An analytical investigation into filmwise condensation on a horizontal tube in a porous medium with suction at the tube surface |
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Authors: | Tong Bou Chang Fu Jen Wang |
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Institution: | (1) Department of Mechanical Engineering, Southern Taiwan University, Tainan, Taiwan;(2) Department of Refrigeration, Air Conditioning and Energy Engineering, National Chin-Yi University of Technology, Taichung, Taiwan;(3) 1, Nan-Tai Street, YungKang, Tainan, Taiwan |
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Abstract: | An analytical investigation is performed into the problem of steady filmwise condensation flow over the outside surface of
a horizontal tube embedded in a porous medium with suction at the tube surface. As in classical film condensation problems,
an assumption is made that the condensate and vapor layers meet at a common boundary rather than being separated by an intermediary
two-phase zone. Furthermore, it is assumed that the condensate film has constant properties and conforms to Darcy’s law within
the porous medium. By introducing an effective suction function to represent the effect of the wall suction on the thickness
of the liquid film, both the local condensate film thickness and the local Nusselt number are derived using a simple numerical
shooting method. The analytical results indicate that the mean Nusselt number depends on the Darcy number, the Jakob number,
the Rayleigh number and the suction parameter. Furthermore, it is found that the local Nusselt number has a maximum value
at the upper surface of the horizontal tube and reduces toward zero at the lower surface as a result of the finite thickness
of the condensate layer. |
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Keywords: | |
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