Dépouillements

Dielectric properties of liquid refrigerants / A.P.C. Ribeiro in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 393-401 Titre : Dielectric properties of liquid refrigerants : Facts and trends Titre original : Propriétés diélectriques des frigorigènes liquides : données et tendances Type de document : texte imprimé Auteurs : A.P.C. Ribeiro, Auteur ; C.A. Nieto de Castro, Auteur Année de publication : 2011 Article en page(s) : pp. 393-401 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Debye  temperature  Dielectric  constant  Electric  property  HFC  Thermodynamic  property  -  viscosity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper we analyse the situation for the dielectric properties of the refrigerants, from the experimental and theoretical point of view, based on more than one decade of research of our group. Examples of the predictive power of simple models will illustrate the existing tools for electrical permittivity and dipole moment prediction and correlation. The relation of Báron and Buep was analysed and extended to include the effects of pressure variation. Analogies between the Vedam equation and rough hard-sphere theory of transport properties were encountered and discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002677 [article] Dielectric properties of liquid refrigerants = Propriétés diélectriques des frigorigènes liquides : données et tendances : Facts and trends [texte imprimé] / A.P.C. Ribeiro, Auteur ; C.A. Nieto de Castro, Auteur . - 2011 . - pp. 393-401. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 393-401 Mots-clés : Debye  temperature  Dielectric  constant  Electric  property  HFC  Thermodynamic  property  -  viscosity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper we analyse the situation for the dielectric properties of the refrigerants, from the experimental and theoretical point of view, based on more than one decade of research of our group. Examples of the predictive power of simple models will illustrate the existing tools for electrical permittivity and dipole moment prediction and correlation. The relation of Báron and Buep was analysed and extended to include the effects of pressure variation. Analogies between the Vedam equation and rough hard-sphere theory of transport properties were encountered and discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002677

Refrigerant injection for heat pumping/air conditioning systems: Literature review and challenges discussions / Xing Xu in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 402-415 Titre : Refrigerant injection for heat pumping/air conditioning systems: Literature review and challenges discussions Titre original : Injection du frigorigène dans les systèmes à pompe à chaleur et de conditionnement d'air : passage en revue de la littérature et discussion sur les défis Type de document : texte imprimé Auteurs : Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2011 Article en page(s) : pp. 402-415 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Liquid  Vapor  Separation  Injection  Tank  Heat  exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper reviews the major research on refrigerant injection techniques in detail. Liquid and vapor refrigerant injection techniques are discussed and compared. The current research on refrigerant injection techniques falls into two categories: system level research and component level research. The system level research is focused on low ambient temperature heating, heat pump water heating, high ambient temperature cooling, cycle comparison, and control strategy development. Internal heat exchanger and flash tank cycles are the two typical cycles for refrigerant injection. These two cycles are discussed and compared in detail. The component level research is focused on employing different types of compressors, variable speed compressors, the injection process, and the flash tank. Different types of compressors employing refrigerant injection are presented. Based on the literature study, the potential future research directions are presented and discussed. The flash tank cycle control strategy and refrigerant charge management strategy are worth further research efforts. Compressor design can be improved in order to optimize the performance with refrigerant injection. The appropriate design of flash tanks plays a vital role in achieving appropriate two-phase flow patterns in the flash tank. Computational Fluid Dynamics (CFD) modeling can be a useful tool to facilitate the design of the flash tank. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002239 [article] Refrigerant injection for heat pumping/air conditioning systems: Literature review and challenges discussions = Injection du frigorigène dans les systèmes à pompe à chaleur et de conditionnement d'air : passage en revue de la littérature et discussion sur les défis [texte imprimé] / Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2011 . - pp. 402-415. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 402-415 Mots-clés : Liquid  Vapor  Separation  Injection  Tank  Heat  exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper reviews the major research on refrigerant injection techniques in detail. Liquid and vapor refrigerant injection techniques are discussed and compared. The current research on refrigerant injection techniques falls into two categories: system level research and component level research. The system level research is focused on low ambient temperature heating, heat pump water heating, high ambient temperature cooling, cycle comparison, and control strategy development. Internal heat exchanger and flash tank cycles are the two typical cycles for refrigerant injection. These two cycles are discussed and compared in detail. The component level research is focused on employing different types of compressors, variable speed compressors, the injection process, and the flash tank. Different types of compressors employing refrigerant injection are presented. Based on the literature study, the potential future research directions are presented and discussed. The flash tank cycle control strategy and refrigerant charge management strategy are worth further research efforts. Compressor design can be improved in order to optimize the performance with refrigerant injection. The appropriate design of flash tanks plays a vital role in achieving appropriate two-phase flow patterns in the flash tank. Computational Fluid Dynamics (CFD) modeling can be a useful tool to facilitate the design of the flash tank. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002239

Studies on the heating capacity control of a multi-type heat pump system applying a multi-input multi-output (MIMO) method / Il Hwan Lee in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 416-428 Titre : Studies on the heating capacity control of a multi-type heat pump system applying a multi-input multi-output (MIMO) method Titre original : Etudes sur la régulation de la puissance thermique d'un système à pompe à chaleur de type multiple employant une méthode comportant plusieurs grandeurs d'entrée et de sortie Type de document : texte imprimé Auteurs : Il Hwan Lee, Auteur ; Jong Won Choi, Auteur ; Min Soo Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 416-428 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Capacity  control  Multi-input  Multi-output  Heat  pump  System  Control  Variable  Integral Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes a method to control capacity of a multi-type heat pump system. Because indoor units are interconnected, alteration of the heating or cooling setting of one indoor unit can influence the performance of the other indoor units. Proportional-integral (PI) controllers were used to assess system performance, and the PI controllers’ gain values were optimized by using a genetic algorithm. A system model was established following a system identification optimization process, and a pseudo random binary sequence was selected as the system identification input signal. A multi-input multi-output (MIMO) controller was more effective in reducing such cross-coupling effects than a single-input single-output (SISO) controller. The temperature at the secondary fluid outlet in the condenser and the saturation pressure at the evaporator were selected as the control variables in the MIMO controller. The experimental results showed that an optimized MIMO controller could reduce overshoot by up to 40% compared with the results using a SISO controller. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002173 [article] Studies on the heating capacity control of a multi-type heat pump system applying a multi-input multi-output (MIMO) method = Etudes sur la régulation de la puissance thermique d'un système à pompe à chaleur de type multiple employant une méthode comportant plusieurs grandeurs d'entrée et de sortie [texte imprimé] / Il Hwan Lee, Auteur ; Jong Won Choi, Auteur ; Min Soo Kim, Auteur . - 2011 . - pp. 416-428. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 416-428 Mots-clés : Capacity  control  Multi-input  Multi-output  Heat  pump  System  Control  Variable  Integral Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes a method to control capacity of a multi-type heat pump system. Because indoor units are interconnected, alteration of the heating or cooling setting of one indoor unit can influence the performance of the other indoor units. Proportional-integral (PI) controllers were used to assess system performance, and the PI controllers’ gain values were optimized by using a genetic algorithm. A system model was established following a system identification optimization process, and a pseudo random binary sequence was selected as the system identification input signal. A multi-input multi-output (MIMO) controller was more effective in reducing such cross-coupling effects than a single-input single-output (SISO) controller. The temperature at the secondary fluid outlet in the condenser and the saturation pressure at the evaporator were selected as the control variables in the MIMO controller. The experimental results showed that an optimized MIMO controller could reduce overshoot by up to 40% compared with the results using a SISO controller. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002173

