Dépouillements

Review of correlations of flow boiling heat transfer coefficients for carbon dioxide / Xiande Fang in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2017–2039 Titre : Review of correlations of flow boiling heat transfer coefficients for carbon dioxide Titre original : Corrélations du transfert de chaleur lors de l'ébullition en écoulement pour le dioxyde de carbone : synthèse Type de document : texte imprimé Auteurs : Xiande Fang, Auteur ; Zhanru, Zhou, Auteur ; Dingkun, Li, Auteur Année de publication : 2014 Article en page(s) : pp. 2017–2039 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Carbon  dioxide;  flow  boiling;  heat  transfer;  coefficient;  correlation Résumé : Carbon dioxide (CO2) has quite different flow boiling heat transfer characteristics from conventional refrigerants due to its much higher reduced pressures that make its thermodynamic and transport properties very different. There were some studies evaluating the correlations of flow boiling heat transfer coefficient for CO2. However, either the number of correlations covered or the number of data used was limited, resulting in inconsistent conclusions. This work presents a comparative review of existing correlations for flow boiling heat transfer coefficient of CO2. There are 34 correlations analyzed and evaluated using 2956 experimental data points of CO2 flow boiling heat transfer from 10 independent laboratories. The Fang (2013) correlation performs best with a mean absolute deviation of 15.5%. The evaluation analysis sets a channel transition criterion for flow boiling heat transfer of CO2. Several topics worthy of attention for future studies are identified. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001424 [article] Review of correlations of flow boiling heat transfer coefficients for carbon dioxide = Corrélations du transfert de chaleur lors de l'ébullition en écoulement pour le dioxyde de carbone : synthèse [texte imprimé] / Xiande Fang, Auteur ; Zhanru, Zhou, Auteur ; Dingkun, Li, Auteur . - 2014 . - pp. 2017–2039. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2017–2039 Mots-clés : Carbon  dioxide;  flow  boiling;  heat  transfer;  coefficient;  correlation Résumé : Carbon dioxide (CO2) has quite different flow boiling heat transfer characteristics from conventional refrigerants due to its much higher reduced pressures that make its thermodynamic and transport properties very different. There were some studies evaluating the correlations of flow boiling heat transfer coefficient for CO2. However, either the number of correlations covered or the number of data used was limited, resulting in inconsistent conclusions. This work presents a comparative review of existing correlations for flow boiling heat transfer coefficient of CO2. There are 34 correlations analyzed and evaluated using 2956 experimental data points of CO2 flow boiling heat transfer from 10 independent laboratories. The Fang (2013) correlation performs best with a mean absolute deviation of 15.5%. The evaluation analysis sets a channel transition criterion for flow boiling heat transfer of CO2. Several topics worthy of attention for future studies are identified. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001424

Effect of micro-grooves on the two-phase pressure drop of CO2 in a mini-channel tube / Dae-hwan, Kim in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2040–2047 Titre : Effect of micro-grooves on the two-phase pressure drop of CO2 in a mini-channel tube Titre original : Effet des micro-rainures sur la chute de pression diphasique du CO2 à l'intérieur d'un mini-canal Type de document : texte imprimé Auteurs : Dae-hwan, Kim, Auteur ; Siyoung, Jeong, Auteur Année de publication : 2014 Article en page(s) : pp. 2040–2047 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Two-phase;  pressure  drop;  micro-grooves;  mini-channel;  carbon  dioxide Résumé : The pressure drop characteristics of CO2 have been experimentally investigated for a mini-channel tube with and without micro rectangular grooves. The multiple mini-channels have an inner diameter of 0.8 mm and the grooves have a rectangular cross section (0.1 × 0.2 mm). The pressure drop was measured for a saturated liquid phase and two-phase. Using the hydraulic diameter, the pressure drop in the grooved mini-channel can be successfully estimated with the correlations used for smooth channels. Because of a smaller hydraulic diameter, the pressure drop of the grooved channel was found to be about 1.3 times and 1.1–1.45 times greater than that of the smooth channel, for liquid and two-phase, respectively. The experimental results were compared with widely used two-phase pressure drop models. Most of the models showed the mean absolute error of 17–35% for the smooth channel and 13–32% for the grooved channel. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001461 [article] Effect of micro-grooves on the two-phase pressure drop of CO2 in a mini-channel tube = Effet des micro-rainures sur la chute de pression diphasique du CO2 à l'intérieur d'un mini-canal [texte imprimé] / Dae-hwan, Kim, Auteur ; Siyoung, Jeong, Auteur . - 2014 . - pp. 2040–2047. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2040–2047 Mots-clés : Two-phase;  pressure  drop;  micro-grooves;  mini-channel;  carbon  dioxide Résumé : The pressure drop characteristics of CO2 have been experimentally investigated for a mini-channel tube with and without micro rectangular grooves. The multiple mini-channels have an inner diameter of 0.8 mm and the grooves have a rectangular cross section (0.1 × 0.2 mm). The pressure drop was measured for a saturated liquid phase and two-phase. Using the hydraulic diameter, the pressure drop in the grooved mini-channel can be successfully estimated with the correlations used for smooth channels. Because of a smaller hydraulic diameter, the pressure drop of the grooved channel was found to be about 1.3 times and 1.1–1.45 times greater than that of the smooth channel, for liquid and two-phase, respectively. The experimental results were compared with widely used two-phase pressure drop models. Most of the models showed the mean absolute error of 17–35% for the smooth channel and 13–32% for the grooved channel. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001461

Modeling and simulation of the transcritical CO2 heat pump system / Kai-Hsiang, Lin in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2048–2064 Titre : Modeling and simulation of the transcritical CO2 heat pump system Titre original : Modélisation et simulation du système de pompe à chaleur au CO2 transcritique Type de document : texte imprimé Auteurs : Kai-Hsiang, Lin, Auteur ; Cheng-Shu, Kuo, Auteur ; Wen-Der, Hsieh, Auteur Année de publication : 2014 Article en page(s) : pp. 2048–2064 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Carbon  dioxide;  gas  cooler;  system  modeling;  COP;  transcritical Résumé : In this study, a CO2 transcritical cycle model without imposing any excessive constraints such as fixed discharge pressure and suction pressure is developed. The detailed geometrical variation of the gas cooler and the evaporator have been taken into account. The model is validated with the experimental measurements. Parametric influences on the CO2 system with regard to the effect of dry bulb temperature, relative humidity, inlet water temperature, compressor speed, and the capillary tube length are reported. The COP increases with the dry bulb temperature or the inlet relative humidity of the evaporator. Despite the refrigerant mass flowrate may be increased with the inlet water temperature, the COP declines considerably with it. Increasing the compressor speed leads to a higher heating capacity and to a much lower COP. Unlike those of the conventional sub-critical refrigerant, the COP of the transcritical CO2 cycle does not reveal a maximum value against the capillary tube length. En ligne : Modélisation et simulation du système de pompe à chaleur au CO2 transcritique [article] Modeling and simulation of the transcritical CO2 heat pump system = Modélisation et simulation du système de pompe à chaleur au CO2 transcritique [texte imprimé] / Kai-Hsiang, Lin, Auteur ; Cheng-Shu, Kuo, Auteur ; Wen-Der, Hsieh, Auteur . - 2014 . - pp. 2048–2064. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2048–2064 Mots-clés : Carbon  dioxide;  gas  cooler;  system  modeling;  COP;  transcritical Résumé : In this study, a CO2 transcritical cycle model without imposing any excessive constraints such as fixed discharge pressure and suction pressure is developed. The detailed geometrical variation of the gas cooler and the evaporator have been taken into account. The model is validated with the experimental measurements. Parametric influences on the CO2 system with regard to the effect of dry bulb temperature, relative humidity, inlet water temperature, compressor speed, and the capillary tube length are reported. The COP increases with the dry bulb temperature or the inlet relative humidity of the evaporator. Despite the refrigerant mass flowrate may be increased with the inlet water temperature, the COP declines considerably with it. Increasing the compressor speed leads to a higher heating capacity and to a much lower COP. Unlike those of the conventional sub-critical refrigerant, the COP of the transcritical CO2 cycle does not reveal a maximum value against the capillary tube length. En ligne : Modélisation et simulation du système de pompe à chaleur au CO2 transcritique

Novel partial admission radial compressor for CO2 applications / Bartosz, Kus in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2065–2078 Titre : Novel partial admission radial compressor for CO2 applications Titre original : Nouveau compresseur radial à admission radiale pour applications au dioxyde de carbone Type de document : texte imprimé Auteurs : Bartosz, Kus, Auteur ; Petter Nekså, Auteur Année de publication : 2014 Article en page(s) : pp. 2065–2078 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Novel  partial  admission  compressor;  oil-free  compressors;  oil-free  refrigeration;  CO2  turbo-compressor Résumé : A novel partial admission turbo compressor concept is proposed as an alternative to a conventional radial oil-free CO2 compressor. The concept aims at the improvement of the overall performance through the reduction of the non-stage windage and cooling losses enabled by compression at significantly reduced shaft speeds. Transient CFD analysis gives fairly optimistic prediction of more than 80% of base stage efficiency at around 1.4 total pressure ratio. The study shows potential for efficiency improvement by optimization of the shape and number of blades. The conceptual compressor may be an interesting alternative for commercial CO2 applications operating at close to critical pressures, provided that the deceleration of the gas in the diffuser is efficient. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001801 [article] Novel partial admission radial compressor for CO2 applications = Nouveau compresseur radial à admission radiale pour applications au dioxyde de carbone [texte imprimé] / Bartosz, Kus, Auteur ; Petter Nekså, Auteur . - 2014 . - pp. 2065–2078. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2065–2078 Mots-clés : Novel  partial  admission  compressor;  oil-free  compressors;  oil-free  refrigeration;  CO2  turbo-compressor Résumé : A novel partial admission turbo compressor concept is proposed as an alternative to a conventional radial oil-free CO2 compressor. The concept aims at the improvement of the overall performance through the reduction of the non-stage windage and cooling losses enabled by compression at significantly reduced shaft speeds. Transient CFD analysis gives fairly optimistic prediction of more than 80% of base stage efficiency at around 1.4 total pressure ratio. The study shows potential for efficiency improvement by optimization of the shape and number of blades. The conceptual compressor may be an interesting alternative for commercial CO2 applications operating at close to critical pressures, provided that the deceleration of the gas in the diffuser is efficient. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001801

Development of one-dimensional model for initial design and evaluation of oil-free Co2 turbo-compressor / Bartosz, Kus in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2079-2090 Titre : Development of one-dimensional model for initial design and evaluation of oil-free Co2 turbo-compressor Titre original : Développement d'un modèle unidimensionnel pour la conception initiale et l'évaluation d'un turbo-compresseur sans huile au CO2 Type de document : texte imprimé Auteurs : Bartosz, Kus, Auteur ; Petter Nekså, Auteur Année de publication : 2014 Article en page(s) : pp. 2079-2090 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Radial  turbo-compressor;  carbon  dioxide;  compression;  oil-free  compressors;  oil-free  refrigeration Résumé : A 1-dimenional tool for preliminary design and performance prediction of oil-free CO2 compressor is presented. The model describes high speed centrifugal compressor in a hermetic configuration supported on foil gas bearings. To give possibly comprehensive overview of the technology, a wide range of loss mechanisms is considered. The model predicts aerodynamic performance of the compressor as well as losses related to the windage of rotor and bearings and due to the internal cooling. Numerical investigation of different compressor stages was used to validate aerodynamic predictions of the 1D model. Maximal prediction discrepancy amounted 2% for efficiency and 5% for pressure ratio. The prediction of the total compressor efficiency was compared with test data from a 50 kW compressor published Sandia Laboratories. The predicted peak compressor efficiencies are between 66 and 67.5% while experimentally measured values are within 65–70% region. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001217 [article] Development of one-dimensional model for initial design and evaluation of oil-free Co2 turbo-compressor = Développement d'un modèle unidimensionnel pour la conception initiale et l'évaluation d'un turbo-compresseur sans huile au CO2 [texte imprimé] / Bartosz, Kus, Auteur ; Petter Nekså, Auteur . - 2014 . - pp. 2079-2090. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2079-2090 Mots-clés : Radial  turbo-compressor;  carbon  dioxide;  compression;  oil-free  compressors;  oil-free  refrigeration Résumé : A 1-dimenional tool for preliminary design and performance prediction of oil-free CO2 compressor is presented. The model describes high speed centrifugal compressor in a hermetic configuration supported on foil gas bearings. To give possibly comprehensive overview of the technology, a wide range of loss mechanisms is considered. The model predicts aerodynamic performance of the compressor as well as losses related to the windage of rotor and bearings and due to the internal cooling. Numerical investigation of different compressor stages was used to validate aerodynamic predictions of the 1D model. Maximal prediction discrepancy amounted 2% for efficiency and 5% for pressure ratio. The prediction of the total compressor efficiency was compared with test data from a 50 kW compressor published Sandia Laboratories. The predicted peak compressor efficiencies are between 66 and 67.5% while experimentally measured values are within 65–70% region. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001217

