Numerical analysis of different mass transfer models for falling film absorbers

• Published in: International journal of heat and mass transfer Vol. 182; p. 121892
• Main Authors: Arroiabe, P.F., Martinez-Agirre, Manex, Mounir Bou-Ali, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2022; Elsevier BV
• Subjects: Absorbers; Absorption; Diffusion rate; Equilibrium conditions; Falling; Falling film; Heat and mass transfer; Lithium-bromide; Mass transfer; Mathematical models; Numerical analysis; Numerical models; Two dimensional models; Falling film; Lithium-bromide; Absorption; Numerical analysis; Heat and mass transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2021.121892

•The impact of absorption determination methods for LiBr−H2O is analysed via CFD.•The employed methodology considerably changes falling film absorption performance.•Fick method is more sensitive than Higbie to interface’s mass fraction variations.•Fick 1D without imposition approach shows best agreement with experimental results. [Display omitted] 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.