Operation: Refrigeration - Scotsman FME2400R Service Manual

NME1850R & FME2400R

OPERATION: Refrigeration

There are two separate refrigeration systems in this machine.
Beginning at the compressor, the refrigerant is
compressed into a high temperature gas. The
discharge line directs this gas to the condenser.
At the remote condenser the gas is cooled by air
and it then condenses into a liquid. This high
pressure liquid then goes through the liquid line to
the head pressure control valve, into the receiver,
through the liquid line valve and then through the
expansion valve.
The thermostatic expansion valve meters liquid
refrigerant into the evaporator, the volume of liquid
refrigerant depending upon the temperature of the
evaporator; warmer evaporators get more
refrigerant and colder evaporators get less.
Refrigeration Schematic
DISCHARGE
LINE
HEAD
PRESSURE
CONTROL
VALVE
LIQUID LINE
KING
VALVE
RECEIVER
At the evaporator, the refrigerant enters an area of
relatively low pressure, where it can easily "boil
off" or evaporate. As it evaporates, it absorbs
heat from the evaporator and whatever is in
contact with it (such as the water inside it). After
the evaporator, the refrigerant, now a low pressure
vapor, goes through the suction line back to
compressor, where the cycle is repeated.
System Information @ 90
Typical Suction Pressure
35 PSIG
Typical Discharge Pressue
260 PSIG
Minimum Discharge pressure (low temps)
180 PSIG
Typical Compressor Amps
Single Phase = 4.3
Three Phase = 2.8
REMOTE CONDENSER
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
LIQUID LINE
VALVE
SUCTION
LINE
COMPRESSOR
March 1995
Page 18
o o
F. air and 70
THERMOSTATIC
EXPANSION
VALVE
EVAPORATOR
F. Water: