EKS-HUM-033 / Dehumidification technology and performance
Process Air
处理空气
Process air is the airstream that passes through a dehumidifier to have water vapour removed for use in a space or industrial process.
- Aliases
- process airstream, air to be dehumidified
QUANTITY, SYMBOL AND UNIT
Quantity / objectProcess-air stream
Symbolṁ_p, Q_p
SIkg_da/skilogram of dry air per second
Commonm³/scubic metre per second
Definition
Process air is the airstream that passes through a dehumidifier to have water vapour removed for use in a space or industrial process.
Its entering and leaving temperature, humidity ratio, pressure and mass flow define the process-side duty. In rotary desiccant equipment it is physically separated from the regeneration airstream by sectors and seals.
Relations and distinctions
Process air and regeneration air
Process air is dried for use; regeneration air restores the desiccant and normally leaves carrying additional moisture.
Process air and room air
Process air may be outdoor, return, mixed or once-through air. It is not automatically identical to the room condition.
Engineering meaning
- State process-air inlet and required outlet conditions together with mass flow and pressure.
- Use dry-air mass flow and humidity-ratio difference to calculate process-side moisture removal.
Common misconceptions
MisconceptionProcess airflow alone states the capacity of a desiccant dehumidifier.
Accurate explanationCapacity also requires entering and leaving moisture states and depends on regeneration and equipment conditions.
Application boundaries
- Volumetric airflow must be tied to temperature and pressure before it is used as mass flow.
- The term does not identify whether downstream cooling, filtration or distribution is included.
Supporting sources
-
ASHRAE / SRC-ASHRAE-S20-CH24
ASHRAE Handbook - HVAC Systems and Equipment, Chapter 24: Desiccant Dehumidification and Pressure-Drying Equipment ↗
2020 IP edition / Chapter 24, rotary solid-desiccant operation and performance sections
Supports: Process air is the stream being dehumidified; Entering and leaving process-air states determine moisture removal; Process-air velocity and inlet moisture affect outlet performance
Maintenance record
Process Air
- Maintained by
- Yakeclimate Engineering Team
- Authoritative sources verified
- August 3, 2026
- Terminology checked
- August 3, 2026
- Last updated
- August 3, 2026