Marangoni condensation of steam-ethanol mixtures on a horizontal smooth tube

Experiments were conducted to measure condensation heat transfer of steam-ethanol mixtures on a horizontal smooth tube. Heat flux and vapor-to-surface temperature difference accurately measured over wide range mass concentration ethanol (0.001%, 0.005%, 0.01%, 0.025%, 0.05%, 0.1%, 0.5% 1.0%.) at atmospheric pressure. The present work extends earlier data Murase et al. (2007) Ali (2013) lower higher difference. Visual observations, the appearance condensate, show modes their transitions pseudo-dropwise, rivulets filmwise. heat-transfer coefficient are found increase, reach peak decrease as increases for all concentrations vapor velocities. maximum coefficients appear in from 0.01% 0.025%. highest values 112.4 kW/m2 K 93.9 ΔT = 3.43 4.46 K, respectively. enhancement ratio 5.5 is achieved 4 0.01%. results also that filmwise eventually approaches value slightly than pure steam.