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Cooling tower plume abatement using a coaxial plume structure
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- Author(s) / Creator(s)
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The traditional approach of cooling tower plume abatement is supposed to result in an unsaturated, well-mixed
plume with a ‘‘top-hat” structure in the radial structure, but this is an idealization that is rarely
achieved in practice. Meanwhile, previous analyses have shown that there may be an advantage in specifically
separating the wet and dry air streams whereby the corresponding plume is of the coaxial variety
with dry air enveloping (and thereby shielding) an inner core of wet air. Given that a detailed understanding
of the evolution of coaxial plumes is presently lacking, we derive an analytical model of coaxial
plumes in the atmosphere, which includes the effects of possible condensation. Of particular concern
is to properly parameterize the entrainment (by turbulent engulfment) of fluid from the inner to the
outer plume and vice versa. We also present and discuss the two different body force formulations that
apply in describing the dynamics of the inner plume. Based on the resulting model predictions, we introduce
a so-called resistance factor, which is defined as the ratio of the average non-dimensional velocity to
the average relative humidity. In the context of visible plume abatement, the resistance factor so defined
specifies the likelihood of fog formation and/or a recirculation of moist air into the plenum chamber. On
the basis of this analysis, we can identify the region of the operating-environmental condition parameter
space where a coaxial plume might offer advantages over its uniform counterpart. -
- Date created
- 2018-10-23
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- Subjects / Keywords
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- Type of Item
- Article (Published)