ISSN Online: 2377-424X
ISBN Print: 1-56032-797-9
International Heat Transfer Conference 11
CONDENSATION HEAT TRANSFER IN SMALL DIAMETER TUBES
Résumé
Small diameter tubes (e.g. 1.0 to 7.0 mm), including copper tubes and multi-port extruded aluminum tubes are finding increasing usage in air-conditioning applications. Previous work by Moser et al. [ 1997 ] validated the Shah [ 1979 ] correlation for copper tubes with diameters down to 3.14 mm while Yang et al. [ 1996a ] showed that the Shah correlation over-predicted condensation in multi-port aluminum tubes of hydraulic diameter smaller than 2.6 mm by more than 50 %. This paper compares R-134a condensation heat transfer and pressure drop in small diameter copper tubes and in multi-port aluminum tubes. Comparisons of experimental data with existing models reveal that at a saturation temperature of 40 °C, both the Shah and the Friedel [ 1979 ] correlations give good agreement with the experimental condensation heat transfer coefficient and pressure drop respectively, in both types of tubes. However at 65°C saturation temperature, the same correlations over-predict the experimental values. However for both conditions, the equivalent Reynolds number model was found to predict the condensation coefficient well for both tubes. This work is also applicable for a wide range of tube geometries.