Dépouillements

Experimental analysis of a new method for overfeeding multiple evaporators in refrigeration systems / Silvia Minetto in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 1–9 Titre : Experimental analysis of a new method for overfeeding multiple evaporators in refrigeration systems Titre original : Analyse expérimentale d'une nouvelle méthode pour la suralimentation d'évaporateurs multiples dans des systèmes frigorifiques Type de document : texte imprimé Auteurs : Silvia Minetto, Auteur ; Riccardo Brignoli, Auteur ; Claudio Zilio, Auteur Année de publication : 2014 Article en page(s) : pp. 1–9 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : CO2;  Flooded  evaporator;  Thermostatic  valve;  Ejector;  Transcritical  cycle Résumé : An innovative method for feeding flooded evaporators, arranged in parallel in R744 plants, is presented. In order to promote evaporators overfeeding, an ejector circulates liquid from the low pressure receiver back to the intermediate pressure receiver. Since there is not a need for superheat at the evaporator exit, each evaporator expansion valve can be controlled by a signal representative, either of the evaporator load, or the evaporator performance, such as the air temperature at its inlet or outlet. When compared to dry-expansion evaporator systems, the proposed solution offers energy saving and smooth operating conditions, typical of flooded evaporators, while still maintaining a simple plant lay-out. The concept was experimentally validated: the evaporators were maintained in flooded conditions, while the ejector was able to promote liquid recirculation. Direct comparison with dry-expansion operations was performed. The suggested method is mainly intended for commercial refrigeration plants, where many evaporators are arranged in parallel. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002788 [article] Experimental analysis of a new method for overfeeding multiple evaporators in refrigeration systems = Analyse expérimentale d'une nouvelle méthode pour la suralimentation d'évaporateurs multiples dans des systèmes frigorifiques [texte imprimé] / Silvia Minetto, Auteur ; Riccardo Brignoli, Auteur ; Claudio Zilio, Auteur . - 2014 . - pp. 1–9. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 1–9 Mots-clés : CO2;  Flooded  evaporator;  Thermostatic  valve;  Ejector;  Transcritical  cycle Résumé : An innovative method for feeding flooded evaporators, arranged in parallel in R744 plants, is presented. In order to promote evaporators overfeeding, an ejector circulates liquid from the low pressure receiver back to the intermediate pressure receiver. Since there is not a need for superheat at the evaporator exit, each evaporator expansion valve can be controlled by a signal representative, either of the evaporator load, or the evaporator performance, such as the air temperature at its inlet or outlet. When compared to dry-expansion evaporator systems, the proposed solution offers energy saving and smooth operating conditions, typical of flooded evaporators, while still maintaining a simple plant lay-out. The concept was experimentally validated: the evaporators were maintained in flooded conditions, while the ejector was able to promote liquid recirculation. Direct comparison with dry-expansion operations was performed. The suggested method is mainly intended for commercial refrigeration plants, where many evaporators are arranged in parallel. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002788

Experimental and numerical study of electronic module-cooling heat sinks used in a variable frequency air-conditioner outdoor unit / Xifeng Zhao in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 10–21 Titre : Experimental and numerical study of electronic module-cooling heat sinks used in a variable frequency air-conditioner outdoor unit Titre original : Etude expérimentale et numérique de puits thermiques d'un système extérieur de conditionnement d'air à vitesse variable, utilisés pour le refroidissement de modules électroniques Type de document : texte imprimé Auteurs : Xifeng Zhao, Auteur ; Jinju Sun, Auteur ; Chao Wang, Auteur Année de publication : 2014 Article en page(s) : pp. 10–21 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Heat  sink;  Electronic  module  cooling;  Variable  frequency  air-conditioner;  Heat  transfer Résumé : In variable-frequency Air Conditioner (AC), sizes of frequency controlling electronic module and its supplemental heat sink are much restrained and they are also tightly packed. Heat removal in such a limited space is difficult, and effective and compact heat sinks are required. The study has focused on heat sink thermal performance with different geometries and configurations. To allow for interaction of heat sink and fan, both numerical and experimental investigations are conducted in a real AC outdoor unit environment. An increase in heat sink base area significantly improves its thermal performance; fin height and pitch influence convective surface and also sweeping stream behavior and a good compromise is needed to enhance convective heat transfer. A proper tuning of heat sink configuration is effective to improve convective stream and subsequently enhance thermal performance. Heat sink geometry and configuration produces insignificant influence on fan aerodynamic and aeroacoustic performance, and AC system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002533 [article] Experimental and numerical study of electronic module-cooling heat sinks used in a variable frequency air-conditioner outdoor unit = Etude expérimentale et numérique de puits thermiques d'un système extérieur de conditionnement d'air à vitesse variable, utilisés pour le refroidissement de modules électroniques [texte imprimé] / Xifeng Zhao, Auteur ; Jinju Sun, Auteur ; Chao Wang, Auteur . - 2014 . - pp. 10–21. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 10–21 Mots-clés : Heat  sink;  Electronic  module  cooling;  Variable  frequency  air-conditioner;  Heat  transfer Résumé : In variable-frequency Air Conditioner (AC), sizes of frequency controlling electronic module and its supplemental heat sink are much restrained and they are also tightly packed. Heat removal in such a limited space is difficult, and effective and compact heat sinks are required. The study has focused on heat sink thermal performance with different geometries and configurations. To allow for interaction of heat sink and fan, both numerical and experimental investigations are conducted in a real AC outdoor unit environment. An increase in heat sink base area significantly improves its thermal performance; fin height and pitch influence convective surface and also sweeping stream behavior and a good compromise is needed to enhance convective heat transfer. A proper tuning of heat sink configuration is effective to improve convective stream and subsequently enhance thermal performance. Heat sink geometry and configuration produces insignificant influence on fan aerodynamic and aeroacoustic performance, and AC system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002533

Single-effect absorption refrigeration cycle boosted with an ejector-adiabatic absorber using a single solution pump / C. Vereda in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 22–29 Titre : Single-effect absorption refrigeration cycle boosted with an ejector-adiabatic absorber using a single solution pump Titre original : Cycle frigorifique à simple effet à absorption augmenté par un absorbeur à éjecteur adiabatique utilisant une pompe à solution unique Type de document : texte imprimé Auteurs : C. Vereda, Auteur ; R. Ventas, Auteur ; A. Lecuona, Auteur Année de publication : 2014 Article en page(s) : pp. 22–29 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Absorption  hybrid  cycles;  Ammonia-lithium  nitrate;  Cooling;  Two-phase  ejector;  Adiabatic  absorber;  Solar  cooling Résumé : This paper presents a numerical model of a single-effect absorption refrigeration cycle incorporating a triple purpose liquid–vapor ejector acting as pressure booster for refrigerant vapor, adiabatic absorber and controlled solution expansion valve. The promising ammonia-lithium nitrate solution is selected as working pair, being able to produce cold at subzero temperatures, thus valid either for air conditioning or industrial refrigeration. With the use of the liquid–gas ejector, the absorption pressure becomes higher than the evaporation pressure, besides recovering part of the solution pump energy. Results of the simulation show that this innovation behaves like a compressor boosted hybrid cycle without carrying its complexity. It allows decreasing the activation temperature (about 15 °C for a recirculation ratio of 3) and increasing the cooling capacity (reaching a gain of about 100% for a generation temperature of 80 °C). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002880 [article] Single-effect absorption refrigeration cycle boosted with an ejector-adiabatic absorber using a single solution pump = Cycle frigorifique à simple effet à absorption augmenté par un absorbeur à éjecteur adiabatique utilisant une pompe à solution unique [texte imprimé] / C. Vereda, Auteur ; R. Ventas, Auteur ; A. Lecuona, Auteur . - 2014 . - pp. 22–29. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 22–29 Mots-clés : Absorption  hybrid  cycles;  Ammonia-lithium  nitrate;  Cooling;  Two-phase  ejector;  Adiabatic  absorber;  Solar  cooling Résumé : This paper presents a numerical model of a single-effect absorption refrigeration cycle incorporating a triple purpose liquid–vapor ejector acting as pressure booster for refrigerant vapor, adiabatic absorber and controlled solution expansion valve. The promising ammonia-lithium nitrate solution is selected as working pair, being able to produce cold at subzero temperatures, thus valid either for air conditioning or industrial refrigeration. With the use of the liquid–gas ejector, the absorption pressure becomes higher than the evaporation pressure, besides recovering part of the solution pump energy. Results of the simulation show that this innovation behaves like a compressor boosted hybrid cycle without carrying its complexity. It allows decreasing the activation temperature (about 15 °C for a recirculation ratio of 3) and increasing the cooling capacity (reaching a gain of about 100% for a generation temperature of 80 °C). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002880

Component-based, gray-box modeling of ductless multi-split heat pump systems / Howard Cheung in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 30–45 Titre : Component-based, gray-box modeling of ductless multi-split heat pump systems Titre original : Modélisation à « boite grise » définie par l'utilisateur et basée sur les composants, de systèmes de pompe á chaleur multi-split sans conduit Type de document : texte imprimé Auteurs : Howard Cheung, Auteur ; James E. Braun, Auteur Année de publication : 2014 Article en page(s) : pp. 30–45 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Multi-split  heat  pump;  Ductless  heat  pump;  Variable-speed  heat  pump;  Modeling;  Performance  analysis Résumé : Multi-split ductless heat pumps are touted as an energy efficient option for air conditioning and heating in residential and small commercial applications. However, their use of multiple indoor units with variable speed compressor and fans and complicated controls leads to difficulties in understanding their characteristics by experiments only. A method to model the system using gray-box component models and an empirical control algorithm is described in this paper. The model was constructed from experimental results of an 8 kW R410A dual-unit ductless heat pump system having an accumulator. Strategies for modeling systems with accumulators and saturated control inputs are presented. Parametric studies with varying indoor air temperature, individual indoor unit load ratio, indoor fan speed and total indoor load were conducted. The results show that the model predicts system performance accurately and can help to understand the effect of saturated control inputs and changes of accumulator status on system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002855 [article] Component-based, gray-box modeling of ductless multi-split heat pump systems = Modélisation à « boite grise » définie par l'utilisateur et basée sur les composants, de systèmes de pompe á chaleur multi-split sans conduit [texte imprimé] / Howard Cheung, Auteur ; James E. Braun, Auteur . - 2014 . - pp. 30–45. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 30–45 Mots-clés : Multi-split  heat  pump;  Ductless  heat  pump;  Variable-speed  heat  pump;  Modeling;  Performance  analysis Résumé : Multi-split ductless heat pumps are touted as an energy efficient option for air conditioning and heating in residential and small commercial applications. However, their use of multiple indoor units with variable speed compressor and fans and complicated controls leads to difficulties in understanding their characteristics by experiments only. A method to model the system using gray-box component models and an empirical control algorithm is described in this paper. The model was constructed from experimental results of an 8 kW R410A dual-unit ductless heat pump system having an accumulator. Strategies for modeling systems with accumulators and saturated control inputs are presented. Parametric studies with varying indoor air temperature, individual indoor unit load ratio, indoor fan speed and total indoor load were conducted. The results show that the model predicts system performance accurately and can help to understand the effect of saturated control inputs and changes of accumulator status on system performance. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002855

