This experimental and analytical study focuses on the formation of banded condensate films on a horizontal tube, when the ammonia mass fraction of the vapor is less than 0.0126. The experimental results show that there is a step change in the heat transfer coefficient when a banded film is formed. This change develops when the vapor mass fraction is approximately 0.004 and the heat transfer coefficient at the end of the change is 15% greater than the value expected for steam. The banded films are initiated at the base of the tube; midway between the regions where droplets detach. Photographs taken during the tests show that the development starts with the formation of a single band; when this band is complete, secondary bands are formed on either side and then further bands are added until the complete tube surface is covered with a banded film. The reason for the delay in the formation of the bands is examined using a simple two-dimensional force balance. The success of this examination provides an insight to the mechanisms employed in the formation of banded films.
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The Formation of Banded Condensate Films in Weak Ammonia–Water Mixtures
Joe Deans,
Joe Deans
Department of Mechanical Engineering University of Auckland Private Bag 92019 Auckland 1142
New Zealand
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Serhan Kucuka
Serhan Kucuka
Dokuz Eylul University Faculty of Engineering Department of Mechanical Engineering 35100 Bornova Izmir
Turkey
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Joe Deans
Department of Mechanical Engineering University of Auckland Private Bag 92019 Auckland 1142
New Zealand
e-mail:
Serhan Kucuka
Dokuz Eylul University Faculty of Engineering Department of Mechanical Engineering 35100 Bornova Izmir
Turkey
e-mail:J. Heat Transfer. Oct 2011, 133(10): 101505 (10 pages)
Published Online: August 15, 2011
Article history
Received:
January 12, 2010
Revised:
April 14, 2011
Online:
August 15, 2011
Published:
August 15, 2011
Citation
Deans, J., and Kucuka, S. (August 15, 2011). "The Formation of Banded Condensate Films in Weak Ammonia–Water Mixtures." ASME. J. Heat Transfer. October 2011; 133(10): 101505. https://doi.org/10.1115/1.4004019
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