Gas Absorption into a Two-layer Film

  • Author: ChemistryViews
  • Published: 10 April 2015
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: AIChE Journal/American Institute of Chemical Engineers
thumbnail image: Gas Absorption into a Two-layer Film

Gas absorption in single-layer falling films has been intensely studied. However, the mass transfer in wavy two-layer films has not been modeled so far. The main difficulty in computing mass transfer is the complexity of solving the hydrodynamical problem to find finite-amplitude wave regimes.


G. Çekiç and G. M. Sisoev, University of Birmingham, UK, have studied the absorption of a weakly soluble gas into a two-layer film flowing down a vertical wall. The analysis is based on an approximate long-wave model generalizing the Kapitza–Shkadov model for a single-layer film. The suggested algorithm for computing the gas absorption into a two-layer falling film contains two steps: (i) computing the hydrodynamical problem for the evolution equations and (ii) solving the diffusion problem. Reducing the full Navier–Stokes problem to the evolution equations is a condiderable improvement, and saves computational resources in finding optimized regimes of absorption. The algorithm can be generalized for other types of two-layer flow, for example flows over a spinning disk.

It was found that wavy regimes in the film strongly affect the absorption rate. Similar to single-film flow, the absorption rate is increased for wavy regimes in comparison with the waveless flow. This amplification takes place at the interface between the liquids as well as at the film surface. Numerous transient computations have demonstrated that the growth of the absorption rate is explained by the nonuniform distribution of the concentration gradient along the film surface and the interface. The largest gradients and thus largest local gas fluxes at the surface and interface are observed at wave troughs, where the thickness of the first layer and the whole film are minimal.


 

Article Views: 1899

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


CONNECT:

ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter


A product of ChemPubSoc Europe (16 European Chemical Societies)and Wiley-VCH