Documents disponibles écrits par cet auteur

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

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

Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications / Stefan Elbel in International journal of refrigeration, Vol. 34 N° 7 (Novembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 7 (Novembre 2011) . - pp. 1545-1561 Titre : Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications Titre original : Historique et développements actuels des systèmes frigorifiques à éjecteur, avec l'accent mis sur les applications en conditionnement d'air au dioxyde de carbone transcritiques Type de document : texte imprimé Auteurs : Stefan Elbel, Auteur Année de publication : 2011 Article en page(s) : pp. 1545-1561 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Ejector  R744  Expansion  Air  conditioning  Efficiency Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper gives an overview of historical and present developments on how ejectors can be utilized to improve the performance of air-conditioning and refrigeration systems. Research on ejector refrigeration cycles that utilize low-grade energy sources to produce cooling is summarized. Another major class of ejector refrigeration cycles that is described tries to recover expansion work by means of a two-phase ejector. This particular approach appears to be very promising for transcritical carbon dioxide (CO2, R744) systems with inherently large throttling losses. The paper further presents the latest analytical and experimental results of a comprehensive study carried out to investigate possible performance improvements of transcritical R744 two-phase ejector systems. Relevant operational parameters were varied and effects on performance resulting from different ejector geometries were studied as well. Two-phase mixing shock waves inside the ejector were detected by recoding static wall pressure distributions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002720 [article] Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications = Historique et développements actuels des systèmes frigorifiques à éjecteur, avec l'accent mis sur les applications en conditionnement d'air au dioxyde de carbone transcritiques [texte imprimé] / Stefan Elbel, Auteur . - 2011 . - pp. 1545-1561. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 7 (Novembre 2011) . - pp. 1545-1561 Mots-clés : Ejector  R744  Expansion  Air  conditioning  Efficiency Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper gives an overview of historical and present developments on how ejectors can be utilized to improve the performance of air-conditioning and refrigeration systems. Research on ejector refrigeration cycles that utilize low-grade energy sources to produce cooling is summarized. Another major class of ejector refrigeration cycles that is described tries to recover expansion work by means of a two-phase ejector. This particular approach appears to be very promising for transcritical carbon dioxide (CO2, R744) systems with inherently large throttling losses. The paper further presents the latest analytical and experimental results of a comprehensive study carried out to investigate possible performance improvements of transcritical R744 two-phase ejector systems. Relevant operational parameters were varied and effects on performance resulting from different ejector geometries were studied as well. Two-phase mixing shock waves inside the ejector were detected by recoding static wall pressure distributions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002720

Theoretical and practical comparison of two-phase ejector refrigeration cycles including First and Second Law analysis / Neal, Lawrence in International journal of refrigeration, Vol. 36 N° 4 (Juin 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 4 (Juin 2013) . - pp. 1220–1232 Titre : Theoretical and practical comparison of two-phase ejector refrigeration cycles including First and Second Law analysis Titre original : Comparaison théorique et pratique des cycles frigorifiques diphasiques à éjecteur, y compris à l'aide d'analyse fondée sur les premier et second principes Type de document : texte imprimé Auteurs : Neal, Lawrence, Auteur ; Stefan Elbel, Auteur Année de publication : 2013 Article en page(s) : pp. 1220–1232 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Ejector;  Expansion  work  recovery;  Throttling  loss;  Availability;  Destruction;  Cycle-comparison Résumé : This paper compares the standard two-phase ejector refrigeration cycle with a liquid–vapor separator to two alternate, less commonly considered two-phase ejector refrigeration cycles as well as to a conventional cycle with an expansion valve. An analytical comparison of the different ejector cycles' theoretical COP's is presented and used to show that they have the same theoretical COP. Numerical models are used to further compare the cycles in terms of theoretical COP and availability destruction. The results show that the standard two-phase ejector cycle has lower availability destruction and higher Second Law efficiency than the alternate ejector cycles despite having the same theoretical COP. Some advantages and disadvantages of the different ejector cycles that are not accounted for in the theoretical COP are discussed. The potential practical advantages offered by the alternate ejector cycles show that these and other alternate ejector cycles may be worth additional attention in future studies. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000625 [article] Theoretical and practical comparison of two-phase ejector refrigeration cycles including First and Second Law analysis = Comparaison théorique et pratique des cycles frigorifiques diphasiques à éjecteur, y compris à l'aide d'analyse fondée sur les premier et second principes [texte imprimé] / Neal, Lawrence, Auteur ; Stefan Elbel, Auteur . - 2013 . - pp. 1220–1232. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 4 (Juin 2013) . - pp. 1220–1232 Mots-clés : Ejector;  Expansion  work  recovery;  Throttling  loss;  Availability;  Destruction;  Cycle-comparison Résumé : This paper compares the standard two-phase ejector refrigeration cycle with a liquid–vapor separator to two alternate, less commonly considered two-phase ejector refrigeration cycles as well as to a conventional cycle with an expansion valve. An analytical comparison of the different ejector cycles' theoretical COP's is presented and used to show that they have the same theoretical COP. Numerical models are used to further compare the cycles in terms of theoretical COP and availability destruction. The results show that the standard two-phase ejector cycle has lower availability destruction and higher Second Law efficiency than the alternate ejector cycles despite having the same theoretical COP. Some advantages and disadvantages of the different ejector cycles that are not accounted for in the theoretical COP are discussed. The potential practical advantages offered by the alternate ejector cycles show that these and other alternate ejector cycles may be worth additional attention in future studies. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000625