Evaluating performance of mixed mode multistage helium plants for design and off-design conditions by exergy analysis / Arpan Kundu in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 46–57 Titre : Evaluating performance of mixed mode multistage helium plants for design and off-design conditions by exergy analysis Titre original : Evaluation de la performance de systèmes multiétagés à l'hélium à fonctionnement mixte pour conditions de conception et hors-conception grâce à l’analyse exergétique Type de document : texte imprimé Auteurs : Arpan Kundu, Auteur ; Kanchan Chowdhury, Auteur Année de publication : 2014 Article en page(s) : pp. 46–57 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Helium  liquefier;  Refrigerator;  Mixed  mode;  Multistage  systems;  Heat  exchanger  UA;  Exergy  analysis Résumé : Performance of mixed mode helium liquefaction and refrigeration systems based on a number of refrigeration stages has been studied taking compressor discharge pressure, heat exchanger effective UA and expander flow rate as independent parameters. Due to constraints of space and minimum flow rate through expanders (to attain operational reliability), helium plants often have to be designed with heat exchanger UA and number of stages less than the optimum values. It is useful for designers to evaluate the penalty in cold box exergy efficiency when the plant is designed or operated under such constraints. Performance of pure liquefier, pure refrigerator and mixed mode systems when operated at off-design conditions has been evaluated. Exergy efficiency has been used as the tool for the entire analysis of this paper. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002892 [article] Evaluating performance of mixed mode multistage helium plants for design and off-design conditions by exergy analysis = Evaluation de la performance de systèmes multiétagés à l'hélium à fonctionnement mixte pour conditions de conception et hors-conception grâce à l’analyse exergétique [texte imprimé] / Arpan Kundu, Auteur ; Kanchan Chowdhury, Auteur . - 2014 . - pp. 46–57. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 46–57 Mots-clés : Helium  liquefier;  Refrigerator;  Mixed  mode;  Multistage  systems;  Heat  exchanger  UA;  Exergy  analysis Résumé : Performance of mixed mode helium liquefaction and refrigeration systems based on a number of refrigeration stages has been studied taking compressor discharge pressure, heat exchanger effective UA and expander flow rate as independent parameters. Due to constraints of space and minimum flow rate through expanders (to attain operational reliability), helium plants often have to be designed with heat exchanger UA and number of stages less than the optimum values. It is useful for designers to evaluate the penalty in cold box exergy efficiency when the plant is designed or operated under such constraints. Performance of pure liquefier, pure refrigerator and mixed mode systems when operated at off-design conditions has been evaluated. Exergy efficiency has been used as the tool for the entire analysis of this paper. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002892

NLP model-based optimal design of LiBr–H2O absorption refrigeration systems / María S. Mazzei in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 58–70 Titre : NLP model-based optimal design of LiBr–H2O absorption refrigeration systems Titre original : Conception optimale basée sur un modèle PNL (Programmation Non Linéaire) pour des systèmes frigorifiques à absorption de LiBr-H2O Type de document : texte imprimé Auteurs : María S. Mazzei, Auteur ; Miguel C. Mussati, Auteur ; Sergio F. Mussati, Auteur Année de publication : 2014 Article en page(s) : pp. 58–70 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : LiBr–H2O  absorption  refrigeration  systems;  Optimal  design;  Mathematical  programming Résumé : This paper addresses the optimization of a single effect absorption refrigeration system operating with lithium bromide-water solution. A non-linear programming mathematical model is developed to determine the operating conditions and the distribution of the total heat transfer area (sizes) along the involved process units to optimize the following two objective functions: (i) maximization of the coefficient of performance for a given amount of the total heat transfer area, and (ii) minimization of the total heat transfer area of the system for a given cooling capacity. The proposed model can either be used for simulation or optimization purposes. Simulated or optimized values of temperature, pressure, composition and flow rate of all streams and sizing of each process unit are predicted. In addition, because of the non linear nature of the resulting model, a systematic solution procedure is proposed in order to guarantee the model convergence. A detailed discussion of the optimization results are presented through different case studies. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002909 [article] NLP model-based optimal design of LiBr–H2O absorption refrigeration systems = Conception optimale basée sur un modèle PNL (Programmation Non Linéaire) pour des systèmes frigorifiques à absorption de LiBr-H2O [texte imprimé] / María S. Mazzei, Auteur ; Miguel C. Mussati, Auteur ; Sergio F. Mussati, Auteur . - 2014 . - pp. 58–70. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 58–70 Mots-clés : LiBr–H2O  absorption  refrigeration  systems;  Optimal  design;  Mathematical  programming Résumé : This paper addresses the optimization of a single effect absorption refrigeration system operating with lithium bromide-water solution. A non-linear programming mathematical model is developed to determine the operating conditions and the distribution of the total heat transfer area (sizes) along the involved process units to optimize the following two objective functions: (i) maximization of the coefficient of performance for a given amount of the total heat transfer area, and (ii) minimization of the total heat transfer area of the system for a given cooling capacity. The proposed model can either be used for simulation or optimization purposes. Simulated or optimized values of temperature, pressure, composition and flow rate of all streams and sizing of each process unit are predicted. In addition, because of the non linear nature of the resulting model, a systematic solution procedure is proposed in order to guarantee the model convergence. A detailed discussion of the optimization results are presented through different case studies. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002909

A thermodynamic analysis of refrigerants / Piotr A. Domanski in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 71–79 Titre : A thermodynamic analysis of refrigerants : Performance limits of the vapor compression cycle Titre original : Une analyse thermodynamique des frigorigènes : limites des performances du cycle à compression de vapeur Type de document : texte imprimé Auteurs : Piotr A. Domanski, Auteur ; J. Steven Brown, Auteur ; Jaehyeok Heo, Auteur Année de publication : 2014 Article en page(s) : pp. 71–79 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Coefficient  of  performance;  Evolutionary  algorithm;  Refrigerant;  Vapor  compression  cycle Résumé : This paper explores the thermodynamic performance limits of the vapor compression cycle. We have applied evolutionary algorithms to explore the performance of hypothetical refrigerants defined by the thermodynamic parameters used by the extended corresponding states model for fluid properties. We identified optimal values of these parameters required to reach the performance limits. The study confirmed the fundamental trade-off between the coefficient of performance (COP) and volumetric capacity, and indicated refrigerant critical temperature as the dominant parameter influencing the tradeoff. Thermodynamic performance limits depend on the operating conditions and the cycle design. These limits are represented by Pareto fronts developed for the objective functions COP and volumetric capacity. As expected, the performance of current refrigerants falls below the Pareto front limits. We demonstrate that for practical cycles the developed methodology and resulting Pareto fronts are more realistic benchmarks for the performance potentials of refrigerants than is COP alone, which is an efficiency only metric. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002703 [article] A thermodynamic analysis of refrigerants = Une analyse thermodynamique des frigorigènes : limites des performances du cycle à compression de vapeur : Performance limits of the vapor compression cycle [texte imprimé] / Piotr A. Domanski, Auteur ; J. Steven Brown, Auteur ; Jaehyeok Heo, Auteur . - 2014 . - pp. 71–79. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 71–79 Mots-clés : Coefficient  of  performance;  Evolutionary  algorithm;  Refrigerant;  Vapor  compression  cycle Résumé : This paper explores the thermodynamic performance limits of the vapor compression cycle. We have applied evolutionary algorithms to explore the performance of hypothetical refrigerants defined by the thermodynamic parameters used by the extended corresponding states model for fluid properties. We identified optimal values of these parameters required to reach the performance limits. The study confirmed the fundamental trade-off between the coefficient of performance (COP) and volumetric capacity, and indicated refrigerant critical temperature as the dominant parameter influencing the tradeoff. Thermodynamic performance limits depend on the operating conditions and the cycle design. These limits are represented by Pareto fronts developed for the objective functions COP and volumetric capacity. As expected, the performance of current refrigerants falls below the Pareto front limits. We demonstrate that for practical cycles the developed methodology and resulting Pareto fronts are more realistic benchmarks for the performance potentials of refrigerants than is COP alone, which is an efficiency only metric. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002703

A thermodynamic analysis of refrigerants / Mark O. McLinden in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 80–92 Titre : A thermodynamic analysis of refrigerants : Possibilities and tradeoffs for Low-GWP refrigerants Titre original : Une analyse thermodynamique des frigorigènes: possibilités et compromis impliqués pour les frigorigènes à faible GWP Type de document : texte imprimé Auteurs : Mark O. McLinden, Auteur ; Andrei F. Kazakov, Auteur ; J. Steven Brown, Auteur Année de publication : 2014 Article en page(s) : pp. 80–92 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Global  warming  potential;  Low  GWP  refrigerant;  Thermodynamic  properties;  Vapor  compression  cycle Résumé : We explore the possibilities for refrigerants having low global warming potential (GWP). A set of about 1200 candidate fluids is identified from more than 56 000 small molecules examined by applying screening criteria to estimates for GWP, flammability, stability, toxicity, and critical temperature. Methodologies for this screening have been presented in earlier works and are summarized here. The fluids with critical temperatures between 300 K and 400 K (i.e., those that could be used in current types of equipment with minor modifications) number 62. The fluids include halogenated olefins; compounds containing oxygen, nitrogen, or sulfur; as well as carbon dioxide. We discuss the tradeoffs presented by these 62 candidates, considering their thermodynamic properties and their stability and toxicity characteristics. No fluid is ideal in all regards—all have one or more negative attributes: poor thermodynamic properties, toxicity, chemical instability, low to moderate flammability, or very high operating pressures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002661 [article] A thermodynamic analysis of refrigerants = Une analyse thermodynamique des frigorigènes: possibilités et compromis impliqués pour les frigorigènes à faible GWP : Possibilities and tradeoffs for Low-GWP refrigerants [texte imprimé] / Mark O. McLinden, Auteur ; Andrei F. Kazakov, Auteur ; J. Steven Brown, Auteur . - 2014 . - pp. 80–92. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 80–92 Mots-clés : Global  warming  potential;  Low  GWP  refrigerant;  Thermodynamic  properties;  Vapor  compression  cycle Résumé : We explore the possibilities for refrigerants having low global warming potential (GWP). A set of about 1200 candidate fluids is identified from more than 56 000 small molecules examined by applying screening criteria to estimates for GWP, flammability, stability, toxicity, and critical temperature. Methodologies for this screening have been presented in earlier works and are summarized here. The fluids with critical temperatures between 300 K and 400 K (i.e., those that could be used in current types of equipment with minor modifications) number 62. The fluids include halogenated olefins; compounds containing oxygen, nitrogen, or sulfur; as well as carbon dioxide. We discuss the tradeoffs presented by these 62 candidates, considering their thermodynamic properties and their stability and toxicity characteristics. No fluid is ideal in all regards—all have one or more negative attributes: poor thermodynamic properties, toxicity, chemical instability, low to moderate flammability, or very high operating pressures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002661

Improved energy performance of a refrigerating machine using water spray upstream of the condenser / J. Tissot in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 93–105 Titre : Improved energy performance of a refrigerating machine using water spray upstream of the condenser Titre original : Performance énergétique améliorée d'un système frigorifique utilisant une aspersion d'eau en amont du condenseur Type de document : texte imprimé Auteurs : J. Tissot, Auteur ; P. Boulet, Auteur ; F. Trinquet, Auteur Année de publication : 2014 Article en page(s) : pp. 93–105 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Heat  pump;  Condenser;  Spray;  Evaporation;  Energy Résumé : An experimental and numerical study has been carried out on the improvement of the energy performance of a refrigerating machine using a water spray upstream of the condenser. The experimental setup is based on a reversible heat pump used in cooling mode. The spray has been simply added upstream from the heat pump in order to investigate the possible performance improvements on a real machine, leaving its own control system free to adapt itself. Condensation temperature and pressure data have been measured on the refrigerating fluid side, while temperature and humidity have been measured on the air upstream and downstream the condenser. A complete model has been developed, combining a thermodynamic model for the system and heat transfer models on the air and refrigerating fluid sides. Comparisons have been carried out. Results show that water spraying upstream of the condenser may increase the global COP of the system (refrigerating machine plus spraying system) up to 28.9% for relatively hot and dry air conditions (relative humidity 19,7% and temperature 308 K). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002429 [article] Improved energy performance of a refrigerating machine using water spray upstream of the condenser = Performance énergétique améliorée d'un système frigorifique utilisant une aspersion d'eau en amont du condenseur [texte imprimé] / J. Tissot, Auteur ; P. Boulet, Auteur ; F. Trinquet, Auteur . - 2014 . - pp. 93–105. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 93–105 Mots-clés : Heat  pump;  Condenser;  Spray;  Evaporation;  Energy Résumé : An experimental and numerical study has been carried out on the improvement of the energy performance of a refrigerating machine using a water spray upstream of the condenser. The experimental setup is based on a reversible heat pump used in cooling mode. The spray has been simply added upstream from the heat pump in order to investigate the possible performance improvements on a real machine, leaving its own control system free to adapt itself. Condensation temperature and pressure data have been measured on the refrigerating fluid side, while temperature and humidity have been measured on the air upstream and downstream the condenser. A complete model has been developed, combining a thermodynamic model for the system and heat transfer models on the air and refrigerating fluid sides. Comparisons have been carried out. Results show that water spraying upstream of the condenser may increase the global COP of the system (refrigerating machine plus spraying system) up to 28.9% for relatively hot and dry air conditions (relative humidity 19,7% and temperature 308 K). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002429