Numerical study on the steady state and transient performance of a multi-type heat pump system / Jong Won Choi in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 429-443 Titre : Numerical study on the steady state and transient performance of a multi-type heat pump system Titre original : Etude numérique sur le régime permanent et la performance en régime transitoire d’un système à pompe à chaleur polyvalent Type de document : texte imprimé Auteurs : Jong Won Choi, Auteur ; Gilbong Lee, Auteur ; Min Soo Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 429-443 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  System-multi-type  Heat  exchanger  Steady-state  Transient-state  Discharge-superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Numerical methods are provided to analyze dynamic characteristics as well as steady-state performance of a multi-type heat pump system. Lumped parameter method was applied to simulate the compressor and expansion device. Additionally, fully distributed method was used for analyzing the condenser and evaporators. The transient terms in the governing equations for heat exchangers were solved adopting the wave equation solutions. The simulation results predict the steady-state performance of a heat pump system with the deviation of ±10%. The transient simulation showed satisfactory responses of temperatures and pressures for various compressor speeds or expansion valve openings. From the results, it was shown that the operating conditions of secondary fluid of one indoor unit had minor influence on the performance of the other unit, while opening of expansion valve affected the transient responses of both evaporators significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002331 [article] Numerical study on the steady state and transient performance of a multi-type heat pump system = Etude numérique sur le régime permanent et la performance en régime transitoire d’un système à pompe à chaleur polyvalent [texte imprimé] / Jong Won Choi, Auteur ; Gilbong Lee, Auteur ; Min Soo Kim, Auteur . - 2011 . - pp. 429-443. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 429-443 Mots-clés : Heat  pump  System-multi-type  Heat  exchanger  Steady-state  Transient-state  Discharge-superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Numerical methods are provided to analyze dynamic characteristics as well as steady-state performance of a multi-type heat pump system. Lumped parameter method was applied to simulate the compressor and expansion device. Additionally, fully distributed method was used for analyzing the condenser and evaporators. The transient terms in the governing equations for heat exchangers were solved adopting the wave equation solutions. The simulation results predict the steady-state performance of a heat pump system with the deviation of ±10%. The transient simulation showed satisfactory responses of temperatures and pressures for various compressor speeds or expansion valve openings. From the results, it was shown that the operating conditions of secondary fluid of one indoor unit had minor influence on the performance of the other unit, while opening of expansion valve affected the transient responses of both evaporators significantly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002331

Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection / Jaehyeok Heo in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 444-453 Titre : Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection Titre original : Comparaison de la performance en mode chauffage des pompes à chaleur air-eau utilisant diffàrents types d'injection de frigorigàne Type de document : texte imprimé Auteurs : Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Changhyun Baek, Auteur Année de publication : 2011 Article en page(s) : pp. 444-453 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Two-stage  System  injection  Performance-heating Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance degradation of air-source heat pumps cannot be avoided when they operate at both very low and high ambient temperatures. The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. This study measured the heating performance of air-source heat pumps in which novel vapor injection techniques of a combined flash tank and sub-cooler (FTSC) cycle and a double expansion sub-cooler (DESC) cycle were applied. The performance of these cycles was compared with that of a flash tank (FT) and a sub-cooler (SC) cycle. The average heating capacities of the FT, FTSC, and DESC cycles were higher by 14.4%, 6.0%, and 3.8%, respectively, relative to that of the SC cycle, but the average COPs for the respective cycle options were very similar. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002318 [article] Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection = Comparaison de la performance en mode chauffage des pompes à chaleur air-eau utilisant diffàrents types d'injection de frigorigàne [texte imprimé] / Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Changhyun Baek, Auteur . - 2011 . - pp. 444-453. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 444-453 Mots-clés : Heat  pump  Two-stage  System  injection  Performance-heating Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance degradation of air-source heat pumps cannot be avoided when they operate at both very low and high ambient temperatures. The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. This study measured the heating performance of air-source heat pumps in which novel vapor injection techniques of a combined flash tank and sub-cooler (FTSC) cycle and a double expansion sub-cooler (DESC) cycle were applied. The performance of these cycles was compared with that of a flash tank (FT) and a sub-cooler (SC) cycle. The average heating capacities of the FT, FTSC, and DESC cycles were higher by 14.4%, 6.0%, and 3.8%, respectively, relative to that of the SC cycle, but the average COPs for the respective cycle options were very similar. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002318

