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I'm not talking about Sadi Carnot's engine.

In the case of a usual heat engine, it absorbs heat from a hot reservoir, does work and releases a small amount of heat to the cold reservoir. In a cyclic process, the system undergoes many thermodynamic processes. I don't understand which process (isothermal/isobaric/isochoric) is used here.How is it a cyclic process?

One more question is it irreversible cyclic process?

In Sadi Carnot's heat engine, the cyclic process is composed of the above mentioned thermodynamic processes which makes it reversible.

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    $\begingroup$ There are many heat engines (thermodynamics cycles). Examples: en.wikipedia.org/wiki/… $\endgroup$ – valerio Jan 12 '18 at 9:43
  • $\begingroup$ @valerio92 the heat engines we use in our day to day life do not involve reversible processes? $\endgroup$ – susan J Jan 12 '18 at 9:50
  • $\begingroup$ How different is an isothermal and a cyclic process? $\endgroup$ – susan J Jan 12 '18 at 10:00
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Heat engine is a general term for any cyclic process which takes in heat from a reservoir at one temperature, deposits heat in a second reservoir at a different temperature and does work. This definition tells you nothing about the details of how this process takes place. It may involve any or none of the types of process you noticed in any combination and my be reversible or irreversible.

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  • $\begingroup$ My textbook says "Heat engine is a device by which a system is made to undergo a cyclic process that results in conversion of heat to work ". So according to you , a cyclic process may or maynot involve thermodynamic reversible processes. But if it does then it's reversible like carnot's engine $\endgroup$ – susan J Jan 12 '18 at 9:40
  • $\begingroup$ That is a slightly rougher way of phrasing my first sentence $\endgroup$ – By Symmetry Jan 12 '18 at 9:42
  • $\begingroup$ So according to you , a cyclic process may or maynot involve thermodynamic reversible processes. But if it does then it's reversible like carnot's engine $\endgroup$ – susan J Jan 12 '18 at 9:44
  • $\begingroup$ If every step the cycle is reversible, the entire cycle will be reversible. $\endgroup$ – By Symmetry Jan 12 '18 at 9:46

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