IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report A-D3b, Date: December 2010
2.12 Germany: Radiological Practice, Berlin
Description of the application
In the Radiological Practice in Berlin cooling demand occurs throughout the day and throughout
the year for permanent cooling of the tomografic equipment. Originally, the cooling
demand is covered by a chilled water network, serving also other medical services in the
building. An electrically driven compression chiller is operating the network.
Since summer of 2008, an additional small solar autonomous cooing system was installed for
covering daily cooling peak loads of the practice. The approach made is interesting, since
- pre-installed roof-top system: the chiller, hot water storage and all hydraulic components
are installed in a small size container and placed on the roof-top of the building,
since no further technical area inside the building was available;
- dry heat rejection with an air-cooler, which is used in winter for direct chilled water
production without chiller operation (free cooling mode at sufficient low ambient temperatures);
- beside a constant ground level of cooling demand (approx. 8 kW), daily peaks of cooling
demand up to 30 kW matches very well the the operation time of the solar
thermally driven chiller
A monitoring system was operated in 2009.
Type of building heritage protected
commercial building
Location Berlin, Germany
In operation since 2008
System operated by SK Sonnenklima, Berlin
Air-conditioned area 120 m 2
System used for space heating? No
System used for DHW preparation? No
General description of the system
An absorption chiller was installed and thermally driven with solar heat alone. The solar system
is used only for the chiller; due to building related properties, it was not possible to
connect the solar system to the building heating network. The solar thermal system was prepared
to be operated with pure water and a corresponding control was installed. However,
for test reasons, the system was filled with water-glycol.
The plant is pre-cooling the chilled water, returned from the practice. In case the temperature
of the chilled water is not sufficient low (approx. 8°C) leaving the absorption chiller, it is subcooled
passing a heat exchanger in the building chilled water network.
During winter, chilled water can be prepared directly through the air cooler. This mode was
already widely used in 2008 and 2009. As a consequence, the heat rejection circuit as well
as the cold water circuit are filled with water-glycol. Also the hot water circuit is using waterglycol
(foreseen to be replaced with pure water later).
page 42