Experimental investigation of the cooling performance of a ground source heat pump system in Denizli, Turkey / Rasim Karabacak in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 454-465 Titre : Experimental investigation of the cooling performance of a ground source heat pump system in Denizli, Turkey Titre original : Etude expérimentale sur la performance en refroidissement d'un système avec pompe à chaleur sol-eau Type de document : texte imprimé Auteurs : Rasim Karabacak, Auteur ; Şengül Güven Acar, Auteur ; Halil Kumsar, Auteur Année de publication : 2011 Article en page(s) : pp. 454-465 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Ground  source  Heat  pump  Heat  exchanger  Borehole  Ground  Thermal  conductivity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The ground source heat pump system (GSHP) is installed at PamukkaleUniversity in Denizli, Turkey. The U-bend ground heat exchanger pipe length of 225 m was buried in soil at 110 m depth. In the 2008 cooling season, performance coefficients of the heat pump and the system were determined in the range of 3.1–4.8 and 2.1–3.1, respectively. The values of solar radiation, external temperature, relative humidity and wind speed were measured continuously. The relations of performance coefficients of ground source heat pump according to the meteorological data including solar radiation, wind speed, relative humidity and external temperature with this experiment were revealed exactly. The results of this study fulfil the lack in the literature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002380 [article] Experimental investigation of the cooling performance of a ground source heat pump system in Denizli, Turkey = Etude expérimentale sur la performance en refroidissement d'un système avec pompe à chaleur sol-eau [texte imprimé] / Rasim Karabacak, Auteur ; Şengül Güven Acar, Auteur ; Halil Kumsar, Auteur . - 2011 . - pp. 454-465. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 454-465 Mots-clés : Ground  source  Heat  pump  Heat  exchanger  Borehole  Ground  Thermal  conductivity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The ground source heat pump system (GSHP) is installed at PamukkaleUniversity in Denizli, Turkey. The U-bend ground heat exchanger pipe length of 225 m was buried in soil at 110 m depth. In the 2008 cooling season, performance coefficients of the heat pump and the system were determined in the range of 3.1–4.8 and 2.1–3.1, respectively. The values of solar radiation, external temperature, relative humidity and wind speed were measured continuously. The relations of performance coefficients of ground source heat pump according to the meteorological data including solar radiation, wind speed, relative humidity and external temperature with this experiment were revealed exactly. The results of this study fulfil the lack in the literature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002380

Investigation of dry ice blockage in an ultra-low temperature cascade refrigeration system using CO2 as a working fluid / Hiroshi Yamaguchi in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 466-475 Titre : Investigation of dry ice blockage in an ultra-low temperature cascade refrigeration system using CO2 as a working fluid Titre original : Etude sur le blocage par la neige carbonique d'un système frigorifique en cascade à très basse température utilisant le CO2 comme fluide actif Type de document : texte imprimé Auteurs : Hiroshi Yamaguchi, Auteur ; Niu, Xiao-Dong, Auteur ; Kenichi Sekimoto, Auteur Année de publication : 2011 Article en page(s) : pp. 466-475 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Dry  ice  Solid-gas  flow  Ultra-low  temperature  Refrigeration  system-cascade Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Dry ice blockage in a CO2-solid–gas-flow-based ultra-low temperature cascade refrigeration system is investigated experimentally by a visualization test and a system study of the liquid CO2 blew into an expansion tube through a Throttle needle valve. The visualization test shows that dry ice sedimentation occurs in low flow velocity and the dry ice formation makes the heat transfer behavior of CO2 complicated. The sedimentation also occurs at low condensation temperature and low heating power input. Based on the present investigation, it is found that the present ultra-low temperature cascade refrigeration system is better to work at heating power input above 900 W and condensation temperature above −20 °C. At suitable operating condition, the present ultra-low temperature cascade refrigeration system has been shown the capability of achieving ultra-low temperature −62 °C continuously and stably. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002616 [article] Investigation of dry ice blockage in an ultra-low temperature cascade refrigeration system using CO2 as a working fluid = Etude sur le blocage par la neige carbonique d'un système frigorifique en cascade à très basse température utilisant le CO2 comme fluide actif [texte imprimé] / Hiroshi Yamaguchi, Auteur ; Niu, Xiao-Dong, Auteur ; Kenichi Sekimoto, Auteur . - 2011 . - pp. 466-475. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 466-475 Mots-clés : Dry  ice  Solid-gas  flow  Ultra-low  temperature  Refrigeration  system-cascade Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Dry ice blockage in a CO2-solid–gas-flow-based ultra-low temperature cascade refrigeration system is investigated experimentally by a visualization test and a system study of the liquid CO2 blew into an expansion tube through a Throttle needle valve. The visualization test shows that dry ice sedimentation occurs in low flow velocity and the dry ice formation makes the heat transfer behavior of CO2 complicated. The sedimentation also occurs at low condensation temperature and low heating power input. Based on the present investigation, it is found that the present ultra-low temperature cascade refrigeration system is better to work at heating power input above 900 W and condensation temperature above −20 °C. At suitable operating condition, the present ultra-low temperature cascade refrigeration system has been shown the capability of achieving ultra-low temperature −62 °C continuously and stably. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002616

Experimental investigations on adiabatic capillary tube in a transcritical CO2 heat pump system for simultaneous water cooling and heating / Neeraj Agrawal in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 476-483 Titre : Experimental investigations on adiabatic capillary tube in a transcritical CO2 heat pump system for simultaneous water cooling and heating Titre original : Etudes expérimentales sur le tube capillaire adiabatique d'un système à pompe à chaleur au CO2 transcritique utilisé pour le refroidissement et le chauffage simultanés d'eau Type de document : texte imprimé Auteurs : Neeraj Agrawal, Auteur ; Souvik Bhattacharyya, Auteur Année de publication : 2011 Article en page(s) : pp. 476-483 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Capillary  Heat  pump  Refrigerant  charge  Compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental studies for a prototype CO2 heat pump system employing capillary tube as an expansion device for simultaneous water heating and cooling have been presented. Tests were conducted with two stainless steel capillary tubes having specifications of ID = 1.71 mm, L = 2.95 m, εc = 3.92 μm and ID = 1.42 mm, L = 1.0 m, εc = 5.76 μm. System performance is significantly influenced by gas cooler water inlet temperature, whereas the effect of water flow rate on system performance is modest. An optimum charge is also recorded at which the system yields the best COP with a capillary tube. Performance deterioration is more severe at undercharged condition than at overcharged condition. Comparisons of test data with simulated results show that maximum deviation in mass flow rate of refrigerant is about ±10% and the flow characteristics exhibit a reasonably good match with the test data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002227 [article] Experimental investigations on adiabatic capillary tube in a transcritical CO2 heat pump system for simultaneous water cooling and heating = Etudes expérimentales sur le tube capillaire adiabatique d'un système à pompe à chaleur au CO2 transcritique utilisé pour le refroidissement et le chauffage simultanés d'eau [texte imprimé] / Neeraj Agrawal, Auteur ; Souvik Bhattacharyya, Auteur . - 2011 . - pp. 476-483. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 476-483 Mots-clés : Capillary  Heat  pump  Refrigerant  charge  Compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experimental studies for a prototype CO2 heat pump system employing capillary tube as an expansion device for simultaneous water heating and cooling have been presented. Tests were conducted with two stainless steel capillary tubes having specifications of ID = 1.71 mm, L = 2.95 m, εc = 3.92 μm and ID = 1.42 mm, L = 1.0 m, εc = 5.76 μm. System performance is significantly influenced by gas cooler water inlet temperature, whereas the effect of water flow rate on system performance is modest. An optimum charge is also recorded at which the system yields the best COP with a capillary tube. Performance deterioration is more severe at undercharged condition than at overcharged condition. Comparisons of test data with simulated results show that maximum deviation in mass flow rate of refrigerant is about ±10% and the flow characteristics exhibit a reasonably good match with the test data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002227

