An experimental investigation of enhanced tubes for steam condensers

The objective was to identify an enhanced tube for use in steam condensers. A set of commercially available enhanced tubes was tested to determine the enhancement level relative to a plain tube. The tubes have different fin size, shape, spacing, and material. Steam was condensed under vacuum conditions (54 C) and the steam side condensing coefficient was determined. The tube wall temperature was measured for each tube at three different circumferential positions. The apparatus and experimental procedure are described. The results show that the condensation coefficient was enhanced (relative to a plain tube of diameter equal to the diameter over the fins for the enhanced tube) 34%, 75%, and 280% for titanium, copper-nickel, and copper, respectively. Based on the results of this study and correlations for the tube side heat transfer coefficient, the overall heat transfer coefficient of a set of doubly enhanced tubes (internal and external enhancement) were determined at operating conditions that typically occur in electric utility steam condensers. The tubes were made of copper-nickel and titanium. The overall heat transfer coefficients were calculated at a saturation temperature of 54 C and 2.0 m/sec cooling water velocity. The maximum enhancement in the overall heat transfer coefficient, at 2.0more » m/sec is 80% and 58% for the copper-nickel and titanium tubes respectively. 26 refs., 9 figs., 7 tabs.« less