Effect of inclination on heat transfer in large flattened-tube steam condensers

An experimental study of convective steam condensation inside a large, inclined, flattened-tube air-cooled condenser for power plants is presented. This is the second of a two-part study. The first part presents pressure drop and visualization results, while this study presents the experimental method along with heat transfer results. The condenser in this study is steel with brazed aluminum fins. The condenser measures 10.72m in length, with a cross section of 214 mm x 18 mm. The condenser tube was cut in half lengthwise and covered with a polycarbonate viewing window in order to provide visualization access simultaneously with the heat transfer measurements. Inlet steam mass flux ranged from 6.2 - 9.5 kg m-2 s-1, and condenser capacity varied from 25 - 31 kW. The angle of inclination was varied from horizontal to 75o downward. The experiments were performed with a uniform fin-face velocity of crossflowing air at 2.2 m/s. Condenser capacity was found to increase linearly with increasing downward inclination angle of the condenser, at a rate of 0.048% per degree of inclination below horizontal. This improvement was found to be the result of improved drainage and increased void fraction near the condenser outlet.