2-16
T-268-07
2.8 REFRIGERATION CIRCUIT WITH THE
WATER-COOLED CONDENSER (Optional)
Starting at the compressor, the suction gas is
compressed to a higher temperature and pressure.
When operating with the water-cooled condenser, the
gas flows through the discharge service valve into the
pressure regulator valve that is normally open. The
pressure regulator valve may restrict the flow of
refrigerant to maintain a minimum discharge pressure
of 5
kg/cm
@
(70 psig).
Refrigerant gas then moves through the air-cooled coil
to the water-cooled condenser. As the refrigerant flows
across the water chilled coiled tube bundle, it is cooled
to saturation temperature and exits the condenser as a
high pressure/saturated liquid.
From the water-cooled condenser, the liquid refrigerant
continues through the manual liquid line valve, the
filter-drier (which keeps refrigerant clean and dry), a
moisture-liquid indicator, and a heat exchanger that
increases subcooling of liquid refrigerant to the
thermostatic expansion valve. As the liquid refrigerant
passes through the orifice of the expansion valve, some
of it vaporizes into a gas (flash gas). Heat is absorbed
from the return air by the balance of the liquid, causing it
to vaporize in the evaporator coil. The vapor then flows
through the suction modulation valve (and suction
solenoid valve under some conditions) to the
compressor.
The thermostatic expansion valve bulb (on the suction
line near the evaporator coil outlet) controls the
thermostatic expansion valve, maintaining a constant
superheat at the coil outlet regardless of load conditions
except at abnormally high container temperatures such
as during pulldown (valve at maximum operating
pressure condition).
2.9 WATER-COOLED CONDENSER (Optional)
The water-cooled condenser is used when cooling water
is available and heating the surrounding air is
objectionable, such as in a ship’s hold.
The water-cooled condenser is of the shell and coil type,
with water circulating through the cupro-nickel coil.
The refrigerant vapor is admitted to the shell side and is
condensed on the outer surface of the coil.
2.9.1
Water--Cooled Condenser with Water
Pressure Switch (WP)
For operation of the refrigeration unit with the
water-cooled condenser, do the following:
a. Connect the water supply line to the inlet side of
condenser and the discharge line to the outlet side of
the condenser.
b. Maintain a flow rate of 11 to 26 liters per minute (3
to 7 gallons per minute). The water pressure switch
will open to de-energize the condenser fan relay.
The condenser fan motor will stop and will remain
stopped until the water pressure switch closes.
The refrigeration unit operating with the water-cooled
condenser will perform as outlined in section 4.4 except
that the condenser fan motor is stopped in all modes.
To shift to air-cooled condenser operation, do the
following:
Disconnect the water supply and the discharge line to
the water-cooled condenser. The refrigeration unit will
shift to air-cooled condenser operation when the water
pressure switch closes. (Refer to section 2.2.)
2.9.2
Water-Cooled Condenser with Condenser
Fan Switch (CFS)
For operation of the refrigeration unit with the
water-cooled condenser with (CFS), do the following:
a. Connect the water supply line to the inlet side of
condenser and the discharge line to the outlet side of
the condenser.
b. Maintain a flow rate of 11 to 26 lpm (3 to 7 gpm).
c. Set CFS switch to position ”O” when water is
supplied to the water-cooled condenser. This will
de-energize the condenser fan relay. The condenser
fan motor will stop and will remain stopped until
the CFS switch is set to position ”1.”
The refrigeration unit operating with the water-cooled
condenser and the CFS switch in position ”O,” will
perform as outlined in section 4.4 except that the
condenser fan motor is stopped in all modes.
WARNING
When water flow is below 11 lpm (3 gpm) or
when water-cooled operation is not in use,
the CFS switch MUST be set to position ”1”
or the unit will not operate properly.
To shift to air-cooled condenser operation, do the
following:
Turn the unit OFF and set the CFS switch to position
”1.” Disconnect the water supply and the discharge line
to the water-cooled condenser. The unit should now
perform as outlined in section 4.4.
