Effect of fin geometry on condensation heat transfer and condensate flow modes of R245fa on horizontal enhanced surface tubes.

The present study experimentally investigated the condensation heat transfer characteristics, condensate flow modes, and condensate flooding angles of R245fa on horizontal microscopic-grooved tubes. Microscopic-grooved tubes with tube diameters of approximately 19 mm at the fin tip were used as the test tubes. This experiment were observed that three condensate flow modes — droplet mode, droplet-column mode, and column mode. The transition film Reynolds number of the condensate flow mode of the low-finned tubes was different from that of the condensate flow mode of the microscopic-grooved tubes. The condensation heat transfer characteristics of the low-finned and microscopic-grooved tubes were experimentally investigated to clarify the effects of fin geometries on the condensate flow mode, condensate flooding angle and condensation heat transfer.