Carrier 23XL Specifiche Scaricare il pdf (Pagina 7)

Cooler — This vessel (also known as the evaporator) is

located underneath the compressor. The cooler is main-

tained at low temperature/pressure so that evaporating re-

frigerant can remove heat from water/brine ﬂowing through

its internal tubes.

Condenser — The condenser operates at a higher

temperature/pressure than the cooler and has water ﬂow-

ing through its internal tubes to remove heat from the

refrigerant.

Motor-Compressor — The motor-compressor main-

tains system temperature/pressure differences and moves the

heat carrying refrigerant from the cooler to the condenser.

Muffler-Oil Separator — The muffler provides acous-

tical attenuation.

Refrigerant/oil separation is accomplished by the oil sepa-

rator. Discharge gas enters near the midsection and leaves

near the top, while the separated oil drains out through the

bottom and ﬂows through a horizontal oil sump/ﬁlter

assembly (Frame 1 and 2 machines).

Frame 1 and 2 machines have an oil separator and a muf-

ﬂer assembly. On Frame 4 machines, the muffler is located

inside the oil separator.

Control Center — The control center is the user inter-

face for controlling the machine and regulating the ma-

chine’s capacity to maintain the proper chilled water

temperature. The control center:

• registers cooler, condenser, and lubricating system

pressures

• shows machine operating condition and alarm shutdown

conditions

• records the total machine operating hours, starts, and the

number of hours the machine has been currently running

• sequences machine start, stop, and recycle under micro-

processor control

• provides access to other Carrier Comfort Network devices

Factory-Mounted Starter (Optional Accessory)

—

The starter allows for the proper starting and discon-

necting of electrical energy for the compressor-motor, oil heater

(Frame 1 and 2 machines), and control center.

Storage Vessel (Optional) — Two sizes of storage

vessels are available. The vessels have double relief valves,

a magnetically coupled dial-type refrigerant level gage,

a 1-in. FPT drain valve, and a

⁄

-in. male ﬂare vapor

connection for the pumpout unit. A 30-in.-0-400 psi

(-101-0-2750 kPa) gage is also supplied with each unit.

NOTE: If a storage vessel is not used at the jobsite, factory-

installed optional isolation valves may be used to isolate the

machine charge in either the cooler or condenser. An op-

tional pumpout compressor system is used to transfer refrig-

erant from vessel to vessel.

REFRIGERATION CYCLE

The compressor continuously draws refrigerant vapor from

the cooler. As the compressor suction reduces the pressure

in the cooler, the remaining refrigerant boils at a fairly low

temperature (typically 38 to 42 F [3 to 6 C]). The energy

required for boiling is obtained from the water ﬂowing through

the cooler tubes. With heat energy removed, the water be-

comes cold enough for use in an air-conditioning circuit or

process liquid cooling.

After taking heat from the water, the refrigerant vapor is

compressed. Compression adds still more energy, and the re-

frigerant is quite warm (typically 130 to 160 F [54 to

71 C]) when it is discharged from compressor into

condenser.

Relatively cool (typically 65 to 85 F [18 to 29 C]) water

ﬂowing into the condenser tubes removes heat from the re-

frigerant and the vapor condenses to liquid.

The liquid refrigerant passes through oriﬁces into the FLASC

(Flash Subcooler) chamber (Fig. 3 and 4). Since the FLASC

chamber is at a lower pressure, part of the liquid refrigerant

ﬂashes to vapor, thereby cooling the remaining liquid. The

FLASC vapor is recondensed on the tubes which are cooled

by entering condenser water. The liquid then passes through

a ﬂoat valve assembly which forms a liquid seal to keep FLASC

chamber vapor from entering the cooler.

An optional economizer can be installed between the con-

denser and cooler. In this case, the ﬂoat valve meters the

refrigerant liquid into the economizer. Pressure in this cham-

ber is intermediate between condenser and cooler pressures.

At this lower pressure, some of the liquid refrigerant ﬂashes

to gas, cooling the remaining liquid. The ﬂash gas, having

absorbed heat, is returned directly to the compressor at a point

after suction cutoff (Fig. 5). Here it is mixed with gas from

the suction cut-off point to produce an increase in the mass

ﬂow of refrigerant transported and compressed without ei-

ther an increase in suction volume or a change in suction

temperature. Rather than providing the same capacity with

less power, the compressor provides substantially increased

capacity with only a slight increase in power requirements.

The cooled liquid refrigerant in the economizer is me-

tered through an oriﬁce or linear ﬂoat valve (depending upon

machine design) into the cooler. Because pressure in the cooler

is lower than economizer pressure, some of the liquid flashes

and cools the remainder to evaporator (cooler) temperature.

The cycle is now complete.

MOTOR COOLING CYCLE

The motor is cooled by liquid refrigerant taken from the

bottom of the condenser vessel. The ﬂow of refrigerant is

maintained by the pressure differential that exists due to com-

pressor operation. The refrigerant ﬂows through an isolation

valve, in-line ﬁlter/drier, and a sight glass/moisture indicator

(dry-eye), into the motor through the motor spray nozzle.

See Fig. 3 and 4.

The motor spray nozzle is oriﬁced to control refrigerant

ﬂow through the gaps in the rotor and axial vent holes. The

refrigerant collects in the bottom of the motor casing and

then drains into the cooler through the motor cooling drain

line.

The motor is protected by a temperature sensor imbedded

in the stator windings. Motor temperatures above the MO-

TOR WINDING TEMPERATURE OVERRIDE THRESH-

OLD (see Capacity Overrides section, page 29) will over-

ride the chilled water temperature capacity control to hold.

If the motor temperature rises 10 F (5.5 C) above this thresh-

old, the slide valve will unload. If the motor temperature rises

above the safety limit, the compressor will shut down.

LUBRICATION CYCLE

Summary —

The 23XL does not require an oil pump.

Oil ﬂow is driven by differential pressure between con-

denser and evaporator. This system pressure difference holds

the potential to push the oil through the oil separator and

ﬁlter into the compressor rotors, bearings, and slide valve.

The cycle is referred to as a ‘‘high side’’ oil system. See Fig.

3,4, and 5.

Details — The oil system:

• lubricates the roller bearings which support the male and

female rotors, and the ball bearings of the 23XL

compressor.

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Carrier 23XL Specifiche Pagina 7

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