EKS-HUM-037 / Dehumidification technology and performance

Rated Dehumidification Capacity

额定除湿量

Rated dehumidification capacity is the water-removal rate assigned to a dehumidifier under a named test method and specified operating conditions.

Abbreviations: MRC
Aliases: rated moisture removal capacity, dehumidifier capacity

QUANTITY, SYMBOL AND UNIT

Quantity / objectRated moisture removal capacity

SymbolMRC, ṁ_w,rated

SIkg/hkilogram of water per hour

CommonL/daylitre per day: Requires an explicit water-density and time basis

IPpt/daypint per day

Definition

Rated dehumidification capacity is the water-removal rate assigned to a dehumidifier under a named test method and specified operating conditions.

It may be expressed as kg/h, L/day or another mass-per-time unit. A valid comparison states the inlet temperature and humidity, airflow, pressure, operating mode, test duration and rating standard or manufacturer method.

Formula and variables

MRC = Δm_w / Δt

Conditions: The removed water mass and elapsed time are measured under the named rating method, inlet conditions, airflow, pressure and operating mode.

Symbol	Meaning	Unit
`MRC`	rated moisture removal capacity	kg/h or L/day
`Δm_w`	water removed during the rating interval	kg or L with density basis
`Δt`	rating interval	h or day

Relations and distinctions

Rated and actual capacity

Rated capacity belongs to a controlled test point. Actual capacity belongs to the project's entering state, controls, installation and time-averaged operation.

Capacity and moisture load

Capacity is equipment output; moisture load is the application's required removal rate. Selection must compare them on a compatible basis.

Engineering meaning

Compare units only after normalizing the rating condition, time basis and included auxiliaries.
Request performance data across the project's expected temperature and humidity range, including low-load or defrost operation where relevant.

Common misconceptions

MisconceptionA unit rated at 100 L/day will remove 100 litres every day in any room.

Accurate explanationThe rating applies only to its stated conditions; lower entering moisture, temperature, airflow or cycling can reduce field output.

Application boundaries

Consumer, pool, DX outdoor-air and heat-regenerated desiccant ratings use different methods and scopes.
Rated capacity does not by itself state energy use, outlet dew point, external static pressure, noise or control performance.

Supporting sources

ASHRAE / SRC-ASHRAE-TERMINOLOGY-M

ASHRAE Terminology: Moisture Removal Capacity ↗

/ Entry for moisture removal capacity
Supports: Moisture removal capacity is water-vapour mass removed from process air per unit time; The quantity is reported as a mass rate
ASHRAE / SRC-ASHRAE-S20-CH25

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

2020 SI edition / Chapter 25, capacity and performance rating discussion
Supports: Rated dehumidification capacity is determined under specified test conditions; Capacity changes with equipment type and operating condition; Low-temperature operation and defrost can alter delivered output
ASHRAE / SRC-ASHRAE-STD139-2025-SCOPE

ANSI/ASHRAE Standard 139-2025 - Method of Testing for Rating Desiccant Dehumidifiers Utilizing Heat for the Regeneration Process ↗

2025 / ANSI/ASHRAE Standard 139-2025 title, purpose and public scope
Supports: Heat-regenerated desiccant dehumidifiers have a standardized moisture-removal-capacity test method; The standard scope is limited to stated desiccant equipment and atmospheric pressure; Ratings from one method must not be transferred outside its scope

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