Scotsman NME654R - Manual (Page 18)

OPERATION: Refrigeration
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
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”
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.
NME654R & FME804R
January 2000
Page 18
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
DISCHARGE
LINE
LIQUID LINE
HEAD
PRESSURE
CONTROL
VALVE
RECEIVER COMPRESSOR
Refrigeration Schematic
KING
VALVE
SUCTION
LINE
THERMOSTATIC
EXPANSION
VALVE
LIQUID LINE
VALVE
REMOTE CONDENSER
EVAPORATOR