Recover energy from temperature

[rc4]

Magenta walls recover energy. If e is very thin, the energy needed to compress volumes is very small and come from pressure too. I need only to give Y*e and if e is near 0, I need to give 0. The efficiency  is 0.5 due to Y forces.  I imagine the velocity of compression of volumes very high compare to the speed of walls. Y forces compress volume too, it's not only X forces (it's very important, in the contrary this idea not works). Do you understand the idea ?

[MarkE]

You will have to drive this with an external temperature gradient or it will equalize itself and stop.

[rc4]

External temperature heating the gaz, because it lost temperature in one cycle

[MarkE]

RC4 it is not enough to just have some ambient temperature above absolute zero.  You need both a high temperature ("hot") reservoir and a low temperature ("cold") reservoir.  Then you can harvest some of the power in the thermal flux between the two.  Once you add the required "cold" reservoir, then your idea will essentially be a thermoacoustic engine.

[rc4]

This is idea is to recover energy from only one temperature not hot and cold. Look at left volumes when they are compress from X and Y forces. If Y forces don't compress I need to move for each volume the thickness of each volume but like Y decrease in the same time the tickness, I need to  move lower distance. Do you understand  ?
I added an image for show the reduction of thicness of each volume, more and more.