Plant-wide dynamic and static optimisation of supermarket refrigeration systems / Torben Green in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 106–117 Titre : Plant-wide dynamic and static optimisation of supermarket refrigeration systems Titre original : Optimisation dynamique et statique au niveau de l'ensemble du système frigorifique dans des supermarchés Type de document : texte imprimé Auteurs : Torben Green, Auteur ; Roozbeh Izadi-Zamanabadi, Auteur ; Roozbeh Razavi-Far, Auteur Année de publication : 2014 Article en page(s) : pp. 106–117 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Control;  Refrigeration  systems;  Active  system  monitoring;  Performance  optimization;  Performance  assessment Résumé : Optimising the operation of a supermarket refrigeration system under dynamic as well as steady state conditions is addressed in this paper. For this purpose an appropriate performance function that encompasses food quality, system efficiency, and also component reliability is established. The choice of setup parameters, which are necessary for system performance optimisation, depends on whether the system operates under steady state or dynamic conditions. While operating under steady state conditions, the total system performance is shown to predominantly be influenced by the suction pressure. The dynamic optimisation requires use of dedicated excitation signals. A method for designing such signals under realistic operational conditions is proposed. A derivative free optimisation technique based on Invasive Weed Optimisation (IWO) is utilised to optimise the parameters of the controllers in the system. Simulation results is used to substantiate the suggested methodology. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300217X [article] Plant-wide dynamic and static optimisation of supermarket refrigeration systems = Optimisation dynamique et statique au niveau de l'ensemble du système frigorifique dans des supermarchés [texte imprimé] / Torben Green, Auteur ; Roozbeh Izadi-Zamanabadi, Auteur ; Roozbeh Razavi-Far, Auteur . - 2014 . - pp. 106–117. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 106–117 Mots-clés : Control;  Refrigeration  systems;  Active  system  monitoring;  Performance  optimization;  Performance  assessment Résumé : Optimising the operation of a supermarket refrigeration system under dynamic as well as steady state conditions is addressed in this paper. For this purpose an appropriate performance function that encompasses food quality, system efficiency, and also component reliability is established. The choice of setup parameters, which are necessary for system performance optimisation, depends on whether the system operates under steady state or dynamic conditions. While operating under steady state conditions, the total system performance is shown to predominantly be influenced by the suction pressure. The dynamic optimisation requires use of dedicated excitation signals. A method for designing such signals under realistic operational conditions is proposed. A derivative free optimisation technique based on Invasive Weed Optimisation (IWO) is utilised to optimise the parameters of the controllers in the system. Simulation results is used to substantiate the suggested methodology. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300217X

Influence of two internal irreversibilities on the new thermo-ecological criterion for three-heat-source refrigerators / Brigitte Astrid Medjo Nouadje in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 118–127 Titre : Influence of two internal irreversibilities on the new thermo-ecological criterion for three-heat-source refrigerators Titre original : Influence de deux irréversibilités internes sur les nouveaux critères thermo-écologiques des réfrigérateurs à triple source de chaleur Type de document : texte imprimé Auteurs : Brigitte Astrid Medjo Nouadje, Auteur ; Paiguy Armand Ngouateu Wouagfack, Auteur ; Réné Tchinda, Auteur Année de publication : 2014 Article en page(s) : pp. 118–127 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Absorption  refrigeration  system;  Internal  irreversibility;  Optimization;  Ecological  coefficient  of  performance Résumé : Irreversibility is a phenomenon that affects much the performance of absorption refrigeration systems. Internal irreversibility is produced by the dissipation of the working fluid. This paper studies and analyzes the effect of two internal irreversibilities parameters (the internal irreversibility parameter for generator–absorber assembly and the internal irreversibility parameter for condenser–evaporator assembly) on the optimal ecological performances of an irreversible three-heat-source absorption refrigerator based on the ECOP criterion. The results obtained show that the internal irreversibility parameter for condenser–evaporator assembly affects more the ecological performance of the system than the internal irreversibility parameter for generator–absorber assembly. This is of importance to the optimal design and performance improvement of absorption refrigeration cycles. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002740 [article] Influence of two internal irreversibilities on the new thermo-ecological criterion for three-heat-source refrigerators = Influence de deux irréversibilités internes sur les nouveaux critères thermo-écologiques des réfrigérateurs à triple source de chaleur [texte imprimé] / Brigitte Astrid Medjo Nouadje, Auteur ; Paiguy Armand Ngouateu Wouagfack, Auteur ; Réné Tchinda, Auteur . - 2014 . - pp. 118–127. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 118–127 Mots-clés : Absorption  refrigeration  system;  Internal  irreversibility;  Optimization;  Ecological  coefficient  of  performance Résumé : Irreversibility is a phenomenon that affects much the performance of absorption refrigeration systems. Internal irreversibility is produced by the dissipation of the working fluid. This paper studies and analyzes the effect of two internal irreversibilities parameters (the internal irreversibility parameter for generator–absorber assembly and the internal irreversibility parameter for condenser–evaporator assembly) on the optimal ecological performances of an irreversible three-heat-source absorption refrigerator based on the ECOP criterion. The results obtained show that the internal irreversibility parameter for condenser–evaporator assembly affects more the ecological performance of the system than the internal irreversibility parameter for generator–absorber assembly. This is of importance to the optimal design and performance improvement of absorption refrigeration cycles. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002740

Exergoeconomic analysis of carbon dioxide transcritical refrigeration machines / Farivar Fazelpour in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 128–139 Titre : Exergoeconomic analysis of carbon dioxide transcritical refrigeration machines Titre original : Analyse Exergoéconomique de machines frigorifiques transcritiques au dioxyde de carbone Type de document : texte imprimé Auteurs : Farivar Fazelpour, Auteur ; Tatiana Morosuk, Auteur Année de publication : 2014 Article en page(s) : pp. 128–139 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Transcritical  refrigeration  machine;  Carbon  dioxide;  Exergy  analysis;  Economic  analysis;  Energetic  analysis;  Exergoeconomic  analysis Résumé : In the last two decades many scientific papers and reports have been published in the field of the application of the carbon dioxide as a refrigerant for refrigeration (heat pump) systems. A simple transcritical CO2 refrigeration machine is evaluated from the perspectives of energetic, exergetic, economic and exergoeconomic analyses. Special attention has been paid to the transcritical cycle under hot climatic conditions. The main goal of this paper is to define the energy and cost efficient transcritical CO2 refrigeration machine, therefore the options for the structure and parametric improvements are discussed. Introducing the economizer as an auxiliary component for one-stage transcritical CO2 refrigeration machine helps us to decrease the total cost of the final product by approximately 14%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002508 [article] Exergoeconomic analysis of carbon dioxide transcritical refrigeration machines = Analyse Exergoéconomique de machines frigorifiques transcritiques au dioxyde de carbone [texte imprimé] / Farivar Fazelpour, Auteur ; Tatiana Morosuk, Auteur . - 2014 . - pp. 128–139. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 128–139 Mots-clés : Transcritical  refrigeration  machine;  Carbon  dioxide;  Exergy  analysis;  Economic  analysis;  Energetic  analysis;  Exergoeconomic  analysis Résumé : In the last two decades many scientific papers and reports have been published in the field of the application of the carbon dioxide as a refrigerant for refrigeration (heat pump) systems. A simple transcritical CO2 refrigeration machine is evaluated from the perspectives of energetic, exergetic, economic and exergoeconomic analyses. Special attention has been paid to the transcritical cycle under hot climatic conditions. The main goal of this paper is to define the energy and cost efficient transcritical CO2 refrigeration machine, therefore the options for the structure and parametric improvements are discussed. Introducing the economizer as an auxiliary component for one-stage transcritical CO2 refrigeration machine helps us to decrease the total cost of the final product by approximately 14%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002508

Studies on the performance of a CO2 air conditioning system using an ejector as an expansion device / Jae Seung Lee in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 140–152 Titre : Studies on the performance of a CO2 air conditioning system using an ejector as an expansion device Titre original : Etudes de la performance d'un système de conditionnement d'air au CO2 utilisant un éjecteur comme détendeur Type de document : texte imprimé Auteurs : Jae Seung Lee, Auteur ; Mo Se Kim, Auteur ; Min Soo Kim, Auteur Année de publication : 2014 Article en page(s) : pp. 140–152 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Carbon  dioxide;  Performance;  Ejector;  Air  conditioning Résumé : Environmental issues such as stratospheric ozone depletion and global warming have been the primary motivations for recent research in the air-conditioning and refrigeration fields. The CO2 air-conditioning system forms a transcritical cycle which shows slightly degraded performance compared to the conventional system. To overcome this disadvantage, a cycle adopting an ejector is suggested. Experimental results of a CO2 air-conditioning system using an ejector were compared for various outdoor temperatures and inverter frequencies. The COPs of an air-conditioning system using an ejector and conventional system were calculated and compared based on the pressures and temperatures of experiments. The cooling capacity and COP in the air-conditioning system using an ejector are higher than those in the conventional system at an entrainment ratio greater than 0.76. In addition, better performance is shown at entrainment ratio greater than a certain value in other test conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002272 [article] Studies on the performance of a CO2 air conditioning system using an ejector as an expansion device = Etudes de la performance d'un système de conditionnement d'air au CO2 utilisant un éjecteur comme détendeur [texte imprimé] / Jae Seung Lee, Auteur ; Mo Se Kim, Auteur ; Min Soo Kim, Auteur . - 2014 . - pp. 140–152. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 140–152 Mots-clés : Carbon  dioxide;  Performance;  Ejector;  Air  conditioning Résumé : Environmental issues such as stratospheric ozone depletion and global warming have been the primary motivations for recent research in the air-conditioning and refrigeration fields. The CO2 air-conditioning system forms a transcritical cycle which shows slightly degraded performance compared to the conventional system. To overcome this disadvantage, a cycle adopting an ejector is suggested. Experimental results of a CO2 air-conditioning system using an ejector were compared for various outdoor temperatures and inverter frequencies. The COPs of an air-conditioning system using an ejector and conventional system were calculated and compared based on the pressures and temperatures of experiments. The cooling capacity and COP in the air-conditioning system using an ejector are higher than those in the conventional system at an entrainment ratio greater than 0.76. In addition, better performance is shown at entrainment ratio greater than a certain value in other test conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002272

