Thermal Care Accuchiller EQ Series, Руководство по установке и эксплуатации

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water can also encourage biological growth that can
foul heat transfer surfaces.
To avoid the unwanted side effects associated with
water cooling, proper chemical treatment and
preventive maintenance is required for continuous
plant productivity.
Unwanted Side Effects of Improper Water Quality
•
Corrosion
•
Scale
•
Fouling
•
Biological Contamination
Cooling Water Chemistry Properties
•
Electrical Conductivity
•
pH
•
Alkalinity
•
Total Hardness
•
Dissolved gases
Chillers at their simplest have two main heat
exchangers: one that absorbs the heat from the
process (evaporator) and one that removes the heat
from the chiller (condenser). All our chillers use
stainless steel brazed plate evaporators. Our air-
cooled chillers use air to remove heat from the
chiller; however, our water-cooled chillers use either
a tube-in-tube or shell-in-tube condenser which has
copper refrigerant tubes and a steel shell. These, as
are all heat exchangers, are susceptible to fouling of
heat transfer surfaces due to scale or debris. Fouling
of these surfaces reduces the heat-transfer surface
area while increasing the fluid velocities and
pressure drop through the heat exchanger. All of
these effects reduce the heat transfer and affect the
efficiency of the chiller.
The complex nature of water chemistry requires a
specialist to evaluate and implement appropriate
sensing, measurement and treatment needed for
satisfactory performance and life. The
recommendations of the specialist may include
filtration, monitoring, treatment and control devices.
With the ever-changing regulations on water usage
and treatment chemicals, the information is usually
up-to-date when a specialist in the industry is
involved. Table 13 shows the list of water
characteristics and quality limitations.
Table 13 – Fill Water Chemistry Requirements
Water Characteristic Quality Limitation
Alkalinity (HCO
3
-
) 70-300 ppm
Aluminum (Al) Less than 0.2 ppm
Ammonium (NH
3
) Less than 2 ppm
Chlorides (Cl
-
) Less than 300 ppm
Electrical Conductivity 10-500µS/cm
Free (aggressive) Carbon Dioxide (CO
2
)† Less than 5 ppm
Free Chlorine(Cl
2
) Less than 1 PPM
HCO
3
-
/SO
4
2-
Greater than 1.0
Hydrogen Sulfide (H
2
S) Less than 0.05 ppm
Iron (Fe) Less than 0.2 ppm
Manganese (Mn) Less than 0.1 ppm
Nitrate (NO
3
) Less than 100 ppm
pH 7.5-9.0
Sulfate (SO
4
2-
) Less than 70 ppm
Total Hardness (dH)k 4.0-8.5
† Dissolved carbon dioxide calculation is from the pH and total
alkalinity values shown below or measured on the site using a test
kit. Dissolved Carbon Dioxide, PPM = TA x 2
[(6.3-pH)/0.3]
where TA =
Total Alkalinity, PPM as CaCO
3
Table 14 - Recommended Glycol Solutions
Chilled Water Temperature Percent Glycol By Volume
50°F (10°C) Not required
45°F (7.2°C) 5 %
40°F (4.4°C) 10 %
35°F (1.7°C) 15 %
30°F (-1.1°C) 20 %
25°F (-3.9°C) 25 %
20°F (-6.7°C) 30 %
CAUTION: When your application requires the
use of glycol, use industrial grade glycol
specifically designed for heat transfer systems
and equipment. Never use glycol designed for
automotive applications. Automotive glycols
typically have additives engineered to benefit
the materials and conditions found in an
automotive engine; however, these additives
can gel and foul heat exchange surfaces and
result in loss of performance or even failure of
the chiller. In addition, these additives can
react with the materials of the pump shaft
seals resulting in leaks or premature pump
failures.
WARNING: Ethylene Glycol is flammable at
higher temperatures in a vapor state. Carefully
handle this material and keep away from open
flames or other possible ignition sources.
Step 3 - Check Condenser
There are three possible types of condensers present
in the chiller: Integral air-cooled, water-cooled, or
remote air-cooled. It is important to verify the chiller
will have adequate condenser cooling for proper
chiller operation.