TF7039GB_A_NOT
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7.2.2.
OPERATING WITH ANTIFREEZE
It is essentially possible to operate the system with antifreeze (brine). Depending on the concentration, effi-
ciency and performance losses are to be expected. In order to keep the transfer losses between brine and
the target medium as low as possible, plate heat exchangers that have been designed accordingly must be
used. The quality of the heat transfer at this point significantly influences the efficiency of the exhaust air heat
utilisation.
ETHYLENE GLYCOL SOLUTIONS
CORRECTION FACTORS FOR ETHYLENE GLYCOL SOLUTIONS
Freezing point
°C
0
-3.63
-6.10
-8.93
-12.11
-15.74
-19.94
-24.79
-30.44
-37.10
Ethylene glycol
proportion
%
0
10
15
20
25
30
35
40
45
50
Qwh
-
1.000
1.027
1.038
1.050
1.063
1.078
1.095
1.114
1.135
1.158
Ph
-
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
Pa
-
1.000
1.002
1.003
1.004
1.005
1.007
1.008
1.010
1.012
1.015
Dp
-
1.000
1.087
1.128
1.175
1.227
1.286
1.353
1.428
1.514
1.610
PROPYLENE GLYCOL SOLUTIONS
CORRECTION FACTORS FOR PROPYLENE GLYCOL SOLUTIONS
Freezing point
°C
0
-3.43
-5.30
-7.44
-9.98
-13.08
-16.86
-21.47
-27.04
-33.72
Propylene glycol
proportion
%
0
10
15
20
25
30
35
40
45
50
Qwh
-
1.000
1.008
1.014
1.021
1.030
1.042
1.055
1.071
1.090
1.112
Ph
-
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
Pa
-
1.000
1.003
1.004
1.005
1.007
1.009
1.011
1.014
1.018
1.023
Dp
-
1.000
1.050
1.077
1.111
1.153
1.202
1.258
1.321
1.390
1.467
Qwh
:
Correction factor for water flow (average water temperature 42.5 °C)
Ph
:
Correction factor for heating capacity
Pa
:
Correction factor for power consumption
Dp
:
Correction factor for pressure losses
When operating with antifreeze agents, precautions must be taken on site to prevent leakages.
When operating without antifreeze, the heating cables must be protected against freezing in the
event of frost.