An Experimental Investigation of Reflux Condensation Phenomena in Multiple U-Tubes With and Without Noncondensible Gas

Abstract

Abstract A series of experiments were performed to investigate the thermal-hydraulic phenomena inside U-tubes in a reflux condensation mode. A total of 512 data for local condensation heat transfer coefficients (108 for pure steam flow and 404 for steam-air flow conditions, respectively) have been obtained for various inlet flow rates of steam and air under atmospheric condition. A new correlation, which includes the effects of flow rates of steam and noncondensible gases (air) on the heat transfer coefficient and is applicable to the reflux condensation mode, has been developed using the concept of degradation factor based on the steam-air experimental results. In addition, the effects of multiple U-tubes with different lengths (i.e., two-long and two-short U-tubes) and noncondensible gases on the onset of flooding during a reflux condensation have been examined.