Multi-factorial study of the absorption process of H2O(vap) by a LiBr(aq) in a horizontal tube bundle using 2-ethyl-1-hexanol as surfactant

This paper presents the results of a series of experimental tests about the absorption of water vapour by an aqueous lithium bromide solution over a bundle of 14 smooth tubes, using an alcohol (2-ethyl-1-hexanol) as surfactant. It follows the same multi-factorial methodology used in a previous article, in order to compare with the experiences without the alcohol. The study reveals that the 2-ethyl-1-hexanol strongly affects the hydrodynamics and the heat and mass transfer as is already known. However, new insight about the absorption process is gained by comparing our experiences with less common theoretical works on falling film stability where some parallelisms are identified. As a result, the main parameters that control this dynamic process seem to be the Marangoni number and also the Reynolds number, as many authors would point out as obvious. But it is much less obvious, that they do interact with each other to create a stability window and to determine the pattern of the flow and therefore the mass transfer rate. Finally in the conclusions a comment on how this could be used in practice is also done and some further research proposed, as for instance, the implication, or not, of the Soret effect in the inter-phase dynamics of the surfactant (2-ethyl-1-hexanol in our case) for aqueous lithium bromide solutions.