Air-side heat transfer and pressure drop characteristics of accelerated flow evaporators / Paulo J. Waltrich in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 484-497 Titre : Air-side heat transfer and pressure drop characteristics of accelerated flow evaporators Titre original : Evaporateurs à écoulement accéléré: transfert de chaleur côté air et caractéristiques de la chute de pression Type de document : texte imprimé Auteurs : Paulo J. Waltrich, Auteur ; Jader R. Barbosa Jr., Auteur ; Christian J.L. Hermes, Auteur Année de publication : 2011 Article en page(s) : pp. 484-497 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Evaporator  Heat  exchanger  Heat  transfer  coefficient  Enhancement  Household  refrigerator  Modeling  Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : We investigate an alternative tube-fin evaporator design (accelerated flow evaporator, AFE) in which the air-side local heat transfer coefficient is increased due to a progressive reduction of the free-flow area. For a given heat transfer rate, this enhancement is expected to partially compensate the decrease in surface area, which reduces the evaporator material cost. The air-side thermal-hydraulic behavior of nine AFEs was determined experimentally, and a calculation method that relies on j and f correlations for plain tube-fin heat exchangers and on mass and momentum balances has been proposed. The method enables the calculation of the by-pass fraction associated with the air stream through the clearance between the tube bank and the outer edge of the fins. The agreement between the model, which introduces no additional fitting parameters, and the experiments is within ±10% for all heat transfer data and ±15% for the majority of the pressure drop data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000201X [article] Air-side heat transfer and pressure drop characteristics of accelerated flow evaporators = Evaporateurs à écoulement accéléré: transfert de chaleur côté air et caractéristiques de la chute de pression [texte imprimé] / Paulo J. Waltrich, Auteur ; Jader R. Barbosa Jr., Auteur ; Christian J.L. Hermes, Auteur . - 2011 . - pp. 484-497. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 484-497 Mots-clés : Evaporator  Heat  exchanger  Heat  transfer  coefficient  Enhancement  Household  refrigerator  Modeling  Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : We investigate an alternative tube-fin evaporator design (accelerated flow evaporator, AFE) in which the air-side local heat transfer coefficient is increased due to a progressive reduction of the free-flow area. For a given heat transfer rate, this enhancement is expected to partially compensate the decrease in surface area, which reduces the evaporator material cost. The air-side thermal-hydraulic behavior of nine AFEs was determined experimentally, and a calculation method that relies on j and f correlations for plain tube-fin heat exchangers and on mass and momentum balances has been proposed. The method enables the calculation of the by-pass fraction associated with the air stream through the clearance between the tube bank and the outer edge of the fins. The agreement between the model, which introduces no additional fitting parameters, and the experiments is within ±10% for all heat transfer data and ±15% for the majority of the pressure drop data. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000201X

Effect of Al2O3 nanolubricant on R134a pool boiling heat transfer / M.A. Kedzierski in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 498-508 Titre : Effect of Al2O3 nanolubricant on R134a pool boiling heat transfer Titre original : L’effet du nanolubrifiant Al2O3 sur le transfert de chaleur lors de l’ébullition libre de R134a Type de document : texte imprimé Auteurs : M.A. Kedzierski, Auteur Année de publication : 2011 Article en page(s) : pp. 498-508 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Boiling  Heat  flux  Lubricant  Particle  Refrigerant  R134a Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper quantifies the influence of Al2O3 nanoparticles on the pool-boiling performance of R134a/polyolester mixtures on a roughened, horizontal, flat surface. The nanoparticles enhanced the boiling heat transfer relative to that for R134a/polyolester mixtures without nanoparticles for the three lubricant mass fractions that were tested. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) as large as 400% for the lowest heat flux. The average heat flux improvement for heat fluxes less than 40 kW m−2 was approximately 105%, 49%, and 155% for the 0.5%, the 1%, and the 2% mass fractions, respectively. A semi-empirical model was developed to predict the boiling enhancement as caused by the interaction of the nanoparticles with the bubbles. The model suggests that small particle size and large nanoparticle volume fraction improve boiling enhancement. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002367 [article] Effect of Al2O3 nanolubricant on R134a pool boiling heat transfer = L’effet du nanolubrifiant Al2O3 sur le transfert de chaleur lors de l’ébullition libre de R134a [texte imprimé] / M.A. Kedzierski, Auteur . - 2011 . - pp. 498-508. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 498-508 Mots-clés : Boiling  Heat  flux  Lubricant  Particle  Refrigerant  R134a Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper quantifies the influence of Al2O3 nanoparticles on the pool-boiling performance of R134a/polyolester mixtures on a roughened, horizontal, flat surface. The nanoparticles enhanced the boiling heat transfer relative to that for R134a/polyolester mixtures without nanoparticles for the three lubricant mass fractions that were tested. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) as large as 400% for the lowest heat flux. The average heat flux improvement for heat fluxes less than 40 kW m−2 was approximately 105%, 49%, and 155% for the 0.5%, the 1%, and the 2% mass fractions, respectively. A semi-empirical model was developed to predict the boiling enhancement as caused by the interaction of the nanoparticles with the bubbles. The model suggests that small particle size and large nanoparticle volume fraction improve boiling enhancement. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002367

