Dépouillements

Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part I - Experiments / Brian M. Fronk in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 7-16 Titre : Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part I - Experiments Titre original : Refroidisseur de gaz à microcanaux au dioxyde de carbone pour les pompes à chaleur utilisées pour chauffer de l'eau sanitaire. Partie I - Expériences Type de document : texte imprimé Auteurs : Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 7-16 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Heating  Hot  water  Carbon  dioxide  Transcritical  cycle  Experiment  Gas  cooler  Microchannel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of a compact, microchannel water- carbon dioxide (CO2) gas cooler was conducted. The gas cooler design under investigation used an array of serpentine refrigerant microchannel tubes wrapped around water passages containing offset strip fins, resulting in a generally counterflow configuration between the two fluids. Part I of this two-part paper addresses the experimental aspects. Data were obtained using an experimental heat pump facility at varying inlet conditions for three gas coolers of the same design, but different sizes. Measured heating capacity for the three gas coolers ranged from 1.5 to 6.5 kW. The results of this study are used in the companion paper (Part II) to develop a predictive heat exchanger model to optimize gas cooler design over a wide range of operating conditions, eliminating the need for expensive prototype development and testing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710000903 [article] Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part I - Experiments = Refroidisseur de gaz à microcanaux au dioxyde de carbone pour les pompes à chaleur utilisées pour chauffer de l'eau sanitaire. Partie I - Expériences [texte imprimé] / Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur . - 2011 . - pp. 7-16. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 7-16 Mots-clés : Heat  pump  Heating  Hot  water  Carbon  dioxide  Transcritical  cycle  Experiment  Gas  cooler  Microchannel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of a compact, microchannel water- carbon dioxide (CO2) gas cooler was conducted. The gas cooler design under investigation used an array of serpentine refrigerant microchannel tubes wrapped around water passages containing offset strip fins, resulting in a generally counterflow configuration between the two fluids. Part I of this two-part paper addresses the experimental aspects. Data were obtained using an experimental heat pump facility at varying inlet conditions for three gas coolers of the same design, but different sizes. Measured heating capacity for the three gas coolers ranged from 1.5 to 6.5 kW. The results of this study are used in the companion paper (Part II) to develop a predictive heat exchanger model to optimize gas cooler design over a wide range of operating conditions, eliminating the need for expensive prototype development and testing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710000903

Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part II – Model development and validation / Brian M. Fronk in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 17-28 Titre : Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part II – Model development and validation Titre original : Refroidisseur de gaz à microcanaux sur eau souterraine pour des pompes à chaleur au dioxyde de carbone utilisées pour chauffer de l'eau sanitaire. Partie II – Développement et validation du modèle Type de document : texte imprimé Auteurs : Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 17-28 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Gas  cooler  Carbon  dioxide  Transcritical  cycle  Microchannel  Heat  pump  Heating  Hot  water  Modelling  Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of a compact, microchannel water-carbon dioxide (CO2) gas cooler was conducted. The experimental results addressed in Part I of this study are used here in Part II to develop an analytical model, utilizing a segmented approach to account for the steep gradients in the thermodynamic and transport properties of supercritical CO2. The model predicted gas cooler heat duty with an average absolute deviation of 7.5% with varying refrigerant and water inlet conditions. The segmented model reveals that near the pseudo-critical point, there is a significant local decrease in refrigerant-side thermal resistance, which yields a sharp increase in local heat duty. The impact of this spike on gas cooler performance is analyzed. Results from this study can be used to predict the effect of changing geometric parameters of the heat exchanger without the need for expensive prototype development and testing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000109X [article] Water-coupled carbon dioxide microchannel gas cooler for heat pump water heaters. Part II – Model development and validation = Refroidisseur de gaz à microcanaux sur eau souterraine pour des pompes à chaleur au dioxyde de carbone utilisées pour chauffer de l'eau sanitaire. Partie II – Développement et validation du modèle [texte imprimé] / Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur . - 2011 . - pp. 17-28. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 17-28 Mots-clés : Heat  exchanger  Gas  cooler  Carbon  dioxide  Transcritical  cycle  Microchannel  Heat  pump  Heating  Hot  water  Modelling  Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of a compact, microchannel water-carbon dioxide (CO2) gas cooler was conducted. The experimental results addressed in Part I of this study are used here in Part II to develop an analytical model, utilizing a segmented approach to account for the steep gradients in the thermodynamic and transport properties of supercritical CO2. The model predicted gas cooler heat duty with an average absolute deviation of 7.5% with varying refrigerant and water inlet conditions. The segmented model reveals that near the pseudo-critical point, there is a significant local decrease in refrigerant-side thermal resistance, which yields a sharp increase in local heat duty. The impact of this spike on gas cooler performance is analyzed. Results from this study can be used to predict the effect of changing geometric parameters of the heat exchanger without the need for expensive prototype development and testing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000109X

Flow and convection heat transfer characteristics of CO2 mixed with lubricating oil at super-critical pressures in small tube during cooling / Chen-Ru Zhao in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 29-39 Titre : Flow and convection heat transfer characteristics of CO2 mixed with lubricating oil at super-critical pressures in small tube during cooling Titre original : Caractéristiques d'écoulement et de transfert de chaleur du CO2 mélangé avec de l'huile lubrifiante à des pressions surcritiques à l'intérieur de tubes de faible diamètre lors du refroidissement Type de document : texte imprimé Auteurs : Chen-Ru Zhao, Auteur ; Pei-Xue Jiang, Auteur ; You-Wei Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 29-39 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon  dioxide  Transcritical  cycle  Mixture  Polyolester  Heat  transfer  Flow  Pressure  drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes the heat transfer and the pressure drop characteristics of CO2 mixed with small amounts of compatible lubricating oil at super-critical pressures inside horizontal tubes with inner diameters of 1.98 mm and 4.14 mm during cooling. The heat transfer coefficients and pressure drops were measured. The results show that for the oil-free cases, the correlation proposed by Dang and Hihara accurately predicted the heat transfer coefficients and Petukhov’s correlation was found to predict the frictional pressure drops reasonably. Entrainment of the lubricating oil reduced the heat transfer coefficients and increased the pressure drops. Analysis showed that the heat transfer coefficients of the CO2/oil mixture are strongly related to the density and viscosity ratios of the oil to the CO2. An empirical correlation was developed based on the measured data, which predicts most of the experimental data within a deviation of 20%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000143X [article] Flow and convection heat transfer characteristics of CO2 mixed with lubricating oil at super-critical pressures in small tube during cooling = Caractéristiques d'écoulement et de transfert de chaleur du CO2 mélangé avec de l'huile lubrifiante à des pressions surcritiques à l'intérieur de tubes de faible diamètre lors du refroidissement [texte imprimé] / Chen-Ru Zhao, Auteur ; Pei-Xue Jiang, Auteur ; You-Wei Zhang, Auteur . - 2011 . - pp. 29-39. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 29-39 Mots-clés : Carbon  dioxide  Transcritical  cycle  Mixture  Polyolester  Heat  transfer  Flow  Pressure  drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes the heat transfer and the pressure drop characteristics of CO2 mixed with small amounts of compatible lubricating oil at super-critical pressures inside horizontal tubes with inner diameters of 1.98 mm and 4.14 mm during cooling. The heat transfer coefficients and pressure drops were measured. The results show that for the oil-free cases, the correlation proposed by Dang and Hihara accurately predicted the heat transfer coefficients and Petukhov’s correlation was found to predict the frictional pressure drops reasonably. Entrainment of the lubricating oil reduced the heat transfer coefficients and increased the pressure drops. Analysis showed that the heat transfer coefficients of the CO2/oil mixture are strongly related to the density and viscosity ratios of the oil to the CO2. An empirical correlation was developed based on the measured data, which predicts most of the experimental data within a deviation of 20%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000143X

Energetic evaluation of an internal heat exchanger in a CO2 transcritical refrigeration plant using experimental data / E. Torrella in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 40-49 Titre : Energetic evaluation of an internal heat exchanger in a CO2 transcritical refrigeration plant using experimental data Titre original : Evaluation énergétique de l’échangeur de chaleur interne d’une installation frigorifique transcritique au CO2 à l’aide de données expérimentales Type de document : texte imprimé Auteurs : E. Torrella, Auteur ; D. Sánchez, Auteur ; R. Llopis, Auteur Année de publication : 2011 Article en page(s) : pp. 40-49 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration  system  Carbon  dioxide  Transcritical  cycle  Internal  heat  exchanger  Calculation  Efficiency-superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of an Internal Heat Exchanger (IHX) operating in a CO2 transcritical refrigeration plant is analysed, from an energetic point of view, in this work. The evaluation is based on experimental data by contrasting the performance of the plant working with (44 tests) and without the IHX (46 tests) at the same operating conditions. The experimental evaluation covers three evaporating levels (−5, −10 and −15 °C), at two different gas-cooler outlet temperatures each (31, 34 °C), for a wide range of gas-cooler operating pressures (74.5–105.9 bar). The thermal effectiveness of the IHX is empirically analysed for the different operating conditions in the first part of the paper. Moreover, the relation of its effectiveness with the operating parameters is presented. The second part is devoted to analyse the modification of the energetic performance of the plant caused by the IHX. The results show a maximum increment on cooling capacity of 12%, an increment of the efficiency of the plant up to 12% and a maximum increase on discharge temperature of 10 °C at −15 °C of evaporating temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001520 [article] Energetic evaluation of an internal heat exchanger in a CO2 transcritical refrigeration plant using experimental data = Evaluation énergétique de l’échangeur de chaleur interne d’une installation frigorifique transcritique au CO2 à l’aide de données expérimentales [texte imprimé] / E. Torrella, Auteur ; D. Sánchez, Auteur ; R. Llopis, Auteur . - 2011 . - pp. 40-49. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 40-49 Mots-clés : Refrigeration  system  Carbon  dioxide  Transcritical  cycle  Internal  heat  exchanger  Calculation  Efficiency-superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of an Internal Heat Exchanger (IHX) operating in a CO2 transcritical refrigeration plant is analysed, from an energetic point of view, in this work. The evaluation is based on experimental data by contrasting the performance of the plant working with (44 tests) and without the IHX (46 tests) at the same operating conditions. The experimental evaluation covers three evaporating levels (−5, −10 and −15 °C), at two different gas-cooler outlet temperatures each (31, 34 °C), for a wide range of gas-cooler operating pressures (74.5–105.9 bar). The thermal effectiveness of the IHX is empirically analysed for the different operating conditions in the first part of the paper. Moreover, the relation of its effectiveness with the operating parameters is presented. The second part is devoted to analyse the modification of the energetic performance of the plant caused by the IHX. The results show a maximum increment on cooling capacity of 12%, an increment of the efficiency of the plant up to 12% and a maximum increase on discharge temperature of 10 °C at −15 °C of evaporating temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001520

