An experimental study on R22 film condensation on single horizontal tubes(one smooth tube and two doubly enhanced ones) was conducted at the saturation temperatures of 32℃, 35℃ and 38℃ respectively. A modified Wi lson plot was used to obtain the water-side and vapor-side heat transfer coeff icients. The results indicated that the experimental condensation heat transfer coefficients agreed with the Nusselt theory with ±10%. The water side heat tr ansfer coefficients of tube No.1 and tube No.2 were 2.78 and 2.99 times of t hat of smooth tube, respectively. At the same heat flux the condensation heat t ransfer coefficients of tube No.1 and tube No.2 were 8.2—18.0 times and 8. 1—12.4 times of the smooth tube, respectively. Thermal resistance analysis sh owed that the relative percentage of vapor-side thermal resistance increased wi th water velocity. When the thermal resistance values of the two sides were equ al, the water velocity of tube No.1 was 1.25 m·s-1(Re=2.41×104) and that of No.2 was 0.82 m·s-1(Re=1.54×104).For all cases, th e wall thermal resistance was less than 4 percentage. The reasons accounting fo r the superiority of tube No.1 were analyzed.
