Development of low-noise centrifugal fans for a refrigerator using inclined S-shaped trailing edge = Développement de ventilateurs centrifuges peu sonores pour un réfrigérateur à l’aide de la bordure de traînée inclinée en forme de S [texte imprimé] / Seung Heo, Auteur ; Cheolung Cheong, Auteur ; Tae-Hoon Kim, Auteur . - 2012 . - pp. 2076–2091. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2076–2091 Mots-clés : Household  refrigerator  Centrifugal  fan  Noise  Acoustics Résumé : Low-noise centrifugal fans are developed by modifying the linear trailing edge lines of the fan blades into inclined S-shaped lines. The noise reductions achieved by using the inclined S-shaped trailing edges in the existing fans are confirmed by comparing the predicted BPF noise components of the developed fans with those of the existing fan. In addition, the turbulent kinetic energy of the fluid for the inclined S-shaped fans is predicted to be less than that for the existing fan. Finally, experiments using four prototype fans show that the levels of broadband noise from the newly developed fans are less than those of noise from existing fans. An additional experiment performed by using a selected low-noise fan installed in a household refrigerator show that the overall noise from the new fan is reduced by approximately 2.2 dB in comparison with that from the existing fan in the refrigerator. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001733

Fundamental principles for sizing and design of gravity separators for industrial refrigeration / Bent Wiencke in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2092–2108 Titre : Fundamental principles for sizing and design of gravity separators for industrial refrigeration Titre original : Principes de base pour le dimensionnement et la conception de séparateurs de liquide par gravité pour le froid industriel Type de document : texte imprimé Auteurs : Bent Wiencke, Auteur Année de publication : 2012 Article en page(s) : pp. 2092–2108 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Refrigeration  Two-phase  flow  Liquid  Gravity  Separation  Mass  transfer Résumé : Throughout the past decades, the industrial refrigeration industry has developed various “rule of thumb” methods for sizing gravity liquid separators for ammonia and other common refrigerants. However, to date a uniform systematic approach or an agreeable standard has not been established. For commonly used refrigerants such as ammonia, the large installed base of separators can be used as a benchmark for sizing separators. But, when using a less common refrigerant such as CO2, the designer faces new challenges. In this paper, a systematic approach is presented for sizing horizontal and vertical gravity liquid separators for industrial refrigeration applications. To compute separation velocities and separation distances, a theoretical model is presented. The model is used as a basis for comparison with observations from 85 operating gravity separators surveyed in the field. Criteria and formulas are presented for estimating the required liquid volume for storage. An example is provided demonstrating the use of the methods presented in this paper. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001563 [article] Fundamental principles for sizing and design of gravity separators for industrial refrigeration = Principes de base pour le dimensionnement et la conception de séparateurs de liquide par gravité pour le froid industriel [texte imprimé] / Bent Wiencke, Auteur . - 2012 . - pp. 2092–2108. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2092–2108 Mots-clés : Refrigeration  Two-phase  flow  Liquid  Gravity  Separation  Mass  transfer Résumé : Throughout the past decades, the industrial refrigeration industry has developed various “rule of thumb” methods for sizing gravity liquid separators for ammonia and other common refrigerants. However, to date a uniform systematic approach or an agreeable standard has not been established. For commonly used refrigerants such as ammonia, the large installed base of separators can be used as a benchmark for sizing separators. But, when using a less common refrigerant such as CO2, the designer faces new challenges. In this paper, a systematic approach is presented for sizing horizontal and vertical gravity liquid separators for industrial refrigeration applications. To compute separation velocities and separation distances, a theoretical model is presented. The model is used as a basis for comparison with observations from 85 operating gravity separators surveyed in the field. Criteria and formulas are presented for estimating the required liquid volume for storage. An example is provided demonstrating the use of the methods presented in this paper. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001563

