22
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
CPG
). Table 5 also gives the multiplication factors for the
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*
f
= P
f
(F
CPG
) = (163) (0.97) = 158 kW
Q*= Q (F
CQG
) = (7.87) (1.12) = 8.71 l/s
Loss of Head = (40)(1.25) = 50 kPa
(The heat output is not subjected to variations owing to the presence of brine).
Tab.5
HOW TO SELECT THE UNIT
50
60
70
80
87
100
0.905
0.932
0.960
0.944
0.952
0.960
0.972
0.966
0.960
0.980
1
1.022
0.963
0.961
0.959
0.942
0.947
0.952
0.924
0.935
0.946
-5
0
5
7
10
15
Tab.4
Outdoor air temp.
Correction factor F
cUr
Relative humidity %
% of brine in weight
Freezing temperature
Refrigerating power multiplier
(F
CPG
)
Power input multiplier
Water flow rate multiplier
(F
CQG
)
Loss of head multiplier
0
0
1
1
1
1
10%
-3.9
0.99
1
1.04
1.08
20%
-8.9
0.98
0.99
1.08
1.16
30%
-15.6
0.97
0.99
1.12
1.25
40%
-23.4
0.95
0.98
1.16
1.35
Summary of Contents for 150.4
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