In order to test the heat transfer performance of horizontal doubly-enhanced tubes

a new method called water-ring method was put forward. The basic process was that the annulus side correlation of the smooth heat transfer tube wrapping copper wire spirally was firstly obtained by a series of experiments in the self-designed annular tubes test bench. Then the convective heat transfer resistance of the doubly-enhanced tube with the same form of copper wire could be separated from the total thermal resistance to fit out the heat transfer correlations of the inside tube. The condensation surface heat transfer coefficients of refrigerant R123 and the convection surface heat transfer coefficients of water were measured by using the correlations. The experimental study and theoretical analysis shows that the result using water-ring method is more accurate than the normal thermal resistance separation method.