Cooling tower plume abatement using a coaxial plume structure

S. Li
2018
7 The traditional approach of cooling tower plume abatement is supposed to result in an un-8 saturated, well-mixed plume with a "top-hat" structure in the radial structure, but this is an 9 idealization that is rarely achieved in practice. Meanwhile, previous analyses have shown that 10 there may be an advantage in specifically separating the wet and dry air streams whereby the 11 corresponding plume is of the coaxial variety with dry air enveloping (and thereby shielding) an 12 inner core of
more » ... 12 inner core of wet air. Given that a detailed understanding of the evolution of coaxial plumes is 13 presently lacking, we derive an analytical model of coaxial plumes in the atmosphere, which in-14 cludes the effects of possible condensation. Of particular concern is to properly parameterize the 15 entrainment (by turbulent engulfment) of fluid from the inner to the outer plume and vice-versa. 16 We also present and discuss the two different body force formulations that apply in describing 17 the dynamics of the inner plume. Based on the resulting model predictions, we introduce a 18 so-called resistance factor, which is defined as the ratio of the average non-dimensional velocity 19 to the average relative humidity. In the context of visible plume abatement, the resistance factor 20 so defined specifies the likelihood of fog formation and/or a recirculation of moist air into the 21 plenum chamber. On the basis of this analysis, we can identify the region of the operating-22 environmental condition parameter space where a coaxial plume might offer advantages over its 23 uniform counterpart. 24 25
doi:10.7939/r32805f23 fatcat:hsujtpxzbzh4nlvcsqkukh2eva