Simulation and performance optimization of finned tube gas cooler for trans-critical CO2 refrigeration system in Indian context / Dileep Kumar Gupta in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 153–167 Titre : Simulation and performance optimization of finned tube gas cooler for trans-critical CO2 refrigeration system in Indian context Titre original : Simulation et optimisation de la performance du refroidisseur à gaz à tubes ailetés pour un système frigorifique transcritique au CO2 dans le contexte indien Type de document : texte imprimé Auteurs : Dileep Kumar Gupta, Auteur ; M.S. Dasgupta, Auteur Année de publication : 2014 Article en page(s) : pp. 153–167 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Gas  cooler;  CO2  refrigeration  systems;  Trans-critical  refrigeration;  Finned  tube  gas  cooler;  Approach  temperature Résumé : This paper analyzes trans-critical CO2 refrigeration system in typical Indian conditions and the challenges associated with it. A mathematical model for air cooled finned tube gas cooler is developed, validated and used for the performance analysis at various design and operating conditions. A combination of input parameters is employed anticipating that it will enhance heat transfer, reduce the approach temperature and eventually improve the COP of refrigeration system. As the paper reiterates the success of CO2 as refrigerant, it emphasizes upon operating parameters that are based on local environmental conditions for best possible performance of overall system including fan power consumption. Thus the paper help to formulate design guidelines for optimized performance of gas cooler at different ambient temperatures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002752 [article] Simulation and performance optimization of finned tube gas cooler for trans-critical CO2 refrigeration system in Indian context = Simulation et optimisation de la performance du refroidisseur à gaz à tubes ailetés pour un système frigorifique transcritique au CO2 dans le contexte indien [texte imprimé] / Dileep Kumar Gupta, Auteur ; M.S. Dasgupta, Auteur . - 2014 . - pp. 153–167. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 153–167 Mots-clés : Gas  cooler;  CO2  refrigeration  systems;  Trans-critical  refrigeration;  Finned  tube  gas  cooler;  Approach  temperature Résumé : This paper analyzes trans-critical CO2 refrigeration system in typical Indian conditions and the challenges associated with it. A mathematical model for air cooled finned tube gas cooler is developed, validated and used for the performance analysis at various design and operating conditions. A combination of input parameters is employed anticipating that it will enhance heat transfer, reduce the approach temperature and eventually improve the COP of refrigeration system. As the paper reiterates the success of CO2 as refrigerant, it emphasizes upon operating parameters that are based on local environmental conditions for best possible performance of overall system including fan power consumption. Thus the paper help to formulate design guidelines for optimized performance of gas cooler at different ambient temperatures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002752

Effect of vapor-injection technique on the performance of a cascade heat pump water heater / Chul Woo Roh in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 168–177 Titre : Effect of vapor-injection technique on the performance of a cascade heat pump water heater Titre original : Effet de la technique d'injection de vapeur sur la performance d'un chauffe-eau à pompe à chaleur en cascade Type de document : texte imprimé Auteurs : Chul Woo Roh, Auteur ; Min Soo Kim, Auteur Année de publication : 2014 Article en page(s) : pp. 168–177 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Cascade;  Heat  pump;  Vapor  injection;  R404A;  Water  heater Résumé : In this study, we applied a vapor-injection (VI) technique in a cascade heat pump system. The VI was applied to both upper and lower stage cycles. Test results showed that heating and cooling capacities increased by using the VI technique (12% and 6%, respectively); however, the system COP decreased (6.6% at the injection ratio of 16.7%). The cascade system which has a small compression ratio and a cascade condenser, cannot fully utilize the VI's advantages to improve the system COP. However, the VI is effective for the system reliability and capacity improvement. We also found that the VI in the upper and lower stage cycles had different effect on overall cycle operating characteristic. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002545 [article] Effect of vapor-injection technique on the performance of a cascade heat pump water heater = Effet de la technique d'injection de vapeur sur la performance d'un chauffe-eau à pompe à chaleur en cascade [texte imprimé] / Chul Woo Roh, Auteur ; Min Soo Kim, Auteur . - 2014 . - pp. 168–177. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 168–177 Mots-clés : Cascade;  Heat  pump;  Vapor  injection;  R404A;  Water  heater Résumé : In this study, we applied a vapor-injection (VI) technique in a cascade heat pump system. The VI was applied to both upper and lower stage cycles. Test results showed that heating and cooling capacities increased by using the VI technique (12% and 6%, respectively); however, the system COP decreased (6.6% at the injection ratio of 16.7%). The cascade system which has a small compression ratio and a cascade condenser, cannot fully utilize the VI's advantages to improve the system COP. However, the VI is effective for the system reliability and capacity improvement. We also found that the VI in the upper and lower stage cycles had different effect on overall cycle operating characteristic. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002545

Simplified explicit calculation algorithms for determining the performance of refrigerant coils in vapour-compression systems / C. K. Lee in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 178–188 Titre : Simplified explicit calculation algorithms for determining the performance of refrigerant coils in vapour-compression systems Titre original : Algorithmes explicites simplifiés de calcul pour la détermination de la performance de serpentins frigorifiques dans des systèmes à compression de vapeur Type de document : texte imprimé Auteurs : C. K. Lee, Auteur ; H. N. Lam, Auteur Année de publication : 2014 Article en page(s) : pp. 178–188 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Refrigerant  coil;  Vapour-compression  cycle;  Overall  heat  transfer  value;  Heat  transfer  coefficient;  Temperature  effectiveness Résumé : Simplified explicit calculation algorithms were proposed for determining the performance of the condenser, evaporator and air cooler in a vapour-compression system based on a zone-model approach. It was assumed that the fluid temperature changes in the sub-cooled and superheated portions were small and that the wet portion of an air cooler only occurred in the entire saturated portion if it was not fully-dry. With R134a employed as the refrigerant, the simulated coil capacity based on the present modelling approach were compared with those based on a multi-node numerical approach at different refrigerant mass flow rates. It was found that the errors in the simulated specific enthalpy change of the refrigerant across the coil did not exceed 3.6% in all cases. In particular, the errors incurred by employing the present modelling approach in simulating the capacity and compressor power input of a sample water-cooled chiller at different condenser and evaporator fluid entering temperatures were less than 2.7% and 3.1% respectively. This showed that the present approach could be a good choice for improving the computation efficiency of a vapour-compression system significantly while the accuracy of the simulation could still be maintained at an acceptable level. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002326 [article] Simplified explicit calculation algorithms for determining the performance of refrigerant coils in vapour-compression systems = Algorithmes explicites simplifiés de calcul pour la détermination de la performance de serpentins frigorifiques dans des systèmes à compression de vapeur [texte imprimé] / C. K. Lee, Auteur ; H. N. Lam, Auteur . - 2014 . - pp. 178–188. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 178–188 Mots-clés : Refrigerant  coil;  Vapour-compression  cycle;  Overall  heat  transfer  value;  Heat  transfer  coefficient;  Temperature  effectiveness Résumé : Simplified explicit calculation algorithms were proposed for determining the performance of the condenser, evaporator and air cooler in a vapour-compression system based on a zone-model approach. It was assumed that the fluid temperature changes in the sub-cooled and superheated portions were small and that the wet portion of an air cooler only occurred in the entire saturated portion if it was not fully-dry. With R134a employed as the refrigerant, the simulated coil capacity based on the present modelling approach were compared with those based on a multi-node numerical approach at different refrigerant mass flow rates. It was found that the errors in the simulated specific enthalpy change of the refrigerant across the coil did not exceed 3.6% in all cases. In particular, the errors incurred by employing the present modelling approach in simulating the capacity and compressor power input of a sample water-cooled chiller at different condenser and evaporator fluid entering temperatures were less than 2.7% and 3.1% respectively. This showed that the present approach could be a good choice for improving the computation efficiency of a vapour-compression system significantly while the accuracy of the simulation could still be maintained at an acceptable level. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002326

Modelling thermostatic expansion valves / Ian W. Eames in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 189–197 Titre : Modelling thermostatic expansion valves Titre original : Modélisation thermostatique des détendeurs Type de document : texte imprimé Auteurs : Ian W. Eames, Auteur ; Adriano Milazzo, Auteur ; Graeme G. Maidment, Auteur Année de publication : 2014 Article en page(s) : pp. 189–197 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Vapour  compression  refrigerator;  Simulation;  Modelling;  Thermostatic  expansion  valve;  Software Résumé : This paper describes and evaluates the development of generalised steady state and transient mathematical models for thermostatic expansion valves (TEVs) of the types used in commercial refrigeration systems. The model is of a generalised nature, because it is not necessary to input performance or geometrical data for a particular valve to operate the model. However, if required, the models can provide an accurate correlation of valve manufacturer's data. Derivations are provided and validating data is presented. The mathematical models described in the paper form part of computer software that simulates the thermal operation of whole refrigeration systems. The software is titled Vapour Compression Refrigeration System (VCRS) simulator, and by way of example the paper presents results from the VCRS simulator which are used to aid a discussion of operating faults, such as hunting and under damping and their possible causes, where these can be attributed to the expansion valve. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001576 [article] Modelling thermostatic expansion valves = Modélisation thermostatique des détendeurs [texte imprimé] / Ian W. Eames, Auteur ; Adriano Milazzo, Auteur ; Graeme G. Maidment, Auteur . - 2014 . - pp. 189–197. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 189–197 Mots-clés : Vapour  compression  refrigerator;  Simulation;  Modelling;  Thermostatic  expansion  valve;  Software Résumé : This paper describes and evaluates the development of generalised steady state and transient mathematical models for thermostatic expansion valves (TEVs) of the types used in commercial refrigeration systems. The model is of a generalised nature, because it is not necessary to input performance or geometrical data for a particular valve to operate the model. However, if required, the models can provide an accurate correlation of valve manufacturer's data. Derivations are provided and validating data is presented. The mathematical models described in the paper form part of computer software that simulates the thermal operation of whole refrigeration systems. The software is titled Vapour Compression Refrigeration System (VCRS) simulator, and by way of example the paper presents results from the VCRS simulator which are used to aid a discussion of operating faults, such as hunting and under damping and their possible causes, where these can be attributed to the expansion valve. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001576

Nucleate boiling heat transfer coefficients of HFO1234yf on various enhanced surfaces / Yohan, Lee in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 198–205 Titre : Nucleate boiling heat transfer coefficients of HFO1234yf on various enhanced surfaces Titre original : Coefficients de transfert de chaleur d'ébullition nucléée d'HFO1234yf sur diverses surfaces augmentées Type de document : texte imprimé Auteurs : Yohan, Lee, Auteur ; Dong Gyu Kang, Auteur ; Joo-Hyung Kim, Auteur Année de publication : 2014 Article en page(s) : pp. 198–205 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Nucleate  boiling;  Heat  transfer  coefficient;  Alternative  refrigerant;  Enhanced  surfaces;  Evaporators;  HFO1234yf Résumé : In this study, nucleate boiling heat transfer coefficients (HTCs) of HFO1234yf HFC134a are measured on a flat plain, Turbo-B, Turbo-C, and Thermoexcel-E surfaces. All data are taken at the liquid pool temperature of 7 °C on small flat horizontal square copper plates (9.53 mm × 9.53 mm) at heat fluxes from 10 kW m−2 to 200 kW m−2 with an interval of 10 kW m−2. Test results show that nucleate boiling HTCs of HFO1234yf on all four surfaces are similar to those of HFC134a at all heat fluxes tested in this study. At heat fluxes below 150 kW m−2, Thermoexcel-E surface shows the highest heat transfer performance and hence is the best surface for the manufacture of the evaporators in refrigeration and air-conditioning equipment. On the other hand, at high heat fluxes above 150 kW m−2, Turbo-B and Turbo-C show better heat transfer performance than Thermoexcel-E and hence are good for electronic cooling applications. Overall, HFO1234yf is a good long term candidate with excellent environmental properties to replace successfully HFC134a from the view point of pool boiling heat transfer. Hence HFO1234yf can be readily applied to the conventional evaporators designed for HFC134a. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300248X [article] Nucleate boiling heat transfer coefficients of HFO1234yf on various enhanced surfaces = Coefficients de transfert de chaleur d'ébullition nucléée d'HFO1234yf sur diverses surfaces augmentées [texte imprimé] / Yohan, Lee, Auteur ; Dong Gyu Kang, Auteur ; Joo-Hyung Kim, Auteur . - 2014 . - pp. 198–205. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 198–205 Mots-clés : Nucleate  boiling;  Heat  transfer  coefficient;  Alternative  refrigerant;  Enhanced  surfaces;  Evaporators;  HFO1234yf Résumé : In this study, nucleate boiling heat transfer coefficients (HTCs) of HFO1234yf HFC134a are measured on a flat plain, Turbo-B, Turbo-C, and Thermoexcel-E surfaces. All data are taken at the liquid pool temperature of 7 °C on small flat horizontal square copper plates (9.53 mm × 9.53 mm) at heat fluxes from 10 kW m−2 to 200 kW m−2 with an interval of 10 kW m−2. Test results show that nucleate boiling HTCs of HFO1234yf on all four surfaces are similar to those of HFC134a at all heat fluxes tested in this study. At heat fluxes below 150 kW m−2, Thermoexcel-E surface shows the highest heat transfer performance and hence is the best surface for the manufacture of the evaporators in refrigeration and air-conditioning equipment. On the other hand, at high heat fluxes above 150 kW m−2, Turbo-B and Turbo-C show better heat transfer performance than Thermoexcel-E and hence are good for electronic cooling applications. Overall, HFO1234yf is a good long term candidate with excellent environmental properties to replace successfully HFC134a from the view point of pool boiling heat transfer. Hence HFO1234yf can be readily applied to the conventional evaporators designed for HFC134a. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300248X

