Convective Boiling and Condensation Heat Transfer With a Twisted-Tape Insert for R12, R22, R152a, R134a, R290, R32/R134a, R32/R152a, R290/R134a, R134a/R600a.
Convective Boiling and Condensation Heat Transfer With a
Twisted-Tape Insert for R12, R22, R152a, R134a, R290,
R32/R134a, R32/R152a, R290/R134a, R134a/R600a.
Kedzierski, M. A.; Kim, M. S.
NISTIR 5905; 95 p. January 1997.
New Approach Toward Low-Temperature Thermal Engineering
Without Fluorocarbon Refrigerants, 45th. Oji
International Seminar. Proceedings. September 16-19,
1997, Tomakomai City, Japan, 223-232 pp, 1998.
Thermal Science and Engineering, Vol. 6, No. 1,
Available from: National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
1-800-553-6847 or 703-605-6000;
Order number: PB97-140594
azeotropes; flow boiling; in-tube condensation; twisted
tapes; enhanced heat transfer; refrigernant mixtures;
Measured, local-average Nusselt numbers (Nu) for
in-tube, convective boiling and condensation with a
twisted-tape insert are presented for: R12, R22, R152a,
R134a, R290, R32/R134a, R32/R152a, R290/R134a, and
R134a/R600a. The heat transfer data were obtained from
a fluid heated/fluid cooled, 9.7 m long condenser and
evaporator of a breadboard refrigeration cycle.
Convective-boiling, heat-transfer data were taken for
transition and turbulent all-liquid Reynolds numbers.
Convective-condensation, heat-transfer data were taken
for laminar and turbulent all-liquid Reynolds numbers.
The measured convective boiling and condensation Nusselt
numbers for the single component and the azeotropic
mixtures were each correlated to a single expression
consisting of a product of dimensionless properties.
The single component convective-boiling correlation was
modified to predict the zeotropic mixture data. The
predictions obtained from the modified flow-boiling
correlations found in the literature were significantly
different from the present Nusselt number measurements.
Presumably, the correlations from the literature could
account for neither the partial dryout induced by the
tape nor the bubbly-mist flow introduced by an expansion