Experimental study of the minimum film boiling point for liquid--liquid systems Page: 2 of 5
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A .XPI 1i X!w:TAL SI'TY u' TIlE MINIMUM
FILM 10lL1vJ V1T F118 LIQIDi-LlQ'lt' SYSTUL::
R. E. Henry, D. J. Quinn. and C. A. Sp!,h a
Argonne National Laher.tory, Arttonnt, Illinois
Film boiling data is reported for Freon-l1, Freon-22, ethanol, and water boiling on a mercury surface.
Measured heat flue:ee and heat transfer coeficients are in good agreez.ent with previous, data. However,
transition from film boilinr: occurs it :uca lower t.aperatures th2n would be expected fro: solid-liquid
film boiling results. Fil' boiling of Freon-22 on water wa. attempted but transition occurred at much
higher water te.:pvratures than would be extrapolated from solid-liquid results.
hf: Latent heat of vaporization
H Heat transfer coefficient
Th Temperature of the hot liquid
TSAT: Saturation temperature of the boiling liquid
6 : Time
p : Density of boiling liquid
Extensive analytical and experimental efforts have
provided considerable understanding of the film
boiling process as it relates to film boiling of a
liquid on a hot solid surface. Several specific
problems such as quenching of molten globules,1
cryogenic spills on water,2 and understanding of
'experimental results for vapor explosions2,3 re-
quire a knowledge of film boiling of one liquid on
another, and hence, how the wealth of knowledge on
liquid-solid systems relate to such problems. Thi
study specifically deals with Freons-li and -22,
ethanol, and water globules in film boiling on a
Thu very simple apparatus used in this investigati
Is illustrated in Fig. 1. A mercury pool was heat.
from below, and its bulk temperature was monitored
by an isolated sheathed thermocouple. A globule
of the boiling liquid was placed on the surface and
photograph was taken at t - 0.0 sec. After a
sufficient quantity of the liquid had boiled away,
such that the decrease in planar area was readily
apparent; another photograph was taken and the tie
interval between the two pictures wan recorded. Tf
eliminate any metastable hydradynanic effects such
as those witnessed for small Leidenfrost drops,''
both the initial and final globule dimensions were
large compared to the critical wave length for
Taylor instability5 as evidenced by "bubble
breakthrough" within the liquid mass at both points
tO ...- .
r I L- \ r
aaTNwR m /
SFig. 1 Experimental Apparatus
Following the technique utilized by Borishansky6
and Bradfield,7 an electrical probe was inserted
s into the upper portions of the boiling liquid mass,
but not into the mercury pool. This probe was con-
nected in series with a 1 volt dry cell and a strip
chart recorder, which was connected to the mercury*
pool. Such a system will clearly register if
intimate contact is made between the two liquids.
A 304 stainless-steel retainer ring was floated on
the mercury- pool to keep the boiling liquid in the
vicinity of the contact probe and also away from the
m comparatively cool glass wall.
Thin system, which was housed inside of a vented
hood, could generate mercury temperatures of 275/C.
1 At this temperature, glhe mercury vaporization was
significant. and this combined with the heat flux
required to vaporize the boiling liquid equaled the
maximum output of the hot plate.
r Although the planar dimensions of the boiling
liquids were large compared to the most dangerous
wave length, the thickness of the globule was
determined by its surface tension. The thickness
was read from a scale inserted beside the boiling
mass, and this paraceter is probably the least
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Henry, R.E.; Quinn, D.J. & Spleha, E.A. Experimental study of the minimum film boiling point for liquid--liquid systems, article, January 1, 1974; Illinois. (digital.library.unt.edu/ark:/67531/metadc1026595/m1/2/: accessed October 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.