Refrigeration Cycle
The Compressor draws low pressure, lo
w te
mperature, refrigerant from the evaporat or and, by compression, raises the
refrigerant temperature and pressure. High pressure, hot, vaporized refr igerant enters the condenser, where it is cooled by
the flow of ambient air. A change of state occurs as the refrigerant cools in the condense r and it becomes a reduced
temperature, high pressure, liquid.
From the condenser, the liquid passes into the receiver drier which has three functions:
Storage vessel
for varying sy
stem refrigerant demand.
F
ilter to remove sy
stem contaminants.
Mo
isture removal via the dessicant.
With the passage through the receiver drie r completed, the liquid refrigerant, still at high pressure, enters the expansion
valve where it is metered through a contro lled orifice, which has the effect of reducing the pres sure and temperature. The
refrigerant, now in a cold atomized st ate, flows into the evaporator and cools the air passing through the matrix.
As heat is absorbed by the refrigerant, it once again changes state, into a vapor, and returns to the compressor for the
cycle to be repeated.
An automatic safety valve is incorporated in the compressor, which will operate if the system pressure rises above 41 bar.
The valve will reseat when the pressure drops below 27,6 bar.
It
em
Par
t Number
De
scription
1—Compre
ssor
2—Conden
ser
3—Re
ceiver drier
4—Expans
ion valve
5—Evaporator
6—4
-level pressure switch
The terms 'high' and 'low'
pressure (or si
de) refer to the pres sure differential betw een the compressor and expansion valve
ports. This differential is critical to sy stem fault diagnosis and efficiency checks.
