Experimental analysis of steam condensation in vertical tube with small diameter

Thermal design of tubular heat exchanger based on condensation heat of water steam requires knowledge of condensation heat transfer in the each tube. This paper is just aimed on experimental analysis of steam condensation in vertical copper tube in length of 1285 mm with 2.0 mm inner diameter and 0.5 mm wall thickness. Experimental measurement is performed in 12 steps with variable inlet temperature and mass flow rate of water steam. The heat transfer coefficient on the inner surface of tube in condensation zone is calculated by Thermal resistance method and Wilson plot method. The correlation quality of results obtained from both methods is 98.8%. The results are compared with other experimental studies and also correlated with five chosen equations for prediction of condensation heat transfer coefficient. The correlation quality of results obtained from this experimental analysis and four tested equations is over 96.6%, only theoretically determined Nusselt equation undervalues condensation heat transfer coefficient as is known. The Nusselt equation does not take to account waves on condensate surface. These waves on condensate surface are caused by flow of water steam in tube and the wave's effect is approximately 20.5% in this presented case.