Refrigeration Cycle - Carrier AquaEdge 19XR Start-Up, Operation And Maintenance Instructions Manual

REFRIGERATION CYCLE

The compressor continuously draws refrigerant vapor from the
cooler at a rate set by the amount of guide vane opening. As the
compressor suction reduces the pressure in the cooler, the re-
maining refrigerant boils at a fairly low temperature (typically
38 to 42°F [3 to 6°C]). The energy required for boiling is ob-
tained from the water flowing through the cooler tubes. With
heat energy removed, the water becomes cold enough to use in
an air-conditioning circuit or process liquid cooling.
After taking heat from the water, the refrigerant vapor is com-
pressed. Compression adds still more heat energy and the re-
frigerant is quite warm (typically 98 to 102°F [37 to 40°C])
when it is discharged from the compressor into the condenser.
Relatively cool (typically 65 to 90°F [18 to 32°C]) water flowing
into the condenser tubes removes heat from the refrigerant, and
the vapor condenses to liquid. The liquid refrigerant passes
through orifices into the FLASC (flash subcooler) chamber.
Since the FLASC chamber is at a lower pressure, part of the liq-
uid refrigerant flashes to vapor, thereby cooling the remaining
ROTOR
THERMOSTATIC
EXPANSION
VALVE (TXV)
Fig. 3 — Refrigeration Cycle — 19XR Two-Stage Compressor Frame Sizes 6 and 7
ISOLATION
VALVE
(OPTION)
ORIFICE
FITTING TRANSMISSION
COMPRESSOR
IMPELLERS
OIL COOLER
BACK PRESSURE
ORIFICE (INTEGRAL
TO MOTOR SHELL)
COOLER
ISOLATION
VALVE
(OPTION)
liquid. The FLASC vapor is recondensed on the tubes which are
cooled by entering condenser water. The liquid drains into a high
side float valve chamber between the FLASC chamber and the
economizer. The refrigerant is then metered into the economizer.
In the economizer, due to lower pressure, as liquid enters the
chamber, some liquid will flash into a vapor and cool the remain-
ing liquid. The separated vapor flows to the second stage of the
compressor for greater cycle efficiency. A damper valve located
on the economizer line to the compressor acts as a pressure-reg-
ulating device to stabilize low load, low condensing pressure op-
erating conditions. The damper will back up gas flow and there-
by raises the economizer pressure to permit proper refrigerant
flow through the economizer valve during those conditions.
The cooled liquid left in the economizer flows through a low
side float valve and then into the cooler. The float valve forms a
liquid seal to keep vapor from entering the cooler. Liquid refrig-
erant passes through the low side valve into the cooler. The re-
frigerant is now at a temperature and pressure at which the cycle
began. Figure 3 summarizes the refrigeration cycle.
FLASC CHAMBER
HIGH SIDE FLOAT CHAMBER
HOT GAS BYPASS
HIGH SIDE FLOAT VALVE
DAMPER
VALVE
REFRIGERANT
ISOLATION VALVE
ECONOMIZER
LOW SIDE
FLOAT VALVE
7
CONDENSER
WATER
HGBP
VALVE
REFRIGERANT
LIQUID
REFRIGERANT
VAPOR
REFRIGERANT
LIQUID/VAPOR
CHILLED
WATER