Studies on the performance of a small reciprocating compressor with different nitrogen–hydrocarbon mixtures / N. Lakshmi Narasimhan in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2091–2096 Titre : Studies on the performance of a small reciprocating compressor with different nitrogen–hydrocarbon mixtures Titre original : Etudes sur la performance d'un petit compresseur à piston avec différents mélanges d'azote et d'hydrocarbures Type de document : texte imprimé Auteurs : N. Lakshmi Narasimhan, Auteur ; G. Venkatarathnam, Auteur Année de publication : 2014 Article en page(s) : pp. 2091–2096 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Joule–Thomson  refrigerator;  refrigerant  mixtures;  compressor;  adiabatic  efficiency Résumé : The performance of Joule–Thomson refrigerators operating with mixed refrigerants depends on the composition of mixtures as well as the hardware employed. The role of mixture composition on the overall performance of the system has been well addressed in the open literature. What is not well known is the role of mixture composition on the performance of individual components such as the compressor, heat exchanger, etc. The adiabatic efficiency of a single stage Joule–Thomson refrigerator compressor was measured with thirty different nitrogen–hydrocarbon and neon–nitrogen–hydrocarbon mixtures. Our results show that the adiabatic efficiency of the compressor is independent of the mixture composition in the range of pressure ratios tested. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001758 [article] Studies on the performance of a small reciprocating compressor with different nitrogen–hydrocarbon mixtures = Etudes sur la performance d'un petit compresseur à piston avec différents mélanges d'azote et d'hydrocarbures [texte imprimé] / N. Lakshmi Narasimhan, Auteur ; G. Venkatarathnam, Auteur . - 2014 . - pp. 2091–2096. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2091–2096 Mots-clés : Joule–Thomson  refrigerator;  refrigerant  mixtures;  compressor;  adiabatic  efficiency Résumé : The performance of Joule–Thomson refrigerators operating with mixed refrigerants depends on the composition of mixtures as well as the hardware employed. The role of mixture composition on the overall performance of the system has been well addressed in the open literature. What is not well known is the role of mixture composition on the performance of individual components such as the compressor, heat exchanger, etc. The adiabatic efficiency of a single stage Joule–Thomson refrigerator compressor was measured with thirty different nitrogen–hydrocarbon and neon–nitrogen–hydrocarbon mixtures. Our results show that the adiabatic efficiency of the compressor is independent of the mixture composition in the range of pressure ratios tested. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001758

Mechanical sub-cooling vapor compression systems: Current status and future directions / Bilal Ahmed Qureshi in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2097–2110 Titre : Mechanical sub-cooling vapor compression systems: Current status and future directions Titre original : Sous-refroidissement mécanique des systémes de compression de vapeur: situation actuelle et orientations futures Type de document : texte imprimé Auteurs : Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur Année de publication : 2014 Article en page(s) : pp. 2097–2110 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Subcooling;  vapor  compression;  refrigeration  system;  performance  improvement Résumé : Using mechanical sub-cooling systems to increase COP of vapor compression cycles is a known method in literature to save energy and increase efficiency. Recently, much progress has been made with respect to investigation into its different aspects that can help to put it into practice. Numerical and experimental works are considered for the purpose of highlighting this progress. These can be categorized as: a) simulation of performance characteristics resulting from different refrigerant combinations in dedicated mechanical sub-cooling systems, b) variation in performance characteristics for a vapor compression cycle using integrated mechanical sub-cooling because of fouling, c) experimental study about consequences of employing a dedicated mechanical subcooling cycle with a simple vapor compression system, and d) experimental investigation about consequences of employing a subcooler in a two-stage refrigeration cycle. Some important results are discussed. Finally, some suggestions are made to provide direction into future research in this area to help put it into practice. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002041 [article] Mechanical sub-cooling vapor compression systems: Current status and future directions = Sous-refroidissement mécanique des systémes de compression de vapeur: situation actuelle et orientations futures [texte imprimé] / Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur . - 2014 . - pp. 2097–2110. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2097–2110 Mots-clés : Subcooling;  vapor  compression;  refrigeration  system;  performance  improvement Résumé : Using mechanical sub-cooling systems to increase COP of vapor compression cycles is a known method in literature to save energy and increase efficiency. Recently, much progress has been made with respect to investigation into its different aspects that can help to put it into practice. Numerical and experimental works are considered for the purpose of highlighting this progress. These can be categorized as: a) simulation of performance characteristics resulting from different refrigerant combinations in dedicated mechanical sub-cooling systems, b) variation in performance characteristics for a vapor compression cycle using integrated mechanical sub-cooling because of fouling, c) experimental study about consequences of employing a dedicated mechanical subcooling cycle with a simple vapor compression system, and d) experimental investigation about consequences of employing a subcooler in a two-stage refrigeration cycle. Some important results are discussed. Finally, some suggestions are made to provide direction into future research in this area to help put it into practice. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002041

Cycling losses in refrigeration equipment: An experimental evaluation / Giacomo Bagarella in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2111–2118 Titre : Cycling losses in refrigeration equipment: An experimental evaluation Titre original : Pertes lors du cyclage dans les équipements frigorifiques: une évaluation expérimentale Type de document : texte imprimé Auteurs : Giacomo Bagarella, Auteur ; Renato M. Lazzarin, Auteur ; Biagio Lamanna, Auteur Année de publication : 2014 Article en page(s) : pp. 2111–2118 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Cycling  losses;  on–off;  modulation;  refrigeration;  thermostatic  expansion  valve;  electronic  Expansion  Valve Résumé : Cycling losses may be defined as those inefficiencies that reduce the performances of units during the transient period. They may be quantified by comparing the Energy Efficiency Ratio (EER) of a cycling unit and the EER of the same unit working continuously. The on-off control is the most widespread strategy for modulating; therefore, a reliable evaluation of cycling losses is fundamental to assess the EER of the system. The mentioned losses have been experimentally evaluated on a test rig, and logged data demonstrate a loss up to 13% with respect to steady operations when the load factor is lower than 10% and a Thermostatic Expansion Valve (TEV) is used. The insertion of a solenoid valve in series with the TEV can reduce the losses but the best results are obtained by using the Electronic Expansion Valve (EEV) instead of the TEV. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001989 [article] Cycling losses in refrigeration equipment: An experimental evaluation = Pertes lors du cyclage dans les équipements frigorifiques: une évaluation expérimentale [texte imprimé] / Giacomo Bagarella, Auteur ; Renato M. Lazzarin, Auteur ; Biagio Lamanna, Auteur . - 2014 . - pp. 2111–2118. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2111–2118 Mots-clés : Cycling  losses;  on–off;  modulation;  refrigeration;  thermostatic  expansion  valve;  electronic  Expansion  Valve Résumé : Cycling losses may be defined as those inefficiencies that reduce the performances of units during the transient period. They may be quantified by comparing the Energy Efficiency Ratio (EER) of a cycling unit and the EER of the same unit working continuously. The on-off control is the most widespread strategy for modulating; therefore, a reliable evaluation of cycling losses is fundamental to assess the EER of the system. The mentioned losses have been experimentally evaluated on a test rig, and logged data demonstrate a loss up to 13% with respect to steady operations when the load factor is lower than 10% and a Thermostatic Expansion Valve (TEV) is used. The insertion of a solenoid valve in series with the TEV can reduce the losses but the best results are obtained by using the Electronic Expansion Valve (EEV) instead of the TEV. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001989

Alternative evaluation of liquid-to-suction heat exchange in the refrigeration cycle / Christian J.L. Hermes in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2119–2127 Titre : Alternative evaluation of liquid-to-suction heat exchange in the refrigeration cycle Titre original : Évaluation alternative de l'echangeur liquide-vapeur dans le cycle frigorifique Type de document : texte imprimé Auteurs : Christian J.L. Hermes, Auteur Année de publication : 2014 Article en page(s) : pp. 2119–2127 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Liquid–vapor  exchanger;  mechanical  vapor  compression;  thermodynamic  cycle;  COP Résumé : This paper advances a thermodynamic study of the effects of the liquid-to-suction heat exchange in vapor compression refrigeration cycles. The analysis was carried out for refrigerants of current interest, such as R134a, R22, R290, R410A, R600a and R717 assuming the cooling capacity as a constraint so that the evaporating pressure is free to vary. It is shown that the coefficient of performance may either increase or decrease when an internal heat exchanger is introduced into the cycle, depending not only on the working pressures, the heat exchanger effectiveness, the specific heat ratio, and the available latent heat to produce additional refrigerating effect, but also on the change experienced by the evaporating pressure. The thermodynamic conditions required for performance improvement are also discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001540 [article] Alternative evaluation of liquid-to-suction heat exchange in the refrigeration cycle = Évaluation alternative de l'echangeur liquide-vapeur dans le cycle frigorifique [texte imprimé] / Christian J.L. Hermes, Auteur . - 2014 . - pp. 2119–2127. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2119–2127 Mots-clés : Liquid–vapor  exchanger;  mechanical  vapor  compression;  thermodynamic  cycle;  COP Résumé : This paper advances a thermodynamic study of the effects of the liquid-to-suction heat exchange in vapor compression refrigeration cycles. The analysis was carried out for refrigerants of current interest, such as R134a, R22, R290, R410A, R600a and R717 assuming the cooling capacity as a constraint so that the evaporating pressure is free to vary. It is shown that the coefficient of performance may either increase or decrease when an internal heat exchanger is introduced into the cycle, depending not only on the working pressures, the heat exchanger effectiveness, the specific heat ratio, and the available latent heat to produce additional refrigerating effect, but also on the change experienced by the evaporating pressure. The thermodynamic conditions required for performance improvement are also discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001540

State-space model for dynamic behavior of vapor compression liquid chiller / Ye, Yao in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2128–2147 Titre : State-space model for dynamic behavior of vapor compression liquid chiller Titre original : Modèle espace-état du comportement dynamique d’une refroidisseur de liquide à compression de vapeur Type de document : texte imprimé Auteurs : Ye, Yao, Auteur ; Mengwei, Huang, Auteur ; Jing Chen, Auteur Année de publication : 2014 Article en page(s) : pp. 2128–2147 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : State-space  model;  dynamic  response;  vapor  compression;  liquid  chiller;  R-134A Résumé : A state-space model has been developed to investigate the dynamic behaviors of refrigeration system. By using vector-matrix notation and linearization, the ordinary differential equations describing the chiller's dynamic thermal behaviors are transformed into a representation form of the state space. The model has been validated by a series of dynamic response experiments of a chiller with the refrigerant R-134a. The average errors of the model results compared with the experimental data are all less than 10% in the experimental cases. Afterward, the model is used to investigate the transient behaviors of the exit cold carrier temperature of evaporator under different A disturbances. The state-space model developed in this study helps us have a good idea of the dynamic performance of a refrigeration system under transient conditions and design optimized control strategies for a high-energy-efficiency HVAC system. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001187 [article] State-space model for dynamic behavior of vapor compression liquid chiller = Modèle espace-état du comportement dynamique d’une refroidisseur de liquide à compression de vapeur [texte imprimé] / Ye, Yao, Auteur ; Mengwei, Huang, Auteur ; Jing Chen, Auteur . - 2014 . - pp. 2128–2147. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2128–2147 Mots-clés : State-space  model;  dynamic  response;  vapor  compression;  liquid  chiller;  R-134A Résumé : A state-space model has been developed to investigate the dynamic behaviors of refrigeration system. By using vector-matrix notation and linearization, the ordinary differential equations describing the chiller's dynamic thermal behaviors are transformed into a representation form of the state space. The model has been validated by a series of dynamic response experiments of a chiller with the refrigerant R-134a. The average errors of the model results compared with the experimental data are all less than 10% in the experimental cases. Afterward, the model is used to investigate the transient behaviors of the exit cold carrier temperature of evaporator under different A disturbances. The state-space model developed in this study helps us have a good idea of the dynamic performance of a refrigeration system under transient conditions and design optimized control strategies for a high-energy-efficiency HVAC system. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001187

