The term of dehumidifying in air conditioning is to decrease the absolute temperature.

The way to make air dry was decreasing relative humidity by heat. However, the

absolute humidity was not changed; therefore it was not dehumidifying in air

conditioning. A dehumidifier needs to maintain “1. The dehumidification efficiency and

air management capacity as 2. The dehumidification efficiency and air management

capacity” in absolute temperature standard.

1. The dehumidification efficiency-The dehumidifying each unit ⊿ x g(kg)/kg

2. The dehumidification capacity-The dehumidifying each unit×The air management

capacity kg(Lit)/h.min

Dehumidifying units

There are some types of units. Please see the (table 1). 

explains the main concept for each method.

 The difference between solid and liquid are nearly 0 ℃ of the dew point. The

difference between chemical desiccant and cooling and heating for regenerator are

nearly 25 ℃ of the dew point. However, the dehumidifying methods may consist of a

combination with another (hybrid). Moreover, methods may be adjusted and depend on


Heat transfer characteristic

Transferring humidity does not work as air flow but it spreads out by humidity

difference with a supplier (room). If a supplier is not sealed well, this will cause leaking

pressure from the supplier. As a result, it is difficult to constantly maintain humidity.

For instance, blowing air as air flow curtain is sometimes used to control temperature.

However, this does not work to control humidity in air conditioning. On the other hand,

it is more beneficial and better humidity transfer without any wasting if this

characteristic is used.

Dehumidifying for designated area and dehumidification for air conditioning. Most of

the dehumidifiers except for factory ones were used for designated area and these had

simple function and were small sized. They used heat pumps to expand =cooling to

decrease humidity and condense = using heat from exhaust to dehumidify but there is a

solid desiccant rotor method with heating as dehumidifying that is for a room. The

dehumidification efficiency ⊿x is not impacted due to mainly ventilation process.

Separated sensible and latent heat air conditioning on saving energy perspective is

recently advocated. In addition, room air conditionings that have dehumidifiers,

humidifiers and enthalpy heat exchangers are invented. For cleaning purposes, outdoor

processors that control humidity in public facilities are slowly coming out. To

dehumidify completely requires a lot of energy. Processors that have efficiently

dehumidifiers and humidifiers are invented as well. Lastly, conventional outside air

processors can not be used for public users because their facilities are less sealed than

industries’ ones and latent heat may be produced. Based on these, new concept may

need to be invented.

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