In this study, condensation heat transfer coefficients of R-410A
were obtained in flattened tubes (AR = 2, 4, 6) made from 5.0 mm
inner diameter round tubes. The test range covered saturation
temperature 45C, mass flux 100400 kg/m2s and quality
0.20.8. Listed below are major conclusions.
(1) The effect of aspect ratio on condensation heat transfer coefficient
appears to be dependent on the flow pattern. For
annular flow, the heat transfer coefficient increases as aspect
ratio increases. For stratified flow, however, the heat transfer
coefficient decreases as aspect ratio increases.