Dehumidification is the removal of water from the air. Dehumidification equipment will take the ambient air and will “treat” it before it is exhausted into the enclosure. There are currently two industry accepted types of dehumidification:
The desiccant based dehumidification system uses a chemical to directly absorb moisture from the air while it is a vapor. Specifically, the moist air stream is passed over a desiccant material, typically lithium chloride or silica gel, that in its active state has a vapor pressure below that of the air to be dehumidified. Moisture is absorbed from the air stream. The desiccant material is then heated which forces it to give up the absorbed moisture, regenerating the desiccant material for continuous use. The heat of regeneration causes the temperature of the air entering the enclosure to be substantially higher than the ambient air. Due to this heat of regeneration requirement the power requirements to operate this type of unit are generally quite high. Ultimately the desiccant material will have to be completely replaced to maintain its performance level.
The refrigerant dehumidification system directs incoming air over evaporator coils to reduce the absolute amount of moisture in the air via condensation. The air exits the cooling coil section of the dehumidifier at a reduced temperature, dew point, and absolute humidity. It thepasses over both the condenser coils and a series of reheat coils to (a) increase the temperature of the air and (b) reduce the relative humidity of this air. This system is advantageous when the ambient external air is comparatively warm with a high moisture content and the dew point is greater than 0 degrees C (32 degrees F). It has low power consumption requirements - approximately half that of a desiccant unit with an equal air flow rating.
Download PDF to read more: