Figure 1: Schematic representation of a Vapor
Compression-Refrigeration cycle.
From point 3 to point 4, the hot pressurized gas enters the condenser.
The initial part of the cooling process in the condenser is contact with
the outer cold surface that decreases the temperature of the gas and
finally turns it back to liquid. This step is where the inside thermal
energy absorbed by the refrigerant at the evaporation stage is vented
out to atmosphere. The condenser in the back of the refrigerator is hot
as it can be easily observed.
2.4 Expansion of the subcooled and highly pressurized refrigerant
From point 4 to point 1, the high-pressure subcooled liquid passes
through the expansion device which reduces its pressure and controls the
flow of liquid into the evaporator (stage 1). The cycle is repeated
until the temperature in the refrigerator reaches the temperature set at
the thermostat otherwise the inner temperature would continue to
decrease with ice formation on the walls of the internal compartment,
something everybody can observe in a freezer.