The substitution of R134a with R744: / Ciro, Aprea in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2148–2159 Titre : The substitution of R134a with R744: : an exergetic analysis based on experimental data Titre original : Le remplacement du R134a par le R744: une analyse exergétique basée sur des données expérimentales Type de document : texte imprimé Auteurs : Ciro, Aprea, Auteur ; Adriana Greco, Auteur ; Angelo Maiorino, Auteur Année de publication : 2014 Article en page(s) : pp. 2148–2159 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : CO2;  R134a;  transcritical  cycle;  exergetic  analysis;  exergy  loss Résumé : This paper deals with the problem of R314a substitution with a natural refrigerant fluid. A comparison is performed between R134a and R744 (CO2). R134a is a hydrofluorocarbon with a large direct warming impact (GWP), whereas the R744 contribution is negligible. A comparative exergetic analysis, carried out with experimental tests, has been presented. This paper compares a commercial R134a refrigeration plant and a prototype R744 system working in a trans-critical cycle. Based on the experimental data an exergetic analysis has been carried out on the overall plant and on each device. The overall exergetic performances of the classical vapour compression plant working with R134a are consistently better than that of R744 (from a minimum of 20 to a maximum of 44%). The performance of the individual components of the plant has been analyzed, in order to pinpoint those contributing most to the decrease in the exergetic performance of R744. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300159X [article] The substitution of R134a with R744: = Le remplacement du R134a par le R744: une analyse exergétique basée sur des données expérimentales : an exergetic analysis based on experimental data [texte imprimé] / Ciro, Aprea, Auteur ; Adriana Greco, Auteur ; Angelo Maiorino, Auteur . - 2014 . - pp. 2148–2159. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2148–2159 Mots-clés : CO2;  R134a;  transcritical  cycle;  exergetic  analysis;  exergy  loss Résumé : This paper deals with the problem of R314a substitution with a natural refrigerant fluid. A comparison is performed between R134a and R744 (CO2). R134a is a hydrofluorocarbon with a large direct warming impact (GWP), whereas the R744 contribution is negligible. A comparative exergetic analysis, carried out with experimental tests, has been presented. This paper compares a commercial R134a refrigeration plant and a prototype R744 system working in a trans-critical cycle. Based on the experimental data an exergetic analysis has been carried out on the overall plant and on each device. The overall exergetic performances of the classical vapour compression plant working with R134a are consistently better than that of R744 (from a minimum of 20 to a maximum of 44%). The performance of the individual components of the plant has been analyzed, in order to pinpoint those contributing most to the decrease in the exergetic performance of R744. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300159X

Thermodynamic optimization of combined power and refrigeration cycle using binary organic working fluid / H. Abed in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2160–2168 Titre : Thermodynamic optimization of combined power and refrigeration cycle using binary organic working fluid Titre original : Optimisation thermodynamique du cycle de cogénération d'électricité et de froid utilisant un fluide actif organique binaire Type de document : texte imprimé Auteurs : H. Abed, Auteur ; K. Atashkari, Auteur ; A. Niazmehr, Auteur Année de publication : 2014 Article en page(s) : pp. 2160–2168 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Thermal  power;  cooling  cycle;  organic  working  fluid;  multi-objective  optimization Résumé : A combined cycle has been proposed for the production of power and refrigeration simultaneously. The cycle can be driven by low grade heat sources such as solar, geothermal and waste heat sources. In the first part of this paper, a model has been developed to perform a parametric analysis to evaluate the effects of important parameters on the performance of the cycle, which is a combination of Rankine and absorption refrigeration cycle. Propane–decane has been used as an organic dual working fluid. In the second part, multi objective genetic algorithm is applied for Pareto approach optimization of the cycle. There are three important conflicting objectives namely, turbine work (Wt), cooling capacity (Qc) and thermal efficiency (ηth) which have been selected to find the best possible combination of these performance parameters. Optimization has been carried out by varying turbine inlet pressure, superheated temperature and condenser temperature as design variables. Among optimum design parameters, a trade-off point is selected. Turbine inlet pressure, superheated temperature and condenser temperature are assumed to be 29.5 bar, 410 K and 386.6 K respectively as the values assigned to this point. Furthermore, it has been shown that some interesting and important relationships can be discovered among optimal objective functions and decision variables involved, consequently. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001606 [article] Thermodynamic optimization of combined power and refrigeration cycle using binary organic working fluid = Optimisation thermodynamique du cycle de cogénération d'électricité et de froid utilisant un fluide actif organique binaire [texte imprimé] / H. Abed, Auteur ; K. Atashkari, Auteur ; A. Niazmehr, Auteur . - 2014 . - pp. 2160–2168. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2160–2168 Mots-clés : Thermal  power;  cooling  cycle;  organic  working  fluid;  multi-objective  optimization Résumé : A combined cycle has been proposed for the production of power and refrigeration simultaneously. The cycle can be driven by low grade heat sources such as solar, geothermal and waste heat sources. In the first part of this paper, a model has been developed to perform a parametric analysis to evaluate the effects of important parameters on the performance of the cycle, which is a combination of Rankine and absorption refrigeration cycle. Propane–decane has been used as an organic dual working fluid. In the second part, multi objective genetic algorithm is applied for Pareto approach optimization of the cycle. There are three important conflicting objectives namely, turbine work (Wt), cooling capacity (Qc) and thermal efficiency (ηth) which have been selected to find the best possible combination of these performance parameters. Optimization has been carried out by varying turbine inlet pressure, superheated temperature and condenser temperature as design variables. Among optimum design parameters, a trade-off point is selected. Turbine inlet pressure, superheated temperature and condenser temperature are assumed to be 29.5 bar, 410 K and 386.6 K respectively as the values assigned to this point. Furthermore, it has been shown that some interesting and important relationships can be discovered among optimal objective functions and decision variables involved, consequently. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001606

On the parameters of performance of combined refrigeration and power plants / José Alexandre Matelli in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2169-2175 Titre : On the parameters of performance of combined refrigeration and power plants Titre original : Sur les paramètres de performance de centrales de cogénération de froid et d'électricité Type de document : texte imprimé Auteurs : José Alexandre Matelli, Auteur ; Edson Bazzo, Auteur Année de publication : 2014 Article en page(s) : pp. 2169-2175 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Cogeneration;  efficiency;  primary  energy Résumé : Combined Refrigeration and Power (CRP) plants generate power and refrigerate a thermal load simultaneously from the same fuel. The overall efficiency is a parameter based on the first law generally used to quantify the fuel saving, in the sense that a plant that has greater overall efficiency saves more fuel than others to generate the same useful energy. However, the literature shows that the overall efficiency and other parameters of performance are defined in several different ways. This heterogeneity is not desirable when considering a coherent and universally accepted parameter of performance based on the first law. In this work, some parameters found in the literature are critically analyzed in order to indicate the most proper one. The indicated parameter is then formally analyzed in order to verify its mathematical consistency. The primary energy rate is considered the most well-suited parameter based on the first law to characterize the performance of a CRP plant. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001588 [article] On the parameters of performance of combined refrigeration and power plants = Sur les paramètres de performance de centrales de cogénération de froid et d'électricité [texte imprimé] / José Alexandre Matelli, Auteur ; Edson Bazzo, Auteur . - 2014 . - pp. 2169-2175. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2169-2175 Mots-clés : Cogeneration;  efficiency;  primary  energy Résumé : Combined Refrigeration and Power (CRP) plants generate power and refrigerate a thermal load simultaneously from the same fuel. The overall efficiency is a parameter based on the first law generally used to quantify the fuel saving, in the sense that a plant that has greater overall efficiency saves more fuel than others to generate the same useful energy. However, the literature shows that the overall efficiency and other parameters of performance are defined in several different ways. This heterogeneity is not desirable when considering a coherent and universally accepted parameter of performance based on the first law. In this work, some parameters found in the literature are critically analyzed in order to indicate the most proper one. The indicated parameter is then formally analyzed in order to verify its mathematical consistency. The primary energy rate is considered the most well-suited parameter based on the first law to characterize the performance of a CRP plant. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001588

Effect of the header pressure drop induced flow maldistribution on the microchannel evaporator performance / Hanfei Tuo in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2176–2186 Titre : Effect of the header pressure drop induced flow maldistribution on the microchannel evaporator performance Titre original : Effet de la mauvaise distribution de l'écoulement engendrée par la chute de pression dans le collecteur sur la performance d'un évaporateur à microcanaux Type de document : texte imprimé Auteurs : Hanfei Tuo, Auteur ; Pega Hrnjak, Auteur Année de publication : 2014 Article en page(s) : pp. 2176–2186 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Microchannel;  evaporator;  air-conditioning  system;  flow  distribution;  header Résumé : This paper presents an experimental and numerical investigation of the flow maldistribution caused by the pressure drop in headers and its impact on the performance of a microchannel evaporator with horizontal headers and vertically oriented tubes. Experimental results show that the flash gas bypass method almost eliminates the quality induced maldistribution. However, refrigerant flow maldistribution caused by the header pressure drop still exists. This is mainly because the pressure drop along the headers results in uneven pressure difference and therefore non-uniform liquid refrigerant mass flow rate across each microchannel tube. A microchannel evaporator model validated by experimental results is employed to quantify header pressure drop induced flow maldistribution. Parametric analysis reveals that such maldistribution impact is significantly reduced by enlarging the outlet header size, increasing heat exchanger aspect ratio, or reducing the microchannel size while other parameters are kept constant. When ratio of outlet header to the total evaporator pressure drop is less than 30%, the cooling capacity reduction is limited below 3%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001497 [article] Effect of the header pressure drop induced flow maldistribution on the microchannel evaporator performance = Effet de la mauvaise distribution de l'écoulement engendrée par la chute de pression dans le collecteur sur la performance d'un évaporateur à microcanaux [texte imprimé] / Hanfei Tuo, Auteur ; Pega Hrnjak, Auteur . - 2014 . - pp. 2176–2186. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2176–2186 Mots-clés : Microchannel;  evaporator;  air-conditioning  system;  flow  distribution;  header Résumé : This paper presents an experimental and numerical investigation of the flow maldistribution caused by the pressure drop in headers and its impact on the performance of a microchannel evaporator with horizontal headers and vertically oriented tubes. Experimental results show that the flash gas bypass method almost eliminates the quality induced maldistribution. However, refrigerant flow maldistribution caused by the header pressure drop still exists. This is mainly because the pressure drop along the headers results in uneven pressure difference and therefore non-uniform liquid refrigerant mass flow rate across each microchannel tube. A microchannel evaporator model validated by experimental results is employed to quantify header pressure drop induced flow maldistribution. Parametric analysis reveals that such maldistribution impact is significantly reduced by enlarging the outlet header size, increasing heat exchanger aspect ratio, or reducing the microchannel size while other parameters are kept constant. When ratio of outlet header to the total evaporator pressure drop is less than 30%, the cooling capacity reduction is limited below 3%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001497

New approach to improve performance by venting periodic reverse vapor flow in microchannel evaporator / Hanfei Tuo in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2187–2195 Titre : New approach to improve performance by venting periodic reverse vapor flow in microchannel evaporator Titre original : Nouvelle approche pour améliorer la performance en évacuant l'écoulement inverse périodique de vapeur à l'intérieur d'un évaporateur à microcanaux Type de document : texte imprimé Auteurs : Hanfei Tuo, Auteur ; Pega Hrnjak, Auteur Année de publication : 2014 Article en page(s) : pp. 2187–2195 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Vapour;  periodic  reverse  flow;  boiling;  fluctuation;  venting;  evaporator;  microchannel Résumé : This paper presents a proposal for a venting reverse vapor in flash gas removal A/C system in order to improve refrigerant distribution and reduce pressure drop in microchannel evaporator and thus increase system efficiency. Introduction to the reverse vapor flow observed in parallel flow microchannel evaporator was presented in earlier IJR paper by the authors. An experimental comparison of the A/C system with new approach to an FGB system revealed that vapor venting provided a 5% increase of cooling capacity and 3% of COP when operated at identical test conditions, while the maximum COP improvement was approximately 10%–12% when capacity is matched by reduction of compressor speed. The improvement compared to direct expansion system was significantly higher. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001473 [article] New approach to improve performance by venting periodic reverse vapor flow in microchannel evaporator = Nouvelle approche pour améliorer la performance en évacuant l'écoulement inverse périodique de vapeur à l'intérieur d'un évaporateur à microcanaux [texte imprimé] / Hanfei Tuo, Auteur ; Pega Hrnjak, Auteur . - 2014 . - pp. 2187–2195. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2187–2195 Mots-clés : Vapour;  periodic  reverse  flow;  boiling;  fluctuation;  venting;  evaporator;  microchannel Résumé : This paper presents a proposal for a venting reverse vapor in flash gas removal A/C system in order to improve refrigerant distribution and reduce pressure drop in microchannel evaporator and thus increase system efficiency. Introduction to the reverse vapor flow observed in parallel flow microchannel evaporator was presented in earlier IJR paper by the authors. An experimental comparison of the A/C system with new approach to an FGB system revealed that vapor venting provided a 5% increase of cooling capacity and 3% of COP when operated at identical test conditions, while the maximum COP improvement was approximately 10%–12% when capacity is matched by reduction of compressor speed. The improvement compared to direct expansion system was significantly higher. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001473

