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Generalized Pressure Drop Correlation for Evaporation and Condensation of Alternative Refrigerants in Smooth and Micro-Fin Tube.


pdf icon Generalized Pressure Drop Correlation for Evaporation and Condensation of Alternative Refrigerants in Smooth and Micro-Fin Tube. (1731 K)
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.
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Order number: PB2000-103119

Keywords:

refrigerants; correlation; friction factor; heat transfer; hydraulic diameter; microfin tube; pressure drop; smooth tube; two-phase flow

Abstract:

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%.