Scaling analysis and numerical studies on water vapour adsorption in a columnar porous silica gel bed

• A novel theoretical approach to analyze adsorption process.
• The derivation of limiting time and length scales in an adsorber.
• Estimation of vapour inflow and pressure drop scales for a given domain size.
• Validation of scaling results with numerical studies.

This article presents a theoretical analysis of heat and mass transfer in a silica gel + water adsorption process using scaling principles. A two-dimensional columnar packed adsorber domain is chosen for the study, with side and bottom walls cooled and vapour inlet from the top. The adsorption process is initiated from the cold walls with a temperature jump of 15 K, whereas the water vapour supply is maintained at a constant inlet pressure of 1 kPa. The first part of the study is dedicated to deriving relevant scales for the adsorption process by an order of magnitude analysis of energy, continuity and momentum equations. In the latter part, the derived scales are compared with the outcome of numerical studies performed for various domain widths and aspect ratio of bed. A good correlation between scaling and simulation results is observed, thereby validating the scaling approach.