Transcritical carbon dioxide small commercial cooling applications analysis / Luca Cecchinato in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 50-62 Titre : Transcritical carbon dioxide small commercial cooling applications analysis Titre original : Analyse du dioxyde de carbone transcritique dans les petites applications commerciales Type de document : texte imprimé Auteurs : Luca Cecchinato, Auteur ; Marco Corradi, Auteur Année de publication : 2011 Article en page(s) : pp. 50-62 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Capillary  Carbon  dioxide  Commercial  application  High  pressure  Optimisation  Transcritical  cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a project to develop an R744 commercial single door bottle cooler that is cost competitive and matches the performance of typical cost optimised R404A and R134a systems. Compressors with different displacement and efficiency values are evaluated for refrigerating systems with fin and tube and steel wire-on-tube gas coolers. Capillary tubes are tested. A methodology to properly sizing them and to optimize the combination of capillary tube and refrigerant charge is developed. The problem of optimal cycle high pressure is addressed and Liao’s approximated solution questioned. Tests demonstrate that the CO2 energy consumption systems are higher than traditional ones especially at ambient temperatures above 25 °C. Carbon dioxide appears to be a feasible option for stand-alone refrigerating equipment in terms of total equivalent warming impact (TEWI) compared to HFC refrigerants with actual single stage R744 compressor technology, only if the refrigeration units operate at medium–low gas cooler inlet temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002276 [article] Transcritical carbon dioxide small commercial cooling applications analysis = Analyse du dioxyde de carbone transcritique dans les petites applications commerciales [texte imprimé] / Luca Cecchinato, Auteur ; Marco Corradi, Auteur . - 2011 . - pp. 50-62. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 50-62 Mots-clés : Capillary  Carbon  dioxide  Commercial  application  High  pressure  Optimisation  Transcritical  cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a project to develop an R744 commercial single door bottle cooler that is cost competitive and matches the performance of typical cost optimised R404A and R134a systems. Compressors with different displacement and efficiency values are evaluated for refrigerating systems with fin and tube and steel wire-on-tube gas coolers. Capillary tubes are tested. A methodology to properly sizing them and to optimize the combination of capillary tube and refrigerant charge is developed. The problem of optimal cycle high pressure is addressed and Liao’s approximated solution questioned. Tests demonstrate that the CO2 energy consumption systems are higher than traditional ones especially at ambient temperatures above 25 °C. Carbon dioxide appears to be a feasible option for stand-alone refrigerating equipment in terms of total equivalent warming impact (TEWI) compared to HFC refrigerants with actual single stage R744 compressor technology, only if the refrigeration units operate at medium–low gas cooler inlet temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002276

A comprehensive model of a miniature-scale linear compressor for electronics cooling / Craig R. Bradshaw in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 63-73 Titre : A comprehensive model of a miniature-scale linear compressor for electronics cooling Titre original : Modèle extensif d'un compresseur linéaire miniaturisé utilisé pour refroidir les composants des systèmes électroniques Type de document : texte imprimé Auteurs : Craig R. Bradshaw, Auteur ; Eckhard A. Groll, Auteur ; Suresh V. Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 63-73 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Linear  compressor  Compressor  model  Electronic  components  Cooling  Miniature-compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A comprehensive model of a miniature-scale linear compressor for electronics cooling is presented. Linear compressors are appealing for refrigeration applications in electronics cooling. A small number of moving components translate to less theoretical frictional losses and the possibility that this technology could scale to smaller physical sizes better than conventional compressors. The model developed here incorporates all of the major components of the linear compressor including dynamics associated with the piston motion. The results of the compressor model were validated using experimental data from a prototype linear compressor. The prototype compressor has an overall displacement of approximately 3 cm3, an average stroke of 0.6 cm. The prototype compressor was custom built for this work and utilizes custom parts with the exception of the mechanical springs and the linear motor. The model results showed good agreement when validated against the experimental results. The piston stroke is predicted within 1.3% MAE. The volumetric and overall isentropic efficiencies are predicted within 24% and 31%, MAE respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002240 [article] A comprehensive model of a miniature-scale linear compressor for electronics cooling = Modèle extensif d'un compresseur linéaire miniaturisé utilisé pour refroidir les composants des systèmes électroniques [texte imprimé] / Craig R. Bradshaw, Auteur ; Eckhard A. Groll, Auteur ; Suresh V. Garimella, Auteur . - 2011 . - pp. 63-73. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 63-73 Mots-clés : Linear  compressor  Compressor  model  Electronic  components  Cooling  Miniature-compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A comprehensive model of a miniature-scale linear compressor for electronics cooling is presented. Linear compressors are appealing for refrigeration applications in electronics cooling. A small number of moving components translate to less theoretical frictional losses and the possibility that this technology could scale to smaller physical sizes better than conventional compressors. The model developed here incorporates all of the major components of the linear compressor including dynamics associated with the piston motion. The results of the compressor model were validated using experimental data from a prototype linear compressor. The prototype compressor has an overall displacement of approximately 3 cm3, an average stroke of 0.6 cm. The prototype compressor was custom built for this work and utilizes custom parts with the exception of the mechanical springs and the linear motor. The model results showed good agreement when validated against the experimental results. The piston stroke is predicted within 1.3% MAE. The volumetric and overall isentropic efficiencies are predicted within 24% and 31%, MAE respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002240

Fluid flow in a screw pump oil supply system for reciprocating compressors / Marcus V. C. Alves in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 74-83 Titre : Fluid flow in a screw pump oil supply system for reciprocating compressors Titre original : Ecoulement du fluide dans le système d'alimentation en huile des pompes à vis de compresseurs à piston Type de document : texte imprimé Auteurs : Marcus V. C. Alves, Auteur ; Jader R. Barbosa Jr., Auteur ; Alvaro T. Prata, Auteur Année de publication : 2011 Article en page(s) : pp. 74-83 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Reciprocating  compressor  Lubricant  Oil  Pump  Screw-design  Modelling-optimisation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This work presents a mathematical analysis of an oil supply system for reciprocating compressors. The system is based on a single screw pump attached to the bottom end of the vertical rotating shaft immersed in the oil sump. The fluid flow in the pump was modeled with a semi-analytical approach based on the solution for the laminar fully developed oil flow in a screw extruder via the Generalized Integral Transform Technique. The screw pump model is coupled with that for the flow in the shaft region so as to provide an estimate of the oil flow rate and of the so-called ‘climbing-time’, i.e., the amount of time needed for a fluid particle to travel from the oil sump to the top of the shaft. The calculation method was verified against experimental data and Computational Fluid Dynamics modeling results. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001751 [article] Fluid flow in a screw pump oil supply system for reciprocating compressors = Ecoulement du fluide dans le système d'alimentation en huile des pompes à vis de compresseurs à piston [texte imprimé] / Marcus V. C. Alves, Auteur ; Jader R. Barbosa Jr., Auteur ; Alvaro T. Prata, Auteur . - 2011 . - pp. 74-83. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 74-83 Mots-clés : Reciprocating  compressor  Lubricant  Oil  Pump  Screw-design  Modelling-optimisation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This work presents a mathematical analysis of an oil supply system for reciprocating compressors. The system is based on a single screw pump attached to the bottom end of the vertical rotating shaft immersed in the oil sump. The fluid flow in the pump was modeled with a semi-analytical approach based on the solution for the laminar fully developed oil flow in a screw extruder via the Generalized Integral Transform Technique. The screw pump model is coupled with that for the flow in the shaft region so as to provide an estimate of the oil flow rate and of the so-called ‘climbing-time’, i.e., the amount of time needed for a fluid particle to travel from the oil sump to the top of the shaft. The calculation method was verified against experimental data and Computational Fluid Dynamics modeling results. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001751

Study on leakage via the radial clearance in a novel synchronal rotary refrigeration compressor / Hua Yang in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 84-93 Titre : Study on leakage via the radial clearance in a novel synchronal rotary refrigeration compressor Titre original : Etude sur les fuites à travers l'espace mort dans un nouveau compresseur frigorifique rotatif synchrone Type de document : texte imprimé Auteurs : Hua Yang, Auteur ; Qu, Zongchang, Auteur ; Hui Zhou, Auteur Année de publication : 2011 Article en page(s) : pp. 84-93 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Leakage  Rotary  compressor  Loss  Refrigeration  system  Compressor  Rolling  piston Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The leakage flow characteristics at the radial clearance between the rotor and the cylinder in a novel synchronal rotary (SR) refrigeration compressor were analyzed, and the oil–refrigerant two-phase leakage flow model was established. The leakage at different temperatures caused by wall velocity and pressure difference was calculated, and their influences on the total leakage were analyzed, respectively. The calculation results indicate that the leakage of the oil–refrigerant mixture decreases firstly and then increases with the increase in the temperature. However, the refrigerant leakage always decreases when the temperature increases. Moreover, the leakage caused by wall velocity has great influence on the total leakage, especially when the radial clearance is small. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001799 [article] Study on leakage via the radial clearance in a novel synchronal rotary refrigeration compressor = Etude sur les fuites à travers l'espace mort dans un nouveau compresseur frigorifique rotatif synchrone [texte imprimé] / Hua Yang, Auteur ; Qu, Zongchang, Auteur ; Hui Zhou, Auteur . - 2011 . - pp. 84-93. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 84-93 Mots-clés : Leakage  Rotary  compressor  Loss  Refrigeration  system  Compressor  Rolling  piston Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The leakage flow characteristics at the radial clearance between the rotor and the cylinder in a novel synchronal rotary (SR) refrigeration compressor were analyzed, and the oil–refrigerant two-phase leakage flow model was established. The leakage at different temperatures caused by wall velocity and pressure difference was calculated, and their influences on the total leakage were analyzed, respectively. The calculation results indicate that the leakage of the oil–refrigerant mixture decreases firstly and then increases with the increase in the temperature. However, the refrigerant leakage always decreases when the temperature increases. Moreover, the leakage caused by wall velocity has great influence on the total leakage, especially when the radial clearance is small. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001799

Journal bearings design for a novel revolving vane compressor / K.M. Tan in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 94-104 Titre : Journal bearings design for a novel revolving vane compressor Titre original : Conception des paliers lisses pour un nouveau compresseur à palettes rotatives Type de document : texte imprimé Auteurs : K.M. Tan, Auteur ; K.T. Ooi, Auteur Année de publication : 2011 Article en page(s) : pp. 94-104 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  conditioning  Bearing  Design  Compressor  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the theoretical details of the journal bearing design for Revolving Vane (RV) rotary type compressor. The mathematical models, force analysis, and the theoretical design analysis for the dynamically loaded journal bearing of the compressor are presented. The variations of the minimum oil film thickness and the maximum film pressure developed are shown and the influences of design parameters, compressor configurations, and operating conditions on the journal bearing performance are described. For an air-conditioning compressor of 1.5 kW cooling capacity, the lowest minimum oil film thickness for lower and upper journal bearings is 6.6 μm and 4.3 μm respectively, when the cylinder is simply supported and the rotor is cantilever-supported. The lowest minimum oil film thickness for the journal bearing, which supports the cylinder, reduces to 4.0 μm if the cantilever-type support is used. Besides that, a short-fat configuration of RV compressor is favorable in the interest of lowering bearing forces. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001842 [article] Journal bearings design for a novel revolving vane compressor = Conception des paliers lisses pour un nouveau compresseur à palettes rotatives [texte imprimé] / K.M. Tan, Auteur ; K.T. Ooi, Auteur . - 2011 . - pp. 94-104. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 94-104 Mots-clés : Air  conditioning  Bearing  Design  Compressor  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the theoretical details of the journal bearing design for Revolving Vane (RV) rotary type compressor. The mathematical models, force analysis, and the theoretical design analysis for the dynamically loaded journal bearing of the compressor are presented. The variations of the minimum oil film thickness and the maximum film pressure developed are shown and the influences of design parameters, compressor configurations, and operating conditions on the journal bearing performance are described. For an air-conditioning compressor of 1.5 kW cooling capacity, the lowest minimum oil film thickness for lower and upper journal bearings is 6.6 μm and 4.3 μm respectively, when the cylinder is simply supported and the rotor is cantilever-supported. The lowest minimum oil film thickness for the journal bearing, which supports the cylinder, reduces to 4.0 μm if the cantilever-type support is used. Besides that, a short-fat configuration of RV compressor is favorable in the interest of lowering bearing forces. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001842

