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Tab.4
Outdoor air temp.
-5
0
5
7
10
15
If the system is not drained during winter, but is stopped and brine is used, it will be necessary to introduce multi-
plicative correction factors for the Refrigerating Power (F
Power input of the compressors and the Loss of head values.
Supposing that brine with 30% ethylene glycol is used, the Refrigerating Power,
Water Flow Rate and Loss of Head values previously calculated for the selected unit become:
P*
= P
(F
) = (163) (0.97) = 158 kW
f
f
CPG
Q*= Q (F
) = (7.87) (1.12) = 8.71 l/s
CQG
Loss of Head = (40)(1.25) = 50 kPa
(The heat output is not subjected to variations owing to the presence of brine).
Tab.5
% of brine in weight
Freezing temperature
Refrigerating power multiplier
Power input multiplier
Water flow rate multiplier
Loss of head multiplier
22
HOW TO SELECT THE UNIT
50
60
0.905
0.932
0.944
0.952
0.972
0.966
0.963
0.961
0.942
0.947
0.924
0.935
(F
)
CPG
(F
)
CQG
Correction factor F
cUr
Relative humidity %
70
0.960
0.960
0.960
0.959
0.952
0.946
). Table 5 also gives the multiplication factors for the
CPG
0
10%
0
-3.9
1
0.99
1
1
1
1.04
1
1.08
80
87
0.980
1
20%
30%
-8.9
-15.6
0.98
0.97
0.99
0.99
1.08
1.12
1.16
1.25
100
1.022
40%
-23.4
0.95
0.98
1.16
1.35
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