IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report, Date: November 2010
• end of May10:
o clearance temperature (upper storage temp.) for starting the ACM from 88°C
to 80°C
o Change of ventilation control strategy on/off to speed control
The effects of these changes are shown in Figure 13.
Figure 13: Comparison of thermal and electrical COPs 2009 and 2010
Compared to the cooling period 2009 (including free cooling and thermal driven chiller) the
electrical COP was rising 36% up to value of 2.3 while the thermal COP was on the same
level. After changes in the control parameters another increase of 44% could be achieved.
Finally, including the change of the control strategy of the cooling tower fan, the electrical
COP is at about 3.4. Compared to 2009 a plus of 105% in the electrical COP was obtained.
The thermal COP mainly affected by the reccoling, regeneration and chilled water
temperature level was enhanced by 17%.
Main reasons for the better performance are higher loads due to weather conditions and
changes in the set temperatures (supply temp.) and as a result less part load condition!
4.2.4 Cooling period 2010
The daily performance of a typical sunny day is shown in Figure 14. The chiller starts its
operation at 11:30 a.m. after the storage temperature reaches 80°C. The driving
temperature is slightly increasing during operation and the average is at about 77°C. The
chilled water temperature decreases from 20°C to 8° C while the recooling temperature is
controlled to 29°C. Within these conditions a decre asing power for driving heat and cold
production is visible.
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