R-22 Condensation in Flat Aluminum Multi-Channel Tubes

Abstract

In this study, condensation heat transfer tests were conducted in flat aluminum multichannel tubes using 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 ∼ 15kW/m2). The micro-fin tube showed higher heat transfer coefficients compared with those of the smooth tube. The difference increased with the vapor quality. Surface tension force acting on the micro-fin surface at high vapor quality is believed to be responsible. For the smooth tube, the heat transfer coefficient increased with the mass flux. The heat transfer coefficient of the micro-fin tube, however, was independent of the mass flux, especially at high vapor qualities. This implies that, at the high vapor quality, the surface tension force on the fin is dominant over vapor shear. The 1997 Yang and Webb model was modified to correlate the present data. The modified model adequately predicted the data.