IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration
Subtask A Report, Date:…
1600
1400
Frequency
1200
1000
800
600
Output Cold
Water AbCH1
Output Cold
Water AbCH2
400
200
0
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Temperature [°C]
9000
8000
7000
Frequency
6000
5000
4000
3000
Input Cooling
Water AbCH1
Input Cooling
Water AbCH2
2000
1000
0
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Temperature [°C]
Figure 8: Frequency of the operation temperature ranges of both chillers in 2010 at serial
connection in the driving circuit. (Values based on one minute average.) Source: Fraunhofer
ISE
6 Experiences / Lessons Learned
As the collector is a pure water system it is necessary to return heat from the storage to the
collector for the anti-freeze protection. Therefore, the pump runs in short intervals (bucket
principle). The data analysis on an annual base showed that in one year about 10% of the
collector heat gain is returned to the collector. In these 10% it is not only included the heat
for freezing protection but also the losses which appear during the normal collector pump
starts (cold water in the pipes). It should be kept in mind that in normal collector monitoring
these start losses are not recorded. Rough estimated: approximately 1/2 to 2/3 of the 10%
heat losses may be assigned to freezing protection.
As the plant is a pure water system no heat exchanger is installed. Consequently, the
collector water is identical with the water in the heating system and driving circuit of the