Dehumidification technology and performance

Entering-air Condition

进风工况

Entering-air condition is the stated thermodynamic and flow state of the air at a defined equipment or process inlet.

Abbreviations: EAC
Aliases: inlet-air condition, entering condition

QUANTITY, SYMBOL AND UNIT

Quantity / objectEntering-air condition

UnitNot applicable

Definition

Entering-air condition is the stated thermodynamic and flow state of the air at a defined equipment or process inlet.

For dehumidification it normally includes dry-bulb temperature and at least one moisture property, and may also require pressure, airflow and the exact measurement location. Capacity data are meaningful only when the entering condition and test basis are known.

Relations and distinctions

Entering and room condition

Room air may mix, heat or cool before reaching the equipment inlet, so a room sensor is not automatically the entering-air state.

Entering and rating condition

An entering condition is any stated inlet state; a rating condition is a defined test point used to assign performance.

Engineering meaning

Compare required performance with data at matching inlet temperature, moisture state, airflow and pressure.
Name the inlet plane and sensor locations when commissioning or diagnosing capacity.

Common misconceptions

MisconceptionA daily room RH average is enough to select dehumidification capacity.

Accurate explanationEquipment responds to the coincident air state and flow at its inlet, including peaks and changes caused by mixing or duct conditions.

Application boundaries

The term does not specify one standard industrial rating point.
Entering-air condition alone does not include the moisture load, leaving-air target, external static pressure or all auxiliary operating limits.

Supporting sources

ASHRAE / SRC-ASHRAE-S20-CH25

ASHRAE Handbook - HVAC Systems and Equipment, Chapter 25: Mechanical Dehumidifiers and Related Components ↗

2020 SI edition / Chapter 25, dehumidification process points, performance and entering-air discussions
Supports: Dehumidifier performance depends on the condition of air crossing the dehumidifying coil; Entering-air dry-bulb and moisture state affect capacity and operating point; Outdoor-air mixing or heat recovery can change the entering state and performance

Maintenance record