Abo Bibliothek: Guest

ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Experimental Investigation and Prediction of Flooding during Reflux Condensation in a Small Diameter Inclined Tube

Get access (open in a dialog) DOI: 10.1615/IHTC12.5460
6 pages

Abstrakt

In this experimental investigation flooding points are determined during reflux condensation of R134a and steam in an inclined, small diameter tube. The inner diameter of the tube is 7 mm and the cooled length is 500 mm. In addition the condensate film thickness of R134a is measured using the ultrasonic pulse-echo technique before the onset of flooding. The R134a experiments show that the inclination angle has a significant effect on the flooding point. The optimum inclination angle at which the highest flooding vapour velocity occurs is between 45° and 60°. In contrast, due to the much higher surface tension of water such a significant effect cannot be observed in the steam experiments. The experimental flooding data are compared with values predicted by correlations but a satisfying agreement cannot be noticed. A modified form of a flooding correlation by English et al. is proposed for the R134a experiments that is valid for all inclination angles. The derivation of a general correlation for the prediction of flooding during reflux condensation in inclined, small diameter tubes for a wide range of fluid properties appears to be difficult. The condensate film thickness data that have been obtained with the pulse-echo technique give information about the distribution of the condensate film in the inclined tube. This might be helpful for obtaining a more general flooding correlation for reflux condensation in inclined, small diameter tubes.