Desiccant wheel

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The desiccant rotor : at the heart of dehumidification

There are various kinds of dehumidification and humidity control technologies in use today, one of which is the desiccant wheel or rotor. DESSICA systems uses two independent and countercurrent air flows through the desiccant rotor. Desiccant rotor work by directing process air through the wheel itself, which contains silica gel, a very effective adsorbent. Most of this process air is dry after having passed through the dehumidification rotor. Some air retains a little more moisture. This air is then heated (to very high temperatures of between 100 and 160°C) and sent back through the rotor again. This helps dry out the silica gel, with moisture contained in the gel evaporating into the hot air flow. The warm, but moist air is then removed, and the silica gel is ready for another process air. This second flow of air through the desiccant rotor which heat wheel is called the reactivation airflow. This airflow also has another major role : it helps clean the rotor of any contaminants thank to the decontamination capacities of high temperature – this is particularly important for the food processing, agri-food and pharmaceutical industries.

Desiccant rotor

The key advantages of the desiccant wheel over other kinds of humidity control

The desiccant wheel is just one way of removing moisture. Ventilation, heating and cooling are three other approaches to dehumidification. However, each of these come with their own challenges. Ventilation requires air of a low moisture content to start off with, meaning that changing weather conditions can create all sorts of problems.

Heating, meanwhile, has no impact on absolute humidity, and is also expensive. Dessica has been working on new technologies to reduce the running costs of its systems, whilst desiccant rotors are also renowned for their long operational lifespan.

Lastly, cooling is a relatively inefficient way of removing moisture in environments where the ambient temperature is 10°C or less. Cooling-based dehumidification systems, which are ozone-depleting, making the desiccant wheel a more environmentally-friendly choice.

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