Ebullition saturée de l'eau en écoulement dans un canal étroit : coefficients de transfert de chaleur moyens et corrélations.
Saturated flow boiling of water in a narrow channel: time-averaged heat transfer coefficients and correlations.
Auteurs : WEN D. S., YAN Y., KENNING D. B. R.
Type d'article : Article
Résumé
Time-averaged local heat transfer coefficients were measured during flow boiling of water at atmospheric pressure in a vertical channel of rectangular cross-section 2 mm by 1 mm for ranges of mass flux 57-211 kg/m² s, heat flux 27-160 kW/m², thermodynamic quality 0-0.3 and inlet subcooling 1-12 K. The heat transfer coefficients were found to increase nearly with the square root of the heat flux. There was little effect of mass flux at 107, 134 and 211 kg/m² s; lower heat transfer coefficients at 57 kg/m² s were probably due to transient local dryout. Local time-averaged quality and different inlet conditions of subcooling and compressibility had little effect. Conventionally, this behaviour would be interpreted as nucleate boiling and a dimensional expression correlated the data to ±20%. However, the heat transfer coefficients were considerably higher than would be expected for pool nucleate boiling and visual observation showed local time-sharing between nucleate boiling and thin-film evaporation without nucleation, with only small temporal changes in the heat transfer coefficient. Eleven correlations for conventional and narrow-channel boiling predicted the data poorly, ranging from 250% average over-prediction to 70% average under-prediction. This suggests that conventional methods of distinguishing between nucleate and convective boiling mechanisms are unreliable and that a better understanding of the mechanisms of boiling in narrow channels is necessary to guide the development of correlations.
Détails
- Titre original : Saturated flow boiling of water in a narrow channel: time-averaged heat transfer coefficients and correlations.
- Identifiant de la fiche : 2004-2736
- Langues : Anglais
- Source : Applied Thermal Engineering - vol. 24 - n. 8-9
- Date d'édition : 06/2004
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Indexation
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Thèmes :
Transfert de chaleur;
Transfert de masse - Mots-clés : Coefficient de transfert de chaleur; Géometrie; Canal; Mesure; Tube vertical; Ébullition nucléée; Eau
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Flow boiling heat transfer in vertical tubes co...
- Auteurs : STEINER D., TABOREK J.
- Date : 04/1992
- Langues : Anglais
- Source : Heat Transf. Eng. - vol. 13 - n. 2
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BOILING HEAT TRANSFER OF R114 IN A VERTICAL TUBE.
- Auteurs : FAGERHOLM N. E., GHAZANFARI A. R., KIVIOJA K.
- Date : 1983
- Langues : Anglais
- Source : Wärme Stoffübertrag. - vol. 17 - n. 4
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Heat-transfer mechanism of liquid film flow in ...
- Auteurs : OUCHI M., et al.
- Date : 1991
- Langues : Anglais
- Source : Heat Transf., Jap. Res. - vol. 20 - n. 2
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EXPERIMENTS ON SUBCOOLED FLOW BOILING HEAT TRAN...
- Auteurs : HASAN A., ROY R. P., KALRA S. P.
- Date : 10/1990
- Langues : Anglais
- Source : International Journal of Heat and Mass Transfer - vol. 33 - n. 10
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TRANSFERT DE CHALEUR PAR EBULLITION DANS UNE CA...
- Auteurs : OKAMURA T., SAGAWA Y., YOSHIZAWA Y.
- Date : 1990
- Langues : Japonais
- Source : Cryogenics/ Cryog. Eng. - vol. 25 - n. 4
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