How desiccant dehumidifiers remove moisture from the air

Desiccant dehumidifiers are known to perform well even in cold climates. Here's how they dehumidify the air and self-regenerate, requiring no maintenance.

How desiccant dehumidifiers remove moisture from the air

Table of contents

Dehumidifiers are essential household appliances in parts of Australia where persistent high humidity issues occur, especially in coastal regions. Aside from maintaining the ideal relative humidity of between 30-60% for indoor environments, dehumidifiers are also used to prevent moisture damage in homes, such as mould and condensation, as well as to reduce laundry drying time. Due to their wide range of applications, desiccant dehumidifiers are preferred as they perform well all year long, even in winter.

Structure of a desiccant dehumidifier

There are several types of desiccant dehumidifiers in the market. You can get a small disposal unit for wardrobe use or a large industrial unit that can be connected to multiple rooms using ducts. The most common desiccant dehumidifiers for household use generally consists of a spinning wheel with desiccants inside, a heating element, a condenser, a fan, and a duct that drains the condensed moisture or a water tank.

Desiccants used in a dehumidifier

The hygroscopic properties of desiccants enable them to adsorb moisture in the air until they are saturated. The process can then be reversed by heating these desiccants at a high temperature at which the moisture will leave the desiccants in the form of water vapour. Then, the desiccants can be used again to remove moisture from the air.

Some desiccant dehumidifiers use silica gel as the moisture adsorbent but zeolite is a better desiccant because it:

  • Adsorbs more moisture to very low humidity, even at low temperatures.
  • Does not react with other chemicals.
  • Does not disintegrate under high temperatures.
  • Does not oxidise in the air.

These characteristics make this extremely stable mineral ideal for repeated use in a dehumidifier.

Dehumidifying mechanism of a desiccant dehumidifier

In short, desiccants in the dehumidifier adsorb moisture from the air and are heated to remove this moisture from the desiccants, so that they can be reused for further dehumidifying without manual maintenance. Generally, the entire process can be separated into two parts, dehumidification and regeneration.

Illustration of how desiccant dehumidifiers work

Dehumidification

  1. Humid air in the indoor environment is drawn into the desiccant dehumidifier and passed through a spinning wheel with desiccants inside.
  2. Moisture in the air is adsorbed by the desiccants and dry air is blown into the indoor environment.

Regeneration

  1. Another stream of air is heated up and passed through the spinning wheel.
  2. This hot air draws out and removes the moisture stored in the desiccant.
  3. This moisture is then condensed and drained through a duct or stored in a water tank which needs to be emptied periodically.

---

Due to the regenerating process of a desiccant dehumidifier, heat is produced, increasing the surrounding temperature up to 2-3°C. Understanding how desiccant dehumidifiers work allows you to know what to expect and make better decisions in choosing a suitable dehumidifier for household use.

Disclaimer: The information provided in this article is for general reference only. Please seek advice from professionals according to your business’s needs.

Josephine Gan

Josephine Gan

As a customer service manager for more than 5 years now, Josephine has assisted numerous customers in purchasing the air treatment device that best fits their needs. From moisture damage issues to allergens in the air, she understands the indoor air quality issues most commonly faced by Australians and provides practical tips in resolving them.