Frictional performance of R-22 and R-410A inside a 5.0 mm wavy diameter tube

Chi-Chuan Wang*, Ing Youn Chen, Horng Jye Shyu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The influence of return bend on the frictional performance of R-410A and R-22 in a 5-mm diameter tube is examined with a curvature ratio of 6.63. The existing single-phase correlations give fairly good agreements with the present single-phase data, but the existing two-phase correlations of the return bend fail to predict the present two-phase data. For test results of the two-phase flow at G⩾200 kg m−2 s−1, ((dP/dz)c/(dP/dz)s) is approximately equal to 1.8 and is relatively independent of the vapor quality x. However, at a smaller mass flux of 100 kg m−2 s−1, ((dP/dz)c/(dP/dz)s) decreases with x, reaching approximately 5 for x=0.1. The significant increase of this ratio for G increased from 100 to 200 kg m−2 s−1 may be attributed to the change of the two-phase flow pattern.
Original languageEnglish
Pages (from-to)755-760
Number of pages6
JournalInternational Journal of Heat and Mass Transfer
Issue number4
StatePublished - 1 Feb 2003

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