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
2.9 Germany: Technical College Butzbach
Description of the application
In the low-energy building of the Technical College, demand for summer air conditioning
arises due to high occupation rates and frequent use of computer equipment. The building is
used throughout the summer season. Two existing ventilation systems (supply/return air with
heat recovery, 1,250 m³/h air volume flow rate each) are not sufficient to remove the sensible
and latent cooling loads in summer. For this reason, a solar thermally driven chiller plant was
added and supported in the frame of the German Solarthermie 2000plus funding programme.
The ventilation units were extended by cooling coils, and additionally chilled ceilings and
cooling panels were installed.
Type of building College building, low energy building
Location Butzbach, Germany
In operation since 2008
System operated by Technical College Butzbach
Air-conditioned area 335 m 2
System used for space heating? Yes
System used for DHW preparation? No
General description of the system
Two absorption chillers are installed and thermally driven with solar heat alone. The
condensing boiler is used for space heating in winter only. Different operation modes are
possible with the system:
only one chilled water temperature level, e.g. for the removal of sensible cooling
loads, is required. In case both chillers are in operation, the driving circuits of the
chillers are usually connected in parallel;
one chiller operates at low chilled water temperature level for supply air
dehumidification and cooling, while the other provides chilled water at a higher
temperature level for the chilled ceilings. In this mode, it is possible to connect the
driving circuits of the chillers in series with the effect of an increased temperature
difference in this circuit, resulting in a more favourable collector system operation.
The evacuated tube collector system contains pure water as collector fluid. A special freezing
protection control runs the collector loop in short intervals at low ambient temperatures. No
heat exchanger is installed in the total heat supply system.
System concept and overall system control: Hindenburg Consulting (www.hindenburgconsulting.com)
Detailed planning: IGT GmbH
Central air-conditioning unit
Technology
Nominal capacity
Type of closed system
Brand of chiller unit
Chilled water application
closed cycle
2 x 10 kW cold
Absorption
SK Sonnenklima: Suninverse
Supply air cooling and dehumidification, chilled ceilings
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