Desiccant Dehumidifiers Technology

Posted by AlorAir Alex on

There are mainly two types of drying technologies :

1. Refrigeration technology – refrigerated dehumidification equipment uses a series of cooling coils to condense moisture from the air.

2. Desiccant technology –  Desiccant dehumidification equipment use a dry chemical to extract moisture from the air.

Desiccant dehumidifiers are the new brand in drying technologies. Designed for both commercial and residential use. When installing a dehumidification system in any building there are a lot of factors to consider including :

  • The temperatures.
  • The size of the building.
  • The capacity of the dehumidifier.
  • Humidity levels.
  • The efficiency of the dehumidifier.

While most company dehumidifiers are low grain refrigerant(LGRs), Desiccant dehumidifiers are better for specified, temperature set drying needs because they have unique performance features. Desiccant dehumidifiers are known for their exceptional effectiveness in extracting moisture at low temperatures.

Desiccant dehumidifiers are capable of drying air to about 4% relative humidity(RH) at 70◦F (referred to as single-digit grain per pound (GPP) levels). While refrigerated dehumidifiers can only dry areas that are above 32◦F (the dew point).

How do desiccant dehumidifiers work?

1. Air pulled into the Desiccant dehumidifier using a fan.

2. The moist air is the exposure to a desiccant material that absorbs all the moisture.

3. The moisture is then removed from the desiccant material and expelled from the dehumidifiers as water vapor.

4. In the separate sealed chambers(where moisture is removed), there are two airflow paths:

  • The first path is referred to as the process air – used to transport air to be dried.

The process air is directed through the rotor( it is a thick rotating honeycomb disk). The rotor is coated with desiccant material, that absorbs the moisture.

The desiccant material is made up of a silica gel compound. The rotor is circular to increase the surface area. The rotor can be as big as up to one foot in diameter.

  • The second path is called the reactivation or regeneration air –used to exhaust the moisture.   

Warm air from the regeneration air is used to extract the moisture from the rotor. The water-air causes the moisture in the rotor to be released as water vapor, from the desiccant material. This makes the rotor decrease in size.

The hot moist air is then directed out of the Desiccant dehumidifier.

In smaller portable Desiccant dehumidifiers the hot regeneration airflow is electrically generated, while in some of the larger Desiccant dehumidifiers, it is can be from natural gas, electric, or propane.

The rotor rotates slowly the drying chamber and the reactivation chamber. This makes the dehumidification process slow, however, it is very effective in extracting moisture from the air.

The airflow of the process chamber and the reactivation chamber are always on opposite sides of the rotor wheel. This helps blow out any dust particle or impurities coming from the process air (air from the room.). all the regeneration airflow is extracted from 25% of the process airflow. This process is carried out repeatedly till the air from the process airflow contains the required relative humidity.

Basically, the loaded on to the desiccant dehumidifiers in the process section and then unloaded in the regeneration section.

Desiccant dehumidifiers designs

1. hole Desiccant dehumidifiers – has separate air flows(meaning the process and reactivation are separated.) depending on the capacity of the dehumidifier the airflow may differ.

2. hole Desiccant dehumidifiers – this design uses a single inlet for the process and regeneration airflow, then recycle a part of the processed air for the regeneration. The 3 – hole Desiccant dehumidifier is proven to produce better results in damp cold spaces because the regeneration air-dried and heated up several in the process stage.

In Desiccant dehumidifiers, the warmer and drier the regeneration air is, the more effective and efficient the dehumidifier will be.

Where are desiccant dehumidifiers mostly used?

Desiccant dehumidifiers have been used in many industrial facilities, such as :

  • Agriculture – in the case of mushroom cultivation, the farmer required to keep his growth room at a very low temperature appropriately between 20◦to 35◦, which makes the Desiccant dehumidifiers the best option.
  • Food processing plants. – processed foods require low humidity to avoid contamination by in the packaging.
  • Pharmaceutical plants. – pharmaceutical factories maintain a highly controlled indoor environment in terms of humidity, temperature, and air circulation.
  • Cement plants – cement is mixed with water and other building materials to form concrete. Cement factories ensure their environment has very low humidity.

Most of these industrial facilities require dry environments to avoid material damage.

What are the advantages of desiccant dehumidifiers?

  • Weigh less - Desiccant dehumidifiers are light because they are built compact with lighter technology. They are easy to load and unload for transport. Weigh a lot less than refrigerant dehumidifiers.
  • Provide better results at lower humidity and temperature levels – with no worry of ice forming in the dehumidifier, the Desiccant dehumidifiers are able to remove moisture even at temperatures below 60◦F  compared to refrigerated dehumidifiers. Desiccant dehumidifiers are also able to keep lowering the humidity levels even when the relative humidity is below 30%.
  • Easy to install. – easy lift and place at the optimum position to completely dry the space.
  • Less noise – the lack of a compressor in Desiccant dehumidifiers, ensures the dehumidifier produces less noise. Desiccant dehumidifiers are perfect for noise-sensitive spaces.

The disadvantage of desiccant dehumidifiers :

  • Desiccant dehumidifiers are not as efficient as a refrigerated dehumidifier in temperature above 60◦F . at warmer environments refrigerated dehumidifiers more effective and energy effective.
  • Desiccant dehumidifiers consume more energy compared to the refrigerated dehumidifier. Mainly because of the warming of the regenerated air.
  • Desiccant dehumidifiers are more expensive.

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