Solubility of nitrogen in one-component refrigerants / Václav Vinš in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2109–2117 Titre : Solubility of nitrogen in one-component refrigerants : Prediction by PC-SAFT EoS and a correlation of Henry’s law constants Titre original : Solubilité de l'azote dans les frigorigènes à un seul composant : prévision par l'équation d'état PC-SAFT et par corrélation des constantes de la loi de Henry Type de document : texte imprimé Auteurs : Václav Vinš, Auteur ; Jan Hrubý, Auteur Année de publication : 2012 Article en page(s) : pp. 2109–2117 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Equation  of  state  Nitrogen  Non-condensable  gas  Refrigerant  Solubility Résumé : Even small amount of non-condensable gas – mostly air or nitrogen – present inside a compression refrigerating circuit may decrease the efficiency of the cooling system. So far, a quantitative assessment of the effect of dissolved gases on the cooling circuit performance is hindered by unavailability of suitable thermodynamic models. In this study, we analyzed the solubility of nitrogen in the following refrigerants: hydrochlorofluorocarbons (HCFC) R22, R123, R124; hydrofluorocarbons (HFC) R23, R32, R125, R134a; perfluorocarbons (PFC) R14, R116, R218, R-3-1-10; and hydrocarbons (HC) R290, R600a. Perturbed-Chain (PC) Statistical Associating Fluid Theory (SAFT) and its modification for polar fluids PCP-SAFT were used to model the temperature dependence of the Henry’s law constant of nitrogen. A simple correlation of the Henry’s law constants valid over large temperature ranges was developed, suitable for assessment of the adverse effects of dissolved nitrogen (and approximately air) on the performance of compression cooling systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001630 [article] Solubility of nitrogen in one-component refrigerants = Solubilité de l'azote dans les frigorigènes à un seul composant : prévision par l'équation d'état PC-SAFT et par corrélation des constantes de la loi de Henry : Prediction by PC-SAFT EoS and a correlation of Henry’s law constants [texte imprimé] / Václav Vinš, Auteur ; Jan Hrubý, Auteur . - 2012 . - pp. 2109–2117. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2109–2117 Mots-clés : Equation  of  state  Nitrogen  Non-condensable  gas  Refrigerant  Solubility Résumé : Even small amount of non-condensable gas – mostly air or nitrogen – present inside a compression refrigerating circuit may decrease the efficiency of the cooling system. So far, a quantitative assessment of the effect of dissolved gases on the cooling circuit performance is hindered by unavailability of suitable thermodynamic models. In this study, we analyzed the solubility of nitrogen in the following refrigerants: hydrochlorofluorocarbons (HCFC) R22, R123, R124; hydrofluorocarbons (HFC) R23, R32, R125, R134a; perfluorocarbons (PFC) R14, R116, R218, R-3-1-10; and hydrocarbons (HC) R290, R600a. Perturbed-Chain (PC) Statistical Associating Fluid Theory (SAFT) and its modification for polar fluids PCP-SAFT were used to model the temperature dependence of the Henry’s law constant of nitrogen. A simple correlation of the Henry’s law constants valid over large temperature ranges was developed, suitable for assessment of the adverse effects of dissolved nitrogen (and approximately air) on the performance of compression cooling systems. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001630

Numerical investigation of gas species and energy separation in the Ranque–Hilsch vortex tube using real gas model / T. Dutta in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2118–2128 Titre : Numerical investigation of gas species and energy separation in the Ranque–Hilsch vortex tube using real gas model : Etude numérique des gaz et de la séparation de l’énergie dans un tube vortex Ranque-Hilsch à l’aide d’un modèle employant un gaz réel Type de document : texte imprimé Auteurs : T. Dutta, Auteur ; K.P. Sinhamahapatra, Auteur ; S. S. Bandyopadhyay, Auteur Année de publication : 2012 Article en page(s) : pp. 2118–2128 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Vortex  tube  Computational  fluid  dynamics  Temperature  Thermal  diffusion Résumé : A three dimensional Computational Fluid Dynamics (CFD) model is used to investigate the phenomena of energy and species separation in a vortex tube (VT) with compressed air at normal atmospheric temperature and cryogenic temperature as the working fluid. In