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Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes / Chieko Kondou in International journal of refrigeration, Vol. 36 N° 8 (Décembre 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2366–2378 Titre : Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes Titre original : Écoulement en ébullition d'un mélange non-azéotropique de R32 et de R1234ze dans des tubes horizontaux à micro-ailettes Type de document : texte imprimé Auteurs : Chieko Kondou, Auteur ; Daisuke Baba, Auteur ; Fumiya Mishima, Auteur Année de publication : 2014 Article en page(s) : pp. 2366–2378 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flow  boiling;  heat  transfer;  pressure  drop;  microfin  tube;  non-zeotropic  mixture;  GWP Résumé : Flow boiling of a potential refrigerant R32/R1234ze(E) in a horizontal microfin tube of 5.21 mm inner diameter is experimentally investigated. The heat transfer coefficient (HTC) and pressure drop are measured at a saturation temperature of 10 °C, heat fluxes of 10 and 15 kW m−2, and mass velocities from 150 to 400 kg m−2 s−1. The HTC of R1234ze(E) is lower than that of R32. Degradation in the HTC of the R32/R1234ze(E) mixture is significant; the HTC is even lower than that of R1234ze(E). The HTC is minimized at the composition 0.2/0.8 by mass, where the temperature glide and the mass fraction distribution are maximized. A predicting correlation based on Momoki et al. (1995) associated with the correction methods of Thome (1981) to consider the mass transfer resistance and Stephan (1992) to consider the additionally required sensible heat is proposed and validated with the experimental results. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001734 [article] Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes = Écoulement en ébullition d'un mélange non-azéotropique de R32 et de R1234ze dans des tubes horizontaux à micro-ailettes [texte imprimé] / Chieko Kondou, Auteur ; Daisuke Baba, Auteur ; Fumiya Mishima, Auteur . - 2014 . - pp. 2366–2378. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 8 (Décembre 2013) . - pp. 2366–2378 Mots-clés : Flow  boiling;  heat  transfer;  pressure  drop;  microfin  tube;  non-zeotropic  mixture;  GWP Résumé : Flow boiling of a potential refrigerant R32/R1234ze(E) in a horizontal microfin tube of 5.21 mm inner diameter is experimentally investigated. The heat transfer coefficient (HTC) and pressure drop are measured at a saturation temperature of 10 °C, heat fluxes of 10 and 15 kW m−2, and mass velocities from 150 to 400 kg m−2 s−1. The HTC of R1234ze(E) is lower than that of R32. Degradation in the HTC of the R32/R1234ze(E) mixture is significant; the HTC is even lower than that of R1234ze(E). The HTC is minimized at the composition 0.2/0.8 by mass, where the temperature glide and the mass fraction distribution are maximized. A predicting correlation based on Momoki et al. (1995) associated with the correction methods of Thome (1981) to consider the mass transfer resistance and Stephan (1992) to consider the additionally required sensible heat is proposed and validated with the experimental results. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713001734

Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point / Chieko Kondou in International journal of refrigeration, Vol. 34 N° 3 (Mai 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 719-731 Titre : Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point Titre original : Rejet de chaleur lors de l'écoulement du R744 à l'intérieur d'un tube lisse horizontal sous des conditions de refroidissement à température uniforme proche du point critique Type de document : texte imprimé Auteurs : Chieko Kondou, Auteur ; Pega Hrnjak, Auteur Année de publication : 2011 Article en page(s) : pp. 719-731 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon  dioxide  Heat  transfer  Horizontal  tube  Critical  point Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat rejection from CO2 flow near the critical point, where commercial refrigerators spend most of their operating hours, was investigated in this study. Experimental results on the heat transfer coefficient and pressure drop of mass flux from 100 to 240 kg m−2 s−1 at pressures from 5 to 7.5 MPa in a horizontal smooth tube of 6.1 mm inner diameter are provided and compared with correlations. The heat rejection process below critical pressure was categorized into superheat, two-phase, and subcool zones in which the bulk-mean temperature was superheated, saturated, and subcooled, respectively. The results indicated that the heat transfer coefficient in superheat zone is significantly higher than correlations proposed for single-phase turbulent flow, and the condensation was identified from the tube wall temperature below saturation temperature. This superheat zone accounts for a significant portion of the heat rejected in the subcritical cycle and affects on condenser sizing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000263X [article] Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point = Rejet de chaleur lors de l'écoulement du R744 à l'intérieur d'un tube lisse horizontal sous des conditions de refroidissement à température uniforme proche du point critique [texte imprimé] / Chieko Kondou, Auteur ; Pega Hrnjak, Auteur . - 2011 . - pp. 719-731. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 719-731 Mots-clés : Carbon  dioxide  Heat  transfer  Horizontal  tube  Critical  point Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat rejection from CO2 flow near the critical point, where commercial refrigerators spend most of their operating hours, was investigated in this study. Experimental results on the heat transfer coefficient and pressure drop of mass flux from 100 to 240 kg m−2 s−1 at pressures from 5 to 7.5 MPa in a horizontal smooth tube of 6.1 mm inner diameter are provided and compared with correlations. The heat rejection process below critical pressure was categorized into superheat, two-phase, and subcool zones in which the bulk-mean temperature was superheated, saturated, and subcooled, respectively. The results indicated that the heat transfer coefficient in superheat zone is significantly higher than correlations proposed for single-phase turbulent flow, and the condensation was identified from the tube wall temperature below saturation temperature. This superheat zone accounts for a significant portion of the heat rejected in the subcritical cycle and affects on condenser sizing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000263X