For the setup and maintenance of a comfortable atmosphere by air-conditioning systems, the regulation of the room humidity plays an important role in addition to the regulation of the room air temperature. On average, more energy is needed for the dehumidification than for the cooling of occupied zones to reach the comfort field.

The dehumidification of the outdoor air is mostly done by an energy-intensive process based on cooling the air flow below the dew point with subsequent reheating to the desired supply air temperature.

To achieve a reduction of energy and therefore operating costs, an energy-efficient dehumidification unit based on light sensitive hydrogels is developed within a joint research project of the wfk – Cleaning Technology Institute and the Institute of Energy and Environmental Technology (IUTA).

Light sensitive hydrogels change their hydrophilicity and therefore their water absorption capacity during excitation with light of the appropriate wavelength (figure 1). Due to this fact, they possess a high water absorption capacity during the dehumidification process.

During the regeneration process by irradiation (UV light), the deswelling (drainage) of the light sensitive hydrogels is obtained by releasing the majority of the absorbed water from room air as fluid.

In this research project, a dehumidification unit based on light sensitive hydrogels is developed, which allows the exposure of hydrogels to an optimal surround-flow during the air dehumidification process as well as an efficient light coupling and drainage in the regeneration process.

By using such dehumidification units based on light sensitive hydrogels, a significant reduction in the energy demand can be achieved.

The research report is available on request from FRT.