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International Heat Transfer Conference 12

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

Effect of countercurrent vapour flow on film condensation heat transfer inside a vertical tube

Ulrich Gross
Institute of Thermal Engineering, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 7, 09599 Freiberg, Germany

Christian Philipp
Institute of Thermal Engineering, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 7, 09599 Freiberg, Germany

Sven Thumm
Ballard Power Systems AG, Neue Str. 95, 73230 Kirchheim/Teck-Nabern, Germany

DOI: 10.1615/IHTC12.650
6 pages

Abstract

Local film-condensation heat transfer coefficients have been measured inside a vertical tube with countercurrent flow of vapour (from below) and liquid (from above). Water, ethanol and isopropanol have been used as the test fluids at liquid-film Reynolds numbers up to 2100 (i.e. fully turbulent film), vapour Reynolds numbers below the flooding limit, and liquid Prandtl numbers between 2.6 and 33. Results are presented in diagrams, and they are correlated by respective equations. Shear stress is found to restrain the heat transfer in case of a very thin (smooth laminar) liquid film, but condensation heat transfer coefficients are enhanced by the shear stress in the wavy range and for beginning turbulence. This can be well represented by a power function whose slope strongly increases with the liquid Prandtl number.

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