| Titre : | Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point (2011) |
| 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 |
| Auteurs : | Chieko Kondou, Auteur ; Pega Hrnjak, Auteur |
| Type de document : | Article : texte imprimé |
| Dans : | International journal of refrigeration (Vol. 34 N° 3, Mai 2011) |
| Article en page(s) : | pp. 719-731 |
| Note générale : | Génie Mécanique |
| Langues : | Anglais |
| Index. décimale : | 621.5 (Energie pneumatique. Machinerie et outils. Réfrigération) |
| Tags : | Carbon dioxide Heat transfer Horizontal tube Critical point |
| 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 |
