Evaporation of liquid mixtures in laminar flow

Laminar film evaporation of a volatile liquid mixture in the presence of an inert gas is formulated and analysed in this work. The analysis incorporates multicomponent diffusion in the vapor-gas region, taking into account interaction among fluxes of different species. Evaporation of a film flowing over both an insulated and a heated surface is considered. The effect of forced convection of the inert atmosphere is also considered. A non-similarity solution is obtained using a marching technique. However, the starting point is a similarity solution for semi-infinite liquid films, which by itself serves as a good approximation for films of finite thickness. As an example, the problem of the evaporation of a liquid film mixture of methanol and water into air is solved. Rates of evaporation and temperature drop are reported for a wide range of inlet liquid temperatures and concentrations for the case of stagnant air and for the case when forced convection is effective.