An experimental study on oil discharge ratio at inverter-driven high shell pressure scroll compressor using R410A/PVE / Pilhyun Yoon in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 105-112 Titre : An experimental study on oil discharge ratio at inverter-driven high shell pressure scroll compressor using R410A/PVE Titre original : Etude expérimentale sur le taux d'huile au refoulement d'un compresseur à spirale à pression élevée dans l'enveloppe entraîné par des variateurs de fréquence utilisant le R410A et l'huile polyvinyléther (PVE) Type de document : texte imprimé Auteurs : Pilhyun Yoon, Auteur ; Donghoon Kang, Auteur ; Cholhwan Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 105-112 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Scroll  compressor  R410A  Oil  Discharge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, the oil discharge characteristics of a high shell pressure scroll compressor, which uses R410A as the refrigerant and PVE as the oil, were measured according to the conditions for oil management. The measurement of oil discharge ratio (ODR) in the system is very important to secure the operational reliability. It was made in real time through the refractive index sensor. ODR was greatly influenced by the mass flow rate and the dynamic viscosity of the refrigerant. As the rotation frequency of the compressor became higher, ODR increased rapidly. ODR at 120 Hz was 4.22 times higher than that at 60 Hz. At the same rotation frequency of the compressor, the increase of the suction pressure also played a role in increasing the ODR. In addition, in the zone where the ODR increased rapidly, the compressing efficiency of the compressor decreased significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002045 [article] An experimental study on oil discharge ratio at inverter-driven high shell pressure scroll compressor using R410A/PVE = Etude expérimentale sur le taux d'huile au refoulement d'un compresseur à spirale à pression élevée dans l'enveloppe entraîné par des variateurs de fréquence utilisant le R410A et l'huile polyvinyléther (PVE) [texte imprimé] / Pilhyun Yoon, Auteur ; Donghoon Kang, Auteur ; Cholhwan Kim, Auteur . - 2011 . - pp. 105-112. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 105-112 Mots-clés : Scroll  compressor  R410A  Oil  Discharge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, the oil discharge characteristics of a high shell pressure scroll compressor, which uses R410A as the refrigerant and PVE as the oil, were measured according to the conditions for oil management. The measurement of oil discharge ratio (ODR) in the system is very important to secure the operational reliability. It was made in real time through the refractive index sensor. ODR was greatly influenced by the mass flow rate and the dynamic viscosity of the refrigerant. As the rotation frequency of the compressor became higher, ODR increased rapidly. ODR at 120 Hz was 4.22 times higher than that at 60 Hz. At the same rotation frequency of the compressor, the increase of the suction pressure also played a role in increasing the ODR. In addition, in the zone where the ODR increased rapidly, the compressing efficiency of the compressor decreased significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002045

Heat and mass transfer characteristics of a constrained thin-film ammonia–water bubble absorber / Ruander Cardenas in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 113-128 Titre : Heat and mass transfer characteristics of a constrained thin-film ammonia–water bubble absorber Titre original : Absorbeur à bulles à ammoniac-eau aux pellicules minces limitées: caractéristiques du transfert de chaleur et de masse Type de document : texte imprimé Auteurs : Ruander Cardenas, Auteur ; Vinod Narayanan, Auteur Année de publication : 2011 Article en page(s) : pp. 113-128 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorber  Microchannel  Bubble  Ammonia–water Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A study of absorption of ammonia vapour bubbles into a constrained thin-film of ammonia–water solution is presented. A large-aspect-ratio microchannel constrains the thickness of the weak solution film and ammonia vapour bubbles are injected from a porous wall. A counter flowing coolant in a minichannel removes the generated heat of absorption. Experiments and a simple one-dimensional numerical model are used to characterize the absorber performance at a nominal system pressure of 6.2 bar absolute. Effect of varying the mass flow rate of the weak solution, vapour flow rate, solution inlet temperature, and coolant inlet temperature on absorption heat and mass transfer rates and exit subcooling are discussed. Two absorber channel geometries, each of 600 μm nominal depth, are considered: 1) a smooth-wall channel, and 2) a stepped-wall channel that has 2-mm deep trenches across the width of a channel wall. Results indicate that the reduction in coolant inlet temperature significantly enhances the mass transfer rates in both absorber geometries. While the stepped-wall geometry exhibits higher mass transfer rates at lower coolant inlet temperatures of 30 °C and 40 °C, the smooth-wall channel shows higher mass transfer rates at the highest coolant inlet temperature of 58 °C. Both absorption limited and residence time limited conditions are observed with variation of weak solution flow rate at fixed vapour flow rates. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001829 [article] Heat and mass transfer characteristics of a constrained thin-film ammonia–water bubble absorber = Absorbeur à bulles à ammoniac-eau aux pellicules minces limitées: caractéristiques du transfert de chaleur et de masse [texte imprimé] / Ruander Cardenas, Auteur ; Vinod Narayanan, Auteur . - 2011 . - pp. 113-128. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 113-128 Mots-clés : Absorber  Microchannel  Bubble  Ammonia–water Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A study of absorption of ammonia vapour bubbles into a constrained thin-film of ammonia–water solution is presented. A large-aspect-ratio microchannel constrains the thickness of the weak solution film and ammonia vapour bubbles are injected from a porous wall. A counter flowing coolant in a minichannel removes the generated heat of absorption. Experiments and a simple one-dimensional numerical model are used to characterize the absorber performance at a nominal system pressure of 6.2 bar absolute. Effect of varying the mass flow rate of the weak solution, vapour flow rate, solution inlet temperature, and coolant inlet temperature on absorption heat and mass transfer rates and exit subcooling are discussed. Two absorber channel geometries, each of 600 μm nominal depth, are considered: 1) a smooth-wall channel, and 2) a stepped-wall channel that has 2-mm deep trenches across the width of a channel wall. Results indicate that the reduction in coolant inlet temperature significantly enhances the mass transfer rates in both absorber geometries. While the stepped-wall geometry exhibits higher mass transfer rates at lower coolant inlet temperatures of 30 °C and 40 °C, the smooth-wall channel shows higher mass transfer rates at the highest coolant inlet temperature of 58 °C. Both absorption limited and residence time limited conditions are observed with variation of weak solution flow rate at fixed vapour flow rates. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001829

Performance evaluation of combined adsorption refrigeration cycles / Khairul Habib in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 129-137 Titre : Performance evaluation of combined adsorption refrigeration cycles Titre original : Evaluation de la performance des cycles frigorifiques combinés à adsorption Type de document : texte imprimé Auteurs : Khairul Habib, Auteur ; Bidyut Baran Saha, Auteur ; Anutosh Chakraborty, Auteur Année de publication : 2011 Article en page(s) : pp. 129-137 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption  Cooling  R134a  R507  Activated  carbon-cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of an investigation on the performance of combined adsorption refrigeration cycles. The novel combined cycle amalgamates the activated carbon (AC)-R507A as the bottoming cycle and AC-R134a cycle as the topping cycle and deliver refrigeration load at as low as −10 °C at the bottoming cycle. The cycle simulation is based on the experimentally confirmed adsorption isotherms, kinetics and isosteric heat of adsorption data for R134a and R507A on highly porous based activated carbon of type Maxsorb III. The optimum cooling capacity, coefficient of performance (COP) and chiller efficiency are calculated in terms of cycle time, switching time, regeneration and brine inlet temperatures. Results show that the combined adsorption cycles are feasible even when low-temperature heat source is available. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002100 [article] Performance evaluation of combined adsorption refrigeration cycles = Evaluation de la performance des cycles frigorifiques combinés à adsorption [texte imprimé] / Khairul Habib, Auteur ; Bidyut Baran Saha, Auteur ; Anutosh Chakraborty, Auteur . - 2011 . - pp. 129-137. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 129-137 Mots-clés : Adsorption  Cooling  R134a  R507  Activated  carbon-cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of an investigation on the performance of combined adsorption refrigeration cycles. The novel combined cycle amalgamates the activated carbon (AC)-R507A as the bottoming cycle and AC-R134a cycle as the topping cycle and deliver refrigeration load at as low as −10 °C at the bottoming cycle. The cycle simulation is based on the experimentally confirmed adsorption isotherms, kinetics and isosteric heat of adsorption data for R134a and R507A on highly porous based activated carbon of type Maxsorb III. The optimum cooling capacity, coefficient of performance (COP) and chiller efficiency are calculated in terms of cycle time, switching time, regeneration and brine inlet temperatures. Results show that the combined adsorption cycles are feasible even when low-temperature heat source is available. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002100

Performance of an adiabatic cross-flow liquid-desiccant absorber inside a refrigerated warehouse / Sergio M. Pineda in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 138-147 Titre : Performance of an adiabatic cross-flow liquid-desiccant absorber inside a refrigerated warehouse Titre original : Performance d'un absorbeur à déshydratant liquide à écoulements croisés adiabatiques dans un entrepôt frigorifique Type de document : texte imprimé Auteurs : Sergio M. Pineda, Auteur ; Gerardo Diaz, Auteur Année de publication : 2011 Article en page(s) : pp. 138-147 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cold  storage  Desiccant  Defrosting  Energy  consumption  Reduction  Moisture Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Liquid-desiccant systems have been extensively studied as a way of reducing the latent load on air conditioning systems. Most of the studies have targeted the removal of moisture from air at ambient conditions. The literature about the use of liquid desiccants in low temperature applications is scarce. In this study, a small-scale liquid-desiccant absorber is installed inside a commercial refrigerated warehouse. Its performance under realistic operating conditions inside a pre-cooling room is analyzed. The results show that the dew point temperature of the air downstream of the absorber is comparable to the evaporator surface temperature suggesting the potential to delay the formation of ice on the cooling coil. An internal heat exchanger is used to lower the temperature of the inlet liquid-desiccant flow to the absorber and the regeneration process is performed using only ambient air. The analysis of the reduction in water and energy consumption for a scaled-up system is also performed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001775 [article] Performance of an adiabatic cross-flow liquid-desiccant absorber inside a refrigerated warehouse = Performance d'un absorbeur à déshydratant liquide à écoulements croisés adiabatiques dans un entrepôt frigorifique [texte imprimé] / Sergio M. Pineda, Auteur ; Gerardo Diaz, Auteur . - 2011 . - pp. 138-147. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 138-147 Mots-clés : Cold  storage  Desiccant  Defrosting  Energy  consumption  Reduction  Moisture Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Liquid-desiccant systems have been extensively studied as a way of reducing the latent load on air conditioning systems. Most of the studies have targeted the removal of moisture from air at ambient conditions. The literature about the use of liquid desiccants in low temperature applications is scarce. In this study, a small-scale liquid-desiccant absorber is installed inside a commercial refrigerated warehouse. Its performance under realistic operating conditions inside a pre-cooling room is analyzed. The results show that the dew point temperature of the air downstream of the absorber is comparable to the evaporator surface temperature suggesting the potential to delay the formation of ice on the cooling coil. An internal heat exchanger is used to lower the temperature of the inlet liquid-desiccant flow to the absorber and the regeneration process is performed using only ambient air. The analysis of the reduction in water and energy consumption for a scaled-up system is also performed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001775