Flow boiling heat transfer characteristics of nano-refrigerants in a horizontal tube / Bin Sun in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 206–214 Titre : Flow boiling heat transfer characteristics of nano-refrigerants in a horizontal tube Titre original : Caractéristiques du transfert de chaleur d'écoulement en ébullition de nano-frigorigènes dans un tube horizontal Type de document : texte imprimé Auteurs : Bin Sun, Auteur ; Di Yang, Auteur Année de publication : 2014 Article en page(s) : pp. 206–214 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Nano-refrigerant;  Heat  transfer  enhancement;  Flow  boiling Résumé : The flow boiling heat transfer characteristics of four nano-refrigerants with different mass fractions, qualities, and mass velocities in a horizontal tube were studied. The nano-refrigerants were Cu-R141b, Al-R141b, Al2O3-R141b, and CuO-R141b. The nanoparticle mass fractions were 0.1 wt%, 0.2 wt%, and 0.3 wt%; the quality ranged within 0.3–0.8; and the mass velocities were 120, 210, and 330 kg m−2 s−1. Results showed that the flow boiling heat transfer was enhanced by nanoparticle addition. The heat transfer coefficient of the nano-refrigerant increased with increased mass fraction, quality, and mass velocity. The mass fraction of nanoparticles was the main factor that influenced the heat transfer coefficient. The heat transfer enhancement effects of the different nano-refrigerants differed, with the highest enhancement achieved using Cu-R141b. At G = 120 kg m−2 s−1 and 0.3 wt% mass fraction, the maximum heat transfer coefficient of Cu-R141b increased by 49% (average increase = 27%). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002284 [article] Flow boiling heat transfer characteristics of nano-refrigerants in a horizontal tube = Caractéristiques du transfert de chaleur d'écoulement en ébullition de nano-frigorigènes dans un tube horizontal [texte imprimé] / Bin Sun, Auteur ; Di Yang, Auteur . - 2014 . - pp. 206–214. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 206–214 Mots-clés : Nano-refrigerant;  Heat  transfer  enhancement;  Flow  boiling Résumé : The flow boiling heat transfer characteristics of four nano-refrigerants with different mass fractions, qualities, and mass velocities in a horizontal tube were studied. The nano-refrigerants were Cu-R141b, Al-R141b, Al2O3-R141b, and CuO-R141b. The nanoparticle mass fractions were 0.1 wt%, 0.2 wt%, and 0.3 wt%; the quality ranged within 0.3–0.8; and the mass velocities were 120, 210, and 330 kg m−2 s−1. Results showed that the flow boiling heat transfer was enhanced by nanoparticle addition. The heat transfer coefficient of the nano-refrigerant increased with increased mass fraction, quality, and mass velocity. The mass fraction of nanoparticles was the main factor that influenced the heat transfer coefficient. The heat transfer enhancement effects of the different nano-refrigerants differed, with the highest enhancement achieved using Cu-R141b. At G = 120 kg m−2 s−1 and 0.3 wt% mass fraction, the maximum heat transfer coefficient of Cu-R141b increased by 49% (average increase = 27%). En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002284

Heat transfer measurements and correlation of refrigerant flow boiling in tube filled with copper foam / Yu Zhu in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 215–226 Titre : Heat transfer measurements and correlation of refrigerant flow boiling in tube filled with copper foam Titre original : Mesures du transfert de chaleur et corrélation entre les mesures et l'ébullition en écoulement du frigorigène à l'intérieur d'un tube rempli de mousse de cuivre Type de document : texte imprimé Auteurs : Yu Zhu, Auteur ; Haitao Hu, Auteur ; Shuo Sun, Auteur Année de publication : 2014 Article en page(s) : pp. 215–226 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Metal  foam;  Flow;  Boiling;  Flow  pattern;  Heat  transfer;  Correlation Résumé : Flow boiling heat transfer characteristics of refrigerant in tubes filled with metal foams were experimentally investigated at a saturation temperature of 7 °C, mass flux from 10 to 90 kg m−2 s−1, vapor quality from 0.1 to 0.8 and heat flux from 3.1 to 18.3 kW m−2. The refrigerant is R410A. The test sections are tubes with inner diameter of 23.4 or 13.8 mm, filled with 5 or 10 PPI copper foam. The experimental results reveal that, metal foam enhances the flow boiling heat transfer by a maximum of 220% and promotes the flow pattern transition from stratified flow to stratified-wavy flow and from stratified-wavy flow to annular flow. The heat transfer coefficient decreases with vapor quality under low mass flux, while it increases with vapor quality under high mass flux. A correlation for predicting the flow boiling heat transfer was developed and it agrees well with the experimental data. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001011 [article] Heat transfer measurements and correlation of refrigerant flow boiling in tube filled with copper foam = Mesures du transfert de chaleur et corrélation entre les mesures et l'ébullition en écoulement du frigorigène à l'intérieur d'un tube rempli de mousse de cuivre [texte imprimé] / Yu Zhu, Auteur ; Haitao Hu, Auteur ; Shuo Sun, Auteur . - 2014 . - pp. 215–226. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 215–226 Mots-clés : Metal  foam;  Flow;  Boiling;  Flow  pattern;  Heat  transfer;  Correlation Résumé : Flow boiling heat transfer characteristics of refrigerant in tubes filled with metal foams were experimentally investigated at a saturation temperature of 7 °C, mass flux from 10 to 90 kg m−2 s−1, vapor quality from 0.1 to 0.8 and heat flux from 3.1 to 18.3 kW m−2. The refrigerant is R410A. The test sections are tubes with inner diameter of 23.4 or 13.8 mm, filled with 5 or 10 PPI copper foam. The experimental results reveal that, metal foam enhances the flow boiling heat transfer by a maximum of 220% and promotes the flow pattern transition from stratified flow to stratified-wavy flow and from stratified-wavy flow to annular flow. The heat transfer coefficient decreases with vapor quality under low mass flux, while it increases with vapor quality under high mass flux. A correlation for predicting the flow boiling heat transfer was developed and it agrees well with the experimental data. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001011

Experimental study on thermal characteristics of ammonia flow boiling in a plate evaporator at low mass flux / Kohei Koyama in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 227–235 Titre : Experimental study on thermal characteristics of ammonia flow boiling in a plate evaporator at low mass flux Titre original : Etude expérimentale des caractéristiques thermiques de l'ébullition en écoulement d'ammoniac dans un évaporateur de plaques à faible flux massique Type de document : texte imprimé Auteurs : Kohei Koyama, Auteur ; Hirotaka Chiyoda, Auteur ; Hirofumi Arima, Auteur Année de publication : 2014 Article en page(s) : pp. 227–235 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flow  boiling;  Heat  transfer  coefficient;  Heat  exchanger;  OTEC;  Lockhart–Martinelli  parameter Résumé : Thermal characteristics of a plate evaporator using ammonia are experimentally investigated. The effects of mass flux, heat flux, channel height, and saturation pressure on heat transfer coefficient of the evaporator are discussed. The experiments are conducted for mass flux (5 and 7.5 kg m−2 s−1), heat flux (10, 15, and 20 kW m−2), channel height (1, 2, and 5 mm), and saturation pressure (0.7 and 0.9 MPa). Heat transfer coefficient is obtained as a function of quality for all experimental conditions. The characteristics of heat transfer coefficient are discussed and compared with those of earlier works. All experimental results are compiled by using Lockhart–Martinelli parameter. The developed empirical correlation predicts 85% of the experimental data within ±30% range. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002405 [article] Experimental study on thermal characteristics of ammonia flow boiling in a plate evaporator at low mass flux = Etude expérimentale des caractéristiques thermiques de l'ébullition en écoulement d'ammoniac dans un évaporateur de plaques à faible flux massique [texte imprimé] / Kohei Koyama, Auteur ; Hirotaka Chiyoda, Auteur ; Hirofumi Arima, Auteur . - 2014 . - pp. 227–235. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 227–235 Mots-clés : Flow  boiling;  Heat  transfer  coefficient;  Heat  exchanger;  OTEC;  Lockhart–Martinelli  parameter Résumé : Thermal characteristics of a plate evaporator using ammonia are experimentally investigated. The effects of mass flux, heat flux, channel height, and saturation pressure on heat transfer coefficient of the evaporator are discussed. The experiments are conducted for mass flux (5 and 7.5 kg m−2 s−1), heat flux (10, 15, and 20 kW m−2), channel height (1, 2, and 5 mm), and saturation pressure (0.7 and 0.9 MPa). Heat transfer coefficient is obtained as a function of quality for all experimental conditions. The characteristics of heat transfer coefficient are discussed and compared with those of earlier works. All experimental results are compiled by using Lockhart–Martinelli parameter. The developed empirical correlation predicts 85% of the experimental data within ±30% range. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002405

Condensation heat transfer and pressure drop in flattened microfin tubes having different aspect ratios / E. J. Lee in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 236–249 Titre : Condensation heat transfer and pressure drop in flattened microfin tubes having different aspect ratios Titre original : Transfert de chaleur de condensation et chute de pression dans des tubes à micro-ailettes aplatie avec différents rapports longueur-diamètre Type de document : texte imprimé Auteurs : E. J. Lee, Auteur ; N. H. Kim, Auteur ; H. W. Byun, Auteur Année de publication : 2014 Article en page(s) : pp. 236–249 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Microfin;  Tube;  R410A Résumé : In this study, condensation heat transfer coefficients and pressure drops of R-410A are obtained in flattened microfin tubes made from 7.0 mm O.D. round microfin tubes. The test range covers saturation temperature 45 °C, mass flux 100–400 kg m−2 s−1 and quality 0.2–0.8. Results show that the effect of aspect ratio on condensation heat transfer coefficient is dependent on the flow pattern. For annular flow, the heat transfer coefficient increases as aspect ratio increases. For stratified flow, however, the heat transfer coefficient decreases as aspect ratio increases. The pressure drop always increases as aspect ratio increases. Possible reasoning is provided based on the estimated flow pattern in flat microfin tubes. Comparison with existing round microfin tube correlations is made. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002697 [article] Condensation heat transfer and pressure drop in flattened microfin tubes having different aspect ratios = Transfert de chaleur de condensation et chute de pression dans des tubes à micro-ailettes aplatie avec différents rapports longueur-diamètre [texte imprimé] / E. J. Lee, Auteur ; N. H. Kim, Auteur ; H. W. Byun, Auteur . - 2014 . - pp. 236–249. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 236–249 Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Microfin;  Tube;  R410A Résumé : In this study, condensation heat transfer coefficients and pressure drops of R-410A are obtained in flattened microfin tubes made from 7.0 mm O.D. round microfin tubes. The test range covers saturation temperature 45 °C, mass flux 100–400 kg m−2 s−1 and quality 0.2–0.8. Results show that the effect of aspect ratio on condensation heat transfer coefficient is dependent on the flow pattern. For annular flow, the heat transfer coefficient increases as aspect ratio increases. For stratified flow, however, the heat transfer coefficient decreases as aspect ratio increases. The pressure drop always increases as aspect ratio increases. Possible reasoning is provided based on the estimated flow pattern in flat microfin tubes. Comparison with existing round microfin tube correlations is made. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002697

