Analytic modelling of a falling film absorber and experimental determination of transfer coefficients

Accurate interpretation of the experimental data on falling film flows is a critical part of the investigations in the field of absorption energy system research. However, there is no theoretically proven way to determine experimental heat and mass transfer coefficients for non-isothermal absorption falling film flows. In this article, firstly, it is shown how the governing equations of a falling film absorber can be reduced to two ordinary differential equations and analytic expressions can be obtained for the temperature and concentration profiles along the absorber. Secondly, a new method is proposed to determine heat and mass transfer coefficients from experimental data and its application is demonstrated by reprocessing the experimental data from two experimental studies reported in the literature. The results show that some of the experimental data were misinterpreted by conventional methods and the errors were negligible only when heat and mass fluxes were small, which agrees with the fact that the obtained analytic solutions approach the conventional logarithmic heat and mass transfer equations in such conditions.