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Operation:
The evaporator is a heat exchanger into which the
refrigerant fluid is sprayed in order to absorb the
heat in the air stream to be cooled.
It cannot be dissociated from the expansion valve.
The pressure of the refrigerant fluid is reduced by
the expansion valve before it enters the evaporator.
In the evaporator, heat is exchanged between the
cold fluid and the air entering the cabin.
Vaporised liquid
Evaporator
Heat is exchanged between the outdoor air and the cold
surface of the evaporator, air is cooled.
A phase change occurs from liquid to gaseous.
Outdoor air
Cabin air
In the course of the heat exchange with the air
entering the cabin, the state of the refrigerant
gradually changes inside the evaporator.
At the evaporator outlet, the change in state is total
and the fluid is 100% gaseous.
Design:
The evaporator is designed according to the volume
of the cabin and the specific demands of the
applications.
The expansion valve and the evaporator form an
essential duo in the production of cold in the loop.
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Practical advice:
The evaporator must be replaced if it is
clogged, pierced or contaminated with
persistent mould. The most common problems
with evaporators are:
g
Perforation due to corrosion
g
Fins blocked by soiling or frost
g
Leaks from the couplings
When replacing the evaporator, always replace
the receiver drier and the expansion valve/ori-
fice tube.
The evaporator