Condensation of the low GWP refrigerant HFO1234ze(E) inside a Brazed Plate Heat Exchanger / Giovanni A. Longo in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 250–259 Titre : Condensation of the low GWP refrigerant HFO1234ze(E) inside a Brazed Plate Heat Exchanger Titre original : Condensation du frigorigène à faible GWP HFO1234ze dans un échangeur de chaleur à plaques brasées Type de document : texte imprimé Auteurs : Giovanni A. Longo, Auteur ; Claudio Zilio, Auteur ; Giulia Righetti, Auteur Année de publication : 2014 Article en page(s) : pp. 250–259 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Super-heat;  GWP;  BPHE Résumé : This paper presents heat transfer coefficients and pressure drops measured during condensation of the low GWP refrigerant HFO1234ze(E) inside a BPHE. The condensation temperature ranges between 24.8 and 40.2 °C, the refrigerant mass flux from 10.7 to 39.9 kg m−2 s−1 and the heat flux from 5.3 to 26 kW m−2. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux and vapour super-heating. At low refrigerant mass fluxes (<20 kg m−2 s−1) the heat transfer coefficients are independent of mass flux and condensation is gravity-dominated. For higher refrigerant mass fluxes (>20 kg m−2 s−1) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. In the forced convection condensation region the heat transfer coefficients show a 32%–35% enhancement for a doubling of the refrigerant mass flux. The condensation heat transfer coefficients of super-heated vapour are from 8% to 11% higher than those of saturated vapour. HFO1234ze(E) exhibits lower (4%–6%) heat transfer coefficients and higher (10%) frictional pressure drops than those of HFC134a. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002211 [article] Condensation of the low GWP refrigerant HFO1234ze(E) inside a Brazed Plate Heat Exchanger = Condensation du frigorigène à faible GWP HFO1234ze dans un échangeur de chaleur à plaques brasées [texte imprimé] / Giovanni A. Longo, Auteur ; Claudio Zilio, Auteur ; Giulia Righetti, Auteur . - 2014 . - pp. 250–259. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 250–259 Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Super-heat;  GWP;  BPHE Résumé : This paper presents heat transfer coefficients and pressure drops measured during condensation of the low GWP refrigerant HFO1234ze(E) inside a BPHE. The condensation temperature ranges between 24.8 and 40.2 °C, the refrigerant mass flux from 10.7 to 39.9 kg m−2 s−1 and the heat flux from 5.3 to 26 kW m−2. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux and vapour super-heating. At low refrigerant mass fluxes (<20 kg m−2 s−1) the heat transfer coefficients are independent of mass flux and condensation is gravity-dominated. For higher refrigerant mass fluxes (>20 kg m−2 s−1) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. In the forced convection condensation region the heat transfer coefficients show a 32%–35% enhancement for a doubling of the refrigerant mass flux. The condensation heat transfer coefficients of super-heated vapour are from 8% to 11% higher than those of saturated vapour. HFO1234ze(E) exhibits lower (4%–6%) heat transfer coefficients and higher (10%) frictional pressure drops than those of HFC134a. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002211

The impact of fouling on the condenser of a vapor compression refrigeration system / Bilal A. Qureshi in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 260–266 Titre : The impact of fouling on the condenser of a vapor compression refrigeration system : An experimental observation Titre original : L'impact de l'encrassement du condenseur d'un système frigorifique à compression de vapeur : une observation expérimentale Type de document : texte imprimé Auteurs : Bilal A. Qureshi, Auteur ; Syed M. Zubair, Auteur Année de publication : 2014 Article en page(s) : pp. 260–266 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Vapor  compression;  Experiment;  Refrigeration;  R22;  Logarithmic;  Condenser Résumé : In this paper, an experimental study on the nature of the effects of condenser fouling on some performance characteristics and properties of a simple vapor compression system is presented. This is performed by gradually blocking the condenser air passage and measuring the change in condenser pressure, superheat temperature at the compressor exit, compressor power consumption and COP. The room temperature is kept at approximately 21 °C while the ambient temperature is at 31.6 °C with R22 as the cycle refrigerant. The variation in the above-mentioned quantities is found to be logarithmic in nature and this is connected to heat exchanger theory for phase change processes. Comparison with other works is also done and a consistent behavior is concluded for both properties as well as performance parameters. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300220X [article] The impact of fouling on the condenser of a vapor compression refrigeration system = L'impact de l'encrassement du condenseur d'un système frigorifique à compression de vapeur : une observation expérimentale : An experimental observation [texte imprimé] / Bilal A. Qureshi, Auteur ; Syed M. Zubair, Auteur . - 2014 . - pp. 260–266. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 260–266 Mots-clés : Vapor  compression;  Experiment;  Refrigeration;  R22;  Logarithmic;  Condenser Résumé : In this paper, an experimental study on the nature of the effects of condenser fouling on some performance characteristics and properties of a simple vapor compression system is presented. This is performed by gradually blocking the condenser air passage and measuring the change in condenser pressure, superheat temperature at the compressor exit, compressor power consumption and COP. The room temperature is kept at approximately 21 °C while the ambient temperature is at 31.6 °C with R22 as the cycle refrigerant. The variation in the above-mentioned quantities is found to be logarithmic in nature and this is connected to heat exchanger theory for phase change processes. Comparison with other works is also done and a consistent behavior is concluded for both properties as well as performance parameters. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071300220X

Experimental investigation of two-phase flow characteristics of LiBr/H2O solution through orifice plates in vacuum environment / Sheng Wang in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 267–274 Titre : Experimental investigation of two-phase flow characteristics of LiBr/H2O solution through orifice plates in vacuum environment Titre original : Etude expérimentale des caractéristiques diphasiques d'une solution de LiBr/H2O à travers des distributeurs d'air dans un environnement sous vide Type de document : texte imprimé Auteurs : Sheng Wang, Auteur ; Xiaoyun Xie, Auteur ; Yi, Jiang, Auteur Année de publication : 2014 Article en page(s) : pp. 267–274 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Two-phase  flow;  LiBr/H2O  solution;  Choked  flow;  Orifice  plate;  Vacuum Résumé : A new type of multi-stage elementary unit for generating and condensing processes in absorption heat pumps was introduced. One stage of the elementary unit was built, in which the LiBr/H2O solution was concentrated by flash evaporation when flowing through an orifice plate to the generating space. Experiments were carried out to study the flow characteristics of LiBr/H2O solution through an orifice plate in generating processes. The experimental results showed that the reduction of the mass flow rate of the two-phase flow reached a maximum of 24.5%. The mass fraction of gas of the two-phase flow was proportional to its superheat. When the mass transfer pressure difference was higher than 7 kPa or the mass fraction of gas was larger than 0.70%, the flow was choked, and the flow coefficient was reduced as the mass fraction of gas increased, reaching a minimum value of 0.64. A regression model for the flow coefficient of the two-phase LiBr/H2O solution was obtained. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002417 [article] Experimental investigation of two-phase flow characteristics of LiBr/H2O solution through orifice plates in vacuum environment = Etude expérimentale des caractéristiques diphasiques d'une solution de LiBr/H2O à travers des distributeurs d'air dans un environnement sous vide [texte imprimé] / Sheng Wang, Auteur ; Xiaoyun Xie, Auteur ; Yi, Jiang, Auteur . - 2014 . - pp. 267–274. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 267–274 Mots-clés : Two-phase  flow;  LiBr/H2O  solution;  Choked  flow;  Orifice  plate;  Vacuum Résumé : A new type of multi-stage elementary unit for generating and condensing processes in absorption heat pumps was introduced. One stage of the elementary unit was built, in which the LiBr/H2O solution was concentrated by flash evaporation when flowing through an orifice plate to the generating space. Experiments were carried out to study the flow characteristics of LiBr/H2O solution through an orifice plate in generating processes. The experimental results showed that the reduction of the mass flow rate of the two-phase flow reached a maximum of 24.5%. The mass fraction of gas of the two-phase flow was proportional to its superheat. When the mass transfer pressure difference was higher than 7 kPa or the mass fraction of gas was larger than 0.70%, the flow was choked, and the flow coefficient was reduced as the mass fraction of gas increased, reaching a minimum value of 0.64. A regression model for the flow coefficient of the two-phase LiBr/H2O solution was obtained. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002417

Experimental investigation of the refrigerant flow of isobutane (R600a) through adiabatic capillary tubes / Matthias Schenk in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 275–280 Titre : Experimental investigation of the refrigerant flow of isobutane (R600a) through adiabatic capillary tubes Titre original : Etude expérimentale de l'écoulement du frigorigène isobutane (R600a) dans des tubes capillaires adiabatiques Type de document : texte imprimé Auteurs : Matthias Schenk, Auteur ; Lothar R. Oellrich, Auteur Année de publication : 2014 Article en page(s) : pp. 275–280 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Adiabatic  capillary  tube;  R600a;  Experimental  results;  Factorial  design;  Choked  flow Résumé : Capillary tubes are widely used as expansion device in small scale refrigeration systems. Despite the simple geometry one finds complex physical processes during the throttling in the capillary tube, which were subject of many studies in the last decades. However, there is currently only one source of experimental data for the refrigerant isobutane (R600a) and adiabatic capillary tubes (Melo et al., 1999). In order to close this gap a test rig was built and experimental data in the range of typical small scale refrigeration systems was collected. The measured mass flow rates span from 0.64 kg h−1 to 1.93 kg h−1. Additionally, the effect of critical flows (Choked Flow) is shown by means of an extra performed test. The semi-algebraic equation from Hermes et al. (2010) showed a remarkable level of agreement by predicting 94% of all points within a ±10% error band. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002338 [article] Experimental investigation of the refrigerant flow of isobutane (R600a) through adiabatic capillary tubes = Etude expérimentale de l'écoulement du frigorigène isobutane (R600a) dans des tubes capillaires adiabatiques [texte imprimé] / Matthias Schenk, Auteur ; Lothar R. Oellrich, Auteur . - 2014 . - pp. 275–280. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 275–280 Mots-clés : Adiabatic  capillary  tube;  R600a;  Experimental  results;  Factorial  design;  Choked  flow Résumé : Capillary tubes are widely used as expansion device in small scale refrigeration systems. Despite the simple geometry one finds complex physical processes during the throttling in the capillary tube, which were subject of many studies in the last decades. However, there is currently only one source of experimental data for the refrigerant isobutane (R600a) and adiabatic capillary tubes (Melo et al., 1999). In order to close this gap a test rig was built and experimental data in the range of typical small scale refrigeration systems was collected. The measured mass flow rates span from 0.64 kg h−1 to 1.93 kg h−1. Additionally, the effect of critical flows (Choked Flow) is shown by means of an extra performed test. The semi-algebraic equation from Hermes et al. (2010) showed a remarkable level of agreement by predicting 94% of all points within a ±10% error band. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002338

