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Homework Help: Heat Engines

  1. Dec 28, 2004 #1
    In class, we're being introduced to thermodynamics, and one of the topics is heat engines.

    Steam engines were also mentioned.

    Carot engines also entered the pic. They are described as ideal systems. Exactly why are Carnot engines not "real" engines, or are not possible?

    I'm sorry if these inquiries sound stupid.
    Does anyone know of any good Internet sites on heat engines or any images that may help be understand better?

    Thanks. :shy:
  2. jcsd
  3. Dec 28, 2004 #2


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    As you rightly say, the Carnot cycle is an 'ideal' one. We think of it as the most efficient cycle which could be used in an engine. It is conceptual. The efficiency determned by such a cycle is dependent only upon the difference in temperatures of the 'reservoirs' between which it operates.

    The reason this is not a practical cycle (i.e it cannot be employed physically) is because it is based upon the use of reversible 'ideal' processes, and in the real world this does not occur. Efficiencies of various kinds of real world engines are often compared to their associated Carnot efficiency, which is the highest efficiency theoretically obtainable.

    Have a look at this link for a starter:

    After that, have a google with the first, second, third (and zeroth) laws of thermodynamics, there's plenty of stuff out there.
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