Optimisation of a desiccant cooling system design with indirect evaporative cooler / M. Goldsworthy in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 148-158 Titre : Optimisation of a desiccant cooling system design with indirect evaporative cooler Titre original : Optimisation de la conception d'un système de refroidissement à déshydratant à refroidissement évaporatif indirect Type de document : texte imprimé Auteurs : M. Goldsworthy, Auteur ; S. White, Auteur Année de publication : 2011 Article en page(s) : pp. 148-158 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air-conditioning  Desiccant  system  Desiccant  wheel  Optimisation  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Solar desiccant-based air-conditioning has the potential to significantly reduce cost and/or greenhouse gas emissions associated with cooling of buildings. Parasitic energy consumption for the operation of supply fans has been identified as a major hindrance to achieving these savings. The cooling performance is governed by the trade-off between supplying larger flow-rates of cool air or lower flow-rates of cold air. The performance of a combined solid desiccant-indirect evaporative cooler system is analysed by solving the heat and mass transfer equations for both components simultaneously. Focus is placed on varying the desiccant wheel supply/regeneration and indirect cooler secondary/primary air-flow ratios. Results show that for an ambient reference condition, and 70 °C regeneration temperature, a supply/regeneration flow ratio of 0.67 and an indirect cooler secondary/primary flow ratio of 0.3 gives the best performance with COPe > 20. The proposed cooling system thus has potential to achieve substantial energy and greenhouse gas emission savings. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001519 [article] Optimisation of a desiccant cooling system design with indirect evaporative cooler = Optimisation de la conception d'un système de refroidissement à déshydratant à refroidissement évaporatif indirect [texte imprimé] / M. Goldsworthy, Auteur ; S. White, Auteur . - 2011 . - pp. 148-158. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 148-158 Mots-clés : Air-conditioning  Desiccant  system  Desiccant  wheel  Optimisation  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Solar desiccant-based air-conditioning has the potential to significantly reduce cost and/or greenhouse gas emissions associated with cooling of buildings. Parasitic energy consumption for the operation of supply fans has been identified as a major hindrance to achieving these savings. The cooling performance is governed by the trade-off between supplying larger flow-rates of cool air or lower flow-rates of cold air. The performance of a combined solid desiccant-indirect evaporative cooler system is analysed by solving the heat and mass transfer equations for both components simultaneously. Focus is placed on varying the desiccant wheel supply/regeneration and indirect cooler secondary/primary air-flow ratios. Results show that for an ambient reference condition, and 70 °C regeneration temperature, a supply/regeneration flow ratio of 0.67 and an indirect cooler secondary/primary flow ratio of 0.3 gives the best performance with COPe > 20. The proposed cooling system thus has potential to achieve substantial energy and greenhouse gas emission savings. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001519

Modélisation de la phase génération d’un cycle de réfrigération par absorption solaire à fonctionnement intermittent / Yasmina Boukhchana in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 159-167 Titre : Modélisation de la phase génération d’un cycle de réfrigération par absorption solaire à fonctionnement intermittent Titre original : Modelling of the generation phase of an absorption cooling cycle operating intermittently Type de document : texte imprimé Auteurs : Yasmina Boukhchana, Auteur ; Ali Fellah, Auteur ; Ammar Ben Brahim, Auteur Année de publication : 2011 Article en page(s) : pp. 159-167 Note générale : Génie Mécanique Langues : Français (fre) Mots-clés : Réfrigération  Absorption  Énergie  solaire  Intermittence  Simulation  Régime  dynamique  Ammoniac Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : La modélisation en régime dynamique de la phase génération d’une installation frigorifique à absorption solaire à fonctionnement intermittent utilisant le couple ammoniac/eau a été élaborée. L’étude basée sur l’intermittence du fonctionnement a permis d’élaborer, à travers les bilans matières et thermiques, un modèle thermodynamique reliant les températures, les débits et les fractions massiques dans les différents compartiments. Des journées ensoleillées représentatives des quatre saisons de l’année ont été considérées. Les variations du taux d’ensoleillement, des températures et des concentrations ont été explorées. Les résultats ont montré, moyennant les hypothèses adoptées en particulier à pression de fonctionnement constante, que la démarche proposée a permis d’avoir une température de génération autour de 135 °C et une température de condensation de 60 °C. Ces températures sont atteinte par l’adaptation de la convection naturelle à l’air pour le fonctionnement du condenseur. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000174X [article] Modélisation de la phase génération d’un cycle de réfrigération par absorption solaire à fonctionnement intermittent = Modelling of the generation phase of an absorption cooling cycle operating intermittently [texte imprimé] / Yasmina Boukhchana, Auteur ; Ali Fellah, Auteur ; Ammar Ben Brahim, Auteur . - 2011 . - pp. 159-167. Génie Mécanique Langues : Français (fre) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 159-167 Mots-clés : Réfrigération  Absorption  Énergie  solaire  Intermittence  Simulation  Régime  dynamique  Ammoniac Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : La modélisation en régime dynamique de la phase génération d’une installation frigorifique à absorption solaire à fonctionnement intermittent utilisant le couple ammoniac/eau a été élaborée. L’étude basée sur l’intermittence du fonctionnement a permis d’élaborer, à travers les bilans matières et thermiques, un modèle thermodynamique reliant les températures, les débits et les fractions massiques dans les différents compartiments. Des journées ensoleillées représentatives des quatre saisons de l’année ont été considérées. Les variations du taux d’ensoleillement, des températures et des concentrations ont été explorées. Les résultats ont montré, moyennant les hypothèses adoptées en particulier à pression de fonctionnement constante, que la démarche proposée a permis d’avoir une température de génération autour de 135 °C et une température de condensation de 60 °C. Ces températures sont atteinte par l’adaptation de la convection naturelle à l’air pour le fonctionnement du condenseur. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000174X

Configuration and performance analysis of magnetic refrigerators / A. Rowe in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 168-177 Titre : Configuration and performance analysis of magnetic refrigerators Titre original : Configuration et analyse de la performance des réfrigérateurs magnétiques Type de document : texte imprimé Auteurs : A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 168-177 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Exergy  Performance  Gadolinium  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The commercialization of magnetic refrigerators depends upon the ability to meet performance targets while having acceptable equipment costs. This paper links device design parameters and performance of magnetic refrigerators to the cost of cooling delivered. A device configuration parameter, D, is defined that links the field volume to the volume of magnetocaloric material. Combined with the magnet performance parameter, efficiency, and specific exergetic cooling, the cost structure of a magnetic refrigerator is determined. Some magnetic refrigerators reported in the literature are classified using their configuration parameters, and are then compared in terms of demonstrated performance using results available in the literature. The required improvement in performance is calculated such that the cost of a magnetic refrigerator would be equivalent to a conventional compressor-based device. Finally, some of the reasons for different performance are discussed with a focus on opportunities for improvements. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001957 [article] Configuration and performance analysis of magnetic refrigerators = Configuration et analyse de la performance des réfrigérateurs magnétiques [texte imprimé] / A. Rowe, Auteur . - 2011 . - pp. 168-177. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 168-177 Mots-clés : Magnetic  refrigerator  Exergy  Performance  Gadolinium  Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The commercialization of magnetic refrigerators depends upon the ability to meet performance targets while having acceptable equipment costs. This paper links device design parameters and performance of magnetic refrigerators to the cost of cooling delivered. A device configuration parameter, D, is defined that links the field volume to the volume of magnetocaloric material. Combined with the magnet performance parameter, efficiency, and specific exergetic cooling, the cost structure of a magnetic refrigerator is determined. Some magnetic refrigerators reported in the literature are classified using their configuration parameters, and are then compared in terms of demonstrated performance using results available in the literature. The required improvement in performance is calculated such that the cost of a magnetic refrigerator would be equivalent to a conventional compressor-based device. Finally, some of the reasons for different performance are discussed with a focus on opportunities for improvements. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001957

Experimental analysis of a two-material active magnetic regenerator / D.S. Arnold in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 178-191 Titre : Experimental analysis of a two-material active magnetic regenerator Titre original : Analyse expérimentale d'un régénérateur magnétique actif faisant appel à deux matériaux Type de document : texte imprimé Auteurs : D.S. Arnold, Auteur ; A. Tura, Auteur ; A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 178-191 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigeration  COP-exergy  Performance  Gadolinium-cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental results of an active magnetic regenerator (AMR) composed of two equal volumes of gadolinium and Gd0.85Er0.15 using 2 T and 5 T are reported. Drive forces and system losses are measured as a function of thermal load and magnetic field. Metrics for coefficient of performance and efficiency are defined and used to distinguish between regenerator and device performance. Results suggest the largest temperature spans are expected to occur when each material is operating with its average temperature near their Curie temperatures. Force measurements indicate that mechanical losses and pumping power are the most significant contributions to network while the net magnetic work is too small to be resolved. COP values for the magnetic cycle are as high as 2.4 while efficiencies are all less than 0.15. A maximum exergetic cooling of 1.94 W is estimated with a corresponding specific exergetic cooling power of 23 W T−1L−1. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002008 [article] Experimental analysis of a two-material active magnetic regenerator = Analyse expérimentale d'un régénérateur magnétique actif faisant appel à deux matériaux [texte imprimé] / D.S. Arnold, Auteur ; A. Tura, Auteur ; A. Rowe, Auteur . - 2011 . - pp. 178-191. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 178-191 Mots-clés : Magnetic  refrigeration  COP-exergy  Performance  Gadolinium-cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental results of an active magnetic regenerator (AMR) composed of two equal volumes of gadolinium and Gd0.85Er0.15 using 2 T and 5 T are reported. Drive forces and system losses are measured as a function of thermal load and magnetic field. Metrics for coefficient of performance and efficiency are defined and used to distinguish between regenerator and device performance. Results suggest the largest temperature spans are expected to occur when each material is operating with its average temperature near their Curie temperatures. Force measurements indicate that mechanical losses and pumping power are the most significant contributions to network while the net magnetic work is too small to be resolved. COP values for the magnetic cycle are as high as 2.4 while efficiencies are all less than 0.15. A maximum exergetic cooling of 1.94 W is estimated with a corresponding specific exergetic cooling power of 23 W T−1L−1. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002008

The influence of the magnetic field on the performance of an active magnetic regenerator (AMR) / R. Bjørk in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 192-203 Titre : The influence of the magnetic field on the performance of an active magnetic regenerator (AMR) Titre original : Influence du champ magnétique actif sur la performance d'un régénérateur magnétique actif Type de document : texte imprimé Auteurs : R. Bjørk, Auteur ; K. Engelbrecht, Auteur Année de publication : 2011 Article en page(s) : pp. 192-203 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Magnetic  field  Simulation  Modelling  Performance  Variation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The influence of the time variation of the magnetic field, termed the magnetic field profile, on the performance of a magnetocaloric refrigeration device using the active magnetic regeneration (AMR) cycle is studied for a number of process parameters for both a parallel plate and packed bed regenerator using a numerical model. The cooling curve of the AMR is shown to be almost linear far from the Curie temperature of the magnetocaloric material. It is shown that a magnetic field profile that is 10% of the cycle time out of sync with the flow profile leads to a drop in both the maximum temperature span and the maximum cooling capacity of 20–40% for both parallel plate and packed bed regenerators. The maximum cooling capacity is shown to depend very weakly on the ramp rate of the magnetic field. Reducing the temporal width of the high field portion of the magnetic field profile by 10% leads to a drop in maximum temperature span and maximum cooling capacity of 5–20%. An increase of the magnetic field from 1 T to 1.5 T increases the maximum cooling capacity by 30–50% but the maximum temperature span by only 20–30%. Finally, it was seen that the influence of changing the magnetic field was more or less the same for the different regenerator geometries and operating parameters studied here. This means that the design of the magnet can be done independently of the regenerator geometry. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001507 [article] The influence of the magnetic field on the performance of an active magnetic regenerator (AMR) = Influence du champ magnétique actif sur la performance d'un régénérateur magnétique actif [texte imprimé] / R. Bjørk, Auteur ; K. Engelbrecht, Auteur . - 2011 . - pp. 192-203. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 192-203 Mots-clés : Magnetic  refrigerator  Magnetic  field  Simulation  Modelling  Performance  Variation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The influence of the time variation of the magnetic field, termed the magnetic field profile, on the performance of a magnetocaloric refrigeration device using the active magnetic regeneration (AMR) cycle is studied for a number of process parameters for both a parallel plate and packed bed regenerator using a numerical model. The cooling curve of the AMR is shown to be almost linear far from the Curie temperature of the magnetocaloric material. It is shown that a magnetic field profile that is 10% of the cycle time out of sync with the flow profile leads to a drop in both the maximum temperature span and the maximum cooling capacity of 20–40% for both parallel plate and packed bed regenerators. The maximum cooling capacity is shown to depend very weakly on the ramp rate of the magnetic field. Reducing the temporal width of the high field portion of the magnetic field profile by 10% leads to a drop in maximum temperature span and maximum cooling capacity of 5–20%. An increase of the magnetic field from 1 T to 1.5 T increases the maximum cooling capacity by 30–50% but the maximum temperature span by only 20–30%. Finally, it was seen that the influence of changing the magnetic field was more or less the same for the different regenerator geometries and operating parameters studied here. This means that the design of the magnet can be done independently of the regenerator geometry. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001507