Refrigerant distribution in the vertical header of the microchannel heat exchanger / Yang Zou in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2196-2208 Titre : Refrigerant distribution in the vertical header of the microchannel heat exchanger : measurement and visualization of R410A flow Titre original : Distribution du frigorigène dans le collecteur vertical d'un échangeur de chaleur à microcanaux – Mesures et visualisation de l'écoulement du R410A Type de document : texte imprimé Auteurs : Yang Zou, Auteur ; Pega S. Hrnjak, Auteur Année de publication : 2014 Article en page(s) : pp. 2196-2208 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Two-phase  flow;  refrigerant  distribution;  vertical  header;  microchannel;  heat  exchanger Résumé : This paper presents the R410A adiabatic upward flow in three vertical headers of microchannel heat exchangers. All microchannel tubes are inserted into the half depth. The objectives are to explore what affects R410A distribution and attempt to predict the distribution. R410A is circulated into the header through the (5 or 10) tubes in the bottom pass and exits through the (5 or 10) tubes in the top pass. It represents the flow in the outdoor heat exchanger (usually used as the condenser) when it is used as the evaporator in the heat pump mode of reversible systems. The quality was typically varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h−1 per tube. The best distribution was observed at high mass flux and low quality. The experiment and visualization reveals the flow pattern effects in terms of homogeneity and momentum. The churn flow had better distribution since the two-phase mixture was more homogenous and the distribution was better at high mass flux in the header because the higher momentum liquid was able to reach the top exit tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001102 [article] Refrigerant distribution in the vertical header of the microchannel heat exchanger = Distribution du frigorigène dans le collecteur vertical d'un échangeur de chaleur à microcanaux – Mesures et visualisation de l'écoulement du R410A : measurement and visualization of R410A flow [texte imprimé] / Yang Zou, Auteur ; Pega S. Hrnjak, Auteur . - 2014 . - pp. 2196-2208. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2196-2208 Mots-clés : Two-phase  flow;  refrigerant  distribution;  vertical  header;  microchannel;  heat  exchanger Résumé : This paper presents the R410A adiabatic upward flow in three vertical headers of microchannel heat exchangers. All microchannel tubes are inserted into the half depth. The objectives are to explore what affects R410A distribution and attempt to predict the distribution. R410A is circulated into the header through the (5 or 10) tubes in the bottom pass and exits through the (5 or 10) tubes in the top pass. It represents the flow in the outdoor heat exchanger (usually used as the condenser) when it is used as the evaporator in the heat pump mode of reversible systems. The quality was typically varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h−1 per tube. The best distribution was observed at high mass flux and low quality. The experiment and visualization reveals the flow pattern effects in terms of homogeneity and momentum. The churn flow had better distribution since the two-phase mixture was more homogenous and the distribution was better at high mass flux in the header because the higher momentum liquid was able to reach the top exit tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001102

Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf) / Giovanni Di Nicola in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2209–2215 Titre : Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf) Titre original : Mesures de la masse volumique du liquide sous-refroidi et mesures PvT lors de la phase gazeuse pour le 3,3,3-trifluoroprop-1-ène (R1243zf) Type de document : texte imprimé Auteurs : Giovanni Di Nicola, Auteur ; J. Steven Brown, Auteur ; Laura Fedele, Auteur Année de publication : 2014 Article en page(s) : pp. 2209–2215 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : 3,3,3-Trifluoroprop-1-ene  (R1243zf);  CF3CHdouble  bond;  length  as  m-dashCH2;  CAS  number  677-21-4;  liquid  density;  PvT  behavior;  tait  correlation Résumé : The fluorinated propene isomer R1243zf (3,3,3-trifluoroprop-1-ene, CF3CFdouble bond; length as m-dashCH2, CAS number 677-21-4) is a potential alternative refrigerant with short atmospheric lifetime, low-GWP, and low acute toxicity; however, because of its flammability it is being considered primarily as a component in blends. In this paper, 302 subcooled liquid density data and 101 vapor phase PvT data are presented. The subcooled liquid density data are measured for eight isotherms, evenly separated approximately from 283 K to 353 K, for pressures from close to saturation to 35 MPa and the vapor phase PvT data are measured for six isochores for temperatures approximately from 278 K to 368 K and for pressures approximately from 260 kPa to 912 kPa. In addition, a saturated liquid density correlation, a Tait correlation for the subcooled liquid density data, and a Martin–Hou Equation of State for the vapor phase PvT data are presented. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002089 [article] Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf) = Mesures de la masse volumique du liquide sous-refroidi et mesures PvT lors de la phase gazeuse pour le 3,3,3-trifluoroprop-1-ène (R1243zf) [texte imprimé] / Giovanni Di Nicola, Auteur ; J. Steven Brown, Auteur ; Laura Fedele, Auteur . - 2014 . - pp. 2209–2215. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2209–2215 Mots-clés : 3,3,3-Trifluoroprop-1-ene  (R1243zf);  CF3CHdouble  bond;  length  as  m-dashCH2;  CAS  number  677-21-4;  liquid  density;  PvT  behavior;  tait  correlation Résumé : The fluorinated propene isomer R1243zf (3,3,3-trifluoroprop-1-ene, CF3CFdouble bond; length as m-dashCH2, CAS number 677-21-4) is a potential alternative refrigerant with short atmospheric lifetime, low-GWP, and low acute toxicity; however, because of its flammability it is being considered primarily as a component in blends. In this paper, 302 subcooled liquid density data and 101 vapor phase PvT data are presented. The subcooled liquid density data are measured for eight isotherms, evenly separated approximately from 283 K to 353 K, for pressures from close to saturation to 35 MPa and the vapor phase PvT data are measured for six isochores for temperatures approximately from 278 K to 368 K and for pressures approximately from 260 kPa to 912 kPa. In addition, a saturated liquid density correlation, a Tait correlation for the subcooled liquid density data, and a Martin–Hou Equation of State for the vapor phase PvT data are presented. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002089

Behavior of isobaric heat capacity of R32 in the gas phase / Noboru Kagawa in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2216-2222 Titre : Behavior of isobaric heat capacity of R32 in the gas phase Titre original : Comportement de la capacité thermique isobare de R32 dans la phase gazeuse Type de document : texte imprimé Auteurs : Noboru Kagawa, Auteur ; Atsushi Matsuguchi, Auteur ; Kenichi Yamaya, Auteur Année de publication : 2014 Article en page(s) : pp. 2216-2222 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Heat  capacity;  R32;  gas;  ideal  gas;  saturation;  calorimetry Résumé : The specific isobaric heat capacity was measured for R 32 (difluoromethane) in the gas phase. Twenty-one measurements for R 32 were obtained at temperatures from 282 to 319 K and at pressures from 1.0 to 2.4 MPa, which are very close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 15 kPa. The expanded uncertainty for cp is estimated to range from 15 to 47 J kg−1 K−1. The measurements were compared with available equations of state. Based on the measurements, heat capacity curves of the ideal gas and saturated vapor of R 32 were specified. These data will be very useful for improving available models, especially for correcting behavior in the gas phase, so as to represent reliable thermodynamic properties of R 32 and refrigerant mixtures with R32 that are used for refrigeration and air conditioning systems. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001825 [article] Behavior of isobaric heat capacity of R32 in the gas phase = Comportement de la capacité thermique isobare de R32 dans la phase gazeuse [texte imprimé] / Noboru Kagawa, Auteur ; Atsushi Matsuguchi, Auteur ; Kenichi Yamaya, Auteur . - 2014 . - pp. 2216-2222. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2216-2222 Mots-clés : Heat  capacity;  R32;  gas;  ideal  gas;  saturation;  calorimetry Résumé : The specific isobaric heat capacity was measured for R 32 (difluoromethane) in the gas phase. Twenty-one measurements for R 32 were obtained at temperatures from 282 to 319 K and at pressures from 1.0 to 2.4 MPa, which are very close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 15 kPa. The expanded uncertainty for cp is estimated to range from 15 to 47 J kg−1 K−1. The measurements were compared with available equations of state. Based on the measurements, heat capacity curves of the ideal gas and saturated vapor of R 32 were specified. These data will be very useful for improving available models, especially for correcting behavior in the gas phase, so as to represent reliable thermodynamic properties of R 32 and refrigerant mixtures with R32 that are used for refrigeration and air conditioning systems. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001825

Modeling the surface tension of refrigerant mixtures with linear gradient theory / Shahin Khosharay in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2223–2232 Titre : Modeling the surface tension of refrigerant mixtures with linear gradient theory Titre original : Modélisation de la tension superficielle des mélanges de frigorigènes à l'aide de la théorie du gradient linéaire Type de document : texte imprimé Auteurs : Shahin Khosharay, Auteur ; Masoumeh Seyfi Mazraeno, Auteur ; Farshad Varaminian, Auteur Année de publication : 2014 Article en page(s) : pp. 2223–2232 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Surface  tension;  Heyen  equation  of  state;  linear  gradient  theory;  refrigerants Résumé : In this work, the surface tensions of pure refrigerants and binary, ternary, and quaternary refrigerant mixtures were modeled. A simple and reliable model was used, combining the linear gradient theory (LGT) with the Heyen equation of state (Heyen EOS), to take advantage of the well described equilibrium densities of phases and surface tensions of refrigerant mixtures. The binary interaction parameters of the Heyen EOS were determined to improve the description of the equilibrium properties of bulk phases. A new correlation for the influence parameter is also proposed that is a function of the densities of the bulk phases. The geometric mixing rule for the mixture influence parameter is also selected without adjustable coefficients, making this model predictive. The surface tensions predicted by the model agree well with experimental data for pure refrigerants and binary, ternary, and quaternary refrigerant mixtures (overall AAD∼3.27%). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001035 [article] Modeling the surface tension of refrigerant mixtures with linear gradient theory = Modélisation de la tension superficielle des mélanges de frigorigènes à l'aide de la théorie du gradient linéaire [texte imprimé] / Shahin Khosharay, Auteur ; Masoumeh Seyfi Mazraeno, Auteur ; Farshad Varaminian, Auteur . - 2014 . - pp. 2223–2232. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2223–2232 Mots-clés : Surface  tension;  Heyen  equation  of  state;  linear  gradient  theory;  refrigerants Résumé : In this work, the surface tensions of pure refrigerants and binary, ternary, and quaternary refrigerant mixtures were modeled. A simple and reliable model was used, combining the linear gradient theory (LGT) with the Heyen equation of state (Heyen EOS), to take advantage of the well described equilibrium densities of phases and surface tensions of refrigerant mixtures. The binary interaction parameters of the Heyen EOS were determined to improve the description of the equilibrium properties of bulk phases. A new correlation for the influence parameter is also proposed that is a function of the densities of the bulk phases. The geometric mixing rule for the mixture influence parameter is also selected without adjustable coefficients, making this model predictive. The surface tensions predicted by the model agree well with experimental data for pure refrigerants and binary, ternary, and quaternary refrigerant mixtures (overall AAD∼3.27%). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001035

Particle shape effect on the viscosity and thermal conductivity of ZnO nanofluids / Jisun Jeong in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2233–2241 Titre : Particle shape effect on the viscosity and thermal conductivity of ZnO nanofluids Titre original : Effet de forme de particules sur la viscosité et la conductivité thermique de nanofrigorigènes ZnO Type de document : texte imprimé Auteurs : Jisun Jeong, Auteur ; Chengguo, Li, Auteur ; Younghwan, Kwon, Auteur Année de publication : 2014 Article en page(s) : pp. 2233–2241 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : ZnO  nanofluids;  heat  transfer;  thermal  conductivity;  viscosity;  shape  effect Résumé : The viscosity and thermal conductivity of ZnO nanofluids with nanoparticle shapes of nearly rectangular and of sphere, were experimentally investigated under various volume concentrations of the nanoparticles, ranging from 0.05 to 5.0 vol.%. The viscosity of the nanofluids increased with increases in the volume concentration by up to 69%. In addition, the enhancement of the viscosity of the nearly rectangular shape nanoparticles was found to be greater by 7.7%, than that of the spherical nanoparticles. The thermal conductivity of the ZnO nanofluids increased by up to 12% and 18% at 5.0 vol.% for the spherical and the nearly rectangular shape nanoparticles, respectively, compared to that of the base fluid (water). The shape of the particles is found to have a significant effect on the viscosity and thermal conductivity enhancements. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002028 [article] Particle shape effect on the viscosity and thermal conductivity of ZnO nanofluids = Effet de forme de particules sur la viscosité et la conductivité thermique de nanofrigorigènes ZnO [texte imprimé] / Jisun Jeong, Auteur ; Chengguo, Li, Auteur ; Younghwan, Kwon, Auteur . - 2014 . - pp. 2233–2241. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2233–2241 Mots-clés : ZnO  nanofluids;  heat  transfer;  thermal  conductivity;  viscosity;  shape  effect Résumé : The viscosity and thermal conductivity of ZnO nanofluids with nanoparticle shapes of nearly rectangular and of sphere, were experimentally investigated under various volume concentrations of the nanoparticles, ranging from 0.05 to 5.0 vol.%. The viscosity of the nanofluids increased with increases in the volume concentration by up to 69%. In addition, the enhancement of the viscosity of the nearly rectangular shape nanoparticles was found to be greater by 7.7%, than that of the spherical nanoparticles. The thermal conductivity of the ZnO nanofluids increased by up to 12% and 18% at 5.0 vol.% for the spherical and the nearly rectangular shape nanoparticles, respectively, compared to that of the base fluid (water). The shape of the particles is found to have a significant effect on the viscosity and thermal conductivity enhancements. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002028

