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Heat engine examples

The master-equations for generic heat-engine problems are the conservation of energy and the heat-temperature
relation for a Carnot engine:

The question will give you one of , and , and the master-equations give you the other two.

Try these problems for yourself before checking the detailed answers!

*Ex. 1* A power station contains a heat engine operating between two heat reservoirs,
one consisting of steam at C and the other consisting of water at C. What is the
maximum amount of electrical energy which can be produced for every Joule of heat extracted from
the steam?
Answer: J. Details here.

*Ex. 2* When a fridge stands in a room at C, the motor has to extract 500W of
heat from the cabinet, at C, to compensate for less than perfect insulation.
How much power must be supplied to the motor if its efficiency is 80% of the maximium achievable?
Answer: J. Details here.

** Previous:** Reversible processes
Judith McGovern
2004-03-17