AIR COOLED CHILLERS
ETHYLENE GLYCOL SOLUTION CAPACITY CORRECTION
(Antifreeze)
13
When operating in areas with temperatures below 32
0
F (0
0
C), cooler protection in the form of Ethylene glycol solution
(brine solution) is required to protect cooler from low ambient freeze-up. This brine solution must be added to water loop
to bring down the freezing point with a difference of 15
0
F (8
0
C) below minimum operating ambient temperature.
Ethylene glycol solution causes a variation in unit performance. To obtain the effective performance, it is necessary to
multiply the water performance data by correction factors corresponding to the ambient temperature or Ethylene glycol
percentage indicated in the following table.
EXAMPLE:
English system- Determine Ethylene glycol percentage by weight and correction factors at 38
0
F ambient
temperature.
From the above table, Ethylene glycol water solution concentration (percentage by weight) corresponding to 38
0
F ambi-
ent temperature is 12% by weight.
Find the correction factors corresponding to 38
0
F ambient temperature from the table.
Cooling capacity correction factor is 0.985, Flow correction factor is 1.02, Pressure drop correction factor is 1.07.
Apply these correction factors for corrected system performance values.
TONS (E.G. SOLUTION) = Tons (water) x Cooling capacity correction factor.
BRINE (E.G. SOLUTION) FLOW (GPM) = Flow (water) x Flow correction factor.
BRINE (E.G. SOLUTION) PRESSURE DROP = Water pressure drop (Ft.) x Pressure drop correction factor.
EXAMPLE: Metric
system- Determine Ethylene glycol percentage by weight and correction factors where 3.3
0
C ambi-
ent temperature.
From the above table, Ethylene glycol water solution concentration (percentage by weight) corresponding to 3.3
0
C
ambient temperature is 12% by weight.
Find the correction factors corresponding to 3.3
0
C ambient temperature from the table.
Cooling capacity correction factor is 0.985, Flow correction factor is 1.02, Pressure drop correction factor is 1.07.
Apply these correction factors for corrected system performance values.
KW (E.G. SOLUTION) = KW (water) x Cooling capacity correction factor.
BRINE (E.G. SOLUTION) FLOW (L/S) = KW (water) x Flow correction factor.
BRINE (E.G. SOLUTION) PRESSURE DROP = Water pressure drop (kPa) x Pressure drop correction factor.
Note:
Correction factors apply to published chilled water performance rating from 40
0
F to 50
0
F (4.4
0
C to 10
0
C) LCWT.
ETHYLENE GLYCOL % BY WEIGHT
0%
12%
22%
30%
36%
41%
46%
50%
Freezing point of Ethylene glycol solution
0
0
C (32
0
F)
-5
0
C (23
0
F)
-10
0
C (14
0
F)
-15
0
C (5
0
F)
-20
0
C (-4
0
F)
-25
0
C (-13
0
F) -30
0
C (-22
0
F) -35
0
C (-31
0
F)
Ambient temperature
8.3
0
C (47
0
F) 3.3
0
C (38
0
F) -1.7
0
C (29
0
F) -6.7
0
C (20
0
F) -11.7
0
C (11
0
F) -16.7
0
C (2
0
F) -21.7
0
C (-7
0
F) -26.7
0
C (-16
0
F)
Cooling capacity correction factor
1.0
0.985
0.980
0.974
0.970
0.965
0.964
0.960
Water flow correction factor
1.0
1.02
1.04
1.075
1.11
1.14
1.17
1.20
Pressure drop correction factor
1.0
1.07
1.11
1.18
1.22
1.24
1.27
1.30
