Carrier 48/50PG Series - Subcooler Heat Exchanger (SHX 48;50 PG20- -28 Only)

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NETWORK
OPTIONS
REMOTE
CCN SITE
AUTODIAL
GATEWAY
NON CARRIER
HVAC
EQUIPMENT
TERMINAL
SYSTEM
MANAGER
TCU
ROOFTOP
UNIT
DAV AIR
TERMINAL
TCU
TCU
DAV AIR
TERMINAL
AIR DISTRIBUTION-DIGITAL AIR VOLUME CONTROL (DAV)
DAV FAN
POWERED
MIXING
BOX
TO
ADDITIONAL
TERMINALS
HEATING/COOLING UNITS
BUILDING SUPERVISOR
ROOFTOP
UNIT
CL
ROOFTOP
UNIT
CL
ROOFTOP
UNIT
CL
ROOFTOP
UNIT
CL
CCN BUS
CL
COMFORT
CONTROLLER
LEGEND
CCN -- Carrier Comfort Networkr
CL -- ComfortLinkt Controls
DAV -- Digital Air Volume
HVAC -- Heating, Ventilation, and
Air Conditoning
TCU -- Terminal Control Unit
C07030
Fig. 51 -- CCN System Architectur e
Subcooler Heat Exchanger
(SHX -- 48/50PG20--28 Only)
The purpose of the subcooler heat exchanger (SHX) and the
subcooler TXV is to increase the capacity of the evaporator by
sending subcooled liquid refrigerant into the evaporator. Normally,
the condenser subcools the liquid refrigerant by approximately
10_F. The SHX adds another 10_Fto15_F degrees of subcooling
before the refrigerant reaches the evaporator. This allows the
refrigerant to absorb more heat from the mixed air, thereby
providing more cooling capacity.
The subcooler functions by taking a small percentage of the high
pressure, medium temperature liquid refrigerant which exits the
condenser and converting it into a low pressure, low temperature
gas. This is accomplished by using the subcooler TXV. The gas is
then routed through a reverse--flow heat exchanger (SHX), which
transfers heat from the remaining liquid refrigerant in the liquid
line to the reverse flow gas refrigerant. The moderate temperature
gas is then sent to the compressor to complete the loop and the
cooler liquid refrigerant continues its normal path to the main TXV
and the evaporator. (See Fig. 52.)
COND
COMPRESSOR
SUBCOOLER
HX
SUBCOOLER TXV
MAIN TXV
EVAP
C07202
Fig. 52 -- Subcooler Operation
48/50PG and PM