Free-convection condensation of ammonia/water vapour mixtures on a horizontal smooth tube

The heat tranfer characteristics of free-convection condensation of ammonia/water vapour mixtures on a horizontal tube are investigated. The heat transfer coefficients of ammonia/water vapour mixture are predicted by solving the algebraic equations, and the results show that the heat transfer coefficients of the mixtures are lower than those of the pure components, ammonia and water. Experiments are also performed to investigate the condensation behaviour of the vapour mixture on a horizontal smooth tube over a wide range of mass fraction of each component. The results indicate that the experimental heat transfer coefficients agree well with the theoretically predicted values. Observation of the condensate film reveals the appearance of three types of film, namely, smooth film, stationary ringwise film, and turbulent ringwise film.