Adsorption
The principle of adsorption is illustrated in the following diagram. The dehumidifier itself is made up of the following components; adsorption rotor, drive motor, heating elements, air fans, air filters and electrical control components. All these items are packaged in a single cabinet and supplied ready to go into operation for the customer, once a power supply and the necessary air ducts have been connected on site.
The process air is drawn through the air filter and then into the drying section of the adsorption rotor, which is typically 85% of the total rotor volume. This presents a large surface of silica gel to the air to absorb the moisture. This air then leaves the dehumidifier as dry air.
As the rotor turns, it slowly enters the regeneration segment, represented by 25% of the rotor volume. In this section, a smaller opposing air stream is heated and used to drive off the moisture collected in the process air stream. The air then leaves the machine as ‘wet air’ although all the dehumidification and regeneration is completed in the vapour phase and no free water is present at any time.
Because these two opposing flows of air pass through the rotor simultaneously, a continuous and automatic process is obtained. The rotor's silica gel coating on a glassfibre base is capable of operating for many years without losing its’ dehumidifying and regeneration properties.
Compared to other types of dehumidification, the adsorption dehumidifier has the advantage of operating well at low temperatures and low relative humidity levels. The operational ranges are typically –20oC to +35oC and at any relative humidity.