Experimental and theoretical study of surface tension effects on extended surface condensation.

摘要

The goal of this dissertation is to contribute to and build upon the existing knowledge and understanding of the effects of surface tension on the condensation of refrigerants on low-finned tubes. To this end, the project goals were to: (1) measure the heat transfer of a variety of refrigerants (R-123, R-245fa, and R-134a) on an early-model enhanced heat transfer surface (GEWA-K™); (2) measure the heat transfer of these same refrigerants on a more recently developed heat transfer surface (Turbo-CII™); (3) compare these experimental data to the heat transfer model of Rose (1994); and (4) extend the Rose model for these refrigerants and heat transfer surfaces through the selection/creation of appropriate empirical/analytical constants; and, (5) depending on the success or failure of item (4), propose a new model based on the Rose model that expands its validity to the Turbo-CII™ surface.; The significant contributions of this work are: (1) it provides experimental heat transfer data of R-245fa on two enhanced heat transfer surfaces (Note: there is very little prior data in the open literature for R-245fa on any type of heat transfer surface); (2) it provides experimental heat transfer data of several refrigerants on the Turbo-CII™ surface (Note: there is very little data in the open literature for any refrigerant on this enhanced surface); (3) it validates the Rose (1994) model for these refrigerants and heat transfer surfaces; and, (4) it develops a new heat transfer model for condensation of refrigerants on low-finned tubes.