Universal approach to predicting saturated flow boiling heat transfer in mini/micro-channels - Part I. Dryout incipience quality

This two-part study concerns the development of a generalized approach to predicting both Nucleate Boiling dominated and Convective Boiling dominated heat transfer in mini/micro-channel flows. Both heat transfer regimes exhibit substantial reduction in the heat transfer coefficient at the location of partial annular liquid film dryout, hence the need to ascertain the occurrence of this important transition point. This first part of the study concerns the development of a correlation for dryout incidence quality. This goal is accomplished by first amassing a consolidated database consisting of 997 dryout data points for mini/micro-channels from 26 sources. The database includes 13 different working fluids, hydraulic diameters from 0.51 to 6.0 mm, mass velocities from 29 to 2303 kg/m(2) s, liquid-only Reynolds numbers from 125 to 53,770, Boiling numbers from 0.31 x 10(-4) to 44.3 x 10(-4), and reduced pressures from 0.005 to 0.78. The new dimensionless correlation is comprised of Weber, Capillary and Boiling numbers, reduced pressure, and density ratio. The correlation shows good predictions of the entire database, evidenced by an overall MAE of 12.5%, and 93.6% and 98.0% of the predictions falling within +/- 30% and +/- 50% of the data, respectively. The predictive accuracy of the new correlation is also fairly even for the 13 different working fluids, and over broad ranges of all relevant parameters. (C) 2013 Elsevier Ltd. All rights reserved.