Prediction of heat transfer during condensation in inclined plain tubes

• Literature on heat transfer during condensation in inclined tubes is reviewed.
• A method for calculating heat transfer in inclined tubes is presented.
• A database of all published data for condensation in inclined tubes was prepared.
• The proposed method has a mean absolute deviation of 15.7% with the database.
• It is the only well-verified method for condensation in inclined tubes.

Condensation in inclined tubes occurs in many applications, but no verified method for predicting heat transfer is available. This study was undertaken in an attempt to find a method for predicting heat transfer during co-current vapor–liquid flow; thus reflux condensation was excluded. Published experimental studies were reviewed. A method to predict heat transfer is proposed in which a new model for the effect of inclination is used together with a well-verified general correlation for condensation in tubes. The proposed method was compared to a wide-ranging database. The range of data analyzed included inclinations from −90 to +90°, diameters from 1.23 to 14.81 mm, reduced pressures from 0.0065 to 0.427, mass flux from 11.2 to 699 kg/m2s, and 8 fluids that include water, chemicals, and refrigerants. The deviations of inclined tube data were about the same as those of horizontal and vertical down data. All 669 data points were predicted with a mean absolute deviation of 15.7%.