A physical model as well as a mathematical model were established to describe and upgrade the "vapor-phase resistance method" suggested by Bell and Ghaly. Considering the effects of ripples at interfaces on vapor-phase resistance

a correction factor Vr was proposed. Another factor (θ/π)β which corrects the influence of the liquid pool along the bottom of the horizontal tube on the liquid-phase heat transfer coefficient was derived and therelationship of θ and β was correlated. A fully established method for calculating the convective condensation heat transfer coefficient was proposed. The heat transfer coefficients predicted by Bells method are approximately 10-15% lower than experimental values as the effect of ripples on vapor-phase resistance was not taken into account. Comparison of the predicted values of he from the modified vapor-phase resistance method with experimental data showed a deviation of ±10%.