Dehumidification technology and performance
Adsorption
吸附
Adsorption is an increase in the concentration of a substance at an interface caused by surface forces.
- Aliases
- surface sorption
QUANTITY, SYMBOL AND UNIT
Quantity / objectAdsorption
UnitNot applicable
Definition
Adsorption is an increase in the concentration of a substance at an interface caused by surface forces.
In solid-desiccant dehumidification, water vapour is concentrated at internal and external surfaces of materials such as silica gel, activated alumina or molecular sieve. The adsorbed moisture is later removed during regeneration so the desiccant can be reused.
Relations and distinctions
Adsorption and absorption
Adsorption concentrates material at an interface; absorption involves transfer into the bulk of another phase.
Adsorption and condensation
Adsorption is governed by surface interaction. Condensation is formation of a liquid phase after reaching the relevant thermodynamic condition.
Engineering meaning
- Match the desiccant and regeneration method to the required outlet condition and entering moisture load.
- Protect adsorbent surfaces from contaminants that can reduce accessible capacity or change regeneration behaviour.
Common misconceptions
MisconceptionAdsorption and absorption are interchangeable names for any desiccant process.
Accurate explanationThey describe different physical locations of sorbed material and can require different equipment and regeneration descriptions.
Application boundaries
- The term alone does not specify an adsorption isotherm, usable capacity, kinetics or pressure drop.
- Published material properties must be applied at the stated temperature, pressure, moisture state and contamination condition.
Supporting sources
-
International Union of Pure and Applied Chemistry / SRC-IUPAC-GOLDBOOK-A00155
IUPAC Gold Book, Entry A00155: Adsorption ↗
Compendium of Chemical Terminology online entry / Gold Book entry A00155: adsorption
Supports: Adsorption is an increase in concentration at an interface caused by surface forces; Adsorption is an interfacial rather than bulk-phase process; Gas-to-condensed-phase interfaces are included -
ASHRAE / SRC-ASHRAE-S20-CH24
ASHRAE Handbook - HVAC Systems and Equipment, Chapter 24: Desiccant Dehumidification and Pressure-Drying Equipment ↗
2020 IP edition / Chapter 24, solid adsorbents and adsorption-regeneration equipment
Supports: Solid desiccants such as silica gel, activated alumina and molecular sieve remove moisture by adsorption; Adsorptive desiccants can be regenerated and reused; Heat, dry purge gas or both may reactivate adsorption equipment
Maintenance record
Adsorption
- Maintained by
- Yakeclimate Engineering Team
- Authoritative sources verified
- August 3, 2026
- Terminology checked
- August 3, 2026
- Last updated
- August 3, 2026
- Term ID
- EKS-HUM-080