Performance predictions using Artificial Neural Network for isobutane flow in non-adiabatic capillary tubes / M. Heimel in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 281–289 Titre : Performance predictions using Artificial Neural Network for isobutane flow in non-adiabatic capillary tubes Titre original : Prévisions de la performance de l'écoulement d'isobutane dans un tube capillaire non-adiabatique utilisant un réseau neuronal artificiel Type de document : texte imprimé Auteurs : M. Heimel, Auteur ; W. Lang, Auteur ; R. Almbauer, Auteur Année de publication : 2014 Article en page(s) : pp. 281–289 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Capillary  tube;  Artificial  Neural  Network;  Heat  exchanger;  Isobutane;  Non-adiabatic Résumé : This work presents an Artificial Neural Network (ANN) model of non-adiabatic capillary tubes for isobutane (R600a) as refrigerant. The basis therefore is data obtained by a 1d homogeneous model which has been validated by own measurements and measurements from literature. With this method it is possible to account for choked, non-choked, and also for two-phase inlet conditions, whereas most of the correlations reported in literature are not capable of predicting mass flow rates for non-choked and two-phase inlet conditions. The presented models are valid for a broad range of input parameters in respect to domestic applications – the mass flow rates range from 0 to 5 kg h−1, inlet pressure is from saturation pressure at ambient conditions up to 10 bar, the inlet quality is from 0.5 (capillary) and 0.7 (suction line) to 0 and subcooling (capillary) and superheating (suction line) from 0 K to 30 K. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002260 [article] Performance predictions using Artificial Neural Network for isobutane flow in non-adiabatic capillary tubes = Prévisions de la performance de l'écoulement d'isobutane dans un tube capillaire non-adiabatique utilisant un réseau neuronal artificiel [texte imprimé] / M. Heimel, Auteur ; W. Lang, Auteur ; R. Almbauer, Auteur . - 2014 . - pp. 281–289. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 281–289 Mots-clés : Capillary  tube;  Artificial  Neural  Network;  Heat  exchanger;  Isobutane;  Non-adiabatic Résumé : This work presents an Artificial Neural Network (ANN) model of non-adiabatic capillary tubes for isobutane (R600a) as refrigerant. The basis therefore is data obtained by a 1d homogeneous model which has been validated by own measurements and measurements from literature. With this method it is possible to account for choked, non-choked, and also for two-phase inlet conditions, whereas most of the correlations reported in literature are not capable of predicting mass flow rates for non-choked and two-phase inlet conditions. The presented models are valid for a broad range of input parameters in respect to domestic applications – the mass flow rates range from 0 to 5 kg h−1, inlet pressure is from saturation pressure at ambient conditions up to 10 bar, the inlet quality is from 0.5 (capillary) and 0.7 (suction line) to 0 and subcooling (capillary) and superheating (suction line) from 0 K to 30 K. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002260

Experimental study on flooding and flow reversal in small diameter tubes with various inclinations and horizontal lengths / Tiandong Guo in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 290–298 Titre : Experimental study on flooding and flow reversal in small diameter tubes with various inclinations and horizontal lengths Titre original : Etude expérimentale sur le noyage et l'inversion de l'écoulement dans des tubes de faible diamètre avec différentes inclinaisons et longueurs horizontales Type de document : texte imprimé Auteurs : Tiandong Guo, Auteur ; Ji Hwan Jeong, Auteur Année de publication : 2014 Article en page(s) : pp. 290–298 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flooding;  Flow  reversal;  Counter-current  flow;  Suction  pipe;  Refrigerator Résumé : Lubricant oil return to compressor in household refrigerator is controlled by oil-refrigerant two-phase flow behavior in the suction pipe. Conditions of flooding and flow reversal were considered as a conservative bound for the oil return. Phenomena associated with counter current flow limitation (CCFL or flooding) and flow reversal were experimentally investigated using small diameter tubes with vertical, inclined and crank-type configurations. Flooding and flow reversal phenomena were visually observed. Both flooding and flow reversal points were measured using various shapes of test section in a wide range of liquid flow rate. The gas velocities for flooding were found to be inversely proportional to the liquid flow rates and independent of the tube configurations. The gas velocities for the flow reversal point appeared to be at a similar level over a certain range of liquid flow rate but strongly depend on the inclination angle, horizontal length and kind of liquid. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002247 [article] Experimental study on flooding and flow reversal in small diameter tubes with various inclinations and horizontal lengths = Etude expérimentale sur le noyage et l'inversion de l'écoulement dans des tubes de faible diamètre avec différentes inclinaisons et longueurs horizontales [texte imprimé] / Tiandong Guo, Auteur ; Ji Hwan Jeong, Auteur . - 2014 . - pp. 290–298. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 290–298 Mots-clés : Flooding;  Flow  reversal;  Counter-current  flow;  Suction  pipe;  Refrigerator Résumé : Lubricant oil return to compressor in household refrigerator is controlled by oil-refrigerant two-phase flow behavior in the suction pipe. Conditions of flooding and flow reversal were considered as a conservative bound for the oil return. Phenomena associated with counter current flow limitation (CCFL or flooding) and flow reversal were experimentally investigated using small diameter tubes with vertical, inclined and crank-type configurations. Flooding and flow reversal phenomena were visually observed. Both flooding and flow reversal points were measured using various shapes of test section in a wide range of liquid flow rate. The gas velocities for flooding were found to be inversely proportional to the liquid flow rates and independent of the tube configurations. The gas velocities for the flow reversal point appeared to be at a similar level over a certain range of liquid flow rate but strongly depend on the inclination angle, horizontal length and kind of liquid. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002247

Numerical simulation and experimental analysis of refrigerants flow through adiabatic helical capillary tube / Masoud Zareh in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 299–309 Titre : Numerical simulation and experimental analysis of refrigerants flow through adiabatic helical capillary tube Titre original : Simulation numérique et analyse expérimentale de l'écoulement de frigorigènes dans un tube capillaire hélicoïdal adiabatique Type de document : texte imprimé Auteurs : Masoud Zareh, Auteur ; Hossien Shokouhmand, Auteur ; Mohammad Reza Salimpour, Auteur Année de publication : 2014 Article en page(s) : pp. 299–309 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Refrigeration;  Drift  flux  model;  Adiabatic  helical  capillary  tube;  Experimental Résumé : In the present study, two-phase refrigerant flow is simulated using drift flux model for straight and helical capillary tubes. The conservation equations of mass, energy and momentum are solved using the 4th order Runge–Kutta method. This model is validated by previously published experimental and numerical results and also by experimental results presented in this work. The effect of various parameters such as inlet pressure, inlet temperature, sub-cooling degree, and geometric dimensions are studied. The results of the present study show that for the same length and under similar conditions, mass flux through helical capillary tube with coil diameter of 40 mm are about 11% less than that through the straight tube, where the helical tube length is about 14% shorter than the straight one for the same refrigerant mass flux. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002156 [article] Numerical simulation and experimental analysis of refrigerants flow through adiabatic helical capillary tube = Simulation numérique et analyse expérimentale de l'écoulement de frigorigènes dans un tube capillaire hélicoïdal adiabatique [texte imprimé] / Masoud Zareh, Auteur ; Hossien Shokouhmand, Auteur ; Mohammad Reza Salimpour, Auteur . - 2014 . - pp. 299–309. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 299–309 Mots-clés : Refrigeration;  Drift  flux  model;  Adiabatic  helical  capillary  tube;  Experimental Résumé : In the present study, two-phase refrigerant flow is simulated using drift flux model for straight and helical capillary tubes. The conservation equations of mass, energy and momentum are solved using the 4th order Runge–Kutta method. This model is validated by previously published experimental and numerical results and also by experimental results presented in this work. The effect of various parameters such as inlet pressure, inlet temperature, sub-cooling degree, and geometric dimensions are studied. The results of the present study show that for the same length and under similar conditions, mass flux through helical capillary tube with coil diameter of 40 mm are about 11% less than that through the straight tube, where the helical tube length is about 14% shorter than the straight one for the same refrigerant mass flux. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002156

Experimental investigation of a two-phase ejector cycle suitable for use with low-pressure refrigerants R134a and R1234yf / Neal, Lawrence in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 310–322 Titre : Experimental investigation of a two-phase ejector cycle suitable for use with low-pressure refrigerants R134a and R1234yf Titre original : Etude expérimentale d'un cycle d'éjection diphasique adapté pour une utilisation des frigorigènes à basse pression R134a et R1234yf Type de document : texte imprimé Auteurs : Neal, Lawrence, Auteur ; Stefan Elbel, Auteur Année de publication : 2014 Article en page(s) : pp. 310–322 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Ejector;  Expansion  work  recovery;  Cycle  comparison;  Coefficient  of  performance;  Evaporator  design Résumé : This paper presents the results of an experimental investigation in which the performance of the low-pressure fluids R134a and R1234yf was compared between a two-phase ejector cycle and expansion valve cycles. An alternate two-phase ejector cycle, in which the pressure lift provided by the ejector was utilized in order to provide multiple evaporation temperatures, was constructed and tested. The experimental results show that ejectors designed for low-pressure fluids were able to achieve similar but lower work recovery efficiencies compared to CO2 ejectors. When compared to a two evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 12% with R1234yf and 8% with R134a. When compared to a single evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 6% with R1234yf and 5% with R134a. The effect of evaporator design on ejector cycle COP improvement was also demonstrated experimentally. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002132 [article] Experimental investigation of a two-phase ejector cycle suitable for use with low-pressure refrigerants R134a and R1234yf = Etude expérimentale d'un cycle d'éjection diphasique adapté pour une utilisation des frigorigènes à basse pression R134a et R1234yf [texte imprimé] / Neal, Lawrence, Auteur ; Stefan Elbel, Auteur . - 2014 . - pp. 310–322. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 310–322 Mots-clés : Ejector;  Expansion  work  recovery;  Cycle  comparison;  Coefficient  of  performance;  Evaporator  design Résumé : This paper presents the results of an experimental investigation in which the performance of the low-pressure fluids R134a and R1234yf was compared between a two-phase ejector cycle and expansion valve cycles. An alternate two-phase ejector cycle, in which the pressure lift provided by the ejector was utilized in order to provide multiple evaporation temperatures, was constructed and tested. The experimental results show that ejectors designed for low-pressure fluids were able to achieve similar but lower work recovery efficiencies compared to CO2 ejectors. When compared to a two evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 12% with R1234yf and 8% with R134a. When compared to a single evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 6% with R1234yf and 5% with R134a. The effect of evaporator design on ejector cycle COP improvement was also demonstrated experimentally. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002132

Global modeling of heat and mass transfers in spiral tubular absorber of a water–lithium bromide absorption chiller / Nabil Ben Hafsia in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 323–332 Titre : Global modeling of heat and mass transfers in spiral tubular absorber of a water–lithium bromide absorption chiller Titre original : Modélisation globale des transferts de chaleur et de masse dans l'absorbeur tubulaire en spirale d'un refroidisseur à bromure de lithium-eau Type de document : texte imprimé Auteurs : Nabil Ben Hafsia, Auteur ; Chaouachi, Bechir, Auteur ; Gabsi, Slimane, Auteur Année de publication : 2014 Article en page(s) : pp. 323–332 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Absorption  chiller;  Linear  and  nonlinear  models;  Transfer  coefficients;  Coupled  transfer;  LMD  method Résumé : In this work, a simplified nonlinear coupled model and a simplified linear coupled model are examined in order to determine the model that better approaches the global mass and heat transfers during water vapor absorption by a falling film of LiBr solution in a spiral tubular absorber of an absorption chiller. The linear coupled model gives up analytical expressions that are used to determine overall heat and mass transfer coefficients from the experimental measurements taken at the inlet and outlet of absorber. These coupled overall transfer coefficients are used with the uncoupled ones that are deduced from the LMD method to determine the simulated absorption parameters along the absorber area. The comparison between the two models based essentially on the different parameters values at the inlet and the outlet of the absorber shows that nonlinear model approaches better experimental results. It shows also that the use of overall coupled transfer coefficients is not significant at low solution flow rates usually encountered in absorption chiller application and therefore the use of the overall transfer coefficients extracted from LMD method approaches well experimental data. The nonlinear model which is the approved model points up that the absorbed water vapor quantity and the overall effective mass transfer coefficient for the spiral tubular absorber increase with decreasing cooling water temperatures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002739 [article] Global modeling of heat and mass transfers in spiral tubular absorber of a water–lithium bromide absorption chiller = Modélisation globale des transferts de chaleur et de masse dans l'absorbeur tubulaire en spirale d'un refroidisseur à bromure de lithium-eau [texte imprimé] / Nabil Ben Hafsia, Auteur ; Chaouachi, Bechir, Auteur ; Gabsi, Slimane, Auteur . - 2014 . - pp. 323–332. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 323–332 Mots-clés : Absorption  chiller;  Linear  and  nonlinear  models;  Transfer  coefficients;  Coupled  transfer;  LMD  method Résumé : In this work, a simplified nonlinear coupled model and a simplified linear coupled model are examined in order to determine the model that better approaches the global mass and heat transfers during water vapor absorption by a falling film of LiBr solution in a spiral tubular absorber of an absorption chiller. The linear coupled model gives up analytical expressions that are used to determine overall heat and mass transfer coefficients from the experimental measurements taken at the inlet and outlet of absorber. These coupled overall transfer coefficients are used with the uncoupled ones that are deduced from the LMD method to determine the simulated absorption parameters along the absorber area. The comparison between the two models based essentially on the different parameters values at the inlet and the outlet of the absorber shows that nonlinear model approaches better experimental results. It shows also that the use of overall coupled transfer coefficients is not significant at low solution flow rates usually encountered in absorption chiller application and therefore the use of the overall transfer coefficients extracted from LMD method approaches well experimental data. The nonlinear model which is the approved model points up that the absorbed water vapor quantity and the overall effective mass transfer coefficient for the spiral tubular absorber increase with decreasing cooling water temperatures. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002739

