Simultaneous heat and mass transfer in absorption/desorption of gases in laminar liquid films

A theoretical analysis of the combined heat and mass transfer process taking place in the absorption (or desorption) of a gas or vapor into (or from) a laminar liquid film was described. While this type of process occurs in many gas-liquid systems, the amount of heat released is often small, which makes the process practically isothermal. In some cases, however, the heat of absorption/desorption is significant and temperature variations cannot be ignored. One example, from which the present study originated, is in absorption heat pumps where mass transfer is produced specifically to generate a temperature change. The model analyzed in this study describes a liquid film flowing over an inclined plane, with its free surface in contact with stagnant vapor. The absorption/desorption process at the surface creates non-uniform temperature and concentration profiles in the film, which develop until equilibrium between the liquid and vapor is achieved.