Film Condensation of R-11 Vapor on Single Horizontal Enhanced Condenser Tubes

The heat transfer performance of R-11 vapor condensing on single horizontal trapezodially shaped integral-fin tubes has been investigated by systematically varying the fin density, the semi-vertex angle, and the fin height. For the nine copper tubes tested, the best performance has been obtained with a tube having a fin density of 1417 fpm, a semi-vertex angle of 10 deg, and a fin height of 1.22 mm. This tube has yielded a maximum value of the heat transfer coefficient of 16,500 W/m² K at a ΔT of about 3 K, corresponding to an enhancement ratio of 10.3. The performance of the tube has been further improved by fabricating from it “specially enhanced” tubes having axial grooves of varying height. An enhancement ratio of 12.3 has been obtained with this type of tube.