ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
FALLING FILM EVAPORATION INSIDE A CLOSED THERMOSYPHON
Abstract
In the present contribution, visual observations and heat transfer data available in literature for falling film evaporation inside a closed thermosyphon are evaluated and discussed in the light of Nusselt's theory. The fraction of the wall surface area covered by liquid is found to be significantly affected by heat flux and tube diameter. Bubble formation inside the falling film acts to heal dry patches due to spray cooling, a mechanism which fails, however, in the annular thermosyphon. A preliminary model is proposed for the prediction of heat transfer coefficients which includes two components, one for evaporation from the film surface and another one for the enhancement of heat transfer due to nucleate boiling inside the film.