Modeling and thermodynamic consistency of solubility data of refrigerants in ionic liquids / Claudio A. Faúndez in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2242–2250 Titre : Modeling and thermodynamic consistency of solubility data of refrigerants in ionic liquids Titre original : Modélisation et cohérence thermodynamique des données de solubilité des frigorigènes dans les liquides ioniques Type de document : texte imprimé Auteurs : Claudio A. Faúndez, Auteur ; Luis A. Barrientos, Auteur ; José O. Valderrama, Auteur Année de publication : 2014 Article en page(s) : pp. 2242–2250 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Refrigerants;  ionic-liquids;  equation  of  state;  Kwak–Mansoori;  thermodynamic  consistency Résumé : Phase equilibrium data of temperature, pressure and solubility (T-P-x) of hydrofluorocarbon-type refrigerants in different types of ionic liquids over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. Experimental data taken from the literature for nineteen binary mixtures refrigerant + ionic liquids with a total of forty eight isothermal data sets are considered in the study. The modified Peng–Robinson equation of state proposed by Kwak and Mansoori is used for correlating the P-T-x data and a flexible thermodynamic consistency method is applied to analyze the data. Modeling is found acceptable in all cases, meaning that deviations in correlating the data are low, proving at the same time the claimed flexibility of a well-founded model that uses simple van der Waals mixing rules. Thirty eight data sets resulted to be thermodynamically consistent, nine were found to be not-fully consistent and only one set was found to be thermodynamically inconsistent. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001539 [article] Modeling and thermodynamic consistency of solubility data of refrigerants in ionic liquids = Modélisation et cohérence thermodynamique des données de solubilité des frigorigènes dans les liquides ioniques [texte imprimé] / Claudio A. Faúndez, Auteur ; Luis A. Barrientos, Auteur ; José O. Valderrama, Auteur . - 2014 . - pp. 2242–2250. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2242–2250 Mots-clés : Refrigerants;  ionic-liquids;  equation  of  state;  Kwak–Mansoori;  thermodynamic  consistency Résumé : Phase equilibrium data of temperature, pressure and solubility (T-P-x) of hydrofluorocarbon-type refrigerants in different types of ionic liquids over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. Experimental data taken from the literature for nineteen binary mixtures refrigerant + ionic liquids with a total of forty eight isothermal data sets are considered in the study. The modified Peng–Robinson equation of state proposed by Kwak and Mansoori is used for correlating the P-T-x data and a flexible thermodynamic consistency method is applied to analyze the data. Modeling is found acceptable in all cases, meaning that deviations in correlating the data are low, proving at the same time the claimed flexibility of a well-founded model that uses simple van der Waals mixing rules. Thirty eight data sets resulted to be thermodynamically consistent, nine were found to be not-fully consistent and only one set was found to be thermodynamically inconsistent. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001539

Partialization losses of ON/OFF operation of water-to-water refrigeration/heat-pump units / J. M. Corberán in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2251–2261 Titre : Partialization losses of ON/OFF operation of water-to-water refrigeration/heat-pump units Titre original : Pertes de partialisation lors du fonctionnement “tout-ou-rien” des systèmes frigorifiques eau-eau /pompes à chaleur Type de document : texte imprimé Auteurs : J. M. Corberán, Auteur ; D. Donadello, Auteur ; I. Martínez-Galván, Auteur Année de publication : 2014 Article en page(s) : pp. 2251–2261 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Part  load  operation;  heat  pump  performance;  partialization  losses;  COP Résumé : This paper presents the results of an experimental campaign for the characterization of the dynamic behavior of a water-to-water refrigeration/heat-pump unit under ON/OFF operation. The unit was previously tested at different water inlet temperatures under steady state conditions, and a very good agreement was found between the instantaneous dynamic performance of the heat pump and the corresponding quasi-steady state operation. In parallel, a series of tests were carried out to quantify the coefficient of performance (COP) degradation as a function of the load ratio, and a simple formula for the Part Load Factor is presented. Results lead to the conclusion that the only non-negligible factor in the COP degradation is the stand-by electrical consumption during the OFF period, especially at low load ratios. Finally, it is concluded that the minimization of the stand-by consumption is a key point for the future improvement of the seasonal performance of water-to-water systems. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001667 [article] Partialization losses of ON/OFF operation of water-to-water refrigeration/heat-pump units = Pertes de partialisation lors du fonctionnement “tout-ou-rien” des systèmes frigorifiques eau-eau /pompes à chaleur [texte imprimé] / J. M. Corberán, Auteur ; D. Donadello, Auteur ; I. Martínez-Galván, Auteur . - 2014 . - pp. 2251–2261. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2251–2261 Mots-clés : Part  load  operation;  heat  pump  performance;  partialization  losses;  COP Résumé : This paper presents the results of an experimental campaign for the characterization of the dynamic behavior of a water-to-water refrigeration/heat-pump unit under ON/OFF operation. The unit was previously tested at different water inlet temperatures under steady state conditions, and a very good agreement was found between the instantaneous dynamic performance of the heat pump and the corresponding quasi-steady state operation. In parallel, a series of tests were carried out to quantify the coefficient of performance (COP) degradation as a function of the load ratio, and a simple formula for the Part Load Factor is presented. Results lead to the conclusion that the only non-negligible factor in the COP degradation is the stand-by electrical consumption during the OFF period, especially at low load ratios. Finally, it is concluded that the minimization of the stand-by consumption is a key point for the future improvement of the seasonal performance of water-to-water systems. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001667

Thermal modeling of gas engine driven air to water heat pump systems in heating mode using genetic algorithm and Artificial Neural Network methods / Sepehr Sanaye in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2262–2277 Titre : Thermal modeling of gas engine driven air to water heat pump systems in heating mode using genetic algorithm and Artificial Neural Network methods Titre original : Pompes à chaleur air-eau en mode chauffage fonctionnant grâce à un moteur à gaz: modélisation thermique grâce à des méthodes d'algorithmes génétiques et de réseaux neuronaux artificiels Type de document : texte imprimé Auteurs : Sepehr Sanaye, Auteur ; Hesam Asgari, Auteur Année de publication : 2014 Article en page(s) : pp. 2262–2277 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Gas  engine  driven  air  to  water  heat  pump;  plate  heat  exchanger;  thermal  modeling;  artificial  neural  network;  genetic  algorithm Résumé : The gas-engine driven air-to-water heat pump, type air conditioning system, is composed of two major thermodynamic cycles (including the vapor compression refrigeration cycle and the internal combustion gas engine cycle) as well as a refrigerant-water plate heat exchanger. The thermal modeling of gas engine driven air-to-water heat pump system with engine heat recovery heat exchangers was performed here for the heating mode of operation (in which it was required to model engine heat recovery heat exchanger). The modeling was performed using typical thermodynamic characteristics of system components, Artificial Neural Network and the multi-objective genetic algorithm optimization method. The comparison of modeling results with experimental ones showed average differences of 5.08%, 5.93%, 5.21%, 2.88% and 6.2% which shows acceptable agreement for operating pressure, gas engine fuel consumption, outlet water temperature, engine rotational speed, and system primary energy ratio. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001618 [article] Thermal modeling of gas engine driven air to water heat pump systems in heating mode using genetic algorithm and Artificial Neural Network methods = Pompes à chaleur air-eau en mode chauffage fonctionnant grâce à un moteur à gaz: modélisation thermique grâce à des méthodes d'algorithmes génétiques et de réseaux neuronaux artificiels [texte imprimé] / Sepehr Sanaye, Auteur ; Hesam Asgari, Auteur . - 2014 . - pp. 2262–2277. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2262–2277 Mots-clés : Gas  engine  driven  air  to  water  heat  pump;  plate  heat  exchanger;  thermal  modeling;  artificial  neural  network;  genetic  algorithm Résumé : The gas-engine driven air-to-water heat pump, type air conditioning system, is composed of two major thermodynamic cycles (including the vapor compression refrigeration cycle and the internal combustion gas engine cycle) as well as a refrigerant-water plate heat exchanger. The thermal modeling of gas engine driven air-to-water heat pump system with engine heat recovery heat exchangers was performed here for the heating mode of operation (in which it was required to model engine heat recovery heat exchanger). The modeling was performed using typical thermodynamic characteristics of system components, Artificial Neural Network and the multi-objective genetic algorithm optimization method. The comparison of modeling results with experimental ones showed average differences of 5.08%, 5.93%, 5.21%, 2.88% and 6.2% which shows acceptable agreement for operating pressure, gas engine fuel consumption, outlet water temperature, engine rotational speed, and system primary energy ratio. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001618

A novel defrosting control method based on the degree of refrigerant superheat for air source heat pumps / Yiqiang, Jiang in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2278–2288 Titre : A novel defrosting control method based on the degree of refrigerant superheat for air source heat pumps Titre original : Nouvelle méthode de régulation du dégivrage fondée sur la surchauffe du frigorigène, pour une pompe à chaleur aérothermique Type de document : texte imprimé Auteurs : Yiqiang, Jiang, Auteur ; Jiankai, Dong, Auteur ; Minglu, Qu, Auteur Année de publication : 2014 Article en page(s) : pp. 2278–2288 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Defrosting  control  method;  refrigerant;  superheat;  heat  pump;  air-source;  experiment Résumé : When an air source heat pump (ASHP) unit operates for space heating at a frosting environment, periodic defrosting is necessary to maintain a high system performance. To defrost efficiently, it is necessary to find an effective defrosting control method. In this paper, an experiment was carried out on an ASHP unit with a capillary tube as a throttle device, under simulated frosting and defrosting conditions using time control defrosting method, and the experimental results are firstly presented. Secondly, a novel defrosting control method based on the degree of refrigerant superheat (DS) is reported. To validate the novel defrosting control method, a further experiment was conducted on another ASHP unit with an electronic expansion valve (EEV) as a throttle device, under simulated frosting and defrosting conditions. The experimental results demonstrated that when applying the novel defrosting control method, defrosting was initiated before the operating performances of ASHP unit rapidly deteriorated, which was more reasonable. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001436 [article] A novel defrosting control method based on the degree of refrigerant superheat for air source heat pumps = Nouvelle méthode de régulation du dégivrage fondée sur la surchauffe du frigorigène, pour une pompe à chaleur aérothermique [texte imprimé] / Yiqiang, Jiang, Auteur ; Jiankai, Dong, Auteur ; Minglu, Qu, Auteur . - 2014 . - pp. 2278–2288. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2278–2288 Mots-clés : Defrosting  control  method;  refrigerant;  superheat;  heat  pump;  air-source;  experiment Résumé : When an air source heat pump (ASHP) unit operates for space heating at a frosting environment, periodic defrosting is necessary to maintain a high system performance. To defrost efficiently, it is necessary to find an effective defrosting control method. In this paper, an experiment was carried out on an ASHP unit with a capillary tube as a throttle device, under simulated frosting and defrosting conditions using time control defrosting method, and the experimental results are firstly presented. Secondly, a novel defrosting control method based on the degree of refrigerant superheat (DS) is reported. To validate the novel defrosting control method, a further experiment was conducted on another ASHP unit with an electronic expansion valve (EEV) as a throttle device, under simulated frosting and defrosting conditions. The experimental results demonstrated that when applying the novel defrosting control method, defrosting was initiated before the operating performances of ASHP unit rapidly deteriorated, which was more reasonable. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001436