Numerical simulation and its verification for an active magnetic regenerator / Youngkwon Kim in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 204-215 Titre : Numerical simulation and its verification for an active magnetic regenerator Titre original : Régénérateur magnétique actif : simulation numérique et vérification Type de document : texte imprimé Auteurs : Youngkwon Kim, Auteur ; Sangkwon Jeong, Auteur Année de publication : 2011 Article en page(s) : pp. 204-215 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic  refrigerator  Modelling  Simulation  Comparison  Experiment  Gadolinium Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, a one-dimensional model for the active magnetic regenerator (AMR) is established and verified by comparison with the experimental results. Besides four basic governing equations concerning mass and momentum conservation of heat transfer fluid and energy conservation of fluid and magnetic refrigerant, energy conservation of the regenerator wall is considered to achieve high accuracy and generalization. For the verification, a room temperature AMR has been fabricated with Gd and Halbach array. The AMR is operated by helium compressor with a rotary valve so that the effect of gas-compression/expansion also exists. Instantaneous mass flow rate and temperature distributions are measured during the experiment. Measured values are utilized as the boundary conditions and compared with the simulation results. Instead of cooling capacity or COP, simulation results are directly compared with the experimental results by temperature distribution in the AMR. The model and simulation results predict temperature distribution of the AMR properly at cyclic steady-state. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001490 [article] Numerical simulation and its verification for an active magnetic regenerator = Régénérateur magnétique actif : simulation numérique et vérification [texte imprimé] / Youngkwon Kim, Auteur ; Sangkwon Jeong, Auteur . - 2011 . - pp. 204-215. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 204-215 Mots-clés : Magnetic  refrigerator  Modelling  Simulation  Comparison  Experiment  Gadolinium Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, a one-dimensional model for the active magnetic regenerator (AMR) is established and verified by comparison with the experimental results. Besides four basic governing equations concerning mass and momentum conservation of heat transfer fluid and energy conservation of fluid and magnetic refrigerant, energy conservation of the regenerator wall is considered to achieve high accuracy and generalization. For the verification, a room temperature AMR has been fabricated with Gd and Halbach array. The AMR is operated by helium compressor with a rotary valve so that the effect of gas-compression/expansion also exists. Instantaneous mass flow rate and temperature distributions are measured during the experiment. Measured values are utilized as the boundary conditions and compared with the simulation results. Instead of cooling capacity or COP, simulation results are directly compared with the experimental results by temperature distribution in the AMR. The model and simulation results predict temperature distribution of the AMR properly at cyclic steady-state. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001490

Performance optimization of a two-circuit cycle with parallel evaporators for a domestic refrigerator–freezer / Won Jae Yoon in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 216-224 Titre : Performance optimization of a two-circuit cycle with parallel evaporators for a domestic refrigerator–freezer Titre original : Optimisation de la performance d'un cycle à deux circuits muni d'évaporateurs parallèles pour un réfrigérateur/congélateur domestique Type de document : texte imprimé Auteurs : Won Jae Yoon, Auteur ; Hae Won Jung, Auteur ; Hyun Joon Chung, Auteur Année de publication : 2011 Article en page(s) : pp. 216-224 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Household  refrigerator  Parallel  flow  Cycle  Performance  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A two-circuit cycle with parallel evaporators (called a “parallel cycle”) for a domestic refrigerator–freezer (RF) shows energy saving potential compared with a conventional cycle with a single loop or serial evaporators because of a low compression ratio in the fresh food compartment (R)-operation. The objective of this study is to investigate the effects of the refrigerant charge, R-capillary tube, and refrigerant recovery operation on the performance of a parallel cycle. In addition, design guidelines for the heat transfer area and air flow rate of an R-evaporator are proposed. When the parallel cycle was optimized in terms of the refrigerant charge and R-capillary tube diameter, the energy consumption was reduced by 7.8% over a bypass two-circuit cycle with the same RF platform. In addition, an additional energy saving of 1.8% was obtained by the optimization of the operating sequence and refrigerant recovery operation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002136 [article] Performance optimization of a two-circuit cycle with parallel evaporators for a domestic refrigerator–freezer = Optimisation de la performance d'un cycle à deux circuits muni d'évaporateurs parallèles pour un réfrigérateur/congélateur domestique [texte imprimé] / Won Jae Yoon, Auteur ; Hae Won Jung, Auteur ; Hyun Joon Chung, Auteur . - 2011 . - pp. 216-224. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 216-224 Mots-clés : Household  refrigerator  Parallel  flow  Cycle  Performance  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A two-circuit cycle with parallel evaporators (called a “parallel cycle”) for a domestic refrigerator–freezer (RF) shows energy saving potential compared with a conventional cycle with a single loop or serial evaporators because of a low compression ratio in the fresh food compartment (R)-operation. The objective of this study is to investigate the effects of the refrigerant charge, R-capillary tube, and refrigerant recovery operation on the performance of a parallel cycle. In addition, design guidelines for the heat transfer area and air flow rate of an R-evaporator are proposed. When the parallel cycle was optimized in terms of the refrigerant charge and R-capillary tube diameter, the energy consumption was reduced by 7.8% over a bypass two-circuit cycle with the same RF platform. In addition, an additional energy saving of 1.8% was obtained by the optimization of the operating sequence and refrigerant recovery operation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002136

Performance of vapor compression systems with compressor oil flooding and regeneration / Ian H. Bell in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 225-233 Titre : Performance of vapor compression systems with compressor oil flooding and regeneration Titre original : Performance des systèmes à compression de vapeur munis de compresseurs avec suralimentation en huile et régénération Type de document : texte imprimé Auteurs : Ian H. Bell, Auteur ; Eckhard A. Groll, Auteur ; James E. Braun, Auteur Année de publication : 2011 Article en page(s) : pp. 225-233 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air-conditioning  Refrigeration  Regeneration  Flooding  Efficiency-compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Vapor compression refrigeration technology has seen great improvement over the last several decades in terms of cycle efficiency through a concerted effort of manufacturers, regulators, and research engineers. As the standard vapor compression systems approach practical limits, cycle modifications should be investigated to increase system efficiency and capacity. One possible means of increasing cycle efficiency is to flood the compressor with a large quantity of oil to achieve a quasi-isothermal compression process, in addition to using a regenerator to increase refrigerant subcooling. In theory, compressor flooding and regeneration can provide a significant increase in system efficiency over the standard vapor compression system. The effectiveness of compressor flooding and regeneration increases as the temperature lift of the system increases. Therefore, this technology is particularly well suited towards lower evaporating temperatures and high ambient temperatures as seen in supermarket refrigeration applications. While predicted increases in cycle efficiency are over 40% for supermarket refrigeration applications, this technology is still very beneficial for typical air-conditioning applications, for which improvements in cycle efficiency greater than 5% are predicted. It has to be noted though that the beneficial effects of compressor flooding can only be realized if a regenerator is used to exchange heat between the refrigerant vapor exiting the evaporator and the liquid exiting the condenser. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002094 [article] Performance of vapor compression systems with compressor oil flooding and regeneration = Performance des systèmes à compression de vapeur munis de compresseurs avec suralimentation en huile et régénération [texte imprimé] / Ian H. Bell, Auteur ; Eckhard A. Groll, Auteur ; James E. Braun, Auteur . - 2011 . - pp. 225-233. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 225-233 Mots-clés : Air-conditioning  Refrigeration  Regeneration  Flooding  Efficiency-compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Vapor compression refrigeration technology has seen great improvement over the last several decades in terms of cycle efficiency through a concerted effort of manufacturers, regulators, and research engineers. As the standard vapor compression systems approach practical limits, cycle modifications should be investigated to increase system efficiency and capacity. One possible means of increasing cycle efficiency is to flood the compressor with a large quantity of oil to achieve a quasi-isothermal compression process, in addition to using a regenerator to increase refrigerant subcooling. In theory, compressor flooding and regeneration can provide a significant increase in system efficiency over the standard vapor compression system. The effectiveness of compressor flooding and regeneration increases as the temperature lift of the system increases. Therefore, this technology is particularly well suited towards lower evaporating temperatures and high ambient temperatures as seen in supermarket refrigeration applications. While predicted increases in cycle efficiency are over 40% for supermarket refrigeration applications, this technology is still very beneficial for typical air-conditioning applications, for which improvements in cycle efficiency greater than 5% are predicted. It has to be noted though that the beneficial effects of compressor flooding can only be realized if a regenerator is used to exchange heat between the refrigerant vapor exiting the evaporator and the liquid exiting the condenser. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002094

Performance limit for economized cycles with continuous refrigerant injection / Margaret M. Mathison in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 234-242 Titre : Performance limit for economized cycles with continuous refrigerant injection Titre original : Limites de la performance des cycles à économiseur avec injection continue de frigorigène Type de document : texte imprimé Auteurs : Margaret M. Mathison, Auteur ; James E. Braun, Auteur ; Eckhard A. Groll, Auteur Année de publication : 2011 Article en page(s) : pp. 234-242 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : System  Multistage  Modelling  Injection  Energy  saving  Cycle-thermodynamic Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : While economizing can improve the performance of vapor compression cycles, the cost of multi-stage compressors has limited its implementation to large-scale applications. However, the development of compressors with injection ports presents new opportunities for economizing in smaller-scale applications. In addition to eliminating the need for a costly multi-stage compressor, multiple injection ports can be added at relatively low cost to further improve cycle performance. In the current study, a model was developed to study the effect of the number of injection ports on performance and determine the limit to performance with injection. The model predicts that continuous injection, in which economized refrigerant is injected at an infinite number of ports to maintain saturated vapor in the compressor, provides very significant performance improvements for air-conditioning and refrigeration applications. At standard operating conditions, the COP increases between 18% and 51% depending on the application, with higher temperature lift cycles benefiting most significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002112 [article] Performance limit for economized cycles with continuous refrigerant injection = Limites de la performance des cycles à économiseur avec injection continue de frigorigène [texte imprimé] / Margaret M. Mathison, Auteur ; James E. Braun, Auteur ; Eckhard A. Groll, Auteur . - 2011 . - pp. 234-242. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 234-242 Mots-clés : System  Multistage  Modelling  Injection  Energy  saving  Cycle-thermodynamic Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : While economizing can improve the performance of vapor compression cycles, the cost of multi-stage compressors has limited its implementation to large-scale applications. However, the development of compressors with injection ports presents new opportunities for economizing in smaller-scale applications. In addition to eliminating the need for a costly multi-stage compressor, multiple injection ports can be added at relatively low cost to further improve cycle performance. In the current study, a model was developed to study the effect of the number of injection ports on performance and determine the limit to performance with injection. The model predicts that continuous injection, in which economized refrigerant is injected at an infinite number of ports to maintain saturated vapor in the compressor, provides very significant performance improvements for air-conditioning and refrigeration applications. At standard operating conditions, the COP increases between 18% and 51% depending on the application, with higher temperature lift cycles benefiting most significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002112

