October 2012
6-19
••
The water that has absorbed heat is sent to the chiller to re-cool. Inside the
chiller, an evaporator with refrigerant inside removes heat from the chilled water
loop. As the refrigerant absorbs the excess heat, it expands and becomes a gas.
••
The refrigerant gas is then sent to a compressor prior to passing through a con-
denser, where heat is removed by the condenser water loop and the refrigerant
gas returns to the liquid phase. Condenser water is typically between 80° and
85
°F when it is sent through the chiller condenser and rises in temperature 10° to
20
°F after it has removed the heat from the refrigerant.
14
••
In the final stage, the condenser water is re-cooled in a cooling tower.
Figure 6-4. Water-Cooled ChilledWater System
In water-cooled chilled water systems, the condenser water is typically recirculated
to give off heat through evaporation. Cooling by evaporation can occur in either
an open cooling tower, where the condenser water is open to the atmosphere, or
in a closed-loop evaporative cooler, where the condenser water is not open to the
atmosphere. Both cooling towers and evaporative coolers are installed outdoors to
mechanically circulate air used to cool condenser water. Refer to
Section 6.3: Cooling
Towers
for more information on cooling towers.
Alternatively, single-pass cooling systems can be used, which rely on a source of
freshwater supply for condenser cooling water, which is ultimately discharged. In
small systems, the discharge might be to the sewer, but in large systems, it might be
discharged to a local body of water depending upon the discharge permit. Single-
pass cooling systems should be avoided if the water goes to the sewer after it is used.
14
Ibid
.
Page A-2.
(
ColdWater Out)
(
Hot Water In)
Condenser
Water
Supply
Refrigerant
(
ColdWater In)
(
Hot Water Out)
(
ChilledWater Out)
(
WarmWater In)
Chilled
Water
Supply
(
ChilledWater In)
(
WarmWater Out)
Cooling Tower
Condenser
Chiller
Evaporator
Heat Exchange
Unit
6.4
Chilled Water Systems
