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What is a Desiccant?

A desiccant material can be described as a material that naturally attracts moisture from both gases and liquids. This moisture is then adsorbed or retained within the desiccant and can be released again when heated. There are various types of desiccant available on the market, but all Aggreko dehumidifier’s use what is known as Silica Gel as the desiccant within the drying wheels.

Strangely silica gel is not a “gel” as the name implies, but in fact a porous granular form of silica which is made from sodium silicate. The internal structure of each silica granule is made up of a network of interconnecting microscopic pores, which by a process called physical adsorption or capillary condensation, attract and holds moisture within each granule. This trapped moisture can then, with the addition of heat, be released from the desiccant. This desiccant can then be used again and again. As low ambient temperatures do not restrict the material, it makes it a more all season drying system.
The Drying Process

The desiccant wheel rotates slowly.

As air is drawn through the wheel, the water molecules are removed and retained by the silica gel that is impregnated within the wheel itself.

The air is now dry and is blown into the room or building.

This dry air encourages evaporation to take place and therefore buildings, etc become dry.

The water now trapped in the wheel is removed by heating the wheel and the vaporised water is blown outside.