Influence of oil on nucleate pool boiling heat transfer of refrigerant on metal foam covers / Yu Zhu in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 509-517 Titre : Influence of oil on nucleate pool boiling heat transfer of refrigerant on metal foam covers Titre original : Influence de l'huile sur le transfert de chaleur lors de l'ébullition libre nucléée d'un frigorigène sur des mousses métalliques Type de document : texte imprimé Auteurs : Yu Zhu, Auteur ; Haitao Hu, Auteur ; Guoliang Ding, Auteur Année de publication : 2011 Article en page(s) : pp. 509-517 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Correlation  Foam  Metal  Oil  Pool  boiling  Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Nucleate pool boiling heat transfer characteristics of refrigerant/oil mixture on metal foam covers were experimentally investigated. The refrigerant is R113, and the oil is VG68. The copper foams, having ppi (pores per inch) of 10 and 20, porosity from 90% to 98%, and thickness of 5 mm, are selected in this study. Experimental conditions include a saturation pressure of 101 kPa, oil concentrations from 0 to 5%, and heat fluxes from 0 to 80 kW m−2. The experimental results indicate that the nucleate pool boiling heat transfer coefficient on copper foam covers is larger than that on flat heated surface by a maximum of 160% under the present experimental conditions; the presence of oil deteriorates the nucleate pool boiling heat transfer on copper foam covers by a maximum of 15% under the present experimental conditions, and the deterioration of oil on nucleate pool boiling heat transfer on copper foam covers is lower than that on a flat heated surface. A correlation for predicting the nucleate pool boiling heat transfer coefficient of refrigerant/oil mixture on copper foam cover is developed, and it agrees with 95% of the experimental data within a deviation of ±20%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002355 [article] Influence of oil on nucleate pool boiling heat transfer of refrigerant on metal foam covers = Influence de l'huile sur le transfert de chaleur lors de l'ébullition libre nucléée d'un frigorigène sur des mousses métalliques [texte imprimé] / Yu Zhu, Auteur ; Haitao Hu, Auteur ; Guoliang Ding, Auteur . - 2011 . - pp. 509-517. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 509-517 Mots-clés : Correlation  Foam  Metal  Oil  Pool  boiling  Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Nucleate pool boiling heat transfer characteristics of refrigerant/oil mixture on metal foam covers were experimentally investigated. The refrigerant is R113, and the oil is VG68. The copper foams, having ppi (pores per inch) of 10 and 20, porosity from 90% to 98%, and thickness of 5 mm, are selected in this study. Experimental conditions include a saturation pressure of 101 kPa, oil concentrations from 0 to 5%, and heat fluxes from 0 to 80 kW m−2. The experimental results indicate that the nucleate pool boiling heat transfer coefficient on copper foam covers is larger than that on flat heated surface by a maximum of 160% under the present experimental conditions; the presence of oil deteriorates the nucleate pool boiling heat transfer on copper foam covers by a maximum of 15% under the present experimental conditions, and the deterioration of oil on nucleate pool boiling heat transfer on copper foam covers is lower than that on a flat heated surface. A correlation for predicting the nucleate pool boiling heat transfer coefficient of refrigerant/oil mixture on copper foam cover is developed, and it agrees with 95% of the experimental data within a deviation of ±20%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002355

Stationary analysis of a solar LiBr–H2O absorption refrigeration system / C. Monné in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 518-526 Titre : Stationary analysis of a solar LiBr–H2O absorption refrigeration system Titre original : Analyse d'un système frigorifique à absorption au LiBr/H2O solaire Type de document : texte imprimé Auteurs : C. Monné, Auteur ; S. Alonso, Auteur ; F. Palacín, Auteur Année de publication : 2011 Article en page(s) : pp. 518-526 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorption  Solar  energy  Cooling  Energy  saving Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present work describes the operation of a solar powered absorption cooling system. This solar cooling installation was designed in order to resolve the overheating problems of an existing solar field. Since 2007 the system was completely monitored to be able to analyze it. The work evaluates the performance of this kind of installation as well as the behavior of the absorption chiller focusing on its steady state operation. This methodology was applied to the monitoring results of the installation in order to compare the first two years of operation of the system. It is concluded that the performance of the chiller showed better values in 2007 because the heat rejection temperature and the outdoor temperature were more favorable than in 2008. Nevertheless, the coefficient of performance (COP) achieved acceptable values in both periods, over 0.5, being the average chilling capacity between 3.6 kW and 5.8 kW. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002707 [article] Stationary analysis of a solar LiBr–H2O absorption refrigeration system = Analyse d'un système frigorifique à absorption au LiBr/H2O solaire [texte imprimé] / C. Monné, Auteur ; S. Alonso, Auteur ; F. Palacín, Auteur . - 2011 . - pp. 518-526. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 518-526 Mots-clés : Absorption  Solar  energy  Cooling  Energy  saving Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present work describes the operation of a solar powered absorption cooling system. This solar cooling installation was designed in order to resolve the overheating problems of an existing solar field. Since 2007 the system was completely monitored to be able to analyze it. The work evaluates the performance of this kind of installation as well as the behavior of the absorption chiller focusing on its steady state operation. This methodology was applied to the monitoring results of the installation in order to compare the first two years of operation of the system. It is concluded that the performance of the chiller showed better values in 2007 because the heat rejection temperature and the outdoor temperature were more favorable than in 2008. Nevertheless, the coefficient of performance (COP) achieved acceptable values in both periods, over 0.5, being the average chilling capacity between 3.6 kW and 5.8 kW. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002707

Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”, Part I: Model description and validation / Y.T. Ge in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 527-539 Titre : Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”, Part I: Model description and validation Titre original : Evaluation de la performance et conception optimale de systèmes frigorifiques pour supermarchés à l'aide du modèle ≪ SuperSim ≫. Partie I : description et validation du modèle Type de document : texte imprimé Auteurs : Y.T. Ge, Auteur ; S.A. Tassou, Auteur Année de publication : 2011 Article en page(s) : pp. 527-539 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Supermarket  Refrigeration  system  Energy  consumption  Modelling  Validation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Conventional supermarket refrigeration systems are responsible for considerable CO2 emissions due to high energy consumption and large quantities of refrigerant leakage. In the effort to conserve energy and reduce environmental impacts, an efficient design tool for the analysis, evaluation and comparison of the performance of alternative system designs and controls is required. This paper provides a description of the modelling procedure employed in the supermarket simulation model ‘SuperSim’ for the simulation of the performance of centralised vapour compression refrigeration systems and their interaction with the building envelope and HVAC systems. The model which has been validated against data from a supermarket has been used for the comparison of R404A and CO2 refrigeration systems and the optimisation of the performance of transcritical CO2 systems. These results are presented in Part II of the paper. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002719 [article] Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”, Part I: Model description and validation = Evaluation de la performance et conception optimale de systèmes frigorifiques pour supermarchés à l'aide du modèle ≪ SuperSim ≫. Partie I : description et validation du modèle [texte imprimé] / Y.T. Ge, Auteur ; S.A. Tassou, Auteur . - 2011 . - pp. 527-539. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 527-539 Mots-clés : Supermarket  Refrigeration  system  Energy  consumption  Modelling  Validation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Conventional supermarket refrigeration systems are responsible for considerable CO2 emissions due to high energy consumption and large quantities of refrigerant leakage. In the effort to conserve energy and reduce environmental impacts, an efficient design tool for the analysis, evaluation and comparison of the performance of alternative system designs and controls is required. This paper provides a description of the modelling procedure employed in the supermarket simulation model ‘SuperSim’ for the simulation of the performance of centralised vapour compression refrigeration systems and their interaction with the building envelope and HVAC systems. The model which has been validated against data from a supermarket has been used for the comparison of R404A and CO2 refrigeration systems and the optimisation of the performance of transcritical CO2 systems. These results are presented in Part II of the paper. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002719

Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”. Part II: Model applications / Y.T. Ge in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 540-549 Titre : Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”. Part II: Model applications Titre original : Evaluation de la performance et conception optimale de systèmes frigorifiques pour supermarchés à l'aide du modèle ≪ SuperSim ≫. Partie II : applications du modèle Type de document : texte imprimé Auteurs : Y.T. Ge, Auteur ; S.A. Tassou, Auteur Année de publication : 2011 Article en page(s) : pp. 540-549 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Supermarket  Model  Carbon  dioxide  R404A  Control  Comparison Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : As described in Part I, the supermarket simulation software “SuperSim” with its integrated refrigeration, building and HVAC system models, can be used to evaluate, compare and optimize alternative supermarket refrigeration systems. In Part II the model was used to evaluate and compare the performance of a CO2 booster refrigeration system with that of a conventional R404A multiplex system in a supermarket application. Floating head pressure control was implemented for both systems when they were in subcritical cycles. For the CO2 system, when the system was in transcritical cycle due to higher ambient air temperature, the head pressure was optimized through extensive thermodynamic cycle analysis as a function of ambient air temperature. The performance of the CO2 booster system in the supermarket was then simulated during a one year period and compared with that of the R404A system. As a result, the system performance will benefit from a lower ambient temperature and a sizeable heat recovery for the CO2 system. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=ana [...] [article] Performance evaluation and optimal design of supermarket refrigeration systems with supermarket model “SuperSim”. Part II: Model applications = Evaluation de la performance et conception optimale de systèmes frigorifiques pour supermarchés à l'aide du modèle ≪ SuperSim ≫. Partie II : applications du modèle [texte imprimé] / Y.T. Ge, Auteur ; S.A. Tassou, Auteur . - 2011 . - pp. 540-549. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 540-549 Mots-clés : Supermarket  Model  Carbon  dioxide  R404A  Control  Comparison Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : As described in Part I, the supermarket simulation software “SuperSim” with its integrated refrigeration, building and HVAC system models, can be used to evaluate, compare and optimize alternative supermarket refrigeration systems. In Part II the model was used to evaluate and compare the performance of a CO2 booster refrigeration system with that of a conventional R404A multiplex system in a supermarket application. Floating head pressure control was implemented for both systems when they were in subcritical cycles. For the CO2 system, when the system was in transcritical cycle due to higher ambient air temperature, the head pressure was optimized through extensive thermodynamic cycle analysis as a function of ambient air temperature. The performance of the CO2 booster system in the supermarket was then simulated during a one year period and compared with that of the R404A system. As a result, the system performance will benefit from a lower ambient temperature and a sizeable heat recovery for the CO2 system. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=ana [...]

Study on methods of measuring frost crystal dimensions/structure and frost scraping force using a scanning probe microscope / Koji Matsumoto in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 550-559 Titre : Study on methods of measuring frost crystal dimensions/structure and frost scraping force using a scanning probe microscope Titre original : Etude sur les méthodes utilisées pour mesurer les dimensions et la structure des cristaux de givre et la force de raclage du givre à l’aide d’un microscope à balayage Type de document : texte imprimé Auteurs : Koji Matsumoto, Auteur ; Yoshiaki Kenmotsu, Auteur ; Yoshikazu Teraoka, Auteur Année de publication : 2011 Article en page(s) : pp. 550-559 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Frost  formation  Adhesion  Sublimation  Structure Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Frosting on a cooling surface causes serious damage as well as economic losses. Therefore, it is necessary to clarify the mechanism of frosting on a cooling surface both scientifically and technologically. In addition, taking the size of frost crystals into account requires nano-micro-scale investigation. However, there have been few such studies. Thus, the focus of the present study is methods of measuring frost crystal dimensions/structure and frost scraping force in nano-micro-scale fields. In the present study, methods by which to measure frost crystal dimensions/structure, such as diameter, height, number of frost crystals, and interval between adjoining frost crystals, as well as the force required to scrape frost from a cooling surface using a scanning probe microscope (SPM) are proposed, and the effectiveness of these methods is investigated. With the exception of the frost crystal height, the feasibility of these measurements was demonstrated, and examples of the correlation of frost dimensions/structure and frost scraping force could are presented. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002343 [article] Study on methods of measuring frost crystal dimensions/structure and frost scraping force using a scanning probe microscope = Etude sur les méthodes utilisées pour mesurer les dimensions et la structure des cristaux de givre et la force de raclage du givre à l’aide d’un microscope à balayage [texte imprimé] / Koji Matsumoto, Auteur ; Yoshiaki Kenmotsu, Auteur ; Yoshikazu Teraoka, Auteur . - 2011 . - pp. 550-559. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 550-559 Mots-clés : Frost  formation  Adhesion  Sublimation  Structure Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Frosting on a cooling surface causes serious damage as well as economic losses. Therefore, it is necessary to clarify the mechanism of frosting on a cooling surface both scientifically and technologically. In addition, taking the size of frost crystals into account requires nano-micro-scale investigation. However, there have been few such studies. Thus, the focus of the present study is methods of measuring frost crystal dimensions/structure and frost scraping force in nano-micro-scale fields. In the present study, methods by which to measure frost crystal dimensions/structure, such as diameter, height, number of frost crystals, and interval between adjoining frost crystals, as well as the force required to scrape frost from a cooling surface using a scanning probe microscope (SPM) are proposed, and the effectiveness of these methods is investigated. With the exception of the frost crystal height, the feasibility of these measurements was demonstrated, and examples of the correlation of frost dimensions/structure and frost scraping force could are presented. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002343

