IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

IEA SHC Task 38 Solar Air Conditioning and Refrigeration
Subtask A Report, Date:…
80
variable speed control on
water spray mode off
70
60
50
]
40
[°C
s
re
30
tu
ra
e
p20
m
e
T
10
solar supply loop
solar return loop
heat rejection supply loop
heat rejection return loop
cold water supply loop
cold water return loop
ambient temperature
0
6
:5
1
6
:1
2
1
6
:3
2
1
6
:5
2
1
6
:1
3
1
6
:3
3
1
6
:5
3
1
6
:1
4
1
6
:3
4
1
6
:5
4
1
6 6 6
:1 :3 :5
5 5 5
1 1 1
Time
6
:1
6
1
6
:3
6
1
6
:5
6
1
6
:1
7
1
6
:3
7
1
6
:5
7
1
6
:1
8
1
6
:3
8
1
6
:5
8
1
6
:1
9
1
6
:3
9
1
In Figure 14, the temperatures around the adsorption chiller on the 25 th of August 2010 are
shown. It is clearly identifiable, that while the heat rejection temperatures are rising, nearly
any temperature difference between supply and return cold water side happens during the
variable speed control mode of the heat rejection fans. Therefore, there wasn´t nearly any
cooling demand in the offices and the adsorption chiller shouldn´t have been working at all.
The control of the absorption chiller is only taking a certain cooling set point temperature on
the cold supply water side into account (here 12 °C ). It is therefore the duty of the system
controller to turn off the adsorption chiller, when an unreasonable operation like this
happens, but that was not adapted by installing the variable speed control mode of the heat
rejection fans in July 2010.
To avoid the operation, as it happened on the 25 th of August 2010, the cooling set point
temperature was changed to 6 °C until the adaptatio n of the system controller happens (see
Figure 15).