Augmentation of Horizontal In-Tube Condensation of Steam.

摘要

The complete condensation of low pressure steam inside smooth and augmented horizontal tubes has been experimentally investigated. Smooth tubes were tested to establish reference conditions and to check existing in-tube condensation heat transfer predictive methods. Inclined tubes, twisted-tape inserts, and internally finned tubes were tested as passive techniques to augment condensation. Tube inclination (plus or minus 10 degrees) produced only modest improvements in heat transfer. Twisted tapes with pitch-diameter ratios of 3.8 and 7.0 (diameters/180 degrees twist) were tested and found to increase heat transfer coefficients by as much as 30 percent above the empty tube values on a nominal area basis. Four internally finned tubes were also tested. They produced increases in heat transfer coefficients as much as 150 percent above the smooth tube values.