There has been considerable research on the condensation of multicomponent vapors. The most recent practical motivation for this has been the development of new thermodynamic cycles such as Kalina cycles that employ ammonia-water mixtures as working fluids. It has been widely reported that vapor mixtures generally condense at a slower rate than pure mixtures. This lower heat transfer is generally attributed to there being a mass diffusion layer between the bulk vapor and the surface of the condensate film. This vapor film creates an additional resistance to the condensation process. Although the above effect can be modified by vapor velocities and finned tubes, the reduction nevertheless appears unavoidable. This conclusion must, however, be limited to studies where the condensate film is smooth and laminar. While this condition readily facilitates modelling of the binary condensation problem, it ignores the potential of binary vapors to have different condensation behaviors not possible with pure vapors. The condensation of binary vapors may be influenced significantly by Marangoni effects, i.e. by surface tension gradients, which may occur in liquid mixtures where there are local perturbations in concentration and temperature.
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