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An improved correlation for two-phase pressure drop of R-22 and R-410A in 180° return bends

Authors
Journal
Applied Thermal Engineering
1359-4311
Publisher
Elsevier
Publication Date
Volume
28
Issue
7
Identifiers
DOI: 10.1016/j.applthermaleng.2007.06.034
Keywords
  • Short Return Bends
  • Two-Phase Pressure Drop
  • Curvature Multiplier
  • π-Correlation
Disciplines
  • Mathematics

Abstract

Abstract A correlation for two-phase flow pressure drop in 180° 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 (2 R/ 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 RMS deviation of 25%, and 75% of the data fall within ±25% error bands.

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