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
Typical operation temperature
Configuration
Heat storage
Cold storage
Auxiliary heater
Use of auxiliary heating system
Auxiliary chiller
80 °C driving temperature for chiller operation
0.7 m 3 water
no
yes (not used)
no
none
System scheme
System performance
In the last three years, 2007, 2008, 2009 and 2010, the chiller has been operated under
different scenarios of performance. In 2007 the chiller worked with two different solar
collector areas (20 m 2 and 37.5 m 2 ) in order to analyze the influence on the chiller
performance The average COP value operating with 20 m 2 was 0.51 whereas with the
37.5m 2 the COP value achieved 0.49, although in the first case the average chilling power
4.0 kW, in the second one, the chilling power increased to 5.3 kW. In both cases, the chiller
rotary drum speed was 300 rpm. In the next scenario the chiller worked with the whole solar
surface and its rotary speed was increased till 400 rpm to improve the heat and mass
process of the absorption cycle. The performance of the system improved (COP: 0.57, W ch :
5.78 kW), but the installation kept on having a strong influence of the outdoor temperature. In
the year 2008, the average outdoor temperature was 12% higher than the year before, a fact
that was displayed in the results of that year (COP: 0.51, W ch : 4.4 kW). Finally, to eliminate
the outdoor temperature influence on the heat rejection system and taken the opportunity of
using a closed water well with a constant temperature of 17ºC, in 2009, an open geothermal
cycle was installed. The obtained results presented constant values, such as the COP as
well as the chilling and heat rejection powers, but they were lower than the expected (COP:
0.52, W ch : 4.2 kW), due to the higher operational temperature of the water well (25ºC instead
of 17 ºC used in the design process).
System reliability and overall success of the installation
In general, the operation of the installation works reliable. The principal objective of the solar
cooling system has served the purpose of resolve the overheating problems of the solar field.
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