Enhancement of R123 Pool Boiling by the Addition of Hydrocarbons.
Enhancement of R123 Pool Boiling by the Addition of
Hydrocarbons.
(1583 K)
Kedzierski, M. A.
NISTIR 6244; 49 p. October 1998.
International Journal of Refrigeration, Vol. 23,
89-100, 2000.
Available from:
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Order number: PB98-172596
Keywords:
additives; binary mixtures; enhanced heat transfer;
fluid heating; hydrocarbons; pool boiling; refrigerants;
surfactants
Abstract:
This paper presents pool boiling heat transfer data for
ten different R123/hydrocarbon mixtures. The data
consisted of pool boiling performance of a GEWA-T
surface for pure R123 and for ten dilute solutions of
five different hydrocarbons: (1) pentane, (2)
isopentane, (3) hexane, (4) cyclohexane, and (5) heptane
with R123. The heat flux and the wall superheat were
measured for each fluid at 277.6 K. A maximum (19 +
3.5)% increase over the pure R123 heat flux was achieved
with the addition of 0.5% mass isopentane to R123. Other
mixtures of isopentane, pentane, hexane, and cyclohexane
with R123 exhibited smaller maximums than that of the
R123/isopentane (99.5/0.5) mixture. Presumably, a layer
enriched in hydrocarbon at the heat transfer surface
caused the heat transfer enhancement. Conversely, an
R123/heptane (99.5/O-5) mixture and an R123/cylcohexane
(99.5/0.5) mixture exhibited only degradations with
respect to the pure component performance for all test
conditions. Several characteristics of the hydrocarbons
were examined to determine their influence on the
boiling heat transfer performance: molecular weight,
molecular structure, composition, surface tension, and
vapor pressure.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899