Flooded type water cooled screw chiller (MIC)
MCAC-CTSM-2018-1
74
the water by mixing it with an inert gas as it will over-oxygenate it by mixing it with pure oxygen.
Altering oxygenation conditions destabilizes copper hydroxides and enlarges particles.
10. Specific resistance
– electric conductivity: Higher specific resistance, shows corrosion. Conductivity
<20μV/cm (25
℃
) is desirable. A neutral environment favors maximum specific resistance values. For
electric conductivity values of 200-6000S/cm are recommended.
11. PH: Ideal case pH neutral at 20-25°C 7 < pH < 8.5. If the water circuit must be emptied for longer
than one month, the complete circuit must be placed under nitrogen charge to avoid any risk of
corrosion by differential aeration. Charging and removing heat exchange fluids should be done with
devices included in the water circuit by the installer. Never use the unit heat exchangers to add heat
exchange fluid. Piping systems must be properly vented, with no stress on water box nozzles and
covers. Use flexible connections to reduce the transmission of vibrations. Water flowing through the
cooler and condenser must meet site requirements. Measure the pressure drop across cooler and
condenser, and compare it with the nominal values .If pump out storage tank and/or pump out
equipment are installed, ensure the pump out condenser water has been piped in. Check for
field-supplied shutoff valves and controls as specified in the job data. Check for refrigerant leaks on
field-installed piping.
2). Performance adjustment factors
Ethylene and Propylene Glycol Factors
A glycol solution is required when the unit in the mentioned condition. The use of glycol will reduce
the performance of the unit depending on concentration.
Ethylene Glycol
Ethylene
glycol
Evaporator side
Quality of
glycol
(
%
)
Cooling
capacity
modification
Power
modification
Water flow
modification
Water
resistance
Freezing
point
℃
30
0.972
0.99
1.013
1.215
-16
35
0.971
0.984
1.04
1.267
40
0.965
0.977
1.074
1.325
-23
45
0.96
0.967
1.121
1.389
50
0.946
0.955
1.178
1.458
-35
Condenser side
30
0.991
1.02
1.013
1.164
-16
35
0.989
1.027
1.04
1.212
40
0.986
1.032
1.074
1.261
-23
45
0.984
1.037
1.121
1.309
50
0.98
1.044
1.178
1.362
-35
Note: the freezing point is not shown here. Please calculate it according to the i
nterpolation method.
Propylene Glycol
Propylene
glycol
Evaporator side
Quality of
glycol
(
%
)
Cooling
capacity
modification
Power
modification
Water flow
modification
Water
resistance
Freezing
point
℃
30
0.968
0.969
1.01
1.16
-13
35
0.964
0.955
1.028
1.287
40
0.955
0.937
1.05
1.4
-21
45
0.945
0.914
1.078
1.502
50
0.929
0.89
1.116
1.604
-33