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ISSN Online: 2377-424X

ISBN Print: 0-89116-559-2

International Heat Transfer Conference 8
August, 17-22, 1986, San Francisco, USA

DROP-SIZE DISTRIBUTIONS AND HEAT TRANSFER IN DROPWISE CONDENSATION − CONDENSATION COEFFICIENT OF WATER AT LOW PRESSURES

Get access (open in a dialog) DOI: 10.1615/IHTC8.120
pages 1671-1676

Résumé

Though an apparent difference in the number density of microscopic drops existed between gold and chromium condenser surfaces used, the heat-transfer coefficient was found to be almost of the same value. Then the distributions of drops by sizes down to 1 μm in radius were experimentally determined. For the gold condenser surface on which small drops seemed to originate densely, the measured drop-size distribution showed a satisfactory agreement with the theoretical prediction in the so-called equilibrium region of small drops. On the other hand, for the chromium surface, the number density of drops smaller than 7 μm deviated clearly downward. Integrating the measured drop-size distribution weighted with the substantial condensation rate onto each droplet yields a heat-transfer coefficient, which should coincide with the actually measured one. From the comparison of the data for the both condenser surfaces, it is concluded that the condensation coefficient of water at pressures between 1 and 4 kPa is 0.4.