Adsorption thermal wheel combined with reverse-cycle HP

Efforts in the building industry, driven by increasingly stringent regulations, have recently focused on low-consumption and eco-sustainable buildings (NEZEB and ZEB). To achieve the required results, buildings must be isolated from the outside environment through thermal insulation and double-glazed windows. In these buildings, heat recovery ventilation (HRV) units or air handling units (AHUs) are used to provide the air exchange needed to prevent the growth of mould and reduce the concentration of CO₂ and airborne pollutants, rather than relying on natural air infiltration as in the past.  

The temperature of the air taken in from outside is usually below or above the indoor set point temperature, except for a few brief periods during the year. To avoid thermal discomfort with excessively cold or hot air streams, the temperature of the supply air must not be different from that of the indoor air. Partial energy recovery of the exhaust air is possible using a heat exchanger, such as the Klingenburg RRU ECO HUgo Series.

This rotary heat exchanger, thanks to the HUgo zeolite coating (DekaTru^®), transfers sensible and latent heat simultaneously with optimal efficiency, up to 85%, without bacterial growth or odour formation. The sorption coating has a unique surface structure that traps water using the adsorption principle, but does not trap bacteria. Known as selective sorption, this process guarantees maximum air hygiene.

To achieve higher energy recovery values, the ventilation unit can be equipped with a reverse-cycle heat pump (HP), fully integrated into the unit. The heat pump must be able to operate at part load, supplying the system with the right amount of energy. The essential elements for correct design of the HP in this sense are the electronic expansion valve and rotary compressor with inverter.

Electronic expansion valves, such as the E2V-F, thanks to its hermetic design and the availability of an ATEX-certified stator, can be used with flammable refrigerants. The different sizes available and the possibility of using unipolar or bipolar stators mean it can be used in different-sized units, guaranteeing high efficiency thanks to modulation of fluid flow.

Inverters, such as the PSD2, modulate compressor speed and consequently refrigerant flow-rate. The twin rotary compressor, such as the AVIC model, ensures optimal operation with new low-GWP refrigerant gases. These three elements make it possible to precisely manage variations in load, bringing significant increases in the unit’s coefficient of performance (COP) even during part load operation.

To accurately measure temperature, humidity and CO₂ inside buildings and in ventilation ducts, CAREL has developed the new DP-THC series. The duct version is specifically designed to act as the AHU control probe, while LCD wall version lets end users constantly monitor the indoor air quality parameters. Both solutions are available with serial or analogue communication.

To simultaneously manage all these devices and benefit from high-efficiency energy recovery, a smart controller is needed, such as the CAREL k.Air. This is a ready-to-use and flexible solution for controlling air handling units, covering a wide range of layouts and reducing times and costs, from design to commissioning.

Last but not least, the thTx thermostat is useful for controlling temperature, humidity, and split fan speed, with a simple and intuitive user interface.  The thermostat has its own built-in logic, but can also be fully controlled via the Modbus^® communication protocol.

Don’t miss CAREL Sales Manager Alexander Willesch,'s presentation.

He'll show how combining advanced ventilation systems with CO₂ monitoring ensures both comfort and health indoors. Learn how to mitigate pollutants and pathogens, optimising air quality according to the latest European legislation.

March 18th, 11:00 AM

Hall 12, Level 1, E03