Recover energy from temperature

[rc4]

Yes, I need energy to compress but less I recover. And Energy come from temperature, but it's only a unique temperature not a difference in this system. We can discuss about the energy in/out. In theory I can recover energy from PdV but I lost energy give by the formula. Are you agree with the work to give (formula) ? Take the last image to think of the energy. Red surfaces don't move at the same velocity than walls, and the energy I give it's the energy for red walls. If velocity is lower, distance to move is lower and energy too.

[MarkE]

Yes, I need energy to compress but less I recover. And Energy come from temperature, but it's only a unique temperature not a difference in this system. We can discuss about the energy in/out. In theory I can recover energy from PdV but I lost energy give by the formula. Are you agree with the work to give (formula) ?

rc4 you are at odds with the second law of thermodynamics.  The second law requires that you have a temperature difference in order to do work.  If you have a single heat reservoir then you do not have a temperature difference and by the second law you cannot extract work.  This means two general possibilities exist:  1. You have found an exception to the second law, or 2. You are mistaken.

[rc4]

Maybe it's 1/

Please, look at work to give, if you compress walls only with X, I'm agree I need to give the same energy I gave (in theory). But if I use Y forces, the energy come from temperature too for compress, and this allow the system to move at lower distance to the right. Have you understand this principle ?

When gas compress volume, velocity decrease, like all walls must turn a round in one cycle, this would say at one moment some walls must increase its velocity, it's possible inside walls where there is 1 bar and when volume increase (recover energy area).

[PiCéd]

Mh, pressure is a no conservative force, here we have a system who not use pressure in permanence
E in joule with pression (P) in pascal is:
E=(0.5?)xPx(the 3 dimensions)²
P=N (in Newton)/m²
If a force of 1 Newton is permanently exerced to an object of 2 cm x 2cm x 2cm, an energy of:
E=(0.5?)x2500x(0.02x0.02x0.02)²=160 or 80 nanojoules
An energy of 80 nanojoules is used in each second if it is in permanence.
If the volume is 1.5 m x 0.04 m x 0.1 m and if the force (1N) is exerced on the surface of 1.5 x 0.04 it is:
E=(0.5?)x16.666666x(1.5x0.04x0.1)²=0.3 or 0.6 millijoules
if the same force is exerced on the surface of 0.04x0.1, it is:
E=(0.5?)x250x(1.5x0.04x0.1)²=4.5 or 9 millijoules
This is some exemples, we can make pressure in permanence without using a generator or something else but it seem to be hard to harverst this energy with something viable.

[PiCéd]

Ooops, I think I made an error, the volume is not in ²...

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Ah yes, that's it:
E=(0.5?)xPxV
V= volume
E=(0.5?)x2500x0.02x0.02x0.02=10 or 20 millijoules
E=(0.5?)x16.666666x1.5x0.04x0.1=50 or 100 millijoules
E=(0.5?)x250x1.5x0.04x0.1=0.75 or 1.5 joules