Operation: Refrigeration - Scotsman NME650R Service Manual

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.
DISCHARGE
LINE
HEAD
PRESSURE
CONTROL
VALVE
Refrigeration Schematic
LIQUID LINE
KING
VALVE
RECEIVER
August 1993
Page 17
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.
REMOTE CONDENSER
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
THERMOSTATIC
LIQUID LINE
VALVE
SUCTION
LINE
COMPRESSOR
NME650R
EXPANSION
VALVE
EVAPORATOR