What is it about?
Countercurrent condensation for an external flow has never been investigated in detail. In our theoretical study, we consider the simplest geometry, a vertical condensing surface on which film condensation takes place for an up-flow (against gravity) of water vapor. Our theory predicts eight possible film configurations: hanging film, falling film, falling film with zero interface velocity, partly falling film, bidirectional film, partly rising film, transition film, and rising film.
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Why is it important?
Our theory introduces eight possible film configurations that appear when a rising vapor stream condenses on a vertical surface. We have identified five physical mechanisms that subtly govern the film dynamics: gravity, wall shear, interfacial shear, near-wall mass-flux deficit, and interfacial mass entrainment. Concurrent participation of these mechanisms yields spiral vortices within the thin condensate film. Our results show that the entire film morphology depends on a subcooling parameter and a characteristic number.
Perspectives
Although film condensation has been extensively studied since the nineteenth century, countercurrent film condensation for an external flow has never been investigated systematically. Here, we develop a theory considering vapor up-flow near a subcooled vertical surface. The theory captures condensate dynamics and heat transfer characteristics.
Sayantan Sengupta
National Institute of Technology Durgapur
Read the Original
This page is a summary of: Dynamics of condensate film in the vicinity of a pulling vapor stream, Physics of Fluids, December 2022, American Institute of Physics,
DOI: 10.1063/5.0131421.
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