Horizontal Convective Condensation of Alternative Refrigerants Within a Micro-Fin Tube.
Horizontal Convective Condensation of Alternative
Refrigerants Within a Micro-Fin Tube.
Kedzierski, M. A.; Goncalves, J. M.
NISTIR 6095; 75 p. December 1997.
Enhanced Heat Transfer, Vol. 6, 161-178, 1999.
Sponsor:Department of Energy, Washington, DC
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: PB98-122971
heat transfer; enhanced heat transfer; microfin;
refrigerants; refrigerant mixtures; fluid heating;
condensation; pressure drop
This paper presents local convective condensation
measurements for four refrigerants: R134a,
R410A(R32/R125, 50/50% mass), R125 and R32 in a
micro-fin tube. Both heat transfer and pressure drop
measurements are provided. The heat transfer
degradation associated with R410A was shown to be
relatively small and believed to be mostly due to
nonlinear property effects. The measured convective
condensation Nusselt numbers for all of the test
refrigerants were correlated to a single expression
consisting of a product of dimensionless properties.
The correlation was shown to predict some existing data
from the literature within acceptable limits. The
correlation poorly predicted the heat transfer
performance of cross-grooved, micro-fin tubes. the
pressure drop measurements for the micro-fin tube were
predicted satisfactorily by an existing correlation for
flow boiling pressure drop in a smooth tube.
Correlation of the pressure drop measurements suggested
that the heat transfer enhancement was due to the fins
behaving as a surface roughness.