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Condensation heat transfer characteristics of CO2 in a horizontal smooth tube / Piljoo Kang 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. 1090–1097 Titre : Condensation heat transfer characteristics of CO2 in a horizontal smooth tube Titre original : Caractéristiques de transfert de chaleur du CO2 à l'intérieur d'un tube lisse horizontal Type de document : texte imprimé Auteurs : Piljoo Kang, Auteur ; Jaehyeok Heo, Auteur ; Rin Yun, Auteur Année de publication : 2013 Article en page(s) : pp. 1090–1097 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation  heat  transfer;  Carbon  dioxide  (CO2);  Heat  transfer  coefficient;  Pressure  drop;  Low  temperature Résumé : The condensation heat transfer characteristics of CO2 flowing in a horizontal smooth tube were investigated. The tube diameter was 5.15 mm. The condensation temperature ranged from −10 to 5 °C, and the mass flux was from 600 to 1000 kg m−2 s−1. When the temperature changed from 0 to −10 °C, the increase rate of the heat transfer coefficient was from 9.4 to 14.6%, and the pressure drop increased from 6.2 to 52.9%. When the mass flux increased from 600 to 1000 kg m−2 s−1, the heat transfer coefficient increased from 6 to 35%, and the pressure drop increased from 60 to 165%, which were dependent on the condensation temperature. The increases come from the change of vapor velocity and thermophysical properties with condensation temperature. Considering large variation of mass flux from 200 to 1200 kg m−2 s−1 by including the existing studies, the effect of mass flux on condensation heat transfer coefficient was minor. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002617 [article] Condensation heat transfer characteristics of CO2 in a horizontal smooth tube = Caractéristiques de transfert de chaleur du CO2 à l'intérieur d'un tube lisse horizontal [texte imprimé] / Piljoo Kang, Auteur ; Jaehyeok Heo, Auteur ; Rin Yun, Auteur . - 2013 . - pp. 1090–1097. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1090–1097 Mots-clés : Condensation  heat  transfer;  Carbon  dioxide  (CO2);  Heat  transfer  coefficient;  Pressure  drop;  Low  temperature Résumé : The condensation heat transfer characteristics of CO2 flowing in a horizontal smooth tube were investigated. The tube diameter was 5.15 mm. The condensation temperature ranged from −10 to 5 °C, and the mass flux was from 600 to 1000 kg m−2 s−1. When the temperature changed from 0 to −10 °C, the increase rate of the heat transfer coefficient was from 9.4 to 14.6%, and the pressure drop increased from 6.2 to 52.9%. When the mass flux increased from 600 to 1000 kg m−2 s−1, the heat transfer coefficient increased from 6 to 35%, and the pressure drop increased from 60 to 165%, which were dependent on the condensation temperature. The increases come from the change of vapor velocity and thermophysical properties with condensation temperature. Considering large variation of mass flux from 200 to 1200 kg m−2 s−1 by including the existing studies, the effect of mass flux on condensation heat transfer coefficient was minor. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002617

Simulations on the performance of a vapor-injection heat pump for different cylinder volume ratios of a twin rotary compressor / Jaehyeok Heo 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. 730–744 Titre : Simulations on the performance of a vapor-injection heat pump for different cylinder volume ratios of a twin rotary compressor Titre original : Simulations de la performance d'une pompe à chaleur à injection de vapeur pour plusieurs volumes de cylindres d'un compresseur rotatif à deux cylindres Type de document : texte imprimé Auteurs : Jaehyeok Heo, Auteur ; Rin Yun, Auteur ; Yongchan Kim, Auteur Année de publication : 2013 Article en page(s) : pp. 730–744 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Heat  pump;  Injection;  Rotary  compressor;  Simulation;  Cylinder  volume Résumé : In residential air-source heat pump systems, the refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. A numerical simulation model of a flash tank vapor-injection heat pump with a twin rotary compressor is newly presented in this paper. The performance of the twin rotary compressor with refrigerant injection was simulated using a loss and efficiency model. The model was validated by comparing the predictions with measured data. In addition, the model was used to analyze the performance characteristics of the vapor-injection heat pump according to the cylinder volume ratio of the twin rotary compressor. Based on the simulation results, optimum cylinder volume ratios were suggested for various design conditions, including for the fixed first cylinder volume, the fixed total cylinder volume, and the fixed heating capacity. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002757 [article] Simulations on the performance of a vapor-injection heat pump for different cylinder volume ratios of a twin rotary compressor = Simulations de la performance d'une pompe à chaleur à injection de vapeur pour plusieurs volumes de cylindres d'un compresseur rotatif à deux cylindres [texte imprimé] / Jaehyeok Heo, Auteur ; Rin Yun, Auteur ; Yongchan Kim, Auteur . - 2013 . - pp. 730–744. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 730–744 Mots-clés : Heat  pump;  Injection;  Rotary  compressor;  Simulation;  Cylinder  volume Résumé : In residential air-source heat pump systems, the refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. A numerical simulation model of a flash tank vapor-injection heat pump with a twin rotary compressor is newly presented in this paper. The performance of the twin rotary compressor with refrigerant injection was simulated using a loss and efficiency model. The model was validated by comparing the predictions with measured data. In addition, the model was used to analyze the performance characteristics of the vapor-injection heat pump according to the cylinder volume ratio of the twin rotary compressor. Based on the simulation results, optimum cylinder volume ratios were suggested for various design conditions, including for the fixed first cylinder volume, the fixed total cylinder volume, and the fixed heating capacity. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002757