Multi-objective optimization of a cooling tower assisted vapor compression refrigeration system / Hoseyn Sayyaadi in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 243-256 Titre : Multi-objective optimization of a cooling tower assisted vapor compression refrigeration system Titre original : Optimisation d'un système frigorifique à compression de vapeur doté d'une tour de refroidissement menée avec plusieurs objectifs Type de document : texte imprimé Auteurs : Hoseyn Sayyaadi, Auteur ; Mostafa Nejatolahi, Auteur Année de publication : 2011 Article en page(s) : pp. 243-256 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration  system  Cooling  tower  Exergy  Economy  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A cooling tower assisted vapor compression refrigeration machine has been considered for optimization with multiple criteria. Two objective functions including the total exergy destruction of the system (as a thermodynamic criterion) and the total product cost of the system (as an economic criterion), have been considered simultaneously. A thermodynamic model based on energy and exergy analyses and an economic model according to the Total Revenue Requirement (TRR) method have been developed. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final solution from the Pareto frontier has been presented. The exergetic and economic results obtained for three optimized systems have been compared and discussed. The results have shown that the multi-objective design more acceptably satisfies generalized engineering criteria than other two single-objective optimized designs. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001726 [article] Multi-objective optimization of a cooling tower assisted vapor compression refrigeration system = Optimisation d'un système frigorifique à compression de vapeur doté d'une tour de refroidissement menée avec plusieurs objectifs [texte imprimé] / Hoseyn Sayyaadi, Auteur ; Mostafa Nejatolahi, Auteur . - 2011 . - pp. 243-256. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 243-256 Mots-clés : Refrigeration  system  Cooling  tower  Exergy  Economy  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A cooling tower assisted vapor compression refrigeration machine has been considered for optimization with multiple criteria. Two objective functions including the total exergy destruction of the system (as a thermodynamic criterion) and the total product cost of the system (as an economic criterion), have been considered simultaneously. A thermodynamic model based on energy and exergy analyses and an economic model according to the Total Revenue Requirement (TRR) method have been developed. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final solution from the Pareto frontier has been presented. The exergetic and economic results obtained for three optimized systems have been compared and discussed. The results have shown that the multi-objective design more acceptably satisfies generalized engineering criteria than other two single-objective optimized designs. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001726

Experimental evaluation of a cascade refrigeration system prototype with CO2 and NH3 for freezing process applications / J. Alberto Dopazo in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 257-267 Titre : Experimental evaluation of a cascade refrigeration system prototype with CO2 and NH3 for freezing process applications Titre original : Evaluation expérimentale d'un système frigorifique au CO2/NH3 en cascade utilisé pour les applications congélation Type de document : texte imprimé Auteurs : J. Alberto Dopazo, Auteur ; José Fernández-Seara, Auteur Année de publication : 2011 Article en page(s) : pp. 257-267 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration  system  Cascade  system  Carbon  dioxide  Ammonia-development  Prototype-experiment Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A prototype of a cascade refrigeration system using NH3 and CO2 as refrigerants has been designed and built. The prototype is used to supply a 9 kW refrigeration capacity horizontal plate freezer at an evaporating temperature of −50 °C as design conditions. The prototype includes a specific control system and a data acq*uisition system. The experimental evaluation started with the real conditions within the design operating parameters. Subsequently, several tests were performed fixing four CO2 evaporating temperatures (−50, −45, −40 and −35 °C). At each one of the evaporating temperatures evaluated, the CO2 condensing temperature was varied from −17.5 to −7.5 °C and an experimental optimum value of CO2 condensing temperature was determined. The discussions on the experimental results include the influence of the operating parameters on the cascade system’s performance. In addition, the experimental results are compared with two common double stage refrigeration systems using NH3 as refrigerant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001568 [article] Experimental evaluation of a cascade refrigeration system prototype with CO2 and NH3 for freezing process applications = Evaluation expérimentale d'un système frigorifique au CO2/NH3 en cascade utilisé pour les applications congélation [texte imprimé] / J. Alberto Dopazo, Auteur ; José Fernández-Seara, Auteur . - 2011 . - pp. 257-267. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 257-267 Mots-clés : Refrigeration  system  Cascade  system  Carbon  dioxide  Ammonia-development  Prototype-experiment Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A prototype of a cascade refrigeration system using NH3 and CO2 as refrigerants has been designed and built. The prototype is used to supply a 9 kW refrigeration capacity horizontal plate freezer at an evaporating temperature of −50 °C as design conditions. The prototype includes a specific control system and a data acq*uisition system. The experimental evaluation started with the real conditions within the design operating parameters. Subsequently, several tests were performed fixing four CO2 evaporating temperatures (−50, −45, −40 and −35 °C). At each one of the evaporating temperatures evaluated, the CO2 condensing temperature was varied from −17.5 to −7.5 °C and an experimental optimum value of CO2 condensing temperature was determined. The discussions on the experimental results include the influence of the operating parameters on the cascade system’s performance. In addition, the experimental results are compared with two common double stage refrigeration systems using NH3 as refrigerant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001568

Modification of Tao-Mason equation of state: Application to refrigerant fluids / Mohammad Mehdi Papari in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 268-274 Titre : Modification of Tao-Mason equation of state: Application to refrigerant fluids Titre original : Modification de l'équation d'état Tao-Mason : application aux fluides frigorigènes Type de document : texte imprimé Auteurs : Mohammad Mehdi Papari, Auteur ; Rozita Nejabat, Auteur ; Jalil Moghadasi, Auteur Année de publication : 2011 Article en page(s) : pp. 268-274 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigerant  Equation  of  state  Enthalpy  Entropy  Thermodynamic  property Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present work addresses a simplified procedure for the calculation of certain parameters in the Tao-Mason (TM) equation of state needed to estimate thermodynamic properties of 12 ozone–friendly refrigerants fluids. The calculations cover wide ranges extending from the dilute vapor or gas to highly compressed liquid and supercritical region. The theoretical equation of state (EOS) is that of Tao and Mason which is based on statistical mechanical perturbation theory. The novelty of the present work is that we use two scaling constants, the enthalpy of vaporization and the molar density, both evaluated at the normal boiling temperature. This approach contrasts with the original procedure that employs five scaling constants including the critical temperature, the critical pressure, the Boyle temperature, the Boyle pressure and the acentric factor for calculating three parameters second virial coefficient and temperature-dependent parameters. The modified TM EOS predicts thermodynamic properties with equal or better accuracy than those emerging from the original TM EOS. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002161 [article] Modification of Tao-Mason equation of state: Application to refrigerant fluids = Modification de l'équation d'état Tao-Mason : application aux fluides frigorigènes [texte imprimé] / Mohammad Mehdi Papari, Auteur ; Rozita Nejabat, Auteur ; Jalil Moghadasi, Auteur . - 2011 . - pp. 268-274. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 268-274 Mots-clés : Refrigerant  Equation  of  state  Enthalpy  Entropy  Thermodynamic  property Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present work addresses a simplified procedure for the calculation of certain parameters in the Tao-Mason (TM) equation of state needed to estimate thermodynamic properties of 12 ozone–friendly refrigerants fluids. The calculations cover wide ranges extending from the dilute vapor or gas to highly compressed liquid and supercritical region. The theoretical equation of state (EOS) is that of Tao and Mason which is based on statistical mechanical perturbation theory. The novelty of the present work is that we use two scaling constants, the enthalpy of vaporization and the molar density, both evaluated at the normal boiling temperature. This approach contrasts with the original procedure that employs five scaling constants including the critical temperature, the critical pressure, the Boyle temperature, the Boyle pressure and the acentric factor for calculating three parameters second virial coefficient and temperature-dependent parameters. The modified TM EOS predicts thermodynamic properties with equal or better accuracy than those emerging from the original TM EOS. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002161

Measurement of isobaric heat capacity of R125 / Noboru Kagawa in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 275-279 Titre : Measurement of isobaric heat capacity of R125 Titre original : Mesure de la capacité thermique isobare du R125 Type de document : texte imprimé Auteurs : Noboru Kagawa, Auteur ; Atsushi Matsuguchi, Auteur ; Koichi Watanabe, Auteur Année de publication : 2011 Article en page(s) : pp. 275-279 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  capacity  R125  Gas  Calorimeter  Thermodynamic  properties  Refrigeration  Air  conditioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The specific isobaric heat capacity (cp) was measured for R125 (pentafluoroethane) in the gas phase by using a flow calorimeter. Twelve measurements for R125 were obtained at temperatures from 313 to 333 K and at pressures from 0.8 to 2.4 MPa. Some of them are close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 14 kPa. The expanded uncertainty for cp is estimated to range from 12 to 22 J kg−1 K−1. Also, the experimental data were compared with available equations of state. From the results, it became clear that these data will be essential to improve available models so as to represent more reliable thermodynamic properties of R125 and refrigerant mixtures with R125 that are used for refrigeration and air conditioning systems. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001817 [article] Measurement of isobaric heat capacity of R125 = Mesure de la capacité thermique isobare du R125 [texte imprimé] / Noboru Kagawa, Auteur ; Atsushi Matsuguchi, Auteur ; Koichi Watanabe, Auteur . - 2011 . - pp. 275-279. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 275-279 Mots-clés : Heat  capacity  R125  Gas  Calorimeter  Thermodynamic  properties  Refrigeration  Air  conditioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The specific isobaric heat capacity (cp) was measured for R125 (pentafluoroethane) in the gas phase by using a flow calorimeter. Twelve measurements for R125 were obtained at temperatures from 313 to 333 K and at pressures from 0.8 to 2.4 MPa. Some of them are close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 14 kPa. The expanded uncertainty for cp is estimated to range from 12 to 22 J kg−1 K−1. Also, the experimental data were compared with available equations of state. From the results, it became clear that these data will be essential to improve available models so as to represent more reliable thermodynamic properties of R125 and refrigerant mixtures with R125 that are used for refrigeration and air conditioning systems. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001817

An experimental study into the evaporation heat transfer and flow characteristics of R-134a refrigerant flowing through corrugated tubes / Suriyan Laohalertdecha in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 280-291 Titre : An experimental study into the evaporation heat transfer and flow characteristics of R-134a refrigerant flowing through corrugated tubes Titre original : Etude expérimentale sur le transfert de chaleur lors de l'évaporation et les caractéristiques d'écoulement du frigorigène R-134a en écoulement à l'intérieur de tubes ondulés Type de document : texte imprimé Auteurs : Suriyan Laohalertdecha, Auteur ; Somchai Wongwises, Auteur Année de publication : 2011 Article en page(s) : pp. 280-291 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Two-phase  flow  Pressure  Temperature  R-134a  Heat  transfer  enhancement  Corrugated  tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The effects of corrugation pitch on the evaporation of R-134a flowing inside horizontal corrugated tubes are investigated. The test section is a tube-in-tube heat exchanger with refrigerant flowing in the inner tube and hot water flowing in the annulus. Smooth and corrugated tubes having similar inside diameters are used as the inner tube. Three corrugated tubes having a corrugation depth fixed at 1.5 mm and corrugation pitches of 5.08, 6.35 and 8.46 mm are examined. The data obtained from smooth tube are plotted and compared with the flow pattern map established by Censi et al. (2003) and Zurcher et al. (2002). The effects of average vapour quality, equivalent Reynolds number and corrugation pitch are discussed. The maximum ratios of heat transfer enhancement factor to pressure drop penalty factor (Nuc/Nus)/((ΔP/L)c/(ΔP/L)s) is approximately 1.2. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001581 [article] An experimental study into the evaporation heat transfer and flow characteristics of R-134a refrigerant flowing through corrugated tubes = Etude expérimentale sur le transfert de chaleur lors de l'évaporation et les caractéristiques d'écoulement du frigorigène R-134a en écoulement à l'intérieur de tubes ondulés [texte imprimé] / Suriyan Laohalertdecha, Auteur ; Somchai Wongwises, Auteur . - 2011 . - pp. 280-291. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 280-291 Mots-clés : Two-phase  flow  Pressure  Temperature  R-134a  Heat  transfer  enhancement  Corrugated  tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The effects of corrugation pitch on the evaporation of R-134a flowing inside horizontal corrugated tubes are investigated. The test section is a tube-in-tube heat exchanger with refrigerant flowing in the inner tube and hot water flowing in the annulus. Smooth and corrugated tubes having similar inside diameters are used as the inner tube. Three corrugated tubes having a corrugation depth fixed at 1.5 mm and corrugation pitches of 5.08, 6.35 and 8.46 mm are examined. The data obtained from smooth tube are plotted and compared with the flow pattern map established by Censi et al. (2003) and Zurcher et al. (2002). The effects of average vapour quality, equivalent Reynolds number and corrugation pitch are discussed. The maximum ratios of heat transfer enhancement factor to pressure drop penalty factor (Nuc/Nus)/((ΔP/L)c/(ΔP/L)s) is approximately 1.2. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001581

