An experimental study of R-11 and R-12 film condensation on horizontal integral-fin tubes

Experimental results on heat transfer during film condensation of stationary pure vapor refrigerants R-11 and R-12 on a smooth tube and on four tubes with transverse ribs of constant curvature are reported. The tubes were manufactured in such a way that the fins and valleys had circumferences of the same radius. All tubes were made of brass. The effect of surface curvature on heat transfer was studied. The heat transfer coefficient on the finned tubes (based upon the smooth tube surface area having the diameter of the fin root) increased in all cases. The maximum enhancement being obtained with the tube having the smallest fin radius. Experimental data have been compared with the theoretical models of condensation on the curvilinear surfaces They have also been processed in dimensionless form.