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Film condensation in a horizontal rectangular ductCondensation heat transfer in an annular flow regime with and without interfacial waves was experimentally investigated. The study included measurements of heat transfer rate with condensation of vapor flowing inside a horizontal rectangular duct and experiments on the initiation of interfacial waves in condensation, and adiabatic air-liquid flow. An analytical model for the condensation was developed to predict condensate film thickness and heat transfer coefficients. Some conclusions drawn from the study are that the condensate film thickness was very thin (less than 0.6 mm). The average heat transfer coefficient increased with increasing the inlet vapor velocity. The local heat transfer coefficient decreased with the axial distance of the condensing surface, with the largest change at the leading edge of the test section. The interfacial shear stress, which consisted of the momentum shear stress and the adiabatic shear stress, appeared to have a significant effect on the heat transfer coefficients. In the experiment, the condensate flow along the condensing surface experienced a smooth flow, a two-dimensional wavy flow, and a three-dimensional wavy flow. In the condensation experiment, the local wave length decreased with the axial distance of the condensing surface and the average wave length decreased with increasing inlet vapor velocity, while the wave speed increased with increasing vapor velocity. The heat transfer measurements are reliable. And, the ultrasonic technique was effective for measuring the condensate film thickness when the surface was smooth or had waves of small amplitude.
Document ID
19920010007
Document Type
Contractor Report (CR)
Authors
Lu, Qing (Michigan Technological Univ. Houghton, MI, United States)
Suryanarayana, N. V. (Michigan Technological Univ. Houghton, MI, United States)
Date Acquired
September 6, 2013
Publication Date
February 20, 1992
Subject Category
FLUID MECHANICS AND HEAT TRANSFER
Report/Patent Number
NAS 1.26:190044
NASA-CR-190044
Funding Number(s)
CONTRACT_GRANT: NAG3-711
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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