Prediction of frost deposition on a horizontal circular cylinder under natural convection using artificial neural networks / Ali R. Tahavvor in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 560-566 Titre : Prediction of frost deposition on a horizontal circular cylinder under natural convection using artificial neural networks Titre original : Prévision de la déposition de givre sur un cylindre horizontal sous convection naturelle à l'aide de réseaux neuronaux Type de document : texte imprimé Auteurs : Ali R. Tahavvor, Auteur ; Mahmood Yaghoubi, Auteur Année de publication : 2011 Article en page(s) : pp. 560-566 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Neural  network  Frost  Free  convection  Horizontal  cylinder Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present work Artificial Neural Network is used to predict frost thickness and density around a cooled horizontal circular cylinder having constant surface temperature under natural convection for different ambient conditions. The database for ANN generated from the experimental measurements. In the present work a multilayer perceptron network is used and it is found that the back-propagation algorithm with Levenberg–Marquardt learning rule is the best choice to estimate frost growth due to accurate and faster training procedure. Experimental measurements are used for training and testing the ANN approach and comparison is performed among the soft programming ANN and experimental measurements. It is observed that ANN soft programming code can be used more efficiently to determine frost thickness and density around a cold horizontal cylinder. Based on the developed ANN wide range of frost formation over various cylinder diameters are determined and presented for various conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002379 [article] Prediction of frost deposition on a horizontal circular cylinder under natural convection using artificial neural networks = Prévision de la déposition de givre sur un cylindre horizontal sous convection naturelle à l'aide de réseaux neuronaux [texte imprimé] / Ali R. Tahavvor, Auteur ; Mahmood Yaghoubi, Auteur . - 2011 . - pp. 560-566. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 560-566 Mots-clés : Neural  network  Frost  Free  convection  Horizontal  cylinder Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present work Artificial Neural Network is used to predict frost thickness and density around a cooled horizontal circular cylinder having constant surface temperature under natural convection for different ambient conditions. The database for ANN generated from the experimental measurements. In the present work a multilayer perceptron network is used and it is found that the back-propagation algorithm with Levenberg–Marquardt learning rule is the best choice to estimate frost growth due to accurate and faster training procedure. Experimental measurements are used for training and testing the ANN approach and comparison is performed among the soft programming ANN and experimental measurements. It is observed that ANN soft programming code can be used more efficiently to determine frost thickness and density around a cold horizontal cylinder. Based on the developed ANN wide range of frost formation over various cylinder diameters are determined and presented for various conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002379

Performance optimization of an irreversible Carnot refrigerator with finite mass flow rate / Jianlin Yu in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 567-572 Titre : Performance optimization of an irreversible Carnot refrigerator with finite mass flow rate Titre original : Optimisation de la performance d’un réfrigérateur Carnot irréversible avec un débit massique fini Type de document : texte imprimé Auteurs : Jianlin Yu, Auteur ; Yuanyuan Zhou, Auteur ; Ying Liu, Auteur Année de publication : 2011 Article en page(s) : pp. 567-572 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carnot  Refrigerator  Irreversible  Thermodynamics  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present study develops a theoretical model for the optimization of an irreversible Carnot refrigerator subject to a constraint of finite mass flow rate, which includes internal as well as external irreversibilities. By introducing two dimensionless parameters as indicative of the mass flow rates for the refrigerator, the new model allows detailed analyses on the finite mass flow rate allocation problem of working fluids among the hot- and cold-side heat exchangers of Carnot refrigerators. The analytical solutions of the maximum coefficient of performance (COP) for irreversible Carnot refrigerators are obtained under the equivalent of the finite-flow rate constraint. Furthermore, the influences of major parameters on the maximum COP and the corresponding mass flow rate allocation are examined and shown by numerical examples. The obtained results may provide a theoretical guidance for the optimal design and operation of real refrigerators. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002483 [article] Performance optimization of an irreversible Carnot refrigerator with finite mass flow rate = Optimisation de la performance d’un réfrigérateur Carnot irréversible avec un débit massique fini [texte imprimé] / Jianlin Yu, Auteur ; Yuanyuan Zhou, Auteur ; Ying Liu, Auteur . - 2011 . - pp. 567-572. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 567-572 Mots-clés : Carnot  Refrigerator  Irreversible  Thermodynamics  Optimization Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The present study develops a theoretical model for the optimization of an irreversible Carnot refrigerator subject to a constraint of finite mass flow rate, which includes internal as well as external irreversibilities. By introducing two dimensionless parameters as indicative of the mass flow rates for the refrigerator, the new model allows detailed analyses on the finite mass flow rate allocation problem of working fluids among the hot- and cold-side heat exchangers of Carnot refrigerators. The analytical solutions of the maximum coefficient of performance (COP) for irreversible Carnot refrigerators are obtained under the equivalent of the finite-flow rate constraint. Furthermore, the influences of major parameters on the maximum COP and the corresponding mass flow rate allocation are examined and shown by numerical examples. The obtained results may provide a theoretical guidance for the optimal design and operation of real refrigerators. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002483

