ITZ Plus heats with ice

Outside the ITZ Plus, a plastic container with a built-in heat exchanger is buried approximately four meters deep in the ground. The container itself has a capacity of 10 cubic meters. In this underground ice storage tank, water can be continuously frozen and thawed again. This is done using PVT collectors and solar air absorbers (“energy fences”), which are located on the roof of the building. This is because the transition from liquid water to solid ice can be used as an energy source for a heat pump and, conversely, as a heat sink for cooling the building, for example.

For the heat pump in the ITZ Plus building, the ice storage tank is an ideal source for providing a constant source temperature for the duration of the icing process, which has a beneficial effect on the efficiency of the heat pump.

The usable source energy for complete (assumed uniform) icing corresponds to the thermal energy for cooling water from 80°C to 1°C. The ice storage tank is equipped with 2 temperature sensor lances and various other sensors. This enables the research team (led by Prof. Dr.-Ing. Roland Koenigsdorff) from the Institute for Building and Energy Systems at Biberach University of Applied Sciences to monitor the icing and defrosting process more precisely. This will allow existing models to be validated and new  operating strategies for ice storage systems to be developed. Further research potential is offered by the determination of the influence of the ground and its possible use for cooling buildings in summer or the load shifting of chillers. There are also investigations into the connection of an ice storage (field) to so-called “cold local heating networks”, as this variant of heat supply is becoming increasingly attractive for the development of new housing estates. In each application, the ice storage system and the thermal energy storage systems available in the laboratory can also be compared, allowing the most efficient storage technology to be investigated for each individual case.

Contact: Stephan Volkmer, volkmer@hochschule-bc.de,  Prof. Dr.-Ing. Roland Koenigsdorff, koenigsdorff@hochschule-bc.de