Improved Correlation for Two-Phase Pressure Drop of R-22 and R-410A in 180DG Return Bends.
Improved Correlation for Two-Phase Pressure Drop of R-22
and R-410A in 180DG Return Bends.
Domanski, P. A.; Hermes, C. J. L.
Thermal Sciences and Engineering, 11th Brazilian
Congress. ENCIT 2006--ABCM. Proceedings. December 5-8,
2006, Curitiba, Brazil, 2006.
pressure drop; short return bends; two-phase pressure
drop; curvature multiplier; Buckinhan-PI theorem;
A new correlation for two-phase flow pressure drop in
180DG return bends is proposed based on a total of 241
experimental data points for R-22 and R-410A from two
independent studies. The data span smooth tubes with
inner diameters (D) from 3.3 mm to 11.6 mm, bend
radiuses (R) from 6.4 mm to 37.3 mm, and curvature
ratios (2R/D) from 2.3 to 8.2. The correlation consists
of a two-phase pressure drop for straight tubes and a
multiplier that accounts for the bend curvature. The
Buckinham-PI Theorem was used to formulate the curvature
multiplier in terms of refrigerant properties, flow
characteristics, and bend geometry. The correlation
predicts all data with a mean deviation of 15.7%, and
75% of the data fall within - 25% error bands.