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Title: Film condensation of saturated and superheated vapors along isothermal vertical surfaces in mixed convection

Abstract

An analysis for condensation from an isothermal vertical flat plate in mixed convection is reported. The entire mixed convection regime is divided into two regions. One region covers the forced-convection-dominated regime, and the other covers the free-convection-dominated regime. The governing system of equations is first transformed into a dimensionless form by the nonsimilar transformation, separately for each regime, and then solved using the local nonsimilarity method along with a finite difference scheme. Two nonsimilarity parameters are introduced. The parameter {xi}{sub f} = Gr{sub x}/Re{sub x}{sup 2} characterizes the effect of buoyancy force on forced convection, while the parameter {xi}{sub n} = Re{sub x}/Gr{sub x}{sup 1/2} characterizes the effect of forced flow on free convection. Numerical results for pure steam and refrigerant R-134a are presented for both saturated and superheated cases. It is found that the buoyancy force significantly increases the wall shear stress and condensate mass flux. To a lesser degree, the buoyancy force also increases the wall heat flux. Superheating is found to have an insignificant effect on wall heat flux for a pure vapor.

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Missouri, Rolla, MO (US)
OSTI Identifier:
20000641
Alternate Identifier(s):
OSTI ID: 20000641
Resource Type:
Journal Article
Journal Name:
Numerical Heat Transfer. Part A, Applications
Additional Journal Information:
Journal Volume: 36; Journal Issue: 4; Other Information: PBD: Sep 1999; Journal ID: ISSN 1040-7782
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; HEAT EXCHANGERS; VAPOR CONDENSATION; NATURAL CONVECTION; FORCED CONVECTION; TRANSFORMATIONS; FINITE DIFFERENCE METHOD; STEAM; REFRIGERANTS; SATURATION; SUPERHEATING

Citation Formats

Winkler, C.M., Chen, T.S., and Minkowycz, W.J. Film condensation of saturated and superheated vapors along isothermal vertical surfaces in mixed convection. United States: N. p., 1999. Web. doi:10.1080/104077899274705.
Winkler, C.M., Chen, T.S., & Minkowycz, W.J. Film condensation of saturated and superheated vapors along isothermal vertical surfaces in mixed convection. United States. doi:10.1080/104077899274705.
Winkler, C.M., Chen, T.S., and Minkowycz, W.J. Wed . "Film condensation of saturated and superheated vapors along isothermal vertical surfaces in mixed convection". United States. doi:10.1080/104077899274705.
@article{osti_20000641,
title = {Film condensation of saturated and superheated vapors along isothermal vertical surfaces in mixed convection},
author = {Winkler, C.M. and Chen, T.S. and Minkowycz, W.J.},
abstractNote = {An analysis for condensation from an isothermal vertical flat plate in mixed convection is reported. The entire mixed convection regime is divided into two regions. One region covers the forced-convection-dominated regime, and the other covers the free-convection-dominated regime. The governing system of equations is first transformed into a dimensionless form by the nonsimilar transformation, separately for each regime, and then solved using the local nonsimilarity method along with a finite difference scheme. Two nonsimilarity parameters are introduced. The parameter {xi}{sub f} = Gr{sub x}/Re{sub x}{sup 2} characterizes the effect of buoyancy force on forced convection, while the parameter {xi}{sub n} = Re{sub x}/Gr{sub x}{sup 1/2} characterizes the effect of forced flow on free convection. Numerical results for pure steam and refrigerant R-134a are presented for both saturated and superheated cases. It is found that the buoyancy force significantly increases the wall shear stress and condensate mass flux. To a lesser degree, the buoyancy force also increases the wall heat flux. Superheating is found to have an insignificant effect on wall heat flux for a pure vapor.},
doi = {10.1080/104077899274705},
journal = {Numerical Heat Transfer. Part A, Applications},
issn = {1040-7782},
number = 4,
volume = 36,
place = {United States},
year = {1999},
month = {9}
}