Documents disponibles écrits par cet auteur

Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles / Nicholas Fernandez in International journal of refrigeration, Vol. 33 N° 3 (Mai 2010) 

Public ISBD [article]  in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 635-644 Titre : Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles Titre original : Comparaison de la performance d'un système de chauffage d'eau à pompe à chaleur au CO2 et celle d'un cycle de base et celles de deux cycles au COP élevé Type de document : texte imprimé Auteurs : Nicholas Fernandez, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2010 Article en page(s) : pp. 635-644 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Air–water  Carbon  dioxide  Transcritical  cycle  Review  Improvement  Performance  COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A CO2 heat pump water heater breadboard facility was built and a performance evaluation was conducted to investigate the effect of ambient temperature and hot water temperature on the overall coefficient of performance (COP) during full tank heating tests in three scenarios typical of residential water heating. Results show that the overall COP was maximized at higher ambient temperatures and at lower hot water temperatures. The overall COP was 30% higher for heating a full tank of cold water than reheating a warm tank water after standby losses. Additionally, potential COP enhancements of two cycle options were investigated. Performance enhancement of the two-stage cycle with internal heat exchanger was found only for standby loss reheating at low ambient temperatures and was 7.5%, while that of the suction line heat exchanger cycle was up to 7.9% for initial tank water heating and around 3.4% for reheating a warm tank water. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002850 [article] Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles = Comparaison de la performance d'un système de chauffage d'eau à pompe à chaleur au CO2 et celle d'un cycle de base et celles de deux cycles au COP élevé [texte imprimé] / Nicholas Fernandez, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2010 . - pp. 635-644. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 635-644 Mots-clés : Heat  pump  Air–water  Carbon  dioxide  Transcritical  cycle  Review  Improvement  Performance  COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A CO2 heat pump water heater breadboard facility was built and a performance evaluation was conducted to investigate the effect of ambient temperature and hot water temperature on the overall coefficient of performance (COP) during full tank heating tests in three scenarios typical of residential water heating. Results show that the overall COP was maximized at higher ambient temperatures and at lower hot water temperatures. The overall COP was 30% higher for heating a full tank of cold water than reheating a warm tank water after standby losses. Additionally, potential COP enhancements of two cycle options were investigated. Performance enhancement of the two-stage cycle with internal heat exchanger was found only for standby loss reheating at low ambient temperatures and was 7.5%, while that of the suction line heat exchanger cycle was up to 7.9% for initial tank water heating and around 3.4% for reheating a warm tank water. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002850

Performance comparison of R410A and R32 in vapor injection cycles / Xing Xu in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 892–903 Titre : Performance comparison of R410A and R32 in vapor injection cycles Titre original : Comparaison de la performance du R410A et du R32 dans des cycles à injection de vapeur Type de document : texte imprimé Auteurs : Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2013 Article en page(s) : pp. 892–903 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : R410A;  R32;  Vapor;  Injection;  Heat  pump Résumé : As global warming has raised more critical concerns in recent years, refrigerants with high global warming potentials (GWP) are facing the challenges of being phased out. R410A, with a GWP of 2088, has been widely used in residential air-conditioner and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. This paper investigates the performance difference using R410A and R32 in a vapor-injected heat pump system. Through experimentation, it was found that the capacity and coefficient of performance (COP) improvements using R32 can reach up to 10% and 9%, respectively, as compared to an identical cycle using R410A. It is concluded that R32 is an excellent alternative to replace R410A in terms of performance and can be further enhanced by component optimization. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003532 [article] Performance comparison of R410A and R32 in vapor injection cycles = Comparaison de la performance du R410A et du R32 dans des cycles à injection de vapeur [texte imprimé] / Xing Xu, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2013 . - pp. 892–903. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 892–903 Mots-clés : R410A;  R32;  Vapor;  Injection;  Heat  pump Résumé : As global warming has raised more critical concerns in recent years, refrigerants with high global warming potentials (GWP) are facing the challenges of being phased out. R410A, with a GWP of 2088, has been widely used in residential air-conditioner and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. This paper investigates the performance difference using R410A and R32 in a vapor-injected heat pump system. Through experimentation, it was found that the capacity and coefficient of performance (COP) improvements using R32 can reach up to 10% and 9%, respectively, as compared to an identical cycle using R410A. It is concluded that R32 is an excellent alternative to replace R410A in terms of performance and can be further enhanced by component optimization. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003532

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

Theoretical study on separate sensible and latent cooling air-conditioning system / Jiazhen Ling in International journal of refrigeration, Vol. 33 N° 3 (Mai 2010) 