Experimental and numerical modelling comparison of thermal performance of expanded polystyrene and corrugated plastic packaging for fresh fish / Björn Margeirsson in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 573-585 Titre : Experimental and numerical modelling comparison of thermal performance of expanded polystyrene and corrugated plastic packaging for fresh fish Titre original : Comparaison expérimentale et numérique de la modélisation de la performance thermique du polystyrène expansé et de la matière plastique ondulée utilisés comme emballage du poisson frais Type de document : texte imprimé Auteurs : Björn Margeirsson, Auteur ; Radovan Gospavic, Auteur ; Halldór Pálsson, Auteur Année de publication : 2011 Article en page(s) : pp. 573-585 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chilled  food  Temperature  variation  Insulation  Packaging  Heat  transfer  model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experiments were carried out to compare the thermal performance of wholesale fresh fish boxes made of corrugated plastic (CP) and expanded polystyrene (EPS). Free standing boxes containing whole, fresh fillets were exposed to dynamic thermal loads. The chilling effect of frozen ice packs was studied by including them in some of the boxes. The frozen ice packs proved efficient for protecting fresh fish fillets against temperature abuse. Furthermore, the results show that the insulating performance of EPS is significantly better than the insulating capacity of CP. Maximum fish temperature of 16.1 °C (CP) and 11.0 °C (EPS) were recorded inside the thermally abused boxes without ice packs, initially at 1.9 to 2.1 °C and stored for 6.1 h at a mean ambient temperature of 19.4 °C. The fish temperature distributions during thermal abuse were studied with a numerical model for both packaging types, applying effective thermal properties of the sandwich-structured CP box. The purpose of the model was to cost effectively improve the packaging design. A satisfactory agreement between numerical results and experimental results was obtained. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002252 [article] Experimental and numerical modelling comparison of thermal performance of expanded polystyrene and corrugated plastic packaging for fresh fish = Comparaison expérimentale et numérique de la modélisation de la performance thermique du polystyrène expansé et de la matière plastique ondulée utilisés comme emballage du poisson frais [texte imprimé] / Björn Margeirsson, Auteur ; Radovan Gospavic, Auteur ; Halldór Pálsson, Auteur . - 2011 . - pp. 573-585. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 573-585 Mots-clés : Chilled  food  Temperature  variation  Insulation  Packaging  Heat  transfer  model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Experiments were carried out to compare the thermal performance of wholesale fresh fish boxes made of corrugated plastic (CP) and expanded polystyrene (EPS). Free standing boxes containing whole, fresh fillets were exposed to dynamic thermal loads. The chilling effect of frozen ice packs was studied by including them in some of the boxes. The frozen ice packs proved efficient for protecting fresh fish fillets against temperature abuse. Furthermore, the results show that the insulating performance of EPS is significantly better than the insulating capacity of CP. Maximum fish temperature of 16.1 °C (CP) and 11.0 °C (EPS) were recorded inside the thermally abused boxes without ice packs, initially at 1.9 to 2.1 °C and stored for 6.1 h at a mean ambient temperature of 19.4 °C. The fish temperature distributions during thermal abuse were studied with a numerical model for both packaging types, applying effective thermal properties of the sandwich-structured CP box. The purpose of the model was to cost effectively improve the packaging design. A satisfactory agreement between numerical results and experimental results was obtained. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002252

Important sensors for chiller fault detection and diagnosis (FDD) from the perspective of feature selection and machine learning / H. Han in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 586-599 Titre : Important sensors for chiller fault detection and diagnosis (FDD) from the perspective of feature selection and machine learning Titre original : Capteurs importants pour la détection et le diagnostic d'anomalies des refroidisseurs du point de vue des choix des caractéristiques et des connaissances du système Type de document : texte imprimé Auteurs : H. Han, Auteur ; B. Gu, Auteur ; T. Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 586-599 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Sensor  Chiller  Compression  system  Detection  Genetic  Fault Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The benefits of applying automated fault detection and diagnosis (AFDD) to chillers include less expensive repairs, timely maintenance, and shorter downtimes. This study employs feature selection (FS) techniques, such as mutual-information-based filter and genetic-algorithm-based wrapper, to help search for the important sensors in data driven chiller FDD applications, so as to improve FDD performance while saving initial sensor cost. The ‘one-against-one’ multi-class support vector machine (SVM) is adopted as a FDD tool. The results show that the eight features/sensors, centered around the core refrigeration cycle and selected by the GA-SVM wrapper from the original 64 features, outperform the other three feature subsets by the GA-LDA (linear discriminant analysis) wrapper, with an overall classification correct rate (CR) as high as 99.53% for the 4000 test samples randomly covering the normal and seven typical faulty modes. The CRs for the four cases with FS are all higher than that without FS (97.45%) and the test time is much less, about 28–36%. The FDD performance for normal or each of the faulty modes is also evaluated in details in terms of hit rate (HR) and false alarm rate (FAR). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001830 [article] Important sensors for chiller fault detection and diagnosis (FDD) from the perspective of feature selection and machine learning = Capteurs importants pour la détection et le diagnostic d'anomalies des refroidisseurs du point de vue des choix des caractéristiques et des connaissances du système [texte imprimé] / H. Han, Auteur ; B. Gu, Auteur ; T. Wang, Auteur . - 2011 . - pp. 586-599. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 586-599 Mots-clés : Sensor  Chiller  Compression  system  Detection  Genetic  Fault Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The benefits of applying automated fault detection and diagnosis (AFDD) to chillers include less expensive repairs, timely maintenance, and shorter downtimes. This study employs feature selection (FS) techniques, such as mutual-information-based filter and genetic-algorithm-based wrapper, to help search for the important sensors in data driven chiller FDD applications, so as to improve FDD performance while saving initial sensor cost. The ‘one-against-one’ multi-class support vector machine (SVM) is adopted as a FDD tool. The results show that the eight features/sensors, centered around the core refrigeration cycle and selected by the GA-SVM wrapper from the original 64 features, outperform the other three feature subsets by the GA-LDA (linear discriminant analysis) wrapper, with an overall classification correct rate (CR) as high as 99.53% for the 4000 test samples randomly covering the normal and seven typical faulty modes. The CRs for the four cases with FS are all higher than that without FS (97.45%) and the test time is much less, about 28–36%. The FDD performance for normal or each of the faulty modes is also evaluated in details in terms of hit rate (HR) and false alarm rate (FAR). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001830

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