Numerical analysis of different mass transfer models for falling film absorbers

Different methodologies have been used in the literature to determine the absorbed vapour mass flux in falling film absorbers. So far, however, there has been little discussion about the impact of different approaches in the numerical models' performance. This study compared different methods for considering absorption in LiBr - H2O vertical tube-type falling film absorbers operating at both inlet subcooling and equilibrium conditions. This comparison was made based on three different criteria: the way of considering the absorption, the method to determine the absorption rate, and the assumption of the existing type of diffusion at the interface. The influence of the methodology was demonstrated using 2D multiphase CFD model. The effect of different operating conditions on the methods was also examined. Finally, the results of the numerical models were compared with three experimental works, and the most suitable model was chosen, which properly agrees with them. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Various methodologies for determining absorbed vapour mass flux in falling film absorbers have been compared in this study. Three specific criteria were used to evaluate the methods and select the most suitable numerical model for LiBr-H2O absorbers in vertical tube-type falling film absorbers.