R-22 condensation in flat aluminum multi-channel tubes

In this study, condensation heat transfer tests were conducted in flat alum inum multi-channel tubes using R-22. Two internal geometries were tested; o ne with a smooth inner surface and the other with micro-fins. Data are pres ented for the following range of variables; vapor quality (0.1 similar to0. 9), mass flux (200 similar to 600kg/m(2)s) and heat flux (5 similar to 15 k W/m(2)). The micro-fin tube showed higher heat transfer coefficients compar ed with those of the smooth tube. The difference increased with the vapor q uality. Surface tension force acting on the micro-fin surface at high vapor quality is believed to be responsible. For the smooth tube, the heat trans fer coefficient increased with the mass flux. The heat transfer coefficient of the micro-fin tube, however, was independent of the mass flux, especial ly at high vapor qualities. This implies that, at the high vapor quality, t he 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 modifie d model adequately predicted the data.