Scotsman NME1854R Service Manual page 19

OPERATION: Refrigeration
There are two separate refrigeration systems in this machine.
At the compressor, 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.
At the evaporator, the refrigerant enters an area of
relatively low pressure, where it can easily "boil off"
Refrigeration Schematic
DISCHARGE
LINE
HEAD
PRESSURE
CONTROL
VALVE
RECEIVER
LIQUID LINE
KING
VALVE
January 2000
Page 19
NME1854R & FME2404R
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.
REMOTE CONDENSER
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
LIQUID LINE
VALVE
SUCTION
LINE
COMPRESSOR
THERMOSTATIC
EXPANSION
VALVE
EVAPORATOR