Why is the Carnot Cycle so Important?

[SUDOnym]

All reversible cyclic processes (engines) have the same efficiency: 1-T2/T1.

And Carnot demostrated this efficiency with the Carnot Cycle and went on to use this to demonstrate that this was the upper limit for efficiency.

My question is, why is it that there is such importance placed on the Carnot Cycle? ie. since all reversible processes have this same efficiency couldn't we say just take an engine whos path is:

a isobaric b isochoric c isobaric d isochoric a isobaric b isochoric c isobaric d isochoric ...and so on.

and use this engine to also demonstrate that the upper limit is 1-T2/T1? is it simply that with the carnot cycle, which is:

a isotherm b adiabat c isotherm d adiabat a isotherm b adiabat c isotherm d adiabat ... and so on

makes it easy to demonstrate this result?

 

[Drakkith]

See here. http://en.wikipedia.org/wiki/Carnot_cycle#Efficiency_of_real_heat_engines

1-T2/T1 is the efficiency of the carnot cycle, however it is NOT the efficiency of a real engine. Real engines have losses that will always make them less efficient than max.

 

[Andrew Mason]

My question is, why is it that there is such importance placed on the Carnot Cycle? ie. since all reversible processes have this same efficiency couldn't we say just take an engine whos path is:

a isobaric b isochoric c isobaric d isochoric a isobaric b isochoric c isobaric d isochoric ...and so on.

and use this engine to also demonstrate that the upper limit is 1-T2/T1? is it simply that with the carnot cycle, which is:

a isotherm b adiabat c isotherm d adiabat a isotherm b adiabat c isotherm d adiabat ... and so on

makes it easy to demonstrate this result?

In order to create a reversible cycle, all heat flow has to occur at infinitessimal temperature differences. In other words, heat flow from the hot reservoir to the system has to occur with the reservoir and system at the same temperature AND heat flow from the system to the cold reservoir has to occur with the system and cold reservoir at the same temperature. In order to get from the hot temperature to the cold temperature and vice-versa without increasing entropy, the expansions and compressions cannot involve heat flow.

So any reversible cycle must be equivalent to the Carnot cycle: isothermal (expansion), adiabatic (expansion), isothermal (compression), adiabatic (compression).

AM

 

[Curl]

My question is, why is it that there is such importance placed on the Carnot Cycle? ie. since all reversible processes have this same efficiency couldn't we say just take an engine whos path is:

a isobaric b isochoric c isobaric d isochoric a isobaric b isochoric c isobaric d isochoric ...and so on.

this cycle is highly irreversible and much less efficient than carnot's cycle