Modeling CO₂ Adsorption in a Thin Discrete Packing

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Thin tube packed bed adsorbers are crucial for thermochemical energy storage and atmospheric revitalization.
• Understanding local dynamics of carbon dioxide (CO2) adsorption is vital for optimizing these systems.
• Existing one-dimensional models often rely on empirical dispersion, limiting accuracy.

Purpose of the Study:

• To assess the local dynamics of CO2 adsorption within a discrete packing in a thin tube using 3D modeling.
• To investigate the interplay between exothermicity, fluid flow, and transport mechanisms.
• To compare the effectiveness of advective versus diffusive transport on CO2 breakthrough trends.

Main Methods:

• 3D computational modeling of CO2 adsorption dynamics in a thin tube packed bed.
• Analysis of concentration gradients at inter- and intraparticle scales.
• Comparison of model results with experimental data from adsorber exit.

Main Results:

• Diffusive transport was found to be more effective than advective transport in influencing CO2 breakthrough trends.
• Significant concentration gradients were observed at both inter- and intraparticle levels.
• Reduced mass transfer resistance in high-velocity areas enhanced convective transport into pores, impacting angular symmetry.

Conclusions:

• The 3D modeling approach accurately reflects experimental CO2 adsorption data.
• Diffusive transport plays a more critical role than advection in CO2 breakthrough within these systems.
• Findings reduce reliance on empirical dispersion models in one-dimensional simulations for packed bed adsorbers.