Investigating performance of microchannel evaporators with different manifold structures / Junye Shi in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 292-302 Titre : Investigating performance of microchannel evaporators with different manifold structures Titre original : Etude sur la performance des évaporateurs à microcanaux des collecteurs de structures différentes Type de document : texte imprimé Auteurs : Junye Shi, Auteur ; Xiaohua Qu, Auteur ; Zhaogang Qi, Auteur Année de publication : 2011 Article en page(s) : pp. 292-302 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Microchannel  evaporator  Flow  distribution  Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, the performances of microchannel evaporators with different manifold structures are experimentally investigated. Eight evaporator samples with 7 different designs of the I/O manifold and 5 different designs of the return manifold are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant 134A at a real automotive AC condition. The results on the variations of the cooling capacity and air temperature distribution of the evaporator due to the deflector designs in the I/O manifold and flow hole arrangements in the return manifold are presented and analyzed. By studying the KPI’s for the performance of an evaporator, the design trade-off for an evaporator designer is summarized and discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001805 [article] Investigating performance of microchannel evaporators with different manifold structures = Etude sur la performance des évaporateurs à microcanaux des collecteurs de structures différentes [texte imprimé] / Junye Shi, Auteur ; Xiaohua Qu, Auteur ; Zhaogang Qi, Auteur . - 2011 . - pp. 292-302. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 292-302 Mots-clés : Microchannel  evaporator  Flow  distribution  Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, the performances of microchannel evaporators with different manifold structures are experimentally investigated. Eight evaporator samples with 7 different designs of the I/O manifold and 5 different designs of the return manifold are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant 134A at a real automotive AC condition. The results on the variations of the cooling capacity and air temperature distribution of the evaporator due to the deflector designs in the I/O manifold and flow hole arrangements in the return manifold are presented and analyzed. By studying the KPI’s for the performance of an evaporator, the design trade-off for an evaporator designer is summarized and discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001805

The heat transfer performance of horizontal tube bundles in large falling film evaporators / Yang, Li in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 303-316 Titre : The heat transfer performance of horizontal tube bundles in large falling film evaporators Titre original : Performance en termes de transfert de chaleur des faisceaux de tubes horizontaux dans les évaporateurs à film tombant de grandes dimensions Type de document : texte imprimé Auteurs : Yang, Li, Auteur ; Wen Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 303-316 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Evaporator  Falling  film  Bundle  Modelling-simulation  Heat  transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of the horizontal heat transfer tube bundles in falling film evaporators in large compression refrigeration systems was investigated with numerical simulation in this paper. Four types of tubes, including plain tubes, and enhanced surface tubes of Turbo-B, Turbo-BII and Turbo-EHP, were employed in the simulation. Some factors, such as tube kind, tube pass arrangement, dry patch area on tube surface, liquid refrigerant flow rate, and number of flooded tubes, were analyzed based on simulated results. In the study, the maldistribution of liquid refrigerant flow caused by the distributor apparatus was discussed, which severely affects the performance of falling film evaporators according to the simulation. Some calculated results were verified by the experiment. These discussions and results can be used to guide the design of falling film evaporators under realistic flow conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000157X [article] The heat transfer performance of horizontal tube bundles in large falling film evaporators = Performance en termes de transfert de chaleur des faisceaux de tubes horizontaux dans les évaporateurs à film tombant de grandes dimensions [texte imprimé] / Yang, Li, Auteur ; Wen Wang, Auteur . - 2011 . - pp. 303-316. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 303-316 Mots-clés : Evaporator  Falling  film  Bundle  Modelling-simulation  Heat  transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of the horizontal heat transfer tube bundles in falling film evaporators in large compression refrigeration systems was investigated with numerical simulation in this paper. Four types of tubes, including plain tubes, and enhanced surface tubes of Turbo-B, Turbo-BII and Turbo-EHP, were employed in the simulation. Some factors, such as tube kind, tube pass arrangement, dry patch area on tube surface, liquid refrigerant flow rate, and number of flooded tubes, were analyzed based on simulated results. In the study, the maldistribution of liquid refrigerant flow caused by the distributor apparatus was discussed, which severely affects the performance of falling film evaporators according to the simulation. Some calculated results were verified by the experiment. These discussions and results can be used to guide the design of falling film evaporators under realistic flow conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000157X

Condensation heat transfer coefficients of R1234yf on plain, low fin, and Turbo-C tubes / Ki-Jung Park in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 317-321 Titre : Condensation heat transfer coefficients of R1234yf on plain, low fin, and Turbo-C tubes Titre original : Coefficients de transfert de chaleur lors de la condensation du R1234yf sur les tubes lisses, aux ailettes basses et de type “Turbo C” Type de document : texte imprimé Auteurs : Ki-Jung Park, Auteur ; Dong Gyu Kang, Auteur ; Dongsoo Jung, Auteur Année de publication : 2011 Article en page(s) : pp. 317-321 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Condenser  R1234yf  R134a  Measurement  Heat  transfer  coefficient  Plain  tube  Finned  tube  Air  conditioning  Automobile Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, external condensation heat transfer coefficients (HTCs) of HFC134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of 39 °C with the wall subcooling of 3–8 °C. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing HFC134a, one of the greenhouse gases in Kyoto protocol, used extensively in automobile air conditioners and other refrigeration systems. Test results show that the condensation HTCs of R1234yf are very similar to those of HFC134a for all three surfaces tested. For the development of heat transfer correlations, thorough property measurements are needed for R1234yf in the near future. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001295 [article] Condensation heat transfer coefficients of R1234yf on plain, low fin, and Turbo-C tubes = Coefficients de transfert de chaleur lors de la condensation du R1234yf sur les tubes lisses, aux ailettes basses et de type “Turbo C” [texte imprimé] / Ki-Jung Park, Auteur ; Dong Gyu Kang, Auteur ; Dongsoo Jung, Auteur . - 2011 . - pp. 317-321. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 317-321 Mots-clés : Heat  exchanger  Condenser  R1234yf  R134a  Measurement  Heat  transfer  coefficient  Plain  tube  Finned  tube  Air  conditioning  Automobile Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, external condensation heat transfer coefficients (HTCs) of HFC134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of 39 °C with the wall subcooling of 3–8 °C. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing HFC134a, one of the greenhouse gases in Kyoto protocol, used extensively in automobile air conditioners and other refrigeration systems. Test results show that the condensation HTCs of R1234yf are very similar to those of HFC134a for all three surfaces tested. For the development of heat transfer correlations, thorough property measurements are needed for R1234yf in the near future. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001295

Experimental investigation of vortex tube refrigerator with a divergent hot tube / Kun Chang in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 322-327 Titre : Experimental investigation of vortex tube refrigerator with a divergent hot tube Titre original : Etude expérimentale sur un réfrigérateur à tube vortex muni d'un tube chaud divergent Type de document : texte imprimé Auteurs : Kun Chang, Auteur ; Qing Li, Auteur ; Gang Zhou, Auteur Année de publication : 2011 Article en page(s) : pp. 322-327 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Vortex  tube  Refrigerator  Nozzle  Divergent  tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Energy separation performance of vortex tube can be improved by using a divergent hot tube. Experiments are carried out to investigate the influence of the geometrical parameters on vortex tube refrigeration capacity by using nitrogen as the working fluid. In this work, the parameters are focused on the divergence angle of hot tube, length of divergent hot tube and number of nozzle intakes. Experimental results present that there is an optimum angle for obtaining the highest refrigeration performance, and 4° is the optimal candidate under our experimental conditions. Divergent tube length which exceeds a critical length has slight effect on the refrigeration capacity. The critical length to diameter ratio is L/D = 12 in our experiment. Increasing number of nozzle intakes increases the sensitivity of temperature reduction and can obtain the highest possible temperature reduction. Moreover, similarity relations for the prediction of the cold exit stream are presented and confirmed by the experimental data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002057 [article] Experimental investigation of vortex tube refrigerator with a divergent hot tube = Etude expérimentale sur un réfrigérateur à tube vortex muni d'un tube chaud divergent [texte imprimé] / Kun Chang, Auteur ; Qing Li, Auteur ; Gang Zhou, Auteur . - 2011 . - pp. 322-327. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 322-327 Mots-clés : Vortex  tube  Refrigerator  Nozzle  Divergent  tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Energy separation performance of vortex tube can be improved by using a divergent hot tube. Experiments are carried out to investigate the influence of the geometrical parameters on vortex tube refrigeration capacity by using nitrogen as the working fluid. In this work, the parameters are focused on the divergence angle of hot tube, length of divergent hot tube and number of nozzle intakes. Experimental results present that there is an optimum angle for obtaining the highest refrigeration performance, and 4° is the optimal candidate under our experimental conditions. Divergent tube length which exceeds a critical length has slight effect on the refrigeration capacity. The critical length to diameter ratio is L/D = 12 in our experiment. Increasing number of nozzle intakes increases the sensitivity of temperature reduction and can obtain the highest possible temperature reduction. Moreover, similarity relations for the prediction of the cold exit stream are presented and confirmed by the experimental data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002057

Heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers operating under frosting conditions / Mooyeon Lee in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 328-336 Titre : Heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers operating under frosting conditions Titre original : Caractéristiques de transfert de chaleur des échangeurs de chaleur spiralés avec tubes ailetés circulaires fonctionnant sous des conditions de givrage Type de document : texte imprimé Auteurs : Mooyeon Lee, Auteur ; Taehyung Kang, Auteur ; Youngju Joo, Auteur Année de publication : 2011 Article en page(s) : pp. 328-336 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  transfer  Heat  exchanger  Correlation  Frosting  Pressure  drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The objective of this study is to investigate the heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers under frosting conditions. The heat transfer rate, pressure drop, frost thickness, and Nusselt number of the heat exchanger were measured and analyzed by varying the fin pitch and number of tube rows under frosting conditions. In addition, the Nusselt number of the spirally-coiled circular fin-tube exchanger was compared with those of flat plate fin-tube heat exchangers with discrete fins. An empirical correlation of the Nusselt number was developed as a function of the Reynolds number, dimensionless fin pitch normalized by the hydraulic diameter, i.e., Dh/Fp, Fourier number, and number of tube rows. The measured Nusselt number was consistent with the predicted value with mean and average deviations of 3.5% and 0.3%, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001854 [article] Heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers operating under frosting conditions = Caractéristiques de transfert de chaleur des échangeurs de chaleur spiralés avec tubes ailetés circulaires fonctionnant sous des conditions de givrage [texte imprimé] / Mooyeon Lee, Auteur ; Taehyung Kang, Auteur ; Youngju Joo, Auteur . - 2011 . - pp. 328-336. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 328-336 Mots-clés : Heat  transfer  Heat  exchanger  Correlation  Frosting  Pressure  drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The objective of this study is to investigate the heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers under frosting conditions. The heat transfer rate, pressure drop, frost thickness, and Nusselt number of the heat exchanger were measured and analyzed by varying the fin pitch and number of tube rows under frosting conditions. In addition, the Nusselt number of the spirally-coiled circular fin-tube exchanger was compared with those of flat plate fin-tube heat exchangers with discrete fins. An empirical correlation of the Nusselt number was developed as a function of the Reynolds number, dimensionless fin pitch normalized by the hydraulic diameter, i.e., Dh/Fp, Fourier number, and number of tube rows. The measured Nusselt number was consistent with the predicted value with mean and average deviations of 3.5% and 0.3%, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001854