Public ISBD [article]  in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 510-520 Titre : Theoretical study on separate sensible and latent cooling air-conditioning system Titre original : Etude théorique d'un système de conditionnement d'air fondé sur le refroidissement sensible et latent Type de document : texte imprimé Auteurs : Jiazhen Ling, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2010 Article en page(s) : pp. 510-520 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  conditioning  Design  Process  Chilling  Air  Heat  exchange  Separation  Sensible  heat  Latent  heat  Vapour  Compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The advantage of separating sensible and latent cooling (SSLC) via the use of separate cycles is saving energy by raising the evaporating temperature of the sensible cooling process. In this study, the pertinent characteristics of the SSLC system using two parallel vapor compression cycles were investigated. The requirement for high air flow rate through the sensible evaporator was the most important hardware design issue, since it might lead to a high air-side pressure drop. To address this issue, a new air distribution method, which could significantly reduce the pressure drop, was proposed to replace the conventional one. The heat exchanger modeling results demonstrated that sensible evaporators of the SSLC system could provide the equivalent cooling capacity at reduced air-side pressure drop to that of the conventional system without increasing the total heat transfer area. Although initial investment of the SSLC system is projected to be higher than the conventional system, the estimated operating cost of the SSLC system is lower than the conventional one because of the low energy consumption. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002758 [article] Theoretical study on separate sensible and latent cooling air-conditioning system = Etude théorique d'un système de conditionnement d'air fondé sur le refroidissement sensible et latent [texte imprimé] / Jiazhen Ling, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2010 . - pp. 510-520. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 510-520 Mots-clés : Air  conditioning  Design  Process  Chilling  Air  Heat  exchange  Separation  Sensible  heat  Latent  heat  Vapour  Compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The advantage of separating sensible and latent cooling (SSLC) via the use of separate cycles is saving energy by raising the evaporating temperature of the sensible cooling process. In this study, the pertinent characteristics of the SSLC system using two parallel vapor compression cycles were investigated. The requirement for high air flow rate through the sensible evaporator was the most important hardware design issue, since it might lead to a high air-side pressure drop. To address this issue, a new air distribution method, which could significantly reduce the pressure drop, was proposed to replace the conventional one. The heat exchanger modeling results demonstrated that sensible evaporators of the SSLC system could provide the equivalent cooling capacity at reduced air-side pressure drop to that of the conventional system without increasing the total heat transfer area. Although initial investment of the SSLC system is projected to be higher than the conventional system, the estimated operating cost of the SSLC system is lower than the conventional one because of the low energy consumption. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002758

Thermal and hydraulic performance of sinusoidal corrugated plate heat exchanger for low temperature lift heat pump / Hoseong Lee in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 689–700 Titre : Thermal and hydraulic performance of sinusoidal corrugated plate heat exchanger for low temperature lift heat pump Titre original : Performance thermique et hydraulique de l'un échangeur à plaques sinusoïdal d'une pompe à chaleur à faible élévation de température Type de document : texte imprimé Auteurs : Hoseong Lee, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2013 Article en page(s) : pp. 689–700 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Low  temperature  lift;  Heat  pump;  Plate  heat  exchanger;  Corrugated Résumé : Thermal and hydraulic performance of a sinusoidal corrugated plate heat exchanger (PHX) was investigated for the application of a low temperature lift heat pump (LTLHP), which requires unique operating conditions. The water-side heat transfer coefficient and pressure drop of the PHX were obtained through the experimental test. The refrigerant-side heat transfer performance was investigated by varying several parameters. The PHX performance was poor due to low refrigerant mass flux. The PHX needs better balance in two fluids for the LTLHP application. From the current study, it is concluded that the conventional PHX applied for the LTLHP application is limited by two main factors: a large pressure drop on the water-side due to corrugated shape, and a low heat transfer performance due to the low refrigerant-side heat transfer performance. In order to address these drawbacks, heat exchanger designs must be improved by optimizing its geometry and flow area asymmetrically for each fluid. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003076 [article] Thermal and hydraulic performance of sinusoidal corrugated plate heat exchanger for low temperature lift heat pump = Performance thermique et hydraulique de l'un échangeur à plaques sinusoïdal d'une pompe à chaleur à faible élévation de température [texte imprimé] / Hoseong Lee, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2013 . - pp. 689–700. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 689–700 Mots-clés : Low  temperature  lift;  Heat  pump;  Plate  heat  exchanger;  Corrugated Résumé : Thermal and hydraulic performance of a sinusoidal corrugated plate heat exchanger (PHX) was investigated for the application of a low temperature lift heat pump (LTLHP), which requires unique operating conditions. The water-side heat transfer coefficient and pressure drop of the PHX were obtained through the experimental test. The refrigerant-side heat transfer performance was investigated by varying several parameters. The PHX performance was poor due to low refrigerant mass flux. The PHX needs better balance in two fluids for the LTLHP application. From the current study, it is concluded that the conventional PHX applied for the LTLHP application is limited by two main factors: a large pressure drop on the water-side due to corrugated shape, and a low heat transfer performance due to the low refrigerant-side heat transfer performance. In order to address these drawbacks, heat exchanger designs must be improved by optimizing its geometry and flow area asymmetrically for each fluid. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003076

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

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