Development of microwave assisted zeolite–water adsorption heat pump / Hasan Demir in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2289–2296 Titre : Development of microwave assisted zeolite–water adsorption heat pump Titre original : Développement d'une pompe à chaleur à adsorption eau-zéolite fonctionnant en partie à l'aide de micro-ondes Type de document : texte imprimé Auteurs : Hasan Demir, Auteur Année de publication : 2014 Article en page(s) : pp. 2289–2296 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Microwave  heating;  dielectric  heating;  adsorption  heat  pump;  volumetric  cooling  power;  zeolite  water  pair Résumé : A microwave assisted zeolite–water adsorption heat pump system was designed, manufactured and investigated experimentally. The influence of operation time of microwave oven on performance of the adsorption heat pump was studied. The performance criteria: coefficient of performance, specific cooling power and volumetric cooing power, were calculated for the designed and tested adsorption heat pump system. The regeneration of adsorbent bed was achieved very rapidly (35 min) by using microwave heating system. The poor thermal conductivity of adsorbent did not affect the periods of isosteric heating and isobaric desorption processes. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001692 [article] Development of microwave assisted zeolite–water adsorption heat pump = Développement d'une pompe à chaleur à adsorption eau-zéolite fonctionnant en partie à l'aide de micro-ondes [texte imprimé] / Hasan Demir, Auteur . - 2014 . - pp. 2289–2296. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2289–2296 Mots-clés : Microwave  heating;  dielectric  heating;  adsorption  heat  pump;  volumetric  cooling  power;  zeolite  water  pair Résumé : A microwave assisted zeolite–water adsorption heat pump system was designed, manufactured and investigated experimentally. The influence of operation time of microwave oven on performance of the adsorption heat pump was studied. The performance criteria: coefficient of performance, specific cooling power and volumetric cooing power, were calculated for the designed and tested adsorption heat pump system. The regeneration of adsorbent bed was achieved very rapidly (35 min) by using microwave heating system. The poor thermal conductivity of adsorbent did not affect the periods of isosteric heating and isobaric desorption processes. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001692

Nanofibrous membrane-based absorption refrigeration system / Rasool Nasr Isfahani in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2297–2307 Titre : Nanofibrous membrane-based absorption refrigeration system Titre original : Système frigorifique à absorption à membrane à base nano-fibreuse Type de document : texte imprimé Auteurs : Rasool Nasr Isfahani, Auteur ; Karthikeyan Sampath, Auteur ; Saeed Moghaddam, Auteur Année de publication : 2014 Article en page(s) : pp. 2297–2307 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Absorption  system;  membrane-based  absorption;  membrane-based  desorption;  nanofibres;  air  conditioning;  lithium  bromide Résumé : This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001977 [article] Nanofibrous membrane-based absorption refrigeration system = Système frigorifique à absorption à membrane à base nano-fibreuse [texte imprimé] / Rasool Nasr Isfahani, Auteur ; Karthikeyan Sampath, Auteur ; Saeed Moghaddam, Auteur . - 2014 . - pp. 2297–2307. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2297–2307 Mots-clés : Absorption  system;  membrane-based  absorption;  membrane-based  desorption;  nanofibres;  air  conditioning;  lithium  bromide Résumé : This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001977

Performance comparison between enthalpy recovery wheels and dehumidification wheels / Rang, Tu in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2308-2322 Titre : Performance comparison between enthalpy recovery wheels and dehumidification wheels Titre original : Comparaison des performances entre les roues de récupération d'enthalpie et les roues déshydratantes Type de document : texte imprimé Auteurs : Rang, Tu, Auteur ; Xiao-Hua, Liu, Auteur ; Yi, Jiang, Auteur Année de publication : 2014 Article en page(s) : pp. 2308-2322 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Desiccant  wheel;  dehumidification;  enthalpy;  recovery;  speed;  performance Résumé : A mathematical model of desiccant wheels is established and validated by experimental results. The different effects of substrate, air mixing, and rotation speed on the performance of enthalpy recovery wheels and dehumidification wheels are analyzed. Substrate with high heat capacity and low heat conductivity is recommended for enthalpy recovery wheels, while substrate with low heat capacity and low heat conductivity is suitable for dehumidification wheels. Air mixing should be considered in evaluating recovery wheels' performance but can be ignored for dehumidification wheels. For recovery wheels without considering air mixing, higher the rotation speed, higher the recovery efficiency; when considering air mixing, the optimal rotation speed is lower than the corresponding rotation speed at a 5% air mixing rate. There also exists an optimal rotation speed to obtain better dehumidification performance for dehumidification wheels. Meanwhile, the reasons behind the discrepancies between recovery wheels and dehumidification wheels are discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001795 [article] Performance comparison between enthalpy recovery wheels and dehumidification wheels = Comparaison des performances entre les roues de récupération d'enthalpie et les roues déshydratantes [texte imprimé] / Rang, Tu, Auteur ; Xiao-Hua, Liu, Auteur ; Yi, Jiang, Auteur . - 2014 . - pp. 2308-2322. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2308-2322 Mots-clés : Desiccant  wheel;  dehumidification;  enthalpy;  recovery;  speed;  performance Résumé : A mathematical model of desiccant wheels is established and validated by experimental results. The different effects of substrate, air mixing, and rotation speed on the performance of enthalpy recovery wheels and dehumidification wheels are analyzed. Substrate with high heat capacity and low heat conductivity is recommended for enthalpy recovery wheels, while substrate with low heat capacity and low heat conductivity is suitable for dehumidification wheels. Air mixing should be considered in evaluating recovery wheels' performance but can be ignored for dehumidification wheels. For recovery wheels without considering air mixing, higher the rotation speed, higher the recovery efficiency; when considering air mixing, the optimal rotation speed is lower than the corresponding rotation speed at a 5% air mixing rate. There also exists an optimal rotation speed to obtain better dehumidification performance for dehumidification wheels. Meanwhile, the reasons behind the discrepancies between recovery wheels and dehumidification wheels are discussed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001795

Effect of regeneration temperatures in the exergetic performances of the developed desiccant-evaporative air-conditioning system / Napoleon Enteria in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2323–2342 Titre : Effect of regeneration temperatures in the exergetic performances of the developed desiccant-evaporative air-conditioning system Titre original : Effet des températures de régénération dans les performances exergétiques pour le développement d'un système de conditionnement d'air déshydratant par évaporation Type de document : texte imprimé Auteurs : Napoleon Enteria, Auteur ; Hiroshi, Yoshino, Auteur ; Rie, Takaki, Auteur Année de publication : 2014 Article en page(s) : pp. 2323–2342 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Desiccant  dehumidification;  evaporative  cooling;  air  handling  system;  exergy  analysis Résumé : The developed desiccant-evaporative air-conditioning system was evaluated using the exergetic method under controlled environmental conditions to determine the performances of the whole system and its components. Percentage contributions of exergy destruction of system components at different regeneration temperatures and reference temperatures were determined. Exergy destruction coefficient of different components at different regeneration and reference temperatures were presented. It was shown that exergetic performances varied with respect to the regeneration and reference temperatures. The exergetic performances based on thermal, electric, total exergy input, first definition and second definition efficiencies were shown. Based on the results, reference and regeneration temperatures affected the determination of the system performances and its components. It was shown that air-heating coil, air fans and desiccant wheel contributed to large percentage of exergy destruction. Hence, the mentioned components should be given attention for further improvement of the system performances. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002090 [article] Effect of regeneration temperatures in the exergetic performances of the developed desiccant-evaporative air-conditioning system = Effet des températures de régénération dans les performances exergétiques pour le développement d'un système de conditionnement d'air déshydratant par évaporation [texte imprimé] / Napoleon Enteria, Auteur ; Hiroshi, Yoshino, Auteur ; Rie, Takaki, Auteur . - 2014 . - pp. 2323–2342. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2323–2342 Mots-clés : Desiccant  dehumidification;  evaporative  cooling;  air  handling  system;  exergy  analysis Résumé : The developed desiccant-evaporative air-conditioning system was evaluated using the exergetic method under controlled environmental conditions to determine the performances of the whole system and its components. Percentage contributions of exergy destruction of system components at different regeneration temperatures and reference temperatures were determined. Exergy destruction coefficient of different components at different regeneration and reference temperatures were presented. It was shown that exergetic performances varied with respect to the regeneration and reference temperatures. The exergetic performances based on thermal, electric, total exergy input, first definition and second definition efficiencies were shown. Based on the results, reference and regeneration temperatures affected the determination of the system performances and its components. It was shown that air-heating coil, air fans and desiccant wheel contributed to large percentage of exergy destruction. Hence, the mentioned components should be given attention for further improvement of the system performances. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002090

Innovative thermoeconomic diagnosis of multiple faults in air conditioning units / Antonio Piacentino in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2343–2365 Titre : Innovative thermoeconomic diagnosis of multiple faults in air conditioning units : methodological improvements and increased reliability of results Titre original : Diagnostic thermoéconomique innovant de défaillances multiples dans des conditionneurs d'air: améliorations méthodologiques et fiabilité accrue des résultats Type de document : texte imprimé Auteurs : Antonio Piacentino, Auteur ; Miriam Talamo, Auteur Année de publication : 2014 Article en page(s) : pp. 2343–2365 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Thermoeconomic  diagnosis;  air-conditioning  units;  failure;  detection Résumé : Thermoeconomic faults diagnosis of air conditioning units is a pioneeristic approach to detect single or multiple faults and quantify their impact in terms of additional energy consumption. The poor reliability of conventional thermoeconomic approaches has been limiting the interest for practical applications of this technique. In this paper an improved thermoeconomic diagnosis is proposed and applied to a reference 120 kWc air-cooled air conditioning system; a simulator is used to evaluate thermodynamic data under normal and faulty conditions. Four faults are individually or simultaneously imposed: fouling at condenser and evaporator, refrigerant undercharge and compressor valve leakage. For setting up the diagnostic tool only a few numerical or experimental tests are required; the results testify the procedure to be sufficiently reliable both when heavy or light faults are considered. Also, the performance of the diagnostic procedure slightly improves when the effects of “system level” faults like refrigerant undercharge are preliminarily filtered. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001813 [article] Innovative thermoeconomic diagnosis of multiple faults in air conditioning units = Diagnostic thermoéconomique innovant de défaillances multiples dans des conditionneurs d'air: améliorations méthodologiques et fiabilité accrue des résultats : methodological improvements and increased reliability of results [texte imprimé] / Antonio Piacentino, Auteur ; Miriam Talamo, Auteur . - 2014 . - pp. 2343–2365. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2343–2365 Mots-clés : Thermoeconomic  diagnosis;  air-conditioning  units;  failure;  detection Résumé : Thermoeconomic faults diagnosis of air conditioning units is a pioneeristic approach to detect single or multiple faults and quantify their impact in terms of additional energy consumption. The poor reliability of conventional thermoeconomic approaches has been limiting the interest for practical applications of this technique. In this paper an improved thermoeconomic diagnosis is proposed and applied to a reference 120 kWc air-cooled air conditioning system; a simulator is used to evaluate thermodynamic data under normal and faulty conditions. Four faults are individually or simultaneously imposed: fouling at condenser and evaporator, refrigerant undercharge and compressor valve leakage. For setting up the diagnostic tool only a few numerical or experimental tests are required; the results testify the procedure to be sufficiently reliable both when heavy or light faults are considered. Also, the performance of the diagnostic procedure slightly improves when the effects of “system level” faults like refrigerant undercharge are preliminarily filtered. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001813

Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes / Chieko Kondou in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2366–2378 Titre : Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes Titre original : Écoulement en ébullition d'un mélange non-azéotropique de R32 et de R1234ze dans des tubes horizontaux à micro-ailettes Type de document : texte imprimé Auteurs : Chieko Kondou, Auteur ; Daisuke Baba, Auteur ; Fumiya Mishima, Auteur Année de publication : 2014 Article en page(s) : pp. 2366–2378 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flow  boiling;  heat  transfer;  pressure  drop;  microfin  tube;  non-zeotropic  mixture;  GWP Résumé : Flow boiling of a potential refrigerant R32/R1234ze(E) in a horizontal microfin tube of 5.21 mm inner diameter is experimentally investigated. The heat transfer coefficient (HTC) and pressure drop are measured at a saturation temperature of 10 °C, heat fluxes of 10 and 15 kW m−2, and mass velocities from 150 to 400 kg m−2 s−1. The HTC of R1234ze(E) is lower than that of R32. Degradation in the HTC of the R32/R1234ze(E) mixture is significant; the HTC is even lower than that of R1234ze(E). The HTC is minimized at the composition 0.2/0.8 by mass, where the temperature glide and the mass fraction distribution are maximized. A predicting correlation based on Momoki et al. (1995) associated with the correction methods of Thome (1981) to consider the mass transfer resistance and Stephan (1992) to consider the additionally required sensible heat is proposed and validated with the experimental results. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001734 [article] Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes = Écoulement en ébullition d'un mélange non-azéotropique de R32 et de R1234ze dans des tubes horizontaux à micro-ailettes [texte imprimé] / Chieko Kondou, Auteur ; Daisuke Baba, Auteur ; Fumiya Mishima, Auteur . - 2014 . - pp. 2366–2378. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2366–2378 Mots-clés : Flow  boiling;  heat  transfer;  pressure  drop;  microfin  tube;  non-zeotropic  mixture;  GWP Résumé : Flow boiling of a potential refrigerant R32/R1234ze(E) in a horizontal microfin tube of 5.21 mm inner diameter is experimentally investigated. The heat transfer coefficient (HTC) and pressure drop are measured at a saturation temperature of 10 °C, heat fluxes of 10 and 15 kW m−2, and mass velocities from 150 to 400 kg m−2 s−1. The HTC of R1234ze(E) is lower than that of R32. Degradation in the HTC of the R32/R1234ze(E) mixture is significant; the HTC is even lower than that of R1234ze(E). The HTC is minimized at the composition 0.2/0.8 by mass, where the temperature glide and the mass fraction distribution are maximized. A predicting correlation based on Momoki et al. (1995) associated with the correction methods of Thome (1981) to consider the mass transfer resistance and Stephan (1992) to consider the additionally required sensible heat is proposed and validated with the experimental results. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001734

The applicability of an existing fluted tube condenser model when used with refrigerant R-407C / M. van Eldik in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2379–2386 Titre : The applicability of an existing fluted tube condenser model when used with refrigerant R-407C Titre original : Applicabilité d'un modèle existant de condenseur à tube cannelé utilisé avec le frigorigène R-407C Type de document : texte imprimé Auteurs : M. van Eldik, Auteur ; G. Wessels, Auteur Année de publication : 2014 Article en page(s) : pp. 2379–2386 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  fluted  tube;  heat  pump;  simulation  model;  R-407C Résumé : Fluted tube-in-tube condensers are key components in energy efficient water heating heat pumps. Rousseau et al. (2003) developed a model that incorporates all the essential features of these heat exchangers. A feature of the model was that it allowed for the extension to simulate heat exchangers for cycles employing zeotropic refrigerant mixtures. This paper investigates the applicability of the model for R-407C condensation inside fluted tube annuli. To evaluate the model experimental data was gathered using a test facility. Comparisons between the experimental results and the model showed an average model accuracy of 48% when predicting the pressure drop and 56% for the log mean temperature difference (LMTD) for the tubes sizes used. Based on these accuracies new enhancement factors were derived and implemented in the model. This resulted in an average difference between the simulated and measured pressure drops of 9.5% and an average difference for the LMTD of 3.3%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001631 [article] The applicability of an existing fluted tube condenser model when used with refrigerant R-407C = Applicabilité d'un modèle existant de condenseur à tube cannelé utilisé avec le frigorigène R-407C [texte imprimé] / M. van Eldik, Auteur ; G. Wessels, Auteur . - 2014 . - pp. 2379–2386. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2379–2386 Mots-clés : Condensation;  fluted  tube;  heat  pump;  simulation  model;  R-407C Résumé : Fluted tube-in-tube condensers are key components in energy efficient water heating heat pumps. Rousseau et al. (2003) developed a model that incorporates all the essential features of these heat exchangers. A feature of the model was that it allowed for the extension to simulate heat exchangers for cycles employing zeotropic refrigerant mixtures. This paper investigates the applicability of the model for R-407C condensation inside fluted tube annuli. To evaluate the model experimental data was gathered using a test facility. Comparisons between the experimental results and the model showed an average model accuracy of 48% when predicting the pressure drop and 56% for the log mean temperature difference (LMTD) for the tubes sizes used. Based on these accuracies new enhancement factors were derived and implemented in the model. This resulted in an average difference between the simulated and measured pressure drops of 9.5% and an average difference for the LMTD of 3.3%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001631

Effects of vacuum cooling on the enzymatic antioxidant system of cherry and inhibition of surface-borne pathogens / S. Y. He in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2387–2394 Titre : Effects of vacuum cooling on the enzymatic antioxidant system of cherry and inhibition of surface-borne pathogens Titre original : Effets du refroidissement sous vide sur le système antioxydant enzymatique des cerises et l'inhibition des pathogènes à la surface des fruits Type de document : texte imprimé Auteurs : S. Y. He, Auteur ; G. C. Zhang, Auteur ; Y. Q. Yu, Auteur Année de publication : 2014 Article en page(s) : pp. 2387–2394 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Vacuum  cooling;  sweet  cherry;  antioxidant  activity;  scanning  electron  microscope Résumé : The study aimed to determine the effects of vacuum cooling on the enzymatic antioxidant system of cherry and inhibition of surface-borne bacteria during storage. Cherries were vacuum-cooled and then stored at 1 °C and 95% relative humidity for 1 week. Changes in the enzymatic antioxidant system of cherry were measured throughout the storage period. The catalase activity and peroxidase activity of vacuum-cooled cherries were higher than those of the control during storage. In addition, the malondialdehyde content of cherry with vacuum cooling was lower than that of the control. Both groups showed intermediate levels of polyphenol oxidase activity. Scanning electron microscopy studies demonstrated the inhibitory effect of vacuum cooling on the morphology of E. coli on the cherry surfaces. This study offers new insights into the physiological mechanics of cherry fruit after vacuum cooling and storage and provides experimental evidence for better control of cherry quality in practice. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300145X [article] Effects of vacuum cooling on the enzymatic antioxidant system of cherry and inhibition of surface-borne pathogens = Effets du refroidissement sous vide sur le système antioxydant enzymatique des cerises et l'inhibition des pathogènes à la surface des fruits [texte imprimé] / S. Y. He, Auteur ; G. C. Zhang, Auteur ; Y. Q. Yu, Auteur . - 2014 . - pp. 2387–2394. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2387–2394 Mots-clés : Vacuum  cooling;  sweet  cherry;  antioxidant  activity;  scanning  electron  microscope Résumé : The study aimed to determine the effects of vacuum cooling on the enzymatic antioxidant system of cherry and inhibition of surface-borne bacteria during storage. Cherries were vacuum-cooled and then stored at 1 °C and 95% relative humidity for 1 week. Changes in the enzymatic antioxidant system of cherry were measured throughout the storage period. The catalase activity and peroxidase activity of vacuum-cooled cherries were higher than those of the control during storage. In addition, the malondialdehyde content of cherry with vacuum cooling was lower than that of the control. Both groups showed intermediate levels of polyphenol oxidase activity. Scanning electron microscopy studies demonstrated the inhibitory effect of vacuum cooling on the morphology of E. coli on the cherry surfaces. This study offers new insights into the physiological mechanics of cherry fruit after vacuum cooling and storage and provides experimental evidence for better control of cherry quality in practice. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300145X

Impact of the initial field on the thermodynamic performance of room-temperature magnetic refrigeration cycle / Gildas Diguet in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2395–2402 Titre : Impact of the initial field on the thermodynamic performance of room-temperature magnetic refrigeration cycle Titre original : Impact du champ initial sur le rendement thermodynamique du cycle frigorifique magnétique à température ambiante Type de document : texte imprimé Auteurs : Gildas Diguet, Auteur ; Guoxing, Lin, Auteur ; Jincan, Chen, Auteur Année de publication : 2014 Article en page(s) : pp. 2395–2402 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration;  regeneration;  magnetocaloric  material;  room-temperature  applications;  thermodynamics  analysis Résumé : The thermodynamic cycle performance of Gadolinium (Gd) and Gd0.87Dy0.13 used as the working substance in regeneration magnetic Brayton and Ericsson refrigeration cycles are investigated under different external magnetic field conditions. Based on the experimental iso-field heat capacities of Gd with different magnetic fields, the effects of magnetic field change on thermodynamic performances including the magnetic entropy change, cooling quantity, non-perfect regeneration, net cooling quantity, and coefficient of performance (COP) are analyzed and discussed. The present work shows the possibility of reducing the regenerative losses and thereby improving the net cooling quantity for a given field change by selecting optimal initial and final magnetic field values. The similar analysis and calculation of the related thermodynamic performances are further applied to the magnetic material Gd0.87Dy0.13 which exhibits better net cooling quantities when compared to Gd at low temperature. En ligne : www.sciencedirect.com/science/article/pii/S0140700713001722 [article] Impact of the initial field on the thermodynamic performance of room-temperature magnetic refrigeration cycle = Impact du champ initial sur le rendement thermodynamique du cycle frigorifique magnétique à température ambiante [texte imprimé] / Gildas Diguet, Auteur ; Guoxing, Lin, Auteur ; Jincan, Chen, Auteur . - 2014 . - pp. 2395–2402. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2395–2402 Mots-clés : Magnetic  refrigeration;  regeneration;  magnetocaloric  material;  room-temperature  applications;  thermodynamics  analysis Résumé : The thermodynamic cycle performance of Gadolinium (Gd) and Gd0.87Dy0.13 used as the working substance in regeneration magnetic Brayton and Ericsson refrigeration cycles are investigated under different external magnetic field conditions. Based on the experimental iso-field heat capacities of Gd with different magnetic fields, the effects of magnetic field change on thermodynamic performances including the magnetic entropy change, cooling quantity, non-perfect regeneration, net cooling quantity, and coefficient of performance (COP) are analyzed and discussed. The present work shows the possibility of reducing the regenerative losses and thereby improving the net cooling quantity for a given field change by selecting optimal initial and final magnetic field values. The similar analysis and calculation of the related thermodynamic performances are further applied to the magnetic material Gd0.87Dy0.13 which exhibits better net cooling quantities when compared to Gd at low temperature. En ligne : www.sciencedirect.com/science/article/pii/S0140700713001722

Modeling of the interface behavior in tape casting of functionally graded ceramics for magnetic refrigeration parts / Masoud Jabbari in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2403–2409 Titre : Modeling of the interface behavior in tape casting of functionally graded ceramics for magnetic refrigeration parts Titre original : Modélisation du comportement de l'interface lors du coulage en bande des céramiques calibrées pour les composants utilisés dans le froid magnétique Type de document : texte imprimé Auteurs : Masoud Jabbari, Auteur ; Jon Spangenberg, Auteur ; Jesper Hattel, Auteur Année de publication : 2014 Article en page(s) : pp. 2403–2409 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration;  functionally  graded  ceramics;  tape  casting;  fluid  flow Résumé : The main goal of this work is to study the multiple material flows in side-by-side (SBS) tape casting and analyze the influence of the different material properties, i.e. the density and the viscosity, on the interface between the fluids, since this is highly important for the efficiency of a graded configuration of the magnetocaloric materials. The Newtonian flow behavior with relatively high viscosity is assumed for each fluid and used in the simulation with a commercial CFD code (ANSYS FLUENT). The results show that the density difference does not affect the interface between the adjacent fluids, whereas the viscosity of the fluids plays the most important role in the behavior of the interface. Moreover, increasing the viscosity difference of the adjacent fluids, Δμ, leads to increasing the diffusive region between them. However, this can be counteracted by decreasing the velocity by the substrate. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001138 [article] Modeling of the interface behavior in tape casting of functionally graded ceramics for magnetic refrigeration parts = Modélisation du comportement de l'interface lors du coulage en bande des céramiques calibrées pour les composants utilisés dans le froid magnétique [texte imprimé] / Masoud Jabbari, Auteur ; Jon Spangenberg, Auteur ; Jesper Hattel, Auteur . - 2014 . - pp. 2403–2409. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2403–2409 Mots-clés : Magnetic  refrigeration;  functionally  graded  ceramics;  tape  casting;  fluid  flow Résumé : The main goal of this work is to study the multiple material flows in side-by-side (SBS) tape casting and analyze the influence of the different material properties, i.e. the density and the viscosity, on the interface between the fluids, since this is highly important for the efficiency of a graded configuration of the magnetocaloric materials. The Newtonian flow behavior with relatively high viscosity is assumed for each fluid and used in the simulation with a commercial CFD code (ANSYS FLUENT). The results show that the density difference does not affect the interface between the adjacent fluids, whereas the viscosity of the fluids plays the most important role in the behavior of the interface. Moreover, increasing the viscosity difference of the adjacent fluids, Δμ, leads to increasing the diffusive region between them. However, this can be counteracted by decreasing the velocity by the substrate. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001138

