Two-phase pressure drop of refrigerants during flow boiling in small channels: an experimental investigation and correlation development

Two-phase flow pressure drop measurements were made during a phase-change h eat transfer process with three refrigerants (R-134a, R-12, and R-113) at s ix different pressures ranging from 138 to 856 kPa, and in two sizes of rou nd tubes (2.46 and 2.92 mm inside diameters) and one rectangular channel (4 .06 x 1.7 mm). The data were compared with those from large tubes under sim ilar conditions, and state-of-the-art correlations were evaluated using the R-134a data. The state-of-the-art large-tube correlations failed to satisf actorily predict the experimental data, The data were used to develop a new correlation for two-phase pressure drop during flow boiling in small chann els. The correlation was then tested against the experimental data for the three refrigerants; the error was +/- 20%. (C) 2000 Elsevier Science Ltd. A ll rights reserved.