Daikin McQuay AGZ-D, Руководство по эксплуатации и техническому обслуживанию, Страница: 5 / 82

OMM 1087 AGZ 025D through 190D 5
Glycol Solutions
The use of a glycol/water mixture in the evaporator to prevent freezing reduces system capacity and
efficiency, as well as increase pressure drop. The system capacity, required glycol solution flow rate,
and pressure drop with glycol may be calculated using Table 1.
1.
Capacity – Multiply the capacity based on water by the Capacity correction factor from Table 2
through Table 5.
2. Flow – Multiply the water evaporator flow by the Flow correction factor from Table 2 through
Table 5 to determine the increased evaporator flow due to glycol.
If the flow is unknown, it can be calculated from the following equation
3. Pressure drop -- Multiply the water pressure drop from page 10 by Pressure Drop correction
factor from Table 2 through Table 5. High concentrations of propylene glycol at low temperatures
can cause unacceptably high pressure drops.
4. Power -- Multiply the water system power by Power correction factor from Table 2 - Table 5.
Test coolant with a clean, accurate glycol solution hydrometer (similar to that found in service stations)
to determine the freezing point. Obtain percent glycol from the freezing point tables below. It is
recommended that a minimum of 25% solution by weight be used for protection against corrosion or
that additional compatible inhibitors be added.
Concentrations above 35 % do not provide any additional burst protection and should be carefully
considered before using.
Table 1, Flow/Tons/Delta-T Relationship
Glycol Flow (gpm)
Factor Correction Flow
T Delta
glycol Capacity Tons


) ( 24
Glycol Flow (l/s)
Factor Correction Flow
T Delta
Capacity kW

 
18 . 4
!
WARNING
Do not use an automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze
contains inhibitors which will cause plating on the copper tubes within the chiller evaporator. The type
and handling of glycol used must be consistent with local codes
Table 2, Ethylene Glycol Factors for Models AGZ 025D to 130D
Freeze Point
% E.G.
o
F
o
C
Capacity Power Flow PD
10
26 -3.3 0.998 0.998 1.036 1.097
20
18 -7.8 0.993 0.997 1.060 1.226
30 7 -13.9 0.987 0.995 1.092 1.369
40 -7 -21.7 0.980 0.992 1.132 1.557
50 -28 -33.3 0.973 0.991 1.182 1.791
Table 3, Propylene Glycol Factors for Models AGZ 025D to 130D
Freeze Point
% P.G.
o
F
o
C
Capacity Power Flow PD
10
26 -3.3 0.995 0.997 1.016 1.100
20 19 -7.2 0.987 0.995 1.032 1.211
30 9 -12.8 0.978 0.992 1.057 1.380
40 -5 -20.6 0.964 0.987 1.092 1.703
50 -27 -32.8 0.952 0.983 1.140 2.251