EFFECT OF SURFACTANT ON FALLING FILM ABSORPTION

Absorption of vapour into a falling film of absorbent solution is frequently used for absorption heat pumps and chemical processes. For an improvement in absorption rate, a small amount of surfactant is added to the solution. In the present research, processes of heat and mass transfer are experimentally investigated for the case of water vapour absorption into aqueous solutions of lithium bromide flowing on a flat plate. Variables considered are flow rate of inlet solution, concentration of additive and inclination angle of the plate. The use of 2-ethyl-1-hexanol as an additive results in a four- to five-fold enhancement in absorption rate. The occurrence of surface disturbances does not have a direct relation to the solubility limit of the additive. A qualitative discussion of additives in the role of inducing surface disturbances is presented.