this work the NIST real gas model is used for the first time to accurately compute the thermodynamic and transport properties of air inside the VT. CFD simulations are carried out using the perfect gas law as well. The computed performance curves (hot and cold outlet temperatures versus hot outlet mass fraction) at normal atmospheric temperature obtained with both the real gas model and the perfect gas law are compared with the experimental results. The separation of air into its main components, i.e. oxygen and nitrogen is observed, although the separation effect is very small. The magnitudes of both the energy separation and the species separation at cryogenic temperature were found to be smaller than those at normal atmospheric temperature. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001447 [article] Numerical investigation of gas species and energy separation in the Ranque–Hilsch vortex tube using real gas model : Etude numérique des gaz et de la séparation de l’énergie dans un tube vortex Ranque-Hilsch à l’aide d’un modèle employant un gaz réel [texte imprimé] / T. Dutta, Auteur ; K.P. Sinhamahapatra, Auteur ; S. S. Bandyopadhyay, Auteur . - 2012 . - pp. 2118–2128. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2118–2128 Mots-clés : Vortex  tube  Computational  fluid  dynamics  Temperature  Thermal  diffusion Résumé : A three dimensional Computational Fluid Dynamics (CFD) model is used to investigate the phenomena of energy and species separation in a vortex tube (VT) with compressed air at normal atmospheric temperature and cryogenic temperature as the working fluid. In this work the NIST real gas model is used for the first time to accurately compute the thermodynamic and transport properties of air inside the VT. CFD simulations are carried out using the perfect gas law as well. The computed performance curves (hot and cold outlet temperatures versus hot outlet mass fraction) at normal atmospheric temperature obtained with both the real gas model and the perfect gas law are compared with the experimental results. The separation of air into its main components, i.e. oxygen and nitrogen is observed, although the separation effect is very small. The magnitudes of both the energy separation and the species separation at cryogenic temperature were found to be smaller than those at normal atmospheric temperature. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001447

Performance analysis of multi-stage thermoelectric coolers / G. Karimi in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2129–2135 Titre : Performance analysis of multi-stage thermoelectric coolers Titre original : Analyse de la performance des refroidisseurs thermoélectriques multiétagés Type de document : texte imprimé Auteurs : G. Karimi, Auteur ; J.R. Culham, Auteur ; V. Kazerouni, Auteur Année de publication : 2012 Article en page(s) : pp. 2129–2135 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Thermoelectricity  Refrigerator  Cooler  Heat  flux  Thermal  analysis  Performance Résumé : Multi-stage thermoelectric coolers offer larger temperature differences between heat source and heat sink than single-stage thermoelectric coolers. In this paper, a pyramid-type multi-stage cooler is analyzed, focusing on the importance of maximum attainable target heat flux and overall coefficient of performance, COP. Having considered the COP and the thermal resistance of a heat sink as key parameters in the design of a multi-stage thermoelectric cooler, analytical formulas for COP and heat sink thermal resistance versus working electrical current are derived. For a fixed cooling target heat flux, the ratio of the heat sink thermal resistance to the respective single-stage value and the attainable COP in a cascaded cooler are determined as a function of the number of stages. Numerical simulations clearly indicate that the thermal resistance of the hot side heat sink is the controlling factor in determining the overall performance of a multi-stage thermoelectric cooler. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001216 [article] Performance analysis of multi-stage thermoelectric coolers = Analyse de la performance des refroidisseurs thermoélectriques multiétagés [texte imprimé] / G. Karimi, Auteur ; J.R. Culham, Auteur ; V. Kazerouni, Auteur . - 2012 . - pp. 2129–2135. