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Pressure Drop During Condensation in Vertical Tubes

  • R. Numrich
  • N. Claus
Conference paper
Part of the EUROTHERM Seminars book series (EUROTHERM, volume 18)

Abstract

The calculation of required interfacial area during condensation process depends on the knowledge of the heat transfer coefficient in a falling condensate film. This transfer coefficient is a function of flow pattern, physical properties of the condensate film and also of shear stress at the condensate film surface due to the friction of gas flow. For the description of this influence on heat transfer the correct evaluation of shear stress will be necessary. Whereas many calculation methods exist in the range of atmospheric pressure and for systems without simultaneous phase change, data at higher pressures and in the presence of condensation are not available. At a testing plant friction pressure drop and consequently shear stress at the film surface were determined experimentally for downwards cocurrent flow. A method for computing the shear stress will be presented which provides good predictions of the experimental data at higher pressures. Applying this presented method for simultaneous condensation processes two phenomena have to be considered. Firstly, the condensing vapour increases the friction factor and consequently the shear stress at the condensate film surface following the film theory. Secondly, the momentum balance changes due to the decreasing velocity of the gas phase. Pressure drop measurements during partial condensation of vapour in the presence of air and heat transfer measurements during condensation with pure steam at increased pressure show good agreement with the presented method considering these cited phenomena.

Keywords

Shear Stress Pressure Drop Heat Transfer Coefficient Nusselt Number Friction Factor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • R. Numrich
    • 1
  • N. Claus
    • 1
  1. 1.Fachgruppe Verfahrenstechnik, FB 10Maschinentechnik Universität-Gesamthochschule-PaderbornGermany

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