Flow pattern, heat transfer and pressure drop in flow condensation part I: Pure and azeotropic refrigerants
2000 (English)In: HVAC & R RESEARCH, ISSN 1078-9669, Vol. 6, no 2, 175-195 p.Article in journal (Refereed) Published
This study concerns the flow pattern, heat transfer, and pressure drop for flow condensation. The experimental results are recorded in tests with a smooth horizontal tube of 6 mm inner diameter and 2 to 10 m long. This manuscript, which is part I of a two part series, focuses on pure and azeotropic fluids. Part II describes results with non-azeotropic refrigerant mixtures. A flow pattern map by Tandon et al. (1982) roughly predicts flow patterns associated with pure and azeotropic fluids in this work. However, the Froude number is found to be a good additional indicator to identify transition between annular and wavy flows. The transition occurs mostly at Fr = 15 to 20 for both pure and azeotropic fluids. In the case of pure and azeotropic fluids, the hear transfer coefficient was found to be independent of the mass flux in wavy flow regions, but increased with an increasing mass flux in the annular flow regions. For pure and azeotropic fluids, a modified Tandon et al. correlation agreed best with experimental data from tests with R-12, R-22, R-134a, and R-502. For the local pressure drop it is correlated within +/-15% by using the Lockhart-Martinelli parameters. The experimental data for pure and azeotropic refrigerants can be predicted by using a correlation for overall pressure drop.
Place, publisher, year, edition, pages
2000. Vol. 6, no 2, 175-195 p.
IdentifiersURN: urn:nbn:se:kth:diva-19688ISI: 000086531300005OAI: oai:DiVA.org:kth-19688DiVA: diva2:338380
QC 201005252010-08-102010-08-10Bibliographically approved