Desiccant Dehumidifier – How It Works

Desiccant dehumidifier how it works. Mode of operation №1

This mode of operation involves only one common fan for both air flows i.e. the process air and reactivation air. In this case occurs maximum heat recovery due to distribution of the air flows shown on the picture. This solution makes the installation easier and allows achieving the lowest possible dew point.

This mode of operation is implemented only in the smallest desiccant dehumidifier type MDC250.

In this case, desiccant dehumidifier has only one radial fan for both process air and reactivation air intake and exhaust/supply. The process air passes through the honeycomb rotor (desiccant wheel) with tremendous active dehumidification surface. The rotor is made of Silica Gel that has enormous capacity to absorb water molecules. The humid process air passes through ~60% of the rotor face area. The process air is dry after crossing the rotor, because the moisture has been extracted by absorption process to the silica gel.

Simultaneously reactivation airflow initially is partly dehumidified and preheated while crossing the small purge face area of the desiccant wheel. Then the air is heated up to 90-140oC and crosses so called regeneration zone of the rotor. The silica gel gives away the moisture in to the reactivation airflow by means of evaporation of water in to the hot air flow that has increased capacity to be saturated with water vapor. The warm and humid airflow then is exhausted to the outside of the desiccant dehumidifier.

In such way, the rotor (desiccant wheel) restores its capacity to absorb water molecules from the process airflow. The reactivation airflow performs also the function of cleaning the rotor from contaminants that could be present on the surface of the rotor. Continuous rotation of the rotor provides a nonstop process of adsorption/reactivation. Special holding frame from both sides of the desiccant wheel prevents the mixing of the process air and the reactivation airflows. Moreover, the absence of condensation during the dehumidification process allows installing the desiccant dehumidifier, without a connection to drainage system.

operating principle of desiccant dehumidifier
Desiccant dehumidifier working principle. Mode of operation №2

This is the most common mode of operation and it allows drying the air very efficiently down to almost 0% RH.

This mode of operation is implemented in the desiccant dehumidifiers types MDC450 to industrial desiccant dehumidifiers MDC3000.

In this case, desiccant dehumidifier has two separate centrifugal fans for process air and reactivation air intake and exhaust/supply. The process air passes through the honeycomb rotor (desiccant wheel) with tremendous active dehumidification surface. The rotor is made of Silica Gel that has enormous capacity to absorb water molecules. The humid process air passes through ~75% of the rotor face area. The process air is dry after crossing the rotor, because the moisture has been extracted by absorption process to the silica gel.

Simultaneously reactivation airflow is heated up to 90-140oC and crosses so called regeneration zone of the rotor. The silica gel gives away the moisture in to the reactivation airflow by means of evaporation of water in to the hot air flow that has increased capacity to be saturated with water vapor. The warm and humid airflow then is exhausted to the outside of the desiccant dehumidifier.

In such way, the rotor (desiccant wheel) restores its capacity to absorb water molecules from the process airflow. The reactivation airflow performs also the function of cleaning the rotor from contaminants that could be present on the surface of the rotor. Continuous rotation of the rotor provides a nonstop process of adsorption/reactivation. Special holding frame from both sides of the desiccant wheel prevents the mixing of the process air and the reactivation airflows. Moreover, the absence of condensation during the dehumidification process allows installing the desiccant dehumidifier, without a connection to drainage system.

operating principle of desiccant dehumidifier

How does desiccant dehumidifier work? Mode of operation №3

This mode of operation provides heat recovery. The desiccant wheel absorbs the heat while regeneration process. In such way, reactivation air is pre-heated and partially dehumidified and then supplied through the heater in to the reactivation section. This solution allows reducing the power consumption and reduces the temperature increase of the dry air.

This mode of operation is implemented in the desiccant dehumidifiers types from MDC4000 and bigger.

In this case, desiccant dehumidifier has two separate centrifugal fans for process air and reactivation air intake and exhaust/supply. The special purge zone allows to maximize heat recovery. The process air passes through the honeycomb rotor (desiccant wheel) with tremendous active dehumidification surface. The rotor is made of Silica Gel that has enormous capacity to absorb water molecules. The humid process air passes through ~60% of the rotor face area. The process air is dry after crossing the rotor, because the moisture has been extracted by absorption process to the silica gel.

Simultaneously reactivation airflow initially is partly dehumidified and preheated while crossing the small purge face area of the desiccant wheel. Then the air is heated up to 90-140oC and crosses so called regeneration zone of the rotor. The silica gel gives away the moisture in to the reactivation airflow by means of evaporation of water in to the hot air flow that has increased capacity to be saturated with water vapor. The warm and humid airflow then is exhausted to the outside of the desiccant dehumidifier.

In such way, the rotor (desiccant wheel) restores its capacity to absorb water molecules from the process airflow. The reactivation airflow performs also the function of cleaning the rotor from contaminants that could be present on the surface of the rotor. Continuous rotation of the rotor provides a nonstop process of adsorption/reactivation. Special holding frame from both sides of the desiccant wheel prevents the mixing of the process air and the reactivation airflows. Moreover, the absence of condensation during the dehumidification process allows installing the desiccant dehumidifier, without a connection to drainage system.

operating principle of desiccant dehumidifier

publisher Desiccant Dehumidifier – How It Works