Entrainment rate of droplets in the ripple-annular regime for small vertical tubes Page: 10 of 28
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first extraction. The present data are limited to the ripple-annular regime. The range of the
data are shown in the flow regime map on Figure 3.
One of the main objectives of the present work is to extend the range of the data to
higher gas flows and pressures. In the case of the air-water experiment this was achieved
by running very high air flows and by pressurizing the loop. The range of air-water data
presented is pf jj from 5.5 to 290 kg/ms2 and p. jY from 480 to 45000 kg/ms2. The
range of pressures is between 140 and 660 kPa. The ranges are listed in Table 1. Further
data were obtained at higher liquid flow rates, but either the deposition and entrainment
mechanisms change in the wispy-annular regime or the extraction probe technique could
not remove the whole film effectively. Either way it was not possible to match these data
with the rest and therefore they are not presented.
Table 1. Range of Air/Water DataParameter Unit Range
Air flow kg/sec 0.0028 - 0.028
Water flow kg/sec 0.0053 - 0.038
r m/sec 0.074-0.54
jm r/sec 10.7 - 126
Pressure kPa 140 - 660In order to scale annular steam/water flow at high pressures and temperatures,
Freon has been shown to be one of the best fluids available. The range of the present
Freon-113 data is: 3.0 <p, j < 160 and 1000 <p2 j2 < 19500 . The range of pressures
is between 250 and 500 kPa. The ranges are listed in Table 2. Like in the air-water case
further data were obtained at higher liquid flow rates but they did not match the rest.
Furthermore data were also obtained at 1 MPa and none of these data match the present
theory. This is attributed to the very low surface tension of Freon-113 at these conditions
(see Table 3) and presumably the flow becomes wispy-annular at very low liquid flows.
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Lopez de Bertodano, M.A.; Assad, A. & Beus, S.G. Entrainment rate of droplets in the ripple-annular regime for small vertical tubes, article, June 1, 1998; West Mifflin, Pennsylvania. (https://digital.library.unt.edu/ark:/67531/metadc706213/m1/10/: accessed June 3, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.