Interface temperature of condensate for binary mixtures

An experiment on Marangoni condensation of binary mixtures was made on non-isothermal vertical surface. The experimental result shows that with the increase of vaporto-surface temperature difference, the condensation curves of heat transfer coefficient reveal nonlinear characteristics and have peak values. There was the highest heat transfer coefficient at an ethanol vapor concentration of 1%. Interface temperature was presented on grounds of theory of laminar film condensation of binary mixtures for theoretical calculation of heat transfer coefficient. The calculation shows that when vapor-to-surface temperature difference interface is zero, interface temperature equal vapor phase temperature for concerned concentration. Interface temperature decrease gradually with increasing vapor-to-surface temperature difference until it reach liquid phase temperature and keep constant. For the same concentration, the greater the vapor velocity is, the higher is the corresponding vapor-to-surface temperature difference which reach liquid phase temperature, and the vapor-to-surface temperature difference decrease with increasing vapor pressure. The calculation of interface temperature provides the possibility to carry out theoretical calculation for heat transfer coefficient.