22 May 2002
In this study, condensation heat transfer tests were conducted in flat aluminum multi-channel tubes using R-410A, and the results are compared with those of R-22. Two internal geometries were tested; one with a smooth inner surface and the other with micro-fins. Data are presented for the following range of variables; vapor quality (0.1 ~ 0.9), mass flux (200 ~ 600 kg/m2s ) and heat flux (5 ~ 15 kW/m2). Results show that the effect of surface tension drainage on the fin surface is more pronounced for R-22 than R-410A. The smaller Weber number for R-22 may be responsible. For the smooth tube, the heat transfer coefficient of R-410A is slightly larger than that of R-22. For the micro-fin tube, however, the reverse is true. Possible reasoning is provided considering the physical properties of the refrigerants. For the smooth tube, Akers et al. (1959) type correlation predicts the data reasonably well. For the micro-fin tube, the Yang and Webb (1997) model was modified to correlate the present data. The modified model adequately predicts the data.