Koelwiel

Koelwiel is a term used in Dutch HVAC terminology for a rotating energy-recovery wheel installed in air handling units. The device rotates between the incoming (supply) air stream and the outgoing (exhaust) air stream, transferring heat and, in some designs, moisture. The result is preconditioned supply air with reduced heating or cooling load on the main climate system.

There are two main variants. Sensible heat wheels transfer only heat between the two air streams, improving efficiency with minimal moisture interaction. Enthalpy wheels, also known as desiccant or moisture-absorbing wheels, transfer both heat and moisture, enabling simultaneous heating or cooling and dehumidification. The wheel is typically made from a porous medium or desiccant material and is driven by a small motor. In enthalpy designs, part of the wheel that has absorbed moisture is regenerated in a separate zone by heated air, releasing moisture to the exhaust stream and restoring the wheel for reuse.

Applications include commercial buildings, hospitals, data centers, and industrial facilities, where energy recovery reduces overall electricity and fuel consumption. Koelwielen are commonly integrated into rooftop units, central air handling units, or dedicated energy-recovery modules within HVAC systems.

Advantages include reduced energy use, lower operating costs, and improved indoor air quality due to more stable supply conditions. Limitations involve potential pressure drop, the need for periodic maintenance to prevent contamination or microbial growth, and performance sensitivity to extreme humidity conditions. Proper sealing, filtration, and regular cleaning are important to maintain effectiveness and longevity.

See also: Rotating heat exchanger, Desiccant wheel, Enthalpy wheel, HVAC.