Experimental and simulation studies on the performance of standing wave thermoacoustic prime mover for pulse tube refrigerator / Bharatbhushan V. Kamble in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2410–2419 Titre : Experimental and simulation studies on the performance of standing wave thermoacoustic prime mover for pulse tube refrigerator Titre original : Etudes expérimentales et de simulation sur les performances des ondes stationnaires d'une force motrice thermoacoustique pour le réfrigérateur à tube à pulsations Type de document : texte imprimé Auteurs : Bharatbhushan V. Kamble, Auteur ; Biju T. Kuzhiveli, Auteur ; S. Kasthurirengan, Auteur Année de publication : 2014 Article en page(s) : pp. 2410–2419 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Standing-wave;  thermoacoustics;  prime  mover;  deltaEc;  cryocoolers;  simulation Résumé : The thermoacoustic prime mover (TAPM) has gained considerable attention as a pressure wave generator to drive pulse tube refrigerator (PTR) due to no moving parts, reasonable efficiency, use of environmental friendly working fluids etc. To drive PTCs, lower frequencies (f) with larger pressure amplitudes (ΔP) are essential, which are affected by geometric and operating parameters of TAPM as well as working fluids. For driving PTRs, a twin standing wave TAPM is built and studied by using different working fluids such as helium, argon, nitrogen and their binary mixtures. Simulation results of DeltaEc are compared with experimental data wherever possible. DeltaEc predicts slightly increased resonance frequencies, but gives larger ΔP and lower temperature difference ΔT across stack. High mass number working fluid leads to lower frequency with larger ΔP, but higher ΔT. Studies indicate that the binary gas mixture of right composition with lower ΔT can be arrived at to drive TAPM of given geometry. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002053 [article] Experimental and simulation studies on the performance of standing wave thermoacoustic prime mover for pulse tube refrigerator = Etudes expérimentales et de simulation sur les performances des ondes stationnaires d'une force motrice thermoacoustique pour le réfrigérateur à tube à pulsations [texte imprimé] / Bharatbhushan V. Kamble, Auteur ; Biju T. Kuzhiveli, Auteur ; S. Kasthurirengan, Auteur . - 2014 . - pp. 2410–2419. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2410–2419 Mots-clés : Standing-wave;  thermoacoustics;  prime  mover;  deltaEc;  cryocoolers;  simulation Résumé : The thermoacoustic prime mover (TAPM) has gained considerable attention as a pressure wave generator to drive pulse tube refrigerator (PTR) due to no moving parts, reasonable efficiency, use of environmental friendly working fluids etc. To drive PTCs, lower frequencies (f) with larger pressure amplitudes (ΔP) are essential, which are affected by geometric and operating parameters of TAPM as well as working fluids. For driving PTRs, a twin standing wave TAPM is built and studied by using different working fluids such as helium, argon, nitrogen and their binary mixtures. Simulation results of DeltaEc are compared with experimental data wherever possible. DeltaEc predicts slightly increased resonance frequencies, but gives larger ΔP and lower temperature difference ΔT across stack. High mass number working fluid leads to lower frequency with larger ΔP, but higher ΔT. Studies indicate that the binary gas mixture of right composition with lower ΔT can be arrived at to drive TAPM of given geometry. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002053

Experimental investigation of a thermoacoustic refrigerator driven by a standing wave twin thermoacoustic prime mover / N. M. Hariharan in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2420-2425 Titre : Experimental investigation of a thermoacoustic refrigerator driven by a standing wave twin thermoacoustic prime mover Titre original : Etude expérimentale sur un réfrigérateur thermoacoustique entraîné par une force motrice principale thermoacoustique à deux ondes Type de document : texte imprimé Auteurs : N. M. Hariharan, Auteur ; P. Sivashanmugam, Auteur ; S. Kasthurirengan, Auteur Année de publication : 2014 Article en page(s) : pp. 2420-2425 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Thermoacoustic  refrigerator;  twin-wave  thermoacoustic  prime  mover;  spacing;  hot  end  temperature;  temperature  difference Résumé : The objective of this study is to analyse the performance of thermoacoustic refrigerator (TAR) measured in terms of hot end temperature and temperature difference across refrigerator stack with two different spacing namely 0.4 mm and 0.8 mm and stack used in refrigerating section was made of low thermal conductivity materials namely Mylar sheet and photographic film & the experiments were carried out at 1 MPa pressure using helium as working fluid. High powered acoustic wave with frequency of 460 Hz and pressure amplitude of ≅≅0.07 MPa was obtained from twin thermoacoustic prime mover (TAPM) and this acoustic wave produced temperature difference of 16 °C across the Mylar sheet stack made of 0.4 mm spacing in refrigerator section. From this study, it has been inferred that twin TAPM can act as efficient drive for TAR. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001060 [article] Experimental investigation of a thermoacoustic refrigerator driven by a standing wave twin thermoacoustic prime mover = Etude expérimentale sur un réfrigérateur thermoacoustique entraîné par une force motrice principale thermoacoustique à deux ondes [texte imprimé] / N. M. Hariharan, Auteur ; P. Sivashanmugam, Auteur ; S. Kasthurirengan, Auteur . - 2014 . - pp. 2420-2425. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2420-2425 Mots-clés : Thermoacoustic  refrigerator;  twin-wave  thermoacoustic  prime  mover;  spacing;  hot  end  temperature;  temperature  difference Résumé : The objective of this study is to analyse the performance of thermoacoustic refrigerator (TAR) measured in terms of hot end temperature and temperature difference across refrigerator stack with two different spacing namely 0.4 mm and 0.8 mm and stack used in refrigerating section was made of low thermal conductivity materials namely Mylar sheet and photographic film & the experiments were carried out at 1 MPa pressure using helium as working fluid. High powered acoustic wave with frequency of 460 Hz and pressure amplitude of ≅≅0.07 MPa was obtained from twin thermoacoustic prime mover (TAPM) and this acoustic wave produced temperature difference of 16 °C across the Mylar sheet stack made of 0.4 mm spacing in refrigerator section. From this study, it has been inferred that twin TAPM can act as efficient drive for TAR. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001060

Effects of variable thermophysical properties on flow and energy separation in a vortex tube / A. Ouadha in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2426–2437 Titre : Effects of variable thermophysical properties on flow and energy separation in a vortex tube Titre original : Effets de propriétés thermophysiques variables sur l'écoulement et la séparation d'énergie dans un tube vortex Type de document : texte imprimé Auteurs : A. Ouadha, Auteur ; M. Baghdad, Auteur ; Y. Addad, Auteur Année de publication : 2014 Article en page(s) : pp. 2426–2437 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Vortex  tube;  Exergy  analysis;  RSM  model Résumé : A numerical study has been conducted to investigate the effects of variable fluid properties on the prediction of a basic tube vortex design. Beforehand, a literature review is presented to highlight some of the recent advances in the enhancements of the device design and its efficiency. The three-dimensional computations with constant and variable properties revealed that the constant thermophysical assumption might not have a dramatic effect if the aim is to predict global values only, but extra caution should be taken for an in-depth flow assessment. The exergy analysis conducted suggests that the highest exergy efficiency, for the current device design, ranges from 38% to 46% depending on the inlet pressure value. Based on the current numerical analysis; rather large exergy losses are due to irreversibility occurring at either; the lowest or the highest cold mass fraction boundary conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001965 [article] Effects of variable thermophysical properties on flow and energy separation in a vortex tube = Effets de propriétés thermophysiques variables sur l'écoulement et la séparation d'énergie dans un tube vortex [texte imprimé] / A. Ouadha, Auteur ; M. Baghdad, Auteur ; Y. Addad, Auteur . - 2014 . - pp. 2426–2437. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2426–2437 Mots-clés : Vortex  tube;  Exergy  analysis;  RSM  model Résumé : A numerical study has been conducted to investigate the effects of variable fluid properties on the prediction of a basic tube vortex design. Beforehand, a literature review is presented to highlight some of the recent advances in the enhancements of the device design and its efficiency. The three-dimensional computations with constant and variable properties revealed that the constant thermophysical assumption might not have a dramatic effect if the aim is to predict global values only, but extra caution should be taken for an in-depth flow assessment. The exergy analysis conducted suggests that the highest exergy efficiency, for the current device design, ranges from 38% to 46% depending on the inlet pressure value. Based on the current numerical analysis; rather large exergy losses are due to irreversibility occurring at either; the lowest or the highest cold mass fraction boundary conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001965

Optimum number of stages and intermediate pressure level for highest exergy efficiency in large helium liquefiers / Rijo, Jacob Thomas in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2438–2457 Titre : Optimum number of stages and intermediate pressure level for highest exergy efficiency in large helium liquefiers Titre original : Nombre d'étages et niveau de pression intermédiaire optimaux, en vue du meilleur rendement exergétique dans de grands liquéfacteurs d'hélium Type de document : texte imprimé Auteurs : Rijo, Jacob Thomas, Auteur ; Parthasarathi Ghosh, Auteur ; Kanchan Chowdhury, Auteur Année de publication : 2014 Article en page(s) : pp. 2438–2457 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Helium  liquefier;  Exergy  analysis;  Refrigeration  stages;  Expander  pressure;  Reverse  Brayton  stage;  Aspen  HYSYS Résumé : In this paper, an attempt has been made to study the influence of different design and operating parameters on the performance of large scale helium liquefiers through the concept of pre-cooling stages. Through exergy analysis and simulation with Aspen HYSYS® 7.0, it has been demonstrated that four refrigeration stages is the best option for large helium liquefiers when all expanders operate between the entire available pressure differences. However, when some of the expanders are operated at intermediate pressure, a more number of stages gives a higher thermodynamic efficiency. Relationship between the number of stages, effective heat exchanger area and operating pressure levels of expanders, which could optimally be employed for least specific power consumption has been established through exergy analysis. Optimum number of stages, intermediate pressure and corresponding plant efficiency are, however to a large extent, dictated by the prevailing compressor efficiency. The intermediate pressure that gives the maximum exergy efficiency for the plant increases from 0.2 MPa with constant compressor efficiency to 0.35 MPa when considering two-staged compressor where pressure ratio influences compressor efficiency. Results presented may be useful in designing energy-efficient helium liquefiers of large capacity. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001552 [article] Optimum number of stages and intermediate pressure level for highest exergy efficiency in large helium liquefiers = Nombre d'étages et niveau de pression intermédiaire optimaux, en vue du meilleur rendement exergétique dans de grands liquéfacteurs d'hélium [texte imprimé] / Rijo, Jacob Thomas, Auteur ; Parthasarathi Ghosh, Auteur ; Kanchan Chowdhury, Auteur . - 2014 . - pp. 2438–2457. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2438–2457 Mots-clés : Helium  liquefier;  Exergy  analysis;  Refrigeration  stages;  Expander  pressure;  Reverse  Brayton  stage;  Aspen  HYSYS Résumé : In this paper, an attempt has been made to study the influence of different design and operating parameters on the performance of large scale helium liquefiers through the concept of pre-cooling stages. Through exergy analysis and simulation with Aspen HYSYS® 7.0, it has been demonstrated that four refrigeration stages is the best option for large helium liquefiers when all expanders operate between the entire available pressure differences. However, when some of the expanders are operated at intermediate pressure, a more number of stages gives a higher thermodynamic efficiency. Relationship between the number of stages, effective heat exchanger area and operating pressure levels of expanders, which could optimally be employed for least specific power consumption has been established through exergy analysis. Optimum number of stages, intermediate pressure and corresponding plant efficiency are, however to a large extent, dictated by the prevailing compressor efficiency. The intermediate pressure that gives the maximum exergy efficiency for the plant increases from 0.2 MPa with constant compressor efficiency to 0.35 MPa when considering two-staged compressor where pressure ratio influences compressor efficiency. Results presented may be useful in designing energy-efficient helium liquefiers of large capacity. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001552

The 4th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants held in Delft, the Netherlands, on June 17–19, 2013 / Carlos Infante Ferreira in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2458–2459 Titre : The 4th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants held in Delft, the Netherlands, on June 17–19, 2013 Titre original : Rapport de la Conférence: 4ème Conférence de l'IIF sur les Propriétés Thermophysiques et les Processus de transfert des Frigorigènes, tenue à Delft, aux Pays-Bas, du 17 au 19 Juin 2013 Type de document : texte imprimé Auteurs : Carlos Infante Ferreira, Auteur Année de publication : 2014 Article en page(s) : pp. 2458–2459 Note générale : Refrigeration Langues : Anglais (eng) En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002016 [article] The 4th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants held in Delft, the Netherlands, on June 17–19, 2013 = Rapport de la Conférence: 4ème Conférence de l'IIF sur les Propriétés Thermophysiques et les Processus de transfert des Frigorigènes, tenue à Delft, aux Pays-Bas, du 17 au 19 Juin 2013 [texte imprimé] / Carlos Infante Ferreira, Auteur . - 2014 . - pp. 2458–2459. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2458–2459 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002016

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