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

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

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Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions / Youngju Joo in International journal of refrigeration, Vol. 34 N° 4 (Juin 2011)  

Public ISBD [article]  inInternational journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 893-901 Titre : Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions Titre original : Caractéristiques de la performance de plusieurs pompes à chaleur assurant le chauffage et le refroidissement simultanés, fonctionnant en charge partielle Type de document : texte imprimé Auteurs : Youngju Joo, Auteur ; Hoon Kang, Auteur ; Jae Hwan Ahn, Auteur Année de publication : 2011 Article en page(s) : pp. 893-901 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat pump recovery Variable speed Electronic expansion valve R410A Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A simultaneous cooling and heating multi-heat pump can improve thermal comfort and energy efficiency through heat recovery at partial load conditions. The performance of a simultaneous heating and cooling multi-heat pump with four indoor units was measured by varying the compressor speed, EEV opening, and fan speed at full and partial load conditions in five operating modes. In the cooling-only and heating-only modes, the heating and cooling capacities were properly controlled by varying the compressor speed. However, in the cooling-main and heating-main modes under partial load conditions, a large imbalance between the cooling and heating capacities was observed even though the compressor speed was optimized. This capacity imbalance under partial load conditions was optimized by adjusting the EEV openings in the mode change unit and the outdoor unit. In addition, in the entire-heat recovery mode, rating compressor speed ratios were proposed under the full and partial load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000041 [article] Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions = Caractéristiques de la performance de plusieurs pompes à chaleur assurant le chauffage et le refroidissement simultanés, fonctionnant en charge partielle [texte imprimé] / Youngju Joo, Auteur ; Hoon Kang, Auteur ; Jae Hwan Ahn, Auteur . - 2011 . - pp. 893-901. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 893-901 Mots-clés : Heat pump recovery Variable speed Electronic expansion valve R410A Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A simultaneous cooling and heating multi-heat pump can improve thermal comfort and energy efficiency through heat recovery at partial load conditions. The performance of a simultaneous heating and cooling multi-heat pump with four indoor units was measured by varying the compressor speed, EEV opening, and fan speed at full and partial load conditions in five operating modes. In the cooling-only and heating-only modes, the heating and cooling capacities were properly controlled by varying the compressor speed. However, in the cooling-main and heating-main modes under partial load conditions, a large imbalance between the cooling and heating capacities was observed even though the compressor speed was optimized. This capacity imbalance under partial load conditions was optimized by adjusting the EEV openings in the mode change unit and the outdoor unit. In addition, in the entire-heat recovery mode, rating compressor speed ratios were proposed under the full and partial load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000041

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