An analytical prediction for performance and optimum design analysis of porous fins / Balaram Kundu in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 337-352 Titre : An analytical prediction for performance and optimum design analysis of porous fins Titre original : Prévision, analytique de la performance et la conception optimale d'ailettes poreuses Type de document : texte imprimé Auteurs : Balaram Kundu, Auteur ; Dipankar Bhanja, Auteur Année de publication : 2011 Article en page(s) : pp. 337-352 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Fin  Porous  medium  Calculation  Improvement  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Enhancement of heat transfer rate through porous fins is one of the common choices nowadays. As the energy equation is highly nonlinear, researchers never concentrated on analyzing porous fins analytically. In the present study, an effort has been devoted to develop an analytical model for determination of the performance and optimum dimensions of porous fins with consideration of different models of predictions. Every result has been presented in a comparative way so that the merit of the models adopting in the present work can easily be understood. The optimum design analysis of porous fins has also been carried out. The influences of all the dependent parameters on the performances and optimization conditions have been studied for the selection of a design criterion of porous fins in such applications where the requirement of heat dissipation is essentially high. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001301 [article] An analytical prediction for performance and optimum design analysis of porous fins = Prévision, analytique de la performance et la conception optimale d'ailettes poreuses [texte imprimé] / Balaram Kundu, Auteur ; Dipankar Bhanja, Auteur . - 2011 . - pp. 337-352. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 337-352 Mots-clés : Heat  exchanger  Fin  Porous  medium  Calculation  Improvement  Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Enhancement of heat transfer rate through porous fins is one of the common choices nowadays. As the energy equation is highly nonlinear, researchers never concentrated on analyzing porous fins analytically. In the present study, an effort has been devoted to develop an analytical model for determination of the performance and optimum dimensions of porous fins with consideration of different models of predictions. Every result has been presented in a comparative way so that the merit of the models adopting in the present work can easily be understood. The optimum design analysis of porous fins has also been carried out. The influences of all the dependent parameters on the performances and optimization conditions have been studied for the selection of a design criterion of porous fins in such applications where the requirement of heat dissipation is essentially high. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001301

Analytical solution for the simultaneous heat and mass transfer problem in air washers / J.C. Santos in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 353-361 Titre : Analytical solution for the simultaneous heat and mass transfer problem in air washers Titre original : Solution analytique du problème de transfert simultané de chaleur et de masse dans un laveur d'air Type de document : texte imprimé Auteurs : J.C. Santos, Auteur ; J.M. Medeiros, Auteur Année de publication : 2011 Article en page(s) : pp. 353-361 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  conditioning  Air  washer  Evaporative  system  Calculation  Heat  transfer  Mass  transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An analytical solution approach for the simultaneous heat and mass transfer problem in air washers operating as evaporative coolers is presented. A one-dimensional model using the coupled mass and energy balance equations in the air washer is presented. Then, starting from a linear approach for the experimental curve of the air saturation, an analytical solution for the model was derived. The solution showed an excellent agreement with the available results found in the literature. The influence of several important parameters for the cooling process such as temperature and ambient air humidity, air flow rate and feeding water temperature, in the air cooling rate was investigated. The efficacy of the process can be greatly increased by reducing the cooling water temperature and the applied air flow rate. The analytical solution can be easily included into the models used for simulating desiccant air-conditioning systems operating in conjunction with air washers. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001465 [article] Analytical solution for the simultaneous heat and mass transfer problem in air washers = Solution analytique du problème de transfert simultané de chaleur et de masse dans un laveur d'air [texte imprimé] / J.C. Santos, Auteur ; J.M. Medeiros, Auteur . - 2011 . - pp. 353-361. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 353-361 Mots-clés : Air  conditioning  Air  washer  Evaporative  system  Calculation  Heat  transfer  Mass  transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An analytical solution approach for the simultaneous heat and mass transfer problem in air washers operating as evaporative coolers is presented. A one-dimensional model using the coupled mass and energy balance equations in the air washer is presented. Then, starting from a linear approach for the experimental curve of the air saturation, an analytical solution for the model was derived. The solution showed an excellent agreement with the available results found in the literature. The influence of several important parameters for the cooling process such as temperature and ambient air humidity, air flow rate and feeding water temperature, in the air cooling rate was investigated. The efficacy of the process can be greatly increased by reducing the cooling water temperature and the applied air flow rate. The analytical solution can be easily included into the models used for simulating desiccant air-conditioning systems operating in conjunction with air washers. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001465

Modelling of a thermal insulation system based on the coldest temperature conditions by using artificial neural networks to determine performance of building for wall types in Turkey / M. Tosun in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 362-373 Titre : Modelling of a thermal insulation system based on the coldest temperature conditions by using artificial neural networks to determine performance of building for wall types in Turkey Titre original : Modélisation d'un système d'isolation thermique fondée sur les températures les plus froides, à l'aide de réseaux neuronaux artificiels, afin de déterminer la performance de plusieurs types de murs d'immeubles en Turquie Type de document : texte imprimé Auteurs : M. Tosun, Auteur ; K. Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 362-373 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Insulation  Thermal  analysis  Wall  Building  Cooling  Neural  network Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In formation of building external envelope, as two important criteria, climatic data and wall types must be taken into consideration. In the selection of wall type, the thickness of thermal insulation layer (di) must be calculated. As a new approach, this study proposes determining the thermal insulation layer by using artificial neural network (ANN) technique. In this technique five different wall types in four different climatic regions in Turkey have been selected. The ANN was trained and tested by using MATLAB toolbox on a personal computer. As ANN input parameters, Uw, Te,Met, Te,TSE, Rwt, and qTSE were used, while di was the output parameter. It was found that the maximum mean absolute percentage error (MRE, %) is less than 7.658%. R2 (%) for the training data were found ranging about from 99.68 to 99.98 and R2 for the testing data varied between 97.55 and 99.96. These results show that ANN model can be used as a reliable modeling method of di studies. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001738 [article] Modelling of a thermal insulation system based on the coldest temperature conditions by using artificial neural networks to determine performance of building for wall types in Turkey = Modélisation d'un système d'isolation thermique fondée sur les températures les plus froides, à l'aide de réseaux neuronaux artificiels, afin de déterminer la performance de plusieurs types de murs d'immeubles en Turquie [texte imprimé] / M. Tosun, Auteur ; K. Dincer, Auteur . - 2011 . - pp. 362-373. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 362-373 Mots-clés : Insulation  Thermal  analysis  Wall  Building  Cooling  Neural  network Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In formation of building external envelope, as two important criteria, climatic data and wall types must be taken into consideration. In the selection of wall type, the thickness of thermal insulation layer (di) must be calculated. As a new approach, this study proposes determining the thermal insulation layer by using artificial neural network (ANN) technique. In this technique five different wall types in four different climatic regions in Turkey have been selected. The ANN was trained and tested by using MATLAB toolbox on a personal computer. As ANN input parameters, Uw, Te,Met, Te,TSE, Rwt, and qTSE were used, while di was the output parameter. It was found that the maximum mean absolute percentage error (MRE, %) is less than 7.658%. R2 (%) for the training data were found ranging about from 99.68 to 99.98 and R2 for the testing data varied between 97.55 and 99.96. These results show that ANN model can be used as a reliable modeling method of di studies. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001738

Development of a micro thermal sensor for real-time monitoring of lubricating oil concentration / Jonggan Hong in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 374-382 Titre : Development of a micro thermal sensor for real-time monitoring of lubricating oil concentration Titre original : Développement d'un capteur microthermique pour le suivi en temps réel de la concentration en huile lubrifiante Type de document : texte imprimé Auteurs : Jonggan Hong, Auteur ; Young Soo Chang, Auteur ; Dongsik Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 374-382 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Analysis  Development  Sensor  Measurement-concentration  Concentration  Oil  Refrigerant-concentration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : We report development of a micro thermal sensor and sensing techniques for monitoring the oil concentration in a refrigeration system. The sensor acquires the thermal response of the mixture to ac heating and then the concentration can be determined using one of the two different methods. In the first method, the thermal conductivity of the mixture is obtained using the three-omega method and the concentration is determined using the correlation between the mixture concentration and thermal conductivity. In the alternative fast-detection method, the concentration is determined by directly calibrating the sensor output signal to the mixture concentration. The performance of the sensor was tested using the R410A/polyvinyl ether (PVE) oil mixture. The uncertainty of the oil concentration measurement was estimated to be 5.8–7.3 wt.%, depending on the sensing scheme. Especially, the simple structure of the sensor makes the technique cost effective and adequate for miniaturization, i.e., for installation in a limited space. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001556 [article] Development of a micro thermal sensor for real-time monitoring of lubricating oil concentration = Développement d'un capteur microthermique pour le suivi en temps réel de la concentration en huile lubrifiante [texte imprimé] / Jonggan Hong, Auteur ; Young Soo Chang, Auteur ; Dongsik Kim, Auteur . - 2011 . - pp. 374-382. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 374-382 Mots-clés : Analysis  Development  Sensor  Measurement-concentration  Concentration  Oil  Refrigerant-concentration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : We report development of a micro thermal sensor and sensing techniques for monitoring the oil concentration in a refrigeration system. The sensor acquires the thermal response of the mixture to ac heating and then the concentration can be determined using one of the two different methods. In the first method, the thermal conductivity of the mixture is obtained using the three-omega method and the concentration is determined using the correlation between the mixture concentration and thermal conductivity. In the alternative fast-detection method, the concentration is determined by directly calibrating the sensor output signal to the mixture concentration. The performance of the sensor was tested using the R410A/polyvinyl ether (PVE) oil mixture. The uncertainty of the oil concentration measurement was estimated to be 5.8–7.3 wt.%, depending on the sensing scheme. Especially, the simple structure of the sensor makes the technique cost effective and adequate for miniaturization, i.e., for installation in a limited space. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001556

Yearly simulation of the interaction between an ice rink and its refrigeration system: A case study / Lotfi Seghouani in International journal of refrigeration, Vol. 34 N° 1 (Janvier 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 383-389 Titre : Yearly simulation of the interaction between an ice rink and its refrigeration system: A case study Titre original : Simulation annuelle de l'interaction entre une patinoire à glace et son système frigorifique: étude de cas Type de document : texte imprimé Auteurs : Lotfi Seghouani, Auteur ; Ahmed Daoud, Auteur ; Nicolas Galanis, Auteur Année de publication : 2011 Article en page(s) : pp. 383-389 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Energy  Consumption  Refrigeration  plant  Modelling  Building  Ice  rink Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A transient model of airflow and heat transfer in an indoor ice rink and a quasi-steady model of its refrigeration system have been coupled and used to simulate their response to the time dependent ambient conditions and operating schedule for a typical meteorological year. The results for two different cases show that it is possible to reduce significantly the time of operation of the compressors and the energy consumption of the refrigeration system by simultaneously reducing the ceiling emissivity and increasing the secondary coolant temperature without affecting the quality of the ice. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001702 [article] Yearly simulation of the interaction between an ice rink and its refrigeration system: A case study = Simulation annuelle de l'interaction entre une patinoire à glace et son système frigorifique: étude de cas [texte imprimé] / Lotfi Seghouani, Auteur ; Ahmed Daoud, Auteur ; Nicolas Galanis, Auteur . - 2011 . - pp. 383-389. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 1 (Janvier 2011) . - pp. 383-389 Mots-clés : Energy  Consumption  Refrigeration  plant  Modelling  Building  Ice  rink Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A transient model of airflow and heat transfer in an indoor ice rink and a quasi-steady model of its refrigeration system have been coupled and used to simulate their response to the time dependent ambient conditions and operating schedule for a typical meteorological year. The results for two different cases show that it is possible to reduce significantly the time of operation of the compressors and the energy consumption of the refrigeration system by simultaneously reducing the ceiling emissivity and increasing the secondary coolant temperature without affecting the quality of the ice. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001702

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