Analytical description of falling film absorption

Absorption represents an opportunity towards clean and efficient energy conversion systems. However, the attempt to characterize heat and mass-transfer performance of this process is still incomplete. The attainment of numerical solutions and empirical correlations can be a time-consuming procedure. Also, their information content is limited to the specific operative circumstances fixed each time as boundary or experimental conditions. Furthermore, the increased complexity of absorption devices makes detailed calculation very difficult or impossible and the physical content obscure. Under this point of view, properly simplified analytical models have obvious advantages. An analytical model for horizontal tube falling film absorbers and a detailed investigation of heat and mass transfer performance are hereby presented. Moreover, by means of the inclusion of a partial wetting model at reduced solution mass flowrates, the characterization of falling film absorbers can be extended to a wider range of operative conditions. The paper performs a parametric analysis of the model in order to study exhaustively the dependence of the solution on geometrical and operative parameters for actual applications' design and control. Different correlated phenomena have been described pointing out how to maximize heat and mass transfer performances of the system.