Thermal conductivity of ammonia + lithium nitrate and ammonia + lithium nitrate + water solutions over a wide range of concentrations and temperatures / Yolanda Cuenca in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 333–340 Titre : Thermal conductivity of ammonia + lithium nitrate and ammonia + lithium nitrate + water solutions over a wide range of concentrations and temperatures Titre original : La conductivité thermique de solutions d'ammoniac/nitrate de lithium et d'ammoniac/nitrate de lithium/eau à une large gamme de concentrations et de températures Type de document : texte imprimé Auteurs : Yolanda Cuenca, Auteur ; Daniel Salavera, Auteur ; Anton Vernet, Auteur Année de publication : 2014 Article en page(s) : pp. 333–340 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Thermal  conductivity;  Ammonia  +  lithium  nitrate;  Transient  hot  wire  method;  Absorption  refrigeration Résumé : The thermal conductivity of NH3 + LiNO3 and NH3 + LiNO3 + H2O mixtures with an ammonia mass fraction between 0.3 and 0.6 was measured at temperatures from 303.15 K to 353.15 K at 1.5 MPa, using a relative transient hot wire apparatus. The apparatus and method were validated by comparing the measured values of the thermal conductivity of pure water, toluene, dimethyl phthalate, ethylene glycol and water + lithium nitrate with published values. Uncertainty in the measurements was estimated to be less than 0.025 W m−1 K−1. The measured NH3 + LiNO3 thermal conductivity was compared with the literature, showing significant differences. Finally, the experimental data was fitted with a comprehensive model based on the local composition concept. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002168 [article] Thermal conductivity of ammonia + lithium nitrate and ammonia + lithium nitrate + water solutions over a wide range of concentrations and temperatures = La conductivité thermique de solutions d'ammoniac/nitrate de lithium et d'ammoniac/nitrate de lithium/eau à une large gamme de concentrations et de températures [texte imprimé] / Yolanda Cuenca, Auteur ; Daniel Salavera, Auteur ; Anton Vernet, Auteur . - 2014 . - pp. 333–340. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 333–340 Mots-clés : Thermal  conductivity;  Ammonia  +  lithium  nitrate;  Transient  hot  wire  method;  Absorption  refrigeration Résumé : The thermal conductivity of NH3 + LiNO3 and NH3 + LiNO3 + H2O mixtures with an ammonia mass fraction between 0.3 and 0.6 was measured at temperatures from 303.15 K to 353.15 K at 1.5 MPa, using a relative transient hot wire apparatus. The apparatus and method were validated by comparing the measured values of the thermal conductivity of pure water, toluene, dimethyl phthalate, ethylene glycol and water + lithium nitrate with published values. Uncertainty in the measurements was estimated to be less than 0.025 W m−1 K−1. The measured NH3 + LiNO3 thermal conductivity was compared with the literature, showing significant differences. Finally, the experimental data was fitted with a comprehensive model based on the local composition concept. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002168

Study on measurement of frost dimensions/distribution and frost crystals scraping force using scanning probe microscope / Koji Matsumoto in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 341–351 Titre : Study on measurement of frost dimensions/distribution and frost crystals scraping force using scanning probe microscope : Investigation on influence of humidity Titre original : Etude de la mesure des dimensions et de la distribution des cristaux de givre et de la force de raclage utilisant un microscope à balayage (étude de l'influence de l'humidité) Type de document : texte imprimé Auteurs : Koji Matsumoto, Auteur ; Masato Honda, Auteur ; Yoma Ito, Auteur Année de publication : 2014 Article en page(s) : pp. 341–351 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Frost;  Adhesion;  Sublimation;  Humidity;  Structure Résumé : Frosting to a cooling solid surface is often unavoidable and is severe problems. Thus, in order to control the frosting, it is necessary to clarify the mechanism of frosting, both scientifically and technologically. Furthermore, when investigating this mechanism, knowing how frost crystals start to form and grow is very important, therefore, frosting from generation to primary growth stage must be clarified. Since frost crystals dimensions are very small in their generation and primary growth stage, it is essential to conduct these investigations at the micro scale level. In this study, using a scanning probe microscope (SPM), frost crystals dimensions/distribution and scraping force of frost crystals, were measured under fixed surface temperatures, comparing influence of humidity with that of surface temperature via a method proposed by one of the authors. Then, correlations among the above frost crystals dimensions/distribution and scraping force were clarified, comparing with influence of cooling solid surface temperature. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002375 [article] Study on measurement of frost dimensions/distribution and frost crystals scraping force using scanning probe microscope = Etude de la mesure des dimensions et de la distribution des cristaux de givre et de la force de raclage utilisant un microscope à balayage (étude de l'influence de l'humidité) : Investigation on influence of humidity [texte imprimé] / Koji Matsumoto, Auteur ; Masato Honda, Auteur ; Yoma Ito, Auteur . - 2014 . - pp. 341–351. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 341–351 Mots-clés : Frost;  Adhesion;  Sublimation;  Humidity;  Structure Résumé : Frosting to a cooling solid surface is often unavoidable and is severe problems. Thus, in order to control the frosting, it is necessary to clarify the mechanism of frosting, both scientifically and technologically. Furthermore, when investigating this mechanism, knowing how frost crystals start to form and grow is very important, therefore, frosting from generation to primary growth stage must be clarified. Since frost crystals dimensions are very small in their generation and primary growth stage, it is essential to conduct these investigations at the micro scale level. In this study, using a scanning probe microscope (SPM), frost crystals dimensions/distribution and scraping force of frost crystals, were measured under fixed surface temperatures, comparing influence of humidity with that of surface temperature via a method proposed by one of the authors. Then, correlations among the above frost crystals dimensions/distribution and scraping force were clarified, comparing with influence of cooling solid surface temperature. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002375

An analysis on a two-stage cascade thermoelectric cooler for electronics cooling applications / Ming Ma in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 352–357 Titre : An analysis on a two-stage cascade thermoelectric cooler for electronics cooling applications Titre original : Analyse d'un refroidisseur thermoélectrique biétagé en cascade pour des applications de refroidissement de l'électronique Type de document : texte imprimé Auteurs : Ming Ma, Auteur ; Jianlin Yu, Auteur Année de publication : 2014 Article en page(s) : pp. 352–357 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Thermoelectric  cooler;  Two-stage;  Analytical  model;  Electronics  cooling Résumé : This paper presents a comprehensive analysis of a novel two-stage cascade thermoelectric cooler (TTEC). The novel TTEC may be simply formed by joining short-legged thermoelectric couples in cascade, which has advantages of no interstage electrical insulating materials, compact and easy-fabricated structure, and using only one operating power. An analytical model taking into account the allocation of the total input current between the two stages of the TTEC is developed and the performance characteristics are investigated in detail. Especially, the allocation ratio of thermoelectric couple leg length which maximizes the TTEC COP at a specified condition are discussed. The analysis results indicate that such a cascade TTEC can greatly improve the operating temperature difference and be in theory more efficient than a single-stage thermoelectric cooler under most circumstances. It is also revealed that the allocation ratio of thermoelectric couple leg length plays an important role in determining TTEC thermal performance. Overall, the presented TTEC may show its promise in the future electronics cooling applications. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002259 [article] An analysis on a two-stage cascade thermoelectric cooler for electronics cooling applications = Analyse d'un refroidisseur thermoélectrique biétagé en cascade pour des applications de refroidissement de l'électronique [texte imprimé] / Ming Ma, Auteur ; Jianlin Yu, Auteur . - 2014 . - pp. 352–357. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 352–357 Mots-clés : Thermoelectric  cooler;  Two-stage;  Analytical  model;  Electronics  cooling Résumé : This paper presents a comprehensive analysis of a novel two-stage cascade thermoelectric cooler (TTEC). The novel TTEC may be simply formed by joining short-legged thermoelectric couples in cascade, which has advantages of no interstage electrical insulating materials, compact and easy-fabricated structure, and using only one operating power. An analytical model taking into account the allocation of the total input current between the two stages of the TTEC is developed and the performance characteristics are investigated in detail. Especially, the allocation ratio of thermoelectric couple leg length which maximizes the TTEC COP at a specified condition are discussed. The analysis results indicate that such a cascade TTEC can greatly improve the operating temperature difference and be in theory more efficient than a single-stage thermoelectric cooler under most circumstances. It is also revealed that the allocation ratio of thermoelectric couple leg length plays an important role in determining TTEC thermal performance. Overall, the presented TTEC may show its promise in the future electronics cooling applications. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002259

Function of gas parcels in the pulse tube / L. M. Qiu in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 358–366 Titre : Function of gas parcels in the pulse tube Titre original : Fonctions des groupes de gaz dans le tube à pulsation Type de document : texte imprimé Auteurs : L. M. Qiu, Auteur ; X. Q. Zhi, Auteur ; Z. H. Gan, Auteur Année de publication : 2014 Article en page(s) : pp. 358–366 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Pulse  tube  cryocooler;  Refrigeration  mechanism;  Phase  angle;  Thermodynamic  cycle Résumé : The working mechanisms of the pulse tube in a pulse tube cryocooler (PTC) were revealed by tracking the thermodynamic cycles of typical gas parcels quantitatively in Lagrangian viewpoint. The influence of the phase angle on the periodic work-heat conversion of the gas parcels was studied. Research shows that the cold end phase angle determines the heat “transfer” direction of the gas parcels in the pulse tube. For the phase-shifting PTCs, the gas parcels in the pulse tube expand while absorbing heat at the hot side and are compressed while releasing heat at the cold side in a cycle due to the effect of the phase shifter. The gas parcels in the pulse tube do not contribute cooling but bring heat losses to the cold end, which is different with the traditional understanding that the heat is taken away from the cold end by the gas in the pulse tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002491 [article] Function of gas parcels in the pulse tube = Fonctions des groupes de gaz dans le tube à pulsation [texte imprimé] / L. M. Qiu, Auteur ; X. Q. Zhi, Auteur ; Z. H. Gan, Auteur . - 2014 . - pp. 358–366. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 358–366 Mots-clés : Pulse  tube  cryocooler;  Refrigeration  mechanism;  Phase  angle;  Thermodynamic  cycle Résumé : The working mechanisms of the pulse tube in a pulse tube cryocooler (PTC) were revealed by tracking the thermodynamic cycles of typical gas parcels quantitatively in Lagrangian viewpoint. The influence of the phase angle on the periodic work-heat conversion of the gas parcels was studied. Research shows that the cold end phase angle determines the heat “transfer” direction of the gas parcels in the pulse tube. For the phase-shifting PTCs, the gas parcels in the pulse tube expand while absorbing heat at the hot side and are compressed while releasing heat at the cold side in a cycle due to the effect of the phase shifter. The gas parcels in the pulse tube do not contribute cooling but bring heat losses to the cold end, which is different with the traditional understanding that the heat is taken away from the cold end by the gas in the pulse tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002491

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