What Happens to the Work Output in a Carnot Cycle?

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In a Carnot cycle, the reversible isothermal expansion of gas at high temperature results in work done on the surroundings, but this work does not contribute to the total work output of the cycle due to the nature of thermodynamic processes. According to the first law of thermodynamics, the heat transferred equals the work done plus the change in internal energy, which is zero in a cyclic process. The discussion also touches on the role of a boiler in a heat engine, noting that it does not perform work as it is rigid, raising questions about how it maintains isothermal heat transfer. Additionally, the steam produced by the boiler is essential for the cycle, as it is used to perform work in subsequent processes. Understanding these principles is crucial for analyzing the efficiency and operation of Carnot cycles in thermodynamic systems.
Red_CCF
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Hi

From http://en.wikipedia.org/wiki/Carnot_cycle

"Reversible isothermal expansion of the gas at the "hot" temperature, TH (isothermal heat addition). During this step the expanding gas makes the piston work on the surroundings. The gas expansion is propelled by absorption of quantity Q1 of heat from the high temperature reservoir."

I was wondering why the work done on the surroundings at this stage does not count toward the total work output of the cycle and why it is not used?

Thanks
 
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It does.

In fact, from the first law of thermodynamics, you can make Heat = Work + Delta U, though as it is a cycle and U is a state variable, Delta U in the cycle is null, so the heat transferred is equal to work.
 
Hobold said:
It does.

In fact, from the first law of thermodynamics, you can make Heat = Work + Delta U, though as it is a cycle and U is a state variable, Delta U in the cycle is null, so the heat transferred is equal to work.

Hi, thanks for the response

What about for a boiler? A boiler in a heat engine operating a Carnot cycle does not have a piston (it is rigid), in this case, although it is also responsible for Process 1-2 in a Carnot cycle it does no work right? Also, how does a rigid boiler maintain isothermal heat transfer?

Thanks
 
does the steam from the boiler go anywhere and do anything?
 
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