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Heat Transfer Research

Impact factor: 0.930

ISSN Print: 1064-2285
ISSN Online: 2162-6561

Volumes:
Volume 48, 2017 Volume 47, 2016 Volume 46, 2015 Volume 45, 2014 Volume 44, 2013 Volume 43, 2012 Volume 42, 2011 Volume 41, 2010 Volume 40, 2009 Volume 39, 2008 Volume 38, 2007 Volume 37, 2006 Volume 36, 2005 Volume 35, 2004 Volume 34, 2003 Volume 33, 2002 Volume 32, 2001 Volume 31, 2000 Volume 30, 1999 Volume 29, 1998 Volume 28, 1997

Heat Transfer Research

DOI: 10.1615/HeatTransRes.2012004376
pages 47-68

VOF MODELING AND ANALYSIS OF FILMWISE CONDENSATION BETWEEN VERTICAL PARALLEL PLATES

Zhenyu Liu
Shanghai Jiao Tong University
Bengt Sunden
Energy Sciences Heat Transfer Division, Box 118, SE-22100 Lund, Sweden
Jinliang Yuan
Department of Energy Sciences, Lund University, Box 118, SE-22100 Lund, Sweden

ABSTRACT

In this study, a computational model has been developed to predict condensation heat transfer between vertical parallel plates. Transient simulations of filmwise condensation in a small two-dimensional parallel plate passage are performed. The Volume of Fluid (VOF) method is used to track the vapor−liquid interface. The Geometric Reconstruction Scheme, which is a Piecewise Linear Interface Calculation (PLIC) method, is employed to keep the interface sharp. The governing equations and the VOF equation with relevant source terms for condensation are solved explicitly. The surface tension is taken into account in the modeling and it is evaluated by the Continuum Surface Force (CSF) approach. Different methods to evaluate the source terms in the VOF and energy equations are summarized based on previous studies. The simulation is performed using the CFD software package, Ansys Fluent, and an in-house developed code. This in-house code is specifically developed to calculate the source terms associated with phase change, which are deduced from the Hertz−Knudsen equation based on the kinetic gas theory. The predicted results show that a laminar regime exists at the top of the wall, where the film is the thinnest. A wavy regime appears as a series of regular ripples/waves of condensate moving downwards under the action of both gravity and shear stress in the interface area. As a further step, the simulations have been run under different surface tension, wall temperature, and inlet velocity conditions. The predictions also indicate that the wave peak height decreases with increasing surface tension and decreases with increasing inlet velocity. This has an effect on the heat transfer characteristics of the condensation process. The condensation heat transfer increases sharply by increasing the temperature difference between the wall and saturation temperature of the inlet steam.