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2129–2135 Mots-clés : Thermoelectricity  Refrigerator  Cooler  Heat  flux  Thermal  analysis  Performance Résumé : Multi-stage thermoelectric coolers offer larger temperature differences between heat source and heat sink than single-stage thermoelectric coolers. In this paper, a pyramid-type multi-stage cooler is analyzed, focusing on the importance of maximum attainable target heat flux and overall coefficient of performance, COP. Having considered the COP and the thermal resistance of a heat sink as key parameters in the design of a multi-stage thermoelectric cooler, analytical formulas for COP and heat sink thermal resistance versus working electrical current are derived. For a fixed cooling target heat flux, the ratio of the heat sink thermal resistance to the respective single-stage value and the attainable COP in a cascaded cooler are determined as a function of the number of stages. Numerical simulations clearly indicate that the thermal resistance of the hot side heat sink is the controlling factor in determining the overall performance of a multi-stage thermoelectric cooler. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001216

Degradation kinetics of colour, vitamin C and drip loss in frozen broccoli (Brassica oleracea L. ssp. Italica) during storage at isothermal and non-isothermal conditions / Elsa M. Gonçalves in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2136–2144 Titre : Degradation kinetics of colour, vitamin C and drip loss in frozen broccoli (Brassica oleracea L. ssp. Italica) during storage at isothermal and non-isothermal conditions Titre original : Cinétique de détérioration de la couleur, de la teneur en vitamine C et exsudats du brocoli (Brassica oleracea L. ssp. Italica) pendant l'entreposage sous des conditions isothermes et non isothermes Type de document : texte imprimé Auteurs : Elsa M. Gonçalves, Auteur ; Marta Abreu, Auteur ; Brandão, Teresa R. S., Auteur Année de publication : 2012 Article en page(s) : pp. 2136–2144 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Broccoli  Freezing  Storage  Quality  Storage  life  Modelling Résumé : Studies were undertaken on colour CIE L*a*b* values, vitamin C (ascorbic acid) and drip loss alterations of frozen broccoli (Brassica oleracea L. ssp. Italica) stored at isothermal (−7, −15, and −25 °C) and non-isothermal (accelerated life testing with step-stress methodology; temperature range from −30 to −5 °C) conditions. The storage temperatures were selected according to conditions that occur in the cold chain. Frozen storage at all regimes had significant impact on all quality parameters analysed. Significant alterations in broccoli green colour, vitamin C content and drip loss were observed. Experimental data of h* colour degradation and drip loss (%) at isothermal conditions and View the MathML source at non-isothermal conditions could be modelled by zero order kinetics. A first order kinetic model was adequate for the remaining quality factors and temperature regimes. The effect of storage temperature on kinetic parameters was successfully described by the Arrhenius equation. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001514 [article] Degradation kinetics of colour, vitamin C and drip loss in frozen broccoli (Brassica oleracea L. ssp. Italica) during storage at isothermal and non-isothermal conditions = Cinétique de détérioration de la couleur, de la teneur en vitamine C et exsudats du brocoli (Brassica oleracea L. ssp. Italica) pendant l'entreposage sous des conditions isothermes et non isothermes [texte imprimé] / Elsa M. Gonçalves, Auteur ; Marta Abreu, Auteur ; Brandão, Teresa R. S., Auteur . - 2012 . - pp. 2136–2144. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 2136–2144 Mots-clés : Broccoli  Freezing  Storage  Quality  Storage  life  Modelling Résumé : Studies were undertaken on colour CIE L*a*b* values, vitamin C (ascorbic acid) and drip loss alterations of frozen broccoli (Brassica oleracea L. ssp. Italica) stored at isothermal (−7, −15, and −25 °C) and non-isothermal (accelerated life testing with step-stress methodology; temperature range from −30 to −5 °C) conditions. The storage temperatures were selected according to conditions that occur in the cold chain. Frozen storage at all regimes had significant impact on all quality parameters analysed. Significant alterations in broccoli green colour, vitamin C content and drip loss were observed. Experimental data of h* colour degradation and drip loss (%) at isothermal conditions and View the MathML source at non-isothermal conditions could be modelled by zero order kinetics. A first order kinetic model was adequate for the remaining quality factors and temperature regimes. The effect of storage temperature on kinetic parameters was successfully described by the Arrhenius equation. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711001514

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse