Generalized Pressure Drop Correlation for Evaporation and Condensation of Alternative Refrigerants in Smooth and Micro-Fin Tube.
Generalized Pressure Drop Correlation for Evaporation
and Condensation of Alternative Refrigerants in Smooth
and Micro-Fin Tube.
Choi, J. Y.; Kedzierski, M. A.; Domanski, P. A.
NISTIR 6333; 67 p. October 1999.
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: PB2000-103119
refrigerants; correlation; friction factor; heat
transfer; hydraulic diameter; microfin tube; pressure
drop; smooth tube; two-phase flow
This paper presents a pressure drop correlation for
evaporation and condensation in smooth and micro-fin
tubes. The correlation was developed from a database
consisting of the following pure and mixed refrigerants:
R125, R134a, R32, R410A (R32/R125 50/50% mass), R22,
R407C (R32/R125/R134a, 23/25/52% mass) and R32/R134a
(25/75% mass). The new correlation was obtained by
replacing the friction factor and the tube-diameter in
the Bo Pierre correlation with a friction factor derived
from pressure drop data for a micro-fin tube and the
hydraulic diameter, respectively. The new correlation
predicted the measured micro-fin data with an average
residual of 10.8%, and it also predicted the pressure
drop in smooth tube with an average residual of 15.0%.
In addition, the correlation was used to predict
pressure drop data for refrigerant/lubricant mixtures by
using a viscosity-mixing rule. As a result, the new
correlation predicted the measured evaporation and
condensation pressure drop data for mixtures of various
lubricants with R12, R22, and R134a with an average
residual of 19.0%.