Carrier 69NT40-521, 69NT40-511-199 manual WATER-COOLED Condenser Optional

2.8REFRIGERATION 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.

2.9.1Water--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.)

2.9.2Water-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.

T-268-07 2-16