A Study of the Heat Transfer Characteristics of an FC-72(C6F14) Two-Phase Closed Thermosyphon with Helical Grooves on the Inner Surface

This study is a fundamental work performed to obtain basic information about designing two-phase closed thermosyphons with a working fluid of FC-72 (C₆F₁₄). FC-72 is a kind of alternative refrigerant designed to be chemically safe and more environmentally friendly than any other conventional CFC refrigerants.

To obtain experimental data on operational performances of a FC-72 two-phase closed thermosyphon, an experimental model was designed and manufactured with a micro fin groove copper tube with an outside diameter of 22.2 mm for its container, on which a series of operational performance tests were conducted. Its maximum capacity of heat transport rate was designed to be about 300–400 W. The focus was given to investigate the effects of such parameters as micro fin grooves and fill charge ratios on operational performances of the FC-72 two-phase closed thermosyphon. The experimental data on phase change heat transfer coefficients and heat transport limitations were compared with some corresponding correlations, and a couple of measures that would help to predict operational performances were suggested with some physical explanations.