Why overpressure inside a wind turbine matters

When is a dehumidifier is not just a dehumidifier? When it's a Cotes patented combined desalter and dehumidifier, developed specifically for wind turbines to create an air overpressure inside the turbine to protect sensitive electronics and critical components from the harmful effects of humid and salty air.

The right way to dry a wind turbine

Humidity is the concentration of water present in the air. Often measured as relative humidity (%RH). To reduce the %RH and avoid salt entering the wind turbine structure, Cotes has developed and patented a special method that overcomes the problems of creating dry and salt-free air in an offshore wind turbine: the Cotes Wind Overpressure system (or CWO).

How the Cotes Wind Overpressure system works

The CWO (combined desalter and dehumidifier) is usually placed at the bottom of the turbine tower. It creates positive pressure inside the structure with dry air free of salt. The positive pressure moves the air upwards and protects the entire tower as it does so. With this method, almost no ducts are needed (an optional small independent duct can be placed at the bottom of the tower to ensure circulation there, if the transition piece needs to be conditioned).

Illustration of how a Cotes CWO creates overpressure with saltless air inside an offshore wind turbine

In a Cotes CWO, the dehumidifier sucks ambient air into a mixing chamber and blends it with dry dehumidified air, which removes the water in the saltwater droplets. This causes the salt to change phase, from dissolved to crystalline, allowing the salt to be filtered out (measured at a 99.9% filtration rate).

The now saltless air is dehumidified and divided into three airflows (watch the video above to see how it works):

1. An airflow for drying incoming outdoor air
2. An airflow for regeneration of the silica gel rotor
3. An airflow to blow dry and saltless air into the tower

To summarise the concept

A CWO takes airs from outside the turbine, the air is desalted and dehumidified. It is then blown into the tower to create an overpressure, effectively sealing the turbine off from the moist, salty air outside the structure. Depending on the size, design and location of the turbine, Cotes will recommend one of our three CWO models below to suit the specific situation and conditions.

Learn more about Cotes dehumidifiers: Download Cotes CWO Dehumidifiers Datasheet

Get a Cotes dry-air solution recommendation

To create a robust dehumidification solution for offshore turbines, the climatic conditions at sea must be given serious consideration. Otherwise, mould issues that are expensive to resolve are likely to occur. Likewise, condensation leading to corrosion and electrical failures can be expected.

Could you benefit from consultation about the best dry-air strategy for your wind turbines? Our team of experts is here to help.