An Instructive CO<sub>2</sub> Adsorption Model for DAC: Wave Solutions and Optimal Processes

We present and investigate a simple yet instructive model for the adsorption of CO<sub>2</sub> from air in porous media as used in direct air capture (DAC) processes. Mathematical analysis and non-dimensionalization reveal that the sorbent is characterized by the sorption timescale and c...

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Bibliographic Details
Main Authors: Emily Kay-Leighton, Henning Struchtrup
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/26/11/972
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Summary:We present and investigate a simple yet instructive model for the adsorption of CO<sub>2</sub> from air in porous media as used in direct air capture (DAC) processes. Mathematical analysis and non-dimensionalization reveal that the sorbent is characterized by the sorption timescale and capacity, while the adsorption process is effectively wavelike. The systematic evaluation shows that the overall adsorption rate and the recommended charging duration depend only on the wave parameter that is found as the ratio of capacity and dimensionless air flow velocity. Specifically, smaller wave parameters yield a larger overall charging rate, while larger wave parameters reduce the work required to move air through the sorbent. Thus, optimal process conditions must compromise between a large overall adsorption rate and low work requirements.
ISSN:1099-4300