Fundamentals and applications of CFD technology on analyzing falling film heat and mass exchangers: A comprehensive review

Falling film driven by gravity finds wide application in various industry areas, such as refrigeration, chemical engineering and desalination. The liquid film flows along the solid wall and gets contact with the gas phase, and heat and mass transfer occur due to the temperature and concentration gradients. To get the detailed profiles of flow, temperature and concentration and to explore the transport mechanism of falling film multiphase flow, researchers have adopted the Computational Fluid Dynamics (CFD) method for different attempts. The present review gives a comprehensive summarization of the CFD simulation work aided by the commercial software or in-house code concerning the coupled hydrodynamic, heat and mass transfer characteristics in falling film components, including the fields of carbon dioxide capture/chemical absorption, distillation/desalination and evaporation/condensation. The mathematical foundation for the description of falling film flow was introduced firstly. After the presentation of different mass transfer models for the calculation of interfacial heat and mass transfer source term, the previous CFD simulation studies on the abovementioned fields were reviewed respectively. Finally, some conclusive remarks were stated and suggestions for future work were given as well. The present review provides a comprehensive and meaningful guidance for the CFD simulation of falling film flow in various industry application fields.