50
9.4 Cooling Water Control
9.4.1 Temperature control
Cooling water condition effects on the operation cycle of the chiller-heater greatly. Generally, too
low or too high temperature of cooling water may cause the following troubles :
Too low temperature of cooling water ------- Solution crystallization
Too high temperature of cooling water ---- High pressure trip and capacity drop
In general, absorption chiller-heaters are designed to be operated at 32
℃
of cooling water inlet
temperature. However, it is better for the absorption chiller-heater to be operated at lower cooling
water temperature in the range of no trouble. Because the lower the temperature, the more the
fuel consumption rate is improved. (Note that the allowable lowest cooling water inlet temperature
is about 22
℃
).
On the contrary, as the cooling water temperature goes down, the solution concentration becomes
weak. Therefore, the range of capacity control becomes narrow to some extent because of
charged quantity of refrigerant.
9.4.2 Water quality control for cooling water
Since the contamination of cooling water may cause to lower the heat exchange efficiency due to
deposit of scales on the heat exchangers and may also cause a serious accident such as
submersion of the chiller-heater by the corrosion damage of heat transfer tubes, perform water
quality control as per the following procedure.
(1) Make-up water quality
The cooling water is required to satisfy the standard shown in the table below. If the cooling
water fails to satisfy the standard, it is required to be treated properly or passed without
recirculation.
(2) Standard of cooling water quality
Table 9.3 Cooling Water Quality Standard Recommended by Japan Refrigeration and Air-
conditioning Industry (JRA-GL-02-1994)
Cooling Water System
Tendency
Circulation
Pass Way
Circulation
Water
Make-up
Water
Pass Way
Water
Corro-
sion
Scale
Standard
Item
PH(PH(at 25
℃
)
6.5~8.2
6.0~8.0
6.8~8.0
○
○
Conductivity (ms/m) (25
℃
)
(
S/cm) (25
℃
)
≤80
{≤800}
≤30
{≤300}
≤40
{≤400}
○
○
Chlorine ion (mgCl
-
/ℓ)
≤200
≤50
≤50
○
Sulfuric ion (mgSO
4
2
-
/ℓ)
≤200
≤50
≤50
○
M Alkalinity (PH4.8)(mgCaCO
3
/ℓ)
≤100
≤50
≤50
○
Total hardness (mgCaCO
3
/ℓ)
≤200
≤70
≤70
○
Calcium hardness (mgCaCO
3
/ℓ)
≤150
≤50
≤50
○
Ionized silica (mgSiO
2
/ℓ)
≤50
≤30
≤30
○
Reference
Item
Total iron (mgFe/ℓ)
≤1.0
≤0.3
≤1.0
○
○
Copper
(mgCu/ℓ) ≤0.3
≤0.1
≤1.0
○
Sulfur ion (mgS
2
-
/ℓ)
Not detected
○
Ammonium ion (mgNH
4
/ℓ) ≤1.0
≤0.1
≤1.0
○
Residuary chlorine (mgCl/ℓ) ≤0.3
≤0.3
≤0.3
○
Isolated carbonic acid (mgCO
2
/ℓ)
≤4.0
≤4.0
≤4.0
○
Index of stability
6.0~7.0
-
-
○
○
(3) Blow-down of cooling water
Summary of Contents for HDFN-80-1400
Page 11: ...11 Fig 1 1 External View of Chiller heater...
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Page 66: ...66 Fig 8 Lithium Bromide Temperature Specific Gravity Concentration Curve...
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