Heat Transfer During Condensation Inside Small Channels: Applicability of General Correlation for Macrochannels

Prediction of heat transfer during film condensation in mini and microchannels is of much practical interest. No well-verified method for this purpose is available. The applicability of the author’s well-validated general correlation (Shah 2009) for condensation in tubes to small channels is investigated in this paper. A wide range of data for condensation in horizontal micro and mini channels were compared with it. This correlation was found to predict 500 data points from 15 studies on small diameter channels with a mean deviation of 15.9 percent. These data included single round and rectangular channels as well as multiport channels with round and rectangular ports with equivalent diameters from 0.49 to 5.3 mm, 8 fluids, reduced pressures from 0.048 to 0.52, and mass flux from 50 to 1400 kg/m²s. This indicates its applicability to minichannels. However, a large amount of data for diameters from 0.114 to 2.6 mm showed large deviations from this correlation. The discrepancy in the overlapping range of data could be due to difficulties in accurate measurements on small channels.