An
air conditioner takes air from a room at
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Solution: Click For PDF Version From the data of the problem we note that
We assume
that the air conditioner is operating with maximum efficiency, which
is the efficiency of a Carnot engine. For a Carnot refrigerator the
work W done on the
engine in each cycle and the heat absorbed at the lower temperature
Therefore,
We want find
the heat absorbed from the room for each joule of electrical energy
used by the refrigerator. We should calculate
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and transfers to the outdoors, which is at
.
We have to find out the amount in joules of heat transferred from the
room for each of electrical energy required to run the refrigerator.
are related to the low and high temperatures as
.
We find