Principles Of Refrigeration - Pontiac FIREBIRD 1972 Service Manual

1A-20 1972 PONTIAC SERVICE MANUAL
PRINCIPLES OF REFRIGERATION
In order to better understand the operation of Pontiac's
Air Conditioning System, the following principles are pre-
sented. These principles are basic to the operation of any
refrigeration system and are stated informally as follows:
Heat is a form of energy which always seeks a region of
lesser energy. For example, an ice cube (little heat energy)
absorbs heat from a substance like hot water (high heat
energy). As heat is added to a substance, a change in
temperature is usually noted. This same heat may serve to
change the state of a substance as well as its temperature.
For example, when water reaches a temperature of 212°F.
additional heat will not change the temperature of the
water but will change its state from liquid to vapor. This
same reasoning applies when heat is dissipated. As water
vapor cools and reaches its condensation point, heat can
be dissipated with no change in temperature. Once the
change in state has occurred, however, additional changes
in heat will change temperature.
Pressure also has an important effect on heat and tempera-
ture. For example, the vaporization or boiling point of
water can be raised above 212°F. by increasing the pres-
sure on the water. An engine cooling system accomplishes
this by use of a pressurized system which raises the boiling
point well above 212°F.
COMPRESSOR
I
* - RECEIVER-DEHYDRATOR
ASSEMBLY
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LOW PRESSURE GAS
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[ - J
: : : : . . * . * . * . *
LOW PRESSURE LIQUID
HIGH PRESSURE LIQUID
....................... :.:.: . . . . . . . . . . . . . . . . . . . . . . . . .
:;;::E:;;:;:;:;:;:!<:;:;:>;:;;:;$?:;:;
0
:.:.:.:.:.:.:
...........
. . .
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HIGH PRESSURE GAS
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1 - 1
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SUPERHEATED G*S
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Fig. 1A-17 Refrigeration Circuit