# Carnot Cycle

Red_CCF
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

Hobold
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.

Red_CCF
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

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