Technical data

Precision Air Conditioning
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V
Precision Air Conditioning
Technical Manual : 6258867 F 07/2012
63
Design Data - Chilled Water Models
ETHYLENE GLYCOL CORRECTION FACTORS
For conditions outside those quoted, please refer to Airedale.
Glycol is recommended when a supply water temperature of +5°C or below is required or
when static water can be exposed to freezing temperatures.
The effect of glycol in the system has a direct effect upon the Cooling Duty, the Design
Flow Rate and the unit Pressure Drop.
The Use of Glycol
To approximate the effect of glycol on unit performance, the following correction factors
when applied can be used as a guide.
Where:
Q = Total Cooling Capacity (TC) (kW)
Qw = Equivalent Water Cooling Capacity (kW), refer to Performance Data - Chilled
Water Models.
V
&
= Corrected Flow Rate.
DT = Temperature difference between Water/Glycol Inlet/Outlet (°C).
DP = Maximum Water/ Glycol Pressure Drop for the indoor unit (kPa).
DP
w
= Equivalent Water Pressure Drop for indoor unit (kPa), use the corrected flow
rate
V
&
. Refer to Design Data - Chilled Water Models.
Ethylene Glycol (Volume) / Freezing Point °C
10% / -4°C 20% / -9°C 30% / -15°C 40% / -23°C
Q Corrected Cooling Duty = Qw Cooling Capacity 0.980 0.940 0.890 0.830
V
&
Corrected Flow Rate =
Qw/DT
Flow Rate 0.242 0.248 0.252 0.251
DP
Corrected Pressure Drop =
DP
w
Pressure Drop
x by
1.041 1.083 1.133 1.200
Example: V50CW operating at 7/12, 24°C/45% RH Ambient, 20% Ethylene Glycol
Ethylene Glycol (Volume) / Freezing Point °C
10% / -4°C
20% / -9°C
30% / -15°C 40% / -23°C
Q
54.33 kW
= Qw 57.8 kW 0.980
0.940
0.890 0.830
V
&
2.86 l/s
=
Qw/DT
(12 - 7 = 5DT) =
11.56 0.242
0.248
0.252 0.251
DP
45.49 kPa
=
DP
w
42 kPa
x by
1.041
1.083
1.133 1.200
CHILLED WATER