Abonnement à la biblothèque: Guest
Page d'accueil Archives Thermal Letter Responsables Réunions à venir Assembly for International Heat Transfer Conferences
International Heat Transfer Conference 6

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

POOL BOILING HEAT TRANSFER AND SIZE OF ACTIVE NUCLEATION CENTERS FOR HORIZONTAL PLATES WITH DIFFERENT SURFACE ROUGHNESS

K. Bier
Institut für Technische Thermodynamik und Kältetechnik der Universität Karlsruhe (TH), D - 7500 Karlsruhe 1

Dieter Gorenflo
Laboratorium für Wärme- und Kältetechnik, Universität -GH- Paderborn, D-4790 Paderborn, Pohlweg 55, Germany

M. Salem
Institut für Technische Thermodynamik und Kältetechnik der Universität Karlsruhe (TH), D - 7500 Karlsruhe 1

Y. Tanes
Karadeniz Teknik Universitesi Makina bölümü, Trabzon, Turkey

DOI: 10.1615/IHTC6.3730
pages 151-156

Résumé

The heat transfer from horizontal copper plates with different surface finish to boiling refrigerants Rll (CFCl3) and Rll5(C2F5Cl) was measured at saturation pressures between 0.4 and 91 percent of the critical pressure pc. Although the relative pressure dependence of the heat transfer coefficient α is similar for the plates with different surface treatment, a detailed comparison of the experimental results shows that the influence of the different surface conditions achieved by mechanical and chemical treatment on the absolute value of α cannot be correlated by a single roughness parameter within the whole range of pressures investigated.
Applying the Mikic-Rohsenow-model for the bubble population the distribution function N(r) for the size of stable vapor bubbles in active nucleation sites is evaluated from the measured relationship between α and heat flux q. For each of the surfaces the functions N(r) derived from α (q)-measurements at different saturation pressures show little differences. The distribution functions N(r) obtained in this way are in relatively good agreement with direct results for the number density of bubbles available in literature.

Achat $25.00 Check subscription Déontologie de l'édition scientifique et abus Recommander à mon bibliothécaire Ajouter cette page aux favoris